Patent GB-190705764-A (GB)
Title: Process and Apparatus for Electrically Fusing, Refining, and Moulding Refractory Substances such as Quartz.
Inventor: MACKENZIE JOHN WILLIAM
Filed: 1907-03-09
Granted: 1908-04-09
Abstract: 5764. Mackenzie, J. W., [Bolle & Co., L.]. March 9. Electric furnaces.-Quartz and like refractory substances are fused, refined, and moulded by means of an electric furnace in which a carbon crucible forming one electrode is surrounded by resistance material, such as powdered carbon or graphite, and by an annular second electrode, the heating-zone being reduced during melting, for instance, by a plunger which is forced into the crucible and may be used in various ways for moulding the molten mass. In one arrangement, the crucible 3, Fig. 1, is supported by a slab 2 of magnesia, firebrick, &c., and is fitted with a removable plug 5. The plunger 8 is hollow and is adjustably supported, for instance by worm and screw geaiing 9, 10 actuated by a hand-wheel 11 and mounted on a cover 6. The cover is also adjustable on vertical guide-rails by means of chains, chain-wheels, a sbaft 14, and worm gearing 15. Indicators for showing the positions of the movable parts may be provided. The fused mass may be forced out of the melting-zone by compressed air or steam introduced through the plungers. Alternatively, it may be forced into the plunger by lowering the latter, and then may either be pushed out in the form of a cylinder through the opening in the melting-vessel by a second plunger within the first, or ejected by fluid pressure into a mould after removal from the furnace. When cylindrical rods are formed, they may be further shaped by mechanical pressure as they leave the apparatus. Alternatively, the furnace may be moved away from the plonger. The plunger may be provided with a separate heating - device. In another arrangement, the crucible 16, Fig. 2, normally rests on a removable slab 17, but can, when required, be supported by an adjustable platform 22 carried by a verticallymovable frame 21. This frame also carries a tube 18 adapted, when the frame is lowered, to prevent displacement of the resistance material. A plunger 19, perforated for the passage of air or steam, is immersed in the molten mass, which clings to it when the crucible is lowered. Moulding in this case is effected by direct pressure or by blowing, either in the melting-vessel itself or in a separate mould which is introduced by lowering the frame 21. The fused mass may be held at its ends by conical rings pressing it against the plunger. The plunger may be constructed so that moulding is effected both inside and outside it. In another furnace, the crucible is horizontal and cylindrical, and the plunger, which has a solid end or is perforated with small holes, fits closely within it and rests upon rollers. The plunger is pressed into the tube by a weighted bell-crank lever, to which it is connected by a pin-and-slot device. Two vertical tubes at the ends of the horizontal tube serve for feeding in the raw material, and are closed respectively by the plunger and by a slide geared to it, as the material is compressed. Two narrow annular outer electrodes of one polarity are employed.