Abstract :
In this work, the leaching behaviour of six
aluminosilicate industrial minerals and by-products
(kaolin, metakaolin, fly ash, natural pozzolana from
Milos, zeolite and furnace slag) in alkaline solutions is
investigated. The variables studied are the kind of
alkali metal (K, Na), the concentration of the alkaline
solution (2.5, 5 and 10 M) and the time of dissolution
(5, 10 and 24 h). The solid residue after the leaching
was examined by means of XRD and FTIR. As it is
concluded, the leaching ability of Al and Si is according
to the following descending order: Metakaolin >
Zeolite > Slag > Fly Ash > Pozzolana > Kaolin. The
extent of dissolution is higher in NaOH than in KOH
solutions, especially when the most reactive materials
are concerned. Finally, Si and Al seem to have a
synchronized leaching behaviour in both alkaline
solutions.
