TAILINGS EQUIPMENT
An FLSmidth tailings thickener installation
according to FLSmidth’s global best practice –
that is applied when erecting these large
thickeners.
“When supplying a thickener, part of our
engineering deliverables includes an
installation methodology for the site contractor
to follow, to make sure that they implement
each stage correctly,” he says. “FLSmidth also
provides a technical installation expert from the
most suitable of our global offices who visits
the site at appropriate intervals to advise and
inspect.”
He further emphasises that the forces
demanded within large thickeners also makes
the choice of gearbox drive
much more important.
“Smaller thickeners can
usually be designed with
planetary gearbox drives –
available from a number of
OEMs,” he says. “With really
large drives requiring higher
torque, however, we prefer to
use our own ring-gear Dorr
Oliver drives which can reach
much higher torque values
than planetary drives. The
ring-gear drives are also
more able to handle axial
and radial loadings on the rakes.”
Long term fixes are best
Tailings are not the easiest or cleanest thing to
deal with and McLanahan argues that he best
way for producers to deal with tailings is to
answer the question: “What do you envision as
the long-term solution?” This will often depend
on the characteristics of the tailings. If the tailings
are comprised of relatively coarse particles (+38
microns) then the answer may be as simple as
pumping them to cyclones for recovery and dam
building, with the fine cyclone overflow being
impounded behind the dam. “This method has,
for many decades, been employed to both
collect/store tailings, as well as to clarify water for
reuse in the process plant. Make sure it is a long-
term fix and not a short-term fix. Most short-term
fixes don’t fix the problem and create more
downtime and loss of profits.”
The company adds: “What could possibly be
cheaper than to dig a hole or build a dam and
create a space for the waste generated by
processing activities? Two of the most frequent
problems brought up are ‘we don’t have enough
screens’ and ‘our ponds are running out of
space.’ Dredging a pond to create more room for
incoming tailings can become very costly. An
additional pond could be opened, but space
and/or permitting might not be possible.
Additionally, there is the potential to cover
reserves that you may need and the loss of
process water due to evaporation or percolation.”
Besides the costs associated with the pond
solution, there are also risks. Risks that include
placing people on or near the water while
maintaining the pond or building higher dam
structures. Impoundment failure is another
possibility that should weigh heavily into any
risk analysis.
Thickeners, also known as clarifiers, recover
immediately reusable process water, as well as
extract fines and other materials from water.
They can be used in a variety of mineral
processing applications, as well as in industries
such as wastewater management and
aggregates. Thickeners are especially
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