1.
What are the different types of diameter
that can be calculated for an irregular shape particle with their applicability?
b)
Particles of average feed size 5 mm
are crushed to an average product size of 1 mm at the rate of 10 tons per
hour. At this rate the crusher consumes 25 kW of power of which 2 kW is
required to run the mill empty. What would be the power consumption if 15 tons
per hour of this product is further crushed to 0.2 mm size in the same mill?
Assume that Rittinger’s Law is applicable.
2.
a)
What does the sieve BSS 5 mean and find the width of aperture
(sieve opening) of BSS 5 if the wire diameter is 1.727 mm?
b)
Define the efficiency of a screen and derive
the formula used to find it.
3.
Apply the force balance on a particle
settling against water flowing up the column. Explain the working of an
elutriator which is used to separate a mixture into 3 or more fractions.
4. A mixture of quartz and galena of a size
range 0.15 mm to 0.65 mm is to be separated into two pure fractions using a
classifier under laminar flow condition. What density of the fluid would you
suggest that will give the separation? The density of galena is 7500 kg/m3
and the density of quartz is 2650 kg/m3
5. A finely ground mixture of galena and limestone in the proportion of 1 to 4 by mass is subjected to elutriation by an upward-flowing stream of water flowing at a velocity of 6 mm/s. Assuming that the size distribution for each material is the same, and is shown in the following table, estimate the percentage of galena in the material carried away and in the material left behind. The viscosity of water is 1cP and Stokes’ equation can be used. The densities of galena and limestone are 7500 and 2700 kg/m3, respectively.
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