of Hazardous Trace Elements (HTEs) into the environment is influenced by both natural and anthrop... more of Hazardous Trace Elements (HTEs) into the environment is influenced by both natural and anthropogenic activities. In the present study, chemometric analysis is applied as a tool to evaluate the release behaviour of Hazardous Trace Elements (HTEs) during coal mining and utilization processes. Statistical tools like Principal Component Analysis (PCA), cluster analysis, and Linear Discriminant Analysis (LDA) were applied on the TE concentrations of raw coals and thermally treated coals. PCA and LDA successfully predicted the association of potentially hazardous elements contained in coal and their release behaviour. Consistency of chemometric results with the experimental results indicates that it can be used for analyzing release behaviour of HTEs during mining and utilization.
Zenodo (CERN European Organization for Nuclear Research), Nov 30, 2013
Rampant coal mining are being carried out in almost all the coal bearing areas of Nagaland which ... more Rampant coal mining are being carried out in almost all the coal bearing areas of Nagaland which degrading the environment including soil. With a view to reclaim the lands degraded by mining of coal, we find a possibilities of isolating humic acid from inferior (shaly) coal and coal wastes of Mongchen Coalfield, Nagaland. Humic acid the black gold of agriculture is a commercial term referring to combined humic and fulvic acids. They are also known to be most biochemically active materials. Humic acid are macromolecular substance of a predominantly aromatic character with an extremely complex structure. In the present investigation an attempt has been made to prepare the humic acid from the low grade coal of Monchem Coalfield by oxidation followed by alkali extraction and separation techniques. All the results reveal that humic acid can be isolated from the coal samples under study. The product was characterized by FTIR spectra, UV-Visible spectroscopy, SEl\1 and XRD.
Northeast Indian coals have immense potential for energy, power and other value added products. I... more Northeast Indian coals have immense potential for energy, power and other value added products. In comparison to the country’s total deposit, the reserve though less, deserves attention owing to different physico-chemical characteristics and non-availability of good quality coal in the country. The state of Nagaland forms a part of the northern extension of the Arakan-Yoma range which has undergone orogenic upheavals during the Cretaceous and Tertiary period. The state has a good deposit of high sulfur coals, lying unexploited industrially so far. In the present investigation, a systematic study on Nagaland coals has been done to explore their suitability as a source of energy. Coal samples from different coalfields have been analyzed for proximate, ultimate, TGA, composition of ash, and petrographic constituents. The swelling and caking indices have been determined. The fouling and slagging indices of these coals have also been reported. The Nagaland coals have high sulfur content similar to those of the other tertiary coals and low ash fusion temperature range, for which they are not suitable for the power generation with the conventional combustion systems, however could be suitable for combustion with FBC techniques, which operate at lower temperature (≤ 850°C) with in-situ desulphurization mechanism. These coals also show characteristics of non-caking and swelling in general.
The north eastern region (NER) of India has a substantial deposit of high sulfur (2-8%) coals wit... more The north eastern region (NER) of India has a substantial deposit of high sulfur (2-8%) coals with low ash and high volatile matter contents. Assam, one of the coal producing states of the region, has coal deposits with 75-90% of organic sulfur functionalities affixed to the coal structure and difficult to remove. The present investigation reports desulfurization of oxidized Assam coals by solvent extraction and alkali treatment separately. The two coal samples are selected to represent two categories: one with high organic sulfur and low ash (Baragolai) and the other with low organic sulfur and high ash (Ledo) coals of the region The desulfurization routes are comprised of oxidation of two coal samples of various size fractions in an oxidative medium (H 2 O 2 and HCOOH) followed by solvent extraction (dimethyl formamide, DMF) and alkali (NaOH) treatment separately. Oxidation of Baragolai and Ledo coals removes up to about 84% of inorganic and 28 and 18.5% of organic sulfur, respectively. After DMF extraction, desulfurization increases up to 95 and 93% for inorganic sulfur and 31 and 23% organic sulfur of the oxidized Baragolai and Ledo coals, respectively, while the alkali treatment shows complete removal of inorganic and a maximum of 33 and 26.4% organic sulfur for these coals, respectively. During oxidation, solvent extraction, and alkali treatments, ash removal for both the coals is observed. Desulfurization is found to increase with decrease of the particle size. Decrease in the atomic S/C ratio of oxidized samples shows the effectiveness of the process. Fourier transform infrared (FTIR) spectroscopy studies show formation of sulfones and sulfoxides (SdO) during oxidation and their removal by solvent extraction and alkali treatment. With activation complex theory (ACT), the Gibbs free energy of activation (∆G*), entropy of activation (∆S*), enthalpy of activation (∆H*), and activation energy (E a) calculated for organic sulfur removal show possible removal of low molecular weight sulfur compounds. The nonspontaneous nature of the reaction is mainly due to the steric hindrance by large aromatic rings.
Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due t... more Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due to aqueous weathering. These acidic effluents contain dissolved trace and potentially harmful elements (PHEs) that have considerable impact on the environment. The behavior of these elements in AMD is mainly controlled by pH. The focus of the present study is to investigate aqueous leaching of mine rejects for prediction of acid producing potential, rates of weathering, and release of PHEs in mine drainage. Mine reject (MR) and coal samples from the active mine sites of Meghalaya, India typically have high S contents (1.8-5.7% in MR and 1.7-4.7% in coals) with 75-90% of the S in organic form and enrichment of most of the PHEs in rejects. Aqueous kinetic leaching experiments on mine rejects showed high acid producing potential and release of trace and potentially harmful elements. The elements (Sb, As, Cd, Cr, Co, Cu, Pb, Mn, Ni, V and Zn) in mine sample leachates are compared with those in mine waters. The concentrations of Al, Si, P, K, Ti, Mn, Fe, Co, Ni, Cu, Zn and Pb are found to increase with leaching time and are negatively correlated with pH of the solution. The processes controlling the release of these elements are acid leaching, precipitation and adsorption. The critical loads of PHEs in water affected by AMD are calculated by comparing their concentrations with those of regulatory levels. The Enrichment Factors (EFs) and soil pollution indices (SPIs) for the elements have shown that PHEs from coal and mine reject samples are mobilized into the nearby environment and are enriched in the associated soil and sediment.
In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, In... more In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, India have been studied on the basis of proximate and ash analysis. Various statistical tools like Bivariant Analysis, Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA), and also the geochemical indicators were applied to determine the dominant detrital or authigenic affinity of the ash forming elements in these coals. The genetic interpretation of coal as well as the coal ash has been carried out based on chemical compositions of high temperature ash (HTA) by using Detrital/Authigenic Index. X-Ray Diffraction (XRD) analysis was also carried out to study the mineralogy of the studied coal ashes. Both statistical tools and geochemical indicators have confirmed the detrital nature of these coals as well as the ash forming elements.
ABSTRACT tIn the present investigation, the effect of biochar incorporation into high sulphur min... more ABSTRACT tIn the present investigation, the effect of biochar incorporation into high sulphur mine rejects on bufferingof the acid production was assessed. For this, kinetic experiments on pure mine rejects (LMR) and biocharamended mine rejects (LMRBC) were performed for 720 h. Leachate samples were collected at 0, 20, 40,60, 168, 336, 504 and 720 h and characterized. Results revealed that incorporation of biochar inhibitedthe acid production rate (from 10.4 kg/Mt/h to 3.81 kg/Mt/h) and enhanced the alkali consumption (from9.7 kg/Mt/h to 13.9 kg/Mt/h). Biochar was capable to neutralize all the acid produced. As a neutralizingagent, Mg2+dominated over Ca2+. The efficiency of biochar to reduce the rate of acid production may bedue to either the reduction in Fe3+concentration or production of reduced sulphur compounds in reducingconditions of biochar. This is also supported by molar sulphur to iron ratio of leachate water. Principalcomponent analysis applied on the data revealed that biochar altered the salt and carbon dissolutionprocesses of mine rejects. It inhibits the acid production and accelerates the alkali releasing.
In present investigation, chemometric tools, principal component analysis (PCA) and Hierarchical ... more In present investigation, chemometric tools, principal component analysis (PCA) and Hierarchical clustering analysis (HCA) are used to get the linkage between the coal properties and kinetics of pyrolysis. Thermo gravimetric analysis (TGA) of 10 perhydrous Indian coals was done. Devolatilization of these coals showed five independent reactions. Kinetic parameters were calculated for individual reaction. Activation energy and weight loss of each reaction has been analyzed as a function of coal properties (moisture, volatile matter, ash, fixed carbon, carbon, hydrogen, nitrogen and sulfur). By applying chemometric, was extracted information about the linkage between activation energies of each reaction and coal properties. The mathematical treatment of data has provided conclusions on properties of coal and kinetic parameters.
Environmental progress & sustainable energy, Mar 10, 2011
Coal combustion processes have inherent characteristics that lead to the release of both gaseous ... more Coal combustion processes have inherent characteristics that lead to the release of both gaseous and particulate matter in the atmosphere that have primary and secondary impact on air quality, human health, and climate. Coals from Northeastern region of India have high sulfur, low ash, and high volatile matter. In the present investigation, sulfur, metals and ash contents of feed coals were considered for making an emission inventory for these coals. For the calculation of emission factors of SO 2 and metals, mass balance method was used, while for PM 2.5 , measured values near the coke ovens were taken. The emission factors and emission rates of SO 2 for coke ovens ranged between 0.80 to 4.8 Kg/t and 204 to 1226 t/yr respectively. The emission factors for PM 2.5 , total carbon (TC), black carbon (BC) and organic carbon (OC) varied between 0.7 to 3 Kg/t, 0.48 to 2.1 Kg/t, 0.007 to 0.03 Kg/t and 0.47 to 2.1 Kg/t, respectively. Total emissions for PM 2.5 , TC, BC and OC ranged between 72-306 t/yr, 49-217 t/yr, 0.71-2.9 t/yr and 48-214 t/yr, respectively. Emission rates of metals (V,
International Journal of Coal Preparation and Utilization, May 26, 2010
Higher hydrogen content of perhydrous coals exhibits a different composition and physicochemical ... more Higher hydrogen content of perhydrous coals exhibits a different composition and physicochemical properties in comparison with normal coals. In the present investigation, a structural study of perhydrous coals and coke was done using FTIR and HPLC data. These coals have high volatile matter with high-calorific values and low-moisture content. The structural study suggests that the major structural units of these coals are simple phenols with para-alkyl substituted derivatives. They have high alkyl substitution groups and low aromatic compounds. The structural studies reveal that these coals contain high amounts of low-molecular weight PAH compounds with 1-2 ring structures. These 1-2 ring structures have high H/C ratios as compared to large ring polyaromatic hydrocarbons (PAHs). It may also be one of the reasons for high H/C ratios in these coals. The alkyl groups contribute significantly to their high volatile matter (VM) contents. The presence of alcoholic groups found in pyrolytic products may also be due to the conversion of catechol-like structures to those of cresols. Coal properties, such as moisture, VM, H/C ratio, and CV,
PM 2.5 and PM 10 samples collected at a suburban site of northeastern part of India have been ana... more PM 2.5 and PM 10 samples collected at a suburban site of northeastern part of India have been analysed for particle mass, total carbon (TC), water-soluble total carbon (WSTC), water-soluble organic carbon (WSOC), water-soluble inorganic carbon (WSIC), organic acids (formic, acetic, proponoic and oxalic acids) along with inorganic ions (NO 3 − , SO 4 2− and NH 4 −). Most of the PM 10 consists of PM 2.5 in the present site (ratio 54-74%). WSTC content in PM 2.5 and PM 10 corresponds to 21% and 16%, respectively, of their total particle masses. Thermo gravimetric analysis showed the presence of humic-like substances (16-22%) in particulate samples. Domestic heating and stagnant atmospheric conditions enhanced the levels of these carbonaceous compounds in PM 2.5 and PM 10 in winter. Qualitative estimation of various functional groups by Fourier transform infrared (FTIR) analysis indicates the presence of carboxylic, hydroxyl, aliphatic and aromatic hydrocarbons, amines and sulphurous compounds in these aerosols. Absolute principal component analysis applied on the aerosol data resolves four factors. These factors are associated with carbonaceous aerosols released from combustion of coal and wood, secondary inorganic and organic aerosols and water-soluble inorganic fraction.
Journal of the Geological Society of India, Sep 1, 2015
Six high sulphur coal samples along with two fly ash samples were characterized by using X-ray di... more Six high sulphur coal samples along with two fly ash samples were characterized by using X-ray diffraction (XRD), Energy Dispersive x-ray Fluorescence (EDXRF), Atomic Absorption Spectroscopy (AAS), Fourier Transform Infrared (FT-IR) and Scanning Electron Spectroscopy (SEM) techniques to interpret their mineral matters and inorganic constituents. The proximate, ultimate and sulfur analyses of the coal and fly ash samples were also performed to know their possible aspects of utilization. Significant amount of silicate/clay minerals along with other elements are found to be present in these coals and fly ash samples. The SEM micrographs showed the presence of pyrite and marcasite in different forms including clusters of pyrites in the coals. The leaching characteristics of the coal and fly ash samples showed the mobilization of some potentially hazardous elements (PHEs) from them. Mercury was found to be leached out with ~0.50 ppm from fly ash samples in water.
Bio-energy is now emerging as a future source of energy. Pyrolysis is one of the main thermo-chem... more Bio-energy is now emerging as a future source of energy. Pyrolysis is one of the main thermo-chemical processes that can provide a useful and valuable bio-fuel such as biooil and bio-char. Bio-oil was produced from an undesired bioweed named Ipomoea carnea by thermal pyrolysis at a terminal temperature range from 350 to 600°C with a heating rate of 10°C/min. Maximum bio-oil yield (41.17 % of which 11.45 % is the oil phase) was obtained at a pyrolysis temperature of 550°C. The oil obtained was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR; 1 H and 13 C), and gas chromatography-mass spectroscopy (GC-MS) which revealed the presence of various hydrocarbons and alcohols. The H/C molar ratio (1.49) of the bio-oil was found to be comparable with petroleum-derived diesel. However, the presence of oxygen (35.86 %) in the form of oxygenates especially organic acids make the bio-oil acidic, which needs to be upgraded to use in the current IC engine.
Mining practices, present and past, contribute towards environmental degradation affecting the ec... more Mining practices, present and past, contribute towards environmental degradation affecting the ecosystems and human health. The unscientific coal mining in the tertiary North Eastern Region (NER) Indian coal mines poses a serious threat to the environment. Dumping of waste rocks including mine rejects generated during mining adds to the problem by aqueous weathering and discharge of acidic effluents. The coal mining in Meghalaya causes large-scale destruction and degradation of the environment. Coal extraction in the state is done by primitive sub-surface mining methods commonly known as 'rat hole' mining. The indiscriminate and unscientific mining, absence of post mining treatment and management of mined areas are making the fragile ecosystems more vulnerable to environmental degradation and leading to land use changes. The main problems in Meghalaya are the production of Acid Mine Drainage (AMD) in nearby areas by continuous leaching of acidic waste from the coal mining sectors. An Environmental Management Plan (EMP), has been developed for management of AMD in high sulphur coalmines by simulation of AMD from weathered coals and mine rejects. Sequential alkalinity producing (SAP) coupled with biological processes found effective in controlling AMD and reducing TDS, Conductivity, SO 4 and toxic elements. In this paper, the state of art for AMD and the processes suitable for the management of AMD are discussed.
The preparation of some oxides and mixed oxide sorbents with aluminosilicate type of binders for ... more The preparation of some oxides and mixed oxide sorbents with aluminosilicate type of binders for high temperature desulphurisation of fuel gases is di scussed. The sorbents investigated are extrudates of ZnO, Indian iron-ore fm es and slimes, ZnO-iron ore fines , ZnO-iron ore slimes, CuO-iron ore slimes, combusted coal ashes (CCA), CuO-CCAs, Zn0-Fe20 3 , Cu0Fe203 and CuO-Fe20 r A1 20 3. These sorbents have been found highly efficient in absorbing sulphurous gases . The fresh, sulphidised, regenerated sorbents of mixed metal oxides and their chemical ph ases have been identified by X-ray diffracti on technique. The presence of x-chalcopyrite, ZnS, morihoikite, CuFe2S3 , CuFeS3, Cu3(S04)(0H)4 and CuS04 5H20 in both major and minor phases in th e sulphidised samples indi cate the absorption of sulph r from sulphurous gases at hi gh temperatures. The crushing strength of the fresh, sulphidised, regenerated and resulphidised sorbents has been determined. The performance o f the sorbents ...
International Journal of Coal Science & Technology, 2021
In this research work, isolation of humic acid from coal of Northeastern region of India is repor... more In this research work, isolation of humic acid from coal of Northeastern region of India is reported. The study is also targeted for application of the coal-derived humic acid in acid mine drainage (AMD) water treatment and electrochemical devices. All the obtained results are compared with the standard humic acid and examined the formation of humic acid from the coal. The isolated coal-derived humic acid is found to be high degree of humifications and relatively stable up to about 200 °C. The FTIR study indicates the formation of metal-humic acid complexes. On treatment with acidic water (AMD), the coal-derived humic acid was found to have the ability to remove toxic metal such as (in order) Pb > Cu > Zn > Cd. In addition, the preliminary electrochemical properties of the isolated humic acid are also discussed in the paper. The specific capacitance of the isolated coal-derived humic acid via cyclic voltammetry and charge-discharge analysis is found to be 7 mF/g at scan rat...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
of Hazardous Trace Elements (HTEs) into the environment is influenced by both natural and anthrop... more of Hazardous Trace Elements (HTEs) into the environment is influenced by both natural and anthropogenic activities. In the present study, chemometric analysis is applied as a tool to evaluate the release behaviour of Hazardous Trace Elements (HTEs) during coal mining and utilization processes. Statistical tools like Principal Component Analysis (PCA), cluster analysis, and Linear Discriminant Analysis (LDA) were applied on the TE concentrations of raw coals and thermally treated coals. PCA and LDA successfully predicted the association of potentially hazardous elements contained in coal and their release behaviour. Consistency of chemometric results with the experimental results indicates that it can be used for analyzing release behaviour of HTEs during mining and utilization.
Zenodo (CERN European Organization for Nuclear Research), Nov 30, 2013
Rampant coal mining are being carried out in almost all the coal bearing areas of Nagaland which ... more Rampant coal mining are being carried out in almost all the coal bearing areas of Nagaland which degrading the environment including soil. With a view to reclaim the lands degraded by mining of coal, we find a possibilities of isolating humic acid from inferior (shaly) coal and coal wastes of Mongchen Coalfield, Nagaland. Humic acid the black gold of agriculture is a commercial term referring to combined humic and fulvic acids. They are also known to be most biochemically active materials. Humic acid are macromolecular substance of a predominantly aromatic character with an extremely complex structure. In the present investigation an attempt has been made to prepare the humic acid from the low grade coal of Monchem Coalfield by oxidation followed by alkali extraction and separation techniques. All the results reveal that humic acid can be isolated from the coal samples under study. The product was characterized by FTIR spectra, UV-Visible spectroscopy, SEl\1 and XRD.
Northeast Indian coals have immense potential for energy, power and other value added products. I... more Northeast Indian coals have immense potential for energy, power and other value added products. In comparison to the country’s total deposit, the reserve though less, deserves attention owing to different physico-chemical characteristics and non-availability of good quality coal in the country. The state of Nagaland forms a part of the northern extension of the Arakan-Yoma range which has undergone orogenic upheavals during the Cretaceous and Tertiary period. The state has a good deposit of high sulfur coals, lying unexploited industrially so far. In the present investigation, a systematic study on Nagaland coals has been done to explore their suitability as a source of energy. Coal samples from different coalfields have been analyzed for proximate, ultimate, TGA, composition of ash, and petrographic constituents. The swelling and caking indices have been determined. The fouling and slagging indices of these coals have also been reported. The Nagaland coals have high sulfur content similar to those of the other tertiary coals and low ash fusion temperature range, for which they are not suitable for the power generation with the conventional combustion systems, however could be suitable for combustion with FBC techniques, which operate at lower temperature (≤ 850°C) with in-situ desulphurization mechanism. These coals also show characteristics of non-caking and swelling in general.
The north eastern region (NER) of India has a substantial deposit of high sulfur (2-8%) coals wit... more The north eastern region (NER) of India has a substantial deposit of high sulfur (2-8%) coals with low ash and high volatile matter contents. Assam, one of the coal producing states of the region, has coal deposits with 75-90% of organic sulfur functionalities affixed to the coal structure and difficult to remove. The present investigation reports desulfurization of oxidized Assam coals by solvent extraction and alkali treatment separately. The two coal samples are selected to represent two categories: one with high organic sulfur and low ash (Baragolai) and the other with low organic sulfur and high ash (Ledo) coals of the region The desulfurization routes are comprised of oxidation of two coal samples of various size fractions in an oxidative medium (H 2 O 2 and HCOOH) followed by solvent extraction (dimethyl formamide, DMF) and alkali (NaOH) treatment separately. Oxidation of Baragolai and Ledo coals removes up to about 84% of inorganic and 28 and 18.5% of organic sulfur, respectively. After DMF extraction, desulfurization increases up to 95 and 93% for inorganic sulfur and 31 and 23% organic sulfur of the oxidized Baragolai and Ledo coals, respectively, while the alkali treatment shows complete removal of inorganic and a maximum of 33 and 26.4% organic sulfur for these coals, respectively. During oxidation, solvent extraction, and alkali treatments, ash removal for both the coals is observed. Desulfurization is found to increase with decrease of the particle size. Decrease in the atomic S/C ratio of oxidized samples shows the effectiveness of the process. Fourier transform infrared (FTIR) spectroscopy studies show formation of sulfones and sulfoxides (SdO) during oxidation and their removal by solvent extraction and alkali treatment. With activation complex theory (ACT), the Gibbs free energy of activation (∆G*), entropy of activation (∆S*), enthalpy of activation (∆H*), and activation energy (E a) calculated for organic sulfur removal show possible removal of low molecular weight sulfur compounds. The nonspontaneous nature of the reaction is mainly due to the steric hindrance by large aromatic rings.
Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due t... more Coal mine rejects and sulfide bearing coals are prone to acid mine drainage (AMD) formation due to aqueous weathering. These acidic effluents contain dissolved trace and potentially harmful elements (PHEs) that have considerable impact on the environment. The behavior of these elements in AMD is mainly controlled by pH. The focus of the present study is to investigate aqueous leaching of mine rejects for prediction of acid producing potential, rates of weathering, and release of PHEs in mine drainage. Mine reject (MR) and coal samples from the active mine sites of Meghalaya, India typically have high S contents (1.8-5.7% in MR and 1.7-4.7% in coals) with 75-90% of the S in organic form and enrichment of most of the PHEs in rejects. Aqueous kinetic leaching experiments on mine rejects showed high acid producing potential and release of trace and potentially harmful elements. The elements (Sb, As, Cd, Cr, Co, Cu, Pb, Mn, Ni, V and Zn) in mine sample leachates are compared with those in mine waters. The concentrations of Al, Si, P, K, Ti, Mn, Fe, Co, Ni, Cu, Zn and Pb are found to increase with leaching time and are negatively correlated with pH of the solution. The processes controlling the release of these elements are acid leaching, precipitation and adsorption. The critical loads of PHEs in water affected by AMD are calculated by comparing their concentrations with those of regulatory levels. The Enrichment Factors (EFs) and soil pollution indices (SPIs) for the elements have shown that PHEs from coal and mine reject samples are mobilized into the nearby environment and are enriched in the associated soil and sediment.
In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, In... more In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, India have been studied on the basis of proximate and ash analysis. Various statistical tools like Bivariant Analysis, Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA), and also the geochemical indicators were applied to determine the dominant detrital or authigenic affinity of the ash forming elements in these coals. The genetic interpretation of coal as well as the coal ash has been carried out based on chemical compositions of high temperature ash (HTA) by using Detrital/Authigenic Index. X-Ray Diffraction (XRD) analysis was also carried out to study the mineralogy of the studied coal ashes. Both statistical tools and geochemical indicators have confirmed the detrital nature of these coals as well as the ash forming elements.
ABSTRACT tIn the present investigation, the effect of biochar incorporation into high sulphur min... more ABSTRACT tIn the present investigation, the effect of biochar incorporation into high sulphur mine rejects on bufferingof the acid production was assessed. For this, kinetic experiments on pure mine rejects (LMR) and biocharamended mine rejects (LMRBC) were performed for 720 h. Leachate samples were collected at 0, 20, 40,60, 168, 336, 504 and 720 h and characterized. Results revealed that incorporation of biochar inhibitedthe acid production rate (from 10.4 kg/Mt/h to 3.81 kg/Mt/h) and enhanced the alkali consumption (from9.7 kg/Mt/h to 13.9 kg/Mt/h). Biochar was capable to neutralize all the acid produced. As a neutralizingagent, Mg2+dominated over Ca2+. The efficiency of biochar to reduce the rate of acid production may bedue to either the reduction in Fe3+concentration or production of reduced sulphur compounds in reducingconditions of biochar. This is also supported by molar sulphur to iron ratio of leachate water. Principalcomponent analysis applied on the data revealed that biochar altered the salt and carbon dissolutionprocesses of mine rejects. It inhibits the acid production and accelerates the alkali releasing.
In present investigation, chemometric tools, principal component analysis (PCA) and Hierarchical ... more In present investigation, chemometric tools, principal component analysis (PCA) and Hierarchical clustering analysis (HCA) are used to get the linkage between the coal properties and kinetics of pyrolysis. Thermo gravimetric analysis (TGA) of 10 perhydrous Indian coals was done. Devolatilization of these coals showed five independent reactions. Kinetic parameters were calculated for individual reaction. Activation energy and weight loss of each reaction has been analyzed as a function of coal properties (moisture, volatile matter, ash, fixed carbon, carbon, hydrogen, nitrogen and sulfur). By applying chemometric, was extracted information about the linkage between activation energies of each reaction and coal properties. The mathematical treatment of data has provided conclusions on properties of coal and kinetic parameters.
Environmental progress & sustainable energy, Mar 10, 2011
Coal combustion processes have inherent characteristics that lead to the release of both gaseous ... more Coal combustion processes have inherent characteristics that lead to the release of both gaseous and particulate matter in the atmosphere that have primary and secondary impact on air quality, human health, and climate. Coals from Northeastern region of India have high sulfur, low ash, and high volatile matter. In the present investigation, sulfur, metals and ash contents of feed coals were considered for making an emission inventory for these coals. For the calculation of emission factors of SO 2 and metals, mass balance method was used, while for PM 2.5 , measured values near the coke ovens were taken. The emission factors and emission rates of SO 2 for coke ovens ranged between 0.80 to 4.8 Kg/t and 204 to 1226 t/yr respectively. The emission factors for PM 2.5 , total carbon (TC), black carbon (BC) and organic carbon (OC) varied between 0.7 to 3 Kg/t, 0.48 to 2.1 Kg/t, 0.007 to 0.03 Kg/t and 0.47 to 2.1 Kg/t, respectively. Total emissions for PM 2.5 , TC, BC and OC ranged between 72-306 t/yr, 49-217 t/yr, 0.71-2.9 t/yr and 48-214 t/yr, respectively. Emission rates of metals (V,
International Journal of Coal Preparation and Utilization, May 26, 2010
Higher hydrogen content of perhydrous coals exhibits a different composition and physicochemical ... more Higher hydrogen content of perhydrous coals exhibits a different composition and physicochemical properties in comparison with normal coals. In the present investigation, a structural study of perhydrous coals and coke was done using FTIR and HPLC data. These coals have high volatile matter with high-calorific values and low-moisture content. The structural study suggests that the major structural units of these coals are simple phenols with para-alkyl substituted derivatives. They have high alkyl substitution groups and low aromatic compounds. The structural studies reveal that these coals contain high amounts of low-molecular weight PAH compounds with 1-2 ring structures. These 1-2 ring structures have high H/C ratios as compared to large ring polyaromatic hydrocarbons (PAHs). It may also be one of the reasons for high H/C ratios in these coals. The alkyl groups contribute significantly to their high volatile matter (VM) contents. The presence of alcoholic groups found in pyrolytic products may also be due to the conversion of catechol-like structures to those of cresols. Coal properties, such as moisture, VM, H/C ratio, and CV,
PM 2.5 and PM 10 samples collected at a suburban site of northeastern part of India have been ana... more PM 2.5 and PM 10 samples collected at a suburban site of northeastern part of India have been analysed for particle mass, total carbon (TC), water-soluble total carbon (WSTC), water-soluble organic carbon (WSOC), water-soluble inorganic carbon (WSIC), organic acids (formic, acetic, proponoic and oxalic acids) along with inorganic ions (NO 3 − , SO 4 2− and NH 4 −). Most of the PM 10 consists of PM 2.5 in the present site (ratio 54-74%). WSTC content in PM 2.5 and PM 10 corresponds to 21% and 16%, respectively, of their total particle masses. Thermo gravimetric analysis showed the presence of humic-like substances (16-22%) in particulate samples. Domestic heating and stagnant atmospheric conditions enhanced the levels of these carbonaceous compounds in PM 2.5 and PM 10 in winter. Qualitative estimation of various functional groups by Fourier transform infrared (FTIR) analysis indicates the presence of carboxylic, hydroxyl, aliphatic and aromatic hydrocarbons, amines and sulphurous compounds in these aerosols. Absolute principal component analysis applied on the aerosol data resolves four factors. These factors are associated with carbonaceous aerosols released from combustion of coal and wood, secondary inorganic and organic aerosols and water-soluble inorganic fraction.
Journal of the Geological Society of India, Sep 1, 2015
Six high sulphur coal samples along with two fly ash samples were characterized by using X-ray di... more Six high sulphur coal samples along with two fly ash samples were characterized by using X-ray diffraction (XRD), Energy Dispersive x-ray Fluorescence (EDXRF), Atomic Absorption Spectroscopy (AAS), Fourier Transform Infrared (FT-IR) and Scanning Electron Spectroscopy (SEM) techniques to interpret their mineral matters and inorganic constituents. The proximate, ultimate and sulfur analyses of the coal and fly ash samples were also performed to know their possible aspects of utilization. Significant amount of silicate/clay minerals along with other elements are found to be present in these coals and fly ash samples. The SEM micrographs showed the presence of pyrite and marcasite in different forms including clusters of pyrites in the coals. The leaching characteristics of the coal and fly ash samples showed the mobilization of some potentially hazardous elements (PHEs) from them. Mercury was found to be leached out with ~0.50 ppm from fly ash samples in water.
Bio-energy is now emerging as a future source of energy. Pyrolysis is one of the main thermo-chem... more Bio-energy is now emerging as a future source of energy. Pyrolysis is one of the main thermo-chemical processes that can provide a useful and valuable bio-fuel such as biooil and bio-char. Bio-oil was produced from an undesired bioweed named Ipomoea carnea by thermal pyrolysis at a terminal temperature range from 350 to 600°C with a heating rate of 10°C/min. Maximum bio-oil yield (41.17 % of which 11.45 % is the oil phase) was obtained at a pyrolysis temperature of 550°C. The oil obtained was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR; 1 H and 13 C), and gas chromatography-mass spectroscopy (GC-MS) which revealed the presence of various hydrocarbons and alcohols. The H/C molar ratio (1.49) of the bio-oil was found to be comparable with petroleum-derived diesel. However, the presence of oxygen (35.86 %) in the form of oxygenates especially organic acids make the bio-oil acidic, which needs to be upgraded to use in the current IC engine.
Mining practices, present and past, contribute towards environmental degradation affecting the ec... more Mining practices, present and past, contribute towards environmental degradation affecting the ecosystems and human health. The unscientific coal mining in the tertiary North Eastern Region (NER) Indian coal mines poses a serious threat to the environment. Dumping of waste rocks including mine rejects generated during mining adds to the problem by aqueous weathering and discharge of acidic effluents. The coal mining in Meghalaya causes large-scale destruction and degradation of the environment. Coal extraction in the state is done by primitive sub-surface mining methods commonly known as 'rat hole' mining. The indiscriminate and unscientific mining, absence of post mining treatment and management of mined areas are making the fragile ecosystems more vulnerable to environmental degradation and leading to land use changes. The main problems in Meghalaya are the production of Acid Mine Drainage (AMD) in nearby areas by continuous leaching of acidic waste from the coal mining sectors. An Environmental Management Plan (EMP), has been developed for management of AMD in high sulphur coalmines by simulation of AMD from weathered coals and mine rejects. Sequential alkalinity producing (SAP) coupled with biological processes found effective in controlling AMD and reducing TDS, Conductivity, SO 4 and toxic elements. In this paper, the state of art for AMD and the processes suitable for the management of AMD are discussed.
The preparation of some oxides and mixed oxide sorbents with aluminosilicate type of binders for ... more The preparation of some oxides and mixed oxide sorbents with aluminosilicate type of binders for high temperature desulphurisation of fuel gases is di scussed. The sorbents investigated are extrudates of ZnO, Indian iron-ore fm es and slimes, ZnO-iron ore fines , ZnO-iron ore slimes, CuO-iron ore slimes, combusted coal ashes (CCA), CuO-CCAs, Zn0-Fe20 3 , Cu0Fe203 and CuO-Fe20 r A1 20 3. These sorbents have been found highly efficient in absorbing sulphurous gases . The fresh, sulphidised, regenerated sorbents of mixed metal oxides and their chemical ph ases have been identified by X-ray diffracti on technique. The presence of x-chalcopyrite, ZnS, morihoikite, CuFe2S3 , CuFeS3, Cu3(S04)(0H)4 and CuS04 5H20 in both major and minor phases in th e sulphidised samples indi cate the absorption of sulph r from sulphurous gases at hi gh temperatures. The crushing strength of the fresh, sulphidised, regenerated and resulphidised sorbents has been determined. The performance o f the sorbents ...
International Journal of Coal Science & Technology, 2021
In this research work, isolation of humic acid from coal of Northeastern region of India is repor... more In this research work, isolation of humic acid from coal of Northeastern region of India is reported. The study is also targeted for application of the coal-derived humic acid in acid mine drainage (AMD) water treatment and electrochemical devices. All the obtained results are compared with the standard humic acid and examined the formation of humic acid from the coal. The isolated coal-derived humic acid is found to be high degree of humifications and relatively stable up to about 200 °C. The FTIR study indicates the formation of metal-humic acid complexes. On treatment with acidic water (AMD), the coal-derived humic acid was found to have the ability to remove toxic metal such as (in order) Pb > Cu > Zn > Cd. In addition, the preliminary electrochemical properties of the isolated humic acid are also discussed in the paper. The specific capacitance of the isolated coal-derived humic acid via cyclic voltammetry and charge-discharge analysis is found to be 7 mF/g at scan rat...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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