Evolution of crushing
The main objective of crushing theory is to express the relationship between the energy consumed and the amount of the size reduction which resulted through this energy consumption. According to Lee (2009) there are three classical crushing theories in all which assumes rocks, (ore is also classified under rocks) to be brittle. Rittinger was the first to suggest the theory in which he proposed in 1867, he suggested that the surface area produced by crushing is directly proportional to the energy consumed. Rittinger formulated an equation in which energy consumed is in the form of Rittinger. Below is the Energy Rittinger equation
ERittinger=CRittinger(1/P_80 -1/f_80 )………………………………………………………………..Equation 2.1
Where Rittinger E is the energy input, Rittinger C is a material constant, 80 p is the size which 80 % of the product passes, and 80 f is the size which 80 % of the feed passes. Nevertheless, since an unlimited number of different size distributions pass the single points of 80 p and 80 f , neither of the parameters can adequately characterize a size distribution
The second classical crushing theory was introduced by Kick in 1883. Kick declared that the energy required for breakage is proportional to the reduction in volume of the broken particles. Below is the equation which was formulated by kick and it is known as the kick equation.
EKick=CKick ln(f_80/P_80 )…………………………………………………………………………Equation 2.2
Where Kick E is the energy input and Kick C is a material constant. Regrettably, similar to Rittinger’s law, Kick’s law lacks accuracy in describing the shape of a size distribution curve as only a distinct or single point is used
Bond in 1952 proposed the third and final classical relationship of crushing. ...
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... of the longitudinal stress wave
VPP= peak particle velocity which is also equal to impact velocity Vi
The kinematics of hammer rotation
Gupta (1996) argued that the performance of crushers have some other parameters they depend upon mainly the fineness of the crushing and the life of the beaters. It is estimated that the life of the beaters depends on the kind of operation it is applied, depth of penetration of the crushed material into the beaters and the kinetics motion of the beaters. He also suggested that the life of the beaters is approximately 50 to 60 hours but this was not clear in terms of the material used to manufacture the beaters. Gupta (ibid) argued that the crushing effect does not depend on the kinetic equation of the beaters, but depends on the interchange of the beaters and particle or loss of energy due to impact. He argued that there is need
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During impact most of the impact energy in the test specimen is absorbed as plastic deformation when the test specimen yields. Temperature and strain rate effect the yield behaviour and ductility of the material and hence affect the impact energy. Materials that behave this way usually have body-centred cube crystal structures and where lowering the temperature reduces the materials ductility.
Serway, Raymond A, and Robert J Beichner. Physics: For Scientists and Engineers. United States of
It states that, the amount by which a material body is deformed is linearly related to the force causing the deformation i.e. stress. Or more clearly stress is directly proportional to the deformation. Those solid obey Hook’s l...
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