5HB - April 1999
Part A (20 x 2 = 40 Marks)
- What is a screen?
- Give the various methods for finding the size distribution of a mixture of
- Define ‘Volumetric mean diameter’ of a particle
- Increasing the capacity of screen _________ (decreases/increases) the
- What is the main difference between tube mill and ball mill?
- Define ‘Bonds law’ of crushing
- Give the critical speed of a ball mill
- Explain crushing efficiency
- What are flotation agents?
- Define ‘Hindered settling’
- Explain the term ‘classification’
- Differentiate between a thickener and a clarifier
- Define filtration
- What is specific cake resistance?
- Differentiate between incompressible cake and compressible cake
- Mention some commonly used filter aids
- Give the purposes of agitation
- Define power number
- Name the agitator which is suitable for mixing low viscosity fluids
- Write the physical significance of Froude’s number in agitation of fluids
Part B (5 x 12 = 60 Marks)
- (a) Define sphericity for spherical and non-spherical particles.
Critically analyze the differential and cumulative methods of analysis to
determine the average particle size
(b) (i) What are the various types of industrial screens and how they are
(ii) Explain the principle of magnetic separation methods
- (a) State and derive the expression for the three basic laws of size
reduction. What is the size range of feed for their applicability?
(b) (i) Draw a neat sketch of a smooth roll crusher and explain its
(ii) Derive an expression between particle size, roll dimensions and angle
of nip in smooth roll crusher
- (a) (i) Explain the term ‘Terminal Settling Velocity’ of a particle
(ii) Derive the equation for the terminal settling velocity of a particle
in Stoke’s law and Newton’s law range
(b) With a neat sketch, describe the working of a DORR THICKENER
- (a) (i) With a neat sketch explain the working of a plate and frame filter
(ii) Discuss the basic principles in centrifugal filtration
(b) Derive an expression for thickness of cake and volume of filtrate for
- At constant rate
- At constant pressure filtration
- (a) Discuss the following:
- Approximate dimensions of a turbine impeller and baffles used in a batch
reactor based on reactor diameter
- Power required for impeller mixers
Or(b) (i) Classify mixers for dry powders and state their
(ii) What are the preventive measures for reducing swirling in agitated
(iii) What are the types of mixtures suitable for pastes and plastic
masses? Explain any one of them with a neat sketch.