Recycling copper-bearing sludge: status and prospects

This article surveys the current state of the recycling of copper-bearing sludge from electrolysis operations. It notes the main advantages and disadvantages of existing recycling methods, the final operation in which is the smelting of a gold-silver alloy. It is shown that the smelting is the main source of losses of noble metals. The main direction that should be taken to improve sludge recycling is the development of a hydrometallurgical technology that completely eliminates the smelting stage. The article examines several variants of hydrometallurgical technologies. It was found that there has not yet been enough research into the hydrometallurgical decomposition of chalcogenides of noble metals. This process determines the conditions under which gold and silver are concentrated during the recycling of sludge. Existing Russian technologies for extracting selenium in sludge processing are discussed, and it was determined that one of the main ways of improving selenide roasting technology might be the electrolytic precipitation of selenium. Also discussed are different aspects of making the decision to recycle sludge by hydrometallurgical means and the importance of solving problems related to separation of the valuable components.