Comminution-grinding (last yr quiz) Flashcards
A crushing operation is achieved by _______ of the ore against rigid surfaces.
compression
The Comminution operation in its earliest stages (of production) is being done in
order to?
HANDLE THE MATERIALS EASILY BY THE ORE CARRIERS SUCH AS
CONVEYOR BELTS. IT IS ALSO BEING DINE IN ORDER TO HAVE MATERIALS
WITH CONTROLLED PARTICLE SIZE.
What is regarded as the first stage of comminution as it removes ores from their
natural beds?
Blasting
What do you call the angle theta?
Angle of Nip
In a dry crushing operation with a slow feeding rate, the crushed products are
immediately removed from the crushing zone to eliminate excess fines by reducing
the number of contacts. This type of crushing is known as?
Free Crushing
In mineral processing, the measurement of the ore’s hardness is reported to as?
Work Index
This is the measurement of the ease with which materials can be comminuted.
Ore Grindability
Who suggested that the relationship between energy and particle size is a
composite form of Kick’s, Rittinger’s and Bond’s Laws?
Hukki
This is a specialized form of a cone crusher for the production of very fine materials
that has found a wide application in the quarrying industry
Gyradisc Crusher
This crusher is utilized for soft, friable and sticky ores that behave plastically when
fed in a slow compression crushing such as coal and phosphates.
Roll Crusher
T or F
In any industrial comminution operation, the breakage of any individual particle is
not occurring simultaneously with that of many other particles.
false (occurring simultaneously)
12.In gyratory crusher, what do you call the moving or gyrating component of the
crusher?
Mantle
t or f
Compressive force applied at a slow rate, the energy applied will be in excess of
that required for fracture that will result in a comparatively large number of particles
with a wide size distribution.
False (energy applied is sufficient to load comparatively few regions of the
particle to the fracture point and only a few particles result)
This law states that energy of breakage is directly proportional to the amount of
new surfaces produced.
Rittinger’s Law
In a blake crusher, the minimum distance between two jaw plates is called the?
Closed Set
In a blake crusher, the distance between the two jaw plates at the feed opening is
termed as?
Gape
The following are the objectives of comminution except:
a. To liberate valuable partcles from gangue.
b. To decrease the surface area to lessen the consumption of reagents.
c. To reduce pieces of ores into smaller ones.
d. To produce solids of desired sizes.
B
A primary crusher in which the inner conical shell is pointing up and outer conical
shell is pointing down.
Gyratory Crusher
This law states that the energy required for producing analogous changes in
configuration in geometrically similar bodies of equal technological state varies as
the volumes or weights of these bodies.
Kick’s Law
In crushing operation, the extent of size reduction is being described through what
measure?
Reduction Ratio
If the jaw crusher has a fixed discharge area and variable receiving area, this is
called?
Dodge Crusher
The process of separating the ore minerals from the gangue minerals is?
Mineral Processing
This law states that the work input is proportional to the new crack tip length
produced in particle breakage.
Bond’s Law
What mechanism of fracture is a result of insufficient energy being applied on the
particle, and localized stress occurs. This produces a small area that is fractured
giving very fine particles
Abrasion
25.There are modifications of Jaw crushers that resulted to many types, in what way
do they primarily differ?
Pivoting of the swing jaw
Coase grinding produces products within the size range of?
1-10mm
t or f
Abrasion fracture will occur if compressive force acts parallel to the surface of the
particle.
f (when a shear force)
In a blake crusher, the distance between the two jaw plates at the discharge
opening is called?
set
What crusher that has stepped liners on the outside surface to allow a coarser
feed?
Standard Cone Crusher
30.The primary crushers are?
Jaw Crusher
Gyratory Crusher
In a blake crusher, the maximum distance between two jaw plates is called the?
Ans: Open set
Open Set
In crushing, what are the predominant applied breakage forces?
Compression or Impact
When the liberation results to equal particle size, liberation size and grain size, this
is called what?
Intergranular Liberation
What is the dominant force in grinding?
Attrition or Shear
What is the continuous operation used for the separation of particles according to
their sizes?
Screening
This is the size of a mineral as it occurs in the ore.
Grain Size
Grinding balls are conveniently added through this feeder during operation.
Drum Feeder
zones sa ball mill
Empty Zone
Dead Zone
Zone of Circular Path
Zone of Parabolic Path
The interior of tumbling mills is made up of alloy steel or rubber termed as?
Liners
What is the last stage of comminution process?
Grinding
This screen is mounted either horizontally or with a gentle slope, has a slow linear
motion essentially in the plane of the screen.
Shaking Screen/Vibrating Screen
A vibrating screen that makes use of the principle that particles having a size less than the aperture statistically require a certain number of presentations to the screen in order to pass.
Mogensen Sizers
t or f
Sieving is a batch process that is an industry-scale
False(Industry Scale in industrial screening)
What screen surface is best used for lumpy and coarser size particles?
Parallel Rods
If a tumbling mill has a length to diameter ratio of 1.5 to 1.0, this is classified as?
Ball Mill
What type of grinding mill uses a combination of the ore and a reduced charge of
balls or rods as a grinding medium
SAG/ Semi Autogenous Mill
What do you call the particles that pass through the screen aperture?
Undersize
A liberation in which fracture may take place preferentially at the boundary of
mineral grains. If ore is reduced in size to grain size of valuable mineral, all the
valuable mineral particles exist as free particles, no matter whether remaining
particles are free or locked particles of gangue minerals
Intergranular Liberation
A type of industrial screen that has equally spaced parallel rods or bars running in flow direction and sloped to allow gravity transport, mainly used for dry separation of lumpy or coarse particles.
Grizzly
A screen that is used to remove small amounts of either oversizes or undersizes.
Scalping Screen
The beneficiation method to be used depends on liberation size of the ore which in turn depends on type of the ore, which of the following is a disseminated ore type?
Gold ore
If liberation of particles is not appropriately and sufficiently done, what next operation is impractical to be accomplished?
Separation
The free particles of an ore consist of a single mineral, which can be?
Either Valuable or Gangue Particles
Rod mills are usually run at what speed relative to the critical speed?
50-65%
FORMULA
Percent liberation =
amount of free particle/ amount of valuable minerasl x 100
The rate of screening is affected by either machine or material factors. Which of the following is not a material factor?
Angle of incidence of the particle on the screen surface
A woven wire screen surface used for fine particles.
Rectangle
The following are the purposes of industrial screening except:
a. Removal of undersize material before it is sent to the next unit operation which is set to treat material larger than this size
b. Grading of materials into a specific series of sized (finished) products.
c. None of the above
d. Preparing a closely sized feed to any other unit operation
e. Removal of oversize material before it is sent to the next unit operation as an open circuit crushing operations.
E
What is the maximum volume that a grinding mill is usually loaded?
50%
Wet screening is superior to dry screening where adhering fines are easily washed off, and it avoids the dust problem. What makes it undesirable?
High cost of dewatering and drying the products.
t or f
In a tube mill, the smaller and fine particles grind together with the coarsest
particles
False (the coarsest particles will be grinded first)
t or f
33.Particles of size more than the aperture size of the screen passed through the
apertures and smaller particles are retained
False (particles more than the aperture size will not pass through the
apertures, rather the smaller particles will pass through the aperture and will not
be retained).
34.In grinding, the free falling of balls is called?
Cataracting
