Por:Bill Welgoss (Seen in Aggregates Manager, 05/1995)


Located near the top a steep mountain that rises 600 ft from the road, Mark West Quarry, Santa Rose, Calif., presents many plant design challenges, Foremost, the handling of material, with little room to stockpile it. To get the most from the deposit, Mark West Quarry relies heavily on engineering to meet its challenges.


“In most site situation, you can do OK by just moving things around, and we’ve done that,” says Mark West Quarry Owner Dean Soiland, “But, after seeing what the experts can do with a steep 600-ft mountain, I’m a firm believer in an engineered plant.”


The company produces all types of road-based aggregates including chips, base rock, rip rap, asphaltic aggregates and subbase, says Plant Manager Bill Reid. Its market area includes upper Napa Valley, central Sonoma County and lower Lake County.


Plant layout was initially set up to create safe, level areas for processing equipment and larger rolling stock, as well as address plant runoff concerns in the environmentally sensitive area.


“There way we’ve attempted to deal with our situation is to stair-step our way up the hill by creating various benches,” says Soiland. “Plant layout is very workable with processing taking place on three levels.” The benching and stair stepping have also proven successful in controlling drainage and run-off.


Soiland says the initial stair-stepping plan was not a wasted effort. The basic layout remained as the plant further evolved towards better production efficiency and product quality.

Engineering Flexibility
To best utilize the tight confines of the site, the plant was engineered to provide processing flexibility with a minimum of stockpiling. In its present set up, the plant can produce a variety of road-based aggregate product on customer demand, with the ability to custom design to a customer’s needs.


“We can start a run on lesser quality material – rock that otherwise would have been waste material – and convert it to a higher grade,” says Reid. Plant components begin with a SECO 42 x 16 vibrating grizzly that feeds a 30 x 42 Kue-Ken Big Bit jaw crusher. The crusher is mounted on a Fabtec portable chassis. “We designed the hopper extension so that the jaw is gravity fed from an upper level bench 25-ft higher,” says Reid.


From the jaw, the material travels by a large overhead stacking conveyor to a surge tunnel with about 5,000 tons of live storage. Two variable-speeds conveyors feed the material to a secondary plant primary screen, a 7 x 20 triple-deck Telsmith Specmaker. From this point, the plant offers a variety of options. Material can be conveyed to the standard crusher, the fines crusher, to base rock or to other stockpiles.


The secondary crusher is a Telsmith 44 standard powered by a 200-hp electric motor. It uses a 30-ton surge bin with a variable speed belt feeder to control the flow of material into the crusher. The crusher discharges onto a belt that conveyors the material to a secondary screen, a 6 x 20 triple – deck Telesmith Specmaker. From this point, material again can go to the standard crusher, fines crusher, and base rock or be stockpiled. Material can also pass onto a tertiary screen to the fines crusher, based rock or be stockpiled.


The tertiary crusher is a dual drive, 500-hp REMco SandMax 9000, which was installed in February 1995 to replace the original 44-in. fine head cone crusher that could not produce sufficient quantities of asphaltic concrete sand. The new tertiary crusher is fed by a 30-ton surge hopper with a variable speed belt feeder. The crusher feeders adjust automatically depending upon the amperage of the crusher motors.


Other details of the plant include the use of rock-on-rock chutes to minimize abrasion, noise and maintenance. The chutes are infinitely adjustable to provide balance and inventory control, as well as good control over the specifications balance of the crusher, says Soiland.


“All stockpiles get a little bit of material from all the crushers,” says Reid. “The plant can recirculate everything until it drops as dust.” The characteristics of the deposit – a hard, dense basalt material that gets harder as it gets finer, says Soiland – made the choice of a high horsepower vertical shaft impact machine a good fit.


REMco markets the crusher specifically to produce tight specification product, such as concrete, masonry, and asphalt sand. According to Reid, the plant has tripled its output of small-end material: “We’ve getting 400 to 450 tph through put, some of which is unfinished and is recirculated.”


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