Method for production of granular calcium dihydrogen phosphate by one-time granulation of concentrated phosphoric acid

Abstract

Relating to the technical field of production of feed grade calcium dihydrogen phosphate, the invention discloses a method for production of feed grade granular calcium dihydrogen phosphate from wet-process defluorinated concentrated phosphoric acid. The method includes the steps of: S1: subjecting concentrated phosphoric acid with a phosphorus pentoxide content of 45-55wt% and a calcium carbonateemulsion to mixed reaction in a reactor to produce a mixed slurry containing calcium dihydrogen phosphate, wherein the calcium carbonate emulsion and concentrated phosphoric acid are proportioned according to a Ca / P ratio of 0.58-0.68, the reaction temperature is 60-80DEG C, the stirring speed of the reactor is 80-120 rpm, and the reaction time is 3-5min; S2: feeding the mixture slurry produced in S1 and the returned material together into a mixing granulator continuously for granulation so as to produce feed grade granular calcium dihydrogen phosphate wet semi-finished product; S3: sending the feed grade granular calcium dihydrogen phosphate wet semi-finished product in S2 into a drying machine for drying; and S4: screening the dried finished product output from the drying machine in S3to obtain a calcium dihydrogen phosphate finished product, crushing the tailing left by screening and then retuning the crushed tailing as the returned material to S2 for mixing granulation.

Description

technical field [0001] The invention relates to the technical field of producing feed grade calcium dihydrogen phosphate, in particular to a method for producing granular calcium dihydrogen phosphate by granulating concentrated phosphoric acid at one time. Background technique [0002] Feed grade calcium dihydrogen phosphate is an excellent high-efficiency phosphate feed additive, with high phosphorus content and high water solubility, and is an excellent supplement for phosphorus and calcium for animals. It has the highest biological value among feed-grade phosphates, and is especially suitable for fish and shrimp aquatic animals. The utilization rate of calcium dihydrogen phosphate phosphorus in fish and shrimp is as high as 94-98%, while the utilization rate of phosphorus in calcium hydrogen phosphate is only 50%, so feed grade calcium dihydrogen phosphate plays an important role in the development of aquatic products, and this variety of feed additive has been widely use...

AI Technical Summary

Problems solved by technology

This method has a long production process. Due to the high viscosity of the material, all equipment in contact with the material cannot be produced for a long period of time, and the device capacity cannot be enlarged.

[0007] The above three methods produce powdery calcium dihydrogen phosphate products. To obtain granular calcium dihydrogen phosphate products, the powdery products can only be obtained by granulating and sieving again. The process is long and the energy consumption is high.

[0008] In order to improve the above-mentioned technical problems, a method for producing granular calcium dihydrogen phosphate is disclosed in the patent CN105217592A, which uses 40-45% wet-process phosphoric acid to react with calcium carbonate powder, granulates and sieves after drying to obtain granular calcium dihydrogen phosphate , although this method shortens the production process to a certain extent and reduces energy consumption, there are still two problems: one is that when phosphoric acid reacts with calcium carbonate powder, it takes a long time to infiltrate calcium carbonate powder, and at the same time it may The powdered calcium carbonate will be wrapped, resulting in insufficient reaction and low water-soluble phosphorus in the product. To make the product’s water-soluble phosphorus meet the national standard, it is necessary to increase the consumption of phosphoric acid; a small part of the powdered calcium carbonate becomes dust during the reaction process, which affects on-site production Second, in this method, the semi-finished product is first dried into a powder with low moisture content, and then the product is granulated. During the granulation process, water or binders need to be added, and the secondary granulation technology is used. , prolong the production line, increase the energy consumption of the product and the dust in the production process, etc.

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