Phase transformation and multiphase reaction properties of complex copper ore system under melting conditions

Abstract

ABSTRACT Copper pyrometallurgical production relies heavily on copper sulphide concentrate as a raw material. The thermal behaviour of key components in complex copper sulphide during heating was investigated in this work. The findings reveal that under a nitrogen atmosphere, the thermal behaviour of natural chalcocite is split into three stages: crystal transformation, loss of water of crystallization, and disintegration of a minor number of components represented by carbonate minerals. In addition to the foregoing thermal behaviour of copper concentrate, S2 is disproportionated at high sulphur partial pressure to form Cu2O in the reaction system where Cu2S, CaO, and S2 coexist. As both are programmed in an oxygen atmosphere, their thermal behaviour is nearly identical. Cu and S combine with O to generate sulphate at temperatures between 400 and 700°C. This sulphate decomposes as an intermediate product as the temperature rises. The paths of primary constituents in the reaction system in the later stages of heating are as follows: S→SO2; Cu2S→CuSO4→CuO·CuSO4→Cu2O→Cu→Cu2O; FeS→Fe3O4→CuFeO2.