FIELD OF THE INVENTION
The present invention relates generally to methods and processes for production of vitrinite rich hydrocarbons and conversion of inertinite rich material to useful coking coal from various coals by using combination of DGC and bio-processing treatment method which selectively separate the vitrinite rich material suitable for coke making and also convert inertinite rich material to useful coking coal.
Coal macerals
Coal is a fossil fuel created from the remains of plants that lived and died millions of years ago when parts of the earth were covered with huge swampy forests. Under heat and pressure, this plant matter underwent chemical and physical changes, pushing out oxygen and leaving rich hydrocarbon deposits. What once had been plants gradually turned into coal.Coal is a sedimentary rock composed of two categories of substances: organic carbonaceous matter, termed macerals, and inorganic minerals. Applied to coal, the term mineral matter is an inclusive term that refers to the mineralogical phases as well as to all other inorganic elements in the coal; that is, theelements that are bonded in various ways to the organic (C,H,O,N,S) components.Macerals are the various organic components that make up coal and control its overall behaviour. Under the microscope the macerals fall in to three major groups: liptinite, vitrinite, and inertinite. The liptinite groupis derived from the waxy and resinous parts of plants and mainly consists of sporinite, resinite, and cutinite derived respectively from plants pores, resins, and cuticles. The vitrinite group is derived from coalified woody tissue and is the dominant group inmost coals. The inertinite group is derived from woody tissue that has been altered by fire or biochemicalcharring. Vitrinite is very important for coke making perspective as it becomes plastic during carbonisation between 350 – 550 oC. Different types of coals are blended for coke making, which contains significant amount of vitrinite component. India has huge reserves of non-coking coals, which cannot be used directly in coke making as it does not have coking property. But, separation of

vitrinite from coal by leaching and DGC process will give enough sources for vitrinite rich coal for coke making. In the separation process, inertinite rich coal is separated out which again cannot be used in coke making. Hence, this inertinite rich coal is treated by Aspergillus niger fungi to convert this inertinite rich into higher FSI product coal. This is used in coal blend for coke making. Thus, making complete utilization of non-coking coals into coke making.
Maceral separation by different methods
Maceral separation using sink-float methods were described and reported by Kroger et al. (Gluckauf 1957, 93, 122), Van Krevelen et al. (Fuel 1957, 36, 321) and Fenton and Smith (Gas World 1959, 54, 81) in a paper. Their efforts resulted in concentrations enriched in the three main maceral groups. However,these enrichments were not good enough to give definitivecharacterization data. Sink-float techniques have had only limited success in separating single macerals. Some researchers Dyrkacz and others (Sep. Sci and Tech. 1981, 16, No. 10, 157l-1588; Fuel 1982, 61, 3-12; Fuel 1984, 63, 1367-73) tried density gradient centrifugation technique for maceral separation. In this process, micron size coal sample was demineralized with HF and HCl and then put the sample in centrifuge. After centrifugation, sample is filtered, weighed and dried. They plotted the density and weight of each fraction, which shows maceral composition of the sample. A U.S. patent No. 2497790, issued on Feb. 14, 1950, Pauvrasseau et al. talked about sink and float process for the separation of coal from its impurities.
In another U.S. patent No. 4388181, issued on Jun. 14, 1983, Rainis et al. disclosed a method for the production of metallurgical grade coal and low ash coal by the combination of flotation and selective agglomeration.

In all these patents and papers, they have used sink-float, column flotation, density gradient centrifugation, solvent extraction and leaching techniques for maceral separation and coal beneficiation. A shortcoming of these techniques is; products obtained from these processes are mixture of different types of macerals, which needed further treatment to separate them out. Also, these techniques were used mostly in isolation. Inertinite rich part separated from these methods were not suitable for coke making. Hence, there is a need to use combination of different techniques for better separation. Here, we used combination of DGC and bio-processing method to get pure maceral e.g., vitrinite and convert inertinite rich material into useful coking coal. Once vitrinite is separated by using DGC, the sink part; which is inertinite rich material was treated using Aspegillus Niger fungus.
OBJECT OF THE INVENTION
An object of the present invention is to produce vitrinite rich coal from coals using DGC method.
Another objective of the invention is to convert inertinite rich material into useful coking coal by using bio-processing.
Another objective of the invention is to use combination of DGC and bio-processing for separation of vitrinite and conversion of inertinite rich material to useful coking coal.
SUMMARY OF THE INVENTION
The invention is a process for separation of vitrinite from coal, comprising the steps of grinding coal to particle size less than 75 micron, separating the mineral matter from coal by demineralization, separating the coal from its impurities as float by DGC test and converting inertinite reach content from the sink by bio-processing. The process is designed to liberate and recover the vitrinite from the coal and also

convert inertinite rich material to useful coking coal. This provides a usable end product having good coking properties from high ash coking and non-coking coal.
The grinding process preferably includes only dry grinding stages. The target is to reduce the particles size less than 75 micron before commencing the demineralization and DGC test. The grinding process includes grinding in the mill and then sieving. The fine coal is demineralised with NaOH and HCl. The demineralised coal sample undergoes DGC test using various liquid mixtures of different densities from 1.2 to 2 and more appropriate is 1.3 to 1.6. The float at each density was dried and weighed. The weight fraction was noted against each density. Further, floats 1.5 to 1.6 density sample were subjected to bio-processing experiments. In the bio-processing step, float sample along with Aspergillus Niger bacteria put into glass beaker at room temperature condition. Upon completion of bio-processing, treated coal was separated. The treated coal sample was dried in the oven. The Free Swelling Index (FSI) and petrography test was performed on vitrinite rich and bio-processed coal samples to see the coking potential of the same.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described with reference to the accompanying drawing. Block diagram of the process is shown in Fig.1.
DETAILED DESCRIPTION
When macerals are separated from coal, the vitrinite rich part is used in coke making but inertinite rich part is of no use. This inertinite rich part needs further treatment to convert it into useful material in coke making or any other applications. The vitrinite rich part of coking or non-coking coals is separated by sink-float or DGC or flotation method and is blended with other coals for coke making. The separated inertinite rich materials cannot be used in coke making as it has zero FSI. In order to

improve FSI of inertinite, it is further treated by bio-process using Aspergillus niger fungi.Aspergillus niger is a member of the genus Aspergillus which includes a set of fungi that are generally considered asexual, although perfect forms (forms that reproduce sexually) have been found. Aspergilli are ubiquitous in nature. They are geographically widely distributed, and have been observed in a broad range of habitats because they can colonize a wide variety of substrates. A. niger is commonly found as a saprophyte growing on dead leaves, stored grain, compost piles, and other decaying vegetation. The spores are widespread, and are often associated with organic materials and soil. The primary uses of A. niger are for the production of enzymes and organic acids by fermentation. A. niger is also used to produce organic acids such as citric acid and gluconic acid.Aspergillus niger belongs to fungi kingdom, eurotiomycetes class and aspergillus genus. Microbial conversions involve aerobic systems. The mechanism operating under these conditions is oxidative, depolymerization that is hydroxylation of the aromatic ring followed by ring scission. Indeed, it has been shown that biodegradation/oxidation of aromatics are initiated by a series of enzymes known collectively as the oxygenases. These fungi open up or break the organic ring present in inertinite rich part, which improves FSI value. Thus, inertinite rich part is blended with different coals for coke making. In light of this current invention,complete utilization of a coal in coke making is achieved.
A process is developed for separation of vitrinite and inertinite from the coal. The coal may be used as ROM or washed. Coal in either ROM or washed condition is subsequently processed in the same manner. The coal is stored in container. The raw coal is consists of different macerals such as vitrinite, exinite and inertinite. The stored coal is crushed and/or grinded depending on the size of the coal using the crushing and/or grinding mills. The grinded coal is sieved to the desired particles size and stored for further processing. Desired amount of coal sample is taken out from the sieved coal. The said coal is treated using NaOH and HCl. The concentration of NaOH ranges from 10-40% (w/v), more preferably in a range of 15% or higher and

25% or lower. The HCl concentration ranges from 2-20% (v/v) and more preferably in a range of 5% or higher and 12% or lower. The demineralised coal is treated using DGC technique, wherein different density liquids are prepared for the coal treatment. At each density, a float and a sink can be separated out. The sink sample is treated in next density cut. Each float sample is dried, weighed and stored for further processing. Float sample mostly contains vitrinite as macerals distribution. The float sample can directly be used in coke making.While the sink sample mostly contains inertinite, which cannot be used directly in coke making as it has zero FSI value. This inertinite rich sink sample is further treated with the help of fungi. The Aspergillus niger fungi convert inertinite rich sample into useful material by breaking the organic rings. This converted material is again tested with FSI test. This shows improved FSI value of converted materials and hence, this can also be used in coke making.
Referring to Fig. 1 a process flow is explained in which vitrinite was separated from the coal and inertinite was converted into useful material. Coal sample in run-of-mine (ROM) condition is taken for the test. The coal sample is grinded in ball mill and sieved to less than 500 micron size particles. Representative sample is drawn from bulk grind sample by coning and quartering method. The mass of the sample required depends on the size of the coal. This coal is demineralised with NaOH and HCl. The DGC test is performed on 100 - 500 g of demineralised coal sample, depending on the required quantity. For the DGC test, different densities liquid is prepared. The liquid density is measured by hydrometer. High density liquid was prepared of different densities starting from 1.3 to 2.0 by adding the chemicals in certain ratio. More preferable range of density is 1.3 to 1.6. Take 1.3 density of heavy liquid into a clean glass container and slowly add known quantity of coal sample, in the range of 100 - 500g. Mix the solution with clean glass rod. Put this

sample in DGC tube and run the DGC for 2000 to 12000 rpm. DGC is run more preferably in a range of 5000 rpm or higher and 10000 rom or lower. A clear demarcation between the float and sink products is seen. Separate the float product using a wire mesh spoon and/or filtering on filter paper by pouring the float product liquid through a funnelfitted with filter paper to a beaker, by slow decantation. Then separate the sink material and the liquid by filtering on filter paper. Dry the float and sink on hot plate and weigh it. Add sink material to higher density liquid than previous liquid (say 1.4, 1.45 and so on) and repeat the process. At the end of process, the liquids used need to be kept in clean bottles and can be reused after checking its gravity. The dry float sample of each density is weigh and sent for FSI test. The test was performed upto 1.6 density because after this density hardly any material left for further test. Float of 1.5 to 1.6 density was having more inertinite content. This inertinite rich cannot be used in the coke making. The FSI test shows that it has zero swelling value. This coal then treated by bio-processing method. First, media is prepared by weighing czapek dox agar powder dissolving in a culture flask (33.2g/l). This was stabilized in autoclave at 121 oC and 15 psig pressure for 15 minutes. After cooling down the sterilised media, it is taken to laminar air flow for inoculation. Fungi are inoculated by using inoculating loop. The inertinite rich coal was kept with aspergillus niger fungi for one to ten days at room temperature, more preferably for two to 5 days till the pH of the mixture reaches to four (4). Incubation is done at room temperature and 150 rpm followed by washing and filtration to remove the microorganism. The fungi breaks down the organic ring structure and make it aliphatic chain. This causes the change in FSI from zero to some value. The FSI of inertinite rich coal is measured before and after the bio-processing.
Determination of maceral composition of coal was done through Oil immersion Microscopic analysis. Determination of Maceral composition of coalwas done as per standard (ASTM D2799-05a) and Textural analysis of treated coals was done

through image analysis using Leica Qwin software. Coal moulds were prepared from –1mm size of representative coal samples using cold setting compound. Point counting method (500 counts per mould) was used to quantify different maceral groups in coal. Macerals, the organic building blocks of coal, are broadly classified as Vitrinite, Liptinite and Inertinite Group of macerals, identified on the basis of their reflectance and morphological features.
Example of the maceral separation is presented below.
Coal of 15.8% ash was taken for the study. This coal was grinded to below 75 micron size particles. The representative sample then was treated in DGC with density 1.2 to 1.6 with 0.5 increments. Float from 1.2 to 1.45 density were collected separately and tested for FSI and petrography. These samples were of vitrinite rich. Sink from 1.45 density was treated further in DGC with higher density. Float from 1.5 to 1.6 were collected and tested for FSI and petrography. These float samples were of inertinite rich, hence, had a zero FSI. This we cannot use in coke making. So, these samples further treated with fungi aspegillus niger for two days at room temperature. The fungi break the organic ring into aliphatic chain. The FSI value of the inertinite rich coal before and after bio-processing is recorded. The FSI of clean coal was 7 and the FSI of 1.3 float (which is vitrinite rich) is 9. FSI of inertinite rich part was zero and that of the bio-processed coal was 2. This shows two unit increment of FSI value, which indicates the swelling property of the coal. The results are illustrated in table 1.


In table 1, maceral content of feed coal, 1.3 float and 1.5 float is presented. Feed coal is having 42.5% vitrinite and 49.2% inertinite content. After the treatment in DGC, vitrinite becomes 98.1% in case of 1.3 float sample and inertinite becomes almost negligible, which is 1.9%. In case of 1.5 float, value of inertinite increases to 59.3% and value of vitrinite reduces to 33.7%. This is inertinite rich material, which cannot be used in coke making. So, this sample was treated with aspergillus niger and this was converted to more useful product. This is explained in table 2, where it shows increase in FSI by two units.


WE CLAIM:
1. A process for producing vitrinite rich coal and increasing free swelling index
(FSI) of inertinite rich coal, the process comprising of:
grinding coal to pre-determined size;
demineralising the coal;
separating vitrinite and inertinite by density gradient centrifugation (DGC) method using pre-determined high gravity liquid chemicals;
treatinginertinite rich partby a bio-processing route.
2. The process as claimed in claim 1, wherein the pre-determined size is less than 75 micron being achieved through a dry grinding process.
3. The process as claimed in claim 1, wherein DGCmethod is used to separate the vitrinite and inertinite macerals.
4. The process as claimed in claim 1, wherein vitrinite and inertinite are separated out simultaneously.
5. The process as claimed in claim 1, wherein vitrinite rich material is suitable for coke making.
6. The process as claimed in claim 1, wherein inertinite rich material is treated with aspegillus niger fungi for increasing FSI
7. The process as claimed in claim 1, wherein 1.3 float has at least 98% fraction of vitrinite.

8. The process as claimed in claim 1, wherein coal is demineralised with caustic soda (NaOH) in 15-25 % (w/v) and hydrochloric acid (HCl) in 5-12% (v/v) concentration.
9. The process as claimed in claim 1, wherein free swelling number (FSI) of inertinite rich material is improved to two from zero value by bio-processing.