Presentation on theme: "Historical Availability of Metals Before 1800’s, only 10 were in use: Cu, Sn, Fe, Pb, Au, Ag, Zn, Hg, Bi, Pt They were either found uncombined Or Extracted."— Presentation transcript:
Historical Availability of Metals Before 1800’s, only 10 were in use: Cu, Sn, Fe, Pb, Au, Ag, Zn, Hg, Bi, Pt They were either found uncombined Or Extracted by heating with Carbon More metals in use today than 200 years ago. Why? Abundance; need for metals with new properties; ease of extraction
Extracting Metals from Ores Mineral: a pure crystalline compound found in the Earth’s crust (aluminium oxide) Ores: a compound or mixture from which it is economic (or profitable) to extract desired substances (ie. Metals) Eg. Bauxite (aluminium oxide) is an ore but aluminium silicates is not (not economic)
Extracting Metals from Ores 5 tonnes bauxite mined produces one tonne Aluminium Bauxite is crushed to obtain alumina mineral (Al 2 O 3 – aluminium oxide) Bauxite ore, a source of Al, is the most abundant element found in the earth's crust
Uses of Aluminium kitchen utensils cans & foil aircraft & rockets Window & door frames 60% less conductive than Copper but used for high voltage transmission lines Properties: light weight (low density); good tensile strength, high resistance to corrosion
Bauxite Reserves: 1985 - 21 billion tons 1990 - 21.8 billion tons 1993 - 23 billion tons 2006 - 25 billion tons Rate of use in 2006: 177 million tons per year How long will reserves last? 141 years
Extracting Metals from Ores Strong electric current pass through the molten alumina (mobile ions of Al 3+ and O 2- ) separating it into Aluminium metal & Oxygen gas To keep it molten and to perform electrolysis, electricity is a major cost Most smelters have their own electrical power plant
Energy Consumption Electricity consumption by the aluminium industry in the USA alone is equal to the consumption of all of New York City Alcoa Aluminum smelter in Texas requires 36 million pounds of coal to fuel operations per day
Australia is the world’s leading producer of bauxite. In 2010, it produced 71.5 million tons
50 Years of Industry in Australia 5 Bauxite mines 7 Alumina refineries 6 Aluminium smelters 12 Extrusion mills (19 presses) 2 Rolled product plants
$5,055,402,000 in 2011 It a significant contributor the econonmy:
Factors Affecting Price Abundance & location of ores Cost of extracting the metal from the ore Cost of transportation (eg. to smelter) World-wide demand MetalPrice/tonne Al$ 2 150 Cu$ 3 250 Au$ 17 000 000 Zn$ 1 360 Pb$ 1 070
Recycling it can be recycled indefinitely – 2/3 of the aluminum ever produced since 1886 is still in use This does not change the fact that between 1990 and 2000, 7.1 million tons of aluminum cans (only cans!) were wasted – enough to reproduce the world’s commercial air fleet 25 times At an average scrap value of $.58/lb, this represents $8.236 billion in lost revenue – just in cans!
Energy Expenditure Metalfrom natural ores (MJ) from recycled material (MJ) Aluminium2007 Copper704 Mild steel408
Recycling Steps 1. collect used Al products from homes, etc. 2. transport to central processing plant 3. separate the cans 4. Re-smelt the metal into ingots and transport them to product manufacturers Australians currently recycle more than 2 billion aluminium cans each year. But 900 million aluminium cans are thrown away every year ($15 million dollars in the landfill)
Benefits of Recycling Less energy: requires 5% of the energy needed No waste: 1 tonne recycled Al = 1 tonne new Al Less rubish Conserve Natural Resources: ores are non-renewable Australians consumed more than 3 billion aluminium cans in 2002. Of these, 47% were soft drink cans and 53% where alcoholic beverage cans.