Different ways of manufacturing aluminum - Research Paper Example

Different ways of Manufacturing Aluminum Technical Communication for Engineering March 12, Different ways of Manufacturing Aluminum Aluminum is the third major element found in in earth’s crust after oxygen and silicon. About 8% of earth’s crust is made of raw aluminum. Physically it is a relatively soft, durable, lightweight, ductile and malleable metal with silvery to dull gray color that depends on smoothness of its surface. Aluminum is chemically so strong in reaction that it is found in combination of near about 270 different minerals.

The most common ore of aluminum is bauxite having 45-60% aluminum oxide. Due to its nonmagnetic, durable and lightweight characteristics, aluminum has thousands of different applications particularly in construction and manufacturing sectors and “more than 10 billion pounds of aluminum are produced worldwide annually” (Lindamood n. d.). The most commonly found aluminum ore bauxite is a mineral of aluminum (Al) and hydroxyl (OH) with very strong covalent bounding between oxygen and aluminum.

Hence on large scale, it is not possible to directly extract Al from its ore by simple chemical process. The separation is carried out through various indirect methods. The manufacturing of pure aluminum (lxx.x, 99.00% or greater) from its ores is done through following process as given below.Bayer ProcessAlso known as ore separation/purification process is invented by an Austrian chemist Carl Josef Bayer while working at Saint Petersburg, Russia. In this process, after mining, the ore is mechanically crushed into very fine granular form.

The fine powdered ore is then mixed in hot caustic soda liquor (NaOH) at 110-270°C under 340 kPa Pressure to produce slurry of liquid. After several hours of process NaOH completely dissolves the Al. The liquid is then passes through a series of flash tanks to reduce the pressure and to recover the heat. The mixture is separated from its solid impurities by passing it through a settling tank and through filtration process. The saturated aluminum rich liquid passes through a series of six-story-tall precipitation tanks (Hall 1997).

As the liquid propagates through each tank, seed alumina hydrate crystals are also added from the top of each tank. The “aluminum trihydrate crystals grows in size and precipitated calcined in rotary kilns or fluidized bed calciners to produce alumina (Al2O3)” (Aluminum Manufacturing 1998: pp.261).The crystals obtained through kiln are cool down and proceed to smelting process.Reduction or Hall-Heroult ProcessIn Hall-Heroult Process also known as smelting processing the alumina crystal abstained through Bayer process is further dissolved in molten cryolite at a temperature of 960-970° C to form an electrolyte.

The alumina electrolyte solution is placed in steel vats called reduction pots, connected in series with carbon lined bed at bottom. A DC 100,000-230,000 A current at 4-6 DC voltage passes through these reduction pots resulting a reduction reaction between carbon and oxygen to form carbon dioxide and leaving behind molten aluminum that settle at the bottom of the pots. The process remains continue and molten aluminum is removed by lowering a crucible to reduction pots and 99.8% pure aluminum is obtained (Hall 1997).

The molten aluminum obtained through smelting process is further cast into small handy molds or billets. The molds are further going through rolling, extruding and fabrication process to have final finished product. The whole process can be given represented by following process flow diagram below.Reference ListLindamood, K. (n. d.). The Manufacturing Process of Aluminium. Retrieved from http://www.ehow.com/how-does_5118212_manufacturing-process-aluminium.html#ixzz2NHr4Um5nHall, L. (1997). Aluminum- How Products Are Made Vol. 5. Retrieved fromhttp://www.madehow.com/Volume-5/Aluminum.

htmlAluminum Manufacturing. (1998). Pollution Prevention and Abatement Handbook World Bank Group. Retrieved fromwww1.ifc.org/wps/wcm/connect/./alum_PPAH.pdf?MOD=AJPERES