CN101723382A - Purification method of silicon - Google Patents
Purification method of silicon Download PDFInfo
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- CN101723382A CN101723382A CN200810224625A CN200810224625A CN101723382A CN 101723382 A CN101723382 A CN 101723382A CN 200810224625 A CN200810224625 A CN 200810224625A CN 200810224625 A CN200810224625 A CN 200810224625A CN 101723382 A CN101723382 A CN 101723382A
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Abstract
The embodiment of the invention provides a purification method of silicon, which belongs to the fields of solar energy and chemical engineering and comprises the following steps of: mixing silicon grains and Al with the purity of 99.99 percent, putting the mixture into a crucible, putting the crucible with the mixture of Si and Al into a medium frequency induction furnace for melting, introducing the mixed gas of Ar and H2 into the induction furnace, adding Ti grains with the purity of 99.99 percent into a Si-Al fused mass and continuously keeping melting and stirring states for 10-30 minutes; casting a Si-Al-Ti melt in the melting state into a directionally solidified furnace crucible, and inhabiting the lateral heat dispersion of the Si-Al-Ti melt through a maintaining furnace; and introducing water to the bottom of a directionally solidified furnace crucible mould for directional solidification to obtain a silicon ingot. The method has the advantage of high boron removing rate.
Description
Technical field
The present invention relates to sun power and chemical field, relates in particular to a kind of method of purification of silicon.
Background technology
Sun power is human inexhaustible renewable energy source. also is clean energy, do not produce any environmental pollution.In the middle of effective utilization of sun power; Big sun can solar photovoltaic utilization be a research field with fastest developing speed in the last few years, most active, is one of project that wherein attracts most attention.For this reason, people develop and have developed solar cell.Making solar cell mainly is based on semiconductor material, and wherein, the silicon based material has occupied dominant position.
In order to obtain solar-grade polysilicon, prior art provides a kind of method of purification of polysilicon, and this method comprises the steps: as shown in Figure 1
S11, with polysilicon by pulverizing, putting into organic solvent behind the ball milling and soak;
S12, the polysilicon after will soaking are put into the elevated temperature vessel wet-oxygen oxidation;
S13, obtain polysilicon with putting into the internal corrosion of HF solution after the polysilicon after the oxidation cooling and cleaning to neutrality.
In realizing process of the present invention, the contriver finds prior art, and there are the following problems:
The technical scheme that prior art provides is not owing to carry out under molten state, when oxidation, the gas of oxidizing reaction be difficult to silicon in impurity fully act on, the oxidising process of boron can not fully be carried out, to such an extent as to the clearance of boron is not high.
Summary of the invention
In view of above-mentioned existing in prior technology problem, embodiment of the present invention provides a kind of method of purification of silicon, and this method has the high advantage of clearance of boron.
The specific embodiment of the present invention provides a kind of method of purification of silicon, comprising:
A, be that 99.99% Al mixes and puts into crucible with silicon grain and purity, the mass ratio of described Si, Al can be 1: 0.5～0.65;
B, the crucible that will be placed with Si, Al mixture are put into the medium-frequency induction furnace fusion, and the temperature of controlling described induction furnace is at 900-1300 ℃, and stir the Si-Al melt that is in molten state;
C, feed Ar, H to described induction furnace
2Mixed gas, the Ar of described mixed gas, H
2Volume ratio is 9: 1;
D, to add purity in the Si-Al melt be the 99.99%Ti particle, continued to keep fusion and whipped state 10～30 minutes, and the mass ratio of described Ti particle and Si-Al melt is 0.03～0.1: 1;
E, with the Si-Al-Ti melt cast of molten state in the directional solidification furnace crucible, and suppress the side direction heat radiation of Si-Al-Ti melt by holding furnace;
F, carry out directional freeze to the water flowing of the bottom of directional solidification furnace crucible die and obtain silicon ingot, the speed of cooling in the described directional freeze process is 4～10K/min, and the speed of solidifying is 0.25～1mm/min.
By the above-mentioned technical scheme that provides as can be seen, the technical scheme of the embodiment of the invention has the good advantage of removal effect of boron.
Description of drawings
The schema of the method for purification of a kind of silicon that Fig. 1 provides for prior art.
The schema of the method for purification of a kind of silicon that Fig. 2 provides for the specific embodiment of the invention.
Embodiment
Embodiment of the present invention provides a kind of method of purification of silicon, and this method comprises the steps: as shown in Figure 2
S21, be that 99.99% Al mixes and puts into crucible with silicon grain and purity, the mass ratio of this Si, Al can be 1: 0.5～0.65;
Size to silicon grain in this step does not limit.
S22, the crucible that will be placed with Si, Al mixture are put into the medium-frequency induction furnace fusion, and the temperature of controlling this induction furnace is at 900-1300 ℃ and stir the Si-Al melt that is in molten state;
Stirring in this step be in molten state the Si-Al melt implementation method can for, the stirring action by ruhmkorff coil stirs the Si-Al melt that is in molten state, and other alr mode can certainly be arranged.
S23, feed Ar, H to this medium-frequency induction furnace
2Mixed gas, the Ar of this mixed gas, H
2Volume ratio is 9: 1;
S24, to add purity in the Si-Al melt be the 99.99%Ti particle, continued to keep fusion and whipped state 10～30 minutes;
The Ti particle of this step and the mass ratio of Si-Al melt can be 0.03～0.1: 1.
S25, with the Si-Al-Ti melt cast of molten state in the directional solidification furnace crucible, and suppress the side direction heat radiation of Si-Al-Ti melt by holding furnace;
S26, carries out directional freeze to the water flowing of the bottom of directional solidification furnace crucible die and obtain silicon ingot, and the speed of cooling in the control directional freeze process is 4～10K/min that the speed of directional freeze is 0.25～1mm/min.
Optionally, this method can also comprise after S26:
S27, carry out the silica flour that ball milling obtains 50-100 μ m with putting into the ball mill that feeds rare gas element after this silicon ingot fragmentation;
S28, silica flour is put into acid solution, the acid solution that will put into silica flour stirs and soaks 1～2h, and to guarantee to soak be 50～90 ℃;
Acid solution in this step can for, concentration is 40%～60% chloroazotic acid, dense H
2SO
4, HNO
3, any one or two kinds among rare HF, the rare HCl.
Optionally, this step is in immersion process, and the complexing agent that can add 5～10ml carries out complexing, and this complexing agent can be the aqueous solution of N.F,USP MANNITOL or glycerine, thus the boron in the more effective removal silica flour.
S29, the silica flour after will soaking with washed with de-ionized water after, put into the vacuum drying oven drying and obtain polysilicon.
Polysilicon purity after this method is handled by S27～S29 is higher, and the removal effect of boron is better.
For the technique effect that the present invention reached better is described, the existing technique effect that comes the present invention is reached in conjunction with the principle of work of method provided by the present invention describes in detail.
The technology of the present invention is used metallurgical slag making principle, reduces the fused temperature by Al under molten state, according to the difference of the impurity element B that influences battery performance in silicon solution neutral matter, adds alloying element Ti B is combined into the second phase compound TiB
2This process helps the inner impurity element of silicon ingot by transporting action, according to solubleness features of smaller in the Al-Si melt, from Pure Silicon Metal, be separated to slag mutually in; Because the Al fusant density is less, float over silicon liquid top easily simultaneously, can effectively separate with parent.According to the characteristics of directional freeze, impurity that can segregation coefficient is less is further got rid of above silicon ingot or the center; Through the leaching of peracid, can with fractional condensation the second phase material of crystal boundary (Al, Si)
3Ti and Ti
2B leaches, and the purity of product is further improved.
In fusion Al-Si alloy, the Ti that adds can be dissolved in the melt, simultaneously that segregation coefficient is less B is segregated in the border (formula 1) of Al-Si melt by the form that forms second phase, can effectively remove by cutting upper strata Al slag after the directional freeze process.The less impurity that gathers partially at silicon face of solubleness also can go out by acidleach in the process of acidleach.The content of the Ti that adds is less, and forms intermetallic compound with metal A l, keeps content below 1ppm, does not need extra removal.
Ti (l)+2B (l)=TiB
2(s)
(formula 1)
The present invention adds Al as alloying element, not only effectively reduces the fused temperature, and the less density of Al helps the slag gold and separates, and Al can distinguish molten the eliminating in the process of directional freeze; Form on the border in the alloy process (Al, Si)
3The Ti intermetallic compound also can be dissolved in the wang aqueous solution, helps residual A l is removed, and can not introduce impurity element.
Most of metallic impurity elements can obtain removing by directional freeze.Because the solute distribution coefficient k (k=C that solidifies
s/ C
L, C
s, C
LThe equilibrium concentration of representing the solid-liquid phase respectively) there are two kinds of situations in difference, concerns for the phasor of silicon and solution impurity element, and when k＞1, the solid phase C that solidifies earlier
s＞C
0Impurity is more, is unfavorable for solidifying removal; And when k＜1, impurity concentration is C
0The sosoloid heating and melting after, the solid phase foreign matter content C that solidifies is at first solidified in control setting rate multiple bearing
sCompare C
0Reduce.By this method, in the process of setting, solidify from the border to the center from bottom to top, final sample can be with solubleness in the slagging process or the less impurity element of segregation coefficient, and for example Fe (6.40 * 10
-6), Ti (2.00 * 10
-6), Cu (8.00 * 10
-6) and segregation junction be combined in TiB in the Si-Al alloy
2Get rid of the position (silicon ingot top and central position) of in the end solidifying, thereby will in slagging process, be set in the slag blanket with the second phase form by the bonded boron, can slag blanket be removed by cutting subsequently.
The method that the specific embodiment of the invention provides has the high advantage of clearance of boron
In sum, the technical scheme that the specific embodiment of the invention provides has the high advantage of clearance of boron.
The above; only be the preferable embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the embodiment of the invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.
Claims (3)
1. the method for purification of a polysilicon is characterized in that, described method comprises:
A, be that 99.99% Al mixes and puts into crucible with silicon grain and purity, the mass ratio of described Si, Al can be 1: 0.5～0.65;
B, the crucible that will be placed with Si, Al mixture are put into the medium-frequency induction furnace fusion, and the temperature of controlling described induction furnace is at 900-1300 ℃, and stir the Si-Al melt that is in molten state;
C, feed Ar, H to described induction furnace
2Mixed gas, the Ar of described mixed gas, H
2Volume ratio is 9: 1;
D, to add purity in the Si-Al melt be the 99.99%Ti particle, continued to keep fusion and whipped state 10～30 minutes, and the mass ratio of described Ti particle and Si-Al melt is 0.03～0.1: 1;
E, with the Si-Al-Ti melt cast of molten state in the directional solidification furnace crucible, and suppress the side direction heat radiation of Si-Al-Ti melt by holding furnace;
F, carry out directional freeze to the water flowing of the bottom of directional solidification furnace crucible die and obtain silicon ingot, the speed of cooling in the described directional freeze process is 4～10K/min, and the speed of solidifying is 0.25～1mm/min.
2. method according to claim 1 is characterized in that, described method also comprises:
F, carry out the silica flour that ball milling obtains 50-100 μ m with putting into the ball mill that feeds rare gas element after the described silicon ingot fragmentation;
G, described silica flour is put into acid solution, described acid solution is stirred soak 1～2h, and to guarantee to soak be 50～90 ℃; Described acid solution is that concentration is 40%～60% chloroazotic acid, dense H
2SO
4, HNO
3, any one or two kinds among rare HF, the rare HCl;
H, the silica flour after will soaking with washed with de-ionized water after, put into the vacuum drying oven drying and obtain polysilicon.
3. method according to claim 2 is characterized in that, described acid solution is stirred among the described step G soaked 1～2h and comprised: put into the complexing agent of 5～10ml in described acid solution after, stir and soak 1～2h; Described complexing agent is the aqueous solution of N.F,USP MANNITOL or glycerine.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102311121A (en) * | 2011-08-29 | 2012-01-11 | 大连理工大学 | Method for segregation and purification of industrial silicon by alloying |
| CN102351188A (en) * | 2011-07-07 | 2012-02-15 | 陈评 | Method for preparing acicular high-purity silicon aggregates and equipment thereof |
| US20120175553A1 (en) * | 2011-01-12 | 2012-07-12 | Andreas Krause | Method for producing a silicon ingot |
| CN103343384A (en) * | 2013-07-08 | 2013-10-09 | 昆明理工大学 | Device for separating hypereutectic aluminum-silicon alloy and application of device |
| CN104030291A (en) * | 2014-05-14 | 2014-09-10 | 中国科学院等离子体物理研究所 | Method for high-efficacy removal of phosphorus in silicon by alloy method |
| CN104071790A (en) * | 2014-06-10 | 2014-10-01 | 中国科学院等离子体物理研究所 | Device and method for purifying silicon from silicon alloy melt by electromagnetic stirring |
| CN104556043A (en) * | 2014-12-10 | 2015-04-29 | 中国科学院等离子体物理研究所 | Method for quickly removing phosphor in silicon by introducing gas to Al-Si alloy |
| CN104583123A (en) * | 2012-06-25 | 2015-04-29 | 希利柯尔材料股份有限公司 | Method of purifying silicon |
| CN107445170A (en) * | 2017-09-04 | 2017-12-08 | 大连理工大学 | A kind of method of laser pre-treated directional solidification purification Buddha's warrior attendant wire cutting silica flour waste material |
-
2008
- 2008-10-21 CN CN200810224625A patent/CN101723382A/en active Pending
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120175553A1 (en) * | 2011-01-12 | 2012-07-12 | Andreas Krause | Method for producing a silicon ingot |
| CN102351188A (en) * | 2011-07-07 | 2012-02-15 | 陈评 | Method for preparing acicular high-purity silicon aggregates and equipment thereof |
| CN102351188B (en) * | 2011-07-07 | 2012-10-03 | 陈评 | Method for preparing acicular high-purity silicon aggregates and equipment thereof |
| CN102311121A (en) * | 2011-08-29 | 2012-01-11 | 大连理工大学 | Method for segregation and purification of industrial silicon by alloying |
| CN104583123A (en) * | 2012-06-25 | 2015-04-29 | 希利柯尔材料股份有限公司 | Method of purifying silicon |
| CN104583123B (en) * | 2012-06-25 | 2017-07-25 | 希利柯尔材料股份有限公司 | The method of purifying silicon |
| CN103343384B (en) * | 2013-07-08 | 2015-09-16 | 昆明理工大学 | A kind of device of isolated cocrystallized Al-Si alloy and application |
| CN103343384A (en) * | 2013-07-08 | 2013-10-09 | 昆明理工大学 | Device for separating hypereutectic aluminum-silicon alloy and application of device |
| CN104030291A (en) * | 2014-05-14 | 2014-09-10 | 中国科学院等离子体物理研究所 | Method for high-efficacy removal of phosphorus in silicon by alloy method |
| CN104071790A (en) * | 2014-06-10 | 2014-10-01 | 中国科学院等离子体物理研究所 | Device and method for purifying silicon from silicon alloy melt by electromagnetic stirring |
| CN104071790B (en) * | 2014-06-10 | 2018-01-02 | 中国科学院等离子体物理研究所 | Electromagnetic agitation silicon alloy melt silicon purifying plant and method |
| CN104556043A (en) * | 2014-12-10 | 2015-04-29 | 中国科学院等离子体物理研究所 | Method for quickly removing phosphor in silicon by introducing gas to Al-Si alloy |
| CN107445170A (en) * | 2017-09-04 | 2017-12-08 | 大连理工大学 | A kind of method of laser pre-treated directional solidification purification Buddha's warrior attendant wire cutting silica flour waste material |
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Open date: 20100609 |