Surface conditioning of conveyor materials or contact surfaces

{
  "publication_number": "US10005614B2",
  "country": "US",
  "kind": "B2",
  "title": "Surface conditioning of conveyor materials or contact surfaces",
  "abstract": "A method of reducing contamination in a silicon product includes: moving silicon pieces along a conveyance system, wherein the conveyance system comprises a liner having a polished surface finish with a surface roughness of less than or equal to 12 microinches; and moving the silicon pieces across the conveyance system, wherein the silicon pieces contain a reduced number of impurities as compared to silicon pieces in contact with a liner having an unpolished surface. A crushing tool includes: crushing tool elements configured to crush silicon into fragments, wherein the crushing tool elements comprise a surface comprising a polished surface finish with a surface roughness of less than or equal to 12 microinches. A conveyance system includes: a first conveyor discharged onto a second conveyor; wherein the first conveyor comprises a first liner and wherein the second conveyor comprises a second liner.",
  "claims": [
    "1. A method of repairing a conveyance system comprising a liner having a polished surface finish with a surface roughness of less than or equal to 12 microinches, comprising: removing a portion of the liner when the portion of the liner has a surface roughness of greater than 12 microinches; grinding and/or polishing the portion of the liner having a surface roughness of greater than 12 microinches, until the surface roughness is less than or equal to 12 microinches; and reinstalling the portion of the liner to the same or a different conveyance system or conveyors for reuse.",
    "2. The method of claim 1, wherein the liner comprises a material comprising tungsten, carbon, cobalt, or a combination comprising at least one of the foregoing.",
    "3. The method of claim 2, wherein the material comprises less than or equal to 20 weight percent cobalt.",
    "4. The method of claim 1, wherein the conveyance system comprises at least one conveyance device configured to move silicon pieces from a starting point to a finishing point.",
    "5. The method of claim 4, further comprising moving the silicon pieces from a first conveyance device to a second conveyance device, wherein the first conveyance device is disposed above the second conveyance device, wherein the liner is present in the first conveyance device and wherein a second liner is present in the second conveyance device.",
    "6. The method of claim 5, wherein the surface roughness of the second liner remains unchanged when the silicon pieces are dropped from the first conveyance device onto the second conveyance device.",
    "7. The method of claim 1, wherein the conveyance system further comprises a first conveyor and a second conveyor and wherein the method further comprises moving the silicon pieces from the first conveyor to the second conveyor, wherein the first conveyor is at a height, h 1, and the second conveyor is at a height, h 2, wherein h 1 is greater than h 2; wherein the first conveyor comprises the liner and wherein the second conveyor comprises a second liner; wherein the liner and the second liner comprise a material comprising tungsten, carbon, cobalt, nickel, chromium, or a combination comprising at least one of the foregoing.",
    "8. The method of claim 7, wherein the material comprises tungsten carbide, tungsten carbide with a cobalt binder, tungsten carbide with a nickel binder, chromium carbide, chromium carbide with a nickel binder, or a combination comprising at least one of the foregoing.",
    "9. The method of claim 7, wherein the second liner has a polished surface finish with a surface roughness of less than or equal to 12 microinches before and after the silicon pieces are moved from the first conveyor to the second conveyor.",
    "10. The method of claim 9, wherein the surface roughness of the liner and/or the second liner is 0.5 microinch to 12 microinches.",
    "11. The method of claim 7, further comprising moving the silicon pieces across the second conveyor, wherein the silicon pieces contain a reduced number of impurities as compared to silicon pieces in contact with a liner having an unpolished surface.",
    "12. A method of repairing a conveyance system, comprising a first conveyor discharging silicon pieces onto a second conveyor, wherein the first conveyor is at a height, h 1, and the second conveyor is at a height, h 2, wherein h 1 is greater than h 2; wherein the first conveyor comprises a first liner and wherein the second conveyor comprises a second liner; wherein the first liner and the second liner comprise a material comprising tungsten, carbon, cobalt, nickel, chromium, or a combination comprising at least one of the foregoing, wherein the method comprises: removing a portion of the first conveyor and/or the second conveyor from the conveyance system when the portion of the conveyance system has a surface roughness of greater than 12 microinches; grinding and/or polishing the first conveyor and/or the second conveyor having a surface roughness of greater than 12 microinches, until the surface roughness is less than or equal to 12 microinches; and reinstalling the first conveyor and/or the second conveyor to the same or a different conveyance system for reuse.",
    "13. The method of claim 12, wherein the first liner has a polished surface finish with a surface roughness of less than or equal to 12 microinches; and wherein the second liner has a polished surface finish with a surface roughness of less than or equal to 12 microinches before and after the silicon pieces are moved from the first conveyor to the second conveyor.",
    "14. The method of claim 12, wherein the surface roughness of the first liner and/or the second liner is 0.5 microinch to 12 microinches."
  ],
  "description_excerpt": "Disclosed herein are methods for reducing contamination in a silicon product. Also disclosed herein are crushing tools and conveyance systems.\n\nPolysilicon is used as a starting material for semiconductors or wafers in solar applications. The use of such polysilicon must be highly pure (e.g., for semiconductor applications at least 99.9999999% pure (i.e., nine nines pure) and for solar applications at least 99.9% pure. In order to prevent issues with a reduction in desired properties, such as electrical properties, the polysilicon should not be mixed with metal impurities wherever possible.\n\nPolysilicon is typically produced by reducing a silicon compound, such as trichlorosilane, with hydrogen and formed into rods. The polysilicon rods are then crushed or broken into smaller pieces. Contaminant or impurities imparted to the polysilicon pieces during the crushing can be removed by etching after which the polysilicon is passed through water and dried and then conveyed to be sorted for further processing or packaging. During each step, the polysilicon can be contaminated with impurities such as metal or polymeric impurities. Steps must be taken to prevent this contamination that will affect the purity of the polysilicon product.",
  "cpc": [
    "B65G 11/166",
    "B02C 19/0056",
    "B02C 4/12",
    "B29D 29/06",
    "B65G 15/48",
    "B65G 2201/042",
    "B65G 37/00",
    "C30B 29/06",
    "C30B 35/005",
    "H10F 77/164",
    "H10P 32/1414",
    "H10P 90/123",
    "H10W 20/074"
  ],
  "ipc": [
    "B02C 19/00",
    "B02C 4/12",
    "B29D 29/06",
    "B65G 11/16",
    "B65G 15/48",
    "B65G 37/00"
  ],
  "assignees": [
    "Hemlock Semiconductor Operations LLC"
  ],
  "inventors": [
    "Jonathan Patrick Berrie",
    "John Victor Bucci",
    "James C. Mundell",
    "Traig William Savage"
  ],
  "filing_date": "2016-02-25",
  "publication_date": "2018-06-26",
  "grant_date": "2018-06-26",
  "priority_date": "2016-02-25",
  "application_number": "US-201615053677-A",
  "family_id": "59580297",
  "cited_by_count": 0,
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}