Plasterboard Recycling - Airknife Separation

Impact Air Systems were contacted by Hamilton Waste & Recycling Ltd, operating in extensive waste collection and recycling facilities in East Lothian.

Overview

David Hamilton, director of Hamilton Waste & Recycling commented:

“We are delighted with the air separation and dust extraction technology that Impact Air Systems provided for our plasterboard recycling system. Not only are we delighted with the performance of the system, but also the service we received from Impact Air, from our initial discussions through to the commissioning of the plant.  Impact Air’s system has certainly surpassed our expectations and we at Hamilton Waste & Recycling Ltd will be looking first at Impact Air Systems for any future air separation and dust extraction systems.”


Impact proposed installing their highly effective Airknife separation system which due to its totally enclosed design would provide the additional benefit of dust containment and improved working environment. The pre-shredded plasterboard is introduced into the plant and passes over a series of screens which sort the product by size into 4 streams.


The 5-15mm, 15-25mm and >25mm waste streams are conveyed to pulverisers for further processing. Prior to reaching the pulverisers an Airknife assembly is installed at the transfer point between each of the waste stream conveyors and the pulveriser feed conveyors. As the material passes through the high velocity jet from the Airknife, the lighter paper particles are thrown towards the capture hood, which in turn removes them from the waste stream. The heavier gypsum product then passes through the pulverisers which release any paper still attached to the gypsum. The pulverised material is then passed through the system again to remove the paper.

Each Airknife is connected to a high efficiency backward curved fan which is 85-90% efficient thus minimising energy consumption. The fans are also fitted with frequency invertors which allow the velocity at the Airknife to be adjusted to give the optimum material separation.

The paper extracted by the capture hoods is conveyed through a range of ductwork to a rotary separator which removes the paper from the airstream and discharges it into skips. The dust laden conveying air is then cleaned by passing it through a reverse jet filter before being exhausted to atmosphere. In addition, a centralised dust extraction system was also connected to the reverse jet filter. This was designed to contain the dust produced during the screening, conveying and pulverising operations.

Again, with energy conservation a priority, the main dust extract fan was located on the clean side of the filter allowing a high efficiency backward curved model to be selected.

The system was installed on time and within budget and has been operating successfully since installation.

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