In mining engineering, a drift is a specific type of underground passageway. It is defined as a near-horizontal passageway in a mine, following the bed (of coal, for instance) or vein of ore.
Understanding a Mining Drift
Based on the general mining term definition, a drift is essentially a tunnel excavated underground with a particular purpose and orientation:
- Near-Horizontal: The passage is not significantly inclined.
- Follows the Deposit: A key characteristic is that a drift is driven along the actual mineral deposit, whether it's a coal seam or an ore vein. This allows miners direct access to the material being extracted.
Key Characteristics and Distinctions
The reference highlights several important features of a drift and how it differs from other mine workings:
- Ground Surface Intersection: A drift may or may not intersect the ground surface. This means it can start from the surface (like an adit) or be entirely underground, connecting to other levels or shafts.
- Purpose: Since it follows the ore body or bed, the primary purpose of a drift is often to access, develop, and transport the mined material directly from the deposit.
- Distinguished from Other Passages: The reference clearly differentiates a drift from other common mine terms:
- Crosscut: Unlike a drift which follows the vein, a crosscut intersects the vein or ore body. It runs across the general trend of the deposit or other workings.
- Level or Gallery: A level or gallery is a main horizontal working. The reference states that a level or gallery may either follow or intersect the vein. A drift is a specific type of level that must follow the vein.
Summary Table of Underground Passages
To clarify the distinctions mentioned in the reference:
| Passageway Type | Orientation | Relationship to Vein/Bed | May Intersect Surface? | Primary Function |
|---|---|---|---|---|
| Drift | Near-horizontal | Follows the vein/bed | Yes or No | Accessing/developing the deposit along its trend |
| Crosscut | Usually horizontal | Intersects the vein/bed | No (typically underground) | Connecting drifts/levels, accessing parallel veins |
| Level / Gallery | Horizontal | May follow or intersect | Yes or No | Main haulage/accessways along a specific elevation |
In Practice
Understanding the term "drift" is crucial in mining as it describes a fundamental type of excavation used to explore, develop, and produce minerals by following the shape and direction of the deposit itself. For instance, in a narrow vein deposit, a drift would be driven directly along the vein, providing access for drilling, blasting, and hauling the ore.
