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Sundqvist Ökvist, LenaORCID iD iconorcid.org/0000-0003-3363-351x
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Publications (10 of 27) Show all publications
Hellgren, S., Engström, F. & Sundqvist Ökvist, L. (2024). The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction. Metals, 14(1), Article ID 73.
Open this publication in new window or tab >>The Characterization of Residues Related to the Roasting– Leaching–Electrowinning Zinc Production Route for Further Metal Extraction
2024 (English)In: Metals, ISSN 2075-4701, Vol. 14, no 1, article id 73Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2024
Keywords
characterization for metal extraction, residue recycling, silver identification, super-hot acid leaching, zinc leaching residues
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-104168 (URN)10.3390/met14010073 (DOI)2-s2.0-85183369013 (Scopus ID)
Note

Validerad;2024;Nivå 2;2024-02-05 (joosat);

Funder: EIT Raw Materials, co-funded by European Union (19164); Boliden Mineral AB;

Full text license: CC BY

Available from: 2024-02-05 Created: 2024-02-05 Last updated: 2024-02-05Bibliographically approved
Elsadek, M., Ahmed, H., Suup, M., Sand, A., Heikkinen, E., Khoshkhoo, M. & Sundqvist-Öqvist, L. (2023). Recycling of pyrite and gypsum mining residues through thermochemical conversion into valuable products. Resources, Conservation and Recycling, 199, Article ID 107219.
Open this publication in new window or tab >>Recycling of pyrite and gypsum mining residues through thermochemical conversion into valuable products
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2023 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 199, article id 107219Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Geochemistry
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-101825 (URN)10.1016/j.resconrec.2023.107219 (DOI)2-s2.0-85174184746 (Scopus ID)
Funder
VinnovaSwedish Research Council FormasSwedish Energy Agency
Note

Validerad;2023;Nivå 2;2023-10-30 (hanlid);

Funder: CAMM2 (Center for advanced mining & metallurgy), Luleå University of Technology

Available from: 2023-10-30 Created: 2023-10-30 Last updated: 2023-10-30Bibliographically approved
El-Tawil, A., Björkman, B., Lundgren, M. & Sundqvist Ökvist, L. (2023). The Effect of Bio-Coal Agglomeration and High-Fluidity Coking Coal on Bio-Coke Quality. Metals, 13(1), Article ID 175.
Open this publication in new window or tab >>The Effect of Bio-Coal Agglomeration and High-Fluidity Coking Coal on Bio-Coke Quality
2023 (English)In: Metals, ISSN 2075-4701, Vol. 13, no 1, article id 175Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
agglomerated bio-coal, bio-coke, high-fluidity coking coal, torrefied sawdust
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-95546 (URN)10.3390/met13010175 (DOI)2-s2.0-85146806548 (Scopus ID)
Funder
Swedish Research Council Formas, (FR-2018/0010)
Note

Validerad;2023;Nivå 2;2023-02-08 (joosat);

Licens fulltext: CC BY License

Available from: 2023-02-08 Created: 2023-02-08 Last updated: 2023-09-05Bibliographically approved
Andersson, A., Ahmed, H., Sundqvist Ökvist, L. & Björkman, B. (2021). Evaluation of evaporation kinetics of potassium from synthetic blast furnace slag using full factorial design of experiments. In: : . Paper presented at The 11th International Conference on Molten Slags, Fluxes and Salts (MOLTEN 2021), Seoul, South Korea, Online, February 21-25, 2021.
Open this publication in new window or tab >>Evaluation of evaporation kinetics of potassium from synthetic blast furnace slag using full factorial design of experiments
2021 (English)Conference paper, Oral presentation with published abstract (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.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-88855 (URN)
Conference
The 11th International Conference on Molten Slags, Fluxes and Salts (MOLTEN 2021), Seoul, South Korea, Online, February 21-25, 2021
Available from: 2022-01-19 Created: 2022-01-19 Last updated: 2023-09-05Bibliographically approved
Sundqvist Ökvist, L. & Lundgren, M. (2021). Experiences of Bio-Coal Applications in the Blast Furnace Process—Opportunities and Limitations. Minerals, 11(8)
Open this publication in new window or tab >>Experiences of Bio-Coal Applications in the Blast Furnace Process—Opportunities and Limitations
2021 (English)In: Minerals, E-ISSN 2075-163X, Vol. 11, no 8Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
biomass, bio-coal, charcoal, reducing agent, briquettes, injection, coke
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-86841 (URN)10.3390/min11080863 (DOI)000689471900001 ()2-s2.0-85112058610 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-09-01 (johcin)

Available from: 2021-08-26 Created: 2021-08-26 Last updated: 2024-01-17Bibliographically approved
El-Tawil, A. A., Björkman, B., Lundgren, M., Robles, A. & Sundqvist Ökvist, L. (2021). Influence of Bio-Coal Properties on Carbonization and Bio-Coke Reactivity. Metals, 11(11), Article ID 1752.
Open this publication in new window or tab >>Influence of Bio-Coal Properties on Carbonization and Bio-Coke Reactivity
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2021 (English)In: Metals, ISSN 2075-4701, Vol. 11, no 11, article id 1752Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Minerals, Metals & Materials Society, 2021
Keywords
bio-coals, carbonization, gasification, reactivity, dilatation, fluidity
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-87770 (URN)10.3390/met11111752 (DOI)000725158000001 ()2-s2.0-85118196084 (Scopus ID)
Funder
Swedish Research Council FormasLuleå University of Technology, FR-2018/0010
Note

Validerad;2021;Nivå 2;2021-11-08 (beamah)

Available from: 2021-11-04 Created: 2021-11-04 Last updated: 2023-09-05Bibliographically approved
El-Tawil, A., Björkman, B., Lundgren, M., Bäck, F. & Sundqvist Ökvist, L. (2021). Influence of Modified Bio-Coals on Carbonization and Bio-Coke Reactivity. Metals, 12(1), Article ID 61.
Open this publication in new window or tab >>Influence of Modified Bio-Coals on Carbonization and Bio-Coke Reactivity
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2021 (English)In: Metals, ISSN 2075-4701, Vol. 12, no 1, article id 61Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
bio-coals, washing, kaolin, ash, coking, volatile matter
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-88709 (URN)10.3390/met12010061 (DOI)000747640300001 ()2-s2.0-85121723271 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-01-11 (johcin)

Available from: 2022-01-11 Created: 2022-01-11 Last updated: 2023-09-05Bibliographically approved
Orre, J., Sundqvist Ökvist, L., Bodén, A. & Björkman, B. (2021). Understanding of Blast Furnace Performance with Biomass Introduction. Minerals, 11(2), Article ID 157.
Open this publication in new window or tab >>Understanding of Blast Furnace Performance with Biomass Introduction
2021 (English)In: Minerals, E-ISSN 2075-163X, Vol. 11, no 2, article id 157Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
bio-coal, blast furnace, heat and mass balance, Rist diagram, CDRR diagram
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy; Centre - Centre for Advanced Mining & Metallurgy (CAMM)
Identifiers
urn:nbn:se:ltu:diva-82826 (URN)10.3390/min11020157 (DOI)000622847500001 ()2-s2.0-85100178644 (Scopus ID)
Funder
Luleå University of Technology
Note

Validerad;2021;Nivå 2;2021-02-09 (alebob)

Available from: 2021-02-09 Created: 2021-02-09 Last updated: 2024-01-17Bibliographically approved
Ahmed, H., Sideris, D., Lennartsson, A., Prasad, P. N., Sundqvist Ökvist, L., From, L.-E., . . . Björkman, B. (2020). Effect of the Ash from H2‐Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity. Paper presented at 4th European Steel Technology and Application Days (ESTAD), 24-28 June, 2019, Düsseldorf, Germany. Steel Research International, 91(11), Article ID 2000098.
Open this publication in new window or tab >>Effect of the Ash from H2‐Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity
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2020 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 91, no 11, article id 2000098Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
Keywords
biomass, blast furnace, injection, iron making, plastic
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-79179 (URN)10.1002/srin.202000098 (DOI)000538494300001 ()2-s2.0-85085933072 (Scopus ID)
Conference
4th European Steel Technology and Application Days (ESTAD), 24-28 June, 2019, Düsseldorf, Germany
Funder
Swedish Energy Agency
Note

Godkänd;2020;Nivå 0;2020-11-30 (alebob);Konferensartikel i tidskrift;

Finansiär: CAMM2, Center of Advanced Mining and Metallurgy at LTU;

For correction, see: Ahmed, H., Sideris, D., Lennartsson, A., Prasad, P.N., Sundqvist-Ökvist, L., From, L., Orre, J. and Björkman, B. (2020), Effect of the Ash from H2-Rich Carbonaceous Materials on the Physicochemical Properties of Raceway Slag and Coke Reactivity. steel research int., 91: 2000640. https://doi.org/10.1002/srin.202000640

Available from: 2020-06-04 Created: 2020-06-04 Last updated: 2023-09-05Bibliographically approved
Sar, S., Samuelsson, C., Engström, F. & Sundqvist Ökvist, L. (2020). Experimental Study on the Dissolution Behavior of Calcium Fluoride. Metals, 10(8), Article ID 988.
Open this publication in new window or tab >>Experimental Study on the Dissolution Behavior of Calcium Fluoride
2020 (English)In: Metals, ISSN 2075-4701, Vol. 10, no 8, article id 988Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
dissolution of calcium fluoride, calcium carbonate polymorphism, dehalogenation, double leached Waelz oxide, effect of fluoride during electrowinning
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-80585 (URN)10.3390/met10080988 (DOI)000565619900001 ()2-s2.0-85088289985 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-08-27 (alebob)

Available from: 2020-08-27 Created: 2020-08-27 Last updated: 2023-09-05Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-3363-351x

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