Crushing (sa book) Flashcards
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____ is that operation or group of operations in a Mineral Beneficiation plant whose object is to reduce large lumps to fragments, the coarsest particles in the crushed product being ____ inch or more in size. The size of coarsest particles is ____ inch in many cases.
Crushing
1/20
1/2
The crushing action in all crushing machines (crushers) results from??
from forces applied to the particles by some moving part working against a stationary or some other moving part
It is the first stage of size reduction.
Crushing
is generally a dry operation and is usually performed in two or three stages.
Crushing
defined as the ratio of the maximum size of the particle in the feed to the maximum size of the particle in the product.
Reduction Ratio
a convenient measure for comparing the performance of different crushers.
Reduction Ratio
Jaw crusher, Gyratory crusher.
Primary Crusher
Reduction gyratory, Cone crusher, Rolls crusher.
Secondary Crusher
Short-head cone crusher.
Tertiary Crusher
Impact Crushers
Fine Crusher
Bradford Breaker, Toothed Roll crusher.
Special Crusher
Special crushers are designed for specific ores, for example, rotary breaker and toothed rolls crusher for ____ and gravity stamps for ____ milling.
Coal
gold ore
____ consist of two jaw plates set at an acute angle, called ____, to each other which forms a crushing chamber.
Jaw Crushers
angle of nip
Motion to the swing jaw is transmitted by ____ working on an eccentric toggles.
Pitman
It refers to the maximum angle subtended by the approaching jaws or roll surfaces at which a piece of ore or material can be gripped and crushed.
Angle of Nip
If the swing jaw is pivoted at the top, it has a fixed receiving area and variable discharge area and is known as a ____.
Blake Crusher
If the swing jaw is pivoted at the bottom, it has a fixed discharge area and variable receiving area and is known as a ____
Dodge Crusher
If the swing jaw is pivoted at an intermediate position, it has both variable receiving and discharge areas and is known as a ____.
Universal Crusher
In a Blake crusher, the distance between the two jaw plates at the feed opening is known as ____.
Gape
The distance between the two jaw plates at the discharge opening is known as ____.
Set
The minimum distance is called ____ and maximum distance is called ____. The maximum amplitude of swing of the jaw is known as ____.
Closed Set
Open Set
Throw
In the mining industry, ____ are used to crush the run-of-mine ore to a size suit able for transportation.
Jaw Crushers
In a ____ the inner conical shell is pointing up and outer conical shell is pointing down. The reduction ratio varies from ____.
Gyratory Crusher
3 to 10
They consist of two vertical truncated conical shells of which the outer hallow conical shell is ____ and the inner solid conical shell is made to ____
Stationary
Gyrate
____ is the modification of gyratory which has straight or curved heads and concaves and used for secondary crushing. The fine ____ crusher can also be used forTertiary Crushing.
Reduction Gyratory Crusher
The ____ is a modified gyratory.
Cone Crusher
____ is the most widely used type of cone crusher.
Simons Cone Crusher
yes with S
2 forms of Simons Cone Crusher
Standard cone crusher and Short-head cone crusher
has a steeper head angle to prevent choking of finer material.
Short Head Cone Crusher
has stepped liners to allow a coarser feed
Standard Cone Crusher
The ____ is another type having a spherical steel head and used for tertiary crushing
Telsmith Gyrasphere
____ consists of two smooth heavy horizontal cylinders revolving towards each other and the feed material is nipped between the rolls and pulled downward through the rolls by friction.
Roll Crusher
The distinguished feature of a roll crusher is that the material is crushed ____ only whilst it is passing through the crushing chamber.
ONE TIME ONLY
____ crushers are generally used for fine crushing whereas corrugated or ____ crushers are used for coarse crushing of soft materials.
Smooth-surface roll crushers
toothed roll crushers
____ roll crusher and ____ roll crusher are the two types of toothed roll crushers used for crushing ____.
Single toothed
Double toothed
coal
____ reduce the particles by impact forces applied through sharp blows of fixed or free swinging hammers revolving about central rotor at high speed to the free falling particles against stationary surfaces
Impact crushers
They are used for relatively soft, friable, and sticky ores such as phosphates, limestone, clay, graphite and coal.
Impact Crusher
In ____, rolls are subjected to high pressure so that comminution takes place by compressive forces as well as by inter-particle breakage. The force applied to the crushing zone is controlled by a ____.
High Pressure Grinding Rolls
Hydro-pneumatic springs
____ are usually operated dry
Crushers
avoids the production of excessive fines by limiting the number of contacts.
Free Crushing
When the material fed to the crusher is at a high rate, the crusher is ____ and it prevents the complete discharge of crushed product.
Choked
____ may be conducted in open or closed circuit.
Crushing
the feed material is reduced by one crusher. The product of this crusher is screened and only oversize material is crushed by another crusher of small size as the throughput (the quantity of material crushed in a given time) is less.
Open Circuit Crushing Operation
the oversize material from the screen is fed back to the same crusher.
Closed Circuit Crushing Operation
The quantity of the oversize material fed back to the crusher is called as
Circulating Load
expressed as a percentage of the quantity of feed material. It is to be noted that the throughput of the crusher is more than that of the crusher used in open circuit crushing operation and equal to the quantity of feed material plus the quantity of oversize material fed back from the screen
Circulating Load
