Method and system for preparing phosphoric acid

Abstract

The invention provides a method and system for preparing phosphoric acid.The method for preparing phosphoric acid includes the steps that phosphate ore, a reducing agent and a catalyst are mixed to obtain a mixed material; the mixed material is subjected to pelletizing treatment to obtain a globular material; the globular material is dried to obtain a dried globular material; the globular material is subjected to a reduction reaction inside a heat storage type rotary hearth furnace to obtain phosphorus-containing smoke and furnace slag; the phosphorus-containing smoke is subjected to an oxidation reaction to obtain phosphorus pentoxide steam; the phosphorus pentoxide steam reacts with water to obtain phosphoric acid.By the utilization of the method, the preparation efficiency and quality of phosphoric acid can be effectively improved.

Description

technical field [0001] The invention relates to the field of chemical industry. In particular, the present invention relates to methods and systems for producing phosphoric acid. Background technique [0002] The main methods of industrial production of phosphoric acid include wet purification phosphoric acid, thermal phosphoric acid and kiln phosphoric acid. Phosphoric acid is obtained by decomposing phosphate rock powder with sulfuric acid, which is called wet-process phosphoric acid; the phosphate rock is reduced with coke in an electric furnace to obtain yellow phosphorus, and then the yellow phosphorus is oxidized in another device to obtain phosphorus pentoxide (P 2 o 5 ), phosphoric acid is obtained by hydration, which is called electrothermal phosphoric acid. In recent years, domestic wet-process phosphoric acid production enterprises no longer only produce acid for phosphate fertilizers, but have begun to carry out wet-process acid purification, and further devel...

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Problems solved by technology

[0004] 1. The roasting time is long, generally 1.5-3 hours, or even longer, and the fuel cost is high;

[0005] 2. The ring bottom kiln is used. Since the phosphate rock realizes the reduction and oxidation reaction in the ring bottom kiln at the same time, the pellets must be covered with a film to prevent the re-oxidation of phosphorus in the phosphate rock, which not only affects the heat transfer of the pellets to a certain extent Efficiency and breathability, while increasing the process cost of the "cover film";

[0006] 3. Using a rotary kiln, the material balls are turned and rotated in the kiln, which will inevitably produce collisions and frictions, resulting in powder. On the one hand, it will affect the reduction of materials, and on the other hand, it will cause the kiln wall to stick, resulting in the inevitable " "ring" phenomenon, the furnace must be shut down for maintenance, affecting the normal operation of production

[0007] 4. Using coke as a reducing agent, the use is limited in areas lacking coke

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