SU1738753A1 - Method of producing phosphoric acid - Google Patents

Abstract

The invention relates to a process for the production of phosphoric acid used in the manufacture of mineral fertilizers. The aim of the invention is to increase the filtration performance and the washing ratio. Phosphoric acid is obtained by treating phosphate raw materials with boric phosphoric and sulfuric acids with the introduction of boron compounds, which take either boric acid, or borax, or calcium borate, or potassium tetrafluoroborate, or potassium tetraborate, or sodium perborate, at a rate of 2- 20 kg B / t P20s in the raw material, followed by crystallization of the precipitate of calcium crystalline hydrates, separation by filtration from the product, washing the precipitate and the direction of wash water to the raw material treatment. The process is carried out at a mass ratio in the liquid phase of the P20s: B pulp, equal to (500-50): 1. These differences can improve filtration performance up to 750-1480 kg / m-h and the coefficient of washing the sediment up to 95.4-99.2%, depending on the type of raw material and the mode of decomposition. 1 hp f-ly, 4 tab. (Ls

Description

The invention relates to a process for the production of phosphoric acid used in the manufacture of mineral fertilizers.

The aim of the invention is to increase the filtration performance and the washing ratio.

Example 1. In the first section of a six-section extractor with a volume of 5000 cm, 300 g / h of apatite concentrate of composition, wt.%, Are fed: P20s39.4; CaO 52.0; R20s 2.3; MgO 0.3; (fcO + Na20) 0.5; F 2.7; Si02 1.0; and about. 1.8, standard dispersion, 6.6 g / h of boric acid (consumption 9.8 kg V / t P20s) and 302.6 g / h of 93% sulfuric acid. Recycled phosphoric acid with a concentration of 22% P20s and circulating pulp are also served here.

In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 20-25 g / l OZ3, in the fourth to sixth sections 25-30 g / l OZ. The decomposition is carried out at a temperature of 78-80 ° C for 5 hours. The circulating pulp is taken from the sixth section. The circulation ratio is 6. The remaining slurry is filtered. The result is 372.1 g / h of production phosphoric acid composition, wt.%: P20s30,85; AOR 2.3; CaO 0.3; Р20з 1.5; F 1.0; At 0.3. The mass ratio of P20s: 102.8: 1.

Phosphogypsum is washed in a countercurrent scheme with water and solutions.

The resulting phosphogypsum has a crystal size of at least 230x120 µm and contains (in terms of dry matter),%:

VJ SA) 00 VJ SP CJ

Pa total 0.75; Rate of 0.25; CaO 39.6; AOR 55.8; RaOa 0.12; In the traces. The filtration capacity is 990 kg / m2 h. The washings with part of the product are directed to the first section.

The decomposition coefficient is 98.5%, the extraction is 98.4%, the washing is 99.1%, the yield is 97.5%.

According to a known method, phosphoric acid is obtained by decomposition of natural phosphate of phosphoric and sulfuric acids with the introduction of inorganic compounds of boron, for example potassium tetrafluoroborate, boric acid, borax, in the amount of 0.0001-0.005% of boron by weight of calcium oxide in the mixture, which corresponds to 0.0001- 0.1 kg of boron per 1 ton of P20s in raw materials.

The pulp is filtered to obtain phosphoric acid, in which the mass ratio of P203: B is (107-104): 1. There is no sediment from such an acid during long-term storage. Phosphogypsum consists of small rhombic crystals with a small number of needle-like crystals. Filtration capacity is 750-1400 kg / m2 -h, the washing ratio is 95.3-98.8%, depending on the type of phosphate raw material and the mode of decomposition.

Example 2. In the first section of a six-section extractor with a volume of 5000 cm3, 200 g / h of phosphorite of composition, wt.%, Are fed: P20s24.5; CaO 38.0; К20з2,1; MDO 3.2; F 2.5; R20 0.5; C02 8.0; and about. 21.2, 2.8 g / h of boric acid (consumption 10 kgV / t P20s) and 150 g / h of 93% sulfuric acid. Recycled phosphoric acid with a concentration of 15% P20s and circulating pulp are also fed here. The decomposition is carried out at a temperature of 78-80 ° C. The total extraction time is 6 hours. As a result, 216.8 g / h of production phosphoric acid composition are obtained,%: P20s 21.2; AOR 2.0; CaO 0.3; MDO 1.9; R2U3 1.5; F 0.9; In 0,2. The mass ratio of P20s: 106,

Calcium sulfate dihydrate crystals have a size of 200x100 microns. The composition of phospho-gypsum (in terms of dry matter),%: P205 total 1.54; P2O5vod. 0.34; CaO 32.5; AOR 46.0. Filtration capacity is 775 kg / m -h. The decomposition coefficient is 96.4%, the extraction is 96.1%, the washing is 97.6%, the yield is 93.8%.

Example 3. In the first section of a six-section extractor with a volume of 5000 cm, 500 g / h of apatite concentrate of standard composition and grinding, 11.26 g / h of boric acid (flow rate 10 kgV / t P20s) and 504 g / h of 93% are fed. sulfuric acid. 35% P20s circulating phosphoric acid and circulating pulp are also served here. In the first to third sections of the extractor, an excess concentration of 0.9-1.5% of the FCO is maintained, and in the fourth to sixth sections, 1.5 to 2.5% of the F30-Decomposition is carried out at a temperature of 94-97 ° C. Total extraction time 2.5 hours

Get 463 g / h of production phosphoric acid having a composition,%: RaOz 41,5; ЗОз2,4; CaO 0.3; F 1,2; Vol. The mass ratio of P20s: B 103,8.

Composition of phosphotoligate,%: Р20 total. 1.20; P205vod. 0.55; CaO 28.5; AOR 40.9; RA0 0.1; F 0.3; KteO 25.2, B - traces. Filtration capacity 1480 kg / mh. Decomposition coefficient 98.9%, recovery 98.7%, washing 99.1%, yield 97.5%.

Example 4. In the first section of a six-section extractor with a volume of 5000 cm3, 500 g / h of phosphorite of the composition,%, are fed: PaOs 24.5; CaO 38.0; Я20з2,1; MDO 3.2; F 2.5; R20 0.5; C02 8.0, n. 21.2,7.0 g / h of boric acid (consumption 10 kgV / t P20s) and 350 g / h of 93% sulfuric acid. This is also supplied with circulating phosphoric acid with a concentration of 22% P20s and circulating pulp. The decomposition is carried out at 97-100 ° C

The total extraction time is 2.5 hours. 383 g / h of production phosphoric acid composition are obtained,%: P20s 29.3 ;. Ao2 2.6; CaO 0.5; F 1,4; At 0.3. The mass ratio of P20s: B 97,7.

The composition of phosphotoligrate,%: P20 total 1.43; P205vod. 0.61; CaO 30.2; AOR 42.0; R20s 0.3; F 0.5; H20 25.27. Filtration capacity 1195 kg / mh. Decomposition coefficient 96.0%, recovery 95.7%, washing 95.8%, yield 91.7%.

Example 5. In the first section of a six-section extractor with a volume of 5 l, 300 g / h of apatite concentrate (the composition is shown in example 1), 5.9 g / h of borax (calculated on N32B40) (consumption 5.66 kgV / t P20s ) and 302.6 g / h, 93% sulfuric acid. Recycled phosphoric acid with a concentration of 22% P20s and circulating pulp are also served here. In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 20-25 g / l F3; in the fourth to sixth sections, 25-30 g / l. The decomposition is carried out at a temperature of 78-80 ° C for 5 hours. The result is 370.1 g / h of production phosphoric acid composition, wt.%: P20s31,1; A 2.5; CaO 0.3; R20s 1.4; F 1,1; At 0.3, the mass ratio of P2U5: B 103.2. The resulting phosphogypsum has a crystal size of 200x100 µm and contains (in terms of dry substance), wt%: P205 tot. 0.88; P205vod. 0.24; CaO 39.3; ZOZ

35.5; H203 0.13; B - traces. The filtration capacity is 960 kg / m2 h. The decomposition coefficient is 98.5%, the recovery is 98.4%, the washing is 98.9%, the yield is 97.3%.

Example 6. In the first section of a six to 5 sectional extractor with a volume of 5 l, 500 g / h of apatite concentrate of standard composition and dispersion are fed. 8.6 g / h of borax (based on N32640) (consumption 5 kg V / t of P20s) and 504 g / h of 93% sulfuric acid. 35% P20B circulating phosphoric acid and circulating pulp are also served here. In the first to third sections of the extractor, an excess concentration of 0.9-1.5% of the F30 is maintained, and in the fourth, the fifth sixth section of the 1.5-2.5% of the F30. The decomposition is carried out at a temperature of 94-97 ° C. Total extraction rate of 2.5 hours. 469 g / h of production phosphoric acid are obtained, having a composition, wt%: P20s41.2; APF 2.2; 20 CaO 0.25; F 1,2; In 0.4. The mass ratio of Р20з: В 103. The composition of phosphopuhydrate, wt%: Р205 total 0.64; Р205вод 0,18; CaO 29.0; APF 2.2; Р20з 0.15; F 0.25; P20 25.2; B - traces. Filtration performance 25 1460 kg / m2 -h. The decomposition coefficient is 98.7%, the extraction is 98.5%, the washing is 99.1, the yield is 97.6%.

Example 7. In the first section of a six-section extractor with a volume of 5000 cm3 30, 300.0 g / h of apatite concentrate (the composition is shown in example 1), 1.8 g / h of CaO-B20z-2H20 (flow rate 2.03 kgV / t P20s) and 297.5 g / h of 93% sulfuric acid. This is also supplied with circulating phosphoric acid with boron 35 of a concentration of 21.20% P20ZIO, 04% B and circulating pulp. In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 30–35 g / l DZO, in the fourth to sixth sections 25–40–30 g / l DZO. The extraction of P20s and B is carried out at a temperature of 78-80 ° C. The result is 381.5 g / h of production phosphoric acid with boron composition, wt.%: P20s 30,15; B 0.06; CaO 0.20; A 2.40; Р20з 1.40; 45 F 1.20. The mass ratio of P20s: B 502.5: 1.

Washed phosphogypsum contains (in terms of dry substance), wt.%: P205 total 0.66; P205 water 0.22; CaO 32.00; FZA 45.10; 50 R20sO, 16; In-traces.

The filtrate after washing phosphogypsum is used as circulating acid.

- Filtration capacity is 55 kg / m2 - h. The decomposition coefficient of apatite concentrate is 98.6; extraction of P20s 98.4%; washing P20s 98.8% ;. yield 97.2%.

Example 8. In the first section of a six-section extractor with a volume of 5000 cm3, 300.0 g / h of apatite concentrate (the composition is shown in example 1), 17.4 g / h of sodium perborate tetrahydrate (calculated as NaBOs) (consumption 19 , 3 kgV / t P20s) and 294.7 g / h of 93% sulfuric acid. Recycled phosphoric acid with a boron concentration of 21.20% P20s and 0.42% B and circulating pulp are served here. In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 30-35 g / l OZO, in the fourth to sixth sections 25-30 g / l OZO. The extraction of P20s and B is carried out at a temperature of 78-80 ° C. The result is 381.5 g / h of production phosphoric acid with boron composition, wt.%: P20s 30,15; B 0.60; CaO 0.35; Go to 2.15; Р20з 1.45; F 1.20. The mass ratio of P20s: B 50.2.

Washed phosphogypsum contains (in terms of dry substance), wt.%: Р20 total 0.70; P205vod. 0.30; CaO 31.90; AOR 44.90; R20sO, 18; In-traces.

The filtrate after washing phosphogypsum is used as circulating acid.

Filtration capacity is 935 kg / m. The decomposition factor of apatite concentrate is 98.5%; removing P20s 98.3%; washing P20s 98.8%; yield 97.1%.

Example 9. In the first section of a six-section extractor with a volume of 5000 cm3, 300.0 g / h of apatite concentrate (the composition is shown in example 1) are fed with 2.0 g / h of potassium tetraborate octahydrate (calculated on foB / iO) (consumption 3.14 kgV / tR203) and 294.7 g / h of 93% sulfuric acid. Recycled phosphoric acid with a boron concentration of 21.20% P20s and 0.07% B and circulating pulp are also supplied here. In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 30-35 g / l OZO, in the fourth to sixth sections 25-30 g / l OZO. The extraction of P20s and B is carried out at a temperature of 78-80 ° C. The result is 381.5 g / h of production phosphoric acid with boron composition, wt.%: P20s30,15; B 0.10; CaO 0.35; A 2.35; R20s 1.45; F 1.10. The mass ratio of P20b: 301: 1.

Washed phosphogypsum contains (in terms of dry substance), wt.%: Р20 total 0,67; Р205вод 0,25; CaO 31.90; AOR 44.90; Я20зО, 13; In-traces.

The filtrate after washing phosphogypsum is used as circulating acid.

Filtration capacity is 935 kg / m2 h. The decomposition coefficient of apatite concentrate is 98.5%;

extraction of P20s 98.4%; washing P20s 98.9%; yield 97.3%.

Example 10. In the first section of a six-section extractor with a volume of 5000 cm3, 300.0 g / h of apatite concentrate (the composition is shown in example 1), 22.8 g / h of NaBF4 (consumption 19 kgV / t P20s) and 294, are fed. 7 g / h 93% sulfuric acid. Recycled phosphoric acid with a boron concentration of 21.20% PaOs and 0.42% B and circulating pulp are also fed here. In the first to third sections of the extractor, the concentration of sulfate ions is maintained at a level of 30-35 g / l OZO, in the fourth to sixth sections 25-30 g / l OZO. Extraction of P20e and B is carried out at a temperature of 78-80 ° C. As a result, 381.5 g / h of production phosphoric acid with a boron composition are obtained, wt.%: PsOb 30.15; B 0.60; CaO 0.35; Go to 2.15; Я20з 1.45; F 1.20. The mass ratio of PaOs: B is 50.2: 1.

Washed phosphogypsum contains (in terms of dry substance), wt.%; P20 total 0.68; Resolution 0.26; CaO 31.90; AOR 44.90; R20sO, 15; In-traces.

The filtrate after washing phosphogypsum is used as circulating acid.

Filtration capacity is 935 kg / m -h. The decomposition coefficient of apatite concentrate is 98.5%; recovery of PaOs 98.3%; washing R20b 98.9%; yield 97.2%.

Tab. 1-4 illustrate the effect of boron consumption and mass ratio in the liquid phase of the P20s: B pulp on process performance.

From the data table. 1-4, it follows that only in the proposed range of consumption of additives for boron compounds the process indicators are the highest.

Claims (1)

1. A method for producing phosphoric acid, which includes processing phosphate raw materials of phosphoric and sulfuric acids, introducing inorganic boron compounds, crystallizing a precipitate of calcium sulfate crystalline hydrates, separating the product from the precipitate by filtration, rinsing it and sending the wash water to be treated as circulating phosphoric acid, that, in order to improve filtration performance and the coefficient of washing the precipitate, either boric acid or borax or calcium borate are taken as boron compounds , or potassium tetrafluoroborate, or potassium tetraborate, or sodium perborate, introduced as 2–20 kg of boron per one ton of phosphorus pentoxide in phosphorus. 2, the way pop. 1, characterized in that the process is carried out at a mass ratio in the liquid phase of the phosphorus pentoxide pulp to boron (500-50): 1. Table 1 Continuation of table 1 Continuation of the blitz 2. 13 1738753 14 Continuation of the table The conditions of the experiments are given in example 3 Table)