Tailor-made leaching process for the most demanding copper anode slimes.
Copper can be removed from anode slime by atmospheric leaching in sulfuric acid. If the slime contains significant amounts of nickel, tellurium or arsenic, it must be leached in an autoclave at high pressure and high temperature.
In pressure leaching, oxygen gas is used to oxidize the metallic copper. Copper oxide is then leached with sulfuric acid. Outotec's patented GLS agitator efficiently mixes oxygen into the solution.
Selenium and silver are precipitated out of the solution with sulfur dioxide gas in a flash tank or cemented with copper powder. Tellurium can also be recovered as copper telluride from the filtrate by cementation with copper powder.