Automated mineralogical analysis of secondary raw materials – challenges and pitfalls

Secondary raw materials are becoming increasingly more important in ensuring the stability of critical metal supply. Ashes, slags, dusts and other industrial residues are produced in large quantities.
Precise and accurate chemical and mineralogical data, knowledge of distribution of valuable and deleterious elements in the single phases as well as information about homogeneity and grain size distribution of the minerals are crucial for the development of new extraction technologies.
Gaining these essential information can be achieved by using SEM-based automated mineralogical analysis. However, the large particle size range, the dominance of very small grain sizes (< 5 µm) and the diversity of phases are challenging for the analysis. Furthermore, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. Initial results of ash and slag samples will be presented and evaluated.