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Warm Charging Project

April 19, 2022

Warm Charging delivers one Green Star point using InfraBuild manufactured reinforcing products

Warm Charging involves minimising the time between billet being cast and entering the rolling stage of manufacturing various steel products, such as the reinforcing bar and mesh produced by InfraBuild’s EAFs at Laverton and Rooty Hill.

During rolling, the billet must be hot enough to be rolled into the final shapes. This is achieved by placing it in a gas-fired reheat furnace. At this stage, the billet may vary in temperature, which makes a difference to the time it needs in the furnace. When done consistently and effectively, Warm Charging can deliver significant savings in gas use and carbon emissions.

In an ideal Warm Charging process, hot billets are picked up and fed to the mill using crane tines (prongs); alternatively, warm billets are handled using a crane magnet. However, this presents several challenges, including having the right equipment to handle hot billets and coordinating the caster and mill production schedules so the same billet grade is being cast and rolled in the mill at the same time.

The team at the Laverton Rolling Mill tackled these challenges with a few modifications to the plant, including installing a crane lifting beam package to lift hot billets (controlled from inside the crane cabin), and modifying the bar and rod mill charge table to allow placement of hot billets without interfering with existing ones. Additionally, planning and scheduling is being addressed to align steel making and optimise opportunities using Warm Charging.

Since its introduction, Warm Charging has delivered increased energy savings and a tangible reduction in energy use. Warm Charging has also been in place for several years at the Sydney Bar Mill.

On the back of this initiative, a technical submission was put to the Green Building Council of Australia (GBCA) to recognise Warm Charging as a valid Energy Reducing Process (ERP) in Credit 20.1B of the Green Star ‘Design & As Built’ tool.

In March, the GBCA acknowledged that our Warm Charging technique qualified as a valid ERP, which will deliver one Green Star point from the use of reinforcing products made using InfraBuild manufactured steel. The formal notification is in GBCA FAQ 256 available on the GBCA website here: Green Star FAQs – Green Building Council Australia (GBCA).

The use of Warm Charging is in addition to the Polymer Injection Technique (PIT) which was recognised by the GBCA in 2014 as providing the same Green Star point. InfraBuild can now use PIT and Warm Charging to provide reinforcing bar and mesh products with one Green Star Point, as they occur at different stages of the steelmaking and rolling process

As part of the GBCA’s approval, InfraBuild needs to meet two conditions stated by the GBCA: undertaking a third-party review and compliance with recommendations from the review; and providing annual updates to help educate the wider industry on the benefits of Warm Charging.

The third-party review has already been undertaken by thinkstep-anz and independently verified by start2see, while the annual update (which will be publicly available) will be reflected in our annual ERP certificate on our website.

This initiative forms part of InfraBuild’s CN30 Objective, to be a low emission, carbon neutral steel maker by 2030.  Our use of Warm Charging is a deliberate choice that we are making to help us to reduce our Scope 1 emissions, redefine steel as a green building material, and further assist our customers to improve the sustainability credentials of their projects

Img: A stack of InfraBuild Energy-Reducing Process Certificates. The top ERP Certificate is lifted and hovering over the rest of the stacj

View the InfraBuild Energy Reducing Process Certificate 2021.

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