Isaac Plains is located approximately 180km South West of Mackay, Queensland, 172km by rail from the Dalrymple Bay Coal Terminal, and 7km east of the township of Moranbah, in Central Queensland's Bowen Basin Coal province. The project is situated between the Goonyella main railway line and the Peak Down Highway which service the northern area of the Bowen Basin.
The current Mining Lease (ML70342) covers an area of approximately 2940Ha. Coal seams amenable to open cut mining occur in two seam groups and up to six seam splits. Isaac Plains has coal Resources of 5Mt and total Resources of 30Mt.
The coal seams dip to the east, generally at less than 5 degrees. The mining strips are typically aligned north-south, perpendicular to the dip. The coal is split within the Coal Handling & Preparation Plant into coking, SSC (Semi Soft Coking Coal) and thermal coal fractions.
The project consists of 5 potential open cut pits positioned along the north-south striking seam subcrop. Most of the project infrastructure is located in the North West corner of the mining lease, including a 5km rail loop, a 500tph wash plant, train loading facilities, and water and power reticulation facilities. As such, the open cut will develop to the east (away from Moranbah). Rehabilitation is progressive and ongoing. The reclaimed spoil already acts as a noise, light and dust buffer between the open cut mining operations, and the residents to the west of the project.
Haul trucks transport the coal from the mining face to a ROM pad, where it is feed into the CHPP.
Before mining begins, the area is inspected for culturally significant artifacts and approved for clearing and topsoil stripping. Cultural artifacts are recovered, and topsoil is removed and stockpiled for re-use in rehabilitation, or directly placed on rehabilitation targets such as profiled waste dump surfaces. The mining activities may then begin.
Although some overburden may be free-dug by hydraulic excavators, it is necessary to blast the majority of the overburden such that it can be removed by truck-shovel operations and dragline. This material is placed in the adjacent previously mined out void.
The mining method employed at Isaac Plains is strip mining, employing blast cast, dozer push and truck & shovel and dragline overburden excavation methods. This method of mining is used when coal seams are close to the surface, and in a consistent flat lying orientation. Strip mining involves digging a "trench" to expose and extract the coal seam, with the waste material (overburden) placed adjacent to the trench. In subsequent strips, the overburden is placed in the previous strip after coal is extracted, where it is profiled, top soiled and seeded for final rehabilitation.
DL1, 1370 BE dragline is owned by Stanmore IP Coal Pty Ltd. After construction and successful commission, DL1 started operating in June 2011. The machine has achieved above industry standard availability and performance figures.
DL1 is the primary low cost overburden stripping equipment, budgeted to strip over 15Million BCM of waste per year with target dig rate of 2,000 BCM/hr.
Wash Plant – CHPP
The Coal Handling and Preparation Plant (CHPP) at Isaac Plains was designed and constructed to operate at a feedrate of 500t/h, producing up to2.8Mt of washed coal product for export.
The CHPP typically operates in dual product mode producing a primary metallurgical coal product and a secondary steaming coal product. Multiple internal process configurations are available to optimise the proportions of each product coal type being produced.
The coarse coal circuit consists of two dense medium cyclones in series, with a teetered bed separator and Jameson flotation cells utilised to process the fine coal portions of coal feed. Coal product is stacked via a four armed product stacker from which coal is reclaimed through two valves for train loading.
All railed coal is loaded onto vessels for export through the Dalrymple Bay Coal Terminal. Co-disposal of coarse and fines reject is provided for by the use of belt press filters to dewater fine reject material.