Development a modified crossing point temperature (CPTHR) method to assess spontaneous combustion propensity of coal and its chemo-metric analysis

Spontaneous combustion of Indian coals was investigated using spontaneous combustion rig at University of Nottingham, UK to assess their susceptibility. In the present study authors have used eleven coal samples collected from the Jharia coalfield (JCF), India. Both thermal as well as gas profiles from spontaneous combustion rig were studied critically to develop a modified crossing point temperature to assess the spontaneous combustion propensity of coal. The product of combustion gases (CO, CO2, CH4, and H2) emitted from spontaneous combustion rig within the temperature range between ambient and 300 0C of these coal samples were studied. The initial product of combustion gas i.e. CO followed by H2 indicates propensity towards oxidation of coal in laboratory condition for Jharia coalfield. The temperatures at which CO and H2 releases in the level of 50ppm (TCO50, TH250), crossing point temperature of coal (CPTCT) (temperature of coal and bath temperature is same) and modified crossing point temperature of coal (CPTHR) (temperature where dT/dt is equal to 2.0 oCmin-1 because heating rate is double of programme temperature 1 oCmin-1) determined from spontaneous combustion rig categorises the coal as per their propensity to spontaneous combustion. The results of these methods have been compared with other standard method i.e. crossing point temperature method – India, which is widely adopted in Indian regulatory bodies to verify the suitability of this method

Development of a petrographic technique to assess the spontaneous combustion susceptibility of Indian coals

Petrographic studies are commonly used categorise the potential utilisation of coals. Eleven coal samples from the jharia coalfield (JCF), india, were studied using petrographic techniques to investigate maceral content, reflectance, and textural characteristics. Multiple test samples of each coal were slowly oxidised under controlled laboratory conditions from an ambient temperature of 30°c to 300°c to investigate the morphology of oxidised coals. The petrographic characterisation of the coals before and after oxidation showed important changes in both morphology and vitrinite reflectance. The oxidation of the coal particles produced three predominant textural changes: particles with homogeneous change of reflectance (HCv), particles with oxidation rims (ORv), and particles with no changes were observed (Uv) respectively. These textural characteristics were used to indicate how particles had interacted with oxygen at low temperatures during the early stages of oxidation. The morphological classification developed provides an alternative method to confirm the susceptibility of a coal to spontaneous combustion. Conventional thermal parameters such as crossing point temperature (CPT) were unable to identify the coals prone to spontaneous combustion. However, certain petrographic parameters could be combined with CPT values to provide a much more accurate measure for susceptibility to spontaneous combustion

Review of experimental methods to determine spontaneous combustion susceptibility of coal – Indian context

This paper presents a critical review of the different techniques developed to investigate the susceptibility of coal to spontaneous combustion and fire. These methods may be sub-classified into the two following areas: (1) Basic coal characterisation studies (chemical constituents) and their influence on spontaneous combustion susceptibility. (2) Test methods to assess the susceptibility of a coal sample to spontaneous combustion. This is followed by a critical literature review that summarises previous research with special emphasis given to Indian coals

Development of a petrographic technique to assess the spontaneous combustion susceptibility of Indian coals

Petrographic studies are commonly used to categorize the potential utilization of coals. Eleven coal samples from the Jharia coalfield (JCF), India, were studied using petrographic techniques to investigate maceral content, reflectance, and textural characteristics. Multiple test samples of each coal were slowly oxidized under controlled laboratory conditions from an ambient temperature of 30°c to 300°c to investigate the morphology of oxidized coals. The petrographic characterization of coals before and after oxidation showed significant changes in both morphology and vitrinite reflectance. The oxidation of coal particles produced three predominant textural changes: particles with homogeneous change of reflectance (HCv), particles with oxidation rims (ORv), and particles with no changes were observed (Uv), respectively. These textural characteristics were used to indicate how particles had interacted with oxygen at low temperatures during the early stages of oxidation. The morphological classification developed provides an alternative method to confirm the susceptibility of a coal to spontaneous combustion. Conventional thermal parameters such as crossing point temperature (CPT) were unable to identify the coals prone to spontaneous combustion. However, certain petrographic parameters could be combined with CPT values to provide a much more accurate measure for susceptibility to spontaneous combustion

Development a modified crossing point temperature (CPTHR) method to assess spontaneous combustion propensity of coal and its chemo-metric analysis

Spontaneous combustion of Indian coals was investigated using sponcomb rig at University of Nottingham, UK to assess their susceptibility. In the present study authors have used eleven coal samples collected from the Jharia coalfield (JCF), India. Both thermal as well as gas profiles from sponcomb rig were studied critically to develop a modified crossing point temperature to assess the spontaneous combustion propensity of coal. The product of combustion gases (CO, CO2, CH4, and H2) emitted from sponcomb rig within the temperature range between ambient and 300°C of these coal samples were studied. The initial product of combustion gas i.e. CO followed by H2indicates propensity towards oxidation of coal in laboratory condition for Jharia coalfield. The temperatures at which CO and H2 releases in the level of 50 ppm (TCO50, TH250), crossing point temperature of coal (CPTCT) (temperature of coal and bath temperature is same) and modified crossing point temperature of coal (CPTHR) (temperature where dT/dt is equal to 2.0 oCmin−1 because heating rate is double of programme temperature 1 oCmin−1) determined from sponcomb rig categorises the coal as per their propensity to spontaneous combustion. The results of these methods have been compared with other standard method i.e. crossing point temperature method – India, which is widely adopted in Indian regulatory bodies to verify the suitability of this method

AN INVESTIGATION TO OPTIMISE THE EXPERIMENTAL PARAMETERS OF DIFFERENTIAL SCANNING CALORIMETRY METHOD TO PREDICT THE SUSCEPTIBILITY OF COAL TO SPONTANEOUS HEATING

Researchers all over the world have attempted to study spontaneous heating susceptibility of coal by different methods. Amongst all these methods, thermal studies have been widely applied. There are many techniques used in thermal studies of coal and these are differential thermal analysis, differential scanning calorimetry (DSC), crossing point temperature, modifi ed crossing point temperature, puff temperature, initial temperature determination, Russian method, H2O2 method, Olpinski index and adiabatic calorimetry. It may be mentioned here that amongst these techniques DSC has been found to be more sophisticated and it gives reproducible results under similar experimental conditions. These experimental conditions are atmosphere of heating, sample size, heating rates, fl ow rates of carrier gas and amount of sample. However, different researchers all over the world have used different experimental conditions and got different results. These results cannot be comparable. As a result the mine planners and practicing engineers are not in a position to apply these results for planning and operating the mines. Therefore, the authors have carried out 84 numbers of DSC experiments to optimise these experimental conditions, so that it can be uniformly applied for comparing the proneness of coal to spontaneous heating. The outcome of the study will be useful by the mine planners and practicing engineers to take ameliorative measures in advance to prevent the occurrence of coal mine fire

Development of a noise model with respect to sound propagation and its application to a mining complex

A noise source radiates sound energy and will get attenuated to some extent until it reaches the receiver point. The five salient parameters for noise attenuation were considered here, e.g. geometric spreading, barrier, air absorption, ground effect, and meteorological effect. Algorithms of these attenuation parameters were evaluated based on the following considerations. • All the noise sources were considered as point sources or line sources or plane sources. • No directivity index was considered. • For all the receiver points the minimum resultant sound pressure level due to any number of sources was considered to be equal to the background sound pressure level of that area. Based on these algorithms,the programming was written in 'C' language. The noise database of Bhelatand mining complex of TISCO (Tata Iron and Steel Company Limited) was used to test and validate the model. The final printout of the results indicates the locations and the resultant sound pressure level [Leq(R)] of the receiver points where the resultant sound pressure level exceeded or was equal to the permissible noise level of an industrial area [75 dB]. The ultimate output is a noise contour diagram depicting the sound pressure level (Leq) exceeding the desired level

Application of thermal analysis techniques to assess proneness of coal to spontaneous heating

The paper presents the review of application of three thermal techniques viz; differential thermal analysis (DTA), thermogravimetry (TG) and differential scanning calorimetry (DSC); for studying the susceptibility of coal to spontaneous heating and fire. It also critically analyses the experimental standards adopted by different researchers, while applying these techniques in studying thermal behaviour of coal samples. The paper also presents the future direction of research in this subject area

Application of Carbon Dioxide (CO2) for controlling subsurface fire area: Indian context

In bord and pillar method of mining, the panels are sealed off after depillaring. Depending upon the site specific condition, 40 to 45 % coal are left in depillared panel as stook, loose coal left in goaf, hard coal on floor and roof of the panel. The left out coals in goaf area start oxidation, and this leads to spontaneous heating in side sealed off area. For assessment of fire in underground coal mines, thermo-compositional monitoring plays an important role. This paper presents scientific relevance and selective criteria for use of inert gas for control of subsurface fire. Finally the paper discusses spontaneous heating problem in sealed off area and application of inertisation technology by using CO2 to prevent and control sealed off fire at Haripur Colliery, Kenda Area, ECL, India