Extec Portable Crushing Plant Outshines Quarry's Stationary Stand-By

Story by Loren Faulkner | September 28, 2010

The average motorist driving through the Mojave Desert in Southern California sees only barrenness — low rolling hills and mountains in the distance. It can be a blank passage on the way to Las Vegas. But to others, there is "pay dirt" out there in the form of natural-colored rock ready to be quarried and crushed into shades as subtle as wine red, surf green and lilac.

It's a growing market segment as more contractors, home owners and businesses desire construction and landscaping that includes gravel and small rock with exotic, wide-ranging natural colors.

Few private quarries have this kind of product, but BruBaker-Mann, Inc., of Barstow, California, has been in business since 1950, and is said to be the largest producer of these decorative colored rocks in the state.

Rocks of Many Colors

"We are unique in the colored rock industry in that we have the widest range of natural colors: gold, green, pink, lilac, wine red, and white," says Julie Mann, president of Brubaker-Mann, Inc., Natural-Colored Rock. The company also produces crushed red and brown brick, as well as black and red cinders. The finished product is shipped by truck throughout California, Arizona and Nevada, from their Mojave Desert area plant in Southern California.

"The colored rock market looks very good for the foreseeable future in the Southwest," Mann says. "Water shortages are causing more local regulations to make landscaping drought resistant. And our quarries should hold their own for a long time." The white rock roof, a standard in the region, is still in big demand, and more homeowners are opting for decorative rock rather than trying to maintain water-thirsty green landscaping. Some contractors even add colored rock to concrete tilt-up building panels, which are then sanded to form a smooth, lustrous surface.

There are eight Brubaker-Mann quarries. The largest, a white rock quarry, is 55 miles northwest of Barstow; the surf-green quarry is 35 miles east, while the remaining quarries are within five miles of the headquarters' plant.

The finished crushed rock product is shipped and sold by the ton, ranging from $34 – $45 per ton. Brubaker-Mann produces some 50,000 to 70,000 tons of colored rock per year, according to Mann.

Back-up System

Bill Mann and Ron Brubaker cobbled together their original plant as needs arose over the decades. Starting with a 1902 model rock crusher, the two would do demolitions in the early years and haul scrap steel back to Barstow. An old railroad car, a water tank, other odds and ends kept the plant expanding and working. It may not have been stylish but it was always up to code. The problem, says Julie, is that equipment breakdowns were frequent the past few years and keeping up to code with dust and silt was challenging. She needed "Plan B," just in case. That plan has since turned into "Plan A."

"I originally did research for a portable crushing plant to use as a backup for our 56-year-old stationary rock crushing plant," she said. "It was a constant battle for our workers to unclog the various chutes and other gear from a buildup of material from the rocks and dust," she added. After all, the rocks would go into the rolls crusher as 16-inch minus, exit down the line as 6-inch minus, down to two other sequenced jaw crushers for proper sizing. "The stationary plant was difficult to move equipment around in, so all the cleanup had to be done by hand."

The Equipment

During her research, a representative from Extec, out of Perris, California, showed up at the Barstow plant. After a demo, within a short time three mobile Extec machines were purchased. One is stationed at the White Rock quarry; the other two are at the Barstow plant.

"With the new portable machines, we don't have that cleanup problem any more," Mann says. That's because when she got the portable Extec screeds as only a supplement, then saw how well the equipment performed, the decades-old stationary plant was brought to a halt.

"Extec Inc. was a big help, showing us how to use the right jaw crusher and screening plant to improve and speed up our production and get a much wider range of crushed/screened products at less cost." The screening and crushing plants selected were the Extec C-12 jaw crusher and S-5 Double screen.

"In the end it was the simplicity of the crushing and screening operation and the production capability of both machines that convinced us to buy. The machines can be easily tracked around a site, providing an operator-friendly system that enables us to make quick and easy adjustments," Mann says.

The Process

Quarry areas are drilled and blasted by explosive materials. Then, according to Extec info:

The C-12 is maneuvered to any position from an excavator or loader at the quarry face, where recently blasted colored rock is piled to the floor.

Up to 18-inch-sized boulders are fed to the jaw crusher direct from an excavator, where the vibratory feeder transfers the material towards the C-12 50-inch by 30-inch jaw crushing plant. As the rock advances downwards into the crushing chamber, it is crushed between the wear plates and deposited onto the main conveyor. Each rock is crushed an average of 2/2.5 times, as it passes through the jaw with a reduction ratio of approximately 6:1.

Crushed rock is then fed from the C-12 to the Extec S-5 Double screen, which separates the rock into 1-inch, 3/4-inch and 1/8-inch sizes. The S-5 uses a diesel engine to power to the hydraulic power pack, generating electricity for the electrical systems of the machine. The machine's tracks, hopper, conveyors, and all working parts are hydraulically driven.

The C-12 jaw crusher from Extec is designed to provide very high productivity in a mobile crushing system. The material passes over a series of screen meshes which separate the product into three grades. The larger and medium grades are separated onto the side conveyors, leaving the fines to travel up the tail conveyor. Each grade of rock then falls on to three separate stockpiles around the machine.


Compared to the original stationary plant, Brubaker-Mann has observed:

  • Clean gradings at high output, produced as material is exposed to large screening area.
  • A steep angle for the primary screen box, allowing most materials processed in the initial impact area.
  • Most undersize rocks are removed during initial impact.
  • Only near-size material passes to the secondary screen box.
  • Faster product cycle times.
  • Better stockpile volumes and quality.
  • Reduced truck use and haulage.

"Since we bought mobile gear," Mann adds, "the haulage trucks are only required during the day shift when the Extec's are producing material. Truck and haulage costs have been cut nearly in half. We're saving on labor, fuel and maintenance costs."

Bottom line: Mann says a single Extec portable machine outputs more than the stationary plant could.


Cousins Ron Brubaker and Bill Mann were in the Boy Scouts back in the 1930s and took many camping trips to the Mojave Desert. While exploring old mining and ghost towns like Calico and others, the two decided that they wanted to become miners when they grew up. WWII interrupted their plans temporarily, but after their service, the two eventually purchased small quarry stakes in the Barstow area.

It took years of after-hours and weekends from their regular employment; Ron was educated as a mining engineer, Bill earned his degree in history, but eventually the part- time mining operation became profitable. By 1958 both men were able to support their families by the quarry's output.

Over the years, Bill Mann also worked as an explosives/demolition expert and earned the nickname "short-fuse" Mann. His knowledge of the old mining towns and related sites in the area earned him a reputation as a local historian. So much so, that he was on the county museum board and went on to write six travel-guide type books on Southern California desert ghost towns and abandoned mining sites.

Julie says she may tear down her father's and uncle's old stationary rock crushing plant, but then again, it might better be kept as a piece of local history. It was the kind of history her father enjoyed so much.