GB871922A - Improvements in or relating to the production of fused silica - Google Patents

Abstract

871,922. Casting refractory bodies. ENGELHARD INDUSTRIES Inc. Oct. 25, 1957, No. 33406/57. Class 87(2). [Also in Groups XI and XXIII] Silica sand is continuously fused by passage over one or more electric heating resistor rods 40 protected from contact with the sand by semi-cylindrical covers 48 spaced from the rods and supported above them when the sand flows vertically down or at one side of them when the sand is moved horizontally, a support for the fused silica being simultaneously moved away from the heating zone to accommodate the fused silica. As shown the graphite resistor rods 40 are mounted at their ends on opposite walls of a furnace having a detachable bottom part 18 with walls extended up by panels 10, 12. As silica sand is added at 50 between upper partitions 54, the bottom part 18 is continuously lowered automatically at such speed that complete fusion of the silica occurs immediately after it passes over the graphite covers 48. A space 52 is formed below each resistance rod as the fused silica passes on to form a continuous block. The ends of the resistor rods 40 are threaded and screwed into recesses 28 in graphite blocks 24 to which current is supplied by leads 32 through watercooled clamps 36. A graphite collar 42 on the heating rod abuts against the end of the block 24 to protect the junction. An insulating sleeve 44 on the block 24 supports the end of the cover, which extends into a firebrick wall 20. Waste sand poured into the space between the partitions 54 and the outer furnace walls acts as heat insulation. Specification 719,393 is referred to.