Glass

Problems caused by glass:

Affects the chemistry of the aluminium at the melting stage.
Presents a health and safety risk.

Glass contains silica. The maximum tolerance for silica in aluminium can body sheet is ~ 0.25%. Silica inclusions can affect the performance of the can sheet in the sheet rolling and can manufacturing process.

Silica reacts with aluminium in the melting furnaces and 'consumes' aluminium, which is lost to the process [3SiO₂ + 4Al --> 2Al₂0₃ + 3Si]. The reaction produces silicon which can lead to 'off-specification' melts.

50kg of silica can bring 70 tonnes of metal (one of the Novelis furnaces) out of specification and lead to time-consuming and costly dilutions.

How to avoid contamination from glass

For more advice on reducing contamination, see Quality Matters: Earn More From Your Deliveries.