How is oil shale mined?

When the oil shale layer is closer than 30 metres below ground level, we mine it in an opencast mine, and when it is deeper, we use underground mining methods. Eesti Energia operates two mines: The Narva opencast mine and the Estonia underground mine.

Innovation under the ground

In the exhausted room blocks of the Estonia mine, we have established an underground sediment pool and pumping station that are unique internationally and help reduce the environmental effects of mining. Owing to the large size of the sediment pool, the settlement time of suspended solids is longer and the quality of the water led to the surface is better. The underground pool also makes it unnecessary to establish a sediment pool on the ground surface – in a forest or field area. Besides, the maintenance and operating costs are lower for an underground sediment pool. In addition to the new underground sediment pool, the Estonia mine uses five sediment pools on ground level.

Oil shale reserves

Depending on estimated usable oil shale reserves and the speed that the oil shale is used, Estonia will have mineable oil shale for at least another 50 years. In order to ensure the longevity of oil shale resources, we develop new mining development projects and new technologies that enable mining at minimum losses.

Estonia will have mineable oil shale for at least another 50 years.

Sustainable use of resources

As the oil shale layers in the ground alternate with layers of limestone, the latter has to be sorted and removed before the oil shale can be used for energy production. This process is called the enrichment of oil shale. We are looking for new uses for the enrichment residue – waste rock. A broader use of crushed waste rock would increase the added value of the oil shale industry, as it would be an environment-friendly alternative to waste rock heaps. Processed or unprocessed waste rock can be used for the construction of roads, cycle and pedestrian tracks, forest paths, city squares and parking lots and for landscape design.

We regularly restore the mined areas – either by planting forests, turning the areas into fields or finding new uses in order to return the land to the natural and living environment.

More efficient mining methods

Along the north-eastern edge of the Estonia mine, we re-employed the longwall technology that is more cost-efficient than the traditional room-and-pillar mining. This method also uses pillars, but mining takes place simultaneously on a section that is many times longer – nearly 700 m. We continue to use the room-and-pillar method elsewhere on the territory of the Estonia mine.