In flotation, a surface-active substance that has the active constituent in the
positive ion. Used to flocculate and to collect minerals that are not
flocculated by the reagents, such as oleic acid or soaps, in which the
surface-active ingredient is the negative ion. Reagents used are chiefly the
quaternary ammonium compounds; e.g., cetyl trimethyl ammonium bromide.
Source: Dictionary of Mining, Mineral, and Related Terms