Historical Availability of Metals

Before 1800’s, only 10 were in use:Cu, Sn, Fe, Pb, Au, Ag, Zn, Hg,

Bi, PtThey were either found uncombined

OrExtracted 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 (Al2O3 – 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

Digging for BauxiteDigging up the bauxite

The size of the scoop

Bauxite Reserves:

1985 - 21 billion tons1990 - 21.8 billion tons1993 - 23 billion tons2006 - 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 Al3+ and O2-) 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

Aluminium Industry

16,700 Employees

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 PriceAbundance & location of ores

Cost of extracting the metal from the ore

Cost of transportation (eg. to smelter)

World-wide demand

Metal Price/tonne

Al $ 2 150

Cu $ 3 250

Au $ 17 000 000

Zn $ 1 360

Pb $ 1 070

Recyclingit 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

Metal from natural ores (MJ)

from recycled material (MJ)

Aluminium 200 7

Copper 70 4

Mild steel 40 8

Recycling Steps1. 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.