Abstract: This is a method of regenerating dithiophosphorus acids from disulfides containing sulfur--sulfur bonds, formed by oxidation of dithiophosphorus acids, such as sulfur--sulfur bonding of dithiophosphoric, dithiophosphonic and dithiophosphinic acids, in a solvent extraction organic phase in which the dithiophosphorus acid is dissolved in a diluent. This process reacts metal directly with the organic solution containing the disulfide to produce a metal loaded complex form of the regenerated dithiophosphorus extractant in the organic solution. This metal complex forms by direct reaction of the metal with the disulfides without requiring the presence or the formation of nascent or gaseous hydrogen. The organic solution containing the regenerated dithiophosphorus extractant can be either directly recycled into a solvent extraction circuit or recycled after the loaded metal is stripped.

Abstract: A method for electrochemically minimizing sulfide scale buildup on a metal surface by connecting the surface as an anode and periodically reversing the current flow at predetermined intervals.

Abstract: A method is provided for conditioning nickel laterite pregnant leach liquor in preparation for the recovery of nickel therefrom in which pregnant leach liquor is mixed in a reaction vessel under atmospheric pressure with an amount of roasted high-magnesium nickeliferous silicate ore to form a pulp thereof, the amount of roasted ore being at least sufficient to lower the free acid content of pregnant liquor entering the thickener to a level corresponding to a pH ranging from about 1.8 to 3. The pregnant liquor is conditioned by stirring the pulp thereof at a temperature not exceeding 100.degree. C. for a time sufficient to lower the free acid content of the resulting conditioned pregnant liquor to the desired level and to effect substantial precipitation of iron as iron hydroxide and dissolved silica in the liquor.