Re : Jon Greenley
The Cleveland ironstone mines were particularly active from 1850 until 1964 with the highest output of over 6 million tons in 1883. Initially the technical expertise came from experience in the nearby Durham coalfield which was suitable as Cleveland ironstone was stratified i.e. in reasonably horizontal seams, although at an average thickness of about 8 feet thicker than was used to. However only at or near outcrop could it be worked by pick and shovel, otherwise it had to be drilled by hand labour and blasted using gunpowder. The larger companies working the deeper mines soon found that compressed-air powered drilling machines achieved more efficient results; first used in 1875, electrically powered drills were introduced after 1900. From about 1920 the surviving mines re-introduced hand drilling methods more effective and flexible for working pillars, until 1950 when powered machines became standard with multiple-pattern shot-firing using more modern explosives.
Workings were bord and pillar but some longwall was used in certain instances. Generally the shallow mines were free of inflammable gas and always used candles or other naked flames for lighting. However gas was occasionally found and was responsible for the Lingdale disaster of 1953 when 8 men were killed in an explosion. The use of gunpowder for blasting was responsible for great attention to ventilation from the 1870's which no doubt helped to reduce the effects of gas being given off from the bituminous shale in the strata above the seam.
Regards, Simon.
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