178 THE COLLIERY GUARDIAN. July 26, 1918. MECHANICAL MINING WITHOUT EXPLOSIVES.* By N. D. Levin. The entry-driving machine described below is the result of systematic research work carried on during the past eight years, and is able to perform all the operations required in mining coal and loading it into the pit cars without the use of explosives or hand labour. One machine has been in practically daily operation for two years, and additional ones are now being installed in the same mines. The coal is over- laid by a heavy layer of drawslate that comes down as soon as the coal is removed; and as the handling of this slate takes a large percentage of the time, the production is limited. Fig. 1 shows a front view of the machine. It operates on the same principle as a breast machine, the first or sumping cut being made at either rib, usually the left. It is fed forward in a stationary pan, making a cut 5 ft. wide, 7 ft. deep, and of a height to suit the coal bed. The coal in the above- mentioned mines is 5 ft. 8 in. high. The machine has an undercutting chain with cutter head similar to that of a breast machine, and two shearing chains, one on each side. The frames carrying these shearing chains can be varied for different heights of coal. Between the shears is mounted a frame, carrying a number of heavy punching picks, which is readily raised and lowered by the operator, who can cause the picks to strike at any height he desires. The coal falls on to a conveyor which enters the kerf cut by the undercutting chain, and carries the coal to the rear end of the machine, dumping it into a second conveyor which is mounted so as to swing at any desired angle to the machine. After a cut is made, the machine is moved sideways by means of a rope hitched to a jack at the opposite rib, and then another cut is made. When slate is to be piled up at the side of the room, the rear conveyor is swung sideways, the slate rolled on to the front of the machine and gobbed by the two conveyors. Analysis of one of the daily reports of the working of the machine shows that it takes about 13-!, minutes to make a cut, and about three minutes to move the machine to the next cut, or about 16 to 17 minutes’ time for each cut. There were 45 cars of coal loaded and 13 cuts made; therefore each cut gives about 3J cars. The cars hold nearly two tons of coal, which means at least six tons per cut and 21 tons per hour. This rate of mining and loading can readly be main- machine was handled by a crew unskilled in the art of pushing the work; also, the personnel of the crew was frequently changed. It is safe to assume that if the machines are worked double shift, they will advance 40 ft. each 24 hours. This being the case, in opening a new mine it would be desirable to drive to the end of the property and work back. As soon as a pair of entries are given, as many rooms as desired can be turned oft. In the meantime another pair of entries can be started. It is- desirable to cut very few break-throughs in the entries in order to save expense of building fireproof stoppings. The J y « w jggfei Fig. 1.—Front View of the Machine. break-throughs may be driven on 250 ft. centres. In this case air is supplied to the machines by canvas tubes and a small electrically’ driven fan placed in the nearest break-through. A tube of this kind is shown in the lower right-hand corner of fig. 3. These machines should be worked double shift. Between If an output of 100 to 150 tons per machine is ob- tained, then the saving in the first cost will be much in favour of the mining and loading machine. In a mine equipped with mining and loading machines the cost will not increase from year to year as the mine is being worked out, as is the case with the present system. The workings will always be concentrated. Only main haulage will become longer, and this will not materially affect the cost. THE AMERICAN COAL TRADE. In commenting upon the stereotyped character of the market news while the markets are under Govern- men control, the Coal Age (June 29) explains that the demand is unabated and that stocks are low. The impetus given to coal production by the pulling together of the railroad and fuel administrations was reflected in the truly wonderful accomplishment of the bituminous coal mines during the week ended June 15, when 12,571,000 short tons of soft coal were mined. This output breaks all previous records, and is deserving of more than passing notice when it is considered that a serious car shortage still exists, that thousands of experienced miners have been taken by the draft, and that labour conditions in general are demoralised. The labour problem at the hard coal mines continues to cause much uneasiness, as this branch of the industry is losing men at the rate of 2,000 monthly. The condition promises to become critical unless proper remedies are applied speedily. Many of the larger operators’are now shipping their entire output to the lakes, thus necessarily reducing the stocks available for steam and domestic use. The vessel movement is. generally good. On the whole, however, shipments are behind schedule, principally because of the late opening of navigation. Boston reports state that buyers are displaying genuine alarm over the o.utlook. The days go on and still slim receipts from every quarter. Important activities are operating oft very narrow stocks, and consumers generally are dazed. There are so few directions toward which they can turn, and each source of supply seems a little less dependable than the others. Conservation measures are being well sup- ported, and some surprising progress has been made. The railroad fuel situation is particularly urgent. If relief is not had, one of the systems will be obliged to confiscate coal in transit. This only shows the extent to which the New England situation has been allowed to drift. fl ■ f *3 -1 Fig. 2.—Rear View, showing Coal entering tained if conditions in the mine are such that the machine can be kept in steady operation, which is not possible with heavy drawslate. Where the roof conditions were good, the machine has loaded 30 tons an hour in this mine. Fig. 2 shows the machine cutting and delivering to the swinging conveyor. The pipe posts used with the machine can be set in a small fraction of the time that would be required for setting wooden posts. As the machine advances, wooden posts are put in to take the place of the pipe posts. Fig. 3 shows the swinging conveyor delivering coal to a storage hopper, holding about three tons and provided with a conveyor that will empty it in about a minute. A separate motor on this hopper operates the conveyor. A starting box for the motor is at the rear end of the conveyor, con- veniently located for the driver, who stops and starts the hopper conveyor as required in loading the car. There is also mechanism on the hopper for moving the car its own length, so that the driver can load the car without assistance. The machine crew pay no attention whatever to this part of the work. The storage in the hopper gives the driver sufficient time to change cars and keep the coal away from the machine. In another district where a machine of this type was operated for driving an entry under favourable roof conditions, but without the hopper conveyor used, it was found that, regardless of every effort on the part of the machine runners and the mine foremen, an average of five minutes was wasted each time a car was changed. Nevertheless an output of as much as 120 tons per shift of nine hours was obtained, with an average of 60 tons per shift for the three months that the machine was operated. The machine when driving an 11 ft. entry has averaged 20 ft. advance per shift of eight hours under rather unfavourable conditions. There was a con- siderable amount of sulphur in the coal, and the * Coal Age. Swinging Conveyor. Fig. 3.—Rear shifts they should be oiled, looked over in a general way, and the bits reset. Assuming that each machine working in a room pro- duces 60 tons per shift, or 120 tons each 24 hours, and each machine on entry-work produces 40 tons per shift, or 80 tons every 24 hours, there would be 22 machines required for room work and four machines for entry work for a mine producing 3,000 tons per day; so that only 22 rooms and four entries would be needed at one time. If the same mine were laid out along the line of present practice, about 350 rooms and 30 to 40 entries would be required to maintain an output of 3,000 tons per day. The crew for each machine consists of a machine runner, a helper and a driver. If the slate is heavy, it may require an extra man for handling this material. The same class of men that make good shortwall machine runners make good men for the mining and loading machine. There is less danger of roof falling where the mining and loading machines are used. The machine stays in the room until it is worked out, which is a com- paratively short time, probably three to four weeks. On account of this condition the expense of timbering should also be decreased to a marked degree. In a mine worked on the above lines there would be so few entries that they could be inspected fre- quently and kept in a safe condition. No explosives would be used,' and there would thus be no danger of blown-out shots, which often cause dust explosions. AU accidents due to careless handling of powder and carelessness in shooting would be entirely eliminated: Worked-out sections should be closed up perma- nently, and thus only a small portion of the property would be worked at a time, making it easy to ventilate and keep down the dust. The outlay for equipment and the expense of open- ing a mine with mining and loading machines is about the same as with the present system, assuming the machines to load only 60 tons per shift in the rooms. of Conveyor, Storage Hopper and Car. Boat arrivals at Hampton Roads are still irregular. At all times recently there has been a surplus of coal . over bottoms, and not yet have the Hampton Roads shippers felt very seriously the shortage of labour. Each week more of the new lake-built steamers appear with cargoes of Cape Breton coal, discharge, and go to the loading ports to join the coal fleet. That is one of the few encouraging signs in the coast- wise trade, and it is quite possible that during August receipts will show a decided increase through this additional cargo space and the increased movement via the Baltimore piers. Prices at Boston on the smoke- less coals are still on a high basis. Recent cargoes of New River have sold all the way from 8-35 dols. to 9-90 dols. f.o.b cars Boston for distribution inland, the range varying with demurrage and other con- tingent charges. A Philadelphia correspondent refers to the lack of anthracite, and speaks of empty yards, disgruntled dealers, and an impatient public. The new freight rates went into effect recently, and on domestic coal amounts to an increase of 45 c. a gross ton, which makes the rate on the bulk of the coal reaching this market 1-95 dols., although on shipments from some of the other regions it is 2 dols. and 2-11 dols. This increase has placed the dealers in an even more diffi- cult situation as to the deferred orders on the books. There is no chance, apparently, of giving the public anything like the two-thirds supply which had been planned. Some new method of curtailment in early deliveries may now be worked out. In the Pittsburg area, while coal production is in the main increasing slowly, it is not increasing as the requirements are increasing with the constant speeding up of war work, and serious shortages are now more clearly in prospect than they were a few weeks ago. In the case of foundry coke, many of the large con- tracts expire, and quite a number of these have not been renewed, operators seeing a good market from