Pharmaceutical Technology Lab 5 on Mixing

Pharmaceutical Technology Lab 5 1 Mixing Solid Mixing CON V EC T ION S HEA R DI F F U S ION  Rotation of the entire mixer with agitator blade ▪Modification of the tumbling blenders with the addition of a high-speed agitator mixing blade ▪Thi...

Pharmaceutical Technology Lab 5 1 Mixing Solid Mixing CON V EC T ION S HEA R DI F F U S ION  Rotation of the entire mixer with agitator blade ▪Modification of the tumbling blenders with the addition of a high-speed agitator mixing blade ▪This agitator blade gives high shear. ▪The mechanism is convection and shearing. Rotation of the entire mixer with agitator blade Advantages: 1) A wide range of shearing force may permit the intimate mixing of very fine as well as coarse powder. 2) No dead spots. Disadvantages: 1) Cleaning may be a problem. (corners)  Agitator Blades Agitator Shaft V-blender with agitator blade  -------------------- Write the mechanism and the parts of this machine ? Write the advantages and disadvantages of this machine ?  Sigma Blade Mixer The sigma blade mixer is commonly used for dough mixing because of the high shear and kneading action creating by intermeshing blades. It is used for solids and semi-solids blending. The mixer is top loading and is emptied by tilting the entire shell. Mechanism: Shearing Sigma Blade Mixer Sigma Blade Mixer Sigma Blade Mixer  ----------------------- This machine is commonly used for mixing of ---------------- because of ------------------ Planetary Mixer (Hobart’s Mixer) The mixing shaft is driven by a planetary gear, the mixer blade shaft position is rotational as well as the mixer blade itself. It is a high-shear mixer built with a variable-speed drive. The mixer shell is a mixing bowl which is removed from the mixer by either lowering it beneath the blade, or raising the blade above the bowl, or both. There are no dead spaces. Planetary Mixer (Hobart’s Mixer)  -------------------- What is the disadvantage of using this machine? Write in details the operation and the parts of this machine ? Double Planetary mixer The double planetary mixer includes two blades that rotate at their own axis, clockwise and in opposite directions to their common axis. The mechanism of mixing is shear. More efficient than the planetary mixer. 19 two types of blades used in double planetary mixers. Two types of blades used in double planetary mixers. Advantage of HV blades over Rectangular blades: Push materials forward and downward that prevents patch content of climbing up the blades Easily cleaned from heavy and viscous formulations The Impact wheel mixer (Entoleter) The powders are introduced from the inlet, hitted by the revolving wheel. Revolving Wheel Product ---------------------------------- Explain the operation and the mechanism of this machine ?  High speed granulator These are stationary mixers with a large mixer–scraper blade that 1. Mixes the ingredients 2. Eliminates dead spots and 3. presents the mixer contents to a high-speed chopper blade which intimately mixes the ingredients. The chopper is located at the side of the mixing bowl or chamber. The advantages are 1. rapid, intimate solids-solids mixing or liquid solids mixing. 2. It can be used for granulation in case of adding cohesive materials. High speed granulator High speed granulator ------------------------- Mention the advantages and disadvantages of using this machine ? General disadvantages for mixers: 1. They may include product contamination from the mixer shell. 2. Batch size limitation. Column A Column B 1) a. 2) b. 3) More efficient than the planetary mixer c. Works by convection and shearing. 4) Powders introduced from the inlet and d. used for dough mixing because of the hitted by the revolving wheel. high shear and kneading action 5) e. It can be used for granulation in case of adding binders. Liquid Mixing  Paddle Mixers Paddle mixers use an agitator consisting, usually, of flat blades attached to a vertical shaft and rotating at a low speed of the order of 100 rev./min. For liquids : A. Low viscosity: >>> High speed ◦ simple flat paddles (single paddle) B. More viscous liquids: >>> Low speed ◦ paddles generally have a number of blades (Multiple or gate paddle), ◦ often shaped to fit closely to the surface of the vessel, avoiding “dead spots" and deposited solids. Paddle Mixers o Low speeds of rotation do not normally demand baffles, but at higher speeds it is necessary to use them to avoid swirling and vortexing. o As the width of the agitator increases the mixing efficiency increases because it improves the circulation in the vessel. o An alternative design for the more viscous range of liquids is the planetary motion mixer, which has a smaller paddle that rotates on its own axis, but travels, also, in a circular path round the mixing vessel. Thus, the term "planetary" is analogous to the movement of planet round the sun while rotating on its own axis. Paddle Mixers Paddle Mixers A variety of agitator shapes are available according to the character and viscosity of the product. A. The single-paddle: is suitable for mixing miscible liquids of low viscosity. B. The gate agitator: is useful in mixing viscous liquids and thin pastes. C. The multiple-blade paddle: for mixing viscous liquids and suppresses vortex formation with thin liquids. D. The anchor paddle: is suitable for mixing viscous liquids, it is useful in preventing deposits on surfaces, since it is made to fit to the shape of the vessel with only a small clearance. ------------------------ Mention the use of each type in details ? Column A Column B 1) a. 2) b. 3) suitable for mixing miscible liquids of low c. mixing viscous liquids, since it is made to viscosity. fit to the shape of the vessel with only a small clearance. 4) viscous liquids and suppresses vortex d. alternative design for the more viscous formation with thin liquids. range of liquids which has a smaller paddle that rotates on its own axis, but travels in a circular path around the mixing vessel 5) planetary motion mixer e. mixing viscous liquids and thin pastes Each group should finalize groups, theme, and work on your project Thank you