...early mining production at Winsford
Before the purchase of the continuous mining machine the only method of extraction used at Winsford was the drilling and blasting technique. It was used for nearly 70 years and, despite a few changes and advances in machinery, the basic five point technique remained unchanged.
Undercutting
Once the rock has been marked to keep the correct mining horizon, the undercutters - like big chainsaws with tungsten cutting picks - cut a 4.6 metre slot at the base of the face.
Drilling
The next stage is to drill a 'drag cut' pattern of holes. This is a set of holes drilled horizontally and a set of holes at downward angles which almost meet the undercut.
The last drill used at Winsford was a hydraulic drilling jumbo. It had two drilling arms which measured the size of the face so the drill pattern on the computer could be selected. The electrically powered drills operated independently, making approximately 70 holes.
Blasting
Once drilled, the holes are charged with explosives and then detonated. The bottom holes are detonated first to ensure sufficient clearance in the tunnel. A typical blast would yield 1,250 tonnes of salt.
Loading out
After the area is declared safe the loading shovel would move in to load up. Winsford has the largest wheeled loading shovel in any underground UK mine - it carries up to 18 tonnes in its bucket.
Until 1978 the CAT machines loaded the salt into dump trucks which then drove it to the crushing plant. Nowadays we use a face line crusher system and conveyor belts to transport the salt to No 5 shaft for elevation.
Scaling
The last part of the process is to remove loose rock and make the area safe for future working. This was originally done by hand scalers and later by mechanical scalers.
Read more about how rock salt is extracted from Winsford today
