Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1990-02-23
1992-02-04
Andrews, Melvyn J.
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75560, 75567, 75568, C21B 7072
Patent
active
050856910
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to metallurgy and more particularly to a method of producing general-purpose steel.
The invention can be used in production of converter, open-hearth, and electrical general-purpose steel.
The present invention can be most effectively used in production of manganese-alloyed steel.
BACKGROUND OF THE INVENTION
At present all over the world in production of general-purpose steel use is made of ferroalloys as alloying materials.
The use of ferroalloys requires large energy expenditure since an energy carrier is consumed in great amounts. Besides, the production of ferroalloys is accompanied with the formation of harmful for the environment gases in concentration exceeding maximum permissible levels in the atmosphere according to the international standards.
The production of general-purpose steel with the use of ferroalloys proceeds with high losses of an alloying element and with a low degree of extraction thereof into steel. This is due to the fact that the process of preparing ferroalloys and the process of steel alloying are high-temperature and are accompanied with high losses of the alloying element together with gaseous products of the reaction.
In addition, in the production of ferroalloys there exists a high slag multiplicity also resulting in high losses of the alloying element with the slag.
The degree of extraction of the alloying element from ferroalloys into steel is low since approximately one fifth of the ferroalloy is consumed for deoxidizing of metal.
Known in the art is a method of steel refining by the introduction of oxide materials containing metals, which are alloying for the steel being smelted, into a steel making unit (JP, A, 59-215412).
The known method includes the loading of cast iron into a smelting unit, the subsequent supply of oxide materials containing alloying metals, for instance, manganese, chromium, silicon, molybdenum, vanadium, niobium, and cobalt simultaneously with a carbon-containing material into the same unit, and delivery from below of a gas-oxygen mixture containing 20-70% of oxygen at a flow rate of 0.1 mm.sup.3 /t.multidot.min.
This is accompanied with a decrease in the amount of carbon in the carbon-containing material and with liberation of heat required for heating and melting all the materials introduced into the steelmaking unit.
Besides, a part of the carbon is consumed for the reduction of the alloying elements from the slag which proceeds with high heat losses. As a result, mild steel is obtained.
Since oxide materials are used without a thermal treatment, they contain hydrate moisture and readily dissociating complex compounds of various oxides. When such oxides find their way to the surface or into the bulk of liquid metal, gaseous dissociation products are formed the liberation of which leads to slag foaming and to discharge of the metal and slag from the steel-making unit.
As a reducer in the known method use is made of carbon-containing materials introduced into the steel-making unit simultaneously with oxide materials.
It is known that the reaction of carbon with oxygen is endothermal; therefore, to compensate for heat losses in the course of the reduction, an additional heating of liquid metal is required (prior to introducing oxide and carbon-containing materials) up to a temperature higher than that in the method of steel alloying with ferroalloys.
Besides, a simultaneous supply of oxide and carbon-containing materials and a subsequent blowing of liquid metal with an oxygen-containing gaseous mixture results in combustion of carbon in the flow of the gaseous mixture, hence, in an inefficient consumption thereof as a reducer.
The use of the known method does not ensure any certain degree of extraction of the alloying element, for instance, manganese, from the oxide material into steel since it is impossible to predict what amount of the carbon-containing material is consumed for the reduction and what amount is burnt.
Largely, the rational use of manganese in the known method depends on the
Bulyanda Alexandr A.
Gizatulin Gennady Z.
Mizin Vladimir G.
Nakonechny Anatoly Y.
Ponomarenko Alexandr G.
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