PowerX Equipment Design & Install Sixth Wash Plant for NRS

PowerX Equipment have recently delivered a Wash Plant, Water Treatment Plant and a Filter Press to NRS Waste Care at their new Meriden Park operation near Coventry, to process C&D materials.

This is the sixth plant for NRS that PowerX Equipment has supplied; designed, built and commissioned the plant has an operating criteria to operate up to 150tph and produce sharp, soft and, ultra-fine sand, along with 3 aggregates – 10mm, 20mm and +20mm.

The plant has also been configured that when processing sand and gravel the wastewater and silt will bypass the press and go straight to the lagoon system, utilising the sludge tank feed pump.

The primary recycling waste screen:
The plant is unique in that it features a primary 4.9m x 1.55m, 2-deck screen [bottom flip-flow] which provides the facility to remove the -10mm out before the wash plant.

To achieve this the primary screen has been modified so that both the side conveyors are on the same side, enabling the fines to be fed onto an adjacent reversible horizontal conveyor [CV1] allowing the material to go forward to the wash plant or by reversing the conveyor to stockpile the -10mm into a bay. The second side conveyor goes directly onto the wash plant feed. The +20mm can also be sized by the screen modules on the screen if required. The oversize material is stocked in a bay for later crushing where sub-base materials are made.

Plant process:
The plant is fed by excavator through the 9.m³ hopper of a mobile Flip Flow Scalping Screen which features a 16 x 5 screen box which is highly efficient while maintaining exceptional throughput productivity. This in turn feeds the primary screen where material is then fed onto the 38m long inclined plant feed conveyor [CV2] with material passing under an overband magnet.  This conveyor then feeds material into a 4.9m x 1.5m Double-Deck Rinser which features 8 isolated spray bars [each with independent ball valve] and a twin grade sand catch box.

Material then passes through the Twin-Shaft Logwasher with the blades conveying the material from the feed end of the scrub to a 3.7 x 1.5m Double-Deck Part Rinsing Screen. Any organics such as roots are floated off to be dewatered over a 1.8m x 0.6m Trash Screen. Underflow from the trash screen is received in a catch box under the screen and then gravity fed to the sump tank under the hull. Any fines off the back end of the Logwasher are sent to the twin compact sand plant via a sand sump with a horizontal pump.

Scrubbed aggregate then exits the main discharge of the Logwasher onto a 3.7m x 1.5m Double-Deck Sizing Screen which splits the required products of 10mm, 20mm and +20mm aggregate which are then stockpiled by stone conveyors into concrete bays [by NRS].

Sand recovery:
The Compact Sand Recovery Unit at Meriden is an all-electric plant and combines a Collection Tank, Centrifugal Slurry Pumps for both grades of sand, a Hydro-Cyclone for both the sharp and soft sand and a 3.7m x 1.5m Dewatering Screen on a single chassis. It can recover 2 grades of sand from a wet feed and offers a maximum recovery of saleable material through the removal of silt, slimes and clays below 75μm (200 mesh).

Constructed in a robust easy to assemble steel construction, it features galvanized walkways and handrails to provide easy access. It provides low maintenance and simple operation with a self-regulating cyclone tank. Pumps and cyclones have replaceable rubber liners for extended wear life with a high frequency dewatering screen reduces residual water content in your final product to 10–12%. This all-electric plant is driven from a dedicated control room through a PLC controlled panel to an NRS specification.

Ultra Fines recovery:
At the Meriden operation a sand recovery unit which supplies the ultra-fine sand is a crucial step in efficient management and recovery of ultra-fines sand from waste-water streams, produced from washing processes. This Ultra-Fines Sand Recovery Unit can process up to 450m³/hour of slurry recovering material as low as 40µ, thus reducing the volume of solids reporting to storage ponds or water treatment plants.

Bringing together a Centrifugal Pump, a cluster of 4 Hydro-Cyclones and a  high frequency 2.4 x 1.2m Dewatering Screen on one chassis. This unit also boasts a uniquely designed conical tank and anti-turbulence system, which is essential in the process of ultra-fines recovery.

Water Treatment Plant:
The fully integrated water treatment plant at Meriden, consists of a galvanised 16mØ Dynamic Thickener which stands at 3.5m high this provides a minimum of 500m³/hr flow rate and has a 700m³ volume capacity with a low flocculent consumption. The plant has the facility to dose, flocculants, coagulants and anti-foaming polymers, to facilitate the processing of more contaminated materials.

A 14m – 3m high Clarified Water Tank provides a 460m³ capacity with a technical room housing the Flocculant Dosing Unit and a Filter Press. Rainwater is collected in a 1000m³ galvanised tank with high and low sensors and two pump points.

This process allows up to 95% of the water used in the washing process to be re-used. The dirty water is collected in a sump before being treated and allowed to settle in the Thickener. The thickened sludge is then sent to a 100mᶟ buffer tank to control the density of the sludge prior to being  compressed within the 2000mm x 2000mm x 165 plates filter Press enabling the last remaining water to be sent back into the system. NRS are then able to use the 30mm filter cakes that are expelled from the filter press.

The complete C&D processing solution:
Mark Ketcher – CEO of NRS Aggregates, “This is our sixth plant that has been delivered by PowerX Equipment and again they have delivered a processing plant that is exactly what we required. The new wash plant means there is virtually no waste in our C&D processing and the water treatment and filter press enable us to maintain low water usage and turn waste sludge into a usable product. The PowerX engineering teams are first class and their commitment to H&S is above and beyond industry standards.”

MD of PowerX – Luke Talbot, commented, “Our philosophy at PowerX Equipment is that we are committed to supporting NRS long after their plant installation. We understand that the key to their success is having reliable, fully operational equipment to keep productivity flowing and downtime to an absolute minimum. This is why we have invested in our Spares and Service Division to ensure we not only have a wide range of parts, but also an expert team of fully qualified and experienced engineers available to help our customers with advice, maintenance, and fitting in a timely manner.”