Regulating Mechanism of the Coal-Based Reduction Reaction Behavior of Jinchuan Ferronickel Slag: Equilibrium Phase Composition, Kinetics, and Phase Transformation

Herein, the coal-based reduction was proposed to utilize the ferronickel slag of Jingchuan company. An excellent index with metallization rate of 99.22%, iron grade of 77.91%, and iron recovery of 92.79% was obtained at carbon addition coefficient 2.0, reduction temperature 1573 K, reduction time 60 min, the particle size of coal and ferronickel slag - 2.0 mm, and CaO content 15%. The 2FeO center dot SiO2 was reduced to Fe and SiO2 with the increase of temperature. The CaO could promote the reduction of iron oxide. Most of the sulfides (Fe, Cu, Co, and Ni) in the sulfonium were reduced to metal. The reduction degree increased with the reduction time and reduction temperature. The higher reduction temperature represented the higher peak value of reduction rate and the shorter time of reaching the peak value. The isothermal reduction process included three stages: early stage, middle stage, and late stage. The mechanism function were f(alpha) = 1/2(1 - alpha)(3), f(alpha) = 3/2(1 - alpha)(4/3)[(1 - alpha)(-1/3) - 1](-1), and f(alpha) = 4(1 - alpha)[- ln(1 - alpha)](3/4), respectively. The activation energy of three stages was 183.498 kJ center dot mol(-1), 420.077 kJ center dot mol(-1), and 656.619 kJ center dot mol(-1), respectively.

Automated summary

In this study, coal-based reduction was proposed to utilize ferronickel slag, and the optimal reduction conditions and effects were obtained through experiments. CaO and temperature played a promoting role in the reduction process, while reduction time and temperature had a positive correlation with reduction degree. The isothermal reduction process consisted of early stage, middle stage, and late stage, with corresponding mechanism functions and activation energy.