SU769916A1 - Phosphoric acid production process - Google Patents

Description

(54) METHOD FOR PRODUCING PHOSPHORIC ACID

one

The invention relates to the field of extraction phosphoric acid used for the production of fertilizers.

The method of acid decomposition is known, in which, in order to prevent foaming, decomposition is carried out in the presence of sodium, potassium, or ag 1 monium salt of bis- (2-ethylhexyl) phosphira sulphate 1.

The disadvantage of this method is foaming of the solution in the extractor-filter system even with residual concentrations of surfactants in the solution less than 0.0005% and equipment corrosion.

There is also known a method for producing phosphoric acid by decomposing a phosphate raw material with a mixture of sulfuric and circulating phosphoric acid, filtering the pulp, repulping and washing the precipitate of calcium sulfate hemihydrate in the presence of alkali salts: 1 higher fatty acids 2.

The disadvantages of the method are the low degree of precipitation of calcium sulfate precipitate - the content in the washed phosphogypsum is not less than 1.1%, but also significant.

water consumption required for Eki Osashka.

The aim of the invention is to increase the degree of washing and improve the physical and mechanical properties of the sediment.

To do this, phosphate raw materials are decomposed with a mixture of sulfuric and circulating phosphoric acids, introduced into the resulting phosphogypsum suspension a mixture of alkaline salts of higher fatty acids with water-soluble non-ionic high molecular compounds of vinyl alcohol or its derivatives, administered in O, 0005-0.001%,

15 divide the suspension and wash the precipitate.

It is advisable to use poly20 vinyl alcohol as water-soluble non-ionic high-molecular compounds of vinyl alcohol or its derivatives, and alkaline salts of higher fatty acids in an amount of 0.005-0.05% by weight of the phosphogypsum suspension.

The proposed method makes it possible to increase the degree of washing by 25; the coefficient of washing increases by 0.8-1% and reduce the number of washes to two. In addition, when using it, the degree of utilization of the raw material is increased.

30 by reducing losses from

phosphogypsum to 0.4-0.5%, as well as the moisture content of the sediment, 5%.

This improves the mechanical and mechanical properties of the sediment, since the phosphogypsum sediment is obtained crumbly.

The acid output is increased by 30%.

Alkaline salts of higher fatty acids are taken in an amount of 0.005-0.05%, since a smaller amount does not provide complete hydrophobization and does not allow achieving a high degree of washing, and a large one can cause a solubilization effect, which will entail an increase in the moisture content of the precipitate.

Example. A phosphogypsum suspension, obtained under programed conditions in the dihydrate mode during the decomposition of apatite with a mixture of sulfuric and phosphoric acids, is taken at the outlet of the extractor and in an amount of 135150 cm at T: W 1: 2.3 is placed in an apparatus with a stirrer, where served a pre-prepared mixture of aqueous solutions of PCT RSFSR liquid technical soap (the sodium salt of higher fatty acids containing Q6 and polyvinyl alcohol with a concentration of 5% and 0.1%, respectively, in an amount of 5.4 ml. At that, the concentration of liquid technical in phospho the gypsum slurry was 0.01%, and the polyvinyl alcohol was 0.0007% by weight of the phosphogypsum slurry.

The suspension is stirred for 1-5 minutes and fed to a laboratory thermostated vacuum filter. The pressure difference during separation was 0.5-0.6 atm. Use the bedrock fabric art. 931506. The precipitate obtained on the filter is washed with hot water using a three-stage washing scheme. Process indicators were as follows: removal of dry Q sediment - 1050 kg / mh, content

 in phosphogypsum at the filtration stage, 16, 3%, after the third 0, 51%, the washing ratio at the indicated stages: 27.7%, 64.9%, 98.44%, 99.7%. Sediment humidity 38.2%.

The experiments were carried out in the same way as the described example, changing the concentration of the used PCT RSFSR 390-73 (1) and polyvinyl alcohol U in the phosphogypsum suspension in the range from 0.005% (.1), 0.0004% to 0, 05% (1), 0.0012%.

5 To compare the known and proposed methods, experiments were carried out to obtain phosphoric acid (in the dihydrate mode; without the addition of any substances, with the addition of alkali salts of higher fatty acids

concentration of 0.01% by weight of the suspension.

Indicators for phosphogypsum removal, its moisture content and washing are shown in the table.

(N N

D ID

n M

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with

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H

1L

1L

about

P

SP

1P

sh

VO

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Claims (2)

P5 77 Claim 1. A method of producing phosphoric acid, which includes decomposing phosphate feedstock with a mixture of sulfuric and circulating phosphoric acids, introducing into the formed, phosphopype suspension of alkaline salts of higher fatty acids, separating the suspension and washing the precipitate, characterized in that In order to increase the degree of precipitation of the precipitate and increase the yield of the product, alkaline salts of higher fatty acids are taken in a mixture with water-soluble non-ionic high-molecular compounds of vinyl alcohol or its derivatives introduced into lichestve 0,0005-0,001% by weight fosfogit owl suspension. 99168 2. A method of pop 1, characterized in that polyvinyl alcohol is taken as a volatile-soluble non-ionic high-molecular compound of vinyl alcohol or its derivatives. 3 The method according to claim 1, I distinguish that with the fact that alkaline salts of higher liquid acids take in an amount of 0.005-0.05% by weight of phosphohyp10 owl suspension. Sources of information taken into account during the examination 1 USSR Author's Certificate 5 509566 , cl. C 05 V 11/04, 12/24/73. 2. USSR author's certificate 245039. cl. C 01 B 25/22, 04.16.68.