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Method for purifying wet-process phosphoric acid by crystallization

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

Active Publication Date: 2006-02-08
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 5.4 grams of CaO, 3.8 grams of Na 2 S, 0.6 g of activated carbon and 0.6 g of diatomaceous earth, sealed and reacted for 2 h. Separation by suction filtration obtains 560 grams of filtrate, P 2 o 5 The concentration is 38.7%. The filtrate was heated and concentrated to 460 g, and NH 3 5.3 grams, the reaction temperature is 60-80°C, the reaction time is 0.5 hours, 1000ml of isopropanol is added under rapid stirring, and the reaction is 10 minutes. The filtered residue is used as fertilizer after being washed and dried, and 20ml of 20% NaOH solution is added to the mother liquor to stir and react, and after standing still, the brine phase and the organic phase are separated. The solvent in the organic phase is distilled out to get 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 industrial-grad...

Embodiment 2

[0035] Embodiment 1 gets phosphoric acid 100 grams, P 2 o 5 Concentration 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

[0037] 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.

[0038] Table 2 Material flow composition (%)

[0039]

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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 crystallization. Background technique [0002] The impurity content in wet-process phosphoric acid is quite high, mainly sulfates in varying amounts, organic compounds, arsenic and other metal ions. These impurities originate from phosphate rock and the 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 method, ion exchange method, crystallization method and so on. [0003] Compared with several other methods, the crystallization method has simple equipment, low energy consumption, less pollution in the operation process, and the obtained product has ...

Claims

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Application Information

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