Hydrometallurgical process for treating refractory ores containing

Abstract

This invention is directed to an improved process for leach treating gold and silver bearing pyritic and arsenopyritic concentrates and ores. More particularly, the improved process avoids the necessity of adding recycled neutralized solution to the leach solution, thereby alleviating difficulties in maintaining acid levels in the leach solution, and provides for bleeding solutions containing dissolved arsenic, iron and sulphate from the process without the loss oxidized nitrogen species. The process can be carried out in one or more tubular reactors. The process for recovering valuable metals from pyritic and arsenopyritic concentrates and ores involves decomposing the arsenopyrite or pyrite concentrates and ores in acidic solution in a common volume space which contains a gas phase and a liquid slurry (which comprises a liquid phase and a solid phase) through the action of higher valence oxidized nitrogen species in which the nitrogen has a valence of at least plus 3. The active oxidized nitrogen species are regenerated in the same common volume space by an oxygen containing gas. The concentrate or ore is introduced into a denitrating step along with a solution from the leach solution. Essentially all of the oxidized nitrogen species in the leach solution is reacted with concentrate or ore to produce in the denitrating step nitric oxide which is released into an oxygen free gas phase and is transported to the gas phase of the common volume species. The liquid and solid products of the denitrating step are subjected to a solid-liquid separation, after which the solids from the separation step are transported to a leaching vessel where the solids are treated with oxygen and nitric oxide replaced from the denitrating step.