and its Alloys are among the most important Metals in everyday life they resist the effects of other chemicals are strong yet flexible and are light in weight aluminium is the third most common element in the Earth's crust it is extracted from its oxide by electrolysis about 135,000 tons of alumin per year are extracted at Angley aluminium in hollyhead this is about half the UK total Angley aluminium has its own deep water port for importing raw materials aluminium can be shipped out by Road rail or sea the site is really three plants in one electrolysis takes place in four covered areas each half a kilometer in length and each containing 78 electrolysis cells the aluminium is alloyed and cast in the metal finishing shops anodes for the process are produced here aluminium oxide often called alumina is stored here fed by an underground conveyor belt from the docks this white powder is alumin the aluminium is extracted from it alumina is imported from Jamaica Ireland and Spain where it's been purified from boite ore this is one of the four rows of electrolysis cells called pot lines where the electrolysis takes place the current to the pot lines is about 157,000 amps at 4.5 volts angle C aluminium takes electricity from the National Grid this is one of the 312 cells in the pot lines the electrolysis cell consists of a rectangular steel shell lined with heat resistant brick and then carbon each cell is filled with molten cryolite the aluminium oxide is dissolved in molten cryy so that it conducts electricity 18 carbon anodes dip into the electrolyte during the electrolysis aluminium ions move to the cathode gain elect and become aluminium metal oxide ions move to the anode where each ion loses two electrons and the atoms pair up to become oxygen molecules these are the chemical equations as the electrolysis proceeds the aluminium oxide is decomposed into aluminium and oxygen a crust forms on the electroly light and this has to be broken to feed in new aluminium oxide this happens every 3 to 4 minutes The Hoppers on the cells are filled from an overhead oil bucket every 16 hours the electrolyte is at about 955 de at this temperature the carbon anodes gradually burn away in the oxygen from the electrolysis eventually the noes have to be replaced and this happens every 28 days or so the remaining carbon is broken off the old anodes crushed mixed with new Coke and pitch and pressed into shape the newly pressed anodes Abate for about 24 hours in gas heated pits this produces electrodes which will conduct electricity and not crumble away in the cells the temperature of the pit is important and is checked on a regular basis the baited anodes are fitted onto steel stubs these are held in place and connected electrically with cast iron the anodes are sprayed with molten aluminium to protect the top and sides electrolysis takes place 24 hours a day 365 days a year a loss of power of more than a couple of hours would be disastrous as the electrolyte and the aluminium would solidify liquid aluminium is sucked from the cell into a brick light steel Crucible each cell produces about 50 kg of aluminium per hour some of the aluminum is cast as almost pure metal some is made into Alloys by adding other metals this metal being added is magnesium [Music] aluminium Alloys or pure metal can be cast into different shapes the liquid metals are poured into molds where they solidify and can be lifted out [Music] aluminium metal is sold in various shapes according to the needs of the customer [Music]