SU67916A1 - The method of producing alumina - Google Patents

Description

In autoclave leaching of diaspore bauxites in the presence of a number of organic substances, such as: mono- and polyhydric alcohols, dibasic acids, hydroxy acids, mono-polysaccharides, urea, pectin, proteins and their decay products, as well as wood, straw and sapropel, extraction alumina is much easier compared to the factory-accepted leaching technique for bauxite with lime additives. The improvement in the leaching process is manifested both in achieving alumina yields up to the theoretically possible, and in that this method extends to difficult leachable bauxites, which, under production conditions, give very poor results.

The positive effect of the above listed organic substances is manifested to the same extent on bauxite of various grain sizes in a fairly wide range.

Organic substances introduced during leaching are largely preserved in circulating alkaline solutions, as a result of which their consumption is negligible.

A particularly effective effect of organic substances on the leaching process is achieved in the presence of some minor amounts of calcium compounds in the pulp, and it doesn’t matter what. Experiments have shown that those amounts of calcium compounds, which are almost always present in bauxite, are quite sufficient to enhance the leaching of the introduced organic impurities.

Very affordable substances that can be successfully applied under industrial conditions are wood and straw.

Sapropel should be especially recommended, because of its cheapness, its prevalence in nature and the combined content in it of both the relevant necessary organic compounds and calcium compounds.

The use of the above organic compounds significantly improves the known method for the production of alumina from bauxite. These improvements are as follows.

1. The yield of alumina from bauxite is increased by 5-8% compared to leaching it in the presence of lime (according to industry method).

2. Mills are accessible for processing difficult leached bauxites, the alumina yields of which reach very high values.

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3. It is possible to leach relatively coarsely ground bauxite. Ch1O, among other advantages, reduces the loss of alumina and alkali as a result of the silica impurity, most often represented by quartz, which is less reactive under these conditions.

4. The leaching time of bauxite is shortened due to improved process kinetics.

D). Created ... lightened conditions for: reach when leaching reduced, caustic relationships (a., 7) in the resulting solutions.

6. There is no need for the consumption of lime, usually added to the pulp during leaching.

Due to the fact that organic additives introduced by leaching instead of lime are preserved in a significant part in the circulating solution, their consumption is very insignificant. They are added only to compensate for the corresponding adsorption and mechanical losses in the process. These additives are estimated to be no more than tenths of a percent of the weight of bauxite.

Subject invention

A method of producing alumina from bauxite, characterized in that during leaching small amounts of organic substances are added to the pulp, such as mono- and polyhydric alcohols, dibasic acids, hydroxy acids, mono- and polysaccharides, urea, pectic substances, protein substances and their decay products, as well as wood, straw and sapropel.