CN111807372A - Method for top-blown refining of silicon wafer cutting waste - Google Patents
Method for top-blown refining of silicon wafer cutting waste Download PDFInfo
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- CN111807372A CN111807372A CN202010705006.4A CN202010705006A CN111807372A CN 111807372 A CN111807372 A CN 111807372A CN 202010705006 A CN202010705006 A CN 202010705006A CN 111807372 A CN111807372 A CN 111807372A
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 174
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 171
- 239000010703 silicon Substances 0.000 title claims abstract description 171
- 238000005520 cutting process Methods 0.000 title claims abstract description 84
- 239000002699 waste material Substances 0.000 title claims abstract description 80
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000007670 refining Methods 0.000 title claims abstract description 37
- 238000007664 blowing Methods 0.000 claims abstract description 63
- 238000003723 Smelting Methods 0.000 claims abstract description 57
- 239000012535 impurity Substances 0.000 claims abstract description 32
- 230000001590 oxidative effect Effects 0.000 claims abstract description 30
- 239000007789 gas Substances 0.000 claims description 61
- 239000002245 particle Substances 0.000 claims description 45
- 239000000779 smoke Substances 0.000 claims description 45
- 230000005540 biological transmission Effects 0.000 claims description 27
- 239000007788 liquid Substances 0.000 claims description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 19
- 239000001301 oxygen Substances 0.000 claims description 19
- 229910052760 oxygen Inorganic materials 0.000 claims description 19
- 239000000047 product Substances 0.000 claims description 16
- 239000000428 dust Substances 0.000 claims description 14
- 238000005266 casting Methods 0.000 claims description 9
- 238000005273 aeration Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 7
- 239000012065 filter cake Substances 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 7
- 238000012216 screening Methods 0.000 claims description 7
- 238000003860 storage Methods 0.000 claims description 6
- 239000000725 suspension Substances 0.000 claims description 2
- 238000009413 insulation Methods 0.000 claims 1
- 229910052782 aluminium Inorganic materials 0.000 abstract description 9
- 229910052791 calcium Inorganic materials 0.000 abstract description 9
- 238000002360 preparation method Methods 0.000 abstract description 6
- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 238000004064 recycling Methods 0.000 abstract description 3
- 239000002893 slag Substances 0.000 abstract description 3
- 230000001172 regenerating effect Effects 0.000 abstract description 2
- 238000009776 industrial production Methods 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 27
- 229910002804 graphite Inorganic materials 0.000 description 27
- 239000010439 graphite Substances 0.000 description 27
- 239000011575 calcium Substances 0.000 description 18
- 230000006698 induction Effects 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 230000009970 fire resistant effect Effects 0.000 description 6
- 238000009423 ventilation Methods 0.000 description 6
- 229910001868 water Inorganic materials 0.000 description 6
- 239000000498 cooling water Substances 0.000 description 4
- 239000003517 fume Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 239000011863 silicon-based powder Substances 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000009847 ladle furnace Methods 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention relates to a top-blown refining method for silicon wafer cutting waste, belonging to the technical field of preparation of high-purity silicon by recycling and regenerating silicon secondary resources. Aiming at the actual problem that the conventional pyrometallurgical smelting process of the silicon wafer cutting waste does not have impurity removal capability or has low impurity removal efficiency, the blowing device is additionally arranged in the smelting and refining process of the silicon wafer cutting waste, the oxidizing gas is introduced, the melted silicon wafer cutting waste is subjected to oxidizing refining, and the oxidizing reaction of impurities such as Ca, Al and the like in silicon is promoted to enter a slag phase to be removed while the silicon melt is strongly stirred, so that the preparation of high-quality silicon is realized. The method has the characteristics of simple equipment requirement, easy operation, short flow, capability of directly preparing high-quality silicon and suitability for large-scale industrial production.
Description
Technical Field
The invention relates to a top-blown refining method for silicon wafer cutting waste, belonging to the technical field of preparation of high-purity silicon by recycling and regenerating silicon secondary resources.
Background
The main process technology focuses on smelting and extracting the cutting waste in the conventional silicon wafer cutting waste recycling and silicon preparation process. Firstly, due to the difference and fluctuation of raw materials of silicon wafer cutting waste materials, the practical problem that the removal efficiency of aluminum and calcium impurities is low or the removal effect is not good exists in the smelting process. And thirdly, in the smelting process, in order to solve the problems of high melting temperature, high viscosity, poor slag-silicon separation performance and low silicon recovery rate of silicon dioxide, other auxiliary low-melting point additives are usually required to be added to improve the smelting furnace condition, and secondary increase and introduction of foreign impurities in the silicon melt are difficult to avoid while the additives are added, so that the grade and the additional value of industrial silicon products are reduced. Therefore, in order to simultaneously take melting and refining into consideration and meet the requirements of industrial silicon products on purity and recovery rate, the method of top-blown refining of the silicon wafer cutting waste is provided, and aims to realize deep removal of impurities in silicon melt produced by melting the silicon wafer cutting waste and simultaneously improve the recovery rate and purity grade of product silicon, thereby improving the added value and production profit of products.
Disclosure of Invention
Aiming at the actual problem that the conventional pyrometallurgical smelting process of the silicon wafer cutting waste does not have impurity removal capability or has low impurity removal efficiency, the invention provides a top-blown refining method of the silicon wafer cutting waste, namely, a blowing device is additionally arranged in the smelting process of the silicon wafer cutting waste, oxidizing gas is introduced, the melted silicon wafer cutting waste is subjected to oxidizing refining, and Ca, Al and other impurities in silicon are promoted to be oxidized and enter a slag phase to be removed while silicon melt is strongly stirred, so that the preparation of high-quality silicon is realized.
A top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of the silicon wafer cutting waste to obtain silicon wafer cutting waste particles;
(2) slowly adding the silicon wafer cutting waste particles into a smelting device until the effective smelting volume of the smelting device is 1/3-1/2, and heating until the silicon wafer cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the smelting device in batches to 2/3 in the effective smelting volume of the smelting device, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of the smelting device, enabling an air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the molten silicon, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities to obtain impurity-removed silicon melt;
(4) and casting the impurity-removed silicon melt to obtain a silicon product.
The oxidizing gas comprises air, oxygen, wet oxygen or oxygen-enriched air; the oxidizing gas can also be a mixed gas of the oxidizing gas and argon, nitrogen or water; the blowing mode of the oxidizing gas can be single top blowing, top-bottom combined blowing, top-side combined blowing or top-eccentric blowing; blowing in gas not only can play the effect of edulcoration, can also acutely stir silicon melt simultaneously, thereby make the gas-liquid interface of furnace mouth department constantly renew when guaranteeing impurity abundant and edulcoration agent reaction and more do benefit to volatile impurity and volatilize and get rid of.
The aeration pressure of the oxidizing gas is 0.1-1.5MPa, and the gas flow rate is 0.2-2m3/min。
The top blowing device comprises a gas blowing pipe, a smoke collecting hood, a flue and a dust collecting device, wherein the smoke collecting hood, the flue and the dust collecting device are sequentially connected, and the gas blowing pipe penetrates through the smoke collecting hood and is inserted into the bottom of the molten silicon liquid.
Furthermore, the gas blow pipe is a heat-insulating gas guide pipe, the top blowing device further comprises a gas storage cabinet, the gas blow pipe is communicated with the gas storage cabinet, and a safety valve, a pressure reducing valve and an adjustable switch are further arranged on the gas blow pipe.
Further, the smoke collecting hood is hermetically connected with the ladle opening of the external refining device to form a closed cavity right above the ladle opening of the external refining device; the outer wall of the smoke collecting hood is connected with a crown block suspension or lifting-rotating component system. The lifting-rotating component comprises a controller, a driving servo motor I, a driving servo motor II, a transmission shaft I, a transmission shaft II and a clamping connecting rod, wherein one end of the clamping connecting rod is fixedly connected with the outer wall of the smoke collecting hood, the other end of the clamping connecting rod is fixedly connected with the top end of the transmission shaft I, the bottom end of the transmission shaft I is connected with the top end of the transmission shaft II through a ball bearing or a needle bearing, the transmission shaft I can rotate at the top end of the transmission shaft II, the bottom end of the transmission shaft II is fixedly connected with an output shaft of the driving servo motor II, the driving servo motor II is a stepping reciprocating motor, the driving servo motor I is fixedly arranged on the transmission shaft II through a supporting rod, a gear I is arranged on the output shaft of the driving servo motor I, a gear II is sleeved on; the driving servo motor I and the driving servo motor II are respectively and electrically connected with the controller.
Furthermore, a fire-resistant layer and a cooling water jacket are arranged on the outer wall of the smoke collecting hood;
smoke and dust flue gas generated at a gas-liquid interface in the smelting process is collected in a smoke collecting hood, the area of a smoke collecting hood opening can cover the whole top opening of the smelting device, and a lifting-rotating component of the smoke collecting hood can be adjusted in height according to different refining periods, for example, the smoke collecting hood can be properly lifted in the ventilation process and when a slagging agent is added, and the smoke collecting hood can be lifted to a specific height when silicon liquid is added or discharged; the fire-resistant layer of the smoke collecting hood can ensure that the smoke collecting hood can bear different smelting temperatures;
the smelting device can be a ladle furnace, a tundish, a graphite crucible or other special smelting equipment;
the heating mode of the smelting device comprises but is not limited to: resistance heating, induction heating, plasma, arc furnace heating, self-heating of reaction production or heat capacity of silicon melt, etc.;
the fume collecting hood can be in the shape of a round bottom, a conical shape, a tetrahedral frustum and the like, and the specific size and the cross section shape can be determined according to the geometric shape and the size of a top opening of a specific smelting device so as to ensure the complete connection between the fume collecting hood and a furnace opening, thereby avoiding the escape, the overflow, the leakage and the like of furnace gas and ensuring the micro negative pressure environment in the fume collecting hood;
the smoke collecting hood can be made of a stainless steel shell layer, a steel sleeve and the like, and the outer wall of the smoke collecting hood is lined with a fire-resistant layer and a cooling water jacket, so that the rigidity, the strength and the high temperature resistance of the smoke collecting hood are ensured, and the pollution of an external pollution source to the silicon melt is avoided;
the dust collecting system can be a cloth bag, cyclone, gravity or electrostatic dust collecting equipment and can simultaneously collect micro silicon powder, silicon powder and the like carried in smoke dust in the smelting process.
The invention has the beneficial effects that:
(1) in the method, a blowing device is additionally arranged in the smelting process of the silicon wafer cutting waste, oxidizing gas is introduced, the smelted silicon wafer cutting waste is subjected to oxidation refining, and Ca, Al and other impurities in silicon are promoted to be subjected to oxidation reaction and enter a slag phase to be removed while the silicon melt is strongly stirred, so that the preparation of high-quality silicon is realized;
(2) the method disclosed by the invention realizes deep removal of impurities in silicon melt produced by smelting silicon wafer cutting waste, solves the problem that the requirement of a front-end smelting process on the content of the impurities in the raw materials is high, and effectively widens the application range of the raw materials. Meanwhile, the burden of impurity control in the subsequent casting process is reduced, so that the casting process can be carried out by using a large mould, the production efficiency is improved, the unit production cost and the energy consumption are reduced, and the energy-saving emission-reducing green manufacturing of industrial silicon production is indirectly realized.
Drawings
FIG. 1 is a schematic view of a top-blowing apparatus in cooperation with a smelting apparatus;
fig. 2 is a schematic diagram of the lift-rotate system connection.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments, but the scope of the present invention is not limited to the description.
The top-blowing device and the smelting device in the embodiment of the invention are matched as shown in a schematic diagram of figure 1, the top-blowing device comprises a gas blowing pipe, a smoke collecting hood, a flue and a dust collecting device, the smoke collecting hood, the flue and the dust collecting device are sequentially connected, and the gas blowing pipe penetrates through the smoke collecting hood and is inserted to the bottom of molten silicon liquid; the top blowing device also comprises a gas storage cabinet, the gas blowing pipe is communicated with the gas storage cabinet, and a safety valve, a pressure reducing valve and an adjustable switch are arranged on the gas blowing pipe; the outer wall of the fume collecting hood is connected with a lifting-rotating component (shown in figure 2), the lifting-rotating component comprises a controller, a driving servo motor I and a driving servo motor II, the device comprises a transmission shaft I, a transmission shaft II and a clamping connecting rod, wherein one end of the clamping connecting rod is fixedly connected with the outer wall of the smoke collecting hood, the other end of the clamping connecting rod is fixedly connected with the top end of the transmission shaft I, the bottom end of the transmission shaft I is connected with the top end of the transmission shaft II through a ball bearing or a needle bearing, the transmission shaft I can rotate at the top end of the transmission shaft II, the bottom end of the transmission shaft II is fixedly connected with an output shaft of a driving servo motor II, the driving servo motor II is a stepping reciprocating motor, the driving servo motor I is fixedly arranged on the transmission shaft II through a supporting rod, a gear I is arranged on the output shaft of the driving servo motor I, a gear II is; the driving servo motor I and the driving servo motor II are respectively and electrically connected with the controller; the outer wall of the smoke collecting hood is provided with a fire-resistant layer and a cooling water jacket; smoke and dust flue gas generated at a gas-liquid interface in the refining process is collected in a smoke collecting hood, the area of a smoke collecting hood opening can cover the whole top opening of the smelting device, and a lifting-rotating component of the smoke collecting hood can be adjusted in height according to different refining periods, for example, the smoke collecting hood can be properly lifted in the ventilation process and when a slagging agent is added, and the smoke collecting hood can be lifted to a specific height when silicon liquid is added or discharged; the fire-resistant layer of the smoke collecting hood can ensure that the smoke collecting hood can bear different smelting temperatures; the smelting device can be a ladle furnace, a tundish, a graphite crucible or other special smelting equipment; heating modes of the smelting device include but are not limited to: resistance heating, induction heating, plasma, arc furnace heating, self-heating of reaction production or heat capacity of silicon melt, etc.; the smoke collecting hood can be in the shape of a round bottom, a conical shape, a tetrahedral frustum and the like, and the specific size and the cross section shape can be determined according to the geometrical shape and the size of a top opening of a specific smelting device so as to ensure the complete connection between the smoke collecting hood and a furnace opening, thereby avoiding the escape, the overflow, the leakage and the like of furnace gas and ensuring the micro negative pressure environment in the smoke collecting hood; the smoke collecting hood can be made of a stainless steel shell layer, a steel sleeve and the like, and the outer wall of the smoke collecting hood is lined with a fire-resistant layer and a cooling water jacket, so that the rigidity, the strength and the high temperature resistance of the smoke collecting hood are ensured, and the pollution of an external pollution source to the silicon melt is avoided; the dust collecting system can be a cloth bag, cyclone, gravity or electrostatic dust collecting equipment and can simultaneously collect micro silicon powder, silicon powder and the like carried in smoke dust in the smelting process.
Example 1: a top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of silicon wafer cutting waste of a certain slicing enterprise in Yunnan to obtain silicon wafer cutting waste particles; wherein the average particle size of the silicon wafer cutting waste particles is less than 3cm, the water content is less than 8%, and the impurity content in the silicon wafer cutting waste is 7600ppm and the Ca content is 2000ppm in mass percentage;
(2) slowly adding the silicon chip cutting waste particles into a graphite crucible to 1/3 of the effective smelting volume of the graphite crucible, and placing the graphite crucible into an induction furnace to be heated until the silicon chip cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the graphite crucible in batches until the volume of the graphite crucible is 2/3 of the effective smelting volume, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of an induction furnace of the smelting device, enabling the air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the silicon melt, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities such as aluminum, calcium and the like to obtain impurity-removed silicon melt; wherein the blowing mode of the oxidizing gas is top blowing, the oxidizing gas is industrial oxygen, the aeration time is 10min, the aeration pressure is 0.1-2MPa, and the gas flow rate is 0.2-3m3/min；
(4) Casting the impurity-removed silicon melt to obtain a silicon product;
the silicon product of this example has impurities of Al <300ppm and Ca <600ppm, calculated by mass percentage.
Example 2: a top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of silicon wafer cutting waste of a certain slicing enterprise in Yunnan to obtain silicon wafer cutting waste particles; wherein the average particle size of the silicon wafer cutting waste particles is less than 3cm, the water content is less than 8%, and the impurity content in the silicon wafer cutting waste is 5000ppm and the Ca content is 1000ppm in percentage by mass;
(2) slowly adding the silicon chip cutting waste particles into a graphite crucible to 1/3 of the effective smelting volume of the graphite crucible, and placing the graphite crucible into an induction furnace to be heated until the silicon chip cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the graphite crucible in batches until the volume of the graphite crucible is 2/3 of the effective smelting volume, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of an induction furnace of the smelting device, enabling the air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the silicon melt, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities such as aluminum, calcium and the like to obtain impurity-removed silicon melt; wherein the blowing mode of the oxidizing gas is top blowing, the oxidizing gas is oxygen-enriched air, the aeration time is 30min, the aeration pressure is 0.5-1MPa, and the gas flow rate is 0.1-0.2m3/min；
(4) Casting the impurity-removed silicon melt to obtain a silicon product;
the silicon product of this example had impurity levels of Al <200ppm and Ca <500ppm, as measured by mass percent.
Example 3: a top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of silicon wafer cutting waste of a certain slicing enterprise in Yunnan to obtain silicon wafer cutting waste particles; wherein the average particle size of the silicon wafer cutting waste particles is less than 3cm, the water content is less than 8%, and the impurity content in the silicon wafer cutting waste is 5000ppm and the Ca content is 500ppm in percentage by mass;
(2) slowly adding the silicon chip cutting waste particles into a graphite crucible to 1/3 of the effective smelting volume of the graphite crucible, and placing the graphite crucible into an induction furnace to be heated until the silicon chip cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the graphite crucible in batches until the volume of the graphite crucible is 2/3 of the effective smelting volume, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of an induction furnace of the smelting device, enabling the air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the silicon melt, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities such as aluminum, calcium and the like to obtain impurity-removed silicon melt; wherein the blowing mode of the oxidizing gas is top blowing, the oxidizing gas is air, the ventilation time is 20min, and the ventilation pressure is1MPa, gas flow rate of 0.3-0.4m3/min；
(4) Casting the impurity-removed silicon melt to obtain a silicon product;
the silicon product of this example had impurity levels of Al <300ppm and Ca <100ppm, as measured by mass percent.
Example 4: a top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of silicon wafer cutting waste of a certain slicing enterprise in Yunnan to obtain silicon wafer cutting waste particles; wherein the average particle size of the silicon wafer cutting waste particles is less than 3cm, the water content is less than 8%, and the impurity content in the silicon wafer cutting waste is 2000ppm and the Ca content is 3000ppm in mass percentage;
(2) slowly adding the silicon chip cutting waste particles into a graphite crucible to 1/3 of the effective smelting volume of the graphite crucible, and placing the graphite crucible into an induction furnace to be heated until the silicon chip cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the graphite crucible in batches until the volume of the graphite crucible is 2/3 of the effective smelting volume, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of an induction furnace of the smelting device, enabling the air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the silicon melt, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities such as aluminum, calcium and the like to obtain impurity-removed silicon melt; wherein the blowing mode of the oxidizing gas is top blowing, the oxidizing gas is mixed gas of industrial oxygen and argon, the volume ratio of the industrial oxygen to the argon is 2:1, the ventilation time is 40min, the ventilation pressure is 1.2MPa, and the gas flow rate is 0.5m3/min；
(4) Casting the impurity-removed silicon melt to obtain a silicon product;
the silicon product of this example has impurity contents of Al <600ppm and Ca <300ppm, calculated by mass percentage.
Example 5: a top-blown refining method of silicon wafer cutting waste comprises the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of silicon wafer cutting waste of a certain slicing enterprise in Yunnan to obtain silicon wafer cutting waste particles; wherein the average particle size of the silicon wafer cutting waste particles is less than 3cm, the water content is less than 8%, and the impurity content in the silicon wafer cutting waste is 3600ppm and the Ca content is 1200ppm in percentage by mass;
(2) slowly adding the silicon chip cutting waste particles into a graphite crucible to 1/3 of the effective smelting volume of the graphite crucible, and placing the graphite crucible into an induction furnace to be heated until the silicon chip cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the graphite crucible in batches until the volume of the graphite crucible is 2/3 of the effective smelting volume, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of an induction furnace of the smelting device, enabling the air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the silicon melt, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities such as aluminum, calcium and the like to obtain impurity-removed silicon melt; wherein the blowing mode of the oxidizing gas is top blowing, the oxidizing gas is mixed gas of industrial oxygen and water vapor, the volume ratio of the industrial oxygen to the water vapor is 3:1, the aeration time is 60min, the aeration pressure is 1.0MPa, and the gas flow rate is 0.6m3/min；
(4) Casting the impurity-removed silicon melt to obtain a silicon product;
the silicon product of this example had impurity levels of Al <500ppm and Ca <300ppm, as measured by mass percent.
Claims (7)
1. A top-blown refining method for silicon wafer cutting waste is characterized by comprising the following specific steps:
(1) drying, crushing and screening a filter cake obtained by filter pressing of the silicon wafer cutting waste to obtain silicon wafer cutting waste particles;
(2) slowly adding the silicon wafer cutting waste particles into a smelting device until the effective smelting volume of the smelting device is 1/3-1/2, and heating until the silicon wafer cutting waste particles are molten; maintaining the temperature in the furnace at 1500-1600 ℃, adding the silicon wafer cutting waste particles into the smelting device in batches to 2/3 in the effective smelting volume of the smelting device, and heating until the silicon wafer cutting waste particles are molten to obtain molten silicon;
(3) moving the top blowing device to be right above a furnace mouth of the smelting device, enabling an air blowing mouth to be positioned at the bottom of the molten silicon liquid, blowing oxidizing gas into the molten silicon, and carrying out top blowing oxygen-enriched refining on the molten silicon liquid to remove impurities to obtain impurity-removed silicon melt;
(4) and casting the impurity-removed silicon melt to obtain a silicon product.
2. The top-blown refining method of silicon wafer cutting scraps as claimed in claim 1, wherein: the oxidizing gas includes air, oxygen, wet oxygen, or oxygen-enriched air.
3. The top-blown refining method of silicon wafer cutting scraps as set forth in claim 1 or 2, characterized in that: the aeration pressure of the oxidizing gas is 0.1-1.5MPa, and the gas flow rate is 0.2-2m3/min。
4. The top-blown refining method of silicon wafer cutting scraps as claimed in claim 1, wherein: the top blowing device comprises a gas blowing pipe, a smoke collecting hood, a flue and a dust collecting device, wherein the smoke collecting hood, the flue and the dust collecting device are sequentially connected, and the gas blowing pipe penetrates through the smoke collecting hood and is inserted to the bottom of the molten silicon liquid.
5. The method for top-blown refining of silicon wafer cutting waste according to claim 4, wherein: the gas blow pipe is a heat-insulation gas guide pipe, the top blowing device further comprises a gas storage cabinet, the gas blow pipe is communicated with the gas storage cabinet, and a safety valve, a pressure reducing valve and an adjustable switch are further arranged on the gas blow pipe.
6. The top-blown refining method of silicon wafer cutting scraps as set forth in claim 4 or 5, wherein: the smoke collecting hood is hermetically connected with the ladle opening of the external refining device to form a closed cavity; the outer wall of the smoke collecting hood is connected with a crown block suspension or lifting-rotating component system.
7. The method for top-blown refining of silicon wafer cutting waste according to claim 6, characterized in that: the lifting-rotating component comprises a controller, a driving servo motor I, a driving servo motor II, a transmission shaft I, a transmission shaft II and a clamping connecting rod, one end of the clamping connecting rod is fixedly connected with the outer wall of the smoke collecting hood, the other end of the clamping connecting rod is fixedly connected with the top end of the transmission shaft I, the bottom end of the transmission shaft I is connected with the top end of the transmission shaft II through a ball bearing or a needle bearing, the transmission shaft I can rotate at the top end of the transmission shaft II, the bottom end of the transmission shaft II is fixedly connected with an output shaft of the driving servo motor II, the driving servo motor II is a stepping reciprocating motor, the driving servo motor I is fixedly arranged on the transmission shaft II through a supporting rod, a gear I is arranged on the output shaft of the driving servo motor I, a gear II is sleeved; the driving servo motor I and the driving servo motor II are respectively and electrically connected with the controller.
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