Abstract: A process for removing metals from a waste including uranium and a second metal comprising dissolving the uranium and the second metal in a first aqueous solution, removing the dissolved uranium from the first aqueous solution by redissolving in an organic solvent, stripping the uranium from the organic solvent by redissolving in a second aqueous solution, precipitating the uranium from the second aqueous solution, and removing the second metal from the first aqueous solution.

Abstract: A novel process for the recovery of alumina and potassium sulfate from alunite is provided comprising leaching the alunite with potassium hydroxide to which no sodium materials have been added, said leach solution being saturated with potassium sulfate. Aluminum values are solubilized into the leachate, and potassium and sulfur values are rendered soluble, but remain in the residue. The leachate is desilicated if necessary, preferably with lime, and aluminum trihydroxide is precipitated therefrom, followed by calcining to alumina product. The residue is leached to solubilize potassium sulfate in a secondary leach and the potassium sulfate product crystallized therefrom. Potassium hydroxide is regenerated from a portion of the potassium sulfate secondary leachate by several methods.Novel procedures for regenerating alkali metal hydroxides from the corresponding sulfates are also provided including routes involving formates and carbonates as intermediates and pyrohydrolysis.

Abstract: Improvement in electrowinning manganese dioxide, or zinc in which the relative concentration of manganese or zinc ions to impurities is enhanced by selectively extracting manganese or zinc ions from a bleed taken from the electrowinning feed stream with an organic extractant, while rejecting impurities, stripping the loaded organics with spent electrolyte, and recycling loaded strip to the electrowinning feed. Stripped organic may be regenerated with an alkaline agent such as calcium oxide or magnesium oxide prior to recycle, and pH may be controlled during extraction by the same means.