540 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
as waste. The Ball milled product, at P80 85 µm, is further
concentrated within an intermediate magnetic separation
stage (IMS). The magnetics from IMS are sent to sulfide
flotation to remove Pyrrhotite and then on to regrinding
and cleaner magnetic separation (CMS). The magnetite
concentrate is thickened before being pumped to Albany
for filtration and ship loading.
In this circuit there was little opportunity to reduce
front end water use without significant additional capital
equipment, such as dry stack tailings filtration. The wet
RMS stage produced a large volume of dilute non magnet-
ics that required cyclone classification as well as thickening
of the overflow. The cyclone underflow was to be combined
with thickener underflow for pumping to a tailings storage
facility. Thus, the circuit had a heavy reliance on water due
to unacceptable losses to tailings storage. Opportunities to
reduce the reliance of the flowsheet on water were proposed
and this commenced the investigation into dry milling
in 2019.
After Stage 1 of the dry milling test work was com-
pleted, the 2022 PFS proposed replacing the single line of
AG and ball milling (described above) with two lines of dry
Loesche Vertical Roller Mills (VRM). Loesche were in the
final stages of constructing a new pilot unit, incorporat-
ing dry magnetic separation in close circuit with the VRM,
at their facility in Dusseldorf, Germany at about the time
the PFS was completed. This approach allowed Loesche to
reject coarse non-magnetic waste material and improve the
mill efficiency. In conjunction with projected power sav-
ings offered by the VRM technology, the ability of the new
mill configuration to create a coarse dry tailings stream was
a significant incentive to incorporate it in the Southdown
flowsheet.
BRIEF INTRODUCTION TO VERTICAL
ROLLER MILLS (VRM)
VRM technology is one of the oldest grinding technologies
known. Developed in antiquity, it is a simple technology
and machines could be constructed from common materi-
als. With thousands of installations, compressive commi-
nution technology is now a standard in the production of
cement, preparing coal for power stations and grinding for
Figure 2. Project location in Western Australia
as waste. The Ball milled product, at P80 85 µm, is further
concentrated within an intermediate magnetic separation
stage (IMS). The magnetics from IMS are sent to sulfide
flotation to remove Pyrrhotite and then on to regrinding
and cleaner magnetic separation (CMS). The magnetite
concentrate is thickened before being pumped to Albany
for filtration and ship loading.
In this circuit there was little opportunity to reduce
front end water use without significant additional capital
equipment, such as dry stack tailings filtration. The wet
RMS stage produced a large volume of dilute non magnet-
ics that required cyclone classification as well as thickening
of the overflow. The cyclone underflow was to be combined
with thickener underflow for pumping to a tailings storage
facility. Thus, the circuit had a heavy reliance on water due
to unacceptable losses to tailings storage. Opportunities to
reduce the reliance of the flowsheet on water were proposed
and this commenced the investigation into dry milling
in 2019.
After Stage 1 of the dry milling test work was com-
pleted, the 2022 PFS proposed replacing the single line of
AG and ball milling (described above) with two lines of dry
Loesche Vertical Roller Mills (VRM). Loesche were in the
final stages of constructing a new pilot unit, incorporat-
ing dry magnetic separation in close circuit with the VRM,
at their facility in Dusseldorf, Germany at about the time
the PFS was completed. This approach allowed Loesche to
reject coarse non-magnetic waste material and improve the
mill efficiency. In conjunction with projected power sav-
ings offered by the VRM technology, the ability of the new
mill configuration to create a coarse dry tailings stream was
a significant incentive to incorporate it in the Southdown
flowsheet.
BRIEF INTRODUCTION TO VERTICAL
ROLLER MILLS (VRM)
VRM technology is one of the oldest grinding technologies
known. Developed in antiquity, it is a simple technology
and machines could be constructed from common materi-
als. With thousands of installations, compressive commi-
nution technology is now a standard in the production of
cement, preparing coal for power stations and grinding for
Figure 2. Project location in Western Australia