Q. According to Bond crushing law, the work required to form particle of size 'D' from very large feed is (where (S/V)p and (S/V)f are surface to volume ratio of the product and feed respectively).

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Q. Critical Speed (Nc) of a ball mill is given by(where R₁ and R₂ are radii of ball mill and the ball respectively).

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Q. Which of the following equations is Rittinger's crushing law ?
(where P = power required by the machine, m = feed rate, k = a constant, D̅sa & D̅sb = volume surface mean diameter of feed & product respectively.)

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Q. About 2-3 hp, power per gallon of a thin liquid provides vigrous agitation in an agitator. 'Power number' in agitation is given by

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Q. rpm of a trommel at critical speed is given by (where, D = Diameter of trommel in ft)

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Q. A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is

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Q. Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively).

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Q. Critical speed of rotation, N (in rps - rotation per second) of a trammel is equal to (where, g = acceleration due to gravity = 9.81 m/sec² and, r = radius of trammel, metre. )

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Q. The basic filtration equation is given as in the below figure, where, V is volume of the filtrate ; A is the filtration area, a is specific cake resistance, μ is viscosity of the filtrate, and C is the concentration of the solids in the feed slurry.

In a 20 minutes constant rate filtration, 5 m³ of filtrate was obtained. If this is followed by a constant pressure filtration, how much more time in minutes, it will take for another 5 m³ of filtrate to be produced ? Neglect filter medium resistance, Rm ; assume incompressible cake.

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Q. __________ mean diameter of particles is given by

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Q. The specific surface of spherical particles is given by (where D and ρ are diameter and density of particle).

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Q. Velocity of a small particle of diameter 'Dₚ' at a distance 'r' from the rotational axis of a cyclone rotating at an angular speed 'ω' is given by (the other symbols are as per standard notation)

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Q. Pick out the correct statement.

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Q. The cummulative mass fraction of particles smaller than size dⱼ for a collection of Nᵢ particles of diameter dᵢ and mass mi (i = 1, 2, 3, ...... ∞) is given by

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Q. Sphericity for a non-spherical particle is given by (where, V and S are volume and surface area respectively of one particle. and, D = equivalent diameter of particle).

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Q. What is the reduction ratio in a fine crushing operation having following feed and product sizes?

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Q. The value of 'angle of nip' is generally about

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Q. Size reduction of the __________ can be suitably done by ball mills, crushing rolls and rod mills.

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Q. Sulphuric acid mist is arrested by using a __________ scrubber.

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Q. The main size reduction operation in ultrafine grinders is

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