Aggregates Manager

September 2014

Aggregates Manager Digital Magazine

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OPERATIONS ILLUSTRATED AGGREGATES MANAGER Voices of Experience Bill Granville Craig Collins Joseph Flick ▼ ▼ ▼ A ccording to Bill Granville, owner of J.W. Granville Consulting and acting vice president of operations at Garre Limestone, Garre, Pa., geology is extremely important, and knowing how to read conditions takes experience. "Geology is so important, if I could only hire one person for an underground stone mine, I would hire a geologist over a mining engineer," he says. In general, it is difficult to find experienced underground hard rock miners. e state of Pennsylvania requires that each underground mine have a licensed underground foreman for each shi. e foreman must conduct a pre-shi inspection prior to the start of all shis in the mine. "e goal every day in an underground mine is to make sure every miner goes home safe," Granville says. He explains that a large portion of controlling roof conditions includes scaling. Mechanical scaling machines use a boom with a hooked end that scrapes the roof and walls to remove loose material. Prior to the develop- ment of the scaling machine, miners would use scaling bars and scale the surfaces by hand. "I still encourage hand scaling to go along with mechanical scaling," Granville says. "e mechanical scaler brings down the large material. Hand scaling brings down the smaller material. And when the miner is up near the roof in a scaling basket, he can look for hazards and listen for sounds that are out of place. A hand scaler can also mark with paint where the roof bolts should go in a mine that requires bolting." Garre Limestone had previously been an open-pit quarry. Five years ago, the company hired Granville to take the operation underground. "e mine is now in full operation. Going underground is not for the weak of heart," he says. "Companies can spend millions to go under- ground and still be unsuccessful." N ew technology that electronically controls drilling and bolting has resulted in systems that make roof mapping more user friendly. According to Craig Collins, electrical engineering manager for J.H. Fletcher and Co. of Huntington, W.Va., the primary purpose of the system is to efficiently drill and consistently bolt, but a secondary benefit is that the system graphically maps for the operator the locations of voids, bedding planes, and contrasting rock hardness in real time. "A proactive approach to roof control is always best," Collins says. "And faster access to information is a key." Collins explains that each mine has unique characteristics that dictate the method of advance and the way the roof is to be bolted. "If the miner can recognize how the roof characteristics are changing in real time, then they can make the proper adjustments to the method of ad- vance and to the roof control." When roof control adjustments are made during the initial production cycle, it provides a safer roof and will minimize the labor and material costs associated with "repair bolting," he says. e best roof control actually starts with proper drilling and blasting at the face, notes Collins. "It makes for a beer roof. It cuts down on scaling, improves bolting. I've heard from many managers that if the operators drill the face right, the roof control straightens right up," he says. "T here are certain safety commandments that go with underground mining," says Joseph Flick, director of the Miner Train- ing Program at Penn State University. "One of them is that under no condition — never, never — must a miner go beyond a scaled roof. Scaling is a continual, never-ending roof maintenance process. e scaler will scale one section of roof, then go back and follow up with maintenance scaling. If there is ever any real or suspected loose rock, it must be taken down." An underground mine has so many sights and sounds that a miner must understand. And while classroom and task training are extremely important, it is on-the-job training under an experienced miner that really helps underground mine workers to learn what they should see and listen for. "A miner must be looking around all the time," Flick explains. "Sometimes loose rock is hard to see. ey have to train their eyes to see large, as well as small, potential hazards." Any time a miner notices something that might be a hazard, he must protect himself and others. "If you see something that doesn't look right, stop. Back up and call for a supervisor to evaluate the situation," Flick says. Ledges, which are evidenced by a broken or mined off section in an otherwise smooth roof, are also important to note. Miners must be mindful of them because they indicate a section where the roof could possibly fail and need additional support. And, Flick says, ledges can be tricky to spot. "From one direction or angle, you can see ledges fairly easily. It's obvious that a section is lower than the rest of the roof. From another direction, a ledge can be difficult to see because it might be 60 feet up, and because it is dark, it appears to blend into the roof."

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