DEVICE FOR PRODUCING EXPANDED GRANULATED MATERIAL

Abstract

A device for producing expanded granulated material from grains of sand with an expanding agent includes a furnace with a furnace shaft, which has upper and lower ends. A conveying section extends between the ends and passes through separately-arranged heating zones in a conveying direction. At least one feeder charges at least the unexpanded material into the furnace shaft at one end toward the other end. At least one rotatable shaft insert is arranged at least in sections in the furnace shaft and has at least one scraper blade forming with an inner wall of the furnace shaft at least one gap having a gap width and being designed, during rotation of the at least one shaft insert in an operating state of the device, to remove caking on the inner wall at least in sections if a thickness of the caking is greater than the respective gap width.

Description

Claims

1-13. (canceled)

14. A device for producing an expanded granulated material from mineral material in the form of grains of sand with an expanding agent, the device comprising a furnace with a substantially vertically standing furnace shaft having an upper end and a lower end, wherein a conveying section extends between the two ends, wherein further at least one feeding means is provided which is adapted to charge at least the unexpanded material at one of the two ends of the furnace shaft into the furnace shaft in the direction of the other of the two ends of the furnace shaft in order to expand the material, as seen in a conveying direction, in the last half of the conveying section, wherein at least one rotatable shaft insert is provided, which is arranged at least in sections in the furnace shaft and has at least one scraper blade, which forms with an inner wall of the furnace shaft at least one gap having a gap width and which is designed, during rotation of the at least one shaft insert in an operating state of the device, to remove caking on the inner wall in sections if a thickness of the caking is greater than the respective gap width, wherein the at least one shaft insert is rotatable about at least one axis of rotation which extends parallel to a longitudinal axis of the furnace shaft, wherein the conveying section leads through a plurality of heating zones which are arranged separately from one another in a conveying direction, wherein the heating zones each comprise at least one heating element which can be controlled independently of one another in order to heat the material at least to a critical temperature and to expand the sand grains, and wherein the at least one shaft insert each comprises a base body from which the at least one scraper blade projects with a directional portion parallel to a radial direction, wherein the radial direction lies in a plane normal to the axis of rotation of the respective shaft insert and, starting from the respective axis of rotation, faces away therefrom, wherein the respective base body, as viewed at least in the radial direction, is substantially closed.

15. The device according to claim 14, wherein the at least one shaft insert is rotatably mounted in the region of the upper end of the furnace shaft.

16. The device according to claim 14, wherein the at least one shaft insert has a plurality of scraper blades.

17. The device according to claim 16, wherein at least two of the scraper blades are arranged one behind the other as viewed in a circumferential direction around a radial center of the furnace shaft.

18. The device according to claim 16, wherein at least two of the scraper blades form gaps with the inner wall having different gap widths.

19. The device according to claim 14, wherein at least one drive means is provided for rotating the at least one shaft insert at a variable rotational speed.

20. The device according to claim 14, wherein the respective base body is essentially rotationally cylindrical.

21. The device according to claim 14, wherein the at least one scraper blade is arranged on the respective base body such that it can be extended/retracted and/or pivoted in order to be able to adjust the gap width.

22. The device according to claim 14, wherein the at least one scraper blade extends substantially in a straight line.

23. The device according to claim 14, wherein the at least one scraper blade extends at least in sections in a spiral or helical shape about an axis of rotation of the respective shaft insert.

24. The device according to claim 23, wherein, as viewed in a circumferential direction around a radial center of the furnace shaft, the gap width varies.

25. The device according to claim 14, wherein the gap width of the at least one gap varies as viewed in the conveying direction.

26. The device according to claim 14, wherein the inner wall is formed by at least one limiting element, and wherein the at least one shaft insert is made of the same material as the at least one limiting element.

27. The device according to claim 14, wherein the at least one axis of rotation coincides with the longitudinal axis.

28. The device according to claim 15, wherein the at least one shaft insert is floatingly mounted in the region of the lower end of the furnace shaft.

29. The device according to claim 16, wherein the at least one shaft insert has at most eight scraper blades.

30. The device according to claim 16, wherein the at least one shaft insert has two to four scraper blades.

31. The device according to claim 19, wherein the at least one drive means is adapted to set the rotational speed in the range from 0.125 rpm to 3 rpm.

32. The device according to claim 19, wherein the at least one drive means is adapted to set the rotational speed in the range from 0.5 rpm to 2 rpm.

33. The device according to claim 20, wherein, as seen in the conveying direction, upstream and/or downstream of the respective base body a shaft insert section tapering along the axis of rotation and away from the base body adjoins the respective base body.

34. The device according to claim 20, wherein, as seen in the conveying direction, upstream and/or downstream of the respective base body a shaft insert section tapering along the axis of rotation and away from the base body adjoins flush with the respective base body.

35. The device according to claim 22, wherein the at least one scraper blade extends parallel to the conveying direction.

36. The device according to claim 26, wherein the at least one limiting element is made of high-temperature steel.