Thin Spray-On Liners: The Development of a New Mining System
The case is presented for the development of a spray-on liner for ground support, but only in the context of a new mining system, consistent with the technical and business case advantages of liners compared to alternatives. Over the past 10 years much effort has been expended in specifying and testing the mechanical/environmental properties of various liners, without actually fulfilling any mining system requirements. The results have been generally disappointing, with no consistent and sustained application in a day-to-day production environment being achieved, anywhere. Central to this shortcoming has been the failure of mining/liner manufacturing companies to realise that screen/mesh or shotcrete cannot simply be replaced with thin, deformable liners: success will depend upon closely defining and evolving a new, liner-functional mining system.
The paper begins with a discussion of some fundamental technical capabilities and constraints associated with 3M Canada’s liner material that has been developed in partnership with Falconbridge Limited. Intended applications for this liner include the support of bursting ground associated with deep mining conditions. With safe application and consistent performance in mind, the paper argues for a new mining system that derives in the first place from best quality drilling and blasting practices. Taking this as a given, a system for waterscaling and liner application prior to mucking out is proposed, followed by bolting through the liner while arranging for the bolts to be explicitly connected to the liner. Some logistical and equipment related challenges of such a mining system are then reviewed and discussed in the context of the business case for liners. It is concluded that this approach, if successful, will provide the greatest benefits in the areas of safer mining, due to reduction in worker exposure, and in reduced mining cycle times.
Thin spray-on liners, Mining System, Ground support systems