The Yeelirrie uranium deposit is the largest known uranium deposit in Western Australia. It occurs in calcrete hosted material in the central drainage channel of a wide, flat and long valley which is flanked by granitic breakaways of low topographic relief with elevations between 490 m AHD and 610 m AHD.

The mineralisation extends from the surface to an approximate depth of 10 m, with the main concentration centred about 4 m below the surface, with a thickness ranging from 1 to 7 m. The surface extent of the identified resource is 9 km long and an average of 1 km wide, with a maximum width of about 1.5 km.

Lithological and mineralogical studies conducted in the Yeelirrie valley (WMC 1975, and studies conducted for this PER) show that there are four principal lithological units at the proposed development site:

1. Overburden: consisting of a combination of sandy loam, siliceous and ferruginous cemented hard- pan and carbonated loam, which is probably a weathered calcrete.
2. Calcrete: a calcite and/or dolomite replacement of the clay-quartz, although relics of partially replaced clay-quartz are common throughout the calcrete. The upper portion of the calcrete comprises friable ‘earthy calcrete’, a continuous layer grading upwards into the overlying soils. Nodular porcellanous calcrete represents the lower layer of the calcrete and consists of up to 70% carbonate (McKay and Miezitis 2001).
3. Clay-quartz: a kaolinitic clay-quartz allu ........

Mining of the pit would use standard surface mining equipment, such as excavators and front-end-loaders in conjunction with haul trucks and scrapers, to remove the ore and overburden. Due to the typically high friability of the ore and overburden material, minimal drilling and blasting would be required, although this technique may be needed in areas of the open pit if hard rock was encountered. For the purpose of the impact assessment presented in this document, a realistic worst-case scenario has been adopted, whereby 16 blasts are undertaken each year, using a total of about 70 tonnes of explosives and emulsion product.

Given the shallow nature and relatively small footprint of the area being mined at any time, the total mining fleet would consist of 3 to 6 excavators, or similar surface mining equipment, feeding about 12 haul trucks. Standard surface mining support fleet would include water trucks, graders, drill rigs and bulldozers. From the open pit, ore will be trucked to various stockpile areas based on grade and other geochemical characteristics.

The open pit mine will be about 9km long, up to 1.5km wide and about 10m deep. Up to 14 million tonnes (Mt) of overburden and ore would be mined annually during the mining preproduction pre-strip phase, with an average extraction rate of around 8 Mtpa.

The major features of the open pit:
Length of ore body - 9 km;
Average/maximum width of the ore body - 1 to 1.5 km;
Average pit depth - 10 m.

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