Wash recycling as it should be

by Moira Brady / Emerald Equipment Systems

Construction and demolition waste management specialists Collard have opened a new state of the art aggregate washing plant at its recycling facility. 

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

Capable of throughputs up to 135 U.S. tph, with annual production capacity of around 300,000 tonnes, the system will provide a local source of high-grade recycled aggregate products 12 months of the year to enhance the efficiency and environmental performance of regional construction and civil engineering developments in the surrounding area.

Collard’s founder and managing director Robert Collard commented, “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 Northeast. The refinements to the technology involved will enable us to process more wastes than we collect from local sites and create a truly closed-loop recycling system for construction waste in the local area.

Terex Washing Systems’ recycling processes transform construction and civil engineering wastes into clean, homogenous recycled products by removing lightweight and deleterious contaminants and extracting silt and clay which can bind otherwise commercially viable aggregates together. Material processed at the site will be used in a broad range of construction projects.

The plant boasts a number of innovative new features including:

• Hydrocyclone technology producing high-grade coarse sand product with <2% silt content

• Integrated sorting systems removing non-mineral contaminants, to a much greater extent than conventional dry systems, enabling more wastes 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 enable bespoke products to be generated

The wash plant set up at Collard’s is an innovative, effective and coherent approach for the recycled aggregates industry. It constitutes scalping (Warrior™ 1400), aggregate rinsing and sand washing (AggreSand™ 165 3D2S), aggregate scrubbing and sizing (AgreeScrub™ 50) and Matec water treatment and recycling (thickener and filterpress).

The process starts with a Warrior 1400 heavy duty scalping unit particularly suited to claggy and clay contaminated/high soil content feeds. This unit removes excess oversize before passing the bulk of material to the subsequent washing equipment. The Warrior 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 producing clean 2”+ oversize for subsequent crushing and delivering the mid and bottom deck outputs to its partnering AggreScrub 150 for subsequent attrition and sizing. The feed material contains high root content 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. 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, the AggreScrub’s other key purpose is heavy attrition to liberate adherent clays, producing clean, organic-free aggregates for a wide range of construction requirements. A 12×5 part rinser integrated within the AggreScrub modular chassis provides the final product splits requested by Collard.

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