Removal of nitrates from copper containi

The north of Chile is characterised by a large content of caliche minerals which represent high amounts of sodium and potassium nitrates. The presence of these nitrates, in copper-containing aqueous acid leach solutions, are responsible for serious problems in the hydrometallurgical extraction of copper-from ore. The main problems are: extractant losses due to nitration and/or hydrolysis and negative effects upon bioleaching microorganisms such as lower growth cell and higher microbial lag times. On the basis of these problems, the objective of this work was to evaluate electrodialysis (ED) as an alternative method for removal for nitrates from copper-containing aqueous acid leach solutions. For this purpose, ED experiments in a three-compartment cell using both real and synthetic solutions at different current densities, flow rate and temperature were studied. It was found that high temperature favours ion mobility and enhances transfer of ions through membranes, reducing energy consumption while also decreasing solution viscosity, which may decrease pumping costs. However, operational limits due to membrane degradation at high temperatures must be considered.