FIELD OF INVENTION
The present invention relates to a process for producing high grade blast furnace feed
from poor grade iron ore ultra fines. More particularly, the invention relates to a process
of separation of iron bearing minerals from gangue minerals contained in ultra fines by
selective dispersion and selective flocculation process.
BACKGROUND AND PRIOR ART OF THE INVENTION
Large quantities of ultra fines are generated during mining and washing of iron ores. At
present 11 million tons of these ultra fines have accumulated at various slime ponds.
Ultra fines contain iron with high alumina and silica generated in the iron ore mines and
the iron ore washing plants. These materials contain iron bearing minerals namely
hematite, goethite and magnetite and the gangue materials composing of mostly clay
and other alumina silicates. The fine grained clay mineral poses difficulties in
beneficiation of these off grade fines to make it suitable for blast furnace feed, because
the fines generated in the iron ore mines and also in the iron ore washing plants do not
satisfy the stringent specifications of raw materials to be fed into the blast furnace or in
any other iron making processes.

The prior art discloses process of separation among different metal oxides of iron,
aluminium and silicon where these oxide exist in different forms.
Therefore there exists a need to produce quality raw materials from the ultra fines to
make it suitable for blast furnace feed which will be of great economical significance by
separating iron minerals from alumina and silica contained in ultra fines.
OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose a process for producing high grade
blast furnace feed from poor grade iron ore ultra fines which is capable of separating
iron minerals from alumina and silica present in ultra fines to use as blast furnace feed.
Another object of the invention is to propose a process for producing high grade blast
furnace feed from poor grade iron ore ultra fines which makes it environmental friendly
with zero waste.
Yet another object of the invention is to propose a process for producing high grade
blast furnace feed from poor grade iron ore ultra fines which is capable of separating
iron values from ultra fines that qualifies for blast furnace feed having less than 2%
alumina and silica.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig. 1 - shows a flow chart describing the process according to invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
According to the invention, a process has been developed for producing concentrate
containing very high iron with very low alumina and silica from the ultra fines containing
high alumina and silica generated in the iron ore mines and the iron ore washing plants.
In this process, alumina and silica are selectively dispersed whereas the iron bearing
minerals are selectively flocculated under specific conditions. The final product contains
more than 68 % Fe with only around 1% alumina and 1% silica from the ultra fines
containing around 54% Fe, 7.89% alumina and 7.78% silica, separating iron value from
ultra fines. The tailings generated in this process can be utilized as building materials.
This process is environmental friendly with zero waste.
Quality of the raw materials for the iron and steel industries plays an important role in
the down stream processes. The fines generated in the iron ore mines and also in the
iron ore washing plants do not satisfy the stringent specifications of raw materials to be
fed into the blast furnace. It is therefore necessary to beneficiate these off grade fines
to make it suitable for blast furnace feed. In the process of upgrading this ultra fines,
with low gangue minerals containing low

alumina and silica which would be suitable raw materials to be feed into the blast
furnace. At the same time some part becomes rich in gangue materials containing high
silica and alumina which may be useful for making building materials. The fine grained
clay mineral poses difficulties in beneficiation Selective dispersion followed by selective
flocculation has been considered to be the most suitable beneficiation process for these
materials due to the fineness of the materials. The characterization studies of these
ultra fines show that the particles are mostly below 35 micron and the major
constituents are iron oxide, alumina, silica, alumina-silicates and iron-alumina silicates.
Since the surface charge on the gangue minerals (silica and alumina-silicates) are quite
different from that on iron oxide, at a particular pH, separation between iron bearing
minerals and the gangue minerals can be done on the basis of surface charge
conditions. In addition to the above consideration, a starch flocculant can be used to
selectively agglomerate the iron bearing minerals leaving gangue
minerals in the dispersed phase.
In the present invention suitable flocculation process has been developed on different
grades of slime material. The concentrate will be useful feed material for iron making
through blast furnace route where as tailing will be suitable feed material to
manufacture building material.
The difference in surface charge of the iron bearing minerals and the gangue minerals
has been utilized first to separate out some part of the gangue minerals present in the
ultra fines. In the second stage, the materials from the first stage

have been subjected to the selective flocculation by using modified starch. By this
process, value added products, the concentrate becomes the raw material for blast
furnace and the tailing containing high alumina and silica becomes building materials.
As shown in figure 1, ultra fines are subjected to selective dispersion process which
separates tailings with higher alumina and silica from settled material comprising mainly
of iron with some tailings. This is then subjected to re-dispersing process with non
selective dispersant. In the next stage, the materials from the first stage is subjected to
a selective flocculation by a flocculating agent like modified starch which separate out
iron rich concentrate from further left out gangue materials of clay, alumina and silica
which goes out to tailing already collected. Now this concentrate of iron can be used
for blast furnace feed. The gangue materials containing high silica and alumina thus
separated can be used for building material so that no wastage results out of the
process.
The advantages of the process over prior art are:
1. Separation takes place among compounds of iron oxides, alumina and
silica existing in ultra fines in various forms.
2. The final product containing 68% Fe with only around 1% alumina and
1% silica from the ultra fines is qualified as blast furnace feed or in any iron
making processses. More than 2% of alumina and silica disqualifies the product
as blast furnace feed.

Iron containing ultra fines is the mixture of Fe, Si,AI oxide with different particle size.
The particle size of ultra fines is in the range of 100 micron to 100 nm. Both the
alumina and silica levels in ultra fines are in the range of 3 to 8 wt.%.
The dispersant used includes selective and non-selective dispersant with different
dosage. The selective dispersant includes polymer of 5000 to 10,000 molecular weight.
The non-selective dispersant includes sodium silicate and sodium hexameta phosphate.
The dosage of dispersant is in the range of 20 to 10,000 ppm. The flocculants includes
different starch solution with varied dosage in the range of 20 - 10,000 ppm. The
starch includes potato, wheat and maize while the starch solution used is plain as well
as caustic starch solution with starch concentration in the range of 0.1 to 10 wt%. The
process is feasible under varied pH condition when the range of pH is 2.5 to 11 with a
preferred pH range as 8-10. The concentration of ultra fines in this process is in the
range of 2 to 25 wt% . The settling time of the process also varies from 10 seconds to
20 hours. The method of mixing is carried out either by magnetic stirring, mechanical
stirring or mixing the ultra fines in solution using ultra sound. The solvent includes tap
water, distilled water, double distilled water.
By this process of selective dispersion and selective flocculation, the alumina and silica
levels in concentrate iron has been dropped down to a level of 1 whereas both the
alumina and silica level in tailing can be up to 14 wt.%.
From the present invention, various grades of rejected ultra fines can be separated out
into two (1) iron rich concentrate and (ii) tailing (with rich in

alumina and silica) by selective dispersion and selective flocculation process. The
concentrate is most suited feed material for iron making through blast furnace rout
whereas the tailing is the most suited feed material to make building material. Added
advantage is that this process is environmental and eco friendly with zero waste.
Movement of different particles of oxide mineral in solution depends on degree of
surface charge/zeta potential of those particles. Particles are expected to be coagulated
or settled if surface charge/zeta potential becomes zero. Surface charge/zeta potential
characteristics of iron bearing minerals (hematite, goethite and magnetite) are quite
different from clay minerals (alumina and silica) under different conditions. This
variation can be shortened or extended by varying pH and using different chemicals.
Using all this conditions alumina level in rejected ultra fines can be dropped down to 4.
This material is unsuitable as feed material for operation of blast furnace.
In this present invention, the dispersants are selectively adsorbed into the gangue
minerals due to which the gangue particles can be separated in dispersed phase and on
the other hand long chain flocculant selectively adsorbed into the iron bearing mineral
particles through chemisorptions and form flocs. Hence, the finer particles of iron oxide,
alumina and silica obtained from hydro cyclone process are subjected to selective
flocculation to get a final product that contains 68% Fe, around 1% alumina and 1%
silica that qualifies as blast furnace feed or in any iron making process.

WE CLAIM:
1. A process for producing high grade blast furnace feed from poor grade iron ore ultra
fines comprising:
processing ultra fines by selective dispersion to separate gangue materials
from settled material iron;
processing settled material of iron by re-dispersing with non selective
dispersent;
processing dispersed settled material by selective flocculation with modified
starch to separate concentrate iron for blast furnace feed from tailings
leaving the gangue minerals in the dispersed phase;
characterized in that the process of separation between iron bearing
minerals and the gangue minerals is carried on the basis of surface charge
conditions at a particular pH during re-dispersing with non-selective
dispersant and segregating the finer particles by hydro cyclone process for
better flocculation to produce the final product that contains 68% Fe, 1%
alumina and 1% silica.
2. A process as claimed in claim 1 wherein the selective dispersant is a polymer of
5000 to 10,000 molecular weight and the non-selective dispersant includes sodium
silicate and sodium hexameta phosphate wherein the dosage of said dispersant is in
the range of 20 to 10,000 ppm.
3. A process as claimed in claim 1, wherein the dosage of flocculants is in the range of
20 to 10,000 ppm that includes starch solution having starch concentration in the
range of 0.1 to 10 wt%.

4. A process as claimed in claim 1 wherein the starch includes potato, wheat and
maize and the starch solution is plain as well as caustic starch solution having starch
concentration in the range of 0.1 to 10 wt.%.
5. A process as claimed in claim 1 wherein preferable pH range is 8-10.
6. A process as claimed in claim 1, wherein the concentration of ultra fines in solution
is in the range of 2 to 25 wt%.
7. A process as claimed in claim 1, wherein the settling time is in the range of 10
seconds to 20 hours.
8. A process as claimed in claim 1, wherein the mixing process comprises magnetic
stirring, mechanical stirring or mixing the ultra fines in solution using ultra sound.
9. A process as claimed in claim 1, wherein the solvent is tap water, distilled water and
double distilled water.

A process for producing high grade blast furnace feed from poor grade iron ore ultra fines consists of processing ultra fines by selective dispersion to separate gangue materials from settled material iron and processing settled material of iron by re-dispersing with non-selective dispersant. The dispersed settled material is then processed by selective flocculation with modified starch to separate concentrate iron for blast furnace feed from tailings leaving the gangue minerals in the dispersed phase. The process of separation between iron bearing minerals and the gangue minerals is carried out on the basis of surface charge conditions at a particular pH during re-
dispersing with non-selective dispersant and segregating the finer particles by hydro- cyclone process for better flocculation to produce the final product that contains 68%
Fe, 1% alumina and 1% silica.