Removal of Impurities from Scrap and Dust.

Abstract

After presentation of the scrap situation of the last few years future developments in this situation and in scrap-quality are pointed out. The problem caused by the shredder-light-fraction is also included.The melting behaviour of scrap with a special hint to the layer formation of the melt on the scrap and the melting of the scrap itself is discussed, together with the problem of tramp elements and the typical behaviour of these elements, e.g. in the cupola furnace and on the quality of foundry products. Different technologies for the preheating of scrap and the diverse methods of scrap-melting as well as their future problems are discussed. The waste-gas-situation, e.g. with the emitted dust and its influence on the waste heat boiler protected by plasma- and flame-spraying, is described.Influence on the gas-quality (e.g. dioxin) and the different types of output dust in connection with the recycling, e.g. blowing into a cupola-furnace or use in the High Turbulence Mixedr–HTM unit, are considered. The enrichment of the melt, e.g. with dust with a high chromium content, or the removal of elements like Ni, Cr, Sn and Cu is discussed, as are new test campaigns to evaporate zinc and lead. The final conclusion offers some possibilities to quantify the CO2-exhaust of the different steel production-routes and hints to the problem ecological estimations.