In 2011, the Dexter Sand and Gravel operation was a 100-acre cornfield in Southeastern Missouri. Today, the site is a flourishing operation, producing concrete and masonry sand.
Dexter Sand and Gravel is part of Delta Companies, a subsidiary of Colas USA. Delta owned another sand and gravel operation near the current Dexter, Mo., site that was running out of reserves. So in 2009, Area Manager Mike Martin and Delta Engineering Manager Scott Jinks started looking for a new site close to the old operation. They found it in Dexter, just two miles south of the old site.
The company broke ground at the Dexter site in February 2012. By April, crews were pouring concrete for the foundations, and construction was underway in May. The site was producing sand by the end of July.
Challenge
“This site is a great sand deposit with a small amount of gravel that is easily separated,” Martin said. “The challenge with this deposit is it contains trace amounts of lignite.”
Martin said that lignite, a form of coal, causes problems with concrete sand because it is lighter than the sand and essentially pops out as the concrete sets, causing voids in the finished concrete.
Martin and Jinks were concerned with the quality issues caused by lignite and looked at viable options from several aggregate processing equipment manufacturers. Ultimately, they decided to work with McLanahan Corporation, which was represented in Missouri by Mike McCarron, Sales Manager for Continental Equipment.
The team came together to design the plant and make sure the equipment could separate the lignite and make the desired products.
“Delta had a modest budget for a plant of this size,” said McCarron. “But McLanahan does a really good job working with customers and setting the plants up individually. That was definitely the case here.”
Solution
The team settled on a McLanahan Lites-Out™ System, also known as a Flat Bottom Classifier, to remove the lignite. The system uses a pulse-type discharge to induce a jigging action that helps dilate the bed and frees the coarser organics like lignite through the fluidized bed.
“This unique gravity-based process doesn’t need any chemicals – or something like Magnetite – to help the separation,” said McCarron. “In fact, this same technology can be used for soil remediation or to separate construction debris.”
The flat-bottomed nature of the classifier allows the feed height of the plant to be lower to the ground, taking up less room.
“The Lites-Out™ Flat Bottom Classifier has a small footprint on the location because it is flat-bottomed along with lower head height, which decreased our pumping horsepower needed,” said Martin. “The machine features a diverter box that allows Dexter to make concrete and masonry sand at the same time, saving time, energy and money.”
The Lites-Out™ System effectively removes +50 mesh lignite from a -4 mesh feed to achieve the published specifications for lignite-free sand. In addition, McLanahan installed a warning system to ensure lignite did not enter into the concrete sand if the system was ever out-of-balance.
“McLanahan Corporation, from the start, was the leader in our decision making,” said Martin. “They had the total package, with a system that would work well from the get-go.”
Results
“The system helps us gradation-wise with the concrete sand, but also removes any trace amounts of lignite. This makes a high-quality concrete sand which is saleable for Missouri Department of Transportation projects and general construction projects,” said Martin.
Today, the site is producing more than 200 TPH.
McCarron said he appreciates that McLanahan provide everything in-house, rather than needing parts from up to three or four other companies, creating a “hodge-podge” system. He loves that McLanahan makes top-quality products and then stands behind everything they sell.
In addition, Jinks mentioned that McLanahan and Continental were exceptional at working under the gun from the beginning. “We started the job 13 weeks behind schedule,” said Jinks. “The cooperation among McLanahan, Continental and Delta Companies helped us get the plant up and running with only a six-week delay.”
“The success of this plant – from greenfield to construction – was due to the success of coming together as a team – not only within Delta Companies, but also our partners Continental Equipment and McLanahan,” said Martin. “We worked together to overcome any issues and get the job done.”
