Recycling of by-products from metallurgical processes - a contribution to a sustainable metal production

For many years, by-products of different metallurgical processes have not been considered as a potential source for metal recovery. The reason for this can be found in technological as well as economical aspects or simply because of missing know-how and the focus on only one product. Since a few decades the situation has changed and by-products like slags, sludge and dust are taken more and more into account as a possible secondary resource. Nevertheless, recycling rates are still low and improvement of relevant processes or the development of new concepts is strongly required. Especially by-products out of Zinc-, Copper- and Lead industry are well known to carry various base and minor metals which could be recovered, leading to a more efficient and sustainable metal production. This paper gives an outline on the potential of such materials dumped as well as continuously produced ones. Besides an overview of the characteristics of the by-products regarding metal content and mineralogy, statistics on available amounts and valuable metals, possible to recover under economic considerations, are presented. Finally, the availability of possible treatment concepts and processes or the necessity for new developments is discussed. Summarizing, the paper tries to highlight, how more emphasis on the recycling of by-products out of metallurgical industry could have a positive effect on the metal supply, especially in countries with low primary resources, and how such an approach contributes to the principle of circular economy.