Method and a system for gold extraction with halogens

摘要

The invention relates to a method for the extraction of precious metals, using halogens. It has been found that introducing halogens in the reactor in the form of hypohalites rather than free halogens simplified greatly the recycling of halogens by electrolysis. It increases the rate of addition of the halogens and significantly reduces secondary reactions with base metals such as iron. Operating under acidic conditions, the gold recovery has been found as high with hypochlorite as with elemental chlorine, with an active chlorine to ore ratio reduced by a factor of two to five.

主权项

1. In a method for extracting precious metals from ore using halogens:
adding a mixture of hypohalites to an acidic slurry of the ore, a pH of the slurry being comprised in a range between 0.5 and 3, under an oxido-reduction potential in a range comprised between about 0.7 and about 1.2 V vs a Ag/AgCl reference electrode; filtering to collect a pregnant solution; treating the pregnant solution to separate the precious metals from a barren salt brine; and recycling halogens from the barren salt brine in the form of hypohalites formed by electrolysis of the barren salt brine in a diaphragm-less cell.