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Method for preparing electronic grade phosphoric acid by fusion crystallization method

An electronic-grade phosphoric acid, melt crystallization technology, applied in phosphoric acid, phosphorus oxyacids, chemical instruments and methods, etc., can solve the problems of insufficient product purity and high purity requirements of raw acid, and achieve low production energy consumption and high purity Wide-ranging, high-purity effects

Inactive Publication Date: 2006-10-11
朱健
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Russian patent 2209178 uses crystallization to purify thermal phosphoric acid, and the product meets the Russian CooTB Ty electronic industry phosphoric acid standard, but the purity of the resulting product does not reach the standard of FCC4 high-purity phosphoric acid; Japanese patents 3193614, 3237009 and 2000026111 use solution crystallization and melting The crystallization method further purifies electronic-grade phosphoric acid to obtain high-purity phosphoric acid with impurity content at the ppb level. However, this method has higher requirements on the purity of raw acid, which must have reached the level of electronic-grade phosphoric acid.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Put 500g of raw phosphoric acid (the composition is shown in Table 1) into a three-necked flask, and bubble hydrogen sulfide gas into the phosphoric acid at a temperature range of 50~70°C. After 50 minutes of reaction, bubble with air for 30 minutes, and put 5g of diatoms Soil, filter with suction, drop a few drops of hydrogen peroxide into phosphoric acid until clear. The contents of arsenic and sulfur in phosphoric acid after treatment are shown in Table 2.

[0030] material flow

[0031] raw acid

Embodiment 2、3、4

[0033] Put 500g of raw material phosphoric acid of a given concentration (thermal process industrial grade phosphoric acid I and wet purification industrial grade phosphoric acid II, see Table 1) in a hard glass container, and use a constant temperature bath to control its temperature, and use a peristaltic pump to Circulation of raw material phosphoric acid, using a two-layer cylindrical crystallization tube with an outer diameter of 2 cm and a length of 20 cm, is carried out according to the following operations and conditions. That is to soak the crystallization tube in the raw phosphoric acid, circulate the coolant (mixture of water and diol or industrial alcohol) with a predetermined supercooling temperature inside the soaking tube, and precipitate phosphoric acid hemihydrate crystals on the heat transfer surface of the crystallization tube. The specific operating conditions are listed in Table 1.

[0034] Example

[0035] After the above operations, take out th...

Embodiment 5、6、7

[0041] Obtain the phosphoric acid crystal layer after sweating in embodiment 2,3,4, use the phosphoric acid that the present invention obtains or the dilute acid that phosphoric acid mixes with pure water cleans crystal layer surface, after cleaning, crystal layer is all melted, sampling analysis, product impurity The content is shown in Table 6.

[0042] Example

[0043] All impurity contents of the present invention are analyzed and detected by an inductively coupled plasma emission spectrometer VISTA-MPX.

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PUM

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Abstract

The invention relates to a process for preparaing electronic phosphoric acid with melt crystallization method. It comprises following steps: removing arsenic from industrial phosphoric acid; heating crystal tube to minus two Deg. C to ten Deg. C; putting phosphoric acid of 21-28 Deg. C into crystal tube for circultion, the crystal layer growing to 2-4 cm; stewing crystal tube for 15-25 minutes and keeping the temperature, then heating crystal tube at speed of 2-5 Deg. C per hour, stopping when quality of melted crystal is 10-40% of thant of initial one; cleaning crystal layer with cleaning liquid with its tempeature near at temperature of fusible point of phosphoric acid hemi-crystalline. The certificated electronic phosphoric acid can be got after crystallization and perspiration; and electronic phosphoric acid of high purity reaching to FCC4 standard can be got after cleaning. The invention is characterized by high removal rate for foreign matter, low energy consumtion, wide range for treating raw material with different purity, high purity of geot product and sound economic benefit.

Description

technical field [0001] The invention relates to the technical field of crystallization, in particular to a method for purifying industrial-grade phosphoric acid to produce electronic-grade phosphoric acid by melting crystallization. technical background [0002] At present, there are mainly two production methods for phosphoric acid on the market. One is to use inorganic acid (mainly sulfuric acid) to react with phosphate rock, which is called wet phosphoric acid process. The other is to use charcoal in an electric furnace to reduce phosphate rock to elemental phosphorus, then oxidize the elemental phosphorus to phosphorus pentoxide and then react with water to prepare phosphoric acid, which is called dry phosphoric acid process. [0003] Phosphoric acid that can be used in the electronic semiconductor industry is generally dry-process phosphoric acid, because in comparison, the purity of dry-process phosphoric acid is higher than that of wet-pro...

Claims

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Application Information

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IPC IPC(8): C01B25/18C01B25/234
Inventor 朱健
Owner 朱健
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