Show DATA ON DRILL TRIAL AT BUCKEYE BELMONT MINE letson balliet E M specialist on efficiency fici ency in mine operating has prepared some interesting data on the trial of a new drill in the buckeye belmont mine of tonopah To nevada as follows conditions elevation of mine surface feet above sea level compressor 2 stage angle compound type sullivan power electric motor belted to compressor drill water feed Dread dreadnought naught denver rock drill co drill work 1200 feet depth 2500 feet from compressor guage pressure maintained pounds water furnished in tank with air pressure formation tight crosscut section average 7 feet by feet date of test july 18 to 31 inclusive 14 shifts average temperature 89 degrees F while drill was running average atmospheric humidity 12 per cent while drill was running cost of electric power 3 cents per ewh kwh compressor efficiency horsepower per cubic foot delivered per minute cost per cubic foot of air compressed results drilled fourteen rounds eighteen holes to the round total sixty feet per pound in the whole fourteen rounds drilled feet of drill hole advanced the crosscut fifty six and one half feet time of drilling each round averaged three and one half hours longest time for one round 4 hours and 45 minutes shortest time for drilling a round 2 hours and 15 minutes total hours air compressor furnished air to this drill forty nine hours lost time drill idle ten hours in fourteen shifts average number cubic feet air furnished by compressor for this drill average horsepower delivered by compressor motor twenty meter readings showed 17 kwh ewh used per hour average cost of power per drill shift compressing this drill happened to be running at a time when no other drill was running in the mine and the compressor could be stopped when the drill was not running ventilating with compressed air was not allowed 1000 cubic feet of air per minute at per cubic foot costs 7 cents per minute for twenty minutes would cost ventilation was accomplished with a blower or fan discharging through an eight inch pipe to the working face 1 cubic feet for twenty minutes costing 1 cent showing that with power at the same cost ventilating with compressed air costs times as much as ventilating with blower fans |