During the copper refining process, impurities in the anode dissolve into the electrolyte or form anode slimes. When arsenic, antimony and bismuth enter the electrolyte, they can undergo a number of different reactions depending on their concentrations, as well as the presence and the concentration of other elements. Arsenic enters the electrolyte as As(III), and is gradually oxidized to As(V). Under these circumstances, insoluble antimony and bismuth arsenates are formed causing issues with the tank house circulation of both pipe work fouling and copper cathode nodulation. In the past refineries have undertaken multi-step purification processes to tackle the impurity build-up including different ion exchange techniques. Unfortunately, issues of resin poisoning and usage of high regeneration acid have made these processes both expensive and difficult to operate.
Enviolet has addressed the issue of resin poisoning and fresh regeneration acid usage, finally offering copper refineries a viable technology, which removes antimony and bismuth from their copper electrolytes.
enviolet works only with Lewatit resins. The recycling of the eluent is a crucial step towards making the whole process economically efficient and through the enviolet process, 80 % of the eluent acid is recycled.