Engineering & Mining Journal

DEC 2012

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GROUND CONTROL working environments. The challenge for operations is that as they need to mine deeper, transport costs play a key part in system-installation costs. This is where TSLs have a major advantage, with only one-tenth of the materialshandling needed." What becomes clear from this discussion is that in the future, deeper mines will become increasingly reliant on a combination of techniques for their ground-support needs. Each of the systems outlined here has its own place, strengths and shortcomings. With rock conditions varying from heading to heading, as well as from level to level, mines will need to make site-specific choices; there is no 'one-size-fits-all' answer when personnel safety is involved. Rockbolting in one of its many forms will doubtlessly continue to form the front line, either alone or together with meshing. Cable-bolting extends this capability deeper into the rock mass. Shotcreting—either plain or reinforced— requires a better-developed delivery infrastructure, but offers long-term stability so long as ground movements are limited in extent. TSLs are quick to install and offer good spall resistance, but do not have the shotcrete's structural capacity. Each operation must find its own optimum support solution. The Responders in Profile DSI has a long history in ground control and is among the leading ground-control systems providers in Australia and North America. In the U.S. market, DSI Underground Systems claims to be the leader in hard rock product sales, with a range that includes steel, resin, cables, composites, standing steel supports, backfills and other widely used ground-control methods. BASF has a strong foundation in concrete technology, and was one of the early proponents of sprayed concrete. Through collaboration with the mining industry, this is now widely accepted as a very successful means of ground support. The company's ground-consolidation interests today encompass the injection of fractured strata, cavity filling, water-ingress control, and supplying high-performance grouts for rock anchors. Minova's TSL range consists of two product types. The traditional Tekflex type is a flexible TSL system that is available as either a two-component liquid/powder or a single component drysprayed version. The second type, Capcem, is a rigid TSL material that is extensively used for rock weathering protection in South African mines. Spray On Plastics, with 20 years' experience in the development of TSLs, has patented what it claims is a unique way of spraying polyurea coatings by creating polymer strings or 'webs.' It says that these plastic fibers reach and stretch around obstructions before melting back together to form a resilient structural membrane. It now has two RockWeb products, one for general areas like drifts and pillars, and the other designed for remote spraying in large boreholes—developed as an emergency support system for the Chilean mine rescue in 2010 in the event of unravelling in the boreholes. www.e-mj.com DECEMBER 2012 • E&MJ; 53

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