Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
2000-04-17
2001-07-31
King, Roy (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S504000, C075S531000, C075S549000
Reexamination Certificate
active
06267799
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of producing metals and metal alloys, in particular although by no means exclusively iron and iron alloys, from metal oxide, such as ores and partly reduced ores, in a metallurgical vessel containing a molten bath.
BACKGROUND OF THE INVENTION
A known method of producing molten iron from iron ore is described generally as the HIsmelt Process and is based on forming a bath of molten iron and slag in a smelt reduction vessel which comprises:
i. bottom tuyeres for injecting solid carbonaceous material and a carrier gas into the molten bath;
ii. top tuyeres for injecting iron ore, which may be pre-heated and/or partially reduced iron ore, into the molten bath from above the surface of the molten bath; and
iii. top tuyeres for injecting air into the space above the surface of the molten bath to after-burn or post-combust reaction gases, such as CO and H
2
, released from the molten bath.
In accordance with the HIsmelt Process, the carbonaceous material acts as a reductant and an energy source.
An important feature of the HIsmelt Process is to form a transition zone in the gas space above the molten bath surface in which there are ascending and thereafter descending droplets or splashes of molten metal and slag which mix with reaction gases from the molten bath, top blown hot air, and the reaction gases from afterburning. The purpose of the transition zone is to facilitate the transfer to the molten bath of heat that is released by afterburning reaction gases from the molten bath. In accordance with the HIsmelt Process, the transition zone is formed by vigorous bottom injection of carbonaceous material and carrier gas into the molten bath which causes droplets and splashes of molten metal and slag to be projected from the molten bath.
A recent development of the HIsmelt Process is described in Australian patent application 48938/93 entitled “A Method for Intensifying the Reactions in Metallurgical Reaction Vessels” in the name of Technological Resources Pty Limited. The Australian patent application claims a priority date of Oct. 16, 1992 from German patent application 4234974.
The Australian patent application describes that an improvement in heat transfer efficiency of the HIsmelt Process can be obtained by controlling the bottom injection of carbonaceous material and carrier gas so that the transition zone is defined by a “fountain” of splashes and droplets of molten iron and slag. The paragraph bridging pages 5 and 6 of the patent specification of the Australian patent application describes that:
“The invention is also based on the finding that the reactions in metallurgical reaction vessels are increased if fractions of the smelt are ejected from the bath like a fountain through the amount of gas introduced via the under-bath tuyeres and these fractions of the smelt move within the gas space in the form of drops, splashes and large particles of the smelt on ballistic trajectories that are only stopped when the smelt fractions hit the vessel wall or the smelt itself, collide with other smelt fractions or are drawn in by the oxidising gases blown onto the bath in the form of free jets.”
An object of the present invention is to provide an alternative method of generating a fountain-like transition zone.
SUMMARY OF THE INVENTION
According to the present invention there is provided a method of producing metals and metal alloys from metal oxides in a metallurgical vessel containing a molten bath, the molten bath comprising a metal layer and a slag layer on the metal layer, the method being characterised by the steps of:
i. injecting a carrier gas and solid carbonaceous material and/or metal oxides and/or other solid material into the molten bath through a section of a side of the vessel that is in contact with the molten bath and/or from above the molten bath so that the carrier gas and solid carbonaceous material and/or metal oxides and/or other solid material cause molten metal to be projected into a space above the surface of the molten bath to form a transition zone; and
ii. injecting an oxygen-containing gas into the space above the molten bath surface to afterburn reaction gases released from the molten bath into the transition zone.
The term “transition zone” is understood herein to mean a zone above the molten bath in which there are ascending and thereafter descending droplets or splashes of molten metal.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is based on the realisation that it is possible to form the transition zone of the HIsmelt Process, without loss of the performance and with engineering advantages, by injecting carrier gas and carbonaceous material and/or metal oxides and/or other solid material into a molten bath through a section of a side of a metallurgical vessel that contacts the molten bath and/or from above the surface of the molten bath.
As a consequence, the present invention makes it possible to avoid using bottom injection of carbonaceous material and carrier gas to form the transition zone and the engineering difficulties associated with such bottom injection. One engineering difficulty is that the use of bottom tuyeres makes it necessary to mount the metallurgical vessel for rotation about an axis so that the bottom tuyeres can be rotated clear of the molten bath at turn-down. Furthermore, if bottom tuyeres are eliminated, a much simpler, and more robust, furnace bottom construction is possible.
The present invention is also based on the realisation that, in situations where step (i) includes injecting carbonaceous material, injection through a tuyere as proposed is an effective means of achieving the desirable objective of ensuring that carbonaceous material penetrates the molten bath, and in particular the metal layer of the molten bath.
It is preferred that step (i) comprises injecting the carrier gas and carbonaceous material and/or metal oxides and/or other solid material through the side section of the vessel or from above the surface of the molten bath with sufficient momentum to penetrate the molten bath and cause molten metal to be projected into the space above the molten bath surface to form the transition zone.
It is preferred that step (i) comprises injecting the carrier gas and carbonaceous material and/or metal oxides and/or other solid material into the molten bath to cause the molten metal to be projected into the space above the molten bath surface in a fountain-like manner.
The carbonaceous material may be any suitable carbonaceous material, in solid, liquid or gaseous form.
The metal oxides may be in any suitable form. For example, the metal oxides may be in the form of ores and/or partly reduced ores. The degree of pre-reduction of the ores may range from relatively low (eg to FeO) to relatively high (70-90% metallisation).
The metal oxides may be pre-heated.
The other solid material may be any suitable material, such as, by way of example, fluxes or slag forming agents.
The carrier gas may be any suitable carrier gas.
It is preferred that the carrier gas be an oxygen-deficient gas.
It is preferred that the carrier gas comprise nitrogen.
The carrier gas may comprise waste process gas released from the vessel which has been used, by way of example, to partially reduce metal oxides that subsequently are transferred to the vessel.
The oxygen-containing gas may be any suitable gas such as, but not limited to, air or oxygen enriched air.
It is preferred that the oxygen-containing gas be air.
It is preferred particularly that the air be preheated.
According to the present invention there is also provided an apparatus for producing metals and metal alloys from metal oxides comprising:
i. a metallurgical vessel for containing a molten bath, the vessel having a base, a side wall, a roof, and a gas outlet;
ii. a first tuyere for injecting an oxygen-containing gas into a space in the vessel above the molten bath; and
iii. a second tuyere above the molten bath or in a section of the side of the vessel that is in contact with the molten bath for injecting a carri
Batterham Robin John
Dry Rod James
Innes John Alexander
King Roy
McGuthry-Banks Tima
Merchant & Gould P.C.
Technological Resources Pty. Ltd.
LandOfFree
Method of producing metals and metal alloys does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing metals and metal alloys, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing metals and metal alloys will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2483791