Description:Field of Invention

The present invention relates to system for iron ore pellet production for steel plants and the like and related pelletizing process for the production of green iron ore pellets selectively by including and utilizing waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines/coal fines by involving said system whereby waste carbon fines generated in the coke dry quenching (CDQ) unit of the steel plant can be utilized in iron ore pellets production.
More particularly, the present invention is directed to said system including improved and modified configuration of the raw additive and fuel bin of the pellet plant aiding pneumatically controlled pumping of waste carbon fines/carbon dust/CDQ dust to said bin from storage/tanker and discharge therefrom in controlled, precisely measurable flow rate thereby arresting flushing of said waste carbon fines.
More particularly, the present invention is directed to provide improved configuration of the discharge section of raw additive and fuel bin of the pellet plant and processing of pellets therefrom. More particularly, the present invention is directed to handle, store and use the CDQ fines/dust as a partial or complete replacement of conventional carbon bearing materials i.e. coke breeze fines/coal fines conventionally involved in pellet making. Waste generated in the form of fines/dust in CDQ unit of the steel plant contains carbon values and utilization of CDQ fines/dust as an in-situ resource in pellet making was thus investigated firstly in lab scale study and then upgraded to make pellets in pellet plant. Feasibility study of the utilization of CDQ fines as a partial or complete replacement of conventional coke breeze fines was conducted. Properties of the pellets prepared with coke breeze and CDQ fines were analyzed. It was found that CDQ fines can replace coke breeze completely in pellet making.

Background Art
Coke breeze is used as in-situ carbon source in the conventional pellet making process of hematite iron ore. These coke sources are the required constituents in hematite iron ore pelletization process. Use of coal/coke breeze in the production of hematite iron ore pellets fulfils two objectives in the pellets production. Firstly, it provides internal heat to the pellet matrix during pellet heating thereby reduces the temperature gradient between pellet surface and center and this reduction in temperature gradient helps in obtaining better product pellets properties. Secondly, burning of coal particles inside the pellets during induration generates pores which helps in achieving the desired porosity of the product pellets as porosity is required during reduction of the product pellets inside the blast furnace and other iron making units.

IN2014MA03514 describes a process for converting CDQ fines into briquettes. In the described briquette making process, air dried CDQ fines are mixed with Pitch binder in dry condition and subsequently the prepared mixture is mixed with wash oil binder to form a homogeneous mixture of CDQ fines, Pitch binder and wash oil binder. The ratio of Pitch and wash oil is in the proportion of 2:1-2:1.5. The prepared homogeneous mixture is converted into briquettes by compressing the mixture in a sand rammer. The prepared briquettes are cured in open air and then heated at 150-250 °C. The patent describes CDQ fines briquettes. The briquettes made out of CDQ fines may be used as partial replacement of coke in the Blast Furnace.

KR19990052022 relates production of cold bonded pellets. The outer most layer of the cold bonded pellets is coated by using a mixture of CDQ dust and binder. The average particle size distribution of coating materials is 0.125 mm. Preferably, the binder content is 20-30wt. % in the coating materials. CDQ dust contains 85% or more of fixed carbon and 80% or more of particles having a particle size of 0.125 mm or less. The coating of the pellets was done to prevent adhesion of the cold bonded pellets.

BE19850215490 describes a method for agglomerating fuels such as coal dust or the like. It also describes the produced agglomerate. The agglomeration process of coal dust and the like, comprises of adding bentonite to a maximum concentration of 5 wt. % and a thermosetting polymeric binder and extrusion of the mix.

IN201621004252 describes a composition enriched with CDQ fines. The patent describes an agglomerate in the form of micro pellets produced by mixing 10-12 % CDQ fines, 50-85 % metallurgical/mineral/slag waste, 2-3 % silica based activated mineral binder and 4-6 % moisture. The patent describes that the produced micro pellets as one of the constituents of the feed materials for sinter plant.

The prior arts discusses various treatments and processes to enrich CDQ fines/ dust for pellet making and to utilize carbon values therein in said CDQ fines but none of the prior arts traverses assessment of CDQ fines as carbon containing waste fines as in-situ source of carbon while making iron ore pellets. None of the prior arts discussed about the feasibility of utilization of carbon bearing particles as the partial or complete replacement of the existing source of carbon in the iron ore pellet plants. None of the prior arts discussed about the handling, transportation and storage of these carbon particles in the pellet plant.

Practically it is very difficult to collect, transport, store and utilize these waste carbon particles/fines in the pellet making process at the pellet plant.
Hence there is a long felt need in the art to provide for dedicated and improved system for iron ore pellet production in steel plants and the like including improved and modified raw additive and fuel bin that would enable utilization and controlled addition of waste carbon fines/dust generated in coke dry quenching (CDQ) units of steel plant in iron ore pellet production and during pellet making by avoiding flushing adaptable to the conventional process flow of iron ore pellet plant during steel making, which system in involving modified discharge section of raw additive and fuel bin would not only enable production of iron ore pellets by completely replacing coke breeze in pellet making, but would also be able to handle, store and involve such carbon fine wastes generated from CDQ unit as a partial or complete replacement of conventional carbon bearing materials i.e. coke breeze fines/coal fines usually involved in pellet making to enable green iron ore pellets.
Objects of the invention
The basic objective of the present invention is directed to provide for dedicated and improved system for iron ore pellet production in steel plants and the like including improved and modified configuration of raw additive and fuel bin that would enable utilization and controlled addition of waste carbon fines/dust generated in coke dry quenching (CDQ) units of steel plant in iron ore pellet production and during pellet making by avoiding flushing that would be also adaptable to the conventional process flow of iron ore pellet plant during steel making.
Another object of the present invention is to provide for a system in involving modified discharge section of raw additive and fuel bin that would not only enable production of iron ore pellets by completely replacing coke breeze in pellet making, but would also be able to handle, store and involve such carbon fine wastes generated from CDQ unit as a partial or complete replacement of conventional carbon bearing materials i.e. coke breeze fines/coal fines usually involved in pellet making to enable green iron ore pellets.
A further objective of the present invention is directed towards the process development for the utilization of waste carbon particles/fines in the pellet plant.
Yet further objective of the present invention is directed towards the development of a process to handle, pump and store the waste carbon particles/fines in the raw additive and fuel bin.
A further objective of the present invention is directed towards the development of a system that is configured to enable a mechanism of feeding the waste carbon particles/fines into raw additive and fuel bin.
Summary of the invention
It is thus the basic aspect of the present invention providing for a system for iron ore pellet production for steel plants and the like comprising:
Feed bins for pelletization raw materials including raw additive and fuel bin (16205);
said raw additive and fuel bin (16205) comprising of a coke breeze discharge section (106) and/or coke dry quenching unit based waste CDQ dust particles/ fines discharge section (110);
said raw additive and fuel bin (16205) operatively connected to coke conveyor (200) for supply of coke /coke breeze and CDQ fine through supply line (102) provided with pneumatically controlled feeding of said waste CDQ dust particles/fines into said raw additive and fuel bin (16205);
said coke breeze discharge section (106) and said waste CDQ particle/fines discharge sections (110) having means for selective controlled feed of the respective coke breeze along with said CDQ fines or only said CDQ fines through respective sections;
said waste CDQ particles/fines discharge section including valve means including Rotary Air Valve (RAV)(112) means for controlling flow rate and flushing of the CDQ dust particles supply to pelletization process without said coke breeze from said raw additive and fuel bin for use in pelletization.

Preferably in said system for iron ore pellet production for steel plants and the like wherein
said coke breeze discharge section (106) is provided with a knife edge gate (108) to handle flow of the coke breeze along with said waste CDQ dust particles/fines supply to the pelletization process, and, said waste CDQ dust particles/ fines discharge section supply through said RAV (112) independently;
said raw additive and fuel bin (16205) top portion is equipped with baghouse (116) through operative bag house duct line (114);
said waste CDQ fines/particles from various sources as collected is stored in ground level portable storage /tanker (100) providing for enclosed storage;
said enclosed storage of collected waste CDQ fines/particles including operative connections to compressed air supply line (104), material supply pipeline (102) for pneumatically supplying the CDQ to said raw additive and fuel bin (16205) disposed above said ground level of said enclosed storage of said collected waste CDQ fines/particles (100).

According to another preferred aspect of the present invention there is provided system for iron ore pellet production for steel plants and the like wherein said
raw additive and fuel bin (16205) with discharge section (110) as bin chute allows storage and/or controlled addition/pumping of waste carbon fines/carbon dust/CDQ dust generated in coke dry quenching (CDQ) units of steel plant, to weigh Belt Feeder AF5 (202) through pneumatically controlled pumping means,
said pneumatically controlled feeding/supplying including:
compressed air line (104) fitted to a tanker (100) to impinge compressed air on waste carbon fines held in the tanker (100) so as to pump said waste carbon fines through waste carbon fine materials line (102) connected with top portion of the raw additive and fuel bin (16205), and,
rotary air valve (RAV) (112) fitted at cone base of said bin chute thereby enabling pneumatically controlled precise pumping discharge and flow of said waste carbon fines to said weigh Belt Feeder AF5 (202) and finally to additive grinding ball mill.

Preferably said system is provided wherein for iron ore pellet production for steel plants and the like
said raw additive and fuel bin (16205) with bin chute is configured into portions based on dividing bin chute into two halves (110) and (106) allowing storage for controlled addition/pumping of waste carbon fines/dust generated in coke dry quenching (CDQ) units of steel plant, to said weigh Belt Feeder AF5 (202) through said pneumatically controlled pumping means,
said rotary air valve (RAV) (112) is fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) with the other half portion (106) of said bin chute attached with knife edge gate (108) adapted to enable pneumatically controlled & non-simultaneous sequential pumping discharge of said waste carbon fines & coke breeze particles along with waste carbon fines respectively from said half portions of bin chute into said weigh Belt Feeder AF5 (202) and finally into additive grinding ball mill for iron ore pellet making.
According to another preferred aspect of the present invention there is provided a system for iron ore pellet production for steel plants and the like wherein said rotary air valve (112) fitted at cone base of said bin chute or fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) is adapted to control, precisely measure flow rate of waste carbon fines and also arrest flushing of said waste carbon fines.

Preferably said system for iron ore pellet production for steel plants and the like is provided wherein said rotary air valve (RAV) (112) fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) with the other half portion (106) of said bin chute attached with knife edge gate (108) allows sequential discharge of materials such that knife edge gate assisted portion of bin chute enables discharge of coke breeze fines along with waste carbon fines and RAV (112) assisted portion of bin chute enables discharge of waste carbon fines.

According to yet another preferred aspect of the present invention there is provided said system for iron ore pellet production for steel plants and the like wherein discharge from said half portions of bin chute of said raw additive and fuel bin (16205) is lead to weigh Belt Feeder AF5 (202) and forward to additive feed conveyer AF9 (206) and thereafter to lime stone and additive grinding ball mill of iron ore pellet production unit, with said Weigh Belt Feeder AF5 (202) being disposed at a distance (400) at higher level from said floor area (302).

Preferably in said system for iron ore pellet production for steel plants and the like wherein said raw additive and fuel bin (16205) is disposed between Bentonite grinding feed bin (16231-1) and Lime stone grinding feed bin (16231-2), with said Bentonite grinding feed bin (16231-1) and raw additive and fuel bin (16205) adapted to receive materials from Bentonite and Coke Conveyer AF3 (200), and, said Lime stone grinding feed bin (16231-2) is adapted to discharge materials to additive feed conveyer AF9 (206) via Weigh belt feeder AF6 (204).

According to another preferred aspect of the present invention there is provided a system for iron ore pellet production for steel plants and the like wherein said waste carbon fines/carbon dust filled tanker (100) lies on the ground level (300) below the floor area (302); said system enabling production of hematite iron ore pellets based on the utilization of waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines functioning as in-situ carbon source with superior properties superior to ones produced with coke breeze fines.

According to another aspect of the present invention there is provided a process for the production of green iron ore pellets selectively including waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines by involving said system comprising the steps of
(a) providing waste carbon fines/carbon dust/CDQ dust of varied sizes from their generating units in a ground level portable storage /tanker operatively connected to said raw additive and fuel bin;

(b) providing source of coke /coke breeze operatively connected to said raw additive and fuel bin;

(c) providing supply of lime stone to a lime stone grinding feed bin;

(d) pumping said waste carbon fines/carbon dust/CDQ dust from storage /tanker into said raw additive and fuel bin (16205) including said coke breeze discharge section and/or said waste CDQ particle/fines discharge sections, with said bin placed at a higher height and operatively connected to said storage tanker through said operating line (102) aiding pneumatically controlled pumping involving compressed air;
(e) selectively discharging said waste carbon fines/carbon dust/CDQ dust from said waste CDQ particle/fines discharge sections or said coke breeze along with said waste CDQ particle/fines from said coke breeze and waste CDQ particle/fines discharge sections for pelletization involving said waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines.
Preferably in said process wherein
said step (a) includes collecting waste carbon fines/carbon dust/CDQ dust of varied sizes from their generating units and assessing through laboratory studies on their suitability for iron ore pelletization;

in said step (d) during pneumatically pumping finer dust particles gets collected in bag house (116);
in said step (e) during selectively discharging said waste carbon fines to said weigh Belt Feeder AF5 (202) and finally to additive grinding ball mill via rotary air valve (RAV) (112) fitted at cone base of said bin chute thereby enables pneumatically controlled precise pumping discharge and flow of said waste carbon fines for iron ore pellet making.

More preferably said process is provided wherein
when the raw additive and fuel bin (16205) chute is divided into two halve portions then the waste carbon fines/carbon dust/CDQ dust is discharged with the aid of rotary air valve (RAV) (112) to which portion the valve is fitted so that said waste carbon fine discharge is precisely controlled, with precisely measured flow rate of waste carbon fines also arresting flushing of said waste carbon fines,
and,
conventional coke breeze particles along with CDQ dust are discharged from the other half portion of bin chute fitted with a knife edge gate (108) thereby passing discharges from both the portions of the chute bin to the weigh Belt Feeder AF5 (202) and after wards passing the discharges to Additive feed conveyer AF9 (206) that finally goes to lime stone and additive grinding ball mill for iron ore pellet making.
According to another aspect of the present invention there is provided iron ore pellets as green iron ore pellets including waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines said pellets comprising 80-100% content of waste carbon fines/carbon dust/CDQ dust as carbon bearing source with unfired pellets reducing to 1.38 % from 1.52 % when said CDQ dust content is increased to 80-100 % from 0-20% of the specific consumption of fuel sources in the product pellets.
Preferably said iron ore pellets are provided wherein 80-100% increased CDQ dust content in said pellets as compared to 0-20 % CDQ dust content enables the following:
improved average AI (abrasion index) of fired pellets improved to 4.36 % from 4.52 %;
improved average CCS (cold crushing strength) of the fired pellets improved to 298 Kg/pellet from 280 Kg/pellet;
average TI (tumbler index) of fired pellets improved to 94.57 % from 94.3 %.

Thus the basic aspect of the present invention is directed to design modification in the raw additive and fuel bin discharge section.
Further aspect of the present is directed to development of a pumping mechanism for handling and feeding the CDQ dust into the raw additive and fuel bin.
Another aspect of the present invention is to operation of the raw additive and fuel bin with CDQ dust.
Another aspect of the present invention is to assess the particle size of the CDQ dust.
Another aspect of the present invention is directed towards the assessment of CDQ dust towards their utilization as in-situ carbon source in iron ore pellet making.
Another aspect of the present invention is to produce green pellets with coke breeze and CDQ dust and characterization of the produced pellets for their properties.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: Design modification in the raw additive and fuel bin at Pelletizing unit for storage and feeding of CDQ dust;
Figure 2: Photograph of a) conventional chute bin without RAV i.e. Conventional discharge section of the raw additive and fuel bin, and b) modified chute bin with new RAV installed i.e. Modified discharge section of the raw additive and fuel bin fitted with RAV;
Figure 3a: Line chart of day average CCS (Cold crushing strength) of fired pellets before and after plant implementation;
Figure 3b: Line chart of day average TI (Tumbler Index) of fired pellets before and after plant implementation;
Figure 3c: Line chart of day average AI (Abrasion Index) of fired pellets before and after plant implementation;
Figure 3d: Line chart of day average of unfired pellets before and after plant implementation.
Figure 4: shows the thermo-gravimetric (TG) analysis of samples. Curves 1, 2, 3 and 4 corresponds to weight loss in Type 2 CDQ dust sample (curve 1), coke breeze (curve 2), Type 3 CDQ dust sample (curve 3) and Type 1 CDQ dust sample (curve 4). The reactivity of coke breeze is found superior than all Type of CDQ dust sample. Type 2 CDQ dusts are the major fines being generated. As the heating progresses, Type 2 CDQ dust sample show the reactivity similar to that of coke breeze.
Figure 5: Effect of CDQ dust content on CCS
Figure 6: Effect of CDQ dust content on TI
Figure 7: Effect of CDQ dust content on AI
Figure 8: Effect of CDQ dust content on unfired pellets %
Day average values of CCS, TI, AI and % unfired pellets and their standard deviations are shown in Table 13 for the period of before (6 months duration) and after implementation (7 months duration) of the innovation in plant.

List of components/elements:
100 Tanker
102 CDQ fines line
104 Air line
106 Coke breeze discharge section A
108 Knife edge Gate
110 CDQ fines discharge section B
112 Rotary air valve
114 Bag house duct
116 Bag house
200 Bentonite and Coke Conveyer AF3
202 Weigh Belt Feeder AF5
204 Weigh belt feeder AF6
206 Additive feed conveyer AF9
300 Ground Level
302 Floor area
400 Distance between 202 Weigh Belt Feeder AF5 and 302 Floor area
16205 Raw additive and fuel bin
16231-1 Bentonite grinding feed bin
16231-2 Lime stone grinding feed bin

DETAILED DESCRIPTION OF THE INVENTION IN REFERENCE TO ACCOMPNAYING DRAWINGS

As discussed hereinbefore, the present invention provides for a dedicated and improved system for pellet production in steel plants and the like and related pelletizing process for the production of green iron ore pellets selectively by including and utilizing waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze/coal fines by involving said system whereby waste carbon fines generated in the coke dry quenching (CDQ) unit of the steel plant can be utilized in iron ore pellets production.
Said system with improved and modified configuration of the raw additive and fuel bin of the pellet plant aids pneumatically controlled pumping of waste carbon fines/carbon dust /CDQ dust to said bin from storage/tanker and discharge therefrom in controlled, precisely measurable flow rate thereby arresting flushing of said waste carbon fines for utilization in pellet making.
Said dedicated and improved system for iron ore pellet production units in steel plants and process thereof including improved and modified raw additive and fuel bin for controlled addition of waste carbon fines/dust generated in coke dry quenching (CDQ) units of steel plant towards iron ore pellet production and during pellet making, by abiding with the conventional process flow of iron ore pellet plant required for steel making, involves said raw additive and fuel bin with improved configuration of chute over the existing chute with the bin allowing pneumatically controlled feeding of waste CDQ dust into coke grinding feed enabled by its feed mechanism. The system of the present invention is also adapted to handle, store and involve such carbon fine wastes as generated from CDQ unit as a partial or complete replacement of conventional carbon bearing materials for iron ore pellet making i.e. coke breeze fines usually involved in pellet making.

The present invention is thus enabled by firstly, collecting these waste carbon bearing particles of varied sizes from their generating units whose properties were then tested and assessed by utilizing in the laboratory scale study with further conducting iron ore pelletization study to ascertain whether these particles can be used in pellet making as one to one replacement of the existing carbon source of coke breeze fines.

The present invention through its process thereof deals with the feasibility aspect of the utilization of CDQ dust as the in-situ carbon source in pellet making.

WORKING EXAMPLES:

Accompanying Figure 1 shows the pneumatically controlled pumping mechanism developed for handling and storage of the CDQ dust into the raw additive and fuel bin. Figure 1 also shows the modification of the raw additive and fuel chute in the form of additional installed rotary air valve (RAV). CDQ dust generated in the CDQ and coke oven plant collected into the tanker 100 and shifted to pellet plant. Tanker 100 is fixed with compressed air line 104 of diameter 100 mm. During pumping of the CDQ Dust from the tanker 100 compressed air is supplied in to the tanker 100 and CDQ Dust along with compressed air flows in the materials line 102 of 150 mm diameter. This materials line is connected to the top of the raw additive and fuel bin 16205. The top of the raw additive and fuel bin 16205 is also equipped with baghouse 116 through bag house duct 114 of diameter 150 mm. Different sizes of collected CDQ dusts are pumped into the raw additive and fuel bin 16205 with the help of pneumatically controlled developed mechanism. The Half portion (110) of the bin chute of the raw additive and fuel bin 16205 is fitted with RAV 112 of 350 mm diameter and the other half portion (106) is attached with knife edge gate (108). The discharge from both the portions of the chute bin goes to the 202 weigh Belt Feeder AF5 and after wards to 206 Additive feed conveyer AF9. From 206 Additive feed conveyer AF9 materials goes to lime stone and additive grinding ball mill. The CDQ Dust filled tanker lies on the ground level 300. The above discussed modification in the raw additive and fuel bin 16205 enabled the utilization of the different types of CDQ dust particles in pellet plant. Conventional coke breeze/coal fines and CDQ fines/dust is feed to the raw additive and fuel bin 16205 according to the requirement in a proportion. To control the flushing of the CDQ dust/fines RAV is used. During utilization of both coke breeze/coal fines and CDQ fines/dust simultaneously in a proportion, knife edge gate 108 is used to discharge the mixed blend of coke breeze/coal fines and CDQ dust/fines. During utilization of only CDQ dust/fines the RAV 112 is used to control the flushing during discharge. Thus both type of discharge systems are used as per the requirement.

Accompanying Figure 2a shows the digital picture of the existing bin chute of the raw additive and fuel bin 16205. In the existing process the bin chute is equipped with knife edge gate. With the help of knife edge gate it is easy to handle the flow of the coke breeze particles. This facility is unable to handle the CDQ dust particles flow rate.

Accompanying Figure 2b shows the digital picture of the actual modification done in the bin chute of raw additive and fuel bin 16205. During use of coke breeze and CDQ dust as solid fuel in pellet making, knife edge gate 108 is opened and during use of CDQ dust RAV 112 is used to discharge the materials. Selectively employing RAV in the bin chute helps to measure the flow rate accurately and to control the flushing of finer CDQ dust particles.

LABORATORY SCALE STUDIES

Particle size analysis of different types of CDQ dust samples
Size analysis of the samples was carried out using particle size analyzer and the results are shown below.
Type 1 CDQ dust
Table 1: Size analysis of as-received CDQ dust Type 1
Size (micron) -150 +150 -250 +250
Wt.% 95.76 2.97 1.27

Table 2: Size analysis of -150 µ size sample obtained as shown in Table 1.
Size (micron) -2 -4 -6 -8 -10 -20 -25 -32 -45 -75 -150
Cumulative Wt.% 8.72 15.40 20.43 24.91 29.24 49.31 57.47 66.21 77.98 92.78 100.0

Type 2 CDQ dust
Table 3: Size analysis of as received CDQ dust type 2
Size (micron) -150 +150-250 +250-500 +500-710 +710 -1000 +1000
Wt.% 50.85 14.88 15.82 14.31 1.88 2.26

Table 4: Size analysis of -150 µ size sample obtained as shown in Table 3
Size (micron) -2 -4 -6 -8 -10 -20 -25 -32 -45 -75 -150
Cumulative Wt.% 1.31 3.01 5.30 7.75 10.43 21.52 25.66 30.62 39.17 55.52 100.00

Type 3 CDQ dust
Table 5: Size analysis of as received CDQ dust type 3
Size (micron) -150 +150
Wt.% 97.69 2.31

Table 6: Size analysis of -150 µ size sample obtained as shown in Table 5
Size (micron) -2 -4 -6 -8 -10 -20 -25 -32 -45 -75 -150
Cumulative Wt.% 2.43 4.59 6.37 7.91 9.62 17.82 21.65 27.09 38.46 64.31 100.00

Comparison of Bond work Index and GHI of coke breeze and type 2 CDQ dust sample
Bond work Index:
Coke Breeze
• BWI of coke breeze: 43.34 KWh / Ton
• Grindability of coke breeze: 0.32 gm / cycle
Type 2 CDQ dust sample
• BWI of type 2 CDQ dust sample: 46.56 KWh / Ton.
• Grindability of type 2 CDQ dust sample: 0.36 gm / cycle

Hard groove Grindability Index (HGI)
It was found that the type 2 CDQ dust sample have nearly the same value to that of coke breeze, i.e., grinding of coke breeze and type 2 CDQ dust sample do not require extra power consumption.
Table 7: HGI of Coke breeze and chamber fines
Sl. No. Raw materials HGI
1 Coke breeze 43.5
2 Type 2 CDQ dust sample 43.1

Proximate & Ultimate analysis
Table 8: Proximate & Ultimate analysis of fines
Sl. No. Raw materials Proximate Analysis Ultimate Analysis
Ash (%) VM (%) FC (%) C
(%) H (%) N (%) S
(%) O (%)
1 Coke breeze 20.66 3.82 75.52 76.5 0.42 0.74 0.466 1.21
2 Type 1 CDQ dust sample 22.19 2.65 75.16 76.20 0.21 0.41 0.993 -
3 Type 2 CDQ dust sample 18.02 1.48 80.50 81.31 - - 0.674 -
4 Type 3 CDQ dust sample 15.22 1.58 83.20 84.21 - - 0.568 -

Reactivity of coke breeze and CDQ dust
The reactivity of coke fines can be studied either in CO2 atmospheres or in O2-N2. The process in CO2 atmosphere occurs in two different stages, i.e., pyrolysis and reaction to CO2. The reactivity during pyrolysis is mainly a function of volatiles and heating rate whereas during reaction to CO2 is mainly a function of coal type. The reactivity in O2-N2 atmosphere is mainly a function of volatilization extent.

The thermo-gravimetric (TG) analysis of the samples are carried out under O2-N2 atmosphere

Figure 4 shows the thermo-gravimetric (TG) analysis of samples. Curves 1, 2, 3 and 4 corresponds to weight loss in Type 2 CDQ dust sample, coke breeze, Type 3 CDQ dust sample and Type 1 CDQ dust sample. The reactivity of coke breeze is found superior than all Type of CDQ dust sample. Type 2 CDQ dust are the major fines being generated. As the heating progresses, Type 2 CDQ dust sample show the reactivity similar to that of coke breeze.

Gross Calorific Value (GCV) analysis of samples
Table 9: GCV of samples
Sl. No. Raw materials GCV (K.cal / kg)
1 Coke breeze 5876
2 Type 1 CDQ dust sample 5740
3 Type 2 CDQ dust sample 6197
4 Type 3 CDQ dust sample 5496

Pelletization Study:
Table 10: Raw materials Chemical analysis, Wt. %
Raw materials Fe SiO2 Al2O3 CaO MgO MnO Na2O K2O LOI
IOF 61.24 4.92 3.05 0.21 0.03 0.24 0.03 0.02 3.54
Limestone 2.00 2.40 0.47 51.48 0.93 0.00 0.01 0.09 41.38
Dolomite 0.87 5.58 0.71 29.98 18.48 0.00 0.08 0.15 43.52
Bentonite 9.21 50.86 15.96 2.46 2.77 0.11 2.43 0.15 10.82

Table 11: Mass balance and DOE for the experiments, Wt. %
Expt. No. HBF Limestone Dolomite Coke breeze Type 2 CDQ
Dust Bentonite
1 94.37 0.37 3.78 0.84 0.00 0.64
2 94.37 0.37 3.78 0.42 0.42 0.63
3 94.37 0.37 3.78 0.00 0.84 0.63

Table 12: Properties of Green and Fired Pellets
Properties Experiment#1 Experiment#2 Experiment#3
GP moisture, % 9.21 9.13 9.14
Drop strength, No. 18 18 18
Std. dev. of drop test 5 5 4
GCS, kg/pellet 1.4 1.3 1.4
Std. dev. of GCS 0.26 0.25 0.26
CCS, kg/pellet 237 239 245
Std. dev. of CCS 65 66 64

Observations:
• CDQ fines generated in the CDQ plant is a good source of carbon. Type 1 CDQ dust sample are 96% of -150 micron passing and can be used without grinding.
• Type 2 CDQ dust sample are coarse in size and requires grinding for use in pellet making.
• The carbon content in all these coke fines are either comparable or better than that of coke breeze.
• Type 2 CDQ dust sample have higher calorific value (6197 K.cal/kg) as compared to the coke breeze (5876 K.cal/kg).
• Bond work index of Type 2 CDQ dust sample is slightly higher than that of coke breeze.
• HGI of Type 2 CDQ dust sample and coke breeze is nearly same.
• The pelletization study results showed that there is little impact on green or fired pellet properties when Type 2 CDQ dust sample are used as carbon source in place of coke breeze.

PLANT SCALE IMPLEMANTATION
As CDQ dust was very fine in nature so it was very difficult to handle and control the CDQ dust with existing conventional setup at plant and utilization of CDQ dust in pellet production instead of coke fines could reduce production cost of the pellets so the bottlenecks for CDQ dust utilization and solutions which can be done in house and are safe are discussed and identified. Also it was decided to follow-up and standardize the process. The main problem was identified as handling and storage of CDQ micro dust in the bin and involving the same in the pellet process. The area of the problem was identified as raw lime and coke bin. Coke specific consumption cost was affected due to the CDQ dust utilization. Dedicated facility for storage of CDQ fines was developed. Controlled addition of the CDQ dust into the process based on the present system was ensured. Standard Operating Procedure for utilization of CDQ dust was prepared. Figure 1 shows the modification in configuration in raw additive and fuel bin for handling, storage and utilization of CDQ dust in the pellet making process.
Constituents Avg. CCS, Kg/Pellet Std. Dev. of Avg. CCS Avg. TI (+6.3mm, wt. % Std. Dev. of Avg. TI Avg.AI (-0.5 mm), wt. % Std. Dev. Of Avg. AI Avg. Unfired Pellets, % Std. Dev. Of Avg. Unfired Pellets,%
Before implementation 283 18 94.1 1.00 4.75 0.8 1.46 0.65
After implementation 301 17 94.67 0.93 4.33 0.8 1.38 0.65
Table 13: Fired pellets properties before and after implementation of the study

It is thus possible for the present invention to provide for said dedicated system for iron ore pellet production for steel plants and the like favouring controlled addition of waste CDQ dust particles/ fines in pellet making in the conventional process flow of the pellet plant, said system involving pneumatically controlled pumping mechanism to pump the CDQ dust from storage tanker to said raw additive and fuel bin adapted to the modified configuration of bin chute of raw additive and fuel bin, with one portion of the bin chute fitted with Rotary Air Valve (RAV) or the existing bin chute of the raw additive and fuel bin fitted with Rotary Air Valve (RAV) to efficiently control the flow of waste carbon dust for pellet making by arresting flushing. The present invention also makes possible a process for production of hematite iron ore pellets with utilization CDQ dust as 0 to 100 % replacement of conventional coke breeze fines, in which waste CDQ dust acts as an in-situ carbon source sometimes having properties superior to that of produced with coke breeze fines. As shown above superior properties of CDQ dust as highlighted above can provide improved hematite iron ore pellets with superior end characteristics whereby Figures 5 to 8 shows the effect of CDQ content on fired pellets properties. It was observed that with the increasing content of CDQ dust, the end characteristics of the fired pellets showed improvements. As shown in Figure 5, average CCS of the fired pellets improved to 298 Kg/pellet from 280 Kg/pellet when the content of CDQ dust increased to 80-100 % from 0 to 20 % respectively of the total consumption of carbon bearing sources per ton of product of pellets. Figure 6 showed that average TI of fired pellets improved to 94.57 % from 94.3 % when the content of CDQ dust increased to 80-100 % from 0 to 20 % respectively of the total consumption of carbon bearing sources per ton of product of pellets. Figure 7 showed that average AI of fired pellets improved to 4.36 % from 4.52 % when the content of CDQ dust increased to 80-100 % from 0 to 20 % respectively of the total consumption of carbon bearing sources per ton of product of pellets. Figure 8 showed that average unfired pellets reduced to 1.38 % from 1.52 % when the content of CDQ dust increased to 80-100 % from 0 to 20 % respectively of the total consumption of carbon bearing sources per ton of product of pellets. , Claims:We Claim:
1. A system for iron ore pellet production for steel plants and the like comprising:
Feed bins for pelletization raw materials including raw additive and fuel bin (16205);
said raw additive and fuel bin (16205) comprising of a coke breeze discharge section (106) and/or coke dry quenching unit based waste CDQ dust particles/ fines discharge section (110);
said raw additive and fuel bin (16205) operatively connected to coke conveyor (200) for supply of coke /coke breeze and CDQ fine through supply line (102) provided with pneumatically controlled feeding of said waste CDQ dust particles/fines into said raw additive and fuel bin (16205);
said coke breeze discharge section (106) and said waste CDQ particle/fines discharge sections (110) having means for selective controlled feed of the respective coke breeze along with said CDQ fines or only said CDQ fines through respective sections;
said waste CDQ particles/fines discharge section including valve means including Rotary Air Valve (RAV)(112) means for controlling flow rate and flushing of the CDQ dust particles supply to pelletization process without said coke breeze from said raw additive and fuel bin for use in pelletization.

2. The system for iron ore pellet production for steel plants and the like as claimed in claim 1 wherein
said coke breeze discharge section (106) is provided with a knife edge gate (108) to handle flow of the coke breeze along with said waste CDQ dust particles/fines supply to the pelletization process, and, said waste CDQ dust particles/ fines discharge section supply through said RAV (112) independently;
said raw additive and fuel bin (16205) top portion is equipped with baghouse (116) through operative bag house duct line (114);
said waste CDQ fines/particles from various sources as collected is stored in ground level portable storage /tanker (100) providing for enclosed storage;
said enclosed storage of collected waste CDQ fines/particles including operative connections to compressed air supply line (104), material supply pipeline (102) for pneumatically supplying the CDQ to said raw additive and fuel bin (16205) disposed above said ground level of said enclosed storage of said collected waste CDQ fines/particles (100).

3. The system for iron ore pellet production for steel plants and the like as claimed in claims 1 or 2 wherein said
raw additive and fuel bin (16205) with discharge section (110) as bin chute allows storage and/or controlled addition/pumping of waste carbon fines/carbon dust/CDQ dust generated in coke dry quenching (CDQ) units of steel plant, to weigh Belt Feeder AF5 (202) through pneumatically controlled pumping means,
said pneumatically controlled feeding/supplying including:
compressed air line (104) fitted to a tanker (100) to impinge compressed air on waste carbon fines held in the tanker (100) so as to pump said waste carbon fines through waste carbon fine materials line (102) connected with top portion of the raw additive and fuel bin (16205), and,
rotary air valve (RAV) (112) fitted at cone base of said bin chute thereby enabling pneumatically controlled precise pumping discharge and flow of said waste carbon fines to said weigh Belt Feeder AF5 (202) and finally to additive grinding ball mill.

4. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-3 wherein
said raw additive and fuel bin (16205) with bin chute is configured into portions based on dividing bin chute into two halves (110) and (106) allowing storage for controlled addition/pumping of waste carbon fines/dust generated in coke dry quenching (CDQ) units of steel plant, to said weigh Belt Feeder AF5 (202) through said pneumatically controlled pumping means,
said rotary air valve (RAV) (112) is fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) with the other half portion (106) of said bin chute attached with knife edge gate (108) adapted to enable pneumatically controlled & non-simultaneous sequential pumping discharge of said waste carbon fines & coke breeze particles along with waste carbon fines respectively from said half portions of bin chute into said weigh Belt Feeder AF5 (202) and finally into additive grinding ball mill for iron ore pellet making.
5. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-4 wherein said rotary air valve (112) fitted at cone base of said bin chute or fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) is adapted to control, precisely measure flow rate of waste carbon fines and also arrest flushing of said waste carbon fines.

6. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-5 wherein said rotary air valve (RAV) (112) fitted at cone base of one half portion (110) of the bin chute of said raw additive and fuel bin (16205) with the other half portion (106) of said bin chute attached with knife edge gate (108) allows sequential discharge of materials such that knife edge gate assisted portion of bin chute enables discharge of coke breeze fines along with waste carbon fines and RAV (112) assisted portion of bin chute enables discharge of waste carbon fines.

7. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-6 wherein discharge from said half portions of bin chute of said raw additive and fuel bin (16205) is lead to weigh Belt Feeder AF5 (202) and forward to additive feed conveyer AF9 (206) and thereafter to lime stone and additive grinding ball mill of iron ore pellet production unit, with said Weigh Belt Feeder AF5 (202) being disposed at a distance (400) at higher level from said floor area (302).

8. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-7 wherein said raw additive and fuel bin (16205) is disposed between Bentonite grinding feed bin (16231-1) and Lime stone grinding feed bin (16231-2), with said Bentonite grinding feed bin (16231-1) and raw additive and fuel bin (16205) adapted to receive materials from Bentonite and Coke Conveyer AF3 (200), and, said Lime stone grinding feed bin (16231-2) is adapted to discharge materials to additive feed conveyer AF9 (206) via Weigh belt feeder AF6 (204).

9. The system for iron ore pellet production for steel plants and the like as claimed in claims 1-8 wherein said waste carbon fines/carbon dust filled tanker (100) lies on the ground level (300) below the floor area (302); said system enabling production of hematite iron ore pellets based on the utilization of waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines functioning as in-situ carbon source with superior properties superior to ones produced with coke breeze fines.

10. A process for the production of green iron ore pellets selectively including waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines by involving the system as claimed in claims 1-9 comprising the steps of
(a) providing waste carbon fines/carbon dust/CDQ dust of varied sizes from their generating units in a ground level portable storage /tanker operatively connected to said raw additive and fuel bin;

(b) providing source of coke /coke breeze operatively connected to said raw additive and fuel bin;

(c) providing supply of lime stone to a lime stone grinding feed bin;

(d) pumping said waste carbon fines/carbon dust/CDQ dust from storage /tanker into said raw additive and fuel bin (16205) including said coke breeze discharge section and/or said waste CDQ particle/fines discharge sections, with said bin placed at a higher height and operatively connected to said storage tanker through said operating line (102) aiding pneumatically controlled pumping involving compressed air;
(e) selectively discharging said waste carbon fines/carbon dust/CDQ dust from said waste CDQ particle/fines discharge sections or said coke breeze along with said waste CDQ particle/fines from said coke breeze and waste CDQ particle/fines discharge sections for pelletization involving said waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines.

11. The process as claimed in claim 10 wherein
said step (a) includes collecting waste carbon fines/carbon dust/CDQ dust of varied sizes from their generating units and assessing through laboratory studies on their suitability for iron ore pelletization;

in said step (d) during pneumatically pumping finer dust particles gets collected in bag house (116);
in said step (e) during selectively discharging said waste carbon fines to said weigh Belt Feeder AF5 (202) and finally to additive grinding ball mill via rotary air valve (RAV) (112) fitted at cone base of said bin chute thereby enables pneumatically controlled precise pumping discharge and flow of said waste carbon fines for iron ore pellet making.

12. The process as claimed in claims 10 or 11 wherein
when the raw additive and fuel bin (16205) chute is divided into two halve portions then the waste carbon fines/carbon dust/CDQ dust is discharged with the aid of rotary air valve (RAV) (112) to which portion the valve is fitted so that said waste carbon fine discharge is precisely controlled, with precisely measured flow rate of waste carbon fines also arresting flushing of said waste carbon fines,
and,
conventional coke breeze particles along with CDQ dust are discharged from the other half portion of bin chute fitted with a knife edge gate (108) thereby passing discharges from both the portions of the chute bin to the weigh Belt Feeder AF5 (202) and after wards passing the discharges to Additive feed conveyer AF9 (206) that finally goes to lime stone and additive grinding ball mill for iron ore pellet making.

13. Iron ore pellets as green iron ore pellets including waste carbon fines/carbon dust/CDQ dust as 0 to 100 % replacement of conventional coke breeze fines said pellets comprising 80-100% content of waste carbon fines/carbon dust/CDQ dust as carbon bearing source with unfired pellets reducing to 1.38 % from 1.52 % when said CDQ dust content is increased to 80-100 % from 0-20% of the specific consumption of fuel sources in the product pellets.
14. Iron ore pellets as claimed in claim 13 wherein 80-100% increased CDQ dust content in said pellets as compared to 0-20 % CDQ dust content enables the following:
improved average AI (abrasion index) of fired pellets improved to 4.36 % from 4.52 %;
improved average CCS (cold crushing strength) of the fired pellets improved to 298 Kg/pellet from 280 Kg/pellet;
average TI (tumbler index) of fired pellets improved to 94.57 % from 94.3 %.

Dated this the 31st day of July, 2023 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)
IN/PA-199