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Phosphoric acid purification and arsenic removal process

A phosphoric acid and process technology, applied in phosphorus compounds, inorganic chemistry, chemical instruments and methods, etc., can solve the problems of only downgraded use, increased safety control difficulty, increased risk of hydrogen sulfide leakage, etc. Risk reduction, viscosity reduction effect

Pending Publication Date: 2022-07-29
WENGFU (GRP) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because this process involves the addition of sodium sulfide in the two stages of the pretreatment process and the extraction and purification process, the risk of hydrogen sulfide leakage increases and the difficulty of safety control increases. The food acid and arsenic index of the section does not meet the food-grade phosphoric acid standard and can only be downgraded for use

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] A process for purifying and removing arsenic with phosphoric acid, comprising the steps:

[0017] 1) In the wet phosphoric acid purification pretreatment process, sodium sulfide is added to phosphoric acid. The amount of sodium sulfide added is 1.2 times the arsenic equivalent in phosphoric acid. Sodium sulfide reacts with phosphoric acid to generate hydrogen sulfide and reacts with arsenic in phosphoric acid. Pretreatment desulfurization and defluorination residues produce co-precipitation, and after filtration and separation, the acid is removed and enters the extraction and purification process;

[0018] 2), in the extraction and purification process, phosphoric acid is contacted with the unloaded extractant in reverse phase, the impurities in the phosphoric acid are brought into the raffinate acid, and the phosphoric acid after the extraction and purification enters the organic phase and becomes the extraction load solvent;

[0019] 3) The extraction load solvent en...

Embodiment 2

[0024] A process for purifying and removing arsenic with phosphoric acid, comprising the steps:

[0025] 1) In the wet phosphoric acid purification pretreatment process, sodium sulfide is added to phosphoric acid. The amount of sodium sulfide added is 1.2 times the arsenic equivalent in phosphoric acid. Sodium sulfide reacts with phosphoric acid to generate hydrogen sulfide and reacts with arsenic in phosphoric acid. Pretreatment desulfurization and defluorination residues produce co-precipitation, and after filtration and separation, the acid is removed and enters the extraction and purification process;

[0026] 2), in the extraction and purification process, phosphoric acid is contacted with the unloaded extractant in reverse phase, the impurities in the phosphoric acid are brought into the raffinate acid, and the phosphoric acid after the extraction and purification enters the organic phase and becomes the extraction load solvent;

[0027] 3) The extraction load solvent en...

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PUM

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Abstract

The invention discloses a phosphoric acid purification and arsenic removal process which comprises the following steps: (1) in a wet-process phosphoric acid purification pretreatment process, sodium sulfide is added into phosphoric acid, the sodium sulfide reacts with phosphoric acid to generate hydrogen sulfide, the hydrogen sulfide reacts with arsenic in the phosphoric acid, a reactant and pretreated desulfurization and defluorination residues produce co-precipitation, and clear acid enters an extraction and purification process after filtration and separation; (2) in the extraction and purification process, the phosphoric acid is in reverse-phase contact with a no-load extraction agent, impurities in the phosphoric acid are brought into raffinate acid, and the extracted and purified phosphoric acid enters an organic phase to become an extraction load solvent; (3) filtering the extraction loaded solvent in a precision filtering device; (4) enabling the precisely filtered extraction load solvent to enter a washing and reverse extraction unit to obtain reverse extraction acid; and (5) enabling the reverse extraction acid to pass through concentration, decoloration, fine defluorination and bleaching units of a post-treatment process to finally obtain food-grade phosphoric acid. By adopting the process disclosed by the invention, the risk of hydrogen sulfide leakage is effectively reduced, so that the reliability and stability of industrial operation are further guaranteed.

Description

technical field [0001] The invention relates to phosphoric acid purification, in particular to a phosphoric acid purification process for removing arsenic. Background technique [0002] Solvent extraction is the mainstream process for wet phosphoric acid purification. Fertilizer-grade phosphoric acid can be extracted and purified to produce food-grade phosphoric acid. Food-grade phosphoric acid has extremely strict requirements on the content of arsenic. The current national standard (GB1886.304-2020) requires that the content of arsenic in food-grade phosphoric acid be less than 0.5ppm. [0003] The current dearsenic technology is to add excess sodium sulfide to phosphoric acid in the wet phosphoric acid purification and pretreatment process, and the sodium sulfide reacts with phosphoric acid to generate hydrogen sulfide and arsenic in phosphoric acid. After separation by filtration, the clear acid enters the extraction and purification process, and the loaded solvent afte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/238C01B25/46
CPCC01B25/238C01B25/46
Inventor 吴邦文李红林田仁道
Owner WENGFU (GRP) CO LTD