The Ulan Mine Complex (Ulan No.3, Ulan West) is at the western limit of the geological formation known as the Sydney Basin and at the southern end of the Gunnedah Sub-basin. The resource coal targeted for extraction is from the Illawarra Coal Measures, which are of Permian age and overlain by sedimentary formations of varying thickness and types including sandstones, shales and alluvium. Ten coal seams (nine in the west) occur within the coal measures; eight occur above (seven in the west) and one below the Ulan Seam. These seams range in thickness from approximately 0.4 to 10 metres (with the Ulan Seam being thickest). Apart from the Ulan Seam, all seams within the mining leases are considered uneconomic in the current market due to their high ash content.

The main geological features present within the Ulan Mine Complex and in particular within the underground mining area are Triassic Narrabeen Group sandstones overlying the Permian sedimentary rocks of the Illawarra Coal Measures; and some Gulgong granite. More recent Jurassic Pilliga sandstone (over Gomiala shale) caps the Narrabeen layers in the north east and quaternary sands are present along rivers and major creeks.

The Ulan Seam generally dips uniformly towards the north-east at between one and two degrees, and the seam thickness averages 5 to 7 metres (see Stratagraphic Profile) throughout the Ulan Mine Complex. It consists of ten separate plies, which are consolidated into four working sections within the open cut. The working sections are separated by thin claystone horizons.

Current planning is for the open cut extension to mine the full seam, and the underground operations will mine the lower section of the Ulan seam. The lower section has low ash content and an average thickness of 2.75 metres; varying from 2.4 metres in the north- west, and up to 3 metres in the south.

Within the areas to be worked throughout the mine life, the depth of cover will generally increase where extraction progresses toward the north east, due to a combination of topography and a dipping seam.

Underground mining Ulan Mine Complex activities utilise longwall retreat and continuous mining methods.

These methods target the highest quality coal by only removing the bottom 3 metres of the Ulan Seam. Primary coal extraction, also known as 'development', is undertaken using continuous miner and shuttle car operation to develop the longwall panels. Secondary coal extraction, utilising longwall mining methods, operates a longwall width of approximately 400 metres.

Removing the bottom 3 metres of the Ulan Seam reduces the need to wash the coal; approximately < 30% of run of mine coal from the underground requires washing. All underground coal is conveyed to the surface stockpiles by the coal clearance conveyor system. Underground coal that does not require washing is crushed and conveyed directly to the product stockpiles in preparation for railing offsite. The higher ash coal is trucked to the coal wash plant reclaim stockpile where it is picked up by a reclaimer and conveyed to the coal handling preparation plant (CHPP).

CHPP has a flexible 1800 tph raw coal receivals system which allows for either an individual, or any combination of, direct plant feed, raw coal stockpiling or reclamation from the stockpile by a bucket wheel reclaimer.

A 1000 tonne surge bin distributes feed to a nominal capacity 1200 tph between two modules. The CHPP utilises dense medium baths, dense medium cyclones and water washing cyclones to separate rejects from thermal coal product for both the domestic and export markets.
Product coal is stacked onto product stockpiles and reclaimed by a 2000 tph rail mounted bucket wheel reclaimer to a 1750 t rail load out bin for rail transport to domestic markets or export markets through the Port of Newcastle coal terminals.