Long reach

Conveying systems form the backbone of efficient production processes. Conveyor belts and conveying equipment are thus a central ­influencing factor for companies‘ competitiveness. To maintain their peak performance over the long term, regular maintenance is a must.

Whether in mining or general industry, conveyor belt systems (Fig. 1) nowadays form an integral part of both the raw material extraction and modern production. They optimize transport routes, make complex logistics processes more efficient and bridge short or medium distances for the transportation of goods. The demands on the conveyor belts concerned are many and high. As well as high levels of conveying performance and load-carrying capacity, factors such as low wear and maintenance costs and a high degree of production safety play an important role. Another main goal of the operators of conveyor systems is to have the conveyor belts run as efficiently as possible over a long service life and avoid downtimes to the greatest possible extent.

1 Flexible system solutions for companies

In addition, every industrial sector assesses the characteristics of the system differently. Conveyor belts in the raw materials industry, for example, need extremely high levels of tensile strength and operational safety as well as extreme resistance to wear to be able to cope with the load caused by the transported materials over long distances. To meet these differing operator requirements, custom-made and flexible system solutions are required that are matched to the particular location of the conveyor system, its type of use and the range of tasks involved. Flexible solutions for the construction of plant equipment therefore also require a flexible approach to the repair or maintenance of these systems (Fig. 2).

For conveyor systems used for raw material extraction, the belt and other components must be changed after a certain operating time. Conveyor systems used in opencast mining are exposed to particularly difficult conditions that affect the structure of the belt and thus limit its life expectancy. On the other hand, the extraction of natural resources, particularly in regions that are geographically exposed, has again become very lucrative. High demand from the industries of economically emerging nations, the resulting scarcity of certain resources and their increase in price are making conveying projects that were only a few years ago classed as unprofitable again attractive. In this case, the materials and equipment used are often exposed to extreme temperatures, higher levels of insolation or high humidity levels. With the help of specialists who have the necessary know-how and knowledge, professional maintenance and the trouble-free exchange of worn components such as conveyor belts, drive and redirector drums and carrier rollers can be guaranteed. Even large conveyor belts that run round the clock, are several kilometers long, or carry especially heavy materials, can be successfully exchanged using proven techniques and innovative approaches (Fig. 3).

2 Replacing the heaviest-duty conveyor belt in the world

An example of this is the replacement of two conveyor belts in the Chilean Los Pelambres copper ore mine, one of the most profitable copper mines in the world. This opencast mine lies in the Andes at a height of 3300 m. More than 8000 t/h of copper ore are transported for further processing at a height of 1600 m by means of steelcord conveyor belts. At times this means downhill transport gradients of up to 10 % for the conveyor belts. Together with the mine operator, REMA TIP TOP developed an approach which would allow the replacement of both conveyor belts without long plant downtimes, the goal being to keep production losses to a minimum during the maintenance work. “The normal method of changing a belt, making a splice and pulling it in roll by roll would have meant a downtime of over nine weeks”, explains Jan Severing, Reliability Engineer at ­REMA TIP TOP. “Taking into account the copper price of at least 6000 US$/t at the time, an immense production loss of around 250 000 US$/h threatened.”

To keep the production loss as low as possible, a ­REMA TIP TOP team of experts created a sophisticated technical solution that permitted both belts to be simultaneously exchanged in parallel with the running operation (Fig. 4). Both old belts were replaced by the new ones directly on site. In the first phase, half of the belt length was vulcanized together for each belt. The kilometer-long belt loops made in this way were positioned in pits made for this purpose and later attached to the existing belt. This process was then repeated for each second half of the belt.

A smooth sequence of events is decisive, particularly in critical phases such as this that directly affect the production operation. To ensure this, and taking into account the heavy weight of around 44 t per belt length and the length of the splice, 13 people were permanently assigned to each belt. By having the trained personnel operate in two shifts, and through the high degree of work efficiency and the use of state-of-the-art materials and tools, both conveyor belts – a total length of 23 km – could be simultaneously and successfully exchanged (Fig. 5).

In addition to the high requirements regarding quality and work protection, the efficiency of the work processes was also right at the top of the priority lists for this project. This meant that it was necessary to use tools and machines that were state of the art, above all for time-consuming work such as the rubbing down of cover plates, the stripping and brushing off the steelcord or the filling of steelcord interstices. Only the assembly of the vulcanization process – with 10 heating plates and 48 beams – could not be accelerated through the use of machines. Here the fitters were actually even faster than using a crane.

3 Conclusion

This example shows that for the maintenance of ­conveyor systems, flexible approaches tailored to the area of use are required. A relatively high work and materials effort in situations such as this can quickly provide a good return, because the production process remains unaffected by only undergoing short conveyor system downtimes that are fully under control. This example also makes clear the reach possessed by conveyors in both senses of the word – they are not only necessary for efficient transportation of materials from remote or inaccessible regions, but are also central transport arteries that keep global business alive and well.

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