Nickel, Kobalt und Chrom sind wesentliche Rohstoffe der Stahlveredelung. Die Bundesrepublik Deutschland ist fuer diese Metalle 100 v.H. importabhaengig. Grosse Mengen von Ni, Co und Cr sind in lateritischen Erzen vorhanden, koennen aber aus technischen Gruenden von der deutschen Industrie z. Zt. nicht genutzt werden. Ziel des Vorhabens: Vollstaendige chemische, strukturelle und mineralogische Typisierung anhand von ausgewaehlten Lateriterzproben; diese in Beziehung setzen zu den bekannten und moeglichen technologischen Verfahren der Metallurgie und Aufbereitung. Untersuchung der Lateriterzproben nach hydro- und pyrometallurgischen Verfahren im Hinblick auf die Gewinnung von Ni und/oder Co und/oder Cr. Auf dieser Grundlage Bildung von Rohstoffklassen hinsichtlich der Gewinnung von Ni, Co, Cr unter Beruecksichtigung der wirtschaftlich guenstigsten Technologie.
The aim of the project is to replace the traditional cauterization surface treatment of steel press plates used up to now. The complete heat treatment is to be carried out within an inert gas atmosphere in order to eliminate waste and sewage and to spare transport resources. The set-up of the new clean heat treatment equipment especially considers economical and ecological aspects. C.A. Picard, a middle-size company located in Remscheid Germany, processes large quantities (50 tons per month) of raw steel sheets for the production of industrial press plates. The process includes hardening and tempering of the sheets. Up to now this heat treatment takes place in exposure to normal atmosphere, that is to say: under the influence of oxygen. This process brings about the formation of a scale layer on the steel surface which has to be removed through cauterization with sulphuric and fluoric acids and water for the rinsing process. All of this generates large quantities of chemical waste that has to be disposed of properly. The cauterization process can be avoided by introduced a new clean technology, namely the treatment under the influence of an inert gas atmosphere. The technological feasibility of the project is given. However, due to the large sizes of the steel sheets (1800 mm multiply by 5500 mm multiply by 2,5 mm), it takes special efforts to construct the equipment in such a way that the quality of the produced press plates remains intact. By avoiding cauterization, this new technology does not only contribute to unburden the environment and to stop the generation of chemical waste water, but it also considerably saves energy. The omission of the troublesome steel transport to the off-premises cauterization treatment and the optimal use of energy within the new installation through heat recycling additionally reduce the carbon dioxide emission. Especially in the region around Remscheid with its innumerable small and middle-size companies (an enormous production of saws and saw blades), the introduction of a new clean technology deserves exemplary status, worth being sponsored as a demonstration project.
General Information: The growing use of zinc-coated steel sheet in a variety of sectors (motor industry, consumer durables and construction industry) has led to an increase in the zinc content of home scrap, a large proportion of which is recycled in L-D steelworks. From a metallurgical point of view, the Zn coating of the scrap does not interfere with the steel production process, nor does it normally affect product quality. However, the zinc does accumulate in the process dusts. Despite their high iron content, typically around 60 per cent, these dusts cannot be recycled in the sintering plant or the blast furnace because of the zinc load without additional, usually complicated processing stages, above all owing to the risk of scaling in the blast furnace. On the other hand, the typical zinc content of these dusts of 2 per cent is too low to be recycled in zinc foundries. From the purely economic point of view, this currently requires Zn concentrations of well above 30 per cent. If the dusts and slurries from the waste gas cleaning system of an L-D converter are to be recycled internally, the zinc load must be reduced to a level that will not damage the blast furnace. The main source of the zinc in the dusts from waste gas purification is the scrap used in the converter, the Zn content of which can vary considerably. Some types of scrap are practically zinc-free, e.g. the uncoated process scrap or comparable new scrap. However, a large proportion of the scrap used, with the exception of the internal scrap arising in the finishing plants, has an unknown zinc content. This is particularly true of capital scrap. A knowledge of the Zn load per converter batch would basically make it possible to identify and hive off dusts and slurries suitable for the blast furnace. This would permit separation of recyclable and non-recyclable dust fractions, which would reduce the amount of material to be land filled or processed separately. While it is in principle technically possible to study the Zn content of metal in the scrap industry, the information would not normally be very useful, as it is practically impossible to take a representative sample in normal scrap handling practice. A way must therefore be found of reliably quantifying the zinc stream from the converter, in order to be able to determine the zinc load of the dusts and slurries from waste gas purification. The evaporation behaviour of zinc can be harnessed for this purpose, as dusts highly contaminated with zinc are driven off as soon as pig iron is poured over the scrap, or during the following first minutes of blowing, so that a reliable zinc analysis should be possible. The task is to develop a method of detecting zinc in the flue dust of the converter deduster. The objective is to measure the Zn content above a threshold value reliably throughout the process, in order to use this information to separate low-zinc from high-zinc dust fractions.