Mechanical Operations Short Questions & Answers - Set 12 - ObjectiveBooks

# Practice Test: Question Set - 12

1. Grindability of a material does not depend upon its
(A) Elasticity
(B) Hardness
(C) Toughness
(D) Size

2. During the washing of cake
(A) All the resistances are constant
(B) Filter medium resistance increases
(C) Filter medium resistance decreases
(D) Cake resistance decreases

3. In case of a plate and frame filter press, filtrate flow through the cake follows __________ flow.
(A) Plug
(B) Turbulent
(C) Laminar
(D) None of these

4. For laminar flow of filtrate through the cake deposited on septum, which of the following will be valid?
(A) Kozeny-Carman equation
(B) Leva's equation
(C) Blake-Plummer equation
(D) None of these

5. A __________ mixer resembles a ball mill without balls.
(A) Banbury
(B) Pug mill
(C) Tumbling
(D) Pan

6. Feed size of ≥ 25 cms can be accepted by
(A) Ball mill
(B) Rod mill
(C) Fluid energy mill
(D) Jaw crusher

7. Which of the following is a coarse crusher?
(A) Smooth roll crusher
(B) Toothed roll crusher
(C) Gyratory crusher
(D) Tube mill

8. In a grinding operation, the limiting particle size is the size of the __________ particle in the sample.
(A) Smallest
(B) Largest
(C) Either (a) or (b)
(D) Neither (a) nor (b)

9. The reduction ratio for fine grinders is
(A) 5-10
(B) 10-20
(C) 20-40
(D) As high as 100

10. The power number for a stirred tank becomes constant at high Reynolds number. In this limit, the variation of power input with impeller rotational speed (N) is proportional to
(A) N°
(B) N1
(C) N2
(D) N3

11. Filtration should be stopped in a filter press, if the
(A) Cake becomes very dense
(B) Liquor stops flowing out to the discharge
(C) Filtration pressure rises suddenly
(D) Both (b) & (c)

12. Which of the following is a continuous filter?
(A) Plate and frame filter
(B) Cartridge filter
(C) Shell and leaf filter
(D) None of these

13. Xanthates are used in the froth floatation process as a/an
(A) Conditioner
(B) Frother
(C) Collector
(D) Activator

14. In case of a revolving mill, wet grinding compared to dry grinding
(A) Requires more energy
(B) Has less capacity
(C) Complicates handling & classification of the product
(D) None of these

15. The operating speed of a ball mill should be __________ the critical speed.
(A) Less than
(B) Much more than
(C) At least equal to
(D) Slightly more than

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