CN101143722A - Method for abstracting solar energy level silicon by physics metallurgical method - Google Patents

Abstract

The invention discloses a solar grade silicon refinery method by using physical metallurgy. The method includes the following steps: firstly, a vacuum induction melting furnace is utilized and a high purity oxide crucible is selected to avoid carbon pollution; secondly, the vacuum pumping is operated simultaneously during the heating process; thirdly, the protective gases are injected into the furnace; when the melting temperature reaches a certain value, strong oxidative gases (chlorine) are injected into the bottom of the crucible; fourthly, while stirring the silicon solution, the strong oxidative gases carry out chemical reactions with Fe-Al-Ca-P-V etc impurity elements, which lead to the gasification and thermal insulation of the elements; fifthly, the refined silicon is injected into the tundish, and the directional crystallization program is processed. The invention has a simple method, an easy operation, rapid heating and no pollution. The silicon material refined by the invention can reach 5N or higher purity.

Description

The method of abstracting solar energy level silicon by physics metallurgical method

Technical field

The present invention relates to renewable energy source material field, more specifically relate to a kind of method of abstracting solar energy level silicon by physics metallurgical method, directly utilize the vacuum induction melting heating, cooperate strong oxidizing property gas bottom blowing removal of impurities to produce silicon material for solar cells.

Background technology

After the Kyoto Protocol was announced, the whole world had awarded great attention to environmental protection, Sustainable development.The disposable energy such as oil, coal is progressively exhausted, and everybody recognizes not Renewable Energy Development as early as possible, and making up harmonious Sustainable development society is exactly empty verbiage.And traditional HIGH-PURITY SILICON mode of production, the developing steps that investment is big, big to environmental influence, its production capacity does not reach the photovoltaic industry far away.The main method of producing silicon for solar cell at present is arranged in order: improvement Siemens Method, silane thermal decomposition process and fluidized bed method.Ningxia Hui Autonomous Region, the peaceful polysilicon project of introducing by retrieval easternly, May 30 2006 date issued, polycrystalline silicon material is to be raw material reaches certain purity after a series of physical-chemical reactions are purified electronic material with the industrial silicon, be very important intermediates in the silicon product industrial chain, being the main raw material of making silicon polished, solar cell and HIGH-PURITY SILICON goods, is information industry and the most basic starting material of new forms of energy industry.

Polysilicon is divided into metallurgical grade silicon, solar-grade silicon and electronic-grade silicon by purity.Wherein the purity of electronic-grade silicon is the highest, and ultra-high purity reaches 99.999999999% (11N).

At present, world production polysilicon country mainly is the U.S., Germany, Japan, and three state's ultimate productions account for more than 90% of Gross World Product.Family surplus 40 of the manufacturing enterprise that China is engaged in, ultimate production reaches 1400 tons, only accounts for 0.4% of world's product.International market demand is with annual 10% one 12% speed increment, and by 2005, global demand reached 27000 tons, estimates will reach 60000 tons in 2010.Supply falls short of demand owing to the world market, causes the rise significantly of product price, and solar-grade polysilicon rises to 2005 rapidly about 80 dollars/kilogram from 9 dollars/kilogram in 2000, and the domestic market reaches a high position of 100 dollars/kilogram.

The important source material of producing polysilicon is industrial silicon, liquid chlorine, hydrogen.Produce 3000 tons polysilicon per year, need to take up an area of 1000-1500 mu, consume 3600 tons of industrial silicons, 4800 tons of chlor-alkalis, 3900 tons of hydrogen, electric power 2,100,000,000 degree, 600 tons/hour of recirculated waters, gross investment 3,000,000,000, gross output value 15-30 hundred million.

Production of polysilicon is the most ripe also to be that the maximum-norm application technology is an improvement Siemens Method (trichlorosilane reduction method), promptly industrial silicon first chlorination under 1400 degree high temperature is become trichlorosilane, restoring into polysilicon, mainly is to obtain high-purity polycrystalline with chemical reaction complicated between silicon powder and chlorine, the hydrogen.This technology is ripe at present.

In view of the polysilicon vast market prospect, Nanjing DaLu Industry Investment Group Co.,Ltd's (being called for short " continent group ") intends in west area construction polysilicon project.Continent group is created in 1993, is located in the national technological development zone in Jiangning, Nanjing, is the group of private new high-tech enterprise that is engaged in electric power technological applications, biotech industryization, the green information energy, financial investment.Continent group has a mind in peaceful eastern construction of base polysilicon project after repeatedly investigating the Ning Dong base.On April 26th, 2006, three people of delegation of Ning Dong administration commission make a special trip to continent group and contact with regard to the polysilicon project.By investigating study polysilicon there has been more deep understanding, the one, polysilicon is capital-intensive high-tech project.Being projects encouraged by the state, also is simultaneously a project that power consumption is relatively large; The 2nd, the polysilicon technology is grasped by world enterprise of several family at present, and it is blank to fill up China's industry in peaceful eastern construction of base polysilicon project; The 3rd, the present benefit of polysilicon project is fine, in case but technological breakthrough, cost has been competed into key, and investment risk is bigger.Simultaneously, by comprehensive promotion, continent group has been had comprehensively and accurately Ning Dong base situation understand, and by having an informal discussion, exchanging, both sides have reached common recognition with regard to continent group in Ning Dong base investment construction polysilicon project.During this time, the staff of Ning Dong administration commission actively collects related data, actively gets in touch relevant departments and leader, and keeps close ties and communication with continent group.On May 16th, 2006, go to continent group to visit investigation by the member of the standing committee of party committee of autonomous region, tour survey of economy group of Yinchuan City party and government, and enter peaceful eastern construction of base with regard to the polysilicon project, carried out further exchanges and communication with the high-level leader of continent group.And signed the framework agreement of cooperating, carried out deep negotiation and discussion with continent group.According to protocol contents, this polysilicon project is introduced the Ning Dong base, 10000 tons of planning scales, and gross investment reaches 10,000,000,000 yuan, and being divided into is to build three phases, and first phase and second phase are respectively produces 3000 tons solar level high-purity silicon material per year, invests about 3,000,000,000 Renminbi respectively; Three phases were produced 4000 tons of semiconductor grade high-purity silicon materials per year, invested about 4,000,000,000 yuan.Production of polysilicon is the most ripe also to be that the maximum-norm application technology is an improvement Siemens Method (trichlorosilane reduction method), promptly industrial silicon first chlorination under 1400 degree hot conditionss is become trichlorosilane, restoring into polysilicon, mainly is to obtain high-purity polycrystalline silicon from complicated chemical reaction between silicon powder and chlorine, the hydrogen.Till now, the polysilicon in the whole world 90% all is to utilize this mode to produce, and the in the recent period domestic silicon production technology of introducing from Russia also is the siemens's method that adopts.The problem that (southern glass Yichang project, Ningxia project) exists now is: the improvement Siemens Method needs huge investment, and the construction period is long.A large amount of problems of using liquid chlorine, hydrogen to have environmental protection and secure context, and high-purity brick silicon that the physical metallurgy method is produced, though be not suitable for large-scale integrated circuit, purity is that the polysilicon of 5N is suitable for making the solar level battery very much.

Summary of the invention

The objective of the invention is to be to provide a kind of method of abstracting solar energy level silicon by physics metallurgical method, easy to implement the method, easy to operate, when preventing the oxidation of silicon raw material, preventing the fusion process chemical pollution, utilize strong oxidizing gas stirring and itself and silicon impurities in raw materials are fully reacted, thereby make its gasification reach the purpose of purification.

For achieving the above object, the applicant has carried out a large amount of tests in vacuum induction melting furnace.Under the effect of strong oxidizing property gas stirring, impurity in the silicon materials and oxidizing gas produce reaction, and the result of impurity element by the expection decay occur.

A kind of step of abstracting solar energy level silicon is:

A, utilize vacuum induction melting furnace, in the high pure oxide crucible, add the metallic silicon raw material pollution of carbon (thereby avoided);

B, the raw material in the high pure oxide crucible is heated, in heat-processed, vacuumize (oil-sealed rotary pump);

C, injection protective gas (nitrogen or argon gas) avoid silicon oxidized in heat-processed, and smelting temperature is set at the 1450-1780 degree, inject strong oxidizing property gas (chlorine) to crucible bottom after Heating temperature reaches 1600 degree;

D, strong oxidizing gas produce chemical reaction and make its gasification with impurity element such as Fe-Al-Ca-P-V when stirring the Pure Silicon Metal liquation, reach design temperature (design temperature in the aforementioned C step) and are incubated 55-80 minute (the concrete time is determined according to charging weight);

Good Pure Silicon Metal injection tundish enters the crystallographic orientation program to be about to refining after E, melting purification process are finished.

The present invention compared with prior art, have the following advantages and effect: material source is abundant, processing method is simple, construction period short (adopt additive method, its construction period needs 2 years, even the longer time), the present invention only needs six months just can finish the production line construction, easy to operate, less investment, last detective.

Use the inventive method purifying metal silicon, purity can reach more than the 5N.And reached the silicon melt of 5N purity, in the crystallographic orientation device, slowly in the process of cooling, also have a spot of impurity element and in crystallisation process, separate out.Therefore, the final solar power silicon that obtains of applicant is higher than melt purity.The solar energy level silicon that present method is produced can be used for the solar cell manufacturing.Present international solar module market value is 4.5-5.5 dollar/W, and the main part of the production cost of solar cell, silicon chip accounts for 40% of total cost greatly, and the silicon for solar cell cost that present method is produced only is the 50-60% of traditional technology method.So can reduce the manufacture of solar cells cost significantly, create favourable condition for advancing the solar cell application scope.To buffering energy demand contradictory, alleviate the disposable energy and use significant the influence of environment.

Embodiment

Embodiment 1:

A kind of method of abstracting solar energy level silicon by physics metallurgical method the steps include:

1, utilize vacuum induction melting, add metallic silicon raw material in the high pure oxide crucible, raw material is the industrial silicon of 2102,2105,211 trades mark, its major impurity scope: %

Fe Al Ca Si

0.20 0.01 0.02-0.1 99.60-99.68

Pure Silicon Metal is pulverized into stove, and particle diameter is controlled in the 10mm scope.

2, with raw material heating in the high pure oxide crucible, raw material is evacuated to 5 * 10-1Pa after putting into induction melting furnace.

3, inject protective gas (nitrogen or argon gas); smelting temperature is set in 1450 or 1650 or 1670 or 1680 or 1720 or 1740 or 1760 or 1775 or 1780 ℃; when reaching 1600 degree, melt temperature promptly begins bottom blowing strong oxidizing property gas chlorine; continue to heat this moment; but be no more than 1780 ℃, thereby make it stir melt, fully react and make its gasification reach the purpose of removing impurity with impurity element.

4, strong oxidizing gas chlorine produces chemical reaction and makes its gasification with the Fe-Al-Ca-P-V impurity element when stirring the Pure Silicon Metal liquation, reach design temperature (above-mentioned the 3rd step) and be incubated 60-70 minute (the concrete time is determined according to charging weight), melting is purified and is reached after the 5N, and melted silicon is injected the crystallographic orientation device.Melted silicon in the control crystallographic orientation device with the 30-35 degree/hour speed slowly be cooled to below 50 degree, thereby obtain to have the high-purity silicon ingot of crystallographic orientation feature.

5, after the melting purification process was finished, the Pure Silicon Metal that refining is good injected tundish and enters the crystallographic orientation program.

6, chemical analysis is carried out in sampling, and acquisition purity is 99.9996 result.

Embodiment 2:

1, utilize vacuum induction melting, add metallic silicon raw material in the high pure oxide crucible, raw material is that the homemade trade mark is 311 Pure Silicon Metal, its major impurity scope: %

Fe Al Ca Si

0.30 0.10 0.10 99.50

311 Pure Silicon Metals are pulverized into stove, and particle diameter is controlled in the 10mm scope.

2, to raw material heating in the high pure oxide crucible, raw material is evacuated to 5 * 10-1Pa after putting into induction melting furnace.

3, inject protective gas (nitrogen or argon gas); smelting temperature is set in 14500 or 1650 or 1670 or 1680 or 1720 or 1740 or 1760 or 1775 or 1780 ℃; when reaching 1600 degree, melt temperature promptly begins bottom blowing strong oxidizing property gas chlorine; continue to heat this moment; but be no more than 1780 ℃, thereby make it stir melt, fully react and make its gasification reach the purpose of removing impurity with impurity element.

4, strong oxidizing gas chlorine produces chemical reaction and makes its gasification with the Fe-Al-Ca-P-V impurity element when stirring the Pure Silicon Metal liquation, reach design temperature (above-mentioned the 3rd step) and be incubated 60-80 minute (the concrete time is determined according to charging weight), melting is purified and is reached after the 5N, and melted silicon is injected the crystallographic orientation device.Melted silicon in the control crystallographic orientation device with the 30-35 degree/hour speed slowly be cooled to 30 or 35 or 38 or 42 or 45 or 48 degree, thereby obtain to have the high-purity silicon ingot of crystallographic orientation feature.

5, after the melting purification process was finished, the Pure Silicon Metal that refining is good injected tundish and enters the crystallographic orientation program.

6, chemical analysis results shows, purifies through melting, and silicon materials purity reaches 99.9994.

Claims (1)

1. the method for an abstracting solar energy level silicon by physics metallurgical method, it comprises the following steps:

A, utilize vacuum induction melting furnace, in the high pure oxide crucible, add metallic silicon raw material;

B, the raw material in the high pure oxide crucible is heated, in heat-processed, vacuumize;

C, injection protective gas, smelting temperature is set at the 1450-1780 degree, injects strong oxidizing property gas to crucible bottom after Heating temperature reaches 1600 degree;

D, strong oxidizing gas produce chemical reaction and make its gasification with the Fe-Al-Ca-P-V impurity element when stirring the Pure Silicon Metal liquation, reach design temperature and are incubated 55-80 minute;

Good Pure Silicon Metal injection tundish enters the crystallographic orientation program to be about to refining after E, melting purification process are finished.