TITLE:
A process for making Iron ore pellets.
FIELD OF INVENTION:
This invention relates to a process for making Iron ore pellets.
BACKGROUND OF THE INVENTION:
Impurities in iron ore and also in bentonite, has led to poor quality of pellets. There has
been a huge effort by the steel companies for replacing bentonite with organic binders.
Therefore, large number of naturally occurring and synthetic organic binders has been
investigated against bentonite. Among various organic binders, only three binders sodium
carboxymethylcellulose (NaCMC), corn starch, and sodium acrylate-acrylamide
copolymers, are evaluated industrially. Others, owning to their high cost and poor
binding capacity are not suitable for Industrial scale.
Natural organic binders are products of agricultural, one of the rich renewable raw
materials. More specific, GRNS powder is by-product of ground nut shell. After removal
of ground nut, the shell crushing leads to powder. The major component of powder is

cellulose-hemicellulose (50-60%) and lignin (30%) with small amount of inorganic
metal/metal oxides (1 to 2%) like Al, Si, Ca, Fe, Mg, Mn, Na, K, etc., Presently, bentonite
that is used as inorganic binder for iron ore pellets consists of silicon oxides and
aluminum oxides ((Na2O: 2-2.5%; CaO: 1.5%; MgO: 2.9%; SiO2 55.5%; Al2O3: 17.6%;
Fe2O3: 14.2%; LOI: 1.1%). However, current iron ore pelletization process demands a
reduction in silicon and aluminum impurities. These impurities can be reduced with
replacement and/or blending of the bentonite with organic binders having minimum
amount of silica and alumina. So far. cellulose, starch, and their derivatives, natural gums,
lignosulfonates. etc., have been tried as natural organic binders for iron ore pellets. Three
binders viz. sodium carboxymethylcellulose (NaCMC), corn starch, and sodium acrylate-
acrylamide copolymers, have been tested industrially by the iron ore industry. NaCMC is
derived from cellulose and. involves multi-step process of preparations. It will also add
sodium in pellets. There could be restriction of corn-starch uses since it is isolated from
food sources. Sodium acrylate-acrylamide copolymers are petroleum based and contain
sulfur that gives poor strength to the pellets. Also it is expensive as compared to bentonite.
We have developed, characterized and evaluated the ground nut shell powder organic
binder for iron ore pelletization at TSL. GRNS powder can be used without any chemical
processing, abundantly available and less expensive. GRNS powder has better binding
properties for iron ore pellets as compared to their analogs.

OBJECTS OF THE INVENTION:
An object of this invention is to propose a process for making Iron ore pellets.
Another object of this invention is to propose a process wherein natural product GRNS is
used as a binder.
Further object of this invention is to propose an economical process for making Iron ore
'pellets.
Still another object of this invention is to propose using GRNS powder as a binder which
is free from inorganic impurities has minimum/permissible inorganic impurities.
Further object of this invention is to propose using chemical modified or non-modified
GRNS powder as a binder.
BRIEF DESCRIPTION OF THE INVENTION:
According to this invention there is provided a process for making Iron ore pellets
comprising:
preparing the raw materials,
subjecting the raw materials to the step of green pellet formation, and
hardening the green balls by heating.

BRIEF DESCRIPTION OF THE ACCOMPANING DRAWINGS:
Scheme 1: shows the Molecular structures of ideal organic binder.
Scheme 2: shows the chemical structure of GRNS powder.
Scheme 3: shows the process flow diagram for iron ore pelletization.
Figure 1: shows the green compressive strength of wet pellets with Org binder and
bentonite.
Figure 2: shows the drop number of Green pellets with Org binder and bentonite.
Figure 3: shows the dry compressive strength of Green pellets with Org binder and
bentonite.
Figure 4: shows the cold compressive strength of Indurated pellets with Org binder and
bentonite.
Figure 5: shows the reduction degradation index of Indurated pellets with Org binder and
bentonite.

DETAILED DESCRIPTION OF THE INVENTION:
The invention discloses use of GRNS powder without any chemical modification as
organic binder for iron ore pellets. GRNS powder is obtained from ground nut shell. It
consists of cellulose-hemicellulose and lignin. Further, it is free of inorganic impurities,
in particular sodium, silicon, aluminum, phosphorus and sulfur that are major concerns of
iron ore pelletization. The ground nut shell powder is milled to 45 micron. In the present
invention the GRNS powder is used in the range of 0-0.3% with respect to iron ore along
with bentonite. In a typical preparation of iron pellets, iron ore is sun dried and milled to
attain a size of 45 micron in ball mill. The milled iron ore, GRNS powder, bentonite, and
additives are blended in a cone mixer to achieve homogeneity. The blended mixture is
then fed to the rotating pelletizing disc and water is sprayed on the mixture with the help
of jet spray sprinkle. The iron ore mixture agglomerates with the help of capillary forces
and surface tension to coalesce together to grow into small nuclei particles ultimately
resulting to form the green balls. The disc is rotated with optimum rpm speed at an angle
of 45-55° to obtain sufficiently strong green balls and moisture is maintained around 7-
10%. GRNS powder consisting hydroxyl and polar groups which take part in the binding
of iron ore particles and bentonite, thereby giving good strength to the green balls. The
green balls formed in pelletizing disc are dried at room temperature for two days. These
green balls are directly transferred to muffle furnace. The green balls are fired at 1300°C
for 7 minutes (Figure 1) Examples of differed combination of GRNS powder along with
. bentonite is given in Table 1. It can be seen that the physical and metallurgical properties
of pellets are at par with that of bentonite at different weight percent.

Only three organic binders (CMC based Peridur from AkzoNobel; Base polymer from BASF;
Polymer inorganic salt from Ashland) are available in market, that are effective at lower dosages
levels in combination with bentonite. High cost and availability limit their replacement for
bentonite. We at TCL IC identified naturally occurring organic binders that have good binding
capacity, readily available and comparable cost with bentonite. These binders impart good pellet
quality and hence have good market scope.
Reduction of impurities and improving the quality of iron has been the main focus in the
replacement of bentonite with organic binder. Organic binders are developed from natural or
synthetic polymer. Natural binders are categorized in various groups such as celluloses, lignin,
natural gums, starches, wood related products and its derivatives. The synthetic binders are
derived from petroleum i.e. acrylamides and acrylate polymer. Other sources are from byproducts
of paper processing, dairy wastes, heavy hydrocarbons and tar products.
Experimentation at laboratory scale and for few at industry scale shows that organic binders
should have good wettability, adhesive and cohesive forces and thermal stability. Further, it has
been shown that organic binders with more polar and hydrophilic groups, organic skeletons with

unsaturated hydrocarbon chain (more double and triple bond of carbon-carbon) and ring
aromatics structure (like phenolics) are excellent organic binders. Scheme 1 shows the molecular
structures of the idea! organic binder (Polar and hydrophilic groups include OH, COOH, NH2,
COO'; organic backbone incorporating double covalent bonds and phenol rings).
Based on the concept (scheme 1), several researchers have developed various natural and
synthetic organic binders. But, only three organic binders (CMC based Peridur from AkzoNobel;
Base polymer from BASF; Polymer inorganic salt from Ashland) are available in market for
industrial scale.
We have identified large number of naturally available organic binders having desired functional
groups, organic backbone and phenolics ring. Two binders GRNS powder and sulfur free lignin
were superior and better in terms of binding properties, availability and cost. For comparison,
NaCMC was considered for laboratory studies. Scheme 2 shows the chemical structure of GRNS
powder that mainly consists of cellulose, hemicellulose and lignin. Properties of GRNS powder
and lignin are given in Table 1. The analysis of Na, Al, Si, S and P was done by ICP-AES
method and given in Table 2 (these elements are part of pellets impurities and non-desirous).

Iron ore pelletization with bentonite and organic binder take place in three steps.
1) Preparation of raw materials (drying, grinding, mixing of ore, binder and additives viz.
Organic binder, bentonite limestone and pyroxinite) 2) Green pellets formation in
pelletizing disc 3) Induration of green balls (heat hardening)
Step 1: Preparation of raw materials
Table 3 shows the chemical composition of raw materials used for pelletization. Iron ore
pelletization is achieved by having sufficient fineness and size of raw materials. First iron ore is
sun dried and grinded to attain a size of 45 micron in ball mill. The grinded iron ore, organic
binder and bentonite, and additives arc mixed in cone mixer to achieve a homogenous mixing.


Step 2: Green pellets formation in pelletizing disc
The blended mixture, is fed to the rotating pelletizing disc and water is sprayed on the
mixture with the help of jet spray sprinkler (Laboratory scale plastic bottle with fine
nozzle is used). The iron ore mixture is agglomerated with the help of capillary forces
and surface tension to coalesce together to grow into small nuclei particles ultimately
resulting to form the green balls. The disc is rotated with optimum rpm speed at an angle
of 45-55° to obtain sufficiently strong green balls and moisture is maintained around 7-
10 %. Organic binders contain more hydroxyl and polar groups which can take part in
chemical bonding with iron ore particles and bentonite, thereby giving more strength to
the green balls.
Step 3: Induration of green balls
The green balls formed in pelletizing disc are dried at room temperature for two days.
These green balls are directly transferred to muffle furnace. The green balls are fired at
1300°C for 7 minutes. During heating to 1300 °C, many changes take place in the green
balls. Decomposition of hydrates, carbonates, sulphates and organic binders happens.
Further, oxidation of iron oxide, changes in crystalline structure and slag bonds are
formed which imparts additional strength to green balls. The green balls are cooled and
stored for further use in blast furnace. Scheme 3 shows the process flow diagram for
pelletization with organic binder in combination of bentonite.

The physical and metallurgical properties of green balls and indurated pellets are
measured according to the test listed in Table 4.
Table 4. List of physical and metallurgical test for pellets measured at NML


Abbreviations for Table 5
GCS- Green compressive strength
DCS- Dry compressive strength
CCS- Cold compressive strength
RI- Reduction index
RD1- Reduction degradation index Basicity- Ratio of CaO.MgO/SiO2.Al2O3
GRNS- Ground nut shell powder
CMC- sodium carboxyl methyl cellulose

WE CLAIM:
1. A process for making Iron ore pellets comprising:
preparing the raw materials,
subjecting the raw materials to the step of green pellet formation, and
hardening the green balls by heating.
2. The process as claimed in claim 1, wherein the said step of preparing the raw materials
includes drying of iron ore,
crushing the grinding of iron ore,
mixing of ore, binder and additives in a cone mixer.
3. The process as claimed in claim 1, wherein the step of green pellet formation is
performed by rotating the blended mixture on a pelletizing disc,
spraying water on the mixture using a jet spray sprinkler,
subjecting the iron ore mixture to the step of agglomeration to form the green balls,
rotating the disc at an optimum speed at an angle of 45-55° to obtain strong green balls,
maintaining the moisture around 7-10%.
4. The process as claimed in claim 1, wherein the said green balls are dried and then
transferred to muffle furnace and are fired at 1300°C for 7 minutes.

5. The process as claimed in claim 1, wherein the said raw materials comprises of iron
ore, binder and additive.
6. The process as claimed in claim 1, wherein the said binder and additive includes 0.1 to
0.3% of ground nut shell powder (GRNS), lignin and bentonite.
7. The process as claimed in claim 1, wherein 0.2% of only GRNS powder as binder also
gave acceptable physical and metallurgical test.
8. The process as claimed in claim 1, wherein GRNS powder and lignin each 0.1% with
0.2% of bentonite gave very good test results.
9. A process according to claim 1, where in one of the raw material, GRNS can be added
as a binder along with other flux material and inorganic additives such as CaCO3 etc.

10. A process according to claim 1 in which in one of the raw material, GRNS is a
biopolymer of 25-35% lignin, 35% cellulose and 18-20% hemicellulose
11. A process according to claim 1 in which one of the raw material, GRNS is a
biopolymer having a polar groups, hydrophilic groups, aromatic rings, carbon-carbon
double covalent bonds, carbon carbon triple covalent bonds, hydrocarbon branched

12. A process according to claim 1 in which one of the raw material, GRNS particles size
are below 100 micron.
13. A process according to claim 1 in which one of the raw material of at least 80% by
weight of the GRNS has particle size are below 50 micron.
14. A process according to claim 1 in which one of the raw material, GRNS comprises
0.1 to 10% by weight water having a particle size below 100 micron.
15. The process according to claim 1, where in one of the raw material, GRNS can be
added at 0.1 to 0.3% along with any other organic binder such as lignin, CMC, Karaya
gum, gelatin, in combination thereof as a binder.
16. A process according to claim 1 in which one of the raw material, lignin is selected
from sulfur-free process comprises with abundantly aromatic compounds, polar groups
and hydrophilic groups.
17. A process according to claim 1 in which one of the raw material, lignin comprises 0.1
to 10% by weight water having a particle size below 100 micron.

18. The process according to claim 1, where in one of the raw material, GRNS can be
added more than 0.4% where in reduction in silica and alumina in slag.
19. The process according to claim 1, where in one of the raw material, GRNS is a
natural biomass comprises carbon, hydrogen and oxygen atom having high molecular
weight formula.
20. The process according to claim 1, where in one of the raw material, GRNS biomass
used in reduction of coke coal.
21. The process according to claim 1, where in one of the raw material, GRNS biomass
combustion in the range of 300-1000 0C thereby generating energy in induration.
22. The process as claimed in claim 6, where in GRNS biomass obtained from ground nut
shell is a rich agriculture source which comprise less than 100 ppm aluminum and silicon
element.