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.

Methods and systems are provided, which convert spent electrolyte from aluminum-air batteries into high purity alumina (HPA) and useful co-products such as fertilizer(s) and/or feed supplement(s). Aluminum tri-hydroxide (ATH) having potassium (K) and/or sodium (Na) impurities, e.g., from spent electrolyte, may be dissolved in strong acid to form an acidic ATH solution having pH<4. Consecutively, the acidic ATH solution may be neutralized to pH>4 to precipitate ATH while retaining dissolved K/Na in the neutralized solution. The dissolving and the neutralizing may then be repeated with the precipitated ATH until a specified purity level of the precipitated ATH is reached. Using appropriate bases to neutralize the acidic ATH solution, e.g., ammonia and/or choline, yields useful co-products such as ammonium nitrate (with nitric acid as the strong acid) and choline chloride (with hydrochloric acid as the strong acid), respectively.

Methods and systems are provided, which convert spent electrolyte from aluminum-air batteries into high purity alumina (HPA) and useful co-products such as fertilizer(s) and/or feed supplement(s). Aluminum tri-hydroxide (ATH) having potassium (K) and/or sodium (Na) impurities, e.g., from spent electrolyte, may be dissolved in strong acid to form an acidic ATH solution having pH<4. Consecutively, the acidic ATH solution may be neutralized to pH>4 to precipitate ATH while retaining dissolved K/Na in the neutralized solution. The dissolving and the neutralizing may then be repeated with the precipitated ATH until a specified purity level of the precipitated ATH is reached. Using appropriate bases to neutralize the acidic ATH solution, e.g., ammonia and/or choline, yields useful co-products such as ammonium nitrate (with nitric acid as the strong acid) and choline chloride (with hydrochloric acid as the strong acid), respectively.

The invention relates to a method of producing a binder comprising the steps of preparing (20) a residual material comprising amorphous alumina-rich and/or aluminium hydroxide-rich constituents, heating (30) the residual material to produce a fired material, the heating (30) of the residual material being at a temperature of >800° C.

The invention relates to the use of a hydraulic binder containing calcium aluminate, obtainable by a method in which a) prepared amorphous residual material rich in aluminium oxide and/or aluminium hydroxide is heated after the addition of a b) calcium ion-containing binder component and c) water, for the production of a constructing material.

A method for processing water treatment residuals, or other amorphous aluminium oxide or aluminium hydroxide rich waste residuals, for use in the manufacture of hydraulic binders, comprising heating the residuals to remove water and oxidise organic material contained therein, comprising controlling the temperature of the residuals during heating such that they are heated to a temperature no higher than 800° C., more preferably no higher than 650° C., to ensure that aluminium compounds in the WTR, in particular aluminium oxide and aluminium hydroxide, remain in an amorphous state. The method may comprise controlling the temperature of the water treatment residuals such that they are heated to a temperature between 350° C. and 650° C., more preferably between 400° C. and 500° C.

A method for processing water treatment residuals, or other amorphous aluminium oxide or aluminium hydroxide rich waste residuals, for use in the manufacture of hydraulic binders, comprising heating the residuals to remove water and oxidise organic material contained therein, comprising controlling the temperature of the residuals during heating such that they are heated to a temperature no higher than 800° C., more preferably no higher than 650° C., to ensure that aluminium compounds in the WTR, in particular aluminium oxide and aluminium hydroxide, remain in an amorphous state. The method may comprise controlling the temperature of the water treatment residuals such that they are heated to a temperature between 350° C. and 650° C., more preferably between 400° C. and 500° C.

A bauxite processing method including: preliminarily grinding bauxites; mixing the bauxites as ground with magnetic field treated water into a pulp; exposing the pulp in a reaction chamber to a rotating magnetic field created by rotating ferromagnetic elements, carried out in a vortex layer generated by ferromagnetic elements rotating at a speed of at least 2800 rpm, to achieve a magnetoelastic effect and provide forces and energies which enable metal reduction; and separating a resulting metal oxide mixture.

A bauxite processing method including: preliminarily grinding bauxites; mixing the bauxites as ground with magnetic field treated water into a pulp; exposing the pulp in a reaction chamber to a rotating magnetic field created by rotating ferromagnetic elements, carried out in a vortex layer generated by ferromagnetic elements rotating at a speed of at least 2800 rpm, to achieve a magnetoelastic effect and provide forces and energies which enable metal reduction; and separating a resulting metal oxide mixture.

The present invention refers to a process for the preparation of a high surface area nanoparticulate alpha alumina.