To control the moisture content of bulk products of the mining and chemical industry it is preferable to use infrared and high-frequency methods, providing maximum sensitivity of the output parameter of the measuring instrument from the moisture content of the material.

Let a spherical conductor of radius r be placed at a distance d from a plane-parallel layer of thickness a with dielectric constant ε, or a capacitor consisting of two such conductors located at a distance l from each other. Let us consider the problem of determining the self (first case) and mutual (capacitor) capacitance of such a system (second case).

High-frequency moisture meters have been successfully used to measure the moisture content of a number of beneficiation products. However, when measuring the moisture content of bulk materials having low Q-factor (e.g., metal-containing filter cakes), difficulties arise in developing circuits that allow the measurement of the electrical capacitance of the material under low Q-factor conditions. ...

The electrophysical characteristics of beneficiation products entering mining and processing plants from different deposits are, as a rule, heterogeneous. It is obvious that with such a difference in dielectric constant and electrical conductivity of moist charges, high-frequency moisture control is ruled out.

In the course of long-term operation of continuous moisture-measuring systems developed at the Department of Automation of Production Processes of the Leningrad Mining Institute, a significant influence on their operation was found to be exerted by the wear of the base and working electrodes of the sensor. ...

When constructing temperature-compensation circuits in capacitive moisture-measuring systems, it is necessary to take into account that the change in the temperature coefficient of capacitance (TCC) of the material being monitored may have a different character depending on its moisture content. Besides this, the circuit must automatically change the temperature-compensation coefficient in accordance with the change in the TCC.

In a discrete moisture-measuring system of the F-meter type, the whole set of measurements of the capacitive component is brought to the calibration temperature in accordance with the temperature coefficient of capacitance of the material being measured...