Calcium-free or low-calcium method for producing aluminum oxide aluminum oxide

Abstract

The invention relates to the technical field of aluminum oxide production, in particular to a calcium-free or low-calcium method for producing aluminum oxide. The calcium-free method for producing aluminum oxide comprises the following steps: mixing a calcium-free dissolution additive and circulating mother liquor, conducting heating to 90-100 DEG C, and preserving heat for 4-6 hours to obtain additive slurry, wherein the calcium-free dissolution additive is composed of iron powder and ether cellulose; mixing the additive slurry with raw ore pulp, and carrying out pre-desiliconization to obtain desiliconized ore pulp, wherein the raw ore pulp is prepared from circulating mother liquor and bauxite, and lime is not added into the raw ore pulp; and adding circulating mother liquor into the desiliconized ore pulp, and then carrying out high-pressure dissolution. According to the above scheme, the calcium-free additive or a small amount of lime is used for promoting the aluminum oxide to be dissolved out of bauxite, so normal high-pressure dissolution of the diasporic bauxite is guaranteed, and meanwhile the harm of the lime in the process of producing the aluminum oxide with the diasporic bauxite as the raw material is avoided or reduced.

Description

technical field [0001] The invention relates to the technical field of alumina production, in particular to a calcium-free or low-calcium production method for alumina. Background technique [0002] The vast majority of China's bauxite is diaspore type bauxite, which has the characteristics of high aluminum and high silicon, and generally contains 2 to 4% titanium minerals. Among them, titanium minerals exist in the form of rutile, anatase and brookite. During the Bayer dissolution process of diaspore bauxite, titanium minerals will significantly reduce the dissolution rate of alumina, and the higher the content of titanium minerals in the ore and the more dispersed, the greater the effect on the dissolution of alumina. big. [0003] At present, in order to eliminate the influence of titanium minerals on the dissolution of alumina, lime is added to the dissolution system. The amount of lime added is usually 10-20% of the bauxite. [0004] Although the addition of lime ca...

AI Technical Summary

Problems solved by technology

[0005] 1. Due to the production of hydrated garnet, the loss of alumina increases

[0006] 2. Under high temperature conditions, there are many side reactions with sodium aluminate solution, and the effective effect of lime is not obvious.

3. Significantly increase the amount of red mud and red mud washing water, the burden of red mud sedimentation and washing will increase, and at the same time, it will cause dilution of various valuable elements in red mud and increase energy consumption in the evaporation process

[0007] 4. The calcined lime inevitably contains calcium carbonate, and anti-causticization occurs during the bauxite dissolution process, which increases the concentration of sodium carbonate in the system, resulting in an increase in evaporation and salt discharge, and an increase in the amount of causticization

[0008] 5. Due to the large amount of lime added and cannot be recycled, the production cost of alumina increases

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