One-step extraction of CuCl2 from Cu-Ni mixed electroplating sludge by chlorination-mineralization surface-interface phase change modulation

Selective extraction of heavy metals from electroplating sludge has been an urgent problem in the field of sludge disposal and an important way to achieve effective utilization of sludge. The coexistence of multiple metals in electroplating sludge limits the development and use of selective extraction methods. In this work, we proposed a chlorination-mineralization surface-interface phase change method, which innovatively achieved the volatilization separation of Cu in Cu-Ni mixed electroplating sludge (C-N ES). The economical and efficient chlorinating agent HCl and mineralizing agent SiO2 were screened out. Copper resources were extracted from copper-nickel coexisting electroplating sludge in the form of copper chloride dihydrate. Under the action of mineralizer, most of the nickel forms stable nickel silicate, and only about 3% of the nickel was volatilized. The extraction rate of copper under the optimal conditions was 93%, and the purity of the product was about 91%, with only 8.2 mg/kg of nickel content. This work provides a feasible method for the selective extraction of heavy metals from electroplating sludge and also inspires the application of chlorination-mineralization surface-interface phase control method in the recycling of hazardous waste containing heavy metals.