The method for adjusting the impedance of one or more phases of a secondary circuit of an electric furnace, in order to limit the unbalance between the phases themselves comprises the transformer (31), a variable impedance secondary circuit for one or more phases (F1, F2, F3), the rigid and fixed interconnection (32) for each phase (F1, F2, F3) connected to the transformer, the flexible cables (33) connected by means of the proximal end to the fixed interconnection (32), the electrode holding arms (34) connected to the distal end of the flexible cables (33), the conductive electrodes (35) fixed to the respective electrode holding arms (34). The rigid and fixed interconnection (32) of a phase (F1, F2, F3) comprises at least one turn (11), wherein the impedance is either continuously or discreetly variable in order to obtain the desired impedance value.

A control device of an electric arc furnace that controls, in a melting phase and subsequently in a flat bath phase, an energy supply device with first control values (A1), such that the energy supply device supplies electrical energy to electrodes of the electric arc furnace via a furnace transformer. The control device, in both phases, further controls a positioning device with second control values (A2), such that said positioning device positions the electrodes relative to the unmolten steel-containing material in the melting phase and relative to the molten steel in the flat bath phase. As a result, electric arcs are formed in both phases, by means of which the steel-containing material is melted or the molten steel is further heated.

A control device of an electric arc furnace that controls, in a melting phase and subsequently in a flat bath phase, an energy supply device with first control values (A1), such that the energy supply device supplies electrical energy to electrodes of the electric arc furnace via a furnace transformer. The control device, in both phases, further controls a positioning device with second control values (A2), such that said positioning device positions the electrodes relative to the unmolten steel-containing material in the melting phase and relative to the molten steel in the flat bath phase. As a result, electric arcs are formed in both phases, by means of which the steel-containing material is melted or the molten steel is further heated.

An inductively coupled plasma device includes a rotary furnace tube and an inductively coupled plasma source. The rotary furnace tube has a first end, a second end and a longitudinal axis. In a first embodiment, the inductively coupled plasma source is disposed proximate to the first end of the rotary furnace tube and is aligned with the longitudinal axis of the rotary furnace such that the inductively coupled plasma source discharges a plasma into the rotary furnace tube. In a second embodiment, the inductively coupled plasma source is a ground electrode disposed within and aligned with the longitudinal axis of the rotary furnace tube, and a second electromagnetic radiation source disposed around or within the rotary furnace tube that generates a wave energy. The inductively coupled plasma source discharges a plasma within the rotary furnace tube.

An inductively coupled plasma device includes a rotary furnace tube and an inductively coupled plasma source. The rotary furnace tube has a first end, a second end and a longitudinal axis. In a first embodiment, the inductively coupled plasma source is disposed proximate to the first end of the rotary furnace tube and is aligned with the longitudinal axis of the rotary furnace such that the inductively coupled plasma source discharges a plasma into the rotary furnace tube. In a second embodiment, the inductively coupled plasma source is a ground electrode disposed within and aligned with the longitudinal axis of the rotary furnace tube, and a second electromagnetic radiation source disposed around or within the rotary furnace tube that generates a wave energy. The inductively coupled plasma source discharges a plasma within the rotary furnace tube.

An example embodiment of the present invention provides a system for preheating ferromagnetic scrap. The system can include a preheating unit that is configured to hold ferromagnetic scrap and to receive hot gases. The preheating unit may include a removable cover that can include an electrical magnet system. The electrical magnet system can comprise an electrical magnet, a lifting device configured to lower and raise the electrical magnet, a power system configured to provide electrical power to the electrical magnet, and an electrical control system configured to operate the magnet. A hot gases cleaning system may be fluidly connected to the preheating unit.

An example embodiment of the present invention provides a system for preheating ferromagnetic scrap. The system can include a preheating unit that is configured to hold ferromagnetic scrap and to receive hot gases. The preheating unit may include a removable cover that can include an electrical magnet system. The electrical magnet system can comprise an electrical magnet, a lifting device configured to lower and raise the electrical magnet, a power system configured to provide electrical power to the electrical magnet, and an electrical control system configured to operate the magnet. A hot gases cleaning system may be fluidly connected to the preheating unit.

A friction stir welding method for bonding a to-be bonded material, includes: a step of supplying nitrogen and introducing nitrogen into the to-be bonded material while melting the to-be bonded material; and a step of friction stir welding a portion of the non-bonded material in which the nitrogen is introduced. A friction stirring device for bonding a to-be bonded material, includes: a heating source for melting the to-be bonded material; a nitrogen supply source for supplying nitrogen to a melted portion of the to-be bonded material and introducing nitrogen into the to-be bonded material; and a friction stir tool for friction stir welding a portion of the non-bonded material in which the nitrogen is introduced.

A friction stir welding method for bonding a to-be bonded material, includes: a step of supplying nitrogen and introducing nitrogen into the to-be bonded material while melting the to-be bonded material; and a step of friction stir welding a portion of the non-bonded material in which the nitrogen is introduced. A friction stirring device for bonding a to-be bonded material, includes: a heating source for melting the to-be bonded material; a nitrogen supply source for supplying nitrogen to a melted portion of the to-be bonded material and introducing nitrogen into the to-be bonded material; and a friction stir tool for friction stir welding a portion of the non-bonded material in which the nitrogen is introduced.

A control system for a vacuum arc remelting (VAR) process for a metal includes a direct current (DC) power source, a ram drive, voltage drip short sensor, and a controller, which includes a processor. The drip short sensor may be configured to measure a drip short frequency of the electric arc over a period of time. The controller is configured to determine a real time arc gap length between the electrode tip and the melt pool based on a correlation between the drip short frequency and arc gap length. The controller is further configured to control power input to the electrode by the DC power supply by determining an input power level to input to the electrode based on the real time arc gap length, the input power level configured to generate a desired arc gap length, by the DC power supply, at the input power level.