China Nonferrous Metallurgy

It is of great significance to explore the characteristics of the copper-containing phases in the slag to improve the utilization rate of subsequent resource recovery treatment such as high-temperature reduction, flotation and wet leaching. In this study, MLA, SEM-EDS and particle size analysis were used to reveal the existence of each copper phase in the slag and its relationship with each phase. The results show that the copper-containing phases in slag include Cu₂S、Cu₅FeS₄ Cu and CuSb, with contents of 3.01%, 0.28%, 2.38% and 0.04%, respectively. The main distribution intervals of the particle sizes of Cu₂S and Cu₅FeS₄ are 6.8~75μm (69.74%) and 3.4~27μm (79.46%), respectively. The proportion of metallic copper particles with particle size larger than 53μm was 58.4%.The particle size of CuSb particles was smaller, with 93.32% of the particles in the range of 6.8~38μm.Cu₂S and Cu5FeS4 were mainly in a consecutive or encapsulated state with Fe₃O₄, Fe₂SiO₄, and (Pb,Zn,Fe,Al,Ca,K)SiO4 in the slag, and the proportions of their free surface areas were respectively 79.57%, 74.74%. The natural Cu was consecutive with or encapsulated by Fe₃O₄ Fe₂SiO₄ Cu₂S, and partially encapsulated a small amount of PbS, with a free surface area ratio of 50.40%. CuSb was low in the slag phase and was mainly encapsulated by Cu₂S, Cu, Fe₃O₄ and Fe₂SiO₄ with a free surface area ratio of only 28.14%. The results provide a reference basis for the development of efficient separation and recovery process of different copper-containing phases in slag.