Juergen Antrekowitsch

Abstract:

Huge amounts of low-quality secondary zinc oxides are produced by the recycling of steel mill dust or other zinc-containing residues. Due to different impurities the utilization of secondary zinc concentrates, such as waelz oxide, is currently limited to primary zinc industry, undergoing the whole process chain from roasting to winning electrolysis or alternatively solvent extraction and electrolysis. The paper discusses the background of the necessity of purification steps like roasting or solvent extraction as well as the disadvantages of these procedures. Furthermore, opportunities of how to bypass such steps and by doing this, give more value to the secondary zinc oxides, are described. In this special field, Montanuniversitaet Leoben was able to develop some important procedures whereof one is currently patented. Focus on the investigations was especially on the Zinc-Iron separation and the removal of fluorine-containing compounds. Results of various trials improving the zinc oxide quality are summarized and a discussion of economic aspects is performed within the paper. Also included is an evaluation of the world wide potential and an outlook of possible implementations of developed concepts.