Vertical type pulverizing and classifying apparatus

Claim 1

A vertical type pulverizing and classifying apparatus comprising: a pulverizing chamber provided with a pulverizing rotor disposed within a housing having upper, medial and lower portions, a guide ring stationarily disposed above and coaxially with the pulverizing rotor, the guide ring defining inwardly thereof a descending gas stream passage for primary classification of material pulverized in the pulverizing chamber, a classifying blade rotor disposed above and coaxially with the guide ring and driven so as to rotate within an upper housing portion, the blade rotor and the upper housing portion serving to define a classifying chamber therebetween for secondary classification of material fed from the guide ring, a collecting passage disposed above the blade rotor into which fine particles from the classifying chamber flow is fed by gas streams, a first material carrying gas feed duct disposed below the pulverizing rotor, a plate member provided with pores disposed between the descending gas stream passage and the classifying chamber and arranged to serve as a partition therebetween, a conduit having extremities axially disposed such that one extremity terminates within a zone defined by the guide ring and the opposite extremity extends through the plate member so as to terminate within the classifying chamber, a second gas feed duct disposed below the plate member and arranged to supply a flow of gas to the pores of said plate member, a coarse material floating chamber disposed within said medial housing portion above the plate member, said chamber being defined by said medial housing portion and the upper extremity of the conduit, and return passage means disposed exteriorly of said housing and extending from coarse material floating chamber to said lower housing portion and into said pulverizing chamber, whereby coarser particles are separated from finer particles and recylced for further pulverizing.