Engineering & Mining Journal

OCT 2017

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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CONVEYORS 62 E&MJ; • OCTOBER 2017 www.e-mj.com range in size up to 2.8 m in diameter and individually weigh up to 60 t. According to TAKRAF, the 39 pulleys had either been delivered, or were on their way, to the Chil- ean project site as of the end of August. Elsewhere, Rio Tinto has retained en- gineering consultant RCR to handle engi- neering, procurement and construction of a new primary crusher, 9 km of overland conveyor and associated 33-kV power line at its Silvergrass East iron ore mine in West- ern Australia. Fortescue Metals, another iron ore producer, recently announced that it was planning to install what it describes as "an innovative relocatable overland con- veyor" at its Cloudbreak mine in the Pilba- ra, as part of an innovation plan for 2018 that will also include acquisition of more autonomous trucks, as the company seeks to lower production costs. In Queensland, a BHP Billiton-Mit- subishi joint venture plans to spend $204 million to set up an overland conveyor sys- tem between two of its coal mines in the Bowen Basin. The Caval Ridge Southern Circuit (CRSC) project will include an 11- km overland conveyor system to transport coal from the group's Peak Downs mine to its coal handling preparation plant at the nearby Caval Ridge mine. The BHP Billiton Mitsubishi Alliance (BMA) said it has intended for some time to boost potential capacity by installing the conveyer system at the Caval Ridge mine, which currently produces 6 mil- lion mt/y. The CSRC project will increase the coal handling plant's throughput to 10-million-mt/y capacity, according to the company. Full production is expected to be achieved by 2019. In Guatemala, Doppelmayr successfully commissioned a RopeCon conveyor sys- tem to carry 2,100 t/h of limestone from a quarry to a processing plant operated by Guatemalan Cementos Progreso S. A. The installation, which requires only four tower structures, is approximately 1.6 km long and includes a vertical rise of almost 200 m. The long rope spans provided by the RopeCon technology made it possible to minimize the system's on-the-ground foot- print in densely wooded terrain. RopeCon, developed and designed by the Austrian company, combines the features of a belt conveyor with those of a ropeway, making use of the advantages of both technologies. BEUMER Group supplied and in- stalled a pipe conveyor for Transporta- dora Callao S.A., the logistics operator of a cargo terminal in the port of Callao, Peru, that enables the company to move zinc, copper and lead concentrates from a central storage site 3 km away from the terminal. The conveyor transports 2,300 t/h at a speed of 4.5 m/s, and is driven by three motors with a capacity of 650 kW each. "We equipped the system with filters, strippers, a dedusting unit and a control system," said Helmut Wolf, chief engineer on the project. BEUMER was responsible for engineering and automa- tion, and supplied the steel structure and all necessary components. And in British Columbia, Canada, a fea- sibility study update recently prepared for AuRico Metals' Kemess Underground proj- ect specifies underground crushing of ore at the proposed panel-caving operation, fol- lowed by transfer to one of two transfer con- veyors which will feed a 1,067-mm-wide conveyor belt that carries ore to surface. The 3.2-km underground conveyor will rise 305 m vertically and transfer ore to another 4.9-km surface conveyor that will drop 98 m vertically. Approximately 9 million mt/y of ore will be discharged onto a stockpile located at the existing Kemess South pro- cess plant site. Capital cost for the conveyor system is estimated at $30 million. Drives, Couplings Focus on Flexibility The capital costs of these systems are sig- nificant budget items by themselves, and CEMA (Conveyor Equipment Manufactur- ers Association), the U.S.-based trade as- sociation for conveyor equipment suppliers, estimates that annual maintenance costs for a belt conveyor typically total about 5% of the purchase cost of the belt, and 2% of the cost of the structure and equipment. An unplanned shutdown of a main convey- or link at a large mine can quickly rack up additional lost-production costs, in addi- tion to repair expenses, in the million-dollar range. To help customers avoid problems, suppliers maintain a steady stream of prod- uct and service improvements, along with technical guidelines, to keep conveyors running reliably and efficiently. For example, the mechanism used to transmit power to large conveyors has a direct impact on system simplicity and re- liability. Bosch Rexroth pointed out that its direct drives provide superior torque con- trol from standstill, enabling trouble-free starting with a loaded conveyor. The drives' precise pressure limitation prevents over- loading or straining of the conveyor struc- ture. The motor is installed directly on the pulley shaft without a gearbox, foundation or fluid coupling, which makes for a sim- ple drive solution that installs easily and saves valuable space around the pulley. Some of the main operational features of direct drives include torque control that protects the belt from overloads; soft starts and stops to keep belt stress to a mini- mum; the convenience of low speeds for belt inspection; and high-starting torque that can be maintained for an unlimited period of time. Bosch Rexroth noted that because the design of hydraulic direct drives is modular, it allows an optimal solution to be sized and tailored for any conveyor, small or large, from a few kilo- watts up to megawatts of installed power — and the original solution can be adjust- ed in the future if necessary. Hydraulic di- rect drives are easy to upgrade or adapt as needs change and develop over time. Last year, Voith unveiled its TurboBelt 500 TPXL fluid coupling — the first model in the new TPXL family, which combines the advantages of hydrodynamic drive prin- ciples with intelligent control technology. The integrated controller makes it possible to adapt the output torque of the coupling exactly to the startup parameters of the belt conveyor system. In addition, Voith said its engineers were able to significantly reduce the dimensions of the new coupling, so that the TurboBelt 500 TPXL only requires half the volume of conventional coupling types for the same force transmission. In addition Doppelmayr's RopeCon conveyor system minimizes the number of support towers needed for overland conveyors crossing rugged terrain.

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