Method of processing iron-containing mettalurgical residual subs

Details Method of processing iron-containing mettalurgical residual subs Method of processing iron-containing mettalurgical residual subs

1996-12-30

1998-12-29

Andrews, Melvyn

Specialized metallurgical processes, compositions for use therei

Processes

Producing or treating free metal

75961, 266157, C22B 702, C21B 1314, C21C 528

Patent

active

058534539

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a method of processing iron-containing metallurgical residual substances washed out from offgases containing iron-containing particles in the wet process and separated in the form of sludges, wherein the sludges are dehydrated and agglomerated and the agglomerates are processed in an iron melt production process, as well as an arrangement for carrying out the method.
2. Description of the Related Art
For a direct reduction process of iron ore followed by the melting of sponge iron under simultaneous coal gasification it is known (AT-B-376.241) to separate from the reducing gas formed in a melting gasifying zone as well as from the offgas forming during direct reduction, solid particles primarily comprised of dusty carbon, to mix the separated solids particles with binder, i.e., with iron oxide dust, to form shaped coke by hot-briquetting and to subsequently recycle the shaped coke to the melting process.
However, in doing so it is disadvantageous that due to the introduction of iron oxides reduction work must be done within the melter gasifier to reduce the iron oxide, thereby withdrawing from the melting procedure energy required for the same and disturbing the process occurring within the melting gasifying zone. Furthermore, so-called hot-briquetting is an expensive solution in terms of investment and operating costs.
From DE-A-41 23 626 it is known to agglomerate metallurgical residual substances of mixed consistencies by using binders, slag formers and reducing agents, and to introduce the agglomerates into the upper burden region of a melting aggregate, preheating and drying of the agglomerates being effected in that burden region of the melting aggregate. The burden passes through the melting aggregate according to the counterflow principle, at first reaching a reduction zone provided in the interior of the melting aggregate and subsequently being melted in the lower region of the melting aggregate.
This known process requires much energy inasmuch as also metallic waste or residual substances have to travel through the reduction zone of the melting aggregate. A particular problem is the strength of the agglomerates, since those agglomerates are used in the green, i.e. not completely dried state, thus causing great difficulties due to disintegration, abrasion etc. in practice. When travelling through the melting aggregate according to the counterflow principle, damage to the agglomerates resulting from pressure an impact forces may cause a high portion of said agglomerates to be discharged from the melting aggregate by the offgas. For this reason, the process disclosed DE-A-41 23 626 is difficult to realize in practice. There would have to be produced agglomerates having high strengths to be preserved even with a high temperature range, which, again, would be very demanding, and, in particular, would require the use of high-quality and accordingly expensive binders.
From AT-B 380.901 is known to convey metal-oxide-containing metallurgical dusts through a rotating tube along with carbon-containing material, to reduce the same in a hot zone of the tube thereby forming sponge iron and to change said sponge iron into a converter as a substitute for cooling scrap. This method has been successful with metal-oxide-containing metallurgical dusts, yet calls for additional apparatus and process-technological expenditures with a view to the adjustment of a reducing atmosphere. Moreover, only simple metal-oxide-containing metallurgical dusts can be processed by to this method; but such method does not provide for the charging of dusts containing major amounts of metallic iron.
A method of the type initially described is known form EP-A-0 623 684. This enables the complete and energy-saving processing of waste and residual substances from the metallurgical industry in a process for the direct reduction of iron ore to sponge iron and melting the sponge iron in a coal gasification zone, wherein it is necessary to collect the waste and re

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