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Industrial Pharmaceutical Size Reduction. Faculty of Pharmacy OCTOBER 6 University. SIZE REDUCTION. Process of reducing larger size solid unit mass to smaller size unit masses by mech Rate depend on the starting of the material its orientation & residence time in the mill .
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Industrial Pharmaceutical Size Reduction Faculty of Pharmacy OCTOBER 6 University
SIZE REDUCTION • Process of reducing larger size solid unit mass to smaller size unit masses by mech • Rate depend on the starting of the material its orientation & residence time in the mill . OBJECTIVES : 1- susp. Or to facilitate mix. Of powder . 2- increase SA , adsorptive power or mass TC. 3- expose cells before extraction . 4- reduce the bulk of a material .
PHARMACEUTICAL APPLICATION • 1- Increase SA / weight , increase TH E . • 2- Extract from animal glands & crude V D. • 3- The drying of wet masses . • 4- The mixing & blending . • 5- Lubricants. 6- milling of oint , creams & paste. • Tablet production : 1- reduction in size of oversized. 2- agglomerated raw material. -3-reduction in size of wet & dry granular material . 4- reduction of size of tab or compaction .
ADVANTAGE OF SR IN TABLET • 1- Increase SA. 2- Tablet content uniformity • 3- Improved flow prop. Of raw material exp needle or irregular shape . 4- Improved color & AI dispersion (migration) . 5-Uniformly sized wet G to allow uniform dry . 6- Controlled PS distribution ( tab wt uniformity) . 7- Minimize segregation while handing or table ting . 8- SA reproducibility lot to lot G. physical uniformity .
DISADVANTAGE • 1- Polymorphic ( unstable due to heat ) 2- Degradation due to oxidation or WV . 3- Decrease In bulk density lead to flow problem & segregation . 4- Decrease in PS increase in SE ,S/L interface decrease so reduce DR.5- Reduce PS lead to adsorption of air so reduce wet ability .
FACTORS AFFECTING SR • 1- Hardness : not strength , very hard but brittle , MOH”S SCALE 1~3 SOFT ,> 7 SOFT & 3~7 INTERMEDIATE . 2- Toughness : tough problem , reduce by treated with liquefied gas exp. LIQUID N2 . 3- Abrasiveness : hard materials from mineral origin . 4- Stickiness : difficulty to reduce size , exp . gummy or resinous sub. Due to heat so add inert sub.
5- Slipperiness : lubricant ( reveres stickiness ) 6- Softening temp. : exp. Wax or oil using water or air or liquid N2 to reduce temp. 7- Material stru. : exp. Mineral gives flake, & V. drugs lead to long particles . 8- MC :5% ground dry , 50% subjected to wet grinding . 9- Hormones or podophyllum used special air extraction systems or wet grinding .
10- Purity required : cleaning between batches . 11- Ratio of feed to product size : fine product require a small feed size , exp. Crushing , coarse grinding & then fine grinding . 12 – Bulk density : capacities of mills
HEAT GENERATED • 1- Plastic deformation of particles that are not fractured . 2- Friction of particles contact with mill . 3- Friction of particles colliding with each other . 4- Friction of particles with mechanical parts of the mill .
MECHANISMS OF SR • 1- CUTTING :cutting force. 2- COMPRESSION : crushing force . 3- IMPACT : direct , high velocity collision force . 4-ATTRITION : force that works to elongate or pull particle apart , surface are moving relative to each other .
SR EQUIPMENTS • THREE BASIC COMPONENT : 1- A structure for feeding material to mill . 2- The milled chamber & its working parts . 3- A take-off to a receiver or collector in which the milled product is deposited . One exception small-batch ball mills. Mills are also fitted with cyclones , centrifugation , for classifying the particles by size .
FLUID ENERGY MILL • It has no moving parts & is a rapid & efficient method reducing P. to 30 microns • LIMITATION : rate at which material fed to the mill , mill surface made from soft stainless steel to hard ceramics . • ADV. Heat labile sub. Can be milled with little danger of thermal degradation . • USES : 1- RPS of AI require very small PS ….. 2- Tablet content uniformity .
BALL MILL • Used to obtain extremely small particles , but not used in tablet granulation . • Conical shell can used for continuous milling with grinding media of equal or varied size , same for wet milling . • The higher the grinding media are carried up the chamber wall , the greater the capacity of the mill , & the more effective the impact grinding . • CM SPEED when C FORCE becomes > G force
CMSPEED : Nc= 76.6/ D revolution/min • CS & above = centrifugation • Optimum speed = 60-85 % of the CS • No = (57)-40(logD) revolution/min • Grinding also by attrition as media move against one another & walls of the mill .
Wet milling : used when material is insoluble ,so liquid can be utilized ,liquid contain surfactant to prevent PART flocculation , when dry milling cause caking of material . • DISADV.: difficulty in cleaning , long milling times , & high power requirements ,media is 30-50% of milling cha • VARIANTS OF THE BALL MILL : 1- Harding mill : the cylinder has a conical end towards a discharge point . 2- Tube mill : with long narrow cylinder . 3- Rod mill : has rods instead of balls . 4- Vibration mill : vibratory instead of rotation .
Advantages ( over ball mill ) • Grinding is faster . • For most material ,closer size range is produced . • Power requirement is low . • Used for medium & small scale application
HAMMER MILL • IT can be either horizontal or vertical shaft type , widely used . Milling obtained by changing hammer speeds ,&/or screen sizes & feed rates . • Principle : impact between rapidly moving hammers mounted on a rotor & powder . Equipped with specially deflector around the mill inner periphery that deflecting them back into the path of the hammer .
Screen over milling chamber serve to retain large particles for further size reduction ,only certain size pass out into collector . • Hammers may take several shapes & free swinging . • ADV.: 1- Ease of setup, teardown,& clean. 2- Min. scale-up problem. 3- Ease of installation . 4- Wide range . 5- Small space . DISADV. : 1- potential clogging of screen. 2- Heat buildup degradation . 3- Mill & screen wear with abrasive material.
CUTTING MILL • USES : 1- Dispersion of powder mixes . 2- Milling wet & dry granulation . 3- Size reduction of tablet batches . It akin to hammer mill , because cutters are usually on the trailing edge of the bar hammers , hammers can replaced with cutters using the same shaft & milling chamber, shearing action .
THE CONICAL SCREEN MILL • Very effective for dry & wet milling of soft to medium-hard material . • The impeller screen clearance is maintained such that minimal heat is generated & optimum size reduction efficiency is obtained . Variable include screen sizes , impeller designs , & speed
COLLOID MILL • High speed rotor ( 3000 – 20000 rpm ) & stator with conical milling surface bet. Which adjusted 0.002 to 0.03 inches. Material must be premilled to prevent damage of the mill .Rotor & stator may be smooth or rough . It may be jacketed to be cooled & may be sterilized for handling sterile product .
OSCILLATING GRANULATOR • USED : 1- Size reduction of wet & dry granulation .2- reducing tab & compaction that must be recompressed . • SR is primarily by shear with some attrition • Its speed is constant , & the screens are changeable range from 4 to 20 mesh , narrow size range & minim. Amount of fines obtained during SR of a DRY G. , & very uniform for WET G which promotes uniform dry .
DISADV.: 1- Low throughput rat . 2- CONT of product by metal particles .3- SR of large particles or granules must be done stepwise .
GRANULATION CRACKER • Very effective in reducing size of compaction . • Compactions may originate from a compactor , a slugging machine , or compressed tab . • It is comprised of several sets of horizontal positioned , parallel rolls . The top set of rolls have the largest mating corrugation on each roll The space bet. The rolls can be set to accommodate the largest slug or tab size .
EXTRUDER • It is used for continuous wet granulation . The resulting mass is forced out of a series of small orifices . This yields a spaghetti-shaped mass that is broken up & may be dried on trays . # HAND SCREENS : used in tab making for screen analysis of powder raw materials, on small scale & mixing small amount of powder . Made of stainless steel & consist of woven wire cloth stretched in a circular or rectangular frame
ROLLER MILL • It consist of tow cylindrical rolls of stone or metal mounted horizontally & rotate on their longitudinal axis . One is driven directly & the second runs free . The gap between the 2 rolls is adjusted to control the degree of size reduction . • Three roller mill is used for semisolid product exp. Ointment .
POWDER CHARACTERIZATION • Parameters of powder :density , porosity, SA ,shape, PS , & distribution . A- SAMPLING :sampling small lots of material is uncomplicated because sampled coned & quartered or riffled , coning & quartering is repeated at least 4 times ,or returned half .
RIFFLER OR SPLITTER : Bulk is passed more then one time . • GRAIN THIEF :for large batch sizes of powder or granules : 1- inner & outer tube with matching openings ,along its length , rotating together ,so that inner tube are covered . 2- closed shaft is inserted vertically to the bottom ,& inner tube is rotated to open thief sampling chamber .powder fills chamber & inner tube rotate to close chamber & the thief is withdrawn from drum ,0RSCOOP.
NO. OF POSSIBILITES • 1- Segregation in drum, free flowing particles up & dense particles down. • 2- Thief carries parts of upper content to the middle & lower content . • 3- Smaller particles became airborne on emptying thief ,thus dust make analysis is biased , so thief must be of small diameter to take sample from different location .
B- DENISTY & PORISTY : • Density : weight to volume ratio . • True or Absolute D : weight to volume ratio of only SOLID PORTION of powder particle . • BULK DENSITY : ratio of weight of powder to volume it occupies . • BD = Volume Of Solid Portion (TD) + Internal porosity + Void Between particles . • Particular packing report BD as particular PK.CNDITION. • PACKED BD : dropping graduated cylinder containing 50GM sample 3 times at 1SEC intervals dist. 190 cm .
BD important in handling , shipping , storage & sizing hopper & receivers for milling & blending equipment . • POROSITY :measure void space within powder & calculated by manipulating true & bulk densities .Porosity = subtracting reciprocal of true & bulk density .