SPECIALIST EQUIPMENT
installation without additional borehole sealing. A considerable challenge – and one that not every system has overcome – is how to ensure that the resins are stable and perform uniformly at diff erent temperatures. Pumpable resins can be used with cable bolts, as well as with hollow bolts or self-drilling anchors. Open times can be adjusted to suit the application and the resins can be adjusted to work at a range of temperatures from 5°C upwards.
FASTER CYCLES T e speed at which the use of these new resins is spreading demonstrates how eff ective they are. Following extensive fi eld trials on surface and underground, the MasterRoc RBA 38X series was deployed commercially for the fi rst time in 2019. Today the resin is being used in major mine development projects. In less stable ground, the immediate
benefi ts of the resin system are apparent: installation times for cartridges can take 10 or 15 minutes, whereas a self-drilling bolt combined with pumpable resin takes 2.5 to 3 minutes. Although cycle times in good ground are similar for either
polyester cartridges or pumpable resins, some mines are fi nding that it makes sense to use pumpable resins throughout because there is no need to switch between systems if the rock quality falls. T ere are longer-term benefi ts of using pumpable resin too: it penetrates cracks and fracture zones around the bolt, consolidating the ground and increasing its stability. In fact, the polyurea silicate resins used in the MasterRoc RBA 38X series were developed from those used in rock consolidation. Larger-than-planned borehole diameters do not create potential problems with this system as the resin can be pumped until the hole is completely full.
Given that the cost to refurbish a tunnel is three-to-fi ve times the cost to build it originally, improved rock stability and fewer bolt failures over the life of the facility mean lower lifetime costs for the mine.
ADAPTATIONS Switching to pumpable resins requires new or modifi ed equipment. Rigs with built-in systems for pumpable resin have come onto the market in the past 12
months. For some existing equipment fi eld trials have demonstrated that retrofi t kits work well, at a fraction of the cost of a new machine. As with any new operation, mining
operatives will require advice and training as they start to work with pumpable resins. However, systems such as MasterRoc RBA 38X have been designed to be easy to use, and reports that workers prefer to work with the pumpable resin rather than with the cartridges confi rm this.
As well as being easier to work with, pumpable resin is safer too, because there is no need to approach the rock face to install a cartridge. Everything can be done by the boom of the rig, with the operator positioned behind the boom in the cabin of the machine. In an environment where mine operators are looking for more automation to improve safety, this system off ers another considerable benefi t.
Uwe Wyink is global technical manager at BASF.
www.ugc.basf.com
EQUIPMENT
SERVICE
CONSTRUCTION CHEMICALS
ROCK REINFORCEMENT
UNDERGROUND EXPERTISE PROJECT SUCCESS BEGINS AT THE BEGINNING
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EQUIPMENT SERVICE CONSTRUCTION CHEMICALS NOR_180319_International Mining Engineer - May
2018_w185xh121.indd 1 ROCK REINFORCEMENT
NORMET.COM 19.3.2018 18:24:06
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