SU31425A1 - Method for processing ash of coal near Moscow in order to extract aluminum from it - Google Patents

Description

The processing of aluminum silicates involves the use of prebaked clay and related materials at a temperature not higher than 800 °. It is believed that this operation causes a change in the kaolin core clay to form easily soluble forms of alumina. In the case of a transition beyond 800, the compound of free silica and alumina is reacted to form a difficultly soluble silicate, such as silimanite, compounds characteristic of chamotte.

Coal ash Moscow essentially. The clay is clay with a very high content of alumina, reaching up to 38%, but the high temperature of the furnaces transforms it into a species very close to chamotte. Therefore, when extracting alumina from the ash, it is not possible to focus on conventional acidic methods; Thus, in the case of the use of sulfuric acid, the percentage of extraction of alumina from ash does not exceed 10%. The proposed method for processing the ash of coal located near Moscow for the purpose of extracting aluminum from it is based on the already known production of aluminum sulfate by reacting ammonium sulfate with a compound containing aluminum oxide when heated

above 350 °, as well as the known calcination of a mixture of ammonium fluoride with an aluminum compound. The use of these salts results in a combined effect on the silicate of sulfuric anhydrite, which is formed from the thermal dissociation of fluorine ammonium, which promotes the decomposition of the kaolin core.

The occurrence of the reaction can be depicted as follows:

A120З231О2 + 2SiF4 + SNHs +

-f4H201

or

A120З25Уз 12NH4F 2 (NH4) .S iPg + + 8ЫНз -j- 4НзО

A12Oz -3 (LH4) 25O4 A12 (504) g + bNNz + + NH3 + H2O.

Thus, when calcining prp 450-550, aluminum sulphate with a low iron content and ammonium silicofluoride are obtained, which, if absorbed together with the evolving ammonia, gives ammonium fluoride and silica gel.

(NH4) 2SiF64-4NH4OH Si (OH) 4+ 6NH4F

The course of the process is as follows: 1 wt. part of the bait is mixed with IJ weight. parts ammonium sulfate and 1 wt. part of the fluorine ammonium. The mixture placed in is calcined at the indicated temperature. Ammonium silicofluoride emitted and ammonia are absorbed by water. After calcination, the extracted from the crucible is dissolved in water, yielding up to 90% of the alumina recovery from the theoretical. The iron content in the resulting aluminum sulfate5 is not higher than 1%, despite the very high iron content in the starting product. .

I As stated above, ammonium silicate emitted with ammonia gives silica and fluorine ammonium. After filtration, the ammonium fluorine is returned to the process.

Fluorine-ammonium acts as a factor contributing to high yields of aluminum. So, in one of the experiments 50 g of jug mixed with 75 g

ammonium sulfate gave an alumina yield of 33.9% from iron contamination not

above l / o,

Subject patent.

Claims (2)

l.jCnoco6 processing of the ash of coal located near Moscow in order to extract aluminum from it, characterized in that ammonium sulfate and ammonium fluoride are ash in the ash and the mixture is calcined at temperatures above 400 ° to form aluminum sulfate. 2. Acceptance of the method according to claim 1, characterized in that the gases released from the furnace are carried out through the water in the absorption of fluoride ammonia to form ammonium fluoride and silica, the first of which is used to treat the ash batch.