Abstract: A plasma arc torch that is capable of operating in a non-transferred arc mode and a transferred arc mode, and that is intended for use for use with a plasma arc treatment system. The plasma arc torch includes an electrode, a plasma gas ring and a nozzle. At least one power supply within the plasma arc treatment system is connected to the electrode, the nozzle and a workpiece. While the torch operates in a non-transferred arc mode, the non-transferred arc heats gas supplied by the plasma gas ring to create plasma gas that heats the workpiece to raise its conductivity. Once the workpiece is at an appropriately conductive level, the arc is automatically transferred since the ground point can now be found.

Abstract: A pour throat nozzle for a plasma arc centrifugal treatment system includes a substantially cylindrical throat section, with a generally arch-shaped, downwardly-facing surface at smaller radius extending above the plane of the bottom of the throat section, and with this connecting to a generally cylindrical section extending below the aforesaid plane at an inside radius much larger than the radius of the throat section. Furthermore, a method of reforming an orifice of a pour throat in a PACT system centrifuge includes adding ceramic material to the melt, heating and mixing the ceramic material with the melt, then slowing rotation of the centrifuge so that the mix pours into the inlet orifice of the nozzle.

Abstract: Specialty metals and alloys are melted in a crucible typically holding no more than about 100 lbs. of the metal and disposed in a furnace the interior of which is filled with a desired, e.g. inert, gas and subjected to a vacuum in the range of about 5% to 32% of atmospheric pressure. For special circumstances, it would be possible to start in the specified pressure range and then increase the melt chamber pressure to atmospheric or above. The vacuum permits the initiation and formation of long electric discharge arcs between the electrode of an immovable plasma torch mounted to the furnace and the inside of the crucible to provide enough space for charging of the crucible with fresh metal laterally through a charge opening in the upright side wall of the furnace and a vacuum chamber operatively connected with the charge opening.