Method for removing impurities in metallurgic silicon

A technology of metallurgical grade silicon and impurities, applied in the field of silicon purification, to achieve the effect of less acid consumption

Active Publication Date: 2016-11-16
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Gas blowing oxidation refining can also effectively remove boron in silicon, but due to the strong affinity between silicon and oxygen, how to reduce the loss of silicon remains to be solved

Method used

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  • Method for removing impurities in metallurgic silicon

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Effect test

Embodiment 1

[0022] Such as figure 1 As shown, a method for removing impurities in metallurgical grade silicon, the specific steps are as follows:

[0023] (1) Add Zr to industrial silicon (the amount of added Zr accounts for 10% of the total molar number of materials) and put it into a high-purity dense graphite crucible for melting. The melting temperature is 1723K, and the melting atmosphere is argon protective gas;

[0024] (2) Cool down the completely melted silicon melt in step (1) to room temperature at a rate of 20K / min;

[0025] (3) Grinding the silicon obtained in step (2) into silicon powder smaller than 186 μm;

[0026] (4) Pickling the silicon powder obtained in step (3) with aqua regia, HF+HCl mixed acid (the volume ratio of HF and HCl is 1:1) to obtain high-purity silicon, the pickling temperature is 323K, and the pickling time is 5h.

[0027] After step (4), the content changes of main impurity elements in silicon are shown in Table 1, where the added Zr is reduced from ...

Embodiment 2

[0032] Such as figure 1 As shown, a method for removing impurities in metallurgical grade silicon, the specific steps are as follows:

[0033] (1) Add Si-30at%Zr alloy to industrial silicon (the amount of Zr added accounts for 0.1% of the total molar number of materials) and put it into a high-purity dense graphite crucible for melting. The melting temperature is 1973 K and the melting atmosphere is Argon protective gas;

[0034] (2) Cool down the completely melted silicon melt in step (1) to room temperature at a rate of 0.1K / min;

[0035] (3) Grinding the silicon obtained in step (2) into silicon powder smaller than 186 μm;

[0036] (4) The silicon powder obtained in step (3) was pickled successively with aqua regia, HF+HCl mixed acid (the volume ratio of HF and HCl was 1:1) to obtain high-purity silicon. The pickling temperature was 353 K, and the pickling time was 0.5h.

[0037] After step (4), the content changes of main impurity elements in silicon are shown in Table...

Embodiment 3

[0042] Such as figure 1 As shown, a method for removing impurities in metallurgical grade silicon, the specific steps are as follows:

[0043] (1) Add Hf to industrial silicon (the amount of added Hf accounts for 10% of the total molar number of materials) and put it into a high-purity dense graphite crucible for melting. The melting temperature is 1803K, and the melting atmosphere is argon protective gas;

[0044] (2) Cool down the completely melted silicon melt in step (1) to room temperature at a speed of 10K / min;

[0045] (3) Grinding the silicon obtained in step (2) into silicon powder smaller than 186 μm;

[0046] (4) The silicon powder obtained in step (3) was pickled successively with aqua regia, HF+HCl mixed acid (the volume ratio of HF and HCl was 1:1) to obtain high-purity silicon. The pickling temperature was 333 K, and the pickling time was for 3h.

[0047] After step (4), the content changes of main impurity elements in silicon are shown in Table 3, where the ...

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Abstract

The invention relates to a method for removing impurities in metallurgic silicon and belongs to the technical field of silicon purification. The method includes firstly smelting a handful of additives (zirconium, hafnium, zirconium-contained alloy or hafnium-contained alloy) and industrial silicon until materials are completely smelted and cooled to the room temperature, grounding the materials into silicon powder of 186 micrometers, and pickling with mixed acid of aqua regia and HF+HCl to obtain highly pure silicon successively. The method has the advantages that boron that is hardest to remove in the field of silicon purification can be effectively removed as well as other impurities.

Description

technical field [0001] The invention relates to a method for removing impurities in metallurgical grade silicon, belonging to the technical field of silicon purification. Background technique [0002] Since 2013, my country has become the world's largest solar cell market. It is estimated that by 2020, the global installed capacity of solar cells will increase by an average of 47.4GW per year, of which my country will increase by an average of 13GW per year, and the average annual growth will continue to rank first in the world. The rapid popularization of solar cells in my country and around the world puts forward higher requirements for controlling their production costs, and raw materials are one of the key factors determining production costs. [0003] Polysilicon is the main raw material for making solar cells. Since impurities in polysilicon can reduce the photoelectric conversion efficiency of solar cells, the content of impurities must be strictly controlled to obt...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/037
CPCC01B33/037C01P2006/80
Inventor 雷云马文会谢克强吕国强伍继君魏奎先秦博李绍元刘战伟于洁戴永年
Owner KUNMING UNIV OF SCI & TECH
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