METHOD OF RECUPERATIVE PURIFICATION OF WASTE AQUEOUS SOLUTIONS FOR RECOVERY OF CADMIUM IONS

摘要

The invention relates to a method of recuperative purification of waste aqueous solutions with a concentration of 35...1000 mg Cd/l for the recovery of cadmium ions. According to the invention, the method consists in treating waste solutions at a temperature of 80°C, while mechanically stirring for 15 min, with a solution of oxalic acid with a concentration of 1 N, in excess of 10...20%, at a pH of 5...5.7, followed by settling, filtering, washing with distilled water and drying at the ambient temperature the crystallized cadmium oxalate, which is further subjected to thermal decomposition at a temperature of 280...350°C to result in pure cadmium oxide, the recovery efficiency of the cadmium ions being of 97.75%.