US Patent 8210458 Recirculating grinding mill with external risers

A recirculating grinding mill, including at least two rolling presses for comminuting the material to be ground, at least two first classifiers for classifying a coarse-grain fraction, at least one second classifier for classifying a fine-grain fraction and a medium-grain fraction from the fractions classified in the at least two first classifiers. The feedstock is fed into the recirculating grinding mill passing the at least two rolling presses and the at least two first classifiers and then the at least one second classifier and the medium-grain fraction and the coarse fraction of the at least two first classifiers being fed once again to the rolling presses, and the at least two first classifiers being arranged underneath the at least two rolling presses. The rolling presses are placed between at least two risers for transporting the circulating material being ground.