Abstract: A system and method for melting a raw material. The raw material is fed into an electrically conductive vessel. A plasma arc torch melts at least some of the raw material within the vessel to thereby create a molten material. An inductor, physically disposed adjacent the vessel, and electrically disposed in series with the vessel in operation, effects electromagnetic stirring of the molten material by interacting with the current of the plasma arc torch.

Abstract: A method and a system for forming a solid casting. A material is fed into a mold having a retractable bottom. A first portion of the material at a first, lower position within the mold is allowed to solidify to thereby form a portion of the casting. The retractable bottom is withdrawn downwards at a withdrawal rate. A second portion of the material at a second, upper position within the mold is maintained in a liquid state by application of heat thereto, using a plasma arc generated by a plasma arc torch. A voltage of the plasma arc is measured, and the withdrawal rate of the retractable bottom is controlled based on the voltage of the plasma arc.

Abstract: A method and a system for forming a solid casting. A material is fed into a mold having a retractable bottom. A first portion of the material at a first, lower position within the mold is allowed to solidify to thereby form a portion of the casting. The retractable bottom is withdrawn downwards at a withdrawal rate. A second portion of the material at a second, upper position within the mold is maintained in a liquid state by application of heat thereto, using a plasma arc generated by a plasma arc torch. A voltage of the plasma arc is measured, and the withdrawal rate of the retractable bottom is controlled based on the voltage of the plasma arc.

Abstract: A system and method for melting a raw material. The raw material is fed into an electrically conductive vessel. A plasma arc torch melts at least some of the raw material within the vessel to thereby create a molten material. An inductor, physically disposed adjacent the vessel, and electrically disposed in series with the vessel in operation, effects electromagnetic stirring of the molten material by interacting with the current of the plasma arc torch.

Abstract: A plasma arc torch is disclosed which has an elongated electrode with an open front and a nozzle with a plasma discharge opening that is coaxial with the electrode. A mounting arrangement includes a ceramic ring that engages the front end of the electrode and a gas ring which concentrically surrounds the ceramic ring. A forward portion of the gas ring, the forward end of the electrode, and the nozzle define a swirl chamber of the torch, and opposing, spaced-apart concentric cylindrical surfaces of the ceramic ring and the gas ring, respectively, form an annulus which extends rearwardly from the swirl chamber. The ceramic ring closes the aft end of the annulus, and the gas ring houses a plurality of plasma gas injection ports which are located immediately forward of the aft end of the annulus.

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.

Abstract: An arc plasma torch having a tapered-bore electrode provides a long, columnar plasma arc. The torch includes a torch housing, a tapered-bore electrode, a gas-constricting nozzle, and a swirling gas flow generator.The electrode is mounted within the housing and has a closed inner end and an open outer mouth. The electrode has a longitudinally extending, tapered bore. The bore has its largest dimension at the mouth. The nozzle has a bore and is also mounted within the housing. The nozzle is in axial alignment with, forwardly spaced with respect to and insulated from, the tapered-bore electrode. The torch introduces a swirling flow of gas at a location intermediate the electrode and the gas-constricting nozzle, resulting in gas flowing past the electrode during use of the torch. In operation, an electric arc emanating from the electrode ionizes the gas flow.

Abstract: The disclosure is made for the use of a hearth for receiving metals to be melted and exposing the molten metals to the furnace atmosphere with the upper surface of the molten metal free to float impurities such as oxides, carbides, or other undesirable materials on the upper surface of the molten metal or alloy. Gas jets blow an inert gas in one direction over the upper surface of the molten metal, generally parallel to the upper surface of the molten alloy. Thus, the gas jets remove impurities from the upper surface of the molten alloy by blowing or skimming the impurities off the top of the pool toward the walls of the hearth. The preferred position of the gas jets is in the notch of the hearth over which the molten alloy flows from the main body of the hearth into a withdrawal crucible.