The capacitive method is based on the high permittivity of water compared with most of the dry materials. It was found A microwave based system has been developed for the that capacitive measurements are also influenced strongly by continuous measurement of the moisture in non conducting the electrolyte content similar to the conductive methods. materials. The system was implemented on conveyor belts carrying coarse cod. To obtain a reliable mxisurement for this The infrared reflection technique, based on the characteristic application, several other factors that influence the microwave absorption by water, is applicable for moisture determination measurement technique had to be investigated. These factors of black coal in spite of its high absorbance. However, the are among others: the mass per unit area, the ash-content and influence of particle size is an order of magnitude greater the temperature. The measurement of these factors make , . ompared with the microwave method. It is also possible the general characterization of the coal, which is disadvantageous that only a small part of the material stream important for optimizing the utilization of the cod in many is sampled. different applications.