Recycling
Recycling: The process of economic recovery and use of ALL waste glass Steve Whettingsteel* discusses some of the challenges in creating truly sustainable glass and outlines a series of refinement solutions.
The Myth of Bottle to Bottle A further challenge is the long chain CO2 cost of delivering glass to a furnace, the claimed CO2 benefit of using cullet does not account for its recovery, recycling, transport, nor the disposal to landfill of the glass which is not suitable for remelt (pic 1). Having a clear demonstrable CO2 value for cullet or other glass products along any part of its recovery, processing and re-use should be part of any responsible strategy, and to use the glass in a way where the true CO2 cost of each product or market determines its use. Contrary to popular belief efficient and effective alternative markets for glass unsuitable for remelt can play a
� Pic 1. Green colour sorted remelt quality cullet. substantial in the overall reduction in CO2 of the glass recycling industry. Many governments and authorities blindly sign up to the policy of ‘the only true glass recycling is the production of new glass’, not considering the total capacity of furnaces within an economic distance, or the matter of what coloured cullet requirements these furnaces have. This often leads to a glass recycling programme to collapse or indicate disproportionally high cost, eventually having to concede landfill daily cover as material having been recovered and repurposed to meet recycling rates and targets.
� Pic 2. Broken car windscreens (laminated glass)
It is often touted that optical sorters can recover cullet at 3mm, which of course they can, but how efficiently and at what cost per tonne? There is a natural balance of economics in glass recycling which is lacking in clarity. This lack of clarity is detrimental in creating long term stability of the whole glass recycling process. Supporting the development of low CO2 sustainable alternative uses for the glass unsuitable or uneconomic for use as cullet should be championed, not derided. Their use provides economic stability for the recycler, as well as improving overall cullet quality and availability.
Keeping Waste Glass out of Landfill Glass that cannot be used for remelt is often sized <10mm (1/2”) and contaminated with Ceramic, Stone and Porcelain (CSP) among other materials. This glass is certainly the most challenging aspect of glass recycling due to its high levels of multi product contaminates, putrescibles and organics, as well as being uneconomic for optically sorting (Pic 2). There are also a number of ‘harder to recycle’ glass products that while they cannot be recycled in a local MRF, can be recycled by dedicated glass processing plants. These include but are not limited to: heat treated glass (such as Pyrex or drinkware), laminated glass (such as window glass or car windshields), pharmaceutical glass, solar panels and CRT. The challenge within the glass recycling industry is to create a sustainable low CO2 product from 100% of the glass entering the recycling facility. Continued>>
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ontrary to popular belief it is a technical impossibility for all used or recycled glass to be considered as furnace ready feedstock. However unfortunately the public, industry and legislators have been misled to believe that ‘bottle to bottle’ is the only true form of glass recycling. While this is the ideal in a utopian circular economy, in reality globally in excess of 50 million tonnes of glass is produced annually, with less than 40% being used for new glass production. Therefore, not considering any other end markets for the processed waste glass results in a large percentage ending up in landfill as daily cover or used as a low value aggregate substitute Where possible remelt cullet should always be the primary marketplace for recycled glass, however limitations of furnace capacity in many countries, low cost of imported glass, colour disparity, quality, contamination, location, and economics have proven over decades to be the principle challenge in creating sustainability.
21 Glass International November 2021
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23/11/2021 14:10:50
