Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
1999-06-17
2001-12-11
Andrews, Melvyn (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S566000, C420S029000
Reexamination Certificate
active
06328783
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of producing iron from iron carbide in a metallurgical vessel containing a bath of molten iron.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of producing iron from iron carbide which comprises the steps of:
(i) injecting solid iron carbide into a molten bath comprising molten iron and slag and dissolving the iron carbide in the molten bath;
(ii) injecting an oxygen-containing gas into a gas space above the surface of the molten bath to cause combustion of at least a portion of combustible material in the gas space; and
(iii) causing splashes and/or droplets of molten iron and/or slag to be ejected upwardly from the molten bath into the gas space above the quiescent bath surface to form a transition zone in which heat generated by combustion of combustible material is transferred to the splashes and/or droplets of molten iron and/or slag and thereafter is transferred to the molten bath when the splashes and/or droplets of molten iron and/or slag return to the molten bath.
The term “combustible material” is understood herein to mean any solid, molten and gaseous material.
By way of example, the term covers carbon monoxide and hydrogen generated in and thereafter released from the molten bath.
The iron carbide may be obtained from any suitable source and be in any suitable form.
Typically, a small proportion of the “iron carbide” comprises iron ore and/or FeO. As a consequence, dissolution of iron carbide in the molten bath in step (i) introduces oxygen into the bath which can combine with dissolved carbon to form carbon monoxide which is released from the bath into the gas space.
In one embodiment, the method comprises injecting an oxygen-containing gas into the molten bath to provide oxygen for reaction with dissolved carbon in the bath to form carbon monoxide which is released from the bath into the gas space.
Step (i) of the above-described method releases carbon into the molten bath. The carbon has the dual purpose of:
(i) maintaining the molten bath as a reducing environment so as to prevent oxidation of the iron in the bath; and
(ii) providing a source of combustible material for generating heat to maintain the molten bath at a temperature that is sufficient to dissolve iron carbide injected into the bath.
With regard to sub-paragraph (ii) above, as noted above, there is oxygen in the molten bath—which may be introduced as part of the iron carbide feed and/or injected as part of the oxygen-containing gas in step (ii) of the method—and the oxygen reacts with a proportion of dissolved carbon in the molten bath and is released as carbon monoxide into the gas space above the bath surface.
The carbon monoxide is a combustible material which reacts with oxygen-containing gas in the gas space to form carbon dioxide and, as a consequence of this reaction, generates heat which is transferred via the transition zone to the molten bath.
In addition, a proportion of dissolved carbon reacts with carbon dioxide according to the Bouduard reaction to reform carbon monoxide to generate a further supply of combustible material.
In a similar reaction, a proportion of dissolved carbon reacts with steam to reform carbon monoxide to generate a further supply of combustible material.
The reaction of dissolved carbon and carbon dioxide may take place in the transition zone, with:
(i) dissolved carbon being carried into the transition zone with splashes and/or droplets of molten iron from the molten bath; and
(ii) carbon dioxide that is in the gas space being carried into the transition zone with oxygen containing gas injected into the gas space above the molten bath.
It is preferred that the oxygen-containing gas injected into the gas space and/or into the molten bath be air.
It is preferred that the air be pre-heated.
It is preferred particularly that the air be pre-heated to a temperature of at least 550° C.
It is preferred that the method further comprises injecting a carbonaceous material into the molten bath and dissolving the carbonaceous material in the bath.
The term “carbonaceous material” is understood herein to mean any suitable source of carbon, in solid or gaseous form.
By way of example, the carbonaceous material may be coal.
Typically, the coal includes volatiles such as hydrocarbons which are sources of combustible material.
As with the carbon derived from the dissolution of the iron carbide, the carbonaceous material has the dual purpose of:
(i) maintaining the molten bath as a reducing environment so as to prevent oxidation of the iron in the bath; and
(ii) providing a source combustible material for generating heat to maintain the molten bath at a temperature that is sufficient to dissolve iron carbide injected into the bath.
It is preferred that the molten bath be maintained at a temperature of at least 1350° C.
It is preferred particularly that the molten bath be maintained at a temperature of at least 1450° C.
In one embodiment it is preferred that the transition zone be formed by injecting a carrier gas and iron carbide and/or the solid carbonaceous material and/or another solid material into the molten bath via a tuyere extending through a side of the vessel that is in contact with the molten bath and/or extending from above the molten bath so that the carrier gas and solid material cause molten iron and slag in the molten bath to be ejected upwardly.
It is preferred particularly that the method comprises controlling injection of carrier gas and solid material to cause molten iron and/or slag to be projected into the space above the molten bath surface in a fountain-like manner.
In another embodiment it is preferred that the transition zone be formed by bottom injection of carrier gas.
In another embodiment it is preferred that the transition zone be formed by bottom injection of a carrier gas and iron carbide and/or solid carbonaceous material and/or other solid material into the molten bath to cause upward eruption of molten iron and slag from the molten bath.
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Andrews Melvyn
Technological Resources Pty Ltd
LandOfFree
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