Abstract: The present invention relates to a vitrification process for a pulverulent material and an apparatus for implementing said process. The process consists in introducing the pulverulent material into the fusion area of a furnace via injection means, where it is melted by means of at least one plasma torch to obtain a melt, and where the melt is removed from the furnace via a casting zone, the material being introduced laterally into the fusion zone in a direction comprising a horizontal component, and the melt being removed from the furnace by overflowing via the said casting zone, more or less along said horizontal component and away from the means for injecting the material into the furnace, in relation to the fusion zone.

Abstract: The present invention concerns a plasma torch of the type including:two tubular and axially spaced coaxial electrodes (5 and 6), each electrode being arranged in a support (3 and 4) in which a cooling circuit (8 and 9) of the corresponding electrode is fitted; anda passageway for injecting a plasmagene gas between said electrodes, said passageway including a revolution piece (17) coaxial with said electrodes and defining with the latter and their supports a chamber (18) into which the plasmagene gas is injected via transverse orifices (17B) provided in the piece.According to the invention, the revolution piece (17) is not provided with internal cooling means.

Abstract: A plasma torch includes two tubular coaxial electrodes, at least one of which is axially movable between an operating position in which the movable electrode is spaced from the other electrode and an initiating position in which the movable electrode is in contact with the other electrode, thus establishing an electric short circuit so as to generate an electric arc upon rupture of the electric short circuit hen the mobile electrode is brought back to its operating position. Each electrode is contained in a support provided with a cooling circuit, through which a cooling fluid circulates. The cooling circuit associated with the movable electrode is provided with a seal which permits the electrode to be moved without creating any leaks in the cooling circuit.

Abstract: This invention relates to a plasma torch and a first and second electrode for use in a plasma torch. Each electrode includes a tubular intermediate part which is intended to come into contact with the arc feet and a pair of end parts which are intended to facilitate connection of the electrode to the other parts of the torch. Each electrode is disposed within an enclosed fluid circulation chamber within which a cooling fluid circulates. The intermediate and end parts of each electrode are at least ten millimeters thick. The individual parts of each electrode are connected together by a moisture-impervious, disassemblable, mechanical assembly which prevents the cooling fluid from coming in contact with the interior of the electrodes.

Abstract: The invention concerns plasma torches comprising an upstream electrode (12), a downstream electrode (11), a chamber (15) for the injection of plasma producing gas, a priming electrode (13) and optionally a magnetic field coil (14), in which the upstream root of the arc is displaced on the upstream electrode. According to the invention, in order to control a continuous or reciprocating and/or an oscillatory translation, the field coil is supplied with a variable direct current, if need be a pulsatory undulatory current, and/or a diffuser is placed at the inner end of the upstream electrode which is supplied with a modulated flow of gas which it causes to whirl. Application in high power plasma torches for regularizing and rendering uniform the wear of the electrodes so as to prolong the life thereof.

Abstract: A multi-layer refractory structure is provided capable of withstanding high temperatures of the order of 2000.degree. C. to 2500.degree. C. for hundreds of hours. This structure comprises at least two layers, the first of which, subjected directly to said high temperatures and formed by a simple or composite metal oxide or a zirconate, has a thickness between about 1 mm and 4 mm and a specific gravity between about 2.2 and 4.8 and the second layer of which, which serves as support for said first layer, is of the same nature as this latter and has a thickness between about 5 mm and 12 mm and a specific gravity between about 2.2 and 4.2.

Abstract: Method for heating the reducing gas of a blast furnace by means of a plasma generator. The reducing gas flows through a pipe into which issues the nozzle of the plasma generator. The pipe leads towards a tuyere of injection into the blast furnace, and the axis of said nozzle converging towards that of the pipe. The method is characterized in that the acute angle A between the axis of the nozzle and the axis of the pipe is at the most equal to 50.degree., in that the distance 1 separating the point of intersection of the axis of the pipe with the axis of the nozzle from the center of the outlet orifice of the nozzle is at the most equal toD/2sinA,D being the inner diameter of the reducing gas inlet pipe, and in that the ratioD/d,in which d is the inner diameter of the outlet orifice of the nozzle is at least equal to 1.5. The object of the method is to eliminate wear of the reducing gas pipe by means of the jet of plasma.