Method for the extraction of a substance from a starting material

摘要

The starting material is conveyed in an extruder through zones of high and low pressure formed by different screw elements of opposing pitch. An extractant is fed in the high pressure zones located upstream of the screw elements of opposing pitch. The extractant then flows in a direction countercurrent to a direction of transport of the starting material and is discharged via a discharge opening located in or close to the low pressure zone, downstream of a screw element of opposing pitch.