Many copper bearing ores have other metals such as zinc, silver, gold, molybdenum , etc. associated with them.   In many of these deposits, copper is concentrated by a flotation process.  Because of the presence of other metals, it is necessary to treat the surface of the copper minerals with sulphur based or cyanide based chemicals to depress these metals in the flotation process. 

After filtration of the concentrate from the flotation stage, the resulting solution contains significant levels of sulphides and cyanides which can be destroyed by oxidation with peroxide or Caro’s acid prior to discharge from site.  For further information on these detoxification processes, refer to the section on detoxification or consult your local Solvay representative.