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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SHOTCRETE 50 E&MJ • JULY 2018 crete in place," Loevlie said. "That's a big improvement when it comes to raise bor- ing or shaft lining." STI has two different shaft-lining ro- bots. A pneumatic centrifugal shaftlining system sprays 0.5- to 3.5-m inside diam- eters (ID). An electric/hydraulic double nozzle system sprays 3.5-m to 25-ft ID. Making the mix pumpable is key when pumping shotcrete 400 m down a verti- cal shaft using 2-in. shotcrete hoses to place up to 10,000 psi fi ber-reinforced shotcrete in place. "This shotcrete includes amorphous pozzolan, which maintains moisture long after portland cement has dried out and started the deteriorating process," Loevlie said. "The pozzolan makes the mix less permeable, more cohesive and provides the means to place a higher quality shot- crete in place. This instant lining during and after raise boring operation will help increase the time vent raises, ore passes, etc., can be put to use, saving time and money." STI is also developing compact sys- tems for use in underground ore passes and development work. These systems have been designed so that they can be mounted on a pickup truck or carried with a skid-steer loader, which includes a winch, a small grout/concrete pump, a grout/concrete mixer and sand/cement – prebagged or supersacks 0.5-cm more or less. This is how shaftlining can be done without depending on or interfering with production in the mine operations. Researchers at RWTH Aachen University's Institute of Advanced Mining Technologies (AMT) are investigating methods of digitalizing the shotcreting process.

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