There is an increasing trend in the copper smelters to recycle electronic materials, which contain relatively high concentration of silver. Silver lost in the slag is increasing with increasing of treated scrap amount. To determine the portion of the silver chemically dissolved in the slag will be a key factor to improve the recovery of silver.
An experimental study was carried out to determine the solubility of silver in the FeOx-SiO2 slag equilibrated with a pure liquid silver and the molten Ag-Cu alloys at 1573K in the range of oxygen partial pressure from 10–9 to 10–6 as an oxygen activity. The solubility of silver in the slag tends to increase with increasing oxygen partial pressure and the activity of Ag in the alloys. Therefore, lower oxygen partial pressure and lower concentration of silver in the metal phase tend to lower silver dissolution in the slag. Based on the measured silver solubility and the oxygen partial pressure, activity coefficients of silver oxide in the FeOx-SiO2 slag were derived. The activity coefficients of AgO0.5 in iron silicate slag show a constant value regardless of the oxygen partial pressure and the copper concentration in the slag. We found that AgO0.5 and CuO0.5 in the FeOx-SiO2 slag behaved as ideal relation from the derived activity coefficient of AgO0.5.
