The process water discharged in process stage 2 contains, among other things, mineral components ≤250 μm. If this content is below the limit value or below the value accepted by the competent authority, the process water may be discharged into the sewer system. However, this discharge may only take place after appropriate analysis and approval.

If, however, the content is above the limit value and direct discharge is thus not possible, the recycling process is supplemented by process stage 3.

In the fine particle separation, mineral components in the range of 60...250 μm as well as still contained impurities are separated from the discharged process water. For this purpose, the process water is passed through screens and a hydrocyclone. The resulting material is dewatered via a vibrating screen, conveyed to the material box and disposed of.

The process water, with mineral components ≤60 μm, is either discharged or fed to process stage 4: process water recycling . Process stage 4 is used in particular when the following criteria are present:

• Der Anteil an mineralischen, abfiltrierbaren Bestandteilen ist noch zu hoch, um eine Genehmigung für die Einleitung desProzesswassers zu erhalten
• Auch mit anderen Maßnahmen (z.B. Entwässerungscontainer), der zulässige Grenzwert nicht erreicht werden kann.

Scheme fine particle separation