Particle Technology Flashcards
Equivalent Diameter is the diameter of the sphere having the same
ratio of surface to volume as the actual volume
Sphericity of Cylinder having equal L and D
0.87
S = π⅓ (6V)⅔ ÷ SA
S = 6V ÷ (SA*D)
Sphericity of hedrons
Tetra - 0.67
Hexa - 0.81
Octa - 0.84
Dodeca - 0.91
Icosa - 0.94
Units of measurements used for different sizes of particles
Coarse - mm, in, cm
Fine - mesh or screen size
Very fine - microns, nano
Ultrafine - SA/mass (e.g., m²/g)
Short distance transportation of grain gravel, sand is done using
screw conveyor
Power requirement of ball mill is proportional to
D^2.5
Screen for sizing very fine materials
Vibrating Screen
Plate and frame filter operates by
pressure
Tabular bowl centrifuges operate at ____ as/than disk bowl centrifuge
a. lower speed
b. higher speed
c. same speed
higher speed
Pebbles used in pebble mills are made of
flint or porcelain
Agitator for fibrous and dense slurries
Cone type
Centrifuge used in sugar mills
Suspended batch basket
Mesh sizes of this screen is arranged from smallest to largest. Used for powdered and granular feeds
Reciprocating screens
Mesh number is defined as
Number of apertures per linear inch
How to relate mesh number to screen opening/aperture?
Mesh Number (Aperture + Wire Diameter) = 1
Screen interval of Tyler Standard Sieve Series
√2
United States Sieve Series screen interval is
⁴√2
Cumulative Analysis or Plot in screening
Larger than Dp - mass fraction is the overflow of the mesh
Smaller than Dp - mass fraction is the underflow of the mesh
Relationship of screen effectiveness and screen capacity
Inverse
Ball mills and tube mills with flint or porcelain balls are used for size reduction of
non-metallic ores
Size reduction of ____ is accomplished in steam heated rollers and roll crushes
a. waxes
b. resins
c. gums
d. rubber
Rubber
Filter media is used to
increase the porosity if cake
Froth floatation is mist suitable for
a. iron ores
b. quartzite
c. sulfide ores
d. none
sulfide ores
Taggart’s formula
T=0.6LS
Equipment for Coarse, Hard Materials
Jaw crusher and Gyratory crusher
T/S² < 0.115 Jaw
T/S² > 0.115 Gyratory
Equipment for Coarse, Soft Materials ,e.g., gypsum, coal, ice, fire, shales, clay
Brandford breaker for coal
Tooth roll crusher (by pressure)
Hammer Mill
Squirrel Cage Disintegrator
Equipment for Intermediate size reduction
Crushing rolls (2 rolls rotating in opposite direction)
Cone crushers
Edge runner (clay industry)
Crushing roll, angle of nip formula
angle = 2@
cos @ = (r1 + b) ÷ (r1+r2)