Discovery and extraction of aluminum â € "A Brief History

Author: Aluminum Casting process

The term comes from the complex aluminum alum (Kal (SO4) 2? 12H2O), which contains it. In the 18th century realized that alum provides a unique base, different from all others, but only in the 19th century scientists were able to isolate it.

Berzelius and Davy tried to use electrolysis processes to isolate the metal in alumina. In particular Davy Heat a mixture of alumina and potash, and then sends the mixture to an electric current, but without success.

Oersted in 1825 was to try to isolate the metal which is believed to appear in the alumina. It was first prepared anhydrous aluminum chloride (AlCl3) by passing a current of chlorine on a mixture of charcoal and alumina is heated to red. Then, the aluminum chloride produced is mixed and heated with amalgam potassium, producing potassium chloride and aluminum amalgam. Distillation of this mixture without contact with the atmosphere left a piece of metal that color, said Oersted, tin resembles in color and brightness.

WÃ ¶ hler repeated Oersted's experiment, but could not replicate the results. Recent replications of the experiment, based on Oersted's notes, have shown that with a very dilute potassium amalgam (1.5% K), it is possible to extract the aluminum.

Oersted encouraged WÃ ¶ hler to continue in their attempts. Thus, WA ¶ hler first produced anhydrous aluminum chloride. Next, put in a platinum crucible with a mixture of AlCl3 and potassium (K) instead using potassium amalgam as Oersted. The crucible was closed and some heat applied only to start the reaction. Soon, the crucible was very hot, with the reaction:

A 3K + AlCl3 -> Al + 3KCl

exothermic. The aluminum produced was contaminated with platinum, so they repeated the experiment with the porcelain crucibles and other materials, always be able to produce aluminum in the form of a gray powder. The aluminum produced was contaminated with potassium, platinum or aluminum chloride, however, first described the most important properties of aluminum and then in 1845, was able to produce a coherent mass of aluminum.

In 1855 French scientist Henri Sainte-Claire Deville, ignoring WÃ ¶ hler 1845 experiment, repetitive. Observation of the reduction of aluminum chloride, comprising the importance of discovery and immediately began to explore ways to produce large quantities of this metal for sale. Two ways were possible. The first was the chemical production of aluminum chloride with potassium salt and reducing agent, the second option was an electrolytic method to reduce the chlorine, with a carbon anode and cathode of platinum. Both methods are difficult to implement on a large scale. In the chemical method, potassium is very expensive and dangerous to handle, while there are sources of power is available at low cost, the only existing batteries being. Therefore, H. St. Claire Devil choose the chemical method to produce aluminum, using as reducing agent of the most common in nature, sodium (Na) instead of potassium. ™ € s Devilleâ The work was very helpful for the funds given by Napoleon III. Thanks to the work of other chemicals that time, Deville was able to produce for themselves large amounts of sodium. At the same time, in this period of two processes must be turned in industrial processes, the first production and refining of alumina and the second, the conversion of alumina into aluminum chloride. Anyway, in 1859 the available amount of aluminum increased (2 tons / year produced in the plant Salindres). Through the years going from 1855 to 1890 the price of aluminum fell from 1200 to equivalent, ¬ / kg to 13 â, ¬ / kg. During that year, chemical and electrochemical Methods were developed for the extraction of aluminum. Chemical methods more or less variations around the basic process of St. Claire Deville. Include: Castner, Netto, Grabau, Webster, Frismuth, TSAP € | The electrochemical processes could be divided into two main categories: electrothermal and electrolyte. For electrothermal processes we can mention Cowles, HÃ © roult, Brin, Bessemer, Stefanita, Moissan, while for the electrolytic processes have roult HÃ ©, Adolphe Minet, Hall, Hamper, Kleiner, Gooch, Waldo.

In all these processes, did the work of the American Charles Martin Hall and Paul French HÃ © roult Louis Toussaint, who independently and simultaneously invented the process that is still used to reduce alumina to aluminum.

In 1880 at Oberlin College near Cleveland, Ohio, two people meet. One was Frank Fanning Jewett, professor of chemistry and mineralogy at Oberlin College. Jewett had the opportunity to study at the University of GÃ ¶ ttingen in Germany between 1873 and 1875. While in Germany he met WÃ ¶ hler, who had isolated aluminum in 1827. The other was a young student at Oberlin, Charles Martin Hall, self-taught person and so passionate chemistry to carry out experiments at home. Hall, at the age of 16, I knew the problems involved in aluminum production and, under the guidance and encouragement Jewett, worked in the chemistry of aluminum, both at home and laboratory Oberlin College. Hall first tried to chemical reduction methods for the production of aluminum, but without results. Then, with Jewett, decided to follow the path to produce electrolytic aluminum. In a first attempt, Hall tried to decompose aluminum fluoride (ALF3) dissolved in water, but the results only was the production of hydrogen at the anode and aluminum hydroxide on the cathode. What is important in this work was the selection of fluorine never tried before. The next step was the use of molten salts as solvents. After several experiments, choosing the cryolite as the solvent, being aware he and Jewett its use in the Deville works. He was able to melt and cryolite proved to be a good solvent for alumina. The first attempt was done using an electrolysis clay crucible, but the result was the production of silicon from the crucible material. So, recognizing this, the clay pot was lined with graphite, was added some fluoride cryolite aluminum in order to lower the melting point and the experiment was repeated. After several hours of electrolysis, cools merger and opened it, finding small globules of silver confirmed that aluminum Jewett. In February, 23 1886.

After some problems, 1888, a group of investors, organized by Captain Alfred Hunt, Hall provided with sufficient funds to establish the Pittsburgh Reduction Company, Alcoa's predecessor.

One or two months later, the discovery of Hall, Paul Louis Toussaint French HÃ © roult made the same discovery independently. She heard of the discoveries Deville St.Claire age of 15 read Devilleâ ™ € s famous treatise. He tried to produce aluminum from aluminum electrolysis different compounds, without success. Then tried cryolite electrolysis. During the process, the cathode is molten iron. Because temperatures were not so high to justify a merger iron, he realized that some of alloy were formed. A few days later, in an attempt to lower melting temperature, added some chloride Sodium aluminum and realized that the carbon anode is consumed. What happened was that the sodium aluminum chloride into contact with moisture, it becomes aluminum hydrated. So basically discovered HÃ © roult the same process to produce aluminum revealed by Hall only a couple of months earlier.

href = "http://www.aluminumsmeltingprocess.com"> href = "http://www.aluminumsmeltingprocess.com"> http://www.aluminumsmeltingprocess.com

About the author:

Item Source: ArticlesBase.com - title = "discovery and aluminum extraction â € "A Brief History"> Aluminum discovery and extraction â € "A Brief History