The present disclosure relates to processes for recovering rare earth elements from an aluminum-bearing material. The processes can comprise leaching the aluminum-bearing material with an acid so as to obtain a leachate comprising at least one aluminum ion, at least one iron ion, at least one rare earth element, and a solid, and separating the leachate from the solid. The processes can also comprise substantially selectively removing at least one of the at least one aluminum ion and the at least one iron ion from the leachate and optionally obtaining a precipitate. The processes can also comprise substantially selectively removing the at least one rare earth element from the leachate and/or the precipitate.

A process for extracting values from a leach residue from lithium extraction comprising:

(a) mixing the leach residue with a chloride containing compound to form a first mixture;

(b) calcining the first mixture to form a calcined mixture rich in calcium aluminosilicate and a hydrochloric acid containing off gas;

(c) acid leaching the calcined mixture to form an aluminium bearing liquor and a silicon rich solid residue;

(d) recovering values selected from the group consisting of aluminium compounds, silicon compounds and compounds containing silicon and aluminium.

A process for extracting values from a leach residue from lithium extraction comprising:

(a) mixing the leach residue with a chloride containing compound to form a first mixture;

(b) calcining the first mixture to form a calcined mixture rich in calcium aluminosilicate and a hydrochloric acid containing off gas;

(c) acid leaching the calcined mixture to form an aluminium bearing liquor and a silicon rich solid residue;

(d) recovering values selected from the group consisting of aluminium compounds, silicon compounds and compounds containing silicon and aluminium.

There are provided processes for converting alumina into -Al.sub.2O.sub.3 or transition alumina that comprise heating the alumina at a temperature of about 900 C. to about 1200 C. in the presence of steam and optionally at least one gas under conditions suitable to obtain the -Al.sub.2O.sub.3 or transition alumina. For example, the alumina can comprise a transition alumina (such as -Al.sub.2O.sub.3), an amorphous alumina or a mixture thereof.

The invention relates to metallurgy, particular to acid methods for producing alumina, and can used in processing aluminum-containing raw materials, including those of a low-grade. The method for producing alumina comprises treating aluminum-containing raw materials with hydrochloric acid, separating aluminum chloride hexahydrate crystals from the supernatant chloride solution, and thermally decomposing said crystals in two stages to produce alumina. In order to increase the quality of alumina and decrease energy consumption while achieving high process productivity, water vapor is continuously introduced during the second stage of thermal decomposition, with a ratio of the total mass of the introduced water vapor to the mass of produced alumina equal to 0.2-5.7.

The present invention aims to provide a simple and efficient method for manufacturing -alumina particles, main component particles of which each have a crystal face other than the face [001] as a main crystal face and a polyhedral shape other than a hexagonal bipyramidal shape. According to the method for manufacturing -alumina particles of the present invention, when an aluminum compound is calcined in the presence of a specific content of a metal compound, -alumina particles each having a particle diameter of 50 m or less, a degree of crystallization of 90% or more, and a polyhedral shape can be obtained.

Provided herein is a process for producing a high-purity alumina, comprising the steps of: (a) sublimation of anhydrous aluminium chloride at a predetermined temperature to recover pure aluminium chloride; (b) dissolving aluminium chloride from step (a) in water to obtain aluminium chloride solution; (c) introducing HCl gas into aluminium chloride solution of step (b) to crystallize aluminium chloride hexahydrate; and (d) calcining aluminium chloride hexahydrate of step (c) to obtain high purity alumina.

Provided herein is a process for producing a high-purity alumina, comprising the steps of: (a) sublimation of anhydrous aluminium chloride at a predetermined temperature to recover pure aluminium chloride; (b) dissolving aluminium chloride from step (a) in water to obtain aluminium chloride solution; (c) introducing HCl gas into aluminium chloride solution of step (b) to crystallize aluminium chloride hexahydrate; and (d) calcining aluminium chloride hexahydrate of step (c) to obtain high purity alumina.

Provided is a method and apparatus for producing inorganic powder using chemical vapor synthesis (CVS), the method and apparatus being capable of increasing a production yield by suppressing side reactions and of increasing continuous process stability by preventing reactor blockage, and the method includes supplying a precursor, supplying a side reaction prevention gas capable of preventing side reactions of the precursor, to the precursor, supplying a reaction gas to the precursor, and forming inorganic powder due to a chemical reaction between the precursor and the reaction gas.

Provided is a method and apparatus for producing inorganic powder using chemical vapor synthesis (CVS), the method and apparatus being capable of increasing a production yield by suppressing side reactions and of increasing continuous process stability by preventing reactor blockage, and the method includes supplying a precursor, supplying a side reaction prevention gas capable of preventing side reactions of the precursor, to the precursor, supplying a reaction gas to the precursor, and forming inorganic powder due to a chemical reaction between the precursor and the reaction gas.