4. ORES
- are naturally occurring materials that can be
profitably mined. It can be metallic or non-metallic,
depending on the economic requirement. A deposit is
considered a potential ore body if its localized
abundance is greater than its average abundance or
distribution on Earth’s crust.
5. A rock or mineral is considered an ore based on its:
1. Overall chemical composition
2. Percentage of extractable resource with
respect to its total volume
3. Market value of the resource
7. Ore bodies are unevenly distributed throughout
Earth’s crust. This is the main reason why a
country will never be self-sufficient in terms of
natural resources and supplies.
Potential ore bodies are located by
recognizing that geologic process or
combination of processes can produce a
localized enrichment of one or more minerals,
and that these processes only happen on
particular types of environment
8. Hydrothermal fluid
circulation
▪ the most common type of
ore mineral deposition
process.
▪ Hydrothermal fluids form
when groundwater or
seawater is heated by
magma or when hot,
aqueous solutions are
expelled from a cooling
plutonic body. This produces
veins that host metals like
gold, silver, and copper.
FORMATION OF ORE DEPOSITS
9.
10. Metamorphic
processes
▪ leads to the alteration and
recrystallization of
minerals and aids the
formation and localization
of economically –
important materials like
graphite, marble, and
asbestos.
FORMATION OF ORE DEPOSITS
11.
12. Magmatic processes
▪ create ore minerals
which are
concentrated due to
their premature
recrystallization and
separation from
magma.
FORMATION OF ORE DEPOSITS
13.
14. Chemical sedimentary
processes
▪ form evaporates deposits
from the precipitation of
saltwater minerals (halite,
gypsum, limestone) and
evaporation of lake water
(anhydrite)
FORMATION OF ORE DEPOSITS
15.
16. The action of ocean
waves or currents in
flowing surface water
▪ tend to take sediments
along.
▪ If the wave action and
strength is constant, it
causes a selective sifting
effect that removes
sediments and leaves
behind those that are
heavier in what are called
placer deposits.
FORMATION OF ORE DEPOSITS
20. Unlike other natural resources,
mineral resources are
commonly hidden. Finding a
deposit worth mining is very
difficult. It is because of this
unique challenge that access
to large areas of land is
necessary for mineral
exploration.
1. Available Land
Resources
21. ▪ Looking for the ore body
▪ Exploration work relies on
many others besides
geologists, many workers are
involved: pilots, drillers,
assayers, equipment operators,
surveyors, mechanics, camp
cooks, and many others all play
essential roles in the discovery
of viable mineral deposits.
2. Prospecting or
exploration
22. ▪ It is an extremely complex
one that can take years to
complete.
▪ It is at this stage that a
company proposing a mine
project includes a complete
reclamation, satisfactory land-
use end goal, and monitoring
plan.
3. Environmental
Assessment and
Approval
23. ▪ Engineers and scientists work
hard hand in hand to create the
appropriate mine and
operational design, and
proceeds with the construction
once all the necessary permits
are acquired from the
government and local
communities
4. Designing and
constructing the
mine
24. ▪ Suppliers of transportation,
utilities, building materials,
equipment and hundreds of
other goods and services are
brought in to take the project
into production.
▪ Depending on the size of the
mine, construction may require
more than 1000 people and
cost over $1 billion.
4. Designing and
constructing the
mine
25. ❑ Extraction
- Surface mining methods
are used to extract ore close to
the surface of the Earth.
- Large-scale equipment -
drills, shovels and trucks - are
used to make operations
efficient and economical
- High grade ores are
separated from the rest of the
deposit
5. Operation
26. ❑ Processing
- These are the steps
required to change raw, broken
ore into useable material or to
liberate and separate valuable
minerals from waste rock.
5. Operation
27. ▪ Closure of the depleted
mine;
▪ Workers in this department
at a mine carry out long term
monitoring, and design and
implement plans to prevent
deliberate harm and to
minimize or remediate
impacted areas.
6. Reclamation-mine
site decommissioning
28. ▪ Environmental engineers work
with biologists, chemists,
ecologists, wildlife specialists,
and ranchers, along with
equipment operators, nursery
staff, and agronomists so that
when mining is over, the site
is left in a safe and productive
state, as similar in appearance
to the surrounding landscape
as possible.
6. Reclamation-mine
site decommissioning
30. ● Open Pit Mining
– which
commonly
involve large
holes that
extract relatively
low-grade
metallic ore.
1. Surface Mining Methods
31. ● Strip Mining –
which extract
horizontal layers
of ore or rock.
1. Surface Mining Methods
32. ● Placer mining –
where gold or
diamonds are
extracted from
river and beach
sediment by
scooping up the
sediment and then
the ore by density.
1. Surface Mining Methods
33. ● Quarrying - refers
to surface mining
that does not
require complex
processing.
1. Surface Mining Methods
34. ● Quarrying - is used
to mine sand and
gravel, crushed stone
aggregate, many
industrial minerals
(like limestone,
gypsum and
magnetite), and
dimension stone for
building material and
construction.
1. Surface Mining Methods
35. ● are used when the
mineral deposit is
too deep
underground to be
practical and
economical to
mine from the
surface.
2. Underground Mining Methods
36. ● Processing
metallic ore (gold,
silver, copper, iron,
etc.) can involve
numerous steps
including crushing,
grinding, and
physical
separating.
2. Underground Mining Methods
37. ● Smelting – heating
the ore minerals
with different
chemicals to extract
the metal
● Leaching – using
chemicals to
dissolve the metals
from a large volume
of crushed rock.
2. Underground Mining Methods
38. ● Smelting – heating
the ore minerals
with different
chemicals to extract
the metal
● Leaching – using
chemicals to
dissolve the metals
from a large volume
of crushed rock.
2. Underground Mining Methods
40. Mining – open pit
and underground
Some of the harder
areas require blasting
to loosen the rock
prior to excavation by
hydraulic diggers.
Dump trucks haul the
rock to the primary
crushers in the open
pit or to the ore
stockpiles from
underground.
41. Crushing
The primary crushers
located at the open
pit mine site, receive
ore and waste at
separate times. They
break the larger rocks
down to a size
suitable for transport
on the conveyor belt.
42. Transport
A rubber belted
conveyor transports
the ore and waste
rock from the open
pit, approximately
two kilometers, via a
tunnel through Hill,
to the mill and waste
rock embankments.
43. Grinding and sizing
Ore from both open
pit and underground
is stockpiled
separately at the mill
before being fed into
a S.A.G. mill with
lime, water and steel
balls. The larger
particles from this
mill are returned to
the S.A.G. mill for
more grinding.
44. Leaching and adsorption
A slurry of ground ore,
water and a weak cyanide
solution is fed into large
steel leach tanks where
the gold and silver are
dissolved. Following
this leaching process
the slurry passes through
six adsorption tanks
containing carbon
granules which adsorb the
gold and silver.
45. Elution and
Electrowinning
The loaded carbon is fed
into an elution column
where the bullion is
washed off.
The barren carbon is
recycled. The wash
solution—pregnant
electrolyte—is passed
through electrowinning
cells where gold and
silver is won onto stainless
steel cathodes.
46. Bullion production
The loaded cathodes
are rinsed to yield a
gold and silver
bearing sludge which
is dried, mixed with
fluxes and put into
the furnace. After
several hours the
molten material is
poured into a cascade
of moulds producing
bars of doré bullion.
47. Water treatment
Some water from
dewatering the mine,
from the
embankment
underdrains and
decant water from the
tailings pond is
recycled for use in
the grinding circuit.
48. Tailings disposal
Waste rock from the
open pit mine is used to
build the embankment
structures. The
embankments retain the
tailings slurry in a pond
where solids settle and
compact.
Water is decanted off
and used in the
process plant or
treated before it is
discharged.
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