Method for preparing high-alkali high-causticity-ratio solution and improving traditional seed precipitation efficiency

Abstract

The invention discloses a method for improving the traditional seed precipitation efficiency and preparing high-alkali high-causticity-ratio solution from Bayer process seed precipitation mother liquor. The method comprises the steps that: the Bayer process seed precipitation mother liquor is introduced into a forced circulation evaporator, the liquor is evaporated to a state that the concentration of sodium oxide is 320 to 350 g/L, a salt discharge tank is introduced, the settling separation is carried out after staying for 4 to 8 hours, clear liquor is then introduced into the forced circulation evaporator for high-alkali evaporation to a state that the concentration of the sodium oxide is 530 to 600g/L, the materials are introduced into a crystallization reactor for crystallization, the temperature in a crystallizer to be 30 to 60 DEG C, the filtering is carried out after crystallization for 8 to 20 hours, and hydrated sodium aluminate crystals and mother liquor are obtained. The causticity ratio of the obtained hydrated sodium aluminate crystals is 1.3 to 1.7, and the obtained hydrated sodium aluminate crystals can be directly dissolved for the seed precipitation. The causticity ratio of the mother liquor is raised to 25 to 40, the mother liquor can be used for treating Bayer process red mud or low-quality bauxite, and in addition, alumina in the red mud is recovered. The method particularly creates conditions for recovering the alumina in the Bayer process red mud, the economic benefits are obvious, and simultaneously, the traditional seed precipitation efficiency is also effectively improved.

Description

[technical field] [0001] A method for preparing high-alkali and high-caustic ratio sodium aluminate solution from Bayer method seed separation mother liquor and improving the efficiency of traditional seed separation, involving a kind of seed separation mother liquor concentrated by forced circulation, and realizing aluminum-alkali separation through crystallization to improve mother liquor causticity Ratio, and at the same time, a method for preparing hydrated sodium aluminate crystals that can be dissolved for traditional Bayer process decomposition. [Background technique] [0002] At present, in the field of nonferrous metallurgy industry, the Bayer process and sintering process or the series (mixed connection) of the two processes are still used to produce alumina. [0003] In my country, 85% of alumina products come from the Bayer process, and the production of alumina by the Bayer process is still the mainstream production method in the world today. That is, under hig...

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Problems solved by technology

[0006] The purpose of the present invention is to solve the above-mentioned problems that high alkali and high caustic ratio circulating lye cannot be prepared from the current Bayer process system and the problem that the decomposition efficiency of seed fraction is low. Sodium aluminate circulating lye, and at the same time, a method for improving the recycling efficiency of Bayer process alumina

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