In the following some words for the fundamental principle of the opto-electronic assortment of mineral bulk materials. The goal of the procedure is to separate the objects of a materialstream on the basis a surface inspection according to coloured and/or geometrical characteristics with a high throughput, a small error rate and a good reproductibility of the sort decisions.

Before sorting generally a material conditioning is necessary, which affects the sort result considerably. If not done before to material is separated into suitable, not to large grainsize fractions and led across a washing screen or similar, in order to remove adhering, the actual object color covering contamination such as dust or earth. With moistened minerals often also a higher coloured contrast of the objects can be used. Before the actual assortment a object separation is necessary, this happens with the help of a vibratory feeder or a conveyor belt.

The picture recording of the separated material takes place during free fly by means of a high-quality digital line camera, which makes possible a dissolution of 0,4mm² at 1200mm work width. On the basis of these photographs an attached sort computer recognizes objects and decides on the basis of a programable classification chain whether these must be removed or not. In addition in real time valves for compressed air are headed for, which remove the object if necessary.