Mobile Crushers Add Opportunity for Drill-and-Blast Contractors and Value for Customers

Idaho was the third fastest growing state between 2004 and 2005 according to the United States Census Bureau. The capital, Boise, is growing despite the fact that the region's geology is far from ideal for new construction.

Boise - like most of the state - sits on deposits of vesicular basalt that come to the surface or are covered by a thin layer of topsoil. Most new construction in the region involves some method of rock removal.

Jerry Dilley, president of Superior Blasting Inc., and Dan Lafferty, president of Dan Lafferty Construction Inc., share a common goal: drill and blast rock to make way for new construction on jobs ranging from private subdivisions and public roads to agricultural spreads for Idaho's burgeoning dairy industry.

They've seen many competitors use alternative methods such as sawing and trenching to remove rock from the region. In order to stay competitive and provide a greater value of service to their customers, the two men joined together to purchase mobile jaw crushers. Their joint operation is called J2D.

Crushing brings balance

In the old days, Superior Blasting and Dan Lafferty Construction were just responsible for drilling down to the proper depth and installing and igniting the explosives before moving on to the next job. The general contractor in charge of the site was left with piles of shot rock that had to be disposed of and had to find aggregate to bring back in as fill.

To solve this problem, J2D purchased a Komatsu BR350 mobile crusher five years ago and added a new, 180-hp Komatsu BR380JG-1 in 2005.

"It got to the point where people weren't taking rock anymore or were charging to get rid of it," says Lafferty. "Getting a hold of aggregate in south central Idaho is tough. The beauty of the crushers is that you can get into mass excavation, knock that stuff down to compactable structural fill and help the site balance and get rid of the import/export issue of trucking. That's where these crushers really shine is in helping to balance the site. Both of us saw the crushers as a way to make our businesses more competitive by getting rid of the waste issue and by making an unusable product useful."

Potential uses for the crushed rock include 3-in. minus as sub-base for road construction, 3-in. minus as engineered backfill for new construction and class 1 rip rap (8-in. minus) for ground cover along highways. J2D typically crushes waste rock down to 2-5-in. material, a practice that has nearly eliminated the problem of waste rock.

"People will come and get it, as long as you crush it down to something they can use." says Dilley.

Also, both crushers have the ability to remove soil from the crushed rock through a self-contained separator and muck conveyor. The self-designed, custom dirt belt on the BR350 and the factory-installed (optional) muck conveyor on the BR380JG-1 have helped provide optimum use of all material blasted, often leaving nothing behind.

"We need to pull that dirt out of the crushed material to make decent compactable base for any kind of structure-bearing surface," says Lafferty. "We're extremely careful about keeping the rock and dirt separated. If the crushers couldn't do that, we probably wouldn't be using them."

Reuse and recycle

With the explosive growth of the dairy industry in Idaho, Lafferty and Dilley have used the crushers extensively on sites to blast rock to make way for new dairy barns and underground utilities such as manure handling systems and bio-lab chambers. The expansion of the dairy industry has meant changes in the way farmers do business, which has also created a unique opportunity to recycle concrete.

"A lot of these agricultural areas are going to pivot irrigation rather than regular gravity irrigation," says Dilley. "So there have been thousands of feet of concrete ditch that have been ripped out. Both of those crushers eat concrete. It just bores through them."

Lafferty adds that they typically crush the concrete down to a 2-in. minus material that makes a perfect base for erosion-resistant roads and driveways on farms. A factory-installed magnetic separator ensures that no scrap steel or rebar gets in the mix. In addition to recycling concrete on these new projects, Lafferty reports that he has used the crushers to clean up worksites for former customers.

"We've actually gone back and cleaned up shot rock that we blasted 15 years ago," says Lafferty. "We've gone back to several of these sites and crushed 3-in. base for them to do additions or to build roads out to their irrigation projects."

The crushers have also proved effective for off-season projects such as recycling asphalt (ideal in winter due to the oil content in asphalt and the heat generated by crushing) and concrete washout at concrete plants where the need to recycle the aggregate it contains is high.

Versatility and productivity

The easy mobility of the BR350 and the BR380JG-1 has been an important advantage for Lafferty and Dilley. As Dilley says, "Most of our stuff is hit-and-run, drive-by-crushing."

Lafferty adds that you can move the excavator, unload that crusher, pull a couple of pins and be crushing in 5 minutes. Featuring the undercarriage of a Komatsu hydraulic excavator, each crusher can tram from pile-to-pile, eliminating second handling of material.

Lafferty also points out that the radio remote control on the BR380JG-1 has been a boost to mobility and operator awareness because the operator does not have to be on the crusher constantly.

J2D's BR350 has over 7,400 hours on it, and it still has its original hydraulic pumps and undercarriage and features all the same basic controls and functions as the day it was purchased - only high wear items such as the jaw linings have been replaced and/or rebuilt.

According to Dilley and Lafferty, the BR380JG-1 will crush almost twice as much 2-3-in. rock as the older BR350 thanks to a larger jaw. The BR380JG-1 features the largest jaw in its class, a load-presetting semiautomatic feeder system and an increased crusher rotation speed. Lafferty estimates that the BR380JG-1 will crush anywhere from 100-125 tons of 2-3-in. rock per hour and that the BR380JG-1 and BR350 feature similar outputs with larger stone over 6 in.

The jaw systems also have advanced to make the removal of clogged material easier and the recalibration of the jaws as simple as the touch of a button. While most jaw crushers protect themselves by bending toggle plates when jammed, the BR380JG-1 protects itself by allowing the locking cylinders to fully open the discharge port.

In terms of general maintenance and greasing, Lafferty and Dilley service both machines in the field and appreciate the added accessibility to major service points on the BR380JG-1. And while they haven't had to use it, they appreciate the fact that many key components of the crushers are interchangeable with their PC200 excavator.

"The BR380JG-1 is a lot easier," says Dilley. "It's light years ahead - you can actually get to the bottom of the jaw in the BR380JG-1 just by crawling through one of the inspection holes. There's much more room underneath for access than there is on the BR350."