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Operations Working 24/7 November/December 2004 Running a Successful 24/7 Operation Keeping an aggregates operation running 24 hours a day has its own unique challenges. by Kerry L. Clines, Associate Editor |
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A visit to the TXI Mill Creek Stone Plant near Ardmore, Oklahoma will find the plant up and running, no matter what time of day — or night — it might be. The plant opened two years ago, under the watchful eyes of Harold “Papa” Watson, plant manager. Not only does he manage the plant now, he had a great deal to do with the construction of the plant. “There’s not a whole lot I haven’t seen after 43 years [in the business],” says Watson. “I’m really not your typical plant manager. They wanted somebody up here who’d done this. I came up here and watched them build it, and every time I didn’t like what the engineers did, I’d stop them and we’d talk about it.” Watson says the plant is “one of the most automated plants for rock.” Once the rock leaves the pit and is dumped into the first rock crusher at the primary plant, the automation begins. From the first crusher, the rock travels on a conveyor to a smaller crusher. Then, it travels on another conveyor to the first screen, where anything too large is sent back to the smaller crusher to be crushed again. Anything that passes through the screen travels on a different conveyor to a large pile of rock waiting for transport to the secondary plant. From a tunnel underneath this pile, a hopper loads the rock onto another long conveyor that carries it up to the secondary plant. Here, the rock is screened, recycled for additional crushing if necessary, washed, sorted into appropriate sizes, and, finally, loaded into railcars. All plant activity is monitored and controlled from a central control room filled with computers, cameras, and communication equipment. A handful of plant personnel monitor the whole operation from there and stay in contact with everyone else in the plant. When one of the two daily trains comes in, a railroad engineer monitors the loading of the railcars from the control room, telling the train conductor when to move forward, and how far. “The system will load a railcar every two to three minutes,” says Jared Elkins, production coordinator at the plant. “We can get this train out in, roughly, two and a half hours if everything goes right.” The plant produces 1,800 to 2,000 tons per hour — 5 million tons of finished product annually. |
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Maintenance/repair Watson tries to schedule all of his equipment maintenance — conveyors, screens, and so on — during the day so that when the night shift comes in, all they have to do is run the operation. “It’s a 24/7 operation,” says Watson, “but actual running time isn’t quite 24 hours. It takes about 20 to 21 hours a day to meet our production demands. Technically, I’ve got four hours of play, but if I need to tear something down that takes eight or 10 hours to fix, it uses up several days right quick.” If something goes down at night, they determine how serious it is and decide whether to call in the maintenance team or wait until daylight to do the work. Some repairs require the use of a crane, and they won’t use that at night due to safety concerns. Parts availability in the middle of the night is a major problem. “At 2 o’clock in the morning in Mill Creek, Oklahoma, it’s a little hard to find parts,” says Watson. “You either go into Dallas or Oklahoma City — and most of the time the part isn’t in Oklahoma City. It takes you two and a half hours to get [to Dallas] and two and a half hours to get back, and while you’re waiting for the part, another hour. “You have to think a different way when you run a 24-hour operation. You have to think, what do I really need to have here so that, if I do break down, I’ve got the part here and can get back to work. You can’t afford to be down in the middle of the night. You have to really think and be a little more on top of things. “I do a little more consignment work with people. I have a bearing company that has certain size bearings on consignment here. I don’t pay for it until I use it. They come by and count each week and if I’ve used a bearing, they replace it with another bearing and I pay for it then.” Most of the maintenance on vehicles is done at night, however. With fewer people working at night, fewer vehicles are being used. This allows them to rotate the vehicles through the shop for regularly scheduled maintenance. Safety Safety is the most important issue in running a 24-hour operation. You have your standard rules that apply day or night, but nights have some special considerations. “There are some things that have an added risk at night,” says Night Production Supervisor Kelly Grizzaffi, “therefore, we don’t do them at night. Like stripping, work on berms, or working anywhere there’s any kind of high wall — it’s our policy not to do it at night.” As far as stripping, “I don’t want them up there at night,” says Watson. “I can run it where it’s safe, but I still don’t like them up there. I’ve been in this business a long time. I don’t want to get anyone hurt now.” Blasting is also something they won’t do at night. There’s no way to be 100% sure that the area is clear before detonation. “A lot of it is just handled through looking at the overall situation or problem and making a determination about what’s the safest way to do something,” says Grizzaffi. In addition to the Mine Safety and Health Administration, the Oklahoma Mining Commission has its own regulations that require that one man on each shift have a green safety card — he’s been to school and is responsible for safety. The card holders rotate shifts and weekends so there’s always one on duty. Lighting “We didn’t spare any expense on the lighting of the plant,” says Watson. According to MSHA, an operation must have adequate lighting to run at night. ”Lighting could be an issue,” says Grizzaffi, “therefore, we put lights all through the plant. We also have portable light plants for darker areas.” One of the problems with the lighting at night is the issue of dust control. Any amount of dust in the air at night will reflect the lighting, making visibility a problem. So, they keep the watering truck working overtime during the night shift. Both the primary and secondary plants are extremely well lit at night, as is the pit where the wheel loaders load the dump trucks. Watson says they will be adding more lighting along the roads leading from the pit to the rock crusher at the primary plant. Scheduling One of the greatest challenges facing a 24-hour operation is scheduling — finding the people that are content to work nights. The plant pays a shift differential to encourage night work. ”The trap you can get into with a 24-hour operation is that everybody wants to work days,” says Watson. “If you’re not real careful, you’ll wake up and have all your experienced people on days and your night guys will be all inexperienced people. You have to really watch that.” There are some workers, however, who prefer the night shift. One of the pit loaders, a young man right out of high school, had trouble getting up early in the morning and was often late to work, so he was offered a night position. He’s been one of the best, most reliable workers since then. There are also those, like Grizzaffi, who enjoy the cooler temperatures at night, especially during the summer months. “But, still, most people that come to work at night are looking to go to days as soon as they can,” says Watson. “Me and my boss made a vow that we were going to run this different than most rock crushers were run. Most rock crushers schedule between 40 and 80 hours a week, but we schedule 48 hours. We vowed that we were going to put enough people in place that we could run it with quality time off.” The plant has 81 employees. People are scheduled 24-hours a day, with two regular shifts and a rotating shift in between. They have a maximum of 34 people on night shift and 47 during the day, counting office employees. ”At night, we have the same issues as far as production,” says Grizzaffi. “We’re still crushing rock and still producing the finished product and loading trains. “We try to keep it where the day shift can actually push up the production a little bit, but we try not to push it too much at night — we try to run steady.” |
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Reprinted from Aggregates Manager Magazine |
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