During the famous 1849 Gold Rush, miners panned for gold in California streams. Many years later some enterprising companies took it to a new level by “panning” a number of river valleys in northern California with floating dredges.
One such dredging operation started circa 1936 and continued into the early days of World War II. A 100-yd.-long barge-mounted dredge was used to “pan” the Scott River Valley just south of the Oregon border near Yreka, Calif., in Siskiyou County. On the front end of the dredge was a 76-unit rotating bucket line that dug up dirt and rock. Gold was removed inside the hull, using a trommel screen apparatus with .25 and .5 in. (.6 and 1.3 cm) holes. A 120 ft. (36.5 m) long stacker at the back of the barge deposited the dug-up rocks in giant windrows.
For Eagle Peak Rock & Paving, Alturas, Calif., the “gold” is in those windrows of large, smooth, very hard rocks still remaining from the dredging operation.
“Our mining consists of crushing the rocks for use in our two asphalt plants,” said Eagle Peak President Tony Cruse. “Our equipment includes three Terex Pegson crushing plants and two Powerscreen dry screen plants, all in closed circuit. We produce what we call asphalt rock. This includes 3/8 inch clean, 1/2 inch clean and Number 4 — 0 inch crusher dust. We blend all three in the asphalt production process. We reject all natural sand.”
The closed circuit process consists of several steps. Material from the rock windrows is fed into a Terex Pegson XA400 26x44 jaw plant and crushed to 5 in. (12.7 cm) size. The 5 in. goes to a Powerscreen Chieftain double-deck dry screen that rejects 1 in. (2.5 cm) minus stone. The 1 in. plus goes to a Terex Pegson 1300 Maxtrak cone crusher that produces 2 in. (5 cm) minus which goes to a Powerscreen Chieftain 2100 triple-deck producing 3/8 in., 1/2 in. (.95 and 1.3 cm) and crusher dust. The oversize goes to a Terex Pegson 1000 Maxtrak cone, which also produces 3/8 in., 1/2 in. and crusher dust in closed circuit with the Powerscreen triple-deck.
“The rock feed material is very, very hard,” Cruse pointed out. “But our crushing and screening equipment handles it very well. We do gradation testing on samples every 500 tons. That’s six samples a day. And the product is very, very consistent. I couldn’t be happier with that. In addition, we move our entire crushing and screening system fairly often, and the Terex Pegson and Powerscreen equipment sets up and tears down quickly and easily.
“Also, our dealer, Powerscreen of California provides excellent service backup,” Cruse said. “They’re here anytime we need them, and sometimes they just show up on their own to check everything over onsite wherever we are. I’m so happy with the Terex Pegson and Powerscreen equipment that I’m considering getting more.”
Part of the durability and dependability of the equipment and consistency of the products is due to the Paktronic control panel on the Terex Pegson cone crushers. This control sets the close setting and shows the current setting. Further, the control senses anything uncrushable entering the crushing chamber and lifts up (dumps) to allow it through and then automatically goes back to the current setting. The control also records and displays wear so the user can always tell how much life is left in the liners.
The Terex Pegson 1300 and 1000 Maxtrak cone crushers include a feed hopper, product conveyor, crushing chamber and power pack on a single chassis. The plants are engineered for high specification, flexibility, mobility and low operating costs. The 1000 Maxtrak can crush up to 220 tons (200 t) per hour and the 1300 Maxtrak up to 420 tph (381 t), depending on the application. Normally no prescreening is required. The hydraulic system can be adjusted quickly, even while crushing. The entire feeder-hopper assembly can be hydraulically lowered into the feed ring for transport or raised for re-metaling.
The Terex Pegson XA400 26x44 jaw crusher is designed for powerful performance in high production quarrying, demolition and mining operations. An aggressive crushing action with a single-toggle, high-swing jaw facilitates greater material entry to the crushing chamber. The design incorporates a hydraulic setting adjustment system that changes the jaw size at the press of a button for subsequent quick product sizing changes, thus reducing downtime. Throughput capacities range up to 400 tons (363 t) per hour, depending on material and setting.
The Powerscreen Chieftain 2100 two-deck 20x5 dry screen is designed and built for large-scale operations. The unit provides constant, uniform sizing and can process up to 500 tons (453 t) per hour, depending on mesh size and material type. The force in the screen provides optimum performance in wet, sticky applications. The plant is highly mobile and sets up ready to run in 15 minutes. Typical applications include crushed stone, concrete/asphalt rubble, sand/gravel, topsoil and coal.
This story also appears on Aggregate Equipment Guide.
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