Method for reducing hydrolysis in red mud separation and washing processes

Abstract

The invention relates to a method for hydrolyzing red mud, in particular to a method for reducing hydrolysis in a red mud separation and washing process in a Bayer process aluminum oxide production process. According to the method, dissolved ore pulp is directly injected into a separation tank by a final flash tank through self-pressing, washing water is added into a final washing tank, countercurrent washing is conducted for multiple times, overflow of a primary washing tank and overflow of the separation tank are mixed and then enter a coarse liquid tank, underflow of the separation tank enters the primary washing tank, underflow of each washing tank enters a next-stage washing tank, and red mud is finally discharged from a last-stage washing tank. According to the method, the alkali concentration of the ore pulp entering the separation tank is increased by 15-25g / L, and the degree of supersaturation of aluminum oxide is reduced by 5%-50%; a dilution tank and a dilution rear tank areomitted, the process is simplified, and investment and ore pulp conveying energy consumption are reduced; and the hydrolysis loss of alumina in the red mud separation and washing process is reduced by 50%, and the total recovery rate of the whole plant is improved.

Description

technical field [0001] The invention relates to a method for hydrolyzing red mud, in particular to a method for reducing hydrolysis in the separation and washing process of red mud in the alumina production process by the Bayer method, and belongs to the technical field of alumina production. Background technique [0002] In the process of producing alumina by the Bayer process, after the bauxite is dissolved at high or low temperature, it enters the dilution tank through multi-stage flash evaporation, mixes with red mud 1 washing overflow in the dilution tank, enters the post-diluted tank, and then enters the red Slime separation and washing process. The ore pulp is usually separated by one time and reverse washed for many times. After separation, the overflow is that the crude liquid is sent to the fine filtration process, and the bottom flow of the separation enters the red mud washing system for multiple reverse washing. The washing water is added from the last washing t...

AI Technical Summary

Problems solved by technology

[0003] With the reduction of domestic diaspore reserves and the decline in grade, the use of imported gibbsite to produce alumina is increasing. Generally, low-temperature Bayer method is used. In order to pursue high output rate, the molecular ratio of the dissolved liquid is usually controlled between 1.28 and 1.38. time, but it is prone to hydrolysis reaction in the process of separation and washing of red mud

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