Phase equilibria in the NiO-ZnO-SiO2 and PbO-NiO-ZnO-SiO2 systems.

Experimental investigation and thermodynamic modeling of the phase equilibria in the (PbO)-NiO-ZnO-SiO 2 system has been undertaken to characterize Ni behavior in high-Zn slags. Phase equilibria data at 790–1700 °C were obtained through equilibration of synthetic mixtures in sealed silica ampoules or Pt-Ir / Au foils, rapid quenching, and electron probe X-ray microanalysis. Phase equilibria and liquidus isotherms of the NiO-ZnO-SiO 2 system in the tridymite/cristobalite SiO 2 , monoxide (Ni,Zn)O, zincite (Zn,Ni)O, olivine (Ni,Zn) 2 SiO 4 and willemite (Zn,Ni) 2 SiO 4 phase fields were measured and the extent of the 2-liquid immiscibility gap over cristobalite was determined. Additional solid solutions: larsenite Pb(Zn,Ni)SiO 4 and melilite Pb 2 (Zn,Ni)Si 2 O 7 were measured in the PbO-NiO-ZnO-SiO 2 system. It was found that NiO partially substitute ZnO in larsenite and melilite and may form a complete range of solubility in barysilite Pb 8 (Zn,Ni)Si 6 O 21. New data were used for developing a thermodynamic database to describe the Pb/Cu-containing complex system for characterizing Ni behavior in Zn-containing slags. [ABSTRACT FROM AUTHOR]