Informations about Aluminium
Aluminum’s remarkable beneficial properties (strength, lightness, recyclability, resistance against corrosion, formability, thermal and electric conductivity) caused literally an aluminium revolution in the last 50 years. The exploitation of aluminium is much more expressive than any of the other “competitive” metals like steel and copper. For instance, during the last quarter of this century aluminium noticed a growth rate in transportation consumption of 6 per cent annually. Great prospects are offered not only by the automotive but also by the ship-building industry. The conductivity of aluminium has already given way to almost 100% of the market for air conditioning in cars and strongly penetrates also into the residential air conditioning markets.
Unsuspected aluminium possibilities are hidden in packaging of food, beverages and pharmaceuticals, especially when we want to achieve low weight of packing or a completely tight barrier against air and light.
Aluminium based solar collectors can feed a heating system with energy for a complete house, or apartment units. The aluminium collectors generate in only the first six months after installation as much energy as was needed to produce the metal!
Aluminium has also become the most preferred material in the field of civil construction engineering – mostly in areas where designers require to use material with long life span without any maintenance.
Recycling of metal is also considered to be important feature of aluminium. For instance in Europe nowadays about 60 % of metal is continuously collected for re-use. This percentage is likely to grow up to 70 % by 2010, indicating a growing importance of scrap as a highly valuable metal source.
From the above mentioned it is very clear that aluminium should be the preferred metal for future generations due to beneficial properties and “wisw” use of energy. Thus aluminium enters the new millennium with the attributes of the metal for the third millennium.
The first to produce pure aluminum was the Danish physicist, H. C. Oersted, in 1808. The method was reaction of potassium amalgam to water-free aluminum chloride. However, aluminum remained a laboratory curiosity until a French scientist, Henri Sainte-Claire Deville, announced a major improvement in Wöhler’s method, which permitted Wöhler’s “pinheads” to coalesce into lumps the size of marbles.
The most important aluminum ore, an iron-containing rock consisting of about 52 percent aluminum oxide was discovered in 1821 near Les Baux in southern France. The material was later named bauxite. Bauxite is best defined as an aluminum ore of varying degrees of purity in which aluminum in the form of aluminum hydroxide or aluminum oxide is the largest single constituent. The impurities are largely iron oxide, silica and titanium.
Bauxite has been found in all the world’s continents except Antarctica. Not all bauxites are economical for aluminum production. Only earth with aluminum oxide content of 30 percent or more is considered practical. Known deposits of bauxite can supply the world with aluminum for hundreds of years at present production level.
Production of technical aluminum started in 1854, when a factory to produce aluminum was built near Paris. The aluminum pureness was 92%, it being contaminated mostly by sodium and iron. At the time, the greatest technological progress was replacement of aluminum chloride with sodium tetrachloroaluminate, NaAlCl4. Pureness of the aluminum increased up to 96% and its price was higher than the price of gold at the time.
Although enough was then known about the properties of aluminum to indicate a promising future, the cost of the chemical process for producing the metal was too high to permit widespread use. But important improvements presently brought breakthroughs on two fronts: first, the Devill process was improved; and, the second, the development of the dynamo made available a large power source for electrolysis, which proved highly successful in separating the metal from its compounds.
The electrolytic method of producing aluminum was discovered almost simultaneously, and completely independently, by Charles M. Hall of the United States and Paul-Louis-Toussaint Héroult of France in 1886. The essentials of the Hall-Héroult processes were identical and remain the basis for today’s aluminum industry. Nowadays, the only way to produce aluminum is electrolysis of alumina in melted cryolite, which, in fact, differs only slightly from the original Hall-Héroult process. In more than 110 years of the process many substantial improvements have been realized. Nevertheless, a lot of problems making the power gain relatively low rest. Another disadvantage of aluminum production, as made in our days, is relatively demanding production of alumina out of bauxite, which is, as yet, the only economically advantageous raw material to produce Al2O3, while regional limitation of bauxite sources is also to be taken into consideration. Click HERE to read more about electrolytic production of aluminium.