SU1057478A1 - Method for producing complex fertilizers - Google Patents

Abstract

1. A METHOD FOR OBTAINING COMPLEX FERTILIZERS by neutralizing ammonia-1COM mixture containing CaSO, followed by granulating and drying the finished product, which is used in order to reduce ammonia losses during neutralization and to obtain enhanced strength granules, the ratio and CaSO mixtures are taken within 1: 6.58, 5. 2. A method according to claim 1, of which is neutralized with ammonia at 30-80 ° C, and the granules are dried at 110-125 C. 3. The method according to claims. 1 and 2, that is, the use of unwashed phosphogypsum or unfiltered pulp obtained -: i in the production of phosphoric acid as mixtures containing Р2О5 and Са 804 is used as mixtures containing Р2О5 and Са 804. (L

Description

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The invention, the invention, relates to a process for the production of Compound fertilizers, widely used in agricultural production. A known method of obtaining complex fertilizers, including neutralizing phosphoric acid with alviak during the subsequent granulation and drying of the product at a temperature fli. The disadvantage of this method is that a large amount of ammonia (up to 20%) is contained in the exhaust gases after neutralization and granulation. that requires a large volume absorption equipment. Closest to the proposed technical essence and the achieved result is a known method of obtaining complex fertilizers by neutralizing with ammonia a mixture containing tjO and CasOj, followed by granulating and drying the finished product. According to this method, the mixture ratio is taken equal to CaSO 1: 0.1-0.6, neutralization of the mixture with ammonia is carried out at IIO-IIS C, and drying is carried out at a temperature of 80-100 ° C2. The disadvantages of this method are the low strength of the obtained granules. - 25-35 kg / cm and large ammonia roteries, which reach 5-10%. The purpose of the invention is to reduce ammonia losses during neutralization and to obtain granules of excellent strength. The goal is achieved by the method of obtaining complex fertilizers by neutralizing ammonia mixture, containing CaSOj j followed by granules tion and drying of the final product, "charge ratio in the mixture within CaSO 1: 6.5-8.5 .; It is advisable to neutralize the mixture with ammonia at 30–80 ° C, and drying the granules at 110–125 seconds; it is possible to use unwashed phosphogypsum or unfiltered pulp obtained in the production of extraction phosphoric acid as mixtures containing CaSO /. The essence of the method is as follows. The strength of the compound fertilizer granules is a resulting factor in physicochemical and chemical processes. The main factor is the concentration of PjjO and, one-and-a-half oxides in the liquid phase of the pulp, which is supplied for neutralization, as well as the degree of hydration of the original calcium sulfate. Sulfate-calcium adds water of crystallization and sets to form durable granules. Phosphoric acid, when heated, reacts with the sesquioxides contained in phosphogypsum, with the formation of complex compounds that form salt bridges in the granules during cooling and increase their strength. The ratio of P, - and. SaOZh, in the mixture also determines the neutralization temperature, the process proceeds without heat input and removal, and the loss of lmiac at a lower temperature is significantly reduced. The feasibility of the selected process intervals is illustrated in Table. 1 and 2. As can be seen from the table. 1, a decrease in the amount of CaSO in, a mixture of less than 6,5 results in an unacceptable decrease in the strength of the granules, and an increase in this amount above 8.5, although it does allow to increase the strength of the granules, it dilutes the fertilizer below the standard. As can be seen from the table. 2, at a temperature higher than that, large, more than 3% loss of ammonia occurs, and for carrying out the neutralization process at a temperature below 30 ° C, forced cooling of the mixture to be neutralized will be required, which is not energy viable. The dependence of the strength of the granules on the drying temperature is given in Table 3. When the granules are heated above, an intensive decomposition of monobamide and ionium phosphate occurs, as a result of which the strength of the granules decreases sharply. Lower temperatures also lead to lower granule strength. Example 1. A mixture consisting of 200 kg of PjOg and 1700 kg of Ca5Ots (CaSO4 ratio 1: 8.5) is neutralized with ammonia at 30 ° C dB pH 4.5, granulated and dried at 12 ° C. . Contents Eating 2% nitrogen and 11% P2O5 - The strength of the obtained granules is 90 kg / cm., ammonia loss is 0.5%. PRI mme R 2. A mixture consisting of 200 kg of 1500 kg of CasO4 (CaS04 ratio 1: 7.5) is neutralized with ammonia at pH 4.5, granulated and dried at 115c. The result is a fertilizer containing 2.5% nitrogen and 12% rochnost of the obtained granules 75 kg / cm, ammonia loss 1.5%. Example 3. The precipitate obtained in the production of phosphoric acid, containing 200 kg of PjO. and 1300 kg of CaSO4 (P-Fe: CaSO 1 S 6.5 ratio) are neutralized with ammonia at pH 4.0, granulated and dried at. The result is a fertilizer containing 3% nitrogen and 13% 1-2 OU. The strength of the obtained granules 60 kg / cm, the loss of ammonia 3%. The precipitate of the above composition is obtained by decomposing 1000 kg of apatite concentrate containing 394 kg of sulfuric and phosphoric acids in a known dihydrate process in which 386 kg of PfO5 goes into the liquid phase. The precipitate is separated

from the liquid phase, it is concentrated to a residual content of 200 kg P Ov, 1300 kg CaSO2 and 928 kg HgO. 186 kg of vyuskayut in the form of phosphoric acid containing 28-30% P2O5-, and the sediment is processed for complex fertilizer.

Instead of sediment to produce a complex fertilizer by the proposed method

unfiltered pulp can be used, half-finished in the production of phosphoric acid.

The use of the proposed method will increase the strength of the Granules compared with the prototype from 25-30 kg / cm to kg / cm and reduce the loss of ammonia from 5-10 to 0.5-3%.

Table 1

Claims (3)

1. METHOD FOR PRODUCING COMPLEX FERTILIZERS by neutralizing with ammonia a mixture containing ₽2 ° 5 ^{and CaS} C> 4 /, followed by granulation and drying of the finished product, with the exception that ', in order to reduce losses ammonia with a nitric mixture is taken in the range of 11: 6.5 The method according to Clause D, with the fact that neutralization with ammonia is carried out at 30-80 ° C, is carried out and granules of increased strength are obtained, the ratio of PjOg ^and CaSO, 8.5. 2. s and mixtures ___________ and drying the granules at 110-125 ° C 3. The method according to PP. 1 and 2, characterized in that, as mixtures containing P ₂ OJ and Ca SO ₄ , non-washed phosphogypsum or unfiltered pulp obtained in the production of extraction phosphoric acid are used.