This invention relates to an composition, comprising A) at least one quaternary ammonium compound which is a collector for the reverse flotation of magnesium minerals from calcium carbonate B) at least one antifoam agent C) a solvent
and its use in the reverse flotation of calcium carbonate.

Collectors for froth flotation including oxidized fatty acid compositions and oxidized and maleated compositions. In particular, use of oxidized tall oil compositions and oxidized and maleated fatty acid compositions are disclosed.

Disclosed herein are methods and systems for recovery of ancylite, a rare earth mineral comprising strontium carbonate, from rare earth ore. In many embodiments, the disclosed methods and systems provide for recovery of greater than 50% of the ancylite from an ancylite containing ore. In many embodiments, the ore is subjected to flotation in the presence of an acid, for example a hydroxamic acid, such as octanohydroxamic acid. The ore may also be subjected to magnetic separation, for example wet high intensity magnetic separation.