The recycling/remelting of thin aluminum scrap generally involves melt
ing of these pieces submerged in molten salt. These pieces are origina
lly covered with a thin oxide film. The oxide film must be first remov
ed by molten salts before coalescence between the drops can occur. In
this study, two new experimental techniques were designed to study the
oxide film removal and the droplet coalescence in the molten salt. Th
e effects of alloy and salt compositions on the oxide film removal and
the drop coalescence were studied. Mg content in Al alloy results in
a thicker oxide film on the metal piece and its removal was found more
difficult. However, the fluoride addition facilitated the oxide film
removal. The paper discusses various oxide film removal mechaisms. The
second of the two experimental techniques included bringing two molte
n metal drops together and noting the time required for the drops to c
oalesce. These experiments provided a quantitative measure of the coal
escence ability of various salts. Metal drops could not coalesce in th
e pure chloride (NaCl-KCl) molten salt. Alloys containing Mg reacted w
ith salt to produce Na or K which makes the surrounding salt as purple
bluish in color which is termed as ''fog''. Mg containing alloys prod
uced dense ''fog'' and retarded the coalescence of the metal drops, wh
ile Mn, Si, and Fe had little effect on ''fog'' formation and coalesce
nce.