Method of recovering rare earth aluminum and silicon from rare earth-containing aluminum-silicon scraps

Abstract

Disclosed is a method of recovering rare earth, aluminum and silicon from rare earth-containing aluminum-silicon scrap. The method comprises: S1, acid-leaching the rare earth-containing aluminum-silicon scrap with an inorganic acid aqueous solution to obtain a silicon-rich slag and acid leached solution containing rare earth and aluminum element; S2, adding an alkaline substance into the acid leached solution containing the rare earth and aluminum element and controlling a PH value of the acid leaching solution between 3.5 to 5.2, performing a solid-liquid separation to obtain a aluminum hydroxide-containing precipitate and a rare earth-containing solution filter; S3, reacting the aluminum hydroxide containing precipitate with sodium hydroxide to obtain sodium metaaluminate solution and aluminum-silicon slag, and preparing a rare earth compound product with the rare earth-containing filtrate. The method dissolves an the aluminum and the rare earth with the acid and then via step wise alkaline conversion, convert aluminum icons to an aluminum hydroxide precipitate separated from rare earth ions, and then adds excessive amounts of sodium hydroxide to convert the aluminum hydroxide to a sodium metaaluminate solution, thereby realizing high-efficiency recovery of both rare earth and aluminum while significantly reducing the consumption of the sodium hydroxide and thus recovery cost.