Hot Metal Production from DRI with Electric Arc Heating

Patent metadata

Field	Value
Publication number	US-2026071288-A1
Application number	US-202519386625-A
Country	US
Kind code	A1
Filing date	Nov 12, 2025
Priority date	Mar 11, 2022
Publication date	Mar 12, 2026
Grant date	—

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.

First claim

What is claimed is:

1 . 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/m 2 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 from the at least one oxygen injection nozzle such that no oxygen injected from the at least one oxygen injection nozzle fully penetrates the slag layer to reach the layer of molten iron, thereby generating CO gas and exothermic heat within the slag to expand, soften, and disperse the slag layer; 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/m 2 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.

2 . The system of claim 1 , comprising multiple injection nozzles circumferentially laid out around the furnace and wherein the oxygen is configured to be injected with a sub-sonic gas velocity toward each electrode from the injection nozzles.

3 . The system of 1 , 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.

4 . The system of claim 1 , wherein pulverized carbonaceous material or natural gas is configured to be injected in the slag together with the oxygen.

5 . The system of claim 4 , wherein the amount of carbon or natural gas is equal or more than the stoichiometric amount of the oxygen in the combustion reaction forming CO 2 .

6 . The system of claim 1 , wherein the elevation of the slag upper portion is maintained above the elevation of the slag tapping hole or the bottom end of the slag door while the slag is discharged, to prevent the carbonaceous material floating in the liquid slag from being discharged with the slag from the DRI melting furnace.

7 . The system of claim 1 , wherein a combustible gas, a reducing gas, or an inert gas is configured to be injected to stir the molten iron to enhance mixing and replace some of the carbonaceous material fed along with the DRI to efficiently carburize the molten iron.

8 . The system of claim 1 , further comprising an electromagnetic stirrer configured to stir the molten iron.

9 . The system of claim 1 , wherein the DRI is made from iron ore containing an iron content <65 wt. %.

10 . The system of claim 1 , wherein the system is configured to control an oxygen flow rate of the oxygen injected utilizing the at least one oxygen injection nozzle such that a noise level at the DRI melting furnace is maintained below 90 dB.

11 . The system of claim 1 , wherein the system is configured to adjust an oxygen flow rate of the oxygen injected utilizing the at least one oxygen injection nozzle such that current fluctuations of each electrode of the plurality of electrodes are stabilized.

Assignees

• Midrex Technologies Inc
• Kobe Steel Ltd

Inventors

• Michishita Haruyasu
• Tokuda Koji
• Mimura Tsuyoshi
• Fujiwara Katsuma

Classifications

• C21B13/002

  Reduction of iron ores by passing through a heated column of carbon · CPC title

• C21B2100/60

  Process control or energy utilisation in the manufacture of iron or steel · CPC title

• C21B2300/02

  Particular sequence of the process steps · CPC title

• C21B2100/64

  Controlling the physical properties of the gas, e.g. pressure or temperature · CPC title

• C21B2100/66

  Heat exchange · CPC title