RU2156754C1 - Method of production of granulated neutralized superphosphate - Google Patents

Abstract

FIELD: inorganic fertilizers. SUBSTANCE: invention relates to processing technology of pour phosphate raw, in part, dolomitized and iron-containing phosphate raw from layers of phosphate ores containing large amount of acid-soluble impurities to granulated neutralized superphosphate. Method of production of granulated neutralized superphosphate involves decomposition of phosphate raw with sulfuric acid, two-stage neutralization of pulp firstly with phosphate raw to pH 2-2.5 and the second neutralization stage is carried out with ammonia and/or salt solution with pH 4.6-10 to pH 3.6-6. Method provides increase of total sum of nutrient substances in fertilizer to 24.8-31%, yield of commercial fraction is 95-98%. EFFECT: improved method of production, increased content of nutrient substances and commercial fraction. 1 tbl, 5 ex

Description

 The invention relates to techniques for processing granular neutralized superphosphate of poor phosphate raw materials, in particular dolomitic and iron-containing phosphate raw materials (for example, Kingisepp, Vyatka-Kama, Karatausky and other deposits of phosphate ores containing a large amount of acid-soluble impurities).

A known method for the production of granular superphosphate (AS USSR N 1465436. The method of producing granular superphosphate. Authors: Zavertyaeva T. I., Novikov A.A., Kuznetsova A.A. et al. Z. 25.08.87, op. 15.03 .89. BI N 10), in which phosphate raw materials, taken in an amount of 60-90% of the original in the form of a suspension with T: W = 1: 1-2,3, are decomposed with sulfuric acid at a concentration of 75-98% in an amount of 1.6 -2.3 parts by weight per 1 t of P ₂ O ₅ phosphate raw materials, the resulting pulp is mixed with the remaining part of the raw material, taken either in dry form or in suspension with T: W = 1: 1-2.3, then granulation and drying of the product with flue gases are carried out simultaneously followed by absorption of exhaust gases using effluents after the absorption step to prepare a suspension of phosphate feed.

 The disadvantages of this method in the processing of dolomitic and iron-containing phosphate raw materials are not a sufficiently high degree of decomposition of phosphate raw materials at the stage of neutralization, high acidity and hygroscopicity of the finished product and low yield of the commercial fraction at the granulation and drying stage.

 The closest is a method for producing ammonized granular superphosphate (RF Patent N 2107053. A method for producing ammoniated granular superphosphate. Authors: Treschenko NN, Dmitrevsky B. A., Filimonov A. A., Dremov A. V., Yuryev V. I. ., Kostyuzheva MG, Shvetsov OV. Op. 20.03.98. BI N 8), including the decomposition of phosphate raw materials with sulfuric acid, two-stage neutralization of the pulp with phosphate raw materials to a pH of 2-2.5, and then an ammonia-containing reagent to pH 2.8-3.5, granulation and drying of the finished product. Dolomitized phosphate ores, in particular of the Kingisepp deposit, are used as phosphate raw materials, and ammonia and pulp of phosphates and ammonium sulfate with a pH of 4.5 are used as an ammonia-containing reagent.

The disadvantage of this method is the insufficiently high quality of the finished product, in particular, the content of P ₂ O _5sv is 16-16.3%, P ₂ O _5sv is 0-1.2%, N is 0.8-1.5%. The total amount of nutrients does not exceed 18%, the ratio of P ₂ O _5usv to P ₂ O _5total is 91.5-93.5%, the yield of the commercial fraction is 90-95%.

The objective of the invention is to improve the quality of the finished product, namely, obtaining a neutralized product containing 14.5-25.5% P ₂ O ₅ , 0-9.6% N, 0-14.2% K ₂ O with a total nutrients 24.8-31%.

 The method of producing granular neutralized superphosphate includes the decomposition of phosphate feedstock with sulfuric acid, two-stage neutralization of the pulp using phosphate feedstock and neutralization to pH 2-2.5, granulation and drying of the finished product, and the second stage of neutralization is carried out to pH 3.6-6.0 ammonia and / or salt solutions with a pH of 4.6-10.0.

The change in the process conditions is achieved by changing the pH in the second stage of neutralization to 3.6-6.0 by the introduction of salt reagents with a pH of 4.6-10, in particular solutions of salts of phosphates and ammonium sulfate and potassium carbonate and mixtures thereof. This allows you to increase the content of P ₂ O ₅ and nitrogen and introduce potassium into the fertilizer, increase the total amount of nutrients, increase the amount of P ₂ O _{5 sut} relative to P ₂ O _{5 total} , increase the amount of water-soluble salts and thereby increase the yield of the commercial fraction. The essence of the process is illustrated by examples.

Example 1. 1000 kg of Kingisepp flotation concentrate composition: 28% P ₂ O ₅ , 40.8% CaO, 2.5% MgO, 6% CO ₂ , 2.6% F, 8% insoluble residue are suspended in water coming from the absorption offices in relation to W: T = 1: 1. 85% of the suspension is sent for decomposition with sulfuric acid. The concentration of sulfuric acid is 93%, the norm of sulfuric acid is 607 kg. The ratio of W: T in the initial suspension is 1.65. The decomposition process proceeds at a temperature of 90 ^o C for 2.5 hours. The amount of pulp is 2290 kg. The decomposition coefficient of phosphorite is 96%. The pH of the pulp is 1. The pulp is fed to neutralize the rest of the suspension of phosphate concentrate. The neutralization process takes place at a temperature of 80 ^o C for 2 hours to a pH of 2.5. The amount of pulp is 2580 kg. The degree of decomposition of phosphates and carbonates is 63%. Further, the pulp is fed to neutralization with ammonia and ammophos pulp with a pH of 4.6. Pulp consumption is 857 kg, in terms of P ₂ O ₅ - 300 kg (the ratio of P ₂ O _{5 pulp} to P ₂ O _{5 raw materials} is 1.07), nitrogen - 72 kg. Ammonia consumption is 30 kg. The neutralization process takes place at a temperature of 80 ^o C for 5 min to a pH of 3.6. Pulp goes to drying and granulation. The finished product in an amount of 2200 kg has a composition of 26.3% P ₂ O _{5 total} 25.5% P ₂ O _5USB , 4.4% N. The amount of nutrients in the fertilizer is 29.4%. The ratio of P ₂ O _5swr to P ₂ O _5total is 97%. The output of the commercial fraction is 96%.

Example 2. 1000 kg of Kingisepp flotation concentrate composition: 30% P ₂ O ₅ , 41.7% CaO, 1.7% MgO, 5% CO ₂ , 2.7% F, 6% insoluble residue are suspended in water in relation to W: T = 2: 1. 90% of the suspension goes to decomposition with sulfuric acid. The concentration of sulfuric acid is 93%, the norm of sulfuric acid is 630 kg mng. The ratio of W to T in the initial pulp is 2.63: 1. The decomposition process proceeds at a temperature of 95 ^o C for 3 hours. The amount of pulp is 3277 kg. The decomposition coefficient of phosphorite is 96%. The pH of the pulp is 0.8. The pulp enters to neutralize the remainder of the suspension of phosphate rock concentrate. The neutralization process proceeds at a temperature of 85 ^o C for 1.5 hours to a pH of 2.3. The amount of pulp is 3610 kg. The degree of decomposition of phosphates and carbonates is 72%. Further, the pulp is fed to neutralization with a potassium-containing alkaline reagent. Neutralization takes place for 30 minutes at a temperature of 85 ^o C to a pH of 6. As a reagent, a 47% potash solution with a pH of 9.9 is used. The amount of solution is 937 kg. Pulp goes to drying and granulation. The finished product in the amount of 1925 kg has a composition of 15.58% P ₂ O _{5 total} 14.58% P ₂ O ₅ assimilation, 14.2% K ₂ O. The amount of nutrients is 29.2%. The amount of P ₂ O _{5 sut} in relation to P ₂ O _{5 total} is 93.55%. The output of the commercial fraction is 95%.

 Example 3. 1000 kg of Kingisepp flotation concentrate composition specified in example 1, suspended in water in a ratio of W: T = 2.3: 1. 88% of the suspension is decomposed by sulfuric acid. The concentration of sulfuric acid is 93%, the norm of sulfuric acid is 645 kg mng.

The ratio of W to T in the initial pulp is 4: 1. The decomposition process takes place for 2.5 hours at a temperature of 100 ^o C. the Number of pulp 3580 kg The decomposition coefficient of phosphorite is 96%. Pulp has a pH of 0.7. The pulp enters to neutralize the remainder of the suspension of phosphate rock concentrate. The neutralization process proceeds at a temperature of 90 ^o C for 1 hour to pH 2. The amount of pulp 3920 kg The degree of decomposition of phosphates and carbonates is 70%. Further, the pulp enters the neutralization of 60% potash solution with a pH of 10 and ammophosic pulp with a pH of 5.

The amount of potash solution is 120 kg, of ammophos pulp - 615 kg (in terms of P ₂ O ₅ 200 kg (P ₂ O _{5 pulp} / P ₂ O _{5 raw materials} = 0.71), for nitrogen - 48 kg). The process proceeds at a temperature of 90 ^o C for 10 min to a pH of 5.3. Pulp goes to drying and granulation. The finished product in an amount of 2050 kg has a composition of 23.4% P ₂ O _{5 total} , 22.4% P ₂ O _5USB , 2.3% N, 2.4% K ₂ O. The amount of nutrients is 27.1%. The ratio of P ₂ O _{5 water} to P ₂ O _5USr is 95.7%. The yield of the product fraction is 97%.

Example 4. 850 kg of Upper Kama washed phosphorite concentrate composition: 23% P ₂ O ₅ , 36% CaO, 4.5% Fe ₂ O ₃ , 3% Al ₂ O ₃ , 0.8% MgO, 2.7% F, 4.8% CO ₂ , 15% insoluble residue is treated with 2000 kg of 25% sulfuric acid. The ratio of W to T in the initial pulp is 2.35: 1. The decomposition process takes place for 2 hours at a temperature of 90 ^o C. The amount of pulp 2850 kg The decomposition coefficient of phosphorite is 98%. The pulp has a pH of 0.9. The pulp enters to neutralize 150 kg of phosphorite. The neutralization process takes place for 1 hour at a temperature of 90 ^o C to a pH of 2.5. The amount of pulp is 3000 kg. The degree of decomposition of phosphates and carbonates is 90%. Then the pulp goes to neutralization. Ammophos pulp with pH 7 is used as an ammonia-containing neutralizing agent. The amount of pulp is 743 kg (200 kg of P ₂ O ₅ (P ₂ O _{5 pulp} / P ₂ O _{5 raw materials} = 0.87) and 78.8 kg of nitrogen). The neutralization process takes place at a temperature of 90 ^o C for 3 min to a pH of 4.5. Pulp goes to drying and granulation. The finished product in an amount of 2196 kg has a composition of P ₂ O _5total - 21.2%, P ₂ O _5svv - 20.9%, nitrogen - 3.9%. The amount of nutrients is 24.8%. The ratio of P ₂ O _5swr to P ₂ O _5total is 98.6%. The output of the commercial fraction is 98%.

Example 5. 1000 kg of calcined Vyatka-Kama phosphorite composition: 24.9% P ₂ O ₅ , 38.9% CaO, 4.9% Fe ₂ O ₃ , 3.24% Al ₂ O ₃ , 0.86% MgO , 16.2% of the insoluble residue is suspended in circulating water in a ratio of 1: 1; 85% of the pulp is treated with 500 kg of 93% sulfuric acid. The ratio of W: T in the original pulp is 1.6: 1. The decomposition process takes place for 1.5 hours at a temperature of 90 ^o C. The amount of pulp is 2200 kg. The decomposition coefficient of phosphorite is 98%. The pulp has a pH of 0.9. The pulp is supplied to neutralize the remainder of the phosphorite suspension. The neutralization process takes place for 1 hour at a temperature of 80 ^o C to a pH of 2.5, The amount of pulp is 2500 kg. The degree of decomposition of phosphates is 90%. Further, the pulp is fed to neutralization by pulp containing a mixture of ammonium phosphates and sulfate at a pH of 6.8 in the amount of 1500 kg (378 kg of ammonium sulfate (80 kg of nitrogen), 567 kg of ammonium phosphates (300 kg of P ₂ O ₅ (P ₂ O _{5 pulps} / P ₂ O _{5 raw materials} = 1,2) and 120 kg of nitrogen) and 945 kg of water) and ammonia. The neutralization is carried out at a temperature of 80 ^o C for 1 min to a pH of 4.8. The ammonia split is 50.7 kg. The pulp goes to granulation and drying. The finished product in an amount of 2525 kg has the composition: P ₂ O _{5 total} 21.7%, P ₂ O _5USB - 21.4%, nitrogen - 9.6%. The ratio of P ₂ O _5swr to P ₂ O _5total is 98.6%. The total amount of nutrients is 31%. Yield 98%.

 In the table. comparative indicators of the proposed and known methods are given.

As can be seen from the table, increasing the pH of the stage of neutralization of superphosphate pulp from 2.8-3.5 to 3.6-6 by introducing ammonia-containing or potassium-containing salt reagents with a pH of 4.6-10 instead of pH 4.5 can improve the quality of the product, and namely, to increase the content of P ₂ O _{5 sut} in the finished product, increase the nitrogen content and add potassium to 14.2%, increase the amount of nutrients to 24.8-31%, increase the amount of assimilated P ₂ O ₅ in the finished product relative to P ₂ O _5total from 93.1-93.5% to 93.55-98.7%, increase the yield of the product fraction from 92-96% to 95-98% due to increased ia - the amount of water soluble salts. An increase in the pH of the stage of neutralization above 6 is impractical, since in this case ammonia will go into the gas phase during drying, and an increase in the amount of potassium will lead to a decrease in the physicochemical properties of the product, in particular hygroscopicity, a decrease in pH below 3.6 will lead to a decrease in nitrogen and potassium.

Claims (1)

 A method for producing granular neutralized superphosphate, including the decomposition of phosphate feedstock with sulfuric acid, two-stage pulp neutralization using phosphate feedstock in the first stage and neutralization to pH 2 - 2.5, granulation and drying of the finished product, characterized in that the second stage of neutralization is carried out to pH 3.6 - 6.0 with ammonia and / or salt solutions with a pH of 4.6 - 10.0.

Images