Solid-Phase Reduction and Iron Grain Growth in Red Mud in the Presence of Alkali Metal Salts

Grudinskii, P. I.; Dyubanov, V. G.; Zinoveev, Dmitry; Железный, М. В.

doi:10.1134/s0036029518110071

Cited by 12 publications

(10 citation statements)

References 9 publications

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“…It should be noted that Boudouard-Bell reaction regenerates carbon monoxide above 700 • C [45], so Reaction (6) was actually a total reaction of the following interactions: Figure 2 shows the equilibrium amounts of iron containing phases as a function of the roasting temperature during the carbothermic reduction of red mud. It can be seen that full reduction of iron into the metallic form according to Reactions (3)-(11) was possible above 710 • C. However, a previous experimental study [33] pointed out that a high iron metallization degree after the carbothermic reduction of red mud can be achieved only at temperatures above 1050 • C.…”

Section: Magnetic Separationmentioning

confidence: 93%

“…It can be seen that full reduction of iron into the metallic form according to Reactions (3)-(11) was possible above 710 °C. However, a previous experimental study [33] pointed out that a high iron metallization degree after the carbothermic reduction of red mud can be achieved only at temperatures above 1050 °C. Figure 3 shows the effect of Na2CO3 addition on the equilibrium behavior of iron-free phases at 1100 °C.…”

Section: Magnetic Separationmentioning

confidence: 97%

“…Many authors showed that addition of sodium salts promotes the iron grain growth during carbothermic reduction, for example for limonite (FeO(OH)•nH 2 O) [24], titanomagnetite (Fe 2+ (Fe 3+ ,Ti) 2 O 4 ) [25], siderite (FeCO 3 ) [26], and nickeliferous laterite ((Fe,Ni)O•OH) [27] ores. It was reported [28][29][30][31][32][33][34][35][36][37] that the addition of sodium salts such as sodium sulfate (Na 2 SO 4 ), sodium carbonate (Na 2 CO 3 ), and sodium tetraborate (Na 2 B 4 O 7 ) also improves the segregation of metallic iron during the carbothermic reduction of red mud. The addition of Na 2 SO 4 during the carbothermic reduction of high phosphorus oolitic hematite ore promotes iron (II) sulfide' (FeS) generation [38], which increases the sulfur content in the metallic concentrate, so the use of sodium sulfate is less desired compared with other sodium salts.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

Zinoveev

Grudinsky

Zakunov

et al. 2019

Metals

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Red mud is a by-product of alumina production from bauxite ore by the Bayer method, which contains considerable amounts of valuable components such as iron, aluminum, titanium, and scandium. In this study, an approach was applied to extract iron, i.e., carbothermic reduction roasting of red mud with sodium and potassium carbonates followed by magnetic separation. The thermodynamic analysis of iron and iron-free components’ behavior during carbothermic reduction was carried out by HSC Chemistry 9.98 (Outotec, Pori, Finland) and FactSage 7.1 (Thermfact, Montreal, Canada; GTT-Technologies, Herzogenrath, Germany) software. The effects of the alkaline carbonates’ addition, as well as duration and temperature of roasting on the iron metallization degree, iron grains’ size, and magnetic separation process were investigated experimentally. The best conditions for the reduction roasting were found to be as follows: 22.01% of K2CO3 addition, 1250 °C, and 180 min of duration. As a generalization of the obtained data, the mechanism of alkaline carbonates’ influence on iron grain growth was proposed.

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Section: Magnetic Separationmentioning

confidence: 93%

Section: Magnetic Separationmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

Zinoveev

Grudinsky

Zakunov

et al. 2019

Metals

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“…The obtained samples were studied by Mössbauer, X-ray diffraction, optical and electron microscopic methods. The experimental procedure and analysis of results are presented in more detail in [13].…”

Section: Kne Materials Sciencementioning

confidence: 99%

The Research of the Carbothermic Solid–Phase Red Mud Reduction Process in the Presence of Sodium Sulphate

Zinoveev

Grudinsky

Semenov

et al. 2020

Kms

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Russia has accumulated about 600 million tons of the red mud that is alumina production waste generated by Bayer method, but currently only a small amount of the total accumulated red mud is recycled. Solid–phase carbothermic reduction of red mud in the presence of sodium salts with magnetic separation can be a promising method for iron extraction. In this paper, the effect of the addition of sodium sulphate on the reduction of iron–containing phases and the growth of iron grains during solid–phase carbothermic reduction of red mud was investigated. The results show that 10% sodium sulphate additive significantly accelerate the growth of reduced iron grains, but decrease the degree of its reduction at temperatures above 1100∘C. The explanation of mechanism of sodium sulphate effect on the iron grain growth was proposed. Optimization of sodium sulphate amount, temperature and holding time can lead the development of effective technology of iron extraction from red mud by solid–phase carbothermic reduction. Keywords: red mud, solid–phase carbothermic reduction, sodium sulphate

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“…The yield of the non-magnetic fraction was 85.77 wt %. The carbon concentrate can be reused for combustion in thermal power plants or as an additive in metallurgical processes, for example, when replacing coal or hydrogen flow in the reductive roasting of magnetite pellets and red mud at temperatures below 1000 • C [30][31][32]. Based on the results of research, the following flowsheet of the CFA enrichment process using wet magnetic separation and flotation is suggested (Figure 11).…”

Section: Carbon Flotation Of the Non-magnetic Fraction Of Cfamentioning

confidence: 99%

Magnetite and Carbon Extraction from Coal Fly Ash Using Magnetic Separation and Flotation Methods

et al. 2019

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In this study, enrichment methods for coal fly ash (CFA) from Omsk thermal power station No. 4 (TPS-4) were investigated. The magnetite and unburned carbon concentrates were obtained by magnetic separation and flotation methods. The wet magnetic separation used in the study increased the magnetite content in the magnetic fraction from 10.48 to 12.72 wt % compared to dry magnetic separation. The XRD analysis showed that the magnetic fraction primarily consists of magnetite, mullite, and quartz. The SEM analysis demonstrated that magnetite is located primarily on the surface of alumosilicate spheres and has three types of shape: dendritic structures, hexagonal bulk agglomerates, and star-like structures. For the flotation tests, a low-price diesel was used as the collector. It was found that, if CFA particles of 40–71 µm are used, ~99% of unburned carbon can be recovered. It was also found by SEM that, if CFA particles of 71–100 µm are used, alumosilicates on a carbon surface prevent complete interaction of diesel with carbon particles and decrease thereby carbon recovery to 83%.

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Solid-Phase Reduction and Iron Grain Growth in Red Mud in the Presence of Alkali Metal Salts

Cited by 12 publications

References 9 publications

Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

Influence of Na2CO3 and K2CO3 Addition on Iron Grain Growth during Carbothermic Reduction of Red Mud

The Research of the Carbothermic Solid–Phase Red Mud Reduction Process in the Presence of Sodium Sulphate

Magnetite and Carbon Extraction from Coal Fly Ash Using Magnetic Separation and Flotation Methods

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