Patent ID: 6932697

Claim:
A method for separating a flow of crops containing useful material and waste material into a useful material flow and a waste material flow, wherein in the useful material flow, the useful material is concentrated and in the waste material flow, the waste material is concentrated, comprising the following steps: separating the flow of crops into a pre-cleaned flow containing a substantial portion of the useful material and a remaining portion of the waste material with a first selectivity and a first waste material flow containing a substantial portion of the waste material and a remaining part of the useful material; separating the pre-cleaned flow with a second selectivity depending on its flow rate into the useful material flow and a second waste material flow containing a substantial portion of waste material and a remaining portion of the useful material; detecting continously at least one quantity of the amount of useful material flow combined into the waste material flow; and controlling the first selectivity based on the at least one quantity independently from the flow rate of the flow of crops.