Claims:We Claim:
1) A cross-linked polymer comprising a single unit structure represented by Formula I:
-(A-L-B)-
Formula I
wherein:
‘A’ is lignin;
‘B’ is coal tar;
‘L’ is a linker moiety connecting A and B;
and wherein ‘A’ and ‘B’ are further independently connected to each other through a cross-linking agent, a plasticizer, or both the cross-linking agent and the plasticizer.

2) The polymer as claimed in claim 1, wherein the linker moiety is a covalent linker.

3) The polymer as claimed in claim 1, wherein the linker moiety is a methylene moiety.

4) The polymer as claimed in claim 1, wherein the plasticizer is a poly alkylene glycol; and wherein the poly alkylene glycol is polyethylene glycol (PEG), polyglycerol, or a combination thereof.

5) The polymer as claimed in claim 1, wherein the cross-linking agent is hexamine or hexamethylenetetramine.

6) The polymer as claimed in claim 1, wherein the lignin comprises phenol moiety, phenolic derivative moiety, or combination thereof, and the coal tar comprises phenol moiety, phenolic derivative moiety, heterocyclic polycyclic aromatic hydrocarbon (PAH) moiety, or combinations thereof.

7) The polymer as claimed in any of the preceding claims, wherein the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, phenolic derivative, heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected by the covalent linker.

8) The polymer as claimed in claim 1, wherein ‘A’ and ‘B’ are connected to each other through the cross-linking agent, the plasticizer, or both the cross-linking agent and the plasticizer via. hydrogen bonding.

9) The polymer as claimed in any of the preceding claims, wherein the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, the phenolic derivative, the heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected to each other through the cross-linking agent, the plasticizer, or both the cross-linking agent and the plasticizer.

10) The polymer as claimed in any of the preceding claims, wherein A and B are connected to each other by hydrogen bonding independently via polyethylene glycol and hexamethylenetetramine.

11) The polymer as claimed in any of the preceding claims, wherein the phenol, the phenolic derivative, or combination thereof of the lignin and the heterocyclic polycyclic aromatic hydrocarbon (PAH) of the coal tar are connected to each other by: a) methylene linker, and b) hydrogen bonding independently via polyethylene glycol and hexamethylenetetramine, to form the polymer.

12) The polymer as claimed in claim 1, wherein the single unit structure of said polymer is represented by:

13) The polymer as claimed in any of the preceding claims, wherein the polymer comprises solid content of about 58% to 65%, fixed carbon of about 26% to 30% and moisture of about 0.75% to 0.95%, and has a viscosity of about 1500 cP to 3000 cP.

14) The polymer as claimed in any of the preceding claims, wherein the polymer comprises OH functional group of phenolic or phenolic derivative moiety, methylene (-CH2) bridges, aromatic C-H unit, aromatic C=C group, C-N stretching of hexamethylenetetramine and C-O group of lignin aromatic segments.

15) A process of synthesizing the cross-linked polymer as claimed in any of the claims 1 to 14, comprising:
a) reacting lignin and an aldehyde in presence of an alkali, and heating the reaction mixture;
b) adding coal tar to the reaction mixture; and
c) adding plasticizer and cross-linking agent.

16) The process as claimed in claim 15, wherein step a) comprises heating the mixture at a temperature of about 40? to 50°C for about 0.5 hours to 1 hour;
and wherein the lignin is at a concentration of about 1 wt% to 2 wt% and the aldehyde is at a concentration of about 15 wt% to 20 wt%.

17) The process as claimed in claim 15, wherein step b) comprises maintaining the reaction mixture at a temperature of about 65? to 75°C for about 1 hour to 2 hours;
and wherein the coal tar is added at a concentration of about 80 wt% to 100 wt%.

18) The process as claimed in claim 15, wherein step c) comprises heating at a temperature of about 85? to 90°C for about 1 hour to 2 hours;
and wherein the plasticizer is at a concentration of about 5 wt% to 8 wt% and the cross-linking agent is at a concentration of about 0.75 wt% to 1.5 wt%.

19) The process as claimed in claim 15, wherein the cross-linked polymer is formed in step c), and the process further comprises distilling out water formed during step c) and cooling the polymer product to room temperature.

20) The process as claimed in any of the claims 15 to 19, wherein the aldehyde is formaldehyde, paraformaldehyde, or a combination thereof;
the alkali is sodium hydroxide, potassium hydroxide, or a combination thereof;
the plasticizer is polyethylene glycol (PEG), polyglycerol, or a combination thereof, preferably polyethylene glycol (PEG); and
the cross-linking agent is hexamethylenetetramine or hexamine.

21) A blend for preparing metallurgical coke comprising coal and the polymer of any of the preceding claims 1 to 14.

22) A method for improving coking potential of coal, comprising preparing a blend by contacting the polymer of Formula I as claimed in any of the preceding claims 1 to 14 with the coal, to obtain the coal with improved coking potential.

23) The blend as claimed in claim 21 or the method as claimed in claim 22, wherein the polymer is at a concentration of about 0.7 to 1 wt% of the blend.

24) The blend as claimed in claim 21 or the method as claimed in claim 22, wherein the coal comprises non-coking coal (NCC) at a concentration of about 6 wt% to 16 wt% of the blend and coking coal (CC) at a concentration of about 84 wt% to 94 wt% of the blend.

25) The blend or the method as claimed in claim 24, wherein the coking coal (CC) comprises hard coking coal (HCC) at a concentration of about 35 wt% to 45 wt% and semi soft coal at a concentration of about 45 wt% to 55 wt%.

26) The blend as claimed in claim 21 or the method as claimed in claim 22, wherein the polymer improves crucible swelling number (CSN) and fluidity of the coal.

27) The blend as claimed in claim 21 or the method as claimed in claim 22, wherein the polymer improves coking potential of the coal by enabling accommodation of about 6 wt% to 16 wt% of non-coking coal when compared to less than 6 wt% of non-coking coal in the absence of the polymer.
, Description:TECHNICAL FIELD
The present disclosure relates to the field of metallurgy and polymer chemistry. The disclosure particularly relates to an organic polymer for enhancing coking potential of coal for use in production of metallurgical coke.

BACKGROUND OF THE DISCLOSURE
In blast furnace for production of pig iron, metallurgical coke plays a crucial role. It acts as a chemical reducing agent, a fuel as well as a crucial permeable support. Because of the various roles of coke in blast furnace and for smooth operation and high productivity in modern blast furnaces, strict physical and chemical characteristics of coke is mandatory.

Worldwide, due to the high price and inadequate stock of prime coking coal, use of higher amount of non-coking coal in blend is required to produce high-strength/high quality coke in steel industry. Particularly, a technology without compromising the coke quality consisting of higher ratio of non-coking coals is highly desirable. Lately, significant amount of research is going on to develop various additives which can enhance the coke quality from non-coking coal. However, there is still a dire need for alternate and efficient additives which can enhance the coking potential/property of non-coking coals. The present disclosure tries to address said need.

STATEMENT OF THE DISCLOSURE
The present disclosure relates to a cross-linked polymer, wherein single unit structure of said polymer is represented by Formula I:
-(A-L-B)-
Formula I
wherein:
‘A’ is lignin;
‘B’ is coal tar;
‘L’ is a linker moiety connecting A and B;
and wherein ‘A’ and ‘B’ are further independently connected to each other through a cross-linking agent, a plasticizer, or both the cross-linking agent and the plasticizer.

In some embodiments of the disclosure, the single unit structure of the above described polymer is represented by:

The present disclosure further relates to a process of synthesizing the cross-linked polymer as described above, comprising:
a) reacting lignin and an aldehyde in presence of an alkali, and heating the reaction mixture;
b) adding coal tar to the reaction mixture; and
c) adding plasticizer and cross-linking agent

The present disclosure also provides a blend for preparing metallurgical coke, said blend comprising coal and the polymer as described above.

The present disclosure further relates to a method for improving coking potential of coal, comprising preparing a blend by contacting the polymer of Formula I as described above with the coal, to obtain the coal with improved coking potential.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1 depicts schematic representation of synthesis of the present polymer (LIG-CTP).

Figure 2 provides Fourier-transform infrared spectroscopy (FTIR) spectra of the synthesized polymer (LIG-CTP).

DETAILED DESCRIPTION OF THE DISCLOSURE
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising” or “containing” or “has” or “having”, or “including but not limited to” wherever used, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Reference throughout this specification to “some embodiments”, “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in some embodiments”, “in one embodiment” or “in an embodiment” in various places throughout this specification may not necessarily all refer to the same embodiment. It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The term “about” as used herein encompasses variations of +/- 10% and more preferably +/- 5%, as such variations are appropriate for practicing the present invention.

A primary objective of the present disclosure is to synthesize polymeric additive to address the need of improving coking potential of non-coking coals, thereby enhancing the overall efficiency of metallurgical coke production.

Another objective of the present disclosure is to maximize the utilization of low grade non-coking coals in a coal blend for economical and efficient production of metallurgical coke. Particularly, the objective is to utilize maximum amount of non-coking coal in coal blend without deterioration of metallurgical coke properties.

Yet another objective of the present disclosure is to improve the swelling and fluidity of coal matrix by employing a polymeric additive during carbonization.

Accordingly, to meet the above objectives, an organic cross-linked polymeric additive derived from coal tar and lignin based precursors is provided by the present disclosure.

Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. Structurally, coal tar is a complex mixture of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds. Lignin is a class of complex organic polymers comprising cross-linked phenolic precursors.

Particularly, the present disclosure provides an organic cross-linked polymer comprising a single unit structure represented by Formula I:
-(A-L-B)-
Formula I
wherein:
‘A’ is lignin;
‘B’ is coal tar;
‘L’ is a linker moiety connecting A and B;
and wherein ‘A’ and ‘B’ are further independently connected to each other through a cross-linking agent, a plasticizer, or both the cross-linking agent and the plasticizer.

In some embodiments of the polymer, the linker moiety of the polymer is a covalent linker.

In some embodiments, said linker moiety is a methylene moiety. In some embodiments, said methylene linker moiety is derived through aldehyde selected from formaldehyde or paraformaldehyde when employed during the synthesis of present polymer.

In some embodiments of the polymer, the plasticizer is a poly alkylene glycol.

In some embodiments, the poly alkylene glycol is polyethylene glycol (PEG), polyglycerol, or a combination thereof.

In some embodiments, the plasticizer is polyethylene glycol (PEG).

In some embodiments of the polymer, the cross-linking agent is a heterocyclic organic compound.

In some embodiments of the polymer, the cross-linking agent is hexamine or hexamethylenetetramine.

In some embodiments of the polymer, the lignin comprises phenol moiety, phenolic derivative moiety, or a combination thereof.

In some embodiments of the polymer, the coal tar comprises phenol moiety, phenolic derivative moiety, heterocyclic polycyclic aromatic hydrocarbon (PAH) moiety, or combinations thereof.

In some embodiments of the polymer, the phenol, the phenolic derivative, or a combination thereof of the lignin, and the phenol, phenolic derivative, heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected by the covalent linker.

In some embodiments of the polymer, the phenol, the phenolic derivative, or a combination thereof of the lignin, and the phenol, phenolic derivative, heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected by methylene linker.

In some embodiments of the polymer, ‘A’ and ‘B’ are connected to each other through the cross-linking agent, the plasticizer, or both the cross-linking agent and the plasticizer via. hydrogen bonding.

In some embodiments of the polymer, ‘A’ and ‘B’ are connected to each other through both the cross-linking agent and the plasticizer via. hydrogen bonding.

In some embodiments of the polymer, ‘A’ and ‘B’ are connected to each other through polyethylene glycol and hexamethylenetetramine via. hydrogen bonding.

In some embodiments of the polymer, the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, the phenolic derivative, the heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected to each other through the cross-linking agent, the plasticizer, or both the cross-linking agent and the plasticizer.

In some embodiments of the polymer, the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, the phenolic derivative, the heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected to each other through both the cross-linking agent and the plasticizer.

In some embodiments of the polymer, the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, the phenolic derivative, the heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected to each other through both the cross-linking agent and the plasticizer via. hydrogen bonding.

In some embodiments, the phenol, the phenolic derivative, or combination thereof of the lignin and the phenol, the phenolic derivative, the heterocyclic polycyclic aromatic hydrocarbon (PAH) or combinations thereof of the coal tar are connected to each other through polyethylene glycol and hexamethylenetetramine via. hydrogen bonding.

In some embodiments of the polymer, A and B are connected to each other by hydrogen bonding independently via polyethylene glycol and hexamethylenetetramine.

In some embodiments of the polymer, A and B are connected to each other by:
a) methylene linker, and
b) hydrogen bonding independently via polyethylene glycol and hexamethylenetetramine, to form the polymer.

In some embodiments of the polymer, the phenol, the phenolic derivative, or combination thereof of the lignin and the heterocyclic polycyclic aromatic hydrocarbon (PAH) of the coal tar are connected to each other by:
a) methylene linker, and
b) hydrogen bonding independently via polyethylene glycol and hexamethylenetetramine, to form the polymer.

In some embodiments, the single unit structure of the above described polymer is represented by:

The present polymer comprises plurality (any number) of single unit structures/repeating units as represented above. A skilled person would understand that since coal tar is a mixture of different molecular weight based aromatic compounds and mixture of various molecular structures, it is not possible to determine the exact number of single unit structures (repeating units) present in the currently described lignin and coal tar based polymer of the disclosure.

In some embodiments, the polymer comprises solid content of about 58% to 65%, fixed carbon of about 26% to 30% and moisture of about 0.75% to 0.95%, and has a viscosity of about 1500 cP to 3000 cP.

In some embodiments, the polymer comprises OH functional group of phenolic or phenolic derivative moiety, methylene (-CH2) bridges, aromatic C-H unit, aromatic C=C group, C-N stretching of hexamethylenetetramine and C-O group of lignin aromatic segments.

The present disclosure further relates to a process of synthesizing the cross-linked polymer as described above, comprising:
a) reacting lignin and an aldehyde in presence of an alkali, and heating the reaction mixture;
b) adding coal tar to the reaction mixture; and
c) adding plasticizer and cross-linking agent.

In some embodiments of the above described process, step a) comprises heating the mixture at a temperature of about 40? to 50°C for about 0.5 hours to 1 hour.

In some embodiments of the above described process, the lignin is at a concentration of about 1 wt% to 2 wt% and the aldehyde is at a concentration of about 15 wt% to 20 wt%.

In some embodiments of the above described process, the lignin is at a concentration of about 1 wt% and the aldehyde is at a concentration of about 20 wt%.

In some embodiments of the above described process, step b) comprises maintaining the reaction mixture at a temperature of about 65? to 75°C for about 1 hour to 2 hours.

In some embodiments of the above described process, the coal tar is added at a concentration of about 80 wt% to 100 wt%.

In some embodiments of the above described process, the coal tar is added at a concentration of about 85 wt%.

In some embodiments of the above described process, step c) comprises heating at a temperature of about 85? to 90°C for about 1 hour to 2 hours.

In some embodiments of the above described process, the plasticizer is at a concentration of about 5 wt% to 8 wt% and the cross-linking agent is at a concentration of about 0.75 wt% to 1.5 wt%.

In some embodiments of the above described process, the plasticizer is at a concentration of about 6 wt% and the cross-linking agent is at a concentration of about 1 wt%.

In some embodiments of the above described process, the aldehyde employed is formaldehyde, paraformaldehyde, or a combination thereof.

In some embodiments of the above described process, the aldehyde is formaldehyde.

In some embodiments of the above described process, the alkali is sodium hydroxide, potassium hydroxide, or a combination thereof;

In some embodiments of the above described process, the plasticizer is polyethylene glycol (PEG), polyglycerol, or a combination thereof.

In some embodiments of the above described process, the plasticizer is polyethylene glycol (PEG).

In some embodiments of the above described process, the cross-linking agent is hexamethylenetetramine or hexamine.

In some embodiments of the above described process, the cross-linked polymer is formed in step c).

In some embodiments of the above described process, the process further comprises distilling out water formed during step c) and cooling the polymer product to room temperature.

In some embodiments of the present disclosure, the process of synthesizing the cross-linked polymer comprises:
a) reacting lignin and formaldehyde in presence of sodium hydroxide, and heating the reaction mixture;
b) adding coal tar to the reaction mixture;
c) adding polyethylene glycol (PEG) and hexamethylenetetramine to obtain the polymer; and
d) distilling out water formed during step c) and cooling the polymer product.

In some embodiments of the present disclosure, the process of synthesizing the cross-linked polymer comprises:
a) reacting lignin and formaldehyde in presence of sodium hydroxide, and heating the reaction mixture at a temperature of about 40? to 50°C for about 0.5 hours to 1 hour;
b) adding coal tar to the reaction mixture and maintaining the reaction mixture at a temperature of about 65? to 75°C for about 1 hour to 2 hours;
c) adding polyethylene glycol (PEG) and hexamethylenetetramine, and heating at a temperature of about 85? to 90°C for about 1 hour to 2 hours to obtain the polymer; and
d) distilling out water formed during step c) and cooling the polymer product to room temperature.

The present disclosure also provides a blend for preparing metallurgical coke, said blend comprising coal and the cross-linked polymer as described above.

In some embodiments of the blend, the polymer is at a concentration of about 0.7 to 1 wt% of the blend.

In some embodiments of the blend, the coal comprises non-coking coal (NCC) at a concentration of about 6 wt% to 16 wt% of the blend and coking coal (CC) at a concentration of about 84 wt% to 94 wt% of the blend.

In some embodiments of the blend, the coking coal (CC) comprises hard coking coal (HCC) at a concentration of about 35 wt% to 45 wt% and semi soft coal at a concentration of about 45 wt% to 55 wt%.

In some embodiments of the blend, the polymer improves crucible swelling number (CSN) and fluidity of the coal.

In some embodiments of the blend, the polymer improves coking potential of the coal by enabling accommodation of about 6 wt% to 16 wt% of non-coking coal when compared to less than 6 wt% of non-coking coal in the absence of the polymer.

The present disclosure also relates to a method for improving coking potential of coal, comprising preparing a blend by contacting the polymer of Formula I as described above with the coal, to obtain the coal with improved coking potential.

In some embodiments of the above described method for improving coking potential of coal, the polymer is at a concentration of about 0.7 to 1 wt% of the blend.

In some embodiments of the above described method for improving coking potential of coal, the coal comprises non-coking coal (NCC) at a concentration of about 6 wt% to 16 wt% of the blend and coking coal (CC) at a concentration of about 84 wt% to 94 wt% of the blend.

In some embodiments of the above described method for improving coking potential of coal, the coking coal (CC) comprises hard coking coal (HCC) at a concentration of about 35 wt% to 45 wt% and semi soft coal at a concentration of about 45 wt% to 55 wt%.

In some embodiments of the above described method for improving coking potential of coal, the polymer improves crucible swelling number (CSN) and fluidity of the coal.

In some embodiments of the above described method for improving coking potential of coal, the polymer improves coking potential of the coal by enabling accommodation of about 6 wt% to 16 wt% of non-coking coal when compared to less than 6 wt% of non-coking coal in the absence of the polymer.

The present disclosure further provides use of the cross-linked polymer as described above for improving coking potential of non-coking or inferior grade coal.

In some embodiments, use of the present polymer increases the efficiency of metallurgical coke making process.

In some embodiments, using the present polymer for metallurgical coke making comprises:
(i) synthesizing the lignin and coal tar based cross-linked polymer as described above;
(ii) mixing the polymer with coal blend; and
(iii) employing the coal blend in metallurgical coke making process.

Without wishing to be bound by any theory, the cross-linked lignin-coal tar based polymer of the present disclosure acts as an additive to improve coking potential of coal in the following manner:

It is well established that most significant range of temperature during coke making is 350°C to 550°C. In this temperature region, coal exists in the form of a plastic phase that finally resolidifies to give semi-coke. The polymeric additives play the role of plasticizing agent which reduces the viscosity of plastic phase to facilitate the mobility and ordering of the molecules into liquid crystals structures leading to the development of the anisotropic texture of coke. The appropriate characteristics of additives are aromaticity, alkyl substitution, heteroatoms and reactive functional group concentration and chemical compatibility with coal. The H-donor ability is also one of the important characteristics of additives for improving coking potential of non-coking coal during coke manufacturing.

In the cross-linked coal tar-lignin based polymeric additive of the present disclosure, effect of phenolic group of coal tar and lignin in presence of plasticizer (eg. polyethylene glycol) present in the polymeric additive plays a crucial role for donation of hydrogen inside the coal matrix during coke carbonization process. The transferable hydrogens released from the methylene (-CH2) unit of polymeric additive plays a crucial role for polycondensation reaction of coal structure in plastic phase at 350°C to 550°C temperature which is helpful for semi-coke structure formation. Also, p-p stacking interaction between delocalized aromatic structure of coal and well cross-linked aromatic polymeric structure present in the present polymer product is key factor role for coal-cake formation. Also, the presently synthesized cross-linked polymeric additive has higher boiling point (130 to 160?), and therefore more fraction of poly-aromatic hydrocarbons would contribute to co-fusing process during coke making. Consequently, the present polymeric additive improves the coal plastic property. This fact is further supported by the experimental study such as crucible swelling number (CSN) and fluidity test as demonstrated in the below examples. In addition, present polymeric additive has oxygen reached functional group which forms H-bonding with coal structure resulting in inhibition of volatilization of small aromatic clusters present in poor-coking coal. In addition, methylene bridge moiety (linker moiety) along with hexamine cross-linker present in the polymer structure provides desired free radical binding site and accelerates the re-aromatization process of coal structure at plastic phase through free radical mechanism resulting in structural ordering of semi-coke. In summary, the presence of -CH2 bridge polymeric structural chemistry of the present polymer, existence of phenolic -OH group and heterocyclic PAH moiety in modified coal tar and cross-linked aromatic networking of lignin as well as availability of H-bonding site in the polymer play crucial roles during carbonization of non-coking coal to achieve improved coking potential.

Thus, the present disclosure focusses on developing a cross-linked organic polymeric additive which can create new window in coke making industry through maximum utilization of inferior grade coal/non-coking coals as an alternative of prime coking coals. The present polymer is designed by cross-linking polymerization of coal tar and lignin based precursor through aldehyde (eg. formaldehyde) treatment in presence of cross-linker (hexamine) along with plasticizer (eg. polyethylene glycol). Coal tar is primarily selected as a raw material for the synthesis of present organic polymer because of its low-cost, sustainable availability at bulk scale in steel industry, and due to its interesting physical and chemical properties such as easy flowability, lower viscosity and presence of abundant aromatic constituents (eg. phenol and its derivative, and poly aromatic hydrocarbons). Further, lignin is an excellent candidate for chemical modifications/reactions due to its highly functional property (i.e. rich in phenolic groups) which increases its binding property as well as improves thermal stability. The synthesized coal tar-lignin based cross-linked polymer of the present disclosure can be added as an additive at lower amounts to enhance fluidity and swelling property of coal matrix. Particularly, the presently synthesized polymeric additive is effective at lower dosages (eg. 0.7% - 1%) to accommodate higher percentage (eg. 12-16%) of inferior/non-coking coal in the coal blend without deterioration of coke properties and thereby improves the Coke Strength after Reaction (CSR) as further observed from the carbonization study described in the forthcoming examples.

It is to be understood that the foregoing descriptive matter is illustrative of the disclosure and not a limitation. Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow. Further, to the extent not already indicated, it will be understood by those of ordinary skill in the art that any one of the various embodiments herein described and illustrated can be further modified to incorporate features shown in any of the other embodiments disclosed herein. In other words, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Further, it should be understood that this invention is not limited to the particular methodology, protocols, and reagents, etc., described herein and as such may vary. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention, which is defined solely by the claims.

As regards all the embodiments/examples characterized in this specification, in particular in the claims, it is intended that each embodiment mentioned in a dependent claim is combined with each embodiment of each claim (independent or dependent) said dependent claim depends from. As an example, in case of an independent claim 1 reciting 3 alternatives A, B and C, a dependent claim 2 reciting 3 alternatives D, E and F and a claim 3 depending from claims 1 and 2 and reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations: A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; and C, F, I, unless specifically mentioned otherwise.

Similarly, and also in those cases where independent and/or dependent claims do not recite alternatives, it is understood that if dependent claims refer back to a plurality of preceding claims or plurality of embodiments, any combination of subject-matter covered thereby is considered to be explicitly disclosed. For example, in case of an independent claim 1, a dependent claim 2 referring back to claim 1, and a dependent claim 3 referring back to both claims 2 and 1, it follows that the combination of the subject-matter of claims 3 and 1 is clearly and unambiguously disclosed as is the combination of the subject-matter of claims 3, 2 and 1. In case a further dependent claim 4 is present which refers to anyone of claims 1 to 3, it follows that the combination of the subject-matter of claims 4 and 1, of claims 4, 2 and 1, of claims 4, 3 and 1, as well as of claims 4, 3, 2 and 1 is clearly and unambiguously disclosed.

The above considerations apply mutatis mutandis to all claims and embodiments of the present specification. To give a few examples, the combination of claims 4, 6 and 1 is clearly and unambiguously envisaged in view of the claim structure/claimed subject-matter. The same applies for the combinations of claims 12, 10, 4 and 6, and, to give a few further examples which are not limiting, the combination of claims 13, 15, 17 and 18 and the combination of claims 24, 25 and 26.

Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for below examples illustrating the above described embodiments, and in order to illustrate the embodiments of the present disclosure certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the following examples should not be construed as limiting the scope of the embodiments herein.

INCORPORATION BY REFERENCE
All references, articles, publications, patents, patent publications, and patent applications (if any) cited herein are incorporated by reference in their entireties for all purposes. However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as, an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

EXAMPLES

Example 1: Synthesis of cross-linked polymer according to present disclosure
Lignin (about 1 to 2 wt %) is treated with formaldehyde monomer (about 15 to 20 wt %) in presence of sodium hydroxide (alkali medium) and heated at about 40°C to 50°C for about 0.5 hours 1 hour. Thereafter, low quinoline insoluble (Q.I)/low moisture based coal tar (about 80 to 100 wt %) is mixed with the reaction mixture and temperature is maintained at about 65°C to 75 °C for about 1 hour to 2 hours. Thereafter, specific amount of polyethylene glycol (plasticizing agent) at about 5 to 8 wt% is added into the reaction mixture followed by addition of hexamine (cross-linker) at about 0.75 to 1.5 wt%, and the mixture is again heated at about 85 to 90 °C for about 1 hour to 2 hours. Finally, the entire reaction mixture gets converted to a polymer product and the extra water formed during the reaction is distilled out. The cross-linked polymer product is cooled to room temperature. The synthesized product is marked as LIG-CTP and schematic representation is shown in Figure 1. The single unit structure of Formula I as described in the embodiments above is present in the LIG-CTP. During synthesis, crosslinking polymerization occurred between phenolic or phenolic derivative(s) of coal tar and lignin moiety and formaldehyde unit. Here, polyethylene glycol acts as a plasticizing agent and maintains the fluidity of the system. Also, H-bonding interaction between phenolic/heterocyclic PAH moiety of lignin/coal tar and hexamine cross-linker provides the desirable stability of the additive and forms a well cross-linked network structure.

Example 2: Characterization of the synthesized cross-linked polymer
Physical and chemical characteristics of the polymer
Physical and chemical properties of the synthesized lignin-coal tar based cross-linked polymer is described below:
Appearance: Black viscous homogeneous liquid
Nature: Adhesive
Solubility: Insoluble in water; soluble in DMF
Specific gravity (at 25 °C): 1.17
Viscosity (at 22 °C): 2500 cP
Solid Content: 62.96 %
Fixed Carbon: 27.5 %
Moisture Content: 0.92 %
Boiling Point: 130-160?

Structural characterization of the polymer (FTIR spectra):
The FTIR spectrum (Figure 2) of the synthesized polymer (LIG-CTP) shows the symmetric and asymmetric stretching vibrations for C-O group of aromatic sections at 1005 cm-1 and 1190 cm-1, respectively. The peak at 1235 cm-1 is responsible for stretching vibration of C-N functional group present in hexamine cross-linker. The peaks at 1375 cm-1 is associated with the C–H bending vibration. The emerging peaks at 1450 cm-1 are attributed to -CH2 deformation vibration signifying the presence of cross-linking moiety. The peak for aromatic C=C stretching vibration is observed at 1590 cm-1. The peak at 2910 cm-1 is due to the presence of methylene (-CH2) bridges or aliphatic -CH stretching vibration. The peak associated at 3040 cm-1 is responsible for Aromatic -CH stretching mode. The peaks at 3375 cm-1 is associated with the O–H stretching vibration of phenolic/glycol moiety present in lignin and coal tar unit of polymer structure.

Example 3: Crucible swelling number (CSN) study
Characterization of coal
The coals are characterized in terms of ash, volatile matter (VM) and the category in terms of coking potentiality (Table 1). The details of the characterization study is as follows:

Ash analysis: Ash is determined by following ASTM standard D 3174-11. 1 gm of 250 mm size sample is taken to a weighed capsule. The sample is placed in a cold muffle furnace and heated gradually in such a way that the temperature is reached from about 450°C to 500°C by 1 hour. At the end of 2 hours, the temperature reaches about 950?. After cooling, the weight of the sample is measured and ash is calculated by weight difference.

VM analysis: VM is determined by following ASTM standard D 3175-11. In this test, 1 gm of 250 mm size sample is taken in a covered platinum crucible and heated in a furnace at about 950°C for about 7 minutes. The VM is calculated by weight difference.

Table 1: Properties of different coal samples
Coal Ash (%) VM (%) Category
Coal A 16.17 23.81 Captive semi soft
Coal B 7.6 19.80 Imported semi soft
Coal C 5.3 30.20 Imported semi soft
Coal D 17.98 20.81 Captive hard coking
Coal E 9.0 23.40 Imported hard coking
Coal F 7.0 22.50 Imported hard coking
Coal G 9.3 28.3 Imported hard coking
Coal H 9.68 15.08 Imported non-coking

Crucible swelling number (CSN) study:
Crucible swelling number test is done by following ASTM D720-91 (2010). 1 gm of sample
(-0.212 mm size) is taken in a translucent squat shaped silica crucible and the sample is levelled by tapping the crucible 12 times. The crucible is covered with a lid and heated under standard conditions, either by a special type of gas burner or muffle furnace. After the test, the shape of coke button is compared with a standard chart and accordingly, the crucible swelling number (0 to 9) is assigned to the coal sample.

Table 2 summarizes the CSN result of coal before and after the addition of present polymer (LIG-CTP) additive (dosage: 5 wt%). For all the coal samples (Semi Soft: Coal A, Hard Coking: Coal D and Coal E), addition of polymer makes significant improvement in swelling property of coal.

Table 2: CSN value of coal before and after addition of polymer LIG-CTP
Coal CSN
Coal A 5
Coal A + LIG-CTP 5.5
Coal D 5
Coal D + LIG-CTP 6
Coal E 8
Coal E + LIG-CTP 8.5

Example 4: Fluidity study
The instrument used for fluidity determination is known as Geiseler Plastometer. Said plastometer measures the plastic properties of coal by using a constantly applied torque on a stirrer, placed on a crucible into which the coal is charged. The ASTM standard (D2639-Plastometer) is followed for this test. About 5 gm sample of -0.425 mm particle size is packed around a stirrer in a cylindrical steel crucible (21.5 mm ID x 35 mm length). As the coal is being heated from 300°C under prescribed conditions at the rate of 3 °C/min, it begins to soften, and the torque weight causes the stirrer to rotate in the sample. As the coal begins to soften and attain fluid state at higher temperature, the stirrer rotates more rapidly up to a maximum. As the temperature continues to raise, the fluidity of coal starts to fall because of re-solidification of coal and subsequently the stirrer moves slowly until the coal is resolidified into coke and the stirrer stops. The speed of rotation of the stirrer in terms of dial divisions per minute (ddpm) and the corresponding temperatures is recorded every minute.

Fluidity tests are performed with different semi soft and hard coking coal with addition of 5 wt% LIG-CTP. Table 3 shows significant improvement in coal fluidity of semi soft and hard coking coal after addition of polymeric additive.

Table 3: Fluidity of coal before and after addition of polymer LIG-CTP
Coal Max Fluidity (ddpm)
Coal A 1975
Coal A + LIG-CTP 5198
Coal D 13
Coal D + LIG-CTP 1177

Example 5: Carbonization study
A series of carbonization tests were carried out to study the influence of the polymeric additive on coke properties. A number of carbonization tests were conducted in the 7 kg carbolite oven, under stamp charging conditions. Water was added to the coal blend to obtain the desired value of moisture content. The coal cake was made inside a cardboard box keeping the bulk density at 1150 kg/m3. Tests were done with different blends. Initially, test was carried out with base blend (blend no. 1). Thereafter, the hard-coking coal from the base blend is replaced by non-coking coal. Specific amount of polymeric additive (0.7 wt% and 1 wt% with respect to coal blend) is mixed to maintain the coke quality. Before charging the coal cake into the oven, it was ensured that the empty oven temperature is 900±5°C. After about 5 hours of carbonization time, the hot coke was pushed out and quenched with water. The coke samples were tested for coke strength after reaction (CSR).

The coke strength after reaction was studied using NSC method. About 200 gm coke of 19-21 mm size was heated in a reaction tube (78 mm diameter x 210 mm length) at about 1100 °C for about 2 hours and CO2 was passed at a flow rate of about 5 L/min. The percentage weight loss of coke during the above reaction was reported as the coke reactivity indices (CRI). This reacted coke was further tested by rotating in a I drum (127 mm diameter x 725 mm length) for about 30 minutes at a speed of about 20 rpm. The coke was then screened on 10 mm sieve and the % of + 10 mm fraction was reported as the coke strength after reaction (CSR).

Table 4: The blend composition and coking properties
Blend 1 2 3 4
Component (wt%)
Coal A 31 35 34 34
Coal B 14 10 7 7
Coal C 6 6 7 7
Coal D 13 9 9 9
Coal E 10 7 5 5
Coal F 10 11 10 10
Coal G 10 10 12 12
Coal H 6 12 16 16
LIG-CTP 0 0.7 0.7 1
CSR 42.76 45.27 45.5 54.48

In Table 4, blend 1 is the base blend with 6% of non-coking coal (Coal H). In blend 2, 12 % of non-coking coal (Coal H) was used with addition of 0.7% of LIG-CTP polymer to replace imported hard coking coal. Result shows that the CSR value is increased from 42.76 to 45.27. In blend 3, 16 % of non-coking coal (Coal H) was added to replace semi soft and hard coking coal followed by addition of 0.7 % of LIG-CTP polymer and CSR value increased to 45.50. In blend 4, 16 % of non-coking coal (Coal H) was added with addition of 1% of LIG-CTP polymer to replace semi soft and hard coking coal, and the CSR value further increased to 54.48. These results indicate that the LIG-CTP polymer of the present disclosure has significant potential to replace at least up to ~16 % of semi soft and hard coking coal by a non-coking coal.

Thus, the present disclosure relates to the formation of metallurgical coke from poor-coking coal by addition of polymeric additive (LIG-CTP) as described above. More particularly, the disclosure synthesizes a cross-linked polymer derived from industrial by-products (coal tar and lignin precursors) in presence of an aldehyde monomer along with plasticizer and cross-linker for application in metallurgical coke production. The above results clearly evidence the technical effects of the present polymer (LIG-CTP) comprising a single unit structure of Formula I in enhancing the coking potential of non-coking/inferior coal grades by accommodating higher amounts of said non-coking coal and thereby lowering the need of expensive/high grade coals. This further improves the overall economics and efficiency of coke manufacturing.