IM 2020 September 20 | Page 61

PASTE & TAILINGS 2020
failure, and how is the social license to operate
affected.
As part of the EcoTails ® project FLSmidth
developed the 5 x 3 filter which can filter
30,000 tons per day of flotation tailings
get a permit, what is the cost of water for the
mine, what is the risk and consequence of a
IM: Lastly, can you give an example of a filtered
tailings project that FLSmidth has been involved
in that highlights your capabilities in this area?
TW: I think potentially the most important
project that highlights FLSmidth’s capabilities in
evaluating the complete tailings and mine waste
flowsheet is our involvement in the EcoTails ®
project with Goldcorp. All of the topics discussed
here were evaluated for multiple flowsheets and
multiple types of dewatering equipment. In
addition the material handling and placement of
the tailings and mine waste was evaluated to
come up with a solution that has real value for all
mines but especially for large open pit mines. IM
deposition methods. Combining those two
advantages means it is cheap. But of course the
ability to hydraulically flow and self-level is also
what causes the issues if there is a dam failure
as the slurry hydraulically flows
downhill. Saturated thickened tailings flow
much easier and farther than saturated
pressure filter cake. Not only is saturation
important but how much water is available is
also important on how far the material will flow.
Think of water like a lubricant. The more of it
there is the easier it allows the solids
to flow. Reclamation is made easier also when
there is less water as you can get on the TSF to
do the work. If it is a slurry TSF you need to
dewater the area so you can do the work.
IM: Is water recovery also a major aspect in
opting for filtered versus thickened tailings?
TW: Yes, the difference between a 0.15 water
ratio for filtered tailings and 0.50 for thickened
tailings means that for a 100,000 t/d mine that
you save 35,000 m 3 of water per day. At $4 a
cubic metre that is $140,000 per day or ~$50
million per year. You see these kinds of water
costs where water has to be desalinated and
pumped to a high altitude, like in Chile and
Peru.
IM: Why do you think filtered tailings have
received less attention than paste tailings in
recent years?
TW: I think the main reason is the difference in
costs between the two solutions. As we
discussed you need a thickener for any filtered
tailings solution. This means that for a filtered
tailings solution you must have an additional unit
operation. There is no way around the fact
that adding an additional unit operation is going
to cost more money in CAPEX and OPEX. The
question then becomes is there enough value to
justify that cost. Value can be determined by
what regulations are required, how fast can you
We had a ground man that did nothing but
constantly clean up; that was his job. Now we
don’t have a ground man. We haven’t shoveled
the tail wheel or cleared anything out from
under the conveyor since we installed these
cleaners. I’m amazed by CleanScrape ® , it’s
been on for a year now and I haven’t touched it.
This material is sloppy, it’s just muck that we’re
running. And then you look at the return side of
the belt and the proof is right there. Absolutely
phenomenal. Try it out for yourself, it’s amazing.
– Trey Poulson | Fairplay Gold Mine, CO, USA
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SEPTEMBER 2020 Supplement | International Mining P9