Miscibility of the components in the binary oxide systemscontaining CuO, NiO, and ZnO were studied using their dissolution in diluted H2SO4 combined with the examination of the oxides lattice parameters obtained bypowder XRD. In samples synthesized by heating the corresponding mixed hydroxidesat 900 _C in air the following miscibility limits were found: 15 mol.% CuO and26 mol.% ZnO in bunsenite (cubic NiO), 0.8 mol.% NiO and 1.2 mol.% ZnO intenorite (monoclinic CuO), and 1.6 mol.% CuO and 0.5 mol.% NiO in zincite(hexagonal ZnO). The data are generally comparable or lower than those availablein literature. The miscibility limits are of crucial importance for the recoveryand purification of Cu, Ni, and Zn from the industrial sludges by a simplemetallurgical scheme, which is currently tested in a laboratory scale.
