Distribution Behavior of Nickel between Liquid Copper and CaO–SiO2–FetO–MgO Slag

초록

The distribution ratio of nickel (LNi) between Cu-1 mass pct Ni alloy and CaO–SiO2–FetO–MgO slag was measured to explore the possibility of refining nickel from molten copper for increased use of copper scrap. Slag-metal equilibrium experiments were carried out at temperatures from 1598 K (1325 °C) to 1673 K (1400 °C) with an oxygen partial pressure of pO2=10-6atm over a wide range of slag compositions. At a fixed temperature, LNi increased with increasing basicity for the relatively basic regime near the monoxide (Mg, Fe)O-saturated slags, whereas it decreased with increasing slag basicity for the relatively acidic regime near the olivine (Mg, Fe)2SiO4-saturated slags. Thus, the dissolution mechanism of nickel into the CaO–SiO2–FetO–MgO slag can be described by the following two independent dissolution reactions: Ni+12O2g+O2-=NiO22- (at monoxide saturation); Ni+12O2g=Ni2++O2- (at olivine saturation). The distribution ratio of nickel increases with increasing FetO content. Under constant temperature and oxygen partial pressure, the redox equilibrium of iron in FetO-containing slag is influenced by the chemical composition of the slag. The activity coefficient of NiO (γNiO) in the olivine-saturated slag is higher than those in the monoxide-saturated slag in the observed compositions. Consequently, in terms of copper loss and stability of nickel oxide, monoxide-saturated slag system is recommended as an optimal slag window compared to olivine-saturated slag system.

키워드