Inco Limited

Cytec Technology Corporation

Goro Nickel S.a.

Indje O Mihaylov

Eberhard Krause

Cuong V Luong

Steve W Laundry

William A Rickelton

Bruce John Love

Pak Kuen Louie

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.

Regeneration of dithiophosphorus acid metal extractants

The invention provides a hydrometallurgical process for the recovery of metals. In particular, an aqueous feed solution originating from acid leaching is provided. The aqueous feed solution contains nickel and/or cobalt ions. The pH of the solution is maintained at a level between about 2 and 6. The aqueous feed solution is contacted with a water-immiscible organic phase containing an extractant to load the nickel and/or cobalt metal ions to form a metal-bearing organic phase. The extractant has at least one organic soluble dithiophosphinic acid, alkali, alkaline earth metal or ammonium salt thereof. The aqueous feed solution has sufficiently low levels of chromium (VI) ions, iron (III) ions and copper ions to allow repeated use of the extractant. The metal-bearing organic phase is then separated from the metal-containing aqueous feed solution. Finally, after separation from the aqueous feed solution, the metal-bearing organic phase is contacted with an aqueous strip solution to recover the loaded nickel and/or cobalt from the metal-bearing organic phase.

Process for the extraction and separation of nickel and/or cobalt

The invention provides a hydrometallurgical process for the recovery of metals. In particular, an aqueous feed solution derived from acid leaching is provided. The aqueous feed solution contains nickel and/or cobalt ions. The pH of the solution is maintained at a level between about 2 and 6. The aqueous feed solution is contacted with a water-immiscible organic phase containing an extractant to load the nickel and/or cobalt metal ions to form a metal-bearing organic phase. The extractant has at least one organic soluble dithiophosphinic acid, alkali, alkaline earth metal or ammonium salt thereof. The aqueous feed solution has sufficiently low levels of chromium (VI) ions and copper ions to allow repeated use of the extractant. The metal-bearing organic phase is then separated from the metal-containing aqueous feed solution. Finally, after separation from the aqueous feed solution, the metal-bearing organic phase is contacted with an aqueous strip solution to recover the loaded nickel and/or cobalt from the metal-bearing organic phase.

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Mississauga, Canada

Indje O Mihaylov