SU1467034A1 - Phosphoric acid concentration and purification process - Google Patents

Abstract

The invention relates to a process for the concentration and purification of impurities of phosphoric acid from impurities and can be used in the preparation of an acid for the production of feed phosphors. The aim of the invention is to reduce the content of fluorine and sulfate ion in the product and reduce the incrustation of equipment. Phosphoric acid is concentrated and purified by evaporation, mixing the initial with the production concentrated acid at a ratio of 1: (0,, 5) streams with the formation of an intermediate concentration of 40-50% P / jO- with the introduction of silicon-containing additives into this acid 0.1-2, D wt.% SiOj. As additives, a mixture consisting of dicalcium silicate, sodium aluminosilicate 1, sodium aluminate and calcium carbonate is used when they are present in the mixture, wt.%: 75-85, 5-t and 10-15, respectively, the duration of interaction acid additives are maintained for 1-15 minutes, the precipitate formed is concentrated and separated. It is advisable to use belite sludge, obtained in the production of alumina from nepheline composition, in wt.%: SiOj, 24-31; CaO 50-58; , 2-5; (Naj, 0) 1-3-, others - up to 100%. Expedient sludge flow 0.32-8, 33% by weight of acid. Concentrated acid (54% PgOy) contains 0.02-0.08% fluorine and 0.02-0.10% SOj. 1 hp f-ly, 2 tab. O) 4: O) 00

Description

1 The invention relates to a method for concentrating and purifying extractive phosphoric acid (EPA) from impurities and can be used in preparing an acid for the production of feed phosphates.

The aim of the invention is to reduce the content of fluorine and sulfate ions.

in the product and reduction of inlay equipment.

PRI me R 1. 450 kg of dihydrate phosphoric acid with a concentration of 23.5% with a content of 2.0% F and 2.1% 50 mixed with 550 kg of concentrated phosphoric acid with a concentration of 54% PjOj with a content of 0.06%

i: And 0.1% SOj (flow ratio, 1: 1.22). | 29.7 kg of a reagent, in which i80% dicalcium silicate, 5% sodium aluminum silicate, 5% aluminate

rub and

CaCOj. The phosphoric acid with the additive is stirred in the reactor and fed to a settling tank to dissolve the liquid and solid phases. The interaction time of the additive and the acid is 5 min. The clarified acid is fed to the concentration in a vacuum evaporation apparatus. Concentration is carried out at a vacuum of 0.85 atm. The solid phase in the composition of the condensed product is sent further by processing. The stripped rbusphoric acid contains 53% ID, 06% F, and 0.2% SO ,. Degree upaken14670344

duct, the other is mixed with uncooked EPA.

Other examples of the implementation of the g method, incl. when the boundary values of the parameters and values outside the specified intervals, are given in table 1. The order and purpose of the operations correspond to those given in examples 10 and 1 and 2. The method involves the introduction of the reagent into one of the streams entering the mixing.

The appropriateness of the selected intervals for changing the parameters of the process 15 and the composition of the additive is due to the following. When the content of dicalcium silicate in the mixture is less than 75%, the purification of the acid from SOj (example 5, Table 1) worsens, when the content of the dicalcium acid from SO, 97%, the degree of deprotection of soro silicate in the additive composition is ,five%. One stripped off phosphoric more than 85% (examples 4,6) is achieved

the acid is divided into two parts; one is used as a finished product; the other is mixed with uncoupled | EPA in a ratio of 1r2. ; According to a known method, the purification and concentration of extraction phosphoric acid containing 29% Pj, 0y, and 2% F is carried out by evaporation of the acid at 40-50% acid in a vacuum evaporator, followed by the addition of SiOj and evaporation in a vacuum evaporator apparatus The evaporated acid contains 55% 0.07% F and 2.8-3.6%

Of; Example2. 446 kg dihydrate

| 4) osphoric acid with a content of 9.6%, 2.1% F, and 2.2% SO, mixed with 554 kg of concentrated acid (52%, 0.07% F, and 0.2% 80) . The resulting mixture was injected with 30 kg of inorganic sludge from the production of glycyrrhea from nepheline, which included 75% dicalcium silicate, 4% sodium aluminosilicate, 2% sodium aluminate and 10% CaCO, and others up to 100%. The phosphoric acid with the additive is mixed for 5 minutes and then separated in the thickener from the solid phase. The clarified acid is fed to the concentration in a vacuum evaporator, where the vacuum is maintained at 0.9 at. The condensed part is processed into fluoride salts. The evaporated phosphoric acid contains 54% 0.05% F and 0.10% 50. The evaporated phosphoric acid is divided into two streams: one is used as a final promax degree of acid purification from sulfate ions, but fluorine deteriorates, and therefore an increase in the proportion of this component of the mixture is impractical. When the content of hydroaluminosilicate in the mixture is less than 1% (Example 9), the degree of purification of the acid from fluorine decreases, while the content of

30 more than 5% (example 10) are contaminated with aluminum impurity and concentrated phosphoric acid and products of its further processing (ammophos, feed phosphates, etc.). When the content of sodium aluminate in the composition of the reagent is less than 1% (Example 13), purification of the acid from fluorine is impaired; with a content of more than 5%, the prepared product is contaminated with aluminum impurity (at 35

40

45

50

5B

measures 14). When the CaCO content in the reagent composition is less than 10% (Example 17), the degree of acid purification from SOj decreases, with a content of more than 15%, the concentration of free CaO in the finished product increases and, as a result, the equipment is incrusted during subsequent evaporation of the acid.

When the ratio of the flows of weak and concentrated acids is less than 1: 2.5, and more than 1: 0.8, the incrustation of evaporators increases with subsequent evaporation of this acid. In addition, in both cases, the removal of sulfate ions is impaired, and when the ratio is more than 1: 0.8, the degree of defluorization is also reduced (examples 19,22).

the degree of purification of the acid from sulfate ions is maximal, but purification from fluorine is worsened; therefore, a further increase in the proportion of this constituent mixture is impractical. When the content of hydroaluminosilicate in the mixture is less than 1% (Example 9), the degree of purification of the acid from fluorine decreases, while the content of

0 more than 5% (Example 10) is contaminated with aluminum impurity and concentrated phosphoric acid and products of its further processing (ammophos, feed phosphates, etc.). When the content of sodium aluminate in the composition of the reagent is less than 1% (Example 13), purification of the acid from fluorine is impaired; with a content of more than 5%, the prepared product is contaminated with aluminum impurity (at 5%).

0

five

0

AT

measures 14). When the CaCO content in the reagent composition is less than 10% (Example 17), the degree of acid purification from SOj decreases, with a content of more than 15%, the concentration of free CaO in the finished product increases and, as a result, the equipment is incrusted during subsequent evaporation of the acid.

When the ratio of the flows of weak and concentrated acids is less than 1: 2.5, and more than 1: 0.8, the incrustation of evaporators increases with subsequent evaporation of this acid. In addition, in both cases, the removal of sulfate ions is impaired, and when the ratio is more than 1: 0.8, the degree of defluorization is also reduced (examples 19,22).

The interaction of the additive with impurities occurs most fully with a duration of 1–15 min. The duration of less than 1 minute is insufficient to complete the interaction, and the degree of purification of the acid from fluorine and sulfate ions is reduced. With a duration of more than 15 minutes, the maximum degree of purification of the acid from impurities is achieved, therefore, the further contact of the additive and the acid is impractical (examples 23,26).

Belite sludge is formed by leaching alumina-containing non-linear-limestone cakes. According to the phase composition, the belite sludge is a mixture of silicates, hydrosilicates, hydroaluminates, carbonates.

From the above examples it can be seen that with the consumption of white mud less than 0.32 wt.% (3.2 kg / ton of acid), deep purification of phosphoric acid from fluorine and sulfate ions is not achieved. Consumption of the additive of 8.33 wt.% (83.3 kg / ton of acid) provides the maximum degree of purification of the acid from impurities and reduction of equipment incrustation, therefore, a further increase in the consumption of the additive is not economically feasible.

Claims (2)

1. A method for the concentration and purification of phosphoric acid, including its mixing with the productional conosilicate. The sludge particles are aggregated with a centered acid to produce sludge; the sludge is characterized by a high dis-acid intermediate concentration 40-50%, evaporating it in the presence of a silicon-containing additive at a flow rate of 0.1-2.0 wt.% SiO, o t -: which, in order to reduce the content of fluorine and sulfate ions in the product ri, reduce equipment incrustation , as an additive, a mixture consisting of 30 of dicalcium silicate, sodium aluminate, sodium aluminosilicate and calcium carbonate with their content in the mixture, wt.%, is used. 75-85, 1.5, 1-5 and 10-15, respectively, ;, the additive is introduced into the mixing stage of the initial and production acid with a ratio of their flows of 1: (O, 8-2.5), persimnost. The chemical composition of belite sludge,%: SiOj 24.0-31.0 CaO 50.0-58.0 Alj, 0, 2,0-5,0 (NaiO + KjO) 1.0-3.0 Others Up to 100 phase composition,%: Dicalcium silicate Calcium Carbonates Sodium aluminate Sodium Aluminosilicate Other The consumption of the silicon-containing additive is 0.1-2.0 wt.%, Which in terms of belite sludge is 0.32-8.33% (or 3.2-83.3 kg per 1 ton of acid). and the base of the consumption of belite sludge is given in table 2. 75-80 12-13 1-2 1-2 To 100 35 40 45 which is carried out for 1-15 minutes, followed by separation of the precipitate, 2. The method according to claim 1, about tl and h a - y y and with the fact that as an additive use belitovy slime obtained in the production of alumina from nepheline. 70346 From the above examples it can be seen that with the consumption of white mud less than 0.32 wt.% (3.2 kg / ton of acid), deep purification of phosphoric acid from fluorine and sulfate ions is not achieved. Consumption of the additive of 8.33 wt.% (83.3 kg / ton of acid) provides the maximum degree of purification of the acid from impurities and reduction of equipment incrustation, therefore, a further increase in the consumption of the additive is not economically feasible. 15 claims 25 30 35 40-50%, evaporating it in the presence of a silicon-containing additive at a flow rate of 0.1-2.0 wt.% SiO, o t -: characterized by the fact that, with the aim of reducing the content of fluorine and sulfate ions in the product ri, reducing the incrustation of equipment , as an additive, a mixture consisting of dicalcium silicate, sodium aluminate, sodium aluminosilicate and calcium carbonate with their content in the mixture, wt.%, is used. 75-85, 1.5, 1-5 and 10-15, respectively, ;, the additive is introduced into the mixing stage of the initial and production acid with a ratio of their flows of 1: (O, 8-2.5), 0 five which is carried out for 1-15 minutes, followed by separation of the precipitate, 2. The method according to claim 1, about tl and h a - y y and with the fact that as an additive use belitovy slime obtained in the production of alumina from nepheline. F four and "0, 08 About TO 0.6 0.07