One-step installation of rock bolts, a joint venture to improve productivity and safety in rock bolting
Michael Hosp, Minova MAI GmbH
Minova and Epiroc have engaged in a joint project to develop a solution for the installation of rock bolts in a one-step operation. Epiroc as producer of rock bolting machines (BOLTEC series) has developed a fully integrated solution for the handling of resin and rock bolts on their rig, whereas Minova developed suitable rock bolts, a customised resin solution and contributed with its long-term experience in resin pumping technology. One-step in this context is to be understood as a system comprising a hollow bar and bulk resin. The hollow bar is equipped with a sacrificial drill bit and is used as the drill string and as the rock bolt at the same time. The bulk resin is a two-component silicate resin. Within the project, solutions for high convergences and for application in dynamic conditions were developed and successfully tested in laboratories and in-situ. The bolts for converging ground can yield for 200 mm and above, the dynamic versions withstand dynamic requirements of major mining companies. Epiroc has developed an on-board system to store, pump and mix the bulk resin in a fully controlled system. The key parameters of the installation process such as drilling time, resin volume and injection pressure are logged and recorded as a basis for quality control of the bolt installation. The system was tested extensively in LKAB´s Malmberget mine with a focus to expose it to the worst possible conditions in terms of rock hardness, cracks, voids and collapsing boreholes. Significant improvements in productivity and safety could be proven and the durability and reliability of the system were confirmed. The paper will detail the development of the bolt and resin derivatives and their implementation within the large-scale field trial at LKAB, which formed part of of the wider ranging European Union funded SIMS (Sustainable Intelligent MiningSystems) project.
Rock bolting, rock bolts, 1Step, Epiroc, Minova,