RU2216526C1 - Method for preparing complex npk-fertilizer with regulated ratio of nutrient substances - Google Patents

Abstract

FIELD: fertilizers. SUBSTANCE: invention relates to manufacture of complex triple fertilizers containing potassium chloride of sulfate. Ammonium nitrate is added to product of decomposition of phosphate raw with acid after preliminary removing excess of calcium salts, mixture is neutralized with ammonia, evaporated and prepared pulp with pH 3.0-5.5 is mixed with potassium chloride or sulfate. Components are taken in amount providing the mass ratio ammonium nitrate to potassium salt in ready product = 1.6:1, not less. By regulation of amount of adding ammonium nitrate and potassium sulfate or chloride fertilizer is prepared with the ratio of nutrient substances N : P₂O₅ : K₂O in the limits (1-12) : (0.5-6) : 1, respectively. Method allows retention of pulp mobility at stage of mixing with potassium salt and feeding into granulator-drier that provides stabilization of working mixer and sprayers for mixture spraying. EFFECT: improved preparing method. 2 cl, 2 tbl

Description

 The invention relates to the chemical industry and can find application in the technology for the production of complex NRK fertilizers when producing a product using potassium chloride or sulfate as the potassium component.

Modern agrochemical science involves the use of fertilizers with a range of nutrient ratios (N: P ₂ O ₅ : K ₂ O) over a wide range, which requires the creation of technological processes that provide the possibility of obtaining fertilizers with an adjustable ratio of nutrients in accordance with the request of consumers.

A known method of producing a complex NPK fertilizer with an adjustable ratio of N: P ₂ O ₅ : K ₂ O, including acid decomposition of phosphate raw materials, the introduction of potassium nitrate, ammonization, evaporation, granulation and drying of the target product (ed. St. USSR 572442, cl. C 05 V 11/06, publ. 15.09.77). By controlling the flow of reagents, a complex fertilizer is obtained with a ratio of N: P ₂ O ₅ : K ₂ O 1.5: 1: 1; 1.2: 1: 0.5; 1.3: 1: 1. The disadvantage of this method is the use of potassium nitrate as a potassium component, an expensive and scarce component, which is essentially an effective independent double NK fertilizer.

 Closest to the proposed combination of essential features is a known method for producing complex NPK fertilizer with an adjustable nutrient ratio, including the decomposition of phosphate raw materials by acid, regulating the composition of the fertilizer by adding a nitrogen-containing component (urea) in an amount of 15-25% by weight of the finished product, neutralization the obtained pulp with ammonia to pH 6.0-8.0, mixing NP-pulp with potassium chloride, granulation and drying of the target product (ed. St. USSR 1685901, class C 05 V 11/06, publ. 23.10.91).

 The disadvantage of this method is the thickening of the mixture of NP-pulp with potassium chloride, which complicates the operation of the reactor-mixer and nozzles for feeding the mixture into a drum granulator-dryer. A similar disadvantage is manifested in the case of using potassium sulfate as a potassium salt.

 The technical problem solved by the proposed method is the elimination of thickening of the mixture and thereby the stabilization of the reactor-mixer and nozzles for spraying the mixture.

 The problem is solved in that in the method for producing complex NRK fertilizer with an adjustable nutrient ratio, including the decomposition of phosphate raw materials by acid, the addition of a nitrogen-containing component, neutralization with ammonia, mixing the NR pulp with potassium chloride or sulfate, granulation and drying of the target product according to the invention for mixing with a potassium salt serves NP-pulp with a pH of 3.0-5.5, ammonium nitrate is used as the nitrogen-containing component, and the components are taken in an amount that provides a mass ratio of nit ammonium atom: potassium salt in the final product of at least 1.6: 1.

The ratio of nutrients N: P ₂ O ₅ : K ₂ O in the fertilizer is regulated within the range of 1-12: 0.5-6: 1 by the amount of added ammonium nitrate and potassium salt.

 Example 1

The apatite concentrate is decomposed with nitric acid, the nitric acid extract is cooled to a temperature of 0 ÷ -5 ^o C, precipitated crystals of calcium nitrate tetrahydrate are separated by filtration, and a filtrate containing,% (hereinafter, weight percent) is obtained:
Phosphoric acid - 22.0
Calcium Nitrate - 16.1
Nitric acid - 14.0
The filtrate in an amount of 28.5 t / h is mixed with a 45% solution of ammonium nitrate, taken in an amount of 6.6 t / h, neutralized with ammonia, and evaporated to a residual moisture content of 9.5-12%. The pH value of the stripped-off NP-pulp is 3.0-5.5 (the measurement is carried out when diluted with water 1:10). One stripped off NP-pulp is mixed with potassium chloride (95% in the salt of the main substance), which is taken in an amount of 3.4 t / h, and with a scrubbing solution from the stage of purification of exhaust gases from fertilizer dust, the resulting mixture with a moisture content of 9-13% served in a drum granulator dryer. At the same time get 25 t / h of the target product with the following nutrient content,% (average):
N - 19.9, including in the form of ammonium nitrate 8.7 (49.5% in terms of ammonium nitrate)
P ₂ O ₅ - 18.2
K ₂ O - 8.0 (12.7% in terms of potassium chloride)
The mass ratio of ammonium nitrate: potassium chloride in the target product is 3.9: 1. The ratio of the above nutrients, respectively 2.49: 2.27: 1.

 The process of producing fertilizer is characterized by the stable operation of the reactor-mixer and nozzles (no stoppage or breakdown of the mixer, no clogging, etc.), which is further confirmed by the stable particle size distribution of the target product: the content of the 1-4 mm fraction is 95-97%, including the number of fractions 2-4 mm 82-86%.

 By adjusting the supply of components and the cooling mode of the nitric acid extract, the target product of various grades is obtained, the characteristics of which are given in Table 1. Moreover, in all cases, the stable operation of the reactor-mixer and nozzles is ensured, regardless of the type of potassium chloride or sulfate salt used.

 Upon receipt of complex fertilizer in the mode when the pH value of the NP pulp fed to mixing with potassium salt and the ratio of ammonium nitrate: potassium salt in the target product differ from the declared limits, the stable operation of the mixer reactor and nozzles is violated (see table 2 )

 Example 2 (prototype).

To 1000 g of the product obtained under industrial conditions by decomposing apatite concentrate with nitric acid, cooling the nitric acid extract to a temperature of 0 ÷ -5 ^o C, separating the crystals of calcium nitrate tetrahydrate (the composition of the product is shown in Example 1), add 300 g of carbamide, the mixture is stirred , neutralized with ammonia to pH 6, to a neutralized NP-pulp with a temperature close to 100 ^o With, add 270 g of potassium chloride. A granular fertilizer is obtained from a portion of the triple NPK mixture in a laboratory setup. Its composition,%:
N - 25.4, including in the amide form 11.7
P ₂ O ₅ - 13.5
K ₂ O - 13.6
The triple NPK mixture is prone to thickening (possibly due to partial decomposition of urea), which makes it difficult to obtain granules. The output of the fraction 1-4 mm 62%, including fractions of 2-4 mm 51%.

 From the presented data it follows that the claimed method, eliminating the disadvantage of the known, allows to obtain complex NPK-fertilizer with a ratio of nutrients that can be regulated within wide limits.

Claims (2)

 1. A method of producing a complex NPK fertilizer with an adjustable nutrient ratio, including the decomposition of phosphate raw materials by acid, the addition of a nitrogen-containing component, neutralization with ammonia, mixing NP-pulp with chloride or potassium sulfate, granulation and drying of the target product, characterized in that it is mixed with potassium salt serves NP-pulp with a pH of 3.0 ÷ 5.5, ammonium nitrate is used as the nitrogen-containing component, and the components are taken in an amount that provides the mass ratio of ammonium nitrate: potassium salt to the target product at least 1.6: 1. 2. The method according to p. 1, characterized in that the mass ratio of nutrients N: P ₂ O ₅ : K ₂ O in the fertilizer is regulated within 1 ÷ 12: 0.5 ÷ 6: 1 by the amount of added ammonium nitrate and potassium salt.

Images