Mineralisation comprises magnetite-titanium vanadium horizons within the Windimurra Complex — a large, differentiated, layered, ultramafic to mafic intrusion within the Murchison Province of the Yilgarn Craton. Eight magnetic horizons were modelled in the Fold Nose area and four magnetic horizons were modelled in the Kinks area. The mineralisation interpretations were based on the TiO2/V2O5 ratio, magnetics and geology.

The vanadium mineralisation occurs within a magnetite rich horizon - the Shephards Discordant Zone (SDZ) located on the eastern side of a large gabbroic intrusion known as the Windimurra Complex. The magnetite horizon extends for a strike length of over 25 kilometres, five kilometres of which has been tested by drilling.

The resource takes the form of a shallow, 35 degree west dipping cumulate layered intrusive with up to 50 separate magnetite bands between five centimetres to two metres thick separated by magnetite gabbro/leucogabbro and rare anorthosite pods. Economic mineralisation extends to surface with a mineable width of up to 150 metres. Weathering extends to depths of about 40 metres over much of the strike length of the deposit.

-Ore close to surface.
-Very low ore to waste ratio of 1:0.83.
-Soft oxidised nature of ore.
-Minimal blasting in oxide ore.
-Bench mining method.

The life of mine plan for Windimurra provides for the mining of oxidised, transitional and fresh magnetite-rich ore, with transitional and fresh ores to be bench mined for grade control. Mining commenced in the central pit and moved to the northern part of the ore body. Mining will move to the southern part of the ore body in due course. A review of the mining plan is currently being undertaken, as part of an on-going periodic challenge of each of our plans, assumptions and practices, to ensure that optimisation is achieved over time throughout the project.

Ore from the ROM pad passes through three stages of crushing, followed by high pressure grinding (HPGR) in closed circuit with fine dry screens. During these processes the particle size of the material is reduced to between 3 mm and 5 mm. The fine dry screening circuit was modified during the year to divert HPGR product back to the fine dry screens rather than being sent to the repulper. This reduced load pressure on the HPGR and significantly improved the operation of the repulp circuit. The ball mill has been converted to a primary grinding unit, further reducing the particle size of feed to the magnetic separators to less than 650 microns. The introduction of these modifications to the CMB plant during the latter part of the financial year was a major step forward in improving plant performance.

The ball milled material and fines of less than 650 microns next pass through the wet fine screen and report to the beneficiation plant where magnetic separators capture the magnetite concentrate. An important part of the modification work carried out to the CMB plant was the simplification of the process flow through the beneficiation plant, resulting in the redundancy of about 40% of the equipment originally installed in the beneficiation plant and the reduction in the particle size of the material passing through the magnetic separators from between 3 mm and 5 mm down to 650 microns. These changes have improved plant throughput and availability and reduced direct and indirect maintenance costs.