May 1, 2009
To ensure a good, timely supply of quality sand, this glass factory branched out into the aggregates business.
by Kerry Clines, Senior Editor
In southern Oklahoma, just a bit off the beaten path, is a brand new sand plant owned by the largest glass producer in North America and, probably, the second largest in the world. However, the glass company has never been in the aggregates industry before – at least not until last year. The sand plant, FG Minerals LLC, is a division of Cardinal Glass Industries and is the glass company’s first venture into the aggregates business. But if all goes well, it may not be the last.
The idea for the sand plant started back in 2004 when Cardinal Glass Industries built a float glass factory in Durant, Okla., says John Van Der Wal, sand plant manager. When the glass factory, Cardinal FG Co., first opened, it bought its sand in Arkansas and shipped it in by rail, which was expensive and, at times, unpredictable. The sand didn’t always make it to the plant. Sometimes, it ended up in another state or the train derailed on the way, which caused supply problems at the glass factory.
McCabe Industrial Minerals, Inc., a consulting company located in Tulsa, Okla., approached Cardinal with information about a piece of land about 14 miles north of Durant. It was available, and the consulting company suggested that the glass company could open up its own source for sand on that site, rather than purchase it from a sand plant in Arkansas.
Testing was done on the property to make sure the sand met the quality and composition criteria necessary for making glass. Permitting soon followed. “It was an old cow pasture,” Van Der Wal says. “We dug a hole with an excavator, made a pond, and put a dredge in.” But that was the easy part. A processing plant also needed to be built.
Numerous manufacturers and service providers helped build the wet and dry plants. “Krebs provided the dredge pump, slurry pumps, and all the cyclones and whirlsizers for the wet plant,” Van Der Wal says. “Everything else (for the wet plant) was provided by GreyStone.”
In terms of the dry plant, B.W. Sinclair provided bucket elevators and conveyors, while silo tanks were built by Tank Connection. Carrier built the fluid bed dryer, and Rotex provided the screens.
Structural fabrication and general construction of the plant was spearheaded by Texoma Millwright and Welding. When it came time for electrical controls, Van Der Wal turned to Millenium – the same company Cardinal used for the glass factory. In-house expertise, in the form of Cardinal Electrical Engineer Ted Cole, handled the installation of controls for the entire plant.
The wet plant began producing sand in July 2008 and the dry plant went online in September. “From August 2007 to now, we’ve changed that property from a cow pasture to a sand mine with a dredge operation, a wet plant, and a dry plant for drying the sand,” Van Der Wal says.
There are two ponds – one is for the dredge and the other supplies clean water to wash the material in the wet plant. From the dredge pond, sand and water is pumped up to the wet plant through a pipeline. It is then processed through a couple of cyclones and scrubbers. A dewatering screen helps to remove some of the water. Then, the sand is placed in a stockpile where it continues to drain for a couple of days. From there, it is loaded into hoppers that feed the sand onto a conveyor that, in turn, feeds it into the dryer, which is fueled by an 18,000-gallon propane tank.
Once the sand has gone through the dryer, it travels through a screen where the coarse sand particles are removed and placed in a separate pile. The remaining sand then proceeds to one of the plant’s two large silos for storage until it can be shipped to the glass plant.
When a truck arrives to pick up a load of sand, it proceeds to the scale house where it is weighed empty. The truck then drives beneath the silo’s loadout hopper to get its load of sand. An 11-foot downspout drops down from the loadout hopper to keep the sand from blowing around during the loading process. The truck moves forward slowly as it is being filled, which helps distribute the load and the weight evenly over the truck’s axles. A scale ensures that 27 tons of sand is loaded onto each truck. Then the truck returns to the scale house for its final weigh out and to receive a ticket. Each truck cycle takes about 20 minutes.
All new plants encounter challenges when they open, and FG Minerals is no exception. “One of the problems we’ve got here is that the sand is so hard you can’t dig it with the dredge,” Van Der Wal says. “Silica sand is so close together, and the sand has been in the ground for so many years, that it has cemented itself together. It’s hard, just like concrete. That’s why I’ve got an excavator to dig it out. The excavator gets out in front of the dredge, reaches out in the water, breaks the sand loose, and throws it back in the water so the dredge can pick it up.”
Finding experienced workers in the area has been a challenge, also. “The only guy I’ve got here who’s had any experience is the guy on the dredge,” Van Der Wal says. “The others have never done anything like this before, and they don’t understand it,” he adds. “I’m trying to teach them.”
Another challenge is maintaining the quality of the sand, which has to be impeccable. Constant testing is done to ensure the utmost quality. “The white sand is the better sand,” Van Der Wal says. The darker the sand is in color, the more iron there is imbedded in the sand particles.
“It’s critical that the sand meet composition and chemical specs that are set down by the glass industry,” Van Der Wal adds. “We have an X-ray machine so we can check the chemicals in the sand. If something gets off in the sand, it can cause imperfections in the glass. Then you have a lot of glass to break up, cull, and run back through at the factory. It’s very costly.”
Testing is performed by Dave Scorgie, the plant’s quality control technician. “We take a sample of sand from different places in the process,” Scorgie says. “We take 10 grams of sand, grind it up, and put it under 30 tons of pressure to make it into a pellet. We call it a cookie. Then we put it in the X-ray fluorescence instrument. It’s calibrated for us to use for our sand; it tells us the chemistry we’re looking for.”
The sand then goes through a machine resembling a microwave oven. The machine has a tomb that generates increased air pressure. It takes about 15 minutes to perform its test. “If you’ve got one little particle of sand that’s got some iron stuck on it, the test will come out bad,” Van Der Wal says. “That’s all it takes, one little particle. It drives you nuts just trying to keep up with it.”
The sand plant currently has 12 employees and runs only one shift, but once the production of sand for the glass factory is running smoothly, the company plans to start producing fractionated sand and foundry sand. “We’ll probably run two shifts here when we start doing frac sand, because we won’t be able to keep up with it,” Van Der Wal says. “Right now, Cardinal is just using 140,000 tons a year. Working five days a week, 10 hours a day, we can make, probably, 240,000 tons. But to make it pay good, we need to get up around 300,000 to 400,000. The only way you can do that is to run two shifts.”
In the meantime, the company will continue to do what it was set up to do – produce fine, white, silica sand for the Cardinal glass factory in Durant. “The other stuff that we would do, like the foundry sand and frac sand, is just an extra deal to help pay for the cost of the plant,” Van Der Wal says.