Underground Mining

The drawing below applies to the room-and-pillar mining technique planned for at least a portion of the deposit at Bob Bay.  Maturi will require a different mining technique with a substantial “crown” pillar to guard against surface subsidence.

Schematic of Birch Lake Possible Underground Mining System

All of the mining and at least the primary crushing will take place 1600 to 2800 feet underground in a room-and-pillar bulk mining process.  Click on “mining level” to see the detailed drawings of how the ore is extracted.

Room and Pillar Mining Process

1. The ore body is an average thickness of about 25 yards and a fleet of jumbos, scalers, drills, loaders and trucks will be used to extract the dirt and rock according to a carefully drawn out plan.
2. As the ore is extracted, empty spaces or “rooms” will be left.
3. Multiple pillars of rock will temporarily support the roof as the mining progresses. 
4. Eventually, some of those pillars are removed and processed, as they contain valuable minerals,
5. Stabilized waste rock and tailings will be backfilled into the mine for structural strength and disposal.  There will be no surface subsidence.