Complex sentence: The Narva open-pit mine, operated by Eesti Energia Kaevandused, uses surface mining technology of stripping with relatively big bucket (10--35 cubic meters) excavators.
Split into simpler sentences: The Narva open-pit mine, operated by Eesti Energia Kaevandused, uses surface mining technology. The rock is stripped with relatively large-bucket (10--35 cubic meters) excavators.