Open Cut » Environment
The disposal of waste open-gear lubricants and other dragline greases and oils generated by the coal mining industry has proved to be an expensive and labour intensive practice. This is in the main due to the thick, tacky nature of the long-chained hydrocarbons required for such robust machinery combined with the associated difficulties involved in its' collection, breakdown and/or disposal. In the past, most sites have disposed of waste dragline lubricants through high temperature incineration or licensed landfill, with disposal costs in the vicinity of $250 per 205L steel drum. On a site with five draglines, disposal costs alone can be up to approximately $65 000pa.
Legislation and regulatory policies allow high temperature incineration while stipulating that wherever possible, 'Reduce, Reuse, Recycle, Responsibly dispose' strategies should be practised in accordance with the Waste Management Hierarchy. This project aimed to identify alternative practices that are viable from environmental, regulatory, economical and practical perspectives.
Literature on the management of these waste lubricants is very limited, and the information contained herein relied heavily on correspondence with the waste management and coal mining industries. Suggested management options were examined in the context of the Waste Management Hierarchy and economic and practical considerations.
The 'waste to energy' practice was identified as the best available technology. This process involves waste dragline lubricants being mixed with other solvents and being used as solvent based fuel (SBF). This approach is viewed as economically viable, and is also endorsed by regulatory bodies. The project also recognised the separation of waste streams at collection as crucial to improved waste management strategies. Careful streaming of waste types at collection ensures that Best Available Technologies are not hindered or rendered unviable by the cross contamination of waste streams.
The project drew heavily upon information supplied by the waste management and coal mining industries and further identified other current initiatives such as the commercial land farming of wire rope oil-contaminated soil, which are ongoing and for which critical assessment of their suitability will have to be made when more information becomes available.