The Assinck tilting boom grab dredge is allowing aggregate producers to reach new depths of extraction.
The new floating dredge transforms how aggregate producers maximize their reserves. It creates the opportunity to extend the life of existing pits without the lengthy land acquisition and permitting phases for aggregate extraction, which can take years to finalize.
On Oct. 3, Assinck unveiled the first machine of its kind at James Dick Construction’s Caledon Sand & Gravel pit in Caledon Village, Ontario. The tilting boom grab dredge is set up on a manmade lake that was created using a drag line.
“Drag lines just don’t get deep enough. They realized they had left a lot of material behind in various depths in different areas, and they didn’t get as deep as they thought,” said Dean Glenn, Vice President of Assinck.
“With the value of land today, it just made complete sense to design a machine that can go down 80 to 100 feet and extract all that material.”
The Assinck floating grab dredge

The Assinck floating grab dredge is outfitted with a 7-yard hydraulic clam shell bucket and it has the capacity to process 400 tons of 7” minus material per hour.
“We located a company in Germany that specializes in underwater dredging. That’s all they do is make dredging buckets,” Glenn said.
The dredge includes an advanced hydraulic tipping self-cleaning grizzly screen that discharges rocks that are too large for processing back into the lake. As well, the system features a robust scalping screen and a modern fines recovery system that utilizes hydrocyclone technology for peak efficiency.
“There’s a 6×20 triple deck screen in there and then there’s a vertical worm and pump that picks up all the sand through the bottom deck pass on the primary scalping screen,” Glenn explained.
The pump then delivers the material into a hydrocyclone that completes s cut at 40 microns.
“We’re recapturing the sand product, and it’s discharged onto a high frequency dewatering screen. So, we’re drying the product out before we put it back on the conveyor belt, and then everything’s brought to shore after that,” Glenn said.
Control system

The dredge is also equipped with a sophisticated control system. The advanced programmable logic controller (PLC) system and user-friendly human machine interface (HMI) control the machine.
The configuration provides operators with control and flexibility, enabling them to make instant changes and effortlessly navigate difficult deposits. An automated positioning system controlled by a PLC and operated with a joystick controller includes four electric winches with self-spool fairleads, allowing for easy adjustments to the dredge’s position in the lake when mining locations shift.
“With the onboard positioning system, it is super user friendly,” Glenn said.
“You just simply turn on the positioning system, move the joystick control, and you move.”
The dredge’s material processing plant is integrated into the machine itself and includes a floating conveyor system that delivers material to shore for further processing.
This system is designed with an elaborate slew bearing to accommodate intricate operating angles and is built to be exceptionally robust.
Constructing the dredge

Engineering the tilting boom grab dredge required about a year of work by Assinck.
Procurement and fabrication required another year followed by a six-month assembly period.
When it came time to assemble the system, Assinck dredged an area of the lake to get the required barges into the water.
“For the barges that it’s sitting on, we contracted a company in Cornwall, Ontario to build those for us. It took them a year to build,” Glenn said, noting the barges weigh about 113,400 kg.
Assinck then built a dike and dewatered the area to assist with construction of the material processing plant and floating conveyor system.
“As soon as we had the machine built, we opened the dike, let the water flood in, and we floated it up, and we kind of moved it out,” Glenn said.
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Based in Toronto, Assinck has been providing complete solutions for industries such as aggregate, mining, environmental and industrial since the company was founded in 1952.
The Assinck Tilting Boom Grab Dredge was created and produced in Canada by engineers and millwrights, and the dredge is the first of its kind for Canadian aggregate operations. Glenn explained the goal of creating the system was to maximize the lifespan of existing properties with aggregate licenses.
“You own the property, and you own everything. If you can go down and get another 60 feet out of that area, you can expand and extend the life of a pit by 10 or 20 years,” he said.