Mining techniques / Coal extraction methods

Due to different geological formations different techniques were developed and improved to extract coal. From the earliest bell pit method to modern drift, opencast, and deep mining extraction methods.

Bell pit

The name bell pit comes from the shape of the excavation, with a narrow vertical shaft sunk into the coal or iron ore seam, which was then opened out into a small chamber.               Little timber was used, so once the roof became unsafe, the pit was abandoned and another shaft sunk nearby. Coal was cut by using picks and shovels. Man and coal were transported by a basket. Candles or lamps were used for illumination. As indicated in the photograph this is the earliest system of underground mining.

Open cast  

The top soil and sub soil is stripped and stored. Coal is then mined, and once operations are finished, the void is back filled with overburden, sub soil and top soil. Ground contours are graded. The Potteries coalfield occurs in a syncline (dish shaped structure). At the edges coal is near the surface, which enables open-cast methods of extraction to be used.

Drift

Inclined roadways were driven to exploit shallow coal which would be uneconomic to be worked by shafts. Due to the geology some of the North Staffordshire coal seams, the drift mine was introduced to extract the coal. The photograph shows the 1260 yard long main intake drift at Silverdale which 16ft wide, 12ft high and equipped with a 48in conveyor belt capable of discharging 750 tonnes of coal an hour.

Deep mine

At the centre of the syncline, coal occurs at much greater depths and therefore it is more economic to sink a shaft for the extraction of the coal.