Engineering & Mining Journal

APR 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 58 of 91

IN-PIT CRUSHING & CONVEYING APRIL 2018 • E&MJ 57 Commissioned in 2013, the conveyors have replaced numerous haul trucks that would otherwise be required, traveling many kilometers daily, half of the time empty, and burning diesel fuel around the clock. This system requires a vastly smaller labor force to operate and main- tain with the majority of service conduct- ed during pre-scheduled shut downs. The result is that getting the waste rock out of the way has caused very little impact to the planned production of the mine. Operation for the past four years has demonstrated both exceptional reliability and efficiency. Moving and Delivering Material Underground With near-surface orebodies diminish- ing, several existing open-pit mines have to adjust their approach to meet the changing requirements of an aging mine. For many, the alternative is clo- sure or pursuing the ore with under- ground mining techniques. In Indonesia, for example, an under- ground material handling system was recently commissioned to deliver 8,000 mt/h of primary crushed ore from a new block cave to existing mill facilities above ground. The project included six under- ground conveyors with a total length of 4,075 m and an overall vertical lift of approximately 500 m. The design, un- dertaken by TAKRAF's U.S. office, incor- porated 6,000 installed horsepower per conveyor flight. At full capacity, the mine operation is capable of processing up to 240,000 tons a day. Another significant project currently being undertaken by TAKRAF Germa- ny concerns the supply of a highly so- phisticated belt conveyor system for a critical underground project in Chile. A highly innovative belt conveyor scheme will overcome a number of technical challenges, including significant eleva- tion change from the underground mine to the surface, and will comprise steep uphill tunnel conveyors that transport copper ore from underground storage bins. The arrangement will include feeder conveyors as well as an overland conveyor feeding into an existing con- veying system. The conveyor system will employ state of the art gearless drive technology with the tunnel conveyors boasting the high- est power ever to be installed on a single belt conveyor. Gearless drives do not use a gearbox but only a variable speed motor having high torque throughout its speed range. With the challenges of limited space and accessibility and steep grades, the gearless solution is the main reason such a system can be achieved. The high power for each drive permits longer flights. Meanwhile, they have a smaller footprint and reduced maintenance and increased efficiency and reliability with- out a gearbox. Safety, as well as the ease and speed of maintenance are also critical success factors for operating high capacity con- veyors underground. TAKRAF has devel- oped an innovative solution that allows for regular chute maintenance to be con- ducted from the outside with no one hav- ing to enter into the chute. Another significant achievement will be the installation of the newly developed ST 10,000 steel cord belt on the tunnel conveyors. This will mark the world's first conveyor system to employ this highest rated steel cord belt technology. Addition- ally, with its 10,000-mt/h design capacity and total installed power of 55 MW, the system will include a complex cooling system to manage and dissipate the in- tense heat generated within the confined spaces underground. Basic information table of TAKRAF's waste material handling system in Mexico. TAKRAF's underground material handling system in Indonesia delivers 8,000 mt/h of primary crushed ore.

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