How coal is mined in OKD

Rock bounces

Důlní otřesySeismic bumps are an inseparable part of coal mining. They are the result of energy releases in the mass of rock from the creation of empty underground spaces. The rock is stressed by the extraction of ore, pressure is created in it and energy is accumulated, which can be released in an instant by a rockfall. Bumps and slides occur mainly in saddle seams, where there is solid overlying rock. Many bumps occur but only some of them end up destroying mine workings.

Although miners throughout the world strive to anticipate tragedies, bumps can only seldom be foreseen (as is the case with earthquakes). In 1975 OKD declared the anti-bump fight and since then considerable funds have been invested (hundreds of millions of Czech crowns a year) into the prevention of shock bumps. For the monitoring of bumps the company has a special measuring network operated by its subsidiary OKD, DPB, a. s. in Paskov.

Using special apparatus, the experts methodically examine the bumps, monitor the rock properties and pressure development and search for superior prognostic methods. The company tries to release the pressure in the hanging walls by means of drill-holes and partial blast-firing.