Method for removing impurity of phosphorus from metallurgical grade silicon

A technology for metallurgical silicon and impurities, applied in chemical instruments and methods, silicon compounds, non-metallic elements, etc., can solve the problems of increased damage to vacuum equipment, long heating time, low energy utilization rate, etc., to achieve low energy consumption, Good effect, simple operation effect

Inactive Publication Date: 2010-01-20
JACO SOLARSI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Keep the heated ground silicon powder at this temperature for a long enough period of time to remove P and other impurities from metallurgical silicon, but this method requires finer silicon powder, w

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] This example shows the effect of using metallurgical silicon with different phosphorus P content as raw material on the phosphorus removal effect under the same process.

[0024] Commercially available additives (calcium oxide CaO, aluminum oxide Al 2 o 3 , silicon oxide SiO 2 , barium oxide BaO, high-purity C one or several combinations) according to the amount of 1% to 5% of the total weight of metal silicon block or silicon powder placed in the bottom of the crucible (quartz crucible or graphite crucible), self-produced or purchased Metal silicon blocks or silicon powders with phosphorus contents of 18ppm, 27ppm, 36ppm, and 50ppm are respectively placed on the upper part, and a vacuum intermediate frequency induction furnace is used to evacuate until it is stable at 5.0×10 -1 After the Pa is below, turn on the intermediate frequency power supply to heat gradually, and slowly heat when the silicon starts to melt, and heat it to 1450-1550°C after the silicon is compl...

Embodiment 2

[0029] What this example is going to illustrate is the influence of refining time on the effect of phosphorus removal during vacuum refining.

[0030] Place the commercially available additives at the bottom of the crucible (quartz crucible or graphite crucible) in the amount of 1% to 5% of the total weight of the metal silicon block or silicon powder, and place the metal silicon block or silicon powder with a phosphorus content of 18ppm in self-produced or purchased In the upper part, use a vacuum intermediate frequency induction furnace to evacuate until it is stable at 5.0×10 -1 After the Pa is below, turn on the intermediate frequency power supply and gradually heat it up. When the silicon starts to melt, heat it slowly. After the silicon is completely melted, heat it to 1450~1550℃. -2 The vacuum degree below Pa is treated separately.

[0031] Rows 1 to 4 of Table 2 list the refining time as 1 to 5 hours. It can be obtained from Table 2 that with the prolongation of the ...

Embodiment 3

[0035] This implementation case shows the effect of additives on phosphorus removal during vacuum refining.

[0036] Put the self-produced or purchased metal silicon block or silicon powder with a phosphorus content of 18ppm into a crucible (quartz crucible or graphite crucible), and use a vacuum intermediate frequency induction furnace to evacuate until it is stable at 5.0×10 -1 After the Pa is below, turn on the intermediate frequency power supply and gradually heat it up. When the silicon starts to melt, heat it slowly. After the silicon is completely melted, heat it to 1450~1550℃. -2 Refining below Pa for 3 hours. After testing, the phosphorus P content after treatment was 7ppm.

[0037] Compared with row 3 of Table 2, it is obtained that the phosphorus removal efficiency after adding additives is 38.5% higher than that without additives.

[0038] In summary, the test results after removing phosphorus P in the present invention show that phosphorus P≤0.1ppm. The key of th...

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PUM

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Abstract

The invention discloses a method for removing impurities of phosphorus from metallurgical grade silicon. The method comprises the following steps: taking massive or powdery metallurgical grade silicon as a raw material, adding an additive, of which the weight is 1 to 5 percent of that of the metallurgical grade silicon, to the bottom of a crucible, and vacuum-melting the mixture to remove the phosphorus. The method has the characteristics of easy operation, good environmental friendliness, low purification cost and low energy consumption. When the metallurgical grade silicon is processed by the method, the content of phosphorus P in the metallurgical grade silicon is less than or equal to 0.1ppm, namely the requirement of solar-class silicon on the content of phosphorus P is met.

Description

field of invention [0001] The invention relates to a process for purifying metallurgical silicon materials, in particular to a method capable of removing impurity phosphorus in metallurgical silicon, and belongs to the technical field of silicon industry. Background technique [0002] The shortage of solar-grade silicon materials has limited the rapid growth of the global photovoltaic industry, and the most mature polysilicon purification process is the Siemens method. Purification of polysilicon by the Siemens method needs to maintain a high temperature of 1100°C, so a large amount of electric energy is consumed, resulting in high costs. Moreover, this method also uses a large amount of chemicals, and the treatment of these drugs is also a major problem. In addition, the purity of polysilicon used to manufacture solar cells is only 5-6N, while the purity of silicon purified by the Siemens method is relatively high, resulting in waste of resources and energy. [0003] Purif...

Claims

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Application Information

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IPC IPC(8): C01B33/037
Inventor 罗晓斌
Owner JACO SOLARSI
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