Impact of effluents from a copper–cobalt processing plant in the environment

Abstract

Abstract The new concentrator of Kipushi (NCK) in Katanga province is located in the southeast of the Democratic Republic of the Congo. This processing plant produces a concentrate of copper and cobalt, and it also generates a large amount of effluents equivalent to 2,500 m3/h. The complex nature of these effluent has become a threat to human lives, vegetation, as well as to freshwater resources in the surrounding areas. During this investigation, it was found that NCK effluents have high turbidity and high levels of sulphates compared with EPA standards. These sulphates originate from acid mine water used as one of the components for the flotation process. Also, high chlorides compared with EPA standards and hardness levels due to high concentrations of calcium and magnesium were recorded. Furthermore, the effluents contain heavy metals such as zinc, copper, cobalt, lead, ion, cadmium, and arsenic. Water used during flotation and downstream processes to produce copper and cobalt concentrates was a mixture of raw water from Kamalenge pond and acid mine water from Kipushi mine in a volume ratio of 70/30 respectively. However, it was found that the mine water is the major contributor to the effluent contamination.