when molten aluminum makes contact with water(fire sprinkler system) hydrogen gas is released.hydrogen gas burns at a much higher temp than jet fuel,hot enough to melt iron.thermite scenarios aside i think that this could be an explanation of how the fire got so hot.the remnants of the airliners never exited the buildings.aluminum(and oxygen) are used for solid rocket fuel.from wiki:"the exhaust from a solid rocket motor contains hydrochloric acid and aluminium oxide. "also: http://www.g2mil.com/aluminum.htm