Deutsche Gold- Und Silber-scheideanstalt Vormals Roessler

Bernd Brandt

Peter Nauroth

Helmut Reinhardt

Albert Peters

Peter Jansen

Heinz Liesenfeld

A silicic acid filter cake and suspension agent are fed to a container equipped with a stirrer having a peripheral speed of about 20-30 m/sec. The ratio of container diameter to stirrer diameter is about 3:1. The ratio of container diameter to level of filling is a maximum of about 1:2. The container contains at least about 1.5 to about 2 kg of silicic acid suspension, for each 1 kg of silicic acid filter cake which is added to the container. The contents of the container is mixed while maintaining a pH of at most about 4. A portion of the resulting silicic acid suspension is drawn off from the zone of highest turbulence in the container. An apparatus for carrying out the process is provided.

Apparatus for preparation of a sprayable precipitated silicic acid

A finely divided silicic acid having a pH&gt;6 is prepared by spray drying, in the presence of a base or basic-reacting substance, a highly concentrated silicic acid suspension having excess, unwanted acidity.

Process for the production of finely divided silicic acid by spray drying

A silicic acid filter cake and suspension agent are fed to a container equipped with a stirrer having a peripheral speed of about 20-30 m/sec. The ratio of container diameter to stirrer diameter is about 3:1. The ratio of container diameter to level of filling is at most about 1:2. The container contains at least about 1.5 to about 2 kg of silicic acid suspension, for each 1 kg of silicic acid filter cake which is added to the container. The contents of the container is mixed while maintaining a pH of at most about 4. A portion of the resulting silicic acid suspension is drawn off from the zone of highest turbulence in the container.

Process for preparation of a sprayable precipitated silicic acid

Air is vented from steam-charged heating pipes of a tubular rotary dryer via connector pipes and a collecting pipe which is disposed circumferentially around the dryer drum. Holding blocks provided with inwardly-biased rollers support the collecting pipe for longitudinal movement on the exterior wall of the dryer drum.

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Wesseling-Berzdorf, Germany

Bernd Brandt