THE LONG-DISTANCE RUNNER…

Dowling Quarries in County Laois, Ireland was the first in the world to install and operate AggreSandlaunched by Terex Washing Systems just over 10 years ago. Today, this modular aggregates and sand washing plant is still running as reliable as ever, as Awesome Earthmovers discovered when we met up with company director Humphrey Dowling.

The main objective in developing the AggreSand plant was to meet customers’ needs for a modular system that could efficiently wash and produce multiple aggregates and sands within one machine. So, has it lived up to expectations?

“Absolutely,” says Humphrey without hesitation. “This plant replaced an older Terex mobile screen wash plant that was installed 13 years previously. It had a 10x5 screen box and a dewater feature all on one chassis. That did a lot of work and it clearly proved itself, so we had no concerns when we invested in AggreSand. We certainly haven’t been disappointed.”

The modular wash plant brings together aggregate and sand washing on one modular chassis, processing glacier sand and gravel material formed during the ice age. The throughput being achieved on the plant has been excellent, adds Humphrey, and the quality of the aggregates and sands being produced has been very impressive.

The plant was originally sold with a high-performance two-deck vibrating grid to allow Dowling Quarries to feed material directly from the face of the quarry. Large material is scalped off while the minus 50mm material goes straight into the wash plant.

“Throughput being achieved on the plant has been excellent and the quality of the aggregates and sands being produced has been very impressive...”

The AggreSand plant was fitted with a 12ft double-deck vibrating grid with 100mm bofor bars and 50mm woven wire mesh. This particular plant separates 0-50mm to the wash plant that gives three aggregate materials and two sands. Reject material from the live head is stockpiled and later crushed when accumulated into 50,000-tonne stockpiles and then crushed into 6f2 material by a Terex crusher.

“After running the plant for a number of years we made the decision to remove the live head as we knew the plant had more capacity. By adding in a Powerscreen 1400 Chieftain, we increased our throughput and gained an additional product, 50-80mm stone,” says Humphrey.

On the bottom deck the <50mm product is delivered by the feeder belt to a 1,000mm wide electrically driven inclined feed belt. This wide conveyor is fitted with an integral wash box to pre-soak the material and deliver the material to the full width of the screen thus utilizing the full screening area. The 16ft x 5ft (4.9m x 1.5m) three-deck screen is electrically driven producing an aggressive 6mm throw and is fitted with eight individually controlled spray bars on each deck.

The sized and rinsed aggregates produced by the screen are stockpiled on three integral 9m stockpilers. The dual sand plant includes two rubber-lined centrifugal pumps and two heavy-duty rubber-lined cyclones which remove silt (<75 micron). The silt-free sand is delivered to a split 12x5 screen to produce two grades of dewatered (12% moisture) silt-free sand. The sand stockpilers are radial powered through electrical wheel drives and have a stockpiling capacity of 350m3 .

Dowling Quarries use the sand for plastering and block-making, and in the production of concrete. Overall there is zero waste from the plant and minimum sand being lost to ponds.

“This AggreSand plant is over 10 years old now, going on 11, and it has performed very well over that time. A lot of tonnage has been processed by the plant including difficult material which we initially didn’t think it could handle, but it has taken it in its stride,” comments Humphrey, who was there back in 2013 when the official unveiling and live demonstration took place at the company’s quarry in Abbeyleix.

The occasion was part of the TWS Annual Dealer Forum being held at the Heritage Golf & Spa Resort at Killenard in County Laois, attended by more than 40 TWS distributors from around the world.

Plant operators at Dowling’s Quarries were initially apprehensive about the advanced control system, however this was quickly addressed once they had the opportunity to use and familiarize themselves with the system.

“The control panel is extremely user friendly and provides a simple interface, while at the same time being very effective and offering full control of the plant remotely, for example the ability to radial the sand conveyors from the cab is an excellent feature,” said operator John Hamm who worked with the plant when it was first delivered and installed.

Humphrey Dowling remembers that day well. “The plant arrived on site and was installed in approximately 10 hours,” he said, adding that he likes the modular aspect of the plant, allowing it to be easily moved to another site if and when required.

Over the past 10 years, the AggreSand has required little maintenance apart from routine servicing, keeping the potential for downtime to an absolute minimum, with easy access to all servicing points, including pumps and screens.

Humphrey states: “Any parts needed are readily sourced. All of the components are available locally and delivered promptly by the team at Terex Washing Systems, so there have never been any issues.”

So, when the time comes to replace ‘old faithful’ what will Humphrey do? “This AggreSand has served us so well it would be very difficult not to go back to Terex when we want to upgrade. The fact that the very same people I dealt with 10 years ago are still there is a real bonus. They know me, they know my business and my needs, and that’s something I appreciate.”