Method for producing aluminium oxide by middle-low grade alumyte

Abstract

A method to produce aluminum oxide with middle-low bauxite relates to a method to produce aluminum oxide with middle-low bauxite by the means of Bayer-method. The invention is characterized in that: during the Bayer-method process, digestion process is to add dealuminization slag instead of lime as additive in middle-low bauxite to do Bayer process digestion; after digestion and backward washing of red mud, the red mud is mixed with recycle alkaline liquor, the lime is added, the digestion reaction is done, the red mud is separated from the slurry and discharged outside, the solution part obtained oppositely washes with Bayer-method, is sent to Bayer-method system to supplement alkali after digesting the red mud, the lime is added partly and is reacted, then, dealuminization slag and recycle alkaline liquor that goes through Bayer-method red mud wet treatment are gotten and dealuminization slag calcium aluminate hydrate instead of lime is added into the Bayer process digestion. The method of the invention belongs to all wet treatment, has simple process, low energy consumption, low alkali consumption and high recovery rate of aluminum oxide and is suitable for treating Chinese bauxite that is mainly middle-low bauxite; besides, the resource utilization is high, the amount of discharged red mud is low and the red mud is easy to be utilized comprehensively.

Description

technical field [0001] The invention discloses a method for producing alumina from middle and low grade bauxite, which relates to a method for producing alumina by processing middle and low grade bauxite by Bayer method. technical background [0002] my country's bauxite resources are mostly high-alumina, high-silicon, low-iron, and medium-grade diaspore-type bauxite, and the bauxite with an aluminum-silicon ratio of 4 to 6 accounts for more than 60%. The production of alumina mainly adopts the hybrid method, which has high energy consumption and complicated process. In order to reduce alkali consumption, energy consumption and more effective use of bauxite resources, new production processes such as beneficiation Bayer method, lime Bayer method, and series method have been gradually developed and applied. There are some problems in the above-mentioned production process, such as the alumina recovery rate of the beneficiation Bayer method and the lime Bayer method is low; a...

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Problems solved by technology

There are some problems in the above-mentioned production process, such as the alumina recovery rate of the beneficiation Bayer method and the lime Bayer method is low; although the series method can improve the utilization rate of resources, there is still a sintering method, and the energy consumption is still relatively large

Bayer hydration method and hydrothermal method can increase the recovery rate of alumina and reduce alkali consumption and energy consumption. They have great advantages in processing low- and medium-grade bauxite, but there is a high α K Solutions difficult to obtain, high alpha K It is difficult to decompose the solution, or use the method of aluminum precipitation, and there are many problems such as aluminum precipitation slag, which cannot be effectively recycled, so it is difficult to realize industrialization

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