Abstract: A method is described for heating an electrolytic cell used for the production of metal, e.g., aluminum, by electrolysis of a molten electrolyte which contains solid electrolyte between adjacent surfaces of the anode and cathode of the cell. In the described method, holes are drilled in the solid electrolyte, e.g., to the floor of the cell, to provide space for supporting blocks. The holes are spaced a predetermined distance apart to position at least one anode between them. Supporting blocks with a length sufficient to extend from the floor to at least the level of the solid electrolyte beneath the anode are placed in the holes and a resistance heater, preferably one having a positive change in resistivity with temperature, is disposed between the supporting blocks at least one of which is electrically conductive.

Abstract: A method is described for controllably heating an electrolytic cell used for the production of metal, e.g., aluminum, from a compound of the metal, e.g., alumina, to a desired temperature. The method is especially applicable to electrolytic cells which have refractory hard metal articles, e.g., Group 4b metal diboride articles, as internal elements of the cell. The electrolytic cell is brought to the desired temperature, e.g., substantially operating temperature, from ambient temperature by placing a resistance heater having a positive change in resistivity with temperature within the cell and passing current through the heater. Typically, a plurality of heaters is used. In one embodiment, the heaters are placed close to but spaced from the refractory hard metal articles. The heaters are usually connected in parallel to a source of electrical power and in a preferred embodiment are in electrical contact with the cathode and anode of the electrolytic cell.

Abstract: Helical flow of hot plasma gas, e.g., hydrogen gas, produced by a gas vortex stabilized plasma arc is cancelled by introducing attenuating gas, e.g., hydrogen gas, into the hot plasma gas in a manner such that the attenuating gas assumes a vortical direction opposite to the helical flow of the hot plasma gas. The resulting gas stream is well-collimated. The well-collimated plasma gas stream is used in the preparation of finely-divided refractory metal and metalloid carbides, borides, nitrides, silicides and sulfides. Reactants for the preparation of the aforementioned refractory powders are introduced into the collimated plasma gas stream. The reaction is conducted in the gas phase within a reactor and solid, finely-divided refractory powder removed from the reactor.