Mining at Bulga Underground involves three stages: development mining, longwall mining and coal preparation and transport for sale. Bulga Underground is a retreat longwall operation, which enables about 80% of the coal to be removed from the target seam.
Development mining is where the underground roadways are constructed in preparation for Longwall mining. The roadways provide access for men, machinery, ventilation air, water, electricity, communication systems and coal clearance conveyors.
Typically five metres wide and three metres high, the roadways are constructed down the length of the longwall panel which are usually over two kilometres long. Coal is cut by a continuous miner to form the roadways and the roof is secured using steel mesh and roof bolts.
The main purpose of development mining is to form the rectangular blocks (longwall panels) that will be removed by the longwall miner. The Blakefield South longwall panels are 400 metres wide and up to 3.5 kilometres long. The coal seam is 130 metres below the surface at its shallowest point and 355 metres below the surface at the deepest point.
Once the roadways are established and infrastructure and services in place, the longwall is transported down the roadways, piece by piece and installed ready for longwall mining.
Development mining of the Blakefield South mine has been completed.
Bulga Underground is a state of the art longwall mining operation, and a world leader in longwall automation.
Extracting the coal from a longwall panel begins once the longwall has been installed at the coal face. The longwall shearer travels back and forth across the width of the longwall panel, cutting approximately one metre of coal with each pass. The coal is transported from the cutting face to the Coal Handling and Preparation Plant via a network of conveyors.
Large steel hydraulic supports temporarily maintain the roof. These provide a protected area in which our employees can work safely. Bulga Underground is a world leader in longwall automation. The automation creates safer zones, removing operators from dust, noise and fly rock, which improves productivity.
After the shearer moves across the coal face, the roof supports automatically lower and move forward in preparation for the next cut. The roof that was being supported is then allowed to collapse into the space where the coal has been removed (known as the goaf). This causes subsidence on the surface above the longwall panels.
The process continues until the panel of coal has been mined, which typically takes around 8 months.
Approximately 50 employees operate the longwall.
The Blakefield seam ranges from 4.5 to 8 metres in thickness within the Blakefield South longwall area, with the extraction thickness ranging from approximately 2.2 to 3.7 metres, due to the operating range of the available longwall equipment.
- Length of panels: up to 3.5 kilometres long
- Width of panels: 400 metres