Experiments study on silver separated by using Na₂SO₃and NH₃

Study describes the process of gold dregs that separated by Chlorine separating silver by using Na₂SO₃ and NH₃ in the anode slime treatment process; Studied amount of silver Na₂SO₃, pH, time on the effects of separating silver by using Na₂SO₃, as well as temperature, pH effects on the rate of reduction of silver reducted by using formaldehyde; studied concentration of NH₃, time on the effects of separating silver by using NH₃, as well as the amount of hydrazine hydrate, time and temperature on the rate of reduction of silver by using hydrazine hydrate. The results show that separating silver of Na₂SO₃ -reducted by using formaldehyde, when the amount of Na₂SO₃is 1.3 times of the theoretical amount, pH is 9.2, and the leaching time is 4h, the silver recovery rate can be up to 97.39%, while the amount of formaldehyde (formaldehyde: Ag=1:2.5), pH is 10.5, the temperature is 30 ℃~40 ℃, reacted 4h, the silver reduction rate can be up to 96.33%; Separating silver of NH₃ -reducted by using hydrazine hydrate, when the concentration of NH₃ between 8% to 10%, and temperature is at room temperature, the reaction time is 4h, the silver leaching rate can be up to 96.23%, when the amount of hydrazine hydrate is 2 times of the theoretical amount, temperature is 60 ℃, restored 0.5h, silver reduction rate can be up to 98.1%.