MINING PUMPS
Impelling progress
Paul Moore looks at pump market developments,
from new models to refinements of existing
models and technology additions
he overall trend in hard rock mining to
extract ever increasing tonnages of low
grade ores, historically considered to be
uneconomic, has led to the development of
larger equipment from the mine face through
the concentrator and on to tailings. FLSmidth
Krebs Products Director, Brad Moralee, told IM:
“The required development of larger pumps,
though challenging, has not presented
insurmountable difficulties. Along with these
ever-increasing tonnages, reliability and
efficiency is of paramount importance and will
remain so for the foreseeable future.”
T
Saving by downsizing
Sometimes increasing efficiency in a related
process means an operation can install a
smaller pump elsewhere and make resultant
cost savings. In Australia, Kirkland Lake Gold’s
Fosterville gold mine reduced its maintenance
costs significantly using new cyclone liners. But
even more interestingly, they reduced their
annual mill pump operating costs by 40-50% as
the new cyclone liners made it possible to
install Krebs millMAX™ technology.
The Fosterville gold mine is the largest
producing gold mine in Victoria, Australia. It
poured its one millionth ounce of gold back on
January 7, 2016. This important milestone
represented over 11 years of continuous
operations since mining commenced in 2004. In
2016, Fosterville produced 151,755 oz; and daily
mine throughput in 2016 was 1,900 t/d.
Fosterville had originally operated with large
sized pumps to handle the high recirculation load
through the mill. This recirculating load was caused
by oversized/worn cyclone spigots. Once the
cyclone ceramic liners were installed the efficiency
of the cyclones improved significantly - reducing
48 International Mining | APRIL 2017
recirculating load through the mill and mill pumps.
Fosterville has four cyclones in operation and
used to replace one apex per week to stagger
the hours. The highest wearing component of
the cyclones is the underflow apex. The rubber
apexes had typically worn from a diameter of 82
mm when new to 105 mm after 672 h (four
weeks) of operation.
After the 4th apex (2,688 h) the cyclone was
removed from service and was rebuilt with new
liners by the maintenance personnel. Each
rebuild cost approximately A$8,000 in materials
and A$1,000 in labour, including the time to
replace the apex liners. To reduce the significant
maintenance cost Fosterville asked FLSmidth to
replace the cyclone liners with FLSmidth Krebs
ceramic lined cyclones.
The FLSmidth Krebs ceramic lined cyclones
have a much greater life with the underflow
apex diameters wearing approximately 20 times
slower compared to rubber. However, they are
not allowed to increase to as large a diameter as
The first FLSmidth
Krebs millMAX10x8-24
mill discharge pump
installation onsite at
Fosterville Gold, which
was given the go ahead
after new cyclones
success at the site and
has since seen both
mill discharge pumps
replaced from
competitor pumps to
Krebs millMAX. From
left to right: Adam
Noble (FLSmidth Krebs
Area Sales Manager),
Kay Katov (Fosterville
Gold Senior
Metallurgist), Andrew
Nash (Fosterville Gold
Process Engineer)
KSB says it has made a strong commitment to
the oil sands industry in Alberta by establishing
a service centre and parts warehouse
the old rubber apexes. Instead the cyclones are
removed from service after 8,760 h (one year) of
service when the apex reaches 95 mm.
The four cyclones are staggered to replace
one per quarter. The ceramic lined cyclones are
supplied to site as a complete assembled unit.
The maintenance team can replace the whole
unit and no longer have to commit time to
replacing the liners.
Changing cyclone liners improved Fosterville’s
separation process in that this practice of
replacing the worn apexes with new ones
introduced a positive ledge where the new liner
met the worn one above it, which interrupted the
flow of slurry through the cyclone and rejected
oversize material to the overflow.
The effect of this could be observed in the
bottom of the flotation cells which contained a
lot of coarse material which inhibited the dart
plug operation and accelerated the wear of the
rotors and stators. The worn apexes also
allowed excess fine particles to report to the
underflow which increased the recirculating load
and unnecessarily accelerated the wear of the
mill components and discharge pumps. It also
decreased the percentage of the underflow
which could report to the flash flotation cell.
The overflow p80 sizing is now less variable,
but more noticeable is the significant reduction
in coarse material in the flotation cells observed
during shutdowns.
Andrew Nash, Fosterville Gold Process
Engineer states: “The benefit in this for
Fosterville was overall reduced costs of
operation and less wear to mill liners and mill
process pumps due to the reduction of
recirculating load. But even more interesting;
the improved separation process allowed for
smaller and far more efficient pumps to be
installed.” The reduction in fines bypass to the
underflow and the lower recirculating load has