SU842078A1 - Method of ammonium phosphate production - Google Patents

Description

one

The invention relates to the production of complex NP and NPK fertilizers and relates to the production of ammophos.

A method of producing complex fertilizers is known, for example ammonium phosphates in which phosphoric acid (45% solution) is neutralized with ammonia in the first stage to a molar ratio of NH: HjPO O, 7-0.85 with the formation of a slurry containing at a boiling point 15-16% pulp they are sent to the granulator, to which retur and ammonia are also supplied to pre-ammoniate the phosphoric acid remaining in the pulp, to a molar ratio of NH3: H PO4 of 1.36-1.6 at a moisture content of 8-16%. Then the resulting product is dried, classified and receive commodity fraction IJ.

The disadvantage of this method of obtaining the finished product with high humidity, which requires an additional stage of drying by supplying coolant.

The closest in technical essence and the achieved result. To the present invention is a method for producing ammophos by neutralizing phosphoric acid with ammonia, which includes the introduction of a phosphate additive in

starting phosphoric acid, neutralizing the resulting mixture with ammonia, granulating the resulting pulp, drying and cooling the resulting product 2.

However, the introduction of phosphate into phosphoric acid for decomposition does not have the necessary technological conditions for the complete decomposition of the phosphate molecule with the formation of phosphoric acid and sulfate (high temperature — 70–75 ° C and reaction time — 4 hours)

The decomposition of phosphate within 1 hour is carried out at about 60%. The total amount of non-decomposed phosphate completely passes into the finished product ammophos, which reduces the concentration of the i-soluble water-soluble form and impairs the quality

0 ammophos. Moreover, the decrease in the concentration of the aqueous form of P2O5 in ammophos occurs from 80 to 66%.

The purpose of the invention is to increase the yield of the finished product and reduce 5 consumption ratios.

The goal is achieved by the proposed method of obtaining ammophos by neutralizing phosphoric acid with mmonia, including the introduction of phosphate additives in the original phosphoric acid, neutralizing the resulting mixture with ammonia, granulating the resulting pulp, drying and cooling the resulting product, in which neutralization is carried out to pH 2 3 at 110-120 ° C, the phosphate additives are introduced into the resulting slurry and then the resulting mass is neutralized to pH 5 5.5. Monocalcium phosphate (0.040,225 tons per 1 ton of phosphoric acid) is used as a phosphate additive. The method is carried out as follows. At the stage of neutralization of concentrated phosphoric acid (4550%) with ammonia in one step, when pH reaches 2-3 and temperature 120s, mrnocalcium phosphate 0.04 0.225 tons per 1 ton of phosphoric acid are introduced, then the mixture is neutralized to pH 55, 5 (molar ratio) with obtaining ammophos pulp, which at a temperature of 125 ° C and a humidity of 15-30% is transferred to drying and granulation. Granulation and drying of the obtained pulp to a residual moisture content of 1% is carried out in one apparatus by spraying ammophos pulp with air onto a retur curtain. In the same apparatus it is possible to maintain the cooling of the product, which after cooling is classified by known methods. In the finished ammophos, the content of the aqueous form is reduced (as a result, the wearing of the assimilated water P, Oj is 98%) and the product remains with high chemical indicators of a total 51-52%; PjO assimilation 50.5-51.0%; water 49-50%; nitrogen 12%; H, O 1%. Granules have a high mechanical strength of 7090 kgf / cm. . The introduction of monocalcium phosphate at the stage of the neutralization of phosphoric acid makes it possible to obtain ammophos with a high content of the aqueous form P, jO5 and to use the chemical energy of sulfuric acid, an impurity in phosphoric acid; at the same time, the decomposition of monocalcium phosphate proceeds completely, with the result that the amount of phosphoric acid in the process and, consequently, ammophos without the main costs for the production of phosphoric acid increases. The introduction of monocalcium phosphate reduces the humidity of the ammophos pulp by 1%, which improves the operation of the granulation-drying apparatus (less flooding and cleaning). In the known method, the waste product (ammophos) contains,%: PjOif is total 45.7; R, 20 ss 44.9; RoO5 water 30.1; nitrogen 8.2; moisture 1. Attitude RaOb-usv. Example. 1, 1 ton of phosphoric acid is fed to the neutralizer; saturated with 45-50% of 8.2% SO (sulfuric acid is in the form of an impurity) and neutralized with ammonia to pH 2-3. In the process of neutralizing phosphoric acid with ammonia, the temperature of the pulp rises to 120 ° C due to the released heat of the chemical reaction; upon reaching the specified pH and temperature, 0.225 tons of monocalcium phosphate are introduced into the acid pulp and further neutralization is carried out to the molar ratio LH: HzP04 1 (pH 5-5, 5). the formation of an additional amount of phosphoric acid (45.0 kg per 100%), which forms a kg of ammophos. Next, the pulp enters the granulation, drying and cooling, carried out in one apparatus (BGSKhrabanny granule torus dryer-cooler). The cooled product is classified by known methods. The granules are obtained with a size of 1-3.2 mm. Ready ammophos has a composition,% :, absorption 51-52; water 50-51; nitrogen 11-12, 0.5-1.0. Example2. 1 ton of phosphoric acid, containing 45–50%, 2.5–3, –0% SO, j as an impurity, is supplied to the neutralizer and neutralized with ammonia to a pH of 2-3. In the process of neutralizing phosphoric acid with ammonia, the temperature of the pulp rises to 110-115 s due to the heat of a chemical reaction. Upon reaching the indicated pH and temperature, 0.04 tons of monocalcium phosphate are fed to the acidic ammophos pulp and the pulp is further neutralized to a pH of 5-5.5. Molar ratio of LH–.}: H3PO4 1. Calcium phosphate introduced into the pulp decomposes with sulfuric acid (an admixture of phosphoric acid) to form an additional amount of phosphoric acid in an amount of 8 kg per 100%, which corresponds to 16 kg of ammophos. Next, the pulp is fed to the granulation, drying and cooling in one apparatus of the BSF. The cooled product is classified according to known techniques. The granules are obtained with a size of 1-3.2 mm. The finished ammophos has the composition,%: 5- absorbed 51-52; water 50-51; nitrogen 11-12; 0.5-1.0. The use of the proposed method makes it possible at the stage of neutralizing phosphoric acid to effectively use the chemical energy of sulfuric acid, which is in the form of an impurity in phosphoric acid, to decompose calcium phosphate, which reduces the expenditure ratio for raw materials (phosphoric acid) in the production of ammophos by 8%. In this case, it is possible to increase the output of the finished product by 16-18% without additional costs for obtaining phosphoric acid.

In addition, the addition of monocalcium phosphate to ammophos pulp at the stage of saturation contributes to reducing the moisture content of ammophos pulp by 1%, compared with the existing ammophos production scheme, which significantly improves the physical properties of ammophos pulp, which, in turn, is favorably reflected on granulation - drying equipment (sticking of equipment decreases).

Claims (2)

1. A method of producing ammophos by neutralizing phosphoric acid with ammonia, which includes the introduction of phosphate additives in the original phosphoric acid, neutralization of the resulting ammonia mixtures, granulation of the obtained pulp, drying and cooling of the obtained product, characterized in that, in order to increase the yield of the finished product and reduce the consumption ratios, neutralization is first carried out to a pH of 2-3 at 110-120 ° C, the resulting pulp is injected phosphate additive and then the resulting mass is neutralized to pH 5.0-5.5. 2, a method according to claim 1, characterized in that monocalcium phosphate in an amount of 0.04-0.225 tons per 1 ton of phosphoric acid is used as a phosphate additive. Sources of information taken into account in the examination 1. US patent 3249421, CL.71-4 pub. 1963. 2. Avt; Orsk certificate of the USSR No. 350769, cl. From 05 To 1/06, published. 1972 (prototype).