A kind of hydrometallurgical purification process of polysilicon metal impurities by metallurgical method

A metal impurity and hydrometallurgy technology, applied in the direction of non-metallic elements, silicon compounds, chemical instruments and methods, etc., can solve the problems of polysilicon wet method without seeing public information, etc., and achieve the effect of large-scale production and low cost

Inactive Publication Date: 2011-12-28
宁夏银星多晶硅有限责任公司
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Problems solved by technology

How to wet-purify polysilicon to 4N level (ie 99.98-99.99%) has not yet seen relevant public information

Method used

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specific Embodiment approach

[0019] 1) Optimal particle size of silicon powder: metal impurities are enriched in crystal boundaries or gaps of silicon blocks during solidification and solidification of silicon, and metal impurities can be effectively removed only when the size of silicon particles is equal to or smaller than the grain boundaries. However, the smaller the size, the longer the precipitation time of silicon powder. The precipitation time of too fine silicon powder is even calculated in days, and it is slightly disturbed and suspended. It needs to be rinsed many times during the pickling process. Recovery costs, which seriously affect work efficiency and yield. According to the analysis of experimental data, the particle size of the silicon powder is preferably 100-200 mesh (150-74 μm), and it will be separated by a magnetic separator for future use.

[0020] 2) Appropriate pickling temperature: Most literatures report that the pickling temperature is set in the range of 40-80°C. Appropriatel...

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Abstract

The invention relates to the technical field of metallurgical polysilicon purification, in particular to a hydrometallurgical purification method. The purification method of the present invention is as follows: the silicon powder with a particle size of 100 to 200 meshes is subjected to magnetic separation by a magnetic separator for use, and is prepared by pre-cleaning, pickling with dilute hydrochloric acid, pickling with dilute hydrofluoric acid, pickling with aqua regia, and dilute hydrofluoric acid. Acid and hydrogen peroxide pickling process pickling, the solid-to-liquid ratio is 1:3, soak for 12-16 hours, stir for 15 minutes every hour during soaking, and then rinse with deionized water for many times until the pH value of the water For neutrality, centrifugal drying, drying, packaging. Using the purification method of the present invention, by optimizing the conditions such as silicon powder particles, acid concentration, soaking time and stirring, the total content of metal impurities in metallurgical polysilicon is reduced to 100ppmw in advance, and the effect of 4N purity metallurgical silicon can be obtained, and reach A simple, easy, low-cost method that can be mass-produced.

Description

technical field [0001] The invention relates to the technical field of metallurgical polysilicon purification, in particular to a hydrometallurgical purification method. Background technique [0002] Photovoltaic energy is one of the most important new energy sources in the 21st century. In recent years, the global photovoltaic industry has developed rapidly. In order to meet the rapid development of the photovoltaic industry, all countries in the world are committed to developing new preparation technologies and processes for solar-grade polysilicon with low cost and low energy consumption, such as improved Siemens method, new silane method, and fluidized bed law, metallurgy, etc. Among them, the metallurgical method to prepare solar-grade polysilicon is considered to be a production method that effectively reduces production costs and is specifically positioned for solar-grade polysilicon. [0003] At present, the technology of preparing solar-grade polysilicon by metall...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
Inventor 刘应宽盛之林李文革李峰宋冬梅刘永贵
Owner 宁夏银星多晶硅有限责任公司
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