Growth Characteristics of Metallic Iron Particles in the Direct Reduction of Nickel Slag

As the fourth-largest industry waste residue, after iron slag, steel slag, and red mud, in China, the comprehensive utilization of nickel slag is imminent. Coal-based reduction combined with magnetic separation was considered an efficient method to extract iron from nickel slag. During the coal-based reduction of Jinchuan ferronickel slag, the growth characteristics and kinetics of metallic iron were investigated in this paper. The metallisation rate and metal iron grain size gradually increased with the reduction temperature or the reaction time, and the coal-based reduction process was divided into the rapid formation period and the aggregation growth period of the metallic phase. The granularity distribution of metallic iron obeyed the Doseresp sigmoidal function, and the activation energy of grain growth at different stages were 52.482 ± 4.448 kJ·mol−1 and 26.426 ± 3.295 kJ·mol−1, respectively. Meanwhile, a mathematical growth model of the metallic iron grains was also established.

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Effect of Co2O3 on Oxidation Induration and Reduction Swelling of Chromium-Bearing Vanadium Titanomagnetite Pellets with Simulated Coke Oven Gas

Metals ◽

10.3390/met9010016 ◽

2018 ◽

Vol 9 (1) ◽

pp. 16 ◽

Cited By ~ 2

Author(s):

Weidong Tang ◽

Songtao Yang ◽

He Yang ◽

Xiangxin Xue

Keyword(s):

Compressive Strength ◽

Metallic Iron ◽

Thermodynamic Calculation ◽

Coke Oven ◽

Iron Particles ◽

Coke Oven Gas ◽

Reduction Swelling ◽

Lamellar Crystals ◽

Technical Basis ◽

And Diffusion

This study discusses the oxidation induration and swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with Co2O3 additions. The reduction swelling index (RSI) and compressive strength of reduced CVTP (CSRC) were investigated with simulated coke oven gas (COG). The results show that the compressive strength (CS) of CVTP decreases from 2448 to 1983 N and the porosity of CVTP increases from 14.86 to 22.49% with increasing Co2O3 additions. The Co2O3 mainly exists in the form of CoFe2O4 in both of CVTP and reduced CVTP, and the CoFe2O4 is hard to be reduced by thermodynamic calculation. The Co-bearing phase mainly distributes on gap edges and among adjacent hematite grains. Many cracks and pores distribute along the grain boundaries and damage the connection of hematite grains. The CSRC decreases from 901 to 376 N, and RSI of reduced CVTP increases from 5.87 to 9.05% with increasing Co2O3 additions. The Co2O3 addition facilitates the aggregation and diffusion of metallic iron particles, and the aggregations of metallic iron thicken the lamellar crystals. The pores and interval of grains enlarge with increasing Co2O3 additions. This study can supply the theoretical and technical basis for the utilization of CVTP and waste residue-bearing cobalt with COG recyclable technology.

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Influence of Temperature and Holding Time on Number and Size of Metal Particles during Solid-Phase Reduction of Iron by Carbon

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.316.496 ◽

2021 ◽

Vol 316 ◽

pp. 496-501

Author(s):

A. Bil'genov ◽

A.R. Tabylbaeva ◽

P.A. Gamov

Keyword(s):

Crystal Lattice ◽

Solid Phase ◽

Direct Reduction ◽

Complex Oxide ◽

Holding Time ◽

Iron Particles ◽

Experimental Conditions ◽

Influence Of Temperature ◽

Reduction Of Iron ◽

Average Size

There is a lack of complete understanding of the mechanism and kinetics of reduction of metals from oxides. This paper presents results and methods of a series of experiments on direct reduction of metals by solid carbon in the form of graphite from a complex oxide with a low iron content in a laboratory muffle furnace at temperatures of 1300, 1400, 1500, 1600 °C and holding time of 1, 3, 5, 7 hours. The statistical analysis of amount and average size of reduced iron particles inside the oxide was studied. Dependence of amount and average size of the reduced iron particles on temperature and time of reduction is presented. The phenomena of iron crystals’ growth, occurring as a result of changes in the crystal lattice of oxide, was studied under experimental conditions. The influence of temperature and holding time on iron particles’ nucleation and their growth in the crystal lattice of a complex oxide were compared. Investigation of mechanism of metals’ reduction from complex oxides and influence of experimental conditions on the nucleation and growth enables to identify new patterns in the process of reduction of metals from their oxides, in general.

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Effects and mechanism of MgO on carbothermal reduction of Fe2TiO4

Metallurgical Research & Technology ◽

10.1051/metal/2021059 ◽

2021 ◽

Vol 118 (4) ◽

pp. 416

Author(s):

Yunfei Chen ◽

Xiangdong Xing

Keyword(s):

Carbothermal Reduction ◽

Thermodynamic Calculation ◽

Direct Reduction ◽

Reduction Temperature ◽

Iron Particles ◽

Promoting Effect ◽

Effect Mechanism ◽

Metallization Rate ◽

High Reduction

The effects of MgO on carbothermal reduction of Fe2TiO4 had been researched including the thermodynamic calculation in this paper. And, based on XRD and SEM-EDS, the effect mechanism of MgO on the direct reduction of Fe2TiO4 had been deeply dissected, systematically. The results showed that magnesium titanium phases including MgTi2O5, MgTiO3 and Mg2TiO4 were formatted after MgO added into Fe2TiO4, which was main reason to affect the reduction of Fe2TiO4. When the MgO content in Fe2TiO4 did not exceed 2%, there was the promoting effect on the reduction of Fe2TiO4. With the increase of MgO content from 2% to 8%, the magnesium titanium phases transformed from MgTi2O5, and through MgTiO3 to Mg2TiO4. The inhibition function appeared, and can be weaken in the high reduction temperature. When reduction temperature reaches to 1300 °C, the metallization rate of F-M-8 (the reduction sample of 8% MgO) can reach 80.62% from 56.43% at 1200 °C. However, the aggregation degree of iron particles became worse when MgO was added to the sample.

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