Comminution (milling, grinding), sifting and mixing. Principle of equipment 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 times; 4.Micro fine - in times; 5.Super fine - thin (colloidal) – in times.

Classification of the 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 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 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

Cutting mill

Rollers mill 1,2 - rolls 3 - spring

Rollers mill

Disk mill (Excelsior)

IMPACT - CENTRIFUGAL MILLS: Hammer mill Hammer mill Dysmembrator Dysmembrator Disintegrator Disintegrator

Hammer mill 1 - rotor; 2 - hammer ; 3 - corps; 4 - plates.

Hammer mill

Disintegrator

Machines for fine milling: Drum mills: Ball mills Ball mills Rod mills Rod mills Mills, in which material are milled by acting of own weight: Mills, in which material are milled by acting of own weight: * Mills Continuous action * Mills periodic action

Ball mill

Work of Ball mill

Machines for Superfine milling : Vibration mills Vibration mills Jet mills Jet mills Colloidal mills: Colloidal mills: Rotor - Pulsating apparatus (RPA) 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. Shape and size of sieves 2. Thickness of material layer on sieve 3. Humidity of material 4. Movement speed of materials on the sieve 5. Nature of movement and length of way material 6. Work Speed of sifting

Classification sieves depend on way of production : 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 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 Sieve that swing - is installed on the box spring rests at an angle to the horizontal 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 achievement uniformity of mixtures. 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 Ambica Boiler & Fabricators

Mixer with rotating blades Ambica Boiler & Fabricators

Mixer with continuous action

Mixer - "Drunk barrel"

Thank you for your attention