The present invention relates to a process of beneficiation of iron ore and iron ore like
materials by treating their slurries with low frequency ultrasonic pulses. More
specifically, this invention relates to iron ore slurry (mixture of iron ore and water)
treated with ultrasound pulse to reduce its impurities like alumina (AI2O3), silicon (SiO2),
phosphorus, gangue (unwanted materials like clay etc.) content etc. This is achieved by
using ultrasound transducers for transmitting ultrasound energy into the slurry and a
means for exciting the ultrasound transducers in a frequency range of 20-25 KHz. The
final product is the clean iron ore having less quantity of impurities as mentioned
above.
BACKGROUND OF THE INVENTION
Ores are the main sources of many valuable minerals which are extracted by different
types of existing beneficiation processes like crushing, classifying and washing. Ore
washing is a process wherein the valuable minerals are separated from the gangue on
the basis of their specific gravity difference. The said process of separation is based
upon specific gravity difference by the physical separation of the valuable and the
undesired materials. Iron ore washing is one example of beneficiation by a separation
based upon specific gravity difference between the valuable and the undesired
materials.
Iron ore, as a prime mineral for iron and steel making operation, comprises mostly of
iron (Fe) and small percentages of impurities like alumina (AI2O3), silica (SiO2),
phosphorus, gangue (unwanted materials like clay etc.) content. Iron ore is used in iron
making operations as a source of iron. In this operation, when iron ore is melted, the

presence of impurities like alumina (AI2O3), silica (SiO2), phosphorus, gangue (unwanted
materials like clay etc.) content is generally undesirable. Therefore a course is taken up
traditionally to minimize the gangue materials from the iron ore before changing it in
blast furnace for iron production.
In iron ore, impurities like alumina (Al2O3), silica (SiO2), phosphorus, gangue (unwanted
materials like clay etc.) content can be washed out of iron ore by conventional iron ore
washing methods to a large extent. However these methods are not suitably efficient
on a large scale. Only a small portion of the mined iron ore can be sufficiently upgraded
by washing alone.
The present invention is directed towards improving the washing processes of existing
art by better separation brought by the efficient application of ultrasound energy to the
iron ore slurry.
The proposed invention is directed to the removal of the alumina (AI2O3), silica (SiO2)
content from iron ore and iron ore - like materials and at the same time, the process is
directed to reduce the amount of other impurities like phosphorus, gangue (unwanted
materials like clay etc.) materials within the iron ore or iron ore-like material.
In the present invention ultrasound treatment of iron ore slurries is applied in iron ore
washing processes. Typically, the slurry is kept in an ultrasonic cleaning bath to which
ultrasound transmitters are attached.
The present inventive process besides iron ore washing can be applied for the
beneficiation of other mineral and ores, for example, coal and coal-like material, ferro-

chrome ore, gold ore and tailings etc. wherein the valuable materials and gangue
(unwanted materials) can be separated. An additional advantage of this invention is the
minimization of the abrasive action of the slurry on the apparatus for applying
ultrasound to the slurry.
Sound waves in liquids comprise expansion cycles and compression cycles. During the
expansion cycle, the molecules of the liquid are separated creating a gap or "cavity" in
the liquid. The cavity only exists until the next compression cycle at which time the
cavity rapidly implodes. This implosion creates a microscopic jet directed at or along the
surface of solids within the liquid and also rapidly heats the liquid surrounding the
cavity (which is almost instantaneously cooled by the large mass of liquid). The
combination of extremely hot liquid and microscopic jets work upon the surfaces of the
solids.
In the existing art ultrasound energy having frequencies in the range of about 20-25
KHz has been suggested for treatment of iron ore slurries only. This principle was based
in part upon the expected attenuation of sound energy as it progresses into the slurry.
But with adoption of attenuation principle in natural materials produce a pronounced
effect which further weakens the sound. This weakening of sound results from two
basic causes viz scattering and absorption which are both combined in term attenuation
(sometimes also called extinction). The higher the frequency, the more rapid the
attenuation.
To remove the said difficulties of prior art the present invention has proposed a process
of treating iron ore slurry (mixture of iron ore and water) with power ultrasound to
reduce its impurities like alumina (AI2O3), silica (SiO2), phosphorus, gangue (unwanted
materials like clay etc.) content etc with lower frequency 20-25 KHz in which

cavitational implosive impact is severe to break the bond between the impurities and
iron.
DESCRIPTION OF THE INVENTION:
The main objective of the invention is to provide a process for treating ore slurry with
ultrasound to improve separation based upon specific gravity comprising keeping the
ore slurry in an ultrasonic cleaning bath and applying ultrasound energy to the slurry
passing through the conduit having frequencies in the range of 20-25KHz.
The objectives of the invention are achieved by first crushing and preferably sizing the
iron ore to a more or less uniform size. A particular size for this purpose is selected
depending upon the type of iron ore and the amount of impurities like alumina (AI2O3),
silica (SiO2), phosphorus, gangue (unwanted materials like clay etc.) content to be
removed. Certain iron ore have been found to respond to treatment very well if crushed
in size of +2 mm - 12 mm size.
According to this invention there is provided a process of beneficiation of iron ore like
materials by treating their slurries with ultrasonic pulses to reduce impurities alumina
(AI2O3), silica (SiO2), phosphorus and gangue materials including air bubbles, gels,
slimes or algae associated with the ores comprising the steps of:
a) crushing iron ores in size of +2 mm to - 12 mm,
b) combining the iron ore with water to form a slurry and maintaining the
said slurry below 73°C while keeping the said slurry in an ultrasonic
cleaning bath.

c) applying ultrasonic pulses to the said slurry in the order of 20-25 KHz
which breaks the physical bonds of the said impurities in the ore materials
by pressure of the impulses of the applied ultrasound.
d) physically separating the said isolated impurities from the ore materials by
using devices such as cyclone separators, spiral separators, vibrating
screens or centrifuge separators and recovering upgraded ores with
reduced impurities.
The proposed invention will be better understood from the following description with
reference to the accompanying drawings in which
Figure 1 is a schematic representation of ultrasonic pulse generation and applied on
ultrasonic cleaner/conduit via ultrasonic transducer and
Figure 2 represents a schematic flow sheet diagram showing the sequential steps of
recovering upgraded iron ores, which narrates the invention and does not need any
further elaboration.
In figure 1 the ultrasonic generator (1) is applied with power of 220 watt/litre of water
of the slurry solution. Low frequency ultrasonic pulses within the range of 20-25 KHz
are generated by ultrasonic transducer (3) to provide ultrasonic impulses on the
ultrasonic cleaner (2) arranged in a chamber.
In using ultrasonic in connection with liquids, normally, cavitation will occur in liquids
and is produced in transducer acceleration pressures against the liquid slurry. Cavitation
is the formation of partial vacuums within the liquid. Ultrasonically induced cavitation
appears to promote chemical as well as physical change of substances within the liquid

to which the sound is applied. The important aspect of this invention is the provision of
a unit for applying ultrasound to a iron ore slurry wherein the iron ore slurry is kept in
an ultrasonic cleaning bath 20-25 KHz. For ultrasonic treatment, when water is used as
a treatment medium, cavitation and agitation are both involved. Temperature affects
the speeds and frequency of ultrasonic waves within a given medium. Generally, at
about a temperature of 73°C, cavitation and frequency of ultrasonic waves within water
begin to deteriorate. It is therefore, desirable to keep the slurry below 73°C.
The ultrasonic waves created in the slurry as it passes through the ultrasound unit
results in breaking the physical bonds of the fine iron ore particles from the particles of
the impurities like alumina (Al2O3), silica (SiO2), phosphorus, gangue (unwanted
materials like clay etc.) etc. After the physical bonds are severed by this ultrasonic
treatment, physical separation using a screw classifier has been found to be highly
effective and the iron ore particles are also found to be cleaned by the ultrasonic
treatment.
The ultrasonic energy breaks the surface tension bonds between mineral particles and
alumina/clay particles and any air bubbles, gels, slime or algae causing particles to
adhere together. This process is called microscopic scrubbing of the particles and it
produces unusually clan particle surfaces, stripped of foreign material and carrying
much less moisture than before.
The invention illustrated herein with the following examples to clearly define the
invention with improved results over the prior arts.

ADVANTAGES OF THE INVENTION
EXAMPLE -1:
A specimen of Naomundi iron ore having raw materials like alumina (AI2O3), silica
(SiO2), phosphorus content of 1.72%, 1.7% and 0.05% by weight, respectively was
taken and sized to +1 mm - 10 mm.
A portion of the specimen was beneficiated with standard screw classifier and
classification process.
Another portion of the specimen was treated with ultrasonic vibration. The slurry
comprised 100 grams of iron ore and 1000 ml of water. In the case of the specimen
treated by ultrasound, the slurry was subject to ultrasonic vibrations of frequency 20-25
KHz for a period of 30 minutes. The power applied to the ultrasound generated was 220
watts/litre. After the ultrasound treatment, the specimen was beneficiated with
standard screw classifier and classification process.
In each instance, the iron ore was separated from the solution and chemically analysed.
The alumina (AI2O3), silica(SiO2), phosphorus content was reduced from 1.72% to
1.12% from 1.7% to 1.34% and from 0.05% to 0.048% by weight, respectively under
room temperature heat and normal pressure, as expected according to the inventive
features of the invention.
The following table A sets forth characteristics of the iron ore compared with the
specimens beneficiated with standard washing proves that is dense medium cyclones
(Gravity separation) process without ultrasonic treatment and the specimens
beneficiated with standard washing proves that is dense medium cyclone (Gravity
Separation) process without ultrasonic treatment.


Hence, the new process described herein was found to be effective, as a pretreatment
process, before standard mineral beneficiation process, at impurities like alumina
(Al2O3), silica (SiO2), phosphorus, gangue (unwanted materials like clay etc.) content
reduction, than the standard iron ore washing process alone.
EXAMPLE -II
An another specimen of Naomundi iron ore was sized and slurried, treated with
ultrasonic vibration substantially and then beneficiated as was specimen of Example I.
A portion of the specimen was beneficiated with standard screw classifier and
classification process.
The following table B sets forth characteristics of the iron ore compared with the
specimens beneficiated with standard washing proves that is dense medium cyclone
(Gravity Separation) process without ultrasonic treatment and the specimens

beneficiated with standard washing proves that is dense medium cyclone (Gravity
Separation) process after ultrasonic treatment.

It should be noted that all analysis presented in this patent specification are based upon
dry specimens.
The specimen treated by ultrasound was treated in a slurry comprising 100 grams of
iron ore per 1 litre of water. In both cases, the iron ore was classified and separated
from other residue. Hence, the new process described herein was found to be effective,
as a pretreatment process, before standard mineral beneficiation process, as impurities
like alumina (AI2O3), silica (SiO2), phosphorus, gangue (unwanted materials like clay
etc.) content reduction, than the iron ore washing process alone.
EXAMPLE - III
A specimen of Joda iron ore was sized to +0.5mm - 10mm and slurried, treated with
ultrasonic vibration substantially and then beneficiated as was specimen of Example I.

Another portion of the specimen was beneficiated with standard screw classifier and
classification process.
The following table C sets for the characteristics of the iron ore compared with the
specimens beneficiated with standard washing proves that is dense medium cyclone
(Gravity Separation) process without ultrasonic treatment and the specimens
beneficiated with standard washing proves that is dense medium cyclone (Gravity
Separation) process after ultrasonic treatment.

The slurry solutions comprise 1 litre of water to which was added 100 grams of sized
iron ore.
The specimen treated with ultrasonic vibration was washed and the iron ore separated
from the residue. The power applied to the ultrasonic vibrator was about 220
watts/litre. This example establishes that even the smaller particle size iron ore had a
good alumina (AI2O3), silica (SiO2), phosphorus reduction.

EXAMPLE-IV
Another specimen of Joda iron ore was sized to +0.5 mm-10 mm and slurried, treated
with ultrasonic vibration substantially and then beneficiated as was specimen of
Example I.
Another portion of the specimen was beneficiated with standard screw classifier and
classification process.
The following table D sets forth characteristics of the iron ore compared with the
specimens beneficiated with standard washing proves that is dense medium cyclone
(Gravity Separation) process without ultrasonic treatment and the specimens
beneficiated with standard washing proves that is dense medium cyclone (Gravity
Separation) process after ultrasonic treatment.

The slurry solutions comprise 1 litre of water to which was added 100 grams of sized
iron ore.

The specimen treated with ultrasonic vibration was washed and beneficiated with
standard screw classifier and classification process after ultrasound treatment. The
power applied to the ultrasonic vibrator was about 220 watts / litre. This example
establishes that even the smaller particle size iron ore had a good alumina (Al2O3),
silica (SiO2), phosphorus reduction.
When iron ore slurry is treated ultrasonically, as described herein, the standard
beneficiation processes are enhanced. More iron ore appears in output even in plain
water that with conventional beneficiation techniques. More iron ore can therefore be
recovered.
Temperature in one of the criteria affecting the speed and frequency of ultrasonic
waves within a given medium. Generally at about a temperature of 73°C cavitation and
frequency of ultrasonic waves within water begins to deteriorate. It is therefore
desirable to maintain the maximum temperature. The slurry is used in this process
below 73°C.
The improved results achieved as herein described are achieved by utilizing pressure of
impulses generated through oscillation of planes of piezo electric plate which impulses
of ultrasound disturb the iron ore molecules connected in many ways to both organic
and inorganic on the basis of improved beneficiation results obtained it is concluded
that on breaking apart the molecular chains of structure some loose ends will remain
actively seeking to form or reform. Thus if an atom of impurities in iron ore tied to a
ferrous molecule is removed, it will leave behind an active site seeking to replace the
"lost" impurities atom.

The invention as herein described and illustrated should not be read in a restrictive
manner as various adaptations, changes and modifications are possible within the scope
and limit of the invention encompassed in the appended claims.

WE CLAIM
1. A process of beneficiation of iron ore like materials by treating their slurries with
high intensity power ultrasound to reduce impurities alumina (AI2O3), silica
(SiO2), phosphorus associated with the ores comprising the steps of :
a) crushing iron ores in size of +2 mm to - 12 mm;
b) combining the iron ore with water to form a slurry and maintaining the said
slurry below 73°C while keeping the said slurry in an ultrasonic cleaning bath;
c) applying ultrasonic pulses to the said slurry in the order of 20KHz - 25KHz
which breaks the physical bonds of the said impurities in the ore materials by
pressure of the impulses of the applied ultrasound;
d) physically separating the said isolated impurities from the ore materials by
using devices such as cyclone separators, spiral separators, vibrating screens
or centrifuge separators and recovering upgraded ores with reduced
impurities
characterised in that the said low frequency generated severe implosive
impact of the cavitation bubbles which in turn broke the bond between
impurities (like alumina, silica , phosphorus etc.) and iron in the iron ore.
2. A process as claimed in claim 1 wherein ultrasound generated by the ultrasound
cell induce cavitation in the liquid produced by transducer acceleration pressures
in the ultrasound cell against the slurry.

3. A process as claimed in the preceding claims wherein ultrasonically induced
cavitation promote physical as well as chemical changes of substances within the
liquid.
4. A process as claimed in claim 4 wherein the microscopic scrubbing effected by
the ultrasound cell breaks apart the atom of impurities in iron ore tied to a
ferrous molecule of the iron ore and leave behind an active site prone to replace
the lost impurities atom during next cycle of compression.
5. A process as claimed in the preceding claims wherein slurry is prepared by
maintaining weight ratio of iron ore to water between 1:10 and 30 minutes of
ultrasonic treatment time.

The present invention relates to a process of beneficiation of iron ore like materials by
treating their slurries with high intensity power ultrasound to reduce impurities alumina
(AI2O3), silica (SiO2), phosphorus associated with the ores comprising the steps of
crushing iron ores in size of +2 mm to -12 mm and combining the iron ore with water
to form a slurry and maintaining the said slurry below 73°C while keeping the said slurry
in an ultrasonic cleaning bath and applying ultrasonic pulses to the said slurry in the
order of 20 KHz to 25 KHz which breaks the physical bonds of the said impurities in the
ore materials by pressure of the impulses of the applied ultrasound and physically
separating the said isolated impurities form the ore materials by using devices such as
cyclone separators; spiral separators, vibrating screens or centrifuge separators and
recovering upgraded ores with reduced impurities characterised in that the said low
frequency generated severe implosive impact of the cavitation bubbles which in turn
broke the bond between impurities (like alumina, silica , phosphorus etc.) and iron in
the iron ore.