Method for preparing phosphogypsum whiskers by secondary crystallization

A technology of phosphogypsum whiskers and secondary crystallization, applied in chemical instruments and methods, single crystal growth, crystal growth, etc., can solve the problem of short aspect ratio of phosphogypsum whiskers, difficult to succeed without pretreatment, difficult to produce, etc. The problem is to achieve the effect of good solid-liquid ratio, reasonable reaction temperature and stirring speed, and reasonable design.

Inactive Publication Date: 2014-03-12
GUIZHOU KAILIN GRP CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for preparing phosphogypsum whiskers by secondary crystallization, which solves the problem of short aspect ratio, low yield, difficult production under non-high pressure conditions, and difficulty in producing phosphogypsum whiskers without pretreatment in the prior art. success question

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  • Method for preparing phosphogypsum whiskers by secondary crystallization

Examples

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Comparison scheme
Effect test

Embodiment 1

[0032] (1) Primary crystallization:

[0033] Weigh 10g of dried phosphogypsum, add a sulfuric acid solution with a mass fraction of 8% according to the ratio of solid to liquid ratio 1:100, place it in a water bath with a water bath temperature of 80°C, stir and react at a speed of 250r / min, and react for 30min Finally, filter while it is hot, discard a small amount of insoluble matter, and cool the filtrate to crystallize at room temperature. After suction filtration, the filter cake is calcium sulfate dihydrate.

[0034] (2) Secondary crystallization:

[0035] Weigh 10g of calcium sulfate dihydrate obtained in one crystallization, add 8% sulfuric acid solution with a mass fraction of 8% according to the solid-to-liquid ratio of 1:100, and add 5% crystal aid magnesium sulfate, and place it in a water bath with a water bath temperature of 80°C Stir the reaction in a pot at a speed of 250r / min. After the solid is completely dissolved, keep the temperature constant for 30 minut...

Embodiment 2

[0037] (1) Primary crystallization:

[0038] Weigh 100g of dried phosphogypsum, add a sulfuric acid solution with a mass fraction of 10% according to the ratio of solid to liquid ratio 1:100, place it in a water bath with a water bath temperature of 90°C, stir and react at a speed of 250r / min, and react for 45min Finally, filter while it is hot, discard a small amount of insoluble matter, and cool the filtrate to crystallize at room temperature. After suction filtration, the filter cake is calcium sulfate dihydrate.

[0039] (2) Secondary crystallization:

[0040] Weigh 100g of calcium sulfate dihydrate obtained in one crystallization, add 10% sulfuric acid solution with a mass fraction of 10% according to the solid-to-liquid ratio of 1:100, and add 10% crystallization aid magnesium chloride, and place it in a water bath with a water bath temperature of 90°C Stirring reaction in medium temperature, rotating speed 250r / min, after the solid is completely dissolved, keep the tem...

Embodiment 3

[0042] (1) Primary crystallization:

[0043] Weigh 1000g of dried phosphogypsum, add sulfuric acid solution with a mass fraction of 15% according to the ratio of solid to liquid ratio of 1:100, put it in a water bath with a water bath temperature of 100°C, stir and react at a speed of 250r / min, and react for 60min Finally, filter while it is hot, discard a small amount of insoluble matter, and cool the filtrate to crystallize at room temperature. After suction filtration, the filter cake is calcium sulfate dihydrate.

[0044] (2) Weigh 1000g of calcium sulfate dihydrate obtained in the first crystallization, add a sulfuric acid solution with a mass fraction of 15% according to the solid-to-liquid ratio of 1:100, and add 15% crystallization aid magnesium sulfate, and place it in a water bath at a temperature of 100 Stir the reaction in a water bath at ℃, with a rotation speed of 250r / min. After the solid is completely dissolved, keep the temperature constant for 60 minutes, sto...

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Abstract

The invention discloses a method for preparing phosphogypsum whiskers by secondary crystallization. The method comprises the steps of weighing dried phosphogypsum, adding a sulfuric acid solution, performing stirring reaction in a water bath, filtering when being hot, abandoning insoluble substances, cooling filtrate at room temperature for crystallization, performing suction filtration, and then retaining a filter cake; adding the sulfuric acid solution and a crystallization promoting agent, namely magnesium salt, performing stirring reaction in the water bath, naturally cooling the solution in the water bath for crystallization, performing suction filtration to obtain the whiskers, washing till neutrality and drying. The crystallization promoting agent is not used in primary crystallization in the method disclosed by the invention, the solid-liquid ratio of raw materials has a good effect, the reaction temperature and the stirring rotational speed are reasonably designed, the secondary crystallization method is created, the problems of short length-diameter ratio, low yield, difficulty in production under non-high pressure conditions and difficulty in succeeding without pretreatment of the phosphogypsum whiskers in the prior art are solved, the problems of phosphorus residue and the like can be solved by recycling a solvent, and the sustained cyclic production can be further realized. The length-diameter ratio of the whiskers produced by the method disclosed by the invention is more than 100, the whiteness is not less than 95%, and the product yield is improved by 10%-15%.

Description

technical field [0001] The invention relates to a method for preparing phosphogypsum whiskers by secondary crystallization. Background technique [0002] For every 1 ton of phosphoric acid produced in my country, 4.5-5 tons of phosphogypsum will be discharged. Phosphogypsum is divided into dihydrate gypsum (CaSO 4 2H 2 O) and hemihydrate gypsum (CaSO 4 1 / 2H 2 O), mostly gypsum containing two waters. At present, the total annual output of wet-process phosphoric acid in the world is about 270 million tons (in P 2 o 5 Calculated), the by-product phosphogypsum is about 150 million tons, and the utilization rate is only 4.3% to 4.6%. It is estimated that the demand for phosphate fertilizer in my country will exceed 130 million tons in 2015, and the annual discharge of phosphogypsum will exceed 20 million tons, of which the utilization rate is only about 5%. The natural stacking of phosphogypsum has become the main treatment method, which not only costs a lot of money and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/46C30B29/62C30B7/10
Inventor 廖吉星张意赵井腥熊陈杰朱飞武
Owner GUIZHOU KAILIN GRP CO LTD
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