Retsch AS 300 - Manual (Page 20)

07/02/2012 Retsch GmbH
20
Wet sieving
Target group: Owner, operator
Dry sieving will be possible in the large major-
ity of cases. There are, however, some mate-
rials in which the adhesive forces between the
individual particles can cause difficulties.
These problems can be eliminated by adding
liquid, preferably water, during the sieving op-
eration (in so far as the additives mentioned in
the chapter on “sieving aids” were not suc-
cessful). One pre-condition for wet sieving,
however, is that the substances to be sepa-
rated will not swell, dissolve or otherwise in-
teract with the liquid.
Required accessories
Clamping cover with spray nozzle, matching
the sieve diameter.
Base pan with water drain, matching the
sieve diameter.
Preparations
Position your AS200 control “g” near a water
drain.
Use a hose to connect the spray nozzle in
the clamping cover to a water faucet.
Connect the drain from the base pan with
the drain or a suitable container to receive
the liquid.
Operation
Apply the solid in the form of a suspension.
Set the liquid (water) supply rate so that the
spray just covers the sieve surface com-
pletely.
Using dispersion agents is advisable. They
reduce the surface tension of the sieve liq-
uids.
When dealing with goods which resist form-
ing a slurry or where more exact separation
is required, spray each individual fraction,
one after the other.
Following the sieving process, the fractions
are to be transferred from the individual
sieves to suitable filters (e.g. filter paper)
and dried in a drying cabinet at 80°C.
Then clean the sieves in an ultrasonic bath
and dry them, too, in the drying cabinet
(without the gaskets).
Do not exceed a maximum drying tempera-
ture of 80°C.