There is virtually no sand for construction left in coastal Rhode Island and Connecticut. But there is a very big demand for the product. One company, Cherenzia Excavation, is manufacturing #4 minus spec sand at 130 tons per hour from 3/8", 3/4", 1/2" and 1 1/2" granite to fill the need, using a Terex Pegson 1000SR Maxtrak cone equipped with an Autosand head and an integral screenbox.
"The law of supply and demand has never been more evident than it is here in Rhode Island and Connecticut for construction sand," says Vice President and Project Manager Joseph E. Cherenzia, P.E. Our problem has been how to supply spec sand for our own construction use and to sell on the market. We supply three concrete plants and three asphalt plants. We also produce a variety of other stone products for construction and road building with the 1000SR and a 26x44 Terex Pegson XR400 jaw plant.
"With a burgeoning demand and virtually no supply, #4 minus sand had become an extremely valuable commodity for anyone who can supply it," Cherenzia said. "That's what we were wrestling with in late 2007. We've been utilizing fines from blasting and crushing to supply part of our construction sand for the past 20 years. But it's a drop in the bucket compared to the total need. So we went looking for help."
Cherenzia investigated various manufacturers' equipment in their efforts to solve the problem. They wanted to use a cone crusher rather than other equipment because of the wear factor with hard granite. Of all the cone crusher manufacturers and dealers Cherenzia contacted, only the Terex Pegson and Powerscreen dealer, Powerscreen Connecticut, says it could be done. The others scoffed at the idea.
"We were skeptical, too" says Brian Brennan, vice president of operations for Cherenzia Excavation. "But Geoff Morrow of Powerscreen Connecticut came in here and told us that we could get at least 100 tons per hour of #4 minus sand with their Terex Pegson 1000SR cone with Autosand. We gave it a try and were amazed to find that not only can we produce sand products at very consistent specs with the 1000SR, but we can do it at a whopping 130 tons per hour."
"Of all the features and benefits that the Terex Pegson1000SR cone has to offer us," Joe Cherenzia emphasizes, "the most important factor is that it enables us to take a slow-selling, low-profit inventory product-this year it's 3/8"-next year it could be something else-and make it into high-profit sand that sells like crazy. Nobody else around here is doing this. We have the permitted quarry, plus the people and expertise to do it."
"We also use the 1000SR with Automax to make 1 1/2" to 1" material for road base and structural backfill," Brennan added. "We can switch from Autosand to Automax in 2½ hours. We use the Autosand about 85% of the time. We've found the 1000SR to be very dependable and durable with minimum maintenance. And Powerscreen Connecticut gives us great service back-up when we need it.
"We only changed the manganese twice in the first 60,000 tons of sand production, and that's pretty much been the average ever since. We run 20 mil to 10 mil on the closed side of the cone. Changing the manganese is simple and easy and takes only about six hours. We've been using the Terex Pegson 1000SR cone and XR400 jaw since October-November 2007. Both are portable track-mounted machines; so we can use them to follow the quarry face, as well as use them at both of our Cherenzia quarries and at other sites."
In addition to a shortage of sand, there are virtually no level construction sites left in Rhode Island and Connecticut. Contractors are having to build on hilly, rocky terrain they call "ledge." Typically the contractor has to blast the rock-mostly granite-then grade the land for residential and commercial construction projects. This leaves a lot of shot rock to dispose of or put to use in some way.
The best way to handle this situation is to crush the shot rock on site and use it as base materials, usually also on site. Hauling it away to be dumped or crushed would be an added expense, and there are few if any dump sites available.
Crushing on site provides opportunities for Cherenzia to use the portable Terex Pegson 1000SR Maxtrak and Terex Pegson XR400 jaw plant either individually or together in three ways: 1) crushing at their own excavation, demolition and construction jobs; 2) contract crushing for others; and 3) as rental machines to various contractors.
The Terex Pegson XR400 is used largely to crush overburden as base fill. It also enables the recycling of concrete rubble and construction/demolition debris, since the machine design includes hydraulic overload protection. The jaw has a hydraulic release feature that opens up if anything too hard-such as oversize tramp iron-gets in it. The jaw opens up, drops the hard material onto the discharge belt, then closes up again and goes on crushing. This eliminates shutting down the crusher to get the jaw unlocked and the iron out, which can take a lot of time."
The Terex Pegson 1000SR and Terex Pegson XR400 combination gives Cherenzia Excavation accurate spec materials and a lot of flexibility. Joe Cherenzia pointed out that the company is currently bidding jobs that involve recycling, demolition and crushing on site. Cherenzia uses the 26x44 jaw plant to make 1 1/2", 3" and fines. They use both the jaw and the cone to make sand and 1 1/4", 3/4",1/2" and 3/8" stone."
The Terex Pegson 1000SR has a 5' x 11' two-deck product sizing screen, input conveyor/hopper, product conveyors and oversize return conveyor on a single chassis. The 1000SR can simultaneously produce two products plus oversize re-circulation, or three products using an optional third stockpiling conveyor. The plant is engineered for high specification, flexibility, and up to 240 tph, depending on the application, with ideal mobility and low operating costs. Normally no pre-screening is required. The hydraulic system can be adjusted quickly, even while crushing. The entire feeder-hopper assembly can be hydraulically lowered into the feed ring for transport or raised for re-metaling.