Activity 2-unit 2-update 2024. English translation
Ugrc 140 (earth resources)
1.
2. OVERVIEW
Purpose and Objectives of lesson
Introduction
Elements as building blocks
What are minerals?
Types of mineral deposits
Minerals extraction
Economic factors in mining
Environmental consequence of mining
Conclusion
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3. Purpose and Objectives
This lesson is to enable you
understand what minerals/ores
are, the various ore deposits
and extraction
It is expected that by the end of
the lesson you should be able to
…..
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4. Purpose and Objectives
State the characteristics of minerals
Identify the various formations of minerals
State and explain the types of mineral
deposits
Differentiate between metallic and non-
metallic minerals
State the mineral extraction methods
Develop the understanding of the
environmental problems associated with
minerals extraction
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5. Introduction
There is the understanding of the
existence of minerals
More detailed knowledge is
required to understand the various
categories of minerals/deposits and
the environmental impact of mining
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6. Elements and the Periodic Table
Elements are the basic building
blocks of minerals
Over 100 elements are known
8. What are Minerals
1. Naturally occurring
2. Solid substance
3. Orderly crystalline structure
4. Definite chemical composition
5. Generally considered inorganic
9. How many minerals are there?
About 4000 minerals are listed but
relatively few are popular due to
their pleasing appearance
Generally composed of more than
one element or compound
11. Formation of minerals
Crystallization from magma
Precipitation from solution
Recrystallization as a result of
high pressure and temperature
Crystallization from
hydrothermal solutions
13. Metallic and non-metallic
minerals
Metallic
If the surface of the mineral reflects light
e.g. Copper, Gold, Pyrite, Iron, Aluminum
Non-metallic
If the surface of the mineral does not
reflect light
e.g. Sulfur, Halite (rock
salt),Feldspar, quartz, calcite
16. Rocks
They consist of many individual
mineral grains firmly held together
in a solid mass
Types of Rocks
Igneous
Sedimentary
metamorphic
17. Ore Deposits
An ore is a rock in which a valuable mineral
or metal occurs at the concentration
sufficiently high, relative to average rocks, to
make it economically worth mining
The value of a mineral or metal extracted and
its concentration in a particular deposit are
the major factors determining the
profitability of mining a specific deposit
18. Definition of a mineral or rock
resource
Mineral or rock resources
are any material of value
that are derived from rocks
or minerals
19. Definition of a mineral or rock
resource
The resources can be separated into three
groups
Metallic
E.g.
gold, platinum, silver, copper,
iron, aluminum, tin, lead, uran
20. Definition of a mineral or rock
resource
Non-metallic
E.g. diamonds and other
precious
stones, salt, gypsum, potash
21. Definition of a mineral or rock
resource
Rocks
E.g. marble, cut
granite, crushed stone, sand
and gravel
23. Types of Mineral Deposits
Igneous rocksand magmatic deposits
Hydrothermal ores
Metamorphic deposits
Sedimentary deposits
24. Types of Mineral Deposits
Weathering-leaching away of unwanted
minerals leaving a residue enriched in
some valuable metal
Placer -ores concentrated by stream or
wave action on the basis of mineral
densities or resistance to weathering
All require a concentration mechanism
25. Igneous rocks and magmatic deposits
Gravity causes early-crystallizing dense
minerals to sink to bottom of magma
chamber
Minerals may also float to the top if they
are less dense than magma
Chromite, magnetite, and platinum-
group mineral deposits often formed in
this way
27. Diamonds
Diamonds are formed at very high pressures
Usually require 100-200 km depth
Brought rapidly to the surface by Kimberlite
magmas.
These are gas-rich magmas that explode on their
way to the surface. May erupt at very high
velocities.
Only need a few diamonds per ton of rock to make
the rock an ore.
28. Hydrothermal deposits
Hot waters percolating through the rocks
surrounding an intrusion leach elements from them
Later deposits these elements in minerals that
crystallize when the fluids cool as they approach
the surface.
Often this process forms veins rich in sulfide
minerals that contain metals such as
Cu, Pb, Zn, Au, Ag, Pt, and U
31. Metamorphic deposits
Increasing pressure and temperature creates
new minerals, sometimes in great abundance
if the composition is right
Generally, metamorphism produces
concentrations of useful minerals, rather
than a concentration of a specific element.
Examples include graphite, asbestos, and
garnet (abrasive).
32. Sedimentary Deposits
Processesassociated with the
formation of sedimentary rocks can
also produce economic mineral
deposits
E.g. Banded iron ores
Iron-rich layers alternating with
silicate - or carbonate-rich layers
33. Sedimentary Deposits
Banded iron ores
Mode of formation
In early earth's history, atmosphere was
reducing (oxygen poor).
In reducing environments iron is soluble in
water
However, world's oceans contained more
oxygen due to the action of one-celled plants,
such as algae
34. Sedimentary Deposits
Banded iron ores
Mode of formation
Therefore, the oceans were oxidizing
In oxidizing environments iron precipitates
out of solution
So as iron-rich waters entered the oceans the
iron precipitated out forming layers of iron-
rich sediment and eventually forming rocks
35.
36. Sedimentary deposits
E,g. Evaporites:
As seawater evaporates in hot, dry
climates dissolved minerals, such as
calcite, gypsum and halite, crystallize
Form sediment layers (and rocks) rich in
these minerals
Occurs naturally and also in man-made
evaporation ponds
37. Weathering
Intense chemical weathering leaches out
most elements
Material left behind is enriched in Al and
Fe
Forms bauxite (the ore for aluminum) in
lateritic soils
38. Placer deposits
Dense,heavy minerals fall out of
suspension when water velocity
decreases
Thiscan concentrate a specific
mineral in a confined area, and
often occurs in streams or in coastal
environments
39. Placer deposits
The minerals formed in a particular
area are transported, sorted, and
concentrated by the water, to form a
placer deposit
Many gold, tin, and diamond
deposits are formed in this way
41. Metallic Resources
Abundant Metals
Iron, aluminum, manganese,
titanium, silicon, magnesium
Produced by variety of geologic
processes
Supplies for future is adequate
Not distributed uniformly
42. Metallic Resources
Scarce Metals
Comprise less than 0.1% of
Earth’s crust (rare conditions
concentrate them) (e.g.
copper, lead, zinc, gold, and
silver)
Fewer deposits, so supplies are
more precarious
46. Classification of Minerals
Can be classified based on their
composition
1. Silicates
Silicon and oxygen combine to form a
structure called the silicon-oxygen
tetrahedron. This silicon-oxygen
tetrahedron provides the framework of
every silicate mineral.
47. Classification of Minerals
2. Carbonates
Minerals that contain the
elements carbon, oxygen, and one
or more other metallic elements
48. Classification of Minerals
3. Oxides
Minerals that contain oxygen and
one or more other
elements, which are usually
metals
67. Prospecting, Exploration and
Mining
Prospecting Exploration Mining
The act of looking for a Involves many different
spot where there is methods in looking for
spot of mineralization The extraction of the ore
valuable ore in order to
from such a place
mine there
Great impact work
Very low impact work involved.
involved Drilling, trenching, etc.
Great impact work also
68. Prospecting and Exploration
Satellite and Aerial Geochemical Sampling
Photography Electrical Sounding
Remote Sensing
Ground-Penetrating
Geological Mapping Radar
Magnetic Mapping
Seismic Methods
Gravity Mapping
o Reflection : Detailed
Radioactivity Mapping
but expensive
o Refraction : Cheap
but not Detailed
Core Sampling and Well
Logging
69. Mineral extraction
Mineral resources are typically extracted
from rocks using a variety of techniques:
• Strip mining
• Quarrying
• tunnel mining
• heap-leaching
• Flotation
• Crushing - treatment by chemicals to extract
metal from rock "flour"
• Smelting
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78.
79. Economic Factors in Mining
Richness of Ore
Quantity of Ore
Cost of Initial Development
Equipment, Excavation, Purchase of Rights
Operating Costs: Wages, Taxes,
Maintenance, Utilities, Regulation
Price of the Product
Will Price Go up or down?
80. Life Cycle of a Mine
Exploration
Development
Active Mining
o Excavation
o Crushing, Milling, Flotation, Chemical
Separation
o Smelting and Refining
o Disposal of Waste (Tailings)
Shut-down
81. Issues in Mineral Exploitation
Who Owns (or should own) minerals?
Landowner,
Discoverer,
Government
Unclaimed Areas:
Sea Floor,
Antarctica
Who Controls access for Exploration?
o Nobody is obligated to let someone onto their
property to prospect. However, they must allow
access if someone owns the subsurface rights.
83. POSITIVE IMPACT
• Creation of Employment
• Provide raw materials for the
construction Industries
• Encourage cottage Industries
• Generate income
• Earn revenue for the government
84. Environmental impacts of
mineral and rock exploitation
Mining is any activity that involves excavating the earth
surface for the purpose of exploiting and processing the
mineral wealth for economic and industrial
development
both for local and export markets.
This process normally has a negative impact on the
environment.
There are two main methods of mining;
Underground mining
Open cast mining
85. Underground Mining
This refers to any sub-surface vertical or
horizontal excavations that are made for the
extraction of minerals.
This method has little effect on the vegetation
and the ecosystem in general.
Open-casting Mining
This refers to uncovered excavations made on
the ground for the purpose of mineral or rock
exploitation such as the open
quarries, pits, trenches, etc.
86. Impact of Mining on the
Environment
Any mining operation draws ores and
other raw materials from the earth
This has a direct impact on the biological
and physical environment
The nature and degree of impacts vary
widely depending on the location and
type of operation.
87. Impact of Mining on the
Environment
However, mining operations will
generally affect the hydrological
functions and hence water quality.
This is because mining interferes with
the ground water table by lowering it and
introducing pollutants to the aquifer
88. Impact of Mining on the
Environment
Effects can either be physically or
chemically influenced depending on the
mining activities
Disturbs land by removing surface
vegetation and changing topography
Affects hydrological functions and water
quality, causes soil erosion and stream
sedimentation that cause death of trees
along river banks
89. Impact of Mining on the
Environment
Produces dust
Lowers the water tables
Destroys wildlife habitat.
The additional vehicular traffic around a
mine site brings noise and increases wear
on the roads.
90.
91. ACID MINE DRAINAGE
Mining activity occurs in areas that have
high concentrations of economically
important materials, such as
gold, silver, copper, cobalt, iron, lead, and
zinc
These areas may also contain high
concentrations of noneconomic elements
such as arsenic, selenium, mercury, and
sulphur, whose presence is closely tied to
92. ACID MINE DRAINAGE
Many of these economic and noneconomic
elements can be hazardous if released into
the environment
Even without mining, mineralized areas
can naturally adversely affect the
environment.
93. ACID MINE DRAINAGE
A common process that results in
dispersion of elements from a mineralized
site is acid rock drainage.
When acid drainage results from mining
activity, it is more specifically called acid
mine drainage.
As the name implies, acid mine drainage is
the formation and movement of highly
acidic water rich in heavy metals
94. ACID MINE DRAINAGE
This acidic water is formed principally
through chemical reaction of surface
water (rainwater, pond water) and
shallow subsurface water with rocks that
contain sulphur-bearing minerals
(e.g., pyrite), resulting in sulphuric acid.
95. ACID MINE DRAINAGE
Heavy metals can be leached from rocks
that come in contact with the acid, a
process that may be substantially
enhanced by bacterial action.
The resulting fluids may be highly toxic
and when mixed with
groundwater, surface water, and soil may
have harmful effects on humans, animals
and plants.
96. ACID MINE DRAINAGE
Mining accentuates and accelerates natural
processes.
The development of underground
workings, open pits, ore piles, mill
tailings, and spoil heaps and the extractive
processing of ores enhance the likelihood
of releasing chemical elements to the
surrounding area in large amounts and at
increased rates relative to unmined areas
97. ACID MINE DRAINAGE
Studies describing both the extent and effect
of acid drainage both in unmined mineralized
areas and in areas containing inactive and
abandoned mines are required if the
environmental impact of heavy metals is to be
understood.
Studies in unmined mineralized areas describe
the natural, baseline chemical characteristics
and variations of the mineralized areas.
98. ACID MINE DRAINAGE
By combining these baseline studies with
information from areas containing inactive
and abandoned mines, it is possible to
provide:
An assessment of the intensity and extent of
environmental impact due to acid mine drainage
An understanding of natural processes to detect and
predict where and when acid mine drainage might
occur.