Scrubbing sands: Terex Washing Systems

Terex Washing Systems details the specifications of a new state-of-the-art aggregate washing plant in the South of England.

Construction and demolition waste management specialists R Collard have opened a new state of the art aggregate washing plant at its recycling facility in Eversley, Hampshire, UK.

The new washing plant, designed and supplied by Terex Washing Systems (TWS), incorporates the latest technology to enhance the quality and efficiency of the facility’s recycling process.

The installation was specified and project managed by TWS’ England and Wales distributor Duo Plc.

Capable of throughputs up to 120 tonnes per hour, with an annual production capacity of around 250,000 tonnes, the system will provide a local source of high-grade recycled aggregate products 12 months of the year.

The goal: to enhance the efficiency and environmental performance of regional construction and civil engineering developments in the South of England.

“Transport is a major factor in the cost of aggregate, so our investment in this plant is a direct response to increasing demand for high quality, affordable recycled product in our catchment area throughout the South East England,” says Robert Collard, Collard Founder and Managing Director.

“The refinements to the technology involved will enable us to process more waste than we collect from local sites, and create a truly closed-loop recycling system for construction waste in the South of England.”

TWS’ recycling processes are designed to transform construction and civil engineering waste into clean, homogenous recycled products.

This is achieved by removing lightweight and deleterious contaminants and extracting silt and clay, which can bind otherwise commercially viable aggregates together.

According to TWS’ Elaine Donaghy, the plant boasts a number of innovative new features, including hydrocyclone technology that produces high-grade coarse sand product with less than two per cent silt content.

Furthermore, the plant features integrated sorting systems that remove non-mineral contaminants to a greater extent than conventional dry systems, enabling more waste to be used as feedstock.

“The plant can operate all year round due to a new feeder system, which processes cohesive material even when its moisture content changes. Fully adjustable and modular components also enable bespoke products to be generated,” Donaghy says.

“The wash plant set up at R. Collard’s is an innovative, effective and coherent approach for the recycled aggregates industry.”

AGGREGATE WASHING

The R. Collard’s plant draws from TWS’ extensive range of washing equipment, incorporating the Warrior 1400 scalper, AggreeSand 165 3D2S and AgreeScrub 150. The plant also utilises a Thickner and Filterpress for water treatment and recycling.

“The process starts with an AggreScalp heavy duty scalping unit, particularly suited to claggy and clay contaminated, high soil content feeds,” Donaghy explains.

“This unit removes excess oversize before passing the bulk of material to the subsequent washing equipment.”

The AggreScalp includes a magnet to capture ferrous metals, specifically located to allow ferrous metals to be extracted in free fall before transfer to the AggreSand.

The AggreSand incorporates a 16×5 three deck screen to produce clean 50-millimetre aggregate for subsequent crushing, delivering the mid and bottom deck outputs to its partnering AggreScrub 150 for attrition and sizing.

Typical feed material contains high root content, Donaghy says, which is effectively removed by the AggreScrub.

“The flotation capabilities of the AggreScrub are ideal for addressing the variable contaminants found in recycled aggregate sources such as paper, wood and light plastics,” she adds.

“These contaminants, together with most of the water and liberated sand particles, are passed from the rear of the AggreScrub to the integrated trash screen. This step recovers the lightweight contaminants as a waste and allows the water and sand to be collected.”

In addition to flotation, Donaghy says the AggreScrub’s other key purpose is heavy attrition, which liberates adherent clays to produce clean organic-free aggregates for a wide range of construction requirements.

A 12×5 part rinser integrated within the AggreScrub modular chassis then provides the final product splits, as requested by Collards.

Underflows from the trash screen and the aggregate sizing screen are collected and pumped back to the AggreSand to recover any saleable fine material, ensuring maximum efficiency of water management.

“The 120 tonnes per hour sand plant integrated within the AggreSand produces two high quality sands from the recycled feed material, suitable for concrete, pipe bedding and general construction requirements,” Donaghy says.

“Sand and water from the AggreSand screen, together with return water and fines from the AggreScrub, is recovered via the integrated hydrocyclones, producing coarse and fine sand fractions.”

Sand fractions are then dewatered by the system to ~12 per cent m.c., providing clean and ready to handle material stockpiles.

All dirty water gravity flows from the AggreSand’s cyclones to the congruent water management system.   

“By incorporating the very latest technology to enhance the quality and efficiency of the recycling process, the plant significantly reduces cost, fuel consumption and the carbon footprint of supplying recycled aggregate to a number of key developments in the UK,” Donaghy says.

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