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Karviná miners' unique feat: they recrossed a previously backfilled shaft

Karviná miners' unique feat: they recrossed a previously backfilled shaft

Doubrava (30 October 2008) – At Karviná Mine, owned by OKD Coal Mining Corporation, the miners pulled off a technical operation amounting to a rare unique feat at the depth of nearly 700 meters underground. They managed to pass across the backfilled Doubrava shaft, of 7.5 meters in diameter, whereupon they were able to resume coal extraction work. According to available information, this was the first ever project of this kind not only in the Czech Republic but in Europe.

 

In the past, any such old vertical mine workings had to be bypassed by the advancing mine gangs. The working face had to stop when similar obstacles were encountered. The miners drove new galleries around the shaft and moved mining machinery beyond a protective pillar. Only then could coal extraction work be resumed. „That amounted to a loss of the coal reserves adjacent to the shaft, plus a production delay to the tune of about one month. Now we have managed it all within several days' time,“ said Pavel Hadrava, the Mine Director.

 

It took three days to actually effect the passage across the shaft. First of all, specialists drilled several bores to check on the condition of the cement/flyash backfill within the shaft interior, and then the section to be crossed was strengthened using a fan-like structure of thirteen-meter steel bars, which were further reinforced using appropriate technologies. Thanks to this, the crossing proper of the shaft proceeded without any hitch.

 

The implementation team had been making ready for this untraditional project since April. „We had to elaborate all pertinent technical and safety measures in detail. All plans were consulted with the District Mining Authority in Ostrava, which approved the method we proposed,“ Hadrava added.

 

Karviná Mine is one of the four mines owned by OKD Corporation. It was constituted in the spring this year, by an administrative merger of Lazy Mine and ČSA Mine, which had been joined together even before through their underground networks. Now the two Works operate under the same management, affording a higher productivity to OKD Corporation while the miners have benefited, among other things, by shortened commuting routes to work and by simpler transportation to some of the underground workplaces.

 

OKD Corporation is owned by New World Resources N. V. of the Netherlands.

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