Mineral Resources in Canada An Overview on Mining and Metal Recycling

Transcription

1 Resources Processing 58 : 3 8 (2011) Review RESOURCES PROCESSING Mineral Resources in Canada An Overview on Mining and Metal Recycling Shafiq ALAM Faculty of Engineering and Applied Science, Memorial University, St. John s, NL, Canada A1B 3X5 Abstract Canada holds very rich mineral resources. Many world-class mining companies, such as Vale, Xstrata, Barrick, Teck, Rio Tinto etc. are involved in producing different commodities including base and precious metals from their mines located all over Canada. While virgin materials will remain the primary source of metals for the growing world, considering its sustainability and economic benefit, the policy-makers, environmentalists, and engineers in Canada are now considering metals recovery and recycling from its secondary sources to make the modern society environmentally friendly. Canada s metals recycling sector is mature and extensive and consists of more than 2,800 firms including brokers, peddlers, collectors, processors and consumers. In 2006, Teck Cominco first started recycling metals from electronic scraps in their integrated metallurgical facilities at Trail which is located in British Columbia. Although most recycling firms are practising conventional methods to recover metals from the waste materials, some Canadian researchers have considered the needs of future generations and, as such, are now active in developing sustainable technologies. This paper gives an overview on metallurgical industries and metal recycling in Canada, focusing on recent developments on scrap mining and its technological advancement. Key words: Canadian mining, Mineral resources, Metallurgical industries, Metal recycling, Copper, Zinc 1. Introduction Canada is one of the top mineral producing countries in the world. The mining industry in Canada is very active because of its huge mineral deposits located all over this large country. Many organizations, including the federal Department of Natural Resources (NRCan), have recognized that Canada provides an especially favourable climate for mining, because the taxation of the mining industry in this country ranks in the low-to-middle range on an international scale. However, like elsewhere, mining has an impact on soil, water and air quality, fish and wildlife habitats, and public health. Considering its adverse effects, metallurgical industries are now adopting sustainable process technologies, such as hydrometallurgy, to reduce their environmental burden. The other option is to recover metals from its secondary Paper presented at the 8 th Japan/Korea International Symposium on Materials Science and Resources Recycling, June 2010, Seoul, Korea Accepted 5 February, 2011 Vol. 58, No. 1(2011) sources, the only other terrestrial supply currently available. Recycled metals from waste resources always have environmental advantages over mined or primary source metals. Recycling also reduces the volume of waste generation, thus helping to protect the environment. While virgin materials play an important role for minerals and metals production from its primary sources, Canada also generates huge amounts of recyclable waste materials containing valuable and pay metals that are mostly land filled. Considering the increasing cost of land filling, and the decreasing grade and increasing complexity of mineral reserves, recycling is becoming popular in Canada. According to a 1993 report prepared by the Natural Resources Canada (NRCan), a total of 344 firms were indentified across Canada that were involved in the collection, sorting, recycling, and reprocessing of metals-bearing scrap, byproducts and waste. However, the current estimate by NRCan is that over 2,800 firms are involved in the recycling of metals, which is an encouraging amount. 3

2 Shafiq ALAM In the metals industry, recycling is one of the most effective ways of saving energy. Moreover, capital and operating costs are much lower for recycling metals from scrap than for production from virgin ore. The bulk sources of scrap mining are: electronics wastes that include considerable amounts of copper and precious metals, and scrap automobiles that include zinc-coated steel. Recently, the amount of metallic wastes has been rapidly increasing because of faster obsolescence of consumer electronic devices as the rate of technological innovation accelerates. In addition, in North America, there are spikes from one-off events such as the phase out of analog television broadcasts suddenly rendering millions of old sets obsolete. As a result, the recovery and recycling of metals from these wastes is necessary to preserve the environment and metal resources. One of the more challenging aspects of recycling electronic waste is the heterogeneity of the material. Most recycling to date has been achieved by smelting the electronic waste, often using combustion of the plastic portion to partially fuel the process. This may result in toxic emissions, particularly dioxins, and loss of several metals into the slag phase 1. However, recent developments in pyrometallurgy have minimised those problems. The hydrometallurgical processes have been under development for several years to make metals recycling more sustainable and environmentally-friendly 2 5. The following sections describe different aspects of metallurgical and metal recycling industries in Canada. 2. An Overview of Minerals Production in Canada Minerals are one of the largest natural resources in Canada and many mining companies are involved in producing minerals from their different mines. Among them Vale, Xstrata, Sherritt, Barrick, Teck, Rio Tinto, HudBay Minerals Inc., etc. are some giant metallurgical companies who have their mining operations facilities, including world-class pyro- and hydro-metallurgical process plants, based in Canada. Recently Vale started constructing a multi-billion dollar hydrometallurgical process plant in Long Harbour, Newfoundland to process nickel sulphide concentrate from their Voisey s Bay mine in Labrador. The plant is set to start production of nickel, copper and cobalt in early 2013 using hydrometallurgical techniques that include oxidative pressure leaching, solvent extraction, and electrowinning 6. As shown in Table 1, at least 11 metallic and 17 4 non-metallic commodities are produced by the Canadian mining and mineral processing industries that add an average of 3.5% to the Canadian economy. In 2008, the overall value of production totaled more than C$103 billion. This amount includes the value of production from Canadian mined ores, concentrates, and aggregates, which rose substantially in 2008 to a record C$45.3 billion. The remainder represents the value of production that came from the smelting and refining of domestic and imported ores, concentrates and recyclables; steel and aluminum production; and oil sands mining. Canada is one of the world s largest exporters of minerals and metals. The export of these commodities and refined mineral products has had a significant impact on Canada s overall merchandise balance of trade and on the national standard of living. The United States is the leading destination for Canada s minerals and mineral product exports with C$53.9 billion in 2008, which represented 57% of exports. Following this are the European Union at 17.7%, and Japan (Canada s third largest export customer) at 4.8%, China at 4.2%, and Mexico at 1.2%. Exports to the top 20 countries accounted for about 95% of Canadian minerals and mineral product exports. China is an important customer for Canada s mining and mineral processing industry. Canada exported C$4.0 billion in minerals and mineral products to China, up from C$3.0 billion in 2007 and C$2.5 billion in Table 2 shows the list of some world-class mining companies with their mines and metallurgical process plants in Canada. This table only shows a partial list of mines and process facilities. Details can be found in the Natural Resources Canada s website at Taseko Mines Limited has their copper mines in Gibraltar that uses Solvent Extraction-Electrowinning (SX-EW) process. Some of the other big mining companies are Imperial Metals Corp. (Huckleberry mines), Breakwater Resources (Langlois, Myra Falls mines), Inmet Mining (Troilus mine) and North American Palladium Limited (Lac des Iles mine). 3. Metals Recycling in Canada Recycling extends the efficient use of minerals and metals, reduces pressures on landfills and incinerators, and results in major energy savings relative to primary production. As a result, metal recycling from its waste materials is a major concern of the policy-makers and environmentalists. Recycling industry is one of the thriving industries RESOURCES PROCESSING

3 Mineral Resources in Canada An Overview on Mining and Metal Recycling Table 1 Production of leading minerals in Canada 7 Volume Value Commodities 2007 (r) 2008 (p) 2007 (r) 2008 (p) (000 tonnes except noted) (C$ millions) Metals: Nickel , ,856.2 Copper , ,438.0 Gold (kg) 102,211 94,820 2, ,823.6 Iron ore 32,774 31,273 2, ,426.8 Uranium (tu) 9,100 8,702 2, ,488.2 Zinc , ,268.4 Platinum group (kg) 21,925 21, Cobalt (t) 4,289 4, Silver (t) Lead Molybdenum (t) 6,819 7,724 x x Non-Metals: Potash (K 2O) 11,085 10,455 2, ,243.2 Diamonds (000 carats) 17,144 14,803 1, ,403.6 Sulphur, elemental 7,456 7, ,388.5 Cement 14,462 14,028 1, ,792.1 Sand and gravel 240, ,646 1, ,496.1 Stone 149, ,825 1, ,373.1 Sulphur, in smelter gas Salt 11,970 14, Lime 2,134 2, Peat 1,282 1, Clay products na na Gypsum 7,562 5, Quartz (silica) 1,987 1, Nepheline syenite Soapstone, talc, pyrophyllite Chrysotile (asbestos) x x x x Coal 69,131 68,106 2, ,292.3 Note: (na) Not available; (p) Preliminary; (r) Revised; (x) Confidential. in the world at present. Canada and many other countries are stepping up their recycling operations. With everything to gain and nothing to lose, many countries including Canada have made government policies regarding recycling and sustainable metal recoveries. The commitment of the Canadian government is evident from the report published by the Natural Resources Canada 8. More than 2,800 firms across Canada contribute towards Canadian metal recycling sector that salvages an estimated 10 million tones of metals each year, valued at roughly C$3 billion. Table 3 shows the list of some metals that are being recycled in Canada from their sources. Details can be found in the National Pollutant Release Inventory (NPRI) of Environment Canada. Vol. 58, No. 1(2011) Canada s recycling program is run by both federal and provincial government. Federally, Natural Resources Canada oversees most of the work on industrial recycling, while Environment Canada coordinates more of the programs that affect consumers. The provinces oversee blue box programs for the recovery of recyclable household wastes including metallic wastes such as aluminum, steel (often coated), and e-waste. Statistics Canada s province-wide survey showed that Quebec, Ontario, and British Columbia are the leading provinces that report the highest recovery rates in the country. Alberta has implemented the first provincial waste electronic and electrical equipment recycling program. The following sections discuss the recycling of some base metals 5

4 Shafiq ALAM Table 2 Metallurgical industries producing metals from Canadian mines Name of the Industry Name of Mines Metallurgical Facilities Metals Produce Vale Inco Xstrata Teck HudBay Minerals Copper Cliff (ON), Thompson (MB), Voisey s Bay (NL) Kidd Creek (ON), Fraser, Craig, Raglan, Montcalm, Brunswick (NB) Highland Valley (BC), Duck Pond (NL), Hemlo Trout Lake (MB), Flin Flon (MB) Port Colborne SX-EW, Thompson smelter and refinery, Copper Cliff smelter, Hydrometallurgical plant in Long Harbour, NL (Start 2013) Kidd Creek metallurgical plant, Falconbridge smelter in Sudbury, Fraser-Morgan metallurgical plant Trail metallurgical plant in British Columbia Flin Flon metallurgical plant in Manitoba Table 3 Some Recycled Metals in Canada 9 Nickel, Copper, Cobalt, Precious metals Copper, Nickel, Cobalt, Zinc, Lead, Precious metals Zinc, Lead, Precious metals Copper, Zinc, Precious metals Barrick Hemlo (jointly with Teck) Trail (with Teck Cominco) Gold Sherritt International Fort Saskatchewan refinery (SK) Nickel, Copper, Cobalt Note: BC British Columbia, SK Saskatchewan, MB Manitoba, ON Ontario, NB New Brunswick, NL Newfoundland and Labrador. Recycled Metals Major Sources of Secondary Feed Recycled Amount in 2008 (Tonnes) Copper Electronic scrap 40,934 Zinc Galvanized steel scrap from junk automobile 45,195 Lead Lead batteries 51,863 Nickel NiCd batteries 8,164 Cadmium NiCd batteries 669 Aluminum Scrap automobiles and aluminum cans 6,320 6 (copper and zinc) in Canada from their waste materials. 3.1 Copper Recycling A large amount of copper is locked in the metallic wastes especially in the electronic waste. This e-waste should be viewed as a resource rather than a waste material since it contains levels of valuable metals often ten times higher than that can be found in naturally occurring ore deposits. It is assumed that an increasing amount of computer and other electronic equipment will become obsolete in upcoming years because of the current trend in information and communications technologies (IT). The situation is already causing great concern, because disposing of such equipment in landfills has a significant impact on the environment in Canada. According to Environment Canada statistic, in 2005, about 156,000 tonnes of e-scrap were generated in Canada of which about 67,300 tonnes were sent to landfills. To help protect the environment, Canada has started collection of IT equipment for recycling. Various collection options are available that include residential pick-up, drop-off at indoor and outdoor depot, and drop-off at computer retailer. All collected electronic wastes are processed manually for separating glass, plastics and metallic parts that include ferrous metals, aluminum, copper, lead, zinc, and precious metals. There are several smelters in Canada that receive separated metallic parts for further processing. The Horne smelter in Rouyn- Noranda is one of them that processes IT equipment for copper recycling. This smelter is a custom copper smelter which uses both copper concentrates and electronic equipment as feedstock to produce a 99.1% copper anode, which is shipped to Xstrata Copper s Canadian Copper Refinery in Montreal to convert into copper cathodes. In 2006, Teck Cominco started recycling metals from electronic wastes in their worldclass integrated metallurgical facilities at Trail, B.C. In that process shredded electronic wastes are combined with zinc-rich slag, which is fed into a furnace where e-waste is decomposed at high temperature above 1200 C. During , Teck Cominco received a total of 3,000 tonnes of e- waste to process in their Trail facilities. So far, in Canada, copper is being recycled using smeltingrefining processes. No hydrometallurgical techniques are commercially available; however, research is in-progress in different Canadian universities and research companies to develop RESOURCES PROCESSING

5 Mineral Resources in Canada An Overview on Mining and Metal Recycling Fig. 1 A Typical Process Flowsheet for Zinc Recycling from Galvanized Steel Scrap. recover zinc from the galvanized steel scrap using hydrometallurgical techniques, where galvanized steel scrap is de-zinced to produce zinc-free black steel ready to be used as feed in a steel plant. Zinc was recovered as a value added product. This patented work 10 has been carried out at Process Research Ortech Inc., a metallurgical research company located in Mississauga, Canada. In this process zinc in the scrap was leached in an alkaline lixiviant of sodium hydroxide followed by solvent extraction using oxine type of extractant (LIX-26). Finally, zinc was recovered from the aqueous solution as zinc carbonate by precipitation method using sodium carbonate. A typical flowsheet of this zinc recycling process is shown in Figure 1. A part of this hydrometallurgical process is currently being practiced in Dofasco s steel manufacturing plant in Hamilton, Ontario. Main advantages of zinc recovery from galvanized steel scraps are: 1) it allows sustainable development, 2) it minimizes environmental impact, improves air quality and decreases hazardous waste production in steel plants, 3) it ensures steel product quality, 4) it is economical as there are opportunity for zinc marketing, 5) recycled zinc allows decrease of environmental damages from primary zinc production, and 6) it decreases green house gas emissions. sustainable copper recycling processes from its waste materials. 3.2 Zinc Recycling About 80% of world s zinc is used for galvanizing. The feedstock in the manufacture of steel is often waste galvanized steel recovered from scrap automobiles. Such products are a low cost source of feedstock. However, during pyrometallurgical treatment, high temperature causes the zinc in the galvanized coating to be volatilized. This volatilized zinc goes to the environment in the form of dust associated with cadmium and other toxic metals. In North America, every year more than 2.5 million tonnes of galvanized steel scrap containing 3% zinc is processed in steel manufacturing plants. This produces 0.5 million ton/year of zinc dust which is mostly land filled. At 15% zinc in zinc dust, this represents 75,000 tonnes of zinc per year, which is stored on site as hazardous wastes. The zinc dust production could be double in the next 5 10 years with increased recycling of auto scrap. According to the US Environmental Protection Agency (EPA), this zinc dust is classified as a hazardous material. Considering this, the author of this paper has developed a sustainable process to Vol. 58, No. 1(2011) 4. Conclusion Although Canada has vast mineral resources, there is no shortage of metals scrap in this country. Then why has Canada been relying on mining? One of the barriers to resource recycling in Canada is tracking down the scrap metal and determining recycle rates. Canada s large landmass and low population density mean increased costs for material recovery as compared to Japan, Korea, Europe, for example, where a more extensive transportation infrastructure is in place. Recyclable materials are generally collected in urban centres, where most waste is generated, but the recycling plant (smelter) are generally located close to mine sites, in rural areas, thus necessitating transport over great distances. However, the collection and transportation system is now being improved as the federal government is enhancing recycling activities as a priority in its Mineral and Metals Policy. As a part of Canada s commitments under the Kyoto Protocol to reduce greenhouse gas emissions, new initiatives are underway to increase metals recycling. Another barrier is technology. The recycling sectors are much segmented, with secondary smelters targeting easy to 7

6 Shafiq ALAM process scrap to maintain profit margins, i.e. copper and brass, used aluminum beverage cans, stainless steel scrap, etc. Scrap that is difficult to process and requires several processing steps still ends up at primary smelters that are equipped to recycle complex metallic composite materials, such as electronic waste, and the refining facilities enable the extraction of all the valuable including precious metals. The recycling industry is now considering implementing hydrometallurgical processes for value added metals recovery. References 1. J. Cui and L. Zhang: Metallurgical Recovery of Metals from Electronic Waste: A Review, Journal of Hazardous Materials, 158, pp (2008) 2. Y.J. Park and D.J. Fray: Recovery of High Purity Precious Metals from Printed Circuit Boards, Journal of Hazardous Materials, 164, pp (2009) 3. M.S. Alam, M. Tanaka, K. Koyama: Removal of Impurity from the Electrolyte in the Cuprous EW Process, Japanese Patent, Serial No (2009) 4. T. Oishi, K. Koyama, S. Alam, M. Tanaka, J.-C. Lee: Recovery of High Purity Copper Cathode from Printed Circuit Boards using Ammoniacal Sulfate or Chloride Solutions, Hydrometallurgy, 89, pp (2007) 5. M.S. Alam, M. Tanaka, K. Koyama, J.-C. Lee: Energy Saving Green Technology for Copper Recycling from Electronic Scrap, Proceedings of the 43 rd Annual Conference of Metallurgists of CIM, Hamilton, Canada, pp (2004) 6. D. Stevens, G. Bishop, B. Shinghal, B. Love, I. Mihaylov: Operations of the Pressure Oxidative Leach Process for Voisey s Bay Nickel Concentrate at Vale Inco s Hydromet Demonstration Plant, Proceedings of the 48 th Annual Conference of Metallurgists of CIM, Sudbury, Canada, 3 16 (2009) 7. Natural Resources Canada; Statistics Canada, Canada s Mineral Production, Preliminary Estimates, cat. no XIB 8. The minerals and metal policy of the government of Canada: Partnerships for sustainable development. Minerals and metal sector, Natural Resources Canada (1996) 9. &n=bf14cadf-1#part1a 10. V.I. Lakshmanan, R. Sridhar, M.S. Alam: Recovery of Zinc from Galvanized Coatings, Canadian Patent, No. CA (2005) 8 RESOURCES PROCESSING