S6 Flashcards
Pick out the wrong statement.
Cake resistance is independent of the pressure drop.
Which of the following oxides is not present in hematite iron ore?
Cobalt oxide
Ribbon blenders are exclusively meant for
non-flowing powder and thin pastes.
In closed circuit grinding as compared to open circuit grinding, the
operation is economical.
Pick out the correct statement.
A hopper is a small bin with a sloping bottom.
Gelatinous solid (which plug the septum) can be filtered by a __________ filter.
precoat
During the washing of cake
all the resistances are constant.
The opening of a 200 mesh screen (Taylor series) is
0.0074 cm
A gravity decanter is meant for the separation of two __________ density.
immiscible liquids of different
The most suitable filter for the removal of very small amount of precipitate from very large volumes of water is the __________ filter.
sand
Separation of solid particles based on their densities is called
sorting
Activators are those chemicals which help buoying up one mineral in preference to the other in the froth floatation process. Which of the following is an activator?
Copper sulphate
__________ are mixed using ribbon blenders.
Dry powders
During agitation of liquids, the
all (a), (b) and (c).
For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to
the new surface created.
In a size reduction crushing operation, feed size is 300 to 1500 mm while the product size is 100 to 300 mm. This is a case of the __________ crushing.
primary
As per Taggart’s formula, the capacity (kg/hr) of Jaw & Gyratory crushers (for gapes of 10 to 60 cms) is equal to (where,L= Length of feed opening, cmsS= Maximum width of discharge opening, cms)
93LS
The process by which fine solids is removed from liquids is termed as
sedimentation
Which of the following crushing laws is most accurately applicable to the fine grinding of materials?
Rittinger’s law
Shell and leaf filter as compared to plate and frame filter
all (a), (b) & (c)
Metallic wire mesh is used as a filtering medium for the separation of dust from dust laden gas in case of a/an
air filter
Which of the following is a coarse crusher?
Gyratory crusher
Sorting classifiers employing differential settling methods for separation of particles make use of the differences in their
terminal velocities
Separation of particles of various sizes, shapes and densities by allowing them to settle in a fluid is called
classification
The specific cake resistance for incompressible sludges is (where ΔP = pressure drop over cake)
independent of ΔP
To produce talcum powder, use
ball mill
Angle of nip of the crushing rolls does not depend upon the
speed of the rolls
Paddle agitator
is suitable for mixing low viscosity liquids.
Pick out the wrong statement.
Cutting machines mainly employ ‘attrition’ for size reduction of solids.
Cutting machines mainly employ ‘attrition’ for size reduction of solids.
Ribbon
Soft & non-abrasive materials can be made into fines by
attrition
In constant pressure filtration,
rate of filtration decreases with time
The critical speed of a trommel (N) is related to its dia (D) as
N α 1 / sqrt D
Which of the following minerals is not subjected to magnetic separation method?
Galena
Which of the following is not a revolving/tumbling mill used for size reduction?
Cage mill
Which of the following achieves the least reduction ratio for a given feed size?
Roll crusher
A fluid energy mill is used for
ultragrinding
For coarse reduction of hard solids, use
compression
In a size reduction crushing operation, feed size is 100 to 300 mm. while the product size is 10 to 50 mm. This is a case of the __________ crushing.
secondary
Traces of liquid tar fog present in coke oven gas is separated using
electrostatic precipitator
Work index is the gross energy (kWh/tonne of feed) necessary to reduce a very large feed to such a size that 80% of product particles will pass through a 0.1 mm screen. The value of work index determined for wet grinding should be multiplied with __________ to get the same for dry grinding.
1.34
Choke crushing (in case of a Jaw crusher) compared to free crushing
consumes more power.
The specific surface of spherical particles is proportional to (where,Dp= diameter of particle).
1/Dp
Wheat is ground into flour in a
roller crusher
Gravity stamp mill is meant for the __________ crushing.
fine
Washability curve based on float and sink test enables an assessment to be made of the possibility of cleaning a coal fraction based on the
density separation.
Pick out the wrong statement:
Reduction ratio in crushing operation is defined as the ratio of minimum feed size to the maximum product size.
