In the future, mining companies will increasingly have to reduce their energy consumption and increase their systems’ reliability.
The drive systems of ore conveyor belts also have to be very robust so that they can transport heavy loads over long distances outdoors. Maintenance is therefore expensive and time-consuming. Gear maintenance alone can cost up to 5% of the original investment each year, so it makes sense to use gearless systems, which use slow motors instead of high-rpm drives with gearboxes. In the gearless systems, the rotors are flange-mounted directly onto the drive pulley. However, the investment in a gearless drive system only pays off if the system has an output of approximately 2.5 megawatts (MW) per drive pulley.
The first gearless drive system for the long distance transport of copper ore has now been commissioned by Siemens in Peru. The 3.8 MW drive is more reliable and efficient than the systems that are normally used to power conveyor belts, which combine motors and gearboxes. The copper mine in Antapaccay, Peru, is operated by the Australian company Xstrata Copper. Located in a mountainous region 4,200 metres above sea level, the conveyor belt will transport ore 6.5 kilometres from the mine to a processing facility.
The gearless drive system from Siemens in Antapaccay offers a wide range of benefits. For one thing, the motor’s size is no longer limited by that of the gearbox; as a result, operators can dispense with multi-motor drive systems. Only a single drive is needed to provide the required amount of drive output per belt drum. That makes it possible to design smaller distribution stations and reduce the overall weight. The elimination of a whole series of mechanical and electrical components substantially reduces the amount of maintenance needed. Gearless systems are also more reliable and less noisy than conventional drive solutions and have higher availability. In addition, the elimination of the gearbox increases the overall system’s efficiency by up to four percent. With a belt width of 1,370 millimetres and a speed of 6.2 metres per second, the conveyor belt can transport around 5,260 tons of material per hour.
Besides supplying the drive for the conveyor belt, Siemens is providing all of the switchgears and gearless drive systems for the Antapaccay mine’s three vertical mills.
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