SU132622A1 - The method of preparation of active alumina - Google Patents

Description

Methods are known for producing active oxide from bauxite by calcining with soda or by treating with a strong solution of sodium hydroxide.

The proposed method for the preparation of active alumina by carbonization with carbon dioxide at a constant optimum pH of the environment of a desalinated solution of sodium aluminate makes it possible to obtain active alumina directly in alumina factories that prepare aluminate solutions from natural bauxite.

As a result of this measure, reagent costs for re-precipitating aluminum hydroxide are eliminated, raw material costs and other operating costs are reduced, due to a shorter production cycle.

To carry out the proposed method of producing active alumina by carbonizing a solution of sodium aluminate, a carbonation reactor is used, in which, with a small amount of water, a solution of sodium aluminate and carbon dioxide is fed. At the same time, the pulp pH is maintained at a predetermined level (pH 8-10), which is achieved by automatically regulating the supply of reagents to the reactor.

After precipitation, the aluminum hydroxide slurry A1 (OH) 3, in the form of a gelatinous mass, enters the washer to wash the precipitate from soluble impurities, consisting mainly of NagCOs (soda). In order to better remove sodium ions, washing is carried out with ammonia water having a pH of about 9, the mother liquor and the washing waters where soda is contained are returned to the process to prepare new portions of the aluminate solution.

No. 132622-2. The washed and pressed aluminum hydroxide precipitate is further processed by conventional molding and heat treatment methods to produce active alumina (A 12 O 3).

The alumina contamination obtained by the proposed method from the desilicatised aluminate solutions of alumina refineries does not exceed the corresponding impurity of HOCO obtained by re-precipitation, namely: the SiOa content does not exceed 0.3%, ReaOz is not more than 0.05% and - 0, 01%.

Subject invention

A method of preparing active alumina by carbonizing a solution of sodium aluminate, characterized in that, in order to eliminate the re-precipitation step, aluminum hydroxide is precipitated from a desilicated aluminate solution of alumina production by carbonizing the solution at a constant pH within 8-10, the precipitate is then washed away from ammonia soda water at pH 9.