PHARMACEUTICAL ENGINEEERING UNIT I - II Size reduction.pptx

Size Reduction: Objectives, Mechanisms, factors affecting size reduction, principles, construction, working, uses, merits and demerits of Hammer mill, ball mill, fluid energy mill, Edge runner mill & end runner mill.

1. Progressive Education Society’s Modern College of Pharmacy, Yamunanagar , Nigdi , Pune 411044 1

2. Size reduction techniques Mr. Shubham R. Khade Assistant Professor Department of Pharmaceutics Modern College of Pharmacy, Nigdi , Pune 2

3. Size reduction

4. Size reduction is a process of reducing large solid unit masses, coarse particles or fine particles. Precipitation Mechanical Substance is dissolve in appropriate solvent Mecha n ic a l force i s i n t r od u c ed

5. Objectives of Size Reduction: In material processing industry, size reduction is usually carried out in order to Increase the surface area because in most reactions involving solid particles, the rate of reactions is directly proportional to the area of contact with second phase. Break a material in very small particles in order to separate the valuable amongst the two constituents. Achieve uniform mixing To improve handling of material To mix solid particles more intimately.

6. Advantages

7. Disadvantages: Drug Degradation Contamination

8. Mechanism of size reduction Mode of size reduction

9. Factors Affecting Size reduction

10. Hard Materials Iodine and Pumice are hard and abrasive. In general hard materials are most difficult to comminute. For iodine, hammer mill or the fluid energy mill is used. Size reduction process of such material can lead to abrasive wear of milling parts which then causes contamination . Fibrous material: Glycerine, rauwolfia & ginger are fibrous in nature and cannot be crushed by pressure or impact. Fibrous material are tough in nature. They must be teared by a cutter.

11. Friable material: Sucrose and dried filter cake are friable and tend to fracture along well define planes. Brittle substances can be easily converted to smaller particles such materials are milled by the mechanism such as attrition impact or pressure. For example, sugar is milled using hammer and fluid energy mills Elastic material: Synthetic gum waxes and raisins become soft and plastic during milling. These low melting substances should be mill chilled before milling. Such materials are milled using the hammer mill, colloid mill and fluid energy mill

12. Hygroscopic material substances such as a potassium carbonate absorb the moisture rapidly this wet mass sticks and clogs the Mill They are prepared in a closed system such as a porcelain ball mill Solvated materials sodium sulphate and other hydrated liberate water during milling and causes the clogging of the mill Melting point solid with low melting point often become soft and melt owing to the heat generated during milling. such materials are chilled before milling

13. Thermalability Certain substances undergo degradation reactions such as hydrolysis and oxidation due to the presence of moisture and atmospheric oxygen such reaction proceed faster moving to the heat produced during milling They should be milled in a closed system with an inert atmosphere of carbon dioxide on nitrogen vitamins and antibiotics are milled using the fluid energy and the ball mills

14. Particle size of feed For a mill to operate satisfactory the feed should be a proper size for example pre-treatment of fibrous material with high pressure roller or cutters facilities for further communication Moisture content presence of more than 5% of water hinder the milling process and produce the sticky mass The effect is more pronounced when the concentration of water is more In general materials with moisture content below 5% are suitable for dry grinding and from 5 % to 50% are suitable for wet grinding

15. Particle size: If extreme size control is necessary it may be essential to recycle the larger particle. This can be achieved by screening the discharge material and returning the oversized particle for a second time milling Moderately coarse & coarse powders with a minimum of fine powders are easily obtained using a high-speed impact mill for example, belladonna leaves and the roots are easily broken down by the impact mail

16. Ease of sterilization when preparation are intended for parenteral and ophthalmic uses size reduction should be conducted in the sterile environment The equipment should be sterilisable. Ball mills and the fluid energy mill suitable for this purpose Contamination of mailed material In case of potent drug and low dose product contamination of product should be avoided Use of equipment that is free from wearing of mill parts is preferred. Fluid energy mill is suitable for this purpose

17. Explosivity , irritability & toxicity. s relate tconomy Cost, power consumption, space occupied and labour cost are some economic factors that determine the selection of mill..

18. CLASSIFICATION OF SIZE REDUCTION EQUIPMENT A. Crusher Ex-edge runner mill, end runner mill. B. Grinder (1)Impact mill. ex-hammer mill. (2)Rolling-compression. ex-roller mill. (3)Attrition mills, ex-attrition mill. (4)Tumbling mills. ex-ball mill. C. Ultrafine grinder ex-fluid energy mill. D. Cutting machine ex- cutter mill. 19

19. TECHNIQUES ROTARY CUTTER MILL MORTAR AND PESTLE ROLLER MILL HAMMER MILL BALL MILL FLUID ENERGY MILL COLLOID MILL EDGE RUNNER MILL END RUNNER MILL 20

20. ROTARY CUTTER MILL Principle: In the cutter mill, size reduction involves successive cutting or shearing the feed materials with the help of sharp knives. 21 Fig: Rotary cutter mill

21. W orking: 22 Rotor disc rotate at 200-900 revolution per min. Feed material loaded through hopper. Mate r ial is c u t b e tw e en r o ta t ing & st atio n ary k n ives in s m all pieces, therefore particle pass through the screen product is collected into receiver. Uses: Size reduction (finer than 80-100 mesh) of tough and fibrous material. Ex. Medicinal plant, plant parts and animal tissue. It a lso us e d i n m an u facture of r u bbe r , p l asti c s, re c y c ling of paper waste and plastic material.

22. MORTAR AND PESTLE 23 This is the classical and the simplest equipment for grinding. It is work on application of attrition and pressure. In this equipment both mortar and pestle are rotating. This eq u i p m ent cann o t be p rov i d ed with a si e v e fo r c on t inuous removal of fines.

23. ROLLER MILL Principle: The material is crushed (compressed) by the application of stress. The stress is applied by rotator wheels, rollers. W o r kin g: The rollers are allowed to rotate. The material is feed into hopper through gap between two rollers by applying high pressure material is cursed. Uses: Roller mill is used for crushing and cracking of seed before extraction of fixed oils and also used to crush soft tissue to help in the penetration of solvent during extraction process. 9 Fig: Roller mill . F e e d H o pp er Rollers

24. HAMMER MILL Principle: The hammer mill operates on the principle of impact between rapidly moving hammer mounted on a rotor and the powder material . Working: The hammers are allowed to be in continuous motion(8000- 15000 rpm) the feed material is placed into the hopper, whiles hammers are in continuous motion. Uses: Particle size obtained from 10-400mm. Also used to mill dry, wet and filter press cakes materials. 11 Fig: Hammer mill

25. Advantage : Easy to setup and clean up. Occupies small space . Disadvantage: Heat b u i l dup dur i ng m i l ling i s m ore, therefore, product degradation is possible. Not suitable for milling of soft, tacky and fibrous materials. 12

26. BALL MILL Principle: The ball mill works on the impact between the rapidly moving ball and the powder material, both enclosed in a hollow cylinder. Thus, in the ball mill, impact or attrition or both are responsible for the size reduction . Working: The drug is filled into cylinder 60% of the volume. A fixed number of ball introduced and cylinder is close . Uses: Fine grinding with a particle size of 100-5 mm or can less can be obtained. Fig: Ball mill 13

27. Very fine powder produce. Suitable for both wet and dry grinding processes. Close system, sterility can be achieved. Disadvantage: Very noisy machine. Not suitable for milling of soft, tacky and fibrous materials. 29 Advant ag e :

28. Fluid Energy Mill Principle: Fluid energy mill operates on the principle of impact and attrition T he feed stock is suspended with in a high velocity air stream . Working: Powder is introduced through the inlet of venture. Air introduce through the grinding nozzles transport the powder in the circular track of the mill. The turbulent air stream break the particles colloids with each other and break. Particles are carried out to outlet and the coarse particle undergo recirculation. 16 Fig: Fluid energy mill

29. Uses: Fluid energy mill is used to reduce the particle size(10 325mesh) of most of the drugs such as antibiotics and vitamins. Ultrafine grinding can be achieved moderately hard material can be processed for size reduction . Advantages: Contamination is not possible Disadvantage: Not suitable for milling of soft, tacky and fibrous materials

30. COLLOID MILL Principle: Colloid mill consist of 2 steel disc having very small clearance between them. One disc is rotating, while the other one is stationary . Working: Suspension and emulsion are placed in hopper. The solid are mixed with the liquid vehicle before introduce into colloid mill Rotor is moved 3000 to 20000 rpm. The dispersion flow down and adher to the rotor. 19 Fig: Colloid Mill

31. Uses: Colloidal dispersion, suspension, emulsion, and ointment. Advantage: Production of sterile product. Disadvantage: Not useful to dry milling.

32. EDGE RUNNER MILL Principle The size reduction is done by crushing due to heavy weight of stone . Working: Material to be ground is placed on the bed at the same time travel around the shallow stone bed so the size reduction is achieved by sharing as well as crushing. 21 Fig : Edge runner mill

33. Uses : Grinding tough material to fine powder. Advantages: Does not require attention during operation. Disadvantages: More space than other mill, contamination , time consuming, Not use for sticky materials.

34. END RUNNER MILL Principle: Size reduction is done by crushing due to heavy weight of steel pestle. Shearing stress is also involved during movement of mortar and pestle . W o r king : The material to be ground is placed in the mortar. The mortar revolves at a high speed. The revolving mortar causes the pestle to revolve during this process, size reduction is achieved. 23 Fig: End runner mill

35. 37 Uses: Use for fine grinding. Disadvantages: Not suitable for unbroken or slightly broken condition of drug.

36. REFERENCES 39 Aulton , Aulton Pharmaceutics, The Design And Manufactures of Medicines, 1 st Edition (1988), Churchill Livingstone; pp.140-144. Leon Lachman, The Theory And Practice Of Industrial Pharmacy, 1 st Edition (1970), Varghese Publication House; pp. 34-45. Kamath A. Method Of Size Reduction And Factor Affecting Size Reduction In Pharmaceutics: A review.2013;4(8):57-64 Su b rah m a n y a n C. V . S . Ph ar m a c e u tic a l Eng i n e ering P r i n c i p l es and P r act i ce s, 1 st Edition (2001), Vallabh Prakashan; pp.148-164. Pawar A t m a r a m , Intro d ucti o n t o P h a r m a ceu t i c s, 1 s t Edi t i on ( 2008 ) , Career Publication; pp. 207-214.

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