Kinetics study on non-isothermal carbothermic reduction of nickel laterite ore in presence of Na2SO4

Sodium sulfate has proven to be an effective additive for enhancing the reduction and metal aggregation during the carbothermic reduction of Ni laterite ore. In this study, the effect of Na2SO4 on the non-isothermal reduction kinetics of Ni laterite ore with solid C was investigated. The kinetic parameters and mechanism function were determined. The reduction mechanism was also analyzed by combining X-ray diffraction analysis with evolved-gas analysis. The results indicated that the reduction process was divided into three stages on the basis of the conversion degree. The average activation energy was 323.0 kJ/mol for the initial stage of alpha = 0-0.40, 161.2 kJ/mol for the middle stage of alpha = 0.40-0.80, and 161.3 kJ/mol for the decaying stage of alpha = 0.80-1.00. Three-dimensional diffusion equation was determined as the mechanism function in the initial and middle stage. The chemical reaction function exhibited the best fit in the decaying stage. (C) 2019 Elsevier B.V. All rights reserved.