New Mechanism Finding Offers More Alternatives to Control Nitration in Copper Solvent Extraction

摘要

Nitration of the copper extractant (oxime) during the solvent extraction has been a recurrent problemat some copper heap leach operations in the north of Chile, related to the presence of nitrate in theore. Up to now, the only mechanism describing the nitration involved the action of the nitronium ionover the oxime and some alternatives to control or mitigate this phenomenon consisted in reducingthe nitronium ion present in solution.BASF discovered a new nitration mechanism at some mining operations operating with highconcentration of ferrous ion in the PLS, where the nitronium ion should not be present. Thismechanism is related to the presence of a dissolved gas, NOx, absorbed in the aqueous fase duringthe leaching of the ore. The research was made using a quick test developed to evaluate rapidly thenitration aggressiveness of any aqueous sample and a special experimental set up to analyse thedissolved gases.The finding of this new mechanism and the quick nitration test allow BASF to design effective actionsto control the potential nitration of oxime at those mining operations. BASF developed new ways tocontrol the nitration and now shares its expertise with the mining community.