Process and equipment for the treatment of a material by means of an arc discharge plasma

Claim 1

IN A PROCESS FOR THE TREATMENT OF A METAL COMPOUND CAPABLE OF FORMING A VOLATILE METAL HALIDE, WHICH PROCESS INCLUDES THE FOLLOWING STEPS: (A) PRODUCING AN ARC DISCHARGE PLASMA IN A REGION OF A DISCHARGE VESSEL BETWEEN TWO AXIALLY SPACED ELECTRODES (B) MAINTAINING THE AVERAGE PRESSURE IN SAID REGION AT LESS THAN ONE ATMOSPHERE; (C) PRODUCING A MAGNETIC FIELD RUNNING SUBSTANTIALLY PARALLEL TO THE AXIS FORMING THE CONNECTION LINE BETWEEN SAID ELECTRODES THE VALUE OF WHICH IN AT LEAST ONE PART OF SAID REGION HAS SUCH A HIGH VALUE THAT THE PRODUCT W$ OF THE ELECTRON GYRATION FREQUENCY W IN THE PLASMA AND THE TIME $ WITHIN WHICH ON AN AVERAGE ELECTRON TRANSMITS ITS IMPULSE TO THE IONS OF THE PLASMA IS GREATER THAN 1, AND THAT THE ARC DISCHARGE PLASMA IN SAID REGION AS A WHOLE IN ITSELF ROTATES AROUND A MIDDLE MAGNETIC FIELD LINE TO WHICH THE PLASMA IS SUBSTANTIALLY SYMMETRICAL; AND (D) BRINGING SAID METAL COMPOUND INTO A PART OF SAID REGION CLOSE TO THE MID POINT OF SAID MAGNETIC FIELD UNDER SAID CONDITION OF W$ $ 1, WHEREBY SAID PLASMA EFFECTS A CHEMICAL REDUCTIN OF SAID METAL COMPOUND AND SAID REDUCED METAL COMPOUND TRAVELS TO A SPACE LYING RADIALLY OUTSIDE OF SAID REGION; WHEREIN THE IMPROVEMENT COMPRISES RECOVERING SAID REDUCED METAL COMPOUND FROM THE SPACE LYING RADIALLY OUTSIDE OF SAID REGION BY (I) INTRODUCING A HALOGEN OR HALIDE INTO SAID VESSEL AND CONTACTING SAID REDUCED METAL COMPOUND THEREWITH, WHEREBY SAID REDUCED METAL COMPOUND IS CONVERTED INTO A VAPOROUS VOLATILE METAL HALIDE, (II) REMOVING SAID VOLATILE METAL HALIDE IN VAPOR FORM FROM SAID VESSEL, AND (III) FURTHER TREATING SAID VOLATILE METAL HALIDE SUCH AS DECOMPOSING SAID VOLATILE METAL HALIDE TO OBTAIN SUBSTANTIALLY PURE METAL.