FIELD OF THE INVENTION
The present invention relates to Slow Speed Spiral Classifier (SSSC) equipment for
enriching iron ore fines in iron ore beneficiation plant. More particularly, the SSSC
equipment, according to the present invention, is adapted for de-watering and moisture
control on one hand and on the other hand facilitating the improvement in the quality of
product, even if the quality of feed is having inferior grade. Advantageously also, the
present invention provides for an improved configuration of the SSSC equipment directed
to achieve recovery of better quality iron ore fines concentrate particles with moderate
fluctuation in quality of feed material as well as obtaining iron ore fines concentrate with
lesser moisture for transportation purpose through conveyor belts. The invention is thus
basically targeted at enriching the quality of valuable minerals by carefully rejecting the
gangue mineral particles in the SSSC unit. Importantly also, the SSSC unit according to
the present invention would provide for desired better flexibility of operation depending
upon the feed content and thus directed to extract iron ore fines of superior grade even
- from raw minerals of inferior grades and also favour controlling moisture of fines to the
desired level, and thus having prospects of wide advantageous application in iron ore
mines processing plant for recovery of quality fines concentrate from ores/minerals.
BACKGROUND ART
It is well known in the related art that Slow Speed Spiral Classifier (SSSC) is a mineral
beneficiation equipment, engaged mainly in iron ore fines processing plant for de-watering
purposes. The product (iron ore fines concentrate) quality obtained from the conventional
SSSC process is such that the fines largely depends on the quality of its feed material. The
existing equipment is used solely for de-watering of iron ore fines concentrate particle. In
this equipment, two main variable parameters are the speed of spiral rotation and the
other one being the height of overflow weir, which are optimized to recover maximum
possible iron ore concentrate as the output with controlled moisture, wherein water to be
rejected leaving mostly through overflow weir. Conventionally, SSSC unit is fed from one
entry point only, its product is raked up from the slurry pool whereas its reject is discarded
through the overflow side.
The above conventional configuration suffers from the limitations of lack of desired precise
control of moisture level in iron fines at output of the equipment and also is not capable to

meet/maintain the desired quality level at output when the input quality of ore is
degraded.
There has thus been a persistent need in the art to developing a device/equipment with
improved design and functional configuration to carry out the operation of the SSSC over
coming the limitations of the prior art process for beneficiation of iron fines from ore
wherein not only the water would be rejected in a manner to precisely control the moisture
level to the desired level but also said equipment and the process carryout therein would
be adapted to accommodate the variation including the input inferior ore grade and still
deliver fines concentrates to meet the desired consistent quality criteria.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention to provide a Slow Speed Spiral Classifier
(SSSC) for iron ore fines processing in ore beneficiation plant adapted for enriching the
quality of valuable minerals and rejection of water to achieve desired moisture content
which in turn would favour transportation on belt conveyor and at the same time maintain
superior grade of fines at the output of equipment even when the input ore grade is of
inferior quality.
Another object of the present invention is directed to a SSSC equipment having improved
design configuration to meet/maintain the output moisture content as well as superior
quality of iron ore fine concentrates adapted to receive ore input at three different points
in said equipment.
A further object of the present invention is directed to developing a SSSC equipment
having improved design configuration adapted to deliver desired moisture content and
consistent superior quality of iron ore fines wherein said device and the process carried out
therein is targeted at enriching the quality of valuable minerals by carefully rejecting the
gangue mineral particles in the SSSC unit.
A still further object of the present invention is directed to developing a SSSC equipment
adapted to recover better quality iron ore fines concentrate particles with moderate
fluctuation in quality of feed material.

A still further object of the present invention is directed to developing a SSSC equipment
multipoint and preferably three feed entry points instead of conventional one are designed
in such a way that gangue mineral particles get discarded through the classifier overflow.
A still further object of the present invention is directed to developing a SSSC equipment
wherein the exact position of the feeding point for effective rejection of gangue mineral
particles depends on the characteristics of the valuable as well as gangues mineral
particles and the movement of the particles in the pool area.
A still further object of the present invention is directed to developing a SSSC equipment
wherein said device is having simple operation with the facilities of adjusting the overflow
weir height , the option for easy fixation / removal of weir plate and variable feed entry as
well as movement of mineral particles in the pool favour rejection of gangue mineral
particles from the product concentrate.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a slow speed
spiral classifier adapted for enriching the quality of valuable minerals comprising:
a spiral means adapted for maximum possible recovery of iron ore concentrate in the
product and an overflow weir to drain out reject water and a variable feed entry point
adapted such that the gangue mineral particles are effectively discarded through the
classifier overflow.
Another aspect of the present invention is directed to said Slow speed spiral classifier
wherein the variable feed entry points are selectively provided such as to achieve effective
rejection of gangue minerals particles depending upon the characteristics of the valuables
as well as gangues mineral particles and movement of the particles in the pool area.

A further aspect of the present invention is directed to said Slow speed spiral classifier
wherein the variable entry points comprise plurality of entry points adapted to be operated
one at a time or in combination depending upon the characteristics of the mineral particles
to be enriched.
A still further aspect of the present invention is directed to said Slow speed spiral classifier
comprising three entry points for the feed.
Also in the Slow speed spiral classifier of the present invention comprising means for
adjusting the overflow weir height.
A still further aspect of the present invention is directed to said Slow speed spiral classifier
having means for easy fixation /removal of the weir plate.
According to yet another aspect of the present invention directed to said Slow speed spiral
classifier comprising said spiral means adapted for variable spiral speed involving variable
speed variable frequency drive and adapted to monitor the movement of the ore/mineral
particles inside the classifier pool.
Another aspect of the present invention is directed to Iron ore mines processing plant for
recovery of quality fines concentrate from ores comprising a slow speed spiral classifier as
of the present invention.
A still further aspect of the present invention is directed to a process for the recovery of
ore fines concentrate from ores comprising the step of carrying out the recovery of fines
from ores in a slow speed spiral classifier according to the present invention.

An yet further aspect of the present invention is directed to said process for the recovery
of pre fines concentrate from ores wherein the ore fines concentrate obtained are with
lesser moisture from slurry favouring transportation through conveyor belts.
The present invention and its objects and advantages are described in greater details with
reference to the accompanying non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the image of an embodiment of the conventional Slow Speed Spiral Classifier
(SSSC).
Figure 2: is the schematic illustration of the improved configuration of the SSSC
equipment having selective three feed entry points at different location of the spiral,
according to the present invention adapted to ensure desired moisture content and
superior quality of iron fine concentrates even with inferior quality of input mineral ore.
DETAILED DESCRIPTION OF THE INVENTION WITH-- REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to an improved design configuration of the Slow Speed
Spiral Classifier (SSSC) having multiple, preferably three feed entry points for input raw
iron ore minerals adapted to generate iron fines of rich quality with desired controlled level
of moisture content favoring transportation by belt conveyor, regardless of the variation in
quality degradation of raw material input. The device of the invention further equipped
with means for adjusting the overflow weir height and the option for easy fixation/
removal of weir plate that favour rejection of gangue mineral particles from the product
concentrate.
Reference is first invited to the accompanying Figure 1 that illustrates an image of the
conventional SSSC equipment that is primarily aimed at de-watering of the iron ore fines

to collect the iron fine concentrates for transportation by the belt conveyor. It is clearly
apparent from the Figure 1 that such conventional equipment is usually having two main
variable parameters such as the speed of spiral and height of overflow weir, that are
selectively optimized to recover maximum possible iron fines concentrate in its product
leaving most of the water to be rejected through overflow weir. The only one entry for
input raw mineral is located at more or less middle position of the spiral classifier.
Conventionally, the prior art SSSC unit is fed with raw iron ore material/minerals through
only one entry point such that the end product of desired fineness, concentration and
moisture content obtained by being processed through spiral classifier of the device and is
raked up from the slurry pool whereas its reject is discarded through the overflow side.
Such conventional SSSC system thus is not adapted to have any control on overflow weir
or control on hydro-cyclone underflow product for effective separation of gangue mineral
particles from the valuable minerals by control of movement of the mineral particles (less
than 30 mesh size) in the pool area or any precise control on moisture content of the iron
ore fine concentrates recovered from the system at the discharge end. Moreover, the
existing system suffers from the limitations of failing to maintain the required quality of
iron fines concentrate recovered at the output/discharge, when the input quality of raw ore
material is of inferior grade.
Reference is now invited to the accompanying Figure 2 that shows the schematic
illustration of the SSSC device according to the present invention. The improved design
configuration is adapted to provide an additional design parameter to the conventional
system comprising the parameters like the speed of spiral and height of overflow weir that
is the Variable feed entry point' to the SSSC unit. It is clearly apparent from the
embodiment of the SSSC equipment of the present invention is having three different
feeding entry points to the spiral classifier unit. The device of the present invention is thus
adapted not only to be used for de-watering purpose but also improves the quality of
product, even if the feed quality is of inferior/off grade. Importantly, the device of the
present invention is directed to enriching the quality of valuable minerals by carefully
rejecting the gangue mineral particles in the SSSC unit.
The equipment according to the present invention is directed to modifying the conventional
SSSC equipment to act as beneficiation equipment instead of working only as de-watering
unit. The changes are made in the feeding arrangement by incorporating multiple feed
entry points instead of only one entry point as in the existing unit.

The exact location of these feed entry points for effective separation of gangue mineral
particles from the valuable minerals depends on the understanding of characteristics as
well as movement of the mineral particles in the pool area.
The usage of the feed entry points is optimized such that the product made in Slow Speed
Spiral Classifier obtained as of uniform richer quality, even if the feed mineral particles
fluctuate in its chemical composition.
According to an important aspect of said design modification of existing SSSC lies in the
input materials feeding arrangement. Three feed entry points instead of one are selectively
located in such a way that gangue mineral particles get discarded through the classifier
overflow. The exact position of the feeding point for effective rejection of gangue mineral
particles depends on the characteristics of the valuable as well as gangues mineral
particles and the movement of the particles in the pool area. Such an input feeding
arrangement and mineral beneficiation in spiral classifier of the invented equipment
configuration facilitate overcoming the problem of variation in quality of input raw iron ore
fines/minerals and ensure desired quality standard of the iron fine concentrate at the
output/discharge end of classifier, despite inferior grade of ore input feeding.
Advantageously, the SSSC device of the present invention is further adapted to providing
the facilities of adjusting the overflow weir height. This in turn facilitate easy
fixation/removal of weir plate will add to rejection of gangue mineral particles from the
product concentrate. In order to monitor/control the desired movement of ore / mineral
particles inside the classifier pool, the Spiral speed is varied using variable speed variable
frequency drive (VVVF drive). All the three entry points of SSSC unit can be operated
one at a time or in combination depending on the characteristics of the mineral particles to
be enriched.
It is further observed that while the multiple input entry point slow speed spiral classifier
according to the invention is installed and operated experimentally in one of the plants of
the applicants, the same demonstrated that the hydro-cyclone underflow product, which is
iron ore fines of size less than 30 mesh usually being fed to this SSSC unit mainly for de-
watering purpose, in the present configuration of the SSSC provide means for the hydro-
cyclone underflow product to undergo enrichment, three feed entry points in SSSC is
designed, wherein feed can enter in one entry point at a time or slurry can be fed in multi
feed entry points. Thus one more variable parameter is added to operate in tandem with

conventional parameters during the experimental run of the SSSC unit to achieve desired
fineness concentration, enriched quality and moisture/water content for transportation by
means of belt conveyor for next stage of processing. According to an embodiment of the
present invention said three entry points are selectively disposed as entry point 1 at the
most close to discharge; entry point 2 at the middle point and the entry point 3 is located
at the farthest from discharge end of the spiral classifier;
The chemical analysis of the SSSC test samples obtained by carrying out the
enrichment/de-watering process in the SSSC equipment with 3 input points are presented
in the following Table 1.
Table-1 : Chemical composition of SSSC test sample.
Entry point 1 - close to discharge;
Entry point 2 - middle point;
Entry point 3 - farthest from discharge;

The Table-1 shows that hydro-cyclone underflow product could be best enriched in SSSC
unit developed according to the present invention having three input raw material entry
points, if the material is fed in entry point-1 or in entry point-2 which is in the range of
62.34wt.% Fe and 62.4wt.% Fe respectively, though the yield in these cases would be
lesser compared to using feed entry point - 3 which is 60.86wt.%, which is farthest point
from overflow discharge. It is further observed that the respective LOI (Loss On Ignition,
which is chemically bonded water) of overflow (O/F) are 4.42%, 4.17% and 4.02%. This
clearly indicates that the ore particles with higher LOI are lighter and thus inferior with
respect to iron content. The corresponding granulometric analysis of SSSC product and
SSSC overflow show the evidence of the effect on variable feed entry operation.

It is thus possible by way of the present invention to developing a SSSC device for
effective beneficiation of the iron ore fines as well as de-watering the enriched concentrate
discharged from the device, with consistent superior quality irrespective of variation in
input raw material grades/inferior grades, by providing selectively disposed three entry
points for input of raw mineral particles, such that controlled movement of the underflow
of the minerals effectively separates the enriched iron fines and the gangue minerals for
discarding. Moreover, the adjustable weir heights also provide means for controlled water
overflow/separation from valuables iron ore fines and at the same time selectively discard
the gangue mineral particles progressively by controlling feeding entry points depending
on characteristics of the input minerals. The enriched iron ore fine concentrates thus
discharged at the discharge end is having selective water/moisture contents favoring easy
and safe transportation of the same for subsequent use in iron and steel making.

WE CLAIM:
1. Slow speed spiral classifier adapted for enriching the quality of valuable minerals
comprising:
a spiral means adapted for maximum possible recovery of iron ore concentrate in
the product and an overflow weir to drain out reject water and a variable feed entry
point adapted such that the gangue mineral particles are effectively discarded
through the classifier overflow.
2. Slow speed spiral classifier as claimed in claim 1 wherein the variable feed entry
points are selectively provided such as to achieve effective rejection of gangue
minerals particles depending upon the characteristics of the valuables as well as
gangues mineral particles and movement of the particles in the pool area.
3. Slow speed spiral classifier as claimed in anyone of claims 1 or 2 wherein the
variable entry points comprise plurality of entry points adapted to be operated one
at a time or in combination depending upon the characteristics of the mineral
particles to be enriched.
4. Slow speed spiral classifier as claimed in anyone of claims 1 to 3 comprising three
entry points for the feed.
5. Slow speed spiral classifier as claimed in anyone of claims 1 to 4 comprising means
for adjusting the overflow weir height.
6. Slow speed spiral classifier as claimed in anyone of claims 1 to 5 having means for
easy fixation /removal of the weir plate.

7. Slow speed spiral classifier as claimed in anyone of claims 1 to 6 comprising said
spiral means adapted for variable spiral speed involving variable speed variable
frequency drive and adapted to monitor the movement of the ore/mineral particles
inside the classifier pool.
8. Iron ore mines processing plant for recovery of quality fines concentrate from ores
comprising a slow speed spiral classifier as claimed in anyone of claims 1 to 7.
9. A process for the recovery of ore fines concentrate from ores comprising the step of
carrying out the recovery of fines from ores in a slow speed spiral classifier as
claimed in anyone of claims 1 to 7.
10. A process for the recovery of ore fines concentrate from ores as claimed in claim 9
wherein the ore fines concentrate obtained are with lesser moisture from slurry
favouring transportation through conveyor belts.
11. Slow speed spiral classifier adapted for enriching the quality of valuable minerals
substantially as herein described and illustrated with reference to the
accompanying figures.

A Slow speed spiral classifier (SSSC) adapted for enriching the quality of valuable minerals
wherein the variable feed entry points provided to achieve effective rejection of gangue
minerals depending upon the characteristics of the valuables and gangue mineral particles
and desired movement of the particles in the pool area. Said plurality of feed entry points
operated one at a time or in combination depending upon the characteristics of the mineral
particles enriched to desired quality, regardless of variation in quality of input minerals. A
spiral means adapted for maximum possible recovery of iron ore concentrate and an
adjustable overflow weir to favour drain out reject water. A variable spiral speed is used
involving variable speed variable frequency drive for controlled movement of the mineral
particles inside the classifier pool. A process for the recovery of enriched ore fines
concentrate from slurry with lesser moisture using the SSSC, favouring transportation
through conveyor belts in iron ore mines processing plant.