Introduction

Books on the production of aluminum metal have previously focused on its recovery from naturally occurring raw materials. The principal natural ore for aluminum is bauxite, a mineral consisting primarily of hydrated aluminum oxides. Aluminum is recovered from bauxite by a selective leaching sequence known as the Bayer process (Damgaard et al., 2009; OECD, 2010), which dissolves most of the aluminum while leaving impurities behind. The aluminum is recovered from the leach solution by precipitating it as aluminum hydroxide. The hydroxide is then dried and calcined to generate puried alumina. The calcined alumina is in turn fed to electrolytic cells containing a molten salt electrolyte based on cryolite (Na3AlF6). The alumina dissolves in the cryolite and is electrolyzed to generate molten aluminum metal and carbon dioxide gas. This process has been the sole approach for producing primary aluminum metal since the late 1800s and will likely continue in this role for decades to come.