GB714292A - A method and an electro smelter for producing porcelain enamel - Google Patents

Abstract

714,292. Glass melting furnace. THORNTON, A. A. (Ferro Enamel Corporation). March 28, 1952, No. 8013/52. Class 51 (2). [Also in Group XI] Porcelain enamel frit is produced by feeding a dry mixture of raw materials continuously in a thin layer on to the outer end of a deep bath of the mixture in a melting chamber 1 where it is heated by current passing transversely therethrough between opposed deeply immersed electrodes so that convection flow takes place in the bath due to temperature differences in vertical parts thereof, skimming back at 6 the surface of the bath as it flows to a second bath 10 which is shallow and wherein smelting is completed by passing current between three vertical electrodes B, the smelted enamel passing through a submerged passage 24 to a firing chamber 18 in which current is passed transversely through the enamel between submerged electrodes C in opposed walls, the enamel being finally delivered at 27 under fritting conditions. The group of electrodes in each chamber is supplied 'rom a separate power source The smelting chamber 10 is at a higher temperature than the melting chamber 1. The three electrodes B in the smelting chamber are equi-distant from one another so that a hot spot is created in the enamel at the centre between the electrodes thereby causing a circulation of the enamel. The smelting chamber 10 has adjacent the firing chamber a chimney 15, which draws gases through a passage 25 from the firing zone and tends to draw hot gases from the me'ting and smelting zone in the direction of flow of the enamel. The skimmer 6 is water-cooled. The wall 17 of the melting chamber slopes up to the smelting chamber 10. The electrodes A, C are metal plates on opposed walls, through which water-cooled contact arms pass. The electrodes should be of material lower in the electromotive series than the metals the oxides of which are in the raw batch. Graphite electrodes may be used, and if the batch contains much zirconium, the electrodes may be of molybdenum. Specification 683,701, [Group XI], is referred to.