Patent ID: 9206492
Filing Date: 2015-12-08
Classification: C22B,C25B,Y02P

Abstract:
1. A method for extracting precious metals from a polymetallic ore, comprising: a) generating hypochlorites from a salt brine; b) chlorination of the ore using hypochlorites under acidic conditions; c) filtering to collect a pregnant solution and treating the pregnant solution for collection of precious metals; d) filtering to separate the precious metals and a barren brine; e) purifying the barren brine; and f) recycling halogens from the purified brine in the form of hypohalites formed by electrolysis of the purified brine, and comprising hypochlorite and hypobromite; wherein: said step b) further comprises scrubbing excess halogens using calcium hydroxide; said treating the pregnant solution in step c) comprises reducing an oxido reduction potential of the pregnant solution and using calcium hydroxide for neutralization; and said step e) comprises increasing the pH of the barren brine by addition of calcium hydroxide; and wherein, in step c), reducing the oxido reduction potential of the pregnant solution comprises using sulfur dioxide and using calcium hydroxide for neutralization comprises using calcium hydroxide in molar equivalent to excess sulfur dioxide and rinsing.