Efficient recovery of copper from a copper converter dust via thin layer leaching and solvent extraction

The production of flue dusts is inherent in copper pyrometallurgy. These flue dusts are originated in the three types of furnaces used: flash, reverberatory and converters, and all have the same characteristics: a high content of copper accompanying with a miriade of other elements. This is because these dusts can be considered profitables (copper) and hazardous (arsenic, etc.), the above together with the non desirable option of their recycling to the corresponding furnace, make of a necessity their treatment prior to their eventual dumping. The present investigation deals with the treatment of one of these dusts, a converter dust, via hydrometallurgical treatment. The high copper content of the starting material (74 % copper in which 30% is metallic copper), makes any conventional leaching unusable, thus, an advanced option like thin layer leaching of the dust with nitric acid, followed by dissolution in water, leads to a pure copper solution. However, the purity and copper concentration in the solution can be increased via solvent extraction, and a counter-current circuit using Acorga PT5050 dissolved in a kerosene diluent as extractant phase has been proved during 80 hours. The results indicated that a net copper gain of near 12 g/L copper is achieved and the exiting aqueous solution can feed a copper electrowinning plant.