Simple and selective copper recovery from valuable industrial waste by imidazolium based ionic liquids with BF4- anions

In this study, copper was recovered selectively with hydrometallurgical routes (leaching and cementation) from copper anode slime which is a valuable industrial waste. The use of 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF4) ionic liquid as a novel solvent has been systematically investigated. As a result of the leaching experiment, 98.4% of copper was leached at the optimum leaching conditions; ionic liquid concentration as 40%, temperature as 95 ºC, time as 12 h solid/liquid ratio as 1/25 g/mL and, addition of 20% HBF4 as an oxidant. Also, the experimental results revealed that the other elements in the copper anode slime were not soluble in BmimBF4/HBF4. Moreover, the copper was extracted from the leach solution as in metallic form with the cementation. The highest copper extraction rate was achieved as 93.3% at 45 ºC and 120 min using a scrap aluminum sheet. After all, 91.8% of copper was recovered from copper anode slime as metallic form by leaching and cementation processes in BmimBF4/HBF4. Also, it was found that the leach solution can be reused at least 5 times with low deviations.