Measurement and computation of powdered mixture permittivities

The permittivities of pulverized samples of coal and limestone were measured over a range of bulk densities at 11.7 GHz and 20°C, and were used, along with particle densities, determined by pycnometer measurements, and the Landau and Lifshitz, Looyenga dielectric mixture equation to determine the solid material permittivities. Subsequently, similar measurements were taken on a 35%-65% coal-limestone mixture, and the Landau and Lifshitz, Looyenga equation and the Complex Refractive Index dielectric mixture equation were used to calculate the permittivities of powdered coal, limestone, and the 35%-65% mixture at various bulk densities. Results compared to the measured permittivities showed that the Landau and Lifshitz, Looyenga equation provided much better estimates than the other equation, with errors of 0.15% in predicting the dielectric constants of powdered coal, 1.4% in predicting the dielectric constants of powdered limestone, and 0.5% in predicting the dielectric constants of the coal-limestone mixture