DESINTEGRATION 

HOME  C803CFR  IN MEMORIAM  V. I. P. = V. I. P  SITE MAP  ALPHABETIC MAP  GLOBAL LAWS  ETHANOL  ATMOSPHERE  COPPER/PLASTIC  DISTILLATION  FEEDSTOCK$  FERMENTATION  BOILER / REBOILER  HEAT EXCHANGER  GO SOLAR  TOOLS  ELECTRO  ENGINES  S.E.E.F.A  LINKS  REFERENCES  APPENDICES  DOWNLOADS  ETHANOL FUEL MANUAL  FACTS


Enter subhead content here 

DISINTEGRATION 1
Percentages of material greater than 50% of the maximum size are about 50% from rolls, 15% from tumbling
mills, and 5% from closed circuit ball mills. 2
Closed circuit grinding employs external size classification and return of oversize for regrinding. The
rules of pneumatic conveying are applied to design of air classifiers. Closed circuit is most common with ball and roller
mills. 3
Jaw crushers take lumps of several feet in diameter down to 4 in. Stroke rates are 100300/min. The average
feed is subjected to 810 strokes before it becomes small enough to escape. Gyratory
crushers are suited to slabby feeds and make a more rounded product. 4
Roll crushers are made either smooth or with teeth. A 24 in. toothed roll can
accept lumps 14 in. dia. Smooth rolls effect reduction ratios up to about 4. Speeds are 50900 rpm. Capacity is about 25%
of the maximum corresponding to a continuous ribbon of material passing through the rolls. 5
Hammer mills beat the material until it is small enough to pass through the screen at the bottom of the
casing. Reduction ratios of 40 are feasible. Large units operate at 900 rpm, smaller ones up to 16,000 rpm. For fibrous materials
the screen is provided with cutting edges. 6
Rod mills are capable of taking feed as large as 50 mm and reducing it to 300 mesh, but normally the product
range is 865 mesh. Rods are 25150 mm dia. Ratio of rod length to mill diameter is about 1.5. About 45% of the mill volume
is occupied by rods. Rotation is at 5065% of critical.
7. Ball mills are better suited than rod mills to fine grinding. The charge
is of equal weights of 1.5, 2, and 3 in. balls for the finest grinding. Volume occupied by the balls is 50% of the mill volume.
Rotation speed is 7080% of critical. Ball mills have a length to diameter ratio in the range 11.5. Tube mills have a ratio
of 45 and are capable of very fine grinding. Pebble mills have
ceramic grinding elements, used when contamination with metal is to be avoided.
7
Roller mills employ cylindrical or tapered surfaces that roll along flatter surfaces and crush nipped
particles. Products of 20200 mesh are made. 

Enter supporting content here 
