Christian Schorr-Golsong reveals how mining ropes on a friction winch are setting new standards for durability
One expert in the field of mining ropes is proudly showcasing its latest feat; a new world record. This impressive case study comes from Australia’s Northparkes mine.
After 652,239 completed cycles, a service life of 46 months and more than 22 million tons of moved rock, the Turboplast M used for the work was gracefully retired. The rope was discarded according to plan in mid-January 2015 under the supervision of Roger Smith, an expert for high- tech mining ropes in the service of Casar, and Alexander Fäh, sales engineer for mining ropes.
The Northparkes mine is located in a rural area of the state of New South Wales, around 450km to the west of Sydney. Gold and high- quality copper concentrate are mined and extracted in the mine. The hoisting machine is a ground-mounted friction winder with a motor power of 3MW, which transports a maximum payload of 16.5t at a speed of 15.3m/s from a depth of 590m to the top. Four hoist ropes with a diameter of 32mm and a length of 750m are used, two ropes right hand Lang’s lay and two ropes left hand Lang’s lay.
When underground mining began in 1997, the triangular strand ropes that were used reached a service life of around 100,000 working cycles.
The rotation-free 19x7 hoist ropes that were subsequently used only had a very short service life so that the first set of Casar ropes was used in 2000. This set increased the service life to 245,000 cycles and only had to be discarded due to mechanical damage caused by rockfall. The following change to a competitor caused nothing but problems and left the mine with a short rope service life, which is why the company went back to Casar.
Since the return, three additional sets of ropes have been used, and with each set it was possible to increase the service life further.
With the fourth set, Casar managed to increase its own world record of 485,300 cycles on a friction winch, which it had in fact only broken with the third set, to an incredible 652,239 cycles.
This performance ought to be rated even higher as important parameters such as speed, payload, acceleration and utilisation were increased over time, while maintenance measures were reduced. Normally all this would rather lead to a reduced service life.
However, with an intensive examination of the discarded ropes and a comprehensive study of the relevant damage mechanisms, Casar managed to continuously develop the rope for Northparkes, successfully managing to prevent the rope reaching discard maturity prematurely.
When the rope was changed in January 2015, again a Turboplast M was installed to confirm its world record performance. In the long term the mine operator hopes to exceed this record again, aiming for a service life of 800,000 cycles. This should be achieved by using Turboplast MF for the sixth set of Casar ropes, which will be even better adapted to the requirements and circumstances on a friction winder.
Christian Schorr-Golsong is with Casar.