Calcining defluorination method in feed-grade tricalcium phosphate production

Abstract

The invention discloses a calcining defluorination method in feed-grade tricalcium phosphate production. According to the method, phosphoric acid is added to dry rock phosphate and sodium salt and the materials undergo granulation in a disk granulating machine; the granulated materials enter a rotary calcining kiln from the tail part; primary air and secondary air are introduced into the kiln head of the rotary calcining kiln so as to support combustion of fuel in the combustion section, and the materials undergo countercurrent calcining in the combustion section of the rotary calcining kiln; a steam pipeline extends into the kiln, steam which accounts for 10-60% of content of the total materials is added according to content of the materials and content of fluorine in the raw materials during calcining, and letting the steam fully react with the materials to take away the fluorine in the form of HF from the materials by tail gas. After the calcining, mass fraction of the fluorine in the materials is less than 0.18%. The method is simple, convenient and stable to operate, and no defluorination agent is added. Cost is low, and content of fluorine in the product can be effectively reduced. In the production, steam can be adjusted according to the content of fluorine in the materials. The method is easy to control, and the content of fluorine in the product is stable. The method is an ideal defluorination technology for the feed-grade tricalcium phosphate production.

Description

technical field [0001] The present invention relates to phosphate, especially to calcium phosphate, and further to a production method of tricalcium phosphate. Background technique [0002] As we all know, defluorination is the most important process in the production process of feed grade tricalcium phosphate; the traditional defluorination process of feed grade tricalcium phosphate is mainly to add defluorinating agent to the raw material, and then put it into the rotary kiln for high temperature calcination defluorination. Due to the high calcination temperature, it is difficult to control the temperature during production operation; when the system is turned on and off, the temperature fluctuates greatly, the defluorination effect is unstable, and unqualified products are likely to be produced; at the same time, the defluorination agent is relatively expensive, so the production cost is high. These factors are the main reasons why the production of feed grade tricalcium ...

AI Technical Summary

Problems solved by technology

Although these methods can produce feed grade tricalcium phosphate, they still have the defects of unstable product quality, high production cost and low output.

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