In 1694, Cleator was home to the first charcoal fired blast furnace in Cumbria. In 1841, Coke fired furnaces were erected at Cleator Moor. In 1862, the Masonry furnaces were replaced by steel-cased, closed top furnaces. This change resulted in a huge increase in production, and pig iron output.
- A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.
In a blast furnace, fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place throughout the furnace as the material falls downward. The end products are usually molten metal and slag phases tapped from the bottom, and waste gases (flue gas) exiting from the top of the furnace. The downward flow of the ore along with the flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process.
From the 1850s to the 1880s, the population of Cleator Moor expanded rapidly as rich veins of haematite beneath the ground were removed, to keep up with demand. Several varieties of iron ore were mined in the area.
The most common type of haematite mined in Cleator Moor was compact, hard and massive, and of a bluish-purple hue (hard blue). Kidney or pencil ore was often found in irregular deposits in the first or second limestones. Specular ore was something of a rarity often found in cavities (loughs) and saved to be sold as specimens by the miners. Lesser ores consisted of dark ‘black’ soft ore; smite ore (very greasy and highly coloured; muck or ‘ring’ ore.