Extraction of valuable metals from low-grade nickel matte by FeCl3·6H2O roasting and water leaching process with studies on phase evolution and kinetics analysis of chlorination process

Abstract

At present, low-grade nickel sulfide ore with high-alkaline gangue has replaced high-grade nickel sulfide ore as the main raw material for the extraction of nickel. Traditional pyrometallurgical smelting processes have problems such as high energy consumption, large loss of valuable metals, and low comprehensive resource utilization. In this paper, an improved process that uses chlorination roasting followed by water leaching to treat low-grade nickel matte, an intermediate product derived from flotation and high-temperature smelting of ore, is innovatively put forward. The results present that 93.6% Ni, 91.7% Cu and 88.2% Co can be synchronously extracted using matte particles of size range 75–80 μm, chlorination time of 2 h, mass ratio of chlorinating agent to matte at 2:1 and chlorination temperature of 350 °C. The chlorination roasting process was determined using differential thermal and thermogravimetric analysis (DTA-TG), X-ray diffraction (XRD), thermodynamic analysis of chlorination reactions. The kinetics of chlorination process based on the thermal analysis data are analyzed by Kissinger method and Flynn-Wall-Ozawa (FWO) method, and the results show that the average apparent activation energy (Ea) of the matte chlorination process is 77.8 kJ/mol.