Electric arc furnace with alternative sources of energy and operating method for such electric furnace

Electric arc furnace with alternative sources of energy, used for melting metals, which functions with direct current or alternating current, comprising:

• a hearth and furnace sidewall to contain a bath;
• at least one upper electrode to generate an electric arc;
• at least one lance provided on the furnace sidewall to inject pure or combined oxygen above an upper level of the bath inside the furnace;
• a plurality of tuyeres provided in the hearth, each tuyere comprising a central oxygen delivery pipe having an inner diameter between 8 and 30 mm for delivery of oxidation gas so that a pressure of emission of the oxidation gas is modulated at at least above a minimum pressure according to phases of charging of the furnace, wherein the central oxygen delivery pipe has an outer surface having polygonal shape, and an outer peripheral pipe surrounding the central oxygen delivery pipe, wherein the outer peripheral pipe is a circumferential toric element, thereby forming a passage between each side of the central oxygen delivery pipe and an inner circumference of the outer peripheral pipe for conveying a cooling mixture, the cooling mixture comprising at least one cooling gas having a high cooling power and at least one diluting gas.

A method for melting metals in an electric arc furnace with alternative sources of energy, the arc furnace functioning with direct current or alternating current, comprising:

• providing metal in the furnace and containing the metal by the hearth and furnace sidewall;
• generating an electric arc within the furnace;
• injecting pure or combined oxygen into the furnace above an upper level of a metal bath therein through at least one lance provided on the furnace sidewall;
• delivering an oxidation gas into the bath through a plurality of tuyeres provided in the hearth, each tuyere comprising a central oxygen delivery pipe having an inner diameter between 8 and 30 mm for delivery of the oxidation gas so that the pressure of emission of the oxidation gas is modulated at at least above a minimum pressure according to phases of charging of the furnace;
• conveying a cooling mixture, the cooling mixture comprising at least one cooling gas having a high cooling power and at least one diluting gas, through at least one passage formed between the central oxygen delivery pipe and an outer peripheral pipe;
• reading a rate of flow of the oxidation gas to each central oxygen delivery pipe;
• and
• regulating flow rates of the at least one cooling gas and at least one diluting gas based on the flow rate of the oxidation gas.

A method for melting metals in an electric arc furnace with alternative sources of energy, the arc furnace functioning with direct current or alternating current, comprising:

• providing metal in the furnace and containing the metal by the hearth and furnace sidewall;
• generating an electric arc within the furnace;
• injecting pure or combined oxygen into the furnace above an upper level of a metal bath therein through at least one lance provided on the furnace sidewall;
• delivering an oxidation gas into the bath through a plurality of tuyeres provided in the hearth, each tuyere comprising a central oxygen delivery pipe having an inner diameter between 8 and 30 mm for delivery of the oxidation gas and an outer surface having polygonal shape so that the pressure of emission of the oxidation gas is modulated at at least above a minimum pressure according to phases of charging of the furnace;
• and
• conveying a cooling mixture, the cooling mixture comprising at least one cooling gas having a high cooling power and at least one diluting gas, through a plurality of passages formed between each outer side of the central oxygen delivery pipe and an inside of a circumferential toric outer peripheral pipe provided around the central oxygen delivery pipe.