Abstract: This invention provides a method to recover valuable DTPA from DTPA solvent extraction organic solution that avoids the need to operate at either high or very low temperatures, with extended reaction times and having to carry out solid/liquid separation on organic solution. Furthermore, the invention provides the flexibility of selecting appropriate base solution to carry out the DTPA recovery process and further provides the ability to directly treat metal-containing DTPA organic solution.

Abstract: A process for producing a purified nickel hydroxide precipitate from a nickel-containing leach solution with impurities including one or more of the following: manganese, copper, zinc, iron and/or cobalt, so that the purified nickel hydroxide is suitable for pelletization with iron-containing ores and/or stainless steel production, includes treating the leach solution with a base to form a slurry of mixed hydroxide precipitate and low-nickel barren solution, thickening the slurry to form filter cake, washing the filter cake and contacting it with acid to dissolve nickel and other metals to produce a concentrated nickel-containing solution, subjecting the concentrated nickel-containing solution to solvent extraction with an organic acid extractant to remove metals other than nickel from the nickel-containing solution and form a solvent extraction raffinate of purified nickel solution and treating the solvent extraction raffinate with a base to precipitate the purified nickel hydroxide precipitate.

Abstract: A method for selective removal of cadmium from a feed solution also containing other metals such as nickel (Ni) and/or cobalt (Co), utilizing a thiourea based ion exchange resin, and a method for eluting cadmium adsorbed on the thiourea based resin.

Abstract: A process for producing a purified nickel hydroxide precipitate from a nickel-containing leach solution with impurities including one or more of the following: manganese, copper, zinc, iron and/or cobalt, so that the purified nickel hydroxide is suitable for pelletization with iron-containing ores and/or stainless steel production, includes treating the leach solution with a base to form a slurry of mixed hydroxide precipitate and low-nickel barren solution, thickening the slurry to form filter cake, washing the filter cake and contacting it with acid to dissolve nickel and other metals to produce a concentrated nickel-containing solution, subjecting the concentrated nickel-containing solution to solvent extraction with an organic acid extractant to remove metals other than nickel from the nickel-containing solution and form a solvent extraction raffinate of purified nickel solution and treating the solvent extraction raffinate with a base to precipitate the purified nickel hydroxide precipitate.

Abstract: A method for selective removal of cadmium from a feed solution also containing other metals such as nickel (Ni) and/or cobalt (Co), utilizing a thiourea based ion exchange resin, and a method for eluting cadmium adsorbed on the thiourea based resin.

Abstract: The invention provides a method of regenerating dithiophosphorus extractants such as dithiophosphoric acids, dithiophosphonic acids and dithiophosphinic acids from their sulfur-sulfur bonded oxidation products contained in an organic solution. The process generates active hydrogen for regenerating the spent dithiophosphorus extractants. Advantageously, this active hydrogen originates either from introducing a reactive metal into a liquid mixture containing the organic solution and an acidic aqueous solution to form nascent hydrogen or from using hydrogen gas in the presence of a catalyst in the organic solution. The active hydrogen generated in the process breaks the sulfur-sulfur bonds of the dithiophosphorus molecules to form the corresponding dithiophosphorus acids.