The World's Largest Horsepower Driven Ring Gear Drives Chilean Copper Mine Sag Mill
Milwaukee, Wisconsin (USA) -- The world's largest horsepower-driven ring gear drives a
primary ore semiautogenous grinding (SAG) mill at the Escondida Cooper Mine in Chile's Atacama
Desert. Produced by Rexnord in the geared products plant, the custom-made, steel-cast gear is 43.27-foot (13.2 m)
in diameter and weighs 190,000-pounds (86,180 kilograms).
The Falk ring gear, with two pinions, is driven by two 9,000 hp (6,714 kilowatt), 176.5 rpm
synchronous motors. With a reduction ratio of 17.48:1, the drive is capable of producing 9.3 million
ft-lbs (12.7 million Num) of output torque with an output speed of 10.1 rpm.
The SAG grinding mill, built by Allis Mineral Systems, was recently installed at the Escondida mine.
The 36-foot diameter mill reduces large chunks of copper ore (up to 1-foot diameter) to smaller
pieces about the size of course gravel.
Until recently, the most common method for mines was to use a complicated and expensive
wrap-around motor configuration to drive large mills. Due to advances in technology for large gears,
mines can now use a more reliable, low maintenance and less expensive pinion/ring gear drive
configuration that is less vulnerable to dirt and debris resulting in continuous reliable operations.
The Escondida Copper Mine represents the largest technology investment in mining in the 1990's.
The mine is jointly owned by RTZ of England and BHP of Australia.
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