Static multistage melting crystallization method for preparing electronic grade phosphoric acid

An electronic grade phosphoric acid, melt crystallization technology, applied in phosphorus compounds, chemical instruments and methods, inorganic chemistry and other directions, can solve the problems of high production cost, long operation time, high purity requirements, etc., and achieve good market prospects and industrialization value, Mild operating conditions and high product purity

Inactive Publication Date: 2011-09-28
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method operates at extremely low temperature, consumes a lot of energy, and requires pretreatment of raw materials to remove arsenic. The operation time is long, the production cost is high, and the yield is low.
[0011] Chinese patent 201010100473.0 uses flow chromatography crystallization method to prepare high-purity phosphoric acid, and adopts external sound field to crystallize, which requires extremely high purity of raw materials (the concentration of main impurity ions is less than 1.7mg / L, and requires microporous membrane filtration), so it is difficult to apply Larger, not easy to industrialize
However, the concentration of Na, Al, Mg, Cr and other ions in the electronic grade phosphoric acid prepared by this method is relatively high (1.79mg / L, 0.94mg / L, 0.49mg / L, 0.37mg / L), which cannot meet the needs of users who are increasingly updating still needs to be further improved

Method used

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  • Static multistage melting crystallization method for preparing electronic grade phosphoric acid
  • Static multistage melting crystallization method for preparing electronic grade phosphoric acid
  • Static multistage melting crystallization method for preparing electronic grade phosphoric acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Close the valve at the bottom of the crystallization tower, and place 2400 g of raw material food-grade phosphoric acid liquid (the content of metal ion impurities as shown in Table 1) in the crystallization tower at one time. Cooling water was passed through the jacket of the crystallization tower, the raw material was cooled to 21.5°C, and 10 g of solid seed crystals were added to the feed liquid of the crystallization tower at a constant temperature, and dispersed evenly.

[0041] Continue to feed the cooling medium, lower the temperature at a rate of 6°C / h, and the crystals grow uniformly into crystal columns inside the crystallization tower. Cool down to 10°C to reach the primary crystallization temperature, discharge 1 / 2 of the uncrystallized mother liquor 586g after constant temperature for 30 minutes, and measure the quality of the mother liquor by the weighing device at the bottom of the tower. Then close the valve, pass hot water through the jacket of the crys...

Embodiment 2、3、4

[0047] Close the valve at the bottom of the crystallization tower, and place 2400 g of raw material food-grade phosphoric acid liquids of different mass concentrations (the metal ion impurity content is as shown in Table 3) in the crystallization tower at one time. Cool the raw materials to an appropriate temperature, add the pre-prepared seed crystals into the crystallization tower feed liquid, and disperse evenly. Then start the operation of step-by-step material cooling crystallization-constant temperature-discharging part of the mother liquor-heating melting-constant temperature, the specific parameters are shown in Table 2. The material temperature operating curve of the process is as follows figure 2 , 3 , 4 shown. The test results of raw materials and products are shown in Table 3.

[0048] Table 2 One-time static multi-stage melting and crystallization operating parameters

[0049]

[0050] Table 3 Raw material phosphoric acid, test results of one static multi-...

Embodiment 5

[0054] Close the valve at the bottom of the crystallization tower, and place 3000 g of food-grade phosphoric acid liquid with a mass concentration of 83% (the content of metal ion impurities as shown in Table 4) in the crystallization tower at one time. Cool the raw material to 15°C, add 100 g of pre-prepared seed crystals into the feed liquid, and disperse evenly.

[0055] Continue to feed the cooling medium and start to lower the temperature at a rate of 4°C / h, and the crystals grow uniformly into crystal columns inside the crystallization tower. Cool down to 6°C to reach the primary crystallization temperature, discharge 1 / 4 of the uncrystallized mother liquor 450g after constant temperature for 60min, and measure its mass by the weighing device at the bottom of the tower. Then close the valve, raise the temperature at a rate of 6°C / h to the primary melting temperature of 12°C for 15 minutes, then continue to cool down at a rate of 4°C / h to the secondary crystallization tem...

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Abstract

The invention provides a static multistage melting crystallization method for preparing electronic grade phosphoric acid. The method comprises the following steps of: adding phosphoric acid liquid serving as a raw material into a crystallization tower at one time, and introducing a cooling/heating medium to a crystallization tower jacket to control the temperature of the phosphoric acid liquid; adding crystal seeds into the crystallization tower at constant temperature when the phosphoric acid liquid is cooled to the temperature of between 15 and 28 DEG C; and performing static melting crystallization operations of two to four stages by the following steps of: cooling and crystallizing the materials, discharging partial mother solution at constant temperature, heating and melting to the constant temperature, continuously performing the operation of next stage at the temperature, and gradually discharging the mother solution for N times in equal mass to gradually improve the purity of the phosphoric acid crystal. Finally, the left crystal in the tower is the product, and the crystal is melted by heating and collected. The method is simple in operation, low in energy consumption and mild in operating conditions; the product has high purity; an 88 to 90 percent electronic grade phosphoric acid liquid product is directly obtained; and the product purity index accords with multiple standards of domestic and foreign users.

Description

technical field [0001] The invention belongs to the technical field of crystallization, and in particular relates to the preparation of electronic-grade phosphoric acid by a static multistage melting crystallization method. Background technique [0002] Electronic-grade chemicals generally refer to special-purpose chemicals that are matched with the electronics industry. The requirements for the content of impurity ions are much higher than those of food-grade and industrial-grade chemicals. High-purity electronic-grade phosphoric acid is one of the series of electronic chemicals. With the large-scale transfer of international semiconductor chip (IC) and liquid crystal and other electronic industry manufacturing industries to China, my country's electronic technology industry, especially the etching and cleaning process and thin film-liquid crystal manufacturing process in the fine processing of semiconductor devices and integrated circuits, has a significant impact on electr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/234
Inventor 王静康姜晓滨侯宝红张美景尹秋响鲍颖王永莉龚俊波
Owner TIANJIN UNIV
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