Jigging is a gravity concentration method that separates minerals based on specific gravity using a pulsating water current to create stratification. It is commonly used in industries such as coal and minerals like gold and tungsten, and involves various jig designs that optimize the separation process through mechanisms like screens and hydraulic adjustments. The jigging process relies on repeated fluid pulsations to expand and consolidate the particle bed, allowing heavy and light particles to stratify according to their specific gravities.

1. Jigging
Mineral processing

2. Jigging is one of the oldest methods of gravity concentration,
In the jig the separation of minerals of different specific
gravity is accomplished in a bed which is rendered fluid by a
pulsating current of water so as to produce stratification.
The jig is normally used to concentrate relatively coarse
material and, if the feed is fairly closed sized (e.g. 3-10mm), it
is not difficult to achieve good separation of a fairly narrow
specific gravity range in minerals in the feed (e.g. fluorite, sp.
gr. 3.2, from quartz, sp. gr. 2.7). When the specific gravity
difference is large, good concentration is possible with a
wider size range. Ex: Many large jig circuits are still operated
in the coal, cassiterite, tungsten, gold, and iron-ore
industries.

3. Aim of jigging
To dilate the bed of material being treated and to control the dilation
so that the heavier, smaller particles penetrate the interstices of the
bed and the larger high specific gravity particles fall under a
condition probably similar to hindered settling.

4. Conventional jig

5. Jigging:
 Jiggs are commonly used to clean coal but are also used
in heavy mineral separations including gold.
 When treating coal, the light fraction is the concentrate
and in the mineral industry the heavy fraction is the
concentrate.
 The jig is commonly an open tank filled with water, with a
horizontal screen near the top,
 Some early jigs were designed where the screens
surface, in the form of basket, moved up and down in a
barrel or tank of water, hence producing the vertical flow
of the fluid through the bed of particles.
 Some movable screen jigs are still designed today
through most modern jigs employ a stationary screen

6.  The difference between the various types of jigs available related
to the method used to generate the pulsation and the manner in
which the heavy fraction is removed from the jigs.
 The screen is there to support the bed of the particles and the
area underneath the screen is called the hutch.
 The tank is usually divided into two main sections: one containing
the support screen with the bed of ore and the another section
which generates the fluid pulse.
 The heavy discharge from the jig may be either through the
screen or over the screen.

7.  In jigging through the screen, all particles in the feed are smaller
than the screen aperture and thus have the potential to drop
through the screen and collect in the hutch.
 To stop the light fraction falling through the screen, a false
support is provided in the form of a layer of coarse heavy particles
ragging which then contacting the screen surface pack down to
effectively close off the screen apertures to the feed particles.
 Example of ragging material is Feldspar for coal jigs.
 Large jigs are divided into separate compartments with different
operating condition for each compartment, such as roughing and
scavenging and cleaning duties etc.

8.  For feed particles larger than the apertures of the supporting screen,
jigging over the screen may be practiced, and the heavy product
grade is partly controlled by the thickness of the bottom layer which
in turn is controlled by the rate of withdrawal through the heaviest
discharge port.
 Gates are operated to allow the heavy fraction to drop into a bucket
elevator for removal.
 Positioning of the gate opening is controlled by the location of the
boundary between light and heavy layers and this is determined by a
weighted float positioned in the bed or monitoring the pressure
fluctuations in the pulsating water.

9. Types of
jig
Essentially the jig is an open tank filled with water, with
a horizontal jig screen at the top, and provided with a
spigot in the bottom, or hutch compartment, for
concentrate removal.
The jig bed consists of a layer of coarse, heavy particles,
or ragging, placed on the jig screen on to which the
slurry is fed. The feed flows across the ragging and the
separation takes place in the jig bed so that grains with
a high specific gravity penetrate through the ragging
and screen to be drawn off as a concentrate, while the
light grains are carried away by the cross-flow to be
discarded as tailings.
The harmonic motion produced by the eccentric drive is
supplemented by a large amount of continuously
supplied hutch water, which enhances the upward and
diminishes the downward velocity of the water

10. Harz jig
One of the oldest types of jig is the Harz (Figure 10.10)
in which the plunger moves up and down vertically in a
separate compartment. Up to four successive
compartments are placed in series in the hutch. A high-
grade concentrate is produced in the first
compartment, successively lower grades being
produced in the other compartments, tailings
overflowing the final compartment. If the feed particles
are larger than the apertures of the screen, jigging
"over the screen" is used, and the concentrate grade is
partly governed by the thickness of the bottom layer,
determined by the rate of withdrawal through the
concentrate discharge port.

11. Denver mineral
jig
The Denver mineral jig (Figure 10.11) is
widely used, especially for removing
heavy minerals from closed grinding
circuits, thus preventing overgrinding.
The rotary water valve can be adjusted so
as to open at any desired part of the jig
cycle, synchronisation between the valve
and the plungers being achieved by a
rubber timing belt.
By suitable adjustment of the valve: any
desired variation can be achieved, from
complete neutralisation of the suction
stroke with hydraulic water to a full
balance between suction and pulsion.

12. Coal jig (used in coal industry)
•Jigs are widely used coal-cleaning devices, and are preferred to the more
expensive dense medium process when the coal has relatively little middlings,
or "near-gravity" material, like: British coals.
•No feed preparation is required, and for coals which are easily washed, i.e.
those consisting predominantly of liberated coal and denser rock particles.
•Two types of air-pulsated jig – i.e. Baum jig and Batac jig
Air under pressure is forced into a large air chamber on one side of the jig vessel causing
pulsations and suction to the jig water, which in turn causes pulsations and suction
through the screen plates upon which the raw coal is fed, thus causing stratification.

13. Coal jigs
•Suitable for coarse load,
•Feed size range : max 175-200mm
min 40-60 mm
• Air pulsation type
• Two or three product (light materials,
middling and heavy densed type)
• Automatic discharge modular design, bed
area and elevator designed to suit duty.
• Designed to handle high portions of sinks
compared to the mineral jig.

14. Principle of operation and fundamentals
Stratification in a bed of particles results from the repeated pulsation
of a current of fluid up through the bed.
The particles in the bed are expanded so that when pulsation ceases,
the particles are allowed to consolidate under the influence of gravity.
The expansion and contraction of the bed is repeated in a cyclic
operation until the heavy and light particles have stratified according
to their specific gravity.
Frequency of pulsation usually varies from 50-300 cycle per min.

15. Idealised jigging particle distribution over
time

16. As a particle just start to moves from rest, the particle velocity is
small and hence the drag force acting on the particle is
negligible since the drag force increases with particle velocity
relative to the fluid.
That is the initials acceleration of the particles depend only on
specific gravity of the solid and fluid and is independent of the
particle size.
Once the particle reach an appreciable velocity the fluid drag
force becomes significant and it opposes the particle further
acceleration to the extent that eventually the particle
acceleration drops to zero and a constant terminal velocity is
reached which will depend on the particle diameter as well as