On-Line Viscometry in Particulate Processing

Abstract

On-line viscometry of suspensions is very difficult compared to viscometry of pure liquids. The problem arises because of the unstable nature of the suspensions, particularly when coarse and fast settling particulates are present. Several attempts have been made in the past in which special mixing chambers have been designed to maintain slurry homogeneity while measuring viscosity. However, the credibility of these instruments are questioned by many authors, as quite often the same systems measure different rheological behavior for similar suspensions. In most of the designs suggested in the past, solving one of the problems of suspension viscometry introduces new problems. For example, agitation can keep the solids suspended, but it can also seriously affect the sensitivity of the viscometer. In this article the problems involved with three different types of viscometers (rotational, capillary, and vibrational) which have been used for measuring viscosity of suspensions, are discussed.