Problems with dense phase conveying systems for alumina (scaling, fouling)

my name is Arne Lüken and I am studying process engineering in Hamburg
Germany. In line with my studies I am working on a research about the
phenomena of scale formation which occurs while transporting fluorated
or secondary alumina with pneumatic dense phase conveying systems.
Secondary Alumina originates in the dry scrubbing process, where fresh
Alumina is used to adsorb the emissions from the off-gases of the
electrolytic cells. For now it seems like the principle occurrence of
scale formation is independent from the geographical location and the
dense phase conveying system itself, whereat it does differ in speed of
growth. Furthermore it seems that the Alumina itself is not the
initiator of the problem, rather the fine dust or particle emissions
seem to provoke the build up. Another interesting fact is that the
incrustations increase at places of high turbulences (for example at
bows and primary at the end of the conveying pipe due to higher
velocities). Since this is a very particular problem I found it very
hard to find any kind of literature or previous researches about this
problem. Therefore I would be very pleased about any kind of
information or knowledge like: Hints, Literature, Links, Contacts,
Ideas, or Researches

(for example composition of the emissions, composition of the scale
formation, or specifications of primary or secondary alumina,
fundamentals about fouling or scaling build up etc.).

Thanks in advance for any leads.
Best regards
Arne Lüken