1993-10-a-mo
Match the following:
I. Gyratory crusher
II. Hammer mill
III. Buhrstone mill
IV. Fluid energy mill
1989-3-i-a-mo
The angle formed by pouring a powder as a heap on a flat surface is known as:
1990-3-i-mo
In a gyratory crusher the size reduction is effected primarily by:
1995-1-g-mo
A fluid energy mill is used for
1997-1-10-mo
For crushing of solids, the Rittinger’s law states that the work required for crushing is proportional to
1998-1-12-mo
The work index in Bond’s law for crushing of solids has the following dimensions
2002-1-17-mo
Arrange the following size reduction equipment in the decreasing order of the average particle size produced by each of them.
2003-12-mo
Energy requirement (per unit mass of material crushed/ground) is highest for
2005-17-mo
The critical speed of the ball mill of radius \(R\), which contains balls of radius \(r\), is proportional to
2007-12-mo
Size reduction of coarse hard solids using a crusher is accomplished by
2008-14-mo
The power required for size reduction in crushing is
2010-1-mo
The critical speed (revolution per unit time) of a ball mill of radius \(R\), which uses balls of radius \(r\) is
2014-17-mo
In order to produce fine solid particles between 5 and 10 \(\mu \)m, the appropriate size reducing equipment is
1989-3-iii-a-mo
For proper functioning of a ball mill, it has to be operated at a speed ––––- (less / more) than its critical speed.
1989-13-ii-mo
A material is crushed in a jaw crusher and the average size of the particle reduced from 5 cm to 1 cm, with the consumption of energy of \(1.32\times 10^4\) J/kg. What will be the consumption of energy (in kJ/kg) to crush the same material of an average
size of 7.5 cm to 2.5 cm, assuming:
(a) Rittinger’s law
{#1}
(b) Kick’s law
{#2}
1991-14-i-mo
The power required to crush 100 ton/hr of a material is 179.8 kW, if 80% of the feed passes through a 51 mm screen and 80% of the product passes through a 3.2 mm screen. What is the work index (in kWh/ton) of the material?
{#1}
What will be the power (in kW) required for the same feed at 100 ton/hr to be crushed to a product such that 80% is to pass through a 1.6 mm screen?
{#2}
2006-78-79-mo
A continuous grinder obeying the Bond crushing law grinds a solid at the rate of 1000 kg/h from the initial diameter of 10 mm to the final diameter of 1 mm.
(i) If the market now demands particles of size 0.5 mm, the output rate of the grinder (in kg/h) for the same power input would be reduced to
{#1}
(ii) In order to restore the output back to 1000 kg/h, an additional grinder was installed. The two grinders can be operated either in series (configuration-1) or parallel (configuration-2). Compare the two configurations in terms of the additional power consumption over the case above.
{#2}
2001-2-8-mo
The energy required per unit mass to grind limestone particles of very large size to 100 \(\mu \)m is 12.7 kWh/ton. An estimate (using Bond’s Law) of the energy to grind the particles from a very large size to 50 \(\mu \)m is
2002-2-20-mo
What is the critical rotational speed, in revolutions per second, for a ball mill of 1.2 m diameter charged with 70 mm diameter balls
1987-13-i-mo
n a ball mill of diameter 2000 mm, 100 mm dia steel balls are being used for grinding. Presently, for the material being ground, the mill is run at 15 rpm. At what speed (in rpm) will the mill have to be run if the 100 mm balls are replaced by 50 mm balls,
all the other conditions remaining the same?
1988-13-i-mo
A pair of rolls is to take a feed equivalent to spheres of 3 cm in diameter and crush them to spheres having 1 cm diameter. If the coefficient of friction is 0.29, what would be the diameter (in cm) of rolls?
1992-14-a-mo
Particles of average feed size \(25\times 10^{-4}\) m are crushed to an average product size of \(5\times 10^{-4}\) m at the rate of 15 tons per hour. At this rate the crusher consumes 32 kW of power of which 2 kW are required for running the mill empty.
What would be the power consumption (in kW) if 10 tons per hour of this product is further crushed to \(1\times 10^{-4}\) m size in the same mill? Assume that Rittinger’s law is applicable.
1996-15-mo
The rate of grinding of uniform sized particles is assumed to follow first order breakage of particles. 50 grams of powder of average diameter 215 microns was ground in a laboratory batch mill. The amount of unground material (215 microns) was measured at various times of grinding and the results are given in table. Estimate the specific rate of grinding (in s\(^{-1}\)).
Weight (gram) | 50 | 17 | 12 | 8 | 6 | 2 |
---|---|---|---|---|---|---|
Time (s) | 0 | 60 | 90 | 120 | 150 | 240 |
Last Modified on: 03-May-2024
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