Patent GB-1097764-A (GB)
Title: Oxide process
Inventor: HERRIMAN JOHN DENNIS
IPC: C01F7/302
Filed: 1965-03-18
Abstract: In the production of the oxides of metals, e.g. Ti, Zr, Al, Fe, and of silicon by a vapour phase oxidation of an appropriate halide, a primary stream of gas which may comprise one of the reactants or an inert gas is heated to a high temperature by means of an electric arc, and into this heated stream there is introduced at least one secondary gas comprising oxidizing gas and/or metal or silicon halide, the secondary gas being introduced via an injection device comprising a plurality of inlets from a common supply manifold in such a manner that the secondary gas cools the material forming the <PICT:1097764/C1/1> <PICT:1097764/C1/2> wall of the injection device and is thereby heated before passing into the primary gas stream. Preferably, the injection device surrounds the primary gas stream and the secondary gas is fed through a plurality of inlets spaced around the inner surface of the injection device.  The inlets may be evenly spaced, e.g. at a frequency of one inlet/inch.  The electric-arc heating device and the injection device are preferably adjacent to each other, the gases passing through an orifice in the heating device directly into the injection device.  As shown in Fig. 1, the heated gas stream from the electric arc (not shown) enters chamber 2 from orifice 1 and the secondary gas stream enters via annular channels 5 and 6 cut in the chamber wall through inlets 7 and 8.  In Fig. 2 (not shown), channels 5 and 6 are replaced by perforated annular pipes. In Fig. 3, the injection device comprises a series of centrally perforated discs 25, 26 and 27 spaced by spacing washers 28, 29 so as to form a series of annular slits to which secondary gas is fed from manifolds 32 and 34 by perforations 33 and 35. In Fig. 4 (not shown), the degree of heat exchange is improved by replacing solid discs 25 and 26 with hollow annuli, the hollow regions being fitted with baffles so that the secondary gas follows a tortuous path to the injection slits.  In Fig. 5, the exit of the electric arc device 51 is cooled by the admission of gas unreactive with the primary stream through tube 65 into annular slit 64.  Similarly, the exit end of the injection device may be cooled by a fluid passed through inlet 61 and hollow annulus 60 and out through tube 62. Annulus 60 is spaced from the exit by heat resisting washer 63.  In Fig. 6 (not shown), annulus 60 may be perforated on the wall spaced from the exit of the injection device so that additional reactant may be used as cooling fluid and enters chamber 53 parallel to the walls thereof. In the process of the invention the reaction zone may have a temperature of 600 DEG  C., preferably 800 DEG  C., and the wall of the injection device adjacent the reaction zone is at 500 DEG  C., preferably 250 DEG  C.  The primary gas is at a temperature of at least 2000 DEG  C. when it enters the reaction zone, and its energy content is at least 10 kilocalories/gm. mole in excess of that required to heat the gas to 1000 DEG  C.  The electric-arc utilized for heating the primary gas-stream may be generated by passing an A.C. or D.C. current between electrodes, or it may be a gas plasma formed by inductively coupling the gas to an oscillatory current having a frequency from 10 kilocycles to 25 megacycles per second. The preferred halides are TiCl4, ZrCl4, AlCl3, FeCl3 and SiCl4 with the oxidizing gas preferably comprising free oxygen.