Dissolution Behavior of Platinum in Na2O–SiO2-Based Slags

With the aim of minimizing the loss of platinum into slags by controlling the slag composition during the high-temperature recycling process, the effects of representative slag components, namely, Al2O3, MgO, Fe2O3, and CuOx, on the dissolution behavior of platinum into Na2O­SiO2-based slags were investigated. The solubility of platinum in the slags was measured by equilibrating the Na2O­SiO2-based slags with pure solid platinum at 1473K in air. The dissolution of platinum in the slags was found to be suppressed by the addition of Al2O3, MgO, and Fe2O3 .A l2O3 and Fe2O3 behaved as acidic oxides, whereas MgO behaved as a diluent and decreased the solubility of platinum in the slags. CuOx behaved as a weakly basic oxide and slightly enhanced the dissolution of platinum into the slags. The correlation between the platinate capacity of the slag, which is a parameter proposed in this paper, and the optical basicity enabled the content of platinum in slags at 1473K to be estimated from the slag composition. [doi:10.2320/matertrans.M2014042]