Abstract: An assembly for the recovery of aluminum metal from aluminum dross comprising a rotary furnace, a plasma arc torch, and a supervisory control system for tying together and automatically controlling the operation of the rotary furnace and plasma arc torch is described. The invention provides recovery of aluminum metal from dross in an efficient and economical process.

Abstract: An apparatus for starting and maintaining a plasma arc is disclosed, which comprises a plasma arc torch composed of a rear electrode and a front tubular member, with the tubular member acting as a collimator in transfer arc operation or as an electrode in non-transfer arc operation. The power circuit includes a main DC power supply, an electrical pulse generator in series with the plasma torch, and a protective capacitor connected between the main power supply and pulse generator. To initiate the arc, a high voltage pulse is generated by the pulse generator, which has sufficient power to strike an arc which extends from the rear electrode to an external workpiece in the case of transfer arc operation. The main power supply is used only to maintain the established arc, and thus may have a relatively small voltage capacity.

Abstract: A plasma arc heating apparatus is disclosed which is adapted for heating large quantities of air for commercial and industrial uses, and which comprises a housing including an elongate heating chamber, a tubular front electrode mounted at one end of the housing, and a plasma arc torch mounted at the other end of the housing. The torch is mounted for movement toward and away from the front electrode and a power supply system is provided for establishing an arc which extends from a rear electrode in the torch through the heating chamber and to the front electrode at the opposite end of the housing. Structure are also provided for introducing a gas to be heated into the chamber between the torch and the front electrode, and such that the gas is heated by the arc and flows outwardly through the front electrode.

Abstract: A plasma arc torch is disclosed which comprises front and rear coaxially aligned electrodes, and vortex generator for generating a vortical flow of gas, such as air, between the two electrodes. A power supply system is operatively connected to the two electrodes for generating an arc which is adapted to extend axially from the rear electrode through the vortical flow of gas and to an attachment point located on the front electrode. The bore of the front electrode includes a cup-shaped outer end portion which defines a forwardly facing radial shoulder. By proper coordination of the power and gas delivery systems, the arc may be made to attach to the radial shoulder of the front electrode, and such that the erosion of the front electrode occurs along an axial direction rather than a radial direction.

Abstract: A plasma arc torch is disclosed which has the ability to be configured for operation in either the transfer arc mode or the non-transfer arc mode. The torch includes a rear housing section which mounts a rear electrode, a gas vortex generator, and releasable mounting means. The releasable mounting means is adapted to mount either an electrode assembly for operation of the torch in the non-transfer arc mode, or a collimating nozzle assembly for operation in the transfer arc mode. The torch also includes a coolant passageway which is constructed and arranged so as to mate with cooperating passageways in either the electrode assembly or the collimating nozzle assembly, for removing heat from the internal components of the torch.

Abstract: A plasma arc torch is disclosed which comprises a rear electrode, an aligned front tubular electrode, and vortex generating means for generating a vortical flow of gas between the rear and front electrodes. The torch further includes an inner shroud which is electrically connected to the front electrode, and an outer shroud which is electrically insulated from both of the electrodes and from the inner shroud. A power supply is operatively connected to the rear electrode and the outer shroud, which is adapted to generate an arc which extends axially from the rear electrode through the vortical flow of gas and through the front electrode, with the front electrode and inner shroud thereby electrically "floating" with respect to the power supply. A water cooling system is also provided which includes a coolant flow path which extends serially from the rear electrode through an insulator to the front electrode, then to the inner shroud, and then through an insulator to the outer shroud.