Extraction of gold

Abstract

Disclosed is a process for extracting gold ions from an aqueous phase containing gold ions. The process comprises contacting the aqueous phase with an extractant phase consisting of or comprising an ionic liquid (IL) under liquid-liquid extraction conditions for a time sufficient to allow transfer of at least some of the gold ions from the aqueous phase to the extractant phase; and separating the extractant phase from the aqueous phase.

1 . A process for extracting gold ions from an aqueous phase containing gold ions, the process comprising: contacting the aqueous phase with an extractant phase consisting of or comprising an ionic liquid (IL) under liquid-liquid extraction conditions for a time sufficient to allow transfer of at least some of the gold ions from the aqueous phase to the extractant phase; and separating the extractant phase from the aqueous phase, wherein the extractant phase does not contain an extraneous organic extractant. 
     
     
         2 . The process according to  claim 1 , the process further comprising recovering gold or gold ions from the extractant phase. 
     
     
         3 . The process according to  claim 1 , wherein the ionic liquid is selected from the group consisting of: ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-dodecyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide, 1-methyl-1-propylpiperidinium bis(trifluoromethylsulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide, tetradecyl(trihexyl)phosphonium bis(trifluoromethanesulfonyl)imide, tetradecyl(trihexyl)phosphonium chloride, methyltrioctylammonium bis(trifluoromethylsulfonyl)imide, and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide. 
     
     
         4 . (canceled) 
     
     
         5 . The process according to  claim 3 , wherein the ionic liquid is 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. 
     
     
         6 . The process according to  claim 1 , wherein the extractant phase comprises a volatile organic solvent and the ionic liquid. 
     
     
         7 . (canceled) 
     
     
         8 . The process according to  claim 6 , wherein the volatile organic solvent is selected from the group consisting of: chloroform, methanol, ethanol, acetone, toluene, and acetonitrile. 
     
     
         9 . The process according to  claim 6 , wherein the concentration of ionic liquid in the volatile organic solvent is less than or equal to about 20 v/v %. 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . (canceled) 
     
     
         13 . The process according to  claim 1 , wherein contacting the aqueous phase with the extractant phase is carried out under bulk liquid-liquid extraction conditions. 
     
     
         14 . (canceled) 
     
     
         15 . (canceled) 
     
     
         16 . The process according to  claim 13 , wherein the aqueous phase is contacted with the extractant phase in a respective volume-to-volume ratio of about 4:1. 
     
     
         17 . The process according to  claim 16 , wherein the bulk liquid-liquid extraction conditions include mixing the aqueous phase and the extractant phase for a period of about 1 minute to about 30 minutes. 
     
     
         18 . (canceled) 
     
     
         19 . (canceled) 
     
     
         20 . The process according to  claim 1 , wherein contacting the aqueous phase with the extractant phase is carried out under microfluidic solvent extraction conditions. 
     
     
         21 . The process according to  claim 20 , wherein the extractant phase consists essentially of the ionic liquid. 
     
     
         22 . The process according to  claim 21 , wherein the aqueous phase is contacted with the extractant phase in a respective flow rate-to-flow rate ratio that is greater than or equal to about 25:1. 
     
     
         23 . The process according to  claim 22 , wherein the aqueous phase is contacted with the ionic liquid with a residence time of less than about 2 seconds. 
     
     
         24 . The process according to  claim 23 , wherein greater than 90% of the gold ions are extracted from the aqueous phase. 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         27 . The process according to  claim 1 , wherein the process further comprises treating the aqueous phase to increase a concentration of inorganic anions in the aqueous phase prior to or during contact with the extractant phase. 
     
     
         28 . The process according to  claim 27 , wherein the inorganic anion comprises a halide ion selected from iodide, bromide, chloride, and fluoride. 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . (canceled) 
     
     
         32 . The process according to  claim 28 , wherein the halide ion comprises chloride and the process comprises treating the aqueous phase with HCl to increase the chloride concentration in the aqueous phase prior to contact with the extractant phase. 
     
     
         33 . The process according to  claim 32 , wherein the HCl is about 0.02M HCl, 3M HCl or 7M HCl. 
     
     
         34 . (canceled) 
     
     
         35 . (canceled) 
     
     
         36 . The process according to  claim 28 , wherein the halide ion comprises chloride and the process comprises treating the aqueous phase with KCl to increase the chloride concentration in the aqueous phase prior to contact with the extractant phase. 
     
     
         37 . (canceled)