Aim of the experiment: Crushing of ore using Jaw crusher.
Apparatus Required: Laboratory model Jaw Crusher,
materials (for crushing), Vernier calipers.
Objective: To study the jaw crusher and measure
the reduction ratio and capacity of the crusher.
Theory :“Crushing Process” is defined as the
group of operation in a mineral dressing process whose object is to reduce
large lumps to fragment.
“Crusher” is
slow speed machines for coarse size reduction of large quantities of solids by
using compressive force. The main significance of an ideal or grinder should: -
i.
Have a large capacity.
ii.
Require a small input per unit wet of
production.
iii.
Yield a product of single size or required
size distribution.
Constructional Features of JawCrusher: The crusher mainly consists of:
1) Frame 2) Fixed jaw plate 3) Left and
right protecting boards 4) Movable jaw plate 5) Movable jaw 6) Eccentric shaft
7) Toggle plate 8) Toggle seat 9) Components and parts such as oil pressure
lifter
The motor drives eccentric shaft via a belt fixed in a grooved pulley,
which can make movable jaw move repeatedly so it can crush more material. Fixed
jaw plate of frame front wall is fastened depending on left and right
protecting boards and holding down bolts, while movable jaw plate is pressed
tightly on movable jaw depending on battens. When the jaw plates are abraded
(usually under side of the jaw Toggle plate) can not only bear the weight of
movable jaw, but also protect other parts of the machine from hurting. When
un-broken foreign materials come into crushing cavity which results in heavy
load increase of toggle plate, the toggle plate breaks down itself to cut off
the heavy load so as to protect other parts of the jaw crushers. Toggle seat is
fastened on ear seat of the jaw crusher’s two sides by draw bolts; depend on
hydraulic pressure lifter (lifting bolts) to lift out toggle seat, change pad
thickness, and i.e. be able to adjust the width of discharge outlet. As the
name suggest a jaw crusher has two jaws set to from a V shape at the top
through which feed is admitted in to the jaws. One of the jaw is fixed to the
main frame of the crusher almost vertically while the outer than the movable.
The swinging jaw reciprocate in a horizontal plane and make an angle an 20-30
degree with the stationary jaw and is driven by an eccentric so as to that it
applying a great compressive force on the ore lumps caught between the jaws. On
the jaws, replaceable crushing faces are fixed by nut & bolt arrangement. The
crushing faces are made from “Hardfiled Manganese” steels. When extensive wear
is observed on any of the faces it is replaced by new one. The crushing jaw
faces are flat. Initially the large lump is caught at the top and is broken materials
drop to the bottom space (set). The jaw running speed vary from 100-400 rpm
(100-400 times).
Jaw Crushers
are basically in two types
(1) Blake
jaw Crusher, (2) Dodge jaw Crusher
Blake jaw Crusher
The movable
jaw is hinged at the top so that greatest amplitude of motion is at bottom of
the crushing face.
Dodge jaw Crusher
The movable
jaw is hinged at the bottom so that greatest amplitude of motion is at top of
the crushing face.
Working Principle:
i.
Before
starting the experiment inspect the machine. Check the motor and gear drives.
ii.
Set
the jaw plate distance through using jaw plate moving handles. After setting of
the jaw plates close the handles carefully.
iii.
Fill
the raw material hopper before starting of crushing.
iv.
After
completion of primary preparation the start the motor.
v.
Collect
crushed material for the observation.
Observation Table:
Sample
weight |
Max size
of feed (mm)
|
Max size
of product (mm)
|
Length of
gap(mm)
|
Length of
set(mm)
|
Time taken
to crush (sec)
|
Weight of
feed after crushing
|
Calculation
1. Reduction Ratio: The reduction ratio
of average feed size to the average product size is known as reduction ratio.
2. Capacity: The capacity of the jaw
crusher mainly depends on the length and width and width of receiving operation
and the width of the discharge. As per target, the empirical formula for
capacity of jaw crusher is,
T=0.6LS
Where T=T is the capacity tons per hour
L= Length of receiving opening in
inches.
S= Set or Width of discharge opening in inches
thank u sir
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I own a 9"x16" 1917 Gruendler Blake-type ... Interesting article!
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