SU636210A1 - Method of obtaining granulated double superphosphate - Google Patents

Description

This invention relates to a process for producing granular double super phosphate — a highly efficient mineral fertilizer — from carbonate-containing phosphate raw materials.

There is a known method of extracting granulated double superphosphate by decomposing phosphate with phosphoric acid, followed by granulating and drying the product fij.

The disadvantages of the method are low productivity of technological systems and the complexity of the process due to the presence in the scheme of two apparatus for removing water - spray and drum dryers.

The technical essence and the achieved result most closely resemble the method for producing granulated double superphosphate, which consists in decomposing phosphate raw materials with phosphoric acid in the presence of a retur, followed by granulating and drying the product | 2

The disadvantage of this method is the low strength and nonuniformity of graule, which is considered in the processing of carbonate-containing phosphate.

In the chain of the invention 5, the strength of the double superphosphate granules is enhanced and the product of a uniform particle size distribution is obtained during the processing of carbonate-containing phosphate raw materials.

The goal is achieved by the fact that in a known method consisting in the decomposition of phosphate phosphoric acid in the presence of a retur, followed by granulation and drying of the product, the carbonate-containing phosphate phosphate is pre-mixed for 3-10 minutes with a retur, taken in an amount of 1-30 parts by weight . on 1 weight. phosphate.

At the same time, the DF-70% SOL containing in natural phosphate is released into the gas phase, which contributes to an increase in uniformity (odds-to-od ratio of at least 55%) and granule strength (from 5-15 to 25-30 kg / cm)

Example. 100 weight.h. Kingisepp phosphate (29% PgO and 8% CO2) in

For 7 minutes, handle 800 weight, h. retour containing%: 44.2 Pt 05 .: 9.5 1. 4.5 0.3 COj. .11 get 895 weight. including mass of the composition,%: 45.3 R SOBS f

4, 7 SOL, which is fed to a drum granulation dryer, where 80 parts by weight are introduced using a spray bottle. (in terms of F OJ phosphoric acid concentration of 40-50%, maintaining the temperature of the mixture in the apparatus at the level of 105-120 C. Phosphoric acid is served on a curtain of small granules formed during the NX cascade falling from the lifting blades of the dryer. Treading the material in the dryer 2O min, Get the product composition,%: 47 1 CV;

  ® Р% воб / А О, 3 СС. At the same time, its granulometric composition is characterized by the following parameters: 84% of the granules pass through a sieve with a diameter of 5 mm, 50% through a sieve of 3 mm and 16% through a sieve of 1 mm (67% grain size uniformity). Then the product is classified and 8OO wt.h. the retour is returned to the offset with phosphorite, and 210 weight. h, marketable product is neutralized with metaphorium ammonia g to a free acidity of 2-5% (p calculated as RL O). Cooled to

2O-4O With granules of the chain product

characterized by strength not steHee 25 kg / cm.

Comparative tests of the proposed method and the known method have shown that the strength of the granules increases 2-5 times, and their uniformity 1.5-2 times.

Claims (2)

1. USSR author's certificate No. 181665, cl. From 05 to 1/04, 1965 2. The patent of France No. 1140368, class, From 05 to 1/04, 1957.