Steel making plant with electric arc furnace

A steel making plant comprising an electric arc furnace and a fume collection and treatment system for collecting and treating the gaseous emissions produced by said steel making plant, wherein said fume collection and treatment system comprises:

• a first primary suction line fluidically connected to the electric arc furnace to suck fumes generated in said electric arc furnace;
• a secondary suction line configured for ventilating an environment surrounding the electric arc furnace by at least one suction hood;
• at least one filtration apparatus configured for filtering emissions collected by said fume collection and treatment system before discharge of the emissions into the atmosphere;
• and
• a containment casing configured to close a connection zone between the continuous charging system and the electric arc furnace, wherein said fume collection and treatment system comprises a sealing suction line which is fluidically connected to said containment casing to suck air infiltrating inside said containment casing, said sealing suction line flowing into the secondary suction line or directly into the first primary suction line in the section between the denox apparatus and the filtration apparatus, wherein the sealing suction line comprises at least one fan, actuation of which is controlled depending on a pressure inside the containment casing, measured by at least one pressure sensor;
• wherein the electric arc furnace is fed by a continuous charging system and wherein along said first primary suction line, starting from the electric arc furnace a fume cooling apparatus, a dust collecting device and a denox selective catalytic reduction apparatus are arranged in sequence, and wherein the secondary suction line flows into the first primary suction line downstream of the denox selective catalytic reduction apparatus and upstream of said at least one filtration apparatus.

A method of collecting and treating fumes generated by a steel making plant comprising an electric arc furnace and a fume collection and treatment system for collecting and treating gaseous emissions produced by said steel making plant, wherein said fume collection and treatment system comprises:

• a first primary suction line fluidically connected to the electric arc furnace to suck fumes generated in said electric arc furnace;
• a secondary suction line configured for ventilating an environment surrounding the electric arc furnace by at least one suction hood;
• and
• at least one filtration apparatus configured for filtering emissions collected by said fume collection and treatment system before discharge of the emissions into the atmosphere, wherein said method comprises:
• preventing direct emitting of fumes into the environment from the electric arc furnace during furnace charging phases by a continuous charging system so that air sucked by the secondary suction line is substantially uncontaminated by fumes coming directly from the electric arc furnace;
• and
• treating the fumes collected by the first primary suction line in a denox selective catalytic reduction apparatus before sending the fumes to the filtration apparatus together with the fumes collected by the secondary suction line, so as not to dilute and cool the fumes sucked from the electric arc furnace with the fumes sucked by the secondary suction line before treating the fumes in the denox apparatus,
• wherein prior to treating the fumes collected by the first primary suction line in the denox catalytic reduction apparatus said fumes are freed from dust in a dust collecting device and are cooled in a fume cooling apparatus, so as to bring a temperature of said fumes within a predefined temperature range according to operating requirements of the denox apparatus;
• and
• wherein during tapping phases of molten steel from the electric arc furnace the fumes collected by the first primary suction line are sent to the filtration apparatus by-passing the denox selective catalytic reduction apparatus, so as not to send to the denox selective catalytic reduction apparatus cold fumes having temperatures below a predefined temperature range according to the operating requirements of the denox apparatus.