Open Cut » Environment
The disposal of waste tyres from mining machinery in Australia remains problematic. Waste off-the-road tyres from mining operations have generally been buried in landfill or stockpiled in a registered waste area on site. Their size, construction and invariably remote location make their disposal or reuse difficult and expensive. A tyre is engineered and constructed for durability. When a tyre wears out, it remains a virtually indestructible parcel of rubber, chemicals, fabric and steel. At the end of its service life, an estimated 80 percent of its original resources remain trapped in the tyre. In Australia, about 10 million tyres expire annually. Most of them are disposed to landfill, either in shredded or whole form. Legislative change in Australia banning tyres to landfill is stimulating the development of retreading, reprocessing and energy reclamation technology.
Project Objectives
The project aims to identify opportunities to reduce, reuse and recycle scrap mine tyres and to identify cost-effective alternatives for managing waste off-the-road tyres at remote mining sites.
Findings
Tyre recycling technology and literature is focused on passenger tyres. The legislative impetus to ban whole tyres to landfill is designed to conserve urban landfill space and to promote recycling rather than to prevent contamination.
The technological and economic limitations in processing off-the-road tyres currently restrict alternative use to applications that use whole or sectioned tyres or steel-containing shreds.
While the use of tyre derived fuel (TDF) in cement kilns appears the most attractive alternative, the high energy and cost required to process, transport and dispose of the tyres make this option more appropriate for passenger tyres.
Recycling or reuse is extremely difficult to apply efficiently to off-the-road tyres on remote mine sites. There are no companies in Australia with the technology to process them, and the cost to transport the tyres for destruction is prohibitively high. This conclusion is reflected to some extent in recent legislative developments indicating that the disposal option, although not preferable, is acceptable.
The research findings concur with those of the Queensland Environment Protection Agency.
While potentially the highest consumer cost option, the extended producer responsibility principle would result in the greatest likelihood of scrap off-the-road tyre management moving up the waste management hierarchy.
The second most appropriate option would be site specific and depend largely on the proximity of the site to facilities that can process and use the waste.
For remote sites, whole tyre on-site burial at depth is the best option.
Where To From Here
Until the technology and economics of processing off-the-road tyres in Australia improves, disposal will remain problematic, particularly for remote mining operations.