Patent ID: 8673055
Filing Date: 2014-03-18
Classification: C22B,Y02P

Abstract:
1. A process for improving the recovery of precious metals from recalcitrant refractory ores comprising: (a) preparing a solution of hydrogen fluoride gas (HF) in an ionic liquid; (b) contacting said HF containing ionic liquid with crushed ore at a temperature and for a period of time commensurate with the fracturing of the recalcitrant refractory ore; (c) removing the excess HF containing ionic liquid from the ore by settling and decantation or filtration; (d) recycling the HF containing ionic liquid for treatment and fracturing of fresh ore; (el) treating the fractured ore with dilute sodium cyanide solution to extract the precious metals into solution, wherein the ionic liquid is selected from 1-butyl-3-methyl-imidazolium hydrogen sulfate, 1-Butyl-3-methylimidazolium (bmim) hexafluorophosphate, 1-Ethyl-3-methylimidazolium (emim) hexafluorophosphate, 4-Methyl-N-butylpyridinium tetrafluoroborate, [bmim] bis(trifluoromethylsulfonyl)imide, [emim]ethylsulfate, 1-Butyl-3-methylimidazolium chloride, 1-Ethyl-3-methylimidazolium nitrite, 1-Ethyl-3-methylimidazolium tris(trifluoromethylsulfonyl)methide, N-Methyl-N-n-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-Ethyl-3-methylimidazolium tetrabromoaluminate(III), 1-Butyl-3-methylimidazolium tetrachloroferrate, or 1-Hexyloxymethyl-3-methylimidazolium tetrafluoroborate; and the concentration of the hydrogen fluoride dissolved in the ionic liquid is between 10% and 20% weight by weight of ionic liquid.