Concrete Reclaimer Plant

Overview

A concrete reclaimer plant recovers the value left in returned and washed-out concrete. When a ready-mix truck comes back with unused concrete, or when drums and chutes are rinsed at the end of a shift, the result is a wet mix of coarse aggregate, sand, cement fines, and water. Left alone it sets into a solid mass that has to be broken out and dumped. The reclaimer catches that material while it is still wet, scrubs the stone and sand clean, separates them from the cement slurry, and recycles the grey water back to the batch plant. A plant of this size handles 20-30 m3/h of returned concrete and recovers about 90% of its wash water.

The plant chains together a Receiving Hopper and Wash Chute where the truck discharges, an Inclined Reclaimer Screw that lifts and dewaters the solids, an Aggregate Discharge that drops reclaimed sand and gravel onto a stockpile, an Agitated Slurry Pit that keeps the cement fines suspended in water, and a Water Recycling and Return circuit that sends the grey water back for reuse. A Control Panel runs the cycle from level and density readings.

Receiving and washing

The truck backs up to the Receiving Hopper and Wash Chute and discharges its load into a Hopper Body lined with bolt-on Rubber Wear Liner sheets. A Grizzly Grate across the inlet catches rebar offcuts and any concrete that has already set into lumps, since those would jam the screw. A pair of Spray Bar Manifold manifolds fitted with flat-fan Wash Nozzle heads flood the load with water at 4-6 bar, breaking the concrete apart and flushing it down the Wash Chute into the reclaimer.

Coarse aggregate that needs extra scrubbing passes through the Aggregate Wash Drum. The Drum Shell is a perforated cylinder with 6 mm screen holes, turning at 12 rpm on four Trunnion Roller supports. Internal Drum Lifter Flight vanes cascade the stone so an In-Drum Spray Manifold manifold can rinse every face. Cement film washes off through the perforations and the clean stone tumbles out the far end.

Separation and dewatering

The heart of the plant is the Inclined Reclaimer Screw, an Archimedes auger climbing at 18 degrees. The 380 mm Auger Flight sits in a Screw Trough whose lower end is a submerged wash pool and whose upper run is open to drain. The flight turns at 25 rpm on a Auger Shaft, carrying coarse aggregate and sand up the incline while water and cement fines drain back down through the settling pool. By the time the solids reach the head, free water has run off and the reclaimed aggregate is damp but stackable. Because sand is abrasive, the flight edge carries bolt-on Flight Wear Shoe wear shoes, and a Trough Overflow Weir sets the wash-pool level and bleeds the overflow slurry to the pit. The wet lower end runs in a sealed Submerged Tail Bearing with a grease purge that keeps slurry out, while the dry head end rides on a standard Ball Bearing pair protected by an Oil Seal.

Cleaned aggregate leaves through the Aggregate Discharge. The Aggregate Discharge Chute drops it onto a Stockpile Conveyor, a 600 mm belt running over Conveyor Pulley drums and Troughing Idler sets, stacking the reclaimed sand and gravel into a pile that goes straight back into new batches.

Slurry handling

Everything that drains off the screw and drum is cement slurry: water carrying suspended cement fines and the finest sand. It flows to the Agitated Slurry Pit, an 8 m3 Slurry Pit Tank that must never be allowed to settle, because cement that settles will set hard in the bottom of the tank. A Paddle Agitator with a 1.2 m sweep turns at 30-45 rpm on an Agitator Shaft, keeping the fines in suspension around the clock. A Slurry Density Probe reads slurry concentration, typically 1.0-1.3 kg/L, and a Pit Level Sensor tracks the level. Slurry collects in a Collection Sump feeding the Slurry Pump Set.

The Slurry Pump is a rubber-lined centrifugal unit rated 40 m3/h at 20 m head. Pumping abrasive slurry wears parts fast, so it runs a high-chrome Pump Impeller and replaceable Pump Casing Liner casing liners, with a Suction Strainer keeping lumps out and seatless Pinch Valve pinch valves that cement cannot clog.

Water recycling

The Water Recycling and Return circuit closes the loop. A Settling Clarifier lets the last fines settle so the overflow stays below about 1.05 kg/L, and the Water Return Pump, rated 30 m3/h at 25 m head, sends that reclaimed grey water back through the Return Piping to the batch plant water tank. A Return Flow Meter logs how much is returned each batch, and a Make-Up Water Valve tops up with fresh water on low level. Recovering around 90% of the wash water cuts both water consumption and the cost of trucking off settled sludge.

Materials and drives

Wear governs the material choices. Wetted impact surfaces are Hardox 400-450 or chromium carbide overlay, the slurry pump runs high-chrome iron and rubber, and the Structural Frame is welded S355 steel with an Incline Truss holding the screw at its working angle. The Drive System uses three geared motors, a 7.5 kW unit on the screw, 5.5 kW on the drum, and 4 kW on the agitator, driving through Gearbox Housing reducers, Helical Gear Pair sets, and flexible Shaft Coupling joints. Total installed power is about 22 kW.

Operation and control

The Control Panel runs the plant automatically. Its PLC Controller starts the screw, drum, agitator, and pumps in sequence through Soft Starter soft starters, watching pit level, slurry density, and wash-water pressure. The operator sees pit level, density, and recycled volume on the Operator HMI. The agitator must keep running even when the plant is idle, since a stopped pit sets solid overnight, so the control logic holds the agitator on whenever there is slurry in the tank.