Method and equipment for vaporizing full flash distillation of sodium aluminate liquor in technique for producing alumina

Abstract

This invention discloses device and method for completely flash-evaporating sodium aluminum solution during the production of aluminum oxide. The method comprises: (1) introducing the liquid to be evaporated from the raw liquid pool to a multi-stage canula preheater through a centrifuge pump; (2) heating the liquid by secondary steam in the multi-stage canula preheater and new steam in the new-steam preheater; (3) flash-evaporating in a multi-stage flash-evaporator; (4) discharging through a discharge pump to obtain evaporating mother liquid. This invention adopts two-step multi-stage preheating at different temperatures, and controls the temperature difference of multi-stage flash-evaporator cooling to between 10-13 deg.C, thus making full use of secondary steam, largely lower the investment and simplify the process.

Description

Technical field: [0001] The invention relates to an alumina evaporation method and equipment, belonging to the technical field of alumina production. Background technique: [0002] In the production process of Bayer process alumina, the water entering its circulation system mainly includes the following links: [0003] (1) Red mud washing water is added when washing red mud, usually 1.5-4.5t / t-dried red mud in production, and the amount of red mud washing water added when using bauxite to produce alumina is relatively uniform Diaspore is lower. [0004] (2) Aluminum hydroxide washing water, about 0.5~0.75t / t-Al 2 o 3 , [0005] (3) Water is added to other links, such as: vacuum system, pump shaft sealing water, lime digestion and causticizing process, water is added to ore. [0006] Therefore, in the Bayer alumina production process, evaporation is one of its important processes. Its task is to discharge excess water in the process, maintain the water balance in the Bay...

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Problems solved by technology

[0010] The disadvantages of this evaporation process are: high steam consumption, low production capacity of evaporation equipment, low equipment operation rate, large operation and maintenance workload, and it is not recommended to be used in the alumina industry.

[0015] At present, in the evaporation process of alumina plants, the above three evaporation processes and equipment are used at the same time, but all alumina plants have a common feature, that is, they all use evaporator groups, which are large-scale special equipment for the alumina industry. The equipment price is very high, the technological process and control system are relatively complicated, and a set of 6-effect tubular falling film evaporators with a steamed water capacity of 150-200t / h has a total investment of 60-85 million yuan.

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