Boshoff, JCJ & Kleinhans, T 2009, 'Improved Water Consumption at the Sishen Tailings Storage Facility Complex', in R Jewell, AB Fourie, S Barrera & J Wiertz (eds), Proceedings of the Twelfth International Seminar on Paste and Thickened Tailings
, Australian Centre for Geomechanics, Perth, pp. 161-166, https://doi.org/10.36487/ACG_repo/963_19
Tailings material from the existing Sishen plant is currently being deposited on four individual tailings dams.
The solids concentration of the tailings can not be increased by means of thickening as the current process
can not deal with flocculant. Decant water from each tailings dam is transferred into two seepage sumps via
gravity penstock decant systems from where the water is returned back to the Sishen plant. The water
balance and water recovery for the current Sishen tailings disposal system is not optimised and the dams are
used on a random basis for the storage of storm rainfall and excess process water. The deposition cycle on
the dams in terms of layer thicknesses and cycle times was not optimised. Significant evaporational losses
therefore occur which is not ideal for an operation in such an arid climate.
The Sishen Expansion Project (SEP) involves the establishment of a separate process plant. Tailings
material from the SEP plant will be disposed off in the cross area in between the current four individual
tailings dams. One leg of the cross area will be closed off at a time and filled with SEP tailings materials. It
is planned to fill the four legs of the cross area over a period of approximately 10 to 12 years. The SEP will
increase the current water consumption and has prompted the optimisation of the tailings dam complex
Once the cross area is filled up to the same level of the four individual tailings dams, the four dams and the
filled cross area will be consolidated into one single dam with four operating paddocks. The principle of
operating four paddocks with optimised deposition strategies and small pool areas contributes towards
improved water recoveries. The method of tailings disposal and dam operation also remains the same as per
the current operations.
A return water dam (RWD) will be constructed as part of the SEP. The RWD will consist of an operating
compartment capable of containing five days operational storage. Any run-off water from a 1:50 year
24 hour rainfall event on top of the tailings dams will be contained on top of the tailings dams and decanted
in the shortest period of time possible.
This paper will discuss how the water consumption of the Sishen tailings dam complex was improved by
conventional means other than thickened tailings. The improved water consumption over the life of mine will
also be discussed.