The solubility of silver in MO-B2O3 (MO = CaO, BaO and Na2O) slags at high temperatures was measured in order to understand the dissolution mechanism of silver in the slags, and the effects of CaO, BaO, and Na2O on the solubility of silver. The solubility of silver in the Na2Osatd-B2O3 system exhibits a minimum value as a function of oxygen partial pressure at about pO(2) = 8.49×10-9 Pa. Therefore, the dissolution reaction of silver in basic slags at higher oxygen potential can be estimated by the following equation: Ag(l)+1/2O2(g)+O2-(slag) = AgO22-(slag) (pO(2)≥8.49×10-9 Pa). The solubility of silver in B2O3-bearing slags also exhibits a minimum value as a function of slag composition. The minimum composition shifts to the acidic region following the order of CaO-, BaO-, and Na2O-B2O3 slag. Based on these minimum compositions, i.e., 65 (mol%) CaO, 45 (mol%) BaO, and 35 (mol%) Na2O, the value of the CaO-equivalence of BaO and that of Na2O are suggested as 1.44 (= mol% CaO/mol% BaO) and 1.86 (= mol% CaO/mol% Na2O), respectively.
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