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.
Characterizing the effects of shaking intensity on the kinetics of metallic iron dissolution in EDTA