The Yandi region covers an area of approximately 70km E-W and 30km N-S and includes the Yandi deposit (CID), which is in production, as well as the Marillana (BKM) and Ministers North (BKM) deposits, which are at exploration stage.

The main topographic feature of the area is a broad open plateau, dominated by BIFs, shales and dolerites of the uppermost BKM IF and overlying Weeli Wolli Formation, which terminates in a steep NW-SE-trending scarp. To the northeast of the scarp lies the Fortescue Valley, filled with Mesozoic to Cenozoic detrital rocks. Cenozoic rocks also occur on the main plateau, within a major palaeochannel system.

The Yandi mineralisation is of the CID type and occurs within a 27km stretch of the Cenozoic Marillana Formation. This formation infills the meandering palaeochannels of Marillana Creek and its tributary creeks). The total length of the Marillana Creek palaeochannel is at least 80km and the Munjina and Upper Marillana deposits are located at the upstream end of the palaeochannel, to the west of Yandi.

The palaeochannel was eroded in the core of the broad, NNW-trending Yandicoogina syncline, which plunges shallowly to the east. The palaeochannel is flanked by shales, dolerites and BIFs of the Weeli Wolli Formation. The channels incised into the basement lithologies are some 450 to 750m wide and up to 100m deep. The overall gradient is around 2 m/km. At Yandi, the deposits outcrop as a series of low mesas beside the present-day creek.

The mineralisation at Yandi is of the CID type and extends continuously for the entire length of that portion of the palaeochannel covered by WAIO tenements (approximately 35km). The mineralised width of the channel ranges from 300 to 800m and the depth ranges from 70 to 100m.

Mineralisation comprises goethite-hematite pelletoids in the upper part of the Marillana Formation (Barimunya and Iowa Members), with peloid contents increasing towards the base and margins of the channel in the Western deposits at Yandi. The base of the palaeochannel is lined with conglomerates and clays of the basal Munjina Member. Alluvial material, associated with the course of the present day Marillana Creek, flanks the mesa.

Yandi is an open-cut mine.

Mining continues through conventional open cut mining methods, including drilling, blasting, and categorisation of blasted material into iron ore or waste rock.

WAIO open-cut mining uses face shovels, front-end loaders or backhoe excavators. The full bench is drilled and blasted for a 12 m height, sampled three times in 4 m increments and three 4 m flitches are then mined.

Ore and Waste haulage is done with both manually operated and autonomous haul trucks. Waste is hauled directly to the adjacent waste storage areas either ex-pit (on surface) or inpit. Waste material is also utilised as fill material for development works and rehabilitating the completed waste dumps.

Ore is hauled to the Run-of-Mine (ROM) pad where it is stockpiled and blended for ore quality before feeding to the crushers using loaders. Some of the ore suitable for blending is also hauled directly to the crushers.

Yandi processing hub started operations in 1992 to process ore exclusively from the Channel Iron Deposits (CID) and produce a fines only ore type. The production rate of this hub also has increased over time and currently it has four primary crushers and three OHPs with a combined nominal capacity of 80 Mtpa. It also recovers 100% mass of plant feed. This processing hub has a stockyard blending facility and two train load outs.

This facility has already processed >1.3 billion tonnes through to 30 June 2021, but the mine is reaching the end of its life. Therefore, production ramp down, along with the closure and decommissioning of associated infrastructure, started in July 2021 and has continued into June 2022. Once Yandi mine is fully exhausted, parts of the Yandi processing facilities are likely to be used to process ROM feed from nearby BKM deposits.

Ore is crushed, beneficiated (where necessary) and blended at the processing hubs – to create lump and fines products that are transported along the Port Hedland–Mt Newman rail line to the Finucane Island and Nelson Point port facilities at Port Hedland.

Facilities, use & condition: 4 primary crushers, 3 ore handling plants, stockyard blending facility and 2 train load outs (nominal capacity 80 Mtpa).