The Wonmunna iron ore project commenced production in March 2021. Image courtesy of Mineral Resources.
The Wonmunna iron ore project is owned and operated by Mineral Resources Limited (MRL).
The Wonmunna iron ore project is located in the Pilbara region of Western Australia.

The Wonmunna iron ore project is an open-pit, direct-shipping iron ore (DSO) project by Minerals Resources Limited (MRL) in the Pilbara region of Western Australia.

MRL acquired the project from the Australian Aboriginal Mining Corporation (AAMC) in September 2020. It was previously owned by Ascot Resources, which had bought the property from Ochre Group (formerly Rico Resources) in September 2014, while AAMC acquired it from Ascot Resources in December 2018.

The Department of Mines and Petroleum (DMP) of the Government of Western Australia approved the mining proposal of the project in March 2015.

The Wonmunna project produced its first iron ore in March 2021 with the mine’s output planned to be ramped up to five million tonnes per annum (Mtpa) in the second half of the year. The initial mine life of the project is estimated to be approximately eight years.

The Wonmunna iron ore mine has also the potential for further expansion to double the production capacity to 10Mtpa upon securing additional approvals from the government.

Location, geology, and mineralisation

The Wonmunna iron ore project is located in the Pilbara region of Western Australia, approximately 80km northwest of the Newman and approximately 360km south of Port Hedland.

The project site lies at the junction of the Great Northern Highway, within a distance of 25km from the major operating mines such as Hope Downs, Area C, and West Angelas in the Pilbara region.

The Wonmunna iron ore resources are hosted within the Neoarchaean-Palaeoproterozoic Hamersley Basin that extends approximately 500km east to west and 400km north-south, covering a total area of approximately 1,00,000km2.

The Wonmunna ore body comprises banded iron formations (BIF) associated with the Marra Mamba Iron Formation.

The project targets four deposits, namely North Marra Mamba (NMM)-East, NMM-West, Central Marra Mamba (CMM), and South Marra Mamba (SMM) covering mining leases M47/1423-1425.

Iron ore reserves at Wonmunna

The maiden ore reserves estimate reported in 2015 for the CMM, NMM-East, and the NMM-West deposits of the Wonmunna iron ore project stood at 28.86 million tonnes (Mt) grading 58% Fe. The total indicated and inferred resources of the four deposits of the project were estimated to be approximately 84.3Mt grading 56.5% Fe.

Mining and ore processing

The conventional open-pit mining method involving drill, blast, load, and haul operations are employed for extracting the Wonmunna iron ore.

The extracted ore is processed to a minus 8mm product size through a modular crushing and screening facility.

The Wonmunna iron ore output is being used in MRL’s Utah Point Hub iron ore blend that has been using the ore tonnage from the company’s Iron Valley project in Pilbara. It will also incorporate the ore from the proposed Lamb Creek and Wedge mines in Pilbara.

The additional production from Wonmunna is expected to boost the capacity of MRL’s Utah Point export facility at Port Hedland to 14Mtpa by the end of 2021.

Infrastructure facilities

The infrastructure facilities developed as part of the project include a sealed access road connecting the Great Northern Highway, pit access ramps, run-of-mine (ROM) pad, crusher area, processing plant, stockpile areas, product stockpiling and load out yard, waste dumps, tailing facility, mine operations centre, explosive storage facility, and a diesel-fired power station, apart from general administration and service facilities.

MRL also plans to construct a 1.5MW solar array along with a battery storage facility for the project which is expected to be commissioned in the first half of 2022.

Contractors involved

Orelogy Mining Consultants was engaged by Ascot Resources for planning and management consultancy services for the Wonmunna project, while Piacentini & Son prepared the mining proposal report for the project in March 2015.

Peter O’Bryan & Associates carried out the preliminary geotechnical assessment for the NMM and CMM open pits in 2014.

Phoenix Environmental Sciences carried out terrestrial fauna surveys to support the environmental impact assessment of the project.

Azure Capital was hired by Ascot Resources to provide advisory services related to financial and negotiation transaction agreements in June 2018.