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Mineral Resources Society and standard of living critically dependent upon availability of mineral and energy resources Mineral resources here, energy.

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Presentation on theme: "Mineral Resources Society and standard of living critically dependent upon availability of mineral and energy resources Mineral resources here, energy."— Presentation transcript:

1 Mineral Resources Society and standard of living critically dependent upon availability of mineral and energy resources Mineral resources here, energy in the next chapter Think of your home or dorm room: Cement, wood, metals, plastics, ceramics Your breakfast: Dishes, utensils, napkins, even the food required fertilizers (potash, P, N…)

2 A few of the many mineral products in the typical American home

3 Use of minerals in the US > than 18,000 lbs per person each year
Mineral Resources Use of minerals in the US > than 18,000 lbs per person each year

4 Mineral Resources Infrastructure of manufacturing, transportation equipment, etc. Capital, material, energy for manufacture and transportation Much of history (including wars) can be explained in terms of haves and have-nots with respect to mineral and energy wealth Great Britain had huge wealth, and a people who could exploit it Reached the top of the heap: ships, cannon, industrial revolution… Ran low… went and took somebody elses! an Empire is born! Why did Germany attack Russia in WWII?? One large reason was the Caucasus oil fields Norway was invaded for its iron Why is South Africa so strong, and why didn’t the Boers want to let go? Platinum, diamonds, gold Why did Iran invade Kuwait? Why did US get involved to protect it?

5 Flow diagram of non-fuel mineral resources & their role in US economy
Value of processed materials = $351 Billion (310 domestic + 41 imported) = ~ 5% of GDP, but GDP would be much lower without it

6 Mineral Resources Resources are all around us, but too dispersed to be of any value Economic implications! Never completely run out of anything Simply become too expensive to produce ® Mineral deposits when concentrated by various geologic processes since Earth created ~ 4.5 Ga Gold in the oceans: 5 x 10-9 troy oz/gal  10 billion tons of gold! But how would we get it? Note the economic implications here!!! We will never completely run out of anything! It will simply become too expensive to produce

7 Igneous Processes 1) Very valuable minerals- dispersed, but worth scavanging Example: Kimberlite pipes and diamonds Blasted up through crust from the mantle Diamond = C, like graphite, but stable form at very high P (> 150 km depth): metastable A rich economic deposit may have a diamond concentration of 1 – 1.4 g per ton of rock Must be very valuable to merit excavating and processing

8 2) Igneous Concentration Mechanisms:
Igneous Processes 2) Igneous Concentration Mechanisms: a) Crystal settling Magmas are complex and crystallize over a range of temperatures Early heavy minerals settle to bottom of liquid magma chamber: olivine, chromite, magnetite, platinum

9 2) Igneous Concentration Mechanisms:
Igneous Processes 2) Igneous Concentration Mechanisms: b) Concentrating in residual liquids as magma crystallizes Water and many rare elements don’t incorporate in common minerals Remain and concentrate in late melts at the top of a pluton Often the water pressure in the late melts builds to the point that it fractures the overlying rock and material escapes as hydrothermal fluids

10 Igneous Processes 2) Igneous Concentration Mechanisms:
b) Concentrating in residual liquids Examples: Pegmatites: Water-rich melts with concentrations of otherwise rare elements: gems, Li (batteries), Be, REE (semiconductors) Hydrothermal Cu, Au, Ag, Hg, Pb, Zn.... Porphry Cu at subduction zones late fluids  veins and cracks or more permeating Massive sulfide Cu: at mid-ocean ridges (now found where subducted, uplifted, and eroded)

11 A typical cupola area at the roof of a pluton
8 cm tourmaline crystals from pegmatite Contact metamorphic deposits A typical cupola area at the roof of a pluton 5 mm gold from a hydrothermal deposit

12 “Black smoker” on the East Pacific Rise: Fe-Cu-Zn sulfide precipitates
Massive sulfides occur at mid-ocean ridges where recirculating seawater helps withdraw ore and concentrates it as it cools again when it reaches the seabed

13 Exploration techniques use models
slivers of oceanic crust Porphry Cu deposits in the Americas Exploration techniques use models Plate tectonics is a very useful model Subduction zones locate porphry Cu Massive sulfides may be found where oceanic crust slivers onto continents Also use geophysics and geochemistry to locate ores

14 Metamorphic Processes
3) Metamorphic Concentration Mechanisms: Contact metamorphism occurs at the contact between hot magma and cool country rocks  replacement ores (include Cu, W, Sn, Pb, Zn…) Calcite (CaCO3) Sphalerite (ZnS) Scheelite (CaWO4) Fluorite (CaF2) Replacement ore of the Tem-Piute Mine, Nevada. Mined for tungsten.

15 Metamorphic Processes
3) Metamorphic Concentration Mechanisms: Regional metamorphism occurs over broad areas due to mountain-building processes  local concentrations of talc, graphite, asbestos, garnet & corundum (abrasives) Fist-sized garnets created by regional metamorphism, Gore Mt, New York. Mined for sandpaper.

16 Sedimentary Processes
4) Sedimentary Concentration Mechanisms: Clastic processes involve transport and deposition: Sand and gravel (big $$) from old river channels, glacial deposits, deltas Placer deposits of weathering-resistant and heavy minerals (Au, Ag, diamond, garnet) Gold nugget, California (2 cm) Placer diamonds, Namibia (3 cm across)

17 Formation of placer gold by erosion of hydrothermal veins, transport, and redeposition in a stream bed Veins are often called lode deposits, and one may be able to trace the placers to the lode, if any remains

18 California’s gold rush of the 1848-1880:
Numbers are thousands of ft2 of rock debris washed down from the hills or accumulated in the bay Record nugget was 162 lbs of pure gold One miner recovered 30 lbs of gold from 4 ft2 in a month Miners at the Volcano camp sometimes found $370 worth of gold in a single panful

19 Sedimentary Processes
4) Sedimentary Concentration Mechanisms: Precipitates: Marine: limestone, phosphate, Precambrian Fe ores (over 700,000,000 yrs ago when more oxidizing atmosphere), Mn nodules, evaporites (salt, gypsum) plus K, B, some metal-rich brines Fresh-water precipitates are rarely economic

20 Figure 14-8: Marine evaporite deposits of the USA

21 Sedimentary Processes
4) Sedimentary Concentration Mechanisms: Biological deposits: Phosphate = fish bones and teeth, guano  fertilizers Diatomaceous earth & many limestones Weathering: Bauxite = Al in zone of leaching in laterites (highly leached tropical soils) Supergene enrichment of Cu

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24 The time-frame of resources is important
Mineral Resources The time-frame of resources is important Non-renewable resources are created on our time-scale (won’t add much in next 10 Ma) No sustained yield like crops, timber… “Resources” = useful materials that can be extracted and made into a useful commodity at a profit (either now or in the reasonable future) “Reserves” = that portion of a resource that is identified and currently available (legally and economically extractable at the time of evaluation) Resources thus = reserves + sub-economic + speculative estimates Time-frame is important You as an example: Let’s say you’re very bright, and also very poor Is college education worth getting a student loan? (assuming no scholarship) Your reserves are too low to pay, but your resources (future pay as a lawyer or doctor…) are considerable Use both your reserves and resources in your deliberations Likewise, most nations estimate their reserves and resources as they contemplate their plans They continually reassess reserves, resources, needs and consumption rates as technologies change They also have strategic reserves and stockpiles

25 Figure 14.2: USGS classification of mineral resources
Undiscovered Identified In known In undiscovered districts districts or forms Economic Reserves Marginally Marginal Hypothetical Speculative Economic Reserves Resources Resources Subeconomic Subeconomic Resources Some resources can be measured and estimated rather accurately: Coal, evaporites, sedimentary iron, etc. are in beds, so map & estimate thickness and extent Drill copper deposit, so know average grade and size Others are often less well constrained and must be estimated on general geology Smaller, lower grade, and deeper  less economical to extract (Au in seawater example) Increasing degree of geological assurance

26 Consumption, Resources, and Availability
Mineral Resources Consumption, Resources, and Availability Exponential growth of consumption of a resource, either within a country or the planet as a whole is usually greater than population growth The typical evolution curve for a non-renewable resource

27 Consumption, Resources, and Availability
time production rate (1) (2) Growth stages: 1) Demand increases exponentially For non-renewable resources: 2) Deplete the easy to find, highly concentrated and shallow resources Much depends on our ability to keep these resources in production 1) Demand increases exponentially More affluence & ways of using a material to the population growth of users Supply follows suit, at least initially For non-renewable resources: 2) We deplete the easy to find, highly concentrated and shallow resources At some point demand will outdistance supply, so that the curve must decrease in slope Therefore much depends on our ability to keep these resources in production

28 Consumption, Resources, and Availability
When do we do when we run out?? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0.1 100 1,000 10,000 0.01 Average Crustal Rocks High-U Granites Black Shales Phosphoria Formation Original Rich U finds Log Rock Tonnage Uranium Concentration Grade vs. Quantity of Uranium in the upper km of crust in the USA Probable Richest Ore ppm % 1) Search harder, dig deeper, find more (and pay more)

29 % Produced Demand (tons) Foreign sources (% Imported)
Commodity In USA % Produced Demand (tons) Reserves/Cumulative Demand Foreign sources (% Imported) USSR 41, South Africa 15 < 0.1 Chromium Availability and Demand of 32 “Critical” Non-fuel Mineral Commodities (1978) 500,000 9.5 US World Gabon 29, Brazil 18 Manganese 1,300,000 4.6 Zaire 62 Cobalt 8,600 1.2 Malaysia, Thailand, Canada Titanium 750 Brazil 57, Canada 14 Columbium 2,600 > 10 Malaysia 50, Bolivia 18 0.1 Tin 50,000 1.5 0.2 South Africa 74, USSR 8 Platinum Group 65 3 6 South Africa 38, Bolivia 16 Antimony 16,000 1.8 Canada 56, New Caledonia 9 Nickel 170,000 2.2 8 Jamaica 28, Austalia 23 Aluminum 5,300,000 5.8 16 Canada 94, South Africa 4 Asbestos 580,000 0.5 18 Mexico 59, South Africa 17 Fluorine 550,000 0.4 31 Canada 42, Mexico 6 0.6 Zinc 1,000,000 0.8 33 Canada 46, Mexico 24 Silver 3,500 Canada 14, USSR 33 Gold 1.1 38 Canada 25, Bolivia 19 Tungsten 8,700 1.4 39 Canada 95, Israel 3 0.9 Potash 5,900,000 1.0 Cadmium 5,100 2) Import (foreign debt and dependence)

30 Only 12 have cumulative demand < domestic supplies by 2000
Commodity In USA % Produced Demand (tons) Reserves/Cumulative Demand Foreign sources (% Imported) US World 43 Brazil 56, Argentina 21 3.1 Berylluim 63 > 10 Algeria 31, Spain 31 0.3 Mercury 2,000 0.9 48 Australia 48, Canada 22 1.4 Titanium 460,000 4.1 58 Canada 39, Japan 17 1.5 Iron 87,000,000 5.1 60 Peru 28, Ireland 22 1.3 Barite 2,500,000 76 Canada 27, Mexico 26 1.0 Lead 700,000 1.1 South Africa 54, Chile 26 0.2 Vanadium 6,300 7.8 77 Canada 24, Chile 24 Copper 1,700,000 1.6 90 Canada 59, Mexico 39 0.5 Sulfur 13,000,000 Australia 43, Malaysia 32 9.3 Rare Earths 18,000 8.0 144 2.8 Lithium 3,900 - 180 3.6 Phosphate 34,000,000 6.5 200 2.9 Molybdenum 30,000 2.1 42 Canada 46, Mexico 24 1.9 Selenium 500 3.5 Availability and Demand of 32 “Critical” Non-fuel Mineral Commodities (1978) Only 12 have cumulative demand < domestic supplies by 2000 Only last 3 does US produce as much as we consume in US each year (Li, P, Mo) Reserves of > ½ used up by 2020

31 By 1994 US imports looked like this

32 Consumption, Resources, and Availability
When do we do when we run out?? Search harder, dig deeper, find more (and pay more) Import (foreign debt and dependence) Find a substitute (synthetics replace metals, cotton…) Conserve (use less or be more efficient) Recycle (OK for metals, glass, but has limits) Steal somebody else’s (war) Do without The choice depends on many social, political, economic, and environmental factors

33 Environmental Impacts of Mineral Consumption, Mining, and Processing
Processing of a typical metal sulfide ore (copper, lead, zinc, molybdenum...)

34 Environmental Impacts of Mineral Consumption, Mining, and Processing
Surface mining  open pits like Bingham Canyon near Salt Lake (or Helena, MT) Bingham Canyon open pit Cu sulfide mine, Utah The World’s largest hole in the ground

35 Environmental Impacts of Mineral Consumption, Mining, and Processing
Surface mining Mining ruptures the weathered barrier and exposes the interior to the environment

36 Environmental Impacts of Mineral Consumption, Mining, and Processing
Sub-surface mining  less impact on site, but still exposes ore to water

37 Environmental Impacts of Mineral Consumption, Mining, and Processing
Materials are relatively toxic when exposed at the surface Water  weathering, solution  toxic metals + sulfuric acid into surface & groundwater environment Est. 550,000 abandoned mines in USA contaminate 19,000 rivers and streams Collapse of old excavations poses a serious threat as well Acidic and Fe-rich water from an abandoned sub-surface tunnel pours into Beartrap Creek, which flows into the prime trout waters of the Blackfoot River, Montana

38 Mine tailings, Bingham Canyon open pit Cu mine, Utah
Developing lower grades requires larger operations with bigger pits and mines  huge tailings piles (40% of US solid waste) & require large quantities of water to process Whole mountains can be flattened to piles and rivers become acidic and Fe-stained messes Mining production involves crushing the rock, removing the ore minerals from the crush, and smelting the crushed ore to extract the metals Rainwater percolates through the left-over tailings and also contaminates the surface water and groundwater Mine tailings, Bingham Canyon open pit Cu mine, Utah

39 White streaks of zinc leached from a tailings pile and redeposited downslope. Colorado.

40 Mining Pollution Smelting releases SO2 to the atmosphere creating acid rain Ducktown TN Ducktown, when finally forced to install stack scrubbers, found that they made nearly as much money selling sulfuric acid from the scrubbers than they made from the copper! Sudbury, Ontario

41 Mining Pollution Strip Mining- remove shallow surface cover and deposit such as coal, Fe, Mn, or phosphate that extends over a broad area

42 Mining Pollution Adverse effects include: Removal of soil Exposing ore
Polluting water Disrupting drainages Asthetics Strip phosphate mine. Florida Contaminated water from a strip coal mine, Illinois

43 Dredging- excavation, sifting, and redepositing of sediment as remove placer minerals

44 Dredging rarely exposes fresh toxic ore, but severely disrupts a river valley or bed

45 Pad must be lined Note dam
Low-grade gold ore (nearly all that is now left) requires leaching of crushed ore with cyanide solutions to dissolve and extract the gold

46 Keeping cyanide from entering the groundwater system is of critical importance
Aznalcsllar, Spain 1998 50-meter-wide earth-fill dam holding waste water from a mine collapsed, spilling 7 million m3 of toxic wastewater, containing Cd, Zn, Pb, As, cyanide and other metals Toxic mud covered rich farmlands over 75,000 hectares downstream and threatened the Doñana National Park and wildlife refuge (Europe’s largest) Heap-leach pad extracting gold, Winnemucca, Nevada

47 Minimizing the impact of mineral development
Environmental regulation Most degradation is due to past mining practices that are now illegal in 1st world US smelters have stringent air quality standards Water pollution containment and land reclamation plans

48 Mining Reclamation 1977 Surface Mining Control and Reclamation Act (SMCRA) Created the Office of Surface Mining and several branches in mining states Establishes standards and funds federal and state agencies Coordinated federal and state efforts to regulate pollution, subsidence, and restoration of affected lands for coal mining Non-coal still left to individual states Once states set up SMCRA standards they may apply them to non-coal and use SMCRA funds as they see fit

49 Mining Reclamation Clean Air Act and Clean Water Act too, because these are public commons (note Tragedy of…) NEPA applies to activities on federal lands only USFS administers mining reclamation on National Forests Some abandoned mines are bad enough to qualify as Superfund sites

50 Mining Reclamation Steps in Surface Mine Reclamation
If possible: Before begin, peel back and store soil

51 Mining Reclamation Steps in Surface Mine Reclamation
Drainage control and diversion at disturbed area

52 Steps in Surface Mine Reclamation
Add or replace topsoil and immediate seeding with rapidly growing species, such as rye grass

53 Steps in Surface Mine Reclamation
After initial grass dies back, permanent species take over. Can use as habitat, grazing, etc.

54 Dredge Area Reclamation
OK, it ain’t a world-class trout stream, but it ain’t a pile of gravel either

55 Ducktown Tennessee: Superfund Site
1912: Tennessee Copper Co. smelter and tailings Once a fertile wooded eastern valley, opened 1891

56 Ducktown Tennessee: Superfund Site
Sediment from workings and devegetated area filled the reservoir behind this dam downstream

57 Ducktown Tennessee: Superfund Site
Area before restoration 1920s 9,290 hectares devastated

58 Ducktown Tennessee: Superfund Site
Area after restoration 1991

59 Minimizing the impact of mineral development
Biotechnology Use microbes (some genetically engineered) to oxidize, absorb, or leach pollutants Bioassisted leaching uses critters to liberate metals for chemical leaching Also use microbes to neutralize acid mine drainage Homestake Case Study & bio-oxidation of cyanide  nitrates Collected on tailings and cultured CN 10 ppm  0.2 ppm

60 Recycling of Mineral Resources
An elegant solution to both the extraction and waste disposal problems at once

61 Recycling of Mineral Resources
Scrap metal Not a new idea Nearly all cars are reprocessed for metal Metal recycling is a $37 billion business in US Fe >> Al > Cu > Pb > Zn > rest And saves 60 billion tons of otherwise waste (+ mining E - $ - pollution)

62 Recycling of Mineral Resources
Urban Ore Landfills may contain useful materials Palo Alto: ash from incineration of sewage sludge contained 30ppm Au, 660 ppm Ag, 8000 ppm Cu, and 6.6% P Not all cities are like this, of course, but we may find inexpensive ways to process low grade ores, since processing the sewage anyway Palo Alto Thus 1 ton of ash  1 troy oz of Au and 20 of Ag Better than most mined ores! Source? Silicon Valley and photographic industry


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