pharmaceutical engineering, p'engg, size separation

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1. Size SEPARATION

2. Size reduction: Operation carried out for reducing the of size of larger particles into smaller one of desired size, shape with the help of external force. SIZE SEPARATION: Unit operation which involves separation of particles of a particular size range from a mixture of different sized particles.

3. Other names : 1. Sieving, 2. Shifting , 3. Separation, 4. Classification, 5. Screening.

4. Material that remains on the given screening surface is “Oversize” or “ Plus material” Material passing through the screening surface is “Undersize” Or “Minus material”

5. Applications: 1.U𝚗𝚒𝚏𝚘𝚛𝚖 𝚍𝚘𝚜𝚊𝚐𝚎 𝚏𝚘𝚛𝚖. 2.𝚂𝚎𝚙𝚊𝚛𝚊𝚝𝚎 𝚞𝚗𝚠𝚊𝚗𝚝𝚎𝚍 𝚙𝚊𝚛𝚝𝚒𝚌𝚕𝚎𝚜. 3.𝚃𝚘 𝚖𝚊𝚗𝚞𝚏𝚊𝚌𝚝𝚞𝚛𝚎 𝚝𝚊𝚋𝚕𝚎𝚝, 𝚐𝚛𝚊𝚗𝚞𝚕𝚎𝚜, 𝚌𝚊𝚙𝚜𝚞𝚕𝚎, 𝚎𝚝𝚌..... 4.𝙸𝚗 𝚝𝚘𝚙𝚒𝚌𝚊𝚕 𝚍𝚘𝚜𝚊𝚐𝚎 𝚏𝚘𝚛𝚖 𝚜𝚞𝚌𝚑 𝚊𝚜 𝙾𝚒𝚗𝚝𝚖𝚎𝚗𝚝, 𝚙𝚊𝚜𝚝𝚎 & 𝚌𝚛𝚎𝚊𝚖𝚜. 5. 𝚃𝚘 𝚒𝚗𝚌𝚛𝚎𝚊𝚜𝚎 𝚝𝚑𝚎 𝚜𝚝𝚊𝚋𝚒𝚕𝚒𝚝𝚢 𝚘𝚏 𝚜𝚘𝚖𝚎 𝚏𝚘𝚛𝚖𝚞𝚕𝚊𝚝𝚒𝚘𝚗. 𝙴𝚐: 𝚂𝚝𝚊𝚋𝚒𝚕𝚒𝚝𝚢 𝚘𝚏 𝚂𝚞𝚜𝚙𝚎𝚗𝚜𝚒𝚘𝚗.

6. Mechanism: : 1.𝘼𝙂𝙄𝙏𝘼𝙏𝙄𝙊𝙉 2.𝘽𝙍𝙐𝙎𝙃𝙄𝙉𝙂 3.𝘾𝙀𝙉𝙏𝙍𝙄𝙁𝙐𝙂𝘼𝙏𝙄𝙊𝙉 1.Oscillation 2.Vibration 3.Gyration

7. Agitation methods: Sieves are agitated in number of ways. 1.Oscillation Sieve is mounted in a frame that oscillates back and forth . ie. Reciprocal motion.

8. 2.Vi bration: Sieve is vibrated at high speed by means of an eccentric device either electrically or mechanically. 3.Gyration: System is made, sieve is on rubber mounting & connected to an eccentric flywheel.

9. Advantages: Inexpensive Simple Rapid Disadvantages: Lower limit of particle size. Powder is not dried, clogged particles.

10. Brushing method: Brush is used to move particles on the surface of sieves to keep meshes clear. CENTRIFUGAL METHOD: A high speed rotor is fixed inside a vertical cylindrical sieve, rotation of particles are thrown outwards by centrifugal force.

11. Equipment for size separation: Sieve shaker Cyclone separator Air separator Bag filter Elutriation tank

12. 1.SIEVE SHAKER: Principal Construction Powdered drug is separated according to its particle size using a number of sieves in a nest. Standard sieves of different mesh number are available commercially as per the specifications of IP & USP. Sieves are fixed in a mechanical shaker apparatus.

13. Working Sieves are arranged in a nest with the coarest at the top . Sieve set is fixed to the mechanical shaker apparatus & shaken for a certain period of time . The powder retained on each sieve is weighed.

14. #Utilize maximum no. 10 test sieves in one experiment. #Accuracy . #Efficient than manual hand sieving. #Automatically works if timer is set. ADVANTAGES: Sieve shaker

15. DISADVANTAGES: # Chances of clogging. # Attrition may occur. #Not suitable for smaller particles . #Less accurate. Uses: Development of tablet & capsule. Handling dry powder & dry food. Coarse material down to 150 micro meter. Particle analysis of variety of materials.

16. 2.Cyclone separator: PRINCIPAL Centrifugal force is used to separate solid from fluids. Depends on particle size & particle density. Allow fine particles to be carried with the fluid.

17. Construction Short vertical, cylindrical vessel with a conical base. Upper part of the vessel is fitted with a tangential inlet. Outlet ( solid outlet) arranged at the base. Fluid outlet at the center of the top portion. These arrangements prevents the air short circuiting from inlet to outlet.

18. Working Solids to be separated are suspended in a steam of gas. Feed introduced tangentially at a very high velocity. Rotary movement takes place within vessel. Centrifugal force & vortexing throws solids to walls. Speed diminshes, particles discard to solid outlet. Fluid escape from central outlet at top.

19. Types Wet cyclone Dorrclone Vertical cyclone separator Single-cyclone separator Multi-cyclone separator Cyclone separator

20. Advantages Low capital cost No moving parts Low pressure drop Dry collection & disposal High efficiency High volume flow rate Operate at high temperature Less maintain requirements Small space for installation

21. Disadvantages High operating cost Inability to handle sticky material Low efficiency for small materials Can't handle viscous flow Reduced efficiency when overloaded it's capacity

22. Uses: Separate solid particles from gases Size separation of solids in liquids Separate heavy & coarse fraction from fine dust Extract waste powder before reaches central extraction system Used as spray or fluid bed drying Particle free clean air

23. 3.Air separator: Principal Centrifugal force is used to separate solids. Finer particles are carried away by air. Coarse particles thrown by centrifugal force, fall at bottom. Air environment is for rotating disc & blades. To improve separation, stationary blades are used. Carry various size of particles.

24. Construction Cylindrical vessel with conical base. Feed inlet fitted at upper part of vessel. Rotating disc & rotating blades attached to central shaft to produce air environment. One for fine particles, other for heavy particles. Two outlets are provided.

25. Working Disc & blades are allowed to rotate by motor. Current of air is produced. Sample powder is feeded through inlet. Feed falls on rotating disc. Fine particles are picked up & carried out. Heavy particles fall downward & removed through outlet.

26. Efficient separation Low maintenance High reliability A DVANTAGES : Low pressure drop No moving parts Easy to operate Air separator

27. Disadvantages: Low separation yield Unsuitable for separating smaller particles Not suitable for wet & sticky materials. Uses: Attached to ball mill & hammer mill to separate & reduction. Separate dry powders in micron. Improve air quality in pharmaceutical production area. Collection of metal working fluids, coolant or oil mists. Dust collector.

28. 4.Elutriation tank P RINCIPAL Elutriator is a straight forward device divides particles into two or more groups. Fluid moves in the opposite direction of particles sedimentation. Particle size, shape, & density play role. Air elutriator mostly utilized for particles diameter less than 1m.

29. Construction Vertical column with a suspension intake near the bottom. Coarse particles outlet near the base Fluid overflow near the top. Each column give a single separation into two fractions. Velocity gradient across tube, resulting in separation different sizes based on distance. More than one fraction, sequence of tubes increase cross sectional area can connected.

30. Working Materials to be separated first levigated & paste is transferred to elutriation tank. Large amount of water added to make independent particle settling. Content in tank stirred to uniform particle distribution. Coarse particles settle at bottom, small size particles remain suspended in liquid. Fine particles transfered to next elutriator.

31. Advantages Continuous Quicker than sedimentation Has feasibility No skilled operators. Fast process Elutriation tank

32. Disadvantages Undesirable due to dilute suspension Separate based on sedimentation not on specific feature. Can't separate different types of particles. Uses Separate large particles Separate insoluble solids Applied to finer solids.

33. 5.Bag filter: PRINCIPAL Size separation of fines or dust from the milled powder is done in two steps. First step is passed through a bag, facilitates separation. Second step pressure is applied, powder collected from conical base. Applying suction on opposite side of feed entry.

34. Construction Has number of bags made of cotton or wool fabric. Suspended in a metal container. Hoper is arranged at bottom of filter to receive feed. At top, provision made for vacuum fan & exhaust discharge manifold. At top bell crank lever arrangement, change filtering to shaking.

35. Two steps Filtering period Shaking period Filtering period Vaccum fan produce a pressure lower than atmospheric pressure. Gas enters hoppers, passes bags, out at top of apparatus. Shaking period Bell crank lever first close discharge manifold Air enters through top, vacuum is broken. Gives violent jerking action so bags are freed from dust. Fine particles are collected at conical base.

36. Advantages Remove lines Remove dust Low electricity consumption Trouble free operation Simple Healthy environment Bag filter

37. Disadvantages Not a size separation equipment Large in size High cost High gas temperature & high humidity. Uses Used along size separation equipment Remove fines from cyclone discharge Clean air of room Fluidized bed dryer Household vacuum cleaner is a simple version of bag filter.

38. By , M.R.CHARU LATHA., Aadhi bhagawan college of Ph armacy; Rantham . Mentored by, L.G OPI; Assistant professor of Pharmaceutics