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Sub-aqueous mining of anthracite coal
352
CURRENT TOPICS.
[J. F. I.
mental advantage, however, lies in its ability to withstand a marked increase in speeds and feeds over those previously used with highspeed steels. Among the already numerous machine shops employing stellite, the Fonderie des Gobelins in Paris reports that a daily production with high-speed steel of i2o shells of 155 mm. was increased to 200 by the use of stellite. With high-speed steel 2i minutes were consumed in roughing out at a speed of 17 meters and a feed of o. 7 mm. F o r finishing, the same speed and feed were employed and the same time was consumed. With stellite the roughing-out occupied I I minutes at a speed of 25 meters and a feed of o.85 mm. For finishing a speed of 37 meters was maintained with a feed of 1.67 mm. consuming 4 minutes. F o r completely finishing IOoo shells of 155 mm., the cost of stellite is about o.3o francs per shell. Other firms report equally favorable results in this class of work. Sub-aqueous Mining of A n t h r a c i t e Coal. P . A . ROCHE. (Scientigc American, vol. cxvi, No. 4, P. 98, January 27, I 9 1 7 . ) - - P r e s ent day conditions as to the utilization of anthracite coal are now so acute that we find in actual operation plants to recover from river beds by sub-aqueous mining the fuel that for nearly three generations has been buried under water in many of the streams that flow through the extensive anthracite coal regions. The smooth surfaces worn by attrition, it is true, have not ~the glitter of the freshly mined " black diamond," but the combustion value is in nowise impaired, for it happens that the product is the best coal of the mines. These deposits of coal, found in deep layers just above dams, and in pockets where small river whirlpools existed, are easily reached; and the centrifugal pump, traveling bucket conveyor, and even the Archimedes screw are now winning between half a million and a million tons yearly of this previously ignored valuable material. In the Schuylkill region a move was initiated towards a systematic modern handling of coal laden river bottoms, and it may be remarked that the past half dozen years has seen a great increase in the number of dredging plants throughout the anthracite coal country. No land need be purchased as for surface mining; no driving of shafts, etc., and in many cases no payment of royalties: an investment of $2ooo in a pumping plant, second hand canal boats and like equipment, and the river operator is equipped for work. At the most liberal estimate the cost of getting the coal out of the water is I2 cents per ton. The price paid by one consumer who uses nearly the whole output of two of these plants, each consisting of one battery of pumps, is $I.35 per ton at the point where shipment begins. The Susquehanna and Schuylkill as well as the Lehigh are surrendering the buried coal. With closer and more scientific working up of the coal as it comes from the mines, the ugly, disfiguring culm dumps spread over a naturally picturesque landscape will be a thing of the past, and perhaps the small river industr?T too, but hardly for a generation or more.
CURRENT TOPICS.
[J. F. I.
mental advantage, however, lies in its ability to withstand a marked increase in speeds and feeds over those previously used with highspeed steels. Among the already numerous machine shops employing stellite, the Fonderie des Gobelins in Paris reports that a daily production with high-speed steel of i2o shells of 155 mm. was increased to 200 by the use of stellite. With high-speed steel 2i minutes were consumed in roughing out at a speed of 17 meters and a feed of o. 7 mm. F o r finishing, the same speed and feed were employed and the same time was consumed. With stellite the roughing-out occupied I I minutes at a speed of 25 meters and a feed of o.85 mm. For finishing a speed of 37 meters was maintained with a feed of 1.67 mm. consuming 4 minutes. F o r completely finishing IOoo shells of 155 mm., the cost of stellite is about o.3o francs per shell. Other firms report equally favorable results in this class of work. Sub-aqueous Mining of A n t h r a c i t e Coal. P . A . ROCHE. (Scientigc American, vol. cxvi, No. 4, P. 98, January 27, I 9 1 7 . ) - - P r e s ent day conditions as to the utilization of anthracite coal are now so acute that we find in actual operation plants to recover from river beds by sub-aqueous mining the fuel that for nearly three generations has been buried under water in many of the streams that flow through the extensive anthracite coal regions. The smooth surfaces worn by attrition, it is true, have not ~the glitter of the freshly mined " black diamond," but the combustion value is in nowise impaired, for it happens that the product is the best coal of the mines. These deposits of coal, found in deep layers just above dams, and in pockets where small river whirlpools existed, are easily reached; and the centrifugal pump, traveling bucket conveyor, and even the Archimedes screw are now winning between half a million and a million tons yearly of this previously ignored valuable material. In the Schuylkill region a move was initiated towards a systematic modern handling of coal laden river bottoms, and it may be remarked that the past half dozen years has seen a great increase in the number of dredging plants throughout the anthracite coal country. No land need be purchased as for surface mining; no driving of shafts, etc., and in many cases no payment of royalties: an investment of $2ooo in a pumping plant, second hand canal boats and like equipment, and the river operator is equipped for work. At the most liberal estimate the cost of getting the coal out of the water is I2 cents per ton. The price paid by one consumer who uses nearly the whole output of two of these plants, each consisting of one battery of pumps, is $I.35 per ton at the point where shipment begins. The Susquehanna and Schuylkill as well as the Lehigh are surrendering the buried coal. With closer and more scientific working up of the coal as it comes from the mines, the ugly, disfiguring culm dumps spread over a naturally picturesque landscape will be a thing of the past, and perhaps the small river industr?T too, but hardly for a generation or more.