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  • 1.
    Abdollahi, Morteza
    et al.
    Faculty of Engineering, Urmia University, Iran.
    Bahrami, Ataallah
    Department of Mining Engineering, Faculty of Engineering – Urmia University, P.O. Box 57561/51818, Iran.
    Saleh Mirmohammadi, Mir
    School of Mining Engineering, University of Tehran, Iran.
    Kazemi, Fatemeh
    Faculty of Engineering – University of Kashan, Iran.
    Danesh, Abolfazl
    Complex of Copper Processing – Sungun, Headquarters Rd, Tabriz, East Azerbaijan Province, Iran.
    Ghorbani, Yousef
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    A process mineralogy approach to optimize molybdenite flotation in copper: molybdenum processing plants2020Inngår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 157, artikkel-id 106557Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Sungun copper-molybdenum operation in Iran uses a typical copper-molybdenum flowsheet to produce separate copper and molybdenum concentrates through flotation and regrinding of the rougher concentrates arising from the primary circuit. This site was used as a case study limited to the feed and products of the copper-molybdenum separation circuit, in which process mineralogy might improve the quality of the molybdenum concentrate thorough diagnostic analysis of key flowsheet streams. The undesirable presence of copper in the molybdenum concentrate was identified as a key focus for the investigation by process mineralogy, which has a history of successful process diagnosis. This is because it develops information on minerals, which is far more informative than chemical assays alone. Together with the assays, the mineralogical data inform the investigator of the type and quantity of minerals present, their state of liberation and textural associations, and metal recovery.

    A key finding was that the appearance of chalcopyrite in the molybdenum concentrate was due to the presence of a chalcopyrite-pyrite texture that avoided the chalcopyrite depression in the molybdenum circuit because of suitable pyrite flotation conditions. Recovery of liberated pyrite to this concentrate also diluted the molybdenum concentrate. The open-circuit format of the regrind circuit also contributed to the unnecessary production of ultrafine particles. This flaw expressed itself as ultrafine losses of molybdenite to the flotation tailings.

  • 2.
    Adolfsson, Daniel
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Cementitious properties of steelmaking slags2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The present study is directed towards the use of steelmaking slags as raw material for sulphoaluminate belite cement (SAB). Another important objective was to characterise the cementitious properties of phases in ladle furnace slag (LFS) specifically the calcium aluminates. Mayenite (C12A7) is considered one of the most important calcium aluminate in LFS, and since comparatively limited data on the kinetic properties of this phase are available, it was decided to study C12A7 more closely with regard to both particle size and temperature sensitivity. The behaviour of high-temperature reactions of tested SAB mixtures was investigated using thermogravimetric analysis coupled with a quadrupole mass spectrometer. Mineralogical observations were carried out with x-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results proved that steelmaking slags have the potential to work as raw material, since sulphoaluminate (C4A3 S ) along with polymorphs of dicalcium silicate (C2S) and ferrite phase (C4AF) were detected after firing at 1200ºC in an air atmosphere. The hydration properties of the specimens were analysed through conduction calorimetry, and compressive strength of specimens hydrated for 2 and 28 days. The compressive strength was in accordance with that suggested in the literature for slow hardening SAB cement. Both mixtures tested behaved the same with regard to heat development as well as the amount of ettringite (AFt) formed during the first 24 hours of the hydration. The formation of AFt was characterised with both differential scanning calorimeter (DSC) and XRD. The crystallographic distribution in LFS samples was quantified using Rietveldanalysis. Calorimetric studies were performed at 20, 25 and 30°C in order to calculate the activation energy of hydration and thereby to suggest a kinetic model for tested compositions within this temperature interval. In addition to heat of hydration, compressive strength tests were completed on mortar prisms of LFS, and LFS in a blend with ground granulated blast furnace slag (GGBFS) which hydrated for 2, 7 and 28 days. Both compositions reached acceptable early strengths, whereas, after 28 days hydration, the blend was superior to neat LFS. Related activation energy was according to the Avrami-Erofeev model determined to 58 kJ/mol for the LFS and 63 kJ/mol for the blend. Corresponding calorimetric studies at the same temperatures were performed on a fine and coarse size fraction (Fraction A and Fraction B) of a synthesised C12A7. The purity was confirmed by XRD, and the hydraulic behaviour was investigated in excess water with respect to the dissolution. The apparent activation energy was calculated to 33 and 79 kJ/mol, respectively, for Fractions A-B using the Avrami-Erofeev model. From the model, it was also concluded that the acceleration period can be ascribed to a phase-boundary controlled mechanism. The principal calcium aluminate hydrates obtained were C2AH8 and C2AH7.5, and it was further observed that C12A7 is accompanied by an anomalous setting behaviour much like monocalcium aluminate (CA), and that the decomposition of C2AH8 to C2AH7.5 develops more slowly with higher surface area, specifically at 20 and 30°C.

    Fulltekst (pdf)
    FULLTEXT02
  • 3.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt.
    New Trends in The Application of Carbon-Bearing Materials in Blast Furnace Iron-Making2018Inngår i: Minerals, E-ISSN 2075-163X, Vol. 8, nr 12, artikkel-id 561Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The iron and steel industry is still dependent on fossil coking coal. About 70% of the total steel production relies directly on fossil coal and coke inputs. Therefore, steel production contributes by ~7% of the global CO2 emission. The reduction of CO2 emission has been given highest priority by the iron- and steel-making sector due to the commitment of governments to mitigate CO2 emission according to Kyoto protocol. Utilization of auxiliary carbonaceous materials in the blast furnace and other iron-making technologies is one of the most efficient options to reduce the coke consumption and, consequently, the CO2 emission. The present review gives an insight of the trends in the applications of auxiliary carbon-bearing material in iron-making processes. Partial substitution of top charged coke by nut coke, lump charcoal, or carbon composite agglomerates were found to not only decrease the dependency on virgin fossil carbon, but also improve the blast furnace performance and increase the productivity. Partial or complete substitution of pulverized coal by waste plastics or renewable carbon-bearing materials like waste plastics or biomass help in mitigating the CO2 emission due to its high H2 content compared to fossil carbon. Injecting such reactive materials results in improved combustion and reduced coke consumption. Moreover, utilization of integrated steel plant fines and gases becomes necessary to achieve profitability to steel mill operation from both economic and environmental aspects. Recycling of such results in recovering the valuable components and thereby decrease the energy consumption and the need of landfills at the steel plants as well as reduce the consumption of virgin materials and reduce CO2 emission. On the other hand, developed technologies for iron-making rather than blast furnace opens a window and provide a good opportunity to utilize auxiliary carbon-bearing materials that are difficult to utilize in conventional blast furnace iron-making.

    Fulltekst (pdf)
    fulltext
  • 4.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Anton
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    El-Tawil, Asmaa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Lotfian, Samira
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Alternative Carbon Sources for Reduction2015Konferansepaper (Annet vitenskapelig)
  • 5.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Anton
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    El-Tawil, Asmaa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Lotfian, Samira
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Mousa, Elsayed
    Swerea MEFOS, Luleå.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Alternative Reducing Agents for Sustainable Blast Furnace Ironmaking2017Inngår i: ESTAD 2017, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Lowering of CO2 emission from the integrated steel industry as well as minimizing theneed for landfill are important challenges in the focus for the integrated steel industry. With thisaim collaborative research projects have been conducted and are on-going on the possible useof renewable reducing agents or such with high content of H2 as well as for enabling recyclingof 1in-plant fines so far not possible to use. Due to contents of undesired impurities the blastfurnace (BF) sludge has to be pre-treated in an appropriate way before carbon and iron oxidecan be valorized. In order to understand the impact of alternative reducing agents as injectedthrough the tuyeres or part of top charged agglomerates containing iron oxide, samples oftorrefied biomass, plastic and in-plant fines have been analyzed by means of thermogravimetricanalyzer coupled with a mass spectrometer (TGA-MS).The results proved that effective utilization of carbon bearing BF dust and sludge as analternate reducing agent could be realized and can be implemented into BF after adequateupgrading. Plastic materials and biomass based reductants decomposition is associated with therelease of volatiles. The main contents of these volatiles are CO, H2 and hydrocarbon which areall known for their reduction potential. Moreover, injection of such materials is expected toimprove process efficiency and sustain the gas permeability along the BF cohesive zone. Onthe other hand, top charging of these materials would improve the energy and materialefficiency in the BF due to their higher reactivity compared to conventional carbon.

  • 6.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Charlotte
    LKAB, Research & Development, 983 81 Malmberget, LKAB Research and Development.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of olivine fineness and thermal profile on oxidation-sintering of magnetite concentrate pellets2015Inngår i: AISTech 2015: Proceedings of the Iron & Steel Technology Conference : 4-7 May 2015, Cleveland, Ohio, U.S.A / [ed] Ronald E Ashburn, Warrendale, PA: Association for Iron & Steel Technology , 2015, s. 379-388Konferansepaper (Fagfellevurdert)
  • 7.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Helwan, P.O. Box 87, Cairo, Egypt.
    Kumar, T. K. Sandeep
    Luossavaara Kiirunavaara Aktiebolag LKAB, S-97128 Luleå, Sweden.
    Alatalo, Johanna
    Luossavaara Kiirunavaara Aktiebolag LKAB, S-97128 Luleå, Sweden; AFRY AF Poyry, SE-97234 Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of carbon concentration and carbon bonding type on the melting characteristics of hydrogen- reduced iron ore pellets2022Inngår i: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 21, s. 1760-1769Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuel-based reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today's operations. In addition to carbon being an alloying element in steel production, carbon addition controls the melting characteristics of the reduced iron. In the present study, the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content 2 wt%, the molten fraction is higher in the case of carburized samples, which is indicated by the amount of absorbed melting heat.

  • 8.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Department of Minerals Technology, Central Metallurgical Research and Development Institute.
    Morales-Estrella, Ricardo
    Instituto de Investigación en Metalurgia y Materiales, Universidad Michoacana de San Nicolás de Hidalgo.
    Viswanathan, Nurin
    Centre of Excellence in Steel Technology (CoEST), Indian Institute of Technology Bombay.
    Seetharaman, Seshadri
    Royal Institute of Technology (KTH), Stockholm.
    Gas-solid reaction route toward the production of intermetallics from their corresponding oxide mixtures2016Inngår i: Metals, ISSN 2075-4701, Vol. 6, nr 8, artikkel-id 190Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the “Reduction-Sintering” process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H2, CH4 and N2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures in single step.

    Fulltekst (pdf)
    fulltext
  • 9.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Mousa, E.A.
    Minerals Technology Division, Central Metallurgical Research and Development Institute, 87-Helwan, Cairo.
    Larsson, Mikael
    Process Integration Department, Swerea MEFOS.
    Viswanathan, Nurni
    Department of Metallurgical Engineering and Materials Science, Centre of Excellence in Steel Technology (CoEST), IIT Bombay.
    Recent Trends in Ironmaking Blast Furnace Technology to Mitigate CO2 Emissions: Top Charging Materials2016Inngår i: Ironmaking and Steelmaking Processes: Greenhouse Emissions, Control, and Reduction / [ed] Pasquale Cavaliere, Springer International Publishing , 2016, s. 101-124Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The iron- and steelmaking is the largest energy consuming in the industrial sectors. The high energy consumption is associated with emission of CO 2and other pollutants. The most common ironmaking process used in the world is the blast furnace which contributes around 70 % of the world’s steel production. Recently, blast furnace has undergone tremendous modifications and improvements to reduce the energy consumption and CO 2emissions. The modifications are being focused on two main approaches: (1) development of top charging materials and (2) injections of auxiliary fuels through blast furnace tuyeres. The present chapter will discuss the recent modifications and development in the top charging burden and how it could participate in minimizing the energy consumption and CO 2emissions for more efficient and sustainable iron and steel industry. The injection of auxiliaryfuels will be discussed in details in another chapter. The enhancement of burden material quality and its charging mode into the blast furnace has resulted in a smooth and efficient operation. Recently, the usage of nut coke in the modern blast furnace is accompanied by higher production and lower reducing agent rates. An efficient recycling of in-plant fines by its conversion into briquettes with proper mechanical strength is applied in some blast furnaces to exploit the iron- and carbon-rich residues. Nowadays, novel composite agglomerates consist of iron ores and alternative carbonaceous materials represent a new trend for low-carbon blast furnace with lower dependence on the conventional burden materials. The recent investigations demonstrated that the novel composites are able to reduce the thermal reserve zone temperature in the blast furnace and consequently enhance the carbon utilization through its higher reactivity compared to fossil fuels. The top charging of bioreducers and hydrogen-rich materials into the blast furnace is one of interesting innovations to mitigate the CO 2emissions. Although some of previous approaches are recently applied in the modern blast furnace, others are still under intensive discussions to enhance its implementations.

  • 10.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Nurni, Viswanathan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Isothermal reduction kinetics of self-reducing mixtures2017Inngår i: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 44, nr 1, s. 66-75Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Isothermal reduction of haematite carbon mixtures was investigated at temperatures 750–1100°C under inert atmosphere. Mass loss curves proved the stepwise reduction of haematite to metallic iron. The non-linear feature of haematite to magnetite reduction kinetics was observed and an activation energy of 209 kJ mol−1 was calculated. Irrespective of carbon-bearing material type, reduction rate of magnetite was linear. Activation energy values were calculated to be 293–418 kJ mol−1. Significant increase in the reduction kinetics in the last step (Wustite reduction) was observed and explained by the catalytic effect of freshly formed metallic iron. During the initial stages of wustite reduction, the activation energy values were calculated to be in the range of 251–335 kJ mol−1 for all carbon-bearing materials.

  • 11.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Development Inst itute, Helwan, Egypt .
    Persson, Amanda
    Swerea MEFOS AB, Luleå, Sweden.
    Sundqvist, Lena
    Swerea MEFOS AB, Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Energy Efficient Recycling of in-Plant Fines2014Inngår i: Proceedings of World Academy of Science, Engineering and Technology, ISSN 2010-376X, Vol. 8, nr 6, s. 485-491Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Numerous amounts of metallurgical dusts and sludge containing iron as well as some other valuable elements such as Zn, Pb and C are annually produced in the steelmaking industry. These alternative iron ore resources (fines) with unsatisfying physical and metallurgical properties are difficult to recycle. However, agglomerating these fines to be further used as a feed stock for existing iron and steelmaking processes is practiced successfully at several plants but for limited extent.

    In the present study, briquettes of integrated steelmaking industry waste materials (namely, BF-dust and sludge, BOF-dust and sludge) were used as feed stock to produce direct reduced iron (DRI). Physical and metallurgical properties of produced briquettes were investigated by means of TGA/DTA/QMS in combination with XRD. Swelling, softening and melting behavior were also studied using heating microscope.

  • 12.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Persson, Amanda
    Swerea MEFOS AB.
    Sundqvist, Lena
    Swerea MEFOS AB.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Utilization of Steelmaking Industry Waste Materials in Producing Direct Reduced Iron2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The depletion of coke reserves and the raised environmental concerns motivated researchers to work on alternative iron-making processes. Large amount of metallurgical dusts and sludge containing iron and C are produced in the steelmaking industry. These alternative iron ore resources (fines) with poor hydrophilicity are difficult to recycle. The idea of briquetting such wastes containing iron to be used as a feed stock for steelmaking industry is practiced successfully at several plants.In the present study, agglomerates of integrated steelmaking industry waste materials were used as feed stock to produce direct reduced iron (DRI). The reduction behavior of blends of different waste materials (namely, BF dust and sludge, BOF dust and sludge) were investigated thoroughly utilizing TGA/DTA/QMS in combination with XRD.

    Fulltekst (pdf)
    FULLTEXT01
  • 13.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Persson, Amanda
    Swerea MEFOS AB, Sweden.
    Sundqvist-Ökvist, Lena
    Swerea MEFOS AB, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere2015Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 55, nr 10, s. 2082-2089Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Large amount of dust and sludge recovered during cleaning of iron and steel making process gases are annually put on landfill or intermediate storage. These by-products have high contents of iron (Fe) and carbon (C) that potentially could be utilized in the steel industry. However, due to the presence of impuritycompounds as well as the unsuitable physical properties, these by-products cannot be recycled directly. The main objective of the present study is to investigate the possibilities to recover the valuable components Fe and C in these by-products and thereby decrease the need of landfills at the steel plants as well as reduce the consumption of virgin materials, including fossil coal, and reduce CO2 emissions. A recycling route has been investigated by means of laboratory trials and FactSage thermodynamic modeling. Four different blends of BF and BOF dusts and sludges are prepared in predetermined ratios. Reduction behavior of each blend is studied using TG/DTA/QMS and in-situ high temperature X-ray diffraction. High temperature physical properties like softening, swelling and melting are also investigated by means of heatingmicroscope. The obtained results indicate the feasibility of both minimizing the impurity elements as well as recovering of valuable components.

  • 14.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute (CMRDI).
    Semberg, Pär
    Luossavaara-Kiirunavara Aktiebolag (LKAB), Luleå.
    Andersson, Charlotte
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of added olivine on iron ore agglomerate during induration2018Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 58, nr 3, s. 446-452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Olivine is used extensively in iron-pellet production as an additive in LKAB blast furnace pellets, in order to improve the high temperature properties of the finished product during reduction. As the contribution of olivine into the process depends on the available surface area, the present study was designed to find out the effect of olivine and its fineness on the oxidation-sintering and subsequent dissociation of olivine in iron ore agglomerates. Agglomerates were exposed to different experimental conditions to study the effect of olivine on the behavior of magnetite and hematite at high temperatures. Olivine particles were found to react significantly only above 1 000°C. Porosity of the final product was found to depend largely on olivine fineness. The finer the olivine the lower the porosity of the final product. It is found also that irrespective of the starting iron oxide the ratio between hematite and spinel phase was the same after heating in air. Olivine fineness affects significantly the rate of hematite dissociation, the finer the olivine the higher the dissociation rate. Upon cooling the weight lost due to the dissociation was again regained

  • 15.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, P.O. Box 87, EG-114 21, Helwan, Egypt.
    Sideris, Dimitrios
    Luleå tekniska universitet.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Injection of H2-rich carbonaceous materials into the blast furnace: devolatilization, gasification and combustion characteristics and effect of increased H2–H2O on iron ore pellets reducibility2020Inngår i: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 9, nr 6, s. 16029-16037Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increasing the share of hydrogen in reduction of iron oxide in the blast furnace iron making will directly reduce the share of blast furnace greenhouse gas emissions. In the present study, injection of H2-rich biomass and plastic materials was studied in terms of its devolatilization, gasification and combustion characteristics. The released gases were identified using mass spectroscopy attached to a thermogravimetric analyzer and the corresponding kinetics parameters were estimated.

    The devolatilization was found to occur through two or more steps. The first step is always associated with the release of CO2, CO, H2, H2O and hydrocarbons while only CO and H2 were detected during the later steps. Combustion and gasification starting temperatures of char of H2-rich carbonaceous materials were lower than that of pulverized coal char by ≥ 100 °C. The estimated activation energies suggested that, under the present conditions, devolatilization, gasification and combustion were chemically controlled. Carbon reactivity of the char of the studied H2-rich carbonaceous materials were higher than that of pulverized coal. Moreover, increased H2–H2O content in the blast furnace gas, due to injected H2-rich carbonaceous materials, was found to improve the iron ore pellets reduction kinetics.

  • 16.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Helwan, P.O. Box 87, Cairo, Egypt.
    Sideris, Dimitrios
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Lennartsson, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Prasad, Pande Nishant
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. SWERIM, Box 812, 971 25 Luleå, Sweden.
    From, Lars-Erik
    SWERIM, Box 812, 971 25 Luleå, Sweden.
    Orre, Joel
    SWERIM, Box 812, 971 25 Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of the Ash from H2‐Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity2020Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 91, nr 11, artikkel-id 2000098Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The iron and steel industry is one of the most important sectors worldwide, and it has a great impact on the global economy; however, this sector is still highly dependent on fossil carbon. To decrease this dependency, approaches to partially replace the injected pulverized coal with secondary, highly reactive, renewable (biomass) and H2‐rich materials have been studied. The injection of such materials is expected to significantly decrease the emitted CO2 from blast furnaces. However, due to the different ash composition of these alternative materials (especially alkali and alkaline earth metals) compared to that of ordinary injected coal, these materials are expected to alter the raceway slag properties and affect the coke reactivity. In the present article, the effect of the ash from different hydrogen‐rich carbonaceous materials on the raceway slag physicochemical properties as well as coke reactivity is reported. The melting characteristics of the ash briquettes in contact with the coke and wettability of the melted ash on the coke surface are determined visually using an optical heating microscope. The effect of the ash on the coke reactivity is studied by means of thermogravimetry under a continuous flow of CO2.

  • 17.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Viswanathan, Nurni
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Composite Pellets – A Potential Raw Material for Iron-Making2014Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, nr 3, s. 293-306Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Coke constitutes the major portion of iron-making cost and its production causes severe environmental concerns. In addition, lower energy consumption, lower CO2 emission and waste recycling are driving the Iron and steel making industry to develop “coke free, zero waste or green processes”. In the present article, an overview of possible ways to recognize a reasonable improvement in iron and steel making industry is summarized. The present discussion is focusing on the following approaches: 1. Replacing expensive coke with relatively less expensive alternate fuels having carbon as well as significant amount of hydrogen such as coal, waste plastic and biomass materials.2. Producing agglomerates from cheaper raw materials (secondary resources) as well as improving their performance in BF.3.Making the process towards higher carbon utilization by shifting the wustite equilibrium towards lower CO/CO2 ratio by using high reactive coke or catalytic activated one.4.Recycling the unused CO in the top gas by removing CO2 from the gas stream.Much attention has been paid to carbon composite agglomerates (CCA) as a promising raw material for future iron making. Production, mechanical and chemical suitability, reduction behavior, etc. are being elaborated. In addition, other possible ways to utilize CCA in alternate iron-making process has been explored.

  • 18.
    Ahmed, Hesham
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Viswanathan, Nurni
    Department of Metallurgical Engineering and Materials Science, Centre of Excellence in Steel Technology (CoEST), IIT Bombay.
    Seetharaman, Seshadri
    Division of Materials Process Science, KTH-Royal Institute of Technology .
    Gas-Condensed Phase Reactions: A Novel Route to Synthesize Alloys and Intermetallics Involving Refractory Metals2016Inngår i: Materials Today: Proceedings, E-ISSN 2214-7853, Vol. 3, nr 9 Part B, s. 2951-2961Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reduction and simultaneous reduction-carburization of oxide mixtures to get intermetallics and composite materials may open up shorter process routes towards the end-user needs. The use of natural gas or hydrogen would be environment-friendly. With these aims, the corresponding kinetics were studied by thermogravimetry, gas chromatography as well as laser-flash method. It was found that, under identical conditions, the Arrhenius activation energy for the reduction is proportional to the thermodynamic stability of the compound reduced. Intermetallics could be synthesized successfully and the product was found to have nanograins. Also, Metallic coating on copper surfaces was successfully developed.

  • 19.
    Alakangas, Lena
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Sandström, Åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rosenkranz, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Martinsson, Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Hällström, Lina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Geovetenskap och miljöteknik.
    Project: Improve Resource Efficiency and Minimize Environmental Footprint2016Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

  • 20.
    Albertsson, Galina Jelkina
    et al.
    Department of Materials Science and Engineering, Royal Institute of Technology.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Teng, Lidong
    Department of Materials Science and Engineering, Royal Institute of Technology.
    Effect of the Heat Treatment on the Chromium Partition in Cr-Containing Industrial and Synthetic Slags2014Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, nr 10, s. 1418-1431Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the present work, the effects of the slag composition and heat-treatment conditions on the phase relationships in a number of Cr-containing industrial and synthetic slags were investigated with a view to control the precipitation of Cr-spinel in the slag phase. Gas/slag equilibrium technique was used for the chromium partition and the phase relationship study. The phase relationships in synthetic slags and industrial EAF slags supplied by Swedish steelmaking plants have been investigated experimentally in the temperature range of 1473–1873 K. The slags were re-melted, slow-cooled to, and soaked at targeted temperatures in controlled atmosphere. Two different heat-treatment sequences were used in the present experiments. The oxygen partial pressure () was maintained by a suitable mixture of CO and CO2 gases. Phases present and their compositions in the quenched slags were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The chromium content in the phases present was analyzed using wavelength-dispersive spectrometer (WDS). Chromium partition was found to depend on the heat-treatment temperature

  • 21.
    Albertsson, Galina Jelkina
    et al.
    Department of Materials Science and Engineering, Royal Institute of Technology, Division of Materials Process Science, Royal Institute of Technology (KTH).
    Teng, Lidong
    Division of Materials Process Science, Royal Institute of Technology (KTH).
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of basicity on chromium partition in CaO-MgO-SiO2-Cr 2O3 synthetic slag at 1873 K2014Inngår i: Mineral Processing and Extractive Metallurgy: Transactions of the Institutions of Mining and Metallurgy: Section C, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 123, nr 2, s. 116-122Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of the present work is to get an understanding of the phase relationships in the CaO-MgO-SiO2-Cr2O3 system with a view to control the precipitation of Cr-spinel in the slag phase. The equilibrium phases in CaO-MgO-SiO2-Cr2O3 slag system at 1873 K (1600°C) have been investigated experimentally and compared with the results from thermodynamic calculations. The Cr2O 3 and MgO contents in the slag were fixed at 6 and 8 wt-% respectively. The basicity (CaO/SiO2) of slag was varied in the range 1·0-2·0. A gas/slag equilibrium technique was adopted to synthesise the slag at a high temperature in air. The samples were heated to and soaked at 1873 K (1600°C) for 24 h in order to achieve the equilibrium state and subsequently quenched in water. The chromium distribution and phase compositions in the quenched slag were studied using scanning electron microscope wavelength dispersive spectroscopy and X-ray diffraction techniques. FactSage software was used for the phase equilibrium calculations. The experimental results obtained from the present work were compared with the calculation results from FactSage software. It was found that the spinel formation at 1873 K (1600°C) is favoured in the slag basicity range 1·0-1·4

  • 22.
    Albertsson, Galina
    et al.
    Division of Materials Process Science, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden.
    Teng, Lidong
    Division of Materials Process Science, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Seetharaman, Seshadri
    Division of Materials Process Science, Royal Institute of Technology (KTH), SE-100 44 Stockholm, Sweden.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effect of low oxygen partial pressure on the chromium partition in CaO–MgO–SiO2–Cr2O3–Al2O3 synthetic slag at elevated temperatures2013Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, nr 7, s. 670-679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of the present work is to get an understanding of the impact of Al2O3 addition on the phase relationships in the CaO–MgO–Al2O3–SiO2–Cr2O3 slags at low oxygen partial pressures ( = 10−4 Pa), with a view to control the precipitation of Cr-spinel in the slag. The equilibrium phases in CaO–MgO–Al2O3–SiO2–Cr2O3 slag system in the range on 1673–1873 K have been investigated. The compositions close to the industrial slag systems were chosen. The Cr2O3 content was fixed at 6 wt% and MgO at 8 wt%. Al2O3 contents in the slag were varied in the range of 3–12 wt%. The basicity (CaO/SiO2) of slag was set to 1.6. Gas/slag equilibrium technique was adopted. The samples were heated to 1873 K and soaked at this temperature for 24 h. The samples were then slow cooled to 1673 K and equilibrated for an additional 24 h. The oxygen partial pressure was kept at 10−4 Pa. A gas mixture of CO/CO2 was used to control the oxygen partial pressure. After the equilibration, the samples were quenched in water. The chromium distribution and phase compositions in the quenched slags were studied using SEM–WDS and XRD techniques. The results were compared with the phase equilibrium calculations obtained from FACTSAGE software and the samples equilibrated in air. The size of spinel crystals increased drastically after slow cooling followed by annealing compared to samples being quenched after soaking at 1873 K. It was also found that low oxygen partial pressure had a strong impact on chromium partition. The amount of spinel phase increases with increased Al2O3 content.

  • 23.
    Ali, Heba
    et al.
    Cent Met Res & Dev Inst CMRDI, Pyrometallurg Proc Ores Dept, Cairo, Egypt; Cent Met Res & Dev Inst CMRDI, Pyrometallurg Proc Ores Dept, PO Box 87, 1, El-felezat St El-Tebbin, Cairo, Helwan, Egypt.
    Elsadek, Mohamed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Cent Met Res & Dev Inst CMRDI, Pyrometallurg Proc Ores Dept, Cairo, Egypt.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Pyrometallurgical Processing of Ores Department, Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt.
    Investigation of transformations of low-grade manganese ore during the roasting process2023Inngår i: Mineral Processing and Extractive Metallurgy: Transactions of the Institute of Mining and Metallurgy, ISSN 2572-6641, E-ISSN 2572-665X, Vol. 132, nr 1, s. 62-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The transformations of low-grade manganese ore were investigated during roasting in the air at different temperatures up to 1200 degrees C. The transformations were followed up by XRD and TGA-DTA. Moreover, the morphology and magnetic properties were determined by SEM and VSM. It was observed that MnO2 transformed to the lower oxide Mn5O8 at 500 degrees C and then to bixbyite (Mn2O3) at 600 degrees C. Finally, the bixbyite decomposed to hausmannite (Mn3O4) at 800 degrees C. Increasing the roasting temperature to 900 degrees C induced a reaction between hematite and hausmannite and led to the formation of a small amount of solid solution of the ferrite spinel MnFe2O4. Further increase in temperature to 1000 degrees C led to the formation of a solid solution of braunite (Mn7SiO12) which decomposed to rhodonite (MnSiO3) at 1200 degrees C. The magnetic susceptibility of the original ore gradually increased with the roasting temperature, from 0.119 x 10(-3) at ambient temperature to a maximum value of 80 x 10(-3) at 1200 degrees C.

  • 24.
    Alidokht, Mehdi
    et al.
    Tabas Parvardeh Coal Company (TPCCO), Birjand, Iran.
    Yazdani, Samaneh
    Department of Electrical and Computer Engineering, Islamic Azad University, North Tehran Branch, Tehran, Iran.
    Hadavandi, Esmaeil
    Department of Industrial Engineering, Birjand University of Technology, Birjand, Iran.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Modeling metallurgical responses of coal tri-flo separators by a novel bnn: a “Conscious-lab” development2021Inngår i: International journal of coal science & technology, ISSN 2095-8293, Vol. 8, nr 6, s. 1436-1446Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tri-flo cyclone, as a dense-medium separation device, is one of the most typical environmentally friendly industrial techniques in the coal washery plants. Surprisingly, no detailed investigation has been conducted to explore the effectiveness of tri-flo cyclone operating parameters on their representative metallurgical responses (yield and recovery). To fill this gap, this work for the first time in the coal processing sector is going to introduce a type of advanced intelligent method (boosted-neural network “BNN”) which is able to linearly and nonlinearly assess multivariable correlations among all variables, rank them based on their effectiveness and model their produced responses. These assessments and modeling were considered a new concept called “Conscious Laboratory (CL)”. CL can markedly decrease the number of laboratory experiments, reduce cost, save time, remove scaling up risks, expand maintaining processes, and significantly improve our knowledge about the modeled system. In this study, a robust monitoring database from the Tabas coal plant was prepared to cover various conditions for building a CL for coal tri-flo separators. Well-known machine learning methods, random forest, and support vector regression were developed to validate BNN outcomes. The comparisons indicated the accuracy and strength of BNN over the examined traditional modeling methods. In a sentence, generating a novel BNN within the CL concept can apply in various energy and coal processing areas, fill gaps in our knowledge about possible interactions, and open a new window for plants’ fully automotive process.

  • 25.
    Andersson, Anton
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Recycling of Blast Furnace Sludge within the Integrated Steel Plant: Potential for Complete Recycling and Influence on Operation2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Ore-based steelmaking generates various residues including dust, sludges, scales and slags. Internal and external recycling has allowed for 68-90 % of the dust, sludges and scales to be recycled. However, several residues are landfilled despite containing elements valuable as raw material in the production of steel. One such residue is the blast furnace (BF) sludge which has a chemical composition dominated by iron and carbon. In 2008, the annual worldwide landfilling of BF sludge was estimated to 8 million metric tons in dry weight. Furthermore, as the iron production via the BF route has increased significantly since 2008, the landfilling of BF sludge could be even higher as of today. Thus, the potential to reclaim valuable iron and carbon while improving the raw material efficiency is substantial.

    Traditionally, in-plant recycling of residues generated in the integrated steel plant is conducted via the sinter or, in the case of pellet-based BFs, via cold-bonded briquettes and injection in the BF tuyeres. The challenges in recycling BF sludge via these routes are the fine particle size distribution, the high water content and the zinc content. Of these challenges, the latter is the main concern as too high zinc loads in the BF lead to increased reductant rates, reduced lining life of carbon-based bricks and scaffold formation, which may disturb the process. The challenge regarding zinc has previously been addressed by pretreating the sludge, generating a low-zinc and high-zinc fraction where the former has been recycled to the BF via the sinter or cold-bonded pellets. Although pretreatment and recycling of the low-zinc fraction have been achieved in industrial scale, the reported sludges are generally coarse in size and high in zinc. Furthermore, recycling of pretreated BF sludge to the BF utilizing cold-bonded briquettes has not been reported and the internal recycling of the high-zinc fraction has not been considered.

    In the present thesis, newly produced BF sludge with a fine particle size distribution and low zinc content was characterized finding that a majority of the zinc was present in weak acid soluble phases and that the finest fraction of the sludge carried most of the zinc. Based on these findings, the BF sludge was pretreated using sulfuric acid leaching, hydrocycloning and tornado treatment, respectively. Sulfuric acid leaching was the most effective method in selectively separating zinc from the iron, carbon and solids. However, both hydrocycloning and tornado treatment were successful in generating a fraction low in zinc.

    The low-zinc fraction of the tornado-treated BF sludge was incorporated in cold-bonded briquettes and tested for strength, swelling and intrinsic reducibility. Furthermore, the briquettes were charged as basket samples in the LKAB Experimental Blast Furnace (EBF) in order to study the behavior in actual BF conditions. The results suggested that the low-zinc fraction of the BF sludge could be added to the briquettes without negatively affecting the performance of the briquettes in the BF. The results were confirmed in industrial-scale trials where non-treated BF sludge was added to cold-bonded briquettes in an amount that would facilitate complete recycling of the low-zinc fraction. Charging these briquettes to the BF did not induce any negative effects on the process or the hot metal (HM) quality.

    The high-zinc fraction of the tornado-treated BF sludge was added in self-reducing cold-bonded agglomerates and studied in technical-scale smelting reduction experiments aiming at recycling to the HM desulfurization plant. The experiments suggested that melt-in problems could be expected when using either briquettes or pellets. Nonetheless, industrial-scale trials were performed aiming to study the feasibility of recycling cold-bonded briquettes to both the HM desulfurization plant and basic oxygen furnace (BOF). These trials suggested that a substantial amount could be recycled without affecting the final quality of the steel. However, additional experiments were identified to be required in order to enable 100 % recycling of the high-zinc fraction of the tornado-treated BF sludge.

    Based on the results from the experimental work, a holistic concept to completely recycle the BF sludge within the integrated steel plant was suggested.

    Fulltekst (pdf)
    fulltext
  • 26.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, P.O. Box 87-Helwan, Cairo, Egypt.
    Rosenkranz, Jan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Characterization and Upgrading of a Low Zinc-Containing and Fine Blast Furnace Sludge: A Multi-Objective Analysis2017Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 57, nr 2, s. 262-271Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore-based steelmaking generates a variety of residues including dusts, sludges and slags. Recycling of these residues within the process or via other applications is essential for sustainable production from both environmental and economic aspects. In blast furnace (BF) ironmaking, there are generally two residues leaving the gas cleaning equipment; namely, BF dust and BF sludge. Traditionally, the dust is recycled via the sinter or, in the case of pellet based BF, via cold bonded agglomerates and injection. As the main output of zinc from the BF is the top gas, the sludge has to be dezinced prior to recycling to prevent accumulation of zinc in the furnace. Although dezincing of BF sludge has been successfully accomplished using e.g., hydrocycloning, the studied sludges are generally coarse sized and high in zinc. Furthermore, information is lacking regarding the efficiency of separation of different hydrocyclone setups. In the present work, hydrocycloning of a fine sludge, with low zinc content, generated by a pellet based BF has been studied. The gas cleaning equipment used to produce the sludge was running a primary aerocyclone and a scrubber. A characterization of the sludge has been conducted together with an evaluation of the separation efficiency of the hydrocyclone in order to assess the hydrocyclone performance and limitations. Furthermore, the dezincing using the hydrocyclone has been compared to that of sulfuric acid leaching. The results suggest that 51 to 93% of the sludge can be recycled depending on the demand on zinc removal and the chosen dezincing route.

  • 27.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Characterization and Upgrading of Ore Based Steelmaking Sludges2015Inngår i: COM 2015: Conference of Metallurgists, 2015Konferansepaper (Annet vitenskapelig)
  • 28.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Characterization of Blast Furnace Sludge and Upgrading Using Physical Separation and Leaching2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The on-site sinter plants of the Swedish ore based steel industry are all closed. Instead of using sinter, the blast furnaces (BF) operate on iron ore pellets and the major part of the recycling of in-plant residues is realized via cold bonded briquettes charged to the BF. Cost of raw materials and energy continuously drives the work towards an increased recycling of in plant residues. The major part of the zinc entering the BF leaves through the top gas ending up in the BF dust and sludge. The recycling of all the BF dust back to the BF leaves the BF sludge as the main bleed of zinc out of the system. In order to utilize the iron and carbon content of the sludge, means to remove zinc is required prior to recycling via the briquette. In the present work, blast furnace sludge has been characterized. Using the characterization as standpoint, different operations for zinc removal was suggested and studied in laboratory scale. Zinc was successfully removed using a hydrometallurgical and physical separation route, respectively. A successful dezincing operation would enable the recycling of the sludge. This would improve the material- and energy efficiency and substantially decrease the amount of sludge being landfilled.

  • 29.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Feasible routes of blast furnace sludge upgrading in the light of its properties2016Inngår i: SCANMET V: 5th International Conference on Process Development in Iron and Steelmaking, Luleå, 12-15 June 2016, 2016Konferansepaper (Annet vitenskapelig)
  • 30.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, P.O. Box 87, 114 21 Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Evaluation of evaporation kinetics of potassium from synthetic blast furnace slag using full factorial design of experiments2021Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the present work, a full factorial design of experiments with three factors was performed studying the evaporation of potassium (K) from synthetic blast furnace (BF) slag. The experiments showed that slag temperature and B2 basicity (%CaO/%SiO2) had the greatest effect on the evaporation kinetics, while the effect of the MgO content was comparatively less. The regression model developed based on the experimental design could describe the evaporation of K from actual BF slags fairly well, provided that they were within the experimental matrix of the design of experiments.

  • 31.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, P.O. Box 87, 114 21, Helwan, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerim AB, Box 812, 971 25, Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    The Quantitative Effect of Blast Furnace Slag Composition and Temperature on the Kinetics of Potassium Evaporation2020Inngår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 51, nr 6, s. 2711-2723Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Increased in-plant recycling and lower quality raw material in terms of alkali content drive the alkali load in the blast furnace (BF) to higher levels. Excessive load of alkalis, primarily potassium, has several negative effects on the BF operation, which necessitates means to control the removal of potassium from the BF. One method to improve the removal is by increasing the potassium retention in the slag, which is controlled by the evaporation kinetics of potassium. Although several authors have studied factors affecting the evaporation rate, none of these studies have quantitatively investigated the effect of these parameters and attempted to relate these effects to slags from the industry. In the present work, a full-factorial design of experiments with three factors (B2 basicity, MgO content, and temperature) was performed, studying the evaporation of potassium from synthetic BF slag. The results suggested that multiple linear regression is suitable to describe the evaporation kinetics of potassium within the boundaries of the design of experiments. However, extrapolating to industrial slags of different compositions and additional slag components is best performed utilizing the corrected optical basicity. The corrected optical basicity showed a linear relation to the evaporation kinetics of potassium, which was related to the correlation between diffusivity and corrected optical basicity.

  • 32.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Mats
    SSAB Europe.
    Kullerstedt, Adeline
    Swerim AB.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Recycling of the High-Zinc Fraction of Upgraded BF Sludge within the Integrated Steel Plant2018Konferansepaper (Fagfellevurdert)
  • 33.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Mats
    SSAB Europe.
    Kullerstedt, Adeline
    Swerim AB.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist-Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    RECYCLING OF THE HIGH-ZINC FRACTION OF UPGRADED BF SLUDGE WITHIN THE INTEGRATED STEEL PLANT2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Ore-based steelmaking generates a variety of residues and recycling of these within the existing process or via other applications is essential for sustainable production from mainly  environmental aspects. In blast furnace (BF) ironmaking, the gas-cleaning equipment recovers the particles in the off-gas as BF dust and sludge. Traditionally, the dry dust is recycled back to the BF. In order to recycle the BF sludge together with the dust, the sludge has to be upgraded, removing zinc. The literature reports cases of recycling BF dust and the low-zinc fraction of upgraded BF sludge to the BF. However, research towards recycling of the high-zinc fraction of BF sludge within the ore-based steel plant is limited. In the present paper, the high-zinc fraction of tornado-treated BF sludge was incorporated in self-reducing cold-bonded agglomerates. The agglomerates were subjected to smelting reduction experiments aiming to study the feasibility of recycling the in-plant residues to the desulphurization plant. Difficulties in the melt-in of the agglomerates suggested that cold-bonded pellets were more suitable for recycling than the briquettes. However, full-scale trials suggested that cold-bonded briquettes can be used to recycle in-plant residues to the desulphurization plant without affecting the desulphurization process and final steel quality.

  • 34.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Andersson, Mats
    SSAB Europe, Luleå.
    Mousa, Elsayed
    Swerim AB, Luleå, Sweden; Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Kullerstedt, Adeline
    Swerim AB, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerim AB, Luleå, Sweden.
    The Potential of Recycling the High-Zinc Fraction of Upgraded BF Sludge to the Desulfurization Plant and Basic Oxygen Furnace2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 12, artikkel-id 1057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In ore-based steelmaking, blast furnace (BF) dust is generally recycled to the BF via the sinter or cold-bonded briquettes and injection. In order to recycle the BF sludge to the BF, the sludge has to be upgraded, removing zinc. The literature reports cases of recycling the low-zinc fraction of upgraded BF sludge to the BF. However, research towards recycling of the high-zinc fraction of BF sludge within the ore-based steel plant is limited. In the present paper, the high-zinc fraction of tornado-treated BF sludge was incorporated in self-reducing cold-bonded briquettes and pellets. Each type of agglomerate was individually subjected to technical-scale smelting reduction experiments aiming to study the feasibility of recycling in-plant residues to the hot metal (HM) desulfurization (deS) plant. The endothermic reactions within the briquettes decreased the heating and reduction rate leaving the briquettes unreduced and unmelted. The pellets were completely reduced within eight minutes of contact with HM but still showed melt-in problems. Cold-bonded briquettes, without BF sludge, were charged in industrial-scale trials to study the recycling potential to the HM deS plant and basic oxygen furnace (BOF). The trials illustrated a potential for the complete recycling of the high-zinc fraction of BF sludge. However, further studies were identified to be required to verify these results.

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  • 35.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Brander, Linus
    Division of Built Environment—Infrastructure and Concrete, Research Institute of Sweden, SE-501 15 Borås, Sweden.
    Lennartsson, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Roos, Ake
    Boliden AB, SE-101 20 Stockholm, Sweden.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    A Method for Synthesizing Iron Silicate Slags to Evaluate Their Performance as Supplementary Cementitious Materials2023Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 13, nr 14, artikkel-id 8357Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R-3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags.

    Fulltekst (pdf)
    fulltext
  • 36.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Brander, Linus
    Research Institute of Sweden, Division of Built Environment – Infrastructure and Concrete, Box 857, SE-501 15 Borås, Sweden.
    Lennartsson, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Roos, Åke
    Boliden Smelters, Boliden AB, Klarabergsviadukten 90, SE-101 20, Stockholm, Sweden.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Ground granulated iron silicate slag as supplementary cementitious material: Effect of prolonged grinding and granulation temperature2023Inngår i: Cleaner Materials, E-ISSN 2772-3976, Vol. 10, artikkel-id 100209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The metallurgical and cement industries contribute significantly to anthropogenic carbon dioxide emissions. Utilizing oxidic by-products from the metallurgical industry as supplementary cementitious materials (SCMs) can improve resource efficiency and reduce emissions from cement production. Iron silicate copper slags have been studied as SCMs, but mainly in systems where Portland cement is used as an activator. There is limited research on the inherent reactivity of the slag under changing processing conditions. The present study offers insight into the effect of granulation temperature and grinding on the inherent reactivity of an industrially produced iron silicate copper slag. The results showed that granulation temperature had an insignificant effect on reactivity, while grinding generated substantial improvements. The latter effect was concluded to stem from the increased specific surface area, increased number of sites for nucleation and growth of hydrates, and changes in the inherent reactivity owing to structural changes induced by the grinding.

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    fulltext
  • 37.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Brander, Linus
    Research Institute of Sweden, 501 15 Borås, Sweden.
    Lennartsson, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Roos, Åke
    Boliden AB, 101 20 Stockholm, Sweden.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Performance of Ground Granulated Iron Silicate Slag as a Supplementary Cementitious Material: The Effect of Granulation Temperature and Grinding2023Inngår i: Proceedings of the 62nd Conference of Metallurgists, COM 2023 / [ed] Metallurgy and Materials Society of the Canadian Institute of Mining Metallurgy and Petroleum (CIM), Westmount, Canada, 2023Konferansepaper (Fagfellevurdert)
  • 38.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerea MEFOS, Luleå, Sweden.
    Kullerstedt, Adeline
    Swerea MEFOS, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerea MEFOS, Luleå, Sweden.
    Samuelsson, Caisa
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes2019Inngår i: Journal of Sustainable Metallurgy, ISSN 2199-3823, nr 3, s. 350-361Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Depending on the operation of the blast furnace (BF), the main outlet of zinc from the furnace is more or less via the BF dust and sludge. As the dust is recycled to the BF, the sludge has to be de-zinced prior to recycling to prevent the accumulation of zinc in the BF. De-zincing and recycling of the low-zinc fraction via sinter have been reported. However, no research con-cerning recycling of upgraded BF sludge via cold-bonded briquettes has been performed. In the present study, a fine-grained BF sludge with low zinc content, generated by a BF operating on a ferrous burden of 100% pellets, was upgraded using the tornado process. The process simultaneously dried and separated the BF sludge into a high-zinc and a low-zinc fraction. The feasibility of recycling the low-zinc fraction to the BF using cold-bonded briquettes was studied on a laboratory-scale BF shaft simulator. On comparison with a reference briquette, the experiments indicated that 10 wt% of the upgraded BF sludge can be added to the briquette without negatively affecting the reducibility. Higher additions were found to render the briquette less reduced compared to the reference under test conditions corresponding to the central part of the BF. The strength of the briquettes was not compromised with the addition of the upgraded BF sludge, and a decision to study the briquettes in the LKAB experimental blast furnace was made in order to evaluate the behavior under actual BF conditions.

  • 39.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerea MEFOS, Luleå, Sweden.
    Kullerstedt, Adeline
    Swerea MEFOS, Luleå, Sweden.
    Sandberg, Erik
    Swerea MEFOS, Luleå, Sweden.
    Andersson, Mats
    SSAB Europe, Luleå, Sweden.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Swerea MEFOS, Luleå, Sweden.
    Björkman, Bo
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    A Holistic and Experimentally-Based View on Recycling of Off-Gas Dust within the Integrated Steel Plant2018Inngår i: Metals, ISSN 2075-4701, Vol. 8, nr 10, artikkel-id 760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore-based ironmaking generates a variety of residues, including slags and fines such as dust and sludges. Recycling of these residues within the integrated steel plant or in other applications is essential from a raw-material efficiency perspective. The main recycling route of off-gas dust is to the blast furnace (BF) via sinter, cold-bonded briquettes and tuyere injection. However, solely relying on the BF for recycling implicates that certain residues cannot be recycled in order to avoid build-up of unwanted elements, such as zinc. By introducing a holistic view on recycling where recycling via other process routes, such as the desulfurization (deS) station and the basic oxygen furnace (BOF), landfilling can be avoided. In the present study, process integration analyses were utilized to determine the most efficient recycling routes for off-gas dust that are currently not recycled within the integrated steel plants of Sweden. The feasibility of recycling was studied in experiments conducted in laboratory, pilot, and full-scale trials in the BF, deS station, and BOF. The process integration analyses suggested that recycling to the BF should be maximized before considering the deS station and BOF. The experiments indicated that the amount of residue that are not recycled could be minimized.

  • 40.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Gullberg, Amanda
    Swerim AB.
    Kullerstedt, Adeline
    Swerim AB.
    Wedholm, Anita
    SSAB Merox AB.
    Wikström, Jenny
    LKAB.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Sundqvist Ökvist, Lena
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation2019Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 59, nr 10, s. 1786-1795Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ore-based steelmaking generates various residues including dusts, sludges, scales and slags. Recycling of these residues within the process or via other applications is essential for sustainable production of steel. In blast furnace (BF) ironmaking, the gas-cleaning equipment generally recovers the particles in the off-gas as dust and sludge. Traditionally, the dry dust is recycled via the sinter or, in the case of pellet-based BF operation, via cold-bonded briquettes and injection. As the BF sludge mainly consists of iron and carbon, this residue is of interest to recycle together with the BF dust. However, depending on how the BF is operated, these two residues are more or less the major outlet of zinc from the furnace. Thus, to limit the recycled load of zinc, both materials cannot be recycled without dezincing the sludge prior to recycling. Dezincing and recycling of the low-zinc fraction of BF sludge via sinter have been reported whereas recycling via cold-bonded briquettes has not been performed. In the present study, cold-bonded briquettes containing the low-zinc fraction of dezinced BF sludge were charged as basket samples to the LKAB Experimental Blast Furnace (EBF). The excavated basket samples from the quenched EBF suggested that additions of up to 20 wt.% of upgraded BF sludge was feasible in terms of reducibility and strength. Based on these results, BF sludge were added to cold-bonded briquettes and charged in industrial-scale trials. The trials indicated that the annual generation of BF sludge, after dezincing, could be recycled to the BF.

  • 41.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Isaksson, Jenny
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Lennartsson, Andreas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Engström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Insights into the Valorization of Electric Arc Furnace Slags as Supplementary Cementitious Materials2023Inngår i: Journal of Sustainable Metallurgy, ISSN 2199-3823, Vol. 10, s. 96-109Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The transition to hydrogen-based reduction processes within the iron and steelmaking industry will generate new types of slag compositions that require valorization routes. Using slags as supplementary cementitious materials (SCMs) addresses the carbon dioxide emissions of the cement industry since the SCM requires neither calcination nor clinkering. Conventionally, ironmaking slags from the blast furnace (BF) are recycled as SCMs, i.e., ground granulated BF slag (GGBS). Ideally, future slags from electric arc furnaces (EAFs) operating on hydrogen-based direct reduced iron should be valorized analogously. Since the hydrogen-based process route is not yet realized in an industrial scale, the literature lacks data to support this valorization route, and additionally, literature on scrap-based EAF slags is scarce. Therefore, the present study aimed to offer insights into the utilization of ore-based EAF slags as SCMs based on an industrial slag sample from an EAF operating on hot briquetted iron. The slag was remelted, modified, and water-granulated in laboratory scale, and its performance as an SCM was compared to water-granulated ladle slag and two commercial GGBS. The results showed promising reactivities measured using the R3 isothermal calorimeter-based testing protocol. Based on the comparison to GGBS, the study indicated that generating reactive and appropriate SCMs from EAF slags will partly be a challenge in balancing the crystallization of the MeO-type solid solution rich in magnesia and addressing the iron oxide content in the amorphous phase.

    Fulltekst (pdf)
    fulltext
  • 42.
    Andersson, Anton
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Morcel, Adeline
    Swerea MEFOS.
    Gullberg, Amanda
    Swerea MEFOS.
    Ahmed, Hesham
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. Central Metallurgical Research and Development Institute, Helwan.
    Upgrading and Recycling of Blast Furnace Sludge2017Konferansepaper (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 43.
    Andrade, Elaine Cristina
    et al.
    Department of Mining and Petroleum Engineering, Polytechnic School, University of São Paulo, Av. Professor Mello Moraes, 2373, CEP 05508-900, São Paulo, SP, Brazil.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    de Salles Leal Filho, Laurindo
    Department of Mining and Petroleum Engineering, Polytechnic School, University of São Paulo, Av. Professor Mello Moraes, 2373, CEP 05508-900, São Paulo, SP, Brazil.
    A systematic study on gelatinization efficiency of starch by NaOH for enhanced hematite depression2024Inngår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 209, artikkel-id 108621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Starch is a traditional depressant for hematite beneficiation by cationic reverse flotation separation from silicates. Alkali or thermal gelatinization must be used to prepare starch and promote its dissolution in water. In industry, gelatinization is typically carried out using sodium hydroxide at room temperature at different starch/NaOH mass ratios (SNMR). Surprisingly, no investigation has systematically studied the optimum SNMR for boosting hematite depression. This work examined the influence of starch gelatinization under various SNMR (3:1, 5:1, 7:1, and 9:1) on hematite depression (at pH = 10.5, 22 °C) by exploring flotation response (R), contact angle (θ), induction time (τ), hydrodynamic diameter (dH) of starch macromolecules, total energy of interaction starch/hematite (GTOT), based on its two components: the attractive Lifshitz-van der Waals energy (GLW) and attractive/repulsive electrostatic energy (GEL). Flotation test results indicated that SNMR = 5:1 promoted the lowest hematite recovery (14.8 %), coupled with the highest induction time (τ = 55 ms) and the lowest contact angle (θ = 11°). The hydrodynamic diameter (dH) of macromolecules in solutions prepared under different SNMR was determined by Dynamic Light Scattering, showing three peaks: amylopectin (350 < dH < 420 nm), amylose (50 < dH < 100 nm) and debris from gelatinization (dH ∼ 5000 nm). Since the latter only occurred in solutions prepared under SNMR of 7:1 and 9:1, deficient hematite depression might be caused by incomplete gelatinization. As amylopectin is the starch component that is responsible for its depressant ability, larger amylopectin macromolecules (dH = 411 nm) found in solutions prepared at SNMR = 5:1 contrast with smaller macromolecules (dH = 353 nm) produced at SNMR = 3:1. Considering starch macromolecules as a sphere, and hematite&apos;s surface as a plane; GLW, GEL, and GTOT were calculated in function of the sphere/plane separation distance (2 nm < H < 20 nm). GLW was determined based on the assessment of the Hamaker constant of the starch/water/hematite system (2.9 × 10−20J < A132 < 3.3 × 10−20J), whereas GEL was determined based on the zeta potential of starch (−2mV < ζ1 < −4mV) and hematite (ζ2 = −29 mV). GTOT for starch gelatinized at SNMR = 5:1 (−502.9 × 10−21 J) is greater than GTOT for starch prepared at SNMR = 3:1 (−468.8 × 10−21 J) and SNMR = 7:1 (−469.0 × 10−21 J), at a confidence level of 95 %. These results corroborate the more intensive hematite depression by starch prepared at SNMR = 5:1 compared to the other values explored by this study.

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  • 44.
    Asimi, Ali
    et al.
    Department of Mining and Metallurgical Engineering Yazd University, Yazd 89195-741, Iran. Bafgh Zinc Smelting Company (BZSC), Yazd 89195-741, Iran .
    Gharibi, Khodakaram
    Department of Mining and Metallurgical Engineering Yazd University, Yazd 89195-741, Iran.
    Abkhoshk, Emad
    Bafgh Zinc Smelting Company (BZSC), Yazd 89195-741, Iran.
    Moosakazemi, Farhad
    Chemical Engineering Department, Laval University, Québec, QC G1V 0A6, Canada. Beneficiation and Hydrometallurgy Research Group, Mineral Processing Research Center, Academic Center for Education, Culture and Research (ACECR) on TMU, Tehran 15119-43943, Iran.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Effects of Operational Parameters on the Low Contaminant Jarosite Precipitation Process-an Industrial Scale Study2020Inngår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 13, nr 20, artikkel-id 4662Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Jarosite precipitation process (JPP) is the most frequently used procedure for iron removal in the hydrometallurgical zinc extraction process. However, there is a gap in the knowledge of the relationship between operational parameters and the low contaminant JPP on the industrial scale. This study will address these issues by investigating the behavior of zinc calcine (ZC) as a neutralizing agent, exploring the source of zinc and iron through leaching experiments, and simulating the Jarosite process of the Bafgh Zinc Smelting Company (BZSC). The results showed that the zinc dissolution efficiency was 90.3% at 90 °C, and 73% of the iron present in the calcine can be solubilized. The main outcome was the iron removal of about 85% by alkaline ions present in ZC without the addition of any precipitating agent. The second target was to evaluate the effect of operational parameters on jarosite precipitation. Results revealed that increasing the temperature to 90 °C and the stirring rate to 500 RPM as well as adjusting the ZC’s pH during the jarosite precipitation remarkably improved iron removal. Considering all these factors in the plant could improve Fe precipitation to around 80% on average.

  • 45.
    Asimi Neisiani, A.
    et al.
    Department of Mining and Metallurgical Engineering, Yazd University, Yazd 89195-741, Iran.
    Saneie, R.
    Department of Materials Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
    Mohammadzadeh, A.
    Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto M5S 3E5, Canada.
    Wonyen, D. G.
    Department of Material Science and Engineering (Mining and Mineral Processing Engineering), African University of Science and Technology, Abuja P.M.B 681, Nigeria.
    Chehreh Chelgani, Saeed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Polysaccharides-based pyrite depressants for green flotation separation: An overview2023Inngår i: International Journal of Mining Science and Technology, ISSN 2095-2686, Vol. 33, nr 10, s. 1229-1241Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Froth flotation is an essential processing technique for upgrading low-grade ores. Flotation separation would not be efficient without chemical surfactants (collectors, depressants, frothers, etc.). Depressants play a critical role in the selective separation of minerals in that they deactivate unfavorable mineral surfaces and hinder them from floating into the flotation concentration zone. Pyrite is the most common and challenging sulfide gangue, and its conventional depressants could be highly harmful to nature and humans. Therefore, using available, affordable, eco-friendly polymers to assist or replace hazardous reagents is mandatory for a green transition. Polysaccharide-based (starch, dextrin, carboxymethyl cellulose, guar gum, etc.) polymers are one of the most used biodegradable depressant groups for pyrite depression. Despite the satisfactory flotation results obtained using these eco-friendly depressants, several gaps still need to be addressed, specifically in investigating surface interactions, adsorption mechanisms, and parameters affecting their depression performance. As a unique approach, this review comprehensively discussed previously conducted studies on pyrite depression with polysaccharide-based reagents. Additionally, practical suggestions have been provided for future assessments and developments of polysaccharide-based depressants, which pave the way to green flotation. This robust review also explored the depression efficiency and various adsorption aspects of naturally derived depressants on the pyrite surface to create a possible universal trend for each biodegradable depressant derivative.

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    fulltext
  • 46.
    Asimi Neisiani, A.
    et al.
    Department of Mining and Metallurgical Engineering Yazd University, Yazd 89195-741, Iran.
    Saneie, R.
    Department of Materials Engineering, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
    Mohammadzadeh, A.
    School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran.
    Wonyen, D. G.
    Department of Material Science and Engineering (Mining and Mineral Processing Engineering), African University of Science and Technology Abuja, Nigeria.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Biodegradable hematite depressants for green flotation separation – An overview2023Inngår i: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 199, artikkel-id 108114Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Due to environmental issues and the restrictions imposed on mineral flotation separation, the use of biodegradable and environmentally friendly reagents has gained widespread international attention. So far, several investigations have been conducted regarding the eco-friendly flotation separation of iron oxide ores for moving toward sustainable development and cleaner production. Yet, no critical review is specified on the green and eco-friendly depression reagents through their reverse flotation beneficiation. Therefore, this study will comprehensively discuss the previously conducted works in this area and provides suggestions for future assessments and developments. This robust study explored various adsorption aspects of natural-based depressants (polysaccharide-, polyphenolic-, and lignosulfonate-based) on iron oxide minerals (mainly hematite) to create a possible universal trend for each biodegradable depressant derivative. The laboratory and industrial experiments indicated that these depressants (except lignosulfonate-based) could selectively depress hematite at alkaline pHs and enhance its reverse flotation separation from their gangue phases (especially silicates as the main gangue phases). Although these eco-friendly depressants showed promising metallurgical results, several gaps still need to be addressed, notably in surface analyses and their adsorption mechanisms.

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    fulltext
  • 47.
    Asimi Neisiani, Ali
    et al.
    Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran.
    Chehreh Chelgani, Saeed
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Biodegradable acids for pyrite depression and green flotation separation–an overview2023Inngår i: Critical reviews in biotechnology, ISSN 0738-8551, E-ISSN 1549-7801Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Exponential increasing demands for base metals have made meaningful processing of their quite low-grade (>1%) resources. Froth flotation is the most important physicochemical pretreatment technique for processing low-grade sulfide ores. In other words, flotation separation can effectively upgrade finely liberated base metal sulfides based on their surface properties. Various sulfide surface characters can be modified by flotation surfactants (collectors, activators, depressants, pH regulators, frothers, etc.). However, these reagents are mostly toxic. Therefore, using biodegradable flotation reagents would be essential for a green transition of ore treatment plants, while flotation circuits deal with massive volumes of water and materials. Pyrite, the most abundant sulfide mineral, is frequently associated with valuable minerals as a troublesome gangue. It causes severe technical and environmental difficulties. Thus, pyrite should be removed early in the beneficiation process to minimize its problematic issues. Recently, conventional inorganic pyrite depressants (such as cyanide, lime, and sulfur-oxy compounds) have been successfully assisted or even replaced with eco-friendly and green reagents (including polysaccharide-based substances and biodegradable acids). Yet, no comprehensive review is specified on the biodegradable acid depression reagents (such as tannic, lactic, humic acids, etc.) for pyrite removal through flotation separation. This study has comprehensively reviewed the previously conducted investigations in this area and provides suggestions for future assessments and developments. This robust review has systematically explored depression performance, various adsorption mechanisms, and aspects of these reagents on pyrite surfaces. Furthermore, factors affecting their efficiency were analyzed, and gaps within each area were highlighted.

    Fulltekst (pdf)
    fulltext
  • 48.
    Asimi Neisiani, Ali
    et al.
    Department of Mining and Metallurgical Engineering Yazd University, Yazd 8915818411, Iran; Bafgh Zinc Smelting Company (BZSC), Yazd 8915818411, Iran.
    Moosakazemi, Farhad
    Chemical Engineering Department, Laval University, Québec G1 V 0A6, Canada.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Technical and Economic Comparison between Sodium and Ammonium Agents in the Jarosite Precipitation Process─An Evaluation for Industrial Applications2023Inngår i: ACS Omega, E-ISSN 2470-1343, Vol. 8, nr 39, s. 35442-36613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron content can cause severe challenges through zinc production from zinc sulfide concentrate. The zinc industry extensively uses the jarosite precipitation process (JPP) to precipitate dissolved iron and remove it before transferring the solution to downstream stages. Precipitating agents (PAs) play an essential role in the JPP. However, surprisingly, no study compares the efficiency of various PAs on an industrial scale. As an innovative approach, this investigation compares the technical and economic aspects of using various sodium and ammonium compounds (hydroxides, carbonates, bicarbonates, sulfates, and bisulfates) as typical PAs for the JPP at the Bafgh Zinc Smelting Company (BZSC) plant. Experimental results revealed that ammonium hydroxide, with 90.85% iron removal efficiency, had the highest performance, and sodium bisulfate and ammonium bisulfate had the lowest efficiency (74.54 and 77.13%, respectively). However, since ammonium hydroxide is a corrosive PA, it is not a promising alternative to sodium sulfate (with both economic and safety issues). Based on technical and economic assessments, sodium carbonate (84.31% iron removal efficiency) showed the highest potential for an efficient JPP.

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    fulltext
  • 49.
    Ataide Salvador, Dandara
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Geometallurgical Variability Study of Spodumene Pegmatite Ores, Central Ostrobothnia - Finland2017Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This geometallurgical variability study was conducted for Keliber Oy definitive feasibility study. It includes the Syväjärvi, Länttä and Rapasaari lithium ore deposits located in Central Ostrobothnia – Finland. These deposits present different characteristics in terms of spodumene grade, grain size, alteration, and weathering.

    A geometallurgical approach was used to characterize the ore and learn about the variability within and between the deposits in terms of mineralogy and processing response. In the project design chosen, grinding and flotation tests were performed. In addition, chemical composition of spodumene, mineralogical and liberation studies were carried out by MLA and EDS analysis.

    Spodumene is the main Li mineral in the deposits and its characteristics and elemental composition differ between and within these deposits, affecting mineral processing behavior. Spodumene impurities content as FeO and MnO are the highest in Länttä and lowest in Rapasaari. With respect to the harmful elements, Mg is carried by amphiboles and micas and P by apatite and sicklerite.

    Grinding is mainly influenced by the spodumene grade of the ore. The total grinding time to reach the P80 target was similar for the average ores, around 30 minutes of two stage grinding. Pre-flotation removed more than 50% of the apatite with on average 4.6% losses of spodumene. A cleaning stage for the pre-flotation product is recommended to recover some of the spodumene losses.

    In spodumene flotation with rougher and seven cleaning stages, Syväjärvi average ore showed high recoveries (about 90%) to final concentrate, whereas Länttä and Rapasaari presented clearly lower recoveries, (about 70%). In addition, Länttä presented the lowest spodumene grade in the final concentrate (about 70%) and Rapasaari the highest (about 75%). The flotation process, in general, turned out to be efficient in terms of concentrate grade, achieving, in most of the cases, the targeted Li2O grade of 4.5%. Although, the geometallurgical test is based on flowsheet developed for Syväjärvi and it is quite expected that Länttä and Rapasaari samples show poorer performance. Therefore, flotation tests and process optimization should be done to improve the spodumene recovery of Länttä and Rapasaari deposits. Considering Syväjärvi samples, spodumene head grade and grain size had positive effects in flotation. In contrast, spodumene alteration had a negative effect. Länttä shows lower spodumene liberation with given grind which leads to lower recovery and grade in flotation. A combination of lower feed grade, locking association, P80 and secondary Li minerals may explain Rapasaari samples performance. The weathered Rapasaari sample showed a positive effect on spodumene recovery which is possibly due to the liberation of spodumene grains from feldspars and quartz. Controlled waste dilution on ore samples promoted lower spodumene recovery and lower final concentrate grades, proportional to the dilution ratio. The results indicate that flowsheet and processing conditions as P80 and collector dosage need to be optimized by the deposit and by the ore type. Nevertheless, the present study is a diagnostic test and the results cannot be directly correlated to full-scale process.

  • 50.
    Awe, Samuel Ayowole
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Khoshkhoo, Mohammad
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Kruger, Paul
    Boliden Mineral AB, SE-936 81 Boliden, Sweden.
    Sandström, Åke
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Modelling and process optimisation of antimony removal from a complex copper concentrate2012Inngår i: Transactions of Nonferrous Metals Society of China, ISSN 1003-6326, E-ISSN 2210-3384, Vol. 22, nr 3, s. 675-685Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The modelling and optimization for the alkaline sulphide leaching of a complex copper concentrate containing 1.69% Sb and 0.14% Sn were studied. Response surface methodology, in combination with central composite face-centred design (RSM-CCF), was used to optimise the operating parameters. The leaching temperature, sulphide ion concentration and solid concentration werechosen as the variables, and the response parameters were antimony and tin recovery, and the time required to achieve 90% Sb dissolution. It was confirmed that the leaching process was strongly dependent on the reaction temperature as well as the sulphide ion concentration without any significant dependence on the solid concentration. Furthermore, a mathematical model was constructed tocharacterise the leaching behaviour. The results from the model allow identification of the most favourable leaching conditions. The model was validated experimentally, and the results show that the model is reliable and accurate in predicting the leaching process.

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