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Lect 8-Seperation Process 1 Dr. ALI AL-SHATRI .pdf

Abu Hussein
Abu Hussein

Unit operation lecture

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Mixing equipment The efficiency and homogeneity of the mixing process significantly impact the quality of the final product. Several types of equipment are employed in industrial to achieve optimal mixing of solid particles. Here's an overview of some commonly used industrial solid particles mixing equipment: For paste and heavy material Pony mixer Beater mixer Kneader mixer For granular solids Tumbling mixer Ribbon mixer Vertical screw mixer Paddle mixer
Mixers for paste and heavy material Change can mixers: Theses devices blend viscous liquids or light pastes, as in food processing or paint manufactures. A small removable can 5-100 gal size holds the material to be mixed.
Mixers for free-flowing solids (granular solids) (a) (b) Ribbon mixer: it has its unique twisted blades shaped like the inner blade bar, are set up within static shell by rotating blades. - Main mechanism is convective mixing - Accompanied with diffuse and shear mixing Tumbling mixer: Closed vessel rotating about its axis (cube, cone, or V shape). - Main mechanism is diffuse mixing - Problem segregation in free-flowing powders (to minimize use baffles)
Mixers for free-flowing solids (granular solids) Vertical screw mixer Paddle mixer Paddle mixer: it I known as paddle blender, it has efficient and gentle mixing action making it suitable for fragile or heat-sensitive material.. - Main mechanism is convective mixing with rotational motion. Vertical screw mixer: it has its uniform mixing of materials through the rotation and pushing screw. It has difficulty in handling sticky or cohesive materials. - Main mechanism is convective mixing - Accompanied with diffuse and shear mixing
SIZE REDUCTION What is the meaning of size reduction? Size refers to physical dimension of an object. Reduction refers to decrement or the process of decreasing the size.
Simple definition of size reduction
Objectives of SIZE REDUCTION
Lect 8-Seperation Process 1 Dr. ALI AL-SHATRI .pdf
Mechanism of SIZE REDUCTION
Type of IMPACT Gravity impact In gravity impact ,the free falling material is momentarily stopped by the stationary object. Example coal dropped onto a hard steel surface. Dynamic impact Most often used when it is necessary to separate two materials which have relatively different friability. Example material dropping in front of a moving hammer.
Size reduction with COMPRESSION Needed:
Energy for size reduction
Energy for size reduction It was shown that the energy (dE) required to effect a small change in the size of unit mass of material (dL) is a simple power function of size. Where; P is a constant C is a coefficient Three empirical laws have been proposed to solve the above
Energy for size reduction 1. Rittingers law (1867): In this law, P is put equal to (-2) Energy for size reduction Put Where is Rittingers constant ( ) is the crushing strength of the material ( ) The interpretation of this law is that the energy required for size reduction is directly proportional to the increase in surface. / / = 告
Energy for size reduction 2. Kicks law (1885): In this law, P is put equal to (-1) Put Where is Kicks constant ( ) is the crushing strength of the material ( ) The energy required to crush a given amount is directly related to the reduction ratio 叶 叶 . / / = 告 = 告 叶 叶 C
Energy for size reduction Neither of these two laws give an accurate calculation of the energy requirements. Rittingers law is applicable mainly to that part of the process where the increase in surface per unit mass of material is large, i.e. used for fine grinding. Kicks law, however, is more accurate than Rittingers law for coarse crushing where the amount of surface produced is considerably less.
Energy for size reduction 3. Bonds law (1952): Bond has suggested a law intermediate between Rittingers and Kicks laws, by putting P = 3/2. After integration we get: Where : the work index which represents the amount of energy required to reduce unit mass of material from an particle size 叶 to a size 叶 of 100 亮m. The size of material is taken as the size of the square hole through which 80 % of the material will pass.
Lect 8-Seperation Process 1 Dr. ALI AL-SHATRI .pdf
Applications
What is the power required to crush 100 ton/h of limestone if 80 percent of the feed passes a 2-in screen and 80 percent of the product a 1/8-in screen? Solution: Form pervious Table, the work index for limestone is 12.74 (KW.h/ton) The power required to crush is Example: = 艶. . 艶 = 169.57 KW 叶 = . = . 叶 = . . = . 動 = / = 叶 叶 =
Problem 3

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Lect 8-Seperation Process 1 Dr. ALI AL-SHATRI .pdf

  • 1. Mixing equipment The efficiency and homogeneity of the mixing process significantly impact the quality of the final product. Several types of equipment are employed in industrial to achieve optimal mixing of solid particles. Here's an overview of some commonly used industrial solid particles mixing equipment: For paste and heavy material Pony mixer Beater mixer Kneader mixer For granular solids Tumbling mixer Ribbon mixer Vertical screw mixer Paddle mixer
  • 2. Mixers for paste and heavy material Change can mixers: Theses devices blend viscous liquids or light pastes, as in food processing or paint manufactures. A small removable can 5-100 gal size holds the material to be mixed.
  • 3. Mixers for free-flowing solids (granular solids) (a) (b) Ribbon mixer: it has its unique twisted blades shaped like the inner blade bar, are set up within static shell by rotating blades. - Main mechanism is convective mixing - Accompanied with diffuse and shear mixing Tumbling mixer: Closed vessel rotating about its axis (cube, cone, or V shape). - Main mechanism is diffuse mixing - Problem segregation in free-flowing powders (to minimize use baffles)
  • 4. Mixers for free-flowing solids (granular solids) Vertical screw mixer Paddle mixer Paddle mixer: it I known as paddle blender, it has efficient and gentle mixing action making it suitable for fragile or heat-sensitive material.. - Main mechanism is convective mixing with rotational motion. Vertical screw mixer: it has its uniform mixing of materials through the rotation and pushing screw. It has difficulty in handling sticky or cohesive materials. - Main mechanism is convective mixing - Accompanied with diffuse and shear mixing
  • 5. SIZE REDUCTION What is the meaning of size reduction? Size refers to physical dimension of an object. Reduction refers to decrement or the process of decreasing the size.
  • 6. Simple definition of size reduction
  • 7. Objectives of SIZE REDUCTION
  • 9. Mechanism of SIZE REDUCTION
  • 10. Type of IMPACT Gravity impact In gravity impact ,the free falling material is momentarily stopped by the stationary object. Example coal dropped onto a hard steel surface. Dynamic impact Most often used when it is necessary to separate two materials which have relatively different friability. Example material dropping in front of a moving hammer.
  • 11. Size reduction with COMPRESSION Needed:
  • 12. Energy for size reduction
  • 13. Energy for size reduction It was shown that the energy (dE) required to effect a small change in the size of unit mass of material (dL) is a simple power function of size. Where; P is a constant C is a coefficient Three empirical laws have been proposed to solve the above
  • 14. Energy for size reduction 1. Rittingers law (1867): In this law, P is put equal to (-2) Energy for size reduction Put Where is Rittingers constant ( ) is the crushing strength of the material ( ) The interpretation of this law is that the energy required for size reduction is directly proportional to the increase in surface. / / = 告
  • 15. Energy for size reduction 2. Kicks law (1885): In this law, P is put equal to (-1) Put Where is Kicks constant ( ) is the crushing strength of the material ( ) The energy required to crush a given amount is directly related to the reduction ratio 叶 叶 . / / = 告 = 告 叶 叶 C
  • 16. Energy for size reduction Neither of these two laws give an accurate calculation of the energy requirements. Rittingers law is applicable mainly to that part of the process where the increase in surface per unit mass of material is large, i.e. used for fine grinding. Kicks law, however, is more accurate than Rittingers law for coarse crushing where the amount of surface produced is considerably less.
  • 17. Energy for size reduction 3. Bonds law (1952): Bond has suggested a law intermediate between Rittingers and Kicks laws, by putting P = 3/2. After integration we get: Where : the work index which represents the amount of energy required to reduce unit mass of material from an particle size 叶 to a size 叶 of 100 亮m. The size of material is taken as the size of the square hole through which 80 % of the material will pass.
  • 20. What is the power required to crush 100 ton/h of limestone if 80 percent of the feed passes a 2-in screen and 80 percent of the product a 1/8-in screen? Solution: Form pervious Table, the work index for limestone is 12.74 (KW.h/ton) The power required to crush is Example: = 艶. . 艶 = 169.57 KW 叶 = . = . 叶 = . . = . 動 = / = 叶 叶 =