About Surface Mining
Surface mining is an operation that involves the recovery of shallow coal deposits from the ground through the removal of overlying rock by excavators and dumptrucks. We would typically work to depths of 50m to 100m.
Our mining engineers carefully design sites to ensure maximum coal recovery with minimum disruption, which means that, where possible, our sites are worked in a phased way to minimise the site area being worked at any one time.
The first part of the process is to remove the soils. The top soil and sub soil is segregated, removed and placed in mounds around the site. These mounds act as a visual and noise barrier to the work to being undertaken.
The next stage in the process is to excavate down to the coal seams. The material above and between the coal seams is known as overburden and consists of rock which is predominantly shale, mudstone and sandstone.
Material from the first area that is excavated is placed in to a mound, called the overburden mound,
As an area is worked and the coal removed, it is subsequently refilled with the overburden from the next area. This process is repeated until all the coal has been recovered, at which stage the final void is backfilled using the material stored in the overburden mound.
During the excavation process, the rock swells. This is known as bulkage and means that even after having removed the coal there is sufficient material to restore the land to around the same level as it was before mining took place.
The soils are then replaced on to the site and restoration is undertaken.