Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1997-09-16
2000-01-04
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75623, 75585, 75961, 420590, C21B 1314
Patent
active
060105534
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for producing pig iron, nonferrous heavy metal alloys, ferrochromium carbure or carbon-free ferrochromium and synthetic blast furnace slags, using metal-oxide-containing waste incineration residues or slags.
BACKGROUND OF THE INVENTION
A number of process variants have been proposed for processing waste incineration residues, wherein it has already been proposed inter alia to aftertreat waste incineration residues as incur in the form of slags or the like upon largely complete oxidation, by multi-stage reduction with nonferrous heavy metals being recoverable. With hitherto known processes each phase that has been depleted from metals could be granulated and added to a cement as a puzzolane.
Also the use of blast furnace slag in the course of cement production has already been prior art. Blast furnace slag stands out for its latent hydraulic properties and consequently may be added to a mixed cement immediately after appropriate comminuation or granulation. By appropriately treating blast furnace slag it is, however, also possible to directly aim at a defined cement quality, at least in terms of composition. Yet, in metallurgical operation also considerable amounts of steel slag incur, which are characterized by comparatively poor hydraulic properties. Therefore, such a steel slag, as a rule, calls for complex aftertreatment. The dumping of steel slag to an increasing extent gets problematic not least because of the chromium contents of such slags.
SUMMARY OF THE INVENTION
The invention aims at appropriately further processing and working up such steelworks slags within the scope of an overall process associated with a waste burning process such that directly usable products, such as, for instance, synthetic blast furnace slag, may be obtained, which in the following may be added, for instance, to a mixed cement.
To solve this object, the process according to the invention essentially consists in that the charging materials of waste burning, e.g., car shredder light fractions and/or metallurgical dusts, are at least partially oxidized and subsequently are reduced while separating nonferrous metals or alloys, whereupon the oxidic slag phase depleted from metals or alloys is mixed with liquid steelworks slag optionally upon further addition of metallurgical dusts, whereupon crude steel is drawn off while lowering the viscosity of the steelworks slag and the remaining slag portion is subjected to further reduction while recovering pig iron and optionally Fe chromium alloys, whereupon the resulting synthetic blast furnace slag is discharged. By the fact that the charging materials of waste burning, such as, e.g., car shredder light fractions, are oxidized at least partially, the prerequisite for separating nonferrous metals and nonferrous heavy metals is at first created. In this manner, an oxidic iron-oxide-containing slag phase depleted from such metals or alloys is formed, and due to the fact that this slag phase is mixed with liquid steelworks slag optionally upon the addition of metallurgical dusts that are equally difficult to dispose of, the possibility to considerably lower the viscosity of steel slag, on the one hand, and the prerequisite to reduce and separate from such steel slags the relatively high iron-oxide portion in a relatively simple manner, on the other hand, are created. An essential prerequisite for this is the inital lowering of the viscosity as rendered feasible by mixing with the oxidic slag phase derived from waste burning. Such a low-viscous slag containing high amounts of iron oxides in the following may readily be subjected to further reduction while obtaining pig iron and optionally iron chromium alloys, wherein a synthetic blast furnace slag is formed directly from the steel slag, which is relatively difficult to process in the beginning. The synthetic blast furnace slag is characterized by a substantially lower iron oxide content and no toxic heavy metals, the recovery in the form of pig iron of the iron amount cont
REFERENCES:
patent: 5405429 (1995-04-01), Rey et al.
patent: 5501721 (1996-03-01), Edlinger
patent: 5535234 (1996-07-01), Bullmann
patent: 5654976 (1997-08-01), Cowx et al.
Edlinger Alfred
Waschnig Albert
"Holderbank" Financiere Glarus AG
Andrews Melvyn
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