Grinding mill with multiple milling sections

A grinding mill containing a plurality of milling sections and comprising:

• a single cylindrical stator common to all milling sections and having a top, a bottom provided with a central opening, and a longitudinal axis which is substantially vertical when said mill is in operation;
• a rotor mounted in said stator for rotation about the longitudinal axis and having a plurality of milling plates extending parallel to the longitudinal axis and disposed in respective milling sections;
• material supply means disposed for delivering material to be ground to the region beneath said central opening;
• gas supply means disposed for delivering conveyor gas to the region beneath said central opening;
• and a blower facility including a single stage radial blower fastened to said rotor for rotation therewith and disposed near the bottom of said stator below the lowermost milling section for conveying material to be ground and conveyor gas from the region beneath said central opening to said milling sections, characterized by the fact that the blower facility has a central gas and material entrance part and a radial gas and material exit port, and the radial blower (15) has a rim (19) which extends perpendicular to the plane of the blower and which delimits the central entrance port of said facility.

A grinding mill containing a plurality of milling sections and comprising:

• a single cylindrical stator common to all milling sections and having a top, bottom provided with a central opening, and a longitudinal axis which is substantially vertical when said mill is in operation;
• a rotor mounted in said stator for rotation about the longitudinal axis and having a plurality of milling plates extending parallel to the longitudinal axis and disposed in respective milling sections;
• material supply means disposed for delivering material to be ground to the region beneath said central opening;
• gas supply means disposed for delivering conveyor gas to the region beneath said central opening;
• and a blower facility including a single stage radial blower fastened to said rotor for rotation therewith and disposed near the bottom of said stator below the lowermost milling section for conveying material to be ground and conveyor gas from the region beneath said central opening to said milling sections, characterized by the fact that the throughput velocity of the mill is controllable by a gas transport facility (26) installed in series behind the milling sections (5) and designed as a ventilator with a variable speed motor drive (27).

A grinding mill containing a plurality of milling sections and comprising:

• a single cylindrical stator common to all milling sections and having a top, a bottom provided with a central opening, and a longitudinal axis which is substantially vertical when said mill is in operation;
• a rotor mounted in said stator for rotation about the longitudinal axis and having a plurality of milling plates extending parallel to the longitudinal axis and disposed in respective milling sections, material supply means disposed for delivering material to be ground to the region beneath said central opening;
• gas supply means disposed for delivering conveyor gas to the region beneath said central opening;
• and a blower facility including a single stage radial blower fastened to said rotor for rotation therewith, carrying a number of backward curved blades, and disposed near the bottom of said stator below the lowermost milling section for conveying material to be ground and conveyor gas from the region beneath said central opening to said milling sections.

A grinding mill containing a plurality of milling sections and comprising:

• a single cylindrical stator common to all milling sections and having a longitudinal axis which is substantially vertical when said mill is in operation;
• a rotor mounted in said stator for rotation about the longitudinal axis and having a plurality of milling plates each extending parallel to the longitudinal axis, each milling plate having a working surface disposed in a respective milling section;
• and a blower facility for conveying material to be ground and conveyor gas to said milling sections;
• wherein at least some of said milling plates are provided with a cut extending perpendicular to the working surface and dividing the working surface into two parts, and the two parts of the working surface are bent in respectively opposite directions to constitute means for breaking up eddies of the material and conveyor gas during grinding.

A grinding mill containing a plurality of milling sections and comprising:

• a single cylindrical stator common to all milling sections and having a top provided with an exit port, a bottom provided with an inlet port, and a longitudinal axis which is substantially vertical when said mill is in operation;
• a rotor mounted in said stator for rotation about the longitudinal axis and having a plurality of milling plates each extending parallel to the longitudinal axis and disposed in respective milling sections;
• material supply means disposed for delivering material to be ground to the inlet port;
• gas supply means disposed for delivering conveyor gas to the inlet port;
• a blower facility for conveying material to be ground and conveyor gas from the inlet port opening to said milling sections;
• a finger sifter rotatably mounted in said housing between said milling sections and said exit port for rotation relative to said rotor and for sifting material after passage through said milling sections;
• and independent drive means coupled to said sifter for rotating said sifter at a rate selected independently of the rate of rotation of said rotor.