Mining process for materials such as phosphates

The upper cutting rollers in the projection on the movement plane are moved at a greater distance from the movement plane of the work face conveyor than the lower cutting rollers. The beam arms (5) for the cutting rollers (8) are pivotable around a coaxial or common axis (3) in a height direction. At least one upper cutting roller is driven precipitately in the advance feed direction. Where two cutting rollers (8) are used, by reversal of the feed direction the precipitate position of the upper cutting roller is adjusted by pivoting the upper roller downwards and the lower roller upwards and the rotary directions of the cutting rollers are reversed.