Method of measuring solid matter mass flow

A method of measuring a solid matter mass flow during conveying of solid matter-gas suspensions in tubular conduits, particularly during conveying in a dense stream with high pressure, comprises the steps of changing in a pulse mode a solid matter concentration of a solid matter-gas suspension at one location of the conduit through which the suspension flows, continuously measuring a solid matter concentration of a solid matter-gas suspension or a value corresponding thereto at two measuring locations downstream of the first-mentioned changing location and spaced from one another in the conduit, determining a difference between time points at which a difference of the solid matter concentration or the corresponding value is indicated after one another at the measuring locations downstream of the first-mentioned changing location and spaced from one another, determining a per-unit-time average value of the solid matter concentration of the solid matter-gas suspension in a conduit portion corresponding to the measuring location, generating a signal which is proportional to a quotient from the time per unit average value of the solid matter concentration divided by the difference of the time points at which the change of the solid matter concentration at the measuring locations after one another is indicated, and using this signal as a measure for the solid matter mass flow in the conduit.