THE HOMESTAKE MINE
The largest gold mine in the world, employing an average of 3500 men and producing from $5,000,000 to $8,000,000 worth of gold bullion per year, has its principal properties and mines at Lead.
The Elliston Hoist, the largest now operated by the company, is 1850 feet deep. The 1200 H. P. hoisting engine with its hoisting rope, a 7¾ inch by ⅝ inch flat laced steel cable weighing 7 pounds to the foot, lifting a load of 10 tons, not including the weight of the cable from the bottom of the mine to the surface in a few seconds, is an interesting sight. Nearby are two air compressors, one delivering air at 80 pounds pressure for the use of rock drills and other machinery; the other compressing air to 850 pounds pressure for use of compressed air haulage motors.
Across the gulch the drill sharpening shop where 3000 drills are sharpened each day, and the foundry and machine shop are points of interest. The noise of operation of the stamp mill night and day, 365 days in the year make its location easily determinable. Here 240 stamps each weighing 900 pounds and dropping at the rate of 90 times per minute crush to a powder 1000 tons of ore each 24 hours. To each ton of powdered rock is added 2400 gallons of water which wash it over the silver plated copper plates. In another building it is re-ground, and the coarsest portion or sands sent to the Cyanide Plant. Here solution is accomplished by the addition of potassium cyanide, and the gold then precipitated by the addition of zinc dust. The finer portion of the powder or the slime is piped to the Slime Plant at Deadwood, where the gold bearing powder is caught in filter presses and the gold then extracted as before.
The Homestake Pumping Plant at Hanna, 6 miles from Lead, and the Hydro-electric plant at Spearfish, 15 miles from Lead, furnish the water and power used in the Homestake properties. The Hydro-electric Plant is the largest of its kind in the Hills. The water is carried in a tunnel 5 miles long from the river in Spearfish Canyon, at a point 8 miles from Spearfish, to the reservoir on top of the ridge overlooking and directly south of the city. The three surge towers, on the pipe lines leading from the reservoir down the 700 foot drop to the power plant, may be seen for many miles.