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Preparation of Electronic Grade Phosphoric Acid by U-tube Static Multistage Melting Crystallization

An electronic-grade phosphoric acid, melt crystallization technology, applied in the field of phosphorus chemical industry, can solve the problems of long operation time, difficult application, high purity requirements, etc., and achieve high product recovery rate, good economic benefits, and high product purity.

Active Publication Date: 2016-06-08
GUANGXI MINGLI CHEM
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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.
[0005] Chinese patent 201010100473.0 discloses a method for preparing high-purity phosphoric acid by flow chromatography crystallization. This method uses flow chromatography crystallization to prepare high-purity phosphoric acid, and adopts an external sound field for crystallization, which requires extremely high purity of raw materials used (concentration of main impurity ions are all less than 1.7mg / L, and need microporous membrane filtration), the application is difficult, and it is 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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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A U-tube static multi-stage melt crystallization method to prepare electronic-grade phosphoric acid, using food-grade phosphoric acid liquid with a mass concentration of 86% and a temperature of 26°C as the raw acid. Add crystal seeds to the wall of the U-shaped crystallization tube by spraying to ensure that there are crystal seeds hanging on the wall. The dosage of the seed crystal is 0.5‰ of the weight of the raw material acid, and then the U-shaped crystallization tube is placed in the reaction tank, and the temperature of the U-shaped crystallization tube is filled with ice salt water at a temperature of -20°C, so that the crystal seed is firmly attached to the tube wall At last, the raw material acid is added to the reaction tank. When the ice brine cools the raw acid, the outer wall of the U-shaped tube begins to grow and form a crystal film. The U-shaped crystallization tube is continuously fed with -20°C ice salt water, and the crystals begin to grow outward f...

Embodiment 2

[0027] A U-tube static multi-stage melt crystallization method to prepare electronic-grade phosphoric acid, using food-grade phosphoric acid liquid with a mass concentration of 87% and a temperature of 28°C as the raw acid. Add crystal seeds to the wall of the U-shaped crystallization tube by spraying to ensure that there are crystal seeds hanging on the wall. The dosage of the seed crystal is 0.8‰ of the weight of the raw material acid, and then the U-shaped crystallization tube is placed in the reaction tank, and the temperature of the U-shaped crystallization tube is filled with ice salt water at a temperature of -15°C, so that the crystal seed is firmly attached to the tube wall At last, the raw material acid is added to the reaction tank. When the ice brine cools the raw acid, the outer wall of the U-shaped tube begins to grow and form a crystal film. The U-shaped crystallization tube is continuously fed with -15°C ice salt water, and the crystal begins to grow outward f...

Embodiment 3

[0029]A U-tube static multi-stage melt crystallization method for preparing electronic-grade phosphoric acid, using food-grade phosphoric acid liquid with a mass concentration of 88% and a temperature of 30°C as the raw acid. The seed crystal is added on the wall of the U-shaped crystallization tube by brushing to ensure that the crystal seed hangs on the wall. The dosage of the seed crystal is 1.0‰ of the weight of the raw material acid, and then the U-shaped crystallization tube is placed in the reaction tank, and the temperature of the U-shaped crystallization tube is passed into the ice salt water with a temperature of -10°C, so that the crystal seed is firmly attached to the tube wall At last, the raw material acid is added to the reaction tank. When the ice brine cools the raw acid, the outer wall of the U-shaped tube begins to grow and form a crystal film. The U-shaped crystallization tube is continuously fed with -10°C ice salt water, and the crystals begin to grow ou...

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PUM

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Abstract

The invention discloses a method for preparing an electronic-grade phosphoric acid by U-shaped pipe static multistage melt crystallization. The method comprises the following steps: by taking food-grade phosphoric acid liquid as material acid, adding a seed crystal to the wall of a U-shaped crystallization pipe; leading brine ice into the U-shaped crystallization pipe to cool the material acid; loading the material acid into a reaction tank, wherein the crystal begins to grow outwards from the surface of the U-shaped crystallization pipe; stopping leading and exhausting the brine ice inside the U-shaped pipe when the weight of a crystal layer achieves 30-40% of weight of the material acid, and discharging a liquid phase; stating a heating system so that the temperature inside the U-shaped crystallization pipe slowly ascends in a gradient manner; gradually melting the crystal layer, and carrying out four-stage sweating; finally adjusting the temperature and concentration of the phosphoric acid, so as to prepare the finished electronic-grade phosphoric acid. The method disclosed by the invention is simple in operation, low in energy consumption, high in product purity and high in product recovery rate, has better economic benefits, and is the production method which can meet the upgrade requirements of electronic-grade phosphoric acid products and has industrial application values.

Description

technical field [0001] The invention belongs to the technical field of phosphorus chemical industry, in particular to a U-shaped tube static multi-stage melting crystallization method for preparing electronic-grade phosphoric acid. Background technique [0002] Electronic-grade phosphoric acid belongs to high-purity phosphoric acid, which is widely used in microelectronics industries such as large-scale integrated circuits and thin-film liquid crystal displays (TFT-LCD). It is mainly used for cleaning and etching chips. , Conductivity and reliability have a great influence. The ones with lower purity are mainly used for cleaning liquid crystal panel components, and the ones with higher purity are mainly used for cleaning and etching in the production process of electronic chips. Since insoluble solid particles or metal ions may be in the The current is conducted between the tiny circuits to make it short circuit, so electronic grade phosphoric acid has strict requirements on...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/234
Inventor 林军吴小海苏杰文王文营
Owner GUANGXI MINGLI CHEM