™ PAM
Polymer Flocculants
Qualfloc™
Bestac
International, Inc.
P.O.
Box 585
Wayne, NJ 07470 USA
Tel: 973 6336878
Fax: 973 6330828
www.qualfloc.com
Email: service@qualfloc.com
[Bestac International, Inc.]
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for
Alumina
Alumina is produced by processing bauxite ore. After crushing and
grinding the ore to less than 1mm it is then subjected to high temperature and
pressure after the addition of concentrated sodium hydroxide. The alumina
dissolves in the highly caustic liquor and of the many impurities only silica
is soluble.
After digestion the sand particles are removed with the slurry
being settled in primary thickeners where the flocculant is added. This is a
critical stage in achieving very clear overflow clarities. The underflow, or
red mud, then passes to a counter current decantation process where further
alumina from the liquor is recovered via a series of washer decanters. Again
flocculant is used here to promote settling and acceptable overflow clarities.
The pregnant liquor from the primary thickeners is filtered, then
cooled (taking up to 48 hours) and seeded with alumina hydrate to promote
precipitation of alumina trihydrate. This is then filtered and washed finally
calcined to produce alumina.
For the primary thickeners the recommended
product is:
Qualfloc A0014
For the washer decanters the recommended
products are:
Qualfloc A8514
Qualfloc A8516