XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 539
INTRODUCTION
The Southdown Project is being developed by Grange
Resources and involves the construction and operation
of an open pit magnetite mine located approximately 90
kilometers east-northeast of Albany. The project location is
10 kilometers south-west of the locality of Wellstead in the
Great Southern region of Western Australia. Southdown
has been under development since the early 2000s and has
been the subject of various feasibility studies. The 2012
Definitive Feasibility Study (DFS) incorporated a pro-
cessing plant with a capacity to produce 10Mtpa of high-
grade concentrate. The plant was designed by AMEC (now
Wood) after a program of bench and pilot testing. The
2012 DFS was revisited by Wood in 2021 and an updated
Pre-Feasibility Study (PFS) was completed in early 2022
for a smaller plant, producing 5Mtpa high grade magnetite
concentrate.
The deposit itself is approximately 12 kilometers in
length with 6 kilometers of this included in the current
study. It contains over 1.2 billion tons of high-quality
mineral resources, including 388 million tons (Mt) of ore
reserves (Grange Resources 2023).
The deposit is estimated to have a life of mine in excess
of 30 years with a mass recovery to final product in the
34–36% range. The site, illustrated in Figure 1, is located
in farmland and requires the complete establishment of all
facilities and infrastructure for the mining and on-site pro-
cessing of the magnetite ore. The project aims to develop an
open pit mine and processing plant to treat about 15 Mtpa
of run of mine (ROM) feed material from which 5 Mtpa
of high-grade magnetite concentrate will be produced.
The processing plant will be adjacent to the mine and the
concentrate will be pumped via an overland slurry pipeline
to the filtering, storage and ship loading facility located at
the port of Albany. A water pipeline transports recovered
filtrate water, together with new water from other sources,
back to the concentrator for use in processing.
The project is challenged by the lack of water and
electricity. As there is no large volume water supply in the
region, the original DFS (2012) proposed the desalination
of seawater. The closest suitable capacity electricity grid is
280 kilometres away in the Collie region, close to Bunbury.
In part due to these utility supply and cost restrictions,
the target production rate of magnetite concentrate was
reduced from 10 Mt/a down to 5 Mt/a. Despite this, power
and water remain high-cost commodities and decision driv-
ers for the project.
A BRIEF INTRODUCTION TO THE
SOUTHDOWN FLOWSHEET
Southdown Project Design Constraints
Until the update of the PFS in 2022, the Southdown flow-
sheet consisted of a ‘traditional’ autogenous and ball mill
grinding circuit (AG/Ball Circuit) with wet magnetic sepa-
ration stages between each comminution step. The original
production rate of 10 Mt/a of concentrate at P80 45µm
required two parallel AG/Ball grinding circuits. Reducing
the production capability to 5 Mt/a removed the need for
one of the processing lines.
The AG/Ball mill processing flowsheet is described as
follows. AG mill product is screened at 3 mm with undersize
sent to rougher magnetic separation (RMS). Screen over-
size is returned to the AG mill feed. The –3 mm magnetics
is pumped to the ball mill and 3 mm non mags discarded
Figure 1. Green fields exploration drill rigs
INTRODUCTION
The Southdown Project is being developed by Grange
Resources and involves the construction and operation
of an open pit magnetite mine located approximately 90
kilometers east-northeast of Albany. The project location is
10 kilometers south-west of the locality of Wellstead in the
Great Southern region of Western Australia. Southdown
has been under development since the early 2000s and has
been the subject of various feasibility studies. The 2012
Definitive Feasibility Study (DFS) incorporated a pro-
cessing plant with a capacity to produce 10Mtpa of high-
grade concentrate. The plant was designed by AMEC (now
Wood) after a program of bench and pilot testing. The
2012 DFS was revisited by Wood in 2021 and an updated
Pre-Feasibility Study (PFS) was completed in early 2022
for a smaller plant, producing 5Mtpa high grade magnetite
concentrate.
The deposit itself is approximately 12 kilometers in
length with 6 kilometers of this included in the current
study. It contains over 1.2 billion tons of high-quality
mineral resources, including 388 million tons (Mt) of ore
reserves (Grange Resources 2023).
The deposit is estimated to have a life of mine in excess
of 30 years with a mass recovery to final product in the
34–36% range. The site, illustrated in Figure 1, is located
in farmland and requires the complete establishment of all
facilities and infrastructure for the mining and on-site pro-
cessing of the magnetite ore. The project aims to develop an
open pit mine and processing plant to treat about 15 Mtpa
of run of mine (ROM) feed material from which 5 Mtpa
of high-grade magnetite concentrate will be produced.
The processing plant will be adjacent to the mine and the
concentrate will be pumped via an overland slurry pipeline
to the filtering, storage and ship loading facility located at
the port of Albany. A water pipeline transports recovered
filtrate water, together with new water from other sources,
back to the concentrator for use in processing.
The project is challenged by the lack of water and
electricity. As there is no large volume water supply in the
region, the original DFS (2012) proposed the desalination
of seawater. The closest suitable capacity electricity grid is
280 kilometres away in the Collie region, close to Bunbury.
In part due to these utility supply and cost restrictions,
the target production rate of magnetite concentrate was
reduced from 10 Mt/a down to 5 Mt/a. Despite this, power
and water remain high-cost commodities and decision driv-
ers for the project.
A BRIEF INTRODUCTION TO THE
SOUTHDOWN FLOWSHEET
Southdown Project Design Constraints
Until the update of the PFS in 2022, the Southdown flow-
sheet consisted of a ‘traditional’ autogenous and ball mill
grinding circuit (AG/Ball Circuit) with wet magnetic sepa-
ration stages between each comminution step. The original
production rate of 10 Mt/a of concentrate at P80 45µm
required two parallel AG/Ball grinding circuits. Reducing
the production capability to 5 Mt/a removed the need for
one of the processing lines.
The AG/Ball mill processing flowsheet is described as
follows. AG mill product is screened at 3 mm with undersize
sent to rougher magnetic separation (RMS). Screen over-
size is returned to the AG mill feed. The –3 mm magnetics
is pumped to the ball mill and 3 mm non mags discarded
Figure 1. Green fields exploration drill rigs