FORM 2
THE PATENT ACT, 1970
(39 OF 1970)
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
(In respect of Provisional Application No. 2097/MUM/1012 dated 20th July 2012)
TITLE OF THE INVENTION
PROCESS FOR ENHANCING COAL LIQUEFACTION
APPLICANT
Name: PRADEEP METALS LIMITED (A Company incorporated under provisions of the Companies Act, 1956)
Nationality: Indian
Address: R - 205, M.I.D.C, RABALE,
NAVIMUMBAI - 400 701,
MAHARASHTRA PNDIA.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The invention relates to a process for treatment of coal.
The invention particularly relates to the development of a process for treatment of high ash coal using electromagnetic energy such as microwave for enhancing the liquefaction yield from the petroleum crude-like extract so obtained.
The invention more particularly relates to a process for treatment of coal using electromagnetic energy such as microwave in combination with magnetic separation and selection of the more magnetic fraction for enhancing the yield in downstream processing.
BACKGROUND OF RELATED ART
Coal liquefaction is the process of converting solid coal into liquid fuels usable for energy generation. Producing fuel from crude oil is generally cheaper than coal-to-liquid fuel methods. The economics can be advantageous for coal-to-liquid technologies in areas where crude oil is not easily accessible. Recent oil crisis is affecting the economy of all developing countries which are importing petroleum products on the large scale. With the present exploration rate, the natural oil stock is estimated to last only for another four to five decades and with usage from the proven oil reserves of the world, the situation will get even worse.
Coal liquefaction is the process of converting coal into liquid fuel. Two types of processes have been developed for carrying out coal liquefaction, a) Direct liquefaction process and b) Indirect liquefaction process.

In 'Direct coal liquefaction process', coal is pulverized into smaller particles and slurried with a suitable oil. The coal slurry is heated and reacted with hydrogen under high pressure to produce petroleum crude-like extract that can be refined further to obtain lighter and more stable oil molecules. Impurities such as sulfur, nitrogen, and ash are also removed in this process to produce a cleaner fuel.
In 'Indirect coal liquefaction process', coal is first gasified by partially oxidizing it with oxygen and steam to form carbon monoxide and hydrogen known as 'syngas', which is then purified to remove CO2 and other contaminants. Then this syngas is converted into hydrocarbon liquids using Fischer-Tropsch process. The hydrocarbon liquids produced from this reaction are then refined to form liquid fuels. While direct coal liquefaction produces high-octane gasoline and low-cetane diesel, the indirect process produces high-cetane diesel and low-octane gasoline. Furthermore, products from the direct route usually have more energy per gallon due to their denser state.
Direct coal liquefaction has been carried out with hydrogen gas at high temperatures (400 to 500 °C) and pressures (20 to 70 MPa). With certain type of coals, liquid yields can be in excess of 70% of the dry weight coal feed, with thermal efficiencies of around 60-70% depending on the operating conditions. The liquids produced from direct liquefaction are of much higher quality than those from pyrolysis and can be used unblended in power generation or other stationary applications.
In India, total hard coal reserves are estimated to be around 246 billion tonnes, out of which 92 billion tonnes are proven coal reserves. This is about 7% of the world's proven coal reserves. By current estimates, the reserves are enough to meet India's needs for at least another 100 years. Coal reserves are vast and will be available for the foreseeable future without raising geopolitical concerns. Hence, the production of liquid fuels from coal provides a viable alternative to conventional oil products for domestic energy market for the next century and beyond.

Also, Indian coals are of drift origin contain high and thoroughly disseminated mineral matters (ash). These mineral matters (ash) are refractory in nature which makes direct coal liquefaction process of such Indian coal more costly, as it requires large amounts of hydrogen at high temperature and pressure.
Researchers in many countries have been turning their attention to make coal hydrogenation and liquefaction more cost effective. With the passing of time and with the reducing petroleum reserves, the economics will favour coal hydrogenation processes for the production of liquid fuels, especially for the developing countries and those countries with limited oil reserves. However, effective and economy-based techniques are to be introduced to make the hydrogenation process viable.
In this respect the methods outlined in different patent applications where method of converting coal in to hydrocarbon-containing materials using microwaves are described in detail in US 7,955,479 B2, US20060370139, and JP59182887 (A); the disclosure of which are incorporated herein by reference. In these inventions microwave technique is used for accelerating hydrogenation reaction and to produce improved hydrocarbon liquid products in a short reaction time.
US 20100307960A1 and US20090478852 disclose processes in which microwaves are used to generate plasma which in turn produces aliphatic hydrocarbons from coal.
US 4,108,759 disclose a process for gasification and liquefaction of bituminous coal. It consists of producing hydrogen by treating finely pulverized coal with superheated steam in an oxygen free pressure vessel at an elevated temperature using microwave, The hydrogen, thus produced is, further used for converting fine pulverized coal into fuel oil at high pressure and temperature in the presence of hydrogenating liquid.

One of the main bottlenecks in the hydrogenation and liquefaction of Indian coals of drift origin is its high and thoroughly disseminated mineral matter (ash) content. In addition to that, as ash is refractory in nature, direct liquefaction of Indian coal requires large amounts of hydrogen at high temperature and pressure. This creates problems and makes it uneconomical, adding significant direct costs to the processing plants.
Hence, there is a need of development of technologies that will improve the economics of the coal liquefaction process using Indian coal.
OBJECT OF THE INVENTION
It is a primary object of the invention to develop a process for enhancing the yield during the coal liquefaction process.
It is another object of the invention to convert adverse mineral matters present in high ash containing coal into catalytic ones by selective and differential heating of adverse mineral constituents present in the coal by treating it with electromagnetic radiations such as microwaves.
It is yet another object of the invention to increase the magnetic susceptibility of mineral matters present in the coal prior to subjecting it to liquefaction thereby facilitating liquefaction of coal at less severe operating conditions.
It is a further object of the invention to use microwave treated more magnetic fraction of microwave treated coal to liquefaction thereby further enhancing the yield of coal liquefaction.

SUMMARY OF THE INVENTION
Accordingly, a process is invented wherein microwave treatment is attempted on the Indian coal with high ash content. This process shows significant improvements in the whole process of hydrogenation and liquefaction compared to the yield obtained from such untreated coal.
The system and method described in this invention particularly relates to the process for the treatment of Indian coal containing high mineral content (more ash %), where electromagnetic energy such as microwaves is used to improve the magnetic susceptibility and dielectric property of mineral matters (ash) present in such a coal, followed by magnetic separation and selection of the more magnetic fraction for downstream processing, thereby enhancing the liquefaction yield.
The initial microwave treatment increases the magnetic susceptibility of the mineral matters present in the coal This, in turn, alters the breakage characteristics and the intra-particle and the inter-particle mineral characteristics at a molecular level. When the microwave treated coal is further magnetically separated by passing it over a magnetic separator, the fractions obtained (more magnetic and less magnetic) further improve the mineral characteristics of the coal matrix. This unique combination of microwave treatment followed by magnetic separation on such a high ash coal induces changes in the mineral constituents that are very beneficial to the next liquefaction process.
Thus, by the invented process, Indian coal is dry-beneficiated by microwave treatment followed by magnetic separation into less and more magnetic fractions. Catalytic hydrogenation of such a coal results in a better conversion and higher liquefaction yields. The liquefaction process is carried out at a lower temperature and pressure than the conventional process. In this invention, the catalysts used for hydrogenation reaction are coal inherent and modified coal inherent mineral matters

along with the externally added ones. This produces petroleum-like and other-charge stocks for various end uses, starting from high mineral matters (ash) containing coal.
The uniqueness of the invented process is the activation of the thoroughly disseminated inherent mineral matters present in the coal by microwave treatment followed by magnetic separation and selecting more magnetic fraction thereby accelerating the hydrogenation reactions of such a coal, leading to an increase in the efficiency of conversion and higher liquefaction yields at lower operating conditions.
BRIEF DESCRIPTION OF DRAWINGS
The invention and the following detailed description of certain embodiments thereof may be understood with reference to the following Figures:
Fig. 1, Scheme 1 illustrates a schematic process of coal liquefaction on as received
coal samples.
Fig. 1, Scheme 2 illustrates a schematic process of coal liquefaction on more and less
magnetic fractions collected by passing as received coal samples over magnetic
separator.
Fig. 2, Scheme 3 illustrates a schematic process of coal liquefaction on microwave
treated coal samples.
Fig. 2, Scheme 4 illustrates a schematic process of coal liquefaction on more and less
magnetic fractions collected by passing microwave treated coal samples over magnetic
separator.
Fig. 3, illustrates the results of effect of magnetization and microwave pre-treatment of
coal on liquefaction.

DETAILED DESCRIPTION OF THE INVENTION
Detailed embodiments of the present invention are described herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting. but rather to provide an understandable description of the invention.
This invention relates to the microwave treatment of coal specifically coal 101 with a high ash content to enhance the yield during the liquefaction process. In the invented process the microwave treatment 301 was carried out at 2450±50 MHz frequency in a microwave system. During the microwave treatment of the coal 101, the microwave cavity was flushed with an inert gas such as nitrogen, argon, helium, more preferably with nitrogen. Microwave treatment on coal was done for 1 to 10 min. more preferably for 2 to 5 min. The microwave treated coal was crushed in a ball mill and magnetically separated by passing through a magnetic separator 201 and the more magnetic fraction 401 was used for liquefaction process. The liquefaction processes can be carried out either by direct or indirect conversion processes. For confirming the benefits of the invented process different Schemes were employed Fig. 1, Schemes 1,2 and Fig, 2, Scheme 3, 4.
In Fig. 1, Scheme 1, the as-received high ash coal 101 was directly submitted for liquefaction in an autoclave 102 where coal 101 was mixed with the slurrying oil and catalyst and then treated with hydrogen at a high temperature and pressure. After completion of the reaction time, the reaction mixture was filtered 103 and the liquefied extract 104 was used for further yield determination. The residue 105 was rejected.

In Fig. 1, Scheme 2, the as-received high ash coal 101 was first passed over a magnetic separator 201.The more magnetic fraction 202 and less magnetic fraction 203 were collected. More magnetic fraction was subjected to liquefaction in an autoclave 102 where coal was mixed with the slurrying oil and catalyst and treated with hydrogen at a high temperature and pressure. After completion of the reaction time, the reaction mixture was filtered 103 and the liquefied extract 204 was used for further yield determination. The residue 205 was rejected. Similarly, the liquefied extract 206 from low magnetic fraction of coal was used for further yield determination. The residue 207 was rejected.
In Fig. 2, Scheme 3, the as-received high ash coal 101 was first microwave treated 301 in a microwave system for a short duration under controlled conditions and atmosphere by flushing with nitrogen gas. The so-treated coal was then subjected for liquefaction in an autoclave 102 where microwave treated coal was mixed with the slurrying oil and catalyst and treated with hydrogen at a high temperature and pressure. After the completion of the reaction, the reaction mixture was filtered 103 and the liquefied extract 302 was used for further yield determination. The residue 303 was rejected.
In Fig. 2, Scheme 4, which is the main invention where the as-received high ash coal 101 was first microwave treated 30J in a microwave system for a short duration under controlled conditions and atmosphere by flushing with nitrogen gas. The so-treated coal was passed over magnetic separator 202. The more magnetic fraction 401 and less magnetic fraction 402 were collected. These fractions were then separately subjected to liquefaction in an autoclave 102 where coal fraction was mixed with the slurrying oil and catalyst and treated with hydrogen at a high temperature and pressure. After the completion of the reaction, the reaction mixture was filtered 103 and the liquefied extract 403 from more magnetic fraction of coal was used for further yield determinatron. The residue 404 was rejected. Similarly,

the liquefied extract 405 from low magnetic fraction of coal was used for further

yield determination. The residue 406 was rejected.
In an embodiment of the present invention, the high ash coal sample 101 of size 1-25 mm was selected. The first part of the as received high ash coal 101 was crushed to about 100 mesh and subjected to liquefaction (Fig. 1, Scheme 1). The second part of as-received coal 101 was crushed and subjected to magnetic separation and the more magnetic coal fraction 202 and the less magnetic 203 coal fraction was crushed to about 100 mesh and subjected to liquefaction (Fig. 1, Scheme 2). The third part of as received high ash coal 101 was exposed to microwaves at 2450+50 MHz frequency for a specific duration during which an inert gas such as nitrogen was flushed continuously in the microwave system 301. The microwave treated coal sample was crushed and further divided into two parts. The first part of the microwave treated coal was subjected to liquefaction (Fig. 2, Scheme 3) and the other part was crushed and subjected to magnetic separation and separated into more magnetic fraction 401 and less magnetic fraction 402. These were crushed to about 100 mesh and subjected to liquefaction (Fig. 2, Scheme 4).
To prove the efficiency of the invented process, coal liquefaction was carried out by direct liquefaction process. Each coal sample from every scheme was weighed and the moisture contents and ash contents were determined by standard methods. Each sample from every scheme was then mixed with the slurrying oil such as anthracene oil and a catalyst. This was then charged into a batch rocking autoclave, for hydrogenation. The reactor was sealed and pressurized with hydrogen and heated. When the temperature reached 400 °C and pressure about 1400 psig (-10 MPa), rocking of the autoclave was initiated and continued for 2 hours by keeping the temperature constant at 400 °C and pressure around 1400 psig (-10 MPa). After this, the autoclave was stopped, cooled and then depressurized slowly to near atmospheric pressure and the product was collected. The reactor was washed with petroleum ether to remove any adhering coal particles inside the reactor. The

reaction mixture was then filtered using Buchner funnel. The filtered residue was then washed with petroleum ether to remove any anthracene oil as anthracene oil is soluble in petroleum ether. This filtered residue was dried till its weight became constant.
Based on the equations reported in the reference ('Refining of sub-Indian coal with solvent and hydrogen', by Diwedi S.R., R.R. Prasad,, et al., Proc. Of International Symposium on coal and Science Technology, 1980) the percentage liquefaction was calculated. The equation is given as:
% Liquefaction = (C-m-R) / (C-m-A) (I)
Where, C = weight of coal (gm)
m = weight of moisture in C gm of coal, (gm)
R = weight of filter residue collected after drying, (gm)
A = weight of ash in C gm of coal, (gm)
Many modifications in addition to those described above may be made to the technique described herein without departing from the spirit and scope of the invention Accordingly, following are examples only and or not limiting of the scope of the invention.
Example 1:
In this example the effect of only magnetic separation and combination of microwave + magnetic separation, on the properties of coal, specially in more magnetic fraction of coal is reported in Table 1.

Table 1: Effect of magnetic separation and combination of microwave + magnetic separation on coal properties

% (As received) % after
magnetic
separation
(more magnetic
fraction) % after microwave ,
treatment followed by
magnetic separation
(more magnetic
fraction)
Moisture 3.9 3.9 2.3
Volatile matter 22.7 16.3 11.7
Ash 33.1 44.2 55.9
Fixed carbon 40.3 35.5 30.1
Example 2
Coal lumps of about \ to 25 mm size were subjected directly to liquefaction, for which 50 gm of as received high ash coal was crushed to 100 mesh and mixed with 75 gm of anthracene oil and 5 gm dual functional hydrocracking catalyst (Co-Mo on silica-alumina). This mix was then loaded into the autoclave. The temperature and pressure of the reaction mix was slowly increased by passing pure hydrogen gas. The final temperature maintained at 400 °C and pressure about 1400 psig (-10 MPa). After completion of the reaction, the reactor was slowly cooled and depressurized. Then the reactor was opened and the residue was filtered using Buchner funnel and filter paper. The reactor and the residue were washed several times with petroleum ether. The residue was dried till constant weight and % liquefaction was calculated based on the weight of the residue using equation I.
Typical experimental data: Coal. 50 gm Anthracene oil: 75 gm Catalyst. 5 gm

Final temp. : 400 °C
Final pressure :1200 psig
Weight of filtered residue after drying : 40.0 gm
Ash : 33.1%
Moisture: 3.9%
Using equation (I), %liquefaction was calculated to be 25.7%
EXAMPLE 3
Coal lumps of about 1 to 25 mm size were subjected to microwave for about 2 min. under inert atmosphere such as nitrogen. The microwave treated coal was then passed over a magnetic separator. The more magnetic and less magnetic portions were separately collected. From more magnetic portion of the coal, about 50 gm coal was crushed to 100 mesh and mixed with 75 gm of anthracene oil and 5 gm dual functional hydrocracking catalyst (Co-Mo on silica-alumina). This mix was then loaded into the autoclave. The temperature and pressure of the reaction mix was slowly increased by passing pure hydrogen gas. The final temperature maintained at 400 °C and pressure about 1400 psig (~10 MPa). After completion of the reaction, the reactor was slowly cooled and depressurized. Then the reactor was opened and the residue was filtered using Buchner funnel and filter paper. The reactor and the residue were washed several times with petroleum ether. The residue was dried till constant weight and % liquefaction was calculated based on the weight of the residue using equation I.
Typical experimental data:
Coal: 50 gm
Anthracene oil: 75 gm
Catalyst: 5 gm
Final temp. : 400 °C
Final pressure: 1375 psig
Weight of filtered residue after drying: 39.5 gm

Ash: 55.9%
Moisture: 2.3%
Using equation (I), %Iiquefaction was calculated to be 44.7%
ADVANTAGES OF THE INVENTION:
1. The selective and differential heating reduces the erodability and refractory nature of ash present in coal, resulting in decreased resistivity and better heat transfer characteristics.
2. The coaly portion becomes more reactive due to the removal of occluded gases and decomposition products resulting in the opening-up of pores and increase in the voidage space.
3. Some adverse minerals present in coal are converted into reactive ones which act favorably in the liquefaction process.
4. The magnetic susceptibility of mineral matter present in the coal increases thereby facilitating catalytic liquefaction of coal at less severe operating conditions which enhances the quality and yield of the product.
5. Selectively advantageous fractions of feed stocks are obtained by the invented process for down-stream processing for coal liquefaction and other industrial processes.
6. The improved reaction rates of hydrogenation and / or hydro cracking reduce the hydrogen consumption.
7. The invented process can be added onto existing plants relatively easily.
8. The liquefaction yield of high ash Indian coal increases from ~ 26% (untreated as-received coal) to -45% using the invented process.
9. The "rejected residue" obtained after liquid extraction can be utilized for gasification and/or combustion.

We claim:
1. A process for enhancing coal liquefaction yield from the petroleum crude¬
like extract so obtained from high ash containing coal comprising:
a. exposing the coal to electromagnetic radiations such as microwaves;
b. flushing the microwave system with an inert gas during coal
treatment;
c. passing the microwave treated coal over magnetic separator for
separation of less and more magnetic fractions of the coal
d. crushing the magnetically separated coal fraction
e. subjecting the more magnetic coal fraction for further liquefaction
f. extracting the petroleum crude-like extract so obtained to produce
petroleum-like and other-charge stocks for various end uses
2. The process as defined in claim 1, wherein the coal is high ash containing coal.
3. The process as defined in claim 1, wherein the size of the coal is 1mm to 25mm.
4. The process as defined in claim 1, wherein the electromagnetic radiations are continuous or pulsed.
5. The process as defined in claim 1, wherein the microwave energy used is in the range of 2450 ± 50 MHz.
6. The process as defined in claim 1, wherein the inert gas is nitrogen or argon or helium, more preferably nitrogen.
7. A process for enhancing coal liquefaction yield from the petroleum crude¬like extract so obtained from high ash containing coal comprising:
a. exposing the coal lumps of 1 to 25 mm size to electromagnetic radiations such as microwaves for about 2-5 minutes;

b. flushing the microwave system with an inert gas during coal
treatment;
c. passing the microwave treated coal over a magnetic separator for the
separation of less and more magnetic fractions of the coal
d. crushing the magnetically separated coal fractions to 100 mesh size
e. subjecting 50g of the more magnetic fraction for further liquefaction
8. A process for enhancing coal liquefaction from the petroleum crude-like extract so obtained from the high ash coal as described in the text and examples,