Unit VI: Earth Systems Lecture III: The Uneven Distribution of Mineral Resources has Social and Environmental Consequences.

I. Mineral Resources:    Concentration of naturally occurring solid, liquid or gaseous material that can be extracted and processed from earth’s crust at an affordable cost. Nonrenewable Energy Resources: Fossil fuels (coal, oil, natural gas) Metallic Minerals: aluminum, iron, copper Nonmetallic Minerals: sand, gravel, limestone

Life Cycle of a metal Resource

Identified Resources: Ore: Metal yielding material that can be economically extracted. The mineral is processed into useful products Identified Resources: Geologic Information about Plate Tectonics and mineral formation used to locate minerals Aerial photos and satellite images are also utilized Identified Resources: deposits of nonrenewable mineral resource with a known location, quantity and quality based on direct geologic evidence and measurements Undiscovered Resources: Potential supplies of nonrenewable mineral resources assumed to exist based on geologic theory but with unknown specific locations, quantity and quality Reserves: Identified resources from which a usable mineral can be extracted profitably at current prices Reserves can increase when new deposits are found or prices prove profitable to extract deposits previously too expensive.improved mining technlogy Strategic Oil Reserve: The United States started the petroleum reserve in 1975 after oil supplies were cut off during the 1973-74 oil embargo, to mitigate future temporary supply disruptions for example fallout with relations dealing in oil or world war. Currently suspended

** Distribution of mineral resources based on geologic processes-resources not evenly distributed. US, Canada, Russia, S. Africa and Australia supply most of the nonrenewable mineral resources. US, Germany and Russia have 8% population use 75% of resources. 4 of these strategic metal resources-Mn, Co, Cr, Pt are imported from politically unstable countries

Removing Mineral Deposits-Mining A. Surface Mining: removal of shallow deposits of minerals. Used to extract 90% of non energy mineral and rock resources and 60% of coal. Remove overburden (trees, soil, rock) and discard it as waste (spoils) Separate from gangue: commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. Waste deposited in piles called spoils/tailings

Type of surface mining depends on resource and topography. -Open-pit: machines dig holes and remove ore (Fe, Cu) and gravel and stone (limestone, marble) -Strip-Mining: extract resources that lie close to surface in large horizontal beds. A large shovel (20stories high) removes mineral and trench is filled with overburden. A new cut is made parallel to previous cut. -Mountain Top Removal: Explosives, large shovels remove top of mountain and expose seam of coal. The resulting waste rock and dirt are dumped into the streams and valleys, burying them. The sludge dam can collapse and release toxic selenium, arsenic and mercury. Mountain Top Removal

Open-pit mining: Bingham, Utah. Hole fills with toxic water

Banks of waste spoil from a strip mine in Colorado

Mountain top removal in west virginia, kentucky

Use of cyanide: cyanide-a poison toxic to humans and wildlife. Coal Mining/Transport Mountain top Removal http://www.colbertnation.com/the-colbert-report-videos/261997/january-18-2010/coal-comfort---margaret-palmer Gold Mining http://www.npr.org/templates/story/story.php?storyId=99113470 http://ngm.nationalgeographic.com/2009/01/gold/larmer-text http://www.youtube.com/watch?v=WOJDtNLm7J0 60 minutes Gold Mining in the Congo Frack Sand Mining Use of cyanide: cyanide-a poison toxic to humans and wildlife. Used on extract small amounts of gold from low-grade ore. The cyanide solution can enter soil and ground water and/or cause catastrophic spills.

Reclamation: Surface Mining Control and Reclamation Act of 1977 requires mining companies to restore most surface-mined land by grading/recontouring replace topsoil, plant vegetation monitor for 5-10 years. In most cases the reclamation efforts are only partially successful and can take decades. In arid regions, most surface mined land ends up as desert. Coal companies have lobbied to weaken the laws. Mining Impacts: Acid Mine Drainage: Acidic outflow of water from mining metals/coal This acidic water forms through the chemical reaction of surface water with rocks that contain sulfur-bearing minerals, resulting in sulfuric acid. Heavy metals can be leached from rocks that come in contact with the acid, a process that may be substantially enhanced by bacterial action. large piles of waste rock (tailings) that contains sulfur, arsenic and mercury.

B. Subsurface Mining: Removal of coal and metal ores too deep to be extracted by surface mining. Miners dig a vertical shaft and blast tunnels and to reach deposits. Better for enviro but very dangerous.

Smelting: A method of extracting metal from ore (iron and copper) Most ores are a chemical compound of the metal with other elements, such as oxygen (as an oxide), sulfur (as a sulfide) or carbon and oxygen together (as a carbonate). To produce the metal, these compounds have to undergo a chemical reaction. Smelting therefore consists of using suitable reducing substances that will combine with those oxidizing elements to free the metal. Reduction is the final, high-temperature step in smelting. It is here that the oxide becomes the elemental metal. For example iron oxide becomes metallic iron at roughly 1250°C

Solutions to acid mine drainage: Buffer-Neutralize with lime (CaCO3): increase pH; most toxic metal precipitate out. Bioremediation: sulfate reducing bacteria Constructed Wetland Lined Impoundment Cover Tailings

III. Estimating Supplies of Nonrenewable Mineral Resources A. Future supply of non-renewables depends on two factors Actual or potential affordable supply   Rate of Use B. Depletion Time: Time it takes to use a certain portion (80%) of the reserve at current rate of use. Much disagreement-rate of use, new discoveries, new extraction technologies. C. Economics of Nonrenewable Minerals Geologic processes determine the quantity and location of minerals resources; economics determines what port of the know supply is extracted and used. Most prices kept artificially low because govts subsidize to promote economic growth Economic Depletion: Cost of finding, extracting, transporting and processing exceed return.