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Particle Size Reduction & Separation

Particle Size Reduction & Separation. Kausar Ahmad Kulliyyah of Pharmacy. http://staff.iium.edu.my/akausar. Contents. Particle size reduction Fluid energy mill or jet mill Air classifier mill Others Crusher Grinder. Particle size separation Cyclone Others Sieves Classifiers

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Particle Size Reduction & Separation

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  1. Particle SizeReduction & Separation Kausar Ahmad Kulliyyah of Pharmacy http://staff.iium.edu.my/akausar PHM3133 Dosage Design 1 2011/12

  2. Contents Particle size reduction • Fluid energy mill or jet mill • Air classifier mill • Others • Crusher • Grinder Particle size separation • Cyclone • Others • Sieves • Classifiers • Membrane filtration PHM3133 Dosage Design 1 2011/12

  3. Equipment & mechanism • Crusher – compression • E.g. crushing rolls (5 mm) • Grinder – impact and attrition • E.g. hammer/ball millls, bowl grinder (100 m) • Ultra-fine grinder – attrition • E.g. fluid-energy mills (5 m) • Knife - cutting • E.g. carrot slicer ( 5 mm) PHM3133 Dosage Design 1 2011/12

  4. Choosing the equipment PHM3133 Dosage Design 1 2011/12

  5. Step-by-step size reduction Feed material 10 cm Crusher : 10x Feed 1 cm Grinder: 100x Feed 100 m Fluid energy mill: 20x Product ca. 5 m HOW MANY TIMES REDUCTION? PHM3133 Dosage Design 1 2011/12

  6. Attrition mills - principle • attrition - the act of wearing or grinding down by friction • hit the particles with high velocity air to fracture them • increasing the impact velocity or the energy (increase temperature), produces smaller particles • generate a greater amount of fines PHM3133 Dosage Design 1 2011/12

  7. Types of attrition mills • Fluid energy mill • High pressure steam, high T • Compressed air, high T • Air classifier mill • Air • FEED into slightly negative pressure compartment! • Q. But why? PHM3133 Dosage Design 1 2011/12

  8. Classifier • Equipment that is used to narrow down the size distribution of product • Normally built-in design i.e. comes together with the mill • Classifying ability depends on • Design and operation condition • Feed throughput • Air velocity PHM3133 Dosage Design 1 2011/12

  9. Air classifier mill • Consists of: • Hammer mill • Hammer mill reduces the size • Classifier • Classifier determines the size distribution • Size and distribution depends on • Design of mill and classifier • Operation conditions • Their speed of rotation • Feed throughput PHM3133 Dosage Design 1 2011/12

  10. Air classifier mill (ACM) PRODUCT ca. 100 m (to Fluid Energy Mill) CLASSIFIER ROTATE FEED ROTATE ATMOSPHERIC AIR PHM3133 Dosage Design 1 2011/12

  11. Fluid Energy Mill (FEM) FEED (from ACM) Area enlarged Superheated compressed Air/steam PHM3133 Dosage Design 1 2011/12

  12. FEM: Design & Operation Size and distribution depends on • Design • Air nozzles • Feed inlets • Grinding chamber • Operation conditions • Air/steam at high pressure and temperature is introduced into the chamber and reduces the size of particles • Feed throughput PHM3133 Dosage Design 1 2011/12

  13. FEM After size reduction Air/steam at high P, T PHM3133 Dosage Design 1 2011/12

  14. Size reduction & separation ? CYCLONE FEED into FEM injector CYCLONE FEM PRODUCT HIGH VELOCITY HOT AIR/STEAM PRODUCT PHM3133 Dosage Design 1 2011/12

  15. Cyclone • Equipment for separation • To separate product from air and/or fines • Based on centrifugal force • Heavy particles settle down • Fine particles escape PHM3133 Dosage Design 1 2011/12

  16. Cyclone FINES OUTLET FROM FEM INLET PRODUCT PHM3133 Dosage Design 1 2011/12

  17. Factors affecting extent of separation • Design of cyclone • Diameter • Height • Operation of cyclone • Feed throughput • Velocity at inlet PHM3133 Dosage Design 1 2011/12

  18. Feed properties • Need to know size distribution of the feed stream. • may lead to significant cost-reduction methods • such as pre-classifying the material to remove fines before milling. • Thus, use air classifier mill first, followed by fluid energy mill. PHM3133 Dosage Design 1 2011/12

  19. Controlling feed/throughput feeding the material into a mill, and handling the product discharging from it, can pose a significant problem e.g. FEM back-flow feed at a controlled rate is critical to optimizing the performance of mills. PHM3133 Dosage Design 1 2011/12

  20. Problems with poor feed-control PHM3133 Dosage Design 1 2011/12

  21. Example of equipment wear Internal piping CONSTRUCTION MATERIAL + FEED FEM milling area PHM3133 Dosage Design 1 2011/12

  22. Problems with FINE products • Highly charged, static • May produce sparks • Possible explosion • Need to earth equipment • Very cohesive • Stick to silos • Form agglomerates • Poor flow • Add (pyrogenic) silica to allow free flow • Health hazard…………….. De-duster PHM3133 Dosage Design 1 2011/12

  23. Dust Filter http://www.pharmaceuticalonline.com/nl/347748/1849996 PHM3133 Dosage Design 1 2011/12

  24. Exercise • What do you do with so much air/steam in your milled products? • What is the difference between a fluid energy mill and a fluidised bed dryer? • Function? • Operating principle? PHM3133 Dosage Design 1 2011/12

  25. References Levin, M. (2002). Pharmaceutical process scale-up. New York: Marcel Dekker. p 71, 120, 205, 224, 322, 417, 501, 503 PHM3133 Dosage Design 1 2011/12

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