Sulfidatiosn treatment of a mixed metal solution containing Cu2+
, and Ni2+
ions was conducted using CaS as the sulfidation agent. The selective recovery of these metal sulfides was studied. Furthermore, filtration characteristics of the NiS cake obtained with CaS, Na2
S, and NaOH as precipitation agents were compared in terms of their average specific filtration resistance and compressibility coefficient. Results show that selective precipitation of metal sulfides was achieved by sulfidation treatment with CaS at pH of 1.8-2.0 for CuS precipitation and at pH of 5.5-6.0 for ZnS precipitation. Based on the high performance of filtration of the resultant nickel sulfides, it was concluded that solid CaS was more effective for filtration of NiS cake than Na2
S or NaOH as a precipitation agent because NiSO4
was sulfidated with solid CaS, thereby forming larger NiS particles by agglomeration.