Method and apparatus for measuring the volumetric water content of mineral and/or organic mixtures

摘要

A method and an apparatus for determining the volumetric water content of a mineral and/or organic mixture with dielectric measurements. The apparatus includes a probe body having a hollow cylinder formed of an insulating material with an annular cutting edge at a lower end. Electrodes and a temperature sensor are carried by the probe body. A bottom plate may be disposed adjacent to the lower end of the cylinder so that the cylinder and the plate define a cavity for receiving a liquid coolant. A removable cover is provided for closing the cavity to prevent rain water from entering. The method includes introducing the probe in the mixture, charging the electrodes with a high frequency electromagnetic wave so as to generate an HF field in a region of the electrodes and reflect a wave from the electrodes, measuring a complex reflection factor of the reflected wave at a temperature T.sub.1 of the mixture, cooling the surrounding mixture to a temperature T.sub.2 so as to freeze the water therein by closing the bottom the probe with the plate and inserting the coolant into the cavity, measuring the reflection factor with the surrounding mixture at the temperature T.sub. 2, determining the dielectric constant for the mixture at the temperatures T. sub.1 and T.sub.2 from the measured reflection factors with the aid of an invariable probe-specific calibration curve, and calculating the volumetric water content of the mixture from the two determined dielectric constants and the known dielectric constants of water and ice.