Specialized metallurgical processes – compositions for use therei – Processes – Process control responsive to sensed condition
Reexamination Certificate
1999-02-08
2001-05-15
King, Roy (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Process control responsive to sensed condition
C075S387000, C075S460000, C075S469000, C075S491000
Reexamination Certificate
active
06231638
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority of Patent Application No. 19859354.6 filed on Dec. 22, 1998 in Germany, the subject matter of which is incorporated herein by reference.
FIELD OF THE INVENTION
The Invention concerns a process and an apparatus for producing metal from metal ores, in particular crude or pig iron from iron ore, in which the ore which contains metal oxides is brought into reaction contact with a reducing gas which contains carbon and/or hydrogen (and possibly compounds thereof) and which was previously obtained from solid, carbon-bearing and/or hydrocarbon-bearing substances.
BACKGROUND OF THE INVENTION
It is known that the ore which for the major part comprises metal oxides (being various ones, even in the case of iron) must be subjected to a reduction procedure before the metal can be obtained. That reduction operation is effected by means of carbon and possibly hydrogen—or also compounds thereof—which are contained in a reducing gas which is caused to act on the metal ore.
The reduced metal ore then passes into a smelting procedure. In that case, the gas required for the reduction operation is obtained in the region of the reducing and smelting procedure itself, by carbon-bearing substances (for example coke, coal, oil, natural gas) being added to the zone of the metal which has already been reduced and heated, whereby, with the addition of oxygen (in the air), they are broken up or converted in carbon-bearing gas which is fed to the preceding reduction operation.
The conventional blast furnace process is known in that respect, in which both reduction of the metal ore and also formation of the reducing gas as well as subsequent smelting liquifaction of the metal occur in the blast furnace—progressively in a downward direction. In that blast furnace process, among additive substances, coke is possibly mixed with the iron ore, as a carbon carrier. It is known for oil or carbon also to be injected by way of lances into the air flow in the region of the hearth of the blast furnace for better control of the blast furnace process and to save on coke, the consumption of coke thereby also being reduced. This material (oil or coal dust) which is additionally injected must be introduced in very finely distributed form in order to ensure clean adequate gasification. Two articles in the journal “Stahl and Eisen”, No 4 of Feb. 25, 1985, pages 211-220 contain summaries relating to the injection of coal dust into blast furnaces. The injection of coal dust was forced upon operators in particular in the course of rising oil prices. In that respect it was found that when adopting the injection procedure, because of the short time available of about 10 ms, good results, more specifically almost complete gasification of the coal dust, were achieved only with grain sizes of below 0.1 mm., even if tests were also successfully carried out with some installations, using larger grain sizes.
It has also already been proposed that, instead of injecting oil and coal dust, other carbon-bearing waste substances such as, for example, dried sewage sludge or other carbon-bearing waste such as refuse, waste paper, lignite, as well as waste from wood, plastic material, rubber or the like can be introduced (DE-A 29 35 544). In regard to appropriate tests or results however, all that was put forward were assumptions as to the manner in which such substances are to be introduced into the blast furnace. DE-A 41 04 252 also proposes introducing plastic-bearing waste substances into a blast furnace in a fine-grain or dust form by way of the tuy{dot over (e)}res, with the introduction of sewage sludge (dust capable of trickle flow) being referred to by way of example. It is expressly emphasized that this process also requires that the substance, which is to be injected, be of a fine-grain nature.
SUMMARY OF THE INVENTION
Taking the known process as set forth in the opening part of this specification as its basic starting point, the object of the invention is to make plastic waste, including in organically and/or inorganically contaminated form, useable as a supply for the constituents of the reducing gas. Plastic waste occurs constantly in large amounts and represents a serious disposal problem. It occurs mostly if not exclusively in solid form, either as packaging waste—which is frequently heavily contaminated—or as offcuts or the like in the course of the production of plastic articles.
Accordingly the invention provides that the carbon-bearing and/or hydrocarbon-bearing substances, at least partially comprising plastic material, which in the process of the general kind set forth in the opening part of this specification are supplied to obtain the reducing gas, are injected in comminuted fluidised form as an agglomerate into the air flow in the hearth of the metallurgical shaft or pit furnace, in particular a blast furnace. That is effected by way of lances which project into the shaft furnace and which are connected to a transport conduit. The plastic material to be injected is fed to the lances by way of that transport conduit. In the event that, contrary to expectation, blockages should occur or hot air should blow back out of the blast furnace into the lance and thus into the transport conduit, a plurality of shut-off or check devices are proposed in the transport conduit, so that the transport conduit is not only protected but immediate resumption of overall operation of the installation and injection of the plastic materials occurs. To dissolve blockages of the plastic material in the transport conduit, there are provided a first and third shut-off device, while a second shut-off device is provided to prevent reverse transportation of plastic material or blow-back of the hot gas masses from the blast furnace into the transport conduit. The mode of operation thereof is set forth in greater detail in the claims but in particular also in the specific description.
To dissolve blockages in the transport conduit, the invention makes use of the fact that the pressure in the transport conduit is a pressure which is 4 to 6 times atmospheric pressure. If therefore the pressure in the interior of the transport conduit is reduced to atmospheric pressure (about 1 bar) by way of a vent opening, a very great pressure and suction effect is applied to the blockages which are released and conveyed out of the system from the transport conduit.
So that the injection lances which project into the blast furnace do not overheat when the injection installation in a stopped condition, there is provided a connection for compressed air which is always activated.
Further advantageous configurations of the invention are set forth in the claims.
REFERENCES:
patent: 5244490 (1993-09-01), Agarwal
patent: 5554207 (1996-09-01), Bogdan et al.
patent: 5772727 (1998-06-01), De Haas et al.
patent: 27 14 355 (1978-10-01), None
patent: 0 059 904 (1982-09-01), None
patent: 0 622 465 (1994-11-01), None
patent: 597770 (1925-05-01), None
patent: 61-153218 (1986-07-01), None
patent: 6-335628 (1994-12-01), None
Janz Joachim
Voss Manfred
Der Grune Punkt - DSD Duales System Deutschland AG
Kinberg Robert
King Roy
McGuthry-Banks Tima
Spencer George H.
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