CN103072998A - Method for preparing low-phosphorus-boron polycrystalline silicon through two-man ladle refining - Google Patents
Method for preparing low-phosphorus-boron polycrystalline silicon through two-man ladle refining Download PDFInfo
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Abstract
The invention relates to a method for preparing low-phosphorus-boron polycrystalline silicon through two-man ladle refining. The method comprises the following steps that 1, slag formers are filled in a graphite crucible of an intermediate frequency furnace for melting, slag liquid is obtained, and the heat insulation is carried out; 2, in the silicon liquid outlet process of a submerged arc furnace, mixed gas of air and oxygen is continuously introduced into the bottom of a two-man ladle; 3, when the silicon liquid outlet is completed, slag liquid in the graphite crucible of the intermediate frequency furnace is poured into the two-man ladle, and meanwhile, oxidation mixed gas is introduced into the two-man ladle for refining; and 4, after the two-man ladle refining, silicon slag together with the mixture is poured into a crystallizer for realizing the silicon slag separation, and purified low-phosphorus-boron polycrystalline silicon raw materials are obtained. The method has the characteristics that energy sources are fully utilized and saved, the phosphorus and boron removal effect is good, the environment is not polluted, and the like.
Description
Technical field
The present invention relates to a kind of polycrystalline silicon purifying technical field, particularly relate to the method that a kind of refining of two-maing ladle prepares low-phosphorous boron polysilicon.
Background technology
Photovoltaic energy is 21 century one of most important new forms of energy.In recent years, whole world photovoltaic industry high speed development, the standby technology of solar energy polycrystalline silicon new system and the technique of developing low-cost, less energy-consumption all is devoted to, such as improved Siemens, new silane thermal decomposition process, vulcanization bed method, metallurgy method etc. in order to satisfy developing rapidly of photovoltaic industry in countries in the world.Wherein, metallurgy method purifying polycrystalline silicon technique is relatively simple, with low cost, and the pollution on the environment less, has become the main development direction of solar-grade polysilicon.
Normal intermediate frequency furnace slag making, raw material are solid industrial silicon (two-man ladle connect silicon liquid solidify after), and its principle is boron to be oxidized to boron oxide enter SiO
2In the slag, technical process is: the heating SiClx---is thrown slag former, fusing---and is poured out silicon and slag, solidifies.
For the P in the metallurgy-prepared polysilicon, B, because segregation coefficient is large, a difficult problem that is difficult to remove, most domestic producer generally adopts plasma or slagging boron removal technology, solid metal silicon after mine heat furnace smelting out solidified carries out the refuse refining, and energy consumption is large, and cost is high.Therefore, how to take full advantage of the heat that mineral hot furnace goes out silicon liquid, mode in two-man ladle middle employing ventilation and slag making is further removed troublesome impurity P, B, Al, Ca in the silicon, avoid again the thermal losses of SiClx, save electric energy and further reduce cost, and the slag former consumption height of two-maing ladle and not having heat supply and causing, easily sticking bag, the problem such as can not melt fully, be a difficult problem in the metallurgy-prepared polysilicon purifying technique.
Patent CN102344142A discloses a kind of silicon method of purification of removing boron, becomes silicon liquid by silicon being heated refuse, adopts the method for ventilation and slag making to remove boron impurity in the silicon.Patent CN101671023A discloses a kind of boron-removing purification method of polysilicon, by adopting the intermediate frequency furnace induction heating silicon is fused into silicon liquid, removes boron impurity in the silicon by the secondary slag making.Above-mentioned patent all adopts the method with the silicon refuse, and further purifying polycrystalline silicon consumes energy greatly, and cost is high.
Patent CN102583389A discloses a kind of method of purifying industrial silicon through external refining, mixes refining gas and with SiO by blowing in carrying the two-maing ladle of heating system
2-CaO is the gas-solid mixture of the compound slag system of basic slag, realizes that stove is outer concise.Owing to carry two-maing ladle of heating system, difficult design, fragile, cost is high and SiO
2The compound slag system of-CaO is poor except effect of boron, and consumption is many, is not suitable for industrial popularization.
CN102001662A discloses a kind of method of comprehensive utilization of removing boron from industrial silicon, phosphorus and other impurity, and the method is for adopting hydrometallurgy, oxidative slagging and electron beam melting to remove boron, phosphorus and other impurity in the polysilicon.Comprise: the impurity of removing in the silicon with hydrometallurgy pickling mode obtains low impurity polysilicon, with Frequency Induction Heating low impurity polysilicon is carried out the oxidative slagging melting again, by the boron impurities in the mode of oxidizing removal polysilicon of slag former, thereby obtain low boron polysilicon, the phosphorus impurities of again removing in the low boron polysilicon with electron beam melting obtains the low low-phosphorous polysilicon of boron of low metal.The slag former of using in this method is Na
2CO
3-SiO
2-Ca system.Using this method can be with 2～3N industrial silicon of B content 5～10ppm, P content 40～70PPM, metals content impurity 2000～3000ppm, produce the high purity polycrystalline silicon of B＜0.3ppm, P＜0.5PPM, metallic impurity＜1ppm by a series of composite technology flow processs such as hydrometallurgy, oxidative slagging, electron beam meltings, and then the ingot casting that reaches solar-grade polysilicon enters the furnace charge service requirements.The method complex operation step, and slag former directly dropped in the silicon liquid, loss is large.
CN102583386A discloses the method that a kind of muriatic slag system that mixes is removed the boron from industrial silicon phosphorus impurities, relates to the method for purification of industrial silicon.Industrial silicon is added in the plumbago crucible; Start the medium frequency induction power supply heating, add successively slag former in plumbago crucible by increased power; Behind material melting, holding power is constant, and temperature of reaction is controlled at 1600～1800 ℃, makes silicon liquid and slag former hybrid reaction; After the slag making fully, reduce IF-FRE, slag system is poured into answered in the water receiving case, silicon separates substantially with slag after the water-cooled, and sampling is measured B in the silicon, P foreign matter content through plasma inductance coupling spectrometer analysis.Described slag former component is mainly Na
2CO
3-SiO
2-RCl(CaCl
2, MgCl
2, AlCl
3), the special role of the muriate component of passing through to add, and in conjunction with new technical process, low energy drops to 0.2ppm with the content of impurity B in the polysilicon, and the content of P drops to 1ppm.But because muriatic characteristics are volatile, adopt the solid chloride slag former directly to drop in the industrial silicon, loss is large.
In sum, for the heat that how to take full advantage of mineral hot furnace and go out silicon liquid, it is difficult except nonmetallic impurity impurity P, B and metallic impurity Al, Ca further to remove in the silicon in the mode of two-man ladle middle employing ventilation and slag making, avoid again the thermal losses of SiClx, save electric energy and further reduce cost, and the slag former consumption of can't heat supply and causing of two-maing ladle high, change that the quantity of slag is few, easily the sticking problem such as wrap, can not melt does not fully propose good innovative approach, in view of this, special proposition the present invention.
Summary of the invention
, slag former high for the energy loss of avoiding again SiClx, cost is poor and consumption is many except effect of boron, the object of the present invention is to provide a kind of refining of two-maing ladle to prepare the method for low-phosphorous boron polysilicon.The method employing will mix slag system and drop in the composite crucible that is comprised of plumbago crucible and alumina brick, and by the intermediate frequency furnace induction melting, the CO that produces is decomposed in insulation in the avoiding slag process
2Corrosion to the top plumbago crucible; Mineral hot furnace goes out silicon finish after, in two-maing ladle by utilization two-man ladle middle silicon fluid residual heat, with mixing slag system and the oxidizing gas of basic carbonate, alkali metal chloride and silicon-dioxide silicon liquid is carried out refining, remove significantly P in the silicon, B and metallic impurity.
For realizing purpose of the present invention, the present invention adopts following technical scheme:
A kind of refining of two-maing ladle prepares the method for low-phosphorous boron polysilicon, and wherein, described method may further comprise the steps:
1) slag former is packed into heat fused in the intermediate frequency furnace plumbago crucible obtains slag night, insulation;
2) go out in the silicon liquid process in mineral hot furnace, continue to pass into the mixed gas of air and oxygen to the bottom of two-maing ladle;
3) after going out silicon liquid and finishing, the slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, pass into the oxidisability mixed gas in two-man ladle simultaneously and carry out refining;
4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
Can't heat supply for two-maing ladle, change the few shortcoming of the quantity of slag, the present invention at first adopts melts slag former in advance in the intermediate frequency furnace plumbago crucible, not only solved two-man ladle can't heat supply, change the few shortcoming of the quantity of slag, and solved that the slag former consumption is large, easily sticking the problem such as to wrap, can not melt fully, make the refining of two-maing ladle more abundant, the dephosphorization effect of boron is better; And then, the present invention goes out in the silicon liquid process in mineral hot furnace, pass into the mixed gas of air and oxygen to the bottom of two-maing ladle, after going out silicon liquid and finishing, slag poured into night two-man ladle, in two-maing ladle, directly silicon liquid is carried out slag making, save the energy consumption of SiClx process, and made by refractory brick owing to two-man ladle, cost is low; And in slag making, the present invention is in conjunction with passing into the oxidizing gas such as chlorine in two-man ladle, and removal effect is better, and the while rolls at the middle silicon liquid of two-maing ladle always, and is more abundant to contacting of silicon and slag, produced boron phosphorus low-boiling compound, such as boron chloride etc., and volatile removing.
The refining of two-maing ladle provided by the present invention prepares in the method for low-phosphorous boron polysilicon, wherein, slag former described in the step 1) is the composition of alkaline carbonate, alkali metal chloride and silicon-dioxide, its composition is by mass percentage: alkali metal chloride is 5%～10%, and surplus is alkaline carbonate and SiO
2, wherein alkaline carbonate and SiO
2Mass ratio be 1:1.
CN102583386A discloses the muriatic slag system Na of a kind of doping
2CO
3-SiO
2-RCl(CaCl
2, MgCl
2, AlCl
3) remove the method for boron from industrial silicon phosphorus impurities, the method is directly the solid-state chloride slag former to be dropped in the industrial silicon, but because muriatic characteristics are volatile, adopts the solid chloride slag former directly to drop in the industrial silicon, loses very large.For this, the present invention adopts the fritting slag former, and again deslagging has reduced loss.Simultaneously, the present invention adopts alkaline carbonate oxide compound, alkali metal chloride and SiO
2The simultaneously refining of slag system mixture and oxidizing gas is oxidized to boron oxide with the boron in the silicon and enters slag system, and the boron chloride (12.5 ℃ of boiling points) that generates simultaneously is volatile, and the slag system cost is low, pollutes and lacks, and is conducive to extensive Industry Promotion; And the muriate that mixes is alkali metal chloride, and is stronger to the chlorion ionizing power.
Further, described basic carbonate is Na
2CO
3Or K
2CO
3In one or both combination;
Described alkali metal chloride is one or both the combination among NaCl or the KCl.
Although sodium-chlor, Repone K boiling point are lower, more volatile, the easier large problem that causes damage, the present invention has solved this problem well by the method for fritting slag former.
Among the present invention, the insulation described in the step 1) is for keeping the slag liquid temp in 1450～1600 ℃ of scopes.
Step 2) in going out silicon liquid process, the mass ratio of the slag liquid of control silicon liquid and step 1) is 1:0.5～2 in, preferred 1:0.5～1.5, more preferably 1:0.5～1.
In the mixed gas of the air step 2) and oxygen, the volume ratio of oxygen and air is 0.1～1:1, and concrete ratio can be adjusted according to the temperature of silicon liquid.
The ventilation flow rate of the mixed gas of described air and oxygen is 5～12m
3/ h, pressure 3～9atm, aeration time are 2～3h.
Oxidisability mixed gas described in the step 3) is the mixed gas of chlorine, oxygen and nitrogen.
Further, the composition of described oxidisability mixed gas by volume per-cent is: chlorine 40～60%, and oxygen 20～30%, surplus is nitrogen; Preferred chlorine 50～60%, oxygen 20～25%, surplus is nitrogen; More preferably chlorine 60%, oxygen 20%, and surplus is nitrogen; Its ventilation flow rate is 5～12m
3/ h, pressure 3～9atm, aeration time are 1～3h.
The refining of two-maing ladle provided by the present invention prepares in the method for low-phosphorous boron polysilicon, and the structure of the intermediate frequency furnace plumbago crucible described in step 1) and the step 3) is comprised of bottom plumbago crucible and top alumina brick.Avoided like this changing the CO that the slag former decomposition produces in the slag process
2Corrosion top plumbago crucible.
Crystallizer described in the step 4) is by the graphite cake assembly unit, and outside device with lagging material.
Adopt the refining of two-maing ladle of the present invention to prepare the method for low-phosphorous boron industrial silicon, can significantly remove P in the silicon, B and metallic impurity, reach in the silicon metallic impurity Fe content to 560ppm, the Al content is to 42ppm, the Ca content is to 11ppm, nonmetallic impurity B content is to 0.3ppm, and the P content is to 1ppm, thus the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
The present invention compared with prior art has the following advantages:
1, the present invention adopts the refining of two-maing ladle can take full advantage of the self heat of molten silicon, has reduced the again energy consumption of SiClx, reduces cost;
2, the present invention adopts alkaline carbonate, alkali metal chloride and SiO2 slag system mixture and simultaneously refining of oxidizing gas, boron in the silicon is oxidized to boron oxide enters slag system, the boron chloride (12.5 ℃ of boiling points) that generates simultaneously is volatile, the slag system cost is low, pollute and lack, be conducive to extensive Industry Promotion;
3, the medium-frequency induction furnace plumbago crucible of the present invention's employing is comprised of bottom plumbago crucible and top alumina brick, has avoided like this changing the CO that the slag former decomposition produces in the slag process
2Corrosion top plumbago crucible;
4, the present invention is by intermediate frequency furnace fritting slag former, and it is few to have solved the slag former consumption, and easy sticking bag such as can not melt fully at the problem, makes the refining of two-maing ladle more abundant, and the dephosphorization effect of boron is good;
5, the technological operation of the present invention's employing is simple, pollution-free, can realize cleaner production, meets metallurgical requirement.
Description of drawings
Fig. 1 is the intermediate frequency furnace plumbago crucible that a kind of refining of two-maing ladle of the present invention prepares low-phosphorous boron polysilicon;
Fig. 2 is that a kind of refining of two-maing ladle of the present invention prepares two-maing ladle of low-phosphorous boron polysilicon;
Wherein:
1---alumina brick, 2---the brickwork material, 3---liquid slag, 4---plumbago crucible, 5---intermediate frequency furnace, 6---two-man ladle 7---ventpipe.
Embodiment
Below be the specific embodiment of the present invention, described embodiment is in order to further describe the present invention, rather than restriction the present invention.
Embodiment 1
(1) takes by weighing mixing slag system 1t, mix slag system Na
2CO
3-NaCl-SiO
2Component is by weight percentage: Na
2CO
3Be that 47.5%, NaCl is 5%, SiO
2Be 47.5%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1450 ℃ of slag liquid temps;
(2) go out in the silicon liquid process in mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag liquid and silicon liquid is 0.5, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, in the described mixed gas oxygen and air by volume per-cent be 0.1:1, ventilation flow rate is 5m
3/ h, pressure 3atm, aeration time are 2h;
(3) after going out silicon liquid and finishing, pour the slag liquid in the intermediate frequency furnace crucible into the middle continuation refining of two-maing ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 40%, oxygen is 20%, and nitrogen is 40%, and ventilation flow rate is 5m
3/ h, pressure 3atm, aeration time are 1h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B1; After A1 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 1:
Table 1
| Ppm/ unit | P | B | Fe | Al | Ca |
| A1 | 8.0 | 1.1 | 750 | 400 | 30 |
| B1 | 0.9 | 0.29 | 560 | 38 | 12 |
Embodiment 2
(1) takes by weighing mixing slag system 4t, mix slag system K
2CO
3-KCl-SiO
2Component is by weight percentage: K
2CO
3Be that 45%, KCl is 10%, SiO
2Be 45%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1600 ℃ of slag liquid temps;
(2) mineral hot furnace goes out in the silicon liquid process, control silicon liquid quality is 2t, guarantees that the mass ratio of slag liquid and silicon liquid is 1:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, in the described mixed gas oxygen and air by volume per-cent be 1:1, ventilation flow rate is 12m
3/ h, pressure 9atm, aeration time are 3h;
(3) after going out silicon liquid and finishing, pour the slag liquid in the intermediate frequency furnace crucible into the middle continuation refining of two-maing ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 60%, and oxygen is 30%, and nitrogen is 10%,, ventilation flow rate is 12m
3/ h, pressure 9atm, aeration time are 3h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B2; After A2 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 2:
Table 2
| Ppm/ unit | P | B | Fe | Al | Ca |
| A2 | 10.5 | 2.5 | 730 | 410 | 33 |
| B2 | 0.6 | 0.22 | 506 | 30 | 8 |
Embodiment 3
(1) takes by weighing mixing slag system 2t, mix slag system Na
2CO
3-K
2CO
3-NaCl-KCl-SiO
2Component is by weight percentage: Na
2CO
3Be 23%, K
2CO
3Be that 23%, NaCl is that 4%, KCl is 4%, SiO
2Be 46%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1550 ℃ of slag liquid temps;
(2) go out in the silicon liquid process in mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag liquid and silicon liquid is 2:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, in the described mixed gas oxygen and air by volume per-cent be 0.5:1, ventilation flow rate is 10m
3/ h, pressure 6atm, aeration time are 2.5h;
(3) after going out silicon liquid and finishing, pour the slag liquid in the intermediate frequency furnace crucible into the middle continuation refining of two-maing ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 50%, oxygen is 25%, and nitrogen is 25%, and ventilation flow rate is 10m
3/ h, pressure 6atm, aeration time are 2h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B3; After A3 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 3:
Table 3
| Ppm/ unit | P | B | Fe | Al | Ca |
| A3 | 9.2 | 1.6 | 762 | 420 | 32 |
| B3 | 0.8 | 0.28 | 550 | 33 | 9 |
Embodiment 4
(1) takes by weighing slag former 1t, slag former Na
2CO
3-KCl-SiO
2Component is by weight percentage: Na
2CO
3Be that 46.5%, KCl is 7%, SiO
2Be 46.5%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1500 ℃ of slag temperature at night;
(2) go out in the silicon liquid process in mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag night and silicon liquid is 1.2:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, the volume ratio of oxygen and air is 0.8:1 in the described mixed gas, and ventilation flow rate is 7m
3/ h, pressure 5atm, aeration time are 2.8h;
(3) after going out silicon liquid and finishing, slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 55%, oxygen is 28%, and nitrogen is 17%, and ventilation flow rate is 8m
3/ h, pressure 7atm, aeration time are 2.2h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates, the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying, wherein said crystallizer are by graphite cake assembly unit, outside device with lagging material.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B4; After A4 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 4:
Table 4
| Ppm/ unit | P | B | Fe | Al | Ca |
| A | 8.2 | 1.2 | 751 | 418 | 32 |
| B1 | 0.9 | 0.29 | 540 | 37 | 10 |
Embodiment 5
(1) takes by weighing slag former 1t, slag former Na
2CO
3-K
2CO
3-KCl-SiO
2Component is by weight percentage: Na
2CO
3Be 22.5%, K
2CO
3Be that 22.5, KCl is 10%, SiO
2Be 45%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible of packing into, obtain slag night, and keep 1510 ℃ of slag temperature at night;
(2) go out in the silicon liquid process in mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag night and silicon liquid is 1.5:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, the volume ratio of oxygen and air is 0.8:1 in the described mixed gas, and ventilation flow rate is 7m
3/ h, pressure 5atm, aeration time are 2.8h;
(3) after going out silicon liquid and finishing, slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 50%, oxygen is 25%, and nitrogen is 25%, and ventilation flow rate is 8m
3/ h, pressure 7atm, aeration time are 2.2h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates, the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying, wherein said crystallizer are by graphite cake assembly unit, outside device with lagging material.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B5; After A5 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 5:
Table 5
| Ppm/ unit | P | B | Fe | Al | Ca |
| A5 | 8.3 | 1.2 | 745 | 413 | 30 |
| B5 | 0.8 | 0.28 | 521 | 27 | 8 |
(1) takes by weighing slag former 1t, slag former Na
2CO
3-KCl-SiO
2Component is by weight percentage: Na
2CO
3Be that 46.5%, KCl is 7%, SiO
2Be 46.5%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1518 ℃ of slag temperature at night;
(2) go out in the silicon liquid process in mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag night and silicon liquid is 1.2:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, the volume ratio of oxygen and air is 0.8:1 in the described mixed gas, and ventilation flow rate is 7m
3/ h, pressure 5atm, aeration time are 2.8h;
(3) after going out silicon liquid and finishing, slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 57%, oxygen is 22%, and nitrogen is 21%, and ventilation flow rate is 8m
3/ h, pressure 7atm, aeration time are 2.2h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates, the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying, wherein said crystallizer are by graphite cake assembly unit, outside device with lagging material.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B6; After A6 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 6:
Table 6
| Ppm/ unit | P | B | Fe | Al | Ca |
| A6 | 8.9 | 1.2 | 745 | 411 | 30 |
| B6 | 1.0 | 0.3 | 518 | 24 | 7 |
(1) takes by weighing slag former 1t, slag former K
2CO
3-KCl-SiO
2Component is by weight percentage: K
2CO
3Be that 47%, KCl is 6%, SiO
2Be 47%, with the slag former heat fused in the intermediate frequency furnace plumbago crucible that is formed by bottom plumbago crucible and top alumina brick of packing into, obtain slag night, and keep 1480 ℃ of slag temperature at night;
(2) go out in the silicon liquid process in the 12500KVA mineral hot furnace, control silicon liquid quality is 2t, guarantees that the mass ratio of slag night and silicon liquid is 0.6:1, continues to pass into the mixed gas of oxygen and air to the bottom of two-maing ladle, the volume ratio of oxygen and air is 0.8:1 in the described mixed gas, and ventilation flow rate is 7m
3/ h, pressure 5atm, aeration time are 2.8h;
(3) after going out silicon liquid and finishing, slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, simultaneously pass into the oxidisability mixed gas in two-man ladle and carry out refining, described oxidisability mixed gas is chlorine, oxygen and nitrogen, it forms by volume, and per-cent is: chlorine is 60%, oxygen is 20%, and nitrogen is 20%, and ventilation flow rate is 8m
3/ h, pressure 7atm, aeration time are 2.2h;
(4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates, the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying, wherein said crystallizer are by graphite cake assembly unit, outside device with lagging material.
Measure the result of gained among this embodiment, get the silicon ingot central part, measure foreign matter content in the silicon by ICP-MS, be denoted as B7; After A7 represents that mineral hot furnace goes out silicon and finishes, the liquid-like of getting in two-maing ladle before the slag making.
Measuring result such as table 7:
Table 7
| Ppm/ unit | P | B | Fe | Al | Ca |
| A7 | 9.0 | 1.1 | 745 | 411 | 30 |
| B7 | 1.0 | 0.29 | 503 | 21 | 7 |
Claims (10)
1. the refining of two-maing ladle prepares the method for low-phosphorous boron polysilicon, it is characterized in that described method may further comprise the steps:
1) slag former is packed into heat fused in the intermediate frequency furnace plumbago crucible obtains slag night, insulation;
2) go out in the silicon liquid process in mineral hot furnace, continue to pass into the mixed gas of air and oxygen to the bottom of two-maing ladle;
3) after going out silicon liquid and finishing, the slag liquid in the intermediate frequency furnace plumbago crucible poured into two-man ladle, pass into the oxidisability mixed gas in two-man ladle simultaneously and carry out refining;
4) two-man ladle after the refining, pour together white residue into crystallizer and realize that slag silicon separates the low-phosphorous boron polycrystalline silicon raw material after obtaining purifying.
2. the refining of two-maing ladle according to claim 1 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, slag former described in the step 1) is the composition of alkaline carbonate, alkali metal chloride and silicon-dioxide, its composition is by mass percentage: alkali metal chloride is 5%～10%, and surplus is alkaline carbonate and SiO
2, wherein alkaline carbonate and SiO
2Mass ratio be 1:1.
3. the refining of two-maing ladle according to claim 2 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, described alkaline carbonate is Na
2CO
3Or K
2CO
3In one or both combination, described alkali metal chloride is one or both the combination among NaCl or the KCl.
4. the refining of two-maing ladle according to claim 1 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, the insulation described in the step 1) is for keeping the slag liquid temp in 1450～1600 ℃ of scopes.
5. the refining of two-maing ladle according to claim 1 prepares the method for low-phosphorous boron polysilicon, it is characterized in that step 2) in going out silicon liquid process, the mass ratio of the slag liquid of control silicon liquid and step 1) is 1:0.5～2, preferred 1:0.5～1.5, more preferably 1:0.5～1.
6. the refining of two-maing ladle according to claim 1 prepares the method for low-phosphorous boron polysilicon, it is characterized in that step 2) described in air and the mixed gas of oxygen in, the volume ratio of oxygen and air is 0.1～1:1, its ventilation flow rate is 5～12m
3/ h, pressure 3～9atm, aeration time are 2～3h.
7. the refining of two-maing ladle according to claim 1 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, the oxidisability mixed gas described in the step 3) is the mixed gas of chlorine, oxygen and nitrogen.
8. the refining of two-maing ladle according to claim 7 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, the composition of described oxidisability mixed gas by volume per-cent is: chlorine 40～60%, and oxygen 20～30%, surplus is nitrogen; Preferred chlorine 50～60%, oxygen 20～25%, surplus is nitrogen; More preferably chlorine 60%, oxygen 20%, and surplus is nitrogen; Its ventilation flow rate is 5～12m
3/ h, pressure 3～9atm, aeration time are 1～3h.
9. the described refining of two-maing ladle of any one prepares the method for low-phosphorous boron polysilicon according to claim 1-8, it is characterized in that the structure of the intermediate frequency furnace plumbago crucible described in step 1) and the step 3) is comprised of bottom plumbago crucible and top alumina brick.
10. the refining of two-maing ladle according to claim 9 prepares the method for low-phosphorous boron polysilicon, it is characterized in that, the crystallizer described in the step 4) is by the graphite cake assembly unit, and outside device with lagging material.
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|---|---|---|---|---|
| US20050139148A1 (en) * | 2002-02-04 | 2005-06-30 | Hiroyasu Fujiwara | Silicon purifying method, slag for purifying silicon and purified silicon |
| CN101555013A (en) * | 2009-05-18 | 2009-10-14 | 贵阳宝源阳光硅业有限公司 | Refining method of industrial silicon |
| CN101724900A (en) * | 2009-11-24 | 2010-06-09 | 厦门大学 | Device and method for purifying polycrystalline silicon |
| CN102583389A (en) * | 2012-03-05 | 2012-07-18 | 昆明理工大学 | Method for purifying industrial silicon through external refining |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20050139148A1 (en) * | 2002-02-04 | 2005-06-30 | Hiroyasu Fujiwara | Silicon purifying method, slag for purifying silicon and purified silicon |
| CN101555013A (en) * | 2009-05-18 | 2009-10-14 | 贵阳宝源阳光硅业有限公司 | Refining method of industrial silicon |
| CN101724900A (en) * | 2009-11-24 | 2010-06-09 | 厦门大学 | Device and method for purifying polycrystalline silicon |
| CN102583389A (en) * | 2012-03-05 | 2012-07-18 | 昆明理工大学 | Method for purifying industrial silicon through external refining |
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