Extraction device

{
  "publication_number": "US2010308288A1",
  "country": "US",
  "kind": "A1",
  "title": "Extraction device",
  "abstract": "An extraction device is provided for use when extracting a ceramic foam filter, as used for example in the production and processing of aluminium. The extraction device includes an anchor device (3) suitable for driving into the filter, said anchor device (3) having an anchor body (5) with a leading end and a trailing end, a screw thread (13) for engagement with the filter and a substantially pointed part (7) at the leading end for piercing a surface of the filter.",
  "claims": [
    "1. An extraction device for use when extracting a ceramic foam filter, the extraction device including an anchor device suitable for driving into the filter, said anchor device having an anchor body with a leading end and a trailing end, a screw thread for engagement with the filter and a substantially pointed part at the leading end for piercing a surface of the filter. 2. The extraction device according to claim 1, wherein the outer diameter of the screw thread varies along its length. 3. The extraction device according to claim 2, wherein the outer diameter of the screw thread increases from a minimum at the leading end to a maximum at the trailing end. 4. The extraction device according to claim 1, wherein the maximum diameter of the screw thread is in the range of 20-100 mm. 5. The extraction device according to claim 1, wherein the pointed part is an integral part of the anchor body. 6. The extraction device according to claim 1, further comprising a helical groove formed in the anchor body for engagement with the filter. 7. The extraction device according to claim 6, wherein the radial depth of the groove varies along the length of the body. 8. The extraction device according to claim 7, wherein the radial depth of the groove increases from the trailing end towards the leading end, thereby reducing the diameter of the body from a maximum at the trailing end to a minimum at the leading end. 9. The extraction device according to claim 1, wherein the maximum radial depth of the screw thread is in the range of 10-45 mm. 10. The extraction device according to claim 1, wherein anchor body has a maximum diameter in the range 13-22 mm. 11. The extraction device according to claim 1, wherein the screw thread has an upper surface that extends substantially perpendicularly from the anchor body. 12. The extraction device according to claim 1, wherein the screw thread has a lower surface that extends from the anchor body such that it is inclined to the anchor body. 13. The extraction device according to claim 1, wherein the screw thread has a substantially triangular cross-section and is arranged to taper from a root portion at the body to a sharp cutting edge. 14. The extraction device according to claim 1, wherein the screw thread has a side wall, and the side wall is inclined to the longitudinal axis of the anchor device. 15. The extraction device according to claim 1, wherein the screw thread has a lower surface that extends substantially perpendicularly from the anchor body. 16. The extraction device according to claim 1, wherein the thickness of the screw thread is in the range of 1-30 mm. 17. The extraction device according to claim 1, wherein the screw thread comprises from one to four turns. 18. The extraction device according to claim 1, wherein the screw thread has a pitch in the range 5-45 mm. 19. The extraction device according to claim 1, wherein the screw thread has an overall length that is less than or equal to 48 mm. 20. The extraction device according to claim 1, wherein the extraction device is made from carbon steel. 21. The extraction device according to claim 1, further including lifting means. 22. The extraction device according to claim 21, wherein the lifting means is releaseably connectable to the anchor device. 23. A method of extracting a ceramic foam filter, the method including screwing an extraction device according to claim 1 into the filter, and lifting the extraction device to extract the filter."
  ],
  "description_excerpt": "The present invention relates to an extraction device for use when extracting a ceramic foam filter, as used for example in the production and processing of aluminium and other metals. Molten aluminium usually has to be filtered before it is cast. The filtration process removes particles that could otherwise cause rejects in the final products. Traditionally, ceramic foam filters are used. These are made from alumina refractory slurry by impregnating a reticulated foam manufactured to a specific porosity with the slurry. The impregnated foam is then dried and fired in a kiln. The foam burns off leaving a porous ceramic body, which is used as the filter. Ceramic filters come in various sizes, typically 7″, 9″, 12 ″, 15 ″, 17 ″, 20 ″, 23 ″ and 26″ square, and 2″ thick (16 cm, 20 cm, 27 cm, 34 cm, 38 cm, 45 cm, 52 cm and 58 cm square, and 5 cm thick). For use, the filter is mounted in a refractory filter bowl. Liquid aluminium is poured into the bowl through the filter, which traps fine particles in the liquid metal. When the casting operation is complete, the aluminium remaining within the ceramic filter freezes, forming a block of virtually solid aluminium.\n\nAfter use, the filter must be removed and replaced before the next casting operation. Current industrial practice to remove the filter is to stab a hole in the filter while it is still full of liquid aluminium with a hooked steel bar. The aluminium is then allowed to freeze, after which the filter is pulled out using the bar. This is not however a very elegant or safe solution, as liquid metal can splash out when puncturing the filter.",
  "cpc": [
    "C22B 9/023",
    "B25B 27/023",
    "C22B 21/066",
    "F16B 2037/007",
    "F16B 23/0084",
    "F16B 25/103",
    "Y02P 10/20"
  ],
  "ipc": [
    "B66F 3/00"
  ],
  "assignees": [
    "PYROTEK ENGINEERING MATERIALS LTD"
  ],
  "inventors": [
    "VINCENT MARK"
  ],
  "filing_date": "2008-10-06",
  "publication_date": "2010-12-09",
  "priority_date": "2007-10-12",
  "application_number": "US-68222908-A",
  "family_id": "38788082",
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}