Fluidized bed system and method for separating silicon powder from granular polysilicon

Abstract

Fluidized bed systems for separating powder from granular material, such as separating silicon powder from granular polysilicon, can include a main vessel, a cone at a lower end of the main vessel, and an injector assembly coupled to the cone. The injector assembly includes an injector conduit configured to direct fluidization gas into the main vessel through the cone and withdraw granular material from the main vessel. The main vessel has a top cover including an outlet through which fluidization gas and entrained powder can be withdrawn.

Description

4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025FLUIDIZED BED SYSTEM AND METHOD FOR SEPARATING SILICON POWDER FROM GRANULAR POLYSILICONCROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims the benefit of U.S. Provisional Application No. 63 / 690,382, filed on September 4, 2024, which is incorporated herein by reference in its entirety.FIELD

[0002] The present application pertains to fluidized bed systems and methods for separating silicon powder from granular polysilicon.BACKGROUND

[0003] Ultra-high purity polycrystalline silicon (also referred to as “polysilicon”) for the photovoltaic and semiconductor industries can be produced in a variety of ways, including by chemical vapor deposition in the Siemens process and / or by pyrolytic decomposition of silicon- bearing gas in a fluidized bed reactor. Fluidized bed reactors can be controlled to produce polysilicon granules having a selected size distribution. However, the pyrolytic decomposition process results in the formation of some relatively small (e.g., nano- to micron-sized) particles, regardless of the particle size sought for the majority of the mass, which can remain in the bed as free powder, or which can attach to the larger silicon granules. Such powder or “fines” on the outer surface of the larger silicon beads can be undesirable because they can interfere with crystal growth when producing single-crystal ingots in the Czochralski process. Accordingly, a need exists for improved systems and methods for removing silicon powder from granular polysilicon produced in fluidized bed reactors.SUMMARY

[0004] Certain examples of the disclosure pertain to fluidized bed systems and methods for separating powder from granular material, such as separating silicon powder from granular polysilicon. In a representative example, a system for separating powder from granular material comprises a main vessel; a cone at a lower end of the main vessel; an injector assembly coupled to the cone, the injector assembly including an injector conduit configured to direct fluidization gas into the main vessel through the cone and withdraw granular material from the main vessel; wherein the main vessel comprises a top cover including an outlet through which fluidization gas and entrained powder can be withdrawn.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0005] In any or all of the examples disclosed herein, the injector conduit comprises a flange defining a flange surface, the cone of the main vessel is coupled to the flange surface, and an inner portion of the flange surface is exposed and oriented upwardly to contact polysilicon granules circulating in the main vessel.

[0006] In any or all of the examples disclosed herein, the injector assembly further comprises a main injector body defining a central bore and an inner chamber surrounding the central bore, and the injector conduit is received in the central bore of the main injector body.

[0007] In any or all of the examples disclosed herein, the chamber of the main injector body is at least partially defined by an inner wall, an outer wall, an upper wall, and a lower wall, and the chamber is in fluid communication with the central bore through an annular gap defined between the lower wall and the inner wall surrounding the central bore.

[0008] In any or all of the examples disclosed herein, the injector conduit is a first injector conduit; and the injector assembly further comprises a second injector conduit coupled to the first injector conduit and in fluid communication with the first injector conduit, the first and second injector conduits being coupled together by a flexible coupling to facilitate mating between the cone and the flange surface of the first injector conduit.

[0009] In any or all of the examples disclosed herein, the main injector body comprises a counterbore defined concentrically with the central bore; end portions of the first and second injector conduits are received in the counterbore of the main injector body; and an interface between the first injector conduit and the second injector conduit is sealed with one or a plurality of seals to form the flexible coupling.

[0010] In any or all of the examples disclosed herein, the top cover of the main vessel further comprises an inlet configured to supply granular material to the main vessel.

[0011] In any or all of the examples disclosed herein, the system is configured as a spouted bed powder separation system.

[0012] In any or all of the examples disclosed herein, the granular material is polysilicon granules, and surfaces that are configured to be in contact with the polysilicon granules comprise silicon, silicon carbide, quartz, polyethylene, high-purity metal alloys, or any combination thereof.

[0013] In another representative example, a method comprises introducing granular material into a main vessel of a spouted bed powder separation system; flowing fluidization gas through the granular material to at least partially fluidize the granular material and circulate the granular material in the main vessel; withdrawing fluidization gas from the main vessel, the withdrawn4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 fluidization gas containing entrained powder; and withdrawing granular material from the main vessel, wherein the withdrawn granular material comprise a reduced percentage by weight of powder than the introduced granular material.

[0014] In any or all of the examples disclosed herein, the fluidization gas contains a surface conditioning agent.

[0015] In any or all of the examples disclosed herein, the surface conditioning agent comprises an oxidizer, acid, or evaporative coating.

[0016] In any or all of the examples disclosed herein, the fluidization gas is humidified with water.

[0017] In any or all of the examples disclosed herein, the method further comprises purging the conditioning gas or humidified fluidization gas with dry inert gas.

[0018] In any or all of the examples disclosed herein, the granular material is pre-treated by being pre-oxidized, pre-moisturized, pre-coated, or pre-acid washed.

[0019] In any or all of the examples disclosed herein, particles of the entrained powder have a diameter of 40 nm to 250 pm.

[0020] In any or all of the examples disclosed herein, flowing the fluidization gas through the granular material further comprises producing a fountain of granules.

[0021] In any or all of the examples disclosed herein, the method further comprises controlling the flow of fluidization gas to generate a stable fountain of granules, or controlling the flow of fluidization gas such that the fountain forms, collapses, and reforms in an unstable manner.

[0022] In any or all of the examples disclosed herein, the fluidization gas flows into the main vessel through an injector conduit of an injector assembly, and the method further comprises withdrawing granular material from the main vessel through the injector conduit of the injector assembly.

[0023] In any or all of the examples disclosed herein, the granular material comprises granular polysilicon.

[0024] In another representative example, a method comprises operating any of the systems described herein to produce granular material free from dust and fines.

[0025] In another representative example, a method comprises operating any of the systems described herein to produce dust and fines free from granular material.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0026] In another representative example, a method comprises operating any of the systems described herein to produce a combination of separated smaller particles, dust and fines, and larger particles.

[0027] In another representative example, a method comprises introducing polysilicon granules into a main vessel of a spouted bed powder separation system; flowing fluidization gas through the polysilicon granules to at least partially fluidize the polysilicon granules and circulate the polysilicon granules in the main vessel; withdrawing fluidization gas from the main vessel, the withdrawn fluidization gas containing entrained polysilicon powder; and withdrawing polysilicon granules from the main vessel, wherein the withdrawn polysilicon granules comprise a reduced percentage by weight of poly silicon powder than the introduced polysilicon granules.

[0028] The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 schematically illustrates a representative example of a spouted bed powder separation system.

[0030] FIG. 2 is a cross-sectional view illustrating the injector assembly and the lower end of the cone of the powder separation system of FIG. 1.

[0031] FIG. 3 illustrates a top cover plate of the main vessel of the powder separation system of FIG. 1.

[0032] FIG. 4 is a schematic block diagram illustrating a representative example of a method of removing powder from granular material.

[0033] FIG. 5 is a cross-sectional view illustrating another example of an injector assembly that can be used in combination with any of the powder separation systems described herein.DETAILED DESCRIPTION

[0034] Explanation of Terms

[0035] The following explanations of terms are provided to assist in understanding the present disclosure. For purposes of this description, certain aspects, advantages, and novel features of examples of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 toward all novel and nonob vious features and aspects of the various disclosed examples, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed examples require that any one or more specific advantages be present or problems be solved.

[0036] Although the operations of some of the disclosed examples are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods. Additionally, the description sometimes uses terms like “provide” or “achieve” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art.

[0037] As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the term “coupled” generally means physically, mechanically, chemically, magnetically, and / or electrically coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

[0038] As used herein, “e.g.” means “for example,” and “i.e.” means “that is.”

[0039] In some examples, values, procedures, or apparatus may be referred to as “lowest,” “best,” “minimum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many alternatives can be made, and such selections need not be better or otherwise preferable to other selections.

[0040] In the description, certain terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But, these terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, an “upper” surface can become a “lower” surface simply by turning the object over. Nevertheless, it is still the same object.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0041] Unless otherwise indicated, all numbers expressing dimensions, quantities of components, forces, moments, molecular weights, percentages, temperatures, times, and so forth, as used in the specification or claims are to be understood as being modified by the term “about.” Accordingly, unless otherwise indicated, implicitly or explicitly, the numerical parameters set forth are approximations that can depend on the desired properties sought and / or limits of detection under test conditions / methods familiar to those of ordinary skill in the art. When directly and explicitly distinguishing examples from discussed prior art, the examples numbers are not approximates unless the word “about” is recited.

[0042] Although there may be alternatives for various components, parameters, ratios, dimensions, operating conditions, etc., set forth herein, that does not mean that those alternatives are necessarily equivalent and / or perform equally well. Nor does it mean that the alternatives are listed in a preferred order unless stated otherwise.

[0043] As used herein, values and / or relationships modified by the term “substantially” mean ± 10% of the stated value and / or relationship. “Substantially perpendicular” means an angle of 80° to 100° relative to a reference. “Substantially parallel” means an angle of ± 10° relative to a reference.

[0044] Overview of the Disclosed Technology

[0045] Ultra-high purity polycrystalline silicon (also referred to as “polysilicon”) for the photovoltaic and semiconductor industries can be produced in a variety of ways, including by chemical vapor deposition in the Siemens process and / or by pyrolytic decomposition of silicon- bearing gas in a fluidized bed reactor. The Siemens process results in long polysilicon rods that are then broken into small chunks or granules for further processing. Fluidized bed reactors can be controlled to produce polysilicon granules having a selected size distribution.

[0046] In a fluidized bed reactor, granular polysilicon is produced by silane pyrolysis. The conversion of silane to silicon occurs via homogeneous and heterogeneous reactions. The homogeneous reaction produces nano- to micron-sized silicon powder or dust, which can remain in the bed as free powder, attach to silicon granules, or elutriate and leave the FBR with effluent hydrogen gas. The heterogeneous reaction forms a solid silicon deposit on available surfaces, which primarily are surfaces of granular and seed material (silicon particles onto which additional silicon is deposited, seed-particles typically having a diameter in the largest dimension of 0.1 -0.8 mm, such as 0.2-0.7 mm or 0.2-0.4 mm). Granular polysilicon can have a largest dimension of 1.5 mm to 5 mm upon withdrawal from the FBR, with many particles growing to a size of 1.5 mm to 2 mm. This process encapsulates some of the powder and results in growth rings on the granules4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 with some variation in density. On a microscopic scale, the surface of granular silicon has porosity that can trap dust. The surface can also have microscopic attached features that can be broken away or otherwise removed when the granules are handled through a process known as attrition.

[0047] In the context of this disclosure, the terms “powder,” “dust,” and “fines” are used interchangeably, and refer to, for example, polycrystalline silicon particles having an average diameter less than 250 pm. As used herein, “average diameter” means the mathematical average diameter of a plurality of powder or dust particles. When poly silicon is produced in a fluidized bed reactor, the average diameter of the powder particles may be considerably smaller than 250 pm, such as an average diameter less than 50 pm. Individual powder particles may have a diameter ranging from 40 nm to 250 pm, and more typically have a diameter ranging from 40 nm to 50 pm, or from 40 nm to 10 pm. Individual powder particles may also be smaller, such as down to the atomic level. Particle diameter can be determined by several methods, including laser diffraction (particles of submicron to millimeter diameter), dynamic image analysis (particles of 30 pm to 30 nm diameter), and / or mechanical screening (particles of 30 pm to more than 30 mm diameter).

[0048] The terms “granular polysilicon” and “polysilicon beads” refer to polysilicon particles having an average diameter of 0.25 to 20 mm, such as an average diameter of 0.25-10, 0.25-5, or 0.25 to 3.5 mm. As used herein, “average diameter” means the mathematical average diameter of a plurality of granules. Individual granules may have a diameter ranging from 0.1-30 mm.

[0049] As produced, e.g., by a fluid bed reactor, granular polysilicon typically contains from 0.25% to 3% powder or dust by weight, and up to 10% in some instances; this quantity includes both free and surface-attached dust. The quantity of powder present on the external surface of granular polysilicon beads is undesirable for users who melt and recrystallize the silicon with the potential to cause loss of structure for single-crystal growth processes. The powder also creates housekeeping and industrial hygiene difficulties, and potentially a combustible dust hazard for the users. Apparatus and methods for reducing the amount of both free and surface-attached powder in a mixture of granular polysilicon and polysilicon powder are disclosed.

[0050] The present disclosure provides systems and methods for separating powder from larger granular material, such as silicon powder from polysilicon granules. The disclosed systems can include fluidized bed systems configured as spouted bed systems including a central inlet or nozzle through which fluidization gas is introduced. The spouted bed systems can comprise an injector assembly coupled to a main vessel and in fluid communication with the main vessel. Fluidization gas can he introduced into the main vessel through the injector assembly. The injector assembly can comprise a main injector body comprising a central bore and an inner chamber surrounding the4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 central bore. One or a plurality of injector conduits can be received in the central bore of the injector body. Fluidization gas can be introduced into the chamber, and can flow from the chamber into the injector conduit(s) and into the main vessel to circulate the polysilicon granules in the main vessel. The fluidization gas can be controlled to create a fountain of polysilicon granules, and circulate the granules within the bed. Contact between the polysilicon granules and with the walls or ceiling of the main vessel can remove silicon powder attached to surfaces of the granules, as well as polish the surfaces and remove microscopic attached structures from the granules. Powder can become entrained in the flow of fluidization gas through the bed, and can be carried out of the vessel through an outlet. In some examples, various substances and / or surface treatments can be applied to the polysilicon granules to facilitate separation of powder particles, such as humidified fluidization gas. Additionally, although the following examples proceed with reference to polysilicon granules produced in a fluidized bed reactor, it should be understood that the systems and methods disclosed herein can also be applicable to separating powder from other types of material, such as rocks, glass beads, metal pellets, etc. Accordingly, the term “granular material” refers to granules and / or beads of any type of material having a size range similar to the ranges given herein for granular polysilicon.

[0051] Example 1: Spouted Bed Powder Separation System

[0052] FIG. 1 illustrates a representative example of a spouted bed powder separation system 10 (also referred to as a “polishing system” and a “powder removal system”). The powder separation system 10 can be a specific type of fluidized bed system in which fluidization gas is provided through a single, centrally located inlet or orifice, rather than through a multi-orifice distributor plate or a multi-nozzle system. However, it should be understood that the systems and methods described herein can also be implemented using multi-orifice or multi-nozzle fluidized bed systems.

[0053] The powder separation system 10 can comprise a main vessel 12, a cone 14 at the lower end of the main vessel 12, and a top cover plate 16 at the top of the main vessel 12. An injector assembly 18 can be coupled to an outlet 20 of the cone 14.

[0054] FIG. 2 is a cross-sectional view illustrating the injector assembly 18 and the lower end of the cone 14 in greater detail. As shown in FIG. 2, the cone 14 and the main vessel 12 can comprise an outer wall 22 and an inner liner 24. In certain examples the inner liner 24 can comprise silicon, silicon carbide (SiC), quartz, polyethylene, high-purity metal alloys, or physically or chemically coated walls of any type, or another non-contaminating material, as further discussed below.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0055] The injector assembly 18 can comprise a first collar (also referred to as an upper collar) 26, a second collar (also referred to as a lower collar) 28, and a main injector body 30 between the first and second collars 26 and 28. The main injector body 30 can define a central bore 32. The upper end portion of the main injector body 30 can further comprise a counterbore 34. A first injector conduit (also referred to as a first or upper injector insert) 36 can be received in the counterbore 34 and can extend upwardly through the first collar 26. The first injector conduit 36 can define a bore, and can comprise a first flange 38 at one end and a second flange 40 at a second end. The cone 14 can be seated on the upper surface of the first flange 38. The second flange 40 can be received in the counterbore 34 of the main injector body 30.

[0056] The injector assembly 18 can further comprise a second injector conduit (also referred to as a second or lower injector insert) 42. The second injector conduit 42 can comprise a flange 44 received in the counterbore 34 of the main injector body 30, and a tubular portion 46 extending through the central bore 32 of the main injector body 30.

[0057] The main injector body 30 can define an annular chamber 48 surrounding the central bore 32. The annular chamber 48 can be defined by an inner wall 50, an outer wall 51 , an upper wall 52, and a lower wall 53. The main injector body 30 can further comprise an annular gap 54 defined between the inner wall 50 and the lower wall 53 in the floor of the chamber 48. The annular gap 54 can thus place the chamber 48 in fluid communication with a withdrawal conduit 71 , which can include the bore of the lower collar 28.

[0058] The interface between the first injector conduit 36 and the second injector conduit 42 can be sealed using one or a plurality of flexible and / or compressible seals, such as gaskets. For example, one or a plurality of gaskets 58 can be positioned between the flange 44 of the second injector conduit 42 and the lower surface of the counterbore 34. Additional gaskets can be positioned between the flange 40 of the first injector conduit 36 and the flange 44 of the second injector conduit 42, and between the flange 40 and the collar 26. The counterbore 34 of the main injector body 30, the collar 26, and the gaskets 58 can form a flexible coupling 60 between the first injector conduit 36 and the cone 14 of the main vessel 12. In particular, the gaskets 58 can allow the first injector conduit 36 to move relative to the main injector body 30, the second injector conduit 42, and the cone 14. This can facilitate precise alignment and sealing between the mating surfaces of the cone outlet 20 and the flange 38 of the first injector conduit 36.

[0059] The flange 38 of the first injector conduit 36 can define a flange surface 62. The flange surface 62 can be oriented upwardly into the interior of the cone 14 and the main vessel 12. The flange surface 62 can be in contact with at least the silicon carbide inner wall 24 of the cone 14.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025The flange surface 62 can be configured such that an annular inner portion 65 of the flange surface 62 is exposed and oriented upwardly. For example, in some examples the exposed annular inner portion 65 can comprise 20% to 50% of the total surface area of the flange surface 62, such as 20% to 40% or 20% to 30%.

[0060] FIG. 3 illustrates the top cover plate 16 of the main vessel 12 in greater detail. The top cover plate 16 (and therefore the vessel 12) can comprise a variety of inlets and outlets to facilitate, for example, introduction of polysilicon granules, withdrawal of fluidization gas, sensing, etc. The cover plate 16 illustrated in FIG. 3 includes a polysilicon granule inlet 64, a gas vent outlet 66, and a pressure tap 67. In other examples, one or more of the inlets and outlets above can be combined. For example, polysilicon can be introduced and fluidization gas can be withdrawn through the same port, when operating the unit in batch mode or continuous batch mode. The cover plate can also have more than three inlets / outlets, such as a plurality of gas outlets and / or a plurality of polysilicon inlets, such as for continuous operation involving simultaneous feeding of beads and withdrawal of gas and separated fines and dust.

[0061] Surfaces in contact with the polysilicon granules in the spouted bed powder separation system 10 can be coated with and / or made of silicon (Si), silicon carbide (SiC), quartz, high-purity metal compounds, or coated with high-purity coatings, or other non-contaminating materials. Thus, the components of the spouted bed powder separation system 10 can be made from, or can be sheathed in, silicon, silicon carbide, or another non-contaminating material. The surfaces in contact with the polysilicon can thus comprise material(s) configured to maintain the polysilicon at a purity of one part per million to one part per trillion. For example, the inner wall 24 of the main vessel 12 and the cone 14 can comprise silicon carbide. The first and second injector conduits 36 and 42, the collar 28, and the withdrawal tube 71 can also comprise silicon carbide.

[0062] The powder separation system 10 can be operated in a batch process or continuously. For example, referring again to FIG. 1, in batch operation a consignment of polysilicon granules (represented schematically at 68) can be introduced into the main vessel 12 through the inlet 64. An inert fluidization gas (e.g., nitrogen, argon, helium, etc.) can be introduced into the main vessel 12 through the injector assembly 18. For example, referring to FIG. 2, fluidization gas can be supplied to the chamber 48 of the main injector body 30 at a selected pressure. The fluidization gas can flow through the annular gap 54 into the lower collar 28 and / or the withdrawal tube 71 as indicated by arrows 70. In some examples, the withdrawal tube can be sealed such that the inert gas flows upwardly into the second injector conduit 42, through the first injector conduit 36, and into the cone 14, as indicated by arrows 74.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0063] Referring to FIG. 1, the pressure and flow rate of the inert gas can be selected to at least partially inflate and / or fluidize the bed of polysilicon granules 68 in the main vessel 12. The inert gas can create a fountain (also referred to as a spout or a plume) 72 of poly silicon granules 68 inside the main vessel 12. This can cause the polysilicon granules 68 to circulate inside the main vessel 12 with upward motion at the center along the fountain 72 as indicated by arrows 78, and downward motion along the walls of the vessel and cone 14 as indicated by arrows 80. The system can produce a steady state fountain 72 during operation, or the fountain 72 can collapse and reform in an unstable manner.

[0064] As the polysilicon granules 68 move in the main vessel 12, free silicon powder in the bed and silicon powder attached to surfaces of the granules can become entrained in the flow of fluidization gas. Polysilicon granules can contact each other as they tumble, can contact the walls of the vessel and the cone or the ceiling of the vessel, and / or can contact the flange surface 62 of the first injector conduit 36. The tumbling action of the polysilicon granules 68 in the fluidized bed can dislodge powder from the surfaces of the granules, as well as remove surface irregularities from the granules. The entrained silicon powder, represented schematically at 75, can flow upwardly through the vessel 12 and out through the gas outlet 66.

[0065] Upon completion, the amount of silicon powder present in the polysilicon granule consignment can be reduced from 0.25% to 10%, such as 0.25% to 5% or 0.25% to 3% by mass at the start of the separation process, to 0.25% or less. For example, the amount of powder present in the granule consignment can be 0.0001 % to 0.25%, 0.0001 % to 0.1 %, 0.0001 % to 0.01 %, 0.0001 % to 0.005%, or 0.0001% to 0.003% by mass, depending upon the particular product specifications. At the conclusion of the process, the fluidization gas flow volume can be reduced or stopped and the polished polysilicon granules can be withdrawn through the withdrawal conduit 71.Alternatively, polysilicon granules can be added and withdrawn continuously, or in batches, during operation. As can be seen from FIG. 2, the flow path defined by the injector conduits 36 and 42 can be used both for the introduction of fluidization gas as well as for withdrawal of polysilicon granules from the vessel.

[0066] In some examples, the polysilicon granules (or other granular material) can comprise a surface treatment to facilitate powder removal and / or polishing. Examples of surface treatments include additives such as solids, liquids, or gases that alter or moderate the surfaces of the materials (e.g., the polysilicon granules, fines, and / or powder) in some manner. The surface treatments can modify the roughness, oxidize, and / or form a reactive coating or a physical coating, can moderate4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 dust and / or fines adhesion to larger particles, etc. Such coatings may be temporary, such as coatings that evaporate.

[0067] Particular surface treatments that can be used include oxidation with air, oxygen, water vapor (also referred to as “moisture”), or other oxidizing compounds, such as sulfur dioxide, ozone, organic oxidants, or water. For example, water can be added to the inert fluidization gas to achieve a selected humidity. In some examples, humidified fluidization gas can reduce static charges and / or Van der Waals forces between powder particles and the polysilicon granules, facilitating removal of attached powder from the granules. In some examples, after polishing the humidified fluidization gas or other oxidation gas can be purged from the vessel with dry inert gas. In some examples pre-oxidation of the material, in ways described above, can weaken the bonds between the small and larger particles, as described above, so that the particles are more easily separated in the fluidized bed. Other examples of surface treatments include sulfates, carbonates, peroxides, organic and inorganic acids, and mixtures of such chemicals, which can be mixed with the fluidization gas, applied in liquid form, or in solid form, at elevated or ambient temperature, with or without subsequent separation, removal, and / or vaporization.

[0068] Other surface treatments include surface oxidation of the poly silicon granules, such as with oxygen gas, air, steam, water, humidified inert gas, etc. This can be accomplished either simultaneous with particle separation or prior to processing the particles in the fluidized bed.

[0069] FIG. 4 illustrates an exemplary method of removing powder from granular material (e.g., silicon powder from poly silicon granules), comprising introducing granular material into a main vessel of a spouted bed powder separation system at process block 90, flowing fluidization gas through the granular material at process block 92 to at least partially fluidize the granular material and circulate the granular material in the main vessel, withdrawing fluidization gas from the main vessel at process block 94, the withdrawn fluidization gas containing entrained powder, and withdrawing granular material from the main vessel at process block 96. The withdrawn granular materia] can comprise a reduced percentage by mass of powder than the introduced granular material.

[0070] Example 2: Spouted Bed Powder Separation System with Injector Extending into Vessel Cone

[0071] FIG. 5 illustrates another example of an injector assembly 100 configured similarly to the injector assembly 18 with a main injector body 130, a first injector conduit 136, a second injector conduit 142, an upper collar 126, a lower collar 128, and a withdrawal tube 171. One difference between the injector assembly 18 and the injector assembly 100 is that the tube of the first injector4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 conduit 136 extends upwardly inside the cone 114 of the main vessel. Features in FIG. 5 are given similar reference numbers to corresponding features in FIGS. 1-3.

[0072] Example 3: Additional Examples Relating to Operational Parameters and Surface Treatments

[0073] In any or all of the disclosed examples, the particle separation systems disclosed herein can use a fluidized bed to separate particles from one another by size. For example, the disclosed technology may be used to separate fines and ultrafine particles from larger particles or granules. The disclosed technology may be used to separate fines and dust from larger particles that are all of the same material. The disclosed technology concerns spouting bed technology, as one form of a fluidized bed that may be used for the purpose of separating particles by size.

[0074] In any or all of the disclosed examples, fines and submicron particles can be separated from one another via gas velocities in a fluidized bed - for example, smaller particles will be entrained in the gas flow through the bed, while larger particles are retained in the bed.

[0075] In any or all of the disclosed examples, the lines and smaller particles are carried out an exhaust vent in the freeboard of the fluidized bed during the operation of the fluidized bed.

[0076] In any or all of the disclosed examples, the addition and removal of the material from the bed may be continuous - fresh granules are continuously added to the fluidized with a wide particle size distribution, the fluidized bed continually separates powder and fines from these granules, and carries out the smaller particles / powder from the fluidized bed (e.g., from the top of the free board), and also continuously removes the larger granules (e.g., from the bottom of the fluidized bed).

[0077] In any or all of the disclosed examples, the fluidized bed may operate in batch mode, whereby a specific load of granules is introduced into the fluidized-bed chamber initially, before particle separation begins, and then the fluidization is increased to particle-separation conditions (also referred to as “polishing conditions”), operated at those polishing conditions for a specific period of time to remove the smaller particles from the bed, and at the end of polishing, the fluidization is stopped, and the remaining (larger particles) are removed from the fluidized bed, for example by gravity drain from the bottom of the fluidized bed.

[0078] In any or all of the disclosed examples, the material to be size separated is a heterogeneous mixture of different materials, actual and / or geometrically different.

[0079] In any or all of the disclosed examples, the material to be size separated is a homogeneous mixture of similar materials or near-exactly the same material, only differing by size and / or shape, or no difference in shape.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0080] In any or all of the disclosed examples, the material to be size-separated is silicon granules (also referred to as beads), with smaller silicon-bead fines and dust and / or submicron silicon particles (e.g., powder) in the mix.

[0081] In any or all of the disclosed examples, the material to be size-separated or polished by fluidization is without surface treatment (intentional, inherent, or inadvertent), for example any type of coating, oxidation, reactive surface, roughness of the surfaces, passivation of the particles surfaces, or addition of any non-inert gases, such as air, oxygen, hydrogen, acid, water, or water vapor, or moisture of any kind.

[0082] In any or all of the disclosed examples, the material to be size-separated or polished by fluidization has been surface treated or introduced to the fluidized bed with substances, solids, liquids, or gases that may alter or moderate the surfaces of the material (e.g., particles, fines, and dust) in some manner. Such alteration or moderation of the surface can include changes in surface roughness, or oxidation, or reactive coating or physical coating or dust and / or fines adhesion to larger particles or temporary coatings (such as coatings that may evaporate).

[0083] In any or all of the disclosed examples, the surface treatment is oxidation of the surface of the particles via natural or minor or small amount of oxidation, obtained either naturally, by intentional weathering, or purposefully, for either a non-specific amount of oxidation, or for a specific amount of oxidation.

[0084] In any or all of the disclosed examples, the oxidizer is oxygen, air, steam, water, or moist air or moist other gas, or other type of oxidizing gas, liquid, or solid.

[0085] In any or all of the disclosed examples, the surface oxidation of the particles is much less than a monolayer of molecules thick, slightly less than a monolayer thick, a monolayer thick, slightly greater than a monolayer of molecules thick, much greater than a monolayer of molecules thick, or slightly less than, exactly, or much greater than one millimeter thick.

[0086] In any or all of the disclosed examples, the surface treatment either strengthens or weakens the bonds of smaller particles, fines, and / or dust to other particles, and / or larger particles.

[0087] In any or all of the disclosed examples, whereby the surface treatment or additive weakens the bonds (e.g., “bonds” here referring to a generic term meaning that there is an attractive force of some kind between the particles) between particles to be separated.

[0088] In any or all of the disclosed examples, the bonds (as defined above) that are weakened are physical, chemical, static charges, or Van Der Waals forces, or a combination of these attractive forces.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0089] In any or all of the disclosed examples, moisture is added and maintained in the fluidized bed during fluidization, particle separation, and / or polishing, thus maintaining a specified level of moisture on the surface of the particles during the fluidization process.

[0090] In any or all of the disclosed examples, at the end of fluidization with an additive gas, or liquid, the surface modifier is removed or purged.

[0091] In any or all of the disclosed examples, the purge gas is dry inert gas.

[0092] In any or all of the disclosed examples, at the end of particle separation via fluidization, the gas filling the chamber is switched from one gas to another, such as from nitrogen to argon, or from moist air to argon or nitrogen, or from moist nitrogen to argon. These are just examples and not intended to limit the types of gases that may be used or interchanged.

[0093] In any or all of the disclosed examples, the velocity in in the fluidized bed and the associated geometry and granule size are chosen to balance the granule-granule and granule- vessel surface impact necessary to effect particle separation and / or fines and / or dust removal, while not creating, or limiting the creation of, impacts so great that the granules fracture, thus creating more fines, dust, smaller particles, or submicron particles.

[0094] In any or all of the disclosed examples, the type of fluidized bed used is a spouting fluidized bed, where the vessel itself is a cylinder, substantially taller than it is wide, with a concentrical jet flowing up through the bottom of the bed, with a diameter that is less than Vi the diameter of the spouting bed vessel, the entire bed being inflated substantially by the addition of gas through the jet, while the jet itself penetrates through the top of the bead (substantially below the top of the vessel) creating a spout that falls back down with other granules in a puffed-up but gravity fed annulus of the vessel, until the granules reach the bottom of the vessel again and are entrained once again in the spouting jet that passes back up through the bed and creates the fountain that falls back down on the bed again.

[0095] In any or all of the disclosed examples, the spouting fluidized bed vessel is between 3 feet and 100 feet tall, and between 1 inch and 20 feet wide.

[0096] In any or all of the disclosed examples, the spouting fluidized bed vessel is between 5 feet and 20 feet tall, and between 6 inches and 5 feet wide.

[0097] In any or all of the disclosed examples, the spouting fluidized bed vessel is between 8 feet and 15 feet tall, and between 1 foot and 4 feet wide.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025

[0098] In any or all of the disclosed examples, gas is injected up into the vessel from the bottom of the vessel outlet discharge, for the purpose of preventing particle fracturing as it falls into the vessel and / or to prevent the outlet discharge or bottom gas injectors from getting plugged.

[0099] In any or all of the disclosed examples, the particle size distribution and density of the particles to be separated in the spouting fluidized bed is able to be separated in a stable spouting bed operation, whereby the fountain produces a relatively continuous spouting fountain above the top of a relatively consistent lower (but still puffed-up) bed level (of gravity-traversing particles in the annulus of the spouting bed).

[0100] In any or all of the disclosed examples, the particle size distribution and density of the particles to be separated in the spouting fluidized bed is not maintained in stable spouting bed operation. Rather, particle separating, dedusting, and / or polishing occurs while the spouting bed is continually changing in unstable operation, whereby the bed height is constantly changing, the jet annulus is constantly collapsing, and the jet passing through the bed is blasting through the bed, first appearing, then disappearing, and reappearing, all in an unstable manner.

[0101] In any or all of the disclosed examples, the disclosed fluidized bed technology can be used to produce polished, high-purity silicon beads for making ingots as part of the process for making solar panels.

[0102] In any or all of the disclosed examples, the disclosed fluidized bed technology can be used to produce polished, high-purity silicon beads for making electronics grade silicon wafers. For example, polysilicon granules can be melted in a crucible and drawn into single-crystal boules (also referred to as “ingots”) using, for example, the Czochralski process for the production of monocrystalline silicon for semiconductor wafers and / or photovoltaic cells.

[0103] The fluidized / spouted bed powder separation systems described herein can provide one or more significant advantages over existing powder separation systems. For example, using a fluidized / spouted bed to separate larger solid particles from powder can be implemented in many industrial applications. The fluidized / spouted bed powder separation systems described herein can provide a reduction of cost, reduction of processing time, reduction in equipment space, reduction in electricity usage, and / or a separation process that produces higher-quality product. The disclosed systems can provide more precise size and / or density segregation than found in other size separation technologies, and / or can produce a product that contains less residual contamination.

[0104] The use of fluidized / spouted bed technology in the case of manufacturing pure silicon beads can provide the advantage of being able to effectively remove fines, dust, and / or submicron particles from the bulk of the larger particle size distribution, doing so more efficiently, effectively,4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 continuously, and able to take up little space in-line within the manufacturing train for processing high-purity silicon beads.

[0105] Other improvements include reduced cost and electricity usage, and reduced size and / or floor-space and total footprint of the equipment because of the vertical arrangement of the equipment and the much smaller size of the equipment needed than other technologies. This can facilitate incorporating the disclosed technology into a fluidized bed silicon manufacturing line in a continuous and compact manner.

[0106] Another improvement concerns the ability to effectively polish the beads, while not attritting the beads, which would create more fines, dust, and submicron particles.

[0107] Polysilicon granules can be polished without any oxidation or moisture addition or other additives, or with moisture added to the fluidized bed (e.g., added to the fluidization gas) while separating the particles. The addition of moisture has been determined to improve the ability to separate the particles, particularly the fines and dust and submicron particles from the larger granules in the distribution of particles being processed.

[0108] Another aspect of the disclosed technology is the use of a spouting fluidized bed as the type of fluidized bed for size separation and / or polishing. A benefit of using a spouting fluidized bed is that this particular type of fluidized bed design is relatively small compared with other types of fluidized bed. For example, the narrow, tall design makes it easily adaptable into a vertical processing train of product, particularly so for the production of high-purity silicon beads. This can facilitate continuous manufacturing of polysilicon granules, even when the spouting fluidized bed is operated in intermittent batch mode.

[0109] The systems described herein can also be operated to separate powder from larger granular material, which separated powder can be free or substantially free of larger granular material (e.g., granules having a largest dimension of 0.25 mm or greater, such as 0.25 to 3.5 mm). The powder separated from the granular material in the spouted bed system can be collected (such as with a filter) for further processing.

[0110] The systems described herein can be used to separate powder from granular materials including, for example, rocks, granite, feldspar, quartz, glass beads of any type (e.g., lead, borosilicate, fluorosilicate, soda-lime, PYREX® borosilicate glass), iron pellets, steel beads, ball bearings, pellets, metal pellets of any types (e.g., Mg, Mn, Pb, Al, Sb, Ni, Zn, Ti, Ga, Pt, Ag, Pd, Rh, Mo, Zr, their oxides and combinations of these metals and metal oxides), sand, separation of nanoparticles from larger particles, and / or pelletized carbon structures such as coal, wood,4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 petroleum, and grass-based carbon structures. The disclosed systems and methods can also be used in environmental, safety, and health (ES&H) applications, as well as in housekeeping.

[0111] In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are only examples and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is at least as broad as the following claims and equivalents of the recited features. We therefore claim all that comes within the scope and spirit of these claims.

Claims

4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025CLAIMS:

1. A system for separating powder from granular material, comprising: a main vessel; a cone at a lower end of the main vessel; an injector assembly coupled to the cone, the injector assembly including an injector conduit configured to direct fluidization gas into the main vessel through the cone and withdraw granular material from the main vessel; wherein the main vessel comprises a top cover including an outlet through which fluidization gas and entrained powder can be withdrawn.

2. The system of claim 1 , wherein the injector conduit comprises a flange defining a flange surface, the cone of the main vessel is coupled to the flange surface, and an inner portion of the flange surface is exposed and oriented upwardly to contact granules circulating in the main vessel.

3. The system of claim 1 or claim 2, wherein the injector assembly further comprises a main injector body defining a central bore and an inner chamber surrounding the central bore, and the injector conduit is received in the central bore of the main injector body.

4. The system of claim 3, wherein the chamber of the main injector body is at least partially defined by an inner wall, an outer wall, an upper wall, and a lower wall, and the chamber is in fluid communication with the central bore through an annular gap defined between the lower wall and the inner wall surrounding the central bore.

5. The system of claim 3 or claim 4, wherein: the injector conduit is a first injector conduit; and the injector assembly further comprises a second injector conduit coupled to the first injector conduit and in fluid communication with the first injector conduit, the first and second injector conduits being coupled together by a flexible coupling to facilitate mating between the cone and the flange surface of the first injector conduit.

6. The system of claim 5, wherein: the main injector body comprises a counterbore defined concentrically with the central bore;4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 end portions of the first and second injector conduits are received in the counterbore of the main injector body; and an interface between the first injector conduit and the second injector conduit is sealed with one or a plurality of seals to form the flexible coupling.

7. The system of any one of claims 1-6, wherein the top cover of the main vessel further comprises an inlet configured to supply granular material to the main vessel.

8. The system of any one of claims 1-7, wherein the system is configured as a spouted bed powder separation system.

9. The system of any one of claims 1-8, wherein the granular material is polysilicon granules, and surfaces that are configured to be in contact with the polysilicon granules comprise silicon, silicon carbide, quartz, polyethylene, high-purity metal alloys, or any combination thereof.

10. A method, comprising: introducing granular material into a main vessel of a spouted bed powder separation system; flowing fluidization gas through the granular material to at least partially fluidize the granular material and circulate the granular material in the main vessel; withdrawing fluidization gas from the main vessel, the withdrawn fluidization gas containing entrained powder; and withdrawing granular material from the main vessel, wherein the withdrawn granular material comprise a reduced percentage by weight of powder than the introduced granular material.

11. The method of claim 10, wherein the fluidization gas contains a surface conditioning agent.

12. The method of claim 11, wherein the surface conditioning agent comprises an oxidizer, acid, or evaporative coating.

13. The method of claim 12, wherein the fluidization gas is humidified with water.

14. The method of claim 12 or claim 13, further comprising purging the conditioning gas or humidified fluidization gas with dry inert gas.4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 202515. The method of any one of claims 10-14, wherein the granular material is pre-treated by being pre-oxidized, pre-moisturized, pre-coated, or pre-acid washed.

16. The method of any one of claims 10-15, wherein particles of the entrained powder have a diameter of 40 nm to 250 pm.

17. The method of any one of claims 10-16, wherein flowing the fluidization gas through the granular material further comprises producing a fountain of granules.

18. The method of claim 17, further comprising controlling the flow of fluidization gas to generate a stable fountain of granules, or controlling the flow of fluidization gas such that the fountain forms, collapses, and reforms in an unstable manner.

19. The method of any one of claims 10-18, wherein the fluidization gas flows into the main vessel through an injector conduit of an injector assembly, and the method further comprises withdrawing granular material from the main vessel through the injector conduit of the injector assembly.

20. The method of any one of claims 10-19, wherein the granular material comprises granular polysilicon.

21. A method, comprising operating the system of claim 1 to produce granular material free from dust and fines.

22. A method, comprising operating the system of claim 1 to produce dust and fines free from granular material.

23. A method, comprising operating the system of claim 1 to produce a combination of separated smaller particles, dust and fines, and larger particles.

24. A method, comprising: introducing polysilicon granules into a main vessel of a spouted bed powder separation system;4550-112316-02 FILED ELECTRONICALLY ON SEPTEMBER 2, 2025 flowing fluidization gas through the polysilicon granules to at least partially fluidize the polysilicon granules and circulate the polysilicon granules in the main vessel; withdrawing fluidization gas from the main vessel, the withdrawn fluidization gas containing entrained polysilicon powder; and withdrawing polysilicon granules from the main vessel, wherein the withdrawn polysilicon granules comprise a reduced percentage by weight of polysilicon powder than the introduced polysilicon granules.

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