Lecture 2
General concept about machines
and equipment.
Comminution (milling, grinding),
sifting, mixing.
Plan
1. General definition about machines
and equipment.
2. Processes of comminution.
Characteristics.
3. Equipment for milling.
4. Processes of sifting. Equipment for
sifting.
5. Processes of mixing. Equipment for
mixing.
Comminution – is a process of reduction
of particle size of substance by
mechanical influence.
Motivation for particle size reduction:
increase specific surface of substances,
 increase the free surface energy of crushed
substances,
 significantly increase the speed of chemical and
diffusion processes,
 strengthen the pharmacological activity of
substances.

Comminution is characterized by
the symbol index –”i” - the degree of
comminution of substances.
“I” equal ratio of the diameter of
pieces of material to the milling (D) to
particles diameter after ones (d).
i=D/d
Types of milling in depend on degree
of comminution
(in haw much times the particles size was
reduced):
1.
2.
3.
4.
5.
Great (large) – in 2-6 times;
Medium - up 6-10 times;
Fine - at 10-50 times;
Micro fine - in 50-100 times;
Super fine - thin (colloidal) – in 10010000 times.
Classification equipment for
milling:
By the way of milling:
Cutting machine
2. Attrition machine
3. Compression machine
4. Impact machine
5. Impact - Centrifugal machine
1.
Classification equipment for
milling:
By the degree of comminution:
1. crushers:
for great, medium, fine milling;
2. mills:
for micro fine, superfine (colloid) milling.
Classification equipment for
milling:
By the mechanism used to break the
particles:
1.
2.
3.
4.
5.
Disc
Boll
Rotor
Hammer
Rollers and others
Requirements for the milling
process:
1. Substances must has initial its
composition and pharmacological
properties during the milling process;
2. Periodically to remove enough milled
particles from the sphere of comminution;
3. Prevent formation of dust (sealed
enclosures);
4. Appropriate moisture of material;
5. The use of sequence connected
crushing-milling machines.
Parameters for choosing optimal type of
machines:
1.
Initial size of the material and desirable
size of final product
2.
The total amount of material for milling
3.
4.
Physical and chemical properties of
material for milling
Cutting machine are used to comminution
herbal drug that has a fibers structure.





Grass cutting and straw cutting (grass, stalks).
Root cutting with the guillotine knife - for grinding
roots, bark.
Drum straw cutting - for grinding dry medicines.
Knife mill - for milling volume materials, containing
cellulose
Motorized soft meat grinder - for fresh herbal
drugs, animal raw materials
Crushes machines which are
used for milling solid materials:

Cheek and jaw mill

Rollers mill

Cone mill

Hammer mill

Disk mill (Excelsior)
Jaw mill type shock
Grasscutting
Grasscutting
Cutting mill
Rollers mill
1,2 - rolls
3 - spring
Rollers mill
Disk mill (Excelsior)
IMPACT - CENTRIFUGAL
MILLS:
 Hammer
mill
 Dysmembrator
 Disintegrator
Hammer mill
1 - rotor;
2 - hammer ;
3 - corps;
4 - plates.
Hammer mill
Hammer mill
Disintegrator
Machines for fine milling:
Drum mills:
 Ball mills
 Rod mills
 Mills, in which material are milled
by acting of own weight:
 Mills Continuous action
 Mills periodic action
Ball mill
Ball mill
Work of Ball mill
Machines for Superfine milling :




Vibration mills
Jet mills
Colloidal mills:
Rotor - Pulsating apparatus
(RPA)
Work of Jet mills
Jet mills
Equipment for Colloidal milling
(vibration-cavitation mill, Conical mill )
Sifting
(Sorting, Screens) is process department more large
or more small particles of
primary mass separation loose
materials on separate fraction
that differ form and size.
Factors what affect on
process of Sifting :
1.
2.
3.
4.
5.
6.
Shape and size of sieves
Thickness of material layer on sieve
Humidity of material
Movement speed of materials on the sieve
Nature of movement and length of way
material
Work Speed of sifting
Classification sieves depend on way
of make:
1.
2.
3.
Wicker sieve - by binding thin filaments or wires,
with silk, steel and others. Filaments are easily
extracted and not strong, although cheap.
Stamped sieve - by punching metal plate with the
formation of frequent round, oval or square
holes. They are very strong and widely used in
industry, but have rather large holes, so are not
suitable for small particles.
Combination – by combination metal plates.
They are very strong, but have low productivity.
Classification sieves depend on
nature of movement
1.
Sieves, rotary - a cylindrical drum sieve, which is
set at an angle. It consists of sections of sieves
with different size holes that can differentiate
between material in size.
2.
Sieve that swing - is installed on the box spring
rests at an angle to the horizontal 7-14.
3.
Vibration sieve - the structure is the same as in
sieve that swing , but have a great frequency
vibrations - vibrations.
Vibration sieve
Mixing is process which ia used for
achievement uniformity of mixtures.
1.
2.
3.
4.
Classification of mixers:
Mixers with rotating blades
Mixers with rotating corps
Circulation mixers which contains cone that
rotates on a vertical axis
Mixers with fluidized layer (material is thrown
up by the air pressure).
Mixer with rotating corps
Patterson-Kelley
Mixer with rotating corps
Patterson-Kelley
Mixer with rotating corps
Ambica Boiler & Fabricators
Mixer with rotating blades
Ambica Boiler & Fabricators
Mixer with continuous action
Mixer - "Drunk barrel"
Thank you
for
your attention