Title of Invention	METHOD OF PREPARING A COAL CHARGE BLEND WITH DESIRED HOMOGENEITY FOR CARBONIZATION
Abstract	A method of preparing coal charge blend for carbonization and to particular, to preparation of a coal charge blend directed to obtaining proper blend homogeneity and reduced micofines generation in the coal blend for effective and productive carbonization. Advantageously, the invention involves determining the Hard Groove Grindability Index (HGI) of input coals and subjecting the input coals to differential crushing based on the said Hard Groove Grindability index to thereby crush the input coal varieties selectively to obtain a proper coal blend homogeneity and reduced micro fines in the coal blend for carbonization. The method improves bulk density of coal charge blend and also increase the abrasion strength of coke obtained on carbonization thereby enhancing blast furnace productivity. The invention avoids limitations of conventional coal charge preparation and carbonization resulting from varying characteristics of input coals and is directed to improve productivity and provide for a more controlled and cost effective generation of coke.

Title of Invention

METHOD OF PREPARING A COAL CHARGE BLEND WITH DESIRED HOMOGENEITY FOR CARBONIZATION

Abstract

A method of preparing coal charge blend for carbonization and to particular, to preparation of a coal charge blend directed to obtaining proper blend homogeneity and reduced micofines generation in the coal blend for effective and productive carbonization. Advantageously, the invention involves determining the Hard Groove Grindability Index (HGI) of input coals and subjecting the input coals to differential crushing based on the said Hard Groove Grindability index to thereby crush the input coal varieties selectively to obtain a proper coal blend homogeneity and reduced micro fines in the coal blend for carbonization. The method improves bulk density of coal charge blend and also increase the abrasion strength of coke obtained on carbonization thereby enhancing blast furnace productivity. The invention avoids limitations of conventional coal charge preparation and carbonization resulting from varying characteristics of input coals and is directed to improve productivity and provide for a more controlled and cost effective generation of coke.

Full Text	FIELD OF THE INVENTION The present invention relates to a method of preparing coal charge blend for carbonization and, in particular, to preparation of a coal charge blend directed to obtaining proper blend homogeneity and reduced micofines generation in the coal blend for effective and productive carbonization. The invention is also directed to improve bulk density of coal ctarge blend and also increase the abrasion streingth of coke obtained on carbonization thereby enhanong blast furnace productivity. The mvention thus avoids limitations of conventional coal charge preparation and carbonization resulting from varying charastistics of input coats and is directed to improve productivity and provide for a more controlled and cost effective generation of coke. BACKGROUND ART It is well known that for carbonization of coal the coal charge bfend is prepared and subsequently subjected to the carbonization such as in slot type ovens Usually, tne conventional practice of coal preparation for carbonization comprises mixing of input coals in adequate proportion and crushing to predetermine degree of fineness (82+/-2% below 3.2mm). It is experienced that the input coal for such coaf preparation for carbonization vary widely in size, grindability as well as quality parameters. This results in improper blend homogeneity and excessive microfines ( Thus the crushed change usually contain higher coarser size fraction (+6 3mm of 8-10%) and microfines in the range of about 50-55%. Due to such varying characteristics of coal bfend the coke obtained from carbonization shows poor abrasion strength properties (M- to) resulting higher coke consumption and lower blast furnace productivity. It would be dearly apparent from the above that presently followed processes of coal preparation for carbonization does not therefore address to the need for desired homogeneity of coal blend which is usually sourced from variety of sources of varying qualities of grain size, distribution and fines content. Such improper blend of the available coal charge is found to affect productivity with higher coke consumption and less productivity, which in turn also make the process of carbonization cost extensive Moreover, the coke obtained following use of such improper coal blend also have poor abrasion strength properties, which contribute towards higher coke consumption. It is, therefore, evident from the above conventional state of the art that the presently followed method of random mixing and crushing the input coals together result in non- homogeneity and excess fines generation since softer coals get crushed to a higher 2 degree than the harder ones. This necessarily affects the carbonization and coke characteristics as well as the productivity of the blast furnace. OBJECTS OF THE INVENTION It is thus the baste object of the present invention to provide for a process of preparing coal blend for carbonization which would take care of the afore discussed problems and complexities of having randomly mixed coal blend of different sources of vaned qualities which lead to improper blend homogeneity and affected productivity Another object of the present invention is directed to a method of coal blend for carbonization, which would enable generation of coal blend with desired homogeneity and reduced miorofines generation. Another object of the present invention is directed to provide for a method of preparing of coal blend from different sources of vaned qualities of coal which would have optimum grain size distribution and fines content. A further object of the present invention is directed to a methodology for coal preparation based on hard groove grindabilrty index (HGI) indlces of input coals so as to obtain proper blend homogeneity and reduced microfine generation in the preparation of coal blend. A further object of the present invention is directed to a methodology of coal biend preparation based on gnndability characteristic of input coal from variety of sources which is determinant of an intrinsic property and guided by nature and quality (structure, bonding etc) which can vary from coal to coal. Vet further object of the present invention is directed to a process of coal preparation for carbonization which would provide for much desired flexibility in choosing the biend, maintaining homogeneity and improvement in bulk density of coal charge blend. A further object of the present invention in directed to enhancing coal utilization and blast furnace productivity by way of providing a selective process of coal preparation having optimum gram size distribution and fines content with improved bulk density of coal charge which would favour increasing the abrasion strength of coke (M10) obtained on carbonizing the blend with enhanced blast furnace productivity. 3 SUMMARY OF THE INVENTION Thus according to the basic aspect of the present Invention there is provided a method of preparing a coal charge blend with desired hwnogeneity for carbontration comprising, determining the Hard Groove Grindability Index (HGI) of input coals; subjecting the input coals to differential crushing based on the said Hard Groove Grindability Index to thereby crash the input coal varieties selectively to obtain a proper coal blend homogeneity and reduced micro fines in the coal blend far carbonization Importantly, in the above process the input coals are divided into different categories for selective differential crushing based on the grindabiltty indices (HGI), content of coarse size (+ 6.3 mm) and fines (- 0 6mm) size fractions of incoming coals. The differential crushing of the input coal varieties are tarrid out such as to obtain optimum toke quality (strength). In accordance with a preferred aspect of the present invention the categorizing of the input coals is done into three categories comprising Category I being coal harder to crush and required to be crushed to a higher degree of fineness Category III being coals representing varieties softer to crush and required to be crushed to a lower degree of fineness and an intermediate Category II being coal varieties which can be accommodated in either Category I or Category III as per the plant logistics and end requirements. Thus to the above process of the invention the incoming coal varieties are categorized selectively based on their properties including structure, bonding, HGI, content of coarse and fine fractions, caking and coking characteristics. After the above categorization of the incoming coal varieties the same are subjected to differential crushing comprising using a set of crushers where the grouped/categorized coats are crushed differentially selected from high, medium and coarse degree In accordance with another aspect of the present invention there is provided a method of coal carbonization such as in slot type ovens comprising: 4 (a) Preparing a substantially homogeneous coal charges blend following determining the Hard Groove Grindability Index (HGI) of input coals and subjecting the input coals to differential cashing based on the said Hard Groove Grindability index to thereby crush the input coal varieties setectively to obtain a proper coal blend homogeneity and reduced micro fines; and (b) Subjecting the thus obtained proper coal blend of step (i) above to improved and mare productive carbonization of coal. Preferably, in the above method in step (a) above, the input coals are divided into different categories for selective differential crushing based selectively on the grindability indices (HGI), content of coarse size (+ 6.3 mm) and fines (- 0 6mm) size fractions of incoming coals. Also, the said step (a) of differential crushing of input coat is carred out to Improve the bulk density of the coal charge biend and also to increase the abrasion strength of coke (M10) obtained on carbocruzation to enhance blast firnace productivity It Is thus possible by way of the above method of the invention to provide for methodology for coal preparation directed to improved productivity in carbonization process by way of crushing the available sources of input coal selectively in groups based on hard groove grindability index (HGI) of input coals to get to proper blend homogeneity and reduce microfine generation Importantly, the above method of invention takes care of the required vanation of grindability of variety of coals such grindability being an intrinsic property and guided by nature and quality such as structure, bonding etc. The invention is therefore basically directed to grouping) of input coats having similar grindability indices and crushing to the denned degree of fineness. This provides for the much required control on blend homogeneity as well as generation of fines. Such a process of invention therefore avoids the problems of conventional method of random mixing and crushing the input coals together resulting in non-homogeneity and excess fine generation since softer coals usually get crushed to a higher degree than the harder ones. In accordance with the preferred aspect the method of the invention involves dividing the input coals into different categories preferably 2-3 categories for crushing based on grindability indices (HGI), content of coarse size (+6.3mm) and fines (-0 6mm) size fraction of incoming coals. The method therefore achieves controlling the coarse size as 5 well fines content by crushing differentially based on the input quality parameters allowing optimum blend preparation towards achieving optimal coke quality (strength). Importantly, the method of the invention achieves the much desired flexibility in choosing the blend, maintaining homogeneity and improvetnent in bulk density of coal chargt btend. The details of the invention, its object and advantages are explained hereunder in greater detail in relation to non-limiting exemplary illustration as per the following accompanying figure: BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE Figure 1: is an illustration of differential crushing scheme of the input coals in the process of preparation of the coal blend in accordance with the present invention. Reference is invited to figure 1 which schematically illustrates the division of the input coals based on the coal characteristic of the available varieties in particular the hard groove grindability index (HGI), content of coarse and fine fraction, caking and coking etc to obtain the optimum blend homogenerty, composition and coke quality. As dlearly represented in the said figure for such purpose the input coals can preferably be divided into three categories. The above categorisation is basically in terms of two extreme varieties such as, Category Category III and I. Category I being coals, which are harder to crush and which require crushing to a hiqher degree of fineness. Category III being representative of the input coal variety, which are softer to crush and which require crushing to a lower degree of fineness. The intennediate ones can ne tategonzed as Category III which could be sent or grouped in either of Category I or Caregory III based on the plant logistics end requiremente. Preferably, the input coals can be divided into different categories for crushing based on the grindability indices, content of coarse size (+6 3mm) and fines (- 0.6mrn ) size fraction of incoming coals as further detailed in Table 1 hereunder: TABlE1 Category HGI(Range) Size Content+6mm,% -0.6mm % I 50-60 45-65 10-25 II 60-00 30-45 25-50 80-120 10-30 50-75 6 in this way the optimum blend homogeneity and fines content in the coal blend can be effectively and advantageously controlled and flexibility imparted to coal blend preparation for effective carbonization After the input coats are categorized in groups as above they are sent to set of crushers where the grouped coals are envied differentially (Crushed to high, medium and coarse degree). The prepared charge blend can be subsequently carbonized and the resultant coke obtained. A comparative study of the advantages in abrasion strength (M10) of coke obtained foltowng the above coal preparation in accordance with the invention involving differential crushing and the coal blend involving conventional random crushing was carried out and the results are further illustrated in following Table 2. TABLE 2 Coal blend sizefraction Conventional crushing Differentialcrashing +6.3 mm 8.5 7-0 -0.6 mm 53.4 46.9 -3.2 mm 81.8 83.1 Abrasion strength ofcoke M10 9.1 8-8 It would be dearly apparent from the above that the process of the invention including the selective coal preparation for carbonization is found to improve bulk density of coal charge blend as well as increase the abrasion strength of coke (M10) obtained on carbonization of the blend to -slot oven for enhancing blast furnace productivity. It is thus possible by way of present invention to characterize the Input coals (from available sources) in terms of grmdability indices, content of coarse (+6.3mm) and fine fraction (+0.6mm) and caking and coking properties and subject the thus categorized input coals to differential crushing to reach to the proper homogeneous blend with reduced microfines for effective carbonization with improved coke quality (Abrasion Resistance). 7 WE CLAIM- 1. A method of preparing a coal charge blend with desired homogeneity for carbonization comprising: determining the Hard Groove Grindability index (HGI) of input coals, subjecting the input coals to differential crushing based on the said Hard Gioove Grindability index to thereby crush the input coal varieties selectively to obtain 3 proper coal blend homogeneity and reduced micro fines in the coal blend for effective carbonization, 2 A method of preparing a coal change blend for carbonization as claimed in claim 1 wherein the input coals are divided mto different categories for selective differentiai crushing based on the grindability indices (HGI), content of coarse stze (+ 6.3 mm) and fines (- 0.6mm) size, fractions of incoming coals 3. A method of preparing a coal charge blend for carbonization as clainted in anyone of daims 1 or 2 wherein the drfferential crushing of the input coal vaneties are carried, out such as to obtain optimum coke quatity (strength), 4. A method of pteparing a coal charge blend for carbonization as claimed in anyone of claims l to 3 comprising categorizing the input coals tnto three categories comprising Category I being coals harder to crush and required to be crushed to a higher degree of fineness Category III being coals representing vaneties softer to crush and required to be crushed to a lower degree of fineness and an intermediate Category II being coal varieties which can be accommodated in either Category I or Category III as per the plant logistics and end requirements 5 A mented of preparing a coal charge blend for carbonization as claimed in anyone of claims 1 to 4 wherein the incoming coal varieties are categorized selectively based on their properties including structure, bonding, HGI, content of coarse and fine fractions, caking and coking characteristics 6. A method of preparing a coal charge blend for carbonitzation as claimed in anyone of claims 1 to 5 comprising using a set of crushers where the grouped/categorized coals are crushed differentially selected from high, medium and coarse degree 8 7, A method of coal carbonization such as in slot type ovens comprising: (a) preparing a substantially homogeneous coal charge blend following determining the Hard Groove Gnndability Index (HGL) of input coats and subjecting the input coals to differential crushing based on the said Hard Groove Grindability Index to thereby crush the input coal varieties selectively to obtain a proper coal blend homogeneity end reduced micro fines, and (b) subjecting the thus obtained proper coal blend of step (i) above to improved and more produdtive carbonization of coal. 8. P method of coal carbonization as claimed in claim 7 wherein in step (a) above the input coals are divided into different categories for selective differential crushing based selectively on the grindability indices (HGI), content of coarse size (+ 6.3 mm) and fines (- 0,6mm) size fractions of incoming coals 9. A method of coal carbonization as claimed in anyone of claims 7 or 8 vvlnerein the sard step (a) of differential crushing of fnput coal is carried out to improve the bulk density of the coal charge blend and also to increase the abrasion strength of coke (M10) Obtained on carbonization to enhance blast furnace productivity. 10. a method of preparing a coal charge blend for carbonization and 3 method of coal carbonization substantially as herein described and illustrated with reference to the accompanying examples/figures. 9 A method of preparing coal charge blend for carbonization and to particular, to preparation of a coal charge blend directed to obtaining proper blend homogeneity and reduced micofines generation in the coal blend for effective and productive carbonization. Advantageously, the invention involves determining the Hard Groove Grindability Index (HGI) of input coals and subjecting the input coals to differential crushing based on the said Hard Groove Grindability index to thereby crush the input coal varieties selectively to obtain a proper coal blend homogeneity and reduced micro fines in the coal blend for carbonization. The method improves bulk density of coal charge blend and also increase the abrasion strength of coke obtained on carbonization thereby enhancing blast furnace productivity. The invention avoids limitations of conventional coal charge preparation and carbonization resulting from varying characteristics of input coals and is directed to improve productivity and provide for a more controlled and cost effective generation of coke.

Full Text

FIELD OF THE INVENTION
The present invention relates to a method of preparing coal charge blend for
carbonization and, in particular, to preparation of a coal charge blend directed to
obtaining proper blend homogeneity and reduced micofines generation in the coal blend
for effective and productive carbonization. The invention is also directed to improve bulk
density of coal ctarge blend and also increase the abrasion streingth of coke obtained on
carbonization thereby enhanong blast furnace productivity. The mvention thus avoids
limitations of conventional coal charge preparation and carbonization resulting from
varying charastistics of input coats and is directed to improve productivity and provide
for a more controlled and cost effective generation of coke.
BACKGROUND ART
It is well known that for carbonization of coal the coal charge bfend is prepared and
subsequently subjected to the carbonization such as in slot type ovens
Usually, tne conventional practice of coal preparation for carbonization comprises mixing
of input coals in adequate proportion and crushing to predetermine degree of fineness
(82+/-2% below 3.2mm). It is experienced that the input coal for such coaf preparation
for carbonization vary widely in size, grindability as well as quality parameters. This
results in improper blend homogeneity and excessive microfines ( Thus the crushed change usually contain higher coarser size fraction (+6 3mm of 8-10%)
and microfines in the range of about 50-55%. Due to such varying characteristics of coal
bfend the coke obtained from carbonization shows poor abrasion strength properties (M-
to) resulting higher coke consumption and lower blast furnace productivity.
It would be dearly apparent from the above that presently followed processes of coal
preparation for carbonization does not therefore address to the need for desired
homogeneity of coal blend which is usually sourced from variety of sources of varying
qualities of grain size, distribution and fines content. Such improper blend of the
available coal charge is found to affect productivity with higher coke consumption and
less productivity, which in turn also make the process of carbonization cost extensive
Moreover, the coke obtained following use of such improper coal blend also have poor
abrasion strength properties, which contribute towards higher coke consumption. It is,
therefore, evident from the above conventional state of the art that the presently
followed method of random mixing and crushing the input coals together result in non-
homogeneity and excess fines generation since softer coals get crushed to a higher
2

degree than the harder ones. This necessarily affects the carbonization and coke
characteristics as well as the productivity of the blast furnace.
OBJECTS OF THE INVENTION
It is thus the baste object of the present invention to provide for a process of preparing
coal blend for carbonization which would take care of the afore discussed problems and
complexities of having randomly mixed coal blend of different sources of vaned qualities
which lead to improper blend homogeneity and affected productivity
Another object of the present invention is directed to a method of coal blend for
carbonization, which would enable generation of coal blend with desired homogeneity
and reduced miorofines generation.
Another object of the present invention is directed to provide for a method of preparing
of coal blend from different sources of vaned qualities of coal which would have optimum
grain size distribution and fines content.
A further object of the present invention is directed to a methodology for coal
preparation based on hard groove grindabilrty index (HGI) indlces of input coals so as to
obtain proper blend homogeneity and reduced microfine generation in the preparation of
coal blend.
A further object of the present invention is directed to a methodology of coal biend
preparation based on gnndability characteristic of input coal from variety of sources
which is determinant of an intrinsic property and guided by nature and quality
(structure, bonding etc) which can vary from coal to coal.
Vet further object of the present invention is directed to a process of coal preparation for
carbonization which would provide for much desired flexibility in choosing the biend,
maintaining homogeneity and improvement in bulk density of coal charge blend.
A further object of the present invention in directed to enhancing coal utilization and
blast furnace productivity by way of providing a selective process of coal preparation
having optimum gram size distribution and fines content with improved bulk density of
coal charge which would favour increasing the abrasion strength of coke (M10) obtained
on carbonizing the blend with enhanced blast furnace productivity.
3

SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present Invention there is provided a method of
preparing a coal charge blend with desired hwnogeneity for carbontration comprising,
determining the Hard Groove Grindability Index (HGI) of input coals;
subjecting the input coals to differential crushing based on the said Hard Groove
Grindability Index to thereby crash the input coal varieties selectively to obtain a proper
coal blend homogeneity and reduced micro fines in the coal blend far carbonization
Importantly, in the above process the input coals are divided into different categories for
selective differential crushing based on the grindabiltty indices (HGI), content of coarse
size (+ 6.3 mm) and fines (- 0 6mm) size fractions of incoming coals. The differential
crushing of the input coal varieties are tarrid out such as to obtain optimum toke
quality (strength).
In accordance with a preferred aspect of the present invention the categorizing of the
input coals is done into three categories comprising Category I being coal harder to
crush and required to be crushed to a higher degree of fineness Category III being coals
representing varieties softer to crush and required to be crushed to a lower degree of
fineness and an intermediate Category II being coal varieties which can be
accommodated in either Category I or Category III as per the plant logistics and end
requirements.
Thus to the above process of the invention the incoming coal varieties are categorized
selectively based on their properties including structure, bonding, HGI, content of coarse
and fine fractions, caking and coking characteristics.
After the above categorization of the incoming coal varieties the same are subjected to
differential crushing comprising using a set of crushers where the grouped/categorized
coats are crushed differentially selected from high, medium and coarse degree
In accordance with another aspect of the present invention there is provided a method of
coal carbonization such as in slot type ovens comprising:
4

(a) Preparing a substantially homogeneous coal charges blend following
determining the Hard Groove Grindability Index (HGI) of input coals and
subjecting the input coals to differential cashing based on the said Hard
Groove Grindability index to thereby crush the input coal varieties
setectively to obtain a proper coal blend homogeneity and reduced micro
fines; and
(b) Subjecting the thus obtained proper coal blend of step (i) above to improved
and mare productive carbonization of coal.
Preferably, in the above method in step (a) above, the input coals are divided into
different categories for selective differential crushing based selectively on the grindability
indices (HGI), content of coarse size (+ 6.3 mm) and fines (- 0 6mm) size fractions of
incoming coals.
Also, the said step (a) of differential crushing of input coat is carred out to Improve the
bulk density of the coal charge biend and also to increase the abrasion strength of coke
(M10) obtained on carbocruzation to enhance blast firnace productivity
It Is thus possible by way of the above method of the invention to provide for
methodology for coal preparation directed to improved productivity in carbonization
process by way of crushing the available sources of input coal selectively in groups based
on hard groove grindability index (HGI) of input coals to get to proper blend
homogeneity and reduce microfine generation
Importantly, the above method of invention takes care of the required vanation of
grindability of variety of coals such grindability being an intrinsic property and guided by
nature and quality such as structure, bonding etc. The invention is therefore basically
directed to grouping) of input coats having similar grindability indices and crushing to the
denned degree of fineness. This provides for the much required control on blend
homogeneity as well as generation of fines. Such a process of invention therefore avoids
the problems of conventional method of random mixing and crushing the input coals
together resulting in non-homogeneity and excess fine generation since softer coals
usually get crushed to a higher degree than the harder ones.
In accordance with the preferred aspect the method of the invention involves dividing
the input coals into different categories preferably 2-3 categories for crushing based on
grindability indices (HGI), content of coarse size (+6.3mm) and fines (-0 6mm) size
fraction of incoming coals. The method therefore achieves controlling the coarse size as
5

well fines content by crushing differentially based on the input quality parameters
allowing optimum blend preparation towards achieving optimal coke quality (strength).
Importantly, the method of the invention achieves the much desired flexibility in
choosing the blend, maintaining homogeneity and improvetnent in bulk density of coal
chargt btend.
The details of the invention, its object and advantages are explained hereunder in
greater detail in relation to non-limiting exemplary illustration as per the following
accompanying figure:
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE
Figure 1: is an illustration of differential crushing scheme of the input coals in the
process of preparation of the coal blend in accordance with the present invention.
Reference is invited to figure 1 which schematically illustrates the division of the input
coals based on the coal characteristic of the available varieties in particular the hard
groove grindability index (HGI), content of coarse and fine fraction, caking and coking
etc to obtain the optimum blend homogenerty, composition and coke quality.
As dlearly represented in the said figure for such purpose the input coals can preferably
be divided into three categories.
The above categorisation is basically in terms of two extreme varieties such as, Category
Category III and I. Category I being coals, which are harder to crush and which require
crushing to a hiqher degree of fineness. Category III being representative of the input
coal variety, which are softer to crush and which require crushing to a lower degree of
fineness. The intennediate ones can ne tategonzed as Category III which could be sent
or grouped in either of Category I or Caregory III based on the plant logistics end
requiremente. Preferably, the input coals can be divided into different categories for
crushing based on the grindability indices, content of coarse size (+6 3mm) and fines (-
0.6mrn ) size fraction of incoming coals as further detailed in Table 1 hereunder:
TABlE1
Category HGI(Range) Size Content+6mm,% -0.6mm %
I 50-60 45-65 10-25
II 60-00 30-45 25-50
80-120 10-30 50-75
6

in this way the optimum blend homogeneity and fines content in the coal blend can be
effectively and advantageously controlled and flexibility imparted to coal blend
preparation for effective carbonization
After the input coats are categorized in groups as above they are sent to set of crushers
where the grouped coals are envied differentially (Crushed to high, medium and coarse
degree). The prepared charge blend can be subsequently carbonized and the resultant
coke obtained.
A comparative study of the advantages in abrasion strength (M10) of coke obtained
foltowng the above coal preparation in accordance with the invention involving
differential crushing and the coal blend involving conventional random crushing was
carried out and the results are further illustrated in following Table 2.
TABLE 2
Coal blend sizefraction Conventional crushing Differentialcrashing
+6.3 mm 8.5 7-0
-0.6 mm 53.4 46.9
-3.2 mm 81.8 83.1
Abrasion strength ofcoke M10 9.1 8-8
It would be dearly apparent from the above that the process of the invention including
the selective coal preparation for carbonization is found to improve bulk density of coal
charge blend as well as increase the abrasion strength of coke (M10) obtained on
carbonization of the blend to -slot oven for enhancing blast furnace productivity.
It is thus possible by way of present invention to characterize the Input coals (from
available sources) in terms of grmdability indices, content of coarse (+6.3mm) and fine
fraction (+0.6mm) and caking and coking properties and subject the thus categorized
input coals to differential crushing to reach to the proper homogeneous blend with
reduced microfines for effective carbonization with improved coke quality (Abrasion
Resistance).
7

WE CLAIM-
1. A method of preparing a coal charge blend with desired homogeneity for
carbonization comprising:
determining the Hard Groove Grindability index (HGI) of input coals,
subjecting the input coals to differential crushing based on the said Hard Gioove
Grindability index to thereby crush the input coal varieties selectively to obtain 3
proper coal blend homogeneity and reduced micro fines in the coal blend for
effective carbonization,
2 A method of preparing a coal change blend for carbonization as claimed in claim 1
wherein the input coals are divided mto different categories for selective
differentiai crushing based on the grindability indices (HGI), content of coarse stze
(+ 6.3 mm) and fines (- 0.6mm) size, fractions of incoming coals
3. A method of preparing a coal charge blend for carbonization as clainted in anyone
of daims 1 or 2 wherein the drfferential crushing of the input coal vaneties are
carried, out such as to obtain optimum coke quatity (strength),
4. A method of pteparing a coal charge blend for carbonization as claimed in anyone
of claims l to 3 comprising categorizing the input coals tnto three categories
comprising Category I being coals harder to crush and required to be crushed to a
higher degree of fineness Category III being coals representing vaneties softer to
crush and required to be crushed to a lower degree of fineness and an
intermediate Category II being coal varieties which can be accommodated in
either Category I or Category III as per the plant logistics and end requirements
5 A mented of preparing a coal charge blend for carbonization as claimed in anyone
of claims 1 to 4 wherein the incoming coal varieties are categorized selectively
based on their properties including structure, bonding, HGI, content of coarse and
fine fractions, caking and coking characteristics
6. A method of preparing a coal charge blend for carbonitzation as claimed in anyone
of claims 1 to 5 comprising using a set of crushers where the grouped/categorized
coals are crushed differentially selected from high, medium and coarse degree
8

7, A method of coal carbonization such as in slot type ovens comprising:
(a) preparing a substantially homogeneous coal charge blend following determining
the Hard Groove Gnndability Index (HGL) of input coats and subjecting the
input coals to differential crushing based on the said Hard Groove Grindability
Index to thereby crush the input coal varieties selectively to obtain a proper
coal blend homogeneity end reduced micro fines, and
(b) subjecting the thus obtained proper coal blend of step (i) above to improved
and more produdtive carbonization of coal.
8. P method of coal carbonization as claimed in claim 7 wherein in step (a) above the
input coals are divided into different categories for selective differential crushing
based selectively on the grindability indices (HGI), content of coarse size (+ 6.3
mm) and fines (- 0,6mm) size fractions of incoming coals
9. A method of coal carbonization as claimed in anyone of claims 7 or 8 vvlnerein the
sard step (a) of differential crushing of fnput coal is carried out to improve the bulk
density of the coal charge blend and also to increase the abrasion strength of coke
(M10) Obtained on carbonization to enhance blast furnace productivity.
10. a method of preparing a coal charge blend for carbonization and 3 method of coal
carbonization substantially as herein described and illustrated with reference to the
accompanying examples/figures.

9

A method of preparing coal charge blend for carbonization and to particular, to
preparation of a coal charge blend directed to obtaining proper blend homogeneity
and reduced micofines generation in the coal blend for effective and productive
carbonization. Advantageously, the invention involves determining the Hard Groove
Grindability Index (HGI) of input coals and subjecting the input coals to differential
crushing based on the said Hard Groove Grindability index to thereby crush the
input coal varieties selectively to obtain a proper coal blend homogeneity and
reduced micro fines in the coal blend for carbonization. The method improves bulk
density of coal charge blend and also increase the abrasion strength of coke
obtained on carbonization thereby enhancing blast furnace productivity. The
invention avoids limitations of conventional coal charge preparation and
carbonization resulting from varying characteristics of input coals and is directed to
improve productivity and provide for a more controlled and cost effective generation
of coke.

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Patent Number

268356

Indian Patent Application Number

145/KOL/2006

PG Journal Number

35/2015

Publication Date

28-Aug-2015

Grant Date

27-Aug-2015

Date of Filing

17-Feb-2006

Name of Patentee

STEEL AUTHORITY OF INDIA LIMITED

Applicant Address

RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, DORANDA, RANCHI-834002

Inventors:

#	Inventor's Name	Inventor's Address
1	SHARMA MITHILESH KUMAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002, STATE OF JHARKHAND, INDIA.
2	CHAUDHURI AMITA JYOTI	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002, STATE OF JHARKHAND, INDIA.
3	DAS ASIM KUMAR	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002, STATE OF JHARKHAND, INDIA.
4	PRASAD BADRI NARAYAN	RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, STEEL AUTHORITY OF INDIA LTD., RANCHI-834002, STATE OF JHARKHAND, INDIA.

PCT International Classification Number

C10B53

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA