A process for cold hydrochemical decomposition of sodium hydrogen aluminosilicate. The process includes decomposing sodium hydrogen aluminosilicate at low temperature with a chelate to form a solution of soluble compounds and insoluble contaminants; separating the insoluble contaminants from the solution with a coagulator and heating to coagulate the silicic acid and form a silicic acid gel; separating the silicic acid gel to form a silicic acid-free solution; decomposing the silicic acid-free solution to form a precipitate of sodium hydrogen carboaluminate and a mother liquor; separating the precipitate from the mother liquor; concentrating, cooling and regenerating the mother liquor and forming sodium hydrogen carbonate; separating the sodium hydrogen carbonate from the regenerated solution; and calcining the sodium hydrogen carboaluminate at a temperature of about 700 to about 900° C. and forming sodium aluminate.

A microwave thermosolar method and device used in a tubular reactor (110) includes a conveyor for substrates defined as materials thus conveyed. According to this method, a step is provided for circulating an electric current in the conveyor in order to produce heat in this conveyor by Joule effect and optionally to cause, in the substrates, at least some of the following: curing, pyrolyses, gasifications, fusions and chemical reactions including oxidation-reduction reactions, under the action of the electric current.

Provided is a method for producing a reduced form of a metal oxide, the method being capable of preventing the production of carbon dioxide. A method for producing a reduced form of a metal oxide including irradiating a metal oxide and a high-melting-point material that is not in contact with the metal oxide with electromagnetic waves that are at least one of microwaves and millimeter waves to reduce at least a portion of the metal oxide, wherein a partition member is placed between the metal oxide and the high-melting-point material, the high-melting-point material has a melting point higher than the melting point of the metal oxide, and the high-melting-point material includes: an absorbent material that absorbs the electromagnetic waves in a temperature range that is at least partially lower than a temperature range in which the metal oxide absorbs the electromagnetic waves, and an insulation material that has a lower degree of absorption of the electromagnetic waves than the metal oxide.