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Overland conveying

2nd November 2018


Indentation rolling resistance (IRR) can comprise up to 60% of the total energy consumption
Increasingly longer conveyor systems and extreme environmental conditions mean that conveyor belt reliability is becoming extremely important
The ITA's text rig measures IRR
Several lengths of belt have to be spliced at site

Danny Slonka reports on conveyor belts and the solutions to make them durable enough for mining applications

Steel cord conveyor belts were introduced almost 70 years ago and since then have become the most economical and most environmentally friendly means of transporting bulk material over longer distances. Today, 100km-long multiple flight systems are in operation as well as almost 30km-long single flight systems. Belt breaking strengths up to 10,000N/mm are available. There are almost no limits if someone needs to haul bulk material from point A to point B.

This article describes the most important criteria for the design of overland conveyor belts. By applying those criteria, the overland conveyor system will be even more economical.

The most important criteria are the dynamic splice efficiency, taking the splice design and calculation as per DIN 22101 into consideration, and the use of energy-optimised conveyor belt bottom covers.

Energy-optimised conveyor belts

Conveyor belts are used for multiple purposes, having high efficiency and reliability. They provide one of the most economical forms of bulk material transport. Companies are placing a stronger emphasis on sustainability as well as environmental and climate protection. Energy consumption is becoming a more important factor in conveyor applications. Longer conveyors and higher production demands are driving engineers to seek new alternatives to reduce energy demand. Minimising the belts’ deformation while in contact with conveyor components such as idlers has become a high priority.

On long-distance systems the belt is running over a huge number of idlers resulting in deformation of the belt covers. The so-called indentation rolling resistance (IRR) is the predominant part of the main resistances and can represent up to 60% of the total energy consumption. Consequently, the IRR offers the most significant savings potential and has been a major focus in the past decade.

Due to a continuous development of the chemical composition of the rubber compound the IRR could be improved considerably. With the latest generation of energy-optimised conveyor belts it is possible to reduce the energy consumption by as much as some 20% compared to conventional conveyor belts.

The IRR is measured on a practical test rig at the Hannover Institute of Transport and Automation Technology (ITA) and it became a DIN standard in 2012. Meanwhile it has also been transformed into a European Standard (DIN EN 16974:2016 Conveyor belts - Indentation rolling resistance related to belt width - Requirements, testing).

Splice design and efficiency

Every belt has at least one splice and an overland conveyor system consists of several single lengths that have to be spliced at site, and therefore has numerous weak points by its nature. Since a splice is almost the weakest point of a conveyor belt it is obvious that they have to be done with the utmost care.

Most of the splices achieve a static breaking strength of roughly 100%, assuming they have been performed properly. However, more important is the dynamic splice strength in accordance with DIN 22110 part 3, since this parameter directly influences the required minimum belt breaking strength.

In general a higher dynamic splice efficiency, proven by the conveyor belt supplier and verified in accordance with DIN 22110 at the ITA, reduces the required minimum belt breaking strength.

It is obvious that just by taking a higher dynamic splice strength into consideration during the design stage, significant cost savings can be achieved. These include:

•    Lower conveyor belt breaking strength
•    Lower operating costs
•    Potentially smaller conveyor components, e.g. pulleys and idlers

To cope with the increasing requirements of the industry – conveying more material over longer distances, but at the same time focusing on cost and environmental aspects – steel cord conveyor belts from first-class manufacturers need to be considered.

In addition, for optimal protection of the steel cord conveyor belt, it is highly recommended to consider the latest monitoring equipment. The best manufacturers offer fully autonomous devices that continuously monitor the conveyor belt, 24/7, and use x-ray technology to detect all internal and external damage. These high-tech monitoring systems reduce both maintenance work and costs. Unscheduled shutdowns due to time-consuming repairs are prevented, which in turn avoids production losses.

For more information please visit Phoenix Convey Belts







 

 

 

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