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

2020 ◽  
Author(s):  
Dmitry Zinoveev ◽  
Pavel Grudinsky ◽  
Artem Semenov ◽  
Valery Dyubanov ◽  
Alexander Petelin
Keyword(s):  
Red Mud ◽  
Carbothermic Reduction ◽  
Solid Phase ◽  
Reduction Process ◽  
Sodium Sulphate ◽  
Alumina Production ◽  
Sodium Salts ◽  
Iron Extraction ◽  
Reduction Of Iron ◽  
Effective Technology

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

scholarly journals Extraction of Iron from Russian Red Mud by a Carbothermic Reduction and Magnetic Separation Process

2021 ◽  
Vol 3 (1) ◽  
pp. 23
Author(s):  
Dmitry Zinoveev ◽  
Alexander Petelin ◽  
Pavel Grudinsky ◽  
Andrey Zakunov ◽  
Valery Dyubanov
Keyword(s):  
Experimental Data ◽  
Magnetic Separation ◽  
Grain Growth ◽  
Red Mud ◽  
Carbothermic Reduction ◽  
Iron Reduction ◽  
Solid Phase ◽  
Reduction Process ◽  
Alumina Production ◽  
Average Size

Red mud is a hazardous waste of alumina production. Currently, the total accumulated amount of red mud is over 4 billion tons. The promising method of red mud processing is a carbothermic reduction of iron at 1000–1400 °C into metallic form followed by magnetic separation. In this study, the mechanism of carbothermic solid-phase reduction of red mud was investigated. Based on the experimental data, the two-step mechanism of the first rapid stage of the process was proposed, which leads to almost full iron reduction. The estimated value of activation energy has indicated that solid-phase diffusion is a rate-controlling step for this stage. However, an almost full reduction is necessary, but insufficient factor for successful magnetic separation. The second crucial factor of the process is enlargement of iron grain size, which leads to gangue-grain release during grinding and increases efficiency of the magnetic separation. The prediction model of iron grain growth process during the carbothermic reduction process was suggested. The calculation of average size of iron grains formed during the reduction process that was performed according to the assumption of diffusion-controlled process showed their correlation with experimental data. Various methods were proposed to promote the process of iron grain growth during carbothermic reduction of red mud.

scholarly journals Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1571
Author(s):  
Pavel Grudinsky ◽  
Dmitry Zinoveev ◽  
Denis Pankratov ◽  
Artem Semenov ◽  
Maria Panova ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Grain Growth ◽  
Red Mud ◽  
Sodium Sulfate ◽  
Phase Distribution ◽  
Solid Phase ◽  
Alumina Production ◽  
Metallic Particles ◽  
Iron Phase ◽  
High Alkalinity

Red mud is an iron-containing waste of alumina production with high alkalinity. A promising approach for its recycling is solid-phase carbothermic roasting in the presence of special additives followed by magnetic separation. The crucial factor of the separation of the obtained iron metallic particles from gangue is sufficiently large iron grains. This study focuses on the influence of Na2SO4 addition on iron grain growth during carbothermic roasting of two red mud samples with different (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21, respectively. Iron phase distribution in the red mud and roasted samples were investigated in detail by Mössbauer spectroscopy method. Based on thermodynamic calculations and results of multifactorial experiments, the optimal conditions for the roasting of the red mud samples with (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21 were duration of 180 min with the addition of 13.65% Na2SO4 at 1150 °C and 1350 °C followed by magnetic separation that led to 97% and 83.91% of iron recovery, as well as 51.6% and 83.7% of iron grade, respectively. The mechanism of sodium sulfate effect on iron grain growth was proposed. The results pointed out that Na2SO4 addition is unfavorable for the red mud carbothermic roasting compared with other alkaline sulfur-free additives.

scholarly journals Distribution of solid-phase reduction of iron in a layer of ilmenite concentrate

2020 ◽  
Vol 63 (2) ◽  
pp. 116-121
Author(s):  
K. I. Smirnov ◽  
P. A. Gamov ◽  
V. E. Roshchin
Keyword(s):  
Iron Reduction ◽  
Solid Phase ◽  
Point Contact ◽  
Reduction Process ◽  
Reducing Agent ◽  
Metal Phase ◽  
Contact Boundary ◽  
Silicate Phase ◽  
Ilmenite Concentrate ◽  
Reduction Of Iron

Processing of titanium-containing ores with extraction of all the major elements is an urgent task of minerals rational use. It is shown that none of the existing processing schemes allows extracting of all the major useful elements at the same time from titanium-containing iron ores, i.e. – iron, titanium and vanadium. This problem can be solved using selective extraction of these elements based on new ideas about electronic reduction mechanism. Propagation of the process of solid-phase selective reduction of iron with the powder of carbon-containing material deep into the layer of grains of ilmenite concentrate from the surface of its contact was experimentally studied. The results of determining the amount of metal phase released as it moves away from the concentrate – reducing agent contact boundary are presented. Based on the results concerning amount of precipitated metal phase, a conclusion was made about diffusion processes in a layer of concentrate grains contacting only between themselves, limiting process of iron reduction. It is shown that near the plane of contact of solid reducing agent with the layer of concentrate grains, the rate of iron reduction is higher than the rate of high iron content phase precipitation from ilmenite. In depth of ilmenite concentrate layer, process of iron reduction is preceded by formation of iron-containing silicate phase from concentrate grains, where iron is reduced earlier than in ilmenite grains. Formation of iron-containing silicate phase contributes ilmenite grains sintering. It was concluded that in the concentrate layer in contact with solid reducing agent layer in absence of contact of each ilmenite grain with solid reducing agent, the point contact of grains and presence of voids between them in the layer do not prevent propagation of reduction process in the layer of grains contacting with each other only.

scholarly journals Effect of gas composition and temperature on reduction characteristic in red mud-coal composite pellets

2019 ◽  
Vol 23 (5 Part A) ◽  
pp. 2561-2568
Author(s):  
Yi Man ◽  
Jun-Xiao Feng ◽  
Zhan-Min Yang ◽  
Zeng-Lu Song ◽  
Chao Yang
Keyword(s):  
Red Mud ◽  
Reduction Process ◽  
Gas Composition ◽  
X Ray Diffraction ◽  
Alumina Production ◽  
X Ray ◽  
N2 Atmosphere ◽  
Composite Pellets ◽  
Optimum Reaction ◽  
Bayer Red Mud

The disposal of red mud, which is the by-product obtained from alumina production, has brought about environmental pollution because of its caustic nature as well its metal and alkaline contents. Red mud-coal composite pellets were directly reduced to deal with red mud. The influences of reduction temperature and gas composition on the reaction were studied. Experiment results indicated that the optimum reaction parameters were a temperature of 1100?C and an H2 atmosphere. Reduction degrees in H2 and CO atmospheres were significantly higher than those in N2 atmosphere. Reduction did not strictly follow the Fe2O3 ? Fe3O4 ? FeO ? Fe sequence in N2 atmosphere, and this phenomenondid not occur in H2 atmosphere. This gas?solid combination reduction process is appropriate for recovering Fe from Bayer red mud. Meanwhile, the microstructure and phase transformation of the reduction process were investigated via scanning electron microscopy and X-ray diffraction.

Solid-Phase Reduction of Iron from Suroyam Titanomagnetite Ore during Metallization in Rotary Kiln

2019 ◽  
Vol 946 ◽  
pp. 512-516
Author(s):  
K.I. Smirnov ◽  
S.P. Salikhov ◽  
V.E. Roshchin
Keyword(s):  
Electron Microscope ◽  
Melting Point ◽  
Rotary Kiln ◽  
Solid Phase ◽  
Reduction Process ◽  
Reducing Agent ◽  
Continuous Processing ◽  
Phase Reduction ◽  
Reduction Of Iron ◽  
Electron Microscope Analysis

In this work the solid-phase reduction of iron from the Suroyam titanomagnetite ore was studied during metallization in a rotary kiln. The technique of preparation of the ore and reducing agent for metallization and the process of continuous processing of materials in a rotary kiln were described in detail. For metallization the temperature was chosen 1150°C, due to low melting point of apatite from one of the components. The results of the electron microscope analysis of the initial ore and samples subjected to metallization for 1-hour reduction time were presented. The reduction of iron occurred despite absence of pores and contact with a reducing agent in the grains of titanomagnetite. Iron in the grains of titanomagnetite surrounded by apatite was reduced to wustite; whereas, iron surrounded by clinopyroxene was reduced to metallic iron. This indicated the effect of composition of the gangue materials on the reduction process.

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

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1313 ◽  
Author(s):  
Dmitry Zinoveev ◽  
Pavel Grudinsky ◽  
Andrey Zakunov ◽  
Artem Semenov ◽  
Maria Panova ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Grain Growth ◽  
Red Mud ◽  
Carbothermic Reduction ◽  
Reduction Roasting ◽  
Alumina Production ◽  
Iron Aluminum ◽  
Bauxite Ore ◽  
Hsc Chemistry ◽  
Sodium And Potassium

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.

scholarly journals High Temperature Dielectric Properties of Iron- and Zinc-Bearing Products during Carbothermic Reduction by Microwave Heating

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 693
Author(s):  
Beatriz García-Baños ◽  
Jose M. Catalá-Civera ◽  
Juan R. Sánchez ◽  
Laura Navarrete ◽  
Angel M. López-Buendía ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Microwave Heating ◽  
Carbothermic Reduction ◽  
Accurate Determination ◽  
Reduction Process ◽  
Carbonaceous Material ◽  
Scanning Calorimetry ◽  
Reduction Of Iron ◽  
Iron And Zinc ◽  
New Evidence

In this work, the carbothermic reduction of iron- and zinc-bearing products is studied through in situ microwave heating, dielectric properties monitoring, and mass spectrometry up to high temperatures (1000 °C). The results are correlated to the information provided by conventional analysis techniques such as differential scanning calorimetry (DSC) and thermogravimetry (TG). This combination allows a detailed study of seven different process stages with an accurate determination of the reaction temperatures, providing new evidence about the particular conditions of this microwave-driven reduction process. The presented results suggest that molecular vibrations imposed by the microwave field are presumably the reason for reactions taking place at lower temperatures than those observed in the conventional process. This work also explores the influence of other parameters, such as the apparent density or the amount of carbonaceous material, on the resulting dielectric properties, providing useful information for the development of a potential microwave industrial application in the metallurgy field.

Metallographic Estimation of the Number of Forming Metallic Particles Obtained during Direct and Indirect Reduction of Metals from Complex Oxides

2019 ◽  
Vol 946 ◽  
pp. 523-527
Author(s):  
Arman S. Bilgenov ◽  
P.A. Gamov ◽  
V.E. Roshchin
Keyword(s):  
Metal Forming ◽  
Solid Phase ◽  
Quantitative Estimation ◽  
Direct Reduction ◽  
Reduction Process ◽  
Complex Oxide ◽  
Experimental Results ◽  
Solid Carbon ◽  
Indirect Reduction ◽  
Co Gas

The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.

Reduction of iron oxides during the pyrometallurgical processing of red mud

2013 ◽  
Vol 2013 (1) ◽  
pp. 33-37 ◽  
Author(s):  
N. A. Raspopov ◽  
V. P. Korneev ◽  
V. V. Averin ◽  
Yu. A. Lainer ◽  
D. V. Zinoveev ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Red Mud ◽  
Reduction Of Iron ◽  
Pyrometallurgical Processing
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