The Pilbara region comprises a large part of the ancient continental shield of Western Australia which is comprised of both Proterozoic and Archaean rocks. The Pilbara is overlain by the Proterozoics deposited in the Hamersley and Bangernall Provinces.

The BIF is a member of the ~620 m thick Brockman Iron Formation which makes up part of the 2.63 2.45 Ga Hamersley Group. The Hamersley Group comprises almost 2.5 km of consecutive sedimentary and volcanic rocks located within the ca. 80,000 km2 Hamersley Province of the Pilbara craton in North West Australia, approximately 1100 km north of Perth. In the lower part, it consists of dolomite, shale and BIF, while the upper part consists of dolerite, various lava types and BIF with minor amounts of tuffs and shales. Underlying the Hamersley Group, is the 2.78–2.63 Ga Fortescue Group, which consists of flood basalts and rhyolites. These volcanics were laid down on the uplifted and eroded Pilbara block. This volcanic succession may contain remnants of a Large Igneous Province (LIP).

The Brockman Iron Formation ofthe Hamersley Group is divided into four sub-lithostratigraphic units, namely the lowermost Dales Gorge Member (BIF), the Whaleback Shale Member, the Joffre Member (BIF), and the uppermost Yandicoogina Shale Member. After deposition, these laterally extensive BIF have all experienced minor folding and basinal uplift along with low-grade regional metamorphism – from burial prehnite–pumpellyite facies to greenschist facies.

General consensus exists regarding the depositional model of the Brockman Iron Formation. According to this model, the succession was deposited on a large, stable, and clastic-starved, continental platform, which was influenced by episodic inputs of fine-grained tuffaceous detritus.

Mining Operations
All of Hamersley Iron's mines are conventional open pits using track and shovel mining method with preliminary drilling and blasting. The drill holes are filled with an explosive, most often ANFO (Ammonium Nitrate/Fuel Oil) and then charged. The resulting blast breaks the material to a size required for digging.

The broken material is loaded for transport by face shovels, excavators or front-end loaders into haul trucks. Haul trucks at our operations are typically in the 190 tonne and 240 tonne class. Overland conveyors are used to transport partially crushed feed at sites where there are long distances between the pits and process plants.

Rail and port operations
Ore from processing facilities is railed up to 460 kilometres to the coast along a dedicated privately owned rail system. A typical train consist comprises 2 GE Dash 9 locomotives, 230 ore cars and is over 2.4 kilometres long. A single driver, supported by centralised track control, operates the train.

Once the train arrives at the port the ore cars go through the car-dumper. The ore cars are rotated and the ore flows out into bins and then is discharged onto conveyors.

The ore is stockpiled according to product type and the quality control plan. The travelling stackers create 250m long stockpiles. Rotary bucket-wheel reclaimers later reclaim the ore, which will be conveyed to the ship loader.

Vessels are loaded at the berths alongside the ore wharf. Lump ore is rescreened to remove undersize material. Reclaimed ore is conveyed along the wharf and the ore is loaded into the vessel’s holds by travelling, slewing and luffing shiploaders.

Processing of the ore ranges from simple crushing and screening to a standard size, through to processes that beneficiate or upgrade the quality of the iron ore products. This is done by physical processes, which remove impurities by differences in particle density or size gravity or size separation. Processing may be wet or dry.

At Yandi, ore is crushed to fines product only through a combination of dry crushing and screening, or crushing and wet processing of ore using classification to remove finer particles.

The processed ore is stockpiled and blended to meet product quality requirements, before being reclaimed and conveyed to rail load-out. The ore is loaded into ore cars for transport to the port facilities.