SU882921A1 - Method of phosphoric acid production - Google Patents

Description

(54) METHOD FOR OBTAINING PHOSPHORIC ACID

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This invention relates to a process for producing phosphoric acid that is processed into fertilizers and technical phosphates.

A known method of producing phosphoric acid by treating phosphate raw materials with recycled phosphoric and sulfuric acids with the introduction of a 0.05-1.0% solution of polyacrylamide during the decomposition of the raw material or before filtering the pulp, followed by separating the product from the calcium sulfate dihydrate precipitate and washing it with water. Phosphoric acid is obtained, containing 30% of the consumption of polyacrylamide is more than 60 g / t of raw material and the specific filtration capacity is 210220 h.

The disadvantages of this method are the increased consumption of polyacrylamide and the relatively low filtration performance.

A known method of producing phosphoric acid by treating phosphate raw materials with circulating phosphoric and sulfuric acids to produce pulp containing 30-120 g / l of sulfate ions, introducing an additional amount of raw material to reduce the concentration of sulfate ions to 10-30 g / l, followed by separation by filtration product from the precipitate of calcium sulfate dihydrate and washing it with water. Phosphoric acid is obtained with a concentration of 33%, after washing it contains less than 0.3% (2.

The disadvantages of the known method are relatively high 10 tertry precipitates, and a relatively low product yield when using poor phosphate raw materials, the decomposition coefficient is 94.1797, 96.

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The purpose of the invention is to reduce losses with washed precipitate by increasing the washing ratio.

The goal is achieved by the fact that according to the method, which involves 20 seconds in the processing of phosphate raw materials with circulating phosphoric and sulfuric acids, the desulfurization of the pulp by introducing an additional amount of raw material, separating the product from the filtration

25 sulphate of calcium sulfate dihydrate and washing it with water, desalting is carried out in the presence of an aqueous solution of polyacrylamide.

Moreover, polyacrylamide is taken in the amount of 30-80 g / t of raw material.

It is advisable to use ammonia polyacrylamide grade A, containing 4-8% of the basic substance and not more than 13% ammonium sulfate.

Example 1. In the first section of a two-section extractor with a volume of 900 m, 28.2 g / c of the head of Karatau (contains, wt.%: 24.6; CaO 40.7; MgO 1.9; SOL 6 and the insoluble residue 19.1%) and 20.8 t / h of 93% sulfuric acid. This is also supplied with circulating phosphoric acid (15.1% P.2.5 circulating pulp. The raw material is decomposed at 75-78 ° C. The resulting pulp contains calcium sulfate dihydrate and in the liquid part the sulfate ion concentration is 3048 g / l. This pulp flows in the second section of the extractor, where 8 t / h of fosmuki and and, 2% polyacrylamide solution with a consumption of 30 g / t of additional quantity of fosmuk are supplied.

The result is a pulp containing in the liquid portion 18-25 g / l of sulphate ions and dislocated calcium sulphate dihydrate. Pulp; Partially served by filtering. The phosphoric acid obtained contains 20% PO-J — calcium sulfate dihydrate is washed on the filter with water, the flow rate of which is 52.3. Filtration and washing result in decomposition coefficients of .96.55, washing of 96.45 and yield 93, 14.

Example2. 28, phosphomus (Example I) j20y7 t / h of 93% sulfuric acid, circulating pulp and phosphoric Kylot (15.1%) are fed to the first section of the two-section extractor. As a result of processing the raw material, dihydrate pulp is obtained, in the liquid part of which the concentration of sulfate ion is 30-48 g / l. This pulp flows into the second section of the extractor, where

8 t / h of Fosmuki and 0.2% polyacrylamide solution are used at the rate of 80 g of 100% polyacrylamide per 1 ton to an additional amount of fosmuk. As a result, the concentration of sulfate ion in the liquid part of the pulp is reduced to 18-25 g / l. A portion of the resulting pulp was filtered, yielding phosphoric acid 20% PnO. Calcium sulfate dihydrate is washed on the filter with water supplied in the amount of 56.5 mc. The decomposition coefficient is 97.24, the washings are 98.4i and the yield is 95.84.

The proposed method allows to increase the decomposition coefficient to 97.81, the washing ratio to 99.01, the yield coefficient to 97.04, and also to reduce the loss of the washed sediment by 1.6%.

Claims (2)

Invention Formula 1, The method of obtaining phosphoric acid nj / phosphate raw materials processing by circulating phosphoric and sulfuric acids, followed by desulfurizing the slurry with an additional amount of raw material, separating the product from sulphate dihydrate sludge before washing it with water, characterized by coefficient Sediment washout. desalting lead in the presence of an aqueous solution polyacrylamide., 2, the method according to p. 1, about tl and h ayusch and and with tizh, h; then polyacrylamide is taken in the case of 30-80 g / t of raw material ,, Information sources . into account in the examination 1, Patent of Great Britain No. 1367004, CLS, C 1 A, - 1974s 2.Patent Giia number 3155539 ,, class. 423-320. ; .73;