Apparatus for treating impurities in polysilicon and monocrystalline silicon powder

Abstract

The application discloses a kind of polycrystalline silicon and single crystal silicon powder impurity processing equipment, the output shaft of driving motor extends to the inside of shell coaxially connected transmission shaft, transmission shaft is fixedly connected with reversing gear, the output end of reversing gear is multiple driven shafts perpendicular to transmission shaft, the output end of each driven shaft is fixed with a rotating stirring wheel outside coaxial center;Each rotating stirring wheel is opened on the side wall of processing groove, the inner surface of processing groove is integrally fixed with a layer of frosted layer, silicon powder enters the inside of processing groove and rubs with frosted layer;After silicon powder is ground, chemical reagent is added in shell by liquid inlet pipe to carry out surface treatment to silicon powder, is fully stirred and mixed by rotating stirring wheel, improve the surface treatment efficiency of silicon powder, and by air inlet pipe, air outlet pipe and transmission shaft and rotating stirring wheel are accurately matched simultaneously to carry out surface treatment and heating of silicon powder, further improve the surface treatment efficiency of silicon powder.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of manufacturing of polycrystalline silicon and monocrystalline silicon, and more particularly, to an apparatus and method for removing impurities in polycrystalline silicon and monocrystalline silicon powder. BACKGROUND

[0002] The production of polycrystalline silicon is to change low-grade industrial silicon into high-purity polycrystalline silicon, and the purpose is to continue to remove residual impurities so as to make the silicon reach ultra-high purity. The production of monocrystalline silicon not only removes unnecessary impurities, but also artificially adds some useful dopants to make it have special electrical properties. The unnecessary impurities in monocrystalline silicon include nitrogen, hydrogen and some metal impurities, etc. In addition, during the growth of monocrystalline silicon, especially when using the Czochralski method to prepare monocrystalline silicon, other unnecessary impurities such as oxygen and carbon will be introduced. Polycrystalline silicon and monocrystalline silicon will generate powder during the cutting process, and the powder contains impurities. Therefore, removing the impurities contained in the powder can further realize the recycling of the silicon powder.

[0003] The existing silicon powder needs to add various chemical agents during the treatment process. The mixture of silicon powder and chemical agents is first stirred, and then dried by electric heating. This way is low in efficiency, and some impurities on the surface of the silicon powder are not removed, and the electric heating is also uneven.

[0004] Chinese Patent No. CN201010280712.5, entitled "Method for recycling silicon and silicon carbide from monocrystalline silicon and polycrystalline silicon cutting waste", mixes hydrochloric acid and dried cutting powder, stirs, washes and filters, respectively recycles silicon and silicon carbide by water washing and filtering, and recovers the solvent, and improves the purity of the powder by extraction separation and enrichment. Chinese Patent Publication No. CN108383122A, entitled "Ultrafine polycrystalline silicon powder recycling method", puts the polycrystalline silicon particles into a power frequency induction furnace with a high-purity graphite crucible as the conductor, and passes high-purity argon gas as a protective gas to heat the polycrystalline silicon particles, and adds a slagging agent to the molten liquid to remove slag. The treatment process of these two kinds of silicon powder waste is complex, time-consuming and energy-consuming, and the surface treatment of the silicon powder is not thorough enough. SUMMARY

[0005] 1. Technical problem

[0006] In view of the problems existing in the prior art, the purpose of the present application is to provide an impurity treatment equipment for polycrystalline silicon and monocrystalline silicon powder, which can realize thorough surface treatment of the impurity powder after surface treatment of the chemical agent, remove the impurities remaining on the surface of the powder, and use hot gas heating to avoid the problem of uneven heating of the powder caused by electric heating.

[0007] 2. Technical solution

[0008] In order to solve the above problems, the polycrystalline silicon and single crystal silicon powder impurity treatment equipment adopts the following technical scheme: a circular shell, the top of the shell is sealingly connected with a top cover, the top cover is respectively provided with a feeding pipe, a liquid inlet pipe, a gas inlet pipe and a gas outlet pipe extending into the shell, a vertical driving motor is fixedly arranged at the top center of the top cover, the output shaft of the driving motor extends downward into the shell and is coaxially connected with a transmission shaft, a reversing transmission is fixedly connected to the transmission shaft, the output end of the reversing transmission is a plurality of driven shafts perpendicular to the transmission shaft, each driven shaft is connected to the transmission shaft through a respective transmission gear set, and each driven shaft is coaxially fixedly sleeved with a rotating stirring wheel at the output end thereof.

[0009] Further, a treatment groove is formed in the side wall of each rotating stirring wheel, a baffle is arranged at the inlet of the treatment groove away from the driven shaft, a distance is left between the baffle and the inlet of the treatment groove, a reflux channel is formed in the treatment groove at the outlet close to the driven shaft, and the reflux channel penetrates the inside of the shell.

[0010] Further, at least two driven shafts and corresponding rotating stirring wheels are uniformly arranged along the circumferential direction of the transmission shaft; and at least two layers of driven shafts and corresponding rotating stirring wheels are arranged along the axial direction of the transmission shaft.

[0011] Further, the inner surface of the treatment groove is integrally fixedly bonded with a ground layer, and the silicon powder rubs against the ground layer when entering the inside of the treatment groove.

[0012] 3. Beneficial effects

[0013] Compared with the prior art, the polycrystalline silicon and single crystal silicon powder impurity treatment equipment has the following advantages:

[0014] After the silicon powder is ground, the chemical reagent is added through the liquid inlet pipe for surface treatment of the silicon powder in the shell, the rotating stirring wheel is used for sufficient stirring and mixing, the surface treatment efficiency of the silicon powder is improved, and through the precise cooperation of the gas inlet pipe, the gas outlet pipe, the transmission shaft and the rotating stirring wheel, the surface treatment and heating of the silicon powder can be carried out at the same time, the surface treatment efficiency of the silicon powder is further improved, and the surface treatment of the silicon powder is not incomplete. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic view of the overall structure of the polycrystalline silicon and single crystal silicon powder impurity treatment equipment;

[0016] Figure 2 It is an exploded view of Figure 1

[0017] Figure 3 It is an assembly structure front view of the main components contained in the shell of Figure 1

[0018] Figure 4 It is an assembly structure front view of the main components contained in the shell of​​Figure 1 Assembly structure of middle base, shell, discharge port and discharge valve;

[0019] Figure 5 For Figure 3 Enlarged view of middle local part A structure.

[0020] Explanation of figure mark:

[0021] 1, base; 2, shell; 3, discharge port; 4, discharge valve; 5, top cover; 6, feeding pipe; 7, liquid inlet pipe; 8, gas inlet pipe; 9, gas outlet pipe; 10, driving motor; 11, fixed seat; 12, transmission shaft; 13, reversing transmission; 14, driven shaft; 15, rotating stirring wheel; 16, treatment tank; 17, sanding layer; 18, baffle; 19, backflow channel. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application; obviously, the described embodiments are only part of the embodiments of the present application but not all the embodiments of the present application, and all other embodiments obtained by those skilled in the art without creative labor on the basis of the embodiments in the present application belong to the protection scope of the present application.

[0023] Referring to 1-3, the present application is a kind of impurity processing equipment in polycrystalline silicon and single crystal silicon powder, including base 1, base 1 is placed on the ground and fixed, the top of base 1 is fixedly connected with a circular shell 2, the bottom of shell 2 is provided with discharge port 3, discharge valve 4 is arranged at discharge port 3, and discharge valve 4 controls the opening and closing of discharge port 3.

[0024] Discharge port 3 extends to the inside of shell 2 from bottom to top, and the height of discharge port 3 is less than the height of base 1, so that the silicon powder after processing can be transported for the next process.

[0025] Referring to Figures 1-3 As shown, the top of shell 2 is open, and the open part is sealingly connected with top cover 5. Feeding pipe 6, liquid inlet pipe 7, gas inlet pipe 8 and gas outlet pipe 9 are arranged on top cover 5 respectively, and feeding pipe 6, liquid inlet pipe 7, gas inlet pipe 8 and gas outlet pipe 9 all extend to the inside of shell 2 from the outside of shell 2 through top cover 5. Driving motor 10 is fixedly arranged at the top center of top cover 5, and driving motor 10 is vertically arranged, and its output shaft extends to the inside of shell 2 through top cover 5. Fixed seat 11 is fixedly connected to the top of top cover 5, and the shell of driving motor 10 is fixedly connected above fixed seat 11.

[0026] The silicon powder enters the housing 2 through the feeding pipe 6, the chemical agent is added into the housing 2 through the liquid feeding pipe 7, and the heating gas is introduced into the housing 2 through the gas feeding pipe 8 to heat the silicon powder. The impurity gas is discharged from the housing 2 through the gas discharging pipe 9 to improve the impurity treatment speed of the silicon powder.

[0027] The transmission shaft 12, the reversing transmission 13 and the rotating stirring wheel 15 are accommodated in the housing 2. The output end of the driving motor 10 is fixed coaxially connected with the transmission shaft 12 to drive the transmission shaft 12 to rotate in the center of the housing 2 and provide the driving force for stirring in the housing 2.

[0028] The reversing transmission 13 is fixedly connected with the transmission shaft 12, and the output end of the reversing transmission 13 is a plurality of driven shafts 14 which are perpendicular to the transmission shaft 12. The reversing transmission 13 is composed of a gear transmission mechanism, and the perpendicular rotation of the transmission shaft 12 is converted into the horizontal rotation of the plurality of driven shafts 14 through bevel gears or through a circular rack. Each driven shaft 14 is commonly connected with the transmission shaft 12 through respective transmission gear sets. The output end of each driven shaft 14 is coaxially fixed with a rotating stirring wheel 15, and the rotating stirring wheel 15 rotates with the driven shaft 14.

[0029] Along the circumferential direction of the transmission shaft 12, at least two driven shafts 14 and corresponding two rotating stirring wheels 15 are uniformly arranged. Along the axial direction of the transmission shaft 12, at least two layers of driven shafts 14 and corresponding two rotating stirring wheels 15 are arranged up and down.

[0030] A treatment groove 16 is opened on the side wall of each rotating stirring wheel 15. The treatment groove 16 is an inlet away from the driven shaft 14, and a baffle 18 is arranged at the inlet of the treatment groove 16, and a distance is left between the baffle 18 and the inlet of the treatment groove 16. The treatment groove 16 is an outlet near the driven shaft 14, and a reflux channel 19 is opened at the outlet position of the treatment groove 16, and the reflux channel 19 penetrates the inside of the housing 2.

[0031] The treatment groove 16 is a trapezoidal groove structure, and the inlet away from the driven shaft 14 is the bottom of the trapezoid, and the outlet end near the driven shaft 14 is the top of the trapezoid.

[0032] A frosted layer 17 is fixedly adhered to the inner surface of the processing tank 16. When silicon powder enters the processing tank 16, the silicon powder rubs against the frosted layer 17 as the rotating stirring wheel 15 rotates, removing impurities from the surface of the silicon powder. Because the centrifugal force of the rotating stirring wheel 15 is relatively large, it may throw the silicon powder away, making it difficult to treat effectively. Therefore, a baffle 18 is installed at the inlet of the processing tank 16 to block some of the silicon powder from being thrown out. During the latter half of the rotation of the rotating stirring wheel 15, this portion of silicon powder flows into the bottom of the housing 2 through the return channel 19, continuing to undergo surface treatment by the rotating stirring wheel 15. The rotating stirring wheel 15 thoroughly stirs and mixes the silicon powder, improving the efficiency of surface impurity removal.

[0033] The silicon powder undergoes surface impurity treatment through the coordinated operation of the drive shaft 12, reversing drive 13, rotating stirring wheel 15, abrasive layer 17, baffle 18, and return channel 19, further improving the surface treatment efficiency and preventing incomplete surface treatment. The silicon powder, after passing through the abrasive layer 17, is then reintroduced into the lower rotating stirring wheel 15 via the return channel 19, increasing the stirring rate of the silicon powder per unit time.

[0034] During operation, silicon powder is fed through the feed pipe 6, chemical reagents are added through the liquid inlet pipe 7, heating gas is introduced through the air inlet pipe 8, and impurity gas is discharged through the air outlet pipe 9. The drive motor 10 operates, and the drive motor 10 and transmission shaft 12 provide the driving force for stirring. Under the steering action of the reversing transmission 13, the rotating stirring wheel 15 is driven to fully stir and mix the mixture inside the shell 2. The silicon powder passing through the abrasive layer 17 is thrown into the return channel 19, and then reintroduced into the lower rotating stirring wheel 15, increasing the stirring rate of the iron-silicon alloy powder per unit time. After processing, the discharge valve 4 is opened, and the cleaned silicon powder is conveyed out from the discharge port 3 for the next processing step.

Claims

1. An impurity treatment device for polycrystalline silicon and monocrystalline silicon powder, comprising a circular housing (2), the top of which is open and sealed with a top cover (5), characterized in that: The top cover (5) is provided with a feed pipe (6), a liquid inlet pipe (7), an air inlet pipe (8) and an air outlet pipe (9) extending into the shell (2). A vertical drive motor (10) is fixedly installed at the top center of the top cover (5). The output shaft of the drive motor (10) extends downward into the shell (2) and is coaxially connected to the transmission shaft (12). A reversing drive (13) is fixedly connected to the transmission shaft (12). The output end of the reversing drive (13) is a plurality of driven shafts (14) perpendicular to the transmission shaft (12). Each driven shaft (14) is connected to the transmission shaft (12) through its own transmission gear set. A rotating stirring wheel (15) is coaxially fixedly sleeved on the output end of each driven shaft (14). Each rotating stirring wheel (15) has a processing tank (16) on its side wall. A baffle (18) is provided at the inlet of the processing tank (16) away from the driven shaft (14). There is a distance between the baffle (18) and the inlet of the processing tank (16) to block some of the silicon powder from being thrown out. A return channel (19) is provided at the outlet of the processing tank (16) near the driven shaft (14). The return channel (19) runs through the inside of the shell 2. A frosted layer (17) is fixedly adhered to the inner surface of the processing tank (16). When silicon powder enters the processing tank (16), it rubs against the frosted layer (17). The processing tank (16) has a trapezoidal tank structure. The inlet away from the driven shaft (14) is the bottom of the trapezoid, and the outlet end near the driven shaft (14) is the top of the trapezoid.

2. The impurity treatment equipment for polycrystalline silicon and monocrystalline silicon powder according to claim 1, characterized in that: Along the circumferential direction of the drive shaft (12), at least two driven shafts (14) and two corresponding rotating stirring wheels (15) are evenly arranged; along the axial direction of the drive shaft (12), at least two layers of driven shafts (14) and two corresponding rotating stirring wheels (15) are arranged.

3. The impurity treatment equipment for polycrystalline silicon and monocrystalline silicon powder according to claim 1, characterized in that: The bottom of the shell (2) is provided with a discharge port (3), and a discharge valve (4) is provided at the discharge port (3).

4. The impurity treatment equipment for polycrystalline silicon and monocrystalline silicon powder according to claim 1, characterized in that: Silicon powder enters the housing (2) through the feed pipe (6), chemical agents are added into the housing (2) through the liquid inlet pipe (7), heating gas is introduced into the housing (2) through the gas inlet pipe (8), and impurity gas is discharged from the housing (2) through the gas outlet pipe (9).

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