Frequency Dependence of the Dielectric Properties of Coai — Part II

Abstract

The dielectric properties of 18 pulverized coal samples, including run-of-mine and light and dense fractions, were measured over the frequency range from 1 MHz to 12 GHz at 22°C and are presented graphically. For Iowa coal, the dielectric loss factors of dense fractions containing most of the pyrite tended to increase noticeably as frequency increased. The loss factors of dense fractions of eastern coal (Kentucky and Ohio) tended to decrease with increasing frequency and then rose somewhat as frequency approached the microwave range. Data are also presented on the dielectric constant as a function of bulk density. Plots of the square root of the dielectric constant vs. bulk density resulted in straight lines that can be extrapolated with confidence to the coal particle density, thus providing estimates for the dielectric constant of the solid coal from measurements on pulverized samples.