SU952829A1 - Process for producing complex fertilizers - Google Patents

Description

(54) METHOD OF OBTAINING COMPLEX FERTILIZERS

The invention relates to a process for the preparation of complex fertilizers widely used in agriculture.

A known method of obtaining complex fertilizers, comprising mixing powdered superphosphate n ammonium nitrate, subsequent granulating the mixture with one-time steam and ammonia delivery and drying the finished product 1.

The disadvantages of the method are obtaining fertilizer with poor physical and mechanical properties and low intensity of the drying stage.

The closest to the invention of technical dryness and achievable results is a method of obtaining complex fertilizers by decomposing phosphate raw materials with sulfuric acid, followed by mixing the resulting mass with the individual components, granulation and drying of the product. In this method, sulfuric acid is taken in the amount of 2.3 mol H2S04 per 1 mole of PaOs, and, for example, ammonium nitrate, urea, etc., are used as mineral components, 2.

The disadvantages of the method are that i fertilizer contains 85% P2Os in water-soluble form, which is easily lost due to leaching of binding to soil cations into insoluble compounds. In addition, the method is complicated in technological design due to the fact that the initial mixture has a high moisture content and, consequently, large technological volumes and energy consumption are required at the stages of drying and absorption.

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The aim of the invention is to reduce the content of water-soluble forms of Pj Os while simplifying the process.

The goal is achieved according to the method of obtaining complex fertilizers by

15 decomposition of phosphate raw materials with sulfuric acid, taken in an amount of 0.6-1 moles of HjSO4 per 1 mole of PjOs, followed by mixing the resulting mass with mineral components, granulation and drying of the product.

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Claims (2)

Moreover, in order to increase the strength of the granules of the finished product, it is advisable to submit 35–75% of phosphate raw materials to the decomposition stage, and the rest to the granulation stage. 395 The essence of the method is that at the specified rate of sulfuric acid a mixture consisting of monocalcium phosphate, dicalcium phosphate and tricalcium phosphate is formed. Monocalcium phosphate is well soluble in water. The solubility of salts in water with further substitution of the hydrogen ion for calcium ion decreases greatly. As a result, at a certain ratio of these salts in the mixture, slow-acting fertilizer can be obtained, since the presence of monocalcium phosphate in sufficient quantity ensures the normal vegetation of plants in the initial period of development. Then dicalcium and tricalcium phosphate are added to the soil. The selected interval of the norm of sulfuric acid is explained by obtaining the necessary ratio between these salts and varies within the following limits: monokalaydiphosphate 60 + 10%, dicalcium phosphate 30 + 10%, tricalcium phosphate 10 + 10%. The feasibility of the selected norm of sulfuric acid is illustrated in the table. Amount of acid mol / mol 0.6 1.0 1.5 1.6 P2050.4 Content of water-soluble 50 58 65 75 Hygroscopic4-5 5-6 6-7 7-8% mmole / g-h 3-4 Reduction of water-soluble Forms below 50%, although it is important for obtaining slow-acting fertilizers, but it is undesirable because of the agrochemical activity. An increase in the acid rate above 1.5 m causes an increase in the content of water-soluble form in the fertilizer. Serving part of the phosphate raw material to the granulation stage allows the temperature of the granules to be raised and more granules to be obtained. When the raw material is supplied in a quantity of less than 35% at the stage of decomposition, additional moistening is necessary at the granulation stages, which complicates the process. An increase in raw materials of more than 75% leads to a decrease in the strength of the product granules. Example 1. Fosmuk of composition,%: PiOs 25, RecOz 1.3, ABOz 1.3, COj 7 in a quantity of 750 g decompose 433 g of H2SO4 at 60 ° C and then mixed with 416 g of KCl and 735 g of ammonium nitrate. The creep mixture is granulated at 80 ° C with the introduction of 250 g of phosphate powder. The product is dried at 160 ° C. A 1: 1: 1 fertilizer with a hygroscopicity of 6 mmol / g and strength 37 kgf / cm is obtained. Content of P2Osop "u Example 2. In the amount of 350 g of the composition,%: PjOs 27, RegOz 1.1, ABOz 1.1, CO2, decompose 189 g H, 2804 at 60 C and then mix it with 735 g of ammonium nitrate. The mixture obtained is granulated at 80 ° C with the introduction of 650 g of phosphoric acid. Prodztst dried at 160 ° C and get the fertilizer brand 1: 1: 0 with a hygroscopicity of 5.0 mmol / g h, strength 38 kgf / cm. PaOsg content 50%. Example 3. Fosmuk in the amount of 500 g of the composition,%: PjOs 25, RegOz 1.3, LOS 1.3, C02 7.0 decompose 288 g Hg S04 at 60 ° C and then 735 g of ammonium nitrate are mixed with 416 g of KC1. Received; the mixture is granulated at 80 ° C with the introduction of 500 g of phosphate flour. The product is dried at 160 ° C. A 1: 1: 1 fertilizer is obtained with a hygroscopicity of 4 mmol / gh, strength of 36.5 kgf / cm. Content EXAMPLE 4 In an amount of 1000 g, Fosmuk is decomposed with 288 g of H 2804 at 60 ° C and then mixed with 416 g of KC1 and 735 g of ammonium nitrate. The mixture obtained is granulated at 80 ° C and then dried at 130 ° C. A 1: 1: 1 fertilizer is obtained with a hygroscopicity of 5.5 mmol / g h and a strength of 34 kgf / cm. Content P2OsBOAH.63%. Using the proposed method allows to obtain a fertilizer slowly acting neck. P205gg, which characterizes the effect of fertilizer in the soil, is reduced from 85 to 50 by 65%. In addition, the method allows for its technological design to significantly reduce the volume and energy consumption at the stages of drying and gas absorption. The fertilizer is obtained with a hygroscopicity of 5.0-5.5 mmol / gh and a granule strength of at least 34-38 kgf / cm. 1. Method of obtaining complex fertilizers nyjeM phosphate raw material decomposition with sulfuric acid followed by mixing the resulting mass with mineral components, granulation and drying of the obtained product, characterized in that, in order to reduce the content of water-soluble PjOs while simultaneously simplifying the process, decomposition of sulfuric acid lead in the amount of 0.6, 1, 5 mol per 1 mol of P2O5. 2. A method according to claim 1, characterized in that, in order to increase the strength of the granules, 35-75% of the phosphate raw material is supplied to standard 59528296 I give decomposition, and the rest is on stage Gran 1. Pozin ME cast salts. Chemistry, Part 11, 1974, p. 1363-1375. Source of information, 2. Technological regulations N 252 Winprintoe into account when examining a chemical plant, 1968, p. 5-20.