In quarry operations, it’s not easy to replace a piece of equipment that has provided decades of reliable service. However, when that equipment has outlived its practicality and replacing it can significantly reduce downtime and increase production, nostalgia takes a back seat to good business sense.
Such was the scenario confronting the Sand & Gravel Division of Wildish Construction Company in late 2004.
For more than 28 years, the Eugene, OR-based firm had relied upon a cable-driven Lima shovel as part of its quarrying operation. In its day, the shovel had proven a real workhorse. However, the ravages of time, coupled with the development of newer and better technology, prompted Wildish to look at other options.
The upshot of its search was a Hitachi EX1900, which, in its short tenure at the pit, has already made a measurable mark on production and overall performance.
Key to the Operation
A family-run business — third generation and counting –– Wildish quarries more than 1.5-million tons of material a year, supporting its own concrete and asphalt operations as well as outside sales.
According to Mike Wildish, who shares the title of vice president with brother Steve and cousin Bill, the performance of the cable shovel has always been key to the overall production of the quarry.
“We rely heavily upon the equipment providing that function,” he said. “If it goes down, we go down. The cable shovel was purchased in 1976, so it was really becoming a challenge to keep performance up; we knew we were in need of a change. We had actually started looking at Hitachi machines a number of years ago.
“It just so happened that Papé Machinery, with whom we’d had a great relationship for about 30 years, took over the Hitachi line here a few years ago. We already knew them and had grown accustomed to the level of service and support they provided, so making the move was easy,” he added.
Wildish’s approach to quarrying differs from most others doing similar work — it employs more than two mi. of hopper-fed conveyors, rather than haul trucks, to get its material from the pit to the plant. Studies showed that a more efficient way to feed the hopper would improve production.
According to Mike, a combination of the EX1900’s larger bucket, faster cycle times and far improved breakout force accomplished that and have made the transition to the new unit a positive one.
“In our operation, we mine in two separate lifts. The top-lift material, which is roughly the upper 15 to 20 feet, is high-quality material for asphalt and concrete,” he said. “The secondary material, from 20 feet down, is of lower quality and, by itself, is only suitable for use as structural fill, road base, and so on.
“To maximize our resources, we employ a system of downstream material scrubbers and washers that allows us to blend the top lift with the secondary lift material and still meet the concrete and asphalt specifications,” he continued. “However, the density of the material rendered the cable unit ineffective for anything lower than about 50 feet. With the Hitachi’s breakout force, we are already down to a depth of about 80 feet; that’s additional material which was previously not obtainable. In addition, the bucket on the EX1900 has a 14-yard capacity versus the cable shovels’s 8-yard bucket, and the cycle time is easily 50-percent faster. Our biggest problem now is getting the wash plant to keep up with what the EX1900 is sending it.”
Mike added that, since replacing the cable unit with the EX1900, production itself has increased 15 to 20 percent.
“The biggest thing for us, however, has been the uptime,” he said. “Once you factor in the added performance and reduction in downtime, the Hitachi EX1900 has actually made us about 30- to 40-percent more productive, and that’s a significant improvement.”
Crossing the River
Adding the EX1900 will probably extend the life of Wildish’s current quarry site, but that has not stopped them from adding more acreage directly across the McKenzie River — purchased over the course of 37 years.
To get material from that location to the plant obviously involves conveyors. However, strict Oregon environmental regulations presented a challenge as to how to support the conveyors across the river. The solution — an 800-foot-long suspension bridge which, at no point, touches the river — is one that only Wildish could have executed.
“We have a dedicated Highway/Heavy Division of which bridge construction is a big component,” said Mike. “We did all the work on the cable-stayed suspension bridge except for the actual stringing of the cable. We even set up a portable precast plant and cast our own panels for the structure. Having access to the new site will allow us about another half-century’s worth of product, and it’s a pretty safe bet a Hitachi unit of some kind will be moving that material.”
Wildish Construction Company is serviced by Papé Machinery in Eugene, OR.
(This story appears courtesy of “America’s Mines & Quarries.)
Today's top stories