semi wet process of cement industry

In the semi-wet process the raw slurry is dewatered in filter presses. Typically, modern chamber filtration systems produce filter cakes with a residual moisture content of 16-21%. In the past, filter cakes were further processed in extruders to form pellets which were then fed to grate preheater kilns with three chambers.

With modern cement plants, slurry filtration is applied only where raw materials have a very high natural moisture content, i.e. chalk. Filter cake coming from the filter presses is kept in intermediate storage bins before it is fed to heated crushers or dryers where a dry raw meal is produced which is fed to a modern preheater or precalciner kiln.

With the dryers/crushers operating full time in parallel with the kiln (compound operation), these systems have a very good energy recovery by making full use of the kiln exhaust gases and the cooler exhaust air.