[′lēch ¦ī‚än iks¦chānj flō′tā·shən ‚prä·səs] (metallurgy) A method of extraction developed for treatment of copper ores not amenable to direct flotation; the metal is dissolved by leaching, for example, with sulfuric acid, in the presence of an ion-exchange resin; the resin recaptures the dissolved metal and is then recovered in a mineralized froth by the flotation process.