Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/370990
13 AGGREGATES MANAGER September 2014 When the plant was first purchased by Unimin, a majority of the sand went to foundries for use in making steel cast- ings, with the rest used for making glass. After a few years, the American foundry industry slipped and glass became king, so — for many years — a majority of the sand produced at the plant was used for glassmaking. "We still have a few industrial accounts (glass and foundry), but our primary business is the energy market," Malo- ney says, explaining that the plant lost a couple of big glass accounts about the same time the local well service industry was picking up in Arkansas. "We proved to ourselves that we could make hydraulic fracturing (frac) sand, so it was a natural thing to shift to that side of the business to replace the volume we lost. Now, we ship more sand to the energy sector than anywhere else." Daily operations Unimin's Guion Plant currently has more than 100 employees combined — staff, miners, operators, and maintenance. The plant runs 24/7, while the mine operates 12 hours a day. All miners, operators, maintenance, and some staff work the same 12-hour shift schedule with rotating days off. The sandstone deposit varies, but gener- ally averages a thickness of 150 feet and rests beneath a layer of limestone in most places, so underground mining just makes sense. The majority of the sandstone production comes from the underground mine, with the rest coming from the surface quarry. Though Unimin has tried to devel- op a market for the limestone, it hasn't had much success to date, probably due to the fact that there isn't a very large local market for the rock. The local demand is already filled by existing operators. "The underground is not a shaft mine," Maloney explains. "It's called an adit mine, and there are multiple openings into the side of the hill. It was originally mined from the surface until the face was high enough to take it underground. Once you go underground, you're pretty well committed to it. We mine everything in a staggered pillar pattern, so we end up with a checkerboard effect. There are ap- proximately 25 working faces at any given time, which enable us to keep drilling and blasting separate from mucking and scal- ing, and we continuously cycle from one face to another." All the equipment used in the under- ground mine drives in and out every day. These vehicles provide the only lighting underground, as there is no additional lighting of any kind. The equipment is all self-contained and is the type commonly found in most quarries, except for the large jumbo drill that was custom-built for the mine. At the time it was manufactured, it was one of the largest two-boom jumbo drills in North America. The drilling crew starts the mining cycle by drilling a blast hole pattern in a face, then they move on to the next face. The blasting crew then comes next to blow out the holes and load them with explosives. Once the blasting crew has triggered the explosives in a controlled manner, the area is ready for the scaling crew. They scan the area for loose rock and carefully scale (mechanically remove loose rock) the faces in order to ensure the area is safe for the mucking crew. The mucking crew then enters with wheel loaders and haul trucks to move the material to the pro- cessing plant. Once the area is cleared, it is ready for drilling again. This cycle repeats throughout the mine. In the plant, the ma- terial is run through a wet process, dried, and separated into the various product size grades. Once the sand is processed and sepa- rated into the various product bins, the sand is sent via conveyor belt to one of two loadout facilities. From these facili- ties, the Guion Plant has the capability to load either over the road trucks for local customers, which can be a mixture of industrial and energy customers, or bulk railcars for more regional business, which is primarily how the hydraulic fracturing sand is shipped. PLANT PROFILE