Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1993-05-12
1994-08-09
Andrews, Melvyn J.
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75528, 75531, 75537, 75957, 266212, 266215, 266901, C21B 1314
Patent
active
053362969
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to the field of ferrous metal, and more particularly to a method of obtaining steel in a liquid bath and a device to carry out this method.
1. Prior Art
Traditional methods of obtaining steel by multi-step technological techniques are well known, e.g., agglomeration-coke-chemistry-blast-furnace processes, steel-furnace processes (e.g., converter, martin, electrical steel furnace processes). All of these techniques have essential disadvantages: a large number of expensive main technological units with complicated auxiliary equipment; large total costs (labor costs included) to operate and repair the equipment; large inter-stage heat losses, relating to cooling intermediates; large costs for inter-stage transportation of intermediates; significant total heat losses, including heat losses at each technological unit; significant total losses of the iron extracted; limited ability to use the initial metal charge; and significant total environmental pollution with production wastes at each technological stage. Another known method is a method of obtaining steel in a liquid bath from charge materials comprising iron-containing raw material and slag-forming fluxes. The essence of this liquid bath method is to obtain low-carbon steel by interaction of iron oxides with a reductant, burning with an oxygen-containing gas to supply the process with heat, and introducing chemical additions to obtain the required chemical content of the desired low-carbon steel by an out-of-furnace method such as in a ladle. (Pokhvisnev A. N., Kozhevnikov I. Yu., Spektor A. N., Yarkho E. N. "Out-Of-Blast-Furnace Obtaining Iron Abroad", Metallurgy, Moscow, 1964, pp. 314-315).
In the liquid bath method, a liquid bath is formed first by melting iron, for example steel scrap, to form a liquid metal. The iron melt is continuously or periodically carbonized by saturating it with reductant by plunging carbonaceous electrodes into it or by blowing coal powder with the aid of methane into the melt. Pieces of iron-ore and slag-forming fluxes are continuously or periodically fed onto the surface of iron-carbonaceous melt. As a result of close contact with the reductant-carbon, dissolved in the iron melt, the iron is reduced, increasing the mass of iron-carbonaceous melt. Oxide impurities contained in iron-ore, are melted together with slag-forming fluxes to form a slag melt on the iron melt surface. This process of melting charge materials and reducing iron is provided with heat from burning fuel in oxygen-containing gas over the liquid bath. Before tapping, the iron-carbonaceous melt is decarbonized, stopping before hand the feeding of carbon-containing reductant into the melt. The low-carbon steel obtained has its chemical content corrected to the desired content by an out-of-furnace method.
A well known device to obtain steel in a liquid bath, e.g., a martin furnace, has a melting unit to initially melt charge materials, forms a liquid bath, and obtains low-carbon steel. The melting unit is formed with hearth-stones, walls, and an arch. It is provided with a device to introduce iron reductant in the liquid bath, means to feed charge materials, means to tap steel and slag out of it, a burner device to burn fuel inside the melting unit using from oxygen-containing gas, and a device to discharge burning wastes out of the unit.
An important characteristic of both this method and this device is a common technological area for carrying out both the oxidizing and reduction processes.
The atmosphere of the working space of martin furnace is of a very oxidizing character with respect to metal. This results from the necessity of complete burning the fuel. In addition, the oxidizing atmosphere makes the process of iron reduction slower, and iron, counteracting oxidizing gases-burnt products (CO.sub.2 and H.sub.2 O) is actively reduced.
Thus, in the above method, two opposed metallurgical processes simultaneously take place: at the boundary of the contact of metal and slag, which contains iron oxides, iron is r
REFERENCES:
patent: 3565605 (1971-02-01), Vayssiere et al.
patent: 3701519 (1972-10-01), Vayssiere et al.
patent: 3772000 (1973-11-01), Hyde et al.
patent: 4981285 (1991-01-01), Agarwal et al.
"Manufacturing Iron Without Blast Furnace", Metallurgy, Moscow, 1964, pp. 314-316, Pokhvistnev et al. with English Abstract.
Andrews Melvyn J.
Scientific Dimensions USA, Inc.
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