Recovery of Iron from Copper Slag Using Coal-Based Direct Reduction: Reduction Characteristics and Kinetics

The Fe3O4 and Fe2SiO4 in copper slag were successfully reduced to metallic iron by coal-based direct reduction. Under the best reduction conditions of 1300 °C reduction temperature, 30 min reduction time, 35 wt.% coal dosage, and 20 wt.% CaO dosage (0.75 binary basicity), the Fe grade of obtained iron concentration achieved 91.55%, and the Fe recovery was 98.13%. The kinetic studies on reduction indicated that the reduction of copper slag was controlled by the interfacial reaction and carbon gasification at 1050 °C. When at a higher reduction temperature, the copper slag reduction was controlled by the diffusion of the gas. The integral kinetics model research illustrated that the reaction activation energy increased as the reduction of copper slag proceeded. The early reduction of Fe3O4 needed a low reaction activation energy. The subsequent reduction of Fe2SiO4 needed higher reaction activation energy compared with that of Fe3O4 reduction.

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A study of direct reduction characteristics of Bayer process red mud-coal composite pellets

Thermal Science ◽

10.2298/tsci181123145m ◽

2019 ◽

Vol 23 (5 Part A) ◽

pp. 2569-2576

Author(s):

Yi Man ◽

Jun-Xiao Feng ◽

Yan-Yang Wang

Keyword(s):

Red Mud ◽

Direct Reduction ◽

Reduction Rate ◽

Reduction Reaction ◽

Reduction Temperature ◽

Different Temperatures ◽

Composite Pellets ◽

Iron Phase ◽

Reduction Characteristics ◽

High Degree

The effects of reduction temperature, particle size, pellet diameter, and the ratio on the reduction rate in red mud-coal composite pellets were studied. The iron phase change of the reduction under different temperatures was analyzed applying X-ray diffraction technique. The microstructure of reduction was investigated using scanning electron microscope. The conclusion of the study is that the reduction reaction rate increased rapidly with the increase of reduction temperature. The reduction of Fe2O3 forming Fe3O4 started under 700?. At 1100?, the red mud-coal composite pellets with carbon and oxygen mole ratio 1:1 obtained a good reduction result. The appearance of metal iron and the clear porous structure indicated that the reduction had developed to a high degree.

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Reduction Kinetics of Hematite Powder in Hydrogen Atmosphere at Moderate Temperatures

Metals ◽

10.3390/met8100751 ◽

2018 ◽

Vol 8 (10) ◽

pp. 751 ◽

Cited By ~ 5

Author(s):

Zhiyuan Chen ◽

Jie Dang ◽

Xiaojun Hu ◽

Hongyan Yan

Keyword(s):

Activation Energy ◽

Direct Reduction ◽

Reduction Process ◽

Kinetic Mechanism ◽

Hydrogen Atmosphere ◽

Morphological Transformation ◽

Iron And Steel ◽

Multi Stage ◽

Reduction Of Iron ◽

Direct Reduction Of Iron

Hydrogen has received much attention in the development of direct reduction of iron ores because hydrogen metallurgy is one of the effective methods to reduce CO2 emission in the iron and steel industry. In this study, the kinetic mechanism of reduction of hematite particles was studied in a hydrogen atmosphere. The phases and morphological transformation of hematite during the reduction were characterized using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. It was found that porous magnetite was formed, and the particles were degraded during the reduction. Finally, sintering of the reduced iron and wüstite retarded the reductive progress. The average activation energy was extracted to be 86.1 kJ/mol and 79.1 kJ/mol according to Flynn-Wall-Ozawa (FWO) and Starink methods, respectively. The reaction fraction dependent values of activation energy were suggested to be the result of multi-stage reactions during the reduction process. Furthermore, the variation of activation energy value was smoothed after heat treatment of hematite particles.

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Mechanism of composite additive in promoting reduction of copper slag to produce direct reduction iron for weathering resistant steel

Powder Technology ◽

10.1016/j.powtec.2018.01.063 ◽

2018 ◽

Vol 329 ◽

pp. 55-64 ◽

Cited By ~ 7

Author(s):

Zhengqi Guo ◽

Jian Pan ◽

Deqing Zhu ◽

Yang Congcong

Keyword(s):

Direct Reduction ◽

Copper Slag ◽

Resistant Steel ◽

Direct Reduction Iron

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Direct reduction of copper slag-carbon composite pellets by coal and biochar

Environmental Technology ◽

10.1080/09593330.2018.1561757 ◽

2019 ◽

Vol 41 (17) ◽

pp. 2240-2252 ◽

Cited By ~ 1

Author(s):

Zongliang Zuo ◽

Qingbo Yu ◽

Huaqing Xie ◽

Fan Yang ◽

Zhicheng Han ◽

...

Keyword(s):

Direct Reduction ◽

Copper Slag ◽

Carbon Composite ◽

Composite Pellets

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Kinetics of the Volume Shrinkage of a Magnetite/Carbon Composite Pellet during Solid-State Carbothermic Reduction

Metals ◽

10.3390/met8121050 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1050 ◽

Cited By ~ 3

Author(s):

Guang Wang ◽

Jingsong Wang ◽

Qingguo Xue

Keyword(s):

Activation Energy ◽

Solid State ◽

Apparent Activation Energy ◽

Carbothermic Reduction ◽

Iron Ore ◽

Carbon Composite ◽

Volume Shrinkage ◽

Reduction Temperature ◽

Iron Particles ◽

Composite Pellet

The volume shrinkage evolution of a magnetite iron ore/carbon composite pellet during solid-state isothermal reduction was investigated. For the shrinkage, the apparent activation energy and mechanism were obtained based on the experimental results. It was found that the volume shrinkage highly depended on the reduction temperature and on dwell time. The volume shrinkage of the pellet increased with the increasing reduction temperature, and the rate of increment was fast during the first 20 min of reduction. The shrinkage of the composite pellet was mainly due to the weight loss of carbon and oxygen, the sintering growth of gangue oxides and metallic iron particles, and the partial melting of the gangue phase at high temperature. The shrinkage apparent activation energy was different depending on the time range. During the first 20 min, the shrinkage apparent activation energy was 51,313 J/mol. After the first 20 min, the apparent activation energy for the volume shrinkage was only 19,697 J/mol. The change of the reduction rate-controlling step and the automatic sintering and reconstruction of the metallic iron particles and gangue oxides in the later reduction stage were the main reasons for the aforementioned time-dependent phenomena. The present work could provide a unique scientific index for the illustration of iron ore/carbon composite pellet behavior during solid-state carbothermic reduction.

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Kinetic Studies on the Synthesis of Hydroxyapatite Nanowires by Solvothermal Methods

Australian Journal of Chemistry ◽

10.1071/ch06117 ◽

2007 ◽

Vol 60 (2) ◽

pp. 99 ◽

Cited By ~ 7

Author(s):

Shiying Zhang ◽

Chen Lai ◽

Kun Wei ◽

Yingjun Wang

Keyword(s):

Activation Energy ◽

Reaction Rate ◽

Kinetic Studies ◽

Axial Ratio ◽

Reaction Rate Constant ◽

Rate Equations ◽

Solvothermal Reaction ◽

Growth Order ◽

Constant Diffusion ◽

Solvothermal Methods

Hydroxyapatite nanowires with a high axial ratio have been synthesized in reverse micelle solutions that consist of cetyltrimethylammonium bromide (CTAB), n-pentanol, cyclohexane, and the reactant solution by solvothermal methods. This paper focusses on the kinetic studies of the solvothermal reaction and the linear growth of hydroxyapatite nanowires. When the reaction was carried out at low temperatures (65°C), the experimental results showed that the reaction rate was of zero order since the whole reaction was diffusion controlled with constant diffusion coefficients. In the middle to high temperature range (130–200°C), the kinetics were characterized by second order reaction kinetics. Since the controlling factor was activation energy and the apparent activation energy was large, the reaction rate was more sensitive to the temperature. Therefore, the exponent of the reaction rate constant increased by two when the temperature was increased from 130 to 200°C. By calculating the yields of products and the specific surface areas at different times, the linear and overall growth rate equations of the hydroxyapatite nanowires could be obtained. The experimental effective growth order of the crystals was 11. The larger growth order indicated that the crystal could grow more effectively in one direction because of the induction of the surfactant in the experiment system.

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Hydrodechlorination of carbon tetrachloride with nanoscale nickeled zero-valent iron @ reduced graphene oxide: kinetics, pathway, and mechanisms

Water Science & Technology ◽

10.2166/wst.2020.386 ◽

2020 ◽

Vol 82 (4) ◽

pp. 759-772

Author(s):

Xiao Chen ◽

Zhen Wang ◽

Qi Yang ◽

Yeyao Wang ◽

Zhaoxiang Liu ◽

...

Keyword(s):

Activation Energy ◽

Graphene Oxide ◽

Carbon Tetrachloride ◽

Reduced Graphene Oxide ◽

Bimetallic Nanoparticles ◽

Dimensional Structure ◽

Nickel Metal ◽

Reduced Graphene ◽

Supporting Material ◽

Reaction Activation Energy

Abstract In recent years, carbon tetrachloride (CT) has been frequently detected in surface water and groundwater around the world; it is necessary to find an effective way to treat wastewater contaminated with it. In this study, Ni/Fe bimetallic nanoparticles were immobilized on reduced graphene oxide (NF@rGO), and used to dechlorinate CT in aqueous solution. Scanning electron microscopy (SEM) demonstrated that the two-dimensional structure of rGO could disperse nanoparticles commendably. The results of batch experiments showed that the 4N4F@rGO (Fe/GO = 4 wt./wt., and Ni/Fe = 4 wt.%) could reach a higher reduction capacity (143.2 mgCT/gcatalyst) compared with Ni/Fe bimetallic nanoparticles (91.7 mgCT/gcatalyst) and Fe0 nanoparticles (49.8 mgCT/gcatalyst) respectively. That benefited from the nickel metal as a co-catalyst, which could reduce the reaction activation energy of 6.59 kJ/mol, and rGO as an electrical conductivity supporting material could further reduce the reaction activation energy of 4.73 kJ/mol as presented in the conceptual model. More complete dechlorination products were generated with the use of 4N4F@rGO. Based on the above results, the reductive pathway of CT and the catalytic reaction mechanism have been discussed.

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