Relaxações dielétricas do sistema carvão-pirita

Abstract

The dielectric properties of coal-pyrite mixtures with concentrations varying from•0 to 50% were measured in a frequency range varying from 30 Hz to 100 KHz. The measurerrnts were carried out first under humid atmospheric conditions and later with 1 g of water mixed with every 60 g of coal-pyrite mixtures. Under the atmospheric conditions relaxations in frequencies below 1 KHz was observed for mixtures containing 30 or more percent of pyrite; with addition of water, relaxations were observed in all mixtures from 100 KHz down to the lowest frequencies. Relaxations in mixtures with or without water could be adjusted up to certain limits by using the method adopted by Davidson-Cole. For mixtures with water and 40 to 50% of pyrite the relaxations aproximate the behaviour as suggest by Debye. Discrepancies observed between the experimental and the theoretical curves seem to be due to the presence of electrode polarization in volume, and to a significant ohmic conduction of electricity at the low values of frequency.