Study on Filtering Hydrocyclones Operating with Concentrated Non-Newtonian Suspensions

Abstract

Hydrocyclones are devices used to separate a discrete phase (solid or liquid) from a continuous liquid phase. Although this partition process is simple and versatile, there are limitations when separating concentrated suspensions with high viscosity. By replacing the cylinder or cone walls of hydrocyclones by a permeable wall, our research group developed the so-called filtering hydrocyclones. Although previous studies have shown that filtering hydrocyclones have a better performance than conventional devices of the same geometry, they were performed with diluted Newtonian suspensions. Thus, the aim of the present work is to evaluate the performance of a filtering and a conventional hydrocyclone of the same geometry operating with concentrate suspensions with pseudoplastic rheological behavior. The geometric relationship of these hydrocyclones was obtained in a previous optimization study that aimed at maximizing overall efficiency in aqueous diluted suspensions; this high-efficiency device is known as MOEH. When operating a pseudoplastic fluid with a behavior index equal to 0.6536, there was a 48% decrease in the efficiency of the MOEH hydrocyclone. The MOEH experiments performed with a pseudoplastic suspension containing 9.5 wt % of solids and 0.6 wt % of carboxymethyl cellulose achieved an Euler number of 1108, a split ratio of 44%, and an overall efficiency of 47%. However, the average results demonstrated that the operation with the newly designed filtering hydrocyclone, called MOEH-CoF, led to an Euler number about 10% lower and an overall efficiency about 5% higher than that obtained with the conventional device. The findings of this study can lead to a better understanding of solid–liquid separation in the petrochemical, mineral, and food industries, which generally works with concentrated non-Newtonian fluids.