Dross

Scabies ( " Dross " English), also called " dross " or, depending on melting as ash ( stannic oxide ), or slag called ( blast furnace ), produced during smelting of metals from their ores, as well as in the melting of metals or alloys thereof atmospheric or technologically -related influence. Access of oxygen caused oxide formation - sometimes called burn - in different, related by the oxygen affinity of the melt components extent. This may include, to the melt so that resting oxide dross nor the melting primarily adhering impurities, or process-related reaction products with generally lower density than the melt and therefore, even ascending to the bath surface, otherwise expelled by a " flushing " melt treatment.

As the oxides of the melt constituents, although are of lesser density, but have a higher melting point than that itself is that of the melt dross lying generally highly viscous, which favors the inclusion of melt components.

Melting must be freed before the re-use of process waste, " purifies " or " abgekrätzt " (see mold casting and melt treatment as well ). In this respect, means the occurrence, such as the presence of dross always a loss of metallic melt. This applies to a smelter, as well as for recycling plants and foundries and gives the slag processing, such as the dross recycling, within the framework of the offered sustainable use of metallic raw materials, a field of activity.

Dross formation by oxidation can be avoided by vacuum melting. The cost of this technique can be use mostly for high-quality melting, like precious or rare metals.

• Metallurgy