SIZE REDUCTION EQUIPMENTS- mechanical operations

Size Reduction Equipments

1. SIZE REDUCTION M. AKASH 810020239003

2. Agenda Introduction Objectives Mechanisms Affecting Factors Mode of Operation Governing Laws Types of Size Reduction Equipments

3. DEFINITION SIZE refers to the physical dimension of an object. REDUCTION refers to the decrement or the process of decreasing the size. SIZE REDUCTION refers to the process of converting the object from one physical dimension of higher order to another dimension of smaller order. Comminution is the generic term for size reduction.

4. OBJECTIVES Increases the surface area. fine particles size is important because it reduce the rate of sedimentation. Smaller particle sizes may require less energy for mixing, milling, or extrusion. To improve the handling characteristics, to mixed solid particle more ultimately.

5. MECHANISM Impact - particle break by a single rigid force.
Compression - particle disintegration by two rigid forces.
Cutting – the material is cut by sharp blades.
Attrition - arising from particles scraping between two surfaces.

6. MODE OF OPERATION OPEN CIRCUIT GRINDING: Feed is introduced to the size reduction equipment. After size reduction, products are directly sent to another unit without any return of oversize particles back to size reduction equipment. CLOSED CIRCUIT GRINDING: Feed is introduced to the size reduction equipment. After size reduction, products are sent to classifying equipment that separates oversize particles from desired size particles, and oversize particles are sent back to crushing equipment for further size reduction.

7. GOVERNING LAWS

8. AFFECTING FACTORS Feed Material Properties: Hardness, brittleness, moisture content, and friability of the material being processed.
Equipment Design and Operating Parameters: Type of equipment, speed, feed rate, and size of the feed material.
Desired Particle Size Distribution: Target particle size range and distribution for the intended application.

9. TYPES OF SIZE REDUCTION Crushers (coarse and fine) Jaw crushers Gyratory crushers Cone crusher Crushing rolls B. Intermediate crusher Roller mill Granulator Hammer mills (Coarse mine material into lumps of 250 to 150 mm. Again, these lumps are broken into particles of 50-5 mm in size) Feed = 50-5 mm Product = 5-0.1 mm

10. C. Fine crushers/Grinders Attrition mills Tumbling mills Rod mills Ball mills D. Ultrafine grinders Fluid-energy or jet mill Fine impact mill E. Cutting machines Knife cutters Scissors Feed = 5-2 mm Product ≈ 200 mesh Feed < 6 mm Product: 1-50 µm 2 to 10 mm definite size

11. JAW CRUSHER A rock-crushing device comprising one fixed inclined jaw and one movable inclined jaw. It is used to reduce rock to specific sizes. PRINCIPLE : COMPRESSION TYPES OF JAW CRUSHER Blake Jaw Crusher Dodge Jaw Crusher Universal Jaw Crusher

12. BLAKE JAW CRUSHER Based on human jaw, one fixed plate, one moving. One jaw, the fixed, is nearly vertical and does not move. Other jaw, the swinging jaw, reciprocates in a horizontal plane. It makes an angle of 20° to 30 with the fixed jaw. As the material moves down the crushing action increases.

13. DODGE JAW CRUSHER In Dodge jaw crusher, the movable jaw is pivoted at the bottom and the top end executes the reciprocating motion. The large opening at the top enables it to take very large feed and to effect a large size reduction. Since the width of discharge opening is practically constant, a more uniform and closely sized product can be obtained. The constant opening at the discharge end gives the crusher an annoying tendency to clog.

14. UNIVERSAL JAW CRUSHER The universal jaw crusher combines the principles of both Black and Dodge jaw crushers. Here the pivot is slightly above the bottom end of the movable jaw and therefore it provides two strokes per revolution.

15. PLATES / FACES The jaw faces are of several patterns for gripping the material and for concentrating the pressure on smaller areas. Product size is adjusted by adjusting the gap size. The jaws open and close 250-400 times per minute

16. USES: They are suitable for crushing hard and abrasive materials Used as the first stage in the crushing process ADVANTAGES: High Efficiency Versatility, Simple Structure & Adjustable Discharge Size DISADVANTAGES: Limited Crushing Capacity Noise and Vibration Uneven Particle Size Distribution

17. GYRATORY CRUSHER PRINCIPLE: The principle of Gyratory crushers it the of compression. It consists of two vertical conical: shells, the outer shell having its apex. Downward direction while the inner cone is positioned with its apex upward. The inner shell acts as crushing head, which is in the form of a truncated cone and is mounted on a oscillating shaft.

18. ADVANTAGES: High Capacity Uniform Particle Size Distribution Less Maintenance Better Performance in Hard Rock Applications DISADVANTAGES: Space Requirements Limited Adjustability Complex Maintenance Higher Initial Cost

19. CONE CRUSHER A cone crusher is generally used as a secondary crusher in a crushing circuit. Pre- crushed product is fed through the top of the cone crusher and flows over the mantle. The vertical cone crusher drive shaft rotates the mantle eccentrically below the concave, squeezing the product and crushing it between the mantle and concave.

20. BALL MILL

21. GRINDING MEDIA Ceramic grinding media Hardened lead grinding media Standard chrome plated steel grinding media

22. ADVANTAGES: It can produce very fine powder.
Ball mill is used for both wet and dry grinding processes.
Toxic substances can be ground, as the cylinder is closed system.
Installation, operation and labour costs are low. DISADVANTAGES: The ball mill is a very noisy machine.
Ball mill is a slow process.
Soft, fibrous material cannot be milled by ball mill.

23. BALL MILL

24. FLUID ENERGY MILL PRINCIPLE: It operates on the principle of impact and attrition. WORKING: The fluid energy mill is consists of a loop of pipe. A fluid, usually air, is injected at high pressure through nozzles at the bottom of the loop, giving rise to a high velocity circulation in a very turbulent condition. Solids are introduced into the stream and, as a result of the high degree of turbulence, impacts and attritional forces occur between the particles.
A classifier is incorporated in the system, so that particles are retained until sufficiently fine.
The feed to the mill needs to be pre-treated to reduce the particle size to 100 mesh, enabling the process to yield a product as small as 5 µm or less.

25. ADVANTAGE: No wear and tear of mill.
Suitable for heat sensitive material.
It used for obtain particular in μ size. DISADVANTAGES: Pre milling of material is required.
Controlled supply of feed is required.

26. HAMMER MILL PRINCIPLE: It operates on the principle of impact between rapidly moving hammers mounted on rotor and the stationary powder material. CONSTRUCTION AND WORKING: A hammer mill is essentially a steel drum containing a vertical or horizontal rotating shaft or drum on which hammers are mounted.
The hammers swings on the ends or fixed to the central rotor.
The rotor is rotates at a high speed inside the drum while material is fed into a feed hopper.

27. The material is put into the hopper which is connected with the drum.
The material is powdered to the desired size due to fast rotation of hammers and is
collected under the screen.
This are mainly operated at 1000 to 2500 rpm for the reduction of the large sized
particles. High speed rotor uses 10000 rpm speed.

28. USES: Brittle material is best fractured by impact from blunt hammers.
Fibrous material is best reduced by cutting edges ADVANTAGES: It is rapid in action, and is capable of grinding many different types of materials.
They are easy to install and operate, the operation is continuous.
There is little contamination of the product with metal abraded from the mill as surface move against each other.
The particle size of the material to be reduced can be easily controlled by changing the speed of the rotor, hammer type, shape and size of the screen. DISADVANTAGES: Heat build up during milling is more, therefore, product degradation is possible.
Hammer mills cannot be employed to mill sticky, fibrous and hard materials.
The screens may get clogged.

29. ROTARY CUTTER MILL PRINCIPLE: In Rotary cutter mill, feed material is size reduced by continuous cutting and shearing by the help of sharp knives .

30. WORKING: The rotor disc rotates at a speed of 200-900 rotations per minute. The feed is loaded and it comes down due to gravity. Due to the rotations made by the rotator disc, the feed material comes in close contact between the stationary and rotating knives which results in size reduction. Small particles pass through the screen while the coarser particles are held again by the rotating knives and the same procedure is repeated till the desired size is obtained. The shape and size of the particles depends on the size of rotor, gap between rotating and stationary knives and the opening of sieve.

31. Advantages of Cutter Mill: 1. It is the best option of size reduction when impaction, attrition, or compaction type milling is not effective especially for tough, fibrous, or resilient materials. 2. It is easy to install, operate, and maintain. 3. The equipment is not expensive Disadvantages of Cutter Mill: 1. Cutter mill is not suitable for most pharmaceutical applications due to the formation of wide particle size. 2. It is not easy to clean after use.

32. REFERENCES McCabe, W.L., Smith, J.C., & Harriott , P. (2001). Unit Operations of Chemical Engineering (6th ed.). McGraw-Hill Education. Rumpf , H. (2015). Particle Technology and Engineering: An Engineer's Guide to Particles and Powders: Fundamentals and Computational Approaches. Wiley-VCH. Paul, E.L., & Atiemo -Obeng, V.A. (2005). Handbook of Industrial Mixing: Science and Practice. Wiley- Interscience . Goyanes , S., & Vickers, J. (2016). Introduction to Particle Technology. Royal Society of Chemistry. Svarovsky , L. (2000). Solid-Liquid Separation: Equipment Selection and Process Design. Elsevier.Wills , B.A., & Finch, J. (2015). Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery. Butterworth-Heinemann. Klenk , M. (2017). Powder Technology: Handling and Operations, Process Instrumentation, and Working Hazards. Wiley-VCH. Hounslow, M.J., Rhodes, M.J., & Geldart , D. (1997). Particle Technology and Engineering: An Engineer's Guide to Particles and Powders: Fundamentals and Computational Approaches. Wiley-Blackwell. Shacham , M., & Levine, R.L. (2009). Handbook of Powder Science & Technology. Springer Science & Business Media.Chattopadhyay , A., & Adhikari, G. (2016). Introduction to Particle Technology. PHI Learning Pvt. Ltd. Allen, T. (2013). Particle Size Measurement (5th ed.). CRC Press. Himmelblau , D.M., & Bischoff, K.B. (1996). Process Analysis and Simulation in Chemical Engineering. McGraw-Hill Education.

33. Fayed, M.E., & Otten, L. (1993). Handbook of Powder Science and Technology. Springer. Cunningham, J.B., & Snyder, M.H. (2002). Introduction to Chemical Engineering Processes. McGraw-Hill Education. Khurmi , R.S., & Gupta, J.K. (2005). A Textbook of Machine Design. Eurasia Publishing House.Khurmi , R.S., & Gupta, J.K. (2005). A Textbook of Machine Design. Eurasia Publishing House. Lewis, M.J. (2006). Engineering Fluid Mechanics. Oxford University Press. Chhabra, R.P., & Richardson, J.F. (2008). Non-Newtonian Flow and Applied Rheology: Engineering Applications. Butterworth-Heinemann. Mills, S. (2016). Powder Mixing: Theory and Practice. Springer. Rhodes, M.J. (2008). Introduction to Particle Technology. John Wiley & Sons. Muzzio , F.J., & Tardos , G.I. (2010). Handbook of Industrial Mixing: Science and Practice. John Wiley & Sons.

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