Phosphate Hill is located within the Lower-Middle Cambrian deposits of the Duchess Embayment. The latter is part of the Burke River Outlier which is appended to the Georgina Basin (Russell and Trueman 1971). The work of Smith (1967) summarised the geology of the Georgina Basin and the following outline is drawn from that work and from Southgate (1983).

The Georgina Basin is a large (~324,000km2) sedimentary basin that contains both marine sediments (dominantly carbonates) from the Cambrian and Ordovician and freshwater deposits (dominated by sandstones and siltstones) developed during the Devonian or Siluro-Devonian. Although a number of deformation episodes are evident in places, with structures being locally intense in some areas, there is no evidence of metamorphism in any of the sequences. Precambrian sequences define all except the north-western and south-eastern margins. In the northern areas Cambrian strata from the Wiso and Daly River basins merge with the Georgina Basin sediments whilst in the south Cretaceous sediments of the Great Artesian Basin overlap those of the Georgina Basin. The phosphatic deposits of this Basin occur along the eastern side of the basin and in association with the Wonarah High (Northern Territory) (Green 1979, Cook and Shergold 1978).

The Burke River Outlier, of which the Duchess Embayment is part, is an appendage to the south-eastern side of the Georgina Basin. The Outlier itself is just under 100km long, ~30km wide an ........

At the site, Company operates export and warehouse facilities, and open-cut mining is used to extract phosphate rock.

Australia has a number of deposits, but only two phosphate mining operations. The largest is Phosphate Hill, formerly known as the Duchess mine, about 100km south of Mt Isa.

Phosphate Hill is a simple bench mining operation that requires no drilling or blasting, with generally less than 10m of overburden.

In 2008 reserves support a mine life of 25-30 years, even without any significant exploration at the mine in many years.

The mining method begins with all overburden being removed from the top of the ore seam in the chosen parcel area, following the natural contours of the structures (dome-and-basin morphology), and stored in waste stockpiles located close to and within the pits. Strong clay alteration/weathering products (referred to as dissolution and containing little or no phosphate), which can clog screens in the beneficiation plant and affect the morphology and chemistry of the PG, reducing PAP recovery levels, are usually found at this stage and are removed by the excavator under the direction of geological personnel and sent to the waste stockpiles. Once the waste stockpiles have reached full capacity and are not longer in use they are rehabilitated, using engineering to minimise rain runoff and erosion and seeded with local plants to assist with the natural revegetation process.

The ore is mined ........

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