Every year several million tons of heavy metal containing residues are generated by the metal producing and processing industry worldwide. In the most cases this “residues” – slags, dusts und sludges – with a partly high metal content become a technical easy and reasonable dumping. By the time fluctuating material prices and availability on the global market as well as the intensified legislations force the metal industry to deal more and more with the topic recycling. Most of the existing recycling systems are low-end processes with a low economical and ecological optimization grade without knowledge of any basic principles. A wide-ranging characterization, reaching from simple mean density measuring over verification of the softening properties by heating microscope to element- and structure analysis by means of SEM, plays an important rule for fundamental knowledge in this area. Studies on real steel mill dust show, that already small differences concerning particle size, mean density or gas composition cause noticeable changes at the softening- and melting behavior, which are important for the operating mode of a recycling system. For detailed information about e.g. sintering procedure, evaluation of a parameters influence etc. and in view of the fact that real dusts are very complex structured its necessary to create synthetic mixtures of them, which allow further analysis in detail. With the information of all these data a model for optimization of existing or new processes should be generated.