Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Mineral Resources Notes 11-12
Document related concepts
Transcript
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 Distribution 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 Rocks Sedimentary Rocks Metamorphic 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 vents Associated 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 ores Ex. – Lead, Copper, Zinc Prospecting and Exploration Methods of Discovery: Satellite and Aerial Photography Remote Sensing Geological Mapping Magnetic Mapping Gravity Mapping Radioactivity Mapping Geochemical Sampling Electrical Sounding Ground-Penetrating Radar Seismic 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 Mining Safety Mine Wastes/Pollution Hazardous working conditions Noise Economic Impact "Boom and Bust" Cycles Environmental Problems Exploration Construction & Operation Waste 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!
