Glass Fines: A review of cleaning and up-cycling possibilities

Abstract

Globally, glass is now a common choice for packaging products that are distributed to market. In Australia, over 1.3 million tons of packaging glass is consumed per annum. Each year only around 40% of the used glass in this pool is recovered nationally via a complex system of collection, sorting and re-processing. Thus there is a significant opportunity to recover this waste stream further.Throughout the glass recovery process, glass packaging is progressively broken into ever smaller pieces, to eventually form what is known as Glass Fines. Glass Fines are a hard waste to sort and the lowest value in the mixed waste stream due to their size, colour mix, and the range of non-glass contaminates that are additionally a part of the recovery system. Despite the high value the public holds for glass recycling, Glass Fines are in fact a by-product of a recovery process that enables the systemic degradation of an otherwise perfectly recyclable material.This research presents a review, designed to demonstrate ways that Glass Fines can be repurposed, recycled more effectively, or up-cycled. By matching applications for Glass Fines with waste processing and sorting techniques, realistic market contexts may be realised for this waste stream more readily by industry. Previous studies have approached such applications from resource efficiency and environmental impact perspectives, not from a market context. This research addresses the need for business engagement with Glass Fines applications, providing clarity on economic and technical characteristics of Glass Fines products for those interested in developing such markets.The review was conducted in two stages. The first stage, a literature review of characteristics of Glass Fines, cleaning technologies used to process waste glass, and applications for waste glass was undertaken. These data were categorized to identify ‘fit-for-purpose’ applications for Glass Fines within various industries. In order to encourage maximum valorisation of this waste stream, a set of criteria were developed inductively through the results of the literature search, to apply to the Glass Fines applications to categorise them according to the needs of business and investors. As such applications were arranged by way of these heuristic evaluation criteria to identify opportunities for the interoperability of related processes and markets for Glass Fines. Criteria developed included:•Market Development - Maturity of the particular application, from experimental phase, to early commercial development, to established industry practice;•Production Intensity - Energy requirements in the processing raw Glass Fines for the desired application;•Post Recovery Processing – Level of cleaning required when preparing the Glass Fines for production within a particular application;•Up-cycling Value - Rating intrinsic value of the end product versus being remanufactured into glass; and•Macro Market and Market Size - Matching applications within specific industry sectors, and to indicate its possible scale. Through this criteria and associated applications current suppliers and manufactures are provided new potential opportunities working with Glass Fines based on business relevant criteria such as cost, energy intensity and market value. This contribution could lead to future innovation in up-cycling Glass Fines as the global community moves to a more circular economy.