Reduction of electric arc furnace dust pellets by simulated reformed natural gas

Junca, Eduardo; Restivo, Thomaz Augusto Guisard; Oliveira, José Roberto de; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto Soares

doi:10.1007/s10973-016-5629-x

Cited by 22 publications

(10 citation statements)

References 42 publications

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“…After this temperature dα/dt showed a significant increase, that is, a greater reduction rate was achieved causing greater mass loss, shown in f1.5 in Figure 9. According to Junca et al, [ 22 ] the change in curve magnitude dα/dt × t suggests a probable changing of the controller mechanism. The possible mechanisms that may control the kinetics of the iron oxide carbothermal reduction reaction are carbon gasification, diffusion of reducing gases through the product layer, or chemical reaction in the product layer.…”

Section: Resultsmentioning

confidence: 99%

Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

et al. 2020

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The volume of tailings produced by the extractive industry has been increasing due to the processing of the low-grade ore. This issue can cause environmental accidents and require significant investment to control the disposal of tailings. Therefore, this study aims to recover iron from zinc mine tailings by wet magnetic separation followed by the carbothermal reduction of self-reducing briquettes. Two magnetic separation routes were investigated to concentrate iron. Zinc mine tailings were processed by route I, in a rougher stage followed by a scavenger stage; and route II, in a rougher stage followed by a cleaner stage. The carbothermal reductions were performed using self-reducing briquettes composed of Fe concentrate from the route with high Fe content and charcoal. The products were analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), x-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), and volumetric chemical analysis. Magnetic separation route II provided the highest-grade Fe concentrate, 52% Fe, while route I provided 33% Fe. In the carbothermal reductions, a metallization degree of 98% in the Fe concentrate briquette, 97% in the briquette with a 10% replacement of its raw material by Fe concentrate, and 99% in the hematite briquette was reached. The replacement of raw material by Fe concentrate showed no significant change in Fe recovery. Considering the whole process, magnetic separation and carbothermal reduction, the recovery of Fe from the zinc mine tailings was 67%. Therefore, the process route suggested in this study will not only reduce tailings disposal and consequently the risk of environmental accidents, but it will also provide profitable raw material for the steel industry.

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Section: Resultsmentioning

confidence: 99%

Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

et al. 2020

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“…In the third step, for a temperature range of 850-950°C, the functions A2, D1, D2, D3, D4, R2 and R3 presented a greater correlation factor, as can be seen in Table 6. In a previous article (Junca et al, 2016), the influence of the pellet diameter during a reduction…”

Section: Kinetic Investigationmentioning

confidence: 97%

“…The EAFD characterization has been published previously (Junca et al, 2012;Junca et al, 2016). Thus, a summary will be mentioned.…”

Section: Eafd Characterizationmentioning

confidence: 99%

Reduction of electric arc furnace dust pellets by mixture containing hydrogen

et al. 2019

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The large amount of dust generated in electric arc furnace aligned with its chemical composition makes this dust a potential source of iron in the direct reduction iron process. Thus, the aim of this research is to investigate the reduction of pellets produced with electric arc furnace dust using hydrogen as the reducing agent. The kinetic investigation was examined applying the differential method. In addition, the influence of reducing gas stream and temperature in the reduction process were investigated applying the Forced Stepwise Isothermal Analysis technique. The temperature studied varied from 500 to 1000°C with isothermals in each 50°C. The reducing gas was a mixture of 10% of hydrogen and 90% of argon. Then, the product characterization was carried out via scanning electron microscope and X-ray analysis. A thermogravimetric test showed a mass loss of 42 wt% due to the reduction of iron and zinc oxides. Besides this, the reduction occurred in three steps: 550-650°C, 700-800°C, 850-950°C. Between 550-650°C, the reduction was controlled by a nucleation mechanism with an Ea of 41.1 kJ/mol. In the second step (700-800°C), a mixed control between nucleation and diffusion was obtained with an Ea of 89.1 kJ/mol. Furthermore, a crust of iron was formed around the pellet, which hindered the reducing gas diffusion into the pellet. In the third stage (850-950°C), the formation of a sintered structure was noted, which decreased pore volume. The internal diffusion of reducing gases was determined as the controlling mechanism, with an Ea of 130.9 kJ/mol.

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“…The presence of zinc ferrite in these residues makes the extraction of zinc and iron difficult as most of the zinc is present in the form of zinc ferrite. Zinc ferrite has been found as the major component of EAFD in several studies [6][7][8]. In the year 2000, 700,000 to 800,000 tons of EAFD were being generated in the USA per year [9].…”

Section: Introductionmentioning

confidence: 99%

“…The slag is usually used as the civil construction material, whereas the Waelz oxide can be further treated through hydrometallurgical or pyro-metallurgical route to obtain zinc metal. Previous studies on the reduction of zinc ferrite reveal that it can be reduced to a mixture of zinc oxide and magnetite at an intermediate range of temperature (450 to 600°C) [6,8]. Antuñano successfully reduced iron oxide in pure ZF to iron while keeping zinc as zinc oxide by using pure H 2 gas as a reductant [12].…”

Section: Introductionmentioning

confidence: 99%

Selective Extraction of Zinc from Zinc Ferrite

Kashyap

Taylor

2020

Mining, Metallurgy & Exploration

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The presence of iron in sphalerite induces the formation of zinc ferrite (ZF) during roasting. Zinc refinery residues (ZRR) and electric arc furnace dust (EAFD) contain a significant amount of zinc ferrite and are difficult to treat. According to the literature, up to 71% ZF has been found to be present in ZRR. The dissolution of zinc ferrite is inefficient even in aqua regia. The Waelz process is an existing process to recover zinc from electric arc furnace dust by reduction using carbon monoxide followed by the volatilization of zinc. In this study, zinc was selectively extracted from zinc ferrite by partial reduction of zinc ferrite at relatively low temperature followed by leaching in dilute sulfuric acid (20 g/L). Pure zinc ferrite samples were partially reduced to zinc oxide and magnetite by using H 2 gas as a reductant. The presence of magnetite and zinc oxide was confirmed by X-ray diffraction (XRD) technique. A maximum of 95% zinc extraction was achieved after leaching with sulfuric acid on the reacted samples. The paper also discusses the effect of time, temperature, and concentration of H 2 in the reducing gas on the extraction of zinc and iron from ZF.

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Reduction of electric arc furnace dust pellets by simulated reformed natural gas

Cited by 22 publications

References 42 publications

Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

Iron recovery from zinc mine tailings by magnetic separation followed by carbothermal reduction of self‐reducing briquettes

Reduction of electric arc furnace dust pellets by mixture containing hydrogen

Selective Extraction of Zinc from Zinc Ferrite

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