CN102001661B - Method for slagging, boron removal and purification of metalluragical silicon - Google Patents
Method for slagging, boron removal and purification of metalluragical silicon Download PDFInfo
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- CN102001661B CN102001661B CN2010105532815A CN201010553281A CN102001661B CN 102001661 B CN102001661 B CN 102001661B CN 2010105532815 A CN2010105532815 A CN 2010105532815A CN 201010553281 A CN201010553281 A CN 201010553281A CN 102001661 B CN102001661 B CN 102001661B
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Abstract
The invention discloses a method for slagging, boron removal and purification of metalluragical silicon, comprising the following steps of: selecting a metalluragical silicon material, heating until the metalluragical silicon is completely melted into a silicon solution and adjusting the temperature of the silicon solution; then adding a ternary slagging agent; removing scum on the surface of the silicon solution by stirring and carrying out a heat-insulating reaction; and standing the silicon solution for casting and then obtaining polysilicon, wherein the content of B in the polysilicon meets the solar level requirement. According to the method, complicated blowing equipment can be avoided, the process equipment can be simplified and the cost can be reduced; and the method is convenient for industrial application.
Description
Technical field
The invention belongs to the photovoltaic technology field, be specifically related to a kind of metalluragical silicon slagging boron removal method of purification.
Background technology
(Boron B) is acceptor impurity commonly used in the solar-grade polysilicon to boron.B content general requirement is below 0.3ppm in the solar cell level polysilicon, and it is negative effects such as decline of polysilicon resistance rate and generation photo attenuation that the B too high levels can cause, and influences the efficiency of conversion and the stability of solar cell.Boron content generally between 10 to 40ppm, must could use through purifying in the industrial silicon.Siemens Method is mainly adopted in the preparation of high purity polycrystalline silicon at present; This is owned by France purifies in chemical method; Complex process, front-end investment are big, and the construction period is long, and energy consumption is big; Seriously polluted, thereby seek new method of directly industrial silicon being purified and become one of present solar-grade polysilicon industry research focus.
Metallurgy method has development potentiality because of possessing simple, the lower-cost advantage of technology.At present main metallurgy removes plasma method or the air blowing slag practice etc. that boron technology comprises air blast, slag practice, plasma method and combines vacuum technique, induction heating technique.Require equipment the simplest with slag practice in many methods, easy for industrialized is promoted.Thereby the researching value and the application prospect of the tool reality of slag practice.Its mechanism probably can be divided into two types.The one, gas phase is removed boron, and soon the boron in the polysilicon changes into the compound of the boron with higher vapor pressure, like hydrogenate, oxide compound and oxyhydroxide etc.The 2nd, the slag boron that is divided by is about to boron in the polysilicon and changes into the compound that can combine mutually with slag, is mainly oxide compound.Its theoretical foundation is that the oxide compound of boron is an acidic oxide, can be absorbed by alkaline matter, combines with slag, removes in the lump mutually together with slag.
U.S. Pat 5788945 (Anders Schei; Method for refining of silicon) disclose a kind of through adding continuously the method that helps the slag agent to silicon liquid; Make that B content is reduced to 1ppm from 40ppm in the silicon, the used slag agent composition that helps is 60%CaO and 40%SiO
2
U.S. Pat 200501391485 (Fujiwara Hiroyasu et al.; Silicon purifying method; Slag for purifying silicon, and purified silicon) disclose a kind of B method of removing, this method adopts the technology of blowing and carrying out simultaneously with slag making; Make that B content is reduced to 0.8ppm from 7.4ppm in the silicon, the used slag agent composition that helps is CaO and SiO
2
Patent CN101671023A discloses a kind of boron-removing purification method of polysilicon, can boron content in the polysilicon be reduced to 0.18ppm from 15ppm.This method has adopted two kinds of slag formers, and wherein first kind is Na
2CO
3+ SiO
2Second kind is CaO+CaF
2+ SiO
2, the processing requirement vacuum condition.
There is following problem in above-mentioned technology in industrial application: (1), blow or vacuumize equipment requirements higher; (2), do not add CaF
2Slag system its remove the still difficult requirement that reaches the solar-grade polysilicon of effect of boron, and CaF
2Adding comparatively serious to the crucible equipment corrosion; (3), select for use the compound slag practice of two or more slag system to make process complications, be unfavorable for that industry promotes.
Summary of the invention
The object of the present invention is to provide a kind of metalluragical silicon slagging boron removal method of purification, this method does not need complicated air blowing equipment, has simplified processing unit, has reduced cost, is convenient to industrial applications.
The objective of the invention is to realize: a kind of metalluragical silicon slagging boron removal method of purification through following technical scheme; Choose the metalluragical silicon material; Be heated to and all be fused into silicon liquid, regulate the temperature of silicon liquid, add the ternary slag former then; After stirring and insulation reaction, remove the scum silica frost on silicon liquid surface, casting after silicon liquid is left standstill to obtain the polysilicon that B content satisfies the solar level requirement.
Metalluragical silicon slagging boron removal method of purification provided by the invention is preferably and contains following steps:
(1) chooses the metalluragical silicon material as raw silicon, raw silicon is heated to all is fused into silicon liquid;
(2) temperature of adjusting silicon liquid drops into prefabricated ternary slag former in the said silicon liquid in batches, and every batch of silicon liquid that adds the ternary slag former all need be removed the scum silica frost on silicon liquid surface after stirring and insulation reaction;
(3) cast after silicon liquid is left standstill and to obtain the polysilicon that B content satisfies the solar level requirement.
Initial B content is 6 ~ 35ppm in the metalluragical silicon material described in the step of the present invention (1).
Earlier progressively improve Medium frequency induction power with plumbago crucible in step of the present invention (1)-step (2) the metalluragical silicon material all is fused into silicon liquid, reduce intermediate frequency furnace power then, keep the silicon liquid temp.
Ternary slag former described in the step of the present invention (2) is Na
2CO
3-SiO
2-Al
2O
3Ternary slag former, wherein Na
2CO
3The quality percentage composition be 55%-65%, Al
2O
3The quality percentage composition be 0.2%-15%, surplus is SiO
2Al wherein
2O
3Content be preferably 0.5%-3%.
The weight part ratio of the every batch of ternary slag former and metalluragical silicon material is 5-10 ︰ 100 in the step of the present invention (2).
The temperature of regulating silicon liquid in the step of the present invention (2) is 1450-1550 ℃.
The mode that stirs in the step of the present invention (2) is that intermittent type stirs, and mixing chamber was divided into 5-10 minute.
The total reaction time of ternary slag former and silicon liquid is 30-60 minute described in the step of the present invention (2).
Time of repose is 5-10 minute in the step of the present invention (3).
Principle of the present invention is: the present invention is directed to sodium is the easy volatile of slag former, introduces the Al of proper ratio
2O
3, be under slag former high partition ratio, the high prerequisite keeping sodium except that advantages such as boron efficient, form stable ternary slag system, improving sodium is the utilization ratio of slag former, improves the whole effect of boron that removes.
The B mechanism of removing of this ternary slag system is:
SiO
2(l)→Si(l)+[O] （1）
Na
2CO
3→Na
2O(l)+CO
2(g) （2）
Na
2O(l)→2[Na]+[O] （3）
2B(l)+3[O]?→B
2O
3(l) （4）
Na
2O(l)+Al
2O
3→2NaAlO
2 （5）
From reaction, can find out SiO in the slag former
2Mainly be responsible for providing free oxygen.
Na
2CO
3Play three kinds of effects: one, produce CO through decomposing
2Gas plays the certain physical stirring action to melt; Two, Na
2CO
3Decompose the Na that the back produces
2O further decomposes the generation free oxygen; Three, maintain the alkalescence of melt.
Na
2CO
3Fusing point be 851 ℃, Na
2The boiling point of O is 1275 ℃; Fusing point much smaller than silicon; Be added directly into and have considerable part in the fused silicon liquid and decompose, gasification or scatter and disappear with the form of flue dust is difficult to keep the proportioning of initial slag system; Reduced the slag system utilization ratio and caused atmospheric pollution simultaneously, becoming restriction sodium is the bottleneck that slag former is used.For addressing this problem, the present invention passes through at Na
2CO
3-SiO
2Introduce Al in the system
2O
3, through Al
2O
3The fused slag mutually in flocculation insulation, dissociate oxidation and alkaline adsorption, play insulation, keep the effect of slag making proportioning, oxidation reinforced absorption.
Wherein the flocculation insulation is meant Al
2O
3With Na
2CO
3-SiO
2The floccular scum silica frost of reaction back production semi-molten state covers and silicon liquid surface, and silicon liquid is played insulation effect, improves energy utilization ratio.
The oxidation of dissociating is meant, at Na
2CO
3-SiO
2-Al
2O
3In the ternary system, the Al of part
2O
3At Na
2O and SiO
2Down fusing of effect, dissociate a part of free oxygen, the oxidation of remaining B.
The alkalescence adsorption is meant Al
2O
3Throwing out and and Na thereof
2O reaction back generates alkaline matter NaAlO
2The alkalescence of keeping slag former helps B
2O
3Be adsorbed in the slag former effect of being convenient to remove.
Simultaneously, aluminium element and boron belong to same main group (III B), have the outer electronic structure similar with boron, and promptly the outermost electron number is identical, and there is similarity to a certain degree in its chemical property.Part B
2O
3Adsorbable in being rich in Al
2O
3Settling in.
In addition, the adding of aluminum oxide can also be played the effect of insulation, produces sodium metaaluminate with sodium oxide simultaneously, reduces the volatilization of sodium, keeps the ratio of slag former.
Compared with prior art, the present invention has following advantage:
Embodiment
Embodiment 1
The metalluragical silicon slagging boron removal method of purification that present embodiment provides contains following steps:
(1) getting B content is that silicon material 10kg about 7ppm is as raw silicon;
(2) press mass ratio 44.5:55:0.5 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former;
(3) raw silicon is dropped into be heated to 1500 ℃ in the plumbago crucible, treat that silicon liquid all melts the slag former that the back adds, and stir, be incubated the reacted slag charge in removal upper strata after 30 minutes.
(4) with prefabricated slag former according to the ratio of silicon material 1:20, promptly get the 0.5kg slag former and drop in the said silicon liquid for every batch, and carry out intermittent type and stir, mixing chamber was divided into 5 minutes, the each stirring requires silicon liquid and slag former uniform mixing.
(5) after the repetitive operation (4) 3 times, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid left standstill, time of repose is 5-10 minute, measures through inductively coupled plasma emmission spectrum (ICP-AES) method that B content is 2.56ppm in the silicon ingot.
Embodiment 2
Press mass ratio 44:55:1 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former; Selecting the metalluragical silicon material for use is raw silicon, and the initial B content of raw silicon is 7.84ppm; Raw silicon is dropped into plumbago crucible, progressively improve Medium frequency induction power the metalluragical silicon material is fused into silicon liquid; When the silicon material all melts, reduce intermediate frequency furnace power, keeping the silicon liquid temp is 1450-1550 ℃; Every batch of mass ratio by slag former and silicon material is 1:20, and mixing chamber was divided into 5 minutes, and each the stirring requires silicon liquid and slag former uniform mixing; Carry out then removing the surperficial scum silica frost of silicon liquid after the insulation reaction, adopt the graphite device to stir and strike off scum silica frost when scumming, (promptly the mass ratio by slag former and silicon material is 1:20 to the repetitive operation above-mentioned steps; The ternary slag former is added in the silicon liquid, carry out intermittent type then and stir, mixing chamber was divided into 5 minutes; Silicon liquid and slag former uniform mixing during each the stirring; And then carry out insulation reaction) after 3 times, wherein insulation reaction total time is 30-60 minute, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid is left standstill; Time of repose is 5-10 minute, is 1.79ppm through B content in inductively coupled plasma emmission spectrum (ICP-AES) the method mensuration silicon ingot.
Embodiment 3
Press mass ratio 38.5:60:1.5 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former; Selecting the metalluragical silicon material for use is raw silicon, and the initial B content of raw silicon is 9.52ppm; Raw silicon is dropped into plumbago crucible, progressively improve Medium frequency induction power the metalluragical silicon material is fused into silicon liquid; When the silicon material all melts, reduce intermediate frequency furnace power, keeping the silicon liquid temp is 1450-1550 ℃; Every batch of mass ratio by slag former and silicon material is 1:10, and mixing chamber was divided into 5 minutes, and each the stirring requires silicon liquid and slag former uniform mixing; Carry out then removing the surperficial scum silica frost of silicon liquid after the insulation reaction, adopt the graphite device to stir and strike off scum silica frost when scumming, (promptly the mass ratio by slag former and silicon material is 1:10 to the repetitive operation above-mentioned steps; The ternary slag former is added in the silicon liquid, carry out intermittent type then and stir, mixing chamber was divided into 5 minutes; Silicon liquid and slag former uniform mixing during each the stirring; And then carry out insulation reaction) after 3 times, wherein insulation reaction total time is 30-60 minute, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid is left standstill; Time of repose is 5-10 minute, is 0.24ppm through B content in inductively coupled plasma emmission spectrum (ICP-AES) the method mensuration silicon ingot.
Embodiment 4
Press mass ratio 33:65:2 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former; Selecting the metalluragical silicon material for use is raw silicon, and the initial B content of raw silicon is 9.52ppm; Raw silicon is dropped into plumbago crucible, progressively improve Medium frequency induction power the metalluragical silicon material is fused into silicon liquid; When the silicon material all melts, reduce intermediate frequency furnace power, keeping the silicon liquid temp is 1450-1550 ℃; Every batch of mass ratio by slag former and silicon material is 1:10, and mixing chamber was divided into 8 minutes, and each the stirring requires silicon liquid and slag former uniform mixing; Carry out then removing the surperficial scum silica frost of silicon liquid after the insulation reaction, adopt the graphite device to stir and strike off scum silica frost when scumming, (promptly the mass ratio by slag former and silicon material is 1:10 to the repetitive operation above-mentioned steps; The ternary slag former is added in the silicon liquid, carry out intermittent type then and stir, mixing chamber was divided into 8 minutes; Silicon liquid and slag former uniform mixing during each the stirring; And then carry out insulation reaction) after 3 times, wherein insulation reaction total time is 30-60 minute, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid is left standstill; Time of repose is 5-10 minute, is 0.81ppm through B content in inductively coupled plasma emmission spectrum (ICP-AES) the method mensuration silicon ingot.
Embodiment 5
Press mass ratio 30:65:5 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former; Selecting the metalluragical silicon material for use is raw silicon, and the initial B content of raw silicon is 6.96ppm; Raw silicon is dropped into plumbago crucible, progressively improve Medium frequency induction power the metalluragical silicon material is fused into silicon liquid; When the silicon material all melts, reduce intermediate frequency furnace power, keeping the silicon liquid temp is 1450-1550 ℃; Every batch of mass ratio by slag former and silicon material is 1:10, and mixing chamber was divided into 5 minutes, and each the stirring requires silicon liquid and slag former uniform mixing; Carry out then removing the surperficial scum silica frost of silicon liquid after the insulation reaction, adopt the graphite device to stir and strike off scum silica frost when scumming, (promptly the mass ratio by slag former and silicon material is 1:10 to the repetitive operation above-mentioned steps; The ternary slag former is added in the silicon liquid, carry out intermittent type then and stir, mixing chamber was divided into 5 minutes; Silicon liquid and slag former uniform mixing during each the stirring; And then carry out insulation reaction) after 3 times, wherein insulation reaction total time is 30-60 minute, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid is left standstill; Time of repose is 5-10 minute, is 2.55ppm through B content in inductively coupled plasma emmission spectrum (ICP-AES) the method mensuration silicon ingot.
Embodiment 6
Press mass ratio 40:55:5 mixing SiO
2, Na
2CO
3And Al
2O
3Powder is as slag former; Selecting the metalluragical silicon material for use is raw silicon, and the initial B content of raw silicon is 6.96ppm; Raw silicon is dropped into plumbago crucible, progressively improve Medium frequency induction power the metalluragical silicon material is fused into silicon liquid; When the silicon material all melts, reduce intermediate frequency furnace power, keeping the silicon liquid temp is 1450-1550 ℃; Every batch of mass ratio by slag former and silicon material is 1:10, and mixing chamber was divided into 5 minutes, and each the stirring requires silicon liquid and slag former uniform mixing; Carry out then removing the surperficial scum silica frost of silicon liquid after the insulation reaction, adopt the graphite device to stir and strike off scum silica frost when scumming, (promptly the mass ratio by slag former and silicon material is 1:10 to the repetitive operation above-mentioned steps; The ternary slag former is added in the silicon liquid, carry out intermittent type then and stir, mixing chamber was divided into 5 minutes; Silicon liquid and slag former uniform mixing during each the stirring; And then carry out insulation reaction) after 3 times, wherein insulation reaction total time is 30-60 minute, the solar-grade polysilicon after promptly obtaining to purify of casting after silicon liquid is left standstill; Time of repose is 5-10 minute, is 3.40ppm through B content in inductively coupled plasma emmission spectrum (ICP-AES) the method mensuration silicon ingot.
The foregoing description is a preferred implementation of the present invention; But embodiment of the present invention is not restricted to the described embodiments; Other any do not deviate from change, the modification done under spirit of the present invention and the principle, substitutes, combination, simplify; All should be the substitute mode of equivalence, be included in protection scope of the present invention.
Claims (8)
1. metalluragical silicon slagging boron removal method of purification is characterized in that: choose the metalluragical silicon material, be heated to and all be fused into silicon liquid, the temperature of regulating silicon liquid is 1450-1550 ℃, adds the ternary slag former then, and described ternary slag former is Na
2CO
3-SiO
2-Al
2O
3Ternary slag former, wherein Na
2CO
3The quality percentage composition be 55%-65%, Al
2O
3The quality percentage composition be 0.2%-15%, surplus is SiO
2, after stirring and insulation reaction, remove the scum silica frost on silicon liquid surface, casting after silicon liquid is left standstill to obtain the polysilicon that B content satisfies the solar level requirement.
2. metalluragical silicon slagging boron removal method of purification according to claim 1 is characterized in that containing following steps:
(1) chooses the metalluragical silicon material as raw silicon, raw silicon is heated to all is fused into silicon liquid;
(2) temperature of adjusting silicon liquid drops into prefabricated ternary slag former in the said silicon liquid in batches, and every batch of silicon liquid that adds the ternary slag former all need be removed the scum silica frost on silicon liquid surface after stirring and insulation reaction;
(3) cast after silicon liquid is left standstill and to obtain the polysilicon that B content satisfies the solar level requirement.
3. metalluragical silicon slagging boron removal method of purification according to claim 2 is characterized in that: initial B content is 6 ~ 35ppm in the metalluragical silicon material described in the step (1).
4. metalluragical silicon slagging boron removal method of purification according to claim 2; It is characterized in that: progressively improve Medium frequency induction power earlier with plumbago crucible in step (1)-step (2) the metalluragical silicon material all is fused into silicon liquid; Reduce intermediate frequency furnace power then, keep the silicon liquid temp.
5. metalluragical silicon slagging boron removal method of purification according to claim 2 is characterized in that: the weight part ratio of the every batch of ternary slag former and metalluragical silicon material is 5-10:100 in the step (2).
6. metalluragical silicon slagging boron removal method of purification according to claim 2 is characterized in that: the mode that stirs in the step (2) is that intermittent type stirs, and mixing chamber was divided into 5-10 minute.
7. metalluragical silicon slagging boron removal method of purification according to claim 2 is characterized in that: the total reaction time of ternary slag former and silicon liquid is 30-60 minute described in the step (2).
8. metalluragical silicon slagging boron removal method of purification according to claim 2 is characterized in that: time of repose is 5-10 minute in the step (3).
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| CN102267699B (en) * | 2011-06-17 | 2014-07-23 | 福建省上杭县九洲硅业有限公司 | Silicon metal purification method based on oxide high-temperature solid-phase reaction |
| CN102320610B (en) * | 2011-09-13 | 2013-02-27 | 山西纳克太阳能科技有限公司 | Method for purifying solar-grade polysilicon to remove boron |
| CN102432021B (en) * | 2011-09-16 | 2013-02-20 | 江西盛丰新能源科技有限公司 | Method for preparing polysilicon |
| CN104276572B (en) * | 2013-07-02 | 2016-08-10 | 青岛隆盛晶硅科技有限公司 | The slag former of polycrystalline silicon medium melting and using method thereof |
| CN105063749B (en) * | 2015-06-08 | 2017-07-18 | 朱超 | A kind of method for preparing high-purity polycrystalline silicon |
| CN109490059A (en) * | 2018-09-19 | 2019-03-19 | 中钢集团新型材料（浙江）有限公司 | It is a kind of to measure high purity graphite boron content pre-treating method using ICP |
| CN114890428B (en) * | 2022-04-29 | 2023-05-09 | 成都理工大学 | Ternary slag former for external refining of industrial silicon and impurity removing method thereof |
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| CN101870472B (en) * | 2010-02-09 | 2012-01-11 | 厦门大学 | Method for removing impurities of boron and phosphorus in industrial silicon by adopting rare-earth oxide |
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