Bayer process red mud washing method and system thereof in production process of aluminum oxide

Abstract

An embodiment of the invention provides a Bayer process red mud washing method and a system thereof in a production process of aluminum oxide. The method comprises the following steps: qualified ore pulp is sent into a dissolution process, and dissolved ore pulp is diluted with red mud washing liquor; diluted dissolved ore pulp is conveyed to a vacuum filtration filter with a plate which can be turned over, and water is used for diluting and separating underflow; the diluted and separated underflow of low concentration enters a filtering plate, and water is added into the filtering plate for washing; the filtering plate is turned over for discharging mud, and Bayer process red mud washing is completed. The dissolution rate of aluminum oxide is improved, production cost of aluminum oxide is reduced, and settlement can be carried out without addition of flocculating agents.

Description

technical field [0001] The embodiment of the present application relates to the technical field of alumina, in particular to a method and system for washing red mud by the Bayer process in the alumina production process. Background technique [0002] In the production of alumina, the Bayer method is currently the main production method. Its processes include: raw materials, dissolution, sedimentation, decomposition, evaporation, and roasting. In the sedimentation process, the sedimentation tank is basically used. For the liquid-solid separation of red mud, the settling tank is also a very stable liquid-solid separation equipment, but the separation and washing time is too long, about 120 hours. During the separation and washing process, the alumina in the crude liquid undergoes a hydrolysis reaction due to the decrease in temperature and concentration, which reduces the alumina production by 2 to 3% in the sedimentation process. [0003] Specifically, the settling process o...

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Problems solved by technology

The residence time of the dissolution slurry in the separation tank is about 4-7 hours, and the residence time in the washing tank is about 100-120 hours. During this time, due to the addition of water to wash, the alumina in the crude liquid is diluted and the concentration decreases. With the extension of time, the temperature of the entire slurry decreases, and a hydrolysis reaction causes the alumina in the liquid to undergo red mud, resulting in a decrease in the dissolution rate and an increase in the various unit consumption of alumina production.

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