Coal mine explosion

“ A very small percentage of fire-damp when mixed with air and coal-dust is sufficient to cause a disastrous explosion. In all dry coal-mines there is a considerable quantity of coal-dust (coal in a state of impalpable powder) lying about, and a certain proportion of it is always floating in the air through the workings of the mine. Now, when explosives are used, no matter how they are ignited, their combustion is always attended with the formation of a mass of flame, and consequently there is always great danger of an explosion of fire-damp taking place. ”

“ In such cases danger is imminent, disaster is most common.
When the naked light of the miner comes into contact with any considerable quantity of fire damp in an explosive state the shock that follows is terrific. Men and mules, cars and coal, are hurled together to destruction. Walls are swept out, iron rails are bent double, doors are torn from their fastenings, the mine is laid waste. The damage which results from an explosion of gas is of course much greater than that which is due to mere ignition and burning without the explosive force. ”

“ Small particles and dust were thrown out to a much greater distance, and the man who was working in front had been thrown back and buried under the fragments. About seventy-six tons of coal appear to have been displaced by the explosion. Carbonic acid continued to escape from the coal after the accident, and even the pieces that had been thrown into the gallery gave it out when they were disturbed. No satisfactory explanation has been offered of the manner in which the gas could have accumulated, and have gained so high a pressure as to cause a detonating explosion. ”

“ It has been found that a fertile cause of accidents in coal mines is insufficient tamping, or "stemming," as it is called in Yorkshire. Therefore a hole was bored into a strong wall of coal, and a charge of 45 grammes inserted, and very slightly tamped, with the view of producing a flame if such were possible. This "blowout" shot is so termed from the fact of its being easier for the explosion to blow out the tamping, like the shot from a gun, than to split or displace the coal. ”

“ When it is known that fire exists in the wastes, either by the burning of the small coal-dust along the roads, or from the ignition of the solid coal by a blower of gas, the inspection of the mine is incomparably more hazardous, as safety cannot be insured for an instant; for if the extrication of gas be great, it rapidly accumulates, and whenever it reaches the place where the fire exists, a new explosion takes place. ”

“ It is disengaged wherever vegetable matter has fallen and has become decayed. If it were thence collected, together with an admixture of ten times its volume of air, a miniature coal-mine explosion could be produced by the introduction of a match into the mixture. Alone, however, it burns with a feebly luminous flame, although to its presence our house-gas owes a great portion of its heating power. Marsh-gas is the first of the series of hydro-carbons known chemically as the paraffins, and is an extremely light substance, being little more than half the weight of an equal bulk of air. ”

“ There are extensive coal mines about eight miles from us. Some of them are very deep under-ground, but others are not, but the coal is brought up a slope in wagons on wheels. I was up last winter, and saw the men and boys that work in the mines. They were terribly black with coal dust. Each of them carries a safety-lamp, which gives but a feeble light in such dark places. I was up two winters ago, and saw one of the places for myself. At one of the largest mines, about two years ago, there was an explosion, which killed forty men, and ruined the mine. ”

“ Volumes of coal-dust had been driven along by the force of the blast, and lay in waves and drifts on the floor of the levels, into which the party sank to their knees. It was found that clouds of the finer particles had been carried to the shaft and beyond it into the main north level, where a secondary explosion had taken place. . . . Secondary explosions caused by extracted or generated gas are nearly always in the vicinity of the first one ”

“ Coal-Dust and Mine-Explosions.—We have already given an account of the experiments of the Prussian Fire-Damp Commission at Neunkirchen, with reference to explosions in coal-mines, and of the conclusion of Mr. W. Galloway, from the observation of some of them, that the explosions are chiefly or very largely promoted by coal dust. A French commission has reported upon this subject that they consider it established that "coal-dust in the absence of fire-damp does not constitute an element of danger," although it may play an important part in aggravating the consequences of an explosion. ”

“ An example has already been given of the way in which people have been saved from the effects of inundations in mines, others have been dug out when buried by the fall of roofs, but almost countless are the numbers who have perished from other causes, for if the first have destroyed their hundreds, the fire-damp in coal mines has proved the destruction of thousands. It was at one time considered right every night to provoke an explosion by lighting the fire-damp in order that the working stalls should be accessible next morning. ”

“ The gas frequently issues with great force from cavities in the coal (in which it has been pent up) , when the pick of the miner breaks an opening for it. In these circumstances an explosion is inevitable, if the issuing stream of gas happen to be directed full upon the lamp. Fortunately, however, this is a contingency which does not often arise. It is one of those risks of coal-mining which seem absolutely unavoidable by any amount of care or caution. It would be well if it were only such risks as these that the miner had to face. ”

“ In 1844, for the first time, Professors Faraday and Lyell, employed by the British government, discovered that explosion in bituminous coal mines was the quickening of the comparatively slow burning of the "fire-damp" by the almost instantaneous combustion of the fine coal-dust present in the mines. The flyings of the cotton mill do not explode, but flame passes through them with a rapidity almost instantaneous, yet not sufficient to exert the pressure which explodes; the dust of the wood planer and sawer only as yet makes sudden puffs without detonating force. ”

“ If these are properly made and tamped, the force of the explosion will tear down the coal properly; but if the man has been careless in his work, the tamps will blow out like shot from a gun-barrel, and igniting such gas or coal-dust as may be present, kill or badly burn the shot-firers. The proper tamping is wet clay, but it is impossible to convince the men of it, and nine out of ten will tamp their holes with dummies filled with coal-dust (itself a dangerous explosive) scooped up from the side of the track. ”

“ Even at this distance from the explosive den, the blast is often so powerful, that it frequently tears the brattice walls of the shaft to pieces, and blows the corves suspended in the shaft as high up into the open air as the ropes will permit. Not unfrequently, indeed, the ponderous pulley-wheels are blown from the pit-head frame, and carried to a considerable distance in the bosom of a thick cloud of coals and coal-dust brought up from the mine by the fire-damp, whose explosion shakes absolutely the superincumbent solid earth itself with a mimic earthquake. ”

“ After an explosion the air of a mine contains a large amount of the deadly gas carbon monoxide, and this “after-damp,” as it is called, makes rescue work extremely dangerous. Wherever suitable apparatus is available, the rescuers carry with them a supply of oxygen, by breathing which they are able to live for some hours in a poisonous atmosphere. The Bureau of Mines has established a number of rescue stations in the coal-mining districts and maintains several mine safety cars for hurrying rescue crews to the scene of a disaster. ”

“ Sometimes in an unexpected moment there is a great dislodgement of coal, and a tremendous quantity of gas is set free, which may be sufficient to foul the passages for some distance around. The introduction or exposure of a naked light for even so much as a second is sufficient to cause explosion of the mass; doors are blown down, props and tubbing are charred up, and the volume of smoke, rushing up by the nearest shaft and overthrowing the engine-house and other structures at the mouth, conveys its own sad message to those at the surface, of the dreadful catastrophe that has happened below. ”

“ The blast of air blows all the stone dust from those boards and fills the air chock-full of it.
"This stone dust, usually made from crushed limestone or crushed shale, won't burn. The flame of the explosion can't pass through and the fire can't jump a rock-dust barrier. Even the flame of methane, which you know better as 'gas,' or fire damp, which has a terrific force, is choked back by this dense cloud of rock-dust, and, as you know, all coal mines have more or less methane gas." ”

“ Yes, the world must have coal. So Uncle Sam, in pity for the miners who brave these awful dangers, has bought a mine at Bruceton, a short distance from Pittsburgh. There the government is making experiments to find out the causes of explosion, aiming in this way to protect the miners by lessening their dangers. ”

“ The fire was in one of the main passages, and was burning out the timbering, spreading rapidly under the draft from the reversed fan. There could be little hope of rescue in this part of the mine, but the helmet-men would defy the heat and smoke in the burned out passages. They knew how likely was the collapse of such portions of the mine; but also they knew that men had been working here before the explosion. “I must say they're a game lot!” ”

“ Many varieties of coal produce a quantity of fine dust which settles in the roadways, on roof, and sides, and floor. For many years there has been a controversy as to the relative importance of gas and dust in producing explosions, and the question is still one which gives rise to a lively difference of opinion. But there is no doubt that a mixture of coal-dust and air is explosive, and that even if an explosion is started by gas the disturbance creates clouds of dust which gives rise to secondary explosions and spread the disaster over a wider field than was originally affected. ”

“ Most of the great explosions which have destroyed hundreds at once have occurred in such a state of the atmosphere.
“Now the fog which came on that fatal morning was peculiarly thick and heavy, and it so happens that the coal in the Lucca’s bunkers came from a colliery where, only a fortnight ago, there was an explosion. The vapour, or gas, or whatever it was that was thus generated, was not the true coal-damp, or it would have been ignited by the furnaces of the boilers, or at the cook’s fires ”

“ Many more miners are killed by this choke-damp, as they hasten to the bottom of the shaft after an explosion, than by the fire itself. Choke-damp, which is carbonic acid gas, is heavier than ordinary air, and thus the lowest parts of a colliery become first filled with it, as they would with water. In all coal-mines there is a slight, sometimes a considerable, inclination, or "dip" as it is called, of the otherwise flat bed of coal. ”

“ When the fire reaches the powder in the squib the same force that propels a fire-cracker or a rocket acts upon the squib and [120] sends it violently through the channel or tube into contact with the powder of the cartridge. The explosion that results throws out a section of coal from the face, breaking it into large pieces. So soon as the place has settled after the firing of the shot the men go back to the face to note the result. The broken coal is pushed to one side, and preparations are made for drilling the next hole. It usually takes five shots to break down a single bench. ”

“ The safety property attributed to them is due to the depression of the temperature of the flame or products of explosion to a point below that necessary to ignite fire-damp or coal dust in air from a blown-out shot. New explosives that are found to be satisfactory when tested are added to the list from time to time, the composition being stated in all cases.
Methods for enabling miners to penetrate into workings where the atmosphere is totally irrespirable have come into use for saving life after explosions and for repairing shafts and pit-work under water. ”

“ But what gave the impulse such violent and dreadful force that it overwhelmed them before they could reflect? The explosion in the coal-mine is not caused by the sudden spark, without the accumulation of dangerous gases, and the absence of such wholesome ventilation as would carry them away. ”

“ A study of this subject has been made by the United States Department of Agriculture, and various recommendations have been published with a view to preventing the occurrence of sparks in the neighborhood of these dangerous dusts. Coal dust in mines likewise causes numerous explosions. Preventive measures include wetting the dust, moistening the air, and powdering the walls, roof and floor of the mine with a nonexplosive rock dust, which has the effect of stifling an incipient fire or explosion. ”

“ RESCUE PARTY ENTERING MINE AFTER EXPLOSION
THE STORY OF COAL
Safety in Coal Mines SIX
Since the year 1870, some 60,000 men have lost their lives as a result of coal mining accidents in this country. This is approximately one fatality for every 180,000 tons of coal mined. Gradually this bad record is being improved, thanks to the combined efforts of the United States Bureau of Mines, the mining departments of the various states, the operators and the miners themselves; but coal mining remains a hazardous pursuit. ”