This invention relates to a hydrometallurgical process for the recovery and separation of valuable precious, base or rare elements such as platinum group metals (PGMs), gold or silver, and other valuable base and rare metals such as nickel, cobalt, copper, rare earth elements (REE), yttrium and scandium, as well as uranium, thorium, manganese, zinc, cadmium, molybdenum, titanium, tin, and other minor elements such as vanadium, germanium and gallium from a feed material comprising ores, concentrates and other materials. In particular, the process comprises quantitative removal of additional base, rare and gangue elements for increased efficiency of further treatment of the solids for valuable metals recovery and/or recycling and/or separation of valuable metals from pressure leach residue and may be integrated into one or more existing valuable element extraction processes.

A method of processing a purified rare earth sulphate solution, the method including the steps of: contacting the purified rare earth sulphate solution with sodium hydroxide to precipitate rare earths as rare earth hydroxide, including the addition of an oxidant to oxidise cerium contained in the rare earth hydroxide precipitate; and selectively leaching the rare earth hydroxide precipitate with hydrochloric acid to form a rare earth chloride solution and a residue.

A method of processing a purified rare earth sulphate solution, the method including the steps of: contacting the purified rare earth sulphate solution with sodium hydroxide to precipitate rare earths as rare earth hydroxide, including the addition of an oxidant to oxidise cerium contained in the rare earth hydroxide precipitate; and selectively leaching the rare earth hydroxide precipitate with hydrochloric acid to form a rare earth chloride solution and a residue.

A method for extracting and enriching gold with a selenide includes: mixing an isocyanate and a selenium-containing compound of a formula of HO—R—Se—R—OH in a solvent to obtain a mixture system, where R is selected from linear or branched C.sub.2 to C.sub.11 alkylene groups; adding a tin-based catalyst into the mixture system to activate a reaction, drying the mixture system after the reaction, and obtaining a powdery selenium-containing polymer by grinding; immersing the selenium-containing polymer in an aqueous solution containing gold ions to allow gold to be extracted from the aqueous solution; and removing the selenium-containing polymer attached to a surface of extracted gold, thereby obtaining an extracted and enriched gold.

The invention discloses a method of solution mining trona by injecting an aqueous solvent into an underground cavity comprising trona to dissolve trona in the aqueous solution and removing the aqueous solution from the cavity at about the WTN triple point (the temperature at which solid phase wegscheiderite, trona, and nahcolite can co-exist in an aqueous solution). Alkaline values from the removed aqueous solution are recovered to produce a barren liquor. The method further includes either (i) treating the barren liquor to produce an aqueous solvent or (ii) treating injected aqueous solvent to reduce clogging at the trona dissolution surface caused by supersaturation of sodium bicarbonate, and precipitation of nahcolite and wegscheiderite as the aqueous solution in the cavity approaches saturation of both dissolved sodium bicarbonate and sodium carbonate.

The invention discloses a method of solution mining trona by injecting an aqueous solvent into an underground cavity comprising trona to dissolve trona in the aqueous solution and removing the aqueous solution from the cavity at about the WTN triple point (the temperature at which solid phase wegscheiderite, trona, and nahcolite can co-exist in an aqueous solution). Alkaline values from the removed aqueous solution are recovered to produce a barren liquor. The method further includes either (i) treating the barren liquor to produce an aqueous solvent or (ii) treating injected aqueous solvent to reduce clogging at the trona dissolution surface caused by supersaturation of sodium bicarbonate, and precipitation of nahcolite and wegscheiderite as the aqueous solution in the cavity approaches saturation of both dissolved sodium bicarbonate and sodium carbonate.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.

This application pertains to methods of recovering metals from metal sulfides that involve contacting the metal sulfide with an acidic sulfate solution containing ferric sulfate and a reagent that has a thiocarbonyl functional group, wherein the concentration of reagent in the acidic sulfate solution is sufficient to increase the rate of metal ion extraction relative to an acidic sulfate solution that does not contain the reagent, to produce a pregnant solution containing the metal ions.