How RiverStone Group achieves an optimum yield from its crusher

One way to maintain optimum yield in cone crushing circuits is to combine the latest equipment and technology with application expertise and responsive life cycle management.

The latter is essential when fine-tuning a crushing circuit for peak performance, and it’s driven further with a producer-manufacturer partnership that ensures high production capacities and a low percentage of recirculating loads.

Circuits with high recirculating loads eat up more space and horsepower in the crusher while also increasing wear. Also, unnecessary recirculating loads send saleable material back to the crusher rather than to the finished product stockpile.

Minimizing recirculating loads is imperative for producers such as the RiverStone Group, which operates 15 quarries throughout Iowa and Illinois. As a family-owned business since the late 19th century, the company prides itself on pushing the envelope in productivity and innovation.

RiverStone is regarded for its Class A stone products, which meet Department of Transportation and Federal Aviation Administration quality assurance standards. At its Colona, Illinois-based Cleveland Quarry, the company recently upgraded its plant with higher-capacity primary and secondary crushers. For optimum yield of finished product at its tertiary circuit, the company installed a new P500HD Patriot cone crusher, manufactured by Superior Industries.

The result was increased plant uptime, long-term efficiency, reduced wear costs, minimal recirculation load and increased production capacities at lower costs per ton. Delivering a speedy return on investment, the site has nearly doubled its tons-per-hour output since the installation of the new crushers.

Maximum efficiency

Scott Skerston, plant superintendent at the Cleveland Quarry, calculated the circulating load ratios of the new Patriot cone. He reports that at a closed-side setting of 1 in., the cone processes finished product at a 78 percent throughput; and at a 1/2-in. closed-side setting, the throughput percentage reaches a high of 83 percent.

“We’re getting maximum efficiency and very little recirculating load while averaging 80 percent of our crushed material going directly out to the finished, saleable product stockpile,” Skerston says.

He attributes this in part to the cone’s spiral tooth bevel gearing system, which “engages more gradually, giving an efficient transfer of horsepower to the rock rather than to the structure of the machine.”

As a result, the cone performs at higher speeds with less noise and vibration.

“With its uptime and availability at more than 97 percent, the Patriot cone maximizes our production of A-quality concrete stone and asphalt chips,” Skerston says. “Before we added all the new crushers, we ran at just over 400 tph. Now we’re running steady at 800 tph due to our crushing advancements.”

Next-level technology

According to Skerston, the design improvements on the Patriot cone crusher make it more durable, reliable and user-friendly than older-style cones he’s experienced. Unlike most crusher models, he says, the Patriot cone crusher’s countershaft spins in a counterclockwise rotation, which causes the crusher to open if clamping pressure is lost, reducing the risk of catastrophic failure.

“This feature literally saved us last production season when a simple solenoid valve failed and would not reset the clamp pressure,” Skerston says. “The counterclockwise rotation allowed the cone to open, preventing any damage to internal components. When older-style cones lose clamp pressure, the bowl tightens down, often snapping the shaft and leading to machine failure.”

Another feature that prevents costly damage to the new cone’s crushing chamber is a unique tramp relief system.

“First, it’s designed with fewer accumulators for minimized maintenance, but most important is the inclusion of a secondary pressure-relief valve that ensures the crusher will open if a tramp event occurs,” says Mike Schultz, crushing product manager at Superior. “This means even if an accumulator fails, the secondary relief valve will provide immediate pressure relief, allowing the crusher to open.”

Additionally, Schultz points to an inverted design of the tramp release cylinders where the hydraulic cylinder rod seal is not exposed during operation. This reduces the potential of contamination and failure, he says.
Vantage, an in-house cone crusher automation package, is the latest addition to the Patriot series.

“It’s completely built in house with no third parties involved, allowing one-call service and support,” Schultz says.

Equipment life cycle management

As the RiverStone Group upgraded its crushing circuits, Skerston worked closely with Chris Wade, a customer service and technical support technician at Superior, which operates a 70,000-sq.-ft. crushing equipment and parts distribution center in Pekin, Illinois.

“Chris, along with the service and parts support team, has specialized in cone crushing for many years,” Skerston says. “They know how to analyze our application to make us more efficient. It’s such an advantage to rely upon the knowledge of the equipment manufacturer. The product and parts support is excellent, and the Patriot cone does just what it’s designed to do.”

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Carol Wasson is a veteran freelance writer for the aggregate and construction equipment industries.