Falls of ground (FOG) still account for around 35 percent of all fatalities in undergroundmines, and to reduce FOG, appropriate support technology needs to be implemented.
A shift in mindset and culture will see the reduction of stoppages due to FOG, which are very costly.
In underground mining operations, the use of temporary support components offers some protection to workers while permanent and generally more elaborate support systems are installed or constructed.
The mining industry has adopted underground support technologies in order to reduce safety risks and enhance productivity, for instance coal mining has adopted leading technologies over the years, Platinum and chrome mines have also shown significant moves towards adopting leading and appropriate support technologies, seeing noteworthy changes in injury statistics for better.
Underground Support Principles in coal mines
Some of the support technologies that have been adopted in coal mines includes the use of full-column resin capsule steel bolting with fast and slow setting resin in the hole, which allows for an immediately tensioned bolt. The bolter is removed from the bolt position once installation is completed. Further improvements in full-column resin bolting currently implemented are spin-to-stall resin technology along with two-speed resin capsule and bolt installations.
Underground Support Principles in Hard Rock Platinum Mines
Different mine methods applied in platinum mines has resulted in the use of a wide variety of support systems. Mechanized mining operations tend to use resin bolting, but other support items are also used. Various elongated timber support types are used as well as a combination of timber and continuous grout packs.
Underground Support Systems in Gold Mines
Gold mines are generally lagging in the adoption of leading and appropriate support technologies, especially for in-stope support. Hence, very limited in-stope bolting is practised in gold mines, because of friable hanging wall conditions, hanging wall closure rates and perhaps the higher rock stresses due depth.
Underground Support Regimes: Various Steel Bolts
The resin Steel bolt with a resin grout consists of a deformed bar stud, nut, and bearing plate. The bolt is grouted using resin capsules. Cementitious grouting of various types of steel bolts is commonly used in development ends in hard-rock mines. The quality and setting times of the cementitious grouting can vary greatly.
In addition, long anchors of various types, lengths, strengths, and diameters are used for different and special applications. Friction bolts are also used, and these include Split sets, Hydrabolts, Swellex, and end- anchored mechanical shell bolts.
However, the industry continues to evolve and grow, with a number of companies spending more of their resources on intensive research and developing programmes that generate innovative support solutions and a range of products, accessories and applications that are developed to meet specific customer requirements and applications.
Innovative new anchoring technology and dynamic test facility
Mine Support Products (MSP) continues to consolidate on its reputation for being a leading manufacturer and supplier of underground support systems, following the launch of the company’s new hydraulically set anchoring device, Rocbolt, to the Southern African market in mid-2013.
MSP marketing manager Ivan Jacobs highlights the fact that the Rocbolt is unique in that it is a friction bolt with the capabilities of an end anchor, thanks to a patented friction ring that fits around its shaped tube. He reveals that the Rocbolt has been tested at a number of underground mining operations in Zambia and South Africa with successful results.
“During the trial periods in varying regions and conditions, all of the MSP Rocbolt devices were able to withstand loads in excess of 10 tons, which exceeds the industry requirement. The mining operations have subsequently provided us with positive feedback, and I am confident that the Rocbolt will gain measurable market share moving forward,” he explains.
Another unique aspect that sets MSP apart from the competition is the fact that it is the only underground support systems manufacturer in Africa that boasts its own purpose built press that has the capability to test both the static and dynamic capabilities of support units. The press located onsite at its 5,500 m2 manufacturing plant in Vereeniging, and can test at static loads of up to 100 tons and dynamic loads of 40 tons at 3 meters per second.
As a specialist in the manufacture of innovative underground support systems for the mining industry, MSP’s flagship product is the unique Rocprop roof-support system. Jacobs indicates that the Rocprop MK1 model was originally designed by MSP in 1994 for deep level gold mines in tabular ore bodies, with mining widths of up to 6 m.
“Rocprop MK1 is an all-steel elongated support system with predictable and consistent performance that caters for static and dynamic loading conditions. Rocprop MK2, which is a smaller version of the original Rocprop MK1, provides a more cost-effective solution for shorter length support system requirements of up to 2, 1 m,” he adds.
Under static loading conditions, both Rocprop models are able to sustain constant load bearing characteristics during blasting, while maintaining the integrity of the hanging roof after closure. By providing a constant resistance, Jacobs notes that Rocprop devices securely hold key blocks in place in seismically active mines, and in static conditions.
He continues: “Both Rocprop models are easy to transport and install, and their slender design ensures that they do not restrict underground ventilation in any way whatsoever. The Rocprop support system has proven to be particularly successful within the coal-mining environment, where it offers a viable solution for systematic roadway support, belt drive support and long wall moves.”
According to Jacobs, Rocprop also ensures a substantial reduction in material handling costs, while improving installation times too. “This innovation and versatility has opened up new avenues of growth for MSP, particular in soft rock conditions, where Rocprop is being increasingly recognised as a more effective replacement to timber packs.”
The Enerflow ACU fits into a standard mine cage with two layout configurations available, and can be easily moved as mining activities expand. The vapour compression cycle – made up of the compressor, air evaporator and water condenser – are housed within a mobile modular unit that can be mounted on a tracked unit or with its own wheel-mounted undercarriage.
MSP is also renowned for its unique Terra Drill in-stope drilling rig that adheres to all industry standards and safety regulations. The lightweight, low maintenance MSP Terra Drill boasts outstanding features such as; stabilised remote drilling, manoeuvrability, various models/lengths and compatibility with underground drilling machines.
Jacobs has identified Africa as a region with the potential for growth for MSP. “The mining industry continues to develop at a rapid rate, thanks to a steady rise in investment. As more underground projects are established and existing ones are upgraded, mining houses will be seeking support systems that ensure that the highest standards of quality and safety are maintained in a cost effective manner. MSP is able to meet these requirements through its product offering, and I am confident of sustained long term growth throughout Southern Africa and beyond,” he concludes.
