Lateral flow causticization process method and device

Abstract

A lateral-flow causticizing process and apparatus features that 1-3 lime milk baths and 4-6 causticizing baths are used for continuous causticizing, the secondary washing liquid in the red mud settling-washing procedure and the lime milk are fed in the first causticizing baths, and the finally causticized slurry is returned back to the settling-washing procedure. It is suitable for preparing alumina from trihydrated bauxite.

Description

Technical field: [0001] The invention relates to an alumina production process, in particular to a sodium carbonate causticization process method and device for alumina production. Background technique: [0002] In the Bayer Alumina Plant, the evaporation workshop is equipped with a salt discharge causticization process. The function of this process is to allow sodium carbonate to precipitate from the sodium aluminate solution during the evaporation process, and convert the precipitated sodium carbonate into caustic soda. The caustic soda is then returned to the process. [0003] The sodium carbonate in the process is mainly brought into the process by four aspects: [0004] (1) When the raw material is milled and mixed with lime, the lime usually contains 3-5% CO 2 . [0005] (2), brought into the ore, the ore usually contains 0.1 to 0.3% CO 2 . [0006] (3) Into the air, mainly during the production process, the sodium aluminate solution in the tank is in contact with...

AI Technical Summary

Problems solved by technology

There are many disadvantages in the causticization of salt discharge by evaporation, such as: the process becomes complicated, the operation of the salt discharge crystallizer greatly increases the steam consumption of the evaporator, and the precipitation of sodium carbonate during the evaporation process causes scarring and blockage of the heat exchange surface Pipes and valves affect the normal operation of the evaporator

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