Hard rock mining refers to various technique used to mine large ore bodies by creating huge underground "rooms" or stopes supported by surrounding pillars of standing rock. Terms for this include
- stope and pillar
- room and pillar
- longhole
- vertical crater retreat
- caving
Because of its high cost, hard rock mining is used primarily for mining valuable minerals such as gold and diamonds.
There are a number of mining methods that are used to extract the mineral bearing rock from the host rock. Typically some means of support is required in order to maintain that openings that are made by mining. This can be done by pillars which are then mined following the backfilling of the initial stopes.
Coarse ore is mucked out using gravity to help move it down rock raises or shafts to waiting trains of ore cars used to move it to the surface These trains can travel through long drifts or tunnels ending in portals to the mills on the surface. Ore is also moved in skip buckets hauled up shafts and emptied into bins beneath surface headframe towers for transport to the mill.
In some cases these stopes become exposed to the surface and become open pits.
Trivia
The deepest hard rock mine in North America is a nickel mine in Sudbury, Ontario.
See also