The activity coefficient of nickel oxide in alumina saturated MnO-SiO2-Al2O3 slags at 1573K

As a fundamental study related to spent lithium-ion batteries recycling by a combined pyro- and hydro- metallurgical process, the solubility of nickel in alumina saturated MnO-SiO2-Al2O3 slags in equilibrium with Cu-Ni alloy has been investigated under controlled oxygen potentials of 5.5 × 10−11 atm, 5.5 × 10−12 atm, and 5.5 × 10−13 atm at 1573 K. The results show that nickel dissolved in the slags mainly exists as NiO. The nickel solubility in the slags increased with the increase of nickel concentration in the alloy, and increased with increasing oxygen potential at a given concentration of nickel in the alloy. The activity coefficient of NiO in the slag relative to the pure solid standard, γNiO(s), increased with increasing NiO content in the slag, and can be calculated by the following equation: γNiO(s) = 46.77(wt.% NiO in slag) + 9.85, where (wt.% NiO) represents mass percent of NiO in the slag.