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Feng, Y., Yang, Q., Chen, Q., Kero, J., Andersson, A., Ahmed, H., . . . Samuelsson, C. (2019). Characterization and evaluation of the pozzolanic activity of granulated copper slag modified with CaO. Journal of Cleaner Production, 232, 1112-1120
Open this publication in new window or tab >>Characterization and evaluation of the pozzolanic activity of granulated copper slag modified with CaO
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2019 (English)In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 232, p. 1112-1120Article in journal (Refereed) Published
Abstract [en]

GCS, granulated copper slag, is currently utilized in cement and concrete with a low rate, due mainly to its low pozzolanic activity. The present study was thus performed by first mixing the GCS with CaO, and then melting and water-granulating the GCS-CaO mixtures, as to enhance the reactivity of GCS. Blended cements were formulated by replacing 30 wt. % of the cement, PC, with the modified GCS. The addition of CaO in GCS increased the release rates of heat from the early-age hydration of the blended cement pastes. The pastes with CSC20, the GCS of the highest CaO content (19.5%), acquired higher compressive strengths than those for the PC and other PC-GCS pastes at both 28 and 90 days of curing. The GCS richer in CaO consumed more calcium hydroxide for the formation of calcium silicate hydrates, with SEM micrographs showing a microstructure of more gel phases and less pores in PC-GCS paste. These results indicate that the modification by addition of CaO is an effective way to achieve a high reactivity for the GCS. It may then be possible to utilize the modified GCS as a high-quality supplementary cementitious material to enhance the sustainability for both copper and cement industries.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-74404 (URN)10.1016/j.jclepro.2019.06.062 (DOI)000477784000095 ()2-s2.0-85067309016 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-06-17 (svasva)

Available from: 2019-06-12 Created: 2019-06-12 Last updated: 2019-08-20Bibliographically approved
Lotfian, S., Ahmed, H., Umeki, K. & Samuelsson, C. (2019). Conversion Characteristics of Alternative Reducing Agents for the Bath Smelting Processes in an Oxidizing Atmosphere. Journal of Sustainable Metallurgy, 5(2), 230-239
Open this publication in new window or tab >>Conversion Characteristics of Alternative Reducing Agents for the Bath Smelting Processes in an Oxidizing Atmosphere
2019 (English)In: Journal of Sustainable Metallurgy, ISSN 2199-3823, Vol. 5, no 2, p. 230-239Article in journal (Refereed) Published
Abstract [en]

The amount of plastic-containing materials, such as shredder residue material, which is generated after the processing of electronic equipment waste, is increasing. One interesting option for the sustainable management of these materials, instead of incineration or landfilling, is recycling through injection in a bath smelting process, such as zinc fuming. In this way, the plastic material could partially substitute coal as a reductant in the process. In such processes, shredder residue material is injected alongside air into the furnace at temperatures up to 1250 °C. Once the material is injected, it undergoes several conversion steps, including ignition, devolatilization, and char oxidation. In this study, the conversions of shredder residue material and other pure plastic materials were investigated using a drop tube furnace and an optical single-particle burner. The effect of particle size on the conversion time of each material was studied. The conversion time of the particles increases as the particle size increases, although the relationship is not linear. The results indicate that plastic materials with a particle size range of 1–7 mm have a considerably longer conversion time than that of coal used in the conventional processes.

Place, publisher, year, edition, pages
New York: Springer, 2019
Keywords
Shredder residue materials, Thermal conversion, Oxidizing conditions, Drop tube furnace, Optical single- particle burner
National Category
Metallurgy and Metallic Materials Energy Engineering
Research subject
Process Metallurgy; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-73269 (URN)10.1007/s40831-019-00217-x (DOI)000471200800009 ()2-s2.0-85062709413 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-01 (johcin)

Available from: 2019-03-20 Created: 2019-03-20 Last updated: 2019-07-01Bibliographically approved
Kumar, T. S., Viswanathan, N. N., Ahmed, H., Dahlin, A., Andersson, C. & Björkman, B. (2019). Developing the Oxidation Kinetic Model for Magnetite Pellet. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 50(1), 162-172
Open this publication in new window or tab >>Developing the Oxidation Kinetic Model for Magnetite Pellet
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2019 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, no 1, p. 162-172Article in journal (Refereed) Published
Abstract [en]

Oxidation is a vital phenomenon for magnetite pellets in their excursion through the furnace during induration. One of the pre-requisites for magnetite pellets to achieve homogeneously structured good quality pellets is to have complete oxidation before sintering begins. Partially oxidized magnetite pellets, upon sintering, might result in inhomogeneous structured pellets which could be detrimental to pellet quality. It is necessary to understand the mechanisms responsible for magnetite oxidation, and hence, it is intended in this study to investigate experimentally as well as develop a mathematical model based on oxidation kinetics. Oxidation of pellets is largely influenced by the oxidation kinetics of particles and hence should be studied at particle as well as at pellet scale. The principles of the Grain Model have been adopted to develop the Oxidation Model at pellet scale, whereas the particles’ oxidation follows the Avrami Kinetic Model. Isothermal oxidation experiments performed Thermogravimetric Analyzer showed that oxidation rate of magnetite at pellet scale contained two peaks. They were complemented well by oxidation rates predicted from the model. Further, the pellet was investigated microstructurally at pellet and particle scale to substantiate the findings from the experiments and the model. The oxidation model developed is used to predict the progression of oxidation in the magnetite pellet with respect to the reaction time at three different temperatures (873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C)) and at four levels of oxygen (0.21, 0.30, 0.60, and 1.00 atm) in the oxidizing gas.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Pellet Oxidation Model, Magnetite Pellet, Induration, Grain model
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-71433 (URN)10.1007/s11663-018-1423-4 (DOI)000456070300017 ()2-s2.0-85055995152 (Scopus ID)
Projects
Investigations on the Physico-Chemical Phenomena during Induration of a Magnetite Pellet
Note

Validerad;2019;Nivå 2;2019-02-11 (inah)

Available from: 2018-11-05 Created: 2018-11-05 Last updated: 2019-04-24Bibliographically approved
El-Tawil, A., Ahmed, H., Sundqvist Ökvist, L. & Björkman, B. (2019). Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis. Metals, 9(2), Article ID 168.
Open this publication in new window or tab >>Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis
2019 (English)In: Metals, E-ISSN 2075-4701, Vol. 9, no 2, article id 168Article in journal (Refereed) Published
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. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
devolatilization, torrefied biomass, bio-coal, volatile matter, iso-conversional method
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-73181 (URN)10.3390/met9020168 (DOI)000460764700059 ()2-s2.0-85062329541 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-03-13 (johcin)

Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2019-04-12Bibliographically approved
Lotfian, S., Vikström, T., Lennartsson, A., Björkman, B., Ahmed, H. & Samuelsson, C. (2019). Evaluating the potential of plastic-containing materials as alternative reducing agents. Canadian metallurgical quarterly, 58(4), 389-399
Open this publication in new window or tab >>Evaluating the potential of plastic-containing materials as alternative reducing agents
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2019 (English)In: Canadian metallurgical quarterly, ISSN 0008-4433, E-ISSN 1879-1395, Vol. 58, no 4, p. 389-399Article in journal (Refereed) Published
Abstract [en]

The amount of discarded plastic-containing materials is increasing, and one option to help with this issue is to use these materials in bath smelting processes. The injection of plastic-containing materials to partially substitute coal in zinc-fuming processes has been studied in an industrial trial at Boliden–Rönnskär smelter. To evaluate the potential of plastic-containing materials, thermodynamic calculations were performed in this study. In the first step, a thermodynamic calculation was performed for trials with only coal injection, and then this calculation was applied to trials with the co-injection of plastic materials. The thermodynamic calculation shows that not all the injected coal participates in the reactions within the slag. Similarly, the calculation with the co-injection of plastic-containing materials shows that different amounts of each plastic material participate in the reactions within the slag bath.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
base metal production, industrial trial, recycling, reducing agent, Shredder residue material, sustainable management, thermodynamic calculation
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-73373 (URN)10.1080/00084433.2019.1590044 (DOI)000463333600001 ()
Note

Validerad;2019;Nivå 2;2019-10-10 (johcin)

Available from: 2019-04-01 Created: 2019-04-01 Last updated: 2019-10-10Bibliographically approved
Kumar, T. S., Nurni, V., Ahmed, H., Andersson, C., Dahlin, A. & Björkman, B. (2019). Investigation of Magnetite Oxidation Kinetics at the Particle Scale. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 50(1), 150-161
Open this publication in new window or tab >>Investigation of Magnetite Oxidation Kinetics at the Particle Scale
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2019 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, no 1, p. 150-161Article in journal (Refereed) Published
Abstract [en]

The induration of magnetite pellets is a complex physico-chemical process that involves oxidation, sintering, and heat transfer. The thermal- and gas-composition profile that is experienced by the pellet in an induration reactor could result in the formation of a homogenous or heterogeneous pellet structure, which could affect the pellet quality. The oxidation kinetics of magnetite pellets from sintering studies have been studied at two levels, namely, the pellet scale and at the particle scale, and the findings of the latter are presented here. The rate of oxidation of the magnetite concentrate depends primarily on temperature, oxygen content in the oxidizing gas, and particle size. These factors are investigated in this study. It was found that the oxidation of the magnetite concentrate is comprised of two distinct stages, a primary stage with high rates followed by a secondary stage where rates decrease significantly. The isothermal oxidation behavior as analyzed by the Avrami kinetic model was found to fit better than the shrinking-core model. The partially oxidized particles were examined microstructurally to supplement the experimental and model results. The Avrami kinetic model for isothermal oxidation was extended to non-isothermal profiles using the superposition principle, and the model was validated experimentally.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Oxidation Kinetics, Shrinking Core Mechanism, Avrami Mechanism, Magnetite particle oxidation
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-71839 (URN)10.1007/s11663-018-1459-5 (DOI)000456070300016 ()2-s2.0-85057526513 (Scopus ID)
Projects
Investigations on the Physico-Chemical Phenomena during Induration of a Magnetite Pellet
Note

Validerad;2019;Nivå 2;2019-02-01 (johcin) 

Available from: 2018-11-30 Created: 2018-11-30 Last updated: 2019-02-01Bibliographically approved
Andersson, A., Gullberg, A., Kullerstedt, A., Wedholm, A., Wikström, J., Ahmed, H. & Sundqvist Ökvist, L. (2019). Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation. ISIJ International
Open this publication in new window or tab >>Recycling of Blast Furnace Sludge to the Blast Furnace via Cold-Bonded Briquettes: Evaluation of Feasibility and Influence on Operation
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2019 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460Article in journal (Refereed) Epub ahead of print
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.

Place, publisher, year, edition, pages
Iron and Steel Institute of Japan, 2019
Keywords
blast furnace sludge, recycling, cold-bonded briquettes, pilot-plant scale blast furnace trials, industrial-scale blast furnace trials
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-75198 (URN)10.2355/isijinternational.ISIJINT-2019-080 (DOI)
Funder
Swedish Energy Agency, JK21069
Available from: 2019-07-03 Created: 2019-07-03 Last updated: 2019-08-22
Andersson, A., Gullberg, A., Kullerstedt, A., Ahmed, H., Sundqvist Ökvist, L. & Samuelsson, C. (2019). Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes. Journal of Sustainable Metallurgy (3), 350-361
Open this publication in new window or tab >>Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes
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2019 (English)In: Journal of Sustainable Metallurgy, ISSN 2199-3823, no 3, p. 350-361Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Blast furnace sludge, Recycling, Upgrading, De-zincing, Cold-bonded briquettes, Laboratory-scale blast furnace
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-73899 (URN)10.1007/s40831-019-00225-x (DOI)000483723600008 ()2-s2.0-85065727551 (Scopus ID)
Funder
Swedish Energy Agency, JK21069
Note

Validerad;2019;Nivå 2;2019-09-27 (johcin)

Available from: 2019-05-10 Created: 2019-05-10 Last updated: 2019-09-27Bibliographically approved
Andersson, A., Gullberg, A., Kullerstedt, A., Sandberg, E., Andersson, M., Ahmed, H., . . . Björkman, B. (2018). A Holistic and Experimentally-Based View on Recycling of Off-Gas Dust within the Integrated Steel Plant. Metals, 8(10), Article ID 760.
Open this publication in new window or tab >>A Holistic and Experimentally-Based View on Recycling of Off-Gas Dust within the Integrated Steel Plant
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2018 (English)In: Metals, ISSN 2075-4701, Vol. 8, no 10, article id 760Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Basel: MDPI, 2018
Keywords
Recycling, Cold-bonded briquettes, Blast furnace, Desulfurization, Basic oxygen furnace, Dust, Sludge, Fines
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-71130 (URN)10.3390/met8100760 (DOI)000448658700024 ()2-s2.0-85054764975 (Scopus ID)
Funder
Swedish Energy Agency
Note

Validerad;2018;Nivå 2;2018-10-19 (marisr)

Available from: 2018-10-08 Created: 2018-10-08 Last updated: 2019-08-22Bibliographically approved
Kumar, T. K., Simonsson, M., Nurni, V., Ahmed, H., Andersson, C., El-Geassy, A.-H. A. & Björkman, B. (2018). Establishing a Novel Methodology to Correlate the Macroscopic and Microscopic Degree of Sintering inMagnetite Pellets during Induration. Steel Research International, 89(3), Article ID 1700366.
Open this publication in new window or tab >>Establishing a Novel Methodology to Correlate the Macroscopic and Microscopic Degree of Sintering inMagnetite Pellets during Induration
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2018 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, no 3, article id 1700366Article in journal (Refereed) Published
Abstract [en]

The quality of product pellets is a result of the physico-chemical phenomenainvolved in the induration process. Sintering is the primary phenomenon,and its degree or extent contributes substantially to the evolution of themetallurgical and mechanical properties of a pellet. During the induration ofmagnetite pellets, sintering proceeds through the oxidized and non-oxidizedmagnetite phases. Sintering of these phases has been previously studied ona single pellet at the macroscopic scale using an optical dilatometer. Adeeper understanding requires corroboration of these studies throughcharacterization at the microscopic scale. In the present work, the observationsrecorded at the microscopic scale are quantified using image processingtechniques to correlate them to the macroscopic measurements. Distancetransformation, which is an image processing principle, is adapted in a novelway to digitize the microstructures and to determine the degree of sinteringin a pellet quantitatively. This methodology has potential applications as ageneric tool to follow the sintering phenomenon and process kinetics at anystage during induration.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
Distance Transform, Induration, Optical Microstructures, Oxidized and Non-oxidized Magnetite Pellets, Sintering Degree
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-66590 (URN)10.1002/srin.201700366 (DOI)000426525900012 ()2-s2.0-85042594552 (Scopus ID)
Projects
Modeling of Physico-Chemical phenomena during Induration of Magnetite Pellet
Note

Validerad;2018;Nivå 2;2018-02-02 (andbra)

Available from: 2017-11-15 Created: 2017-11-15 Last updated: 2018-05-16Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2358-7719

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