Sunday 1st Mar, 2020

Reclaiming the concrete jungle with Lincom’s new reclaim plant

Lincom Group’s Concrete Washout Reclaim plant is helping recyclers recover sand, water and aggregates while reducing waste and handling costs.

Lincom Group’s Concrete Washout Reclaim plant is helping recyclers recover sand, water and aggregates while reducing waste and handling costs.

Recovering sand, water and aggregates for beneficial reuse and minimising handling costs have been on the agenda of Lincom Group over the past year.

The materials processing equipment specialist has performed extensive research and testing to develop a concrete washout reclaim system that allows concrete recyclers to capture clean sand, aggregates and water for future reuse.

Pete Godwin, Manager of Lincom’s newly introduced Environment and Process Division, says the product combines a Rapid Reclaimer with an Ostwald Filtration Systems (OFS) filter press, allowing the company to service a greater proportion of the market.

The system was put on display at the Firth Concrete yard in February in Auckland – the largest national manufacturer of ready-mixed concrete, letting attendees get an up-close glimpse of the concrete washout reclaim system.

“We’re doing something very separate and distinct from the normal sand and aggregates business,” Mr Godwin says.

“The reclaimer was around 30 years ago, and the world seemed to lose interest for a time, but right now it’s on the top of everyone’s list.”

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One particularly popular selling point was the system’s ability to significantly reduce the footprint for concrete reclaim.

Mr Godwin explains that the prices of real estate in New Zealand and Sydney have made this option attractive, as companies can get more work out of a much smaller yard with just a filter press and a reclaimer.

“If it costs one or two million for a block of land in Auckland, you can take a third of that off because of more efficient use of space,” he says.

Traditionally, concrete plants used to have settling ponds that could take up large amounts of space with cement and stone settling to the bottom. After a week, the water would be pumped out to recover sand and aggregates that emerged.

However, the German-designed and manufactured OFS recessed chamber filter press uses a proven solid/liquid separation technology. Unlike a settling pond system, the filter press is more compact. Dirty water is pumped from the agitated storage pond, through the press, then back into a clean water pit.

This reduces the amount of dust generated from breaking up dry waste concrete, according to Mr Godwin.

“If you can reclaim the concrete at its wet stage there is no dust generated, so environmentally that’s a good thing,” he says.

“The rain that falls from the sky ends up going through the same process so it’s a big general clean-up of the area. Concrete plants spend all day hosing due to the dust created and they use large quantities of water to allay the dust.”

The rapid concrete washout reclaim unit takes waste concrete and deconstructs it back into its base sand and aggregate components. The OFS filter system then recovers grey water by filtering and compressing dewatered cement fines into manageable ‘cake’ form, solving a variety of issues for concrete producers.

The rapid reclaimer is capable of processing up to 20 cubic metres of concrete slurry per hour.

It then discharges the cementitious water into the dirty water pit where it’s continually stirred to keep the spent cement fine particles in suspension. The clean water, known as filtrate, is captured and returned to a clean water pit for use in further concrete batches and reuse in the reclaimer’s washing and separation process.

Sand and aggregates are separated within the reclaimer, with the dewatered sand conveyed by twin hydraulic screws to one pile, while the washed aggregates exit via a belt conveyor to another separate pile. The cementitious water overflows the adjustable weirs and is piped via gravity to an agitated storage pond.

At the end of the cycle, filter cakes fall into the void below the filter press where they are removed as waste or for beneficial reuse.

Mr Godwin says the feedback from customers was highly positive at the Auckland demonstration with a significant number of New Zealand and Australian customers impressed with its capabilities. He says customers were particularly drawn to the high quality of water.

“When the aggregates come out, they are clean. If I pick up a handful of aggregate, there is no colour on my hand – it’s just clean water.”