The effect of competing ions on copper exchange by clays

The US Bureau of Mines performed copper exchange capacity (CuEC) tests on calcium and sodium montmorillonites and attapulgite clays. Mathematical models were developed from the data that the CuEC`s are derived from for each clay as a function of pH, copper concentration, and the concentrations of metal ions, which compete with copper for exchange sites. An analysis was made of the impact of competing ions on copper losses due to ion exchange. The results show that the CuEC`s of clays, and hence copper losses are decreased by the presence of competing ions, and that aluminum and magnesium have the largest impact of those cations normally presents in copper leaching solutions.