CN108328618B - Method for separating hard inclusions in silicon by electromagnetic induction directional solidification - Google Patents
Method for separating hard inclusions in silicon by electromagnetic induction directional solidification Download PDFInfo
- Publication number
- CN108328618B CN108328618B CN201810089314.1A CN201810089314A CN108328618B CN 108328618 B CN108328618 B CN 108328618B CN 201810089314 A CN201810089314 A CN 201810089314A CN 108328618 B CN108328618 B CN 108328618B
- Authority
- CN
- China
- Prior art keywords
- temperature
- silicon
- directional solidification
- stage
- electromagnetic induction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/037—Purification
Abstract
The invention belongs to the technical field of polycrystalline silicon smelting, and particularly relates to a method for separating hard impurities in silicon through electromagnetic induction directional solidification. According to the method, the top skin and the edge skin materials generated in the polycrystalline silicon ingot casting/purification process are selected as raw materials, the migration and enrichment environment of the hard impurities is constructed by utilizing the electromagnetic induction coupling directional solidification technology, so that the hard impurities are finally enriched on the surface of the ingot casting and are further cut off, the high-purity silicon ingot is obtained, and the effect of removing the hard impurities by using the method is remarkable.
Description
Technical Field
The invention belongs to the technical field of polycrystalline silicon smelting, and particularly relates to a method for separating hard impurities in silicon through electromagnetic induction directional solidification.
Background
Solar grade polysilicon is a main raw material of the photovoltaic industry, and with the continuous development of the photovoltaic industry, the demand for polysilicon materials is increasing day by day. China has become the largest export country and demand country of polycrystalline silicon, and depends on import in a large amount, and the production scale needs to be enlarged. However, due to redistribution of impurities in the preparation process and pollution of a smelting environment, the yield of the polycrystalline silicon ingot is less than 70%, the top area of the ingot is rich in carbon impurities, the edge of the ingot is rich in nitrogen impurities, and the ingot cannot be directly utilized. The part of silicon material is purified to obtain high-purity polysilicon material again, so that the silicon material is recycled, and the economic and social significance is great.
After the ingot casting process of preparing the solar grade polysilicon by the metallurgy method, the yield of the ingot casting is only 70 percent, and a large amount of SiC and Si are accumulated in the ingot casting area with the top and the side of the ingot casting area close to 30 percent3N4Inclusions and metallic impurities, the purity of these regions is only 3N (99.9%). From the foregoing, there are currently very effective purification methods for metal impurities. However, C, N and SiC and Si precipitated therefrom3N4The non-metallic inclusion particles, due to their diversity of sources in various processes, also present certain difficulties in studying their distribution and removal, which is the case for carbon in the current traditional processesAlthough the control of nitrogen impurities achieves certain effects, the requirements of a solar cell with higher quality on silicon materials cannot be met, and waste tailings are extremely difficult to recycle.
The existing method has the following defects:
1. filtration
The filtering technology mainly adopts a ceramic sponge filter screen to separate SiC and Si in silicon tailings at high temperature3N4And particles are included. Si when the silicon liquid containing the inclusion flows through the filtering device3N4Mainly concentrates on the surface of the filter screen, and SiC is mainly attached to the surface of the ceramic material in holes in the filter screen, so that the holes are filled, and particles are further prevented from passing through the filter screen. The filtering process is a batch and fractional process, continuous production cannot be realized, a good separation effect is only realized on particles with the particle size larger than 10 mu m, the separation efficiency is low on impurity particles with small particle size, and a large amount of silicon liquid is adhered to the inner wall in the process, so that the loss of silicon materials is caused.
2. Sedimentation
The settling technology mainly utilizes SiC and Si in silicon3N4The difference in physical properties is greater for inclusion densities than for silicon melts. The polycrystalline silicon tailing is carried out under high-temperature melt, and solid particles in the silicon melt gradually settle to the bottom of the melt under the action of gravity, are deposited and are separated from the silicon melt. However, in the simple sedimentation separation, since the melt has almost no fluidity and the sedimentation is completely dependent on the action of gravity, the separation time is long and the separation efficiency is low.
3. Directional solidification
The directional solidification technology adopted by the polycrystalline silicon ingot furnace has the effect of segregating impurities with segregation coefficients less than 1 to the top of the melt. Because the segregation coefficients of C and N in silicon are less than 1. Impurities are segregated to the top of the melt in a directional solidification mode so as to achieve the effect of separating C and N in the silicon. However, due to the extremely weak fluidity of the melt in the directional solidification furnace, although free C and N may segregate to the last solidification region as the solid-liquid interface advances, their supersaturated precipitation of particle phases SiC and Si occurs3N4Is widely distributedThe separation of particles from silicon cannot be achieved in the solidified ingot.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for separating hard impurities in silicon by electromagnetic induction directional solidification. In the silicon refining process, an external field is applied through electromagnetic induction, under the action of Lorentz force and directional stirring of the melt, the hard inclusions in the silicon melt and the hard inclusions migrate in the electromagnetic induction field and are enriched to the top and the side of the melt, and then the hard inclusions are further enriched to the top of an ingot through directional solidification, so that the hard inclusions are removed. The product prepared by the method has good effect of removing hard impurities and high purification efficiency.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a method for separating hard inclusions in silicon by electromagnetic induction directional solidification is characterized by comprising the following steps: the method comprises the following steps:
A. charging: filling a quartz crucible with a mixture containing SiC and Si3N4The hard inclusion polycrystalline silicon ingot or the top skin material produced in the purification process has the silicon content of 90-99 wt% in the raw material;
B. a temperature rising stage: after the charging is finished, vacuumizing the equipment, starting heating up after the vacuum degree reaches 15Pa, wherein the power is heated up in the initial stage, the frequency of the induction coil is 3000Hz, and the power change is 10kW (10min) -30kW (60min) -60kW (16min) -100 kW; when the temperature of the temperature control thermocouple is 1120 ℃, the temperature control mode is changed from power control to temperature control, and argon gas is filled at the rate of 50L/min; when the temperature of the temperature control thermocouple rises to 1560 ℃ and the argon pressure reaches 60kPa, ending the temperature rise stage;
C. a melting stage: after the temperature rise stage is finished for 50min, raising the temperature of a temperature control thermocouple to 1564 ℃, and preserving the temperature for 768min at the temperature to completely melt the silicon material;
D. a directional solidification stage: after the silicon material is completely melted, the quartz crucible is reduced by 60mm at the speed of 2.5mm/min, and the flowing state of 30L/min argon is kept in the process; then, stabilizing the temperature of the temperature-controlled thermocouple at 1478 ℃, and performing directional solidification at a pull-down speed of 0.1 mm/min;
E. and (3) a cooling stage: after the directional solidification, cooling at the cooling rate of 1.5 ℃/min, and taking out the silicon ingot after cooling.
The charging mass in the step A is 400 kg.
According to the method, the top skin and the edge skin materials generated in the polycrystalline silicon ingot casting/purification process are selected as raw materials, the migration and enrichment environment of the hard impurities is constructed by utilizing the electromagnetic induction coupling directional solidification technology, so that the hard impurities are finally enriched on the surface of the ingot casting and are further cut off, the high-purity silicon ingot is obtained, and the effect of removing the hard impurities by using the method is remarkable.
Detailed Description
The invention is further illustrated by the following examples:
example 1
A method for separating hard inclusions in silicon by electromagnetic induction directional solidification specifically comprises the following steps:
A. charging: filling a quartz crucible with a mixture containing SiC and Si3N4The hard inclusion polycrystalline silicon ingot casting/top skin material produced in the purification process has the silicon content of 90 wt% in the raw materials and the charging mass of 400 kg;
B. a temperature rising stage: after the charging is finished, the equipment is vacuumized, and the temperature is raised after the vacuum degree reaches 15 Pa. The initial stage is power temperature rise, the frequency of the induction coil is 3000Hz, and the power change is 10kW (10min) -30kW (60min) -60kW (16min) -100 kW. When the temperature of the temperature control thermocouple is 1120 ℃, the temperature control mode is changed from power control to temperature control. At this time, the argon gas was introduced at a rate of 50L/min. When the temperature of the temperature control thermocouple rises to 1560 ℃ and the argon pressure reaches 60kPa, ending the temperature rise stage;
C. a melting stage: after the temperature rise stage is finished for 50min, raising the temperature of a temperature control thermocouple to 1564 ℃, and preserving the temperature for 768min at the temperature to completely melt the silicon material;
D. a directional solidification stage: after the silicon material is completely melted, the quartz crucible is lowered by 60mm at a rate of 2.5 mm/min. A30L/min argon flow was maintained during this process. Then, stabilizing the temperature of the temperature-controlled thermocouple at 1478 ℃, and performing directional solidification at a pull-down speed of 0.1 mm/min;
E. and (3) a cooling stage: after the directional solidification, cooling at the cooling rate of 1.5 ℃/min, and taking out the silicon ingot after cooling.
Example 2
The steps of the method for separating hard inclusions in silicon by electromagnetic induction directional solidification in the implementation are the same as those in the embodiment 1, and different technical parameters are as follows: the silicon content of the raw material was 95 wt%.
Example 3
The steps of the method for separating hard inclusions in silicon by electromagnetic induction directional solidification in the implementation are the same as those in the embodiment 1, and different technical parameters are as follows: the silicon content of the raw material was 99 wt%.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (2)
1. A method for separating hard inclusions in silicon by electromagnetic induction directional solidification is characterized by comprising the following steps: the method comprises the following steps:
A. charging: filling a polysilicon cast ingot containing SiC and Si3N4 hard inclusions or a top skin material generated in the purification process into a quartz crucible, wherein the content of silicon in the raw material is 90-99 wt%;
B. a temperature rising stage: after the charging is finished, vacuumizing the equipment, starting heating up after the vacuum degree reaches 15Pa, wherein the power heating up is carried out in the initial stage, the frequency of an induction coil is 3000Hz, and the power change is 10kW to 30kW, 60min to 60kW, 16min to 100 kW; when the temperature of the temperature control thermocouple is 1120 ℃, the temperature control mode is changed from power control to temperature control, and argon gas is filled at the rate of 50L/min; when the temperature of the temperature control thermocouple rises to 1560 ℃ and the argon pressure reaches 60kPa, ending the temperature rise stage;
C. a melting stage: after the temperature rise stage is finished for 50min, raising the temperature of a temperature control thermocouple to 1564 ℃, and preserving the temperature for 768min at the temperature to completely melt the silicon material;
D. a directional solidification stage: after the silicon material is completely melted, the quartz crucible is reduced by 60mm at the speed of 2.5mm/min, and the flowing state of 30L/min argon is kept in the process; then, stabilizing the temperature of the temperature-controlled thermocouple at 1478 ℃, and performing directional solidification at a pull-down speed of 0.1 mm/min;
E. and (3) a cooling stage: after the directional solidification, cooling at the cooling rate of 1.5 ℃/min, and taking out the silicon ingot after cooling.
2. The method for separating the hard inclusions in the silicon by the electromagnetic induction directional solidification as claimed in claim 1, wherein: the charging mass in the step A is 400 kg.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810089314.1A CN108328618B (en) | 2018-01-30 | 2018-01-30 | Method for separating hard inclusions in silicon by electromagnetic induction directional solidification |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810089314.1A CN108328618B (en) | 2018-01-30 | 2018-01-30 | Method for separating hard inclusions in silicon by electromagnetic induction directional solidification |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108328618A CN108328618A (en) | 2018-07-27 |
| CN108328618B true CN108328618B (en) | 2021-02-09 |
Family
ID=62926196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810089314.1A Active CN108328618B (en) | 2018-01-30 | 2018-01-30 | Method for separating hard inclusions in silicon by electromagnetic induction directional solidification |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108328618B (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1569629A (en) * | 2003-07-22 | 2005-01-26 | 龚炳生 | Method of manufacturing a photovoltaic silicon |
| CN1873062A (en) * | 2006-05-06 | 2006-12-06 | 大连理工大学 | Method for preparing polysilicon in high purity in use for solar cell |
| CN101289188A (en) * | 2008-05-30 | 2008-10-22 | 大连理工大学 | Process and device for removing phosphorus and metal impurities in polycrystalline silicon |
| CN101665253A (en) * | 2009-09-29 | 2010-03-10 | 包头市山晟新能源有限责任公司 | Polysilicon purification method and crucible and purification device used for polysilicon purification |
| CN102173424A (en) * | 2011-01-31 | 2011-09-07 | 大连理工大学 | Method and equipment for removing phosphorus and metal impurities in ganister sand through vacuum induction melting |
| CN102849743A (en) * | 2012-09-25 | 2013-01-02 | 青岛隆盛晶硅科技有限公司 | Polysilicon purification method and device by reverse induced solidification |
| CN102976335A (en) * | 2012-12-13 | 2013-03-20 | 青岛隆盛晶硅科技有限公司 | Method and apparatus for purifying polycrystalline silicon through rotation and blow induced inversion solidification |
| CN103539125A (en) * | 2013-10-18 | 2014-01-29 | 青岛隆盛晶硅科技有限公司 | Device and method for purifying polycrystalline silicon by linking of medium smelting and primary directional solidification |
| CN103553052A (en) * | 2013-10-30 | 2014-02-05 | 大连理工大学 | Polysilicon reverse solidification device and method |
-
2018
- 2018-01-30 CN CN201810089314.1A patent/CN108328618B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1569629A (en) * | 2003-07-22 | 2005-01-26 | 龚炳生 | Method of manufacturing a photovoltaic silicon |
| CN1873062A (en) * | 2006-05-06 | 2006-12-06 | 大连理工大学 | Method for preparing polysilicon in high purity in use for solar cell |
| CN101289188A (en) * | 2008-05-30 | 2008-10-22 | 大连理工大学 | Process and device for removing phosphorus and metal impurities in polycrystalline silicon |
| CN101665253A (en) * | 2009-09-29 | 2010-03-10 | 包头市山晟新能源有限责任公司 | Polysilicon purification method and crucible and purification device used for polysilicon purification |
| CN102173424A (en) * | 2011-01-31 | 2011-09-07 | 大连理工大学 | Method and equipment for removing phosphorus and metal impurities in ganister sand through vacuum induction melting |
| CN102849743A (en) * | 2012-09-25 | 2013-01-02 | 青岛隆盛晶硅科技有限公司 | Polysilicon purification method and device by reverse induced solidification |
| CN102976335A (en) * | 2012-12-13 | 2013-03-20 | 青岛隆盛晶硅科技有限公司 | Method and apparatus for purifying polycrystalline silicon through rotation and blow induced inversion solidification |
| CN102976335B (en) * | 2012-12-13 | 2014-04-30 | 青岛隆盛晶硅科技有限公司 | Method and apparatus for purifying polycrystalline silicon through rotation and blow induced inversion solidification |
| CN103539125A (en) * | 2013-10-18 | 2014-01-29 | 青岛隆盛晶硅科技有限公司 | Device and method for purifying polycrystalline silicon by linking of medium smelting and primary directional solidification |
| CN103553052A (en) * | 2013-10-30 | 2014-02-05 | 大连理工大学 | Polysilicon reverse solidification device and method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108328618A (en) | 2018-07-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2198077B1 (en) | Method for processing silicon powder to obtain silicon crystals | |
| US20120164055A1 (en) | Method of removal of impurities from silicon | |
| CN110343870B (en) | Oxygen-free copper casting production method | |
| CN111675222B (en) | Method for producing industrial silicon by using low-grade silica | |
| Yu et al. | Si purification by enrichment of primary Si in Al-Si melt | |
| Zou et al. | Effects of AlB2/AlP phase and electromagnetic stirring on impurity B/P removal in the solidification process of Al-30Si alloy | |
| CN101798705A (en) | Method and device for continuous crystal-pulling purification of polysilicon from low-temperature melt | |
| Li et al. | Recycling of silicon scraps by electron beam melting coupled with directional solidification and its mechanism of impurity removal | |
| CN101812727B (en) | Method for directionally solidifying and purifying polycrystalline silicon under DC electric field | |
| CN108328618B (en) | Method for separating hard inclusions in silicon by electromagnetic induction directional solidification | |
| CN105274619B (en) | It is a kind of to strengthen the method for removing boron in metallurgical grade silicon | |
| CN108101064B (en) | Method for separating hard impurities in silicon by temperature gradient | |
| CN104195348A (en) | Low-silicon and low-impurity pre-melting slag for electro-slag remelting and preparing method and application thereof | |
| US10773963B2 (en) | Method of purifying aluminum and use of purified aluminum to purify silicon | |
| CN114672677B (en) | Method for purifying aluminum-lithium alloy melt | |
| CN108128779B (en) | Method for removing carbon and nitrogen impurities in polycrystalline silicon | |
| CN108557825B (en) | Method for removing carbon and nitrogen impurities in polycrystalline silicon at low cost | |
| CN104071790A (en) | Device and method for purifying silicon from silicon alloy melt by electromagnetic stirring | |
| US20110120365A1 (en) | Process for removal of contaminants from a melt of non-ferrous metals and apparatus for growing high purity silicon crystals | |
| CN202717593U (en) | Device utilizing electromagnetic method to recycle silicon components in fretsaw silica mud | |
| CN111747415B (en) | Method for removing impurity iron in industrial silicon | |
| CN111591996A (en) | Method for preparing industrial silicon by using ferrosilicon | |
| CN103266350A (en) | Vacuum solid-liquid separation method and device for polycrystalline silicon ingot | |
| CN111762786B (en) | Method for removing impurity elements by controllable solidification of silicon melt | |
| CN102849742B (en) | Device and method for recovering silicon component in fretsaw silicon sludge by electromagnetic method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |