SU589902A3 - Method of purifying phosphoric acid - Google Patents

Description

one.

The invention can be used in the process of producing phosphoric acid by the wet method.

A known method of purification of phosphoric acid by extraction from aqueous p, g; solid organic solvents, which are indefinitely miscible with water, The shortcoming of the method is to obtain an extract with a relatively high content of impurities, and this extract requires additional complex purification, after which it is distilled again separated into phosphoric acid and solvent.

Closest to the inventive method proposed is the purification of phosphoric acid by extracting it from an aqueous solution using an organic solvent that is not miscible or partially miscible with water and has a boiling point higher than the boiling point of water or azeotropic mixture at an acid-extractant ratio of 1: 8, with the subsequent separation of the organic phase and the release of phosphoric acid from it 2j.

The disadvantage of this method is 6ont shoy. The number of extraction steps (up to 1O), while the extract contains water in significant amounts of biibix, which increases the solubility of the impurities and the transition into the extractable part. To remove these impurities from the extract, a large excess of anhydrous solvent is required, the introduction of special additives or additional azeotropic distillation of special additives or additional azeotropic distillation of the separated extract. The degree of purity achieved is (in terms of) wt.%: Fe O, OO6, AB O, OO1b, Ca 0, OO44, Mg0, 0037, V O, O004, Mri 0.0002, F 0.15, - SiO 0.15, SO 0.5.

The purpose of the invention is to simplify the method, i.e. reducing the number of extraction steps, and increasing the degree of purification of the product. .

For this, according to the method of preference, phosphoric acid is mixed with the solvent in a volume ratio of 1: O, 3-1: DA, mostly 1: 1-1: 4, and the mixture is heated to a temperature tshzhe than the point

solvent, and higher than the boiling point of water or an aerootrope, until the water is completely removed,

P-butanol, P-amyl alcohol, ethylhexanol, dibutyl ether, methyl ethyl isobutyl ketone, butylacetate, tributyl phosphate, tridocecylamine,

The extraction process allows the extraction of the aqueous phosphoric acid in one stage, and the anhydrous cancer extracts that are formed are very easily separated from the impurities, which are released in solid form, which allows, in combination with the subsequent washing and distilling of the solvent from the extract, to obtain phosphoric acid. high purity acid.

Example Made from phosphate from Morocco, after dissolving cheese with sulfuric acid, phosphoric acid contains, after gypsum separation, 28.5% PjOy and the following Mesi (in terms of P, Og) wt%: Fe, Le 0.57, Ca 0, 17 / Mgr- 0.6, SiQ O, i5, V 0, O61, Mn O, OO8, As O, OO25, F 3.85, SO 5.0,

28 kg / h of this sour g and 2 kg / h of rb G25 of the zirculated washing raffinate are mixed with the addition of O, O8 kg / h of active carbon, O, 434, kg / h of 50% sodium hydroxide and 0.05 p / h approximately 2O% woro sodium sulphide solution at i 130 - th

135 ° C

with 39 kg / h of water-saturated alcohols from oxosynthesis with vigorous stirring and with the reflux of alcohol, in accordance

with a volume ratio of phosphoric acid to alcohol 1: 2. In this case, 1 20 kg / h of water with approximately 1% alcohol is distilled from the system1. The mixture of anhydrous alcoholic solution of phosphoric acid and a solid fine-grained refiner is separated in this operation, 2.2 kg / h of sediment are removed, 47.4 kg of crude alcohol extracts are washed with 4.8 kg / h of distilled water in a battery of 8 mixing clarifiers, and 5O, 2 kg / h of high purity extract and 2 kg / h are obtained raffinate wash. The latter is sent back to the reactor, and the extract is fed to the re-extraction of 15; 2 kg / h of distilled water in a column with rotating disks and with 8 theoretical plates. In this case, 26.7 kg / h (, 29%) of pure phosphoric acid and 39.7 kg / h of water-saturated alcohol, which, together with .3 kg / h of the residual alcohol distilled from pure acid, are recycled, are obtained. phosphoric acid absorption. The loss is 3%. The achieved purity of the purified phosphoric acid is (in terms of ria Pj Oj), weight,%: Fe O, PO15, AE O, OO, Ca 0, OO20, Mg0, 0005, V 0.0005 Mn O, 0001, As 0.0001, F 0.0100, SiOjj 0.0100, 50 O, 0500.

The results of applying various solutions: ritepei are given in the table.

2: 1P -butanol

2: 1.P-amyl

1: 1P - amyl alcohol

1: 2P - amyl alcohol

2: 1 ethylhexanol

2: 1 butyl ether

2: 1methylisobutyl ketone

2: 1 butylacetate

2: 1tributyl phosphate

Claims (2)

5: 1 tridodecylamine Claim 1, a method for purifying a phosphoric acid by extracting a grave solution with an organic solution that is not miscible or partially miscible with water with a boiling point higher than the boiling point of a question Or azeotropic mixture, followed by separation of the organic phase and separation from it phosphoric acid, characterized in that, with a chain of simplifying the process and increasing the degree of purification, phosphoric acid is mixed with a solvent in a volume ratio of 1: 0.3-1.30, preferably 1: 1-1: 4, and the mixture is heated to a temperature lower than the boiling point of the rasporitel, and Sh.ppo, just boiling water or azeotrope, and removing water, 2. The method according to claim 1, that is, With hw; the solvent uses p-butyl, p-mil alcohol, ethylhexanol, d-butyl simple ef, methyl isobutyl ketone, butyl petroleum, tr f butyl phosphate, trido Deiylnn. Sources of information received in the workshop during the examination: 1; UK patent K 1 (.2ОО71, class C1A, 16.02.66. 2. Patent of Great Britain No. 1210 46, kp. S1L, 10.28.7O,