The Lake Giles project is an open-pit iron ore mine planned to be developed by Macarthur Iron Ore, a subsidiary of Macarthur Minerals, in Western Australia, Australia.

The project involves the development of the Moonshine North and Moonshine magnetite deposits and will leverage existing regional rail and port infrastructure.

A definitive feasibility study (DFS) for the project, completed in March 2022, estimated that the development of the mining project would require a total investment of £436.3m ($569m).

The Lake Giles iron ore project is expected to produce approximately three million tonnes (Mt) of magnetite concentrate per year, over an estimated mine life of 25 years.

Location, geology and mineralisation

The Lake Giles iron project is located around 175km northwest of the gold mining town of Kalgoorlie-Boulder in Western Australia and about 450km east-northeast from the capital city Perth.

The project comprises a series of banded iron formation (BIF) hematite and magnetite prospects hosted in the Snark, Clark Hill North, Clark Hill South, Sandalwood and Moonshine deposits.

The tenements form part of the 80km-long and 10km-wide Yerilgee Greenstone Belt and are located within the Southern Cross province of the Yilgarn Craton, which includes several lenticular greenstone belts with variably foliated gneissic granitoids surrounding them.

The greenstone belts hold metamorphosed ultramafic, mafic and sediments consisting of Archean age BIF intruded by mafic, intermediate and granitic rocks.

The Lake Giles iron ore mineralisation comprises primary mineralisation and goethite-hematite mineralisation associated with un-oxidised BIF and ultramafic rocks, and oxidised BIF, respectively. It also includes secondary pisolite mineralisation.

Estimated reserves and resources

The Moonshine North and Moonshine deposits were estimated to contain proven and probable reserves of approximately 237 million tonnes (Mt) of grading at 28.2% iron (Fe), as of August 2020.

The measured and indicated mineral resources were estimated to be 272.5Mt grading at 28.1% Fe, while the inferred resource stands at 449.1Mt at a grade value of 27.1% Fe.

Mining method and ore processing

The Moonshine North and Moonshine pits will employ a conventional open-pit mining method utilising hydraulic excavators and dump trucks.

The primary feed ore will be hauled to the run-of-mine (ROM) pad and tipped into the crusher pocket for onward processing.

The ore will be processed through crushing and grinding involving high pressure grinding rolls, ball mill and Vertimill, followed by magnetic separation.

A reverse flotation method will be employed for the treatment of the ore to lessen the silica contained in the final concentrate.

The final product will be hauled through road transport and stockpiled at the railway siding. It will be transported via rail with rotary tippling wagons to the port of Esperance for onward transshipment.

Infrastructure facilities

The infrastructure facilities at the project site include a ROM pad, processing plant, haul roads, and a tailings storage facility (TSF).

It will also comprise an accommodation village, a railway siding and an airstrip.

The other infrastructure will include the construction of a new concentrate storage shed to store approximately 260kt of product.

Power and water supply

The Lake Giles iron project, including the process plant and non-process supporting infrastructure, will require a power supply of 40MW to be delivered by a standalone microgrid.

The microgrid will comprise liquefied natural gas (LNG) reciprocating engines, solar panels and a battery energy storage system.

The mining project is expected to consume approximately four gigalitres (Gl) of water per year, sourced through the local paleochannel aquifer.

Contractors involved

CSA Global was engaged to complete the mineral resource estimate for the Lake Giles iron project, while Orelogy Consulting delivered the mineral reserve estimate.

Stantec (previously Engenium) was awarded a contract for the design works of all supporting infrastructure that includes bore field, mine village, airport, haul road, water desalination plant, solar power plant, mining infrastructure and railway siding.

iDrilling and Drillwest were engaged to conduct drilling activities at the Moonshine and Moonshine North prospects of the iron project.

Optimize Group was contracted to deliver study management services in the preparation of a feasibility study for the Lake Giles project, whereas Projectus Infrastructure was selected to provide transport infrastructure (rail and port) optimisation support.

FTI Consulting carried out the economic and financial modelling services for the feasibility study of the iron ore project.

VECKTA, a joint venture between Worley and XENDEE, was selected for the delivery of critical inputs to the power solutions at the Lake Giles project in September 2021.

Macarthur Minerals executed a memorandum of understanding (MoU) with Southern Ports Authority to access the Esperance Port in February 2021.