bauxite and alumina 1997 10 1 b auxite a lumina by patricia plunkert is naturally occurring heterogeneous material composed primarily of one or more aluminum hydroxide minerals plus various mixtures silica sio 2 iron oxide fe o 3 titania tio aluminosilicates clay etc other impurities in trace amounts the principal found varying proportions within are gibbsite al oh polymorphs boehmite diaspore both alo bauxites typically classified according to their intended commercial applications abrasive cement chemical metallurgical refractory all mined approximately 85 converted for production metal an additional goes nonmetal uses as forms specialty remaining 5 used nonmetallurgical bulk world therefore feed manufacture via wet caustic leach process known bayer majority produced from this refining smelted using hall héroult produce electrolytic reduction molten bath natural synthetic cryolite
