Claims:We Claim:
1. Micropellets for iron ore sinter plant comprising of process waste of steel plant including sludge and dust along with binder comprising a selective binder composition of bentonite and high carbon fly ash with carbon content of unburnt carbon in the range of 6-20 % as iron ore sinter plant feed having added carbon based fuel source and maintaining iron ore sinter plant feed requirements of Drop no.:>11, moisture: <12%; -1mm%: <33% (after 48 hrs).

2. Micropellets suited for iron ore sinter plant as claimed in claim 1 wherein said high carbon fly ash comprises 45-50% SiO2, 25-30% Al2O3, 6-10% CaO, 6-20% Carbon and 8-22% LOI.

3. Micropellets for iron ore sinter plant as claimed in anyone of claims 1 to 2 wherein said bentonite comprises of 40-52% SiO2, 15-28% Al2O3, 1-4% CaO,10-20% Fe2O3, 2-5% Na2O, 0.1-0.3 K2O, 0.1-0.6% P2O5, 5-12% LOI.

4. Micropellets for iron ore sinter plant as claimed in anyone of claims 1 to 3 wherein said binder composition comprises up to 35% by wt fly ash in combination with rest bentonite as binder.

5. Micropellets for iron ore sinter plant plant as claimed in anyone of claims 1 to 4 wherein said binder composition includes fines size 25-50 % of 10 microns passing, 50-80 % of 25 microns passing, 75-90 % of 45 microns passing, 85-98 % of 75 microns passing, 100 % of 150 microns passing of fly ash providing for larger surface area for binding between particles.

6. Micropellets for iron ore sinter plant plant as claimed in anyone of claims 1 to 5 wherein said process waste of steel plant comprises selectively

SMS sludge : 21 to 41 wt%;
Bag filter dust : 20 to 36 wt%;
LD slag :7 to 15 wt%;
Lime-dolo fines:3 to 7wt%;
CDQ fines : 2 to 7 wt%;
Pellet dust: 2 to 5 wt%.

7. Micropellets for iron ore sinter plant as claimed in anyone of claims 1 to 6 wherein said process waste of steel plant comprises
SMS sludge : 40.0 wt%;
Bag filter dust : 33.5 wt%;
LD slag : 11.2 wt%;
Lime-dolo fines: 4.0 wt%;
CDQ fines : 6.0 wt%;
Pellet fines: 3.0 wt%;
Binder composition : 2.3 wt%.

8.Micropellets for iron ore sinter plant as claimed in anyone of claims 1 to 7 wherein said binder composition include bentonite and high carbon fly ash comprising:

Bentonite Fly-ash
SiO2, % 43.18 41.17
Al2O3, % 23.85 27.27
CaO, % 1.83 9.00
Fe2O3, % 16.56 7.85
K2O, % 0.20 0.83
Na2O, % 2.56 0.70
P2O5, % 0.45 0.67
SO3, % 0.14 0.34
MgO, % 0.90 0.33
LOI, % 10.28 1.45
Carbon, % --- 10.20
Zn, % 0.05 0.00

9. Micropellets as claimed in anyone of claims 1 to 8 wherein particle size distribution of Bentonite and Fly-ash comprising:
Size (microns),
Cumulative passing Bentonite (%) Fly ash, (%)
2 4.8 11.3
10 18.8 48.3
25 36.6 75.0
32 43.5 80.6
45 55.5 87.6
63 69.6 93.2
75 76.9 95.7
125 92.3 99.7
150 96.6 100.0
200 100.0 100.0
Blain No. (cm2/g) 2830 3450

wherein size analysis indicates that the fly-ash is finer than that of bentonite.

10. Micropellets as claimed in anyone of claims 1 to 9 having lower alkalies 0.39 to 0.47 % by wt and ZnO 0.02 to 0.03 % by wt, as well as improved CaO 16.9 to 19.8 % by wt and carbon content 11 to 13.4 % by wt.

11. A process for producing micropellets as claimed in anyone of claims 1 to 10 comprising :
providing process waste of steel plant and involving a binder composition to form micropellets comprising of bentonite and high carbon fly ash with carbon content of unburnt carbon in the range of 6-20 % as binder and obtaining therefrom the said iron ore sinter plant feed having added carbon based fuel source and maintaining iron ore sinter plant feed requirements of Drop no.:>11, moisture: <12%; -1mm%: <33% (after 48 hrs).
12. A process as claimed in claim 11 wherein the binder composition comprises upto 35% by wt fly ash in combination with rest bentonite as binder.

13. A process as claimed in anyone of claims 11 or 12 comprising
(i) providing raw materials including process wastes blend through feed hopper to conveyer comprising
SMS sludge : 21 to 45 preferably 40.0 wt%;
Bag filter dust : 20 to 36 preferably 33.5wt%;
LD slag : 7 to15 preferably 11.2 wt%;
Lime-dolo fines: 3 to7 preferably 4.0 wt%;
CDQ fines : 2 to 7 preferably 6.0 wt%;
Pellet dust: 2 to 5 preferably 3.0 wt%;
Binder : 1.5 to 3.0 preferably 2.3 wt%,
including selectively bentonite 1.6 to 2.0 wt% preferably 1.7 wt % and Fly-ash 0.20 to 1.0 wt% preferably 0.60 wt%; said Fly-ash containing carbon in the range of 6-20wt%;
Moisture : 4 to 8 wt% preferably 6 wt%.

(ii) feeding base blend with proportion of input ingredients as in (i) above including bentonite and fly ash as binder, through conveyer in primary mixer with moisture level of 13-15%;
(iii) subjecting the charge mix to micropelletization in a disc pelletizer; and
(iv) green micropellets so produced are subjected to atmospheric curing to obtain cured micropellets suitable as iron ore sinter plant feed.

14. A process as claimed in anyone of claims 11 to 13 wherein green micro pellets are subjected to atmospheric curing for 24 to 72 preferably about 48 hours duration thereby obtaining cured micropellets meeting the iron ore sinter plant requirements of: Drop no.:>11, moisture: <12%; -1mm%: <33%.

Dated this the 24th day of April, 2019
Anjan Sen
Of Anjan Sen & Associates
(Applicant’s Agent)
IN/PA-199

, Description:FIELD OF INVENTION

The present invention relates to a process of making micropellets by using high unburnt carbon containing fly-ash as binder for partial replacement of bentonite without affecting the quality of micropellets and recycling of waste material. Major constituents of high carbon fly-ash are 45-50% SiO2, 25-30% Al2O3, 6-10% CaO, 6-20% Carbon and 8-22% LOI. Micropelletization is the process of making 1-6 mm size cold bonded pellets by using process wastes such as sludge and dust from the steel plant. The present invention deals with the replacement of up to 35% of bentonite with fly-ash without affecting the present process of micropelletization process as well as iron ore sinter plant. Use of fly-ash resulted in cost benefit by reducing binder (bentonite) consumption, waste utilization, and protection of environment by reducing the dumping/land-fill. The unburnt carbon present in the flyash is an added advantage for iron ore sintering process by contributing as fuel. Superior fineness of the flyash is the other advantage of the fly-ash over bentonite. Due to the similar chemistry of fly-ash and bentonite, the iron ore sinter chemistry remains unaltered.

BACKGROUND OF THE INVENTION

Fly-ash is a byproduct generated from thermal power plants after combustion of coal fines. Disposal and recycling of flyash is a major environmental concern for the power plants. Though a considerable part of fly-ash is used in cement making and bricks manufacturing, substantial quantity remains unutilized, which is environmentally hazardous issue. Low carbon fly-ash (< 5 wt.% carbon) is generally utilized by cement and brick manufacturing industries but high carbon fly-ash (6-20 wt.% carbon) does not find applications. Major constituents of high carbon fly-ash are 45-50% SiO2, 25-30% Al2O3, 6-10% CaO, 6-20% Carbon and 8-22% LOI..Fly-ash is a byproduct generated from thermal power plants after combustion of coal fines. The chemistry of the fly-ash is very much similar to that of bentonite. The major constituents are silica (45-50%) and alumina (25-30%) in the form of alumino-silicates.

It is reported in literature (paper titled “Can fly-ash extend bentonite binder for iron ore agglomeration?” by S. Jayson Ripke, S. Komar Kawatra) that flyash contains alumino silicates and un-hydrated lime, reacts with water and undergoes a “pozzolanic” reaction with water and alkalis to form a cementitious bonding between the particles. The chemical composition of fly ash is similar to that of bentonite, so the usage will not disrupt the chemistry of the finished product.
While bentonite binders produce a physical bond between sludge and dust concentrate grains in the pellet, where as the fly-ash-based binders undergo a “pozzolanic” reaction. To check the feasibility of usage of fly ash as binder in micro pelletization, lab scale experiments are conducted at R&D pilot scale pellet disc.

Patent No. 3734-DELNP-2008, titled “Aggregate for Concrete and Construction” describes about usage of flyash as aggregate for concrete making in construction. This involves blending of fly ash together with a plasticizer and a reduced quantity of water to produce a fly ash slurry or dough. Heating the fly ash slurry or dough to effectively dry the slurry or dough from which a fly ash briquette is derived; and crushing the fly ash briquette to provide the lightweight fly ash aggregate. Preferably the method further comprises the step of sizing the fly ash aggregate according to a predetermined particle size range.

China Patent No. CN103602804 titled “High-performance pellet adhesive” describes about method of high performance pellet binder by using additives such as bentonite, flyash, zirconium oxide, polyester resin, starch. Whereas our present invention is usage of flyash as alternative binder for making of micro pellets. Micro pellet and pellet both are of different applications. Pellets used in BF and micro pellets are used in iron ore sinter planting.

UK Patent Application No. GB 2330138A titled “Aggregates from flyash” describes making of artificial light weight aggregate from flyash by mixing it with low melting alkali compounds of having Na2O & K2O, iron oxide fines, carbonaceous material, silicon carbide and then crushing the mix to make particle size of below 15mic powder. After that add water and make pellets of 5-10mm diameter and then bake the pellets at 1000-1250 deg C to get specific gravity 1.0 gm/cc which will developed light weight aggregate of crushing strength of 11-15N.

Indian Patent No. 216945 titled “A process for manufacture of cold bonded aggregate pellet from fly ash of thermal power plant for constructional use” describes the invention relates to a process of making cold bonded aggregate pellet from fly ash of thermal power plant for constructional use, building materials, concrete, road, pavement and embankment by replacing natural stone aggregates, gravel and sand. Where in the fly ash has been used to convert into pellet like aggregate firing at 1000 to 1500°C temperature in the rotary kiln or continuous chain grate sinter systems. Another object of the project invention is the use of hydraulic binders which are commercially available or prepared by combinations of various industrial solid wastes as binding agent with fly ash to make stone like aggregate by pelletisation technique.

Technical paper titled “A review of binders in iron ore pelletization, T.C.Eisele and S. K.Kawatra 2003” describes the reaction between high-purity aluminosilicate fly-ash and water would be as follows.
AS2 + 3CH + zH ===» C-S-H z-5 + C2 ASH8
where, C? CaO ; A? Al2O3; S? SiO2; H? H2O; z is a numerical variable.
The products of this reaction are an amorphous calcium silicate hydrate gel (C-S-H) and gehlenite hydrate (C2ASH8).

Thus none of the prior art made use of fly ash as binder for making micropellets utilizing iron bearing steel plant wastes. Present invention describes the usage of fly-ash as partial replacement of bentonite in micropelletization process.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to a process for producing micropellets using high carbon containing fly-ash as partial replacement of bentonite as binder for making micropellet and waste utilization, by making cold bonded pellets using process wastes such as sludge and dust from the steel plant.

A still further objective of the present invention is directed to increase the carbon content in micropellets present in fly ash as unburnt carbon in the range of 6-20%, which is an added advantage for iron ore sintering process by contributing as fuel.

A still further objective of the present invention is directed to production of micropellets suitable for iron ore sinter plant feed with <1 mm size fraction of less than 33% and <12% moisture.

A still further objective of the present invention is directed to production of micropellets using fly ash as binder wherein finer size (i.e., larger surface area) of the fly-ash results in more surface contact between particles and helps in improved binding.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to provide micropellets for iron ore sinter plant comprising of process waste of steel plant including sludge and dust along with binder comprising a selective binder composition of bentonite and high carbon fly ash with carbon content of unburnt carbon in the range of 6-20 % as iron ore sinter plant feed having added carbon based fuel source and maintaining iron ore sinter feed requirements of Drop no.:>11, moisture: <12%; -1mm%: <33% (after 48 hrs).

A further aspect of the present invention is directed to micropellets suited for iron ore sinter plant wherein said high carbon fly ash comprises 45-50% SiO2, 25-30% Al2O3, 6-8% CaO, 6-20% Carbon and 8-22% LOI.

A still further aspect of the present invention is directed to micropellets for iron ore sinter plant wherein said bentonite comprises of 40-52% SiO2, 15-28% Al2O3, 1-4% CaO,10-20% Fe2O3, 2-5% Na2O, 0.1-0.3 K2O, 0.1-0.6% P2O5, 5-12% LOI.

A still further aspect of the present invention is directed to micropellets for iron ore sinter plant wherein said binder composition comprises upto 35% by wt fly ash in combination with rest bentonite as binder.

A still further aspect of the present invention is directed to micropellets for iron ore sinter plant wherein said binder composition includes fines size 25-50 % of 10 microns passing, 50-80 % of 25 microns passing, 75-90 % of 45 microns passing, 85-98 % of 75 microns passing, 100 % of 150 microns passing of fly ash providing for larger surface area for binding between particles.

Another aspect of the present invention is directed to provide said micropellets for iron ore sinter plant wherein said process waste of steel plant comprises selectively

SMS sludge : 21 to 41 wt%;
Bag filter dust : 20 to 36 wt%;
LD slag : 7 to 15 wt%;
Lime-dolo fines: 3 to 7 wt%;
CDQ fines : 2 to 7 wt%;
Pellet dust: 2 to 5 wt%.

Yet another aspect of the present invention is directed to said micropellets for iron ore sinter plant wherein said process waste of steel plant comprises
SMS sludge : 40.0wt%;
Bag filter dust : 33.5wt%;
LD slag : 11.2wt%;
Lime-dolo fines: 4.0 wt%;
CDQ fines : 6.0 wt%;
Pellet dust: 3.0 wt%;
Binder composition : 2.3wt%.
.

A further aspect of the present invention is directed to micropellets for iron ore sinter plant wherein said binder composition include bentonite and high carbon fly ash comprising:

Bentonite Fly-ash
SiO2, % 43.18 41.17
Al2O3, % 23.85 27.27
CaO, % 1.83 9.00
Fe2O3, % 16.56 7.85
K2O, % 0.20 0.83
Na2O, % 2.56 0.70
P2O5, % 0.45 0.67
SO3, % 0.14 0.34
MgO, % 0.90 0.33
LOI, % 10.28 1.45
Carbon, % --- 10.20
Zn, % 0.05 0.00

A still further aspect of the present invention is directed to micropellets wherein particle size distribution of Bentonite and Fly-ash comprising:
Size (microns),
Cumulative passing Bentonite (%) Fly ash, (%)
2 4.8 11.3
10 18.8 48.3
25 36.6 75.0
32 43.5 80.6
45 55.5 87.6
63 69.6 93.2
75 76.9 95.7
125 92.3 99.7
150 96.6 100.0
200 100.0 100.0
Blain No. (cm2/g) 2830 3450

wherein size analysis indicates that the fly-ash is finer than that of bentonite.

A still further aspect of the present invention is directed to micropellets having lower alkalies 0.39.. to 0.47 % by wt and ZnO 0.02 to 0.03 % by wt, as well as improved CaO 16.9 to 19.8 % by wt and carbon content 11 to 13.4 % by wt.

A further aspect of the present invention is directed to process for producing micropellets as described above comprising:

providing process waste of steel plant and involving a binder composition to form micropellets comprising of bentonite and high carbon fly ash with carbon content of unburnt carbon in the range of 6-20 % as binder and obtaining therefrom the said iron ore sinter plant feed having added carbon based fuel source and maintaining iron ore sinter plant feed requirements of Drop no.:>11, moisture: <12%; -1mm%: <33% (after 48 hrs).

A still further aspect of the present invention is directed to a process wherein the binder composition comprises upto 35% by wt fly ash in combination with rest bentonite as binder.

Another aspect of the present invention is directed to said process comprising
(i) providing raw materials including process wastes blend through feed hopper to conveyer comprising
SMS sludge : 21 to 41% preferably 40.0wt%;
Bag filter dust : 20 to 36 % preferably 33.5wt%;
LD slag : 7 to 15 % preferably 11.2wt%;
Lime-dolo fines: 3 to 7 %preferably 4.0 wt%;
CDQ fines : 2 to7% preferably 6.0 wt%;
Pellet dust : 2 to 5% preferably 3.0 wt%;
Binder : 1.5 to 3.0 preferably 2.3wt%,
including selectively bentonite 1.6 to 2.0 preferably 1.7 wt % and Fly-ash 0.2 to 1.0 preferably 0.6 wt%; said Fly-ash containing carbon in the range of 6-20wt%;
Moisture : 4 to 8 preferably 6 wt%.

(ii) feeding base blend with proportion of input ingredients as in (i) above including bentonite and fly ash as binder, through conveyer in primary mixer with moisture level of 13-15%;
(iii) subjecting the charge mix to micropelletization in a disc pelletizer; and
(iv) green micropellets so produced are subjected to atmospheric curing to obtain cured micropellets suitable as iron ore sinter plant feed.

A still further aspect of the present invention is directed to said process wherein green micropellets are subjected to atmospheric curing for 24 to 72hours, preferably about 48 hours duration thereby obtaining cured micropellets meeting the iron ore sinter plant plant requirements of: Drop no.:>11, moisture: <12%; -1mm%: <33%.

The above and other objects and advantages of the present invention are described hereunder in greater details with reference to following non limiting illustrative drawings.
BRIEF DESCRIPTION OF THE ACCOMPNAYING DRAWINGS
Fig. 1: Schematic flow diagram of the process flow of micropelletization.
Fig. 2: SEM micrograph of bentonite and fly-ash.
Fig. 3: Photo image of Green micropellets produced according to present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a process of making micropellets by using high unburnt carbon containing fly-ash as binder for partial replacement of bentonite without affecting the quality of micropellets and recycling of waste material.

Micropelletization is the process of making pellets of 1-6 mm size cold bonded pellets by using process wastes such as sludge and dust from the steel plant. The schematic process flow diagram is illustrated in accompanying Figure 1. The facilities include the following components/features indicated with reference number:

Figure 1 shows the process of making cold bonded pellets comprises mixing of iron and carbon rich process wastes mixing of raw materials of SMS sludge, Bag filter dust, LD slag, pellet fines, CDQ fines, and by adding water during mixing. Sequence of addition of raw material through bunkers are as follows:

1- SMS sludge (bunker of 101), 2-Bag filter dust(bunker of 102), 3-LD slag (bunker of 103), 4-lime-dolo fines (bunker of 104), 5-CDQ fines (bunker of 105), 6-pellet fines (bunker of 106), 7-Bentonite(bunker of 107) , 8-Flyash (bunker of 108), materials of 1-8 will be discharge through screw feeding system of bunkers on to conveyor 1 (109) and then to primary mixer (201) for uniform mixing of raw materials and then discharge on Conveyor 2 and then discharge to Erich mixer (301). 4-8% of water will be added depends on the as received moisture content of raw materials and into the mixer during mixing and granulation of the mix for 3-6 minutes to make micro pellets of 1-6mm size and discharged to conveyor 3 (302) through which the produced micropellet will be stored as heap (401) of 5-7 meter height and transferred to iron ore sinter plant base mix feeding yard after 48 hrs of atmospheric curing. The moisture of the micro pellets of fresh prepared are 13-15% and after 48hrs of curing the moisture is 8-12% (below 11%).

Generally, binders such as bentonite, hydrated lime, molasses etc. are used in micropelletization processes. The chemical composition of fly ash used as binder in this invention is similar to that of bentonite. Alumino silicates and unhydrated lime, present in fly-ash, reacts with water and undergo a “pozzolanic” reaction to form a cementitious bond between the particles. The chemical composition and size analysis of bentonite and fly-ash are shown in Table 1 and 2 respectively.

Table 1: Chemical analysis of bentonite and fly-ash
Bentonite Fly-ash
SiO2, % 43.18 41.17
Al2O3, % 23.85 27.27
CaO, % 1.83 9.00
Fe2O3, % 16.56 7.85
K2O, % 0.20 0.83
Na2O,% 2.56 0.70
P2O5,% 0.45 0.67
SO3,% 0.14 0.34
MgO,% 0.90 0.33
LOI,% 10.28 1.45
Carbon, % --- 10.20
Zn,% 0.05 0.00

Table 2: Particle size analysis of binders, %

Size (microns),
Cumulative passing Bentonite (%) Fly ash, (%)
2 4.8 11.3
10 18.8 48.3
25 36.6 75.0
32 43.5 80.6
45 55.5 87.6
63 69.6 93.2
75 76.9 95.7
125 92.3 99.7
150 96.6 100.0
200 100.0 100.0
Blain No. (cm2/g) 2830 3450

The size analysis indicates that the fly-ash is finer than that of bentonite. The finer size of the fly-ash resulting in larger surface area and more surface contact between particles leading to improved bonding.

Microscopic examination: From the SEM micrographs of bentonite and fly-ash as shown in Figure 2, it is observed that the fly-ash particles are spherical in shape and finer is size wherein bentonite is mostly flaky and irregular in shape. The finer size (i.e., larger surface area) of the fly-ash results in more surface contact between particles and helps in improved binding.

Lab scale experiments and results:
Micropellets were prepared with process wastes blend as shown in Table 3 and binders using the disc pelletizer. The experimental plan is shown in Table 4. The steps in the experimental process of micropelletization was carried out as follows:
(i) Base blend was prepared with proportion of input ingredients as shown in Table 3 including binder as bentonite and fly ash in the replacement ratio of 0 to 100 wt% in steps of 25 wt% constituting total 2.3 wt% and mixed in primary mixer to have a 10 kg charge with moisture level of 13-15%.
(ii) The charge mix was subjected to micropelletization in a disc pelletizer.
(iii) Green micropellets so produced were subjected to 48 hr atmospheric curing.

Table 3: Composition of base blend
Raw material Wt. %
SMS sludge 40.0
Bag filter dust 33.5
LD slag 11.2
Lime-dolo fines 4.0
CDQ fines 6.0
Pellet dust 3.0
Binder 2.3
Total 100

Table 4: Experimental parameters
Batch size, kg 10
Binders Bentonite and Fly-ash
Total binder, % 2.3
Moisture, % 13 -15
Curing time, hrs 48 hrs atmospheric curing

Figure 3 shows the prepared green micropellets. The micropellets were subjected to atmospheric curing for 48 hrs and the properties were measured for 0, 24 and 48 hrs as shown in Table 5.

Table 5: Experimental Results

Expt. No. #1 #2 #3 #4 #5
Bentonite, % 100 75 50 25 0
Fly-ash,% 0 25 50 75 100
Green properties (zero hrs) Moisture, % 13.1 12.7 12.8 12.8 12.5
GCS, kg 0.8 0.8 0.7 0.6 0.5
Drop No. 15.0 14.0 14.0 15.0 13.0
After
24 hrs Moisture, % 7.8 7.9 8.0 7.7 7.0
DCS, kg 0.8 0.7 0.6 0.6 0.5
Drop No. 14.0 14.0 9.0 9.0 8.0
After
48
hrs Moisture, % 3.5 3.3 3.5 3.4 3.2
DCS, kg 1.2 1.0 0.9 0.7 0.5
Drop No. 18.0 15.0 15.0 14.0 12.0
-1 mm% (after 48 hrs) 14.0 14.0 16.7 18.3 20.9

The results indicate that the micropellets meet the properties required for use in iron ore sinter plant feed. Iron ore sinter plant Plant requirements are: Drop no.:>11, moisture: <12%; -1mm%: <33% (after 48 hrs).

Plant implementation of the process as ascertained through lab scale trial were carried out after regularization with and without flyash as binder and results are presented in table 6 below:

Table 6: Properties of micropellets with and without fly-ash usage.

Month/ Year Bentonite,
% Flyash
% Moisture,
% -1mm,
% MPS,
mm Fe(T),
% C,
% Na2O,
% K2O,
% ZnO,
% CaO, %
Without Fly-ash
Jan 2018 100 0 11.8 28.0 4.4 40.0 15.2 0.22 0.19 0.04 18.4
Feb 2018 100 0 11.7 28.5 4.4 39.1 15.2 0.23 0.20 0.03 18.6
Mar 2018 100 0 11.6 28.6 4.4 38.7 15.3 0.30 0.19 0.03 17.5
Apr 2018 100 0 11.3 27.9 4.5 38.7 15.6 0.31 0.20 0.04 16.9
May 2018 100 0 11.8 29.4 4.4 39.9 14.6 0.35 0.18 0.04 18.6
Jun 2018 100 0 12.0 28.7 4.4 39.6 13.1 0.31 0.18 0.03 19.8
Avg. 100 0 11.7 28.5 4.4 39.3 14.8 0.29 0.19 0.034 18.3
With Fly ash
Jul 2018 90.9 9.1 11.9 28.1 4.6 41.2 15.3 0.26 0.18 0.03 18.7
Aug 2018 68.2 31.8 11.5 30.4 4.4 40.4 15.1 0.24 0.17 0.03 18.9
Sep 2018 77.3 22.7 11.2 29.8 4.4 40.0 15.4 0.22 0.17 0.02 18.2
Oct 2018 72.7 27.3 11.2 29.1 4.3 41.4 15.8 0.26 0.17 0.03 19.0
Nov 2018 72.7 27.3 11.2 29.2 4.4 42.0 14.7 0.26 0.17 0.03 17.5
Dec 2018 72.7 27.3 11.6 29.9 4.4 41.0 13.0 0.28 0.20 0.03 17.9
Avg. 77.3 22.7 11.4 29.4 4.4 41.0 14.9 0.25 0.18 0.028 18.4

The lower alkalies, ZnO and improved CaO and carbon content in micropellets made with fly-ash-cum-bentonite as binder is attributed to the fly ash chemistry and it is better for the iron ore iron ore sinter plant feed.

It is thus possible by way of the present invention to provide a process of making micropellets by using high unburnt carbon containing fly-ash as binder for partial replacement of bentonite without affecting the quality of micropellets and recycling of waste material having the following distinct advantageous features:

1. A new application of fly-ash as binder for agglomeration (micropelletization) of process wastes.
2. Use of fly-ash as partial replacement of bentonite for micropellet making.
3. Improving the properties of micropellets by using fly-ash as binder resulting in lower alkalies, ZnO and improved CaO and carbon content making it a better iron ore sinter plant feed.
4. Production of micropellets suitable for iron ore sinter plant feed with <1 mm size fraction of less than 33% and <12% moisture.
5. Protection of environment by conserving the natural resources of bentonite
6. The finer size of the fly-ash resulting in larger surface area and more surface contact between particles leading to improved bonding.