Green and efficient comprehensive utilization of pyrite concentrate: A mineral phase reconstruction approach

Abstract

Pyrite concentrate obtained from sulfide mines is of low value and not friendly to the environment. This paper proposed a method for clean and efficient comprehensive utilization of pyrite concentrate by phase reconstruction (pyrolysis) under high temperature and nitrogen atmosphere. Firstly, the results of HSC calculation and thermogravimetric analysis showed that the pyrolysis temperature range of pyrite is between 400 and 700 °C. The pyrolysis conditions test proved that temperature, layer thickness and time were the important factors affecting the pyrolysis results. At a temperature of 650 °C, a layer thickness of 10 mm and a reaction time of 3 h, the decomposition ratio of the pyrite concentrate reached 100%. The XRD results showed that the pyrolysis slag was mainly pyrrhotite (Fe7S8). The SEM image showed that the microstructure of the pyrolysis slag became loose and porous. The decomposed sulfur gas was condensed into solid sulfur, and the result showed that the purity of the sulfur was in accord with the standard specification. In addition, PbSO4 in the pyrite concentrate turned into PbS through pyrolysis. The results of this study provide an economical and green process for the comprehensive utilization of pyrite concentrate.