River diverted at surface mine
When managers at Kolubara, Serbia’s largest coal mine, began talking about widening their operations, they immediately ran into a rather large snag – there was a river in the way.
“The kolubara coal basin comprises an eastern and western part, divided by the Kolubara river,” explains Ivan Kovac, marketing manager of Hidrotehnika-Hidroenergetika, the Serbian civil engineering construction company in charge of the expansion project.
The eastern part of the basin, which represents 20 percent of the mine’s total productive surface, covers about 120km2, but much of the area has long since been exhausted.
However, the western part of the basin – spanning 480km2 – at the opposite side of the river, remains unexploited. With its four
open-cast pits and 26million tonnes of annual production, the Kolubara mine (located some 40kilometres southwest of Belgrade) supplies coal to several large thermal plants situated in the close vicinity, so finding a quick, reliable solution was vita.
“There is enough coal across the water to satisfy Serbia’s needs for decades to come,” enthuses Kovac. “But first, we have to get there!”
Hidrotehnika-Hidroenergetika issued a tender for a solution to the problem and against stiff international opposition, Trelleborg was chosen.
“Rather than try to dig under the river, it was decided to divert it eastwards, into the already workedout areas,” explains Neboj¨sa Miletic, managing director of Neshvyl Ltd, which represents Trelleborg in Serbia and Montenegro, Bosnia and Macedonia. “But because of the instability of the soil underneath we needed to line parts of the five kilometre long riverbed with a material that would ensure that the movement in the underlying soil would be absorbed”. The answer? Trelleborg’s EPDM rubber membrane.
Phase1 of the project was finished by the end of 2006 with further diversions planned over the coming few years.
EPDM (Ethylene Propylene Diene Monomer) is a synthetic rubber whose balance of physical properties and chemical resistance make it suitable for a wide variety of rubber applications.
The membranes are laminated with a thin layer of thermoplastic elastomer, a thermoplastic olefine that has many of the characteristics of vulcanised rubber, and then spliced using a new, patented splicing technique – Thermobond – whereby the seams are produced with a hot wedge in the form of two parallel welds with an air channel between them which enables the joins to be tested using compressed air.
For more information, visit www.trelleborg.com
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