The Circular Economy Challenge: Re-use of processing granite wastes for REEs-recovery: preliminary results

Chemical and minero-petrographic analyses by ICP-MS, XRPD, and SEM-EDS have been performed on scraps from the industrial processing of granite. The work aims to study the optimization of industrial processes by reusing the feldspar-treated waste material to recover Critical Raw Materials in the view of economic circularity and sustainable mining. The material used for this work derives from Montorfano quarry wastes (Piemonte, Italy). The ICP-MS analyses on the 1.2 to 0.1 mm fraction discarded after magnetic separation of granitic material for pure feldspar production show enrichment in Rare Earth Elements (REEs), mainly Ce, La, Nd, and Y. The XRPD and SEM-EDS analyses indicate that monazite, allanite, and xenotime are the main REE-bearing minerals, commonly locked within phyllosilicates. The results suggest that a further grinding on the unprocessed material is probably required to enhance particle liberation. Comminution to a particle size smaller than 0.1 mm, will lead to a more effective concentration of REEs minerals during magnetic separation.