Most of platinum and palladium will go into the solution along with silver during the leaching of silver anode slime by nitric acid, resulting in low recovery efficiency of platinum and palladium. In the present study aiming at improving the recovery of platinum and palladium, sodium bisulfite was used to reduce platinum and palladium from the leaching solution before it was submitted to the purification treatment for silver. The conditions for reducing platinum and palladium, such as the amount of sodium bisulfite, concentration of nitric acid, reduction temperature and time, was investigated and optimized. Under the given conditions, the reduction rate can reach 99.5% for Pt and 99.7% for Pd. The content of Pt and Pd in the reduction slag is 1.70% and 13.59%, respectively. |