The Moolarben deposit is located on the western margin of the Western Coalfield within the Sydney Basin where sedimentary strata of Permian, Triassic and Jurassic age dip towards the northeast at 1° - 3° and overlie Carboniferous granite and folded metamorphic basement. The Permian strata comprise the coal-bearing Illawarra Coal Measures and the underlying Shoalhaven Group, which in turn uncomformably overlies the Lachlan Fold Belt basement rocks. Surface Quaternary alluvial deposits and remnant Tertiary basalt flows are common in the area.

The Illawarra Coal Measures are equivalent to the basal section of the Newcastle Coal Measures and the Wittingham Coal Measures in the Hunter Coalfield. Extrusive basaltic lavas and intrusive igneous activity was common during the Tertiary era (< 65 million years ago). These igneous features are usually not significant for open cut mining but for underground operations the impact of unidentified igneous intrusions can be serious from a safety as well as a cost perspective. RPM is aware the Company and its operators are well aware of this issue and continue to monitor and explore to minimise their impact.

The Illawarra Coal Measures are typically 80 to 100m thick within the Moolarben resource area and comprise a sequence of interbedded siltstone, sandstone, minor claystone with up to eight coal intervals, of which the Ulan Seam is the only seam mined. Regionally, the Wollar Sandstone which is a 120m thick sandstone sequence within the Narrabeen Group, overlies the coal measures forming cliffs and escarpments. The Pilliga Sandstone and Purlawaugh Siltstone, both of Jurassic age, overlie the Narrabeen Group to the north and east of Moolarben, with a combined thickness of up to 120 m. The Pilliga Sandstone is an aquifer of regional significance.

The Ulan Seam includes several partings and on a regional basis is up to 12m thick. A tuffaceous parting (C Marker – CMK) approximately 0.3m thick occurs in the middle of the seam and separates the upper (WS1L) and lower (WS2) open cut working sections. East of Moolarben the CMK interval increases to 15m thick. The Lithgow Seam, which is up to 15m below the Ulan Seam is the basal seam within the Illawarra Coal Measures throughout the Western Coalfield.

The seam depth increases towards the northeast due to regional dip. Overburden thickness north of the railway in the north of EL6288 reaches 300m and in the south of EL6288 severe topographic relief caused by remnant Triassic escarpments, limit the extent of open cut development even though overburden thickness tends to be less than 150 m.

The Ulan Seam is typically 11m thick throughout much of tenure although in the south of EL6288 and within EL7073, deterioration of some upper coal plies in the WS1 results in a decrease in overall seam thickness to less than 6 m.

Company utilises large scale open cut mining methods in open cut mining operations, which include the removal and storage of topsoil material via truck and front-end-loader (“FEL”) methods, drilling of a blast pattern, blasting of fragment rock, excavation of waste material with truck and shovel or excavator in the upper benches and by draglines in lower benches, and digging, loading and hauling of coal via truck and excavator or FEL methods. Open cut mines include HVO, MTW, Stratford Duralie, Middlemount and Yarrabee, as well as portions of Moolarben and Ashton.

Company utilises longwall mining in underground mining operations. Longwall mining roadways are cut by continuous miners around the perimeter of a rectangular block or panel of coal to form ventilation and access passageways. Underground mines include Austar and portions of Moolarben and Ashton.

Now fully developed, mining operations at the Moolarben Coal Complex comprise a multi-pit open cut mine, a longwall underground mine, and mining related infrastructure (including coal processing and transport facilities).

MINING OPERATIONS
Moolarben utilises conventional truck and excavator methods in its open-cut mining areas, and longwall operations in its underground mining areas. Moolarben is operational 24 hours a day, seven days a week.

Mining activities were undertaken in accordance with relevant project approvals and the approved MOP. During the reporting period general mining activities included:
- Overburden removal from OC2 and OC4 using excavator and truck fleets;
- Overburden removal from OC4 using cast and dozer push;
- Coal extraction from OC2 and OC4;
- Drilling and blasting select overburden and coal;
- Spoil emplacement in-pit in OC2, OC4 and within the OC4 Out of pit emplacement;
- Bulk spoil reshaping and rehabilitation; •
- Construction and operation of water management works;
- Continued underground development; and
- Extraction of LW102, LW103 plunge planel and commencement of LW103.

Mine Design
Open Cut
The open cut operations consist of five pits labelled OC1, OC2, OC3, OC3E and OC4. Mine designs are based on the 2017 LOM plan generated by Yancoal however have been reviewed by RPM and considered reasonable. RPM note that Reserves are reported for all pits with the exception of OC3E Pit. Pit designs are based on a 75° pre-split wall or 70° trimmed wall with a 45° batter through weathered material. A 12m – 15m berm is placed at the base of the weathering and at required intervals to avoid batters greater than 45m in height. Strip widths vary from 50m to 100m to suit dozer push and excavators respectively.

Information provided by YAL notes the following with regards to pit design:
- An in situ barrier of coal has been left between OC1 and UG1 pits,
- Factors such as 1 in 100 year flood extents, economic limits, adjacent mining operations, geological features, approval limits, coal crops, watercourses and infrastructure define the pit boundaries and
- Extensions to OC3 to the south are under investigation, as such are not included in Coal Reserves.

Both waste and coal mining will be completed using hydraulic excavators in both backhoe and shovel configuration dumping into rear dump trucks. OC4 will have the assistance of a dozer push fleet that has recently been introduced. RPM view this equipment as appropriate for the operations at Moolarben.

Underground
Underground development is undertaken using conventional development equipment. Single-pass bolterminers (continuous miners) are used in development sections, with shuttle cars used to transport coal to the coal clearance system. The coal extraction methodology has been based on the use of standard Australian continuous miner practices for development and retreat longwall practices for production.

Development in UG1 and UG4 is performed by a combination of conventional development and super unit configurations. Conventional development units consist of one continuous miner and up to two shuttle cars in a panel alternately advancing each roadway and completing a pillar cycle. Super units consist of two continuous miners and two shuttlecars in a panel, with a continuous miner in each roadway to increase the rate of advance of the panel.

Longwall extraction is undertaken using a CAT longwall system applying the Bi-Di method of cutting through use of a twin ranging arm shearer cutting a conventional mining section with a 1m web. Automation technology is being used on the face to ensure face alignment and correct horizons are mined, to support efficient and productive operations.

Long / wide panels with modern longwall equipment, incorporating automation technology provides the potential for highly productive and reliable operations. Although these dimensions are in line with other highly productive longwall operations, they are within current experience levels with the longest panels up to 6 km in length and the widest, up to 400 m.

UG1
In UG1 longwall mining will extract the combined D working section (DWS) and DTOP plies of the Ulan Seam with up to 3.4m (3.0m to 3.4m) of the seam to be recovered. Longwall panels will range from 2.4 km to 4.6 km in length and will be 300m wide. The panels have been laid out in a southwest to northeast orientation with an extraction sequence of sequentially mining panels from north to south (towards OC4). Within each panel the longwall will retreat from the southwest (inbye) end to the main headings along the north-eastern boundary. The longwall is currently operating in the first panel (short) panel on the northern side. Both development and longwall operations are currently operating to plan and underground conditions have been favourable as are expected.

Igneous plugs (diatremes) which are expected to impact on production and quality have been identified in UG1 in panel 2 and panel 3. The longwall has been planned to “step around” i.e. not mine, the diatreme in panel 2 but schedules still show full mining through the igneous feature on the inbye end of panel 3. It is expected that the decision on how to mine the inbye end of Panel 3 will be made when more information has been made available as per typical grade control practices.

UG4
Expansion into the UG4 mining area will occur once development of UG1 is completed. Due to changes in coal quality, longwall mining in UG4 will extract the DWS seam only with up to 3.0m (2.8m to 3.0m) mining height. Longwall panels will range from 2.4 km to 4.7 km in length and will be 250m wide. The subsidence criteria set out in the Stage 1 approval for UG4 has resulted in retaining a narrower panel width. The panels in UG4 based on YAL’s plan will be oriented generally north to south.

Panel layout is impacted by the location of “The Drip” on the Goulburn River (a surface featured waterfall sourced from groundwater). The mine is further bounded by Ulan Road, Goulburn River National Park and the old Goulburn River Valley palaeochannel. In particular the significance of ”The Drip” has resulted in a 500m standoff being required from the Goulburn River so that there are no subsidence impacts.

Access
The underground access is via portals in the OC1 highwall which has been left open for this purpose. By using an existing highwall the project was able to avoid the significant capital cost of driving inclined drifts from the surface down to the seam. Travelling roads and coal conveying routes have been established between the portal area and the CHPP to provide mine access for personnel, equipment and materials and to clear coal from the mine.

The portals enter the underground at the western corner of the first underground panel in UG1.

All Open Cut ROM coal is washed in a single wash plant which produces three thermal coal products, while all Underground ROM coal is crushed and screened and sent directly to the market (bypass) as a low ash thermal coal product.

- Two/single stage 1450 mm dense medium cyclones (-50 +2 mm)
- Two stage spiral banks (-2 +0.125 mm)
- Two stage Jameson cells for froth flotation (-0.125mm).

ROM coal from the open cut operation is processed through an on-site coal preparation plant while ROM coal from the underground operation is bypassed, in each case to produce thermal coals for the export market. Product coal is loaded onto trains for transportation 270 kilometres through the Hunter Valley rail network to the NCIG and PWCS loading terminals at Newcastle where it is shipped to international customers.

Coal Preparation Plant (CHPP)
The Moolarben CHPP was designed as a 1,800tph, two module plant (2 x 900tph throughput) able to be operated ........