1971 年 87 巻 994 号 p. 29-32
The kinetics of dissolution of silver in ammonia solutions under oxygen pressure have been investigated with a view of establishing the factors which influence the dissolution rate. The results indicate that the rate is determined by the following factors:
1) the fraction of surface sites covered with oxyge
2) the concentration of ammonia
3) the temperature
4) the additional quantities of sodium thiosulphate.
Based on this investigation, the zinc leach residues have been leached with 7.5M ammonia solution at a temperature between 175 and 200°C and an oxygen partial pressure of 15kg/cm2. Gold and silver extractions of over 95 per cent were obtained.