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Method for preparing high-purity silicic acid at low cost

A low-cost, silicic acid technology, applied in the direction of silicon oxide, silicon dioxide, etc., can solve problems such as complex processes and achieve the effect of removing metal impurities

Inactive Publication Date: 2021-11-05
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Both of the above two methods use three ion exchange processes. Generally speaking, the process is more complicated, and there is still room for improvement in terms of cost and production cycle.

Method used

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  • Method for preparing high-purity silicic acid at low cost
  • Method for preparing high-purity silicic acid at low cost

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment 1: 15kg water glass (containing SiO 2 25%, SiO 2 : Na 2 O=3.3, the ratio of the number of molecules, the same below) was dissolved in 300kg of water, then 0.25kg of sodium chloride was added and stirred to dissolve. Pass this solution through a cation exchange column (packed with 732 resin), collect the liquid with pH<2, and obtain acidic silicic acid containing hydrochloric acid, pH=2.0. Pass the acidic silicic acid through an anion exchange column (filled with 717 resin), collect the liquid with pH<5.5, and obtain the finished silicic acid. The characterization results are shown in Table 1.

Embodiment 2

[0026] Embodiment 2: with 70kg water glass (containing SiO 2 25%, SiO 2 : Na 2 O=4.0) was dissolved in 300kg of water, and then 4.5kg of sodium nitrate was added and stirred to dissolve. Pass this solution through a cation exchange column (packed with 732 resin), collect the liquid with pH<2, and obtain acidic silicic acid containing nitric acid, pH=0.5. Pass the acidic silicic acid through an anion exchange column (filled with 717 resin), collect the liquid with pH<5.5, and obtain the finished silicic acid. The characterization results are shown in Table 1.

Embodiment 3

[0027] Embodiment 3: 60kg anhydrous sodium silicate solid (containing SiO 2 49.2%, SiO 2 : Na 2 O=1.0) was dissolved in 400kg of water, then 4.5kg of sodium perchlorate was added and stirred to dissolve. Pass this solution through a cation exchange column (packed with 732 resin), collect the liquid with pH<2, and obtain acidic silicic acid containing perchloric acid, pH=1.0. Pass the acidic silicic acid through an anion exchange column (filled with 717 resin), collect the liquid with pH<5.5, and obtain the finished silicic acid. The characterization results are shown in Table 1.

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Abstract

The invention relates to a method for preparing high-purity silicic acid at low cost. Sodium silicate or sodium silicate is used as a raw material, a certain amount of strong acid and strong alkali salt is dissolved in the raw material, and then cation exchange and anion exchange are carried out in sequence to obtain silicic acid with low impurity metal content. According to the method disclosed by the invention, the pH value of the solution is reduced by utilizing the strong acid generated in situ by acid radical ions of the strong acid during cation exchange, so that metal oxides such as aluminum oxide and iron oxide are converted into corresponding metal cations and are captured by ion exchange resin, and the purpose of removing metal impurities is achieved. The method is characterized in that the number of the times of the ion exchange is decreased to two from three, and the obtained silicic acid has low impurity metal ion content.

Description

technical field [0001] The invention belongs to the technical field of chemical industry and relates to a method for preparing high-purity silicic acid at low cost. Background technique [0002] Chemical Mechanical Polishing (CMP) is currently recognized as the best global planarization technology for silicon wafers in the IC process, and silica sol is the only available abrasive in the CMP polishing fluid for silicon wafers. With the continuous shrinking of the semiconductor feature size, the CMP process has higher and higher requirements on the metal content of the abrasive. This is because the impurity metal ions in the abrasive are easily adsorbed on the surface of the silicon wafer, resulting in a decrease in product performance and yield. [0003] At present, the techniques for preparing silica sol abrasives mainly include orthosilicate hydrolysis, ion exchange and silica powder. The ion exchange method has cheap raw materials, simple equipment and process, easy opera...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/12
CPCC01B33/12C01P2006/80
Inventor 高逸飞李洪深吕毅张剑
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH