| abstract |
1390351 Arc furnaces TETRONICS RESEARCH & DEVELOPMENT CO Ltd 7 Feb 1972 [16 Feb 1971 (2) 18 Aug 1971] 4789/71 4790/71 and 38855/71 Heading F4B [Also in Division H5] In order to produce an expanded arc in a plasma furnace, a rotating electrode, e.g. plasma torch 1 is rotated at for example speeds at and above 300 r.p.m. by mounting it within a rotor 3 secured to a refractory member 8, the rotor and member 8 being rotated by a drive chain 5 from motor 6. The torch is arranged to slide in the bore formed by bush 2, its distance from a fixed annular electrode 12 being adjusted hydraulically by a piston rod 18 in cylinder 17. Universal couplings 21 link the rod to the torch. An annular disc 10 ensures even spread of material to be processed which is introduced between the furnace body and the member 8. The annular electrode 12 may be segmented, Fig. 5 (not shown), and liquid cooled, and oils, &c. may be added to the flame through holes in the electrode. The product is collected in a single, Fig. 1 (not shown), or double crucible (Fig. 3). Fig. 3 has tapping means 16, 16A, flue duct 18 and an additional duct 17 for introducing for example an oxidizing blast. The crucible walls 13, 13A are spaced from the refractory block 15 to reduce thermal shock and allow preheating. The arrangement of Fig. 3 provides a factionating device to gravity separate heavier products from lighter ones. The plasma torch and annular electrode may be replaced by other types of electrodes consumable or non-consumable. Copper cathode for copper refining may for example replace the stationary annular electrode. There may be a plurality of electrodes (stationary and rotating) and the atmosphere of the furnace may be varied. The arc may be adjusted to provide gaps in its path so as to increase turbulence. Specifications 1,390,352 and 1,390,353 disclose the invention as set out in this Specification. |