Size Reduction Problems

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1. The average minimum or representative dimension of the material retained on a sieve in the set used for a fineness modulus determination is approximately 1.4 times the sieve opening. Why?

2. Derive equation 6.1.

3. Prove that the fineness modulus is a geometric mean of a minimum dimension weighted on the basis of quantities, that is,

    where w is the weight or per cent of material of minimum dimension D.

4. Determine the fineness modulus, uniformity index, and average particle size for the following sieve analysis:

5. Assume the particles in problem 4 to be spherical and the result of a reduction from a uniform product 3/8 in. in diameter. Prepare and complete a table with the following column headings: (1) sieve mesh, (2) sieve-opening width, (3) relative number of particles retained by each sieve, using 2 on the 3/8-in. sieve as the base, (4) total relative area represented on each sieve. Discuss the data from the standpoint of ( 1) power requirements, (2) rate of oxidation of air sensitive materials, (3) importance of a minimum amount of fine material.

6. Determine the constants of equation 6.7 for shelled corn and barley ground by hammer mill from the curves of Fig. 6.10. Express an opinion as to the deviation from Kick's and Rittinger's laws.

7. If all the grinding power, Fig. 6.12, at 3400 rpm is accumulated as heat in the ground material, what is the temperature rise of the material? Assume the specific heat to be 0.30.

8. Plot the sieve analysis data of paragraph 6.2 in the two ways discussed in paragraph 6.4. Discuss the possibility of representing each curve by an equation.

Buy the solutions: PM @ Engineering Daily 

Buy the solutions: PM @ Engineering Daily 

Buy the solutions: PM @ Engineering Daily