Coal and the coal mines

by Homer Greene

“The bodies of some of those who were shut in by the fall, or buried under it, were found when the drift was again opened, but for others the mine has been an undisturbed grave for more than forty years.”

Note added in 1898.—The latest disaster resulting from a squeeze or fall in the mines occurred June 28, 1896, at the Twin Shaft of The Newton Coal Mining Company at Pittston, Luzerne County, Pennsylvania. This mine had been working for some days, and when the fall came the Superintendent, together with his foremen and workmen, were engaged in timbering or propping the affected region, in order, if possible, to prevent a fall. The effort was useless, however, and these officials and workmen were caught while at their work, and perished in the disaster. There were fifty-eight of them. Superhuman efforts were put forth to rescue them, but the attempt was useless, and later on it was found utterly impossible even to recover their bodies, owing to the extent and magnitude of the fall.

CHAPTER XI.
AIR AND WATER IN THE MINES.

Man is an air-breathing animal. So soon as his supply of air is cut off he dies. In proportion as that supply is lessened or vitiated, his physical and mental energies fail. One of the first requisites, therefore, in all mining operations is that the ventilation shall be good. To accomplish this end an air current must be established. It is true that into any accessible cavity atmospheric air will rush, but if it be allowed to remain in that cavity without any replacement it becomes dead and unfit to breathe. If, in addition to this, it takes up deleterious gases, like those which escape from the coal measures, it becomes poisoned and dangerous to human life. Hence the necessity of a continuous current. Provisions for such a current are made with the opening into every mine. The separate air compartment of a shaft has already been noticed. In drifts, tunnels, and slopes a part of the opening is partitioned off for an airway, or, what is more common, a separate passage is driven parallel with, and alongside of, the main one. In drifts and tunnels, since the mines there are not deep, air shafts are often driven at some other point above the workings, or slopes are sunk from the outcrop to accommodate the return air from the mine. It is due to the necessity of maintaining an air current that all passages and chambers are driven in pairs or sets in the manner already explained. It has also been explained how the fresh air going in at the carriage ways of the shaft, or other openings, passes along the gangway to its extremity, back along the airway, up to and across the faces of each set of chambers, and then down into the airway again, to be carried to the foot of the shaft and up by the air passage to the surface. But in the larger mines there are many passages besides the main gangway that must be supplied with air, and the current must therefore be divided or split to accommodate them; so these separate currents, taken in this way from the main current, and themselves often divided and subdivided, are called “splits.” The air channels thus branching, uniting, crossing, and recrossing form a most complicated system of ventilation. But the current goes nowhere by chance. Every course is marked out for it. On the fact that it follows that given path depends the lives of the workmen and the successful operation of the mine. Sometimes it becomes necessary to carry two currents of air through the same passage in opposite directions. In that case the passage will either be partitioned along its length, or a wooden box laid through it to conduct one of the air currents. If one air course crosses another, as is often the case, a channel will be cut in the roof of one of the passages, and the lower side of the channel will be closed tightly by masonry, to prevent any possible intermingling of the currents, a circumstance which might prove disastrous. Entrances and cross-headings cut through between parallel passages for purposes of ventilation are closed as soon as the next cross-heading is made, for reasons already explained. This closing is usually done by building up in the aperture a wall of slate, rock, and coal, and filling the chinks with dirt from the floor of the mine. Sometimes wooden partitions are put in instead, and between principal air passages the cross-headings are closed by heavy walls of masonry. When it is necessary to turn the air from any traveling way, or to prevent it from further following such traveling way, a partition is built across the passage, and in the opening left in the partition a door is swung. If this is across a way through which mine cars pass, a boy will be stationed at the door to open it when the cars come and close it as soon as they have gone through. He is called a “door boy.” All doors are so hung as to swing open against the current of air, and are therefore self-closing. The law directs that this shall be done. There are several patented devices for giving an automatic movement to mine doors; but few if any of them are in practical operation in the anthracite mines. The conditions here are not favorable for the use of self-acting doors, and besides this the act of 1885 provides that all main doors shall have an attendant. The law is very explicit on this subject of ventilation; it is a matter of the utmost importance in operating a mine. A failure of the air current for even an hour might, in some mines, result in the death of all those who chanced to be inside. For this current not only supplies air for breathing purposes, but it takes up the smoke, the dust, the dangerous and the poisonous gases, and carries them to the surface. In the same way pure air is drawn into the lungs, loaded with the refuse matter brought there by the blood, and then expelled. So life is preserved in both cases.

In order to create this circulation of air and make it continuous, artificial means are ordinarily used. The earliest method of creating an artificial air current which should be constant, and one still in use to a limited extent, is that by the open furnace. This is an ordinary fireplace with grate bars, built near the foot of an opening into the mine, and having a bricked-in smoke-flue which leads into the air passage of that opening at some little distance above the floor of the mine. The volume of heat thus passing into the airway will rarefy the air therein, and so create and maintain a strong, invariable, upward current. Sometimes the furnace is placed at the foot of an air shaft a long distance from the main opening, thus making it an upcast shaft. The reverse, however, is usually the case. All air that enters the mine by any opening is usually drawn out at the main shaft or other main entrance. But as the air returning from the working places of the mine is often laden with inflammable gases, it is not allowed to come into contact with the fire of the furnace, but is carried into the shaft by a channel cut into the rock above the roof of the mine. Furnace ventilation in mines in which explosive gases are generated is dangerous at the best, and is now prohibited by the act of 1885.

The modern and most common method of creating and maintaining a circulation of air in a mine is by a fan built at the mouth of the air compartment of the shaft or slope. The fan exhausts the air from the mine by the airway, and fresh air rushes in by the carriage way, or any other opening to the surface to restore the equilibrium. Sometimes the fan is used as a blower and forces air into the mine instead of exhausting it. The advantage of this method is that it gives better air to the workmen at the faces of chambers and headings, but the objection to it is that it brings all the smoke and gases out by the main gangway. This is a serious objection, not only making this principal passage unfit to see or breathe in, but making it dangerous also by the presence of inflammable gases. The fan is therefore commonly used as an exhauster.

There are various kinds of fans in use at the mines, but the kind generally employed is patterned after Guibal’s invention. It is simply a great wheel without a rim, and instead of spokes it has blades like those of a windmill. It is run by a steam-engine, makes forty revolutions per minute at an average rate of speed, and sends from one hundred thousand to two hundred thousand cubic feet of fresh air per minute into the mine.

The act of 1885 requires the mine operator to furnish two hundred cubic feet of air per minute to every man in the mine. This is the maximum amount necessary for perfect respiration. In the larger workings perhaps six hundred men and boys are employed. For this number one hundred and twenty thousand cubic feet of air per minute would be required by law. A large fan would supply this amount by running at almost its minimum rate of speed. So long, therefore, as the fan and air passages are in good working condition there need be no fear of lack of proper ventilation. But to give absolutely pure air to the workers in the mine is an utter impossibility under any system that has yet been devised. The outer atmosphere that is drawn into the mines has hardly got beyond the light of the sun before it has taken up a certain percentage of impurities. As it passes by the working faces of the chambers it carries along with it the gases evolved from the coal; principally the carbonic acid gas or black damp, and the light carbureted hydrogen or fire damp. It also takes up and carries along the powder smoke, the organic matter contained in the exhalations of men and animals, the products of decaying timber, and the dust which is always in the air. Nor is this the only deterioration which this air current undergoes. The proportion of oxygen in it is diminished by the burning of many lamps, by the respiration of many men, and by the constant decay of wood. It is seen, therefore, that the air in which the miner must breathe is far from being the pure oxygen and nitrogen of the outside atmosphere. It follows also that the longer the route is of any particular current, and the more working faces it passes in its course, the more heavily laden will it be with impurities, and the more poisonous for those men who last breathe it on its return to the upcast air shaft.