Patent GB-783534-A (GB)
Title: Improvements in or relating to the separation of metallic halides
Inventor: HAYDEN JOHN
IPC: C22B34/12
Filed: 1954-08-06
Abstract: <PICT:0783534/III/1> Gases resulting from the chlorination of titanium bearing materials are cooled to a temperature sufficient for the condensation of those components of the gases which condense as a solid (ferric chloride), by passing the gases through a chamber containing a plurality of substantially horizontal tubes internally-cooled such that their external surfaces are at a temperature above the titanium tetrachloride dew point but low enough to condense the solidforming component, the surfaces of the tubes being cleansed from solid deposits by dropping shot through the chamber periodically or continuously.  As shown in the Figure, chlorination gases are fed through port 27 to a vessel 11 provided with horizontal tubes 12 cooled by a coolant entering at 14 and leaving at 16, the cooled gases being discharged at 30.  A shot feeding distributer 20 is arranged at the top of the vessel 11 and is fed with particles of iron or other metal or ceramic heavy bodies in the form of spherical or irregular shaped bodies one-eighth to one-half inch in diameter. In falling through the chamber the shot dislodges the condensed solid from the tubes and carries it via a discharge port 31 to a vibrating screen 33 where the ferric chloride is separated from the shot and collected in an air-tight vessel 36. The shot leaving the screen through line 38 is passed to a venturi section 40 where it is entrained in a stream of air or other gas and delivered through pipe 43 to a shot storage vessel 44 from which it is fed to the hopper 24 of the shot storage device after separation from the air which is vented at 45.  A dry air purge is provided at points 34 and 37 to prevent any titanium tetrachloride fumes from entering the ferric chloride receptacle 36.  The chlorination gases normally consisting of titanium tetrachloride, ferric chloride and chromium, zirconium, vanadium and silicon chlorides at a temperature of 900 DEG  to 1100 DEG  C. are preferably freed from entrained solids and cooled to 250 DEG  to 300 DEG  C. before passing to the cooler of the present invention.  Such initial cooling may be effected by externally or internally cooled vessels or by the direct injection of liquids such as titanium tetrachloride or ferric chloride or the injection of cold inert, preferably recycled, gases. The chlorination gases are then cooled to a temperature above the dew point of titanium tetrachloride, (e.g. 150-170 DEG  C.), to deposit ferric chloride. The preferred temperature of the external surface of the cooling tubes is 70 DEG  to 130 DEG  C. and the cooling may be effected by passing air at 90 DEG  to 110 DEG C. through the tubes at a speed of 25 feet per second.  The cooling tubes are preferably arranged in layers one above the other in parallel but staggered positions or alternatively alternate layers may be at right angles to each other.  The tubes may be slightly inclined, for example a drop of four inches in five feet.  According to an example, gases from the chlorination of rutile were chilled in a primary cooler by liquid titanium tetrachlorde to a temperature of 305 DEG  C. before passing to the cooling plant of the invention which was operated to cool the gases to 150 DEG  C. to condense the ferric chloride, by air cooling the tubes to a temperature of 95 DEG  to 110 DEG  C.  After three hours operation the temperature of the effluent chlorination gas stream had risen to 160 DEG  C., with a corresponding drop in the coolant air stream exit temperature, whereupon shot was circulated over the tubes at a rate of 20 to 30 pounds per minute for ten minutes, after which the heat transfer conditions were restored to their former state; 30 per cent of the ferric chloride content of the chlorination gases were removed and collected in vessels 36, the remainder being entrained in the gases leaving through port 30.