DESC:FIELD OF THE DISCLOSURE
The present disclosure relates to bentonite product and a process for its preparation.
BACKGROUND
Bentonite (montmorillonite) is an aluminum phyllosilicate comprising aluminum octahedral and silica tetrahedral sheets. The space between the aluminum and silica sheets is occupied by exchangeable cations such as Mg2+, Ca2+, Na+, K+ and Li+. Bentonite clay demonstrates varying physical properties which are governed by its chemical composition and morphological features. The chemical composition and morphological features of bentonite depend on the physical and chemical changes in the environment where bentonite deposits are found.
The distinctive properties of bentonite such as binding ability, thixotropy, swelling and absorption make bentonite a valuable material for a wide range of applications and uses. Bentonite is used as a binding agent for the preparation of iron-ore pellets and castings.
Bentonite is preferred in the iron-ore pelletizing process due its superior thermal stability. For preparing iron ore pellets, the iron mineral dust is mixed with bentonite along with water and other ingredients such as dolomite or lime, in small quantities. Conventionally, the pellet contains 0.7 to 1.5 weight % of bentonite. The iron-ore pellets are used in the direct reduction process. However, the direct reduction process produces large amounts of slag as a byproduct, which is to be disposed. The disposal of large amounts of slag is a cumbersome affair for the steel industries. Therefore, reducing slag production during direct reduction process is desired in the steel industries. It is envisaged that improving binding ability of bentonite will reduce the amount of bentonite needed for the preparation of iron ore pellets, which in turn will lead to reduced slag production.
Therefore, there exists a need for providing bentonite with improved properties particularly improved binding ability.

DEFINITION
The term “iron ore pellet” in the context of the present disclosure refers to a shaped solid material comprising iron ore as main ingredient.
The term “Green Compressive Strength” in the context of the present disclosure refers to the strength of moist iron-ore pellets which is measured as the maximum load applied to the moist iron-ore pellets under pre-determined conditions before the iron-ore pellet is crushed.
The term “Dry Compressive Strength” in the context of the present disclosure refers to the strength of iron-ore pellets dried at 110oC for 2 hours which is measured as the maximum load applied to the dried iron-ore pellets under pre-determined conditions before the dried iron-ore pellet is crushed.
The term “Drop Number of green pellets” in the context of the present disclosure refers to the ability of iron-ore pellets to withstand the drops encountered at conveyor belt transfer points during conveying iron-ore green pellets from balling section to induration grate. The Drop number of green pellets is measured by dropping 20 green pellets onto a steel plate from a height of 457 mm (18 inches) until the green pellets develop cracks or crumble. The number of drops each pellet can withstand is measured and the average of 20 green pellets is taken as drop number.

OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
It is an object of the present disclosure to provide a bentonite composition having improved binding properties.
Another object of the present disclosure is to provide a bentonite composition with improved properties that include but are not limited to binding, gelling and thixotropy.
Still another object of the present disclosure is to provide a process for the preparation of the bentonite composition.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which is not intended to limit the scope of the present disclosure.
SUMMARY
In one aspect of the present disclosure there is provided a binder composition for the iron-ore pelletization process. The composition comprising on a dry basis:
a) alkalinized bentonite, wherein the amount of the alkalinized bentonite ranges from 99 to 99.99 weight %; and
b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
The alkalinized bentonite is obtained by reacting bentonite with at least one alkali selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate. The bentonite is at least one selected from the group consisting of sodium bentonite and calcium bentonite.
The polymer is at least one selected from the group consisting of hydroxylethyl cellulose, carboxymethyl cellulose, acrylamide, polypropylene and derivatives thereof.
The marsh funnel viscocity of the composition is in the range from 51 to 70 seconds. The zeta potential of the composition is in the range from -36 to -18 mV.
In another aspect of the present disclosure there is provided a process for the preparation of a binder composition for the iron-ore pelletization process. The process involves the steps of:
a) reacting bentonite with an aqueous alkali solution to obtain alkalinized bentonite;
b) partially drying the alkalinized bentonite to obtain a mass having a pre-determined moisture content;
c) mixing the mass with at least one polymer to obtain the binder composition; and
d) optionally, milling the binder composition to obtain the binder composition in the form of powder.
The alkali is at least one selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate.
The aqueous alkali solution is obtained by dissolving alkali in water; wherein the amount of the alkali ranges from 0.5 to 5.0% of the weight of bentonite.
The pre-determined moisture content of the mass is in the range from 9 to 25% of the total weight.
The binder composition having moisture content in the range from 9 to 14% of the total weight is subjected to milling. The particle size of the binder composition in the powder form is in the range from 5 to 100 micron.
The binder composition can be partially dried to obtain the binder composition having moisture content in the range from 9 to 14% of the total weight.
In yet another aspect of the present disclosure there is provided a pellet comprising an iron ore, a binder composition and at least one additive; wherein the amount of the iron ore ranges from 90 to 95 weight %, the amount of binder composition ranges from 0.05 to 2 weight % on dry basis, and the amount of additive/s ranges from 4 to 8 weight %.
The iron ore is at least one selected from the group comprising of hematite and magnetite. The pellet is formed using the binder composition of the present disclosure. The binder composition comprising on a dry basis:
(a) alkalinized bentonite, wherein the amount of alkalinized bentonite ranges from 99 to 99.99 weight %; and
(b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
The additive is at least one selected from the group consisting of dolomite, lime and charcoal.
It is found that the amount of the binder composition of the present disclosure needed to obtain pellets of requisite green drop number, green compressive strength and dry compressive strength is less as compared to the amount of bentonite needed to obtain a pellet of similar characteristics.
Pellets are prepared using at least one iron ore selected from the group consisting of hematite ore and magnetite ore and using the binder composition of the present disclosure as a binding agent. The pellets are evaluated for green drop number, green compressive strength and dry compressive strength. The pellets show desired properties.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present disclosure will now be described with the help of the accompanying drawings, in which:
Figure 1 illustrates a process flow chart for preparing the composition of the present disclosure;
Figure 2 depicts a graph related to the green drop number of iron-ore pellets prepared using varying amount of two binders: bentonite and the composition of the present disclosure;
Figure 3 depicts a graph related to the green compressive strength (GCS) of iron ore pellets prepared using varying amount of two binders: bentonite and the composition of the present disclosure;
Figure 4 depicts a graph related to the dry compressive strength (DCS) of iron ore pellets prepared by using varying amount of two binders: bentonite and the composition of the present disclosure;
Figure 5 depicts a graph related to the green drop number of the pellets prepared using an iron ore (hematite ore and magnetite ore) with various amounts of the composition of the present disclosure as a binding agent;
Figure 6 depicts a graph related to the green crush strength of the pellets prepared using an iron ore (hematite ore and magnetite ore) with various amounts of the composition of the present disclosure as a binding agent; and
Figure 7 depicts a graph related to the dry crush strength of the pellets prepared using an iron ore (hematite ore and magnetite ore) with various amounts of the composition of the present disclosure as a binding agent.
DETAILED DESCRIPTION
In one aspect of the present disclosure there is provided a binder composition for the iron-ore pelletization process. The composition comprising on a dry basis:
a) alkalinized bentonite, wherein the amount of the alkalinized bentonite ranges from 99 to 99.99 weight %; and
b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
The alkalinized bentonite is obtained by reacting bentonite with at least one alkali selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate.
In accordance with one embodiment of the present disclosure, the alkali is sodium carbonate.
Bentonite is at least one selected from the group consisting of sodium bentonite and calcium bentonite.
In accordance with one embodiment of the present disclosure, bentonite is a mixture of sodium bentonite and calcium bentonite.
The polymer is at least one selected from the group consisting of hydroxylethyl cellulose, carboxymethyl cellulose, acrylamide, polypropylene and derivatives thereof.
In accordance with one embodiment of the present disclosure, the polymer is hydroxylethyl cellulose.
In accordance with one embodiment of the present disclosure, the amount of hydroxylethyl cellulose is 0.075 weight %.
Physical properties of bentonite are altered due to surface modification by the polymer. The binder composition has improved properties that include but are not limited to binding, gelling and thixotropy. Due to improved binding, the pellets prepared using the binder composition of the present disclosure have increased strength. Further, reduced amount of binder composition is needed to obtain pellets of required strength. Therefore, these pellets produce reduced amount of slag during the direct reduction process.
The composition of the present disclosure is characterized by the following features:
i) The marsh funnel viscocity of the composition is in the range from 51 to 70 seconds.
ii) The zeta potential of the composition is in the range from -36 to -18 mV.
In another aspect of the present disclosure there is provided a process for the preparation of a binder composition for the iron-ore pelletization process. The process involves the following steps:
a) reacting bentonite with an aqueous alkali solution to obtain alkalinized bentonite;
b) partially drying the alkalinized bentonite to obtain a mass having a pre-determined moisture content;
c) mixing the mass with at least one polymer to obtain the binder composition; and
d) optionally, milling the binder composition to obtain the binder composition in the form of powder.
An illustrative embodiment of the process for the preparation of the binder composition of the present disclosure is described as a process flow chart in Figure-1.
The alkali is at least one selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate.
In accordance with one embodiment of the present disclosure, the alkali is sodium carbonate.
The aqueous alkali solution is obtained by dissolving alkali in water. The amount of the alkali used for preparation of the aqueous alkali solution ranges from 0.5 to 5.0% of the weight of bentonite.
In accordance with one embodiment of the present disclosure, the amount of the alkali used for preparation of the solution is 2.5% of the weight of bentonite and the amount of water is 40% of the weight of bentonite.
Bentonite used for preparation of the composition may have high moisture content. Usually, the moisture content of bentonite obtained from commercial source is in the range from 20 to 40 weight%. The moisture content is reduced to requisite level by drying.
The pre-determined moisture content of the mass is in the range from 9 to 25% of the total weight.
In accordance with one embodiment of the present disclosure, the process step of partially drying is carried out to obtain mass having the pre-determined moisture content in the range from 19 to 23% of the total weight.
The binder composition obtained by mixing the mass having the pre-determined moisture content in the range from 19 to 23% of the total weight with at least one polymer, can be partially dried to obtain the binder composition having moisture content in the range from 9 to 14% of the total weight.
Higher amount of moisture in the binder composition hinders the process of milling. The moisture content of the binder composition is reduced in order to carry out milling so as to obtain the binder composition in the form of powder.
In accordance with one embodiment of the present disclosure, the binder composition having moisture content in the range from 9 to 14% of the total weight is subjected to milling. The particle size of the binder composition in the powder form is in the range from 5 to 100 micron.
The binder composition can be partially dried to obtain the binder composition having moisture content in the range from 9 to 14% of the total weight.
The binder composition of the present disclosure demonstrates improved binding, gelling and thixotropic properties. The binder composition is capable of being used in a wide range of applications including but not limited to a binding agent in the iron-ore pelletizing process and castings.
In yet another aspect of the present disclosure there is provided a pellet comprising an iron ore, a binder composition and at least one additive; wherein the amount of the iron ore ranges from 90 to 95 weight %, the amount of binder composition ranges from 0.05 to 2 weight % on dry basis, and the amount of additive/s ranges from 4 to 8 weight %.
The iron ore is at least one selected from the group comprising hematite and magnetite.
In accordance with one embodiment of the present disclosure, the iron ore is hematite.
In accordance with another embodiment of the present disclosure, the iron ore is magnetite.
In accordance with another embodiment of the present disclosure, the amount of binder composition is 0.7 weight % on dry basis, of the total weight of the pellet.
The binder composition used for the preparation of the pellet contains on a dry basis: (a) alkalinized bentonite, wherein the amount of alkalinized bentonite ranges from 99 to 99.99 weight %; and (b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
The additive is at least one selected from a group consisting of dolomite, lime and charcoal. Other additives of similar nature, known in the art, can also be used for the preparation of pallet.
In accordance with one embodiment of the present disclosure, the additive is lime.
The properties of the pellets are evaluated by green drop number, green compressive strength and dry compressive strength. The pellets prepared using the binder composition of the present disclosure, are found to have higher strength as compared to those prepared using bentonite.
Further, it is found that the amount of the binder composition of the present disclosure needed to obtain a pellet of requisite strength is less as compared to the amount of bentonite needed to obtain a pellet of similar strength. The strength of pellet is evaluated by green drop number, green compressive strength and dry compressive strength. The results are shown in Figures 2, 3 and 4.
The reduction in amount of the binder composition required during the pelletization preparation eventually leads to reduced amount of silica in the iron ore pellets, thereby reducing the amount of slag produced in the direct reduction process. Thus, use of the binder composition of the present disclosure during the iron ore pelletization process leads to a reduced amount of slag formation during direct reduction process.
Pellets are prepared with an iron ore (either hematite ore or magnetite ore) using the binder composition of the present disclosure as binding agent. The pellets are evaluated for green drop number, green compressive strength and dry compressive strength. The pellets show desired properties. The results are shown in Figures 5, 6 and 7.
The present invention is further illustrated by way of the following non-limiting examples.
Example 1:
Preparation of the binder composition
2.5 Kg of sodium carbonate was dissolved in 40 L water to form a solution. The sodium carbonate solution was mixed with 100 Kg bentonite and the mixture was allowed to stand for 24hours. The resulting alkalinized bentonite was dried till the moisture content of the mixture reached 14%. 0.075Kg hydroxyethyl cellulose was added to the alkalinized bentonite and mixed uniformly. The binder composition was milled to provide powder having particle size in the range from 5 to 100 micron.
The chemical analysis of the binder composition is provided in Table 1.

Table 1: Chemical analysis of the binder composition
Properties Components Composition
(Polygel SP-200)
Mineralogy
Montmorillonite (Active Clay Content) > 84 %
Chemical Analysis (%)
SiO2 50 - 52
Al2O3 15 - 17
Fe2O3 14 - 16
TiO2 2 - 3
CaO 1 - 2
MgO 2 - 3
Na2O 2 - 3
K2O 0.1 – 0.5
SO3 0.1 – 0.2
LOI 7 - 8
Polymer Hydroxyethyl cellulose 0.075%
- Moisture 12 – 14%

The physical properties of the binder composition are provided in Table 2.

Table 2: Physical properties of the binder composition
Physical Property Composition
(Polygel SP-200)
pH 9 – 10
Free Swelling Value > 30 ml
Methylene Blue Value > 420 mg / g
Plate Water Absorption > 675 %
Marsh funnel viscocity (sec.@ 1000ml)
58.8
Zeta potential (mV) -21.0
Total CEC (cation exchange capacity) > 90 meq/100gm
Following experiments were carried out to evaluate properties of the binder composition.
Example 2:
Determination of viscocity
a) Determination of marsh funnel viscocity
A slurry was prepared using 112.5g of bentonite in 1637.5 mL water and the freshly prepared slurry was charged to a marsh funnel. The slurry runs down through a fixed orifice at end of the stem of the marsh funnel and collects in a graduated vessel. The time taken to collect 1000mL of the slurry in the vessel was noted.
Similarly, marsh funnel viscocity for the binder composition of the present disclosure was determined.
The marsh funnel viscosity of bentonite and the binder composition prepared using different amounts of the hydroxyethylcellulose (HEC) are mentioned in Table 3.
Table 3: Marsh funnel viscosity of bentonite and the binder composition
Sr. No. Sample Details Marsh funnel viscosity (sec.@ 1000ml)

1 Bentonite clay without polymer 47.36
2 Bentonite clay + 0.02% HEC 52.12
3 Bentonite clay + 0.04% HEC 56.37
4 Bentonite clay + 0.06% HEC 57.14
5 Bentonite clay + 0.08% HEC 59.88
6 Bentonite clay + 0.1% HEC 63
HEC: Hydroxyethyl cellulose
It is found that the marsh funnel viscosity increased with increasing the amount of HEC in the binder composition.
b) Determination of fann viscocity
A slurry was prepared using 22.5g of bentonite in 350 mL water. 350 mL of the freshly prepared slurry was charged to stainless steel sample cup of viscometer. Desired speed was selected, stirring was started and the sheer stress value was noted. Experiment was carried out at a speed of 300rpm and 600 rpm.
Similarly, fann viscocity for the binder composition of the present disclosure was determined.
The fann viscosity of bentonite and the binder composition prepared using different amounts of the HEC are mentioned in Table 4.
Table 4: Fann viscosity of the binder composition
Sr. No. Sample Details Fann Viscosity
600 300
1 Bentonite clay without polymer 59 47
2 Bentonite clay + 0.02% HEC 64 60
3 Bentonite clay + 0.04% HEC 66 61
4 Bentonite clay + 0.06% HEC 66 63
5 Bentonite clay + 0.08% HEC 67 64
6 Bentonite clay + 0.1% HEC 68 67
HEC: Hydroxyethyl cellulose
It is found that the fann viscosity increased with increasing the amount of HEC in the binder composition.
An increase in the viscocity of the binder composition leads to an increase in the binding, gelling and thixotropy. Improved binding provides pellets having improved strength.
Example 3:
Determination of surface charge
Zeta potential is a measure of the magnitude of the electrostatic or charge repulsion/attraction between particles, and is one of the fundamental parameters known to affect stability. The zeta potential was determined using Malvern Zeta potential analyser.
The surface charge of bentonite and the binder composition prepared using different amounts of the HEC are mentioned in Table 5.
Table 5: Surface charge of the binder composition
Sr. No. Sample Details Zeta potential (mV)
1 Bentonite clay without polymer -36.5
2 Bentonite clay + 0.02% HEC -21.5
3 Bentonite clay + 0.04% HEC -20.1
4 Bentonite clay + 0.06% HEC -21.5
5 Bentonite clay + 0.08% HEC -20.6
6 Bentonite clay + 0.1% HEC -33.5
HEC: Hydroxyethyl cellulose
It is found that the zeta potential increased substantially with increasing the amount of HEC in the binder composition from 0.02 to 0.08%. However, the binder composition containing 0.1% HEC showed an increment of a value lower than that obtained with binder compositions using 0.02 to 0.08% of HEC.
The charge modification enhances the biding of the composition to the iron ore. The improved binding leads to pellets having improved strength.
Example 4:
Determination of free swelling volume
2g of dried bentonite was charged in two separate measuring cylinders. Water was added to first measuring cylinders to make the total volume 100mL. Kerosene was added to the second measuring cylinder to make the total volume 100mL. The content was allowed to stand for 24 hours and free swelling volume was calculated.
Similarly, free swelling volume for the binder composition of the present disclosure was determined.
The free swelling volume of bentonite and the binder composition prepared using different amounts of the polymer are mentioned in Table 6.
Table 6: Free swelling volume of the binder composition
Sr. No. Sample Details Free Swelling Volume (ml)
1 Bentonite clay without polymer 29
2 Bentonite clay + 0.02% HEC 30
3 Bentonite clay + 0.04% HEC 30
4 Bentonite clay + 0.06% HEC 30
5 Bentonite clay + 0.08% HEC 29
6 Bentonite clay + 0.1% HEC 29
HEC: hydroxyethyl cellulose
It is found that the free swelling volume did not change with increasing amount of the HEC in the binder composition.
Example 5:
Plate water absorption test
The plate water absorbance (PWA) test measures the amount of water that bentonite can absorb. 2g pulverized bentonite was placed on a filter paper which is then placed on a partially submerged sintered alumina plate in a closed container containing water. The amount of water absorbed by bentonite over 16 hours was determined.
Similarly, plate water absorption for the binder composition of the present disclosure was determined.
The plate water absorption test of bentonite and the binder composition prepared using different amounts of the polymer are mentioned in Table 7.
Table 7: Plate water absorption of the binder composition
Sr. No. Sample Details Plate Water absorption (%)
1 Bentonite clay without polymer 625
2 Bentonite clay + 0.02% HEC 626
3 Bentonite clay + 0.04% HEC 626
4 Bentonite clay + 0.06% HEC 622
5 Bentonite clay + 0.08% HEC 612
6 Bentonite clay + 0.1% HEC 615
HEC: hydroxyethyl cellulose
It is found that the plate water absorption did not change with increasing amount of HEC in the binder composition.
Example 6:
Characterization of iron ore pellet using the binder composition of the present disclosure.
Iron ore pellets were prepared using 92.3g iron ore, 7.0g lime and 0.7g bentonite. Similarly, pellets were prepared using 0.7% amount of the binder composition prepared in example 1.
Pellets are prepared using either the binder composition or bentonite as a binding agent. Properties of the pellets were evaluated.
The comparison of green drop number of the pellets prepared using various amounts of the binder composition with those prepared using bentonite are shown in Figure 2. It is observed that the amount of the binder composition needed to prepare a pellet of desired green drop number is less as compared to the amount of bentonite needed to prepare a pellet of similar green drop number.
The comparison of green crush strength of the pellets prepared using various amounts of the binder composition with those prepared using bentonite is shown in Figure 3. It is observed that the amount of binder composition needed to prepare a pellet of desired green crush strength is less as compared to the amount of bentonite needed to prepare a pellet of similar green crush strength.
The comparison of dry crush strength of the pellets prepared using various amounts of the binder composition with those prepared using bentonite is shown in Figure 4. It is observed that the amount of binder composition needed to prepare a pellet of desired dry crush strength is less as compared to the amount of bentonite needed to prepare a pellet of similar dry crush strength.
The green drop number of the pellets prepared using hematite ore or magnetite ore and various amounts of the binder composition of the present disclosure is shown in Figure 5.
The green crush strength of the pellets prepared using hematite ore or magnetite ore and various amounts of the binder composition of the present disclosure is shown in Figure 6.
The dry crush strength of the pellets prepared using hematite ore or magnetite ore and various amounts of the binder composition of the present disclosure is shown in Figure 7.
Pellets of desired green drop number, green crush strength and dry crush strength are obtained for hematite ore or magnetite ore using the binder composition of the present disclosure.
TECHNICAL ADVANCEMENTS:
The present disclosure, related to a binder composition and a process for the preparation thereof has the following technical advancements, including but not limited to the realization of:
1. The binder composition of the present disclosure has improved properties including but not limited to binding, gelling and thixotropy.
2. A process for the preparation of the binder composition is simple. The process can be implemented on commercial scale.
3. The amount of binder composition needed as a binding agent in the iron-ore pelletizing process is relatively less as compared to the process using bentonite.
4. The composition provides improved strength to the pellets with lower bentonite dosage. The pellets have higher green drop number, green crushing strength and dry crushing strength.
5. The reduced amount of the bentonite in iron ore pellet results in reduced slag formation during ore melting process.
6. The polymer decomposes at a temperature of 400-5000C. The decomposed polymer does not leave residue resulting in the formation of pores in the pellet, which in turn improves permeability during firing at higher temperature.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the invention as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:1. A binder composition for the iron-ore pelletization process; said composition comprising on a dry basis:
a) alkalinized bentonite, wherein the amount of the alkalinized bentonite ranges from 99 to 99.99 weight %; and
b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
2. The binder composition as claimed in claim 1, wherein the alkalinized bentonite is obtained by reacting bentonite with at least one alkali selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate.
3. The binder composition as claimed in claim 2, wherein the bentonite is at least one selected from the group consisting of sodium bentonite and calcium bentonite.
4. The binder composition as claimed in claim 1, wherein the polymer is at least one selected from the group consisting of hydroxylethyl cellulose, carboxymethyl cellulose, acrylamide, polypropylene and derivatives thereof.
5. The binder composition as claimed in claim 1, wherein the marsh funnel viscocity of the composition is in the range from 51 to 70 seconds.
6. The binder composition as claimed in claim 1, wherein the zeta potential of the composition is in the range from -36 to -18 mV.
7. A process for the preparation of a binder composition for the iron-ore pelletization process; said process comprising steps of:
a) reacting bentonite with an aqueous alkali solution to obtain alkalinized bentonite;
b) partially drying the alkalinized bentonite to obtain a mass having a pre-determined moisture content;
c) mixing the mass with at least one polymer to obtain the binder composition; and
d) optionally, milling the binder composition to obtain the binder composition in the form of powder.
8. The process as claimed in claim 7, wherein the alkali is at least one selected from the group consisting of sodium carbonate, sodium bicarbonate, sodium hydroxide, and sodium silicate.
9. The process as claimed in claim 7, wherein the aqueous alkali solution is obtained by dissolving alkali in water; wherein the amount of the alkali ranges from 0.5 to 5.0% of the weight of bentonite.
10. The process as claimed in claim 7, wherein the pre-determined moisture content of the mass is in the range from 9 to 25% of the total weight.
11. The process as claimed in claim 7, wherein the binder composition having moisture content in the range from 9 to 14% of the total weight is subjected to milling.
12. The process as claimed in claim 7, wherein the particle size of the binder composition in the powder form is in the range from 5 to 100 micron.
13. The process as claimed in claim 7, wherein, optionally, the binder composition is partially dried to obtain the binder composition having moisture content in the range from 9 to 14% of the total weight.
14. A pellet comprising an iron ore, a binder composition and at least one additive; wherein the amount of the iron ore ranges from 90 to 95 weight % of the total weight of the pallet, the amount of binder composition ranges from 0.05 to 2 weight % on dry basis, and the amount of additive/s ranges from 4 to 8 weight %.
15. The pellet as claimed in claim 14, wherein the iron ore is at least one selected from the group comprising of hematite and magnetite.
16. The pellet as claimed in claim 14, wherein the binder composition comprising on a dry basis:
(a) alkalinized bentonite, wherein the amount of alkalinized bentonite ranges from 99 to 99.99 weight %; and
(b) at least one polymer, wherein the amount of the polymer ranges from 0.01 to 1 weight %.
17. The pellet as claimed in claim 14, wherein the additive is at least one selected from the group consisting of dolomite, lime and charcoal.