PASTE SUPPLEMENT 2019
Cemented paste pouring
Placement of a filter layer of rock fill
advantage here given the system is designed
to enable its delivery
n Adding a cementitious binder to the paste
also reduces the likelihood of liquefaction as
binder hydration consumes water in the
paste matrix and creates a solid material
Timing
Based on economical merits alone, it is unlikely
that an investment in a paste operation can be
justified without the merits from underground
backfilling. In most cases the transition to
underground mining overlaps with the tail end
of open pit operation. Thus, even if a paste
plant is commissioned by
the time underground
backfill is required it is
unlikely that deposition into open pit is an
available option for some period of time. This
makes the continuation of delivery of tailings to
other surface tailings storage facilities a
necessity until the open pit is fully
decommissioned and all necessary measures
are in place to assure safe deposition of paste
or filter cake into the open pit are taken.
Engineered Solution
A paste plant that is used for backfilling
underground voids, dewaters a slurry to a
useable paste consistency and as an
intermediary product, filter cake. The paste
plant can therefore be readily modified to either
place paste or filter cake in-pit. Different
operators reviewing this opportunity have a
keen interest in realising this concept.
In the Pinos Altos Oberon de Weber pit
example in Mexico, Agnico-Eagle placed a roller
compacted concrete layer at the base of the
open pit to improve crown pillar stability and
create an impervious layer to isolate the
underground. On top of this, a drainage layer is
placed to collect the seepage water. Dewatering
pumps are placed inside a pump well. Paste or
filter cake can then be deposited and safely
contained. IM
All photos are courtesy of Agnico Eagle Mines Ltd
References
Karajeh, I: Paste for In-Pit Tailings Disposal
Applications in ‘Minefill 2017’ Proceedings of the
12th International Symposium on Mining with Backfill,
February 22, 2017
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APRIL 2019 Supplement | International Mining P11