Abstract: Silver is recovered from an anode sludge by initially chlorinating the sludge in a slurry with nascent chlorine. The nascent chlorine is produced in situ by addition of sodium hypochlorite to the slurry in hydrochloric acid. Then the slurry is filtered and the silver containing solid phase extracted with ammonia to produce a solution from which lead is precipitated. The filtrate is then reacted with copper to precipitate silver.

Abstract: A hydrometallurgical process for enrichment of gold, platinum and palladium from copper electrolysis anode sludge, and simultaneously recovery of selenium, in which the sludge is treated with Cl.sub.2 /HCl to transform the selenium of a hexavelent state and precipitate out silver chloride. The filtrate is then subjected to selective reduction of precipitate the noble metals and the resulting filtrate is chlorinated and a further reduction is effected to precipitate the metallic selenium.

Abstract: A hydrometallurgical process for recovering pure silver from sludge formed at the anode in copper electrolysis and other sources comprises suspending the sludge, after removing Pb, Ni, and Cu, in hydrochloric acid, subsequently adding an alkali metal hypochlorite, preferably NaOCl, to the resulting suspension to convert the silver present to AgCl, filtering to separate the AgCl containing solid residue from the filtrate containing the other metallic elements, and finally working up the AgCl containing residue to obtain high purity silver. Preferably the high purity silver is obtained from the AgCl containing residue by leaching with an alkaline ammoniacal solution to dissolve the silver as the soluble silver diamine chloride, and subsequently reducing the silver diamine chloride to silver metal. The reducing agent for the silver diamine chloride is preferably either a Cu.sup.+ containing compound such as CuCl or a metal powder such as copper or bronze powder.