Explanation of Highwall Mining

Highwall mining was originally undertaken using augers but eventually, the continuous miners used in the underground mining of coal were developed and outfitted to recover coal from highwalls. This spurred the development of new highwall mining machine systems such as the Terex SHM, the
Highwall Hog, and the ADDCARr System developed in 1990 by Addington, a medium-sized Kentucky based coal mining company.

A standard highwall miner or mining system) involves driving a typically rectangular shaped entry or section out of an exposed highwall seam by remote control. Advanced highwall mining systems such as the Terex SHM are self-contained, hydraulically-powered, tracked mobile units with electric drive.
The SHM highwall mining was the first unit that could mine parallel entries in coal seams with a thickness ranging from 76 centimetres to five metres to pre-determined depths of up to 300 metres.

The mined coal is then transported back to the machine by two counter-rotating screw conveyors positioned inside the pushbeams. The SHM system is highly efficient, with the capability of producing an output of 15,000 to 50,000 tonnes of coal per month, depending on the height of the seam.

Terex estimates there are 25 of its machines operating currently around the world with the USA and Russia being the main areas of activity. International Coal Group Inc estimates there are over 20 of its ADDCAR systems operating worldwide.

Terex Machine operating in USA

Trench Mining

Trench mining is a well known variant of highwall mining and has been used since the late 1980s. In Trench mining, instead of using the highwall from an open cut coal mine, a box cut or slot is cut and the highwall miner is moved into the box cut and then mining is carried out from either side. The slots can be along strike with the mining carried out down dip or the slots down dip with the mining carried out along strike.

Trench mining can be carried out at a lower capital cost than conventional open pit mining due to not needing a large pre-strip. It also offers better control over coal quality due to selective mining. It is capable of substantial coal production levels with good productivity.


Highwall Miner in Australia

The following papers provide more information on Highwall Mining: 

Click here to view Digging Deeper Pdf
Click here to view Highwall Mining: The Way Ahead