Characterizing Flocculated Suspensions with an Ultrasonic Velocity Profiler in Backscatter Mode

This paper reports on use of a commercial ultrasonic velocity profiler (UVP) to monitor changes in concentration within complex suspensions. A calcium carbonate (CaCO 3 ) nuclear waste simulant was used with a high molecular weight anionic polymer flocculant to produce varying suspension environments. 2 MHz ultrasonic transducers were used in both in situ and ‘remote’ configurations to extract backscatter voltage profiles of the suspensions, where the remote probes highlighted the ability of the UVP to analyze through pipe walls. Calibration was achieved by measuring logarithmic function of the backscatter voltage (G-function). Here, profile gradients averaged over selected distances and concentrations are used to measure particle attenuation coefficients. Both in situ and remote probes gave comparable results, where addition of polymer flocculant led to a decrease in the relative attenuation, due to lower viscous absorption with particle aggregates. Flocculated aggregates largely followed estimation from spherical scattering theory if aggregate density is taken account of. Attenuation constants can be used to determine single and dual inversions to measure concentration profiles in nuclear wastes.