CN115557507A - Method and system for separating silicon powder from chlorosilane-containing slurry and application of method and system - Google Patents
Method and system for separating silicon powder from chlorosilane-containing slurry and application of method and system Download PDFInfo
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- CN115557507A CN115557507A CN202211370069.4A CN202211370069A CN115557507A CN 115557507 A CN115557507 A CN 115557507A CN 202211370069 A CN202211370069 A CN 202211370069A CN 115557507 A CN115557507 A CN 115557507A
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- 239000002002 slurry Substances 0.000 title claims abstract description 182
- 239000005046 Chlorosilane Substances 0.000 title claims abstract description 121
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 title claims abstract description 121
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 114
- 239000011863 silicon-based powder Substances 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000000926 separation method Methods 0.000 claims abstract description 85
- 239000002245 particle Substances 0.000 claims abstract description 77
- 238000010438 heat treatment Methods 0.000 claims abstract description 66
- 239000007790 solid phase Substances 0.000 claims abstract description 65
- 238000001035 drying Methods 0.000 claims abstract description 57
- 239000002893 slag Substances 0.000 claims abstract description 17
- 239000006228 supernatant Substances 0.000 claims abstract description 15
- 230000000149 penetrating effect Effects 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 48
- 239000007787 solid Substances 0.000 claims description 39
- 238000005243 fluidization Methods 0.000 claims description 34
- 230000008569 process Effects 0.000 claims description 29
- 238000011084 recovery Methods 0.000 claims description 21
- 239000008247 solid mixture Substances 0.000 claims description 17
- 239000007788 liquid Substances 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 13
- 238000007599 discharging Methods 0.000 claims description 11
- 238000007789 sealing Methods 0.000 claims description 9
- 239000004744 fabric Substances 0.000 claims description 7
- 239000007791 liquid phase Substances 0.000 claims description 7
- 230000035699 permeability Effects 0.000 claims description 7
- 239000002210 silicon-based material Substances 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 5
- 238000009833 condensation Methods 0.000 claims description 4
- 230000005494 condensation Effects 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 27
- 239000012535 impurity Substances 0.000 abstract description 7
- 238000010924 continuous production Methods 0.000 abstract description 5
- 230000006872 improvement Effects 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 238000005265 energy consumption Methods 0.000 description 6
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 6
- 239000000428 dust Substances 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 230000002349 favourable effect Effects 0.000 description 4
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- 238000010586 diagram Methods 0.000 description 3
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- 239000002912 waste gas Substances 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
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- 238000003825 pressing Methods 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000005049 silicon tetrachloride Substances 0.000 description 2
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 2
- 239000005052 trichlorosilane Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
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- 238000007664 blowing Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000011164 primary particle Substances 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
- C01B33/08—Compounds containing halogen
- C01B33/107—Halogenated silanes
- C01B33/10778—Purification
-
- 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
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention discloses a method and a system for separating silicon powder from chlorosilane-containing slurry and application thereof. The method comprises the following steps: carrying out standing layering treatment on the slag slurry containing chlorosilane to obtain solid-phase slurry and supernatant; crushing the solid-phase slurry to obtain slurry particles; heating the slurry particles by using a fluidized drying device to obtain dried silicon powder and chlorosilane gas, wherein the fluidized drying device comprises an outer cylinder and an inner cylinder penetrating the outer cylinder, an annular cavity is formed between the outer cylinder and the inner cylinder, and micropores are formed on the wall of the inner cylinder, and the aperture of each micropore is not more than 0.5 mu m; and (3) feeding the slurry particles into the inner cylinder, and introducing fluidizing hot air into the inner cylinder to volatilize the chlorosilane. The method has the advantages of good separation effect, high efficiency, realization of effective separation of the chlorosilane and the silicon powder, higher yield of the chlorosilane and the silicon powder, less impurity content, high purity, realization of continuous production and great improvement of the treatment capacity of the slurry.
Description
Technical Field
The invention belongs to the field of polycrystalline silicon, and particularly relates to a method and a system for separating silicon powder from chlorosilane-containing slurry and application of the method and the system.
Background
By adopting the cold hydrogenation process, the byproduct silicon tetrachloride in the production process of the polycrystalline silicon can be converted into trichlorosilane, and the trichlorosilane can be used as a raw material for producing the polycrystalline silicon, so that the closed loop of the process in the production process of the polycrystalline silicon is realized. The cold hydrogenation reaction is mainly carried out in a fluidized bed by taking hydrogen, silicon tetrachloride and solid silicon powder as raw materials, the obtained chlorosilane product contains solid silicon powder escaping from the fluidized bed, in the operation of separating chlorosilane from solid micro powder, dry dust removal is usually carried out firstly to remove large-particle silicon powder, then wet dust removal is carried out to remove a large amount of fine silicon powder, and the chlorosilane containing about 2-8 wt% of fine silicon powder impurities and obtained by wet dust removal is called as slag slurry.
With the continuous increase of the polysilicon production capacity, the amount of the slag slurry generated by the cold hydrogenation process and the content of fine silicon powder impurities in the slag slurry are also at a higher level. The process of the slurry treatment at the present stage mainly combines multiple complex solid-liquid separation processes of standing, vacuum drum, drying by a dryer and the like, the liquid phase chlorosilane recovery rate of the slurry finally reaches about 97%, the separated solid silicon powder impurities still contain 1-3 wt% of chlorosilane and need to be further subjected to hydrolysis treatment, the treatment cost is high, and the generated waste water and waste gas can cause environmental pollution.
Disclosure of Invention
The present invention is directed to solving, at least in part, one of the technical problems in the related art. To this end, an object of the present invention is to propose a process, a system and the use thereof for separating silicon powder from a chlorosilane-containing slurry. The method has the advantages of good separation effect, high efficiency, realization of effective separation of the chlorosilane and the silicon powder, higher yield of the chlorosilane and the silicon powder, less impurity content, high purity, realization of continuous production and great improvement of the treatment capacity of the slurry.
In one aspect of the invention, a process for separating silicon powder from a chlorosilane-containing slurry is provided. According to an embodiment of the invention, the method comprises:
(1) Carrying out standing layering treatment on the slag slurry containing chlorosilane to obtain solid-phase slurry and supernatant;
(2) Crushing the solid-phase slurry to obtain slurry particles;
(3) Heating the slurry particles by using a fluidized drying device to obtain dried silicon powder and chlorosilane gas, wherein in the step (3), the fluidized drying device comprises an outer cylinder and an inner cylinder penetrating through the outer cylinder, a closed annular cavity is formed between the outer cylinder and the inner cylinder, micropores are arranged on the wall of the inner cylinder in the annular cavity, the pore diameter of the micropores is not more than 0.5 mu m, and a gas outlet is arranged on the outer cylinder; the heating treatment comprises: and supplying the slurry particles into the inner cylinder, and introducing fluidizing hot air into the inner cylinder to volatilize chlorosilane and discharge the chlorosilane through the gas outlet. The method for separating silicon powder from chlorosilane-containing slurry of the embodiment of the invention at least has the following beneficial effects: 1) Most of chlorosilane can be separated and recovered from the slurry through standing and layering; the slurry particles are heated by combining the fluidized drying device, so that the silicon powder and residual chlorosilane in the slurry particles can be effectively separated, and the dried silicon powder and chlorosilane can be respectively recovered; 2) The recovery rate of chlorosilane in the slurry can reach more than 99.5 percent, the silicon powder obtained by separation has higher purity and no obvious chlorosilane smell, and the problem of environmental pollution caused by waste water and waste gas generated by washing because of higher content of chlorosilane impurities in the silicon powder is solved; 3) The silicon powder obtained by separation has high drying degree, is convenient to collect, has stable performance, is beneficial to storage and transportation, and can be sold as a raw material; 4) The whole process flow can be continuously carried out on the whole, and compared with the existing intermittent production flow, the process flow has higher treatment capacity, separation efficiency and effect on the slag slurry, and has lower investment and operation energy consumption.
In addition, the method for separating silicon powder from chlorosilane-containing slurry according to the above embodiment of the invention may further have the following additional technical features:
in some embodiments of the invention, in step (1), the slurry has a solids content of 1 to 8wt%.
In some embodiments of the invention, in the step (1), the standing layering treatment time is 0.5-3 h.
In some embodiments of the invention, the moisture content in the solid phase slurry is 10 to 40wt%.
In some embodiments of the invention, the slurry particles have a particle size of no greater than 1mm.
In some embodiments of the invention, nitrogen and/or an inert gas is used as the fluidizing hot air.
In some embodiments of the invention, the fluidized drying device further comprises: the fluidization air pipe is arranged outside the outer cylinder body and penetrates through the outer cylinder body to be connected with the fluidization nozzle.
In some embodiments of the invention, the fluidized drying device further comprises: the heating piece is arranged in the annular cavity.
In some embodiments of the invention, the feed end and the discharge end of the inner cylinder are arranged one above the other.
In some embodiments of the present invention, the temperature of the heat treatment is 200 to 250 ℃, and the time of the heat treatment is not less than 100s.
In some embodiments of the invention, the fluidizing hot air has a flow velocity of 0.02 to 0.05m/s.
In some embodiments of the invention, the pressure in the annular cavity is 0.1-0.5 MPa, and the pressure in the annular cavity is not higher than the pressure in the inner cylinder.
In some embodiments of the present invention, the length of the outer cylinder is 4 to 18m, and the length of the inner cylinder is not less than the length of the outer cylinder.
In some embodiments of the invention, the aspect ratio of the inner cylinder is (100 to 150): 1, the length-diameter ratio of the outer cylinder body is (100-150): 5.
in some embodiments of the present invention, the gas-solid mixture obtained by heating treatment is subjected to gas-solid separation to obtain the dry silicon powder.
In some embodiments of the present invention, the supply of the fluidizing hot air is stopped when the gas-solid mixture obtained by the heating treatment is discharged from the inner cylinder.
In some embodiments of the present invention, the particle size of the dried silicon powder is 0.5-30 μm.
In some embodiments of the invention, the fluidized drying device comprises a plurality of the fluidizing nozzles, at least part of which are arranged at intervals along the length direction of the inner cylinder.
In some embodiments of the present invention, the heat generating member is disposed on or adjacent to an inner wall of the outer cylinder, and the fluidization air duct is wound around the outer cylinder and extends along a length direction of the outer cylinder.
In some embodiments of the invention, the inner cylinder is arranged vertically, and the gas injection direction of the fluidizing nozzle forms an obtuse angle with the vertical downward direction.
In some embodiments of the invention, the fluidized drying device comprises at least 8 of the fluidizing nozzles.
In some embodiments of the present invention, the inner cylinder comprises a plurality of sub-cylinders which are communicated end to end, and two adjacent sub-cylinders are connected in a sealing manner.
In some embodiments of the invention, the heat generating members are arranged along the length of the annular chamber.
In some embodiments of the invention, the air permeability of the inner cylinder is not less than 20m 3 /m 2 ·h。
In some embodiments of the present invention, the number of the sub-cylinders is 8 to 12, and the length of a single sub-cylinder is 0.6 to 1.5m.
In some embodiments of the invention, two adjacent sub-cylinders are connected by an expansion joint in a sealing manner.
In some embodiments of the present invention, at least one fluidizing nozzle is disposed on each sub-cylinder, and at least one fluidizing nozzle is disposed on each sub-cylinder near the discharge end.
In yet another aspect of the invention, a separation system for carrying out the above-described method for separating silicon powder from a chlorosilane-containing slurry is provided. According to an embodiment of the invention, the system comprises: a standing device, a crushing device, the fluidized drying device and a gas-solid separation device. The standing device comprises a slag slurry inlet, a supernatant outlet and a solid-phase slurry outlet; the crushing device comprises a solid-phase slurry inlet and a slurry particle outlet, and the solid-phase slurry inlet is connected with the solid-phase slurry outlet; the feed end of the inner cylinder of the fluidized drying device is connected with the slurry particle outlet, and the gas outlet on the outer cylinder of the fluidized drying device is connected with the chlorosilane recovery tank; the gas-solid separation device comprises a gas-solid mixture inlet, a first tail gas outlet and a dried silicon powder outlet, and the gas-solid mixture inlet is connected with the discharge end of the inner barrel. Compared with the prior art, the system has the advantages of high separation efficiency, good separation effect on the slurry, capability of improving the yield of chlorosilane and dry silicon powder, stable performance of the dry silicon powder obtained by separation, capability of serving as a raw material for sale and the like, low investment and operation energy consumption, and capability of realizing continuous production.
In addition, the separation system for implementing the method for separating silicon powder from chlorosilane-containing slurry according to the embodiment of the invention can also have the following additional technical features:
in some embodiments of the present invention, the standing means, the crushing means, the fluidized drying means and the gas-solid separating means are arranged one above the other.
In some embodiments of the invention, the separation system further comprises: and the feeding device is arranged between the crushing device and the inner cylinder body and is suitable for supplying slurry particles into the inner cylinder body.
In some embodiments of the invention, the feed end of the inner cylinder is provided with a feed valve, the discharge end of the inner cylinder is provided with a discharge valve, and the feed valve and the discharge valve are not opened at the same time.
In some embodiments of the invention, the lower part of the standing device is provided with a visible liquid level area.
In some embodiments of the present invention, in the standing device, the solid-phase slurry outlet is provided with a material passing sensor, and the material passing sensor is configured to automatically close the solid-phase slurry outlet when a liquid phase passes through the material passing sensor.
In some embodiments of the invention, the chlorosilane recovery tank further comprises a second tail gas outlet and a chlorosilane condensate outlet.
In some embodiments of the invention, the feed valve and the discharge valve of the inner cylinder are respectively and independently opened and closed intermittently.
In some embodiments of the invention, a crushing assembly is also provided within the feeding device.
In some embodiments of the invention, the lower part of the standing device is provided with a conical area, and the visible liquid level area is arranged in the conical area.
In some embodiments of the invention, the gas-solid separation device is connected with the discharge end of the inner cylinder body through a hydraulic quick connector; and/or the gas-solid separation device further comprises a silicon material receiving device, a multilayer filter cloth bag is arranged in the gas-solid separation device, and the dry silicon powder outlet is arranged at the bottom of the multilayer filter cloth bag and connected with the silicon material receiving device through a conical back mixing baffle.
In a further aspect of the invention, the invention proposes the use of a separation system for carrying out the above-described process for separating silicon powder from a chlorosilane-containing slurry and for carrying out the above-described process for separating silicon powder from a chlorosilane-containing slurry for the recovery of finely divided silicon powder. The application has all the technical characteristics and effects of the method for separating silicon powder from chlorosilane-containing slurry and the separation system for implementing the method for separating silicon powder from chlorosilane-containing slurry, and the description is omitted here. In general, the recovery of the fine silicon powder is more favorably realized, and the fine silicon powder with higher purity and stable performance is obtained.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow diagram of a process for separating silicon powder from a chlorosilane-containing slurry according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of a separation system according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of a separation system according to one embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "length", "upper", "lower", "vertical", "horizontal", "bottom", "inner", "outer", "circumferential", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In one aspect, the present invention provides a method for separating silicon powder from a chlorosilane-containing slurry, which is understood in conjunction with fig. 1-2 and according to an embodiment of the present invention, and includes:
s100: carrying out standing layering treatment on the slag slurry containing chlorosilane to obtain solid-phase slurry and supernatant
According to the embodiment of the invention, the slurry containing chlorosilane is subjected to standing layering, so that the initial separation of solid phase substances in the slurry can be realized, and the supernatant obtained by separation can be used for recovering chlorosilane.
In accordance with embodiments of the present invention, chlorosilane-containing slag slurries include, but are not limited to, slag slurries produced during the production of cold hydrogenation processes, such as other slag slurries having similar compositional properties that may also be produced during the production of polycrystalline silicon. In addition, it should be noted that the solid content in the slurry is not particularly limited, and those skilled in the art can flexibly select the solid content according to the actual needs, for example, the solid content of the slurry can be 1-8 wt%. In addition, the time for carrying out the standing and layering treatment on the slurry is not particularly limited, and a person skilled in the art can flexibly select the time according to the actual needs of the slurry composition, the solid content and the like, for example, the time for carrying out the standing and layering treatment can be 0.5 to 3 hours for the slurry with the solid content of 1 to 8 weight percent, so that the solid phase and the liquid phase can be preliminarily separated. Furthermore, the moisture content of the solid-phase slurry at the bottom layer obtained by standing and layering treatment can be 10-40 wt%, for example, 20wt% or 30wt%, and the like, so that the efficiency and effect of subsequent separation and drying of silicon powder can be improved, and the high recovery rate of chlorosilane can be ensured.
S200: crushing the solid-phase slurry to obtain slurry particles
According to the embodiment of the invention, the solid-phase slurry is crushed, so that the specific surface area of the solid-phase slurry can be increased, the fluidization degree in the subsequent heating treatment process is improved, and the solid-phase slurry is fully contacted with the fluidization hot air, thereby being more beneficial to realizing the fluidization crushing of the particle materials, the full vaporization of the chlorosilane and the dispersion of the silicon powder, and further realizing the full separation and recovery of the chlorosilane and the silicon powder in the solid-phase slurry. Further, after the slurry is crushed, the particle size of the slurry particles can be not larger than 1mm, so that the slurry particles have a higher specific surface area, and the separation efficiency and effect of the silicon powder and the chlorosilane in the subsequent heating treatment process can be improved.
S300: heating the slurry particles by using a fluidized drying device so as to obtain dry silicon powder and chlorosilane gas
According to an embodiment of the present invention, as will be understood with reference to fig. 2, the fluidized drying device 100 for performing the heat treatment comprises an outer cylinder 110 and an inner cylinder 120 penetrating the outer cylinder, a closed annular chamber 130 is formed between the outer cylinder 110 and the inner cylinder 120, micropores (not shown in the figure, preferably micropores are uniformly distributed on the wall of the inner cylinder 120 in the annular chamber 130) are arranged on the wall of the inner cylinder 120 located in the annular chamber 130, the diameter of the micropores is not more than 0.5 μm, and the outer cylinder 120 is provided with a plurality of holesThe cylinder 110 is provided with a gas outlet 111. The heat treatment includes: the slurry particles are supplied into the inner cylinder 120 while fluidizing hot air is introduced into the inner cylinder 120 to volatilize the chlorosilane and discharge it through the gas outlet 111. The particle size of the fine silicon powder in the slurry is usually not less than 0.5 μm, and by arranging the micropores on the inner cylinder and controlling the pore size of the micropores not to be more than 0.5 μm, chlorosilane gas separated from solid-phase slurry particles in the fluidization heating treatment process can enter the annular cavity 130 through the micropores under the entrainment of the fluidization hot air and is discharged through the gas outlet 111 arranged on the outer cylinder 110, and meanwhile, the fine silicon powder is retained in the inner cylinder 120, so that the effective separation of the chlorosilane and the silicon powder is realized. Further, the air permeability of the inner cylinder 120 may be made not less than 20m 3 /m 2 H, specifically, the method can be realized by controlling the pore diameter of the micropores on the surface of the inner cylinder body, the distribution density of the micropores, the flow rate and the flux of fluidized hot air and the like, so that chlorosilane gas can escape from the inner cylinder body more conveniently. According to the invention, the slurry particles are heated by adopting the fluidized drying device, so that the fine silicon powder and the residual chlorosilane in the slurry particles can be fully separated and respectively recovered, the obtained fine silicon powder has stable performance, no obvious chlorosilane smell, and is convenient to collect, can be sold as a raw material and is beneficial to storage and transportation; in addition, the supernatant obtained by standing and layering treatment and the mixed gas containing chlorosilane and separated by heating treatment are respectively recovered, so that the recovery rate of chlorosilane in the slurry can reach more than 99.5 percent.
According to the embodiment of the invention, in the heating treatment process, certain pressure can be kept in the inner cylinder body 120 and the annular cavity 130 by controlling the flow rate, the flux and the like of the fluidizing hot air, and meanwhile, the pressure in the annular cavity 130 is greater than the atmospheric pressure and not greater than (preferably smaller than) the pressure in the inner cylinder body 120, so that the air permeability of the inner cylinder body can be improved, chlorosilane gas can be facilitated to escape from the inner cylinder body into the annular cavity, and the chlorosilane gas is discharged out of the outer cylinder body under the positive pressure in the annular cavity; further, when the gas-solid mixture obtained by heating treatment is discharged from the inner cylinder, the supply of fluidization hot air can be stopped, because a certain positive pressure exists in the annular cavity 130, and the fluidization hot air is stopped when the inner cylinder discharges materials, the internal instant decompression of the inner cylinder can be realized, and then the silicon powder attached to the inner wall of the inner cylinder and the micropores can be backflushed by the pressure instant pulse in the annular cavity, and the backflushed silicon powder can be settled to the bottom of the inner cylinder under the action of gravity, so that the recovery yield of the silicon powder can be further improved, the higher air permeability of the inner cylinder in the continuous production process can be ensured, and the influence of micropore blockage on the separation efficiency and effect is avoided. According to some embodiments of the present invention, in the heating process, the pressure in the annular cavity 130 may be 0.1 to 0.5MPa, for example, 0.2MPa, 0.3MPa, or 0.4MPa, and the pressure in the annular cavity 130 is not higher than (preferably lower than) the pressure in the inner cylinder 120, and by controlling the pressure in the annular cavity within the above range, the present invention is not only more beneficial to maintaining the inner cylinder to have a higher air permeability and improving the separation effect, but also capable of promoting the discharge of the chlorosilane entering the annular cavity through the gas outlet to achieve the purpose of collection, and at the same time, capable of ensuring the recoil effect on the silicon powder attached to the inner wall and the micropores of the inner cylinder during the discharge, improving the yield of the silicon powder, controlling the cost, and reducing the equipment loss and energy consumption.
According to the embodiment of the invention, in the fluidizing and heating treatment process, nitrogen and/or inert gas can be adopted as the adopted fluidizing hot air, in the fluidizing process, solid slurry particles can be gradually crushed and dried (namely liquid-phase chlorosilane volatilizes, and the moisture content is reduced) to obtain fine silicon powder, and the fine silicon powder is easy to spontaneously combust when being contacted with air.
According to an embodiment of the present invention, as will be understood from fig. 2, the fluidized drying device 100 may include a fluidizing air duct 140 and a fluidizing nozzle 150, the fluidizing nozzle 150 may be disposed on the inner cylinder 120, the fluidizing air duct 140 may be disposed outside the outer cylinder 110 and connected to the fluidizing nozzle 150 through the outer cylinder 110, fluidizing hot air is supplied into the inner cylinder through the fluidizing air duct via the fluidizing nozzle, so that the solid-phase slurry particles are fluidized and dried, and then separated to obtain fine silicon powder, wherein the fluidizing degree, the drying efficiency, the separation effect, and the like of the solid-phase slurry particles in the fluidizing and heating process may be flexibly adjusted by adjusting the distribution position, the air injection direction, and the like of the fluidizing nozzle.
According to an embodiment of the present invention, as understood in conjunction with fig. 2, the inner cylinder 120 may include a feeding end 121 and a discharging end 122, the feeding end 121 and the discharging end 122 may be arranged up and down, and preferably, the inner cylinder 120 (length direction) may be vertically arranged, so that the feeding end 121 is located at the upper part of the inner cylinder 120, the discharging end 122 is located at the lower part of the inner cylinder 120, solid-phase slurry particles enter the inner cylinder 120 through the feeding end 121, and sufficient separation of chlorosilane and silicon powder is achieved through fluidized drying during falling, thereby facilitating both feeding and processing during heating processing, and sufficient fluidized drying of slurry particles. Further, the gas outlet 111 may be located on one side of the outer cylinder 110 away from the discharge end 122, that is, the gas outlet 111 may be located on the upper portion of the outer cylinder 110, thereby facilitating the discharge of the chlorosilane gas entering the annular cavity from bottom to top, and avoiding the influence on the separation effect of the silicon powder and the chlorosilane due to the back-mixing of the gas phase containing the chlorosilane in the annular cavity.
According to the specific embodiment of the present invention, when the inner cylinder 120 is vertically arranged, an included angle between an air injection direction of the fluidizing nozzle 150 and a vertically downward direction may be an obtuse angle, for example, 95 to 180 degrees, not less than 120 degrees, or not less than 150 degrees, and the like, so that when the solid-phase slurry particles sink in the inner cylinder due to their own gravity, the fluidizing hot air may exert an upward or obliquely upward blowing force on the slurry particles to slow down the descending speed thereof, thereby not only prolonging the heating and drying time of the solid-phase slurry particles, but also facilitating the sufficient volatilization and escape of chlorosilane, and further pulverizing the particles to obtain fine silica powder. Preferably, the air injection direction of the fluidizing nozzle is vertically upward or forms an angle of not less than 150 degrees with the vertically downward direction, so that the descending speed of the slurry particles is favorably slowed down, the fluidizing and drying time is prolonged, and the probability that the micro-powder is blown to the inner wall of the inner cylinder transversely is reduced.
According to an embodiment of the present invention, the fluidized drying device 100 may include a plurality of fluidizing nozzles 150, and at least some of the fluidizing nozzles 150 may be arranged at intervals along the length direction of the inner cylinder 120, for example, when the inner cylinder 120 is arranged vertically, by providing a plurality of fluidizing nozzles arranged at intervals along the length direction of the inner cylinder 120, the slurry particles may be repeatedly purged for many times during the falling process, and then a plurality of progressive fluidizing processes may be implemented, so as to be more beneficial to implementing effective and sufficient separation of silicon powder and chlorosilane. It should be noted that, the shape and the setting height of the fluidization nozzle in the present invention are not particularly limited, and those skilled in the art can flexibly select the shape and the setting height according to practical situations, for example, a nozzle with a conical upward opening can be adopted to reduce the occurrence of the situation that the fine powder blocks the nozzle, and for example, the setting height of the fluidization nozzle can be controlled not to be lower than the upper limit of the storage amount of the fluidized fine silicon powder in the inner cylinder, so as to avoid the conditions of nozzle blocking and erosion.
According to the embodiment of the present invention, the length of the outer cylinder 110 may be 4 to 18m, for example, 8m, 10m, 12m, or 16m, and the length of the inner cylinder 120 may be not less than the length of the outer cylinder 110, so that sufficient heat treatment time of the solid-phase slurry in the inner cylinder can be ensured, thereby further facilitating the sufficient fluidization separation process. On the basis, the fluidizing device may include at least 8 fluidizing nozzles 150, and the 8 fluidizing nozzles 150 are preferably arranged at intervals along the length direction of the inner cylinder 120, so that multiple progressive fluidizing processes can be further implemented on the solid-phase slurry particles, thereby further facilitating sufficient drying and dispersion of the solid-phase slurry particles, achieving effective and sufficient separation of silicon powder and chlorosilane, and improving yield of chlorosilane and silicon powder. Further, as can be understood from fig. 2, the inner cylinder 120 may include a plurality of sub-cylinders 123 connected end to end, and two adjacent sub-cylinders 123 are connected in a sealing manner, wherein a larger length-diameter ratio of the inner cylinder is more favorable for prolonging the heating time, and achieving sufficient fluidization and separation effects of slurry particles, but based on the length of the inner cylinder, if the inner diameter of the inner cylinder is smaller, the processing difficulty and the processing cost are higher. Preferably, a wear-resistant sub-cylinder may be used at a side close to the discharge end of the inner cylinder 120, whereby the service life of the inner cylinder may be further improved. In addition, it should be noted that the form of sealing and connecting the two adjacent sub-cylinders 123 is not particularly limited, and a person skilled in the art may flexibly select the sealing and connecting form according to actual situations, for example, the sealing and connecting form may be sealed and connected through an expansion joint, so that not only the sealing effect between the adjacent sub-cylinders may be ensured, but also the internal stress at the connection position of the adjacent sub-cylinders may be buffered.
According to the specific embodiment of the present invention, at least one fluidizing nozzle 150 may be disposed on each sub-cylinder 123, and at least one fluidizing nozzle may be disposed on one side of each sub-cylinder 123 close to the discharge end 122, so as to further prolong the fluidizing time of the solid-phase slurry particles in the sub-cylinders, and ensure the fluidizing effect, thereby facilitating volatilization of the chlorosilane and timely discharging the chlorosilane from the sub-cylinders under the driving of the fluidizing hot air, and improving the drying effect and the separation efficiency.
According to the specific embodiment of the present invention, the inner cylinder 120 may include 8 to 12 sub-cylinders 123, and the length of a single sub-cylinder 123 may be 0.6 to 1.5m, so that it may be further ensured that the solid-phase slurry particles have a sufficiently long fluidized drying path, the separation effect and yield of the fine silicon powder and the chlorosilane are improved, and the processing difficulty and processing cost of the inner cylinder may be reduced.
According to an embodiment of the present invention, the aspect ratio of the inner cylinder 110 may be (100 to 150): 1, for example, may be 110: 1. 120: 1. 130, 130:1 or 140:1, etc.; the aspect ratio of the outer cylinder 110 may be (100 to 150): 5, for example, may be 110: 5. 120: 5. 130:5 or 140:5, and the like. Therefore, the solid-phase slurry particles can be ensured to have sufficient heating time in the heating treatment process, can be sufficiently fluidized and dried, and can also enable chlorosilane gas to enter the annular cavity to be separated as much as possible, so that the separation effect of the fine silicon powder and the chlorosilane can be improved, and the yield of the fine silicon powder and the chlorosilane can be improved.
According to the embodiment of the present invention, the temperature of the heat treatment may be 200 to 250 ℃, for example, 210 ℃, 220 ℃, 230 ℃, or 240 ℃, and the time of the heat treatment may be not less than 100 seconds. The inventor finds that if the heating temperature is too low, the volatilization rate of chlorosilane is reduced, the chlorosilane is not beneficial to the full separation of fine silicon powder and the chlorosilane, metal chloride possibly existing in solid-phase slurry particles can be crystallized in the inner cylinder, micropores on the cylinder wall of the inner cylinder are blocked, the chlorosilane gas is not beneficial to escape and recovery, and if the heating temperature is too high, the risk of damage of a fluidization device is increased, and the service life of the device is shortened; if the heating treatment time is too short, the fluidization heating time of the solid-phase slurry particles in the fluidization drying device is insufficient, so that the full separation of the fine silicon powder and the chlorosilane is difficult to realize, and the further crushing of the slurry particles is not facilitated, so that the particle size distribution of the fine micropowder obtained by recovery is influenced. Further, the time of the heating treatment can be controlled by controlling the flow rate of the fluidizing hot air, and when the included angle between the air injection direction of the fluidizing hot air fluidizing nozzle and the vertical downward direction is an obtuse angle, the larger the flow rate of the fluidizing hot air, the slower the descending speed of the solid-phase slag slurry, for example, according to some specific examples of the present invention, the flow rate of the fluidizing hot air can be made to be 0.02 to 0.05m/s, for example, 0.25m/s, 0.3m/s, 0.4m/s, or 0.45m/s, and the inventors found that if the flow rate of the fluidizing hot air is too small, the fluidizing time of the solid-phase slurry particles is too short, the drying effect is not good, and if the flow rate of the fluidizing hot air is too large, for example, the fluidizing hot air is more than the fine air entrainment speed of the fine silicon powder, the fine silicon powder is likely to cause the phenomenon of elutriation, and the yield is reduced. According to the invention, by controlling the temperature and time of the heating treatment and the flow rate of the fluidizing hot air within the ranges, the separation effect of the fine silicon powder and the chlorosilane can be further improved and the yield of the fine silicon powder and the chlorosilane can be improved on the premise of ensuring the stable use of the device.
According to an embodiment of the present invention, as understood in conjunction with fig. 2, the fluidized drying device 100 may further include a heat generating member 160, and the fluidized air is heated or the thermal field during the heating process is maintained stable by the heat generating member 160. For example, the heat generating member 160 may be disposed in the annular cavity 130 (as shown in fig. 2), and the heat generating member disposed in the annular cavity can further maintain the high temperature environment inside the inner barrel and the annular cavity, thereby facilitating volatilization and discharge of chlorosilane. Further, the heat generating member 160 may be disposed along the length direction of the annular cavity, so as to be more favorable for maintaining the thermal field environment and temperature stability of the slurry particles in the whole fluidization heating process, and preferably, the heat generating member 160 may also be disposed along the circumferential direction and the length direction of the annular cavity 130, so as to be more favorable for improving the thermal stability in the whole fluidization heating process, so as to stably perform the fluidization heating process. In addition, the heat generating member 160 may be disposed on the inner wall of the outer cylinder 110 or disposed adjacent to the inner wall of the outer cylinder 110 in the annular cavity 130, and the fluidizing air duct 140 may be disposed outside the outer cylinder 110, for example, may be wound around the outer surface of the outer cylinder 110 and extend along the length direction of the outer cylinder, so that not only the stability of the thermal field during the heating process is maintained, but also the fluidizing air in the fluidizing air duct is heated by the heat generating member to obtain the fluidizing hot air. It should be noted that the type of the heating element 160 used in the present invention is not particularly limited, and those skilled in the art can flexibly select the heating element 160 according to actual needs, for example, the heating element 160 may be a heating cell or a thermocouple, or may be a radiation heating pipe with a circulating high temperature liquid phase or a circulating gas phase; for another example, the heat generating member 160 may be an electric heating element, and in this case, the fluidized drying device 100 may further include a power supply device electrically connected to the heat generating member, and in this case, the power supply device may be disposed outside the outer cylinder.
According to the embodiment of the present invention, by subjecting the slurry particles to the fluidized heating treatment by the fluidized drying device 100, the slurry particles can be further dried and pulverized to obtain dried fine silicon powder having a particle size of 0.5 to 30 μm, and it should be noted that the particle size of the obtained dried silicon powder can be actually understood as the primary particle size of the silicon powder mixed in the slurry, and the fluidized drying heating treatment can achieve sufficient drying and dispersion of the silicon powder, and effective separation and recovery of the silicon powder having a particle size of not less than 0.5 μm. After the heating treatment is finished, the material discharged from the discharge end of the inner cylinder body is actually a gas-solid mixture comprising the fine silicon powder and fluidized air, and at the moment, the gas-solid mixture can be further subjected to gas-solid separation to obtain the dry silicon powder. The type of the apparatus used for the gas-solid separation is not particularly limited, and those skilled in the art can flexibly select the apparatus according to actual needs, for example, a bag-type dust collector can be used.
According to the embodiment of the invention, the method for separating silicon powder from the chlorosilane-containing slurry can be continuously carried out on the whole process flow, the feeding and discharging of the inner cylinder 120 can be carried out intermittently in the fluidized heating treatment, namely, the fluidized heating treatment can be carried out on the slurry particles by utilizing the gaps for crushing the solid-phase slurry, the slurry is discharged after the fluidized heating treatment is finished, the feeding end is opened after the discharging end is closed, and the next batch of slurry particles after the crushing treatment is supplied into the inner cylinder for continuous fluidized heating treatment, so that the treatment capacity of the slurry can be improved, and the separation effect and efficiency of the silicon powder and the chlorosilane can be ensured.
In summary, the method for separating silicon powder from chlorosilane-containing slurry according to the above embodiment of the present invention has at least the following beneficial effects: 1) Most of chlorosilane can be separated and recovered from the slurry through standing and layering; the slurry particles are heated by combining the fluidized drying device, so that the effective separation of the micro powder and the residual chlorosilane in the slag slurry particles can be realized, and the respective recovery of the dried silicon powder and the chlorosilane can be realized; 2) The recovery rate of chlorosilane in the slurry can reach more than 99.5 percent, the silicon powder obtained by separation has higher purity and no obvious chlorosilane smell, and the problem of environmental pollution caused by waste water and waste gas generated by washing because of higher content of chlorosilane impurities in the silicon powder is solved; 3) The silicon powder obtained by separation has high drying degree, is convenient to collect, has stable performance, is favorable for storage and transportation, and can be sold as a raw material; 4) The whole process flow can be carried out continuously on the whole, and compared with the existing intermittent production flow, the treatment capacity, the separation efficiency and the effect on the slag slurry are higher, and the investment and the operation energy consumption are lower.
In yet another aspect, the invention provides a separation system for carrying out the above-described method for separating silicon powder from a chlorosilane-containing slurry. According to an embodiment of the invention, as understood in connection with fig. 3, the system comprises: a standing device 200, a crushing device 300, the fluidized drying device 100 and a gas-solid separation device 400. Compared with the prior art, the system has the advantages of high separation efficiency, good separation effect on the slurry, capability of improving the yield of chlorosilane and dry silicon powder, stable performance of the dry silicon powder obtained by separation, capability of serving as a raw material for sale and the like, low investment and operation energy consumption, and capability of realizing continuous production. The separation system is described in detail below with reference to fig. 2 to 3.
Standing device 200
According to an embodiment of the present invention, as understood in conjunction with fig. 3, the standing device 200 includes a slurry inlet 210, a supernatant outlet 220 and a solid-phase slurry outlet 230, and is adapted to perform a standing layering process on the slurry containing chlorosilane, after the slurry containing chlorosilane enters from the slurry inlet 210, the slurry is allowed to stand and layer in the standing device to obtain a solid-phase slurry and a supernatant, the supernatant is discharged through the supernatant outlet 220, and the solid-phase slurry flows out through the solid-phase slurry outlet 230.
According to an embodiment of the present invention, the standing device 200 may further include a pressing member (not shown) adapted to apply a certain static pressure to the solid phase slurry so as to be supplied into the subsequent crushing device 300. The static pressure provided by the pressing part can be adjusted, and the static pressure applied to the solid-phase slurry can be flexibly adjusted by a person skilled in the art according to the actual situation in the actual operation process, for example, the static pressure of 0.1-0.5 MPa can be applied to the solid-phase slurry, so that the solid-phase slurry can be smoothly discharged, and the energy consumption can be saved. In addition, the lower part of the standing device 200 can be provided with a conical area (as shown in fig. 3), thereby being more beneficial to controlling the outflow speed of the solid-phase slurry. In addition, a liquid level visible area (not marked in the figure) may be further disposed at the lower portion of the standing device 200, a layering condition in the standing device may be observed through the liquid level visible area, when a liquid level in the standing device is higher (i.e., there are more solid-phase slurries), an opening time of the solid-phase slurry outlet may be appropriately prolonged, it should be noted that a disposition form of the liquid level visible area is not particularly limited, and a person skilled in the art may flexibly select the liquid level visible area according to an actual situation, for example, a liquid level viewing mirror may be employed, and for example, the liquid level viewing mirror may be disposed in the above tapered area. Furthermore, in the standing device 200, a material passing sensor (not shown) may be further disposed at the solid-phase slurry outlet 230, and the material passing sensor may be configured to automatically close the solid-phase slurry outlet 230 when there is a liquid phase, so that the supernatant can be prevented from entering the fluidization device, and the difficulty of subsequent treatment operation can be reduced.
According to an embodiment of the present invention, as will be understood in connection with fig. 3, the crushing device 300 comprises a solid phase slurry inlet 310 and a slurry particles outlet 320, the solid phase slurry inlet 310 being connected to the solid phase slurry outlet 230 and being adapted to perform a crushing process on the solid phase slurry resulting in slurry particles. The specific type of the crushing device 300 is not particularly limited, and those skilled in the art can flexibly select the crushing device according to actual needs, for example, the crushing device 300 may include a crushing assembly, the crushing assembly may include a propeller blade, and the like, and the crushing of the solid-phase slurry is achieved by the rotation of the propeller blade; for another example, the rotating speed of the rotating blades may be 1 to 10r/min, and the slurry particles obtained by the crushing treatment may be discharged through the slurry particle outlet 320 for a subsequent treatment process.
According to an embodiment of the invention, as understood in connection with fig. 3, the separation system may further comprise: a feeding device 600, the feeding device 600 may be provided between the crushing device 300 and the inner cylinder 120 and adapted to supply slurry particles into the inner cylinder 120. According to the specific example of the present invention, in addition to the function of storing and storing the solid-phase slurry, the feeding device 600 may further have a crushing assembly inside, the crushing assembly is suitable for performing re-crushing on the slurry particles obtained after being crushed by the crushing device 300, for example, the particle size of the slurry particles after being crushed again may be controlled below 1mm, so as to further improve the efficiency and effect of the subsequent fluidization heating treatment. Wherein, the specific type of the crushing assembly in the feeding device has no special requirement, and the skilled person can flexibly select the crushing assembly according to the actual situation, for example, a propeller blade and the like can be adopted.
Fluidized drying apparatus 100
According to the embodiment of the present invention, it should be noted that the fluidized drying device 100 has all the technical features and effects of the drying and fluidizing device described in the above method for separating silicon powder from chlorosilane-containing slurry, and details are not repeated here. In addition, as understood in fig. 3, the feeding end 121 of the inner cylinder 120 of the fluidized drying device 100 is connected to the slurry particle outlet 320, and the gas outlet 111 on the outer cylinder 110 of the fluidized drying device 100 is connected to the chlorosilane recovery tank 500, and is adapted to heat the slurry particles so as to obtain dry silicon powder and chlorosilane gas, wherein the specific process of the fluidized heating process has been described in detail above and is not repeated here. The chlorosilane recovery tank 500 may further include a second tail gas outlet 510 and a chlorosilane condensation outlet 520, and after the mixed gas (including fluidized air and chlorosilane gas) discharged from the gas outlet 111 of the outer cylinder 110 is collected in the chlorosilane recovery tank 500, the separation of the fluidized air and the chlorosilane may be achieved through condensation, and after the mixed gas is condensed, the chlorosilane is liquefied and is discharged and recovered through the condensation outlet 520.
According to some specific examples of the present invention, the feeding end 121 of the inner cylinder 120 may be provided with a feeding valve (not shown in the drawings), and the discharging end 122 of the inner cylinder 120 may be provided with a discharging valve 124, wherein the discharging valve 124 may be a quick-opening and closing discharging valve. The feed valve and the discharge valve 124 are not opened at the same time, and in the fluidized heating treatment process, the discharge valve 124 is closed, so that the pressure of the inner cylinder is kept higher than that of the annular cavity, the chlorosilane gas is discharged from the micropores, and the drying effect is prevented from being influenced by the back mixing of the chlorosilane gas phase; after the fluidization heat treatment is finished, the discharge valve 124 is quickly opened, the discharge valve is opened, the feed valve and the gas outlet are closed, the supply of fluidization hot air into the inner cylinder 120 is stopped, the pressure loss inside the inner cylinder is realized while the gas-solid mixture is discharged, the pressure in the annular cavity is instantaneously pulsed in, the powder attached to the inner wall of the inner cylinder is backflushed and is settled to the bottom of the inner cylinder, and therefore the micro-pores can be kept in good gas permeability at each fluidization heat treatment stage. Wherein, this feed valve and bleeder valve can be respectively independently intermittent type nature switching, and bleeder valve switch interval time can be adjusted according to actual powder volume, prevents that interior barrel is gaseous a large amount of from the bleeder valve outflow.
Gas-solid separation device 400
According to an embodiment of the present invention, as will be understood in conjunction with fig. 3, the gas-solid separation device 400 may include a gas-solid mixture inlet, a first tail gas outlet 410 and a dried silicon powder outlet, wherein the gas-solid mixture inlet is connected to the discharge end 122 of the inner cylinder 120 and is adapted to perform a gas-solid separation treatment on the gas-solid mixture discharged from the inner cylinder 120 so as to obtain dried silicon powder.
According to the embodiment of the present invention, the gas-solid separation device 400 can be connected to the discharge end 122 of the inner cylinder 120 through the hydraulic type quick connector 420, so that the gas-solid separation device can be connected to the discharge end 122 of the inner cylinder in a quick and airtight manner. In addition, a plurality of layers of filter cloth bags (not shown in the figure) can be arranged in the gas-solid separation device 400, the gas-solid separation is carried out on the gas-solid mixture discharged from the inner cylinder body through the plurality of layers of filter cloth bags, a small amount of gas remained in the gas-solid mixture can be discharged to obtain dry silicon powder, wherein the discharged small amount of gas can be preferably discharged after being further condensed by a condensing device, and thus trace chlorosilane possibly existing in tail gas can be further removed; further, the gas-solid separation device 400 may further include a silicon material receiving device 430, the outlet of the dry silicon powder may be disposed at the bottom of the multi-layer filtering cloth bag and enter the silicon material receiving device 430 through the tapered back-mixing baffle 440, the silicon powder falling down may be effectively prevented from being directly blown by the gas discharged from the next fluidized heating stage to generate dust, and meanwhile, a repose angle may be prevented from being formed in the silicon material receiving device, thereby reducing the storage amount.
According to the implementation of the present invention, as will be understood in conjunction with fig. 3, the standing device 200, the crushing device 300, the fluidized drying device 100 and the gas-solid separation device 400 can be arranged up and down, so that the slag slurry can be layered through the standing device 200 under the action of gravity, the supernatant liquid is discharged through the supernatant liquid outlet 220, and the solid slurry in the lower layer passes through the crushing device 300, the fluidized drying device 100 and the gas-solid separation device 400 in sequence to obtain the dried silicon powder.
In a further aspect of the invention, the invention proposes the use of a separation system as described above for separating silicon powder from a chlorosilane-containing slurry and for carrying out the above-described method for separating silicon powder from a chlorosilane-containing slurry for recovering fine silicon powder. The application has all the technical characteristics and effects of the method for separating the silicon powder from the chlorosilane-containing slurry and the separation system, and the details are not repeated here. In general, the recovery of the fine silicon powder is more favorably realized, and the fine silicon powder with higher purity and stable performance is obtained.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A method for separating silicon powder from chlorosilane-containing slurry is characterized by comprising the following steps:
(1) Carrying out standing layering treatment on the slag slurry containing chlorosilane to obtain solid-phase slurry and supernatant;
(2) Crushing the solid-phase slurry to obtain slurry particles;
(3) Heating the slurry particles by a fluidized drying device to obtain dry silicon powder and chlorosilane gas,
in the step (3), the fluidized drying device comprises an outer cylinder and an inner cylinder penetrating through the outer cylinder, a closed annular cavity is formed between the outer cylinder and the inner cylinder, micropores are arranged on the cylinder wall of the inner cylinder in the annular cavity, the pore diameter of the micropores is not more than 0.5 μm, and a gas outlet is arranged on the outer cylinder; the heating treatment comprises: and supplying the slurry particles into the inner cylinder, and introducing fluidizing hot air into the inner cylinder to volatilize chlorosilane and discharge the chlorosilane through the gas outlet.
2. The method of claim 1, wherein at least one of the following conditions is satisfied:
in the step (1), the solid content in the slurry is 1-8 wt%;
in the step (1), the standing layering treatment time is 0.5-3 h;
in the step (1), the moisture content in the solid-phase slurry is 10-40 wt%;
in the step (2), the particle size of the slurry particles is not more than 1mm.
3. The method according to claim 1 or 2, wherein step (3) satisfies at least one of the following conditions:
the fluidizing hot air adopts nitrogen and/or inert gas;
the fluidized drying device further includes: the fluidization air pipe is arranged outside the outer cylinder body and penetrates through the outer cylinder body to be connected with the fluidization nozzle;
the fluidized drying device further includes: the heating piece is arranged in the annular cavity;
the feeding end and the discharging end of the inner cylinder body are arranged up and down;
the temperature of the heating treatment is 200-250 ℃, and the time of the heating treatment is not less than 100s;
the flow velocity of the fluidized hot air is 0.02-0.05 m/s;
the pressure in the annular cavity is 0.1-0.5 MPa, and the pressure in the annular cavity is not higher than the pressure in the inner cylinder;
the length of the outer cylinder body is 4-18 m, and the length of the inner cylinder body is not less than that of the outer cylinder body;
the length-diameter ratio of the inner cylinder body is (100-150): 1, the length-diameter ratio of the outer cylinder body is (100-150): 5;
carrying out gas-solid separation on the gas-solid mixture obtained by heating treatment to obtain the dry silicon powder;
stopping supplying the fluidizing hot air when the gas-solid mixture obtained by heating treatment is discharged from the inner cylinder;
the particle size of the dry silicon powder is 0.5-30 μm.
4. The method of claim 3, wherein step (3) satisfies at least one of the following conditions:
the fluidization drying device comprises a plurality of fluidization nozzles, and at least part of the fluidization nozzles are arranged at intervals along the length direction of the inner cylinder;
the heating part is arranged on the inner wall of the outer cylinder or is arranged close to the inner wall of the outer cylinder, and the fluidization air pipe is wound on the outer cylinder and extends along the length direction of the outer cylinder;
the inner cylinder body is vertically arranged, and the included angle between the air injection direction of the fluidization nozzle and the vertical downward direction is an obtuse angle;
the fluidized drying device comprises at least 8 of the fluidizing nozzles;
the inner cylinder body comprises a plurality of sub-cylinder bodies which are communicated end to end, and two adjacent sub-cylinder bodies are connected in a sealing way;
the heating pieces are arranged along the length direction of the annular cavity;
the air permeability of the inner cylinder body is not less than 20m 3 /m 2 ·h。
5. The method of claim 4, wherein the sub-cartridge satisfies at least one of the following conditions:
the number of the sub-cylinders is 8-12, and the length of each sub-cylinder is 0.6-1.5 m;
two adjacent sub-cylinders are connected in a sealing way through expansion joints;
each sub-cylinder is provided with at least one fluidization nozzle, and at least one fluidization nozzle on each sub-cylinder is arranged close to the discharge end.
6. A separation system for carrying out the method of any one of claims 1 to 5, comprising:
the device comprises a standing device, a liquid level control device and a control device, wherein the standing device comprises a slag slurry inlet, a supernatant outlet and a solid-phase slurry outlet;
the crushing device comprises a solid-phase slurry inlet and a slurry particle outlet, and the solid-phase slurry inlet is connected with the solid-phase slurry outlet;
the fluidized drying device of any one of claims 1 to 5, wherein the feed end of the inner cylinder of the fluidized drying device is connected with the slurry particle outlet, and the gas outlet on the outer cylinder of the fluidized drying device is connected with a chlorosilane recovery tank;
the gas-solid separation device comprises a gas-solid mixture inlet, a first tail gas outlet and a dried silicon powder outlet, and the gas-solid mixture inlet is connected with the discharge end of the inner barrel.
7. The separation system of claim 6, wherein at least one of the following conditions is satisfied:
the standing device, the crushing device, the fluidized drying device and the gas-solid separation device are arranged up and down;
the separation system further comprises: the feeding device is arranged between the crushing device and the inner cylinder body and is suitable for supplying slurry particles into the inner cylinder body;
a feed valve is arranged at the feed end of the inner cylinder, a discharge valve is arranged at the discharge end of the inner cylinder, and the feed valve and the discharge valve are not opened at the same time;
a liquid level visible area is arranged at the lower part of the standing device;
in the standing device, a solid-phase slurry outlet is provided with a material passing sensor, and the material passing sensor is arranged to automatically close the solid-phase slurry outlet when a liquid phase passes through the material passing sensor;
the chlorosilane recovery tank further comprises a second tail gas outlet and a chlorosilane condensation outlet.
8. The separation system of claim 7, wherein at least one of the following conditions is satisfied:
the feed valve and the discharge valve of the inner cylinder are respectively and independently opened and closed intermittently;
a crushing assembly is also arranged in the feeding device;
the lower part of the standing device is provided with a conical area, and the liquid level visible area is arranged in the conical area.
9. The separation system according to claim 6 or 8, wherein the gas-solid separation device is connected with the discharge end of the inner cylinder body through a hydraulic quick connector; and/or the presence of a gas in the gas,
the gas-solid separation device also comprises a silicon material receiving device, a multilayer filter cloth bag is arranged in the gas-solid separation device, and the dry silicon powder outlet is arranged at the bottom of the multilayer filter cloth bag and is connected with the silicon material receiving device through a conical back mixing baffle.
10. Use of the process of any one of claims 1 to 5 and the separation system of any one of claims 6 to 9 for recovering fine silicon powder.
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| CN202211370069.4A CN115557507B (en) | 2022-11-03 | 2022-11-03 | Method, system and use for separating silicon powder from slag slurry containing chlorosilane |
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| CN202211370069.4A CN115557507B (en) | 2022-11-03 | 2022-11-03 | Method, system and use for separating silicon powder from slag slurry containing chlorosilane |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9169589B1 (en) * | 2013-10-10 | 2015-10-27 | ShaQuavis D. Sales | Space saving washing and drying system |
| CN106927469A (en) * | 2017-04-12 | 2017-07-07 | 中国恩菲工程技术有限公司 | The recovery system of chlorosilane waste liquid |
| JP2018153755A (en) * | 2017-03-17 | 2018-10-04 | 日本コークス工業株式会社 | Crushing system |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9169589B1 (en) * | 2013-10-10 | 2015-10-27 | ShaQuavis D. Sales | Space saving washing and drying system |
| JP2018153755A (en) * | 2017-03-17 | 2018-10-04 | 日本コークス工業株式会社 | Crushing system |
| CN106927469A (en) * | 2017-04-12 | 2017-07-07 | 中国恩菲工程技术有限公司 | The recovery system of chlorosilane waste liquid |
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