1. L D College of engineering Branch : Chemical Subject : Machenical Operation

2. Topic : Smooth Roll Crusher Prepared by:- Jignesh Ravliya(130280105049) Ankit Shah(130280105050) Neel Shah(130280105051) Shail Shah(130280105052) Anil Sindhav(130280105053)

3. Principle of the Roll crusher Size reduction is achieved by compression.

4. The feed of materials: Raw materials, secondary raw materials and by-products such as coke duff, coal, rock, fireclay, fertilizer, salt, glass and similar products Smooth Roll Crusher

5. The mode of operation of smooth Roll crusher The crushing rolls are driven individually and directly by means of electro-motors or with coupling and gears, counterrotating via V-belts. The material is fed into the machine by means of conveyors while it is spread over the whole width of the roll. The roll diameter grants an optimum angle of entry. The careful adjusting of the roller speed towards the falling speed of the feeding material guarantees a gentle grinding process with a minimum of wear and tear.

6. Figure of Smooth Roll Crusher

7. Construction Smooth-roll crusher consist of two heavy metal of the same diameter placed side by side each other in the horizontal position The rolls are rotated towards each other at the same speed. One of the shafts moves in fixed bearing while other moves in movable bearings. The clearance between the rolls can be adjusted accordingly to the size of feed and the required size of the product.

8. One of the roll driven directly, the other by friction by the solids. The roll have relatively narrow faces and are large in diameter, therefore they can nip moderately large lump. The material fed to the machine is reduced in size by compression and discharged from the bottom. The machine is operated by spring loading(i.e. by mounting the bearing of one of the roll shafts against coiled springs) against damage due to tramp the very hard material.

9. Working of Smooth Roll Crusher The material to be crushed is fed from the top. As the roll rotate, the material gets caught between them and gets reduced in size by compression and discharge from the bottom.

10. Design of Crushing Rolls  Selection of Crushing Roll It is necessary to know the size of feed and Product.

11. In figure spherical particle B of a material is just being caught between the rolls. The line AB passes through the centre of the left hand roll, through the centre of particles, and through point C where there particle is in contact within the roll. Angle between the line AB and horizontal is α. The line OD is tangent to the roll at point C. OD made the same angle α with the vertical, neglecting gravity to forces are acting at point C 1. Frictional Forces T(T cos α) 2. Radial Forces N ( N sin α )

12. Figure 1

13. The coefficient of friction μ = T/N If the particle is to be drawn between the roll and crush then, T cos α >= N sin α T = μN μ N cos α >= N sin α μ >= tan α μ is vary from material to material but the value of angel is taken 16°. Angle DOE, which is twice the α is called the angle of nip.

14. Angle of nip : angle formed by the tangent to the roll faces at a point of contact with a particle to be crushed. R = Radius of feed particle r = Radius of roll 2d = Distance between the rolls. In figure 2 triangle ABG, the angle BAG is α, AG is r+d AB is r+R

15. Figure 2

16. cos α = AG/AB = r+d / r+R If α = 16°, then cos α = 0.961 so that, 0.961 = r+d / r+R Uses Crushing of oil seed and gun powder industry.

17. Capacity of Smooth Roll Crusher  The capacity of a roll crusher will vary with: The kind of stone The size of feed The size of the finished product The width of rolls The speed at which the rolls rotate The extent to which the stone is fed uniformly into crusher.

18. Advantages of Smooth Roll Crusher High and constant capacity Low susceptibility to breakdowns Long lifetime Easy replacement of wear and spare parts Wide range of application With a minimum of fine grains Gentle crushing

19. Disadvantages of Smooth Roll Crusher It is limited by the roller rotation rate So its production capacity is relatively small It is more suitable for medium and small beneficiation plants.

20. The scope of application Capacity: up to 200 m3/h Feeding size: up to approx. 80 mm Final grain size: up to approx. < 1 mm depending on the product and feed materialand its size The speed of the rolls varies from 50 to 300 rev/min. Crushing rolls are secondary crusher accepting feed 12 to 75 mm in size and yielding products-12 mm to about 20 mesh. These machines are characterized by production of few fines and by a smaller reduction ratio of the order of 4 to 1.