A method for preparing high purity alumina (HPA) is provided. The method includes subjecting an aluminum feedstock to acid leaching, thereby yielding an aluminum bearing leachate; subjecting the aluminum bearing leachate to solvent extraction, thereby yielding an organic phase which is loaded with aluminum; stripping the aluminum from the loaded organic phase with a stripping solution containing an acid, thereby yielding an aluminum bearing extract; crystallizing an aluminum salt from the aluminum bearing extract; dissolving the aluminum salt in an ammoniacal solution, thereby generating a boehmite precursor compound and an ammonium salt; calcining the boehmite precursor compound to yield HPA; subjecting the ammonium salt to electro-dialysis, thereby yielding ammonia and the acid; and performing at least one step of (a) utilizing the ammonia in preparing the ammoniacal solution used in a subsequent iteration of the method, or (b) utilizing the acid in preparing the stripping solution used in a subsequent iteration of the method.

A method for preparing high purity alumina (HPA) is provided. The method includes subjecting an aluminum feedstock to acid leaching, thereby yielding an aluminum bearing leachate; subjecting the aluminum bearing leachate to solvent extraction, thereby yielding an organic phase which is loaded with aluminum; stripping the aluminum from the loaded organic phase with a stripping solution containing an acid, thereby yielding an aluminum bearing extract; crystallizing an aluminum salt from the aluminum bearing extract; dissolving the aluminum salt in an ammoniacal solution, thereby generating a boehmite precursor compound and an ammonium salt; calcining the boehmite precursor compound to yield HPA; subjecting the ammonium salt to electro-dialysis, thereby yielding ammonia and the acid; and performing at least one step of (a) utilizing the ammonia in preparing the ammoniacal solution used in a subsequent iteration of the method, or (b) utilizing the acid in preparing the stripping solution used in a subsequent iteration of the method.

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.

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.

Disclosed herein, is a process for recovering valuable metals and/or their oxides from red mud bauxite residues or similar. The process comprises: calcining a red mud residue having a pH of less than about 10 to provide a calcinated red mud residue; acid leaching the calcinated red mud residue to provide a silica rich solid component and an acid leachate; separating the silica rich solid component and the acid leachate; precipitating an iron rich solid component from the acid leachate; and separating the precipitated iron rich solid component from the acid leachate to provide an aluminium rich liquor.

Disclosed herein, is a process for recovering valuable metals and/or their oxides from red mud bauxite residues or similar. The process comprises: calcining a red mud residue having a pH of less than about 10 to provide a calcinated red mud residue; acid leaching the calcinated red mud residue to provide a silica rich solid component and an acid leachate; separating the silica rich solid component and the acid leachate; precipitating an iron rich solid component from the acid leachate; and separating the precipitated iron rich solid component from the acid leachate to provide an aluminium rich liquor.

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 hydroxidee 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.

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 hydroxidee 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.