Salt slag
Aluminum - salt slag is a residue from the melting of aluminum scrap and dross, which mainly takes place in the rotating drum furnaces of so-called refiners. During this process, molten salt, a mixture of z. B. 70% NaCl , 28% KCl and 2% CaF 2 added. This salt floats on the metal melt , prevents oxidation and also absorbs the contaminants from the scrap. Aluminum metal and salt cover are then drained from the rotary drum furnace one after the other.
The last “tapped” salt mixture contains residues of aluminum metal and various metal oxides , primarily aluminum oxide. This mixture solidifies in buckets and forms what is known as aluminum salt slag.
There are the K + S or Befesa processes for the preparation (recycling) of aluminum salt slag which allows reuse of the aluminum content and reuse of the molten salt z. B. as RESAL and a use of the residues z. B. enable SEROX as a replacement for bauxite .