Bucyrus International recently commissioned a 49HR rotary blasthole drill equipped with a 3,800 cfm (107 m~3/m) air compressor at a high-altitude copper mine in Chile—the first of two Bucyrus 49HR Drills with the high-capacity air compressors that will be delivered to the mine in 2009. According to the company, since the mine is situated at an elevation of 14,763 ft (4,500 m), it's an ideal environment for these specially equipped drills. Air compressors de-rate at high elevation and in high-temperature environments, causing bailing velocity to decrease. As bailing velocity deteriorates, so does drill productivity. The high-capacity compressors, with an operating pressure of 65 psi (448 kPa), allow drills to maintain target bailing velocity of 8,000 to 12,000 fpm (2,240 to 3,660 m/min) along with optimum radial clearance of 1 to 2 in. (2.54 to 5.08 cm) in both high elevation and high temperature environments. Bucyrus said drills equipped with the high-capacity air compressors are also well-suited for mines with fractured rock strata, where pressurized air can leak into ground cracks, causing loss of air volume. The added capacity offered by the 3,800-cfm compressors reduces the net loss of air volume in porous ground, maintaining target bailing velocity and optimum radial clearance. In addition to productivity benefits, Bucyrus said drills equipped with the high-capacity air compressors offer potential energy savings for mine operators. Because these compressors run at an operating pressure of 65 psi (448 kPa), compared with 110 psi (758.4 kPa) from standard compressors, the drill requires less horsepower.
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