May 2002
Dredge and dragline technology moves ahead in digging ability and mobility
Above: Rohr Twin 20-cu. yd. bucket dredge installed at Vulcan Materials Western Division’s operation in Irwindale, Calif.
Clamshell dredges and draglines have been staples for operations in the aggregates industry for many years.
Recently, however, technology has pushed the envelope of production capability of these units. Smaller units designed for mobility have also been developed to provide an economically sound alternate to mining smaller deposits over short time periods. This article will focus on three projects that present some of the ways these units are being put into action.
Twin 20-cu. yd. bucket Dredge
In January 2001, Vulcan Materials’ Western Division replaced a Rohr twin 13-cu. yd. clamshell bucket dredge with a twin 20-cu. yd. bucket dredge, nearly doubling its extraction capability.
The new dredge will be able plumb the 200 ft. permitted depth.
“With a retrofit of the drum, we can make it go down 300 ft.” said Jochen Rohr, president of Rohr U.S. operations. In Europe, continued Rohr, operations have Rohr dredges that go as deep as 550 ft.
“We can really speed up the machines underwater,” said Rohr. “We go down 500 ft. per minute, so if you have a cycle time of roughly 95 seconds at 100 ft., you are looking at may be increasing it to 125 to 130 seconds at 200 ft.”
This is the largest twin bucket dredge made by Rohr. Using ABB DC variable speed hoist drives, both buckets—working at a depth of 80 ft.—can produce 2,000 tph. Buckets are equipped with Rohr’s patented bucket monitoring and diagnostics system. The buckets have transmitters located at key points, which send information to an onboard computer.
The service and diagnostics system provides on-screen depictions of bucket tilt angle and opening and closing. The system also provides real-time data on hydraulic cylinder pressure, oil level and temperature, and oil filter condition.
The system also keeps track of historic information, such as, a listing of problems and downtimes, which can be organized by operating shift. Maintenance software and a frequency control drive protects mechanical parts from damage caused by peak loads when starting the motor. The last feature allows the operator to alter the closing time of the bucket to better fit the material.
“The best way to describe (the system), is that we made the buckets active digging tools,” said Rohr.
The system is also set up for Rohr upgrades that have not been installed yet. These include: a dredge global positioning system (GPS) and sonar scanning to present a depiction of the water bottom.
Vulcan specified on the dredge, what amounts to be a floating processing plant.
The buckets feed material onto a patented rake grizzly, which feeds the oversize into a Deister 4-ft. x 16-ft. rubber-lined vibrating feeder, which moves material to a 30-in. x 42-in. Pioneer jaw crusher. The grizzly rake can be reversed to discharge oversized material into the pond if the material is predominantly clay.
For each bucket, two Deister 8-ft. x 20-ft. double-deck, horizontal wet vibrating screens (about 1/2-in. opening top deck, 3/16-in. bottom deck) separate material. Two 8-in. Galigher Pumps—each pump able to handle 2,010 gpm of slurry—are used for each screen pair. The same-sized Galigher pumps are also paired with each bucket.
The Galigher pumps each feed two Warman Cavex 20-in. cyclones, which then discharge material onto two Deister 6-ft. x 12-ft. dewatering screens. Overflow, mostly 200 minus mesh material from the cyclones, go to a floating wastewater line.
Two of the 6-ft. x 12-ft. high frequency screens are used for each bucket, and two more same-sized screens are used for each Galigher pump pairing.
A Rohr onboard conveying system includes a 42-in. x 43-ft. belt conveyor for each system, which collects discharge from the 8-ft. x 20-ft. and the 6-ft. x 12-ft. screens and moves material to a 4-ft. x 66-ft. belt conveyor, which also collects discharge from the jaw crusher. This material is moved to a 800-ft. x 42-in. Rohr Series II floating conveyor system to the shore.
A Peerless vertical 4,000-gpm turbine pump supplies fresh water to the dredge.
To drive the dredging operation, Rohr specified two drive and motor-control stations powered by two 2,000 kVA 12 kV-480 volt transformers and two 480 volt switchboards.
So far, according to Rohr, Vulcan is very pleased with the performance of the dredge. Rohr originally anticipated production of 1,800 tph, and currently it is providing in excess of 2,000 tph. Since the machine was put into service, there has been no significant changes made to the system.
“For a project like this, the customer has to be an integral part, not just a bystander,” said Rohr. “We give great credit to Vulcan Vice President of Aggregate Operations David Pasley. We spent a lot of time together to make sure everything went right.”
7-cu. yd. Modular Dredge
Supreme Mfg. Inc., based in Stoneboro, Pa., is introducing a 7-cu. yd. modular dredge. The dredge uses modular components that can be shipped on 11 legal highway-weight truckloads, and can be assembled, according to the company, in one week. (AggMan, June 2001, Success in the Field, p. 28, which features a Rohr modular 6-cu. yd. luffing jib dredge.)
The dredge is capable of digging 160 ft. below the water level. One operator runs the automated machine and attached conveyor systems. It can be run via portable generators or commercial power.
Floating conveyors can be arranged in combinations from 100 ft. to 400 ft. individual lengths and total lengths to 1,000 ft. or more, according to Supreme.
Standard equipment includes:
• U.S.-built components;
• 7-cu. yd. spade nose bucket powered by a 70- to 100-hp motor;
• Deister 6-ft. x 6-ft., two-deck primary dewatering screen;
• Deister 4-ft. x 8-ft. dewatering fines recovery screen;
• Krebs cyclone;
• Galigher rubber-lined pump;
• Rockwell Automation/Allen-Bradley PLC; and
• Operator cab and control room in one enclosure.
Supreme Manufacturing also designs and builds conveyor components. The company is an out-branch of H&H Materials, a Pennsylvania aggregate producer with two sites, which use plant components designed and built by Supreme. H&H operates two 10-cu. yd. clamshell dredges designed and fabricated by Supreme.
President David Hoobler described the niche the modular dredge is targeting, “There are a lot of pits in Ohio, Pennsylvania and Michigan, where in the past, a company has dug with a small dragline or with excavators. When the pit floods, they’re done, even though there still is more material.
“These pits don’t merit setting up a $2 million dredge that takes six weeks to assemble and six more to disassemble. It is just not there. It is too expensive of a machine. The production of these machines is probably too much to handle for the portable plants these operations run anyway.”
The Supreme 7-cu. yd. dredge will be prewired in the shop and use bolt up connections. All components will break down into road portable units. For instance, the hoisting unit and boom base are fabricated in two pieces so it can bolt together on-site.
With these design features, Hoobler estimates the dredge will be able to be set up in a week.
“With the prewired and bolt-up connections inside the pontoons, we will be able to set the pontoons one at a time onto the water. We will be able to set up the pontoons in a day and assemble the rest of the dredge on the water,” said Hoobler.
Another advantage of building the dredge on water is eliminating the possibility of damage when a dredge assembled on-shore is pushed into the water.
According to Hoobler, Supreme can also build a floating crushing unit that would bolt up to the dredge if required.
“Production rate is proportional to digging depth and material, but should be able to do 300-tph plus, consistently,” said Hoobler, adding, “A clamshell dredge is real dependent on material. If you have a nice gradation—usually the coarser, the better—you can dewater a lot faster, and go faster.”
The design of the dredge uses a tilting boom rather than a gantry to raise and lower the bucket. The tilting boom is easier to assemble, disassemble and move, according to Hoobler. For remote areas, the dredge can be run with a 500-kW generator.
Supreme made a conscious decision to use parts that are either built in the United States or readily available.
“We would like to sell two to three of this particular size dredge each year,” said Hoobler.
Another attractive feature of the dredge is that electrical components and operator controls are in one unit.
“We don’t have to wire from one to the other,” said Hoobler. “Also, if you have to do a repair or adjustment, it is right there in the operator’s cab.”
Upon sale of a Supreme dredge, the company plans to offer a two-week training period, using the operators who have run the Supreme units at the H&H site.
20-cu. yd. Skyline dragline
Rainier Rigging has designed two 15-cu. yd. skyline draglines that are operating in the Washington State area. Now the company says it has the engineering done to supply a skyline dragline equipped with a 20-cu. yd. bucket—a machine that will operate using just under 1,000 hp.
“The design of the 20-cu. yd. system will be very similar to the 10- to 15-cu. yd. systems, just much bigger. It will get up in the neighborhood of 400,000 to 450,000 lbs. working weight,” said Rainier President Mike Walch.
Rainier started building prototype skyline draglines as early as in the 1970s. From the time when the company mainly operated as a logging company, using cable logging techniques, to near present, Rainier had built its skyline draglines for aggregate extraction by modifying cable logging equipment.
Today, Rainier Rigging designs and fabricates its skyline draglines from scratch. The equipment components are fabricated in a shop in Centralia, Wash. The components are then sent to a second shop for final painting, prepping and testing.
It has been about seven years since Rainier started designing and building machines specifically for aggregate extraction, which became its core business. The company also fabricates its own cast manganese bucket, a bottomless design developed by Sauerman many years ago.
The bottomless bucket is ideal for the type of extracting done by the skyline dragline. When the dragline begins digging into a flat floor, it slowly creates a ramp to pull material to shore. The deeper the dragline bucket digs, the longer and steeper the ramp becomes. At the point when the angle of the ramp reaches the angle of repose of the material, the dragline is then positioned further from the bank to change the digging angle. A typical installation may have the dragline set 400 ft. from the other side of the extraction area, where the other tracked tower guides the bucket. The mainframe machine will move back in 200 ft. increments as excavation progresses. Rainier has developed charts to give customers an idea of the economics of using different sized machines, digging to deeper depths.
One of Rainier Rigging’s 15-cu. yd. bucket units has operated in Washington state for about four years. It replaced a conventional dragline, not only because it can dig deeper, but also because it is more efficient, according to Walch: “We can actually produce material on shore cheaper than a dragline starting at track level. Because those machines have a lot more moving parts, they typically operate at 30 to 60¢ a ton. We have machines operating at 12¢ and 15¢ a ton—that was part of our objective: to dig cheaper, too.”
Rainier Rigging 15-cu. yd. bucket dragline is basically a smaller-scale version of the planned 20-cu. yd. bucket unit.
The Washington operation is currently digging to 60 ft., and, according to Walch, the operation will be able to go to the bottom of the deposit at 180 ft.
Given the length the bucket travels, sometimes along hard, abrasive material, the bucket teeth are a wear point. Rainier had to develop its own oversized, reinforced teeth to meet the unique requirements.
“Teeth on the bucket can last anywhere from two to six weeks,” said Walch.
Here’s a breakdown of changeout times of lines: inhaul line takes 30 min. to 1 hour; outhaul line and skyline takes 1 to 2 hours.
Modifying suitable logging equipment requires slowing down the operating speed by changing the gearing, torque converter and clutch.
“Actually, we are finding it cheaper to build a new skyline dragline from scratch than to re-engineer it from logging equipment,” said Walch. “A lot of the logging hoists we had to dismantle totally and rearrange the drums. If the gears didn’t mesh properly, we had to build a new gear. Now, we are actually getting the components designed exactly the way we want them.”
The company will outsource components such as shafting, gears, bearings and clutches from vendors, and have them built to the company’s specifications.
Rainier Rigging, in its own shops, will be fabricating the mainframe, the tower and the winch frames that house the shaft and gears. It will also build the carrier, gantry frames, tower frames, track frame and roller carrier.
“We have to make our own track frame because we are putting a lot more weight on it than if it were used for a backhoe,” said Walch.
Tracks are driven hydraulically with a self-contained hydraulic motor and transmission mounted on the track frame. The pumps are then disengaged from the track components to operate the bucket.
Daily maintenance takes about 15 minutes, which includes common grease points—shivs, drums and rotating parts such as bearings. Monitoring large gearing for wear is also a part of daily maintenance.
Oil changes on components, engine transmission, final drives, etc. follow a typical service life of excavation equipment and take about a couple hours.
The dragline cable is the biggest wear point. “We treat cable like a consumable product like diesel oil,” said Walch.
Of the three cables on a skyline dragline, typically the skyline cable will last two to three years, and the inhaul and outhaul cables will last four to six months, according to Walch.
As for the skyline system, Walch said the machines are designed to have a 30-year cycle life, similar to big draglines.
“The main frame, the towers, the gantries and the draw-works, gearing and drums, will achieve about a 30-year life with proper maintenance,” said Walch. “Component changes—engines, converters, tracks, and oil pumps—go anywhere from 15,000 to 20,000 hours.”
According to Walch, the weakest point in the system is the ability of an operator to dig consistently over a day’s worth of repetitious operation.
“To make a machine totally efficient, we’ll have to eliminate the inefficiencies caused by operator boredom,” he said.
Rainier Rigging is developing a system to automate the operation of the equipment. A worker will need to be on hand only to correct problems signalled by the automation equipment.
Overall, clients of Rainier Rigging have commented on the technology’s ability to handle variance in a deposit, whether it is compacted sand or larger objects.
“Just the other day, we dragged up a petrified tree, about 150-ft. long (with a 15- cu. yd. unit). We estimated it weighed 70 tons. You never know what you are going to encounter in these deposits,” said Walch.
Perhaps the main reason for its digging strength is its design. Though the system uses a 50-ft. tower to span a cable as far as 1,000 ft. in some locations, the machine only uses 17,000 lbs. of counterbalance. This is because the unit uses a lot of its working forces to keep it down. Walch likens the process to trying to lift yourself up by your shoe strings. Less required counterbalance makes the system easier and less costly to move and transport. Also, the design nearly allows an unlimited digging depth. The machine has been considered for dredging work to 600 ft. in certain applications, said Walch. For aggregates, there is a point where the depth of the deposit will make cycle times too long to allow for profitable extraction.
“What this design does require is the fabrication of a tremendously strong main frame,” said Walch, “because we are trying to bend our own machine in the middle.”
Specific Issues of Short-Term Mine Planning
By Larry Bolling
Mine planning presents the opportunity to evaluate options to make moving dirt as painless as possible.
Let’s assume that, as an aggregate producer, you have recognized the need for mine planning at your facility. You have assembled your team to assist with the development and review of the mine plan, and you’re ready to jump in. Now is the time to consider the specific benefits you want to derive from the planning process.
In a nutshell, a mine plan directs you to the “best” place to mine at any given time. What makes that place the best depends on the criteria that you have deemed important for your operation. The following are specific issues that can be addressed in your mine plan:
Overburden removal and storage
Mine planning presents the opportunity to determine exactly how much overburden must be removed to support anticipated production, and to budget for that amount. It is a good idea to avoid dependence on production material that must be stripped in the same production year, because when things get tight or business takes a sudden upturn, the stripping operation tends to be the first to suffer. Since there is rarely enough room on any given site for overburden storage or disposal, the mine planning process could include evaluation of options to make moving dirt as painless as possible.
Reduce hauling costs or minimize/defer increases
Close examination of your ramp systems and haul routes is required to identify opportunities to develop more direct routes to the primary crusher, or limit distance increases. Optimum production areas with the shortest haul cycles can be used to offset longer haul times from areas mined concurrently that require development, yielding acceptable average cycle times. This approach can support production rates while providing much-needed quarry development.
Equipment upgrades/replacement
At some point it may become clear that the existing fleet will not be able to keep up with production requirements due to some combination of longer haul distances, greater quarry depth or
increases in production. Awareness of this impending need a few years in advance doesn’t make the new equipment any cheaper, but it does provide the lead time to analyze equipment options and prepare for the capital expenditures. If the
required upgrades include relocation or replacement of the primary crusher, at least a couple of years of lead time may be required to analyze potential locations and different crusher types.
Material blending
Rare is the quarry that doesn’t have to deal with some sort of dirty or lower quality material on a regular basis. Extraction can be scheduled to optimize the use of this less desirable material, maximizing available reserves while minimizing adverse impacts on production rates and product quality.
Short-term production changes
Reserving some particularly high quality stone or reserves in close proximity to the primary might offer some insurance for meeting short-term production increases or higher-quality requirements. Major local construction projects or scheduled plant downtime can put a strain on available running time, and maintaining some quantity of easily accessible or higher-quality material could support maximum plant feed capability for short periods.
Reclamation opportunities
Careful scheduling might present a chance to finish mining in certain areas of your site. Regulatory agencies sometimes require, but always like to see, reclamation concurrent with mining. Reduction of disturbed areas reduces the environmental maintenance burden and may reduce bonding requirements. Release and sale of reclaimed property, or in-house development of that property offers other sources of welcome revenue.
These factors pertain to all mining facilities, but sand and gravel mining operations offer additional challenges to the planning process. Mining reserve thicknesses measured in the tens of feet, as opposed to the hundreds of feet in many quarries, increases the importance of certain issues for sand and gravel producers. The following is a partial list of these issues:
Land planning
Permitting, stripping, extraction, reclamation and reuse proceed at an accelerated pace for sand and gravel producers. As extensive reserve properties close to major markets become scarcer, and development encroaches on the remaining reserve locations, permitting is becoming a greater challenge, and takes longer than it used to. On the flip side, greater opportunities for promoting post-mining uses of reclaimed properties can sometimes make this type of mining nominally more acceptable than rock quarrying. Projects that will reach fruition in a single generation, or even a few years, may be easier to visualize and accept by the surrounding community. As a result, land management has a high priority and great economic impact for sand and gravel operators.
Quality issues
Increasing scarcity of acceptable reserves close to major markets means that the definition of “acceptable” has become somewhat flexible. Mining several properties concurrently and processing at a central location may offer the only opportunity for some operators to maintain product quality. An accurate assessment of reserve quantity and quality is paramount. As materials with increasing percentages of fines are processed, wash-pond permitting, construction and maintenance become more significant. Wash ponds require valuable real estate and are tougher to rehabilitate for post-mining uses. As a result, fines removal and handling systems are getting increased attention. Plant design and pond requirements should be a significant component of the mine planning process for sand and gravel operations.
Plant location and material transport options
The location of the processing plant can be critical for sand and gravel producers, due to the relatively rapid turnover of mining properties. Evaluation of options for material transport depends on the size and location of the reserve bodies available for mining, and the characteristics of the surrounding community. Contiguous properties might make the use of overland conveyors or off-road haul vehicles the best choice. Crossing over or under heavily traveled routes is possible, but requires significant planning and higher capital expenditures. Analysis of the combinations of plant location, transport options and reserve locations should be included in a comprehensive mine plan.
Creation of a mine plan is the process of identifying criteria critical to a mining operation, analyzing available alternatives and developing a plan that answers the specific needs of that production facility. The items listed above include the major issues most producers must consider when developing a short-term mine plan. Facing these issues proactively allows evaluation of alternatives and preparation for the future, empowering aggregate producers to proceed forward on their chosen path.
Larry Bolling, P.G., is a geologist with the Industry & Environment Group of Morris & Ritchie Associates, Inc. He can be contacted at LBolling@mragta.com.
Taking the Guesswork Out of Brake Safety
Editor’s Note: This monthly column is supplied exclusively for AggMan by Association of Equipment Management Professionals (AEMP).
You may not realize it, but the process you depend on to protect your assets, minimize your greatest exposure to liability and control one of your highest maintenance costs is defective. Why? Because the process itself depends on guesswork.
By examining the process, you will see why it depends on guesswork and in how many ways you are exposed to costs and liability. Once you see it, you’ll appreciate the simple solution. It is what the North American Brake Safety Conference recommends as “the single most meaningful change that can be made to improve brake compliance.”
Daniel Judson, an inventor and technical director for Brake Sentry, Asheville, N.C., likes to begin by considering the facts.
“Brakes out-of-adjustment remains a serious safety defect and leads all out-of-service violations despite the emphasis on brake safety, increased enforcement efforts and the widespread use of automatic slack adjusters,” said Judson.
“Recent figures from an ‘Operation Airbrake’ inspection conducted throughout North America reveal that, of the vehicles inspected in the United States, 13.7 percent were placed out-of-service (OOS) for brakes out-of-adjustment,” he added. “That’s an out-of-service rate of nearly one in seven vehicles!”
To put that into perspective, the next closest OOS violation is for tire defects, and that is at the rate of only one in 30.
Since these inspections were conducted at random and in a variety of states, the data gathered provides a good “snapshot” of the general population of all air-braked vehicles. It means that if every vehicle in the United States were to be inspected today, we could expect that one out of every seven vehicles would be put out-of-service for having exceeded the 20 percent allowable safety threshold.
These numbers are important because, statistically, vehicles with major non-complying components are five times more likely to be involved in accidents than those in compliance, and the braking system is the most frequent contributor to accidents caused by mechanical defects. In fact, out-of-adjustment brakes are estimated to be a contributing factor in at least 30 percent of all truck crashes and truck-crash fatalities. Clearly, no other defect places drivers and the public at greater risk or exposes fleets to any higher liability than brakes out-of-adjustment.
And the effects are not limited to safety; the ongoing costs resulting from brakes out-of-adjustment are significant. As the leading cause of unbalanced braking, out-of-adjustment contributes substantially to one of the highest cost components of all trucks, tractors and trailers—brake cost-per-mile.
For physical evidence, you might take a look at the brake shoe “discard pile” to see if all brakes have worn evenly. You’ll find that some brakes are doing most of the work while others are just “along for the ride.” Consider a typical “brake job” on a vehicle with tandem axles. The first wheel brake that reaches its maximum wear limit now dictates that the others must be replaced as well, regardless of remaining life. In many cases, it would not be unusual to see brake shoes having close to 50 percent lining being discarded. This will give you an idea of how much money is being routinely thrown away.
This brings us to “The Process.” That is, the process that fleets depend on to protect their assets, minimize their exposure to liability and control their costs.
The process is built on a series of regularly scheduled preventive maintenance inspections that are separated by intervals of weeks or months. When a vehicle is returned to service after a preventive maintenance inspection, it will not have any repairs performed on it until its next scheduled preventive maintenance—that is, unless the driver reports a defect. Now, during those intervals, all safety and maintenance concerns depend on the driver and, more specifically, the driver’s ability to inspect, identify and report defects. Please notice that a driver performing a safety inspection can visually inspect every item except the most critical—brake stroke. So what does the driver depend on? Brake “feel.”
In short, safety and maintenance depend on drivers; drivers depend on “feel.”
Do you know that Commercial Driver’s License (CDL) inspection methods of testing brakes by feel have proven to be unreliable and that drivers are commonly unaware of brake defects that exist on their vehicles? Do you know that as brake performance degrades, there is little indication of the degradation?
Since brake stroke is physically limited and operates within a narrow range between safe/effective braking and unsafe/ineffective braking, the only dependable means to verify adjustment is by measuring the “applied stroke.”
Judson cites this example: “A typical ‘type 30’ air brake chamber has a limited, available stroke of 2-1/2 in. with an effective, or legal, stroke of 2 in. Of the 2 in., the first 1/2-in. is necessary for free travel. That leaves 1-1/2 in. to develop enough torque to accomplish effective braking. Here, the relationship of push-rod stroke to brake-shoe movement becomes critical, because it requires one inch of push-rod travel to move the brake shoes forty thousandths of an inch (0.040 in.). Now as brake linings wear down and the brake drum expands, the clearance between shoe lining and brake drum increases. This increased clearance directly affects the distance the brake chamber’s push rod must travel to actuate the brakes. And since the brake chamber’s push-rod stroke is physically limited, it is very possible that stroke will exceed the safe operating limits.”
Therefore, whether accomplished manually or automatically, unless adjustment is maintained within the effective stroke limits, it makes little difference how hard the driver presses on the brake pedal or how much air is delivered to the brake chambers. When you are out of stroke, you are out of brakes!
Adding to the problem is improper maintenance practices. This is largely due to the confusion that exists regarding automatic slack adjusters (ASAs). Although it is true that ASAs are not to be manually adjusted except at initial installation or when performing major brake work, it does not mean that brake adjustments can be neglected. On the contrary, brake stroke needs to be checked and verified regularly using the proper “applied stroke” procedure. The industry approved procedure requires physically referencing or marking brake-chamber push rods while brakes are in the released position, then applying the brakes at 90-psi system pressure and measuring the applied stroke to see if they are within the safe/effective range specified for each chamber type.
But does everyone take the time to follow this procedure? Methods vary widely and range from not checking at all (after all, they are automatic), to manually pulling or prying, or simply adjusting them as though they were manual slack adjusters (the most common). While it may be faster, this last method actually reduces the service life of ASAs, masks failed components and leaves defective brakes in service! So the guesswork continues.
When you consider the physical limitations of brake stroke, improper maintenance practices, long intervals between preventive maintenance inspections and a process that depends so heavily on guesswork, is it any wonder that brakes out-of-adjustment leads all violations and contributes to so much cost and liability?
In the final report of the North American Brake Safety Conference, Strategies to Improve Commercial Vehicle Brake Performance and Compliance, issued Jan. 15, 2001, it states: “It was unanimously agreed that brake-stroke indicators were the single item that would do the most to improve brake compliance.”
And, in its Recommendations to Carriers, it states; “Push-rod stroke indicators that are able to show the condition of brake adjustment to a person who is adjacent to the vehicle are perhaps the single most meaningful change that can be made to improve brake compliance.”
Improve the process with a low-tech solution and eliminate the guesswork.
Now let’s replay the process, except this time brake-chamber push rods are equipped with effective visual brake-stroke indicators. During intervals between preventive maintenance inspections, a driver can visually inspect and identify any out-of-adjustment conditions. There is no depending on feel, no guesswork and no assumptions. Visual brake stroke indicators eliminate the need for mechanics to physically mark and measure stroke at each wheel. They eliminate unnecessary and damaging manual adjustments to ASAs, identify hard-to-detect problems, reduce costly road calls, downtime, fines and out-of-service violations. In fact, use of visual brake-stroke indicators vastly improves maintenance efficiency (cuts each preventive maintenance inspection by about 15 minutes), improves brake safety and compliance and substantially reduces maintenance costs.
Can you afford to keep guessing at brake safety? Not when you consider the costs and liabilities…you’ve got too much riding on it.
The Association of Equipment Management Professionals (AEMP), formerly the Equipment Maintenance Council (EMC), is an individual membership organization comprised of equipment maintenance and management professionals. Its members are responsible for the purchase, maintenance, employee training, shop facilities and parts management of leading corporations and government entities that utilize heavy, off-road equipment. Its members also represent the major manufacturers and suppliers of the heavy equipment industry. AEMP provides end users with cutting-edge education, and it is the only organization to offer a certification program for the industry, the Certified Equipment Manager (CEM). For more information, contact Stan Orr, CAE, AEMO executive director, at (970) 384-0510, e-mail at ceo@equipment.org or visit AEMP's web sitee at www.equipment.org.
Cooling Systems Don’t Have to Cause Headaches
By Bob Drake
An important aspect of managing aggregate operations is the never-ending search for ways to decrease costs and increase production. From the pit to the plant, each process and each piece of machinery must be scrutinized to eliminate bottlenecks and optimize production. Quarry drilling and blasting operations, however, because they are the starting point for the entire production process and because they involve so many variables, may offer the most significant opportunities for improvements.
Optimizing drilling efficiency and accuracy depends on variables such as hole spotting, drill alignment, penetration rate, consumables wear rates and hole depth and straightness. Fragmentation—which affects loading and hauling efficiency, crushing costs, plant throughput and, to some extent, product mix—depends on factors such as blast design, drilling accuracy, explosives loading and detonation timing. Added to this mix of variables are safety, regulatory and community relations issues of flyrock, vibration, airblast and record keeping.
Fortunately, drilling and blasting technology can help crushed stone producers grapple with the seemingly infinite combinations of factors. Automated drills; efficient hammers; long-wearing bits; blast design and simulation software; expert advice; and turnkey drilling, blasting and monitoring services can lower overall production costs and ease quarry managers’ burdens, allowing them to focus more on plant operations. To this end, the following are summaries of some of the latest drilling and blasting products and services available to the North American quarry industry.
DRILL RIGS
1. Atlas Copco ROC D7 C
Computerized functions on Atlas Copco’s ROC D7 C surface crawler drill enable the machine to automatically drill holes unattended, such as during operator lunch breaks and between shifts, the company said. The operator sets the hole depth and automatic feed alignment and initiates drilling. Rods are added to the drill string automatically. ROC Manager software enables producers to design drill plans in the office and send them to the drill rig. The system monitors the drilling operation and logs deviations and other data, which can be analyzed in the office.
The ROC D7 C uses Atlas Copco’s COP 1800-series hydraulic top hammer to drill 2-1/2- to 4-1/2-in. holes. A Rig Control System senses variations in rock conditions and adjusts drilling functions to achieve smooth and accurate drilling while minimizing bit wear, according to the company. The system controls hammer impact pressure based on changes in rotation resistance. In addition, a two-stage anti-jamming system is automatically activated if excessive rotation resistance is sensed.
2. Furukawa DCR-23 and HCR-1500
Furukawa expanded its line of crawler-mounted drills for the quarry market with the addition of the DCR-23 downhole (DTH) machine and the HCR-1500 hydraulic top hammer drill. The Cummins-powered DCR-23 is designed to drill 5-1/2- to 6-1/2-in. holes to 140 ft. It features a ROPS/FOPS cab with sound suppression, heat and air conditioning; angle indicators for drilling accuracy; high-pressure air; automated rod changing; and quick set up without conventional jacks, the company said. Compressor capacity is 350 psi at 950 cfm.
The Cummins-powered HCR 1500 uses a HD715, dual-dampened hydraulic drifter to drill 3-1/2- to 5-1/2-in. holes. A drilling control system automatically adjusts the impact, feed, rotation and dampening pressures to match the rock conditions, the company said. The drill also features a new carousel-type rod changer (uses standard T-51 drill rods) and single-lever drilling controls. The HCR 1500 also has a ROPS/FOPS, sound-suppressed cab.
3. Ingersoll-Rand ECM-720
The ECM-720 is the first in Ingersoll-Rand’s (IR’s) new 700-series of crawler drills, which will be followed this summer with introduction of the DTH, CM-780D. The 10.6-ft.-high, 35.6-ft.-long and 8.3-ft.-wide ECM-720 is designed for transport without special permitting. It is powered by a Cat C-10, 365-hp diesel and can drill to 102 ft. deep. The machine uses a HC-200A drifter with IR’s T60 ThunderRod (see page 30). An energy-recovery valve matches blow energy to the hardness of the rock and Montabert’s Energy Recovery System stores rebound energy and converts it to overall striking force, according to the company. This provides greater penetration, straighter holes and less stress in the drill string, IR said.
Drilling automatics on the ECM-720—called Reliable Strata-Sense—hydraulically monitor and adjust drilling functions without use of microprocessors or electronics. Flow and pressure adjustments are progressive, instant and automatic, according to IR. Standard reverse percussion on the drifter and a blow air sensing circuit help prevent loss of drilling accessories.
4. Reedrill SD250
Reedrill (formerly Svedala Drilling), a division of Metso Minerals, recently introduced its SD250 hydraulic, top-hammer crawler drill. Using the company’s new HPR45 hydraulic rock drill, the SD250 can drill 2-1/2- to 3-1/2-in. holes. The HPR45 has fewer total parts than any rock drill on the market, according to Reedrill, which simplifies field maintenance and reduces downtime. The rock drill is mounted on a newly designed feed system with a cylinder/cable feeding arrangement. The SD250 is equipped with Reedrill’s SmartDrill system, featuring hydraulically operated, self-adjusting, feed force logic that the company said extends consumables life.
The SD250 is available in ROPS/FOPS cab and non-cab versions. It can be equipped with remote tram and boom controls with an extension cord for tramming in difficult terrain. Reedrill’s Duraquip dust-control system has a power-operated pick-up pot, a precleaner with a drop-out box and a dust collector. The collector is mounted on a swing post so it can be moved to provide access to the hydraulic valves. The collector fits within the profile of the drill, giving it an operating and transport width of less than 8 ft.
5. Sandvik Tamrock Titon 500
Sandvik Tamrock’s latest offering for drilling 4- to 6-in.-diameter blast holes is the Titon 500 DTH crawler drill. A Cat C10 diesel and screw-type compressor provide 776 cfm of air at 350 psi and two-speed tramming up to 2.5 mph. The 42,990-lb. machine also has a compact design for easier transport—37 ft. 6 in. long, 8 ft. 2 in. wide and 10 ft. 4 in. high. With the carousel rod changer and 16 ft. 4 in. pipe length, the Titon 500 can drill to 131 ft. with 3.5-in.-diameter pipe, 115 ft. with 4.0-in. pipe, and 98 ft. using 4.5-in. pipe. The machine’s boom telescopes for improved alignment accuracy, the company said, and it has angle and toe-hole capability. The FOPS/ROPS cab has joy stick controls.
Sandvik Tamrock also announced other product updates. Its Pantera 1500 now supports up to 6-in. diameter holes using the new 60-mm Sandvik Sixty rod. An addition to Tamrock’s Ranger series of hydraulic crawler drills, the Ranger 7002, offers optional 180° swing, providing up to 284 sq. ft. of surface drilling coverage without rig relocation.
6. TEI Rock Drills HEM 500
Enabling double duty for hydraulic excavators, TEI Rock Drills’ HEM 500 drilling attachment can drill a 4-in. hole up to 100 ft. deep. The unit uses a TE500 rotary percussion drill and hydraulic cylinder feed that can handle up to 20-ft.-long drill steel. Hydraulic hoses for the top hammer drill are routed over a hose reel and inside the feed rails for protection. The drill delivers impact frequency of 2,500 to 4,000 bpm; maximum rotation is 250 rpm. Options for the HEM 500 include hydraulic centralizers, electric/hydraulic controls, dust-collection hood and water mist system.
7. Tramac Excavator-Mounted Drills
Tramac offers three models of excavator-mounted drills for 28,600- to 77,000-lb carriers: CPA 225, CPA X-Tend 14/12 and CPA X-Tend 24/20. The attachments contain all necessary valving and controls and adapt to existing plumbing for excavator-mounted hydraulic breakers, according to the company. Hydraulic requirements range from a flow of 40 gpm at 2,300 psi for the CPA 225 to 53 gpm at 2,800 psi for the CPA X-Tend 24/20. An air compressor—capable of producing 185 to 300 cfm at 120 psi, depending on attachment model—must be provided for flushing drilled holes.
Tramac’s rock drill attachments use Montabert drifters featuring rebound energy recovery valves, optional reverse percussion and automatic Rock Reader Technology. This technology automatically adjusts feed pressure, rotation, percussion pressure and feed speed as rock hardness varies. A rod-changing carousel and rod length up to 24 ft. are available. The largest model can drill up to 4-1/2-in.-diameter holes.
HAMMERS, DRILL STRING and BITS
8. Atlas Copco Secoroc COP 64 Gold Hammer
Atlas Copco said its new generation, 6-in. Secoroc COP 64 Gold DTH hammer provides 30 to 50 percent longer service life compared to previous models. A steel disc spring and new grade of rubber buffer are designed to withstand operating pressure as great as 430 psi. The piston has a polygon shape that, combined with milled slots in the cylinder, improve its guidance, the company said. The cylinder is made of high-strength steel.
9. Boart Longyear Laserod
The rigid Laserod Straight Hole System from Boart Longyear uses 2-3/4-in. diameter drill steel for top-hammer drilling to 60 ft. The system, designed for 4-1/2- to 6-in.-diameter holes, utilizes more of the available power from the latest generation top-hammer drills while maintaining hole accuracy, the company said. A key to the system is the rod-coupling design—a tapered end with what Boart Longyear calls an Extended Life (EL) 68 thread. EL68 maintains tight connections during drilling and allows fluid uncoupling for quick rod changes, according to the company. Laserod is available in 12-, 20- and 24-ft. lengths. Button bits in 4-1/2-, 5- or 6-in.-diameters with flat or recessed faces also are available to fit the system.
10. Drillmaster International Hammers and Bits
Drillmaster International manufactures a line of hammer bits in sizes from 2-3/4 to 48 in. in diameter for any hammer shank. The bits are available in standard or custom bit-head designs in a number of face profiles: concave, drop center, convex, flat and double gauge. Carbide buttons are available in dome, ballistic, semi-ballistic or chisel shape in various sizes. The bits also can be equipped with back-reaming buttons for back drilling in caving rock.
Drillmaster also manufactures two lines of downhole hammers called Earthquake and Shockwave. Earthquake hammers are matched in size, construction and air cycle to the specific application, the company said. Shockwave hammers drill holes from 2-3/4 to 48 in. in diameter and can be adapted to all popular bit shanks.
11. Ingersoll-Rand ThunderRod 60
Ingersoll-Rand designed its new ThunderRod 60 drill string system—bit, rod and striking bar—to work with its new 700 series crawler drills (see page 28) and other high-power drifters. Striking bars and bits are available in three designs: hard rock, drop center retract and drop center retract ballistic. The ThunderRod 60 drill string features a large cross section to increase energy transfer and to provide greater stiffness, which reduces bending stresses and drills a more accurate straight hole, the company said. Thread stabilizers keep the male and female joints aligned, even when the threads are loosened, which reduces thread galling and chatter, according to IR.
12. Ingersoll-Rand Total Depth Hammer
The Total Depth DTH hammer from Ingersoll-Rand is available in two models: TD60 and TD65. To drill holes from 6 to 6-3/4 in. in diameter, Total Depth uses IR’s Quantum-Leap air-cycle system, which allows supply pressure to be applied to the piston for 80 percent of the impact stroke to provide more energy to the drill bit, the company said. New items include a snap-in cylinder and piston guide-seal system. The snap-in cylinder reduces the number of parts required to position the cylinder within the drill. The piston guide seal system uses a floating piston seal that minimizes the galling and frictional cracking usually caused by misalignment between the backhead and the casing, according to IR. A backhead saver-ring also helps prevent erosive wear of the backhead.
13. Numa Patriot 60
Numa’s Patriot 60 downhole hammer is designed to drill 6- to 8-1/2-in.-diameter holes. Drilling at high frequency—1,950 bpm at 350 psi—provides less vibration and smoother operation, the company said. At 350 psi the Patriot 60 consumes 945 cfm of air. The hammer’s simplified design uses fewer internal components.
14. Rockmore International Xtreme Bit
Designed for percussive surface drilling of hard and abrasive rock, Rockmore International’s Xtreme series of button bits use the company’s Functional Asymmetry (FA) carbide design on the perimeter or gauge row of buttons. Asymmetrically shaped buttons provide increased wear protection where contact and cutting forces are the greatest. Xtreme bits, available in 4- to 5-in. diameters, also feature a flat-face configuration and Rockmore’s Turbo radial grooves. The flat-face design provides improved chip flushing and bit-penetration rates, according to the company. Turbo radial grooves, placed at calculated angles in the direction of bit rotation, also enhance rock chip flushing.
INITIATION PRODUCTS and BLASTING SERVICES
15. Austin Powder Electronic Blast Report and Blast Assesment
All of Austin Powder Co.’s licensed blasters are now equipped with laptop computers to provide customers with Electronic Blast Reports (EBR). EBRs enhance report legibility, accuracy (all required fields must be filled out properly to complete the report), database management and electronic report storage and retrieval. In addition to ensuring quarry operators have complete documentation for each blast, the format allows cost and production analyses.
State-of-the-art instrumentation, methods and software provide the basis for Austin Powder’s pre-blast, blast and post-blast assessments, including Austin Blasting Software (computer-aided blast design and simulations), QED software (virtual mining methods), laser profiling of quarry faces and muckpiles, borehole deviation measurement, video and high-speed cameras, velocity of detonation measurement, seismographs and photographic fragmentation analysis.
16. Dyno Nobel DynoConsult
Dyno Nobel’s DynoConsult service uses explosives-application specialists working in partnership with select customers to refine quarry blasting programs. DynoConsult promotes that optimized fragmentation provides measurable benefits in downstream processes, from the pit to the plant, which reduces overall cost and improves productivity. DynoConsult said it uses a project-based, hands-on, measure-and-manage approach. The company also assists quarry staffs with blasting safety and basic explosives-application training; cost and productivity improvements; explosives selection; blast design, diagnostics and evaluation; flyrock, airblast and vibration reduction; community relations support; greenfield permitting assistance; and expert testimony.
17. Ensign-Bickford Trojan 600 and 800 Cast Boosters
The Ensign-Bickford Co. introduced two cast boosters with a modified design intended for use with bulk explosives. Trojan 600 and Trojan 800 boosters are longer than conventional boosters, measuring 9.5 in. x 1.85 in. and 9.5 in. x 2.1 in., respectively. The added length increases the probability of intimate contact with the bulk explosive and the smaller diameter makes the boosters less likely to cause bridging of the explosive, the company said. In addition, a central detonation point creates fully developed shock fronts at both ends of the booster. The new boosters are designed for use with detonators only in difficult blasting environments, such as wet boreholes, deep boreholes and long sleep times. The boosters will not accept initiation from detonation cords.
18. GeoSonics Blast Data Management Service
Using its environmentally sealed seismographs in secure enclosures with remote communication—satellite, cellular or land line—GeoSonics provides third-party monitoring with its Blast Data Management Service. The service ensures proper seismograph placement, installation and operation; complete and accurate data; immediate access to blast results by fax and email; and 24-hour-a-day, 7-day-a-week coverage, the company said. GeoSonics prepares detailed monthly reports containing blast and trend analyses and offers access to a team of vibration consultants. The Blast Data Management Service also eliminates costs associated with seismograph setup, operation, retrieval, data collection, calibration and maintenance.
19. Thunderbird Mining Systems DEI Plus
Thunderbird Mining System’s updated drilling efficiency indicator, DEI Plus, monitors and records data from rotary blasthole drills. A 4.5-in. x 3.4-in., sunlight-readable video display shows depth, rate of penetration (ROP), target depth, drill time and estimated time to complete the hole. A bar graph shows the target and drilled depth. A second screen displays ROP vs. depth. The drill operator has access to data for holes previously drilled and the system maintains current- and previous-shift statistics, such as total number of holes, total depth, total drill time, average depth, average ROP and average hole drill time.
Bob Drake is editor-at-large for AggMan.