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GROUND CONTROL technology that they envisage will be able to help mining companies operate safely at greater depths. Hage: "Mines getting deeper will lead to more heat and deformation. To tackle these challenges, more developed and flexible mechanization will be necessary, as well as improved logistics. Optional technologies such as fast-setting sprayable polymer membranes provide effective surface support and protection against weathering of rock and strata, which are important for the safety and efficiency of a mine." He went on to quote one of his colleagues, Warren Mahoney, market manager for ground support at BASF Australia. "Faster setting sprayed concrete accelerators in the initial 1- to 2hour period after spraying, and real-time thickness control during the application of sprayed concrete will help mining. More consideration should also be given to the use of resin injection for very badly fractured ground. This technology has an extremely fast setting time for bonding strata with minimal downtime," Mahoney said. Macpherson: "Generally, operations interested in using RockWeb are experi- encing unravelling ground or high convergence. Though it cannot stop the convergence (due to its flexibility) when applied underneath a stiffer support like bolts and screen, the unravelling of broken ground can be reduced as the smaller pieces cannot be dislodged from between key blocks." He added that while this can also be achieved using shotcrete, shotcrete tends to break in squeezing ground, allowing the unravelling to continue. Macpherson went on to look at logistics issues. "As mining operations reach greater and greater depths, the challenges of moving materials like shotcrete increase. RockWeb was used in a cone sump application at a depth of 9,300 feet because the mine was unable to move shotcrete to the level via two shafts fast enough to complete the job economically or on time. The RockWeb materials and equipment were sent to the level in two cage runs," he said. Minova: Harker agreed, "The key is to develop technology that reduces handling, both in terms of transportation to the mine heading but also in terms of site application. Minova's development focus is on technologies that will lend themselves to automated installation." Inventing a Sticky Solution Wire mesh has long been used to provide coverage of roofs and sidewalls, catching spalled rock before it falls and—if it is installed correctly and pinned in place with rockbolts—providing additional support to the rock mass. However, as anyone will know, who has ever had the challenge of handling it, and trying to ensure that the mesh conforms closely to the rock surface, it is not the world's easiest material to work with. As a result, all too often the job is not done properly, and the support provided is not as good as it could be. Improved accuracy and speed of installation are just two of the benefits to be gained by using a synthetic support grid instead of wire mesh, which can be heavy and unyielding, says U.S.-based Convenience Products. The company has teamed up with Tensar International Corp., manufacturer of TriAx TX Geogrid, an extruded and stretched polymeric grid that can be used in roof and sidewall installations. Made from lightweight, high-strength, corrosion-resistant polymers, Tensar reports that TriAx TX is equivalent to 10-gauge weldmesh, coming in rolls that can be installed using roofbolters, miner-bolters or jumbos. "Polymeric rolled grids are much safer and easier to handle, transport and install than metal screens," said the company's sector manager, John Steffenino. "For years, everyone has tried to install rolled mesh without the use of holding brackets." What was needed, however, was a method of holding the grid in its rolled configuration with just the right amount of resistance to allow it to be pulled apart when the roll was unwound during www.e-mj.com DSI: DSI has been engaged in the development of a full dynamic bolting product line for the past three years. These products include dynamic steel bolts/resin assist, dynamic cable/resin assist, and dynamic mesh that have all been tested and rated. This work has been completed in Canada and Australia to prepare products that will allow mining companies to work safely and productively at greater depths. Each of the respondents also addressed the ever-present question of finding sufficient skilled labor to install their systems safely and effectively. From Minova's perspective, Harker told E&MJ; that the company does not just focus on the development of products, but has a systems approach to development. "With this in mind, we aim to provide the tools needed for ease of installation, regardless of labor force skills," he said. "Having enough skilled personnel will always be an issue, particularly in booming economies," said Hage. "Provided there is a good level of skilled supervision and training incentives in place, this will go a long way to support adequate levels of conformity when installing these systems." installation, according to Steffenino, who approached Convenience Products to see if its Touch 'n Seal Mine Foam would provide an answer. This led to the development of a patent-pending process known as 'resistive unrolling,' the companies report. The Mine Foam is strong enough to prevent rolls of grid material from unwinding under their own weight, yet allows them to be pulled apart in a controlled manner while keeping the remainder of the roll intact. Resistive unrolling keeps the untensioned grid under better control during installation. DECEMBER 2012 • E&MJ; 51