Characterization by XRD and electron paramagnetic resonance (EPR) of waste materials from “Cerro Matoso” Mine (Colombia)

Materials from a mining process, in which ferronickel metal extraction is the principal aim, were studied. The residual solid (scum) obtained in this process leads to large-scale accumulation of a vitreous material (pollutant) which creates an environmental problem. These materials were characterized by EPR, X-ray diffraction and X-ray fluorescence. The results indicate that the analyzed solids are rich in Fe2O3 and NiO among other oxides. The scum material shows diffraction signals corresponding to the minerals enstatite (pyroxene) and α-alumina. Moreover, the scum EPR analysis showed a broad line around g = 2.1 corresponding to Fe3+ clusters in a complex glassy matrix. An analysis of EPR at different temperatures was also performed. The objective of this work, as a first exploratory stage, is to develop a better understanding of the residual solids in order to identify potential applications.