A method for controlling the concentration of impurities in Bayer liquors, the method comprising the steps of adding an oxide and/or a hydroxide of a metal other than aluminium to a Bayer liquor with a desired TA forming a layered double hydroxide; and incorporating at least one impurity in the layered double hydroxide, wherein the impurities are selected from the group comprising chloride, fluoride, sulfate and TOC.

A Bayer process increases oxalate removal in the red side of the Bayer process and at least substantially minimises, for example by at least substantially suppressing, precipitation of oxalates in the white side of the Bayer process.

A method of dewatering sludge is provided herein. In some embodiments, the method includes introducing micronized dry water soluble polymer (DWSP) particles into a sludge, wherein the sludge includes water and solids; separating water of the sludge from solids of the sludge using the micronized DWSP particles; and collecting a wet solid including water and solids of the sludge, wherein a concentration of solids in the wet solid is higher than a concentration of solids in the sludge, wherein the micronized DWSP particles comprise a DWSP wherein the DWSP is selected from the group consisting of a dry anionic water soluble polymer, a dry cationic water soluble polymer, a dry nonionic water soluble polymer, and mixtures thereof, and wherein a mean particle size of the micronized DWSP particles ranges from about 100 to about 300 microns.

Disclosed is a method for processing bauxites to produce alumina comprising: filtering an alumina slurry obtained after a digestion of the bauxites, the slurry, after leaching, dilution or thickening, is filtered at a temperature of at least 95 C. to obtain a filtrate representing a green liquor after the filtration and a solid phase of a red mud on filtration equipment; and washing the solid phase of the red mud on the filtration equipment, the washing being carried out with hot water at a temperature of below 98 C. the filtrate being subjected to security filtration or precipitation, and the water after washing the red mud on the filtration equipment is fed for dilution of the alumina slurry after the digestion of the bauxites or dilution of the filtrate to obtain a specified concentration of the green liquor, wherein a resulting cake is a waste product.

Disclosed is a method for processing bauxites to produce alumina comprising: filtering an alumina slurry obtained after a digestion of the bauxites, the slurry, after leaching, dilution or thickening, is filtered at a temperature of at least 95 C. to obtain a filtrate representing a green liquor after the filtration and a solid phase of a red mud on filtration equipment; and washing the solid phase of the red mud on the filtration equipment, the washing being carried out with hot water at a temperature of below 98 C. the filtrate being subjected to security filtration or precipitation, and the water after washing the red mud on the filtration equipment is fed for dilution of the alumina slurry after the digestion of the bauxites or dilution of the filtrate to obtain a specified concentration of the green liquor, wherein a resulting cake is a waste product.

Methods and compositions for improving performance of flocculants in an industrial production process. Methods include pH triggered cross-linking reaction between a flocculating agent, such as dextran, and a composition comprising a boronic acid-containing polymer. The pH trigger can be provided by a fluid having a pH of 8 or more. The production process can be a Bayer Process and the fluid is caustic liquor or slurry in the fluid circuit of the Bayer, wherein the reaction time is reduced over conventional methods and the cross-linked dextran composition effectuates improved flocculation of the trihydrate particles.

Methods and compositions for improving performance of flocculants in an industrial production process. Methods include pH triggered cross-linking reaction between a flocculating agent, such as dextran, and a composition comprising a boronic acid-containing polymer. The pH trigger can be provided by a fluid having a pH of 8 or more. The production process can be a Bayer Process and the fluid is caustic liquor or slurry in the fluid circuit of the Bayer, wherein the reaction time is reduced over conventional methods and the cross-linked dextran composition effectuates improved flocculation of the trihydrate particles.

A method of purifying a spinel powder includes contacting a spinel powder with an acid solution to form an acid-washed spinel composition and contacting the acid-washed spinel composition with a basic solution to form a purified composition. The purified powder is suited to formation of low-absorption shaped bodies, such as windows for high intensity laser devices.

A method of purifying a spinel powder includes contacting a spinel powder with an acid solution to form an acid-washed spinel composition and contacting the acid-washed spinel composition with a basic solution to form a purified composition. The purified powder is suited to formation of low-absorption shaped bodies, such as windows for high intensity laser devices.

Methods and compositions for improving performance of flocculants in an industrial production process. Methods include pH triggered cross-linking reaction between a flocculating agent, such as dextran, and a composition comprising a boronic acid-containing polymer. The pH trigger can be provided by a fluid having a pH of 8 or more. The production process can be a Bayer Process and the fluid is caustic liquor or slurry in the fluid circuit of the Bayer, wherein the reaction time is reduced over conventional methods and the cross-linked dextran composition effectuates improved flocculation of the trihydrate particles.