Separation And Purification Of Precious Metal In Copper Anode Slime

The copper anode slime is an important byproduct in the process of copper electrolysis refining. It contains a large amount of gold, silver, and platinum group metals, and consequently becomes an important raw material in nonferrous metallurgy. Therefore utilizing the copper anode slime reasonably has great economic value.This research took black gold powder and silver nitrate, which were formed in the production processes of copper anode slime, as raw materials. The reduction of black gold powder, electrolytic refining silver and resin adsorption of palladium were studied to obtain the optimal conditions of these processes.The results showed that if using Na2SO3as the reducing agent of gold solution, then the optimal reduction conditions were as followed, temperature was25℃, the solution of pH at1.0, the reduction time was2h, and the excess coefficient of reducing agent was250%, the gold recovery ratio reached99.80%; if adopting H2C2O4·2H2O as the reducing agent of gold solution, then the best conditions were as followed, solution temperature at80℃, the solution pH at2, the reduction time at2h, and the excess coefficient of reductant was200%, the gold recovery ratio reached99.92%; if using NaHSO3as the reducing agent, the best conditions were:solution temperature at25℃, the solution pH at1.5, reduction time at2.5h and the excess coefficient of reductant was250%. Oxalic acid restoring the purity of gold reached99.97%, the gold recovery ratio reached99.85%.The experimental results of silver electrolytic refining showed that the electrolytic heat was enough to sustain the reaction process itself when the concentration of AgT was80～120g/L. When controlling the impurity concentrations of Cu2+and Pb2+under45g/L and1g/L respectively, then Cu2+and Pb2+would not affect the proceeding of the electrolyte. And the current efficiency could maintain above90%.The adsorption and desorption of Pd+using D113resin were carried out in the electrolyte recycling. Under certain the amount of resin condition, D113resin adsorption Pd2+increased with the increase of the adsorption time and the adsorption reached equilibrium after4h; elevated temperature and pH were conducive to the resin adsorption exchange reaction of palladium. Increasing the resin amount could also increase the resin adsorption rate for palladium.4g D113resin adsorption100mL of70.50mg/L liquid containing palladium, and the adsorption rate was up to80%. The adsorption and desorption of Pd2+using D113resin were carried out in the electrolyte recycling. The results showed that the higher the temperature, pH value and the greater the circulation flow rate were smaller for palladium adsorption; higher temperature and lower resolution agent flow were also advantageous to the palladium desorption.