SU1011618A1 - Process for producing complex fertilizer - Google Patents

Description

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00 The invention relates to a process for the production of fertilizers from nitrate-phosphate solutions formed during the decomposition of phosphate ores and sulfuric acids in the presence of alkali metal sulfates or ammonium. A known method for producing fertilizers, for example, nitrophosphates, involves incomplete decomposition of apatites in decomposition. norm of nitric acid when calcium ions are removed by introducing sulfuric acid and alkali metal or ammonium salts into the reaction medium during the decomposition process. The closest in technical essence and the achieved result to the invention is a method of obtaining fertilizers, including decomposition of ainaTHTa with nitric and sulfuric acids in the presence of ammonium sulfate at a ratio of liquid and solid phases in the reaction pulp of 3-5 and a concentration of excess sulfuric acid of 2030 g / l, filtering the production pool to produce a nitrate-phosphate solution (NFR, washing phosphogypsum with water, returning the washing solutions to decompose phosphorite ammonization, and removing NFR. A known method allows to obtain roammophos with a content of 22.7%, 7% with significant bathing capacity in the range from 21.1 to 21.6%. In addition, the yield in nitroammophos is only 92%. The disadvantage of this method is the relatively low amount of nutrients fertilizer. The aim of the invention is to improve the quality of the product by increasing the amount of nutrients. The goal is achieved by the method of decomposing the phosphate raw material with a mixture of nitric acid and ammonium sulfate at a T: W ratio equal to 3% in the presence of sulfuric acid, separating nitrate-phosphate solution tion filter washing. the phosphogypsum formed with water to form washing solutions and neutralizing the nitrate-phosphate solution with ammonia to form the finished product, the nitrate-phosphate solution is divided into two streams, one of which is directed to maintain the desired ratio, and the other is mixed with the washing solutions and fed to neutralize . With such a process, the end is increased. In the liquid phase of the decomposition pulp from 8.2 (known method) to 11.5%, which leads to an improvement in the filtering properties of phosphogypsum, the practical absence of the gypsum mantle, which makes it difficult for the unpowered to access acids. parts of phosphate And; as a result, to an increase in the yield of P O to fertilizer up to 95%. In addition, according to the invention, the ratio of the NFR, going to the production of fertilizers, is reduced. This is due to the fact that in the proposed method, circulating solutions do not participate in the decomposition of phosphorites, but only combine with a part of the first filtrate (thus forming NRF;) acting as a diluent, i.e. not changing the ratios of the components formed during the decomposition As a result, the quality of fertilizers is improved by reducing the ballast impurities introduced with sulfate ion, reducing retrogradation and increasing P Op, which is water soluble due to a decrease in the calcium content in the system. Example: 100 g of apatite (39.4% of processing 137.5 g of 47% nitric acid for 1 hour at 60 ° C in the presence of 211.5 g of a 32% solution of ammonium sulfate and 298.8 g of the first filtrate 50,2 g 92% are introduced into the pulp within 30 minutes sulfuric acid at 75-80 ° С and undergoing it for 1 hour at a concentration of excess sulfuric acid of 25-30 g / l. At that 20 g are removed with waste gases, and 778 g of pulp is filtered and 444.7 is obtained g of the first filtrate and 333.3 g of unwashed phosphogypsum (humidity 55%. Phosphogypsum was washed in a threefold countercurrent washing mode with 196.3 g of water, thus obtaining 230.8 g of washed phosphogypsum (humidity 35% and washing waters — the second filtrate in the amount of 298.8 g, which is combined with part of the first filtrate 145.9 g , and in the form of NFR (444.7 g) is directed to the production of fertilizers. The remaining amount of the first filter (444.7-145.9 298.8 g) is directed to the decomposition of apatite to maintain the desired ratio of liquid and solid phases. filtration of phosphogypsum 35 g / m per day with the height of the sediment layer 47 M1. 444.7 g NFR ammonizir comfort to a pH of 4.04-4.2, evaporated and dried at. 159 are obtained, IT of itrothammophos containing,%: aW3.5 23.2 / P ;, 2 Extraction-P O (from apathy; into nitroammophos 95.1%. The table below shows comparative results of testing known and peredgaemyh methods.

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Technical and economic advantages of 1.7%. When processing on the basis of the predicted method in comparison with Stin according to the proposed technology

well-known are in the uptake of 300 thousand tons of apatite can Sytopolnoe PjOg. 15% tons of nitro-g are obtained in nitroammophos by 3%

and the amount of nutrients in higher quality nemmmophos.

Claims (1)

(57) Process for the preparation of compound fertilizers consisting of decomposition of the phosphate raw material with a mixture of nitric acid and ammonium sulfate at a ratio of S: L equal to _3: and 5 in the presence of Ser hydrochloric acid, separation of nitrate-phos fatnogo filtration solution, washing the resulting phosphogypsum water to form rromyvnyh solutions and neutralizing the nitrate-phosphate solution with ammonia to form the finished product, characterized in that, in order to improve the quality of the product by increasing the amount of nutrients, the nitrate-phosphate solution is divided into two streams, one of which is directed to maintain a given ratio, and the other is mixed with washing solutions and served for neutralization. phosphorite and, as a consequence, to increase the yield of P O in fertilizer to> 95% * * * In addition, according to the invention CaO