CN101372335B - Method for preparing polysilicon - Google Patents
Method for preparing polysilicon Download PDFInfo
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- CN101372335B CN101372335B CN2007101204684A CN200710120468A CN101372335B CN 101372335 B CN101372335 B CN 101372335B CN 2007101204684 A CN2007101204684 A CN 2007101204684A CN 200710120468 A CN200710120468 A CN 200710120468A CN 101372335 B CN101372335 B CN 101372335B
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- hydrogenchloride
- silicon
- dichloro
- trichlorosilane
- tail gas
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Abstract
An improved method for producing polycrystalline silicon comprises the following steps: industrial silicon and hydrogen chloride are taken as raw materials and react to obtain trichlorosilane. The trichlorosilane is purified, put into a reducing furnace and reacts with hydrogen for reduction to obtain the polycrystalline silicon, and the tail gas is collected, wherein, the tail gas mainly comprises hydrogen, hydrogen chloride and chlorosilane, the chlorosilane mainly comprises dichlordihydrosilicate, trichlorosilane and silicon tetrachloride. The method further comprises the steps that the hydrogen chloride in the tail gas is recovered and recycled; and the recovered hydrogen chloride is used in the process of polycrystalline silicon production and reacts with the industrial silicon to obtain the trichlorosilane. The method adopts a dry process to recover the hydrogen chloride from the tail gas which is reused for the polycrystalline silicon production. The method has the advantages of sufficiently using the raw materials, reducing pollutants, solving the environmental pollution problem, improving the product quality and reducing the cost.
Description
Technical field
The present invention relates to a kind of method for preparing polysilicon, more specifically, relate to the improved method for preparing polysilicon of the hydrogenchloride in a kind of recyclable tail gas.
Background technology
Polysilicon is the raw material of preparation silicon single crystal, finally is used to produce unicircuit and electron device, and be one of the highest basic material of information industry consumption maximum, purity requirement, also be the product and the industry of state key encourage growth.
World advanced person's production of polysilicon technology by the company monopolizing of beautiful, day, moral three states always, all there be know-how and technical characterstic separately in each company, through constantly research, exploitation, formed production technique separately, and from national strategy angle separately, strict control techniques transfer also monopolizes global polysilicon market.
China's polysilicon industry is started in the fifties, middle nineteen sixties is realized industrialization, early seventies is pell-mell development once, factory is family surplus in the of 20 nearly, and what all adopt is traditional Siemens process, backward in technique, environmental pollution is serious, supplies consumption is big, production cost height, most losses of enterprise and stop production in succession or change the line of production.
The outstanding characteristics of tradition production of polysilicon technology are tail gas hydrometallurgic recovery technology, be that tail gas in the reduction furnace is used water wash after preliminary pressurization separates chlorosilane, recover hydrogen, but do not reclaim hydrogenchloride, simultaneously, because in the water wash process, foreign gases such as water oxygen gas, carbonic acid gas can be polluted the hydrogen of preparing recovery, so a large amount of hydrogen that reclaim also need to purify once more, in addition, after the chlorosilane hydrolysis, also can produce large amount of sewage in the lessivation, need further to handle, also can cause environmental pollution and supplies consumption big.And the hydrogenchloride that produces in the production fails to be fully utilized, and has both wasted the energy, has caused environmental pollution again.
Summary of the invention
Purpose of the present invention is intended to overcome at least one above-mentioned shortcoming of the prior art, proposes a kind of improved method for preparing polysilicon of recyclable hydrogen chloride in tail gas.
Utilize method of the present invention, not only can reclaim fully and recycle, and can significantly reduce the generation of pollutent in the production, made full use of material simultaneously, reduced cost the hydrogenchloride in the tail gas that in polysilicon production process, is produced.
For achieving the above object, embodiments of the invention propose a kind of method for preparing polysilicon, may further comprise the steps: with industrial silicon and hydrogenchloride (HCl) is raw material, and reaction generates trichlorosilane (SiHCl
3); With described trichlorosilane after purifying with hydrogen (H
2) reaction, thereby reduction generates polysilicon; Collect and generate the tail gas that trichlorosilane, purify trichlorosilane and generation polysilicon process produce, wherein said tail gas mainly comprises hydrogen (H
2), hydrogenchloride (HCl) and chlorosilane, described chlorosilane mainly comprises dichloro-dihydro silicon (SiH
2Cl
2), trichlorosilane (SiHCl
3) and silicon tetrachloride (SiCl
4); Pressurization and cool off described tail gas, described hydrogen, hydrogenchloride, dichloro-dihydro silicon remain gaseous state, thereby by gas-liquid separation gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon are separated with silicon tetrachloride with the trichlorosilane of liquid state so that make described trichlorosilane and silicon tetrachloride become liquid; Make gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon by liquid absorption agent,, thereby hydrogen is separated with dichloro-dihydro silicon with hydrogenchloride so that gasiform hydrogenchloride and dichloro-dihydro silicon are dissolved in the liquid absorption agent; The absorption agent that has dissolved hydrogenchloride and dichloro-dihydro silicon is heated up and/or pressurizes, so that hydrogenchloride and dichloro-dihydro silicon are desorbed from stripping liquid; Make dichloro-dihydro silicon become liquid state with the pressure and/or the temperature of gasiform hydrogenchloride that desorbs by control and dichloro-dihydro silicon, thereby separating hydrogen chloride and dichloro-dihydro silicon reclaim hydrogenchloride thus.
The further embodiment according to the present invention, described tail gas is pressurized to 0.3～0.9Mpa.Described tail gas is cooled to-20～-70 ℃.Described absorption agent is a silicon tetrachloride.
The further embodiment according to the present invention, a kind of method for preparing polysilicon also comprises: the liquid silicon tetrachloride that has absorbed hydrogenchloride is heated up and/or pressurizes, make that hydrogenchloride is desorbed.
Particularly, the described liquid silicon tetrachloride that has absorbed hydrogenchloride is raised to 70～220 ℃; The described liquid silicon tetrachloride that has absorbed hydrogenchloride is pressurized to 0.1～2.0Mpa.The gasiform hydrogenchloride that desorbs and the temperature of dichloro-dihydro silicon are controlled to be 30～-70 ℃.The gasiform hydrogenchloride that desorbs and the pressure-controlling of dichloro-dihydro silicon are 0.1～2.0Mpa.
The further embodiment according to the present invention, described method for preparing polysilicon also are included in before tail gas pressurization and the cooling, with liquid silicon tetrachloride tail gas are carried out drip washing.
The further embodiment according to the present invention, described method for preparing polysilicon also comprises: the liquid silicon tetrachloride that has absorbed hydrogenchloride in lessivation is heated up and/or pressurizes, make hydrogenchloride be desorbed from liquid silicon tetrachloride.
Particularly, the described liquid silicon tetrachloride that has absorbed hydrogenchloride is raised to 70～220 ℃.The described liquid silicon tetrachloride that has absorbed hydrogenchloride is pressurized to 0.1～2.0Mpa.
Overcome and eliminated the shortcoming of the hydrometallurgic recovery technology that adopts in traditional production of polysilicon according to the present invention, hydrogenchloride in the tail gas is recycled simultaneously, especially the hydrogenchloride that reclaims is turned back in the production of polysilicon operation, make the production means can be able to sufficient utilization, and significantly reduced the generation and the quantity of pollutent in the production.
According to the present invention, material is in closed cycle is used, greatly reduce the consumption of raw and auxiliary material, fundamentally solved the problem of environmental pollution that production of polysilicon causes, simultaneously, save project investment, improved quality product, reduce cost, made the construction and upgrading of production of polysilicon project obtain sufficient initiative.
The additional feature and advantage of the present invention part in the following description provide, and part will become obviously from the following description, or recognize by practice of the present invention.
Description of drawings
Fig. 1 is the schematic flow sheet according to first embodiment of the invention;
Fig. 2 is the schematic flow sheet according to second embodiment of the invention.
Embodiment
So that explain the present invention, described embodiment is exemplary, can not be interpreted as limitation of the present invention below by describing specific embodiment with reference to the accompanying drawings.
Embodiment 1:
With reference to figure 1, wherein show the FB(flow block) that to use according to a kind of improved method for preparing polysilicon of the embodiment of the invention, production of polysilicon technology of the present invention is that to utilize industrial silicon and hydrogenchloride (HCl) be main raw material, generates with trichlorosilane (SiHCl by the control reaction conditions
3) be master's the chlorosilane and the mixture of hydrogen, pass through existing purification techniques then to trichlorosilane (SiHCl
3) purify after, send into reduction furnace, make trichlorosilane (SiHCl
3) and auxiliary material hydrogen (H
2) reaction, reduction generates polysilicon.
In the process of above-mentioned industrial production polysilicon, the tail gas of generation mainly comprises hydrogen (H
2), hydrogenchloride (HCl) and chlorosilane, described chlorosilane mainly comprises dichloro-dihydro silicon (SiH
2Cl
2), trichlorosilane (SiHCl
3) and silicon tetrachloride (SiCl
4).
Reaction main in the production process is:
Si+HCl→SiHCl
3+SiCl
4+H
2
SiHCl
3→Si+SiCl
4+H
2
SiHCl
3+H
2→Si+HCl
Need to prove, owing in primary industry silicon, also have plurality of impurities, for example iron, aluminium, calcium, boron, phosphorus or the like, so, in reaction, also can produce the muriate of calcium, the muriate of iron, the muriate of aluminium and the muriate of boron, and solid and/or gaseous impurities such as other high chlorosilanes, these impurity also can be mixed in the middle of the tail gas, certainly content is less, and the method according to this invention also can be handled these impurity, and this will be described below.
Below with reference to the improved method for preparing polysilicon of Fig. 1 description according to first embodiment of the invention, Fig. 1 shows the schema according to the method for preparing polysilicon of first embodiment of the invention.
At first, the tail gas that produces in the polysilicon production process is collected, and the tail gas of collecting is pressurizeed and cools off, and for example, tail gas is pressurized to about 0.3～0.9Mpa and is cooled to approximately-20～-70 ℃, because described trichlorosilane (SiHCl
3) and silicon tetrachloride (SiCl
4) and described hydrogen (H
2), hydrogenchloride (HCl), dichloro-dihydro silicon (SiH
2Cl
2) between the boiling point difference, therefore, under above-mentioned processing condition, the trichlorosilane (SiHCl in the tail gas
3) and silicon tetrachloride (SiCl
4) become liquid state, and described hydrogen (H
2) still remain gaseous state, described hydrogenchloride (HCl) and dichloro-dihydro silicon (SiH simultaneously
2Cl
2) also mainly exist with gaseous form, thereby just gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon can be separated with silicon tetrachloride with the trichlorosilane of liquid state by gas-liquid separation.
Above-mentioned pressure condition 0.3～0.9Mpa and temperature condition-20～-70 ℃ only are exemplary, for those having ordinary skill in the art will appreciate that, as long as can gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon be separated with silicon tetrachloride with the trichlorosilane of liquid state by gas-liquid separation, any suitable pressure and temperature condition can be used.
Then, utilize liquid silicon tetrachloride (SiCl
4) as absorption agent, make most gaseous hydrogen chloride (HCl) and dichloro-dihydro silicon (SiH
2Cl
2) be dissolved in the absorption agent, so that with gasiform hydrogen (H
2) and hydrogenchloride (HCl) and dichloro-dihydro silicon (SiH
2Cl
2) initial gross separation, yet, for persons of ordinary skill in the art may appreciate that in isolated gaseous hydrogen, still have the gaseous hydrogen chloride (HCl) and the silicon tetrachloride (SiCl of small portion of residual
4) be mixed in wherein.In addition, need to prove that absorption agent is not limited to liquid silicon tetrachloride.
For the hydrogenchloride that is absorbed as absorption agent by liquid silicon tetrachloride, can hydrogenchloride and the dichloro-dihydro silicon that be dissolved in the stripping liquid be desorbed by the method that heats up and/or pressurize; In the present embodiment, it is 70～220 ℃ that employing is warmed up to, and is pressurized to 0.1～2.0Mpa simultaneously, just hydrogenchloride and dichloro-dihydro silicon can be desorbed.
Certainly, above-mentioned pressure condition 0.1～2.0Mpa and temperature condition only are exemplary for 70～220 ℃, as long as hydrogenchloride and dichloro-dihydro silicon can be desorbed for persons of ordinary skill in the art may appreciate that, any suitable pressure and temperature condition can be used.
In like manner, utilize the difference of physics boiling point once more, gaseous hydrogen chloride and the dichloro-dihydro silicon that is desorbed is passed through control pressure and/or controlled temperature again, carry out gas-liquid separation, make that hydrogenchloride is gaseous state, dichloro-dihydro silicon is liquid, and collects with surge tank respectively or directly fail by pipeline and reclaim hydrogenchloride and dichloro-dihydro silicon.
The hydrogenchloride of separating can turn back in the polysilicon production process, with industrial silicon reaction, synthesizing trichlorosilane, thereby the hydrogenchloride in the tail gas can be by recycle fully in polysilicon production process, reduce production cost, improved the utilising efficiency of raw material.And, reduced the generation of pollutent, avoid environmental pollution, and eliminated and handled the needs of pollutent, thereby reduced production cost and energy consumption.
Embodiment 2:
Below with reference to the improved method for preparing polysilicon of Fig. 2 description according to second embodiment of the invention.Fig. 2 shows the FB(flow block) according to second embodiment of the invention, and the key distinction of present embodiment and above-mentioned first embodiment is, also comprises with liquid silicon tetrachloride (SiCl
4) step of tail gas being carried out drip washing.
In the middle of traditional wet method tail gas treatment process process, usually all be that water carries out drip washing to tail gas, purpose is that the hydrogenchloride (HCl) in the tail gas is entered in the water by drip washing, the chlorosilane that part does not reclaim is hydrogenchloride and Silicon dioxide, hydrate by the water wash posthydrolysis, this type of sewage needs individual curing, causes supplies consumption big, and environmental pollution is serious, simultaneously also waste the hydrogenchloride that can be used as raw materials for production in a large number, limited large-scale industrialized production.
According to embodiments of the invention, lessivation adopts liquid silicon tetrachloride (SiCl
4), the effect and the effect of carrying out drip washing with traditional water are all inequality.In the present invention, adopt liquid silicon tetrachloride (SiCl
4) tail gas is carried out drip washing can remove impurity in the tail gas, as mentioned above, described tail gas is except mainly comprising hydrogen (H
2), hydrogenchloride (HCl), dichloro-dihydro silicon (SiH
2Cl
2), trichlorosilane (SiHCl
3) and silicon tetrachloride (SiCl
4), owing to produce in the process of polysilicon, also can produce impurity such as solid impurity and high chlorosilane, therefore, utilize liquid silicon tetrachloride (SiCl
4) tail gas is carried out drip washing, can remove the above-mentioned impurity in the tail gas.
In addition, owing in the production reduction process of polysilicon, also can produce the part by product---silicon tetrachloride (SiCl
4), common every production 1kg polysilicon can produce the silicon tetrachloride (SiCl about 10kg
4), therefore, if silicon tetrachloride can't be handled and use, restriction is just received in the production of so much crystal silicon.Therefore, according to the present invention, the silicon tetrachloride that produces in the production of polysilicon can be used for tail gas is carried out drip washing.
Simultaneously, in the present embodiment, the liquid silicon tetrachloride that has absorbed hydrogenchloride in lessivation is heated up and/or pressurizes, make that hydrogenchloride is desorbed once more.In the present embodiment, can adopt to be warmed up to 70～220 ℃, be pressurized to 0.1～2.0Mpa simultaneously, hydrogenchloride is desorbed.And then, hydrogenchloride and the chlorosilane that is desorbed are simultaneously carried out separation and purification once more by the gas-liquid separation process.Particularly, the gasiform hydrogenchloride that desorbs of described control and the temperature of dichloro-dihydro silicon are 30～-70 ℃.The gasiform hydrogenchloride that described control desorbs and the pressure of dichloro-dihydro silicon are 0.1～2.0Mpa.
Certainly, 70～220 ℃ of above-mentioned pressure condition 0.1～2.0Mpa and temperature condition, and temperature condition 30～-70 ℃, only be exemplary, as long as hydrogenchloride can be desorbed for persons of ordinary skill in the art may appreciate that, any suitable pressure and temperature condition can be used.
Following table shows the effect hydrogenchloride recycled according to method for preparing polysilicon of the present invention and conventional wet side relatively.
Production method of the present invention is to the comparison to the hydrogenchloride recovering effect of hydrogenchloride recovering effect and conventional art
| Project | The present invention | Conventional wet |
| Hydrogenchloride rate of recovery % | More than 99.99% | All drench in the entry |
| Hydrogenchloride reclaims purity | More than 99%, contain micro-chlorosilane | All drip washing entry, generation large amount of sewage |
From above-mentioned table as can be seen, utilize method of the present invention, recovery of hydrogen chloride rate and recovery quality all are higher than traditional wet method far away, according to the present invention, hydrogenchloride almost completely obtain reclaiming and purity very high, therefore, can be as with industrial silicon reaction and produce the raw material of polysilicon, thus recycled, reduced consumption of raw materials, saved cost, reduced pollution, and effect is apparent from above table.
Although foregoing has illustrated and has described embodiments of the invention, but for those skilled in the art in this area, without departing from the principles and spirit of the present invention, can change these embodiment, so scope of the present invention is limited by claims and equivalent thereof.
Claims (9)
1. method for preparing polysilicon may further comprise the steps:
With industrial silicon and hydrogenchloride is raw material, and reaction generates trichlorosilane;
With described trichlorosilane after purifying and hydrogen reaction, thereby reduction generates polysilicon;
Collect and generate the tail gas that trichlorosilane, purify trichlorosilane and generation polysilicon process produce, wherein said tail gas mainly comprises hydrogen, hydrogenchloride and chlorosilane, and described chlorosilane mainly comprises dichloro-dihydro silicon, trichlorosilane and silicon tetrachloride;
Silicon tetrachloride with liquid state carries out drip washing to described tail gas, to remove solid impurity and high chlorosilane wherein;
Pressurization and the described tail gas of cooling after drip washing, described hydrogen, hydrogenchloride, dichloro-dihydro silicon remain gaseous state, thereby by gas-liquid separation gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon are separated with silicon tetrachloride with the trichlorosilane of liquid state so that make described trichlorosilane and silicon tetrachloride become liquid;
Make gasiform hydrogen, hydrogenchloride and dichloro-dihydro silicon by liquid absorption agent,, thereby hydrogen is separated with dichloro-dihydro silicon with hydrogenchloride so that gasiform hydrogenchloride and dichloro-dihydro silicon are dissolved in the liquid absorption agent;
The absorption agent that has dissolved hydrogenchloride and dichloro-dihydro silicon is heated up, so that hydrogenchloride and dichloro-dihydro silicon are desorbed from stripping liquid; With
The gasiform hydrogenchloride that desorbs by control and the pressure and/or the temperature of dichloro-dihydro silicon make dichloro-dihydro silicon become liquid state, thereby separating hydrogen chloride and dichloro-dihydro silicon reclaim hydrogenchloride thus.
2. method for preparing polysilicon according to claim 1, wherein said tail gas is pressurized to 0.3～1.5MPa.
3. method for preparing polysilicon according to claim 1, wherein said tail gas are cooled to-20～-70 ℃.
4. method for preparing polysilicon according to claim 1, wherein said stripping liquid are silicon tetrachloride.
5. method for preparing polysilicon according to claim 1, the wherein said absorption agent that has dissolved hydrogenchloride and dichloro-dihydro silicon is raised to 70～220 ℃.
6. method for preparing polysilicon according to claim 1 wherein heats up to the liquid silicon tetrachloride that has absorbed hydrogenchloride in lessivation, makes hydrogenchloride be desorbed from liquid silicon tetrachloride.
7. method for preparing polysilicon according to claim 6, the wherein said liquid silicon tetrachloride that has absorbed hydrogenchloride is raised to 70～220 ℃.
8. method for preparing polysilicon according to claim 1, the gasiform hydrogenchloride that wherein desorbs and the pressure-controlling of dichloro-dihydro silicon are 0.1～2.0Mpa.
9. method for preparing polysilicon according to claim 1, the gasiform hydrogenchloride that wherein desorbs and the temperature of dichloro-dihydro silicon are controlled to be 30～-70 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101204684A CN101372335B (en) | 2007-08-20 | 2007-08-20 | Method for preparing polysilicon |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101204684A CN101372335B (en) | 2007-08-20 | 2007-08-20 | Method for preparing polysilicon |
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| CN101372335A CN101372335A (en) | 2009-02-25 |
| CN101372335B true CN101372335B (en) | 2011-08-10 |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101628710B (en) * | 2009-08-03 | 2011-01-26 | 中国石化集团南京设计院 | Method for producing high-purity concentrated hydrochloric acid by adopting hydrogen chloride gas containing chlorosilane |
| CN102180467B (en) * | 2010-12-24 | 2012-12-26 | 江苏中能硅业科技发展有限公司 | GCL method for producing polycrystalline silicon |
| CN102390833B (en) * | 2011-08-03 | 2013-06-05 | 乐山乐电天威硅业科技有限责任公司 | Method for recycling waste chlorosilane in polycrystalline silicon, produced by using modified Siemens process under negative pressure |
Citations (2)
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|---|---|---|---|---|
| EP0921098A1 (en) * | 1997-11-10 | 1999-06-09 | MEMC Electronic Materials, Inc. | Closed loop process for producing polycrystalline silicon and fumed silica |
| CN1693192A (en) * | 2005-06-16 | 2005-11-09 | 中国有色工程设计研究总院 | Process for pressure purification of silicon trichlorohydrgen and apparatus thereof |
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2007
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0921098A1 (en) * | 1997-11-10 | 1999-06-09 | MEMC Electronic Materials, Inc. | Closed loop process for producing polycrystalline silicon and fumed silica |
| CN1693192A (en) * | 2005-06-16 | 2005-11-09 | 中国有色工程设计研究总院 | Process for pressure purification of silicon trichlorohydrgen and apparatus thereof |
Non-Patent Citations (2)
| Title |
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| 严大洲.我国多晶硅生产现状与发展.世界有色金属.2001,(1),6-8，35. * |
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