And RMIT University-led project examined ways to overcome the barriers of recycling glass fines.
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Glass fines are the small glass particles (typically between 3 and 8 millimetres in size) that are broken during commingled recycling collection, transportation and processing.
The market for using glass fines in new products is relatively undeveloped, so RMIT University partnered with leading sustainable materials producer Alex Fraser Group, and glass designer Mark Douglass, to examine ways to overcome the barriers of recycling glass fines and provide tangible insights for business and investors on the various uses of this low-cost but high-value material.
The project was supported by Sustainability Victoria through a Research, Development and Demonstration grant and resulted in the Glass fines: Final report (pdf, 9.7mb).
Glass fines are considered unsuitable for recycling or remanufacturing into glass for a number of reasons.
One of the major challenges for refining recovered glass fines is the mixing of colours that occur through the commingled recycling system.
RMIT glass fines report
The challenges associated with recycling glass fines often lead to the otherwise valuable glass material being stockpiled or landfilled.
The research project focused on understanding the properties of glass fines and identifying contaminates present from the commingled kerbside recycling process.
Alex Fraser Group provided a range of glass fine samples and a series of technical explorations were undertaken by the RMIT research group to define the characteristics.
The research found that:
The research identified and explored a diverse range of new uses for glass fines. These included using glass fines in:
And harnessing glass fines for:
This otherwise unutilised material could be used for a range of potential low cost, high-value product development opportunities.
RMIT glass fines report
Due to the low financial value of recycled glass fines, the sorting and cleaning methods need to be low-cost and easily integrated into the existing recycling process.
The research group explored a variety of options that can achieve these outcomes.
Alternative ways to separate glass fines from contaminants in the recycling process were explored and included:
Large-scale thermal-based cleaning can be conducted at 550°C for 15 minutes inside a conventional furnace to remove organic contaminants from glass fines.
It is possible to chemically remove the colourants and heavy metals present in glass fines. Colourants are typically metal oxides added in the original manufacturing of glass packaging. Promising methods explored in the report for chemically removing colours include:
The research group suggests the above methods should be explored further for their feasibility in industrial scale glass fines processing.
Recycling glass fines presents the opportunity to tackle a growing waste stream and reduce the need for natural resources.
Glass use in food and beverage packaging has increased over recent years. This is likely due to more virgin glass being imported, subsequently entering the waste stream and more glass fines ending up in landfill.
Finding new and appropriate uses for glass fines extends the material’s lifecycle.
Recycled glass fines can replace a percentage of materials such as sand and bitumen. By using glass fines in this way, fewer virgin materials are required in manufacturing or construction.
While the product of a recycling and waste commodity industry that is struggling to deal with issues of oversupply and inadequate systems, glass fines offer considerable opportunities.
RMIT glass fines report
RMIT University – in partnership with Sustainability Victoria, Alex Fraser Group and Mark Douglass Designs – took a multidisciplinary approach to addressing issues related to recycled glass fines.
The report details challenges associated with recycling glass fines, methods for improving the quality of glass fines and explores a diverse range of innovative applications for the material.
The ideas RMIT reported are designed to demonstrate opportunities for further research and development to develop the market and convert concepts into commercially viable applications.
Download RMIT's Glass Fines: Final report (pdf, 9.7mb).
Recycled glass fines, alongside other types of recycled materials, are starting to replace a percentage of virgin materials used in government infrastructure projects.
In 2019, Wyndham City Council increased the uptake of recycled content by trialing a concrete mix design and laying 200 metres of concrete footpath in Geddes Park at Hoppers Crossing, which contained 199,000 recycled glass and plastic bottles.
Downer has partnered with Hume City Council, Close The Loop and RED Group to set a new benchmark in sustainability and innovation, constructing Australia’s first road using a combination of soft plastics and glass.
These projects are examples of the circular economy in action.
Find out more on our Procuring recycled materials for government projects page.