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Lu, Y.-C., Karasev, A., Glaser, B. & Wang, C. (2024). Comparison of Hydrochar and Anthracite as Reducing Agents for Direct Reduction of Hematite. ISIJ International, 64(6), 978-987, Article ID ISIJINT-2023-436.
Open this publication in new window or tab >>Comparison of Hydrochar and Anthracite as Reducing Agents for Direct Reduction of Hematite
2024 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 64, no 6, p. 978-987, article id ISIJINT-2023-436Article in journal (Refereed) Published
Abstract [en]

The substitution of fossil coal with biocarbon in the metallurgical processes can help to decrease fossil CO2 emissions. Biocarbon’s characteristics, such as high volatile matter contents and high reactivities with CO2, are beneficial for increasing the reduction degrees and reduction rates of iron oxides in carbon composite agglomerates (CCA). This study compared the reduction of hematite by of two types of carbonaceous materials (CM): hydrochar (high-volatile biocarbon) and anthracite (a low-volatile coal) in the form of CCA. CM, hematite, and binder (starch) were mixed together to obtain mixtures with C/O molar ratios equal to 0.4–1.2. The mixtures were reduced non-isothermally in nitrogen atmosphere up to 1003 K or 1373 K. Up to 1003 K, the volatiles released from CMs and starch reduced hematite by 18–35%. Between 1003 K and 1373 K, both hydrochars (produced from lemon peels and rice husks) reacted with iron oxides more rapidly than anthracite below 1360 K, when the samples had C/O ratios in the range of 1.0–1.2. In this temperature range, rice husk hydrochar promoted a slower reaction with iron oxides than lemon peel hydrochar, which was possibly influenced by its higher ash content which decreased the rate of Boudouard reaction. Samples with C/O ≥ 1.0 achieved complete reduction at 1373 K, regardless of the type of CM used, whereas samples with C/O equal to 0.4–0.5 achieved 63–86% reduction. It can be concluded from this study that hydrochar can fully substitute anthracite for direct reduction of iron oxide to decrease fossil CO2 emissions during ironmaking processes.

Place, publisher, year, edition, pages
Tokyo, Japan: Iron and Steel Institute of Japan, 2024
Keywords
direct reduction of iron, carbothermic reduction, carbon composite agglomerates, hydrochar, anthracite, biocarbon, volatile matter
National Category
Metallurgy and Metallic Materials
Research subject
Metallurgical process science; Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-345649 (URN)10.2355/isijinternational.isijint-2023-436 (DOI)2-s2.0-85192161980 (Scopus ID)
Funder
Vinnova, 2020-04140
Note

QC 20240416

Available from: 2024-04-16 Created: 2024-04-16 Last updated: 2024-05-16Bibliographically approved
Lu, Y.-C., Karasev, A. & Ersson, M. (2023). Direct Reduction of Iron Ore Pellets by Using CO/CO2 and CO Gases. Steel Research International, 95(3)
Open this publication in new window or tab >>Direct Reduction of Iron Ore Pellets by Using CO/CO2 and CO Gases
2023 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 95, no 3Article in journal (Refereed) Published
Abstract [en]

Gas-based direct reduction in a shaft furnace is the dominant process in the world for production of direct reduced iron. As fresh reducing gas passes through the iron ore burden, it is diluted by the gas emitted from the reacted iron ores which decreases the reduction potential of the reducing gas. Previous reduction experiments mostly used single pellet which could not examine this phenomenon. In this study, hematite pellets arranged in multiple layers inside a molybdenum basket are reduced isothermally at 1173–1273 K using 50% CO + 50% CO2% and 100% CO gases under flow rates of 0.2–5.0 NL min−1 to simulate the dilution of CO by CO2 in the shaft. It is discovered that the reduction of pellets in the basket is highly uneven even in pure CO atmosphere. Pellets in the middle layer are reduced ≈2 times less than the pellets in the top and bottom layers. The top side of a pellet is also less reduced than the bottom side facing the gas inlet. During melting of incompletely reduced pellets at 1873 K, intensive interaction between the unreduced iron oxides and the alumina crucible was observed. Thus, smelting of incompletely reduced iron could potentially shorten the refractory lifetime.

Place, publisher, year, edition, pages
Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2023
Keywords
carbon monoxide, direct reduced iron, incompletely reduced iron, iron ore pellet, low CO2 steelmaking
National Category
Metallurgy and Metallic Materials
Research subject
Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-345650 (URN)10.1002/srin.202300634 (DOI)001134496800001 ()2-s2.0-85180849422 (Scopus ID)
Projects
OSMET 3.0
Funder
Vinnova, 2021‐04660
Note

QC 20240416

Available from: 2024-04-16 Created: 2024-04-16 Last updated: 2024-04-26Bibliographically approved
Wang, Y., Liu, C., Ni, H., Karasev, A., Mu, W., Jönsson, P. & Park, J. H. (2023). Effect of ferrochromium (FeCr) and ferroniobium (FeNb) alloys on inclusion and precipitate characteristics in austenitic stainless steels. Journal of Materials Research and Technology, 25, 4989-5002
Open this publication in new window or tab >>Effect of ferrochromium (FeCr) and ferroniobium (FeNb) alloys on inclusion and precipitate characteristics in austenitic stainless steels
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2023 (English)In: Journal of Materials Research and Technology, ISSN 2238-7854, Vol. 25, p. 4989-5002Article in journal (Refereed) Published
Abstract [en]

Lab-scale alloying experiments were carried out by first adding commercial low-carbon ferrochrome (LCFeCr) alloys and then adding ferroniobium (FeNb) alloys in 316-grade austenitic stainless steel in this study. The inclusion and precipitation characteristics in LCFeCr and FeNb were evaluated as well as in a 316 austenitic stainless steel after the alloy additions by using two- and three-dimensional characterization methods in combination with thermodynamic calculations. The results showed that MnCr2O4 spinels and pure Al2O3 were the main types of inclusions in LCFeCr alloys, while pure TiOx, Al2O3 inclusions and complex TiOx-Al2O3 aggregates were mainly found in FeNb alloys. After the addition of LCFeCr alloy to the steel, the SiO2 contents in liquid inclusions decreased to some extent, while more inclusions containing higher MnO contents were observed. Some MnCr2O4 spinel inclusions can be reduced by Si in steel and form liquid inclusions. Some MnCr2O4 spinel and Al2O3 inclusions from LCFeCr alloy can remain in the steel melt, which decreased the steel cleanliness. After the addition of FeNb alloy, pure TiOx inclusions present in this alloy can hardly be found in the steel melt. The inclusion types in steel were not changed so much but high Nb-containing phases were found around the inclusions and coarse Laves phases were formed in the matrix. Overall, this work aims to understand the impurity particle behavior during the alloying process when using ferroalloys to produce high-performance stainless steels.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Alloying, Ferrochromium, Ferroniobium, Non-metallic inclusion, Precipitate
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-333902 (URN)10.1016/j.jmrt.2023.07.011 (DOI)2-s2.0-85164302982 (Scopus ID)
Note

QC 20230822

Available from: 2023-08-22 Created: 2023-08-22 Last updated: 2023-11-28Bibliographically approved
Lu, Y.-C., Yang, H., Karasev, A., Wang, C. & Jönsson, P. (2022). Applications of Hydrochar and Charcoal in the Iron and Steelmaking Industry—Part 1: Characterization of Carbonaceous Materials. Sustainability, 14(15), 9488-9488
Open this publication in new window or tab >>Applications of Hydrochar and Charcoal in the Iron and Steelmaking Industry—Part 1: Characterization of Carbonaceous Materials
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2022 (English)In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 15, p. 9488-9488Article in journal (Refereed) Published
Abstract [en]

The iron and steelmaking industry faces the dilemma of the need to decrease their greenhouse gas emissions to align with decarbonization goals, while at the same time fulfill the increasing steel demand from the growing population. Replacing fossil coal and coke with biomass-based carbon materials reduces the net carbon dioxide emissions. However, there is currently a shortage of charcoal to fully cover the demand from the iron and steelmaking industry to achieve the emission-reduction goals. Moreover, the transportation and energy sectors can compete for biofuel usage in the next few decades. Simultaneously, our society faces challenges of accumulation of wastes, especially wet organic wastes that are currently not reused and recycled to their full potentials. Here, hydrothermal carbonization is a technology which can convert organic feedstocks with high moisture contents to solid fuels (hydrochar, one type of biochar) as an alternative renewable carbon material. This work studied the differences between a hydrochar, produced from lemon peels (Lemon Hydrochar), and two types of charcoals (with and without densification) and an Anthracite coal. Characterizations such as chemical and ash compositions, thermogravimetric analyses in nitrogen and carbon dioxide atmospheres, scanning electron microscope analyses of carbon surface morphologies, and pyrolysis up to 1200 °C were performed. The main conclusions from this study are the following: (1) hydrochar has a lower thermal stability and a higher reactivity compared to charcoal and Anthracite; (2) densification resulted in a reduction of the moisture pickup and CO2 reactivity of charcoal; (3) pyrolysis of Lemon Hydrochar resulted in the formation of a large amount of tar (17 wt%) and gas (39 wt%), leading to its low fixed carbon content (27 wt%); (4) a pyrolyzed hydrochar (up to 1200 °C) has a comparable higher heating value to those of charcoal and Anthracite, but its phosphorous, ash, and alkalis contents increased significantly; (5) based on the preliminary assessment, hydrochar should be blended with charcoal or Anthracite, or be upgraded through slow pyrolysis to fulfill the basic functions of carbon in the high-temperature metallurgical processes.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI, 2022
Keywords
greenhouse gas emissions; biomass; charcoal; hydrothermal carbonization; hydrochar; low CO2 steelmaking
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-345651 (URN)10.3390/su14159488 (DOI)000839429900001 ()2-s2.0-85129699865 (Scopus ID)
Projects
OSMET 3.0
Funder
Vinnova, 2020-04140
Note

QC 20240416

Available from: 2024-04-16 Created: 2024-04-16 Last updated: 2024-04-26Bibliographically approved
Lu, Y.-C., Brabie, L., Karasev, A. & Wang, C. (2022). Applications of Hydrochar and Charcoal in the Iron and Steelmaking Industry—Part 2: Carburization of Liquid Iron by Addition of Iron–Carbon Briquettes. Sustainability, 14(9), 5383-5383
Open this publication in new window or tab >>Applications of Hydrochar and Charcoal in the Iron and Steelmaking Industry—Part 2: Carburization of Liquid Iron by Addition of Iron–Carbon Briquettes
2022 (English)In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 9, p. 5383-5383Article in journal (Refereed) Published
Abstract [en]

Hydrochar (a solid product from hydrothermal carbonization of organic feedstock) and charcoal have the potential to substitute coke and coal consumption in the iron and steelmaking processes for reduction of greenhouse gas (GHG) emissions. Among steelmaking processes, melt carburization is an important but less-studied application. In this study, briquettes produced with mixture a of iron powder, hydrochar or charcoal powder, and binder were tested as iron melt recarburizers. It was found that the hydrochar briquettes have good mechanical properties, whereas those of charcoal briquettes were poor. Melt carburization with briquettes was performed in a lab induction furnace (10 kg) in two steps: firstly, by heating up some briquettes with charged electrolytic iron from room temperature up to 1600 °C, followed by the addition of some briquettes into the melt. Recarburization efficiency (RE) during the first step of carburization was found to be controlled by the amount of carbon content bound in the solid phase (fixed carbon) determined at 1200 °C. Thus, the REs of charcoal briquettes (70–72%) were higher than those of hydrochar (43–58%) due to the higher fixed carbon contents in charcoal. REs obtained from the second step were strongly affected by the amount of briquette losses during their addition into the iron melt, which correlate with the mechanical strengths of the briquettes. Thus, the REs for hydrochar briquettes (48–54%) were higher than those of charcoal (26–39%). This study proves the feasibility of using hydrochar and charcoal as liquid steel recarburizers.

Place, publisher, year, edition, pages
Basel, Switzerland: MDPI AG, 2022
Keywords
greenhouse gas emissions, EAF, briquettes, carburization, hydrochar, charcoal, recarburization efficiency
National Category
Metallurgy and Metallic Materials
Research subject
Metallurgical process science
Identifiers
urn:nbn:se:kth:diva-345648 (URN)10.3390/su14095383 (DOI)000795336600001 ()2-s2.0-85129729455 (Scopus ID)
Projects
OSMET 3.0
Funder
Vinnova, 2020-04140
Note

QC 20240416

Available from: 2024-04-16 Created: 2024-04-16 Last updated: 2024-04-26Bibliographically approved
Sidorova, E., Karasev, A., Kuznetsov, D. & Jönsson, P. G. (2022). Investigation of the Initial Corrosion Destruction of a Metal Matrix around Different Non-Metallic Inclusions on Surfaces of Pipeline Steels. Materials, 15(7), Article ID 2530.
Open this publication in new window or tab >>Investigation of the Initial Corrosion Destruction of a Metal Matrix around Different Non-Metallic Inclusions on Surfaces of Pipeline Steels
2022 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 15, no 7, article id 2530Article in journal (Refereed) Published
Abstract [en]

Typical non-metallic inclusions in two industrial low-carbon steels for oil pipelines were investigated as three-dimensional objects on film filters after electrolytic extraction and filtration of metal samples. A method of soft chemical extraction using a 10%AA electrolyte was used to study the initial corrosion process in the steel matrix surrounding various non-metallic inclusions. To determine and compare "corrosive" inclusions and their influence on the initial stages of corrosion of the adjacent layer of the steel matrix, quantitative parameters (such as the diameter of the corrosion crater (D-cr) and pit (D-pit), and the relative dissolution coefficient of the metal matrix (KD) around various inclusions) were determined after chemical extraction. It was found that CaO-Al2O3-MgO oxides and TiN inclusions did not cause an initial corrosion of the steel matrix surrounding these inclusions. However, tensile stresses in the steel matrix occurred around CaS inclusions (or complex inclusions containing a CaS phase), which contributed to the initiation of corrosion around these inclusions.

Place, publisher, year, edition, pages
MDPI AG, 2022
Keywords
pipeline steels, non-metallic inclusions, corrosion, electrolytic extraction, chemical extraction
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-311292 (URN)10.3390/ma15072530 (DOI)000781839400001 ()35407861 (PubMedID)2-s2.0-85128297335 (Scopus ID)
Note

QC 20220421

Available from: 2022-04-21 Created: 2022-04-21 Last updated: 2022-06-25Bibliographically approved
De Colle, M., Puthucode, R., Karasev, A. & Jönsson, P. (2021). A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials. Materials, 14(17), 4806
Open this publication in new window or tab >>A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials
2021 (English)In: Materials, E-ISSN 1996-1944, Vol. 14, no 17, p. 4806-Article in journal (Refereed) Published
Abstract [en]

Different stainless steel slags have been successfully employed in previous experiments, for the treatment of industrial acidic wastewaters. Although, before this technology can be implemented on an industrial scale, upscaled pilot experiments need to be performed. In this study, the parameters of the upscale trials, such as the volume and mixing speeds, are firstly tested by dispersing a NaCl tracer in a water bath. Mixing time trials are used to maintain constant mixing conditions when the volumes are increased to 70, 80 and 90 L, compared to the 1 L laboratory trials. Subsequently, the parameters obtained are used in pH buffering trials, where stainless steel slags are used as reactants, replicating the methodology of previous studies. Compared to laboratory trials, the study found only a minor loss of efficiency. Specifically, in previous studies, 39 g/L of slag was needed to buffer the pH of the acidic wastewaters. To reach similar pH values within the same time span, upscaled trials found a ratio of 43 g/L and 44 g/L when 70 and 90 L are used, respectively. Therefore, when the kinetic conditions are controlled, the technology appears to be scalable to higher volumes. This is an important finding that hopefully promotes further investments in this technology.

Place, publisher, year, edition, pages
MDPI AG, 2021
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-301057 (URN)10.3390/ma14174806 (DOI)000694276800001 ()34500896 (PubMedID)2-s2.0-85114040658 (Scopus ID)
Note

QC 20220322

Available from: 2021-09-03 Created: 2021-09-03 Last updated: 2024-01-12Bibliographically approved
Karasev, A., Gorkusha, D., Grigorovich, K. V. & Jönsson, P. (2021). Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg. Metals, 11(3), Article ID 448.
Open this publication in new window or tab >>Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg
2021 (English)In: Metals, ISSN 2075-4701, Vol. 11, no 3, article id 448Article in journal (Refereed) Published
Abstract [en]

In this study, a complete and comprehensive analysis of non-metallic inclusions (NMI) in an Fe-10%Ni alloy was done by using two modern analytical methods that complement each other: Electrolytic Extraction (EE) of inclusions from metal samples followed by investigations by using Scanning Electron Microscopy (SEM) and Fractional Gas Analysis (FGA). The composition, morphology, size and number of different NMIs and clusters were investigated in metal samples taken after deoxidation by additions of Ti, Ti/Zr and Ti/Mg. The obtained results were discussed with respect to formation, modification and removal of NMIs and clusters depending on the type of deoxidations and the holding time. It was found that the peaks of oxygen reduced from different oxide inclusions obtained by the FGA measurements corresponded well to the main types of inclusions and clusters observed by using the EE + SEM method. More specifically, the total O content in oxide inclusions (O-NMI) increases by 10% after a Zr addition and then decreases linearly by 40% during 5 min of holding due to flotation of NMIs and clusters. However, after a Mg addition in the melt deoxidized by Ti, the O-NMI content decreases drastically by 63% during 5 min of holding, due to a fast floatation of NMIs caused by bubbles of vaporized Mg.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
Fe-10%Ni alloy, complex deoxidation, oxide non-metallic inclusions, electrolytic extraction, fractional gas analysis
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-293466 (URN)10.3390/met11030448 (DOI)000633878600001 ()2-s2.0-85102030371 (Scopus ID)
Note

QC 20210426

Available from: 2021-04-26 Created: 2021-04-26 Last updated: 2022-06-25Bibliographically approved
Wang, Y. (2021). Characterization of non-metallic inclusions in different ferroalloys used in the steelmaking process. Steel Research International
Open this publication in new window or tab >>Characterization of non-metallic inclusions in different ferroalloys used in the steelmaking process
2021 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344XArticle in journal (Other academic) Submitted
Abstract [en]

 Ferroalloys are one of the most important raw materials widely used in the steelmaking processes. Depending on the cleanliness of used ferroalloys, they can be an inevitable source of impurities and non-metallic inclusions (NMIs) in steelmaking products. In this study, the inclusions in five different industrial ferroalloys (FeTi, FeMo, FeW, MnN and FeCrN) were investigated. This was done by using two-dimensional (2D) investigations on polished crosssections of ferroalloy samples and by using three-dimensional (3D) investigations of NMIs on film filters and metal surfaces after electrolytic extraction (EE) using scanning electron microscopy in combination with energy dispersive spectroscopy (SEM-EDS). Moreover, the characteristics of the main types of inclusions presented on film filters and metal surfaces afterEE were compared and their possible transformations in Al-killed steel were evaluated. The results showed that the main inclusions were more likely the oxidization products of the reductant and some unreduced ore during the ferroalloy production process. The 3Dinvestigations of inclusions on metal surfaces after extraction were found to be very useful in detection and evaluation of larger sized inclusions. Overall, this study helps to better understand the impurities in different ferroalloys and their possible effect on the steel cleanliness. 

Keywords
ferroalloy, non-metallic inclusions, steelmaking, high-alloyed steels, electrolytic extraction.
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-293961 (URN)
Note

QC 20210527

Available from: 2021-05-06 Created: 2021-05-06 Last updated: 2022-06-25Bibliographically approved
Wang, Y., Karasev, A. & Jönsson, P. (2021). Characterization of Nonmetallic Inclusions in Different Ferroalloys used in the Steelmaking Processes. Steel Research International, 92(11), Article ID 2100269.
Open this publication in new window or tab >>Characterization of Nonmetallic Inclusions in Different Ferroalloys used in the Steelmaking Processes
2021 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 92, no 11, article id 2100269Article in journal (Refereed) Published
Abstract [en]

Ferroalloys are one of the most important raw materials widely used in the steelmaking processes. Depending on the cleanliness of used ferroalloys, they can be an inevitable source of impurities and nonmetallic inclusions (NMIs) in steelmaking products. Herein, the inclusions in five different industrial ferroalloys (FeTi, FeMo, FeW, MnN, and FeCrN) are investigated. This is done using 2D investigations on polished cross sections of ferroalloy samples and using 3D investigations of NMIs on film filters and metal surfaces after electrolytic extraction (EE) using scanning electron microscopy in combination with energy-dispersive spectroscopy (SEM-EDS). Moreover, the characteristics of the main types of inclusions presented on film filters and metal surfaces after EE are compared and their possible transformations in Al-killed steel are evaluated. The results show that the main inclusions are more likely the oxidization products of the reductant and some unreduced ore during the ferroalloy production process. The 3D investigations of inclusions on metal surfaces after extraction are found to be very useful in detection and evaluation of larger-sized inclusions. Overall, this study helps to better understand the impurities in different ferroalloys and their possible effect on the steel cleanliness.

Place, publisher, year, edition, pages
Wiley, 2021
Keywords
electrolytic extraction, ferroalloys, high-alloyed steels, nonmetallic inclusions, steelmaking, Aluminum coated steel, Binary alloys, Energy dispersive spectroscopy, Inclusions, Scanning electron microscopy, 3D investigation, Al-killed steel, Metal surfaces, Non-metallic inclusions, Production process, Steel cleanliness, Steelmaking process, Extraction
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-311180 (URN)10.1002/srin.202100269 (DOI)000681385900001 ()2-s2.0-85111812712 (Scopus ID)
Note

QC 20220502

Available from: 2022-05-02 Created: 2022-05-02 Last updated: 2022-06-25Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9801-0842

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