Abstract: A method for making a rare earth metal salt of an organic acid, for example neodymium naphthenate, is provided. The method includes the steps of producing a three-phase system which comprises an aqueous phase in which is dissolved a salt of a rare earth metal or an alkali metal or alkaline earth metal salt, a solid water-insoluble rare earth compound suspended in the aqueous phase, and an organic phase containing the organic acid. The organic acid is allowed to distribute between the organic and aqueous phases, react with the dissolved inorganic salt and release an inorganic acid. This leads to some of the water-insoluble rare earth compound becoming dissolved in the aqueous phase and reacting with the organic acid to form a rare earth metal salt of the organic acid. The rare earth metal salt of the organic acid is allowed to transfer to the organic phase from whence it is recovered.

Abstract: A method of selectively recovering an arsenopyrite, pyrrhotite or like mineral from a material containing such a mineral and pyrite which includes the steps of providing a slurry of the material, adding a dialkyl (C.sub.3-8)-dithiophosphate to the slurry, passing a gas through the slurry to cause the mineral to be carried to the surface of the slurry and report in a first float concentrate, removing this concentrate from the slurry, activating the mineral remaining in the slurry by adding a suitable water-soluble copper salt to the slurry, adding a monoalkyl (C.sub.3-10)-dithiocarbamate to the slurry, passing a gas through the slurry to cause mineral to be carried to the surface of the slurry and form a second float concentrate, removing the second concentrate from the slurry and combining the first and the second float concentrates.