THE MAKING ALUMUNIUM REVIEW Alumunium is active metal ,bonded and combine with other elements, so we will never find pure aluminium. Alumunium contains in surface of Granit . Granit is a rock that contain elements such as Aluminium, silicon, phosphor, Magnesium, Calsium and Iron. So how aluminium decomposed from the rock was by million years of washed granit. Rain and organic material washed the granit so the granit was decomposed into many element such as iron and aluminium, when exposed to the atmosphere aluminium will combine with oxygen and hydrogen become aluminium hydroxide. After decomposion for million years all that remain is surface deposit of aluminium bearing ore called bauxite. Bauxite chemical name is Hydrated Alumunium Oxide (Al2O3.3H2O). Because alumunium is active metal its give bauxite melting point about 2000o C. Smelthing in this temperature is dangerous and costly. So instead of heat we use electrolysis to eventually make aluminium from bauxite. But before electrolysis to work,the bauxite must first being refined into Alumina. Alcoa refinery in Australia doing this. One of three Alcoa refinery is in Pingera west Australia. Bauxite mine ore reserve near the plant loaded by conveyor belt. Once there, Alcoa use Bayer process to chemically filter impurities such as Iron hydroxide, Silica and Titanium oxide. Its an energy hungry process that use half domestic gas of western Australia. Heres is the process: Al2O3.3H2O + 2 NaOH-> 2NaAlO2+ 4H2O in high temperature solution. During this reaction Sodium hydroxide dissolve aluminium oxide and leaving undissolved impurities to filtered out. Then next process : 2NaAlO2+ 4H2O-> Al2O3.3H2O + 2NaOH. When this enough, large Aluminium hydrate crystal filtered out and heated to around 1000oC. This intense heat dried water up into steam which release to the atmosphere. The refining dry and free flowing sandy compound called Aluminium Oxide or Alumina (Al2O3). Alumina contains small highly charge aluminium ions and oxide ions held in strong ionic network called lattice. Each oxide ion has radius two and half times larger than that of each aluminium ion. Because of this, its difficult to show this into three dimensional shape. But alcoa research believe that in order to maintain the charge balance these ion are arrange in regular pattern in alternating layers. To make 1 ton of aluminium we need about 2 tons of alumina and just half a ton of carbon. Alumina from the previous process than ships into Portland Alumunium, western Victoria factory. Its loaded by vacuum system and travels by underground conveyor belt into big storage(cricket field size). American made petroleum coke, a brittle solid containing of 80% carbon used for making anode used for smelthing. The other major “ingredient” is electricity. There are enormous amount of electricity to make aluminium around about 15kWh per kg of aluminium produced or same as 1kW radiator to runs for 15 hours. Like Alcoa, produced 900 tons of aluminium a day and cost over half million dolars per day. They use 10 percent of electricity generated each day in Victoria. These energy transferred to 500 km to Portland at 500000 volts enough to compensate transmission lost. At Portland transformers drop the voltage to under 1000v DC. Production cost per tonne in Australia: Raw material about 45,3% Alumina 33,1% Energy 28,5% Electricity 26,6% Labour & overheads 26,2%. The heart of the smelther is in pot line, The name given for rectangular pots where electrolysis transform alumina into molten aluminium. These port also called Hall- heroult cells in recognition for the French man paul heroult and American Charles Martin Hall who simultaneously but independently foun economic smelthing method in 1886. Portland Aluminiums have 2 pot lines each with 204 parts measuring 13 meters long and 4 meters wide. Currents flow in one in flows in series frome one part to the next then going in second pot lines before returning to the switch out to complete these massive circuit. Although the pot just runs for 4,5 volt the currents is 300.000 A. For 408 pots total power consumption is over 550 megawatts. These power is generating heat and electrolytic force needed for smelthing. Each cell made from steel in bottom and carbon block(cathode), at the top is Carbon anode hold by insulated superstructure. Include Alumina hopper, Fume hood and removable doors. The process is using electrical resistance heating. Anode are lowered onto cathode. Shorts circuit heats the pot to 950oC. The anode than raised to leave a gap of 50 mm then cryolite(the chemical decomposition of certain substances by an electrical current passed through the substance in a dissolved or molten state) placed in the heated pot. Composition of cryolite 3NaF.AlF3 , AlF3 CaF2 and Al2o3 to reduce cryolite melthing points. Next, Alumina will dissolves and melts at 950oC. Cryolite forms a thick crust and Carbon soaks up sodium, Pot room operators add soda ash, alumunium fluoride also added then gas collected. These process are carefully monitored by computer. Carbon is ripped from each anode, and anode are automatically lowered. From electrolysis,,then goes to ingot. Previous product is molten Aluminium. The quality control of compotition

is Ingot puity about 99,8% . Alumunium is 8 of valuable commodity. Side product of these process is carbon dioxide and also green house gas and also particle gas. But some by product also become fertilizer. Pollutant also generated include particle and heat that blows by the wind into the island. Electrolysis is the economic process to produce alumunium but still gives pollutant and gases but these is the most valuable method to process the most important metal aluminium.