An overview of underground mining methods, its importance in the mining industry, and the factors influencing the choice of underground mining over surface mining.
Introduction to Underground Mining
Key concepts, methods, and considerations for extracting mineral resources below the earth’s surface.
| Aspect | Description |
|---|---|
| Definition | Extraction of ore deposits located beneath the ground surface, using tunnels, shafts, and chambers. |
| Purpose | Access high‑grade or deep‑lying ore bodies that are uneconomical to mine by open‑pit methods. |
| Typical Products | Coal, gold, copper, zinc, nickel, diamonds, rare earth elements, and many other metals and minerals. |
| Depth Range | Usually > 100 m (330 ft) below ground; can exceed several kilometers for deep‑level operations. |
| Advantages | Disadvantages |
|---|---|
| • Lower surface disturbance → smaller land footprint. | • Higher capital cost for development (shafts, ventilation, safety systems). |
| • Ability to target high‑grade zones → better ore recovery. | • Increased safety hazards (rock falls, gas, fire). |
| • Reduced overburden removal → less waste rock. | • Complex logistics for personnel, equipment, and ore transport. |
| • Can operate in rugged terrain where open‑pit is impossible. | • Greater energy consumption for ventilation and de‑watering. |
| Method | Typical Use | Key Features |
|---|---|---|
| Room‑and‑Pillar | Flat‑lying, tabular deposits (e.g., coal, potash). | • Large “rooms” mined, leaving pillars for support. • Pillars may be partially or fully reclaimed (retreat mining). |
| Longwall Mining | Thick, continuous coal seams. | • Mechanized shearer cuts a long wall; hydraulic roof supports advance with the face. • High productivity, high recovery (> 80 %). |
| Cut‑and‑Fill | Irregular ore bodies, steep dips. | • Ore is removed in slices; each slice is back‑filled with waste rock or cemented paste to provide support. |
| Block Caving | Massive, low‑grade ore bodies at depth. | • Induced fracturing and caving of a large block; broken ore flows by gravity to drawpoints. |
| Sublevel Stoping | Medium‑to‑high‑grade, steeply dipping ore. | • Drilling from sublevels, blasting creates a “stop” (hanging wall) that is removed. |
| Shrinkage Stoping | High‑grade, steep ore bodies. | • Broken ore is left in the stope to provide temporary support; later removed. |
| Raise‑boring & Drilling | Access creation, ventilation shafts. | • Large‑diameter holes bored upward from a lower level, then reamed to size. |
Selection depends on ore geometry, depth, rock mechanics, safety, and economics.
Access Infrastructure
Ground Support Systems
Material Handling