Success in the Hitting the Mark on Stone Storage

by Aggregates Manager

Ready-mix operation feeds multiple aggregate silos with one, automated telescoping radial stacker.

The TeleStacker is programmed to discharge into openings on the tops of each of four 526-ton silos.

Aggregate is a precious resource in urban areas, forcing many ready-mix operations to truck material more than 25 miles. With increasing transportation costs, therefore, it is critical that producers implement cost-effective methods to feed, store, and transfer aggregate materials on site.

Loaders and stockpiles are increasingly expensive because of rising fuel and maintenance costs. Even operations located adjacent to a pit must minimize or eliminate loader use to remain competitive. Conveyors are advantageous because they require lower maintenance; produce less noise, dust, and emissions; and result in fewer labor hours per yard of material. Conveyor systems also offer the added advantages of extended hours of operation and longer useful lives.

"Any time you can replace rolling stock with stationary iron, you're much better off," says Bob Hurren, vice president of Concrete Operations at Jack B. Parson Companies (part of Staker and Parson Companies). "It's a huge savings. Belt systems don't require near the maintenance of yellow iron." Parson Companies has 28 ready-mix plants and additional portable plants.

When the company replaced a loader with an automated, telescoping radial-stacking conveyor at its Beck Street Plant in Salt Lake City, loading costs per yard plummeted. The company upgraded its 135,000 yards-per-year Beck Street Plant from a smaller portable operation to a fully automated stationery plant and installed a 130 ft. TeleStacker conveyor, manufactured by Morris, Minn. based Superior Industries. The stacker is programmed to feed each of four aggrega te storage silos and is controlled via a touchscreen panel. The radial stacking conveyor has a 24 in. discharge hopper that feeds into a 36 in. diameter opening on top of each of the four 35 ft. tall aggregate storage silos.

"The big demand on this customized automation package is getting a single conveyor to automatically hit the exact mark on any one of those feed openings, and do it in any order that we want," says Brandon Weaver, former plant technical advisor. "Other [telescoping conveyor] systems would have to be reprogrammed for every change."

The long-term goal is to direct belt feed from a nearby quarry to the stacking conveyor at the Beck Street ready-mix plant. Until then, the plant uses a drive-over truck unloading system. Belly dump trailers unload into a below-grade hopper that feeds the radial stacking conveyor. Drivers push one button to choose which aggregate silo to load, and the TeleStacker swings automatically to the feed opening. Each storage silo can hold 526 tons. An above-ground tunnel conveyor (also manufactured by Superior Industries) is designed to intersect and run through the series of silos. The tunnel conveyor system (with radiant heat) eliminated the need for excavation and minimized installation costs.

"When a silo is full, we simply hit the touchscreen, then we can swing it over to fill the next silo off the same belt," says Hurren. "If we are bringing in a load of specialty material, we can swing the conveyor over to the side to build a stockpile, if we need to."

The telescoping conveyor consists of a stinger conveyor mounted inside an outer conveyor of similar length. The stinger conveyor can move linearly along the length of the outer conveyor, thereby varying the location of the discharge pulley. The height of the discharge pulley and the radial position of the conveyor also are variable.

The automation package used at the Beck Street Plant accesses a programmable logic controller (PLC). An encoder is mounted to the winch that extends and retracts the stinger conveyor. Throughout extension or retraction, the PLC is aware of the exact location of the stinger conveyor, making its movements programmable.

Truck drivers push one button by the drive-over hopper to choose which aggregate silo is loaded. The stacker moves automatically to the silo.

The Bottom Line
Jack B. Parson Companies installed an automated aggregate silo-loading/feed system at its Beck Street ready-mix plant to minimize the use of loaders. The system uses a telescoping radial stacker that is programmed to move at a push of a button to any of four silos.

To submit a suggestion for a Success in the Field or for more information about any of these stories, contact Aggregates Manager at 330-966-2454, Fax: 330-966-2454 or email at bob@aggman.com
  NEWS | PROJECTS | COMMUNITY