With glass and glass product manufacturers making up nearly a third of the sand and gravel market in 2018-19, producers have increasingly used recycled glass materials in their processes, reducing demand for silica sand from the industry.1
As crushed glass is being transformed into recycled glass and sand for construction, the benefits of glass recycling have sustainable and efficient advantages for the environment, saving energy and natural resources. For example, a glass bottle in landfill can take up to a million years to finally break down but a recycled glass bottle takes only 30 days to leave your recycling bins and become a new glass container in the supermarket, without loss of purity or quality.
In addition to becoming new glass vessels, recycled glass is also being utilised in many other areas such as reflectors in paints, as well as in roads. Due to the benefits of the process and product, there are an increasing number of sites taking up glass crushing and screening, particularly with suitable mobile equipment, to optimise this industry.
With a team specialising in crushed glass applications and knowledge, Astec Industries was an exhibitor at the Australian Waste and Recycling Expo in 2019, which featured equipment suitable for crushing glass. With one of the largest bluestone producers in Tasmania processing glass as a side project at 30,000 tonnes per year with Astec Equipment, a major processor in country Victoria has also come to the fold.
This country-based site in Victoria crushes and screens glass bottles in a dry closed circuit at an output of 80 tonnes per hour to produce a manufactured glass sand. The mobile equipment it is employing in in this glass recycling process is an Astec Industries GT200DF cone crusher and a GT205MF multi-frequency screen.
The GT200DF at the feed end in the process flattens the plastics (eg lids and straws) and delivers a clean product to the screen. This is in contrast to a vertical shaft impact crusher which would alternatively shred the material, requiring new bar tips approximately every four weeks from this wear. Comparatively, the manganese liners on the cone crusher have worn at a rate of once every 12 weeks.
The style of cone crusher the customer uses is a roller bearing machine. Working with this style gives producers a greater level of accuracy about settings and product specifications with a greater loading capacity than some alternative cone designs.
In the case of a roller bearing machine, its hydraulic tramp iron relief (TIR) system would identify an “uncrushable” object, opening up to allow this uncrushable piece to pass and then reset itself. The TIR system also minimises crusher overload impact shock loads that would be transmitted to the crusher components.
The roller bearings themselves are designed for a P90 of 20,000 operating hours (P90 is an industry measurement whereby 90 per cent of the bearing should last 20,000 hours or more – the other 10 per cent of failures are caused by a variety of different factors).
Finally, plastics, wood and other incompatible materials are screened off at apertures of 15mm to 18mm, with a manufactured sand product of 4.5mm or smaller being cleanly stockpiled. The discharged products are used as a sand replacement in asphalt, crushed rock products and pipe bedding material. The magnetic head drums on both of the side conveyors collect stray metals that are sent for further recycling.
From individual machines to complete turnkey solutions, Astec Industries offers creative and accurate solutions from equipment installation to complete turnkey engineered systems with advanced automation controls.
Source: Astec Industries.
REFERENCE & FURTHER READING:
1 IbisWorld B0911. https://www.sl.nsw.gov.au