RU2315709C1 - Method of production of purified phosphoric acid - Google Patents

Abstract

FIELD: production of purified phosphoric acid for food-processing industry and production of fertilizers : ammonium sulfate phosphate and commercial strontium or barium sulfates.

SUBSTANCE: proposed method of production of purified phosphoric acid at simultaneous production of ammonium sulfate phosphate and commercial strontium and barium sulfates; fertilizing ammonium sulfates are mixed with water and pulp is divided into ammonium phosphate solution and insoluble residue; ammonium phosphate solution is treated with cation in H⁺ form till complete absorption of ammonium ions from it, thus obtaining phosphoric acid and cationite in NH₄ ⁺ form; strontium or barium sulfates are settled from acid by their carbonates and are separated from liquid phase in form of commercial product; cationite in NH⁺ ₄ form is subjected to desorption by sulfuric acid solution, thus obtaining ammonium sulfate solution which is mixed with insoluble residue; pulp thus obtained is evaporated, granulated and dried. Fertilizing ammonium sulfate is mixed with water at solid-to-liquid ratio = 1 : (1-3). Phosphoric acid is evaporated to concentration of 73-85% of H₃PO₄ and is withdrawn from the process in form of finished product.

EFFECT: enhanced efficiency; high purity of acid.

4 cl, 6 tbl

Description

The invention relates to the production of purified phosphoric acid, characterized by a high degree of purity, which can be used in the food industry and allows you to simultaneously obtain fertilizers - sulfoammophos and marketable strontium sulfate or barium sulfate.

Strontium sulfate is the main source of strontium metal and its salts used in pyrotechnics, chemical, ceramic and glass industries.

Barium sulfate - significantly absorbs x-rays and gamma rays. This property is widely used in medicine for the diagnosis of gastrointestinal diseases; used in construction, paper, paint and varnish and other industries.

Various methods are known for purifying extraction phosphoric acid (EPA) in various ways.

In copyright certificate No. 850577, cl. СВВ 25/234, 1981 describes a method for purifying extraction phosphoric acid by sequentially treating it with alkaline compounds (for example, sodium hydroxide, active silicic acid, and isopropyl alcohol). The result is phosphoric acid (FC) containing 49% P ₂ O ₅ and 0.014% fluorine. The resulting acid cannot be classified as food grade acid. During its treatment with sodium hydroxide, partial neutralization of phosphoric acid to a content of 5.95% Na ₂ O, i.e. equivalent to this content, the concentration of hydrogen ions in phosphoric acid decreases; in addition, the solubility of isopropyl alcohol in phosphoric acid is high enough and distillation distillation is proposed for its separation. The technology presented is very complex and expensive.

SU patent No. 1088658, cl. СВВ 25/46, 1984, a method for the purification of phosphoric acid (47.5% P ₂ O ₅ ) obtained by the sulfuric acid decomposition of Moroccan phosphorite, including treatment of the acid to remove sulfate ions with barium compounds, for example, barium carbonate, at a flow rate of 3, is protected , 85% of the content of P ₂ O ₅ in the acid, and the direction of the resulting suspension for extraction with water-saturated P-amyl alcohol, which is dispersed in the mixing zone into the aqueous phase, in an 8-stage extractor with the introduction of concentrated sulfuric acid in an amount of 2 to the 7th stage of extraction -20 wt.% From ositelno content of phosphorus pentoxide in phosphoric acid, washing of the extract and the aqueous re-extraction.

According to the authors of the proposed method, their invention can be used in the chemical-pharmaceutical and food industries.

However, this statement does not follow from the application materials. Indeed, the content of sulfate ion in EPA at a barium sulfate flow rate of 3.85% of% P ₂ O ₅ is 9 × 10 ^-4 %, which corresponds to the content of this component in food acid. But then sulfate ions are again introduced into the extraction stage in the form of concentrated sulfuric acid in order to increase the degree of P ₂ O ₅ extraction into the organic phase, while they are partially extracted with P-amyl alcohol, therefore, in the best mode, the content of sulfate ion in purified acid is 0.1%, which is significantly higher than required.

In addition, the content of other impurities in the FC is unknown from the application materials. However, given that the initial product for the production of FC is Moroccan phosphorite, in which the impurity content is much higher than in the Kola Apatite concentrate, it is clear to specialists in this field that carrying out only preliminary desulphurization and acidification of the organic phase at the stage of extraction with sulfuric acid does not allow purification of Moroccan EPA from other impurities.

In the patent of the Russian Federation of the company "Kemira Chemical OY" No. 2226499, cl. СВВ 25/234, a method for producing food-grade phosphoric acid by crystallization of phosphoric acid hemihydrate from previously purified raw acid is protected.

Obtaining food acid involves crystallization of phosphoric acid hemihydrate from the initial phosphoric acid having a concentration of P ₂ O _{5 of} more than 58%, a concentration of magnesium ions of less than 1.5%, a concentration of sulfate ions of less than 1%, a concentration of fluorine ions of less than 0.2% at a speed crystal growth of at least 10 μm / min, with a temperature difference during the first crystallization of less than 17 ° C; crystalline phosphoric acid is diluted to a concentration of 63% P ₂ O ₅ , germ crystals are added and re-crystallization is carried out at a temperature difference between the temperature of the crystal suspension and the temperature of the cooler less than 8 ° C.

The initial phosphoric acid is pre-purified by: a) a foam flotation step of the phosphate concentrate and directing it to the intensive magnetic separation step to reduce the amount of magnesium ions; b) leaching the formed phosphate concentrate (item a) in a mixture of sulfuric and phosphoric acids, precipitating sulfate ions and arsenic ions, removing them from the reaction mass and adding silicon ions to bring the molar ratio F / Si to less than 6; c) concentration of phosphoric acid (item b), removal of the solid residue and evaporation of fluoride ions.

As follows from the foregoing, all of the above operations are necessary to obtain phosphoric acid in feed or food condition.

Analysis of the known method (examples 1-7, tables 1-6) allows us to conclude that the direct yield of phosphoric acid from an acid obtained by the wet method containing 58.5% P ₂ O ₅ , 0.15% fluorine, in food grade phosphoric acid does not exceed 30% (example 4), 25% (example 5); 31% (example 6) and 55% (example 7), but this example deviates from optimal conditions in relation to pre-treatment and other stages and does not allow to obtain FC food condition. The low recovery of P ₂ O ₅ in the target product is also confirmed by the fact that in the process of utilization, along with food acid, phosphoric acid of feed quality and a number of wastes containing gypsum, insoluble impurities, H ₂ SiF ₆ and products remaining from the deposition of arsenic and fluorine (figure 1), as well as phosphoric acid of quality suitable for the production of fertilizers (figure 2).

The calculations show that the cost of phosphoric acid obtained according to the patent is higher than the cost of thermal phosphoric acid and much higher than the cost of acid obtained by the proposed method. In addition, there are doubts about their practical implementation.

The most widespread methods of purification of phosphoric acid by extraction of impurities with tributyl phosphate. So, for example, the patent SU No. 1438607, Cl. СВВ 25/234, 1988. The method includes preliminary purification by liquid extraction of most impurities and subsequent purification of impurities of fluorine and organic compounds (most likely of dissolved extractant, in particular TBP) by heating the FC before cleaning to 130-175 ° C and processing steam at a pressure of 2-6 bar in the presence of hydrogen peroxide.

The inventive method allows to achieve the purification of FC from fluorine and organic compounds to food condition, but its content of sulfate ion, iron and aluminum ions does not meet the requirements of GOST for food grade FC, which follows from the capabilities of those reagents that are used for purification: steam and hydrogen peroxide. In addition, heating the FC to high temperatures (130-175 ° C) and processing with high pressure steam require significant energy costs, which reduces the technical and economic performance of the method.

This direction has been especially developing in recent years. Methods protected by patents No. 2075436, С01В 25/46, 1994; No. 2109681, СВВ 25/234, 1994; No. 2149830, СВВ 25/46, 1999; No. 2174491, СВВ 25/46, 2000; No. 2191745, СВВ 25/46, 2001; No. 2205789, СВВ 25/46, 2002; No. 2219125, СВВ 25/46, 2002; No. 2214361, СВВ 25/234, 2002; No. 2275329, СВВ 25/46, 2004, offer various technological methods for improving the purification of phosphoric acid, but none of them can be used to obtain a low content of all types of impurities.

In addition, the regenerated extracting tributyl phosphate regularly needs to be replaced with a new one and there is always the possibility that the remainder of the reagent will remain in the product.

The objective of the present invention is to provide a method for producing purified phosphoric acid while producing fertilizer - sulfoammophos and marketable strontium or barium sulfates, which allows not only to obtain acid (food) with a minimum amount of all impurities, but also to greatly simplify the processes of separation of impurities.

This problem was solved by creating a new type of method, characterized in that ammonium fertilizer is mixed with water, the pulp is separated into an ammonium phosphate solution (AMPF) and an insoluble residue, AMPF is treated with cation exchange resin in the H ⁺ form until ammonium ions are completely absorbed from it to produce phosphoric acid and a cation exchanger in NH ₄ ⁺ form, from the acid precipitated strontium sulfates or barium salts of carbonic acid, they are separated from the liquid phase in the form of commercial products, and the cation exchange resin in NH ₄ ⁺ -form is stripped with sulfuric sour s to obtain an ammonium sulfate solution which is mixed with the insoluble residue, and the resulting pulp was evaporated, granulated and dried. Mixing fertilizer ammonium phosphates with water is carried out at T: W = 1: (1-3). The resulting phosphoric acid is concentrated, if necessary to a concentration of 73-85% H ₃ PO _4. It is advisable to separate the pulp of fertilizer ammonium phosphates by centrifugation, and the separation of phosphoric acid from strontium or barium sulfates should be carried out either by filtration or centrifugation.

Fundamentally new in the proposed method is the use as a starting component of non-technical phosphoric acid, fertilizer ammonium phosphates (for example, ammophos, diammophos). The fertilizer is pre-mixed with water at a certain T: W.

These fertilizers, naturally, contain impurities of elements such as Fe, Al, REE, Ca, F, Pb, Hg, As, Cd, which pass into it from technical extraction phosphoric acid.

In the fertilizer, nitrogen is in ammonia form in the form of mono- and diammonium phosphates and ammonium sulfate, and the rest of the composition is characterized by the presence of water, insoluble phosphates Fe, Al, REE, calcium, calcium fluoride, silicon dioxide and other impurity elements. When mono- and diammonium phosphates are dissolved in water, ammonium sulfate passes into the liquid phase (in this case, the pulp pH is 4.2–4.4 when ammophos dissolves and 6.2–6.6 - when diammophos dissolves), and the remaining elements go into insoluble residue, which is quite simply separated by centrifugation from ammonium phosphate AMPF.

When mixing fertilizer with water, the ratio of solid to liquid phases is taken strictly defined, which is explained as follows.

With a decrease in the initial ratio of solid and liquid phases when mixing fertilizer ammonium phosphates with water below 1.0, for example, at T: G equal to 0.8, a supersaturated solution of monoammonium phosphate (diammonium phosphate) is formed, which is a water-soluble part of the fertilizer, as a result of which part of the phosphorus equal to 10-15% of the total content in the fertilizer does not go into the liquid phase and remains with an insoluble residue, while the extraction of P ₂ O ₅ in AMPF is 67-72%.

With an increase in the initial ratio of solid and liquid phases when mixing fertilizer ammonium phosphates with water above 3.0, for example, at T: Ж equal to 3.2, a significant dilution of AMFR occurs: for example, the concentration of P ₂ O ₅ in it after separation of the insoluble residue is 11.4%. This leads to the fact that the volume of the phosphoric acid solution formed after sorption increases and, accordingly, the energy costs increase upon evaporation of phosphoric acid to a concentration of 73% and 85% H ₃ PO ₄ .

Next, AMFR is treated with cation exchange resin in the H ⁺ form. Strongly acidic cation exchangers manufactured by the industry can be used as cation exchangers: KU - 2 × 8, KU-2g, KU-22, containing the sulfo group SO ₃ Н ⁺ , which during sorption exchanges hydrogen ions for an equivalent amount of ammonium ions in the AMPF. Complete absorption of ammonium ions is achieved by the corresponding amount of cation exchanger depending on the amount of AMPF. As a result, phosphoric acid is completely purified from the above impurities. However, it contains sulfate ions, which are removed from the obtained acid by adding carbon dioxide salts of strontium or barium; the strontium or barium sulfates formed in this case have a crystalline structure, they are separated from the liquid phase by filtration or centrifugation.

After the separation of sulfates, phosphoric acid has a concentration of 20-25% H ₃ PO ₄ and therefore the method involves evaporation of it to the required concentration, namely 73-85% H ₃ PO ₄ (commercial products). However, if further phosphoric acid is used to produce dietary phosphates, then its evaporation is not necessary.

Cation exchange resin after sorption contains ammonium ions and a small amount of impurities. This is due to the fact that, when the fertilizer is dissolved in water, part of the impurities goes into AMPF, and then, in the process of sorption, from the liquid phase to sulfocationite. Under these conditions, an additional complete purification of phosphoric acid from all impurities contained in fertilizer ammonium phosphates occurs.

Ammonium ions are desorbed with a dilute sulfuric acid solution, since the use of concentrated sulfuric acid is limited, firstly, by the concentration of ammonium sulfate solution formed during desorption (when it contains more than 35-40%, ammonium sulfate crystals precipitate on the cation exchanger), and secondly, possible partial destruction of cation exchange resin granules. The ammonium sulfate solution formed during desorption is mixed with an insoluble residue. The insoluble residue is essentially brand B ammophos, since it contains 45-47% P ₂ O ₅ and 10-11% N, the latter are represented by monoammonium phosphate that has not transferred to the liquid phase, phosphates of Fe, Al, Ca, REE located in digestible by plants.

By mixing ammonium sulfate and an insoluble residue, a fertilizer is obtained - sulfoammophos, containing, in addition to phosphorus and nitrogen, a significant amount of sulfur in the sulfate form, also necessary for plants.

At the same time, by varying the amount of components to be mixed (a solution of ammonium sulfate and insoluble residue), it is possible to obtain fertilizers at the request of consumers containing different mass fractions of total phosphates, total nitrogen and total sulfur. In addition, ammonium sulfate and an insoluble residue (ammophos grade B) can be used independently.

The method is illustrated by the following examples.

Example 1. 1000 g of ammophos produced by Voskresensk Mineral Fertilizers OJSC (P ₂ O ₅ total - 52.8%; P ₂ O ₅ assimilation - 52.5%; P ₂ O ₅ water - 46.2%; Ntotal 11.8; SO ₄ 5.35%; CaO 2.16%; Fe ₂ O ₃ 1.1%; Al ₂ O ₃ 0.4%; REE ₂ O ₃ 0.2 %; F - 1.08%) is mixed with 1700 g of water at the initial ratio of liquid and solid phases T: W = 1: 1.7, for 30 min, at a pH of the system of 4.2; 2700 g of the resulting pulp is separated by centrifugation into 2310 g (1950 ml) of an ammonium phosphate solution (AMPF) containing P ₂ O ₅ - 18.8%; N amm. - 3.93%; SO ₄ - 1.7%; Fe ₂ O ₃ - 0.008%; Al ₂ O ₃ - 0.003%; REE ₂ O ₃ - 0.001%; F - 0.02%) and 390 g of a wet insoluble residue (HO) containing, in terms of the product dried at 100-105 ° C, P ₂ O ₅ total. - 46.9%; P ₂ O ₅ ass. - 46.5%; P ₂ O ₅ water. - 6.8%; Ntotal - 10.6%; SO ₄ - 7.17%; CaO - 6.3%; Fe ₂ O ₃ - 5.4%; Al ₂ O ₃ - 1.96%; REE ₂ O ₃ - 1.0%; F - 3.35%).

AMPF is treated with 2925 ml of sulfonic cation exchanger KU-2 × 8 in the H ⁺ form, 2885 g of phosphoric acid containing 15.05% P ₂ O ₅ (20.8% H ₃ PO ₄ ), 1.36% sulfate ion are obtained, N amm. - absent .; Fe ₂ O ₃ - traces; Al ₂ O ₃ - traces; REE ₂ O ₃ - no .; F - 0.007%, and is directed to the deposition of sulfate ions by barium carbonate; 2967 g of the resulting pulp is filtered, 145 g of an uncleaned precipitate of barium sulfate is washed with water, the filtrate (phosphoric acid) is combined with washings, evaporated at 110-115 ° C to a concentration of P ₂ O ₅ - 52.94% (73.06% H ₃ PO ₄ ) and get 820.3 g of food phosphoric acid (the composition is presented in table 1), when P ₂ O _{5 is} extracted from ammophos equal to 82.2%, and the washed precipitate of barium sulfate is dried at 100-105 ° С and output as a commercial product.

Sulfocathionite in the NH ₄ form is subjected to desorption of 4000 g of a 10% solution of sulfuric acid; this produces 4060 g of a 9.88% solution of ammonium sulfate, which is mixed with 390 g of a wet insoluble residue, the resulting pulp is evaporated to a moisture content of 8.5%, granulated in a granulator, dried at 100-105 ° C and 721 g of sulfoammophos containing P ₂ O ₅ total - 12.6%; P ₂ O ₅ ass. - 12.6%; N - 15.2%; cation exchange resin after desorption is returned to the head of the process for processing new quantities of AMPF.

Table 1
The composition of food phosphoric acid (PFC) according to the claimed method (according to example 1) TECHNICAL INDICATORS,% PFC according to the claimed method Mass fraction of phosphoric acid (H ₃ PO ₄ ), not less than 73.0 Mass fraction of sulfates, no more 0.001 Mass fraction of iron, no more 0.001 Mass fraction of heavy metals hydrogen sulfide group (Pb), not more than 0.0001 Mass fraction of arsenic, no more 0.0001 Mass fraction of fluoride compounds (F), no more 0.001 Mass fraction of mercury, no more 0.00005 Mass fraction of volatile acids (CH ₃ COOH), no more 0.001 Mass fraction of chlorides, no more 0.001 Mass fraction of cadmium 0,0005 Mass fraction of suspended particles, no more absent

Food phosphoric acid was obtained using the same method as an example of another fertilizer of ammonium phosphate - diammophos.

Example 2. 1000 g of diammophos produced by Voskresensk Mineral Fertilizers OJSC (P ₂ O ₅ total. - 47.3%; P ₂ O ₅ assy. - 47.2%; P ₂ O ₅ water. - 41.2%; N total - 16.8%; SO ₄ - 5.20%; CaO - 1.8%; Fe ₂ O ₃ - 1.0%; Al ₂ O ₃ - 0.3%; REE ₂ O ₃ - 0 , 2%; F - 1.0%) is mixed with 2500 g of water at the initial ratio of liquid and solid phases T: W = 1: 2.5, for 30 min, at a pH of the system of 6.4; 3500 g of the resulting pulp is separated by centrifugation on 3080 g (2700 ml) of an ammonium phosphate solution (AMPF) containing 12.74% P ₂ O ₅ ; N amm. - 4.8%; SO ₄ - 1.2%; Fe ₂ O ₃ - 0.006%; Al ₂ O ₃ - 0.003%; REE ₂ O ₃ - 0,0008%; F - 0.015% and 420 g of wet insoluble residue (BUT), containing, in terms of dried at 100-105 ° C product P ₂ O ₅ total. - 44.8%; P ₂ O ₅ ass. - 44.6%; P ₂ O ₅ water. - 7.0%; N total - 11.2%; SO ₄ - 8.3%; CaO - 6.3%; Fe ₂ O ₃ - 5.5%; Al ₂ O ₃ - 2.0%; REE ₂ O ₃ - 1.0%; F - 5.30%). AMPF is treated with 4053 ml of sulfonic cation exchanger KU-2 × 8 in the H ⁺ form, 3846 g of phosphoric acid containing 10.2% P ₂ O ₅ (14.08% H ₃ PO ₄ ), 0.9% sulfate ion are obtained, N amm. - absent .; Fe ₂ O ₃ - traces; Al ₂ O ₃ - traces; REE ₂ O ₃ - no .; F - 0.006%), and is directed to the deposition of sulfate ions by carbon dioxide strontium; 3900 g of the resulting pulp is filtered, 140 g of an uncleaned precipitate of strontium sulfate is washed with water, the filtrate (phosphoric acid) is combined with washings, evaporated at 110-115 ° С to a concentration of P ₂ O ₅ - 61.7% P ₂ O ₅ (85, 1% H ₃ PO ₄ ) and 636.0 g of food phosphoric acid are obtained (the composition is shown in Table 2), when P ₂ O _{5 is} extracted from ammophos equal to 82.8%, and the washed precipitate of strontium sulfate is dried at 100 -105 ° C and displayed in the form of a commercial product.

Sulfocathionite in the NH ₄ form is subjected to desorption of 4000 g of a 10% solution of sulfuric acid; this produces 4060 g of a 9.88% solution of ammonium sulfate, which is mixed with 420 g of a wet insoluble residue, the resulting pulp is evaporated to a moisture content of 8.5%, granulated in a granulator, dried at 100-105 ° C and 710 g of sulfoammophos containing P ₂ O ₅ total - 11.3%; P ₂ O ₅ ass. - 11.2%; N - 14.8%; cation exchange resin after desorption is returned to the head of the process for processing new quantities of AMPF.

table 2
The composition of food phosphoric acid (PFC) according to the claimed method (according to example 2) TECHNICAL INDICATORS,% PFC according to the claimed method Mass fraction of phosphoric acid (H ₃ PO ₄ ), not less than 85.0 Mass fraction of sulfates, no more 0.001 Mass fraction of iron, no more 0.001 Mass fraction of heavy metals hydrogen sulfide group (Pb), not more than 0.0001 Mass fraction of arsenic, no more 0.0001 Mass fraction of fluoride compounds (F), no more 0.001 Mass fraction of mercury, no more 0.00005 Mass fraction of volatile acids (CH ₃ COOH), no more 0.001 Mass fraction of chlorides, no more 0.001 Mass fraction of cadmium 0,0005 Mass fraction of suspended particles, no more absent

Using the proposed method, as shown by the examples, allows to obtain phosphoric acid with a much greater degree of purification. For comparison, we present the quality of purified acid obtained by extraction with tributyl phosphate, including using patented solutions produced by Voskresensky mineral fertilizers (Tables 3, 4).

A comparison of the main indicators of acid from HAIFA CHEMICAL (Israel) and PRAYON (Belgium) shows that their quality is practically not better than the acid obtained by our method (Tables 5 and 6), and prices, of course, above.

In addition, the method allows to obtain high-quality fertilizer - sulfoammophos, the need for which in agriculture is quite large, as well as strontium or barium sulfates. All of the above makes the method highly profitable.

Table 3
Resurrection mineral fertilizers orthophosphoric acid "improved" TU 2142-002-00209450-96 quality indicators name of indicator standards for brands fact BUT B one Appearance Faint yellow or yellow liquid corresponds to 2 Mass fraction of phosphoric acid (H ₃ PO ₄ ),%, not less 73 73 74 3 Mass fraction of sulfates,% no more 0.3 0.35 0.21 four Mass fraction of iron,% no more 0,03 0.04 0,03 5 Mass fraction of heavy metals of the hydrogen sulfide group (Pb),%, no more 0.001 0.001 <0.001 6 Mass fraction of arsenic,%, no more 0,0005 0,0005 0,0002 7 Mass fraction of fluoride compounds,%, no more 0.005 0.005 0.005 8 Mass fraction of tributyl phosphate,%, no more 0,0005 0,0005 0,0004 9 Mass fraction of suspended particles,%, no more 0.05 0.05 0.001 A danger sign is applied to the vehicle in accordance with GOST 19433-88

Table 4
Resurrection mineral fertilizers orthophosphoric acid "purified" TU 2142-001-00209450-95 name of indicator standards for brands fact T2 T3 one Appearance Faint yellow or yellow liquid corresponds to 2 Mass fraction of phosphoric acid (H ₃ PO ₄ ),%, not less 55 73 74 3 Mass fraction of sulfates,% no more 0.2 0.3 0.2 four Mass fraction of iron,% no more 0.02 0,03 0.02 5 Mass fraction of fluoride (F) compounds,%, no more 0.005 0.005 0.005 6 Mass fraction of tributyl phosphate,%, no more 0.005 0.005 0.004 7 Mass fraction of suspended particles,%, no more 0.1 0.1 0.001 A danger sign is applied to the vehicle in accordance with GOST 19433-88

Table 5
HAIFA CHEMICAL, Israel, phosphoric acid specific gravity: 1,686 at t 26 ° С chemical analysis name value,% ppm max P ₂ O ₅ 61.6 H ₃ PO ₄ 85 F 0,00084 8.4 Fe 0,0001231 1.23 As 0,000023 0.23 Cr 0.000001 0.01 Sa 0,00067 6.7 Cd 0.000001 0.01 Cu 0.000006 0.06 Ni 0.000004 0.04 Heavy metals Pb <0,0005 5 Cl 0,00055 5.5 SO ₄ 0.0056 56

Table 6
PRAYON, Belgium, phosphoric acid, 85-concentration, specific gravity: 1,689 at t - 26 ° С chemical analysis name value,% ppm max P ₂ O ₅ 61.5 H ₃ PO ₄ 85 F 0.001 10 Fe 0.001 10 As 0.00005 0.5 Pb 0.00005 0.5 Hg 0.000001 0.01 Cd 0.00002 0.2 Cu 0.0001 one Ni 0,0002 2 Heavy metals 0,0005 5 Cl 0.002 twenty SO ₄ 0,035 350 Pb 0,0005 0.5

Claims (4)

1. A method for producing purified phosphoric acid with simultaneous production and commodity sulphoammophos strontium or barium sulphate, characterized in that fertilizing ammonium phosphate was mixed with water, the pulp is separated into ammonium phosphate solution and an insoluble residue, ammonium phosphate solution is treated with cation exchange resin in H ⁺ form until complete absorption of ammonium ions to produce phosphoric acid and cation exchange resin in the NH ₄ ⁺ form, strontium or barium sulfates are precipitated from the acid with their carbonic salts, and are separated from the liquid phase in the form commercial products, and cation exchange resin in NH ₄ ⁺ form is subjected to desorption with a solution of sulfuric acid to obtain a solution of ammonium sulfate, which is mixed with an insoluble residue and the resulting pulp is evaporated, granulated and dried. 2. The method according to claim 1, characterized in that the mixing of fertilizer ammonium phosphate with water is carried out at T: W = 1: (1-3). 3. The method according to any one of claims 1 and 2, characterized in that the phosphoric acid is evaporated to a concentration of 73-85% H ₃ PO ₄ and removed from the process in the form of a finished product. 4. The method according to any one of claims 1 and 2, characterized in that the pulp of fertilizer ammonium phosphate is separated by centrifugation, and the separation of phosphoric acid from strontium or barium sulfates is carried out either by filtration or centrifugation.