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Lectures 32 & 33 - Mineral Resources & Mining.docx
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Department
Environment
Course
ENV100Y5
Professor
Monika Havelka
Semester
Winter

Description
ENV100 Chapter 11 Notes Jan 6 & 8, 2014 Lecture #32 & 33: Mineral Resources & Mining This lecture will help you understand: − The main types of mineral resources − How mineral resources contribute to our economy and society − The major methods and stages of mining − The environmental and social impacts of mining − Reclamation efforts and mining policy in Canada − Some ways to encourage sustainable use of mineral and other nonrenewable resources Central Case: Mining Central Case: Mining for… cell phones? • Cell phones and many other high-tech products contain Coltan, used to make tantalum capacitors. -  Coltan = columbite + tantalum • Democratic Republic of the Congo: “Resource Curse” -  Since 2000, >5 million died and millions more fled • Congo at war -  Soldiers control mining operations -  Profits from Coltan sales financed the war = “conflict minerals” - In such countries, they don't have a legal structure in place for the mining industry →proceeds from mining do not stay in the country. They are used to finance war. • Most tantalum from the Congo is smuggled into China • Artisanal Mining - refers to an activity that is done informally, low-tech, less equipment, small operations, traditional types of activities. Ex: Fishing → 1 or 2 fisherman on a vessel fishing. In the case of mining, it almost always has negative environmental impacts. • People doing artisanal mining in national parks killed wildlife, cleared rainforests, polluted rivers, caused uncontrolled erosion. • Artisanal Mining - usually illegal, unregulated, no safety precautions (Sierra Leone). Rocks provide the mineral resources we need to conduct our lives • Rock = solid aggregation of minerals. Ex: Granite. • Mineral = naturally occurring solid inorganic chemical element or compound with a crystal structure, a specific chemical composition, and distinct physical properties. Ex: Quartz. − Inorganic - thing of biological origin are not minerals. − Crystal Structure - refers to the orderly arrangement of the atoms that actually make up the mineral. • Some things that are not minerals: (Can you figure out why?) -  Bone → biological origin. Fossilized bones are replaced molecule by molecule by minerals. -  Coal → Not a mineral b.c i) it is an aggregate ii) it originates biologically. - Amber -  Synthetic diamond or cubic zirconia -  Water (but ICE is a mineral) Ice → naturally occurring, crystal structure etc. -  Lava, magma -  Volcanic glass → no crystal structure. It is considered as a rock. Page 1 of 13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 • Tantalite is a mineral that consists of the elements oxygen, iron, manganese, and tantalum bonded together in specific proportions (Fe,Mn) Ta2O6, and occurs most commonly in pegmatite (a type of igneous rock similar to granite). • When we mine Coltan, we are interested in getting the element Tantalum. Mineral resources can be metals or non-metals • Metal = chemical element that is shiny, opaque, malleable, and conducts heat and electricity − Precious metals (gold, silver, platinum) − Base & ferrous metals (iron, nickel, copper, zinc, etc…) • Non-metal = basically everything else − Fertilizers, Salt, Building stone,Aggregates, Clay, Asbestos, Gemstones, Uranium and other fuels − Not-metallic sources are economically very important (more so than precious metals). Building Stone, Aggregates → needed for building roads. − We are fundamentally dependent on minerals. We obtain mineral resources by mining • Mining = systematic removal of rock, regolith, or other materials for the purpose of extracting minerals of economic interest. − Most minerals are widely spread in low concentrations; miners and geologists must try to locate concentrated sources → economically extractable. − We are looking for deposit of high grade →a lot of the material we're interested in. • Deposit = natural occurrence of a resource • Grade = level of concentration of ore in a deposit • Ore = economically valuable material in a deposit. − The material we're going to extract is called the Ore. − Native = uncombined with other elements (i.e., not in the form of a compound) • Gangue = waste rock and non-valuable minerals. Mining is an important industry both globally and for Canada • Much of Canada’s economic history has been based on extractive industries ( such as mining, oil extraction, forestry & fishery). -  Many towns exist mainly because of their mining history. • Mineral production contributed approx. $63 billion to Canada’s GDP in 2011 • 21% of the value of exported goods from Canada. • The non-fuel (non-oil) mining industry, together with processors and manufacturers of products provided roughly 1 in every 46 jobs in Canada in 2011. • Although mining has negative environmental impacts, it is imp to address that we are fundamentally dependent on the mining industry. Thus, it is necessary to make the industry more responsible & more efficient at work w/o having significant env/social impacts. There are different types of mines •  The type of mine depends on what you are mining and what type of deposit it is •  Underground (subsurface) mines •  Surface mines (4 main types): 1) Strip mine 2) Mountaintop removal Page 2 of 13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 3) Open-pit mine 4) Placer operations Subsurface mining: Takes place in underground tunnels and shafts • Gold, zinc, lead, nickel, tin, diamonds, phosphate, salt, coal, uranium, and many others • Deepest mines extend nearly 4 km underground • The most dangerous form of mining -  Dynamite blasts, collapsed tunnels, toxic fumes, coal dust (extremely explosive). • Subsurface mines can affect people years after they close -  Mines can collapse, acid drainage, polluted groundwater, sinkholes damage roads and homes, etc. Today, many underground mines have a safe room that miners can go to in case of explosions. Mining today is much more safer, more regulated than it was back in the 1900s. Solution mining: Dissolves resources in place for extraction • Solution mining [in-situ (in place) recovery] = resources in a deep deposit are dissolved in a liquid and siphoned out. -  Can be surface or subsurface • Inject solvent (water, C2 ), dissolve the material & suck it back out. Used for things that dissolve easily → Salts → lithium, boron, bromine, potash, copper, uranium • Efficient type of mining - less manpower, less disturbance at the surface. But we don't entirely know what is happening underground. • Less surface area is disturbed than in other methods - Acids, heavy metals, uranium can accidentally leak into groundwater -  Subsidence, ground collapse Surface mining: Strip mining removes surface soil and rock • Strip mining = layers of soil and rock are removed to expose a resource close to the surface. Stripping all of the overburden. Usually it's done for things that are continuous & close to the surface. Ex: Coal (it occurs in long seams that are very continuous & close to the surface), Tar Sands. • Overburden = overlying soil and rock that is removed by heavy machinery - After extraction, each strip is refilled with the overburden • Used mainly for coal, oil sands, sand, gravel. • Destroys natural communities over large areas and triggers erosion. • Can lead to acid mine drainage Page 3 of 13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 Acid mine drainage is a problem for both surface and subsurface mines • Acid mine drainage = sulfide minerals form sulfuric acid and flow into waterways • Forms from Sulfur. Mostly associated with metal mines. Metal mines have pyrite in them. Occurs in metal mines which has these elements in them. • If you have a coal or metal mine (w/ pyrite) + crushed rock + man-made openings, water is going to come in & mix with the Sulfur to create Sulfuric Acid. When this sulfuric aid runs off & joins the stream, it affects the surface & kills the organisms. - As the sulfuric acid runs off, it leaches metals from the rocks, many of which are toxic -  This toxic liquid is called leachate - AMD is probably the biggest problem associated with mining in Canada today. - Really hazardous to ecosystems. • Effluent = any toxic, contaminated liquid runoff • Mining industry in NorthAmerica takes AMD very seriously • Mine Environment Neutral Drainage (MEND) established in Canada in 1988 -  Development of new technologies and approaches to prevent, control, and remediate the effects of acid mine drainage - Metal Mining Effluent Regulation (MMER) in 2002 -  Established limits for cyanide, arsenic, and other hazards Surface mining: Mountaintop removal mining reshapes ridges and valleys • Yes, believe it or not – an extension of strip mining • Entire mountaintops are blasted off and the rock waste is dumped into valleys (valley filling) • Used for coal in theAppalachian Mountains of the eastern U.S. • Like strip mining, surface mining is used for resources that are continuous & occur in long seams. • Economically efficient • Degrades and destroys vast areas • Pollutes streams, deforests areas, erosion, mudslides, and flash floods People living in communities near the sites experience social and health impacts • Mine blasting cracks foundations and walls • Psychological distress from constant noise Page 4 of13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 • Floods and rock slides affect properties • Overloaded coal trucks speed down rural roads • Coal dust and contaminated water cause illness • High-efficiency mining reduces the need for workers → No economic benefits. Surface mining: Open-pit mining requires immense holes at the surface • Used for less continuous, lower-grade materials. Typically remove a lot of rock for a small amount of material. Ex: Gold, Silver. • Used with evenly distributed minerals. -  Terraced so workers and machines can move about • Copper, iron, gold, diamonds, coal • Quarries = open pits for clay, gravel, sand, stone (limestone, granite, marble, slate) • Huge amounts of rock are removed to get small amounts of minerals • Habitat loss, aesthetic degradation, acid drainage • Abandoned pits fill with toxic water • Pic: Bingham Canyon Copper Mine in Utah, Diavik Diamond Mine in NWT. Canada is the 2nd-3rd largest diamond producer in the world. • Canadian Diamonds - non-conflict, certified diamonds. Surface mining: Placer mining uses water to isolate heavy minerals • Can be done with any minerals that are dense. Heavier than regular rock. Ex: Gold, Diamonds, Coltan. • Placer mining uses running water, miners sift through material in riverbeds - Coltan miners in Congo; California’s Gold Rush of 1849; British Columbia in 1858; Klondike in 1896. -Low-tech material. Metal scoops. • Commonly used for gold, gems • Debris washed into streams makes them uninhabitable for wildlife • Disturbs stream banks, causes erosion , harms riparian plant communities Some mining occurs in the ocean • Not economically or technologically feasible. • Most deepwater mining (both oil drilling & mining) is technologically very challenging → Oil Spills. • Some minerals can be extracted from seawater or dredged from the ocean floor - Sulfur, phosphate, calcium carbonate (for cement), silica (for insulation and glass), copper, zinc, silver, gold. • Manganese nodules = small, ball-shaped ores scattered across the ocean floor - Mining them is currently uneconomical • Hydrothermal vents may have gold, silver, zinc - Probably similar to the geologic environments in which many of today’s ore deposits originally formed. - Mining would destroy habitats and organisms and release toxic metals that could enter the food chain. Mining affects air, water, land, health • Impacts depend on: -  the geological and ecological setting Page 5 of13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 -  mine procedures and technologies -  company policies and management processes -  the stage of mining -  the laws and policies in place • 1 of the really big ethical questions: − Do all Canadian mining companies use Canadian environmental standards when carrying out mining in other countries? → Sometimes they do, sometimes they don't. Canadian public needs to encourage mining companies to maintain standards in other countries as well → reduce negative environmental impacts. • Impacts on air: - Pollution from smelting and refining -  Dust from waste rock and tailings piles - Tailings - waste crushed up stuff mixed w/ chemicals • Impacts on water: -  Effluents containing toxic metals -  Toxic leakage from tailings ponds -  Effluents containing chemical reagents - Acidic and saline mine drainage • Impacts on land: -  Construction of roads and buildings -  Stripping of surface vegetation and soil -  Mine shafts and excavation pits -  Ground subsidence -  Rock waste and tailings piles • Impacts on human health: -  Exposure to radiation (Uranium) -  Black lung disease -  Coal dust explosions -  Mine collapse and rock bursts -  Health impacts of pollution from smelting, acid drainage, etc. -  Exposure to asbestos (mesothelioma → rare form of lung cancer, etc.) (Quebec) Different stages of mining have different impacts • Exploration • Mining/milling • Refining/smelting • Post-operational Exploration generally has the lowest environmental impacts • Exploration stage: looking for the deposits. -  Relatively low impacts -  Habitat disturbance -  Noise from flyovers -  Discharge of contaminants from drilling, trenching, road access Page 6 of 13 ENV100 Chapter 11 Notes Jan 6 & 8, 2014 Mining and milling can have more significant impacts • Mining/Milling stage: taking the rock out of the ground. -  Dust, noise -  Land disruption -  Increased erosion, siltation - Acid mine drainage -  Heavy metals in ore and tailings -  Organic compounds in chemical reagents -  Cyanide, ammonia used to separate ores -  Waste rock piles and tai
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