Patent attributes
A flow of crops, which contains useful material and waste material, is separated in a crop machine into a useful material flow and a waste material flow, in which, respectively, the useful material or the waste material is concentrated. A first step separates the flow of crops with a first selectivity into a pre-cleaned flow, which contains a substantial portion of the useful material and a remaining portion of the waste material, and a first waste material flow, which contains a substantial portion of the waste material and a remaining portion of the useful material. A second step separates the pre-cleaned flow with a selectivity dependent on its flow rate into the useful material flow and a second waste material flow, which contains a substantial portion of waste material and a remaining portion of the useful material. A quantity combined from the amount of the useful material into the waste material flow is detected continuously, and the first selectivity is regulated based on this quantity, independently from the flow rate of the flow of crops (S3, S4).