Tiina Heikola1 *, Marja Salo1, Jarno Mäkinen1, Quentin Dehaine2, Martina Bertelli2, Pasi Heikkilä2, Päivi 2 Kinnunen1 3 1
VTT Technical Research Centre of Finland Ltd., 02150 Espoo, Finland 4 2
Geological Survey of Finland, Circular Economy Solutions Unit, 02151 Espoo, Finland 5
*corresponding author 6
Keywords: leaching, nickel, cobalt, bioleaching, chloride addition 7
Abstract: In this study a finely ground nickel sulphide concentrate was leached in shake flask and batch reactor experiments to determine the optimal method to recover nickel, cobalt and copper from the material. The selected leaching methods were sulphuric acid leaching, ferric sulphate leaching and bioleaching. In addition, the effect of chloride ions on the leaching efficiency was evaluated with different concentrations. The results of the sulphuric acid and ferric sulphate experiments showed increased nickel and cobalt recovery with chloride addition. The highest metal yields in the 8-hour reactor experiment (67% Ni, 69% Co, 87 % Cu) were obtained with chloride concentration of 20 g/L at the temperature of 90 °C. The mineralogical analysis showed that pyrrhotite was dissolved almost completely in all the experiments. Pentlandite and chalcopyrite leaching was clearly improved by the addition of Cl- at similar temperatures.