At the beginning of the 19 th century, the danger of coal dust was slowly being realised. There were references to the explosibility of coal dust in several reports, including that of the celebrated North of England viewer, John Buddle, on the Wallsend Colliery Explosion in 1803 and that of the Rev. John Hodgson, describing the Felling Colliery Explosion in 1812. More emphatic and detailed is the description by Lyall and Faraday of the Hasswell Colliery Explosion in 1844, they stated:-
“In considering the extent of the fire from the explosion, it is not to be supposed that firedamp is the only fuel. The coal dust, swept by the rush of flame and wind from the roof, floor and walls of the workings, would instantly take fire and burn if there was enough oxygen in the air present to support its combustion, and we found that the dust, adhering to the face of the pillars, props, and walls was in some places a half inch and in others almost one inch thick, it adhered together in a friable coked state.
When examined with a glass, it presented the fused round form of burnt coal dust, and when examined chemically and compared with the coal itself reduced to powder, was found derived of the greater part of the bitumen and in some cases entirely devoid of it."
“There is every reason to believe that much coal gas was made from this dust in the very air itself of the mine by the flame of the fire damp, which raised and swept it along and much of the carbon remained unburned only for the want of air”. (This produces deadly carbon monoxide gas)
In his report on the Ince Colliery Explosion in 1854 Dickinson stated:-
“That as the workings were very dry, it would be aggravated by the coal dust raised by the blast”. Another interesting reference was made by two colliery managers at the inquest following the Winnstay Explosion in 1873 when they said in their evidence that the coal dust would be ignited by “firing the shot”.
Meanwhile in France, during the period 1855-1874 scientists were beginning to attach increasing importance to the dangers of coal dust in colliery explosions, stating:-
“the absence of fire damp having being well verified, we believe that in order to explain the Campagnac Explosion, it was necessary to admit the combustion of coal dust raised by the firing of a shot”. Mr. Vital also reported on this explosion, and in addition carried out experiments. As a result, he concluded that, “very fine coal dust is a cause of danger in dry workings where blasting is practiced. In fiery mines it increases the chances of explosions and when accidents of this kind do occur, it aggravates their consequences”.
In 1906 one of the most extensive explosions happened, at Courrieres, Pas-de-Calais, Northern France, where 1,099 men lost their lives. This was a formidable coal dust explosion. Investigators from this country believed that nearly all the big explosions were due chiefly, and in some cases entirely, to coal dust, and that,
“the only certain method of preventing such loss of life would seem to be, to render the mines incapable of being the scene of widespread dust explosions, by watering or otherwise preventing the accumulation of dry coal dust in the roads and workings”.
In Britain, in 1875, Galloway commenced experimental work on the explosibility of coal dust. First, he demonstrated that mixtures of firedamp and air, containing less than one percent of firedamp and air, became inflammable when charged with fine coal dust. Later, investigations of certain colliery explosions, disclosed the dominant part coal dust played in them.
In 1876, he wrote:-
“there would be no difficulty in accounting for the extent of violence of many explosions that have occurred in mines which no large accumulations of firedamp exist, if it could be shown that mixtures of air and coal dust were inflammable”.
About the same time, experiments were carried out in the North of England and the Midlands. The results of the Midlands experiments were reported in a paper, read before the Chesterfield and Derbyshire Institute of Mining in 1878 and concluded:-
“Explosions of coal dust and air were obtained in the absence of firedamp”.
This increased activity led to the problem being considered in subsequence explosions. In1879. Royal Commissions on Accidents were appointed both in this country and on the continent, and then attention was mainly directed on the coal dust problem.
After the Seaham Pit Explosion in September 1880, in which 164 died, the problem assumed great public importance, and the British Government sanctioned official experiments. At this enquiry too it appears that the first mention of stone dust was made. Atkinson, a mines inspector, stated that:
“ the intake travelling road was not damaged by the explosion, but the parallel haulage road was completely wrecked”.
The difference he attributed to the presence of stone dust in the travelling road. Thus he for-shadowed one of the future methods of combating the inflamabillity of coal dust in mines.
Later that same year, in December 1880, the first mention of the application of watering the roads was made at an inquiry at the Penygraig explosion, December 1880. Mr. W.W. Hood, manager of the Glamorgan colliery Co. gave evidence that he watered all roads at his collieries.
Mr. Overton in his report at an inquest suggested that:-
“If coal dust was removed by watering, or some other method that can be hereafter discovered, then shot firing can be carried on safely as in ordinary wet mines, in which no great explosions have occurred”.
From the following it is noted that the two chief causes of extensive colliery explosions, are the ignition of coal dust by either,
- A firedamp explosion or,
- The use of explosives.
Galloway, who investigated the Penygraig Colliery Explosion, emphasised the part played by coal dust, which had propagated the explosion through the entire workings, with the exception of one wet heading, he stated that three conditions were present:-
- A violent blast of air.
- A large flame.
- A simultaneous production of a cloud of coal dust.
As a result of his observations, he commenced another series of experiments at Liwynypa Colliery in 1880; these experiments showed conclusively that a mixture of fine, dry coal dust and air is capable of forming an explosive mixture, without the presence of firedamp.
Despite criticism, concentration on the subject still persisted, and at Elemore Colliery Explosion in Durham, September 1886 Atkinson said, he believed the explosion to be entirely due to coal dust combustion in pure air. He suggested that concussion, caused by the firing of a shot, raised a cloud of coal dust, which was then ignited by the issue of a flame at the same moment.
The Altoft Explosion in 1886, which was also propagated by coal dust, led to a demand for the addition to the Coal Mines Act (1872) to deal with dangers arising from coal dust.
It was not until the Coal Mines Act of 1887 that amongst the precautions required, was that of watering the dust in the vicinity of shots for a radius of 20 yards.