Chapter 19 - Advances in Gravity Gold Technology

Abstract

Gravity separation relies on different specific gravity of minerals and their relative motion under gravity and drag forces. This chapter describes units, circuits, and strategies that are used to recover gravity-recoverable gold (GRG) from very high-grade gold particles and from sulfidic particles with low-grade gold content. Although low efficiency and advent of newer carbon-in-pulp and carbon-in-leach processes had seen a reduction in reliance on gravity as primary means of concentration, more reliable gravity units in combination with intensive cyanidation have heralded a return to gravity recovery. Beginning with the economic consideration of the existing semicontinuous and continuous centrifuge technologies for the GRG recovery, this chapter discusses dominant factors with modeling and analysis of processes for the optimization of gravity circuits. Conditions for high table recoveries from traditional table-based gold rooms where cyanidation is impossible or undesirable are examined. Intensive cyanidation is the preferred route in virtually every case where cyanide can be utilized. The two batch-intensive cyanidation units, namely the Consep Acacia and the Gekko InLine Leach Reactor, constituting the majority of the gravity recovery installations around the world are critically examined. The chapter lays down the fundamental rules for measurement of unit efficiency of any concentrator in a gold circuit and concludes with future trends.