Isaac Downs project is a new open-cut metallurgical coal mine being developed in Queensland, Australia.
The mine is a part of the Isaac Plains complex, which also includes the Isaac Plains mine (IPM), Isaac Plains East, and Isaac Plains underground project. The Isaac Plains complex is wholly-owned by Australian coal mining company Stanmore Coal.
The Isaac Downs project is estimated to produce approximately 35 million tonnes (Mt) of run of mine (ROM) coal over a mine life of 16 years. It will produce 3.2 million tonnes per annum (Mtpa) in the first nine years, with a steady production of 3Mtpa to 4Mtpa, followed by approximately 1Mtpa over the next seven years.
The coal project will generate approximately 250 jobs during the construction phase and approximately 300 during its operation. It will bring in more than A$200m ($143.26m) of coal royalties to the Queensland Government.
Construction activities are expected to begin in early 2021. Mining operations will commence in mid-2021 with first coal anticipated in the first quarter of 2022.
Location of Isaac Downs project
The Isaac Downs coal project is located in the Bowen Basin coal field, 145km away from Mackay and 10km from Moranbah. It is situated within the Isaac Regional Council (IRC) local government area of Queensland.
A major portion of the project is located within the former Nebo Shire Council and a small part is within the former Belyando Shire Council.
The project site is located in proximity to several existing coal mining and coal seam gas operations in the region such as Moranbah South mine, Bowen gas project, and Poitrel mine.
Isaac Downs project reserves
In August 2021, Stanmore Coal reported an increase in the mineral resources and coal reserves of the project following 18 months of exploration activities as part of the bankable feasibility study (BFS).
The Isaac Downs project’s total resource is estimated at 36.2Mt, comprising 24.7Mt of measured resources and 11.5Mt of indicated resources as of June 2020.
The mine’s recoverable reserves stand at 25.9Mt, including proved reserves of 22.3Mt and probable reserves of 3.6Mt.
Mining method at Isaac Downs
The project will employ a single open-cut mining pit and use dragline, shovel, and excavators for removing overburden and extracting coal. Mining will be performed with front-end loaders and excavators, while rear dump trucks will be employed for haulage.
The open cut mining activities will begin with the clearing of vegetation, stripping and stockpiling of topsoil. The pre-strip overburden will be drilled and blasted, and then removed using truck and shovel fleets and / or dozers. Drilling and blasting of the overburden will be followed by overburden removal using dragline.
After the mining of coal using excavators, the overburden emplacement areas will be rehabilitated.
The project will be developed in a series of mine stage plans. The top seam will be mined along the length of a strip until the end is reached, while the deeper coal seams will be mined until the designated basal seam.
Construction for the project will take six to 12 months to complete and will include civil works for the levee, roads, and water management and associated infrastructure.
Processing and coal export at Isaac Downs
The coal will be transported along the strip via a ramp out of the pit and along a haul road to an ROM stockpile area near the pit.
The material will then be dumped onto a stockpile and loaded for transport to the IPM coal handling and preparation plant (CHPP) for processing.
The runoff from the stockpile area will be stored in a dam and then transferred to the mine water management system. The coal reject will be sent to an in-pit dump area at IPM. The tailings and rejects from the project are intended to replace the tailings and rejects from IPM.
The processed coal will be transferred to the IPM rail loop for transportation to the Dalrymple Bay Coal Terminal (DBCT) at the Port of Hay Point from where it will be exported.
Infrastructure at Isaac Downs
The project infrastructure will include an ROM haul road, ROM coal pad, access road, and a mine infrastructure area (MIA) comprising offices and workshops.
Isaac Downs will utilise infrastructure at IPM such as the CHPP and rail loop. The equipment and workforce for the project are also planned to be transferred from IPM.
A levee will be constructed to protect the open-cut mining operations from flooding and the overburden dumps will be rehabilitated.
Workforce accommodation will be a combination of accommodation villages and residences in Moranbah and other local towns.
Palaris Australia prepared the coal reserves estimate for the project.
CMC was selected under the early contractor involvement (ECI) model for the engineering design for the major civils works.
The contract includes bridgeworks for an underpass for the Peak Downs Highway crossing, and the construction of a flood protection levee and a haul road between Isaac Downs and Isaac Plains.