Comminution (milling, grinding), sifting and mixing. Principle of equipment work.

ComminutionComminution (milling, (milling, grinding), sifting and grinding), sifting and

mixing. mixing.

Principle of equipment Principle of equipment work.work.

Plan

1. General concern about machines and equipment.

2. Processes of comminution. Characteristics.

3. Equipment for comminution.4. Processes of sifting. Equipment for

sifting.5. Processes of mixing. Equipment for

mixing.

Comminution – is a process of particle size of substance reduction 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.

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. Great (large) – in 2-6 times; 2. Medium - up 6-10 times; 3. Fine - at 10-50 times; 4. Micro fine - in 50-100 times; 5. Super fine - thin (colloidal) – in

100-10000 times.

Classification of the Classification of the equipment for milling: equipment for milling:

By the way of milling:

1. Cutting machine 2. Attrition machine 3. Compression machine 4. Impact machine 5. Impact - Centrifugal machine

By the degree of comminution:

1. crushers:

for great, medium, fine milling;

2. mills:

for micro fine, superfine (colloid) milling.

Classification of the Classification of the equipment for milling: equipment for milling:

By the mechanism used to break the particles:

1. Disc 2. Boll 3. Rotor 4. Hammer 5. Rollers and others

Classification of the Classification of the equipment for milling: equipment for milling:

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. 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 - IMPACT - CENTRIFUGAL MILLS: CENTRIFUGAL MILLS:

Hammer millHammer mill

DysmembratoDysmembratorr

Disintegrator Disintegrator

Hammer mill

1 - rotor;

2 - hammer ;

3 - corps;

4 - plates.

Hammer mill

Hammer mill

Disintegrator

Machines for fine milling:Machines for fine milling:

Drum mills:Drum mills: Ball mills Ball mills Rod mills Rod mills Mills, in which material are milled Mills, in which material are milled

by acting of own weight: by acting of own weight:

* Mills Continuous action * Mills Continuous action

* Mills periodic action* Mills periodic action

Ball mill

Ball mill

Work of Ball mill

Machines for Superfine milling : Machines for Superfine milling :

Vibration mills Vibration mills Jet mills Jet mills Colloidal mills:Colloidal mills: Rotor - Pulsating apparatus Rotor - Pulsating apparatus

(RPA) (RPA)

Work of Jet mills

Jet mills

Equipment for Colloidal milling (vibration-cavitation mill, Conical mill )

Sifting Sifting (Sorting, Screens) - (Sorting, Screens) -

is process department is process department more large or more more large or more small particles of small particles of

primary mass separation primary mass separation loose materials on loose materials on

separate fraction that separate fraction that differ form and size. differ form and size.

Factors what affect on Factors what affect on process of Sifting : process of Sifting :

1.1. Shape and size of sievesShape and size of sieves

2.2. Thickness of material layer on Thickness of material layer on sievesieve

3.3. Humidity of materialHumidity of material

4.4. Movement speed of materials on Movement speed of materials on the sieve the sieve

5.5. Nature of movement and length of Nature of movement and length of way materialway material

6.6. Work Speed of Work Speed of siftingsifting

Classification sieves Classification sieves depend depend on way of productionon way of production::

1. Wicker sieve - by binding thin filaments or wires, with silk, steel and others. Filaments are easily extracted and not strong, although cheap.

2. 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.

3. Combination – by combination metal plates. They are very strong, but have low productivity.

Classification sieves depend Classification sieves depend

on nature of movementon 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 is used for Mixing is process is used for achievement uniformity of achievement uniformity of

mixtures.mixtures.

Classification of mixers: 1. Mixers with rotating blades2. Mixers with rotating corps3. Circulation mixers which contains

cone that rotates on a vertical axis4. Mixers with fluidized layer

(material is thrown up by the air pressure).

Mixer with rotating corps Mixer with rotating corps PattersonPatterson--Kelley Kelley

Mixer with rotating corps Mixer with rotating corps PattersonPatterson--Kelley Kelley

Mixer with rotating corps Mixer with rotating corps Ambica Boiler & Fabricators Ambica Boiler & Fabricators

Mixer with rotating blades Mixer with rotating blades Ambica Boiler & Fabricators Ambica Boiler & Fabricators

Mixer with continuous Mixer with continuous actionaction

Mixer - "Drunk barrel"Mixer - "Drunk barrel"

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