The Blantyre mining disaster, which happened on the morning of 22 October 1877, in Blantyre, Scotland, was Scotland's worst ever mining accident. Pits No. 2 and No. 3 of William Dixon's Blantyre Colliery were the site of an explosion which killed 207 miners, possibly more, with the youngest being a boy of 11. It was known that firedamp was present in the pit and it is likely that this was ignited by a naked flame. The accident left 92 widows and 250 fatherless children.
Blantyre was also the scene of two further disasters in 1878 and 1879. There was a succession of lesser fatalities, some of which—particularly in the earlier years—were caused by firedamp.
The Lanarkshire coalfield in the vicinity of Blantyre had three seams of coal being worked in the 1870s. They were the ell coal, 7 feet (2.1 m) thick at 117 fathoms (702 ft; 214 m); the main coal, 4.5 feet (1.4 m) thick at 129 fathoms (774 ft; 236 m) and the splint coal, 5.5 feet (1.7 m) thick at 155 fathoms (930 ft; 283 m). Precise depths vary with the elevation of the top of the various shafts.
The Blantyre colliery had five shafts:
No. 1, 24 feet (7.3 m) by 8 feet (2.4 m) working the ell and main coals.
No. 2. 16 feet (4.9 m) by 8 feet (2.4 m) working the splint coal.
No. 3. 24 feet (7.3 m) by 8 feet (2.4 m) working the splint coal.
No. 4. 24 feet (7.3 m) by 8 feet (2.4 m) working the splint coal. At the time of the explosion No. 4 had not yet connected with the rest of the colliery.
No. 5. 10 feet (3.0 m) diameter used as the upcast for numbers 1, 2 and 3.
Numbers 2 and 5 shafts were close to each other, within 30 yards (27 m). Number 3 shaft was 680 yards (620 m) away. Number 1 shaft was between the two but only reached the ell and main coals. Blind pits, that is shafts that do not extend to the surface, connected the ell and main coals to the splint coal. The main coal ceased to be worked in November 1878 and the passages from shaft 1 bricked up. Shaft 1 continued to work the ell coal.
Four main districts were formed in the splint coal:
A smaller area with workings to the north and south of number 3 pit.
An area lying in the north-west quadrant from number 2 pit.
An area lying in the south-west quadrant from number 2 pit.
An area lying in the south east quadrant from number 2 pit close to, and in communication with, the workings from number 3 pit.
Conditions in the mine were held to be poor by the colliers. The previous year the miners had sought a wage rise to compensate for the poor safety and been refused. They went on strike and were immediately sacked. Since the miners lived in tied cottages they were therefore evicted by force. The mine owners then brought in Irish Catholics to work the mine.
Most of the coal was worked using the Newcastle system, also known as "pillar and stall" or "stoop and room". A heading was driven into the coal and at intervals along it rooms were excavated, around 12 feet (3.7 m) wide. As the rooms got deeper another heading was driven from room to room to leave pillars (or stoops) about 20 yards (18 m) square behind. During this stage only around 30% of the coal was extracted. Eventually the whole district consisted of a grid pattern of passageways around stoops. The final stage in extraction was "stooping". The furthermost roof was supported by pit props and the stoops removed. Once a complete row of stoops had gone the props were removed from the furthest part which would collapse into the space ("goaf" or "gove") behind. During this process settlement and fracturing of the roof and seams above could occur, potentially releasing larger quantities of gas.
The alternative method of working the coal was the longwall system. Two headers were driven forward to the far end of the district and an interconnecting passageway excavated. The passageway was supported by props and the long wall on the shaft side of the passage excavated. As this wall retreated the roof was propped and the furthermost props removed, allowing the overburden to collapse into the goaf. With longwall the same fracturing and gas release that stooping could cause was always present.