Measuring level of horizontal boundary layer for level control of multiple phase mixture in flotation cell - directing ultrasound at predetermined angle in defined region and sensing components reflected from boundary between phases.

摘要

A defined vertical region (7) of the mixture is subjected to ultrasound from a transmitter (3) at a defined angle of incidence ( beta ). The reflected component of the ultrasound is received by a receiver (2) and quantitatively evaluated to determine the height of the boundary layer (20) within the vertical region. The angle of incidence is below 60 deg., pref. above 48 deg., and esp. between 52 and 55 deg. The frequency of the ultrasound is between 0.5 and 4 MHz, esp. between 1 and 2 MHz. ADVANTAGE - Enables reliable measurement of boundary layer height eg avoiding effects of diffusion etc. which affect propagation time.