Roll mill and method for feeding particulate material

A method for feeding particulate material within a predetermined range of sizes to a roll mill which comprises a pair of rollers of predetermined axial length, having generally cylindrical outer surfaces forming a roll nip to grip said particulate material between said surfaces in an upper zone of the nip and for squeezing the particles below said upper zone in an intermediate nip zone, the method comprising the steps of

• feeding said particulate material in a width greater than said axial length by at least one centimeter;
• collecting the particulate material fed beyond the axial length;
• guiding all the collected particulate material to a level above said upper zone of the nip and discharging it thereinto the nip;
• and wherein
• said step of guiding includes a step of inhibiting a discharge of particles below said level for improved wearability of said rollers.

A roll mill comprising:

• a pair of rotatable rollers axially parallel to each other having a predetermined axial length between lateral end surfaces thereof, the rollers having substantially cylindrical outer surfaces forming therebetween a roll nip to grip particles within a predetermined range of sizes to be milled between said outer surfaces in an upper zone of the nip and for squeezing the particles below said upper zone in an intermediate nip zone when the rollers rotate about respective axes of rotation;
• feeding means for feeding said particles above a predetermined level to said rollers over a feeding width exceeding the axial length of said rollers;
• and
• guide means for limiting said feeding width, said guide means receiving said particles from said feeding means adjacent lateral ends of said feeding width and guiding and discharging all of the particles so received to above said upper zone of the nip adjacent said lateral ends of the rollers;
• and wherein
• said rollers comprise frusto-conical end portions, and said guide means comprise a wedge structure extending between said frusto-conical end portions of the rollers to inhibit discharge of particles below said predetermined level.

A roll mill comprising:

• a pair of rollers having a predetermined axial length between lateral end surfaces, and generally cylindrical outer surfaces forming a roll nip to grip particles within a predetermined range of sizes to be milled between said outer surfaces in an upper zone of the nip and for squeezing the particles below said upper zone in an intermediate nip zone, when the rollers rotate about respective axes of rotation of the rollers;
• feeding means for feeding said particles to be milled to said rollers over a feeding width exceeding the axial length of said rollers;
• channel means having a first end adjacent said feeding means and a second end adjacent the lateral ends of said rollers for limiting said feeding width and for guiding particles fed at the lateral lends of said feeding width towards the end surfaces of the rollers;
• guide means for the particles fed through said channel means, the guide means extending from said second end of the channel means to a level above said upper zone of the nip for discharging all the particles from said channel means above said upper zone of the nip;
• and wherein
• said rollers comprise frusto-conical end portions, and
• said guide means comprise a wedge structure extending between said frusto-conical end portions of the rollers to inhibit entry of the particles from said channel means into a side of the nip below said level.

A roll mill comprising

• a pair of rollers having a predetermined axial length between lateral end surfaces, and generally cylindrical outer surfaces forming a roll nip to grip particles within a predetermined range of sizes to be milled between said outer surfaces in an upper zone of the nip and for squeezing the particles below said upper zone in an intermediate nip zone, when the rollers rotate about respective axes of rotation of the rollers;
• feeding means for feeding said particles to be milled to said rollers over a feeding width exceeding the axial length of said rollers;
• channel means having a first end adjacent said feeding means and a second end adjacent the lateral ends of said rollers for limiting said feeding width and for guiding particles fed at the lateral ends of said feeding width towards the end surfaces of the rollers;
• and
• guide means for guiding the particles fed through said channel means to said rollers at a location above said nip, the guide means extending from said second end of the channel means to a level above said upper zone of the nip to prevent entry of the particles from said channel means below said level into a side of the nip, the guide means discharging all the particles from said channel means above said upper zone of the nip.