SU1507730A1 - Method of producing monoammonium phosphate - Google Patents

Abstract

The invention relates to the preparation of reactive-grade phosphorus compounds. The monoammonium phosphate obtained by the proposed method can be used in the manufacture of optical glasses, electrolytes of universal phosphatization and in analytical practice. The purpose of the invention is to increase the yield of the product and its quality. The method is carried out by neutralizing phosphoric acid with ammonia gas at a temperature of 70-90 ° C to a pH of 3.0-3.3, followed by cooling the ammoniated solution to 20-25 ° C and separating the finished product. A solution of phosphoric acid with a mass ratio of P ₂ O ₅ : H ₂ O = 1: (1.1-1.3) is used, and ammonia is fed at a rate of 0.15-0.17 kg / h per 1 / kg P ₂ O ₅ The resulting product corresponds to the reactive qualification of the brand "hh". The product yield is 66-72%. 3 tab.

Description

The invention relates to the preparation of reactive-grade phosphorus compounds, in particular monoammonium phosphate, used in the manufacture of optical glasses, electrolytes, universal phosphatization and in analytical practice.

The aim of the invention is to increase the yield and quality of the product.

PRI me R 1. In the reactor, equipped with a stirrer and reflux condenser, placed 400 ml (544 g) of phosphoric acid with a mass ratio

PijOg: HgO 1: 1.2 and ammoniated at 85 ° C with gaseous ammonia fed at a rate of 0.15 kg / h (0.7 l / min) until the pH of the reaction medium is equal to 3.2 ( 95 min. The ammoniated solution is cooled to 23 s, the specific solids content in the cooled pulp is (T | 41 g / g. The precipitated crystals are separated from the mother liquor by centrifugation and dried in a drying oven). Get 246 g of monoammonium q

31507

veil, which corresponds to the brand:; | cf. The yield of the target product is 72%, the pH of a 5% solution of the preparation is 4.1.

According to a known method, monoammonium- (phosphate is obtained by neutralization) of orthophosphoric acid solution with a density of 1.4-1.44 g / cm and a mass: Pg-O: 1- (0.6-0.7) gaseous ammonia ratio to pH 5, The process of amnonization is carried out at 70-80 C rj ammonia consumption of 0.25-0.35 kg / h Shz / kg. After cessation of the ammonia in the ammoniated solution, orthophosphoric acid is supplied until the pH of the medium is 1–1.3, and then the reaction mass is cooled to 20–25 ° C. The monoammonium phosphate crystals obtained are separated from the mother liquor by centrifugation. The yield of the finished product is 35-45%. The pH of the 5% solution of the product is 3.0 to 3.64, which indicates the presence in the finished product of an impurity of free phosphoric acid and the inability to obtain a product of reactive qualification.

PRI mme R 2. Conditions are similar to Example 1. The difference is the mass ratio of PeCBiHijO in the initial solution of phosphoric acid.

Influence of mass ratio

The pH of the 5% solution is 4.0–4.2) and its maximum yield is 1 (66–72%) with a sufficiently high / specific solids content in the cooled pulp of monoammonium phosphate (0.37–0.42 g / g). .

When the ratio of PeOgiHg varies in the direction of reduction, a rather high product yield and specific solids content in the pulp are achieved, but the quality of the product in terms of the pH of a 5% solution decreases. The finished product contains an admixture of free phosphoric acid.

A change in the P ratio (205: Hg O towards an increase leads to a decrease in the yield of the product and a deterioration in its quality in terms of .рН 5% solution. The finished product contains an admixture of diammonium phosphate. In addition, a decrease in the specific solids content in the cooled pulp, and this leads to low-tech process.

PRI me R 3. Conditions are similar to example 1. The difference is the ammonia feed rate.

The effect of ammonia feed rate on the yield and quality of the product is presented in Table. 2

table 2

it 0.15 kg / h / kg PgOg is impractical because it significantly increases the duration of the process,

PRI me R A. Conditions are similar to example 1. Difference - the final pH value of the ammoniated solution.

The dependence of the yield and quality of the product on the pH value of the ammoniated solution is presented in table. 3

Table 3

From tab. 3 it follows that when the solution is ammo nated to a pH value equal to 3.0-3.3, a reactive qualification product is obtained, corresponding to the grade of chemically pure grade. (pH of 5% solution of 4.0- 4.2),

Carrying out the ammonization process to a pH of more than 3.3 or less than 3.0 leads to a decrease in the specific solids content of the monoammonium phosphate pulp in the product yield and deterioration of its quality due to the presence of an impurity, respectively, of diammonium phosphate or free phosphoric acid.

Claims (1)

Invention Formula The method of producing monoammonium phosphate,. including the treatment of an aqueous solution of orthophosphoric acid with gaseous ammonia at elevated temperatures, cooling the solution to 20–25 ° to form a precipitate of the product, followed by its separation from the mother liquor by centrifugation, so that and the quality of the product, the treatment is supplied with an acid with a mass ratio of PijOs and water 1: t, 1-1.3 and ammonia with a flow rate of 0.15-0.177 kg / h per 1 kg of PijOg in acid and the treatment is carried out to a pH of 3, 0-3.3. Editor M. Bandura Compiled by G. Tselishchev TechReD; JoeRes corrector. Little boy Order 5309/26 Circulation 435 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Subscription