Treatment of Low-Grade Copper-Nickel Sulfide Ore by Gradient Sulfidation Roasting Method

In order to transform the oxide and silicate phases of valuable metals in low-grade copper-nickel sulfide ore into sulfide phases, this study takes Jinchuan sulfide ore as raw material, sulfur as sulfurizing agent, and carbon powder as reducing agent. The thermodynamic feasibility of the sulfidation reaction and the regional dominance diagram of Me-S-O, Me-C-S were analyzed by FactSage 8.1. The effects of the amount of additives, the temperature control system, and the proportion of grinding fineness (< 74 mu m %) on the sulfidation extent of Ni, Cu, and Co were investigated. The results show that oxide and silicate phases of Ni, Cu, and Co in sulfide ore can be transformed into sulfide phase by adding an appropriate amount of sulfur, carbon powder, and Na2CO3 in the process of gradient sulfidation roasting. With the increase of additives, the increase of roasting temperature, the prolongation of roasting time, and the increase of the proportion of grinding fineness (< 74 mu m) particle size, the sulfidation extent of Ni, Cu, and Co showed a tendency to first grow, and then reach equilibrium. Under the optimum experimental conditions, the occupancy of the Ni, Cu, and Co sulfide phases increasing from 74.4%, 77.6%, and 51% to 95.27%, 98.66%, and 81.47%, respectively.