SU72405A1 - The method of separation of potassium sulfate, ammonium and sodium - Google Patents

Description

A method is proposed for the separate isolation of potassium, ammonium and sodium sulphates contained in large quantities in the waste solutions of the production of alumina from alloys using the ammonia method.

By separating potassium, ammonium and sodium sulphates, the following products are obtained:

a) potassium ammonium sulphate - nitrogen-potassium fertilizer, which is a solid solution of potassium and ammonium sulphates;

b) ammonium sulfate;

c) anhydrous sodium sulfate (tennardite).

The proposed method of processing alunite solution consists of the following operations.

1. First evaporation, during which 76% of the water contained in it is evaporated from the alunite solution. After evaporation, potassium ammonium sulphate (a ratio of 1.2 to 1 potassium oxide to nitrogen) crystallizes from the solution, using about 88% of the potassium sulphate contained in the alunite solution.

P p and m S h a and not. An increase in the degree of evaporation leads to a decrease in the ratio of potassium oxide to nitrogen and an increase in the yield of potassium sulphate from nitrogen and nitrogen. y: .obreniel1.

2. The second is residue. The mother liquor after separation of potassium ammonium sulfate by centrifugation (alunite mother liquor) is mixed with a cold and hot mother liquor (see paragraphs 3 and 4 below) and sent to the second residue, as a result of which al monium sulfate crystallizes, and the residue is concentrated to wherein the solution becomes saturated with sodium sulfate.

3. B crystallization of the double salt. The mother liquor after separation of ammonium sulfate is cooled to 30 ° C, and the double salt Na.SO (NN4) 380-4HaO crystallizes from the solution. The solution after separation of the double salt ("cold mother liquor") is napranled to the second residue (see point 2) in a mixture with alunite matochnol.

4. The decomposition of the double salt of Na, S04 (NHJ, SO, i - 4Hg. The double salt is treated with water at a television temperature of about 100 °. At the same time, it

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decomposes into tennardite, precipitated, and ammonium sulfate, which passes into solution.

Tennardite is separated from the solution, and the solution, called the "hot solution, is sent to the second residue, pre-mixed with the alunite solution and the cold mother liquor (see paragraph 2).

From 1 ton of solution you can get:

a) 150 kg of nitrogen-potassium fertilizer containing 64% () 2804 and 29.5%,;

b) 119 kg of ammonium sulfate containing 91.1% (NHJaSO and 5.2%,;

c) 38 kg of tennardite containing 95% NagSOj (calculated on the dry matter).

Subject invention

A method of separating potassium, ammonium and sodium sulphates by evaporation and crystallization, characterized in that the solution of these salts is evaporated before crystallization of the nitrogen-potassium fertilizer with a ratio of 1.2: 1 potassium oxide to nitrogen obtained after filtration; the mother liquor is evaporated before crystallization of ammonium sulfate, after separation of which cooled to 30 ° C and the crystallized double salt Na2S04 (NH4) 2S04 4H20, which is treated with water at 100 ° C, is separated, and the released tennardite is filtered off.