Boeg-Jensen, PK & Swan, G 2014, 'The operational and laboratory aspects of a thin spray-on liner', in M Hudyma & Y Potvin (eds), Deep Mining 2014: Proceedings of the Seventh International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 241-251, https://doi.org/10.36487/ACG_rep/1410_14_Boeg-Jensen
(https://papers.acg.uwa.edu.au/p/1410_14_Boeg-Jensen/)
Abstract: Bolts, shotcrete and mesh are today a part of the standard ground support system, although it becomes economically challenging to combine them sufficiently to support seismically active ground that requires increased yielding and energy-absorbing capabilities. An enhancement to current ground support systems is the thin spray-on liner (TSL) that may possess significant yielding properties. TSL has the potential ability to support seismically active ground in terms of deformation and rock bursting, common in deep mining.
This paper describes part of an investigation, to prove whether the current formulation of a TSL called 3M polymeric composite membrane (PCM) could be implemented as an alternative ground support system or for improvement of the support capabilities for application in complex ground types. The paper delivers some conclusive operational and laboratory results that are expected to achieve this.
The trials examined the operational and laboratory aspects of the TSL. The paper focuses on the specific operational testing conducted at the Nickel Rim South Mine during 2012, together with the re-testing at MTI experimental mine and CANMET laboratory in 2013 that provided additional evidence. The health and safety aspects of TSL application are manageable due to robotic application and temporary shutting down of the local ventilation to prevent the dispersion of isocyanates. The test results available for the full composite liner material concluded that peel off at the leading edge next to the face blast, together with
fly-rock damage, was severe, due to primer adhesion failure and insufficient curing time, so this result was therefore considered to be a failure. The same test was performed on topcoat only, with significant improvement. The robot managed to apply the TSL with sufficient coverage and consistent thickness on the walls, except for the edges where the guns flip over and missed large perimeter patches, which was not dealt with till later in the testing. 3M took the effort back to the lab and produced three adhesive primers, while Asea Brown Boveri (ABB) refined the robotic application controls. Re-testing was completed in August and September 2013.
These results indicate the requirement of a rehab procedure for damage caused to the liner. In addition, bolting of the leading edge could be implemented to partially address the peeling issue. Liner adhesion failure may occur due to rock failure however the liner retains the loose material. The trial was done only on the rock walls; in order to make a fair judgment on the liner performance and capability it should in addition be applied on the shoulders and the back. Full proof of operational liner functionality requires underground deployment of a prototype mobile carrier.