Abstract: A feedback control system for the impedance control of an electric arc furnace having at least one electrode, a hydraulic electrode actuator for adjusting the electrode. The actuator is adapted to be supplied with hydraulic fluid through a control valve. The furnace further includes a controller, which is connected to the valve actuator for the control valve, and impedance signal generator for delivering impedance signals to one input of the controller and a setpoint signal generator for delivering a setpoint signal representing a desired impedance to another input of the controller.

Abstract: With a continuous casting mold, the mold side walls each are formed by a supporting wall and an internal plate fastened thereto and getting into contact with the metal melt. On the side of the internal plate facing the supporting wall parallely arranged coolant channels are provided, which are designed as slits open towards the supporting wall and whose width is smaller and whose depth is larger, than the width of the ribs located between the slits. In order to render the cooling performance particularly effective, the width of the cooling ribs is smaller than, or equal to, 13 mm and the flow speed of the coolant is adjusted such that the heat transmission coefficient alpha between the internal plate and the coolant is between 20 and 70 kW/m.sup.2 K, preferably between 25 and 50 KW/m.sup.2 K, such that the heat flow density for the internal plate is larger than the heat flow density for a smooth internal plate having no ribs.

Abstract: In an apparatus for fixing a roll ring 4 on a roll shaft 2 mounted in two parallel roll stands 1a, 1b on both sides of the roll ring, by means of a tensioning means 18 and an axially tensionable conical sleeve 8 a radial tension is generated in the roll ring 4. In addition, the conical sleeve 8 carries the roll shaft bearing 3a.To enable the axial and radial tensioning of the roll ring 4 to be adjusted simply and accurately in spite of the additional roll shaft bearing 3a, the tensioning means 18 acts on the one hand on the conical sleeve 8 via a first thrust transmitting means passing through the roll stand 1a and on the other hand on the roll ring 4 clamped between two thrust rings 22, 23 via a second thrust transmitting means passing through the roll stand, one of the two thrust transmitting means also receiving the roll shaft bearing 3a.

Abstract: There is disclosed a metallurgical vessel, such as a steelworks converter, having a refractory brick lining and a probe opening passing a wall of the vessel for introducing a measuring and/or sampling probe. In order that the probe opening will get obstructed only minimally, if at all, and possible deposits of slag will be removed easily and quickly, the probe opening is provided with a lining of graphite or a graphite/alumina mixture.

Abstract: An apparatus for hardening rails having a rail foot, a rail head, which is to be hardened, and a web between the rail foot and the rail head comprises a dip basin for receiving the rail head, a manipulator for receiving from a feeder individual consecutive rails supported at their head and foot and for dipping the head of each rail into the dip basin, and a delivery conveyor for carrying the treated rails away from the dip basin.

Abstract: The apparatus utilizes twin casting drums and a cast-on site removed from a sump formed between the two drums. The apparatus forms a completely uniform continuous metal sheet without a molten center when the sheet emerges from between the casting drums. Complete solidification of the metal sheet does not take place on a single casting drum, allowing for sheeting of substantially greater thickness to be uniformly cast.

Abstract: In the operation of a top-blowing steelmaking converter having at least one blowing lance, the distance of said lance from the surface of the molten metal bath is controlled in dependence on the sound levels of the blowing noise measured through the slag at selected frequencies. In order to minimize the risk of slopping, the actual values of the sound levels measured at predetermined frequencies are combined to form a resultant value, the difference between said resultant value and a predetermined reference value, which is associated with a sound level and indicates that slopping is likely to occur, is determined, and said difference is used as an indication of the probability of an occurrence of slopping and is compared with at least one predetermined probability limit, the distance of the blowing lance and optionally also the oxygen supply rate is corrected when said difference exceeds said probability limit.

Abstract: To produce deoxidized steel by the addition of deoxidizing agents to molten crude steel having an oxygen content of at least 200 ppm and the subsequent addition of alloying agents, the deoxidation is realized at least partially under the formation of liquid deoxidation products by the simultaneous addition of the two deoxidizing agents FeSi and FeMn. The method according to the invention ensures a great analytical precision of the steel and is not limited to the production of certain steels.

Abstract: To permit a continuous production of foamed blast furnace slag, a revolving conveyor is provided, which is continuously supplied with a stream of slag from a slag feeder in a trough which comprises a bottom and side walls rising from the bottom. Adjacent to the slag feeder, stationary tubular lances extend in said trough closely above the bottom in the direction of conveyance and are formed in a predetermined length portion with radial outlet orifices for a discharge of water into said trough.

Abstract: When continuously casting a thin strip, metal melt is cast onto the drum surface of a first casting drum. A casting gap is formed by a second casting drum spaced apart with its drum surface from the first casting drum by the thickness of the strip. Strand shells form on the drum surfaces of the first and second casting drums. In order to enable the casting of strips having different thicknesses, a sump is formed at a distance from the cast-on site of metal melt on the drum surface of the first casting drum. Between the sump and the cast-on site on the drum surface of the first casting drum, a strand shell of a predetermied thickness is formed. The casting gap is adjusted in a position on the circumference of the first casting drum such that the two strand shells formed on the drum surfaces in terms of their maximum thickness, in total, correspond at least the thickness of the cast strip.

Abstract: There is disclosed a continuous casting mold for casting billets and blooms including a stirring means to produce a rotating electromagnetic field or force. It is sought to use a continuous casting mold of this type facultatively with free-stream casting or with immerged-tube casting. The continuous casting mold includes at least one stirring means which is displaceable over the height of the continuous casting mold and is fixable in different height positions.

Abstract: In a combined process for the thermal and chemical treatment of lignocellulose-containing biomass and for the production of furfural, biomass is supplied to a cooker in batches, is heated in the cooker under the addition of cooking liquor, and cellulose or pre-treated biomass is withdrawn from the cooker in batches. In order to guarantee a high yield of furfural, cooking liquor is withdrawn from the cooker during the heating phase and is fed to a furfural production plant, and the cooking liquor at least largely freed from pentoses and furfural is returned to the cooker.