METHOD FOR PRODUCING HIGH GRADE REDUCED SILVER

摘要

The known method comprises the following steps. (1) the de-copperized anode slime is chlorination-leached with HCl and H2O2. (2) Na2CO3 is added to the chlorination-leach residue of (1). (3) NH3 is added to the residue of (2). (4) Distillation of NH3 to remove NH3 contained in the ammonia leach solution of (3). (5) Distillation residue is washed with water to yield refined AgCl. (6) Conversion of AgCl to Ag2O. (7) Reduction of Ag2O to Ag. In order to enhance the purity of the reduced silver, the present invention provides the following improvements (a) to (d). (a) Dechlorination (2) with the use of Na2CO3 is carried out at ambient temperature. (b) After dechlorination, the residue is washed with hot water. (c) Sulfuric acid is added instead of carrying out distillation (4). (d) Prior to conversion (6), the chlorination is again carried out.