Method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid

A technology of polyethylene glycol and silicon carbide, which is applied in the field of waste liquid recovery, can solve the problems of fluorine pollution, loss of use value, ineffective separation of silicon carbide and silicon, etc., to reduce the amount of addition, reduce the cost of environmental protection treatment, and improve the production process Proven and Reliable Effects

Inactive Publication Date: 2010-09-01
ZHEJIANG YUANSHENG SILICON MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method is easy to control, simple equipment, and low cost, but its existing problems are: one is that silicon carbide and silicon cannot be effectively separated; the other is that HNO 3 The mixed acid liquid treatment method composed of +HF is likely to c

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] Take 50 kilograms of silicon wafer cutting waste liquid, add 50 kilograms of water, stir, the mixture is ultrasonically treated, and the iron in the mixture is sucked out with a magnet; 0.03 kg of flocculant is added, and the solid is separated by a centrifugal separator after the reaction. 1. Solids and liquids. The second solid can be sold directly.

[0033] Take 10 kilograms of solid substance, add 10 kilograms of water to dilute to a silicon carbide suspension, add 30% by mass sodium hydroxide solution to the suspension to a pH of 12, and heat to 80°C to react. After the reaction is complete , Wash with water until the pH value reaches 7.5, then add 30% sulfuric acid solution by mass percentage to the pH value 3, and wash with water until the pH value reaches 7 to obtain the crude silicon carbide. A scraper centrifuge is used for separation, and the separated solids are heated and dried to a moisture content of not more than 0.4% to obtain silicon carbide products. I...

Embodiment 2

[0036] Take 50 kilograms of silicon wafer cutting waste liquid, add 100 kilograms of water, stir, the mixture is subjected to ultrasonic treatment, and the iron in the mixture is sucked out with a magnet; 0.05 kg of flocculant is added, and the solid is separated by a centrifugal separator after the reaction. 1. Solids and liquids. The second solid can be sold directly.

[0037] Take 10 kilograms of solid, add 15 kilograms of water to dilute it into a silicon carbide suspension, add 40% by mass sodium hydroxide solution to the suspension to a pH of 11, and heat to 90°C to react. After the reaction is complete , Wash with water until the pH value reaches 7, then add 25% hydrochloric acid solution by mass percentage to the pH value 1, and wash with water until the pH value reaches 6.5 to obtain the crude silicon carbide. A scraper centrifuge is used for separation, and the separated solid is heated and dried to a moisture content of not more than 0.5% to obtain a silicon carbide p...

Embodiment 3

[0040] Take 50 kilograms of silicon wafer cutting waste liquid, add 25 kilograms of water, stir, the mixture is subjected to ultrasonic treatment, and the iron in the mixture is sucked out with a magnet; 0.01 kg of flocculant is added, and after the reaction, a centrifugal separator is used for solid-liquid separation to obtain solids 1. Solids and liquids. The second solid can be sold directly.

[0041] Take 10 kilograms of solids, add 5 kilograms of water to dilute to a silicon carbide suspension, add 10% by mass sodium hydroxide solution to the suspension to a pH of 13, and heat to 60°C to react. After the reaction is complete , Wash with water until the pH value reaches 7, then add 20% sulfuric acid solution by mass percentage to the pH value 4, and wash with water until the pH value reaches 7 to obtain crude silicon carbide. A scraper centrifuge is used for separation, and the separated solids are heated and dried to a moisture content of not more than 0.3% to obtain silico...

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PUM

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Abstract

The invention discloses a method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid. The method comprises the following steps of: A) diluting the cutting waste liquid with water and stirring, extracting metal scarp iron from the mixture by using a magnet after ultrasonic processing; B) adding a flocculating agent into the mixture for centrifugal separation; C) diluting solid I with water, adding sodium hydroxide into the solution, heating the mixture to perform reaction, cleaning the mixture with the water, adding an acid into the mixture, and cleaning the mixture with the water to obtain a crude silicon carbide product; D) performing centrifugal separation on the crude silicon carbide product, and drying the crude product to obtain a finished silicon carbide product; and E) filtering the liquid, heating, evaporating and dehydrating the filtered liquid to obtain a finished polyethylene glycol product. In the scheme, the mixture is diluted first, so the recovery rate of the polyethylene glycol is improved. The silicon and iron content of the crude silicon carbide product and the consumption level of the acid and alkali are reduced by ultrasonic processing and iron removal. The method has the characteristics of reasonable process, environmental protection and the like.

Description

Technical field [0001] The invention relates to a waste liquid recovery method, more specifically a method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid. Background technique [0002] In the process of multi-wire cutting of silicon wafers, the main role of the cutting fluid is to disperse, suspend, lubricate, cool, improve cutting efficiency, and reduce cutting consumption. The main components of the existing silicon wafer cutting fluid are polyethylene glycol and silicon carbide. Therefore, the main components of the cutting waste liquid generated by the silicon wafer cutting are polyethylene glycol and silicon carbide, and also include a small amount of silicon chips (generally 2~ 5%) and trace metal iron. The existing recycling of polyethylene glycol and silicon carbide in the silicon wafer cutting waste liquid often has problems such as low recovery rate and low purity of the recycled polyethylene glycol and silicon carbide....

Claims

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Application Information

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IPC IPC(8): C01B31/36
Inventor 罗其洋陈云根
Owner ZHEJIANG YUANSHENG SILICON MATERIALS
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