Phosphoric acid desulfurization method applied to the production process of feed grade calcium hydrogen phosphate

Abstract

The invention discloses a phosphoric acid desulphurization method used in a feed grade calcium hydrogen phosphate production technology. The method comprises the following steps: 1, adding phosphate rocks to phosphoric acid to carry out pre-extraction and desulphurization; 2, conveying a slurry obtained after a complete reaction to a cyclone, and carrying out solid-liquid separation; 3, allowing cyclone underflow to enter an extraction tank after the solid-liquid separation, extracting the cyclone underflow, allowing an overflowing slurry to enter a settlement device, and settling the overflowing slurry; and 4, allowing a clear liquid obtained after settlement to enter a defluorination process, allowing a thick slurry obtained after settlement to enter the extraction tank, extracting the thick slurry, and circulating step 2 to step 4. The method has the advantages of ingenious design, stable thick slurry volume and denseness, no influences of re-extraction of the desulphurized thick slurry on the slurry filtering effect, low cost, satisfactory improvement of the contradiction of phosphoric acid desulphurization and the filtering effect, and realization of depth desulphurization.

Description

technical field [0001] The invention relates to the technical field of food processing, in particular to a phosphoric acid desulfurization method applied to the production process of feed-grade calcium hydrogen phosphate. Background technique [0002] The production of wet-process phosphoric acid uses phosphate rock and sulfuric acid to extract and filter to obtain phosphoric acid. Due to the needs of extraction conditions, the filtered phosphoric acid also contains some sulfate radicals (usually the free SO in phosphoric acid is extracted 3 Content 20-40g / l), so when phosphoric acid is defluorinated with calcium source, the higher the sulfate ion content, the lower the phosphorus yield in the defluorination process; otherwise, the higher the phosphorus yield in the defluorination process. At the same time, if more sulfate radicals are not removed and brought into the product, the quality of the product will decline. It can be seen that it is very important to reduce the su...

AI Technical Summary

Problems solved by technology

[0005] 1. The calcium sulfate crystals in this kind of thick slurry stay in the low temperature and low sulfate state for too long (the environment and conditions for the growth of calcium sulfate crystals are not obtained in time), and the crystal shape is still small after entering the extraction tank, resulting in the When the material is filtered, there will be problems such as difficulty in filtration, increase in water content, and decrease in washing rate (commonly known as "diarrhea")

[0006] 2. The effect of sedimentation and separation is poor. It is generally improved by increasing the amount of flocculant added and reducing the amount of ore pulp input, or by adding sedimentation equipment. It is not conducive to the digestion and treatment of the device, but in this way, the investment cost of the equipment will increase significantly, and the operation is cumbersome

[0007] 3. The discharge volume and consistency of thick slurry are not well controlled, resulting in unstable extraction operation indicators, increasing the difficulty of extraction operation, affecting the filtration effect and output, especially the decline in the quality of phosphate rock, the impact is more obvious

[0008] 4. The cleaning frequency of sedimentation equipment is high and difficult to clean