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.Management Sciences
Category: Mechanical Operations
Rod mills employed for grinding_________________?
A. Employ a steel shell having L/D ratio of 1.5 to 3.0
B. Is useful for handling sticky materials
C. Employ steel rods of 2-12 cms diameter extending over full length of the mill
D. All A , B & C
Which of the following oxides is not present in hematite iron ore ?
A. Titanium oxide
B. Calcium oxide
C. Cobalt oxide
D. Manganese oxide
The main size reduction operation in ultrafine grinders is_____________?
A. Cutting
B. Attrition
C. Compression
D. Impact
Which of the following is not a non-metalliferous mineral ?
A. Calcite
B. Fluorspar
C. Quartz
D. Cassiterite
A suspension of glass beads in ethylene glycol has a hindered settling velocity of 1.7 mm/s, while the terminal settling velocity of a single glass bead in ethylene glycol is 17 mm/s. If the Richardson-Zaki hindered settling index is 4.5, the volume fraction of solids in the suspension is_____________?
A. 0.1
B. 0.4
C. 0.6
D. None of these
A compressible cake has the_________________?
A. Maximum porosity at the upstream side
B. Maximum porosity at the filter medium
C. Same porosity throughout the cake thickness
D. None of these
Which of the following is used for primary crushing of very hard lumpy materials ?
A. Toothed roll crusher
B. Gyratory crusher
C. Ball mill
D. Tube mill
Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is_______________?
A. Added to the feed slurry
B. Pre-coated on the filter medium prior to filtration
C. Separated from the cake by dissolving solids or by burning it off
D. All A, B. & C.
Moisture can be removed from lubricating oil using_________________?
A. Tubular centrifuge
B. Clarifier
C. Sparkler filter
D. Vacuum leaf filter
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