Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1996-09-24
1999-08-31
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
588207, C21B 1100
Patent
active
059448709
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of International application PCT/AT96/00019, filed Feb. 7, 1996.
FIELD OF THE INVENTION
The invention relates to a process for producing pig iron or steel and cement clinker from slags.
BACKGROUND OF THE INVENTION
Prior Art
It has already been known to blow prereduced and at least partially preheated charges into a fluidized layer along with coal, wherein coal is gasified in a fluidized layer under reduction of the charge and pig iron as well as slag are drawn off in the liquid states. These known melting gasifying reactions, as a rule, have been optimized in view of the pig iron output sought. In order to be able to produce cement clinker in addition to pig iron, ore together with a batch of lime have already been charged into the melter gasifier according to an earlier suggestion, the desired cement clinker composition having been adjustable by means of the lime batch. By appropriate adjustment of the basicity of the slag, a suitable starting material having hydraulic properties may be synthetized from a series of slags, which starting material may be used either directly as what is called slag cement or as an additive in cement adjustment or in the production of cement. However, strongly basic slags, such as, for instance LD slags, on grounds of their high iron oxide contents, as a rule, are not suitable directly for further utilization in the production of cement. Taking into account the increasing burden of such steel slags and, in particular, LD slags, by heavy metals, the disposal of such slags also constitutes an ever increasing problem. Above all, the relatively high amounts of steelworks slags incurred to date no longer can be utilized in an economic manner, and taking into account the increasing content of heavy metals it is to be feared that also dumping will be encumbered with ever increasing problems.
Binder additives influencing the setting time, the fatigue strength and other parameters essential to binders, have gained more and more importance in the production of hydraulic binders. Such additives may be used in connection with conventional hydraulic binders, such as, for instance, slag cements or portland cements, to adjust the desired properties.
SUMMARY OF THE INVENTION
The invention aims at providing a process of the initially defined kind by which a number of slags and, in particular, problematic slags, in a particularly simple manner can be converted into valuable hydraulic binders and binder additives at the simultaneous production of pig iron or steel. To solve this object, the process according to the invention substantially consists in that iron-oxide containing liquid slags, such as, e.g., steelworks slag, are mixed with iron oxide carriers, such as, e.g., iron ores, basic lean ores, rolling mill cinders or metallurgical dusts and lime, and the ferrite slag formed is reduced in a reduction reactor under formation of an iron bath and a sinter phase while burning carbon, whereupon the sinter phase is discharged as a clinker. Primarily with liquid steel slag, as incurs in the LD process, relatively low CaO values, in addition to iron oxide values that are too high, are responsible for homogenous clinker structures having the required cristallographic properties, such as, in particular, high alite/C.sub.3 S values, not being readily obtainable. By the fact that iron-oxide-containing liquid slags of this kind, such as, e.g., steelworks slag, are mixed with iron oxide carriers, such as, e.g., iron ore and lime, the appropriate cristallographic marginal conditions for the formation of synthetic binder additives or synthetic hydraulic binders have been substantially enhanced. The early strength of cements to a large degree depends on the alite content of appropriate cement clinkers. By controlling the process according to the invention by the addition of iron ores, basic lean ores or the like and lime to iron-oxide-containing liquid slags, it has become feasible to produce cement clinkers having high early strength values. Mixing of the liquid ir
REFERENCES:
patent: 4396422 (1983-08-01), Matsuno et al.
patent: 5336296 (1994-08-01), Lupeiko
patent: 5501721 (1996-03-01), Edlinger
patent: 5516357 (1996-05-01), Edlinger et al.
Patent Abstracts of Japan, vol. 10, No. 287, (C-375), Sep. 30, 1986, & JP,A,61104013, May 22, 1986.
Piret et al: "Verwertung von LD-Schlacke zur Erzeugung von Portlandzementklinder und Roheisen", Stahl and Eisen, vol. 104, No. 16, Aug. 13, 1984, Dusselforf, DE., pp. 774-778.
"Holderbank" Financiere Glarus AG
Andrews Melvyn
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