A guide to leading practice sustainable development in mining

Tailings Management During Mining Operations
The Business Case for Leading Practice in Tailings Management
The business case for applying leading practice in tailings management is compelling.
The failure or poor performance of a tailings storage facility can have a profound
impact on the corporate bottom line. In extreme cases, tailings storage facility
failures have severely eroded share value as the market anticipates the cost of
cleanup, suspension of operations and possibly mine closure. This is in addition to
the loss of company reputation and the loss of a social licence to operate. The cost
of leading practice tailings management systems is more than offset by the reduced
risk of a major incident.
Conventional economic analysis can lead to minimising initial capital expenditure
and deferring rehabilitation costs. Net present value analysis discounts the current
cost of future expenditures on closure, rehabilitation and post-closure management.
Therefore, if this short-term economic perspective is taken, without taking into
account the longer-term social and environmental costs, there is little motivation to
invest more substantially at the development stage to avoid or reduce expenditures
at the closure stage. There is a number of reasons, however, for applying leading
practice at the earliest stage of development, and in designing and operating
the tailings storage facility (TSF) to optimise closure outcomes. Designing and
operating for closure of a TSF can avoid significant earthworks expenditures to reestablish
stable landforms and drainage systems. Progressive rehabilitation, where
possible during operations, enables rehabilitation work to proceed while there is
an operational cash flow, and management and resources available. Progressive
rehabilitation can also reduce the cost of financial assurance required by regulatory
agencies. Leading practice tailings management will also minimise the time required
for post-closure monitoring and maintenance.
Tailings and risk
Tailings are an inevitable consequence of most metalliferous mining operations as
well as certain coal mines and industrial mineral operations. The management of
a TSF present mine managers with some of their most challenging sustainability
issues. Indeed many premature mine closures are caused by failure of the TSF.
Many companies have implemented innovative leading practices to reduce the risk
of a failure of a TSF or the risk of negative environmental and community impacts
from dust etc. In recent times for example there has been an increasing use of the
Robinsky or Central Thickened Discharge method of tailings disposal. Sunrise Dam
gold mine (SDGM) located 55 km south of Laverton in WA, commenced operation
in 1997. A “paddock style” TSF for conventional medium-density tailings slurry
was commissioned for the design throughput of 1.5 Mtpa. One downstream raise
was carried out in 1998 prior to decommissioning in 1999. Design throughput was
scheduled to increase from 2 Mtpa in 2000 to 3 Mtpa in 2003, and it was decided to
thicken the tailings to a higher density and change to the central thickened discharge
(CTD) method of tailings disposal in a new location. The design area of the CTD TSF
in 1999 was 300 ha and eventually increased to 330 ha (see LP Tailings p.55).
A GUIDE TO LEADING PRACTICE SUSTAINABLE DEVELOPMENT IN MINING 117