17 - Management of coal tailings

Abstract

This chapter covers the management of coal tailings, describing the conventional dewatering and management of coal tailings, alternative coal tailings dewatering and management, dominant tailings Guidelines and Standard, coal tailings rehabilitation and closure with some examples, and conclusions and future trends. The focus of the chapter is coal tailings management in Australia, and in the dominant Bowen Basin and Hunter Valley Coalfields in eastern Australia in particular. The conventional approach involves limited dewatering of the coal tailings, their transport using centrifugal pumps, and disposal to a surface or, increasingly to a completed ramp or open pit. Over the last several decades, the Australian coal industry has employed a range of alternative approaches to tailings management. These have included tailings deposition in small cells constructed using coarse reject, the use of belt-press filters, the pumped codisposal of coal tailings with coarse reject, the use of on-off tailings cells that are harvested, and dewatering coal tailings using solid bowl centrifuges. Several of these alternative approaches involve coal tailings and coarse reject in combination, and some involve final deposition within spoil piles. The chapter goes on to discuss the dominant CDA and ANCOLD Tailings Guidelines and the recent Global Industry Standard on Tailings Management, which are risk-based and seek to minimize the consequences of all credible failure modes of tailings facilities. Postclosure, coal tailings storage facilities are required to be safe, stable, and nonpolluting, and able to support the agreed postclosure land use or ecological function. The chapter describes difficulties in achieving these aims, guiding regulations, and in-pit coal tailings facilities.