Method and system capable of improving alumina seed decomposition rate

Abstract

The invention discloses a method and a system capable of improving alumina seed decomposition rate, the method is characterized in that a causticizing solution generated by a causticizing system in Bayer process alumina production is added to a refined sodium aluminate seed decomposition system, the concentration of caustic alkali of the added causticizing solution is 30-100g / l, the causticizing ratio alpha k30-200, the causticizing ratio alpha k30-200, and the causticizing ratio alpha k30-200. The concentration of caustic alkali in the refined sodium aluminate solution is 150-170g / L, the caustic ratio alpha < k > is 1.38-1.50, the initial decomposition temperature is 58-63 DEG C, the final decomposition temperature is 45-52 DEG C, and the decomposition time is 40-50h; by utilizing the characteristics of low caustic alkali concentration and high caustic ratio alpha k of the salt elimination causticizing liquid, the method has important contribution to improving the seed decomposition rate of the Bayer process, can break through the existing seed decomposition rate level, is beneficial to seed decomposition of the Bayer process sodium aluminate solution and improves the seed decomposition rate.

Description

technical field [0001] The invention relates to a method and a system for improving the decomposition rate of alumina species, belonging to the technical field of alumina production. Background technique [0002] With the gradual depletion of bauxite ore resources, the content of impurities in the ore gradually increases, especially the increase in the content of impurities such as carbon and sulfur in the ore has a serious impact on the alumina production process. Carbon in bauxite ore mainly exists in the form of carbonate. In the production process of alumina by Bayer process, carbonate in bauxite ore enters into sodium aluminate solution as sodium carbonate, resulting in sodium aluminate solution. The concentration of sodium carbonate gradually increases, causing changes in the physical properties of the sodium aluminate solution, seriously affecting the process links such as dissolution, evaporation and decomposition, resulting in the inability of the system to run stab...

AI Technical Summary

Problems solved by technology

The carbon in bauxite ore mainly exists in the form of carbonate. During the production process of Bayer process alumina, the carbonate in bauxite ore is formed as sodium carbonate and enters into the sodium aluminate solution, resulting in the formation of sodium aluminate solution. The concentration of sodium carbonate gradually increases, causing changes in the physical properties of the sodium aluminate solution, seriously affecting the process links such as dissolution, evaporation, and decomposition, causing the system to fail to operate stably, resulting in a reduction in alumina production or even shutdown, resulting in increased system consumption and increased production costs.

An increase in the concentration of sodium carbonate will cause a change in the material properties of the sodium aluminate solution, especially an increase in the viscosity of the sodium aluminate solution, which will affect the mass transfer driving force in the decomposition process of the species, thereby reducing the decomposition rate of the alumina species and causing the system The cycle efficiency is low, thereby reducing the efficiency of production operations, increasing system consumption and production costs

After the concentration of sodium carbonate in the sodium aluminate solution rises, the balance of sodium carbonate concentration in the system must be achieved through the causticization process of salt discharge. The process of causticization of salt discharge will produce a large amount of causticizing liquid, and the causticizing liquid directly entering the red mud sedimentation washing system will cause The increase in the amount of semen in the system not only increases the transport load of the semen system and shortens the decomposition time, but also causes the semen causticity ratio ɑk, which is not conducive to improving the decomposition rate of the species, especially as the carbon content of the ore gradually increases, the causticization system The increase in fluid volume is more prominent

In order to alleviate the actual production problem of the low seed fractionation rate in the alumina production system under high-carbon alkali conditions, the applicant believes that there is still room for improvement in the seed fractionation rate based on years of work experience

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