Abstract: 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.

Abstract: 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.

Abstract: The invention provides a method of forming copper arsenate. Copper and arsenic are leached into a treatment solution maintained at a pH level of about 2 to 5 in the presence of at least one impurity. An oxidant is added to the treatment solution to oxidize the copper and arsenic. A copper arsenate compound is precipitated from the solution as copper arsenate. Preferably, the copper arsenate is then releached in a purification solution. The molar ratio of copper to arsenic is adjusted to a level of at least 2. The pH of the purification solution is then increased to precipitate copper arsenate having a decreased concentration of said at least one impurity. Impure copper arsenate may be suspended and reacted in a recrystallization solution preferably having cupric ion. The pH of recrystallization solution is adjusted to a valve between about 1 and 4.5.

Abstract: Uranium is leached from water slurries of uranium ore by incorporating a mixture of sulfur dioxide and air therein to provide the oxidizing and acidifying requirements to accomplish leaching.

Abstract: A process for removing sulfur dioxide from industrial gas streams by scrubbing the gas with an aqueous slurry including 2CaO.Fe.sub.2 O.sub.3 (dicalcium ferrite). The 2CaO.Fe.sub.2 O.sub.3 is present in lime slags or flotation tailings derived from non-ferrous smelting operations.