Chapter 17 - Comminution Circuits for Gold Ore Processing

Abstract

This chapter considers comminution for gold ores, starting with breakage induced in the blasting process, continuing through primary crushing, primary milling, and secondary milling. Both technical and operational considerations are reviewed; while gold ore comminution is broadly similar to like-sized circuits for other mineral processing applications, specific considerations applicable to gold circuits are highlighted. Although significant production of gold comes from both heap leaching (including run-of-mine and crush-for-leach) and milling operations, milling operations are present at 18 of the 20 largest producing gold operations in the world. As such, the majority of this chapter targets discussion of milling operations, in particular, the various configurations of primary milling circuits including crushing, autogenous/semiautogenous, and crusher/high-pressure grinding rolls circuits. Further, the capital and operating costs, the complexity of milling operations, and the risk and opportunity from good circuit design and operation merit focusing on milling operations. Elements specific to gold ore processes, such as dry grinding for roasting operations, security considerations for gold milling, reagent additions, and integration of mineral processing steps in the comminution circuit, are also addressed.