SU1629291A1 - Process for producing complex fertilizer - Google Patents

Abstract

The invention relates to a method for producing a complex fertilizer, can be used in the production of long-acting mineral fertilizers and contributes to improving the quality of a product by increasing water-soluble and assimilable phosphates and reducing acidity. The proposed method for producing a complex fertilizer involves treating the phosphate raw material with ammoniated phosphoric acid, followed by granulation and drying of the stock. In this case, 50-70% of the total mass of phosphoric acid is ammoniated to a pH of 5-7 and divided into two streams: the first in an amount of 30-60% is evaporated to a moisture of 30-40% with the formation of one stripped off pulp, the second is mixed with the remaining amount of the starting phosphoric acid acids and are fed to the stage of processing phosphate raw materials, followed by mixing with one stripped off the pulp before granulating and drying the product. The proposed method allows improving the quality of the fertilizer by increasing the content of digestible phosphates by 20-30% and water-soluble by 20-40% and reducing the acidity of the product to a pH of 4.2-4.5 instead of 2.5-4.0 in the known method . 1 tab. (Ls

Description

The invention relates to a technique for producing complex durable fertilizers, ensuring fuller utilization of nutrients by plants.

The aim of the invention is to improve the quality of the product by increasing the water-soluble and assimilable forms of PaOs and reducing the acidity of the product.

As phosphate raw materials use phosphorite composition, May%. P20 25: CaO 39.7; C02 8.1; MDO 2.5, Н20з1,7.

Example 1. 750 kg of 20% phosphoric acid are divided into two streams. The first in an amount of 50% by weight (375 kg) is ammoniated to a pH of 7 46.7 kg of gaseous ammonia.

The resulting 421.7 kg of ammoniated suspension is divided into two parts, 60% by weight (253 kg) is mixed with the remaining amount (375 kg) of the initial phosphoric acid and treated with this solution (62-8 kg) 100 kg of phosphate After activation of 724 kg of the resulting mass (4 kg of CO 2 is removed) is mixed with the remaining amount of the suspension ammoniated to a pH of 7, the weight of which after evaporation to a moisture content of 30% is 100 kg

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The resulting slurry is dried and granulated. The finished product (388 kg) contains 45.1% P20 total, 33.3% PaOsycu (P205 ratio: P205 total 85%), 33.3 Paid (ratio P205 ratio: P205 total 74.2%), 9.4% N. Free acidity 0.8%.

Example 2. 750 kg of phosphoric acid are divided into two streams. The first in the amount of 60% by weight (450 kg) is ammoniated to a pH of 6 43.0 kg of gaseous ammonia.

The resulting 493 kg of ammoniated suspension is divided into two parts: 50% by weight (246.5 kg) are mixed with the remaining amount (300 kg) of the initial phosphoric acid and treated with this solution (546.5 kg) 100 kg of phosphate after activation of 640 kg of weight (6.5 kg of CO2 are removed) is mixed with the remaining amount of the suspension ammoniated to pH 6, the weight of which after evaporation to a moisture content of 35% is 120 kg. The resulting slurry is dried and granulated.

The finished product (384 kg) contains 45.5% Pa Total, 40.1% P20zusv (ratio P205usv, PaGeneral 88.2%), 34.6% P205water (ratio Pg05water: P205 total 76%), 8.7N Acid free 0, 6%

Example 3 750 kg of phosphoric acid is divided into two streams. The first in the amount of 70% by weight (525 kg) is ammoniated to a pH5 of 39.9 kg of gaseous ammonia.

The resulting 564.5 kg of ammoniated suspension is divided into two parts: 30% by weight (169.3 kg) is mixed with the remaining amount (225 kg) of the initial phosphoric acid and 100 kg of phosphate is treated with this solution (394.3 kg). After activation, 489 kg of the mass (5.3 kg of CO2 are removed) are mixed with the remaining amount of the suspension ammoniated to a pH of 5, the weight of which after evaporation to a moisture content of 40% is 140 kg.

The resulting slurry is dried and granulated. The finished product (389 kg) contains 44.9% P205 total, 39.0% P205usv (ratio

P205usv: P205 total 86.8%), 34.0%. P205VOD

(P205water ratio: P205 total 75.8%), 7.9% N. Acid free 1.0%.

The table shows the parameters of the process within the proposed limits (examples 1-3) and beyond their upper and lower levels (examples 4-11).

Reducing the amount of phosphoric acid, ammoniated to a pH of 5-7, up to 40% of the total mass (example 4) leads to a decrease in process performance. This is due to the feed to the phosphorite activation stage of a more acidic suspension (pH 2), which leads to a partial decomposition of the phosphate raw material. The latter affects the process of regrogradation of F 205 and

a decrease in the content of the water-soluble form of P20s in the product, as well as an increase in the residual acidity. Increasing the amount of phosphoric acid to 80% of the total mass (Example 5) impairs the process performance due to the fact that a solution with a high pH (pH 4) is supplied at the activation stage, does not allow the activation of phosphorite. This leads to the retrogradation of water-soluble forms of P20s.

A decrease in pH at the ammonization stage of less than 5 (Example 6) increases the acidity of the product due to the use of more acidic phosphorus containing solutions at the activation stage.

An increase in pH at the ammonization stage of more than 7 (example 7) leads to a sharp thickening of the pulp and the impossibility of its pulping and transportation.

0 Decrease in the share of phosphoric acid with

A pH of 5-7 supplied to mixing with the starting phosphoric acid to 20% (Example 8) leads to a decrease in process performance due to retrogradation of P20b and an increase in 5 acidity of the product.

An increase in the proportion of phosphoric acid with a pH of 5-7, fed to the mixture with the starting phosphoric acid, up to 70% (example 9) also affects the quality of the product due to the high pH (more than 4) at the activation stage.

A decrease in the humidity of the solution ammoniated to a pH of 5–7 with parsing less than 30% (Example 10) leads to thickening of the pulp and deterioration of the processes of granulation 5 and drying.

An increase in the humidity of the solution ammoniated to a pH of 5–7 with parsing less than 30% (example 10) leads to thickening of the pulp and deterioration of the processes of granulation 0 and drying.

An increase in the moisture content of the solution ammoniated to a pH of 5–7 with overpare more than 40% (Example 11) leads to a decrease in the intensity of the granulation and drying process. 5 The proposed method allows improving the quality of fertilizer by increasing the content of digestible phosphates by 20-30% and water-soluble by 20-40%, reducing the acidity of the product to a pH of 4 2-4.5 instead of 2.5-0.0.0 in the known way.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION Method for producing a complex fertilizer, including preliminary ammonization of initial phosphoric acid, 5 processing of phosphate raw materials with ammoniated phosphoric acid followed by granulation and drying of the product, characterized in that, in order to improve the quality of the product by increasing water-soluble and digestible forms P20s and reducing the acidity of the product, 50-70% of the total mass of phosphoric acid is ammoniated to a pH of 5-7 and divided into two streams: the first in the amount of 30-60% is evaporated to a moisture of 30-40% with the formation of one stripped pulp, and the second is mixed with the remaining the amount of the initial phosphoric acid and serves on the processing of phosphate raw materials, followed by mixing the resulting mass with one stripped off the pulp.