SU564297A1 - Method for obtaining compound fertilizers - Google Patents

Description

one

The invention relates to the field of the production of mineral fertilizers and can be used to obtain complex fertilizers based on the decomposition of natural phosphates with mineral acids.

A known method of producing complex fertilizers is by decomposing natural phosphates with nitric acid at 120 ° C, followed by filtration of the nitric acid extract, ammoniation thereof, drying, and granulating the product l.

In this case, the aggression of the reaction medium at the boiling point of nitric acid and the difficulty of separating fluorine-containing gases from nitric acid vapors are high.

There is also known a method for producing complex fertilizers by decomposing natural phosphates with a circulating mixture of nitric and phosphoric acids, followed by treating the nitrogen-phosphoric acid extract with sulfuric acid, filtering it, ammonizing it, drying it and granulating the product 23,

The disadvantage of this method is the high fluorine content in the final product (1.2-1.5%).

The purpose of the invention is to reduce fluorine in the product.

To this end, the filtrate is first ammoniated in the presence of 1–2% active silicon dioxide to a pH of 2.0–2.5, evaporated for 6–90 min at 115–125 ° C to a water content of 20–40% and then doammoniziruyut to pH 4, O-6.0.

This allows for improved quality of the product by reducing the content in ;. there is fluorine in 3-6.

Example 1. As the raw material used phosphate Karatau of the following composition,%: PI Oy25,2; CaO 39.4; MgO 1.85; R i Oj 2.6; G 2.4.

Claims (2)

Per 100 weight parts phosphorite take 92 weight.h 47% nitric acid, 74 weight.h. 93% sulfuric acid. After the decomposition of phosphorus and the separation of phosphogypsum, the solution is partially directed to the decomposition stage (ZOO weight.h), and the other part, in the amount of 24O, weight. h, for processing into the final product, during the decomposition of the raw material and filtration of phosphogypsum 2% fluorine phosphate raw material is released into the gas phase and 13%. (0.31 wt. H.) Is removed with phosphogypsum to the dump. With the pro-auction part of the filtrate, 85% (2.0 wt. H) of all the fluorine from the raw material comes. For the isolation of fluorine, the solution is ammoniated to a pH of 2; previously, 2 wt. h. S O and sent to a vacuum evaporator, where for 60 minutes. at 115 ° C, the pulp is heated and the water is evaporated with a water content of 20%. From the vacuum of the evaporator, the pulp is sent to the BGS apparatus for pre-ammonia to pH 4 and further processed into nitroammophoska by mixing with potassium salt, drying, etc. In the process of evaporation, in the gas phase € 0-6 5% of fluorine released from the solution (Ij2 - 1.3 weight, h) is released. Consequently, 12–13 kg of fluorine as an additional product is obtained from 1 kg of fosn fatah raw material. The finished product (nitroammofosk) of composition N., K.f 17:17: 17 contains O, 2-O, 4% fluorine. Example 2. Karatau phosphorite is used as a raw material at the next co0, 5-25.2; CaO 39.4; 185 T 26 T 24. At 100 1 s. h phosphorite take 92 weight of 47% nitric acid, 72 weight. including 93% sulfuric acid, 300 wt. including working mixture of nitric and phosphoric acids and 12O weight. part - wash water after washing phosphogypsum. Phosphogypsum (146 parts by weight) is separated on a vacuum filter, washed with hot water (120 parts by weight), and sent to the dump. The washings are returned to the decomposition stage. The main filtrate (540 parts per hour) is partially directed to the decomposition stage (300 parts per hour), and the other part (240 parts per hour) is recycled to fertilizer. This solution is neutralized with ammonia (22 wt. H) at the beginning to a pH of 2.5, 4 wt. h. pre-input in neg-and - oev ;. i. .l "and sent to a vacuum evaporator, where for 90 minutes. at 125 ° C, the pulp is evaporated to a water content of 40%. At the same time, fluorine gases (including 1.2-1.3 parts by weight of fluorine) are released into the gas phase, which are sent for processing to obtain individual fluorine salts. From the vacuum evaporator, the pulp is sent to doammonization to pH 6, mixed with potassium salt (42 wt. H.), Then dried in the BGS apparatus to obtain a nitroammophos (155 wt. H), Formula of the invention The method of obtaining complex fertilizers by decomposing natural phosphate using a circulating mixture of nitric and phosphoric acids, followed by treatment of the nitric-phosphoric acid extract with sulfuric acid, its filtration, ammonium filtrate, drying and granulating the product, characterized in that, in order to reduce fluorine content duct, the filtrate in the presence of 1-2% is first ammoniated with active silicon dioxide to a pH of 2.0-2.5, evaporated for 60-90 minutes at 115-125 ° C to a water content of 20-40%, and then pre-ammoniated to pH 4.0-6.0. Sources of information taken into consideration - for examination: 1. Collected works of the Leningrad Technological Institute. Lensoveta, 1973, in. 4, s. 131-139, 2, Journal of Chemical Industry, 1971, vol. 47, No. 11, p. 829-831.