CN101555015A - Purifying method and device for removing boron from polysilicon - Google Patents
Purifying method and device for removing boron from polysilicon Download PDFInfo
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- CN101555015A CN101555015A CNA2009101118086A CN200910111808A CN101555015A CN 101555015 A CN101555015 A CN 101555015A CN A2009101118086 A CNA2009101118086 A CN A2009101118086A CN 200910111808 A CN200910111808 A CN 200910111808A CN 101555015 A CN101555015 A CN 101555015A
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Abstract
A purifying method and a device for removing boron from polysilicon relate to polysilicon, and a purifying method and a device for removing boron from polysilicon are provided, and the method has low cost and simple process and is suitable for industrialized popularization. The purifying device for removing boron from polysilicon is provided with a vacuum system, an intermediate frequency sensing melting system, a secondary feeding device, a porous rotating nozzle and a graphite mould for pouring. Firstly, slag former is pre-melted, and the obtained slag is loaded into a feeding hopper; metal silicon is put into a graphite crucible, then vacuum pumping and applying the intermediate frequency sensing coil power are executed, after the metal silicon is heated and melted, the silicon liquid is kept at the temperature of 1500 to 1800 DEG C, then the porous rotating nozzle is reduced to the above of the silicon liquid surface to be pre-heated, and reaction gas is pumped; the feeding hopper is rotated, the slag former is added, then the porous rotating nozzle is reduced into the graphite crucible, and rotating paddles are started; and after the pumping and slag forming are finished, the rotating paddles are closed, the porous rotating nozzle is raised, then the gas source is closed, the silicon liquid is poured into the graphite mould for standing, after cooling, the silicon ingot is taken out, and the impurity aggregation part is removed, thus obtaining the polysilicon ingot.
Description
Technical field
The present invention relates to a kind of polysilicon, especially relate to a kind of boron-removing purification method and device that adopts the polysilicon of metallurgy method.
Background technology
Energy dilemma and traditional energy have become the main restricting factor of the society and the national economic development to the pollution of environment.For keeping Sustainable development, all actively readjusting the energy structure in countries in the world, greatly develops renewable energy source, and polysilicon solar cell becomes the focus that the whole world is paid close attention to.The technology that employing improvement Siemens Method prepares high purity polycrystalline silicon is comparatively complicated, and the cost of investment height will increase the battery price greatly with its preparation solar cell.And metallurgy method purifying polycrystalline silicon technology is simple relatively, and is with low cost, and less relatively to polluting of environment, become the main developing direction of solar-grade polysilicon.
Industrial silicon is the important source material of producing solar-grade polysilicon, but its purity often needs purification processes to remove impurity element wherein, as Al, Ca, Fe, C, P, B etc., especially nonmetallic impurity such as P, B about 2N.That be difficult to remove most in the polycrystalline silicon material is P and B, because P, the B segregation coefficient in Si is respectively 0.35,0.8, (segregation coefficient of metallic element in silicon is generally: 10 far above metallic element
-2～10
-7The order of magnitude), so, in the directional freeze purification process of routine, when silicon when liquid cooling is solidified as solid, the P and the B that rest in the solid phase are still a lot, refining effect is poor.
For P impurity, the most effective P method of removing is to utilize the vapour pressure of P under vacuum to raise and the characteristics of very fast increase with temperature, adopts the vacuum dephosphorization.For example U.S. Pat 5254300 discloses a kind of method, with molten silicon refining under reduced pressure, makes P enter gas phase, and volatilization is removed.And for B impurity, for example during 1823K, the vapour pressure of silicon is 0.40Pa, and the saturation vapour pressure of B is 6.78 * 10
-7Pa well below silicon, therefore, can't adopt the method for vacuum metling to remove B.
People such as the Kazuki Morita of Tokyo Univ Japan are at paper " Refining of Siby the solidification of Si-Al meltwith electromagnetic force " (ISIJ International, Vol.45 (2005), No.7, pp.967～971) propose under electric field action, from the Si-Al alloy melt, to solidify the method for refined silicon in, and from Theoretical Calculation and experiment measuring, draw the segregation coefficient of B in the Si-Al alloy melt and reduce significantly.And at another piece paper " Boron removal by titaniumaddition in solidification refining of silicon with Si-Al melt " (Takeshi Yoshikawa, Kentaro Arimura, Kazuki Morita, Metallurgical and Materials Transactions B, Volume 36, and Number 6,837～842,2005) propose in, in the Si-Al alloy melt, add the Ti element, can form TiB
2Precipitation is separated out.U.S. Pat 4256717 and US4312848 also disclose the similar fractional crystallization method that adopts, and add alloying element, remove the B impurity in the polysilicon.But how above method separates Si with Al, and aspects such as realization suitability for industrialized production still remain to be studied.U.S. Pat 20060123947 adopts electron beam vacuum metling, and the B impurity in the polysilicon is reduced to 25ppmw from 55ppmw.The paper of U.S. Pat 5182091 and Tomonori Kumagai etc. (Tomonori Kumagai et al.Removal of boron from metallurgical-grade silicon by applying the plasma treatment " ISIJ International; 1992; 32 (5); 630-634) all disclose a kind of method that applies plasma body to molten silicon surface; have and well remove the B effect, but above technology power consumption is big, equipment requirements is high, cost is expensive.
At present, low-cost metallurgy method is removed B and is mainly utilized the B in reactant gases and slag and the silicon liquid that oxidizing reaction takes place, and reaction product will be to contain the gas of B, such as HBO
2Form is discharged from system, or generates boron oxide compound, as BO
1.5, enter in the slag system, separate by the slag gold and remove.
U.S. Pat 20070180949 has been mentioned and a kind ofly being blown into by Ar, H from silicon liquid bottom
2, H
2O and O
2Deng the reactant gases of forming, oxidation removes the method for boron, and B can reduce to 5ppmw from 25ppmw.U.S. Pat 60844372 then adopts the natural bluster of different oxygen proportions, and feeds a small amount of Ar, H
2And H
2The mixed gas of O is reduced to 3.6ppmw with B from 8.9ppmw.U.S. Pat 6368403 points out that the reactant gases that removes B is mainly rare gas element and O such as Ar
2Deng the mixed gas of forming.
(Tanahashi et al.Distribution behavior of boron between SiO such as Tanahashi
2-saturated NaO
0.5-CaO-SiO
2Flux-molten silicon, Journal of the Mining and Materials, 2002,118 (7): 497-505) propose with Na
2O-CaO-SiO
2Be the reaction slag system, the dispersion coefficient (content of the content/B of B in slag system in silicon liquid) that draws B can reach 3.5, and in theory, through the slag making reaction, the B content in the silicon can be reduced to 0.4ppmw at most.
Japanese Patent JP2851257 also discloses a kind of by adding continuously the method for slag former in molten silicon, under 1500 ℃, adds SiO at twice
2With Na
2CO
3, B drops to 0.29ppmw from 12ppmw.
To sum up, all there is certain deficiency in main processing method at present.At first, the removal effect of B is difficult to reach the requirement of solar-grade polysilicon.Secondly, there is certain limitation in the mode that feeds gas, and ventilation member corrodes easily, or damages.And consider the viscosity of silicon liquid, the diffusion effect and the level of response of gas are unsatisfactory.And partial oxygen voltinism gas at high temperature can with pasc reaction, cause the loss of unnecessary silicon.In addition, for common slag making reaction, according to paper (Thermodynamics for removal of boron from metallurgical silicon by flux treatment, 10 of K.Suzuki and N.Sano
ThEuropean photovoltaic solar energy conference, 273-275,1991), because the dispersion coefficient of B is very little, well remove the B effect if want to obtain, must strengthen the slag former consumption, and melt back, this does not obviously meet the requirement that low-cost industrialization is produced.Though adopted the B dispersion coefficient to reach as high as 2 CaO-SiO as U.S. Pat 5788945
2Slag system, slag-metal rate still need maintain 1: 1, and slag-metal rate is too high, are inappropriate on Financial cost.
Outside last method, the technical maturity of chlorination process, the purity height discloses the method for a kind of HCl of feeding as U.S. Pat 4298423, but has bigger environment and safety problem.
In addition, belonging to cheaply that smelting process also has fused salt electrolysis process, is raw material with the industrial silicon, adds the halogenide fused salt, adds thermal electrolysis, forms high-purity siliceous deposits on negative electrode.But this technology electro-conductive material poor-performing, sedimentation rate is limited.
Summary of the invention
The objective of the invention is to the existing limitation of method at B impurity in the existing removal polysilicon, a kind of low cost is provided, technology is simple, is fit to the boron-removing purification method and the device of the solar-grade polysilicon of Industry Promotion.
Technical scheme of the present invention is to adopt the boron removal method of metallurgy method, and utilization is blown into oxidizing gas makes the boron oxidation, or adding helps the slag agent to make boron form polynary slag to remove the boron impurity in the silicon.
Polysilicon of the present invention removes the boron purifying plant and is provided with vacuum system, Medium frequency induction smelting system, secondary charging device, porous swivel nozzle and cast graphite jig.
Vacuum system is provided with mechanical sliding vane rotary pump and lobe pump, the Medium frequency induction smelting system is provided with ruhmkorff coil and plumbago crucible, ruhmkorff coil is located at the outside of plumbago crucible, the secondary charging device is located at the plumbago crucible top, the secondary charging device is provided with and adds feed bin and rotating mechanism, the porous swivel nozzle is located at the plumbago crucible top, the porous swivel nozzle is provided with rotating paddle, be provided with the ventpipe that is used to inject reactant gases in the pivoting leaf bobbin, rotating paddle and ventpipe are symmetrically distributed, the bottom of ventpipe is connected with the top of rotating paddle, and gas is blown into by the spray orifice of being located between pivoting leaf bobbin and the rotating paddle.
Cast can be provided with 4 graphite flakes with graphite jig.Rotating paddle is preferably established 6.
The porous swivel nozzle can adopt liftable porous swivel nozzle.
The boron-removing purification method of polysilicon of the present invention may further comprise the steps:
1) selecting purity for use is that the Pure Silicon Metal of 99% (2N) is a raw material;
2) with the slag former fritting, the gained slag equivalent feed bin that adds in the secondary charging device of packing into;
3) feed metal silicon is put into plumbago crucible, start mechanical sliding vane rotary pump and lobe pump and vacuumize,, connect the Medium frequency induction coil power, the Pure Silicon Metal in the heat fused plumbago crucible when vacuum tightness reaches 100Pa when following;
4) after silicon all melts, improve power, make the silicon liquid temp remain on 1500～1800 ℃, the porous swivel nozzle is reduced to the surface preheating of silicon liquid, and feed reactant gases, carry out the surface and blow;
5) rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and the porous swivel nozzle is reduced in the plumbago crucible, and start rotating paddle, stir on one side ventilation on one side;
6) after slag making to be ventilated is finished, close rotating paddle, rise the porous swivel nozzle, and close source of the gas, pour silicon liquid into cast with in the graphite jig, leave standstill, silicon ingot is taken out in the cooling back, removes impurity enriched part end to end, obtains removing the polycrystal silicon ingot after boron is purified.
Can measure except that the boron impurity content before and after the boron purification.
Described Pure Silicon Metal can be bulk or powdery.
Described slag former can be basic metal base oxide, basic metal base fluorochemical, alkaline carbonate, BaCO
3, Ba (OH)
2And SiO
2, wherein, SiO
2Content be no more than 30%.Slag former can divide 4 batches to add in the silicon liquid through fritting, and each timed interval that adds is preferably 15～20min.
The power controlled of intermediate frequency induction heating power supply is built in 20～50kW.
The porous swivel nozzle is preferably 5～10min in the time of silicon liquid surface preheating, inserts in the plumbago crucible, is preferably 20～30mm apart from the bottom, and speed of rotation is preferably 100～500rpm/min.
The reactant gases that feeds can be the mixed gas of water vapour and argon gas, and the content of water vapour is no more than 1.5%, and gas flow can be 6～24L/min, preferably can be 18～24L/min, and aeration time can be 60～120min, is preferably 90～120min.In the ventilation slagging process, vacuum tightness preferably remains on 100～500Pa.
Gordian technique of the present invention is to feed certain oxidizing atmosphere to make the B active oxidation form volatile compound under negative pressure, and help the slag agent to make B form polynary slag mutually so that realize the slag gold and separate by adding, will blow and slag making combines the purpose that can reach effective B of removal.Concrete grammar of the present invention is to make the fusing of feed metal silicon by the induction heating plumbago crucible, feeds oxidizing gas and add slag former to remove B under the rough vacuum hot conditions.Wherein, slag joins in the silicon liquid at interval by certain hour in batches, and is blown into the mixed gas of water vapour and argon gas with certain proportion, flow velocity from the porous swivel nozzle in the mode of fritting, by turning unit stir silicon liquid, make full and uniform being scattered in the silicon liquid of slag and reactant gases.
The selection of slag former of the present invention comprises:
1) provides lower melt temperature, make in slagging process, to keep molten state;
2) density of density and Pure Silicon Metal has certain difference, makes the slag of generation can float over the liquid-state silicon surface or be sunken to the bottom, so that the slag gold separates;
3) provide good mobility;
4) can improve the dispersion coefficient of B in slag system;
5) provide the oxygenant of capacity and the B in the silicon liquid fully to react;
6) can combine with ventilatory response is effective;
7) avoid introducing too much impurity.
According to the paper " Thermodynamics of boron in a silicon melt " (Metallurgicaland Materials Transactions B, Volume 25B, 1994) of K.Suzuki and N.Sano, B and slag former are as SiO
2Following reaction can take place:
B(1?in?Si)+3/4(SiO
2)＝(BO
1.5)+3/4Si(1)
Wherein, BO
1.5In basic slag system, more tend towards stability.In addition, according to paper " Estimation of water vapor solubilityin molten silicates by quadratic formalism based on the regular solution model " (Shiro Ban-Ya, Mitsutaka Hino, Tetsuya Nagasaka, ISIJ International, Vol 33, No 1,12～19,1993) calculating in feeds H in the high alkalinity slag
2O can effectively increase the OH in the melt
-The concentration of ion and free oxygen is for forming the BOH volatilization and forming B
2O
3Enter slag more advantageous conditions is provided mutually.
Therefore, the selected slag system of the present invention is mainly by basic metal base oxide, alkaline carbonate and SiO
2Deng composition, by control alkalimetal oxide and SiO
2Ratio with guarantee slag system be alkalescence.Simultaneously, for basicity, fusing point, viscosity and the density of regulation system, can select to increase BaCO
3, Ba (OH)
2, CaF
2Deng.
The selection of reactant gases of the present invention, by above analysis, the gases used small amount of H that contains of the purifying reaction that the present invention is blown into
2O, and with silica-based rare gas element that does not react such as Ar as carrier gas.
Adopt boron-removing purification method of the present invention, can make the highest 0.1ppmw of being reduced to of content of B, meet the purity requirement of solar-grade polysilicon.
Compare with the B method and apparatus that removes of existing solar-grade polysilicon, air blowing of the present invention and slag making are carried out simultaneously, and by stirring, accelerated reaction is with the B oxidation of impurities in the liquid-state silicon, the boron oxide compound of generation, can enter in the slag system on the one hand, after reaching thermodynamic(al)equilibrium,, realize that the slag gold separates through cooling; On the other hand, form that can also boron-containing gas is discharged from system, all can reach the effect except that B.The liftable porous swivel nozzle that is adopted, rotary blowing method in the Aluminium industry is applied in the silicon purifying technique, can increase substantially airshed, do not splash and do not produce silicon liquid, simultaneously, under the violent stirring effect of rotating paddle, can obviously improve the degree of scatter of reactant gases and slag former, make with silicon liquid fully to contact, strengthen and remove the B effect, this respect is at present domestic does not see that as yet relevant report is arranged.Above technological operation is simple, and device can be transformed by traditional intermediate frequency furnace, and cost is low, and environmental pollution is little, is convenient to Industry Promotion, has very considerable market outlook.
Description of drawings
Fig. 1 is the structural representation that the solar-grade polysilicon of the embodiment of the invention removes the boron purifying plant.
Fig. 2 is the structural representation that the solar-grade polysilicon of the embodiment of the invention removes the porous swivel nozzle of boron purifying plant.
Embodiment
Referring to Fig. 1 and 2, polysilicon of the present invention is provided with vacuum system (not drawing among the figure), Medium frequency induction smelting system 1, secondary charging device 4, porous swivel nozzle 5 except that the boron purifying plant and pours into a mould with graphite jig (not drawing among the figure).
Vacuum system is provided with mechanical sliding vane rotary pump and lobe pump, Medium frequency induction smelting system 1 is provided with ruhmkorff coil 2 and plumbago crucible 3, ruhmkorff coil 2 is located at the outside of plumbago crucible 3, secondary charging device 4 is located at plumbago crucible 3 tops, secondary charging device 4 is provided with 4 and adds feed bin and rotating mechanism, can realize batch charging by rotating mechanism.Porous swivel nozzle 5 is located at plumbago crucible 3 tops, porous swivel nozzle 5 is provided with rotating paddle 7, be provided with the ventpipe 6 that is used to inject reactant gases in the pivoting leaf bobbin, rotating paddle 7 is symmetrically distributed with ventpipe 6, the bottom of ventpipe 6 is connected with the top of rotating paddle 7, and gas is blown into by the spray orifice of being located between pivoting leaf bobbin and the rotating paddle 8.
Cast can be provided with 4 graphite flakes with graphite jig.Rotating paddle is preferably established 6.
Porous swivel nozzle 5 can adopt liftable porous swivel nozzle.
Below provide some embodiment of the boron-removing purification method of solar-grade polysilicon of the present invention.
1) takes by weighing the feed metal silicon 10kg that B concentration is about 10ppmw.
2) mixed C aO, CaF according to a certain ratio
2, BaO, SiO
2Powder makes CaO, CaF as slag former
2, BaO, SiO
2The composition ratio be 60: 9: 6: 25.The weight ratio of slag former and raw silicon is 1.5: 10 (slag-metal rate is 0.15), i.e. 1.5kg.
3) slag former is carried out fritting after, four of packing in the secondary charging device of gained slag equivalent add feed bin.
4) feed metal silicon is put into plumbago crucible, start mechanical sliding vane rotary pump and lobe pump and vacuumize, when vacuum tightness reaches 100Pa, connect the Medium frequency induction coil power, power melts up to silicon fully at 25kw.
5) improve power to 30kw, make the silicon liquid temp reach 1600 ℃, the porous swivel nozzle is reduced to silicon liquid surface preheating 10min, and feed 99.5%Ar+0.5%H
2O, H
2O content can be controlled by wet bulb thermometer, carries out the surface and blows.
6) rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and each timed interval that adds is 15min.The porous swivel nozzle is reduced to apart from about 30mm place, plumbago crucible bottom, and air flow is 12L/min, and aeration time is 60min, and speed of rotation is 200rpm.
7) after slag making to be ventilated is finished, close rotating paddle, rise the porous swivel nozzle, and close source of the gas.Pour silicon liquid into cast with in the graphite jig, leave standstill, silicon ingot is taken out in the cooling back, remove end to end part each 1/10, record by sims (SIMS) that B content is 0.52ppmw in the polycrystal silicon ingot.
Technological process is with embodiment 1.The weight ratio of slag former and raw silicon is 3: 10 (slag-metal rate is 0.3), i.e. 3kg.After treating that silicon all melts, improve power, make the silicon liquid temp reach 1650 ℃, the porous swivel nozzle is reduced to silicon liquid surface preheating 5min, and feed 98.5%Ar+1.5%H to 35kw
2O carries out the surface and blows.Rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and each timed interval that adds is 20min.The porous swivel nozzle is reduced to apart from about 30mm place, plumbago crucible bottom, and air flow is 18L/min, and aeration time is 90min, and speed of rotation is 300rpm.
Treat that silicon liquid pours cast into in the graphite jig, leave standstill that silicon ingot is taken out in the cooling back, remove end to end part each 1/10, record by sims (SIMS) that B content is 0.34ppmw in the polycrystal silicon ingot.
Technological process is with embodiment 1.Mixed C aCO according to a certain ratio
3, CaF
2, Ba (OH)
2, SiO
2Powder makes CaCO as slag former
3, CaF
2, Ba (OH)
2, SiO
2The composition ratio be 55: 7: 8: 30.The weight ratio of slag former and raw silicon is 3: 10 (slag-metal rate is 0.3), i.e. 3kg.After treating that silicon all melts, improve power, make the silicon liquid temp reach 1700 ℃, the porous swivel nozzle is reduced to silicon liquid surface preheating 5min, and feed 99.25%Ar+0.75%H to 40kw
2O carries out the surface and blows.Rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and each timed interval that adds is 20min.The porous swivel nozzle is reduced to apart from about 20mm place, plumbago crucible bottom, and air flow is 24L/min, and aeration time is 120min, and speed of rotation is 450rpm.Treat that silicon liquid pours cast into in the graphite jig, leave standstill that silicon ingot is taken out in the cooling back, remove end to end part each 1/10, record by sims (SIMS) that B content is 0.11ppmw in the polycrystal silicon ingot.
Technological process is with embodiment 1.Metallic silicon raw material 50kg, mixed C aO, CaF according to a certain ratio
2, SiO
2Powder makes CaO, CaF as slag former
2, SiO
2The composition ratio be 60: 10: 30.The weight ratio of slag former and raw silicon is 3: 10 (slag-metal rate is 0.3), i.e. 15kg.After treating that silicon all melts, improve power, make the silicon liquid temp reach 1750 ℃, the porous swivel nozzle is reduced to silicon liquid surface preheating 5min, and feed 99%Ar+1%H to 45kw
2O carries out the surface and blows.Rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and each timed interval that adds is 20min.The porous swivel nozzle is reduced to apart from about 20mm place, plumbago crucible bottom, and air flow is 24L/min, and aeration time is 100min, and speed of rotation is 500rpm.Treat that silicon liquid pours cast into in the graphite jig, leave standstill that silicon ingot is taken out in the cooling back, remove end to end part each 1/10, record by sims (SIMS) that B content is 0.45ppmw in the polycrystal silicon ingot.
Technological process is with embodiment 1.Mixed C a (OH) according to a certain ratio
2, CaF
2, Ba (OH)
2, SiO
2Powder makes Ca (OH) as slag former
2, CaF
2, Ba (OH)
2, SiO
2The composition ratio be 52: 7: 8: 33.The weight ratio of slag former and raw silicon is 3: 10 (slag-metal rate is 0.3), i.e. 3kg.After treating that silicon all melts, improve power, make the silicon liquid temp reach 1800 ℃, the porous swivel nozzle is reduced to silicon liquid surface preheating 5min, and feed 99.5%Ar+0.5%H to 50kw
2O carries out the surface and blows.Rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and each timed interval that adds is 20min.The porous swivel nozzle is reduced to apart from about 20mm place, plumbago crucible bottom, and air flow is 20L/min, and aeration time is 120min, and speed of rotation is 500rpm.Treat that silicon liquid pours cast into in the graphite jig, leave standstill that silicon ingot is taken out in the cooling back, remove end to end part each 1/10, record by sims (SIMS) that B content is 0.22ppmw in the polycrystal silicon ingot.
Comparative Examples 1
Except not adding the slag former, under the condition similar, carry out 2h and handle to embodiment 3, the B content of measuring after the melting is 3.95ppmw.
Comparative Examples 2
Except not feeding the oxidizing gas, under the condition similar, carry out 2h and handle to embodiment 3, the B content of measuring after the melting is 1.71ppmw.
Comparative Examples 3
Except not making rotating paddle rotation, stirring, under the condition similar, carry out 1h and handle to embodiment 3, the B content of measuring after the melting is 1.17ppmw.
Comparative Examples 4
Except with slag former without fritting, directly mix outside the disposable adding molten silicon, under the condition similar, carry out 1h and handle to embodiment 3, the B content of measuring after the melting is 0.99ppmw.
Claims (10)
1. polysilicon removes the boron purifying plant, it is characterized in that being provided with vacuum system, Medium frequency induction smelting system, secondary charging device, porous swivel nozzle and cast graphite jig; Vacuum system is provided with mechanical sliding vane rotary pump and lobe pump, the Medium frequency induction smelting system is provided with ruhmkorff coil and plumbago crucible, ruhmkorff coil is located at the outside of plumbago crucible, the secondary charging device is located at the plumbago crucible top, the secondary charging device is provided with and adds feed bin and rotating mechanism, the porous swivel nozzle is located at the plumbago crucible top, the porous swivel nozzle is provided with rotating paddle, be provided with the ventpipe that is used to inject reactant gases in the pivoting leaf bobbin, rotating paddle and ventpipe are symmetrically distributed, the bottom of ventpipe is connected with the top of rotating paddle, and gas is blown into by the spray orifice of being located between pivoting leaf bobbin and the rotating paddle.
2. polysilicon as claimed in claim 1 removes the boron purifying plant, it is characterized in that cast is provided with 4 graphite flakes with graphite jig.
3. polysilicon as claimed in claim 1 removes the boron purifying plant, it is characterized in that rotating paddle establishes 6.
4. the boron-removing purification method of a polysilicon is characterized in that may further comprise the steps:
1) selecting purity for use is that 99% Pure Silicon Metal is a raw material;
2) with the slag former fritting, the gained slag equivalent feed bin that adds in the secondary charging device of packing into;
3) feed metal silicon is put into plumbago crucible, start mechanical sliding vane rotary pump and lobe pump and vacuumize,, connect the Medium frequency induction coil power, the Pure Silicon Metal in the heat fused plumbago crucible when vacuum tightness reaches 100Pa when following;
4) after silicon all melts, improve power, make the silicon liquid temp remain on 1500～1800 ℃, the porous swivel nozzle is reduced to the surface preheating of silicon liquid, and feed reactant gases, carry out the surface and blow;
5) rotation adds feed bin, adds the slag former of fritting in silicon liquid in batches, and the porous swivel nozzle is reduced in the plumbago crucible, and start rotating paddle, stir on one side ventilation on one side;
6) after slag making to be ventilated is finished, close rotating paddle, rise the porous swivel nozzle, and close source of the gas, pour silicon liquid into cast with in the graphite jig, leave standstill, silicon ingot is taken out in the cooling back, removes impurity enriched part end to end, obtains removing the polycrystal silicon ingot after boron is purified.
5. the boron-removing purification method of a kind of polysilicon as claimed in claim 5 is characterized in that described Pure Silicon Metal is bulk or powdery.
6. the boron-removing purification method of a kind of polysilicon as claimed in claim 5 is characterized in that described slag former is basic metal base oxide, basic metal base fluorochemical, alkaline carbonate, BaCO
3, Ba (OH)
2And SiO
2, wherein, SiO
2Content be no more than 30%.
7. the boron-removing purification method of kind of polysilicon as claimed in claim 5 is characterized in that slag former through fritting, divides 4 batches to add in the silicon liquid, and each timed interval that adds is 15～20min.
8. the boron-removing purification method of a kind of polysilicon as claimed in claim 5, it is characterized in that the porous swivel nozzle is 5～10min in the time of silicon liquid surface preheating, inserting in the plumbago crucible, is 20～30mm apart from the bottom, and speed of rotation is 100～500rpm/min.
9. the boron-removing purification method of a kind of polysilicon as claimed in claim 5 is characterized in that the reactant gases that feeds is the mixed gas of water vapour and argon gas, and the content of water vapour is no more than 1.5%.
10. the boron-removing purification method of a kind of polysilicon as claimed in claim 5 is characterized in that gas flow is 6～24L/min, and aeration time is 60～120min, and in the ventilation slagging process, vacuum tightness remains on 100～500Pa.
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Cited By (15)
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| CN101955186A (en) * | 2010-09-19 | 2011-01-26 | 江西盛丰新能源科技有限公司 | Method for preparing polycrystalline silicon by physically removing boron |
| CN102134075A (en) * | 2011-01-24 | 2011-07-27 | 云南乾元光能产业有限公司 | Novel method for producing solar-grade polysilicon |
| CN101698481B (en) * | 2009-10-22 | 2011-08-10 | 厦门大学 | Solar-grade polysilicon purifying device and solar-grade polysilicon purifying method |
| 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 |
| CN102344142A (en) * | 2010-07-26 | 2012-02-08 | 比亚迪股份有限公司 | Method for purifying silicon through removing boron |
| CN101724900B (en) * | 2009-11-24 | 2012-05-23 | 厦门大学 | Device and method for purifying polycrystalline silicon |
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| CN101698481B (en) * | 2009-10-22 | 2011-08-10 | 厦门大学 | Solar-grade polysilicon purifying device and solar-grade polysilicon purifying method |
| CN101724900B (en) * | 2009-11-24 | 2012-05-23 | 厦门大学 | Device and method for purifying polycrystalline silicon |
| 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 |
| CN102344142A (en) * | 2010-07-26 | 2012-02-08 | 比亚迪股份有限公司 | Method for purifying silicon through removing boron |
| CN101955186A (en) * | 2010-09-19 | 2011-01-26 | 江西盛丰新能源科技有限公司 | Method for preparing polycrystalline silicon by physically removing boron |
| CN102134075A (en) * | 2011-01-24 | 2011-07-27 | 云南乾元光能产业有限公司 | Novel method for producing solar-grade polysilicon |
| CN102616787A (en) * | 2012-03-22 | 2012-08-01 | 厦门大学 | Method for removing boron-phosphorus impurities from silicon metal |
| CN103265035A (en) * | 2013-06-05 | 2013-08-28 | 青岛隆盛晶硅科技有限公司 | Method for realizing convection agitation of silicon slag in medium smelting |
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| CN103274417A (en) * | 2013-06-05 | 2013-09-04 | 青岛隆盛晶硅科技有限公司 | Continuous slag-feeding and slag-discharging device in polycrystalline silicon medium smelting process |
| 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 |
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| CN103771419A (en) * | 2014-01-10 | 2014-05-07 | 黑河合盛光伏科技有限公司 | Method for removing boron in polycrystalline silicon |
| CN103771419B (en) * | 2014-01-10 | 2016-03-30 | 合盛硅业股份有限公司 | A kind of method removing boron in polysilicon |
| CN105540593A (en) * | 2015-12-31 | 2016-05-04 | 厦门大学 | Boron removal method and device through activated slag agent |
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| CN108128778A (en) * | 2018-01-30 | 2018-06-08 | 青岛蓝光晶科新材料有限公司 | A kind of method of boron in vapor auxiliary electron beam melting removal silicon |
| CN108128778B (en) * | 2018-01-30 | 2021-02-05 | 青岛蓝光晶科新材料有限公司 | Method for removing boron in silicon by steam-assisted electron beam melting |
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