Melting method in an electric arc furnace and corresponding apparatus
AssigneesDanieli Automation S.P.A., Danieli & C. Officine Meccaniche SpA
InventorsDamiano Patrizio, Antonello Mordeglia
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Abstract
A melting method including a step of loading solid metal material into an electric furnace, a step of generating an electric arc between at least one electrode and the metal material, a step of perforating the metal material during which said electrode is moved through said metal material, a step of melting the solid metal material in order to obtain a molten material, a step of refining said molten material by adding reaction compounds. At least one of said steps includes regulating the electric parameters of the electric arc.
Claims11
A melting method comprising:
- a step of loading solid metal material into an electric furnace;
- a step of generating an electric arc between at least one electrode and the metal material;
- a step of perforating the metal material during which said electrode is moved through said metal material;
- a step of melting the solid metal material in order to obtain a molten material, said melting step providing to keep an electric power current of said electric arc substantially constant over time at a first current value;
- a step of refining said molten material by adding reaction compounds,
- wherein the electric power supply to said electric furnace provides the transformation, with at least one transformer, of a mains alternating voltage and a mains alternating current into a base alternating voltage and a base alternating current;
- rectifying said base voltage and base current with rectifiers in order to obtain a direct electric voltage and current;
- converting, with converters, said direct voltage and electric current into a power voltage and power current;
- wherein during said refining step includes increasing the electric power current of said electric arc to a second current value comprised between 1.04 and 1.2 times the first current value, and in that the rectifiers are connected to the converters by at least one intermediate circuit which works in direct current, wherein the intermediate circuit stores electrical energy continuously and generates a separation between the electrodes and the rectifiers, and therefore with the mains electric network.
A melting apparatus comprising an electric arc furnace into which metal material is introduced and provided with at least one electrode configured to generate an electric arc toward said metal material, and a command and control unit configured to regulate at least an electric power current of said electric arc, the apparatus further comprising a transformer connected to an electric network to supply a mains alternating voltage and a mains alternating current, said transformer being configured to transform said mains voltage and said mains current into an alternating base voltage and base current respectively;
- a plurality of rectifiers connected to the transformer and configured to transform said base voltage and said base current into direct voltage and electric current;
- a plurality of converters connected to said rectifiers and configured to convert direct voltage and current into an alternating power voltage and current, comprising a regulation device configured to regulate at least said electric power current of said electric arc during at least a melting step and a refining step and so that said power current is kept at a first current value during said melting step, and during said refining step at a second current value, comprised between 1.04 and 1.2 times the first current value, and in that the apparatus further comprises at least one intermediate circuit, which connects the rectifiers to the converters, and works in direct current, wherein the intermediate circuit is configured to store electric energy continuously and to generate a separation between the electrodes and the rectifiers, and therefore with the mains electric network.
Dependencies are inferred from the claim text.