Method of making low carbon steel using ferrous oxide and mineral carbonates
a technology of ferrous oxide and mineral carbonates, which is applied in the direction of process efficiency improvement, etc., can solve the problems of large amount of molten large amount of dissolved oxygen in the steel, and yield loss of iron available, so as to reduce the amount of iron oxide in the slag, increase the dissolved oxygen, and maintain the effect of dissolved oxygen
Inactive Publication Date: 2013-07-04
DRESSEL GREGORY
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Benefits of technology
The invention provides an improved method for increasing dissolved oxygen in the steelmaking process while also forming carbon dioxide for stirring and carbon oxidation. This is useful for low carbon steel production. By injecting a cored wire containing mineral carbonate after the furnace melting process, the dangerous and expensive effects of adding oxygen in the electric arc or basic oxygen furnace can be eliminated. The use of cored wire reduces the risk of damage to the ladle refractory lining and provides more precise control of the process for the operator while reducing costs. Additionally, the invention utilizes ferrous oxide and mineral carbonate for making low carbon steel grades with 0.015 to 0.06% carbon.
Problems solved by technology
When the carbon level in the molten steel gets below 0.06%, dissolved oxygen in the steel exponentially increases resulting in the formation of large amount of molten iron oxide in the slag.
Iron oxide increases in the slag represent a yield loss of iron available in the furnace for further processing.
Additionally, iron oxide in the slag attacks furnace refractories causing erosion and possible steel and slag leakage from the furnace shell.
Thermodynamically it is possible increase the dissolved oxygen content from atmospheric air to remove carbon but the ladle must be violently stirred with resulting damage due to liquid metal roiling against the ladle refractory lining.
Stirring results in a violent roil in the slag layer on top of the ladle.
Many carbon steel plants do not have vacuum degassers available.
Vacuum degassers represent a large capital cost and an additional processing step.
Furthermore, Ca, CaSi, and Mg can be used as fuels to increase temperature in molten steel but at a higher energy cost per kJ as compared to aluminum or silicon.
This method has largely been abandoned due to the fact that reduction of carbon by gaseous oxygen injection provides for faster carbon reduction.
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[0030]FIG. 1 shows the cored wire (100) consists of a filling (200) made of particular material and a metal jacket (110) made out of steel. The metal jacket (110) is usually made from a soft mild carbon steel ranging from 0.4 to 0.5 mm thick. The metal jacket (110) provides the following functions:
1. Contains the filling (200);
2. Keeps the filling (200) dry;
3. Prevents the filling (200) from reacting in the liquid slag layer on top of the ladle; and
4. Provides rigidity for the filling (200) to penetrate into the molten steel.
[0031]The cored wire (100) is preferably wound into a coil (400) and placed on a reel. The metal jacket (110) starts as a flat ribbon like construction and is formed into the cylinder that holds the filling (200). The flat ribbon like material is bent into a cylinder with the seam (120) holding the filling (200) in place inside the cored wire (100).
[0032]FIG. 2 shows the cored wire (100) with the seam (120) bent flush with the circumference of the cored wire (10...
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Abstract
A cored wire injection with a filling of iron oxide and mineral carbonate provides an improved method and apparatus for increasing and maintaining dissolved oxygen in the steelmaking process, while also providing a method for forming carbon dioxide for stirring and carbon oxidation in the molten steel bath. The method and apparatus are particularly useful for low carbon steel production by lowering the tap oxygen content in the furnace and preventing high amounts of iron oxide in the slag. Injecting a cored wire containing a mineral carbonate in the ladle after the furnace melting process provides sources of oxygen and a method of stirring the steel and reducing the partial pressure of CO needed to lower the carbon content.
Description
RELATED APPLICATIONS[0001]This application claims benefit and priority from U.S. provisional application No. 61 / 631,423 accorded a filing date of Jan. 4, 2012.FIELD OF INVENTION[0002]This invention relates generally to a material and method for reducing the carbon and alloy content in molten steel.DESCRIPTION OF RELATED ART[0003]Various steel making technologies have been developed since the Bessemer / Kelly bottom blown furnace and the Siemens open hearth furnace breakthroughs in the mid 19th century. Open hearth steelmaking predominated steel production through the mid 1960's. Electric arc and basic oxygen furnaces have completely replaced Bessemer / Kelly processes and open hearth steelmaking in the USA and most of the world.[0004]Molten steel is normally produced in an Electric Arc Furnace (EAF) using primarily solid ferrous scrap or other solid iron derivatives, or a Basic Oxygen Furnace (BOF) using hot molten iron containing up to 4.0% C and scrap, or other solid iron derivatives....
Claims
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Login to View More IPC IPC(8): C21C5/00
CPCC21C5/00C21C7/0056C21C7/076C21C7/068C21C7/0075Y02P10/20
InventorDRESSEL, GREGORY
OwnerDRESSEL GREGORY