An impact mill for grinding loose material, comprising: - at least a main rotor moving in rotation around a first axis inside a grinding chamber; - at least a secondary rotor moving in rotation around a second axis inside an inlet chamber of the material to be ground communicating with said grinding chamber, said secondary rotor being suitable for sending the material to be ground inside said grinding chamber; - said inlet chamber and said grinding chamber being delimited by at least two respective side walls (4a, 12a) arranged substantially transversal to said first and second axes (3, 11), respectively and by at least a connection wall (4b, 12b) placed between the respective side walls (4a, 12a) to surround at least in part the relative rotor (2, 10), said first and second axes (3, 11) being arranged substantially horizontally and parallel to one another; characterised by the fact that said inlet chamber has an inlet gap of the material to be ground defined on at least one of said side walls, by the fact that said inlet gap is arranged along said second axis of rotation, by the fact that said secondary rotor comprises a base plate facing said inlet gap and with which are associated integral a plurality of throw elements for throwing the material to be ground, where said throw elements extend starting from the perimeter edge of said base plate towards said second axis and are spaced from the latter so as to delimit a receiving area of the material to be ground, arriving from the inlet gap, free and without protrusions, substantially facing said inlet gap, said receiving area being arranged in correspondence to the central portion of the base plate, by the fact that said inlet chamber and said grinding chamber communicate with each other by means of a connection gap defined on the respective connection walls (4b, 12b), said connection gap being arranged so that the material sent by said secondary rotor is directed towards the lower portion of said grinding chamber, said main rotor and said secondary rotor being synchronized together so that the material to be ground substantially impacts in a perpendicular way the front face of said crushing elements upon their transit, and by the fact that said inlet chamber has a collection area of the material to be ground entering from said inlet gap, said collection area being arranged at a lower height than said receiving area and said connection gap. - at least a main rotor moving in rotation around a first axis inside a grinding chamber; - at least a secondary rotor moving in rotation around a second axis inside an inlet chamber of the material to be ground communicating with said grinding chamber, said secondary rotor being suitable for sending the material to be ground inside said grinding chamber; - said inlet chamber and said grinding chamber being delimited by at least two respective side walls (4a, 12a) arranged substantially transversal to said first and second axes (3, 11), respectively and by at least a connection wall (4b, 12b) placed between the respective side walls (4a, 12a) to surround at least in part the relative rotor (2, 10), said first and second axes (3, 11) being arranged substantially horizontally and parallel to one another;