mineral resources & mining
DESCRIPTION
Mineral Resources & Mining. Eight chemical elements make up 98.3% of Earth’s crust. Oxygen Silicon Aluminum Iron Calcium Sodium Magnesium Potassium. Other elements comprise 1.7% of Earth’s Crust. Many of these are important to industry - PowerPoint PPT PresentationTRANSCRIPT
Mineral Resources & Mining
Eight chemical elements make up 98.3% of Earth’s crust.
OxygenSiliconAluminumIronCalciumSodiumMagnesiumPotassium
Other elements comprise 1.7% of Earth’s CrustMany of these are important to industryDistribution of these elements is not
uniform across the Earth.
Examples:Ni, Ti, Cr, Cu, Pb, Zn, U, Pt, Au, Ag, etc.
Ore If one or more chemical elements occur in
sufficient abundance that they may be mined for a profit, then the rock is termed an ORE.
Classification of Mineral Resources• Metallic Mineral Resources• Abundant (Iron, Aluminum, Magnesium, Manganese,
Titanium)• Scarce (Copper, Lead, Zinc, Chromium, Nickel, Gold,
Silver)• Non-Metallic Mineral Resources• Construction (Sand, Gravel, Clay, Limestone,
Gypsum)• Agriculture/Industry (Phosphates, Nitrates, Sodium
Chloride, Sulfur)• Ceramics/Abrasives (Feldspar, Clay, Quartz,
Diamond, Pumice, Garnet, Corundum)
Processes of ore concentration are related to rock formation. Rocks are grouped into three major families,
based upon their processes of formation.Igneous RocksSedimentary RocksMetamorphic Rocks
Ore formation by igneous processes Crystal Settling
Dense minerals crystallizing in magma, settle to the bottom of the magma chamber– Ex. – Chromium, Platinum, Nickel, Copper, Lead
Ore formation by igneous processes
Hydrothermal enrichment
water, superheated by magma, dissolves minerals and deposits them in “veins”– Ex. – Copper, Gold,
Silver
Ore Formation by Igneous Processes Lode – many thick mineral veins in a small region
– Ex. – The “Mother Lode” during the California gold rush
Hydrothermal Enrichment Pegmatites – “veins” in rocks
Common form of gold enrichment
Exhalites – Submarine vents of hot, mineral-rich water
“Black Smoker Chimneys” – hydrothermal ventsAssociated with mid-ocean ridges
“Black Smokers”
Sulfide Mine in an Exhalite Deposit
Ore Formation by Sedimentary Processes Placer deposits
Moving water erodes rocks releasing heavy minerals which settle on the bottom of stream beds (ex. – gold)– Ex. - gold
Ore Formation by Sedimentary Processes Evaporite deposits
Precipitation of salt in shallow marine basins or saline lakes (in arid climates)– Ex. – halite, gypsum, borax
Ore Formation by Metamorphic Processes During contact metamorphism, pre-existing
rock is altered forming oresEx. – Lead, Copper, Zinc
Prospecting and Exploration
Methods of Discovery:Satellite and Aerial Photography Remote Sensing Geological MappingMagnetic Mapping Gravity Mapping Radioactivity MappingGeochemical Sampling Electrical Sounding Ground-Penetrating RadarSeismic Methods – Reflection - Detailed but Expensive – Refraction - Cheap but Not Detailed
Core Sampling and Well Logging
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?
Issues in Mineral Exploitation
Who Owns (Or Should Own) Minerals?Landowner Discoverer Government
Unclaimed Areas: Sea Floor Antarctica
Who Controls Access for Exploration?Remote Sensing vs. Privacy
Types of Mines Surface
Open pit (Au, Cu)Quarries (stone, gravel, sand)Strip mines (coal)
Subsurface (underground) Placer – dredging (Au) Seafloor– nodules (Mn, Ni, Fe)
Problems with MiningSafety
Mine Wastes/PollutionHazardous working conditionsNoise
Economic Impact"Boom and Bust" Cycles
Environmental ProblemsExplorationConstruction & OperationWaste Disposal
Reclamation Returning the land to
a more natural state after mining operations have ended
Mine Albert, Quebec, before and after reclamation. Government of Quebec
Economic Implications Ores are not found everywhere Some ores are richer than others Ore distribution is a function of geology Ore distribution is not equal across the world Some nations are rich in mineral resources Other nations have few mineral resources No nation is self sufficient in mineral resources
Environmental Considerations Mining leaves holes in the ground Mining adds unusual quantities of sediment
to rivers and streams Mining exposes minerals to interaction with
surface and groundwater, which may contaminate them
Mine waste may be unstable - landslides Smelting may pollute air and water
Why do we need mines?
We all make choices. Industrialized societies depend on mineral
resources Environmental problems must be considered in
extracting wealth from the Earth Its not Good (environment) vs. Evil (industry) It’s a compromise, of which, we must make the
best!