Feasibility of Air Classification in Dust Recycling in the Iron and Steel Industry

Lanzerstorfer, Christof; Angerbauer, Albert; Gaßlbauer, Michael

doi:10.1002/srin.201800017

Cited by 7 publications

(5 citation statements)

References 33 publications

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“…The reduction in the number of volatilization cycles Zn has to get through until the required Zn concentration is reached, which can be achieved by air classification of the dust shows large potential to further increase the feasibility of such BOF dust recycling. The cost of air classification of dusts strongly depend on the throughput of the classification system . Thus, the profitability of the application of air classification has to be investigated separately for individual steel mills.…”

Section: Resultsmentioning

confidence: 99%

Zinc Enrichment in In‐Plant Electrostatic Precipitator Dust Recycling by Air Classification in Converter Steelmaking

Lanzerstorfer¹

2018

steel research int.

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Steelmaking in a basic oxygen furnace generates a considerable amount of dust, which is separated in a growing number of plants by dry de‐dusting systems. This dust is rich in Fe and therefore, suitable for recycling within the steel mill. Because of the elevated Zn content recycling via the sintering process is often not feasible. Therefore, several steel mills apply in‐plant dust recycling where the dust is recycled back into the furnace. Thereby, the Zn content of the dust increases steadily until the desired concentration in the dust for discharge is reached. In this procedure, the Zn atoms in the dust are circulated several times consuming energy and reduction agent for the volatilization each time. Classification experiments with basic oxygen furnace dust performed in this study show a certain dependence of the Zn concentration on the particles size. This size dependence is exploited by introducing an air classification step into the recycling process. The calculations for this novel process show that the required average number of times a Zn atom has to be volatilized and can be reduced by 35–72% depending on the underlying circumstances. Thus, the energy and reduction agent consumption required for dust recycling can be reduced substantially.

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Section: Resultsmentioning

confidence: 99%

Zinc Enrichment in In‐Plant Electrostatic Precipitator Dust Recycling by Air Classification in Converter Steelmaking

Lanzerstorfer¹

2018

steel research int.

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“…A number of efforts are undertaken to process the residual materials and to reuse them for other purposes, to recover valuable materials, or to return them to the process after treatment. [5,[7][8][9] This article deals with the treatment options for residues created especially during the Midrex direct reduction process. The factors that determine the mass of iron oxide pellets required to produce 1 ton of DRI in the Midrex process include the loss of oxygen through the reduction, the addition of carbon, oxide fines losses from screening, the processing of the iron oxide pellets in the reduction furnace, and the screening of DRI/HBI products.…”

Section: Residues and Recycling Possibilitiesmentioning

confidence: 99%

Investigation into the Hot Briquetting of Fine‐Grained Residual Materials from Iron and Steel Production

Lohmeier

Wollenberg

Schröder

2020

steel research int.

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Hot briquetting tests with mixtures of direct reduced iron (DRI) pellets and residues of the Midrex direct reduction process are conducted on a hydraulic piston press with a closed die. The trials seek to test the feasibility of recycling these residues by introducing them directly into hot briquetted iron (HBI). The inclusion of residues is possible if a high pressure of 350 MPa and a high briquetting temperature of 800 °C are applied. It is ascertained that up to 20 wt% of the HBI can consist of residues and still meet the quality requirements for the safe transportation to the steel plant if the mixture contains sufficient HBI screened fines and HBI classifier dust. Under such conditions, the HBI briquettes have a compressive strength of >300 MPa, an abrasion resistance of >80%, and, most importantly, an apparent density of >5 g cm−3. It is further shown that the hot briquetting of Midrex residues is also possible without DRI pellets so that they can be reused as educt in the Midrex direct reduction process.

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“…The cast house dust is emitted into the cast house of a blast furnace as a consequence of the casting of liquid iron and slag [11]. Conventionally, around 2.8 kg of cast house dust are produced per ton of hot metal [12]. Since cast house dust is commonly recycled to the sinter process, elevated zinc concentrations in the cast house dust would make it difficult to fully recirculate blast furnace flue gas dust, as its recirculation will favor the zinc enrichment in the system.…”

Section: Introductionmentioning

confidence: 99%

Bioleaching of Zinc from Blast Furnace Cast House Dust

Sasiain,

Thallner,

Habermaier

et al. 2023

Minerals

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Metallurgical dusts are by-products from steel manufacturing. The high iron content of cast house dust (~64%) makes this by-product an interesting iron feedstock alternative. Therefore, its return into the internal steelmaking circuit, specifically in the sinter plant, is a common practice in the steel industry. However, this dust fraction also contains heavy metals, as zinc. As a result of the re-entry of zinc into the process, the zinc concentration in the blast furnace flue gas dust also increases. This prevents the full recirculation of the blast furnace flue gas dust in the steelmaking process despite its relatively high iron content (~35%), thus causing part of the blast furnace flue gas dust to end in the landfill. The goal of this study was to investigate the usage of bacteria, such as the sulfur oxidizing Acidithiobacillus thiooxidans or the iron and sulfur oxidizing Acidithiobacillus ferrooxidans, to leach the undesirable element zinc from the cast house dust while preventing the leaching of iron, by adjusting the sulfur addition and avoiding, at the same time, the accumulation of sulfur in the solid fraction. Experiments proved that a co-culture of A. thiooxidans and A. ferrooxidans can effectively leach zinc from metallurgical dusts, maintaining high iron concentrations in the material. The influence of elemental sulfur on the efficiencies reached was shown, since higher removal efficiencies were achieved with increasing sulfur concentrations. Maximum zinc leaching efficiencies of ~63% (w/w) and an iron enrichment of ~7% (w/w) in the remaining residue were achieved with sulfur concentrations of 15 g/L for cast house gas concentrations of 125 g/L.

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Feasibility of Air Classification in Dust Recycling in the Iron and Steel Industry

Cited by 7 publications

References 33 publications

Zinc Enrichment in In‐Plant Electrostatic Precipitator Dust Recycling by Air Classification in Converter Steelmaking

Zinc Enrichment in In‐Plant Electrostatic Precipitator Dust Recycling by Air Classification in Converter Steelmaking

Investigation into the Hot Briquetting of Fine‐Grained Residual Materials from Iron and Steel Production

Bioleaching of Zinc from Blast Furnace Cast House Dust

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