Chapter 15 - Gravity Separation

Abstract

This chapter gives an account of gravity separation methods used in mineral refinement. Not all mineral combinations are amenable to this type of concentration technique. To determine the suitability of gravity separation processes to a particular ore type, a concentration criterion is commonly used, which is a function of specific gravity of the minerals and fluid. The chapter provides the detail explanation of this function and its uses in further processes of calculating the rate of particle settling. Gravity concentrating operations are characterized by processes that allow particles to be held slightly apart, so that they can move relative to each other and can therefore, separate into layers of dense and light minerals. The mechanism by which this inter-particular spacing is accomplished is used as a convenient means of classifying gravity concentrators. The chapter describes several processes of gravity separation, such as jigging, shaking concentration, and flowing film concentration, focusing on their types and applications. If the density of the medium lies between the densities of the two minerals, then separation becomes much simpler because the lighter mineral will float in the fluid medium and the heavy mineral will sink. Hence, separations of this kind are referred to as sink-float separation. The chapter highlights the application of this fact in separation process and discusses various types of dense medium separators, such as gravity dense medium separators and centrifugal dense medium separators. It also discusses the performance of gravity separation.