A process is described wherein a material, such as particulate metal oxid is treated with an arc discharge plasma under vacuum in the presence of a magnetic field running axially between the arc electrodes, wherein the plasma rotates symmetrically about a middle magnetic field, under conditions such that in a region the product of the electron gyration frequency .OMEGA. and time .tau., within which the average electron transmits its impulse to the plasma ions, is .OMEGA..tau. > 1 at about the middle of the magnetic field, and treated material, i.e., reduced metal, is recovered radially outside the region. Apparatus is described, for carrying out the process, including a discharge vessel, two spaced annular electrodes arranged symmetrically to the axis of the vessel, a magnetic coil enclosing coaxially the space between the electrodes, and means to introduce material axially through one electrode into the space.
A heat treating apparatus including a crucible to contain molten metal, at least one plasma ejecting nozzle which is constructed so as to generate a plasma jet and is secured with respect to the crucible around the central axis of it and a magnetic field generating means to generate a magnetic field interacting with the plasma jet and deflecting it.
Iron ore and a mixture of methane and hydrogen are fed into a plasma arc torch and form a swirling film of material that slowly descends the walls of the torch. The ore is reduced in the torch, and metallic iron is collected in a crucible below the torch.
A plasma arc furnace in which an expanded plasma column is generated between at least one orbiting electrode moving in a substantially circular path and a stationary electrode. The orbiting electrode is directed towards the orbital axis so as to generate a plasma column having a portion of generally inverted conical shape in the vicinity of the orbiting electrode and feedstock is introduced into the upper end of the plasma column. The orbiting electrode may be directed across the orbital axis whereby the generated plasma column is in the form of two generally conical portions meeting at a common apex.
Free flowing powders such as for flame spray applications are produced by agglomerating finely divided material, classifying the agglomerates to obtain a desired size range, entraining the agglomerates in a carrier gas, feeding the agglomerates through a high temperature plasma reactor to cause at least partial melting of the particles, and collecting the particles in a cooling chamber containing a protective gaseous atmosphere, wherein the particles are solidified.
A method for heat treatment, i.e, annealing or softening, of metal materials in the nature of coiled rod, wire, strip sheet, and the like, utilizes a conventional batch type furnace with a controlled atmosphere heated by an electric arc source, i.e., a plasma generator.
