A sustainable and synergistic approach for the efficient recovery of copper from the copper slag: experimental insights and perspectives

Abstract

The untreated disposal of copper (Cu) slag raises significant environmental concerns. Besides, the swift exhaustion of primary resources and rising demand compel the recovery of Cu from the potential secondary resources, such as Cu-slag. The existing literature on recovering Cu from Cu-slag comprises studies focused on individual route-based methods, including either beneficiation or pyro-or hydrometallurgical processes. However, these individual techniques encounter several challenges and compromise Cu recovery due to the complex mineralogy of slag. Thus, the present research adopts a novel synergistic approach of integrating all three processing routes to enhance Cu recovery from the Cu-slag. The as-received Cu-slag sample used in the present research investigation analysed 3.35 % Cu. The mineralogical studies revealed the incidence of fayalite, covellite, and chalcopyrite as the major mineral phases. The flotation studies were conducted to concentrate the Cu values by varying particle size, reagent dosages, and slurry pH. Based on the results of the flotation optimization studies, a process flowsheet was developed that could enrich the Cu content to 32.46 % with a recovery of 90.5 %. The beneficiated Cu concentrate was further subjected to roasting studies using a novel additive, ammonium iron sulphate, by varying the temperature, time, and quantity of the additive. The roasted product was subsequently water-leached, and under the optimized roast-leaching conditions, about 98 % of the Cu values were recovered in the leach liquor. This research offers valuable insights into effective Cu recovery, resulting in an overall Cu recovery of 88.7 % from the feed Cu-slag.