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Method for removing impurities from large-particle metallurgical silicon material

A technology for metal impurities and metallurgical silicon, which is applied in the field of removing metal impurities from large-particle metallurgical silicon materials, can solve the problems of secondary pollution of the surface of silicon materials, dust cannot be used for subsequent processes, excessive oxidation, etc., and achieves good metal impurities removal effect. , the effect of reducing energy consumption and avoiding dust

Inactive Publication Date: 2011-06-01
东海晶澳太阳能科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The object of the present invention is to provide a method for removing metal impurities in large-particle metallurgical silicon materials. This method does not need to deeply pulverize the silicon materials, avoids secondary pollution and excessive surface oxidation of silicon materials, and solves the problem that dust cannot be used for Follow-up process and other issues simplify the process equipment, reduce costs, increase environmental friendliness, and facilitate industrial application

Method used

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  • Method for removing impurities from large-particle metallurgical silicon material

Examples

Experimental program
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Effect test

Embodiment 1

[0023] HNO first 3 Wash the silicon material with a mixed acid of HF for 1-2 minutes, and then ultrasonically clean the silicon material with deionized water with a resistivity greater than 7MΩ·cm for 10-20 minutes to remove impurities on the surface of the silicon material, among which HNO in the mixed acid 3 The mole fraction of HF acid is 15-50%, and the mole fraction of HF acid is 1-5%. Then, the surface-cleaned silicon material is crushed and screened. The process of crushing and screening is to blast the metallurgical silicon water and put it into a pulverizer (including a ball mill and an electromagnetic separator inside) to pulverize for 2-3 times, and then use a sieve to screen out the particles. The diameter is 20-50 mesh powder. The silicon material whose particle size does not meet the requirements is crushed and screened again until the particle size of the silicon material meets the requirements. The metallurgical silicon material with a particle size of 20 mes...

Embodiment 2

[0029] Screen 30 mesh metallurgical silicon materials, and the test results of the silicon materials are as follows:

[0030] Fe(ppm)

Al(ppm)

Ca(ppm)

Cu(ppm)

Ni(ppm)

B(ppm)

P (ppm)

835.2

248.04

408.83

3.5

132

2.8

2.2

[0031] Clean the silicon material with pure water for 1min in the ultrasonic tank, dry it and put it into a high temperature furnace for heat treatment, at 50kPaAr50vol.%+N 2 Raise the temperature to 1150°C in a 50vol.% atmosphere, keep at this temperature for 10 hours, and then carry out acid leaching treatment at normal temperature and pressure after natural cooling. The mole fractions of each acid in the acid leaching agent are HF: 20%, HCl: 4%, HNO 3 : 0, the weight ratio of silicon material to acid leaching agent is 1:2, the acid leaching time is 10h, repeat the above operation 3 times, then wash and dry and send samples for testing.

[0032] The ICP-AES test results are as follow...

Embodiment 3

[0035] Screening 40 mesh metallurgical silicon materials, the implementation results:

[0036] Fe(ppm)

Al(ppm)

Ca(ppm)

Cu(ppm)

Ni(ppm)

B(ppm)

P (ppm)

427.8

96.4

419.57

4.9

34.3

6.8

40.9

[0037] Wash the silicon material with pure water in the ultrasonic tank for 1min, dry it and put it into a high-temperature furnace for heat treatment, heat it up to 1200°C in a 20kPa Ar atmosphere, keep it at this temperature for 15 hours, cool it naturally to normal temperature and pressure, and then carry out acid leaching treatment , the molar fractions of each acid in the acid leaching agent are HF: 40%, HCl: 4%: HNO 3 : 1%, the weight ratio of silicon material and acid leaching agent is 1:3, the acid leaching time is 36h, repeat the above operation 3 times, and then wash and dry.

[0038] The ICP-AES test results are as follows:

[0039] Fe(ppm)

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PUM

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Abstract

The invention discloses a method for removing impurities from a large-particle metallurgical silicon material, which is to select a metallurgical silicon material, make metal impurities disperse into the surfaces or grain boundary of silicon material particles through high temperature treatment, and remove the metal impurities by acid leaching to prepare high-purity silicon. The method obviates the need of deeply crushing the silicon material and therefore avoiding secondary pollution to the silicon material and the over oxidation of the surface; meanwhile, the method solves such problem that dust cannot be used in subsequent processes, simplifies process equipment, reduces cost, improves environmentally friendliness and is convenient for industrial application.

Description

technical field [0001] The invention belongs to the technical field of photovoltaics, and in particular relates to a method for removing metal impurities of large-particle metallurgical silicon materials. Background technique [0002] Metallurgical silicon is the primary raw material for the production of solar-grade silicon. Typical impurities include metal elements such as Fe, Al, and Ca, and non-metallic elements such as B and P. The impurity content is between 103ppm and 104ppm. When metallurgical silicon is used as a raw material for solar cells, these impurities will increase the recombination of photogenerated carriers at the silicon grain interface, thereby affecting the photoelectric conversion efficiency of solar cells. However, the impurity concentration in metallurgical silicon required by general solar cells is at least less than 1.0 ppm. Traditional purification methods include chemical purification and physical purification. The Siemens method is a typical c...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 黄新明刘付冠尹长浩温志辉
Owner 东海晶澳太阳能科技有限公司
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