Electrical Resistance Tomography Applied to Slurry Flows

*Lachlan Graham*

## **Abstract**

Electrical resistance tomography (ERT) is used to investigate a variety of slurry flow applications including pipe flow, mixing tanks, and thickener feed wells. Transparent liquids such as Carbopol polymer solutions and water are often used to allow for visualization of slurry flows, but ERT can provide data about solids behavior when the liquid phase is transparent or when it is opaque. The state of suspension of solids using ERT is often useful even when the technique is not a primary requirement of a test. The chapter introduces ERT from the point of view of a user in a research environment, but with flow scenarios relevant to industrial applications in mineral processing. Relevant literature concerning slurry flow applications of ERT is reviewed. The basic theory of ERT will be presented together with a discussion of the image reconstruction problem which is a topic of research activity in the slurry transport community. An overview of ERT applications in slurry pipe flow and mixing tanks will be presented. Examples of the application of ERT to pipe flow and tanks will be discussed in detail, including practical experiences with integrating ERT into slurry pipe and tank rigs.

**Keywords:** electrical resistance tomography, slurry flow, pipe flow, visualization, slurry pipe applications

### **1. Introduction**

Electrical resistance tomography (ERT) is a well-established technique for obtaining the cross-sectional distributions of solids in slurry pipe flows and tanks, among other uses. Basic details of the ERT technique are given in [1] and many other publications. ERT for process applications was discussed in [2]. Previously, ERT had been extensively used in geophysical applications as well as being explored for use in biomedical imaging. The basics of design and implementation of ERT technology suitable for process applications are presented in the paper. The authors specifically mention mixing scale-up as an application for ERT and introduced the 1.5-m diameter tank at UMIST (University of Manchester Institute of Science and Technology), which was equipped with a full set of ERT electrodes covering most of the tank wall. A recent book describing many forms of tomography for industrial applications, including ERT, is [3].

The present contribution describes the basic principle of ERT as applied to slurries focusing on pipe flow and mixing tanks as conducted by the Fluids Engineering Team at CSIRO.
