A kind of method for preparing high-white ultrafine aluminum hydroxide with Bayer process aluminum hydroxide

Abstract

The invention belongs to the field of low-smoke halogen-free fire-retardant ultrafine aluminum hydroxide production and relates to a method for preparing high-whiteness ultrafine aluminum hydroxide from aluminum hydroxide prepared by a Bayer process. The method comprises the following steps of adding aluminum hydroxide prepared by a Bayer process into a dissolving tank with an evaporation mother liquid, carrying out stirring and steam heating for dissolution to obtain a supersaturated sodium aluminate solution with high suspended matter content, feeding the supersaturated sodium aluminate solution into a high-temperature high-pressure dissolving tank, feeding steam into the supersaturated sodium aluminate solution, keeping a temperature of 120-130 DEG C and pressure of 0.1-0.25MPa for 4-5h to obtain a sodium aluminate solution with low suspended matter content, feeding the sodium aluminate solution with low suspended matter content into a settling tank by a pump, adding lime milk into the settling tank for silicon removal and color removal, filtering the color-free refined liquid by a leaf filter to obtain refined liquid, carrying out heat exchange cooling, and then carrying out seed crystal decomposition, separation, washing, drying and dispersion to obtain the high-whiteness ultrafine aluminum hydroxide. The refined liquid obtained by the method has good quality. The method has simple processes and good operationality, realizes recovery and recycle of used materials in processes and basically realizes clean production.

Description

technical field [0001] The invention belongs to the field of producing low-smoke, halogen-free flame retardant superfine aluminum hydroxide, and in particular relates to a method for preparing high-white superfine aluminum hydroxide by Bayer process aluminum hydroxide. Background technique [0002] There are sintering method and Bayer method to produce aluminum hydroxide. The sintering method has complex process, high energy consumption and high cost, but the product has high purity, good quality and high added value; the aluminum hydroxide prepared by the sintering method is mainly used to produce high-quality, high value-added chemicals aluminum hydroxide and alumina ; while the Bayer process is simple, low energy consumption, low cost, low product purity, low added value, the aluminum hydroxide prepared by the Bayer process is mainly used to produce ordinary alumina. At present, the industrial production of ultra-fine high-white aluminum hydroxide basically uses expensiv...

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Problems solved by technology

The sintering method has complex process, high energy consumption and high cost, but the product has high purity, good quality and high added value; the aluminum hydroxide prepared by the sintering method is mainly used to produce high-quality, high value-added chemicals aluminum hydroxide and alumina ; while the Bayer process is simple, low energy consumption, low cost, low product purity, low added value, the aluminum hydroxide prepared by the Bayer process is mainly used to produce ordinary alumina

At present, the industrial production of ultra-fine high-white aluminum hydroxide basically uses expensive sintering sodium aluminate semen, and Bayer process sodium aluminate semen is also used to produce ultra-fine aluminum hydroxide through decolorization, but the whiteness cannot reach more than 98%. It belongs to medium-white ultra-fine aluminum hydroxide, and the production of high-quality, high-value-added ultra-fine high-white aluminum hydroxide with low-cost Bayer process aluminum hydroxide has not been realized

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