Effect of grinding conditions on oil shale surface: FTIR analysis

Abstract

Grinding is an indispensable process in many industrial plants. Nonetheless, the ground products may pass through the surface and/or undergo structural changes that may affect subsequent processes. In this study, the changes in the oil shale surface during its dry grinding in a ball mill were followed by Fourier-transform infrared (FTIR) analysis under different grinding conditions such as grinding time, ball type (i.e. ceramic or steel), and number of balls. Moreover, the generated heat limits during grinding were revealed by correlating the change in surface function groups of the ground products with those of conventionally heated oil shale samples in a furnace. The results indicated that the more intense the grinding action, in terms of the number or size of grinding balls and the grinding time, the higher the variations in the ground products’ FTIR spectra, indicating the higher the surface oxidation of oil shale. More interestingly, correlating the FTIR spectra of the heated samples with those of the ground products indicated that the temperature inside the mill does not exceed 150 °C.