"Memory loss" during mineral processing: Application to base metals traceability

Abstract Traceability of concentrates is required to introduce transparency in the trade of raw minerals. In this context traceability may be considered as a kind of inversion process: studying the product sold (i.e. the concentrate) in order to identify the original ore, in terms of ore deposit-type and if possible, location. The difficulty of making this inversion from concentrate toward bulk ore corresponds to the “memory loss” of the crude ore which occurs during mineral processing. Based on textural characterization and the chemical composition of the material at different steps of processing, as well as the minimum residence corresponding to each step, an estimation of this “memory loss” is proposed and the relations between memory loss and global kinetic rate of flotation are established. “Memory loss” calculations are applied to the Neves Corvo plant. Throughout the process, the parameter of memory loss increases respectively from 0 to 195.06 for Cu; 0 to 46.15 for Zn and 0 to 0.43 for Fe. The “global memory loss”, namely as the “experimental memory loss”. For the Neves Corvo plant at the moment of the study this “experimental memory loss” was 14,146 min for Cu, 3408 min for Zn and 36 min for Fe. The results show that “memory loss” is greater for Cu than for Zn, thus emphasizing the importance of secondary elements for traceability purposes.