Wet-process metallurgy method for extracting copper from waste composition brass melting furnace slag

The invention discloses a wet melting method which extracts copper from copper melting slag after being floated. The copper smelting slag is crushed at high temperature and then leached by hydrochloric acid; concentrated sulfuric acid is added to supplement acidity, so as to go on to react with the oxidize copper and most calcium is precipitated. Then water is added to separate the solid from the liquid, and liquid phase adjusts pH by sodium hydroxide solution and adds naf solution to precipitate iron and magnesium ions. After being filtered, the solution is precipitated via sodium hydroxide solution and then the solid phase is washed and via hydrochloric acid to dissolve and crystallize, thus the chlorinated copper product is obtained. The method removes the disturbance of coal and also precipitates calcium, magnesium and iron and other impure metal. The extraction efficiency is more than 95 percent and the purity of copper chloride products is more than 99 percent, thus fully making use of the waste and bringing remarkable economic benefit and good social benefit.