PASTE SUPPLEMENT 2019
Pipeline designed for deposit free
operation at lowest design flow rate
Nominal flow
0.046 kW/t/km
Maximum flow rate 0.067 kW/t/km
Table 1: Specific energy consumption for
different design approaches
discussed in more detail below.
The authors are familiar with several tailings
pipelines which operate reliably with a deposit.
This new design approach has the potential to
reduce the capital and operating costs of tailings
pipeline systems.
Pipeline designed for deposit free
operation at nominal design flow rate
0.030 kW/t/km
0.044 kW/t/km
pipelines have been designed operated in
turbulent flow but there are many examples of
slurry pipelines operating in laminar flow.
Paste backfill distributions operate in laminar
flow due to the high mixture yield stresses
(typically above 300 Pa). In general, there are no
instability issues in the operation of these
pipeline systems although there are cases where
solids build-up on the pipe invert has been
observed for yield stress values around 200 Pa.
There are several tailings pipelines operating
successfully in laminar flow as shown in Figure 3.
However, the wide-spread adoption of this
approach has been limited by our incomplete
knowledge of how to design for laminar flow.
Our current understanding of the flow of tailings
Laminar flow pipeline operation
Tailings pipelines are increasingly operated at
higher solids concentrations to help mining
operations conserve water and energy. As solids
concentrations increase, there is a greater
likelihood the pipeline will operate in laminar flow
due to the higher tailings rheology. The tailings
yield stress and slurry density largely govern the
transition from the laminar to turbulent flow. As
illustrated in Figure 2, it is practical to operate in
the turbulent flow for only moderate yield stresses
(ie a Bingham yield stress of 40 Pa requires that
the pipeline is operated above 4 m/s to remain in
turbulent flow).
To avoid potential instabilities associated with
the laminar flow (Cooke, 2002), historically slurry
Figure 2: Laminar to transition (typical copper tailings)
When the best
solution doesn’t
exist, we create it.
We have designed and built some of the most
technically challenging tailing dams in the
industry and have done so with a focus
on safety and sustainability.
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