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 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 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 Correction to: “Advanced Method for Recycling Red Mud by Carbothermal Solid-Phase Reduction Using Sodium Sulfate”

Metallurgist ◽  
2020 ◽  
Vol 63 (11-12) ◽  
pp. 1345-1345 ◽  
Author(s):  
P. I. Grudinskii ◽  
D. V. Zinoveev ◽  
A. F. Semenov ◽  
A. S. Zakunov ◽  
V. G. Dyubanov ◽  
...  
Keyword(s):  
Red Mud ◽  
Sodium Sulfate ◽  
Solid Phase ◽  
Advanced Method ◽  
Phase Reduction

Treatment of Red Mud From Alumina Production by High–Intensity Magnetic Separation

1995 ◽  
Vol 6 (4) ◽  
pp. 243-251 ◽  
Author(s):  
Mohamad Fofana ◽  
Stanislav Kmet ◽  
ŠTefan Jakabský ◽  
Slavomír Hredzák ◽  
Gabriel Kunhalmi
Keyword(s):  
Magnetic Separation ◽  
Red Mud ◽  
High Intensity ◽  
Alumina Production

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

2018 ◽  
Vol 2018 (11) ◽  
pp. 1020-1026 ◽  
Author(s):  
P. I. Grudinskii ◽  
V. G. Dyubanov ◽  
D. V. Zinoveev ◽  
M. V. Zheleznyi
Keyword(s):  
Alkali Metal ◽  
Grain Growth ◽  
Red Mud ◽  
Solid Phase ◽  
Metal Salts ◽  
Alkali Metal Salts ◽  
Phase Reduction

Comprehensive Utilization of Red Mud Remaining in Alumina Production

2014 ◽  
Vol 881-883 ◽  
pp. 663-666 ◽  
Author(s):  
Ao Ping He ◽  
Zhi Liu Hu ◽  
De Guang Cao ◽  
Jian Min Zeng ◽  
Bo Lin Wu ◽  
...  
Keyword(s):  
Red Mud ◽  
Aluminum Industry ◽  
Construction Materials ◽  
Environmental Restoration ◽  
Alumina Production ◽  
The Sustainable Development ◽  
Valuable Metals ◽  
High Alkalinity ◽  
Main Factors

Red mud is a solid waste which is generated in the process of alumina production and is of highly alkaline. Red mud has very complex compositions, but contains a variety of rare and valuable metals. In addition, its high alkalinity is a severe pollution to water, land, air and environment, which has been one of the main factors to affect the sustainable development of aluminum industry. The characterization of red mud, the extraction of valuable metals from red mud, the utilization of red mud in construction materials, environmental restoration materials and other fields are introduced in this paper.

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

A Study on The Phase Transformation and Exchange-Coupling of (Nd0 95La0 05)9 5FebalCo5Nb2B10.5 Nanocomposites

1999 ◽  
Vol 577 ◽  
Author(s):  
Q. Chen ◽  
B. M. Ma ◽  
B. Lu ◽  
M. Q. Huang ◽  
D. E. Laughlin
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Phase Transformation ◽  
Thermal Treatment ◽  
Grain Growth ◽  
Exchange Coupling ◽  
Phase Distribution ◽  
Maximum Energy ◽  
Treatment Temperature ◽  
Phase Identification

ABSTRACTThe phase transformation and the exchange coupling in (Ndo095Lao005)9.5FebaICOsNb 2BI05 have been investigated. Nanocomposites were obtained by treating amorphous precursors at temperatures ranging from 650TC to 9500C for 10 minutes. The magnetic properties were characterized via the vibrating sample magnetometer (VSM). X-ray diffraction (XRD), thermomagnetic analysis (TMA), and transmission electron microscopy (TEM) were used to perform phase identification, measure grain size, and analyze phase distribution. The strength of the exchange coupling between the magnetically hard and soft phases in the corresponding nanocomposite was analyzed via the AM-versus-H plot. It was found that the remanence (Br), coercivity (Hci), and maximum energy product (BHmax) obtained were affected by the magnetic phases present as well as the grain size of constituent phases and their distribution. The optimal magnetic performance, BHm, occurred between 700°C to 750°C, where the crystallization has completed without excessive grain growth. TMA and TEM indicated that the system was composed of three phases at this point, Nd2(Fe Co) 14B, ca-Fe, and Fe3B. The exchange coupling interaction among these phases was consistently described via the AM-versus-H plot up to 750°C. The Br, Hci, and BHmax degraded severely when the thermal treatment temperature increased from 750°C. This degradation may be attributed to the grain growth of the main phases, from 45 to 68nm, and the development of precipitates, which grew from 5nm at 750°C to 12nm at 850°C. Moreover, the amount of the precipitates was found to increase with the thermal treatment temperatures. The precipitates, presumably borides, may cause a decrease in the amount of the a-Fe and Fe 3B and result in a redistribution of the Co in the nanocomposites. The increase of the Co content in the Nd 2(Fe Co) 14B may explain the increase of its Curie temperature with the thermal treatment temperatures. In this paper, we examine the impacts of these factors on the magnetic properties of (Ndo 95Lao 05)9 5FebaICosNb2B10.5 nanocomposite.

Recovering metals from red mud by thermal treatment and magnetic separation

JOM ◽  
1996 ◽  
Vol 48 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Paolo Plescia ◽  
Dante Maccari
Keyword(s):  
Thermal Treatment ◽  
Magnetic Separation ◽  
Red Mud
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