Solution to bridging

By |  June 28, 2015

PPE0615_kinkaidstone1RTime dedicated to cleaning out a vibrating grizzly feeder and prying out rocks wedged between grizzly bars adds up. Especially when work crews must address pegging and plugging issues within a grizzly feeder multiple times per week.

Will Pyatt, general manager of Anna Quarries and Kinkaid Stone Co. in southern Illinois, estimates his crew at Kinkaid Stone previously had to address the grizzly feeder within one quarry three to four times per week at the end of shifts. That’s time Kinkaid Stone preferred to dedicate to production.

Yes, grizzly bars are an industry norm. But as Pyatt points out, traditional grizzly bars have some disadvantages.

“If you’re trying to pop a rock between the grizzly bars with a hydraulic hammer, that can cause damage to your equipment,” says Pyatt, who mines limestone at Kinkaid Stone.

Pyatt found a replacement to traditional grizzly bars in Grizzly Spring Fingers, an alternative from Dakota Equipment Manufacturing Inc. (DEMI). According to DEMI, Grizzly Spring Fingers are made from flexible spring tines that are designed and forged for the direct replacement of rigid-mounted grizzly bars or punch plates. They’re designed for all types of vibrating grizzly feeders, the company adds.

“What we really like about them is a couple of different things,” Pyatt says. “One, the bars: It’s much harder to bridge them over. They tend to have some slight movement in them along with the feeder, so it’s harder for material to get bridged up between the fingers as opposed to grizzly bars.”

In addition, Pyatt says DEMI’s bars are narrower than traditional grizzly bars. The design leads to more desired material passing through, DEMI says. Plus, Grizzly Spring Fingers reduce the amount of cleaning needed to remove rocks from between bars.

According to DEMI, Grizzly Spring Fingers eliminate all rock jams and allow all material to pass – even wet, sticky clay-like material.

“This product, like most others, developed because a solution was needed to a problem that has plagued the industry since the creation of vibratory equipment,” says Tim Holmberg, president and CEO of DEMI. “The vibrating grizzly feeder, combined with the typical tapered fixed bar or punch plate media positioned within the grizzly area of the feeder itself, typically operates with intermittent surge loads of extremely dense and heavy primary-based materials being dropped in from loaders or haul trucks.

“These surge loads, combined with other variables, often crowd the grizzly area and its media, [preventing] the proper conditions needed to shed, cut or separate the much larger particles from smaller ones.”

Grizzly Spring Fingers eliminate rock jams, according to DEMI.

Grizzly Spring Fingers eliminate rock jams,
according to DEMI.

Add excessive moisture and clays into a load, and Holmberg says grizzly bars can provide an increased level of aggravation.

“You will be one frustrated equipment operator having to not only shut down production but to physically be required to hammer or pry out the stuck rocks, which isn’t always easy,” Holmberg says.

Pyatt agrees Grizzly Spring Fingers eliminate the rock-prying bottleneck, and Holmberg says they extend the life of consumable wear media in a crusher by keeping unnecessary material from going through it.

The finer details

Although Kinkaid Stone uses Grizzly Spring Fingers over a Universal 5165 impact crushing plant that produces about 500 tph, Holmberg says the product can be customized to both stationary and portable crushing equipment.

“I can adapt it to fit into anything that has ever been built since the very beginning of conception,” Holmberg says. “There really isn’t any piece of vibratory or static classifying equipment with my background that I couldn’t make it fit.”

According to Holmberg, the only thing Grizzly Spring Fingers cannot provide is a spec-sized finished product. Grizzly Spring Fingers only size in one direction, he says, as they do not feature any cross or woven components.

Pyatt came across Grizzly Spring Fingers while visiting a company Holmberg previously worked for a few years back. Grizzly Spring Fingers were among the products Pyatt saw. He was intrigued.

“We later tried them in an application at our other quarry where we were having difficulty at our riprap plant,” Pyatt says. “A year or two later, we purchased a new vibrating grizzly feeder for our Kinkaid quarry, and we had Tim’s bars come in from the get-go.”

Anna Quarries, whose primary market is heavy highway construction, still uses Grizzly Spring Fingers in its riprap plant, as well.

“Our riprap plant consists of two vibrating grizzly feeders,” Pyatt says. “One controls the top size and the other the bottom size of the aggregate. We use the [Grizzly Spring Fingers] with the grizzly feeder to remove the fines.”

Previously, Pyatt says fines bridged in the grizzly bars. The bridging cost Anna Quarries about an hour of production time in each instance.

“We put in Tim’s system, and I don’t think we’ve ever touched it since,” Pyatt says.

DEMI’s system has also helped to reduce the amount of use of a pedestal-mounted boom system with a hydraulic hammer.

“We have greatly reduced how often we have to use that.” Pyatt says.

The system has proven to be a durable one too, he adds.

“At our quarry at Kinkaid, our material is shot,” he says. “You have 36-in. x 36-in. boulders going over and into those bars, and they’ve held up well.”

Kinkaid Stone is an Illinois limestone producer using Grizzly Spring Fingers in multiple applications.

Kinkaid Stone is an Illinois limestone producer using Grizzly
Spring Fingers in multiple applications.

Takeaways

Holmberg admits the first impression some producers have upon seeing his system is that it looks light duty. He says this is not the case, though.

“It looks light duty, but it’s strong,” says Holmberg, who adds that one system typically weighs between 35 and 40 lbs. “When people get their hands on the bar they realize it’s good.”

Holmberg adds that some of his customers have produced between 800,000 and 1 million tons before having to replace one. He says change-outs are easy, and Pyatt concurs.

“As far as installing it in an existing piece of equipment, it’s not that difficult,” Pyatt says. “In our experience, we had to do a little bit of prep work to our existing feeder with one of our welders. We removed the support system on the old grizzly system, added new cross members to support the new Grizzly Spring Finger system and then dropped the Grizzly Spring Finger system into place.

From start to finish, Pyatt estimates installation took about a shift and a half with two guys on the job.

“It’s really not a complex thing to do,” Pyatt says. “Tim’s very knowledgeable looking at your existing machine and knowing what type of bracing needs to be removed and what should be added.”

Grizzly Spring Fingers are useful with a number of materials, Holmberg adds, including concrete, asphalt and other recyclables. For Kinkaid Stone, the product has been particularly useful with its aggregates.

“In the quarry business there’s a lot of different processing situations,” Pyatt says. “There may be a few situations where you might be more comfortable with a standard bar. But in most cases, I would think [Grizzly Spring Fingers] would be the way to go.  In the future, we will be looking to use the Grizzly Spring Fingers any place we can.

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