Unlike metals such as gold, aluminum cannot be found in a natural metallic state. It takes a lot of work and a lot of energy to turn red dirt into shiny metal. The basic process for making aluminum has not changed in more than a hundred years.

The raw material for aluminum can be found in all kinds of clays, but a red dirt known as bauxite forms the basis for making aluminum.

Bauxite contains all kinds of impurities -- primarily metals such as iron -- but atitsheart, it consists of 45 percent to 60 percent aluminum oxide, or alumina.

Bauxite is generally mined using open pits. In open pit mining, the overburden (the engineering word for the soil on top of the deposit) is removed and saved for later replanting operations. Reynolds Metals has an extensive history of restoring the land back to its natural state.

Following mining, the bauxite is crushed, sometimes dried, and transported to processing plants via ship, barge, rail or truck

Processing begins by passing the ore through screens to sort and crush by size. The ore is then fed to large grinding mills and mixed with a caustic soda solution called liquor.

The shell of the grinding mill rotates, and steel rods rolling around inside the shell grind the ore to an appropriate size. The process is a lot like a kitchen blender only much slower and much larger. The discharge from the mill is called slurry.

The slurry is pumped to a digester where the chemical reaction to dissolve the alumina takes place. In the digester the slurry is heated to 300 degrees Fahrenheit or 145 degrees Celsius (all while being under 50 pounds per square inch pressure) and it stays in those conditions for 30 minutes to several hours.

More caustic soda is added at this point, in order to dissolve aluminum containing compounds in the slurry. Undesirable compounds either don't dissolve in the caustic soda, or combine with other compounds to create a scale on equipment which must be periodically cleaned. The digestion process produces a sodium aluminate solution.

Because all of this takes place in a pressure cooker, the slurry is pumped into a series of flash tanks to reduce the pressure and recover heat before moving on to the settling tanks.

From the flash tanks, the slurry travels to settling tanks. Most of the work here is handled by simple gravity, although some chemicals are added to help the settling process.

Just as a glass of sugar water with fine sand suspended in it will separate out over time, the impurities in the slurry -- things like sand and iron and other trace elements that do not dissolve -- settle to the bottom.

The liquor at the top of the tank, which looks like coffee at this point, then moves on to a series of filters. The remaining red mud is pumped off and, after washing to recover alumina and caustic soda, is sent to dry out in large storage ponds.

The alumina left in the liquid moving along in the process now consists of tiny crystals suspended in a liquor that's still quite warm at this point, however there are still some very fine solid impurities that must be removed. Just as coffee filters keep the grounds out of your cup, the filters here work the same way.

The giant-sized filters consist of a series of "leaves" -- big cloth filters over steel frames and remove much of the remaining solids in the liquor. The material caught by the filters is known as a filter cake and is washed to remove alumina and caustic.

The filtered liquor is then cooled and pumped to the precipitation process.

Imagine a tank as tall as a six-story building. Now imagine row after row of those tanks. And imagine that those tanks are filled with millions of tiny particles of alumina.

Seed crystals -- alumina hydrate-- are poured into the top of these tanks called precipitation, which helps the alumina crystals grow bigger and settle to the bottom. The crystals pulled from the bottom of the tank move along to thickening tanks, and from there to filters and calcination kilns.

Calcination is a heating process to remove the chemically combined water from the alumina hydrate.

That's why, once the hydrated alumina is calcined, it's known as anhydrous alumina. "Anhydrous" means "without water."

From precipitation, the hydrate is filtered and washed to rinse away impurities and remove moisture. A continuous screw conveyor moves the hydrate into the calcining kiln.

The calcining kiln is brick-lined inside and gas-fired to a temperature of 2,000 degrees Fahrenheit or 1,100 degrees Celsius. It slowly rotates (to make sure the alumina dries evenly) and is set upon a tilted foundation which allows the alumina to make it's way to the cooling equipment, shown at the right . (Newer plants use a method called fluid bed calcining where alumina particles are held in suspension by hot air and calcined.)

At this point, the alumina is ready for conversion into aluminum at a smelter. Alumina can also be used in chemical and ceramic applications.

In 1886, two 22-year-old scientists on opposite sides of the Atlantic, Charles Hall of the USA and Paul L.T. Heroult of France, made the same discovery -- molten cryolite (a sodium aluminum fluoride mineral) could be used to dissolve alumina in order to produce metallic aluminum. The Hall-Heroult process remains in use today.

The key to the chemical reaction was the running of an electrical current through the cryolite/alumina mixture.

It has to be direct current -- not the alternating current used in homes -- and it is the reason why the location of aluminum plants is based in large part on the availability of affordable electrical power. Some experts believe one percent of all the energy used in the United States is used in the making of aluminum.

The Hall-Heroult process takes place in an electrolytic cell called a reduction pot. The current used in a typical reduction pot is only 5.25 volts, but the amperage generally tops 100,000 amperes.

The steel tubs are lined with carbon, and the carbon acts as one pole or carbon electrode (called the cathode). The other electrode (called the anode) is dipped into the molten mix of cryolite and alumina from above.

When the electric current passes through the mixture, the carbon of the anode combines with the oxygen in the alumina and drifts away as carbon dioxide. The metallic aluminum settles to the bottom of the pot, where it is periodically syphoned off into crucibles. From here the metal can be forged, turned into alloys, or extruded into the shapes and forms of which you are familiar.

Very little cryolite is ever lost in the process, and the alumina is constantly replenished from storage containers above the reduction pots. In most plants, reduction pots are lined up in long rows, called potlines, and are usually kept in production 24 hours a day year-round.