How are solid non-fuel mineral resources formed and concentrated?

Transcription

1 Resources Part II: Solid Nonfuel Mineral Resources Au Cu SnO 2 Renewable Nonrenewable or Nonrenewable Mineral Resources Gabbro Direct solar energy Winds, tides, flowing water Fossil fuels Metallic minerals (iron, gold, copper, aluminum) Non- Metallic minerals & rocks (clay, sand, marble, slate) These two are sometimes Called: Solid Nonfuel Mineral Resources Potentially Renewable What s Environmental Degradation? Marble Fertile Fresh Fresh Plants and air water animals Slate soil (biodiversity) Fig. 1.11, p. 11 How are solid non-fuel mineral resources formed and concentrated? Rock Cycle Web Links: please read about this: A series of events / processes, both internal and external, through which a rock changes between igneous, sedimentary and metamorphic forms. Cycle takes millions of years and is responsible for concentrating Earth s Nonrenewable Mineral Resources. + Plate Tectonics / Hydrologic Cycle Magmatic Rocks & Minerals granite, diorite, quartz, feldspar, chromite, Magmatic deposits Sedimentary deposits: wind, water, placers Fig a, p.351 1

2 Common Magmatic Rock / Mineral Resources & Their Use (Read later) Granite / Diorite / Gabbro: building materials, dimension stone, roads, shoulders, furniture, counter tops, interior/exterior surfaces (FeMg)Cr2O4 Chromite: important ore of chromium, used to harden and manufacture steel, coloring agent, making bricks, tanning leather, dyes, also used in common materials such as cars, planes, engines, satellites, weapons, home appliances (form from basaltic magmas) Opal (Quartz): gems, abrasives, mortar, glass, silica brick, porcelain, paints, sandpaper, scouring soaps, wood filler, radios, watchesl Platinum, Magnetite, Cobalt and Manganese: also used in manufacturing cars, planes, engines, satellites, weapons, home appliances (form from basaltic magmas) Hydrothermal Deposits Metallic chemical elements, Sulfides and Oxides form in association with magma and water. Hydrothermal deposits often occur in veins Disseminated deposits / gangue e.g. Au rich deposits of CA Sierra Nevada. Black Smokers (undersea hot springs) form at Oceanic Ridges (divergent plate boundaries) and at undersea hot spots. Formation of Metals: Hydrothermal and Magmatic Read this Figure over very carefully Know these symbols / names: Fe = Iron Divergent Au = Gold Plate Boundary Ni = Nickel Cu = Copper Pb = Lead Zn = Zinc Ag = Silver Sn = Tin Cr = Chromium Iron Copper Zinc Lead Hydrothermal Activity Black smokers (undersea hot springs) form at mid-ocean ridge/divergent boundaries. Convergent Plate Boundary Au, Cu Pb, Zn, Ag, Cu Fe Sn, Mo Fe Pb, Zn, Au, Ag, Cu Sn Cu Iron Chromium Nickel Picture taken from Submersible Alvin, 1/7/09 Hydrothermal vein deposits. e.g. rich Au deposits of CA Sierra Nevada. 2

3 Common Hydrothermal Mineral Resources & Their Use Read later Fe / Iron: bikes, cars, bridges, magnets, machines, nails, tools, food supplements Fe / Hematite (Fe 2 O 3 ): ore of iron, pigments, polishing powder, jewelry Au / Gold: circuit boards, electronics, jewelry, planes, space shuttles, compact discs, cameras, telephones Cu / Copper: electrical purposes, circuit boards, wire, sculpture, brass = Cu and Zn, bronze = Cu + Sn and some Zn, German silver Pb / Galena (PbS): lead sulfide, major source of lead, used in making metals, pipe, sheets, solder, glass Zn / Sphalerite (ZnS): ore of zinc, important metal alloy used in making brass, paint, zinc oxide, batteries Ag / Silver: photographic film and paper, photosensitive glass, mirrors, batteries, silverware Sn / Tin: metals, coins, cups, plates, cans, solder, opalescent glass, enamel, weather resistant vinyl siding Magmatic deposits Rare Earth Elements Sedimentary deposits: wind, water, placers The Rare Earth Elements REE Web Link The 17 Rare Earth Elements _element Ru Ruthenuim Rh Rodium Pd Palladium Os Osmium Ir Iridium Pt Platinum Se Selinium 3

4 missiles, drones MRI s night vision goggles Wide Variety of uses: medical (MRI), military, missiles, clean energy technology, catalytic converters, magnets, hybrid car batteries. Consumer Products: cell phones, computer hard drives, monitors, power tools, sun glasses, wine bottles, fluorescent light bulbs, TVs, automobiles, SUV s Also used in Cell Phones Over 3 Square miles Until the mid 1980 s, US led the world in REE production; has ~13% of world reserves. China has ~48% of world reserves, but supplies >97% of the world s needs. Russia, Canada and Australia also have large deposits. 4

5 Mountain Pass Rare Earth Mine in Mountain Pass California, Mojave Desert. Closed in 2002, re-opened in August 2012 Web Link: The Only American Mine for Rare Earth Metals Environmental Concerns Need to excavate a lot of earth / dig huge holes / takes a lot of energy + a lots of solid waste rock. Some elements associated with the REE are radioactive such as Uranium and Thorium. They end up in slurry pools and can enter groundwater. Toxic acids and chemicals are required during the refining process, often end up in slurry pools and can enter groundwater. Baotou, a city in China where ~80% of REE are mined produces ~10 million tons of wastewater/year. Birth defects and Leukemia have been linked to rare earth refinery in Malaysia and China In 2008, ~1/3 of REE in China were mined illegally by heavy polluting, violent criminal gangs. Most of the world s major metal deposits occur at past or present plate boundaries. Surface processes also play an important role in concentrating nonmetallic minerals and rocks. The Lynas Plant in Malaysia is the world's largest processing facility of rare earths. Magmatic deposits Sedimentary deposits Water / Placer deposits Metamorphism Most of the world s major metal deposits occur at past or present plate boundaries. Surface processes also play an important role in concentrating nonmetallic minerals and rocks. Magmatic deposits Sedimentary deposits: wind, water, placers 5

6 Sand Mining in Monterey Bay has been occurring since 1906, ~150, ,000 cubic yards/yr, with no regulation until 1960s. 3 companies for ~80 years, only one is left. Sedimentary Deposits: Sand and gravel accumulate in river A connection between mining and shoreline erosion was determined in the mid 1980s, but still 1 company mines ~200,000 cubic yards each year. water filtration, glass production.. channels and bars, coastal offshore bars, sand dunes, beaches and glacial outwash plains. After deposition sediments lithify by compaction and cementation. Materials used for: road beds, cement production, bricks, tiles, abrasives, Sand Mining in Monterey Bay (web link) Point Bars Placer Deposits Read this slide over very carefully. Evaporites: (Salts: halite, gypsum, borates) water evaporates from shallow inland seas or lakes in warm arid climates. Materials used in: making glass, ceramics, metals, preservatives, cleaning agents, water softeners.. Most of the world s major metal deposits occur at past or present plate boundaries. Surface processes also play an important role in concentrating nonmetallic minerals and rocks. Magmatic deposits Sedimentary deposits: wind, water, placers 6

7 How are mineral resources found? Understand the geologic/plate tectonic history of an area Make Maps: rock formations, faults, structure Drill, extract and analyze rock/sediment samples Aerial photos and satellite images, reveals outcrops and types of rock types Seismic & gravitational surveys give info about buried rock layers Chemical analysis of water and plants to detect minerals leached into water and absorbed by plants Remote sensing: (detect /analyze wave transmitted energy) reveals outcrops and types of rock Secondary Enrichment Measure radiation, magnetism to detect radioactive metals, iron and other How are Mineral Resources Extracted? Bingham Copper Mine, Utah >4km wide, 1.2 km deep, >6 billion tons of rock mined since 1906 Surface Mining machines strip away millions of tons of Overburden (rock/earth covering ore) and pile it up as waste material sometimes called Spoil 1) Open-pit mining: commonly used surface mining technique; used for mining most major metal deposits, also sand, gravel and stone. The Palabora open pit in NE South Africa. The hard rock allows the pit walls to be cut much steeper than is normal in open-pit Copper mining. More Surface Mining 2) Hydraulic Mining: wash away overburden on hillsides; mine uplifted placer deposits. In CA huge volumes of sediment washed into SF-San Joaquin delta harming navigation and agriculture, ~ 1850 s 1890 s. 3) Dredging: used on underwater mineral deposits; gold mining of CA riverbed sediments until 1960s; leaves great piles of spoil alongside channels called spoil banks/dredge fields. ~13 billion cubic yards of sediment have been washed away from the Sierra Nevada 7

8 How are ores processed? Smelting or Extractive Metallurgy is the practice of extracting metal from ore, purifying it, and recycling it Remove undesired parts of ore (gangue) Smelting extracts metals from other elements Separation of ore from gangue Melting metal Pure metal is then converted to desired product by manufacturing companies Metal ore Recycling Conversion to product Drawbacks? Results in air, water, soil pollution; solid and liquid hazardous wastes; safety and health hazards Start Here: Surface Mining Discarding of product Scattered in environment Why do we mine? Concerns? Environmental degradation from mining and processing, depletion time, economic depletion, exhaustion, import dependence, high cost Supply and Consumption of Mineral Resources Economic Depletion Costs more to find, extract, transport and process mineral than deposit is worth. Options: 1) recycle or reuse existing supplies, 2)waste less, 3) use less, 4) find substitute, 5) do without. Depletion Time: time it takes to use up 80% of reserves of a mineral at a given rate of use. US currently imports ~50% of its most important non-fuel minerals. Used faster than they can be produced here Foreign ores are higher grade and can be extracted cheaper than US reserves A Mine, use, throw away; no new discoveries; rising prices Production B Recycle; increase reserves by improved mining technology, higher prices, and new discoveries C Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices, and new discoveries Present Depletion time A Depletion time B Time Depletion time C 8