| 1. |
- Larsson, Mikael, et al.
(författare)
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Improved energy and material efficiency using new tools for global optimisation of residue material flows
- 2006
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Ingår i: International Journal of Green Energy. - : Informa UK Limited. - 1543-5075 .- 1543-5083. ; 3:2, s. 127-137
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Tidskriftsartikel (refereegranskat)abstract
- Residue materials generated in the metallurgical industry have gained an increasing importance, both from the points of view of energy and material supply. A joint process integration model for the integrated steel plant system is developed and used in this paper. It takes into account both residue materials and energy recirculation for the system. The potential for increased recirculation and the effect on the system from an environmental point of view is presented, and implementations and practical experiences are discussed. The model developed can serve as a benchmark for different steelmaking operations and constitute a basis for the continuous work involved in material, energy, environment or economic analyses for the steel production system.
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| 2. |
- Lindblom, Bo, et al.
(författare)
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Fine-particle characterization an important recycling tool
- 2002
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Ingår i: JOM. - 1047-4838 .- 1543-1851. ; 54:12, s. 35-38
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the results from different research projects on fine-particle characterization of metallurgical residues, such as hydroxide sludge, electric-arc, furnace dust, and copper-converter dust. These studies demonstrated that characterization is essential for developing new recycling strategies. The basic knowledge of the chemical and physical properties of the residues obtained by the characterizations also provides necessary information on potential problems that could be encountered during the processing of such materials.
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| 3. |
- Lundkvist, Katarina, et al.
(författare)
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Optimisation of a centralised recycling system for steel plant by-products, a logistics perspective
- 2013
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Ingår i: Resources, Conservation and Recycling. - : Elsevier BV. - 0921-3449 .- 1879-0658. ; 77, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the optimisation of a recovery strategy for waste materials and thereby improved material efficiency in the iron and steel industry. A joint venture between four Nordic steel plants is considered in order to recycle materials otherwise mainly put to landfill, i.e. dusts and sludges from the steel production processes. Process integration (PI) was used to investigate the possibilities for recovering the materials by developing a system optimisation model of the steel plants and integrating a dedicated material upgrading process in the system. This work aims to develop a model suitable for analysing and finding a logistic solution needed to achieve a common recycling system by studying material supply, required material storage, shipping system and shipping frequency. The developed optimisation model is presented, using a case study of the steel production plants with the dedicated upgrading process and the logistics system. The prospect for shipping materials from the steel production sites to the material upgrading process site as well as the material supply to the upgrading unit is essential in the system analysis. A mathematical optimisation model based on mixed-integer linear programming (MILP) for the common system is presented. The integration of the dedicated material upgrading process show a system in balance regarding the materials generated and processed in the upgrading unit. Generated material amounts suitable for the upgrading process can be fully recovered thereby decreasing the landfilled amounts from the four steel production sites.
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| 4. |
- Lundkvist, Katarina, et al.
(författare)
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System analysis of slag utilisation from vanadium recovery in an integrated steel plant
- 2013
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 47, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- Vanadium in raw materials used in iron- and steelmaking, a particular challenge for Nordic steel producers, affects the composition of the generated slag from the steelmaking vessel, i.e. The basic oxygen furnace (BOF) adversely and reduces the potential for recycling and external utilisation. A process concept under development aims to enrich and extract the vanadium content of slag from the BOF, making use of the vanadium in the slag and also increasing the overall slag use potential. Applications of this concept affect slag compositions and internal material flows in the iron and steel production system, especially when recycling BOF slags as flux in the blast furnace (BF). This paper will present a case study, based on a Process Integration (PI) approach, using a designated system model to simulate the steel production system and the implementation of the process concept, thereby analysing how to obtain maximum usage of metallurgical slags without compromising the quality of the main product, i.e. liquid steel. Different approaches were studied to improve the environmental sustainability in the production system by maximising the material efficiency through vanadium recovery (as FeV alloy) and the use of slags, thereby minimising the stored/deposited slag amounts.
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| 5. |
- Andersson, Anton, et al.
(författare)
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Characterization and Upgrading of a Low Zinc-Containing and Fine Blast Furnace Sludge : A Multi-Objective Analysis
- 2017
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Ingår i: ISIJ International. - : The Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 57:2, s. 262-271
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Tidskriftsartikel (refereegranskat)abstract
- Ore-based steelmaking generates a variety of residues including dusts, sludges and slags. Recycling of these residues within the process or via other applications is essential for sustainable production from both environmental and economic aspects. In blast furnace (BF) ironmaking, there are generally two residues leaving the gas cleaning equipment; namely, BF dust and BF sludge. Traditionally, the dust is recycled via the sinter or, in the case of pellet based BF, via cold bonded agglomerates and injection. As the main output of zinc from the BF is the top gas, the sludge has to be dezinced prior to recycling to prevent accumulation of zinc in the furnace. Although dezincing of BF sludge has been successfully accomplished using e.g., hydrocycloning, the studied sludges are generally coarse sized and high in zinc. Furthermore, information is lacking regarding the efficiency of separation of different hydrocyclone setups. In the present work, hydrocycloning of a fine sludge, with low zinc content, generated by a pellet based BF has been studied. The gas cleaning equipment used to produce the sludge was running a primary aerocyclone and a scrubber. A characterization of the sludge has been conducted together with an evaluation of the separation efficiency of the hydrocyclone in order to assess the hydrocyclone performance and limitations. Furthermore, the dezincing using the hydrocyclone has been compared to that of sulfuric acid leaching. The results suggest that 51 to 93% of the sludge can be recycled depending on the demand on zinc removal and the chosen dezincing route.
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| 6. |
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| 7. |
- Andersson, Anton, et al.
(författare)
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Characterization of Blast Furnace Sludge and Upgrading Using Physical Separation and Leaching
- 2017
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Konferensbidrag (refereegranskat)abstract
- The on-site sinter plants of the Swedish ore based steel industry are all closed. Instead of using sinter, the blast furnaces (BF) operate on iron ore pellets and the major part of the recycling of in-plant residues is realized via cold bonded briquettes charged to the BF. Cost of raw materials and energy continuously drives the work towards an increased recycling of in plant residues. The major part of the zinc entering the BF leaves through the top gas ending up in the BF dust and sludge. The recycling of all the BF dust back to the BF leaves the BF sludge as the main bleed of zinc out of the system. In order to utilize the iron and carbon content of the sludge, means to remove zinc is required prior to recycling via the briquette. In the present work, blast furnace sludge has been characterized. Using the characterization as standpoint, different operations for zinc removal was suggested and studied in laboratory scale. Zinc was successfully removed using a hydrometallurgical and physical separation route, respectively. A successful dezincing operation would enable the recycling of the sludge. This would improve the material- and energy efficiency and substantially decrease the amount of sludge being landfilled.
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| 8. |
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| 9. |
- Andersson, Anton
(författare)
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Recycling of Blast Furnace Sludge within the Integrated Steel Plant : Potential for Complete Recycling and Influence on Operation
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ore-based steelmaking generates various residues including dust, sludges, scales and slags. Internal and external recycling has allowed for 68-90 % of the dust, sludges and scales to be recycled. However, several residues are landfilled despite containing elements valuable as raw material in the production of steel. One such residue is the blast furnace (BF) sludge which has a chemical composition dominated by iron and carbon. In 2008, the annual worldwide landfilling of BF sludge was estimated to 8 million metric tons in dry weight. Furthermore, as the iron production via the BF route has increased significantly since 2008, the landfilling of BF sludge could be even higher as of today. Thus, the potential to reclaim valuable iron and carbon while improving the raw material efficiency is substantial.Traditionally, in-plant recycling of residues generated in the integrated steel plant is conducted via the sinter or, in the case of pellet-based BFs, via cold-bonded briquettes and injection in the BF tuyeres. The challenges in recycling BF sludge via these routes are the fine particle size distribution, the high water content and the zinc content. Of these challenges, the latter is the main concern as too high zinc loads in the BF lead to increased reductant rates, reduced lining life of carbon-based bricks and scaffold formation, which may disturb the process. The challenge regarding zinc has previously been addressed by pretreating the sludge, generating a low-zinc and high-zinc fraction where the former has been recycled to the BF via the sinter or cold-bonded pellets. Although pretreatment and recycling of the low-zinc fraction have been achieved in industrial scale, the reported sludges are generally coarse in size and high in zinc. Furthermore, recycling of pretreated BF sludge to the BF utilizing cold-bonded briquettes has not been reported and the internal recycling of the high-zinc fraction has not been considered.In the present thesis, newly produced BF sludge with a fine particle size distribution and low zinc content was characterized finding that a majority of the zinc was present in weak acid soluble phases and that the finest fraction of the sludge carried most of the zinc. Based on these findings, the BF sludge was pretreated using sulfuric acid leaching, hydrocycloning and tornado treatment, respectively. Sulfuric acid leaching was the most effective method in selectively separating zinc from the iron, carbon and solids. However, both hydrocycloning and tornado treatment were successful in generating a fraction low in zinc.The low-zinc fraction of the tornado-treated BF sludge was incorporated in cold-bonded briquettes and tested for strength, swelling and intrinsic reducibility. Furthermore, the briquettes were charged as basket samples in the LKAB Experimental Blast Furnace (EBF) in order to study the behavior in actual BF conditions. The results suggested that the low-zinc fraction of the BF sludge could be added to the briquettes without negatively affecting the performance of the briquettes in the BF. The results were confirmed in industrial-scale trials where non-treated BF sludge was added to cold-bonded briquettes in an amount that would facilitate complete recycling of the low-zinc fraction. Charging these briquettes to the BF did not induce any negative effects on the process or the hot metal (HM) quality.The high-zinc fraction of the tornado-treated BF sludge was added in self-reducing cold-bonded agglomerates and studied in technical-scale smelting reduction experiments aiming at recycling to the HM desulfurization plant. The experiments suggested that melt-in problems could be expected when using either briquettes or pellets. Nonetheless, industrial-scale trials were performed aiming to study the feasibility of recycling cold-bonded briquettes to both the HM desulfurization plant and basic oxygen furnace (BOF). These trials suggested that a substantial amount could be recycled without affecting the final quality of the steel. However, additional experiments were identified to be required in order to enable 100 % recycling of the high-zinc fraction of the tornado-treated BF sludge.Based on the results from the experimental work, a holistic concept to completely recycle the BF sludge within the integrated steel plant was suggested.
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| 10. |
- Andersson, Anton, et al.
(författare)
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Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes
- 2019
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; :3, s. 350-361
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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