Mining uranium in Canada Essay Example

Mining uranium in Canada Essay Example Mining uranium in Canada Essay Mining uranium in Canada Essay Introduction Uranium was foremost discovered in Canada in the mid eighteenth century on the north shore of Lake Superior in Ontario [ 1 ] . However, Canada s first economic U find was located at Great Bear Lake in Northwest Territories, exploited ab initio for its Ra content. Following, major finds were made on northern Saskatchewan and, more significantly, in the Blind River/Elliot Lake country of northern Ontario.Until the early 1980s, most of Canada s uranium production came from the Uranium City and Elliot Lake installations [ 2 ] . Following the closing of the Elliot lakes installation in 1996 due to economic instability in the uranium market and the find of higher per centum uranium oxide, all active uranium production is presently present in northern Saskatchewan, chiefly from McArthur River and McClean Lake ( Fig.1 ) [ 3 ] . Known by its high grade/high per centum of U and the Proterozoic unconformities in the Athabasca Basin as a significant beginning of uranium ores, Saskatchewan is now Canada s exclusive manufacturer of U. This paper provides an debut to the formation and geographic expedition of U in Canada, chiefly the northern Saskatchewan Athabasca basin followed by a drawn-out analysis of the techniques that are used for its extraction and processing. The first subdivision will supply background information about U and analyze the geological formation and types of the U deposits found throughout Canada, concentrating specifically in northern Saskatchewan. The following portion of the paper will analyze the extraction and processing of U from its ores which includes unfastened cavity and belowground excavation. Newly discovered extraction and enrichment engineerings will be besides discussed. The 3rd and concluding part of the study will include environmental concerns that surround the U industry followed by a decision about the importance of U to Canada s energy production and the possibility of minimising the long-run environmental impacts as a consequence of U excavation. Background Information What is uranium and why is it being mined? Uranium is one of the most widespread of all metals. Small parts of U can be found in land, ocean H2O and most normally in stones. It is a heavy radioactive component with an atomic figure of 92. Its two chiefly happening isotopes are U235 and U238. Merely isotope U235 is fissile by thermic neutrons. However, isotope U238 decays to isotope Pu239 called Pu which is more radioactive that uranium itself and can be besides used in atomic fission reactions. Uranium is found in certain minerals such as uraninite and uraninite as ores because it is easy oxidized to organize Uranium Oxide ( U3O8 ) . Little was known about the possible energy that uranium holds until it was shortly recognized that this energy could be harnessed to bring forth electric power and atomic arms. Canada, for illustration, generates an norm of 14 % of its electricity [ 4 ] from atomic reactors. The electricity is generated utilizing Canadian-built reactors called Candu, fuelled in big step by Canadian U. Therefore, the chief grounds behind the extraction of U, apart from atomic arms development, are the coevals of electricity to be less dependent on the usage of fossil fuels and to make a market where the Canadian economic system could profit from. Formation of the Uranium- Geology of Athabasca Deposit. Furthermore, the majority of Canada s known uranium resources occur in Proterozoic unconformity-related sedimentations of the Athabasca Basin in northern Saskatchewan. These sedimentations host their mineralization near the unconformity boundary in either monometallic or polymetallic mineral groups. Pitchblende, one of the common minerals where U is present in, is found in the monometallic sedimentations whereas uraninite is found in the polymetallic sedimentations. The mean class of uranium scopes from 1 % to 15 % . [ 5 ] The Athabasca Basin, shown in figure 2, lies within the northern portion of the Saskatchewan Province ( Fig. 1 ) . The deposits have been deposited during Late Palaeo-proterozoic to Meso-proterozoic, at about 1.7Ga and are separated from the underlying cellar by a major unconformity [ 6 ] . The Athabasca Group is the major preserved unit of the basin located at its base and it is composed of midst, flat-lying sequences of quartzose sandstones deposited in a proximal shelf environment [ 7 ] . Unconformity-related U sedimentations are located near to the unconformity between an Archean to Palaeo-Proterozoic metamorphic and flinty cellar, and a Late Palaeo- to Meso-Proterozoic sandstones. [ 8 ] Such sedimentations have been discovered chiefly in the 1970s, in the Thelon and Athabasca Basins in Canada [ 9 ] . The Athabasca Basin as shown in figure 2 is the Prime Minister host for such unconformity-type sedimentations. The first uranium deposition phase occurred during a diagenesis event at a temperature of about 200-250 grades Celsius [ 10 ] . In this basin, sandstones host several medium to top-quality uraninite sedimentations such as the elephantine McArthur and Cigar Lake sedimentations as shown in figure 2 [ 11 ] . In add-on the sedimentations of the Athabasca Basin correspond to estimated militias of about 1,250,000 lbs of U3O8, matching to about 500,000 dozenss of metallic uranium [ 12 ] .Due to the highly high class of U, these sedimentations represent the most profitable uranium resources in the universe [ 13 ] . In the Athabasca Basin, unconformity-related U ore sedimentations are by and large located at the intersection of several mistake waies cross-cutting the unconformity, the chief ore-controlling construction being a graphite-rich shear zone shown in figure 3. The uranium ore sedimentations are besides often hosted and surrounded by breccias in the sandstone as shown in figure below. Exploration of Uranium Next, there are several types of geographic expedition that take topographic point on countries of involvement as portion U find. The first type is called Regional Exploration which consists of assemblage and rating of bing information and farther informations acquisition from land geophysical studies to dirty and H2O analysis [ 14 ] . This degree of geographic expedition efforts to sketch countries of uranium resource potency. The 2nd type is called Detailed land Exploration which includes boring, nucleus analysis and most significantly geochemical studies as it provides the concentration of uranium nowadays in the country of involvement [ 15 ] . The 3rd type of geographic expedition is used to measure the uranium recovery rate within the country of involvement [ 16 ] . It uses systematic boring and sampling of surface/underground ores of U in order to find the recovery rate. Extraction and Processing of Uranium Furthermore, while U is in many ways similar to other extractive industries, in certain of import respects it is different. Economically it differs in footings of value and direct income generated by its production [ 17 ] . Uranium is so a really high value metal and accordingly outputs really high incomes and grosss. [ 18 ] Uranium excavation methods are typical to other types of ore excavation which includes unfastened cavity and resistance. Northern Saskatchewan contains some of the universe s richest sedimentations of U. The ore is mined belowground or in unfastened cavities, depending on the deepness of the sedimentation. Open Pit Mining Open cavity excavation occurs where sedimentations are near the surface and have a significant horizontal dimension which is found largely in the Athabasca basin of northern Saskatchewan. Next, unfastened cavity excavation is much easier than belowground excavation. However, it occupies more surface country than belowground excavation. It can typically widen for 300-400 estates and involves blaring and lading onto heavy machinery trucks that transport the U ore to the factory. [ 19 ] Open cavity mines at Cluff Lake, Key Lake and Rabbit Lake infusion ore from really rich, shallow ore sedimentations. First it must be decided if H2O in sandstone must be removed by boring drainage Wellss. Pumping to maintain H2O degrees below the ore zone may hold to go on throughout the operation. The dirt and stone overburden must be removed by mechanical shovels and immense trucks. These same shovels dig out the ore by cutting down in annular benches, organizing a broad funnel-shaped digging [ 20 ] . The ore is removed by truck to the milling works. Mined-out cavities are often lined and used to hive away shadowings. Underground excavation Underground mines are favored when the deepness and physical dimension of the U sedimentations are ill-sorted for unfastened cavity excavation. A good illustration of an belowground mine would be in the Elliot Lake part in northern Ontario and McArthur River in Saskatchewan. The sedimentations at McArthur River are so rich that unmanned equipment and remote excavation methods must be used to protect employees from high degrees of radiation underground [ 21 ] . Typical underground mining operations include such installations as service edifices, a caput frame with lading installation, conveyers, a mine waste heap and a flow of H2O from the belowground sumps pumped to the surface for usage in the factory and concentrator [ 22 ] . The country occupied by the mine above the land may be merely few estates but extends to many stat mis of belowground gaps. Following, both belowground and unfastened cavity mining involves the burden of refinable and fringy U ores and the disposal of big measures of overburden and waste stone. Another new method of extraction that minimizes the burden and disposal procedure of stones is called unmoved leaching. It is done by taking the U from the ores while injected in drill holes or ore hemorrhoids above the land. This method is merely acceptable where U is present in sandstones. In situ leaching is non really practical as most of the U in Canada does non happen in porous mineralization. Other types of remote underground mining include raise-boring, box-hole drilling and remote box-hole fillet. [ 23 ] In decision, mineable ore is by and large 75 % -85 % of ore-in-place for belowground operations and higher for unfastened cavity operations [ 24 ] . Processing/ Enrichment of Uranium Uranium milling operations are similar to chemical extractive procedures such as the bitumen from oil littorals or Fe from Fe oxide ores. A U factory consists of oppressing machinery, having bins and a chemical intervention installation. The ore is crushed into little pieces to let easier and faster fade outing rate of uranium minerals as chemicals are being applied inside the chamber. Furthermore, the solid/liquid solution gets separated and the U is chemically recovered from the liquid solution as a precipitate. This precipitate undergoes powder until it turns into a all right pulverization known as the U308 [ 25 ] . On the other manus, the solid solution, known as U shadowings which consist of unwanted stuff, is so put in slurry of finely land solids which are transferred to a shadowings pool for settling [ 26 ] . This is the end merchandise of the milling done at the Millss in northern Saskatchewan. Today segregation of the byproducts ( shadowings ) of excavation and milling is extremely regulated, and must be done in an environmentally responsible mode. [ 27 ] Further, there are other uranium compounds present in U308 that must be removed at a refinery in a series of chemical separation processes. Initially the Canadian refinery was located at Port Hope, nevertheless, all uranium refinement in Canada was moved to Blind River in 1983 due to environmental jobs caused by the accrued refinery shadowings [ 28 ] . Polishing consists of several stairss get downing with fade outing the U308 in azotic acid to organize a solution incorporating uranyl nitrate. This solution is purified and the uranyl nitrate is eventually reduced to organize uranium trioxide ( UO3 ) . This is the end merchandise of the refinement procedure, which is so shipped to Port Hope for farther processing. Conversion is the procedure of change overing the uranium trioxide from the refinery into uranium dioxide, UO2, for usage in natural U reactor fuel and into uranium hexafluoride, UF6, for enriched fuel. These stairss are performed at Port Hope, the topographic point of the l argest uranium transition workss in the universe. [ 29 ] Uranium Enrichment The aim of uranium enrichment is to bring forth fuels with an increased proportion of U235. Get downing with natural U ( 0.7 % U235 ) one can pattern enrichment procedures in footings of the concluding grade of enrichment and the sum of U235 in the dress suits ( the residuary U, depleted in U235 ) [ 30 ] . For a procedure of given efficiency, the higher the needed enrichment ( % of U235 in the merchandise ) the more natural U is required for a fixed per centum of U235 left in the dress suits [ 31 ] . Similarly, higher enrichment per centums for a fixed sum of natural U and dress suits mean more energy must be expended in the separation procedure. Multiple phases with changing enrichment values for the input and end product watercourses must besides be taken into history [ 32 ] . A measure called the Separative Work Unit ( SWU ) is used as a step of the energy used in enrichment given the multitudes and U235 contents of the provender, merchandise, and dress suits. [ 33 ] The dim ension of the SWU is mass and therefore, it is more right expressed as kg-SWU or tonne-SWU. [ 34 ] Present uranium enrichment methods exploit the little mass difference between U235 and U238 in the signifier of UF6. The engineerings now in practical usage are gaseous diffusion and centrifuge separation. Laser separation is one of the newer engineerings that are being practiced. Gaseous diffusion is the older engineering and the first to go economically successful. It depends on the fact that in a gas of given temperature the lighter molecules of U235, travel faster than the heavier 1s incorporating U238. If a gas flows past a porous membrane that allows diffusion of molecules through it so gas on the other side of the membrane will be somewhat enriched in the igniter molecule. The really little enrichment at each phase means that a sequence of 1000s of such phases, jointly called a cascade, must be used to accomplish U235 enrichment degrees of practical involvement for atomic power coevals. The gas force per unit area must be brought back up after each phase to retrieve the force per unit area loss across the membrane. The compaction used heats the gas which is so cooled. The net consequence is that big sums of electricity are used to pump, compress and chill the gas. Gas extractor engineering, the 2nd coevals enrichment method, was developed in the 1960s and since so has been replacing gaseous diffusion [ 35 ] . The physical rule involved is to whirl uranium hexafluoride in a high velocity extractor, with the consequence that the centrifugal force exerted favours the resettlement of the heavier molecules to the outer radii of the extractor. An axial circulation between the top and underside of the extractor makes it possible to pull off a somewhat enriched fraction at the top of the extractor and a correspondingly depleted fraction at its underside. A important advantage of this engineering is that it is much more efficient in its usage of electricity than gas diffusion. Third coevals enrichment engineering is based on optical maser isotope separation and a assortment of such techniques have been proposed. These rely on the fact that the energy degrees in atoms and molecules vary somewhat with mass, a phenomenon known as the isotope consequence. [ 36 ] Lasers can be accurately tuned to a frequence that selectively excites an energy degree of an atom or molecule containing, for illustration U235, but non one incorporating U238. For case, excitement of one or more such energy degrees can ensue ionisation of one of the isotope-containing species but non the other, leting electromagnetic separation. The SILEX ( Separation of Isotopes by Laser Excitation ) procedure was developed in recent old ages in Australia [ 37 ] . It relies on selective excitement to take a fluorine atom from UF6 to change over it to UF5 to organize a solid. Environmental Risks and Impacts of Uranium But why would a automaton be picking an apple in the first topographic point? Automatons are frequently used in the atomic industry because of the menace to worlds from direct exposure to atomic fuel or waste. Robots may hold to be used to mine the high class U at the proposed Cigar Lake belowground U mine. In the universe of spread outing atomic energy, radiation would necessarily go on to come in into the Earth s ecosystem from the uranium shadowings left at the mines and the atomic releases and the waste from the reactors. The in writing can hence be interpreted as demonstrating that, in such nuclearlized universe, an apple ( typifying the nutrient concatenation ) might go so contaminated that worlds would non be able to safely pick or eat it [ 38 ] Environmentally and socially, uranium excavation is perceived otherwise from other energy industries because of the of import wellness and safety concerns that appear due to the extraction and processing of U. [ 39 ] Extraction of U from its ore below the surface is inherently harmful to our environment because of the very nature of the component and because of the high class of ore mined in Saskatchewan. The greatest hazards of U excavation to the environment are taint of lakes with dissolved radioactive stuffs, ruinous failures of shadowings containment and the pollution of surface and land H2O by chemical pollutants in shadowings, notably heavy metals, acids, ammonium hydroxide and salts. In the short term, chemical pollution has caused by far the most harm. Whole groups of beings have disappeared downstream from some old uranium shadowings countries because of acidification. Unless the shadowings are decently disposed of, these jeopardies can go really damaging to planet Earth if it enters the nutrient concatenation. Next, a complex containment system was late developed for the long-run storage of a big volume of uranium shadowings in the Elliot Lake part of Ontario. Figure 4 illustrates the many degrees of H2O screen separated by butchs and dikes. The H2O helps to forestall the flight of Rn gas into the ambiance. Radon has a four twenty-four hours half life, intending that half of the Rn atoms will disintegrate in four yearss [ 40 ] . The decay merchandises of Rn are solid stuffs, including three assortments of Po. If radon flights into the air from the chasing heap, lead-210 and polonium-210 will be deposited on the flora and will happen its manner into the nutrient concatenation. The different H2O degrees besides allow for solid radioactive stuffs such as Ra to be precipitated out, intending that these solids will roll up at the underside of each pool and will non go through into the following degree of H2O lower down, because of the presence of the butch. In 1979, a new shadowings dike built with the latest engineering all of a sudden collapsed in Churchrock, New Mexico [ 41 ] .The ensuing spill was the greatest inadvertent release of radioactive stuff into the environment prior to the Chernobyl atomic catastrophe. At modern mines in Canada, the short-run environmental impacts are frequently caused by non-radioactive parametric quantities. For illustration, increased degrees of salts may hold caused a displacement in species downstream of one U mine in Saskatchewan. Construction, geographic expedition and route edifice in countries antecedently untouched by industrial activity frequently cause the most terrible short-run impacts. Furthermore, in an enrichment works with lone natural U as input, the lone radioactive stuffs present are those already contained in the provender. No other radioactive stuffs are produced as they would be in a atomic reactor. The dress suits, like the natural U, are merely mildly radioactive and are stored as low UF6, which must be converted for disposal. The chief environmental concerns are chemical wastes caused by the refinement of U. UF6 reacts with H2O to organize extremely caustic hydrofluoric acid, and hint sums of arsenous anhydride and other heavy metals besides need to be controlled. Therefore chemical toxicity instead than radiation is the primary concern, and the safety systems are similar to those used in other chemical workss. For illustration, the environmental impact survey for the National Enrichment Facility in Lea County, New Mexico, found the environment impacts in all countries are at most moderate in a few countries such as transit during building and UF6 waste cylinder disposal [ 42 ] . This undertaking was approved and is now under building [ 43 ] . In July, 2008 a uranium waste leak at Tricastin in France, resulted in 6 three-dimensional metres of H2O incorporating U to be spilled into two local rivers [ 44 ] . Tricastin is the site of France s largest gaseous diffusion works, but it besides has four power reactors that supply electricity to the enrichment works. Port Hope has had jobs with uranium operations for many decennaries [ 45 ] . It has an estimate of 2 million three-dimensional metres of historic refinery wastes assorted with dirt dating from the 1930s to the 1970s [ 46 ] . In add-on, a new undertaking regulated in port hope aims to build waste direction installations for redress of the waste sites, and supply long-run monitoring and care of the installations. Escape from the big UF6 transition installation at Port Hope was found in 2007 [ 47 ] . Uranium, arsenic and some fluorine compounds had been leaking into the dirt under the works, since the start of the refinery. Contamination of the seaport may besides hold occurred from contaminated groundwater fluxing under the works. Extensive redress was undertaken and the works was re-opened in September 2008 [ 48 ] . Finally, important nursery gas ( GHG ) emanations are frequently attributed to atomic power because of the big sums of electricity used gaseous diffusion works which is being generated from coal. A Canadian enrichment works is most likely to be located in Ontario and Saskatchewan due the high favourable sum of atomic reactors. In 2005 Environment Canada calculated CO2 tantamount emanations per kWh of electricity for each state by burdening the emanation per-unit-energy for each coevals engineering by the per centum usage of that engineering in electricity production [ 49 ] . Saskatchewan electricity is produced chiefly from coal and gas and the emanation per kWh is 880g. [ 50 ] Ontario generates about 75 per centum of its electricity from atomic and hydro, and the mean emanation per kWh is 220g. Entire one-year emanations from a Capenhurst-type enrichment works of 1 M kg-SWU size would therefore be about 11,000 metric tons of CO2 for Ontario and four times that for Saskatchewan [ 51 ] . This is a comparatively little sum compared to the 34 M metric tons emitted by the Ontario electricity coevals system as a whole [ 52 ] . As CO2 emanations from all provincial electricity coevals systems are expected to diminish in the hereafter. Decision The building of the refinery and the development of atomic energy is a moral inquiry because it concerns life and decease on this planet. It is non merely a proficient affair refering economic sciences and energy beginnings. The lives of people everywhere are affected by uranium refineries, atomic reactors and atomic arms. Therefore the determinations must be made by all of these people, non by alleged experts. [ 53 ] Is Uranium needed? Uranium is an of import sector of Canada s chief natural resources. Canada s uranium production in 2007 was 11,180 metric tons of uranium oxide of which 9,476 metric tons was uranium metal. This is about 23 per centum of universe end product. About 9 per centum of the universe s U ore militias are present within the Athabasca basin of northern Saskatchewan in Canada. It presently has 22 CANDU reactors operated by public public-service corporations and private companies bring forthing on mean 14 % of the entire electricity. Exploration is still on-going and future mines are being proposed and will shortly come to production such as the Cigar Lake, Midwest Lake and the Millennium basin ( fig ) . This is really advantageous as it greatly expands the Canadian economic system and decreases the ingestion of fossil fuels, therefore deceases C dioxide emissions into the ambiance. However, the waste merchandises that are being produced from the extraction to the use in atomic reactors of U su ch as Pu and low U are so really harmful to the environment. That s why many people believe that the long-run danger to the planet caused by the spread of atomic engineering is greater than any benefit that U has to offer. Therefore, minimising the long term environmental impact of U is a really good proposal for the safeness of the environment/ecosystem and the human wellness. In decision, this could be done by enforcing rigorous environmental regulations where U ore is shipped off from the mine site. The extraction of U should be so taken to a distant topographic point where it wo nt impact the surrounding environment. Finally, if the factory is near to the operated mine, so the radiological jeopardy of the shadowings should besides be collected and treated in order to do it less harmful to the environment by minimising the radiation of the half life. Mentions Books: Holman, G.J. ( 1982 ) . Impacts if Canada s Uranium Mining Industry. Calgary, Alberta. Canadaian Energy Research Institute, 1-6pp OECD. ( 2004 ) . Uranium 2003: Resources, Production and Demand. Moulineaux, France. International Atomic Energy Agency, 97-100pp Harding, J. ( 2006 ) . Canada s Deadly Secret. Saskatchewan U and the planetary atomic system, Fernwood Publishing, Halifax and Winnipeg, Alberta. 118pp Bodansky, D ( 2000 ) . Nuclear Energy: Principles, Practices and Prospects, 2nd edition. New York: Springer. Bulletin of the Atomic Scientists. 201-204pp Lamarsh, John R. and Baratta, Anthony, J. ( 2001 ) .Introduction to Nuclear Engineering, 3rd edition. Upper Saddle River, NJ: Prentice Hall. 176-190pp Internet: Veslud, C ( 2007 ) . 3D mold of uranium-bearing solution-collapse breccias in Proterozoic sandstones ( Athabasca Basin, Canada ) Metallogenic readings. Computers and Geosciences. Quebec, Canada, 97-98pp Jefferson, C ( 2002 ) . Unconformity-associated uranium sedimentations of the Athabasca basin, Saskatchewan and Alberta. Geological study of Canada. Ottawa Canada. 273-274pp Leewuwen, J ( 2006 ) . Energy from Uranium. Oxford Research Group, Storm and Smith 2005. Oxford United Kingdom 20-22pp