Mining Operations and Techniques

Cycle of Operation

• The cycle of operation involves a sequence of unit operations to accomplish mine development and exploitation, repeated to produce mineral commodities.

Production Operations

• Production operations are directly involved in mineral extraction.

Auxiliary Operations

• Auxiliary operations support production but are not directly involved in mineral extraction.

Rock Breakage

• Rock breakage: freeing or detaching large masses of harder rocks from the parent deposit.

Drilling

• Drilling involves a mechanical device that converts energy into rotational and/or percussive energy to penetrate the rock.
• Drill components:
  • Drill rod (steel, stem, or pipe): transmits energy from the drill to the bit.
  • Bit: attacks the rock with rotational and/or percussive action.
  • Circulation fluid: cleans the hole, controls dust, cools the bit, and stabilizes the hole.
• Drilling strength: resistance of rock to penetration by drilling tools.

Explosives

• Explosives: chemical compounds, mixtures, or devices that function by explosion.
• Blasting agent: chemical material that can detonate under the right impulse.

Blasting Properties

• Velocity of detonation: speed at which a detonation wave travels through a column of explosive.
• Detonation pressure: pressure exerted as the detonation wave travels through an area (measured in kilobar units).
• Borehole (explosion) pressure: gas pressure resulting from the explosion, measures an explosive's ability to displace rock.
• Density: specific weight of the explosive, positively correlated with strength in granular explosives.
• Energy output or strength: total energy released by the explosive during its reaction.
• Cap sensitivity: ease of initiation of an explosive when subjected to a shock wave from a detonator.
• Gap sensitivity (sensitiveness): ability of one explosive charge to detonate another with an air gap between the two.
• Water resistance: ability to withstand exposure to water without losing sensitivity or efficiency.
• Fume class: measures the amount of toxic fumes produced by the blast.

Drilling for Exploration

• Hand Auger: used for testing shallow alluvial deposits and in clay and ordinary materials.
• Empire drill: used for prospecting alluvials.
• Churn drill: used in alluvial, lead, zinc, and copper deposits.
• Hydraulic rotary: used in oil well drilling.
• Jetting method: used in moderately consolidated materials and alluvial deposits.
• Diamond drill: used for tough, hard rocks like unaltered igneous rocks, quartz, and slates.
• Chilled-shot drilling: similar to diamond drilling.

Drilling for Blasting Purposes

• Piston drill (hollow type): admits water and air through the hollow steel, dependent on drill size, air pressure, rock hardness, diameter, depth, and time required.
• Traction Drill: suitable for very hard rock and systematic drilling over an extensive area, suitable for open pit mining.
• Leyner-Ingersoll: uses a light piston that strikes the end of the drill set, primarily used in drifting, crosscutting, stoping, and tunnel work in hard rock.
• Air-feed mounting: telescopic air-feed hammer drill to keep the drill at maximum cutting capacity.
• Air-feed hammer drill types:
  • Solid steel type: suitable for drilling holes at any angle above 30°, mostly used in stoping and raising.
  • Hollow steel type: used in any position, exhaust air blows cuttings out of the hole.
• Non-rotative Hand-held hammer drill: variously termed as hand-feed plugger, plugger, or plug drill, used for small-scale drilling.
• Rotative hand-held hammer: known as jackhammer.