MINING
- is the process of mineral extraction from a rock seam or ore –a natural rock or
sediment containing one or more valuable mineral. The minerals can range from
precious metals and iron to gemstones and quartz. Modern mining technology uses
geophysical techniques that involve measuring the magnetic, gravity and sonic
responses of rocks above and around a prospective mineral ore body
MINING METHODS
A. Surface Mining
1. Open Pit Mining - This is the most common type of surface mining. Open
pit means a big hole (or pit) in the ground. The pit in mine is created by
blasting with explosives and drilling. It is used to mine gravel and sand
and even rock.
2. Strip Mining - This mining type involves the removal of a thin strip of
overburden (earth or soil) above a desired deposit, dumping the removed
overburden behind the deposit, extracting the desired deposit, creating a
second, parallel strip in the same manner and depositing the waste
materials from that second (new) strip onto the first strip. This mining
method is used for coal, phosphates, clays, and tar mining.
3. This is the process of mining materials from the bottom of a body of
water, including rivers, lakes, and oceans.
B. Underground Mining -Utilized to extract ore minerals from the orebody that is deep
under the Earth’s surface
Mineral Processing
1. Sampling – is the removal of a portion which represents a whole needed for the analysis
of this material.
2. Analysis - is important to evaluate the valuable component in an ore. This includes
chemical, mineral and particle size analysis.
3. Recovery - is the process where the valuable components of the ore are separated
through crushing and grinding. This process begins by crushing the ores to a particular
size and finishes it by grinding the ores into a powder form.
Milling or Recovery Methods or Processes
a. Heavy media separation: The crushed rocks are submerged in liquid where the
heavier/denser minerals sink thus are separated from the lighter minerals. This is
commonly used to separate chalcopyrite from quartz before the refining processes of
extracting copper
b. Magnetic separation: If the metal or mineral is magnetic, the crushed ore is separated
from the waste materials using a powerful magnet.
c. Flotation: The powdered ore is placed into an agitated and frothy slurry where some
minerals and metals based on physical and chemical properties may either sink to the
bottom or may stick to the bubbles and rise to the top thus separating the minerals and
metals from the waste.
d. Cyanide heap leaching: This method used for low-grade gold ore where the crushed
rock is placed on a “leach pile” where cyanide solution is sprayed or dripped on top of
the pile. As the leach solution percolates down through the rocks, the gold is dissolved
into the solution. The solution is processed further to extract the gold.
