For many years it was known for its high-quality coking coal, even being exported to coal-rich South Africa for use in steelmaking.

However, in 2013/2014, the market was swamped with cheap imports from the Far East, spelling the demise of Monckton due to it being uneconomical.

[6] In 1994, RJB Mining purchased the site from ICI for £4.7 million, and fed the plant with coal from the Clipstone Colliery in Nottinghamshire.

[9] Coke Oven Gas (COG), was sold to a local glass manufacturer, but when this supply ceased, the COG was burnt on site as part of a 12.7 megawatt steam condenser turbine which fed steam back into the coking process,[10] with excess electricity being sold into the National Grid.

Most was destined for customers outside of the United Kingdom; in the 1990s, when RJB Mining took over the concern, coke was exported to Norway.

[19][20] Some of the coke was destined for the domestic house-fire market and was sold under the branded names of “Sunbrite”, “Monckton Boiler Beans” or "Cosycoke".

[33] Closure of the plant was brought about by cheaper imports of coke from the Far East being available on the open market.

[34] Mothballing the site was not an option for Hargreaves as when the refractory bricks in the ovens cool, they crack and need to be replaced.