INEX is the largest producer of aluminium profiles in New Zealand and holds a unique position as the only extruder in Australasia which recycles its scrap directly with an aluminium smelter.

The company, which produces profiles for the Altherm, First and Vantage window brands, has invested in an aluminium compactor to consolidate scrap profiles into bales for convenient shipment to the NZ Aluminium Smelter plant at Tiwai Point in Southland. These bales and other surface metal items of waste, called 'butts,' which are produced in the extrusion process, are used at Tiwai as a highly efficient coolant in the hot metal that needs to be reduced in temperature before casting.

Recycling in this manner through billet preparation furnaces dramatically reduces the energy input that would otherwise be incurred if the material was recycled through an industrial remelt plant. In addition, the re-use of INEX material at its billet supplier means that the company is, in effect, using virgin billet that may have up to 8% of INEX recycled metal content.

The 40-tonne compactor at INEX has a hydraulic ram with a shearing force of 195M/T and a packing pressure of 262 Bar. The result is a scrap bale 360mm square with a density of 950KG per cubic metre. A sub-floor layout was built with 270M/T of concrete and 25M/T of reinforcing steel to ensure no structural movement.

APL General Manager Marketing, Shane Walden said that APL and INEX had a multi-faceted programme to mitigate aluminium's high 'embodied energy' and pointed out the favourable comparison between aluminium and alternative window materials for both recyclability and durability.

"Aluminium is notable for its ability to be recycled indefinitely, owing to its high intrinsic value," he said. "A balance needs to be achieved between energy conservation and the ideal allocation of energy-rich materials to appropriate end uses. Aluminium is best used in applications where its unique properties are indispensable."

Mr Walden said that aluminium alloys have unusual strength, light weight, ductility and corrosion-resistance and the metal's use in windows imparts attributes of span, scale, strength, functionality and aesthetic capability that alternative window materials have difficulty in matching. "Modern architectural trends and practices would be hugely impacted if exterior aluminium joinery was unavailable," he said.