Hot Metal Production from DRI with Electric Arc Heating
AssigneesMidrex Technologies, Inc., Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
InventorsHaruyasu MICHISHITA, Koji Tokuda, Tsuyoshi Mimura, Katsuma Fujiwara
Life of this patent
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Abstract
According to embodiments, disclosed is a method and system to maintain the soft and sparse slag characteristic favorable for an electric arc to efficiently transfer the energy to molten iron with the power input per furnace area higher than 600 KW/m2 while keeping FeO amount less than 5% in the slag and carbon amount higher than 2.5% in the product hot metal at a DRI melting furnace.
Claims20
A method to maintain a soft and sparse slag characteristic favorable for an electric arc furnace to efficiently transfer energy to molten iron with a power input per furnace area higher than 600 KW/m2 while maintaining a FeO amount less than 5 wt. % in the slag and a carbon amount higher than 2.5 wt. % in a product hot metal at a direct reduced iron (DRI) melting furnace, comprising:
- providing an electric DRI melting furnace as an electric arc furnace and including a plurality of electrodes for electric arc heating;
- charging the DRI to the DRI melting furnace through a chute;
- charging lumpy carbonaceous material fed along with the DRI;
- forming a slag layer comprising slag and forming a layer of molten iron below the slag layer;
- providing at least one oxygen injection nozzle for injection of oxygen;
- injecting the oxygen into the slag layer not penetrating the slag or reaching the molten iron from the at least one oxygen injection nozzle;
- adjusting oxygen flow rate to stabilize current fluctuation for each electrode;
- discharging the slag through a slag door or a slag tap hole located at an intermediate elevation of a side wall of the DRI melting furnace;
- and
- discharging the product hot metal through a tap hole located at a bottom or lower portion of the DRI melting furnace;
- wherein the method maintains the soft and sparse slag characteristic favorable for the electric arc furnace to efficiently transfer energy to the molten iron with a power input per furnace area higher than 600 KW/m2 while maintaining the FeO amount less than 5 wt. % in the slag and the carbon amount higher than 2.5 wt. % in the product hot metal at the DRI melting furnace.
A method of producing a product hot metal from DRI using electric arc heating comprising:
- charging the DRI along with lumpy carbonaceous material to an electric DRI melting furnace through at least one chute;
- forming a slag layer comprising slag and forming a layer of molten iron below the slag layer;
- injecting oxygen into the slag layer not penetrating the slag or reaching the molten iron from the multiple injection nozzles circumferentially laid out;
- discharging the slag through a slag door or a slag tap hole located at an intermediate elevation of a side wall of the furnace;
- and
- discharging the product hot metal through a tap hole located at a bottom or lower portion of the DRI melting furnace;
- wherein the method further comprises maintaining a soft and sparse slag characteristic favorable for an electric arc to efficiently transfer energy to the molten iron with a power input per furnace area higher than 600 KW/m2 while maintaining a FeO amount less than 5 wt. % in the slag and a carbon amount higher than 2.5 wt. % in the product hot metal at the DRI melting furnace.
A system configured to maintain a soft and sparse slag characteristic favorable for an electric arc furnace to efficiently transfer energy to molten iron with a power input per furnace area higher than 600 KW/m2 while maintaining an FeO amount less than 5 wt. % in the slag and a carbon amount higher than 2.5 wt. % in a product hot metal at direct reduced iron (DRI) melting furnace, the system comprising:
- an electric DRI melting furnace as an electric arc furnace and including a plurality of electrodes for electric arc heating;
- a chute configured to charge therethrough the DRI along with lumpy carbonaceous material to the DRI melting furnace through the chute;
- wherein the system is configured to form a slag layer comprising slag and a layer of molten iron below the slag layer;
- at least one oxygen injection nozzle configured to inject oxygen into the slag layer not penetrating the slag or reaching the molten iron from the at least one oxygen injection nozzle;
- an oxygen adjustor configured to adjust oxygen flow rate to stabilize current fluctuation for each electrode;
- a slag door or a slag tap hole located at an intermediate elevation of a side wall of the DRI melting furnace configured to discharge the slag;
- and
- a tap hole located at a bottom or lower portion of the DRI melting furnace configured to discharge the product hot metal;
- wherein the system is configured to maintain the soft and sparse slag characteristic favorable for the electric arc furnace to efficiently transfer energy to the molten iron with a power input per furnace area higher than 600 KW/m2 while maintaining the FeO amount less than 5 wt. % in the slag and the carbon amount higher than 2.5 wt. % in the product hot metal at the DRI melting furnace.
The system of 12, wherein the amount of the lumpy carbonaceous material is more than 30 kg of carbon left in the slag per 1 ton of molten iron.
Dependencies are inferred from the claim text.