Method for purifying wet-process phosphoric acid by crystallization

A technology of wet-process phosphoric acid and crystallization, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of high energy consumption and environmental pollution

Active Publication Date: 2007-04-25
天津天达联合工程技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] At present, the main raw material for the preparation of electronic-grade phosphoric acid is thermal phosphoric acid, and the production process of thermal phosphoric acid consumes a lot of energy and causes great environmental pollution. It will soon be replaced by wet-process phosphoric acid.

Method used

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  • Method for purifying wet-process phosphoric acid by crystallization
  • Method for purifying wet-process phosphoric acid by crystallization
  • Method for purifying wet-process phosphoric acid by crystallization

Examples

Experimental program
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Effect test

Embodiment 1

[0030] 600 g wet process phosphoric acid, P 2 O 5 Concentration 39.8%, add 5.4g CaO, 3.8g Na 2 S, 0.6 g of activated carbon and 0.6 g of diatomaceous earth, sealed and reacted for 2h. Suction filtration was separated to obtain 560 g of filtrate, P 2 O 5 Concentration 38.7%. The filtrate was heated and concentrated to 460 g, and NH was added with stirring. 3 5.3 g, the reaction temperature is 60~80 ℃, the reaction time is 0.5 hour, 1000 ml of isopropanol is added under rapid stirring, and the reaction is carried out for 10 minutes. The filtered residue was washed and dried to be used as fertilizer, and 20 ml of 20% NaOH solution was added to the mother liquor to stir and react, and the brine phase and the organic phase were separated after standing. The solvent in the organic phase was distilled to obtain 312 grams of acid solution, P 2 O 5 Concentration 55.2%; decolorized by activated carbon and concentrated to P 2 O 5 The concentration is 62% to obtain technical gra...

Embodiment 2

[0034] Embodiment 1 obtains 100 grams of phosphoric acid, P 2 O 5Concentration 63.9%, introduce 2.0 grams of crystallization agent at 15°C, keep the stirring speed at 200r.p.m, cool down to 5°C, operate for 5.0h, separate by suction filtration, and use 10 grams of next-stage crystallization mother liquor with a mass concentration of 80% for the filter cake Wash to obtain 47.6 grams of product, which can be used in the electronics industry after melting and dilution, and the composition is listed in Table 2. This step crystallization operation P 2 o 5 The mass yield is 49.0%, and the mother liquor and washing liquid are mixed with the aforementioned food-grade purification acid.

Embodiment 3

[0036] Embodiment 2 gets phosphoric acid 45 grams, P 2 o 5 Concentration 63.9%, introduce 0.9 g of crystallization agent at 10°C, keep the stirring speed at 160r.p.m, cool down to 2°C, operate for 6.0h, separate by suction filtration, and wash the filter cake with 5 g of high-purity phosphoric acid with a mass concentration of 80%. Obtain product 21.0 grams, melt and dilute to obtain high-quality electronic grade phosphoric acid, composition is also listed in Table 2. This step crystallization operation P 2 o 5 The mass yield is 48.6%, and the mother liquor and washing liquid are mixed with the aforementioned qualified electronic-grade purification acid.

[0037] Table 2 Material flow composition (%)

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Abstract

The invention relates to the process for purifying purifying phosphoric acid through crystallization process, which comprises pre-processing the raw material acid, precleaning with solvent precipitation method, concentrating the obtained phosphoric acid to 85-90% and carrying out crystallization operation at 8-20 deg. C, introducing seed crystal 1-3 wt% of the total acid liquor quality, disintegrating, scouring and diluting the crystal, fluxing the obtained crystal, diluting to 85-90% and carrying out recrystallization, third crystallization, finally separating, washing and diluting the crystal product.

Description

technical field [0001] The invention relates to the technical field of crystallization, in particular to a method for purifying wet-process phosphoric acid by a crystallization method. Background technique [0002] Impurities in wet-process phosphoric acid are quite high, mainly sulfates, organic compounds, arsenic and other metal ions in varying amounts. These impurities originate from phosphate rock and sulfuric acid used in the production process. Wet-process phosphoric acid must effectively reduce the content of these impurities before it can be used in various industries such as industry, food additives, medicine, and electronics. The current refining methods mainly include extraction, ion exchange, crystallization and so on. [0003] Compared with several other methods, the crystallization method has simple equipment, low energy consumption, little pollution during operation, and the obtained product has high purity and good color. Therefore, since the 1980s, the re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/234
Inventor 卫宏远
Owner 天津天达联合工程技术有限公司
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