Low temperature sulphidization of Cu-Co slag in the presence of calcium sulphide

Hara, YRS and Jha, A orcid.org/0000-0003-3150-5645 (2015) Low temperature sulphidization of Cu-Co slag in the presence of calcium sulphide. In: Jha, A, Wang, C, Neelameggham, N, Guillen, DP, Li, L, Belt, CK, Kirchain, R, Spangenburger, JS, Johnson, F, Gomes, A, Pandey, A and Hosemann, P, (eds.) Energy Technology 2015: Carbon Dioxide Management and Other Technologies. TMS 2015 144th Annual Meeting & Exhibition, 15-19 Mar 2015, Orlando, Fla., U.S.A.. Springer , pp. 105-113. ISBN 978-3-319-48602-4

Abstract

The investigation focuses on sulphidization of Cu, Co and Fe from a 7wt%CuO-7wt%CoO-10wt%CaO-40wt% SiO₂-(30 wt%Fe,6 wt%Al)₂O₃ slag in the presence of calcium sulphide (CaS), over a temperature range of 1173 K – 1323 K. The metal oxides phases (CuO, CoO, FeO and Fe₃O₄) in the slag were converted into metal sulphide phases (Cu₂S, CuFeS₂, FeS, Cu₅FeS₄, Co₈S₉) via MO + CaS + SiO₂ = MS + CaSiO₃ reaction, where M represents metallic Cu, Co or Fe. Cu₂S and CoS formed preferentially at low molar ratio of MO/CaS and below 1173 K. The sulphidized slag was reduced in the presence of lime (CaO) and carbon at 1323 K by following the equilibrium: MS + CaO + C = M + CaS + CO(g). The reaction products were characterised by X-ray diffraction and scanning electron microscopy techniques. The proposed method of recovering metallic phases (Cu, Co and Fe) from a Cu-Co slag via sulphidization and reduction at lower reduction temperature than 1373 K offers an energy efficient process.