Engineering & Mining Journal

JUL 2018

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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Page 49 of 75

SHOTCRETE 48 E&MJ • JULY 2018 Shotcrete plays a crucial role under- ground. It's performance, as far as ground support, can be affected by many factors. The operators on shotcreting machines strive for a consistent thickness, but it's a subjective process at best. There are the site-specific parameters, such as geology and the ambient conditions underground, which affect how well the mixture ad- heres and cures. Then there's the ingredi- ents that make up the shotcrete and how well they are mixed and delivered. With more miners pursuing ore at depth, it's also important to remember that shotcreting systems can also affect the rate of development. If some shafts and tunnels are not lined quickly, the rock begins to deteriorate. Slow shotcret- ing systems that generate a lot of dust or waste can hinder development rates. Reducing the time it takes to line an ore pass, shaft or tunnel, will only improve development rates. The world's largest underground oper- ations have extensive shotcreting opera- tions and the industry could learn from their experience. New mixtures and ap- plication systems have been introduced, which are also saving mines time and money. Looking toward the future, re- searchers are already looking at ways to digitalize this process, much like many of the other mining processes. Rapid Development for Mass Mining A significant portion of the future copper supply is scheduled to come from large, underground, block and sublevel cave operations, currently in development or planning stage, including the Grasberg Block Cave (GBC) in Indonesia, Oyu Tol- goi in Mongolia, Wafi Golpu in Papua New Guinea, and Chuquicamata in Chile. These projects will all have ore throughput rates of around 100,000 metric tons per day or greater and, to provide the support infrastructure and the footprint for such outputs, rapid mine development is criti- cal to source ore from a first drawpoint in time. Two key projects have laid the basics for such underground, mass-mining tech- niques and have provided many lessons for projects to follow, according to Sika. Codelco's El Teniente mine in Chile and LKAB's Kiruna mine in Sweden pro- vide some of the best demonstrated prac- Better Shotcrete Mixtures and Robotics Allow Rapid Development Several suppliers and service providers are looking at new ways to consistently apply shotcrete safely and quickly By Steve Fiscor, Editor Today, technologies are being used for fast, early-strength shotcrete liners that allow for the safe re-entry within a short period. (Photo: Sika)

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