Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
1999-02-01
2001-04-10
Andrews, Melvyn (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S500000, C075S501000, C075S502000, C075S503000, C075S553000
Reexamination Certificate
active
06214085
ABSTRACT:
INTRODUCTION
This invention relates to a method for making steel directly. Conventionally, about 60% of the steel is made in integrated facilities generally consisting of a coke plant, a sintering plant, a blast furnace (BF) department and a basic oxygen furnace (BOF) complex. The other 40% is mainly produced in facilities known as electric arc furnace (EAF) shops or mini-mills which use scrap melters energized with electric power; in some instances iron units in other forms complement the scrap charged. Whether steel is made in integrated facilities or in scrap melters both processes suffer from production inefficiency, poor energy performance, environmental problems and large capital investment needs.
With respect to production inefficiency, it begins at the mine where the ore concentrate is made into pellets which are fired, and the special metallurgical coals that are mined and then classified at the delivery point where they are crushed to make a three or four component blend in order to produce a coke suitable for the BF; or, the concentrate is delivered to the sinter plant to make a sinter that is charged together with pellets and coke in the BF. The BF makes molten iron which is tapped into refractory lined torpedo cars and delivered to the BOF complex by rail using a locomotive. The molten iron is poured into a ladle which is then charged into the BOF. Every one of the above mentioned steps adds to production inefficiency which increases the discharge of greenhouse gases.
With respect to poor energy performance it takes energy to agglomerate the concentrate to form green pellets which are then fired to make pellets suitable for use at the BF. In the classifying of the various coals and their crushing to make the proper blend, in the making of the coke inclusive of the significant heat losses which take place during the heating of the coal, and in the using of the extensive machinery which is required for charging of the coal, pushing and quenching of the incandescent coke, conveying it and screening it, large quantities of energy are expended. The BF also consumes appreciable quantities of energy inclusive of the turbo-blowers to compress the air for the blast. In making the sinter as a feed for the BF, the sinter plant expends energy in firing hot gases through the raw materials to make the sinter, and then cooling it before delivery to the BF. Moving massive torpedo cars by locomotive from the BF department to the steelmaking complex demands expenditure of energy in addition to heat losses incurred until the molten iron is in the BOF ready to be blown. Pollution control devices of all sorts which consume large quantities of energy are disposed at the mines, at the coke plant, at the sinter plant at the BF and at the BOF. In the making of steel with scrap which is melted with electric power, the energy consumption is quite high by virtue of the high demand which is in surge form; also, electricity must be generated at the power plant and the efficiency of generating electricity is only about 33%. When melting iron units from directly reduced iron or the like, the consumption of electric power increases by roughly 50%. Poor energy performance means greater energy consumption which results in the discharge of excessive greenhouse gases.
With respect to environmental problems, every step taken in connection with conventional steelmaking whether it occurs at the mine, in the coke plant, in the sinter plant, at the BF or in handling and charging of molten iron into the steelmaking furnace, emissions of all sorts take place; emissions in the form of hydrocarbons, CO, H
2
S, SO
2
, NO
x
, CH
4
, and particulate matter and of course very large quantities of CO
2
.
With respect to investments, the last integrated steelmaking facility in the U.S. was built by Bethlehem Steel at Bums Harbor, Indiana about 40 years ago. The reason no other integrated facility was constructed is because the investment cannot be afforded; however several mini-mills (EAF's) have been constructed but mini-mills are essentially recyclers of steel scrap. But even in mini-mills, the cost of facilities is steadily increasing by virtue of the need to make quality steel with no contaminants. This situation is forcing scrap melters to build additional costly facilities (or have others build facilities) for producing from (virgin ore sources) iron units such as directly reduced iron (DRI), hot briquetted iron (HBI), iron carbide (Fe
3
C) or molten iron in order to be able to market an acceptable product which is devoid of contaminants.
OBJECTIVE OF THE INVENTION
The present invention addresses the above disadvantages by eliminating pelletizing the ore, the coke plant, the sintering plant and the blast furnace in integrated facilities and the electricity need for melting in mini-mills, and has for its main object the overcoming of such disadvantages with one single solution which is:
Efficient in production as well as in energy performance;
Environmentally benign; and
Low in capital requirement.
Another object of the present invention is to lower the operating costs of making a ton of steel by greatly reducing the manpower required.
Still another object of the instant invention is to increase the yield of steel from the same amount of raw material used.
Although this invention does not eliminate all green house gases originating from steelmaking, it substantially reduces their generation.
Other objects of this invention will appear from the following description and appended claims; reference is made to the accompanying drawings which describe certain physical structures to practice this method of making steel directly.
REFERENCES:
patent: 3941359 (1976-03-01), Shinville et al.
patent: 4756748 (1988-07-01), Lu et al.
patent: 5445363 (1995-08-01), Becerra-Novoa et al.
Calderon Albert
Laubis Terry James
Andrews Melvyn
Calderon Energy Company of Bowling Green, Inc.
Marshall & Melhorn
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