Oil shale is extracted by opencast mining in the Narva quarry and by underground mining in the Estonia mine.
n places where the oil shale stratum is not very deep below the surface, oil shale is mined in quarries, which can extract oil shale from depths of up to 30 metres.
If the oil shale stratum lies more than 30 metres below the ground, it has to be extracted in an underground mine, so mining chambers must be dug and supported, and transport systems built to get the mined rock to the surface.
The enrichment process for oil shale removes limestone from the raw mix of oil shale and limestone produced by mining. Enriched oil shale has a much higher calorific value than does a raw oil shale mix.
Investments in mining (million euros)
Eesti Energia Mining is continually investing in increasing production efficiency.
Oil shale production of Eesti Energia (thousands of tonnes)
The maximum amount of oil shale that it is permitted to mine in Estonia is 20 million tonnes per year.