Specifying an Excavator


Whether you’re mining on the mountains, at a quarry or underground, matching the proper excavator to the project is critical to achieving maximum productivity at the lowest cost per ton.

“Few machines work harder on mining jobs than excavators. These machines are digging and shoveling overburden or breaking up rock in some of the most abrasive environments on earth,” said Doosan Excavator Product Specialist Shane Reardon.55-LH-310

When you’re thinking about supplementing production with an excavator, it’s important to meet some key objectives including utilization, machine capacity and loading cycles. In addition to productivity, it’s critical to evaluate machine durability and serviceability to be successful and profitable in challenging conditions. And, it’s reassuring to know that an acquisition will be strengthened with flexible finance options, extended warranty support, and the backing of a trained and responsive dealership.

To be certain every important base is being covered in the purchasing process, Reardon offered the following five factors to consider when specifying an excavator to perform mining and quarry work.

Fit the fleet. While excavators in the 33- to 44-ton size class are typically best designed to handle the rigors of aggregate mining jobsites, Reardon said buyers need to identify the tasks the machine will be performing and the material that needs removed. Will the excavator perform a single job or multiple jobs? Will the tasks it’s needed for today be the only work it performs during its lifetime in your fleet? The answers to those questions can help define the role of a new machine in your fleet.

“Leveraging excavator attachments to perform specific mining or quarry tasks can significantly increase utilization rates, while also increasing functionality. With several different types of buckets and specialty attachments available, excavator capabilities can be maximized to complete a variety of projects in mines and quarries,” Reardon said.

Right now, you may need to dedicate an excavator to digging with a rock, heavy-duty or general-purpose bucket. However, excavators that are set up with two-way hydraulics and a thumb or grapple can efficiently pick up those pieces in quarry projects. Likewise, the power of excavators combined with the versatility of high-impact breakers allows operators to perform a growing variety of tasks in mines and quarries. Those include primary breaking and secondary breaking or “oversize breaking” of blasted rock to sizes more manageable for crushers.

Be productive and profitable. Excavator productivity can be defined a number of ways, but some of the most common metrics are machine horsepower, hydraulics, and digging and lifting capacity. Since an excavator’s bucket is typically its biggest revenue generator, its size and capacity are naturally important factors for productivity – but so is the type of material. Once you’ve determined daily production targets, calculate the density of the material and match it to the size and capacity of a bucket, and then look at the size of the machine needed to complete the job.

Machines designed for finish production in a quarry or mine are often working with aggregate ranging from fine sand to large rock. Due to these varying material densities, Reardon said it’s important to spec the bucket based on the heaviest material it will handle.

“Calculate for the high-end density values of the material in the work environment,” said Reardon. Materials like sand that absorb moisture will be heavier wet than dry. Additionally, clean, washed aggregate densities can vary greatly from base fill densities.

Machines that are engineered with a system of different power modes can help operators establish proper levels for mining or quarry operations. This capability can provide appropriate levels of power and performance for tough digging conditions and truck loading tasks, and also protect engine systems and structural components from stress.

Partner with the right hauling equipment. A primary goal of any excavator owner is to accomplish tasks and reduce loading cycles for maximum efficiency, but it’s easy to mismatch equipment. One of the best ways to ensure desired production is to pair an excavator to its hauling equipment, so that neither the excavator operator nor the hauling truck operator will have long waits between loads.

56-LH-400“A bucket properly matched to its material and equipped with adequate lift capacity and dump height could reduce the number of passes needed to fill trucks,” said Reardon. For example, industry consensus is typically between six and 10 passes to fill an average dump truck with an excavator. For maximum production, the number of passes to load should be between three and five.

Determine a machine’s durability. Excavator durability in mining environments is a key point to be evaluated. Long carriage designs can enhance performance in heavy digging and lifting operations. Look for sturdy frames, reinforced upper structures, plate thickness and internal gussets inside an excavator’s boom and arm for maximum rigidity.

One-piece cast bosses for pin-up points and hard wear discs can increase the overall durability of the bucket area, improve breakout forces and contribute to a longer life for your workgroup in tough applications. Excavator models that incorporate guards and shields designed to protect the excavator’s undercarriage – and protective methods for hose routings and components – can contribute significantly to durability in challenging mining environments.

Seek dedicated dealership support. Beyond the machine itself, the support of a full-service dealership can help companies evaluate the overall cost of ownership by taking a comprehensive look at a purchase past the machine’s initial acquisition and residual value.

In a rocky environment, wear will be greater on the ground-engaging tools, the undercarriage and other wear items. In addition to understanding the terms of manufacturers’ warranties, dealers can provide insight into the potential for any additional preventive maintenance expenses during its working life. Machines equipped with fleet management systems can link dealers to equipment to enable the transfer of key diagnostic information and faster response times.

Seeking out a dealer with a reputation for helping contractors meet deadlines and minimize downtime with parts availability and maintenance can be invaluable. Quarries and mines can be pretty intense applications, so dealer support in the form of mobile service trucks and fast parts availability are critical as well. Finally, dealerships will be the most knowledgeable and qualified to meet iT4 (interim Tier 4) and Tier 4 technologies and their maintenance requirements.

Information courtesy of Doosan Infracore Construction Equipment America.

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