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  • 1.
    Ahmed, Hesham
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Andersson, Anton
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    El-Tawil, Asmaa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lotfian, Samira
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Mousa, Elsayed
    Swerea MEFOS, Luleå.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Alternative Reducing Agents for Sustainable Blast Furnace Ironmaking2017In: ESTAD 2017, 2017Conference paper (Refereed)
    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.

  • 2.
    Ahmed, Hesham
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Helwan, P.O. Box 87, Cairo, Egypt.
    Sideris, Dimitrios
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lennartsson, Andreas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Prasad, Pande Nishant
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. 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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Effect of the Ash from H2‐Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity2020In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 91, no 11, article id 2000098Article in journal (Refereed)
    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.

  • 3.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, P.O. Box 87, 114 21 Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Evaluation of evaporation kinetics of potassium from synthetic blast furnace slag using full factorial design of experiments2021Conference paper (Refereed)
    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.

  • 4.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, P.O. Box 87, 114 21, Helwan, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, 971 25, Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    The Quantitative Effect of Blast Furnace Slag Composition and Temperature on the Kinetics of Potassium Evaporation2020In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 51, no 6, p. 2711-2723Article in journal (Refereed)
    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.

  • 5.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Luleå, Sweden.
    The Potential of Recycling the High-Zinc Fraction of Upgraded BF Sludge to the Desulfurization Plant and Basic Oxygen Furnace2018In: Metals, ISSN 2075-4701, Vol. 8, no 12, article id 1057Article in journal (Refereed)
    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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  • 6.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Gullberg, Amanda
    Swerea MEFOS, Luleå, Sweden.
    Kullerstedt, Adeline
    Swerea MEFOS, Luleå, Sweden.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerea MEFOS, Luleå, Sweden.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes2019In: Journal of Sustainable Metallurgy, ISSN 2199-3823, no 3, p. 350-361Article in journal (Refereed)
    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.

  • 7.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    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 University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerea MEFOS, Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    A Holistic and Experimentally-Based View on Recycling of Off-Gas Dust within the Integrated Steel Plant2018In: Metals, ISSN 2075-4701, Vol. 8, no 10, article id 760Article in journal (Refereed)
    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.

  • 8.
    Andersson, Anton
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Gullberg, Amanda
    Swerim AB.
    Kullerstedt, Adeline
    Swerim AB.
    Wedholm, Anita
    SSAB Merox AB.
    Wikström, Jenny
    LKAB.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation2019In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 59, no 10, p. 1786-1795Article in journal (Refereed)
    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.

  • 9.
    Elsadek, Mohamed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Helwan, P.O. Box 87, Cairo, Egypt.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, Helwan, P.O. Box 87, Cairo, Egypt.
    Suup, Malin
    Boliden Mineral AB, SE-936 32, Boliden, Sweden.
    Sand, Anders
    Boliden Mineral AB, SE-936 32, Boliden, Sweden.
    Heikkinen, Eetu
    Process Metallurgy, University of Oulu, PO Box 4300, FI-90014 Oulu, Finland.
    Khoshkhoo, Mohammad
    Boliden Mineral AB, SE-936 32, Boliden, Sweden.
    Sundqvist-Öqvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Recycling of pyrite and gypsum mining residues through thermochemical conversion into valuable products2023In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 199, article id 107219Article in journal (Refereed)
  • 10.
    El-Tawil, Asmaa A.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ahmed, Hesham M.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, P.O Box 87, Helwan, Cairo 11421, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, 97125 Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis2019In: Metals, E-ISSN 2075-4701, Vol. 9, no 2, article id 168Article in journal (Refereed)
    Abstract [en]

    The interest of the steel industry in utilizing bio-coal (pre-treated biomass) as CO2-neutral carbon in iron-making is increasing due to the need to reduce fossil CO2 emission. In order to select a suitable bio-coal to be contained in agglomerates with iron oxide, the current study aims at investigating the thermal devolatilization of different bio-coals. A thermogravimetric analyzer (TGA) equipped with a quadrupole mass spectrometer (QMS) was used to monitor the weight loss and off-gases during non-isothermal tests with bio-coals having different contents of volatile matter. The samples were heated in an inert atmosphere to 1200 °C at three different heating rates: 5, 10, and 15 °C/min. H2, CO, and hydrocarbons that may contribute to the reduction of iron oxide if contained in the self-reducing composite were detected by QMS. To explore the devolatilization behavior for different materials, the thermogravimetric data were evaluated by using the Kissinger– Akahira–Sonuse (KAS) iso-conversional model. The activation energy was determined as a function of the conversion degree. Bio-coals with both low and high volatile content could produce reducing gases that can contribute to the reduction of iron oxide in bio-agglomerates and hot metal quality in the sustained blast furnace process. However, bio-coals containing significant amounts of CaO and K2O enhanced the devolatilization and released the volatiles at lower temperature. 

  • 11.
    El-Tawil, Asmaa A.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Ahmed, Hesham M.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Central Metallurgical Research and Development Institute, P.O Box 87, Helwan, 11421 Cairo, Egypt.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, 971 25 Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Self-Reduction Behavior of Bio-Coal Containing Iron Ore Composites2020In: Metals, E-ISSN 2075-4701, Vol. 10, no 1, article id 133Article in journal (Refereed)
    Abstract [en]

    The utilization of CO2 neutral carbon instead of fossil carbon is one way to mitigate CO2 emissions in the steel industry. Using reactive reducing agent, e.g., bio-coal (pre-treated biomass) in iron ore composites for the blast furnace can also enhance the self-reduction. The current study aims at investigating the self-reduction behavior of bio-coal containing iron ore composites under inert conditions and simulated blast furnace thermal profile. Composites with and without 10% bio-coal and sufficient amount of coke breeze to keep the C/O molar ratio equal to one were mixed and Portland cement was used as a binder. The self-reduction of composites was investigated by thermogravimetric analyses under inert atmosphere. To explore the reduction progress in each type of composite vertical tube furnace tests were conducted in nitrogen atmosphere up to temperatures selected based on thermogravimetric results. Bio-coal properties as fixed carbon, volatile matter content and ash composition influence the reduction of iron oxide. The reduction of the bio-coal containing composites begins at about 500 °C, a lower temperature compared to that for the composite with coke as only carbon source. The hematite was successfully reduced to metallic iron at 850 °C by using bio-coal, whereas with coke as a reducing agent temperature up to 1100 °C was required.

  • 12.
    El-Tawil, Asmaa A.
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lundgren, Maria
    Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Robles, Astrid
    Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Influence of Bio-Coal Properties on Carbonization and Bio-Coke Reactivity2021In: Metals, ISSN 2075-4701, Vol. 11, no 11, article id 1752Article in journal (Refereed)
    Abstract [en]

    Coke corresponds to 2/3–3/4 of the reducing agents in BF, and by the partial replacement of coking coals with 5–10% of bio-coal, the fossil CO2 emissions from the BF can be lowered by ~4–8%. Coking coal blends with 5% and 10% additions of bio-coals (pre-treated biomass) of different origins and pre-treatment degrees were carbonized at laboratory scale and with a 5% bio-coal addition at technical scale, aiming to understand the impact on the bio-coal properties (ash amount and composition, volatile matter content) and the addition of bio-coke reactivity. A thermogravimetric analyzer (TGA) connected to a quadrupole mass spectroscope monitored the residual mass and off-gases during carbonization. To explore the effect of bio-coal addition on plasticity, optical dilatometer tests were conducted for coking coal blends with 5% and 10% bio-coal addition. The plasticity was lowered with increasing bio-coal addition, but pyrolyzed biomass had a less negative effect on the plasticity compared to torrefied biomasses with a high content of oxygen. The temperature for starting the gasification of coke was in general lowered to a greater extent for bio-cokes produced from coking coal blends containing bio-coals with higher contents of catalyzing oxides. There was no significant difference in the properties of laboratory and technical scale produced coke, in terms of reactivity as measured by TGA. Bio-coke produced with 5% of high temperature torrefied pelletized biomass showed a similar coke strength as reference coke after reaction.

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  • 13.
    El-Tawil, Asmaa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lundgren, Maria
    Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Bäck, Frida
    SSAB EMEA AB, SSAB Special Steels Division, Aspaleden 2, 613 31 Oxelosund, Sweden.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Influence of Modified Bio-Coals on Carbonization and Bio-Coke Reactivity2021In: Metals, ISSN 2075-4701, Vol. 12, no 1, article id 61Article in journal (Refereed)
    Abstract [en]

    Substitution of coal in coking coal blend with bio-coal is a potential way to reduce fossil CO2 emissions from iron and steelmaking. The current study aims to explore possible means to counteract negative influence from bio-coal in cokemaking. Washing and kaolin coating of bio-coals were conducted to remove or bind part of the compounds in the bio-coal ash that catalyzes the gasification of coke with CO2. To further explore how the increase in coke reactivity is related to more reactive carbon in bio-coal or catalytic oxides in bio-coal ash, ash was produced from a corresponding amount of bio-coal and added to the coking coal blend for carbonization. The reaction behavior of coals and bio-coals under carbonization conditions was studied in a thermogravimetric analyzer equipped with a mass spectrometer during carbonization. The impact of the bio-coal addition on the fluidity of the coking coal blend was studied in optical dilatometer tests for coking coal blends with and without the addition of bio-coal or bio-coal ash. The result shows that the washing of bio-coal will result in lower or even negative dilatation. The washing of bio-coals containing a higher amount of catalytic components will reduce the negative effect on bio-coke reactivity, especially with acetic acid washing when the start of gasification temperature is less lowered. The addition of bio-coal coated with 5% kaolin do not significantly lower the dilatation-relative reference coking coal blend. The reactivity of bio-cokes containing bio-coal coated with kaolin-containing potassium oxide was higher in comparison to bio-coke containing the original bio-coal. The addition of ash from 5% of torrefied bio-coals has a moderate effect on lowering the start of gasification temperature, which indicates that the reactive carbon originating from bio-coal has a larger impact.

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  • 14.
    El-Tawil, Asmaa
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, Luleå, 97125, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lundgren, Maria
    Swerim AB, Box 812, Luleå, 97125, Sweden.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, Luleå, 97125, Sweden.
    The Effect of Bio-Coal Agglomeration and High-Fluidity Coking Coal on Bio-Coke Quality2023In: Metals, ISSN 2075-4701, Vol. 13, no 1, article id 175Article in journal (Refereed)
    Abstract [en]

    Metallurgical coke with high strength and low reactivity is used in the ironmaking blast furnace. Replacement of some coking coal with bio-coal was shown to result in lower strength and higher reactivity of produced coke due to introduction of reactive bio-coal carbon and ash components catalyzing the Boudouard reaction, but also due to lowering of the coking coal blend fluidity, which influences coke strength and reactivity negatively. The current study aims to investigate the possibility to counteract negative impact from bio-coal addition on fluidity and coke reactivity by using high-fluidity coking coal and by agglomeration of bio-coal before addition. Original bio-coal and micro-agglomerate of bio-coal was added at 10%, 15% and 20% to the coking coal blend. The influence of bio-coals on the coke reactivity was measured by using CO2 in a thermogravimetric analyzer. Selected cokes and bio-cokes were produced in technical scale, and their reactivity and strength were measured in standard tests. The effect on dilatation of adding bio-coal or crushed agglomerates of bio-coal to the coking coal blends was measured in an optical dilatometer. The results show that by using a coking coal blend containing high-fluidity coal with agglomerated bio-coal, the max. contraction is increased, whereas the opposite occurs by using original bio-coal. The results show overlapping between contraction occurring before dilatation and during dilation, which affects max. dilatation. The bio-coke containing high-fluidity coal with agglomerated bio-coal has lower reactivity in comparison to bio-cokes with original bio-coal or bio-coke with agglomerated bio-coal produced from a coking coal blend without high-fluidity coal. The reactivity of coke produced in technical scale, as measured in CRI/CSR tests, shows a similar trend regarding reactivity, as measured by thermogravimetric analysis, on coke produced in laboratory scale.

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  • 15.
    Hellgren, Simon
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction2024In: Metals, ISSN 2075-4701, Vol. 14, no 1, article id 73Article in journal (Refereed)
    Abstract [en]

    Super-hot acid leach residue is generated during zinc production in the roasting–leaching–electrowinning route, where both primary and secondary resources are used as feed material. This residue may contain valuable metals, such as lead, zinc, and iron, as well as precious metals, such as gold and silver. Four materials, namely super-hot acid leach residue, a residue formed when super-hot acid leach residue is selectively leached for lead with triethylenetetramine, as well as flotation concentrate, and flotation tailings formed in a selective silver flotation process with super-hot acid leach residue as the feed material were characterized to obtain a deeper understanding of possible further metal extraction. These four materials were characterized for chemical composition, mineralogy, and mineral distribution via chemical analyses, X-ray diffraction, and energy-dispersive scanning electron microscopy, respectively. The scanning electron microscope images showed that the materials have large variations in particle size distribution and composition. The results showed that the main lead phase in super-hot acid leach residue is lead sulfate, whereas it is mostly converted to lead sulfide during the selective lead leaching of the super-hot acid leach residue. The remaining lead sulfate is found in a solid solution with barium sulfate. Extracting lead from super-hot acid leach residue via triethylenetetramine leaching resulted in increased concentrations of gold and silver by 41% and 42%, respectively. The identified silver phases in super-hot acid leach residue may correspond to silver sulfide, silver chloride, and elementary silver, where silver sulfide was the most commonly occurring silver phase. After leaching this selectively for lead with triethylenetetramine, similar silver phases were identified, but silver sulfide and silver chloride occurred to a similar extent. Additionally, silver copper sulfide was detected. The presence of different silver phases might pose a challenge to reaching high silver recovery during leaching as the optimum leaching conditions differ somewhat. Furthermore, elemental sulfur, with a tendency to coat gold and silver particle surfaces, which is indicated to be present in all materials except the silver flotation tailings, may hinder metal extraction.

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  • 16.
    Hu, Xianfeng
    et al.
    Process Metallurgy Department, SWERIM AB, Luleå, Sweden.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB.
    Ölund, Martin
    Process Metallurgy Department, SWERIM AB, Luleå, Sweden.
    Materials Properties and Liquid Flow in the Hearth of the Experimental Blast Furnace2019In: Metals, E-ISSN 2075-4701, Vol. 9, no 5, article id 572Article in journal (Refereed)
    Abstract [en]

    The materials’ properties in the hearth of the blast furnace are very crucial for the hearthconditions. In this study, a number of coke, slag, metal, and aggregate samples were collected fromthe hearth of the LKAB’s experimental blast furnace (EBF). Subsequently, the coke, slag, and metalsamples were chemically analyzed by X-ray fluorescence (XRF) or optical emission spectrometer(OES); the aggregate samples were analyzed by scanning electron microscope combined withenergy-dispersive X-ray spectroscopy (SEM/EDS). The possible flow field of the liquid in the EBFhearth before quenching is depicted according to Cu tracers in the metal samples. Selected elementsin the coke, slag, and metal were mapped for two sampling layers in the hearth, as well as in one crosssection of the flow field. The results indicate that there exists an area beneath, and in front of, tuyere 3,where the flow resistance of the liquid was high. The high flow resistance contributed to the formationof a cold zone in the close-to-wall region and at the bottom of the EBF hearth. The temperaturedistribution in the EBF hearth has significant impacts on the chemical properties of the materials indierent positions of the EBF hearth, as well as on the radial and vertical distributions of certainelements/components.

  • 17.
    Hu, Xianfeng
    et al.
    Process Metallurgy Department, Swerea MEFOS.
    Sundqvist-Öqvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Eriksson, Johan
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Combined Chromium Reduction and Alloying of Steel2016In: Scanmet V, 2016Conference paper (Refereed)
  • 18.
    Hu, Xianfeng
    et al.
    Process Metallurgy Department, Swerea MEFOS AB.
    Sundqvist-Öqvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Process Metallurgy Department, Swerea MEFOS AB.
    Eriksson, Johan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Direct alloying steel with chromium by briquettes made from chromite ore, mill scale, and petroleum coke2017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 5, article id 1600247Article in journal (Refereed)
    Abstract [en]

    In this work, the effectiveness of using briquettes made from chromite ore, mill scale, and petroleum coke for direct chromium alloying is tested by induction furnace trials carried out in three different scales. The experimental results show that steel scrap can be alloyed with chromium by the chromite ore in the briquettes and the Cr yield from the chromite ore increases with the increase in mill scale addition to the briquettes: the more mill scale is added to the briquettes, the lower the mass ratio of Cr to (Cr+Fe) would be, leading to a higher Cr yield from the chromite ore. Specifically, the maximum Cr yield from the chromite ore is 99.9% when the mass ratio of Cr to (Cr+Fe) in the briquettes is 0.05, and being 93.0% when the ratio is 0.10. However, when the ratio of Cr to (Cr+Fe) in the briquettes reaches 0.20, the maximum Cr yield is only 67.1%. The reduction of chromite ore under the present experimental conditions is promoted by a solid-state reduction mechanism

  • 19.
    Hu, Xianfeng
    et al.
    Process Metallurgy Department, Swerea MEFOS AB, Sweden.
    Sundqvist-Öqvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Process Metallurgy Department, Swerea MEFOS AB, Sweden.
    Åström, Elin
    LKAB R&D.
    Forsberg, Fredrik
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics. LKAB R&D.
    Checchia, Paolo
    INFN Sezione di Padova, Padova, Italy.
    Bonomi, Germano
    Universita degli Studi di Brescia, Brescia, Italy.
    Calliari, I.
    Universita degli Studi di Padova, Padua, Italy.
    Calvini, Piero
    Universita degli Studi di Genova, Genoa, Italy.
    Donzella, Antonietta
    Universita degli Studi di Brescia, Department of Mechanical and Industrial Engineering, Brescia, Italy.
    Faraci, Eros
    Centro Sviluppo Materiali S.p.A., Roma, Italy.
    Gonella, Franco
    Istituto Nazionale Di Fisica Nucleare, Frascati, Frascati, Italy.
    Klinger, Joel
    Istituto Nazionale Di Fisica Nucleare, Frascati, Frascati, Italy.
    Pagano, Davide
    Universita degli Studi di Brescia, Brescia, Italy.
    Rigoni, Andrea
    Consorzio Rfx, Padua, Italy.
    Zanuttigh, Pietro
    Universita degli Studi di Padova, Padua, Italy.
    Ronchese, Paolo
    Universita degli Studi di Padova, Padua, Italy.
    Urbani, Michele
    Universita degli Studi di Padova, Department of Physics and Astronomy, Padua, Italy.
    Vanini, Sara
    Universita degli Studi di Padova, Department of Physics and Astronomy, Padua, Italy.
    Zenoni, Aldo
    Universita degli Studi di Brescia, Department of Mechanical and Industrial Engineering, Brescia, Italy.
    Zumerle, Gianni
    Universita degli Studi di Padova, Department of Physics and Astronomy, Padua, Italy.
    Exploring the capability of muon scattering tomography for imaging the components in the blast furnace2018In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 58, no 1, p. 35-42Article in journal (Refereed)
    Abstract [en]

    Knowing the distribution of the materials in the blast furnace (BF) is believed to be of great interest for BF operation and process optimization. In this paper calibration samples (ferrous pellets and coke) and samples from LKAB’s experimental blast furnace (probe samples, excavation samples and core-drilling samples) were measured by the muon scattering tomography detector to explore the capability of using the muon scattering tomography to image the components in the blast furnace. The experimental results show that it is possible to use this technique to discriminate the ferrous pellets from the coke and it is also shown that the measured linear scattering densities (LSD) linearly correlate with the bulk densities of the measured materials. By applying the Stovall’s model a correlation among the LSD values, the bulk densities and the components of the materials in the probe samples and excavation samples was established. The theoretical analysis indicates that it is potential to use the present muon scattering tomography technique to image the components in various zones of the blast furnace.

  • 20.
    Hu, Xianfeng
    et al.
    Process Metallurgy Department, Swerea MEFOS.
    Teng, Lidong
    Division of Materials Process Science, KTH-Royal Institute of Technology.
    Wang, Haijuan
    State Key Laboratory of Advanced Metallurgy, University of Science and Technology .
    Sundqvist-Öqvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Yang, Qixing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Seetharaman, Seshadri
    Division of Materials Process Science, KTH-Royal Institute of Technology .
    Carbothermic Reduction of Synthetic Chromite with/without the Addition of Iron Powder2016In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 56, no 12, p. 2147-2155Article in journal (Refereed)
    Abstract [en]

    Carbothermic reduction of chromite is an important industrial process for extracting chromium from the chromite. To have a better understanding of the effect of iron on the carbothermic reduction of chromite, the reduction of synthetic chromite (FeCr2O4) by graphite with/without the addition of iron powder was investigated in this paper by Thermogravimetric Analysis (TGA) in argon atmosphere. The fractional reduced samples were examined by SEM/EDS and XRD analysis, and the reduction process was thermodynamically and kinetically evaluated. The experimental results show that the iron powder addition enhances the reduction of FeCr2O4 and this effect increases when increased amounts of iron powder are added. This phenomenon is attributed to the in situ dissolution of chromium into the iron and mixed carbide (Cr,Fe)7C3, which can decrease the activity of the nascent chromium formed by the reduction of the FeCr2O4. The experimental results indicate that the reduction of FeCr2O4 with up to 80 wt.% iron powder addition is likely to be a single-step process and the kinetic analysis suggests that the reduction reaction is likely to be either (a) chemical reaction at the surface of FeCr2O4 or (b) diffusional dissolution of the product (FeCr2) into the iron/alloy particles or the mixed control of (a) and (b). 

  • 21.
    Mousa, Elsayed
    et al.
    Swerim AB, Luleå. Central Metallurgical Research and Development Institute, Cairo, Egypt.
    Lundgren, Maria
    Swerim AB, Luleå.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Luleå.
    From, Lars-Erik
    Swerim AB, Luleå.
    Robles, Astrid
    Swerim AB, Luleå.
    Hällsten, Siv
    SSAB Merox AB, Oxelösund.
    Sundelin, Bo
    SSAB EMEA AB, Oxelösund.
    Friberg, Hanna
    SSAB EMEA AB, Oxelösund.
    El-Tawil, Asmaa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Reduced Carbon Consumption and CO2 Emission at the Blast Furnace by Use of Briquettes Containing Torrefed Sawdust2019In: Journal of Sustainable Metallurgy, ISSN 2199-3823, Vol. 5, no 3, p. 391-401Article in journal (Refereed)
    Abstract [en]

    Lowering the carbon consumption and fossil CO2emissions is a priority in blast furnace (BF) ironmaking. Renewablebiomass is one option that can play an important role in future low-carbon ironmaking particularly in the countries rich inbiomass resources. In this study, full-scale trials to investigate the impact of briquettes containing torrefied sawdust on theBF efficiency and process stability have been conducted. Briquettes containing 1.8% of torrefied pelletized sawdust (TPS),86.2% of steel mill residues, and 12% cement with sufficient mechanical strength have been produced on industrial scale. Thebio-briquettes were charged at two different rates: 37% ( ~ 39 kg/tHM) and 55% ( ~ 64 kg/tHM) bio-briquettes to the SSABBF No. 4 in Oxelösund. The gas utilization was higher during bio-briquette-charging periods without change in pressuredrop up to 55% bio-briquettes, indicating sustained shaft permeability. BF dust generation or properties did not change significantly.Measurements of the top gas composition using mass spectrometry did not indicate release of hydrocarbon fromTPS in connection to the charging of bio-briquettes. Evaluation of process data has been carried out using a heat and massbalance model. The evaluation of operational data in the model indicated lowering of thermal reserve zone temperature by45 °C and reduction in carbon consumption by ~ 10 kg/tHM when charging 55% bio-briquettes compared to the referencecase. The total CO2emission was reduced by about 33–40 kg/tHM when using 55% bio-briquettes.

  • 22.
    Orre, Joel
    et al.
    Metallurgy Department, Swerim, 974 37 Luleå, Sweden.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Metallurgy Department, Swerim, 974 37 Luleå, Sweden.
    Bodén, Axel
    Relitor, 973 34 Luleå, Sweden.
    Björkman, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Understanding of Blast Furnace Performance with Biomass Introduction2021In: Minerals, E-ISSN 2075-163X, Vol. 11, no 2, article id 157Article in journal (Refereed)
    Abstract [en]

    The blast furnace still dominates the production and supply of metallic units for steelmaking. Coke and coal used in the blast furnace contribute substantially to CO2 emissions from the steel sector. Therefore, blast furnace operators are making great efforts to lower the fossil CO2 emissions and transition to fossil-free steelmaking. In previous studies the use of pre-treated biomass has been indicated to have great potential to significantly lower fossil CO2 emissions. Even negative CO2 emission can be achieved if biomass is used together with carbon capture and storage. Blast furnace conditions will change at substantial inputs of biomass but can be defined through model calculations when using a model calibrated with actual operational data to define the key blast furnace performance parameters. To understand the effect, the modelling results for different biomass cases are evaluated in detail and the overall performance is visualised in Rist- and carbon direct reduction rate (CDRR) diagrams. In this study injection of torrefied biomass or charcoal, top charging of charcoal as well as the use of a combination of both methods are evaluated in model calculations. It was found that significant impact on the blast furnace conditions by the injection of 142 kg/tHM of torrefied biomass could be counteracted by also top-charging 30 kg/tHM of charcoal. With combined use of the latter methods, CO2-emissions can be potentially reduced by up to 34% with moderate change in blast furnace conditions and limited investments.

  • 23.
    Sar, Suchandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Experimental Study on the Dissolution Behavior of Calcium Fluoride2020In: Metals, ISSN 2075-4701, Vol. 10, no 8, article id 988Article in journal (Refereed)
    Abstract [en]

    The presence of halogens has an adverse effect on the zinc extraction process through electrowinning, the last phase of the RLE (Roasting, Leaching and Electrowinning) zinc extraction route. Fluoride (F) may be present as calcium fluoride (CaF2) and this is, for example, the case in double leached Waelz oxide (DLWO). Efficient removal of F from primary and secondary raw materials for zinc extraction results in a simplified process and increases flexibility in the selection of raw materials. Understanding of the solubility behavior of pure CaF2 can give valuable information on treatment for maximized halogen removal. Dissolution of CaF2 was studied with the addition of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). Dissolution studies were combined with thermodynamic calculations to understand the solubility behavior of CaF2 under different conditions. Results from the experiments and the thermodynamic calculations show that Na2CO3 and NaHCO3 have similar behavior if the pH is controlled at the same value. The available carbonate (CO32−) ion in the system limits the concentration of calcium (Ca2+) ion by precipitation of CaCO3, which enhances the dissolution of CaF2. At higher temperatures and pH, calcite, vaterite, and aragonite were formed and co-precipitation of CaF2 along with calcium carbonate (CaCO3) was observed. At lower temperatures and lower pH levels, only calcite and vaterite were formed and a coating by CaCO3 on CaF2 was found to hinder complete dissolution reaction. The results of this study indicate that the temperature along with the reagents used for the dissolution tests have a significant impact on the CaCO3 polymorph mixture (calcite, vaterite and aragonite) formation.

  • 24.
    Sar, Suchandra
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sundqvist Ökvist, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Sparrman, Tobias
    Umeå University.
    Engström, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Samuelsson, Caisa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Characterization of Double Leached Waelz Oxide for Identification of Fluoirde Mineral2019In: Metals, ISSN 2075-4701, Vol. 9, no 3, article id 361Article in journal (Refereed)
    Abstract [en]

    Double leached Waelz oxide (DLWO), with 76% zinc, is a secondary zinc containing raw materials obtained by the treatment of electric arc furnace dust. The content of fluoride in DLWO is still too high for direct leaching, as fluoride has a detrimental effect on electrowinning for zinc production. Knowledge of the characteristics of DLWO, and especially on how a fluoride mineral might exist, can contribute to further improvement of the selective leaching for the removal of fluoride. In this study, DLWO was characterized using analytical techniques, such as inductively coupled plasma-optical emission spectroscopy (ICP-OES), 19F liquid-state nuclear magnetic resonance (19F LS NMR), X-ray powder diffraction analysis (XRD), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and 19F solid-state nuclear magnetic resonance (19F SS NMR). This study showed that DLWO mainly consisted of zincite (ZnO), cerussite (PbCO3) and a spinel containing zinc, iron and manganese. The fluoride mineral identified was calcium fluoride (CaF2). In SEM analysis, fluorine was found in larger grains together with calcium and oxygen, which was possibly calcium carbonate.

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  • 25.
    Sundqvist Ökvist, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Andersson, Anton
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Hydrometallurgical Recycling of Lithium from Off-Gas Dust Generated in Pyrometallurgical Treatment of Lithium-Ion Batteries2020In: Proceedings of the 59th annual conference of metallurgists (COM2020), Canadian Institute of Mining, Metallurgy and Petroleum, 2020, article id 819325Conference paper (Other academic)
  • 26.
    Sundqvist Ökvist, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerea MEFOS AB, Aronstorpsvägen 1, 974 37 Luleå Sweden.
    From, Lars-Erik
    Swerea MEFOS AB, Aronstorpsvägen 1, 974 37 Luleå Sweden.
    Ölund, Martin
    Swerea MEFOS AB, Aronstorpsvägen 1, 974 37 Luleå Sweden.
    Orre, Joel
    Swerea MEFOS AB, Aronstorpsvägen 1, 974 37 Luleå Sweden.
    Sundelin, Bo
    SSAB Special Steels, Järnverket, 961 31 Oxelösund, Sweden.
    Ahmed, Hesham
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Lowering of CO2 Emissions at the BF by Using Biocoal: Theoretical and Practical Possibilities and Limitations2018In: 2018 AISTech Conference Proceedings, Association for Iron and Steel Technology (AISTECH) , 2018, p. 61-72, article id PR-374-133Conference paper (Refereed)
  • 27.
    Sundqvist Ökvist, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Process Metallurgy Department, Swerea Mefos AB, Luleå.
    Lagerwall, Per
    Ironmaking Department, SSAB Europe, Luleå.
    Sundelin, Bo
    Strategic Production Development, SSAB Special Steels, Oxelösund.
    Orre, Joel
    Process Metallurgy Department, Swerea Mefos AB, Luleå.
    Brämming, Mats
    Process Integration Department, Swerea Mefos AB, Luleå.
    Lundgren, Maria
    Process Metallurgy Department, Swerea Mefos AB, Luleå.
    Low CO2 ironmaking in the blast furnace: Roheisenerzeugung im Hochofen mit niedrigen CO2 Emissionen2017In: Stahl und Eisen (1881), ISSN 0340-4803, Vol. 137, no 9, p. 29-37Article in journal (Refereed)
    Abstract [en]

    The steel industry contributes to the global emissions of fossil CO2 by ~ 7 %, mainly related to coal and coke used in the BF. At the same time the BF is, and will be in a foreseeable future, the most energy efficient method for ore based hot metal production. Several R&D teams have investigated concepts to minimise CO2 emission as e.g. the ULCOS top gas recycling BF, high injection of H2, use of bio-mass products and HBI. In this paper these different options, and in some cases combination of these are analysed relative the BF conditions and their possible impacts on fossil CO2 emission are compared.

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  • 28.
    Sundqvist Ökvist, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering. Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Lundgren, Maria
    Swerim AB, Box 812, 971 25 Luleå, Sweden.
    Experiences of Bio-Coal Applications in the Blast Furnace Process—Opportunities and Limitations2021In: Minerals, E-ISSN 2075-163X, Vol. 11, no 8Article in journal (Refereed)
    Abstract [en]

    Metal production, and especially iron ore-based steel production, is characterized by high fossil CO2 emissions due of the use of coal and coke in the blast furnace. Steel companies around the world are striving to reduce the CO2 emissions in different ways, e.g., by use of hydrogen in the blast furnace or by production of iron via direct reduction. To partially replace fossil coal and coke with climate neutral bio-coal products that are adapted for use in the metal industry, e.g., at the blast furnace, is a real and important opportunity to significantly lower the climate impact in a short-term perspective. Top-charging of bio-coal directly to the blast furnace is difficult due to its low strength but can be facilitated if bio-coal is added as an ingredient in coke or to the mix when producing residue briquettes. Bio-coal can also be injected into the lower part of the blast furnace and thereby replace a substantial part of the injected pulverized coal. Based on research work within Swerim, where the authors have been involved, this paper will describe the opportunities and limitations of using bio-coal as a replacement for fossil coal as part of coke, as a constituent in residue briquettes, or as replacement of part of the injected pulverized coal. Results from several projects studying these opportunities via technical scale, as well as pilot and industrial scale experiments and modelling will be presented. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

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