Treatment of iron oxide agglomerates before introduction...

Details Treatment of iron oxide agglomerates before introduction... Treatment of iron oxide agglomerates before introduction...

1999-03-19

2001-04-10

Andrews, Melvyn (Department: 1742)

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

C075S321000, C075S484000, C075S504000, C075S414000, C075S629000, C075S641000

Reexamination Certificate

active

06214087

ABSTRACT:

FIELD OF INVENTION
This invention relates to a method for treatment of feed material before feeding into an ore processing furnace. More particularly, this invention relates to the encapsulation of iron bearing agglomerates with carbonaceous materials before introduction into a furnace for improvements in iron oxide metallization.
BACKGROUND OF THE INVENTION
In 1998, Midrex International received U.S. Pat. No. 5,730,775, that teaches an improved method (known by the service mark of FASTMET
7
) and apparatus for producing direct reduced iron from dry iron oxide and carbon compacts that are placed onto a rotary hearth, and are metallized by heating the compacts for a short time period. For a general understanding of the recent art, U.S. Pat. No. 5,730,775 is herein incorporated by reference.
Improvements in efficiency have been attempted within the industry with furnace modifications that provide a vitreous hearth layer that remains vitrified at increased temperatures, with a modification that provides an additional hearth coating to allow for shortened processing time of iron oxide compacts. Coating of the hearth surface facilitates product removal, reduces loss of purified molten iron onto the vitreous hearth layer and/or reduces loss on the interior surfaces of furnaces from the protective coating of surfaces with metallized iron oxides during processing and reducing operations. The above described hearth coatings add additional costs by adding materials onto the hearth layers, add to the complexity of reactions occurring within the furnace, and add additional processing time for the hearth coatings to cure onto the hearth surfaces.
Improvements are sought within the metal production industry for treatment with coatings of carbonaceous feed material before placement within a furnace, the coatings providing improved metallization of compounds within the furnace without additional treatment and coatings on the furnace hearth surface, or in conjunction with limited hearth surface conditioning.
SUMMARY OF THE INVENTION
The invented process includes the method of producing solid metal product by treating carbon containing metal bearing compounds in compacts or agglomerates with coatings of treatment material before feeding compacts or agglomerates into a furnace. The method of producing includes the steps of providing carbon containing metal bearing compounds in compacts, coating the metal bearing compounds in compacts with a treatment material encapsulating the metal bearing compounds in compacts, treating the treatment material to form a hardened encapsulating coating on the compacts, feeding the compacts into a furnace, heating and reducing the metal bearing compounds in the compacts, forming liquid metal and carbon globules and slag particulates, cooling and creating solid metal and carbon nuggets, and removing solid metal and carbon nuggets and slag particulates from the furnace.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide a more efficient method of achieving reduction of metal bearing compounds in compacts and production of metal nuggets at elevated temperatures in a reducing furnace.
An additional object of the present invention is to provide a method for pre-treatment of carbon containing metal bearing compounds in compacts, forming hardened outer surface coatings around the compacts to reduce the generation of particulates when the compacts are fed into a furnace.
A further object of the present invention is to form a sacrificial layer of treatment material onto carbon containing metal bearing compounds in compacts, to provide a sacrificial layer to react with oxidizing combustion components within a furnace.
An additional object of the present invention is to provide a coating on carbon containing iron bearing compounds in compacts or agglomerates that prevents interaction between the molten iron and slag in the compacts or agglomerates with the hearth surface of the furnace.
The objects of the invention are met by a method of producing carbon containing metal bearing compounds comprising the steps of providing a plurality of compacts having carbon containing metal bearing compounds, coating the compacts with a treatment material, encapsulating the exterior surfaces of the compacts with a residual layer, and treating the residual layer on the coated compacts. After the encapsulating coating is in place, the compacts are feed into a furnace, heating and reducing the carbon containing metal bearing compounds within the compacts without the degradation of the compacts, forming metal and carbon globules and slag particulates, cooling of the liquid metal and carbon globules, and creating of solid metal and carbon nuggets which remain separate from the furnace hearth surface for ease of removal of the solid metal and carbon nuggets and slag particulates from the furnace.


REFERENCES:
patent: 2869850 (1959-01-01), Wienert
patent: 3443931 (1969-05-01), Beggs et al.

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