Electrical conductivity measurements and the nonhomogeneous settling behavior of aqueous suspensions of barite

Using electrical conductivity measurements to monitor the local concentration of solids indirectly in settling tests is a practice already explored in the literature. However, since suspended particles may comprise a mixture of solids, a new suspension preparation methodology and calibration procedure were proposed to eliminate the influence of soluble materials on conductivity measurements. This article investigates water-barite suspensions of 10%, 15%, and 20% v/v in solids. Their settling dynamics resulted in particle Reynolds numbers and Peclet numbers always smaller than 0.0012 and larger than 2100, respectively. Particle agglomeration, multiple boundaries (layers of different maximum local concentrations), channeling (formation of flow paths or channels), and particulate stratification were some phenomena inferred from the results. Hence, this article illustrates that settling behaviors typically seen in solid-liquid mixtures of non-Newtonian continuous phase can also occur in aqueous suspensions, indicating there are still considerable challenges to understanding the process of gravitational settling.

Automated summary

This article investigates the use of electrical conductivity measurements to indirectly monitor the local concentration of solids in settling tests. A new suspension preparation methodology and calibration procedure were proposed to eliminate the influence of soluble materials. The results revealed phenomena such as particle agglomeration, multiple boundaries, channeling, and particulate stratification, indicating the challenges in understanding the process of gravitational settling.