Method for smelting low nitrogen steel using electric furnace

Patent metadata

Field	Value
Publication number	US-12018341-B2
Application number	US-201917278594-A
Country	US
Kind code	B2
Filing date	Sep 25, 2019
Priority date	Sep 27, 2018
Publication date	Jun 25, 2024
Grant date	Jun 25, 2024

Abstract

A method is disclosed for smelting low nitrogen steel using a dual-shell electric furnace having two furnace shells and an arc power system for alternatively electrically heating the furnace shells in which one of the two furnace shells is respectively sequentially subjected to electric heating, feeding, sealing of a molten pool and blowing of a combustion medium and oxygen to initiate smelting; when the temperature of molten steel in the furnace shell subjected to electric heating reaches a target temperature, initiating electric heating of the other furnace shell. The method can shorten the smelting period and improve the throughput of a production line of an electric furnace to efficiently meet the market requirements for low nitrogen steel while reducing the emission of environmental pollutants associated with known processes.

First claim

The invention claimed is:

1. A method for smelting low nitrogen steel by using an electric furnace, wherein a dual-shell electric furnace is adopted to carry out smelting, and the dual-shell electric furnace is provided with two furnace shells and an arc power system; and the method comprises carrying out steps of feeding, sealing of a molten pool, blowing of a combustion medium and oxygen and electric heating respectively and sequentially in the two furnace shells, specifically, carrying out electric heating on the two furnace shells alternately by the arc power system, when electric heating is carried out on one of the two furnace shells, sequentially carrying out the steps of feeding, sealing of the molten pool and blowing of the combustion medium and oxygen in the other furnace shell, and when the temperature of molten steel in the furnace shell subjected to electric heating reaches a target temperature of 1,600-1,660° C., starting to carry out electric heating on the other furnace shell.

2. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein the arc power system is a DC arc power system.

3. The method for smelting the low nitrogen steel by using the electric furnace of claim 2 , wherein the DC arc power system has a rated power of 0.7 to 1 MW per ton of molten steel.

4. The method for smelting the low nitrogen steel by using the electric furnace of claim 2 , wherein the DC arc power system is provided with a hollow argon blowing electrode, and a bottom electrode of the hollow argon blowing electrode is a flake electrode.

5. The method for smelting the low nitrogen steel by using the electric furnace of claim 4 , wherein argon blowing of the hollow argon blowing electrode is throughout the entire electric heating process.

6. The method for smelting the low nitrogen steel by using the electric furnace of claim 5 , wherein an argon blowing flow of the hollow argon blowing electrode is controlled to be 50-100 standard liters per minute.

7. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein each of the furnace shells is provided with 4 to 6 blowing guns for blowing the combustion medium and oxygen, and an oxygen blowing flow of each blowing gun is 2,500-4,000 standard cubic meters per hour.

8. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein the step of blowing the combustion medium and oxygen further comprises simultaneously blowing the combustion medium and oxygen for 5-10 min, and then only blowing oxygen to carry out decarburization smelting.

9. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein when electric heating is carried out on the furnace shell, a slagging material is added into the furnace shell to form foam slag; and after the foam slag is formed, the oxygen blowing flow, according to the carbon content of steel, is adjusted as follows: when the carbon content is smaller than 0.5%, the oxygen blowing flow is reduced to 40% to 60% of the oxygen blowing flow when the carbon content is greater than 0.5%, until smelting is finally finished.

10. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein in the step of feeding, a total carbon content of the molten steel is 1.5-2.5 wt % of a final quantity of the molten steel after tapping, and the nitrogen content of the molten steel after tapping is smaller than 25 ppm.

11. The method for smelting the low nitrogen steel by using the electric furnace of claim 1 , wherein the step of feeding comprises firstly, adding at least one of light and thin scrap steel and direct reduced iron, cokes and lime, then adding molten iron, and finally, adding common scrap steel.

Assignees

• Baoshan Iron & Steel

Inventors

• Xu Yingtie
• Chen Zhaoping
• Li Chengbin
• Yang Baoquan

Classifications

• C21C2250/06

  Hollow electrode · CPC title

• C21C2005/5235

  with bottom electrodes · CPC title

• C21C7/072

  Treatment with gases (C21C7/06, C21C7/064, C21C7/068 take precedence) · CPC title

• F27B14/02

  with tilting or rocking arrangements (F27B14/04 takes precedence) · CPC title

• F27B3/10

  Details, accessories or equipment, e.g. dust-collectors, specially adapted for hearth-type furnaces · CPC title