Coal Fire Zones Research Articles

Fire zone forefront residual tar combustion characteristics and functional group transformation mechanism: Appling the based on thermogravimetric and in-situ high-temperature FTIR

When preventing spontaneous combustion disasters in extinguished coal fire zones, the influence of the tar re-ignition phenomenon is often overlooked. Therefore, in this study, using thermogravimetric analysis and high-temperature (630 °C) in-situ infrared technology, the combustion reactivity and real-time evolution mechanism of key functional groups for tar were deeply discussed under oxygen-lean conditions. Additionally, a novel two-step baseline drift correction method for spectral graphs at high temperatures is proposed. The results showed that tar combustion could be divided into two stages: pyrolysis-volatilization mass loss and crosslinked structure oxidation combustion. Reduced oxygen concentration limits the violent and stable rapid combustion of tar-crosslinked structures and reduces the re-ignition tendency of tar. Among, with a decrease in oxygen concentration, H (burnout performance), Cb (the reaction ability in the early stage of ignition) and S (overall combustion performance) decreased, while Ti (mass loss endpoint temperature), Th(burnout temperature), and HF (combustion stability) increased. This provides information for the selection of a reasonable process to prevent tar re-ignition. The contents of methylidene and aldehyde carbonyl in tar increased by approximately 2 and 3.7 times, respectively, compared to those of raw coal. In the first thermal decomposition stage of tar, the aromatic hydrocarbons were relatively stable under the action of the structural framework, whereas aliphatic hydrocarbons continued to decrease. Before burnout, a decrease in oxygen concentration increased the crosslinking ability of tar and delayed the tar burnout process. The contents of aromatic hydrocarbons and aldehyde groups are highly sensitive to the evolution of the oxygen concentration. Specifically, the Kubelka–Munk value of the aromatic hydrocarbons increased from 0.015 to 0.10, while that of aldehyde carbonyl groups increased from 0 to 0.23. Additionally, in the early stage of tar combustion, the volatile mass loss was basically not affected by the time-scale effect, and mass loss endpoint residual mass was approximately 48.11 %. In the later stage of tar combustion, owing to the cumulative of time-scale effect, the tar re-ignition tendency increased, H, Cb, and S increased, and HF decreased from 1.388 to 1.098. This research is helpful guiding disaster prevention and control of tar re-ignition in a fire area, which leads to reburning in the surrounding area.

Active–Passive Remote Sensing Identification of Underground Coal Fire Zones With Joint Constraints of Temperature and Surface Deformation Time Series

Active–Passive Remote Sensing Identification of Underground Coal Fire Zones With Joint Constraints of Temperature and Surface Deformation Time Series

A Multisource Remote Sensing Identification Method for Coal Fire Zones Based on a Three-Layer Ensemble Learning Model

A Multisource Remote Sensing Identification Method for Coal Fire Zones Based on a Three-Layer Ensemble Learning Model

Oxygen-Lean Combustion Law of Briquetted Coal Under Stress in Coal Field Fire Zone

ABSTRACT Coalfield fires have become a major hidden danger in mining operations. In order to analyze the laws of coal oxidation and combustion under stress, a uniaxial pressurized experiment was conducted on briquettes. The results show that as the temperature rises, the oxygen consumption rate of the oxidative combustion of the coal sample increases. This rate is higher in the active stage (120–200°C). CO and CO2 gases begin to be generated in the awakening stage (60–70°C), while hydrocarbon gases are gradually generated in the active stage. Additionally, the index gas escape rate is relatively high under a specific axial pressure (4MP). The cross point temperature of the coal sample at 4MP is lower (86.9°C), and the maximum heating rate is higher (0.117°C/s) compared to other coal-oxygen samples with axial pressure applied. The application of axial pressure has two functions including opening pore channels and compacting particle space, which affect the oxidative spontaneous combustion of coal samples. The research results provide a strong scientific basis and theoretical guidance for the detection and prevention of coalfield fires.

Assessment of Mechanical Properties for High-Temperature Sandstone in Coal Fire Area Based on Different Cooling Methods

The rocks in coal fire areas are often in high-temperature environments. The mechanical properties of rocks play an important role in mining and engineering disturbance, so we aim to study the static and dynamic properties of high-temperature sandstone in the coal fire zone under different cooling methods, and to evaluate the degree of thermal damage at different high temperatures. The mechanical properties and failure modes of two cooling methods (natural cooling and watering cooling) were analyzed. In addition, the influence of the longitudinal wave velocity (Vp) on the mechanical properties of the high-temperature sandstone was analyzed, and the composition of the high-temperature sandstone was tested by XRD method. Under two cooling conditions, the static and dynamic peak strength of sandstone increases continuously with the increase of longitudinal wave velocity (Vp), and reduces with the increase of heat-treated temperature, but the damage degree increases with the increase of the heat treatment temperature. In the Split Hopkinson Pressure Bar (SHPB) test, the dynamic compressive strength of naturally cooled sandstone is higher than that of water-cooled sandstone. The failure of natural cooling high-temperature sandstone mainly occurs “X-shape”, transverse splitting failure or breaks into pieces, but the watering cooling high-temperature sandstone presents transverse or longitudinal splitting failure.

Practical Application of Oxygen Augmentation Observation in the Process of Unsealing Fire Zone: Case study of Yu Wu coal mine in China

It is very important to unseal the closed coal mine fire zone safely. Although the fire source disappears in the closed fire zone, it is uncertain whether there are still have high-temperature ignition points, and there is a risk of fire or even explosion again after unsealing. To ensure that the closed fire zone can be unsealed successfully at one time, the study puts forward the method of oxygen augmentation observation to understand the combustion state of the closed fire zone in underground coal mine from the perspective of gas analysis technology. When the mine fire is detected to be extinguished, the method is to inject 8–12% oxygen into the fire area, and the fire area shall be monitored for 2 weeks to determine whether the fire area is completely extinguished. The accuracy and practicality of the method of oxygen augmentation observation are verified by comparing and analyzing the difference results generated by two oxygen augmentation observations in closed zone of Yuwu Coal Mine. In this paper, the use conditions of unsealing in fire zone, detailed methods and steps in the whole process of unsealing and emergency rescue plan are given. The research results can provide valuable reference for one-time safe unsealing of fire zone during the process of disaster relief.

Studying the coal fire dynamics in Jharia coalfield, India using time-series analysis of satellite data

Coal fires in Jharia coal field (JCF) leads to significant loss of coal and pollutes the environment through emission of toxic gases. The present study aims to analyze the coal-fire dynamics in JCF during 1989–2019 through time-series analysis. The study used thermal band data of Landsat-5 and Landsat-8 along with the radiosonde data for estimating the land surface temperature (LST) using single channel algorithm. The year-wise coal fire maps were overlapped for analysing the trends of coal fire. The results indicated that coverage area of coal fire zones has been continuously increased from 1989 to 2019. The new fire zones established at every five-year interval from 1989 to 2019 were mapped for understating the fire dynamics. The results indicated that the fire propagation was not in any specific direction. That is, new fire zones developed pocket-wise due to multiple factors and not due to continuous burning of in-situ coals. It has been observed that production level in the mines during this period also been increased possibly through more number of mines. Thus, more number of coal blocks exposed to atmosphere, which leads to catches of fire due to spontaneous heating.

Numerical study on the evolution of methane explosion regions in the process of coal mine fire zone sealing

To explore the distribution rules of methane explosion regions after the beginning of coal mine fire zone sealing, this paper analyzes the change law of methane explosion limits under the influence of CO2 and CO by using a thermal balance methodology. The distribution rules of methane, smoke and oxygen in the fire zone are obtained for different fire source locations. On this basis, the temporal and spatial distributions of the methane explosion regions at the working face are determined. The modeling results show that during the sealing process, the methane explosion limits are greatly affected by fire smoke. In the early stage of sealing, the methane explosion limit range in the fire zone is reduced due to the dilution of CO2, but later, due to the production of CO, the risk of methane explosion increases. A methane explosion region will appear in the working face tunnel within 1 h after the beginning of sealing, and the timing is closely related to the location of the fire source. When the fire source is located on the intake side of the working face, the methane explosion region first appears on the return side and has the longest duration among all the cases studied; the methane explosion region appears the earliest when the fire source is located on the return side of the working face, and the possibility of methane explosion is the largest in this case.

Black carbon aerosols from the coal seam of eastern India: A real-time analysis with statistical validation

Underground coal seam fire is one of the serious problems caused by coal mining activities. Hence, the present study is focused on investigating the potential emission of black carbon (BC) and its dispersion from the fire-affected area located in the Jharia coal field, Dhanbad district of the Jharkhand state of India. The real-time BC concentration measurements in the active fire area and the adjacent neighbouring urban area were studied and reported. Results showed an average concentration of BC was 12.54 $$\upmu $$ g m $$^{-3}$$ in the fumes/smokes emitting from the surface cracks and vents at the fire-affected zone. The continuous probability distribution functions, i.e., lognormal, gamma and Weibull, were used to fit the BC data individually, and among these lognormal fits, the best were for the medium-range values. Furthermore, the robustness of the obtained BC concentration was also explained by these models. All fitness was in good agreement, in the studied area, with the coefficient of regression ranging between 0.84 and 0.96. Both the experimental and predicted results clearly indicated the contribution of the BC that discharged from the coal seam fire as a source of particulate pollutant. Spatial modelling was also performed to validate the experimental consistency of BC concentration while the model was in good agreement with the underground coal fire zone as compared to the rest.

Underground Coal Fires Identification and Monitoring Using Time-Series InSAR With Persistent and Distributed Scatterers: A Case Study of Miquan Coal Fire Zone in Xinjiang, China

The Xinjiang is an important coal production base in China and also a serious coal fire disaster area. Coal fires not only waste resources, but also cause air pollution and damage to the ecological environment. Hence, it is very important to identify and monitor the underground coal fire areas accurately and efficiently for the control of coal fires. Interferometric synthetic aperture radar (InSAR) technology identifies and monitors coal fire areas by monitoring surface subsidence caused by burned out area. Compared with traditional coal fire monitoring technology, InSAR technology has the advantages of all-weather and high efficiency. But the fire areas are often distributed in wild areas, this factor significantly limits the application of the traditional Persistent Scatterer interferometry (PSI) technology. In addition, Xinjiang coal fires are mostly located in historical goafs, so it is necessary to distinguish the subsidence caused by mining and coal fires. Therefore, distributed scatterer interferometry (DSI) technology is used to monitor the Miquan fire area in Xinjiang in this paper. The results show that compared with PSI technology, DSI technology can expand the number of effective monitoring points 124 times. On this basis, spatio-temporal analysis of surface subsidence in the study area suggests that the subsidence caused by mining and coal fires exhibits significantly different space-time evolution rules. Therefore, in the future, the coal fire area and mining area can be separated and identified according to these rules. The final identified coal fire area contains all measured coal fire points, and accurately monitors the fire extinguishing area.

Investigation of the potential risk of coal fire to local environment: A case study of Daquanhu coal fire, Xinjiang region, China

Underground coal fires are disasters associated with coal mining activities. This study, attempts to investigate the impact of coal fires on the soil and atmosphere by measuring heavy metal concentration and borehole gas emissions for the Daquanhu coal fire zone. Different methods and equipment were used in this study, such as remote sensing, determination of the surface temperature and vegetation, field meteorological surveys, air/smoke analysis, flame photometry, atomic absorption spectrophotometry, atomic fluorescence spectrophotometry, and alkali diffusion. The results show that the surface temperature of the Daquanhu coal fire zone was reduced with a progress in coal fire extinction since 2015. Surface vegetation grew better in 2016 than in other years. The mercury (Hg) content in the western part of the fire zone is much higher than that in other parts of the fire zone. The arsenic (As) content in the eastern part is much higher than that of other parts. Data show that the estimated total amount of gas emissions during fire extinction is ~31,500 kg for CO, 489 kg for SO2, 12,885 kg for NO, 576 kg for NO2, and 20,295 kg for NOx. The intensity of the gas emissions during extinction is notably higher than that before extinction. The results also indicate coal fire's potential risk to adjacent communities, especially the risks associated with borehole injection of large amounts of possible harmful slurry, which needs to be taken seriously.

Forced Convective Heat Extraction in Underground High-Temperature Zones of Coal Fire Area

Coal fires exist in almost every coal-producing country and generate huge amounts of heat energy every year. In this paper, forced convective heat-extraction is presented as a method to exploit the potential heat in coal fire zones as an energy resource. A geological model of coal fire zones and a combustion model for underground coal in an O2-depleted atmosphere are established. The borehole layouts, the heat transfer medium (HTM) injection rates, and the cooling effect of the HTM on the coal and rock are analyzed using a three-dimensional (3D) simulation software (fluent). The results show that a borehole layout of multihole injection and oriented type proves to be suitable for coal fire zones. The simulation predicts that the temperature of the extracted HTM and the rate of heat extraction decrease as extraction time increases. The simulation further predicts that the temperature of the extracted HTM can be increased by reducing the rate at which the HTM injected. Additionally, the heat-extraction rate is more stable for relatively low HTM injection rates. The temperature of the coal fire zones can be reduced effectively by using forced convective heat-extraction, with the maximum temperature of the coal fire zones and the average temperature in the residual coal zone being cubic and quadratic function relationship of the heat-extraction time, respectively. This research provides a reference for waste-energy exploitation in coal fire areas.

Oxidatively and thermally altered high-volatile bituminous coals in high-temperature coal fire zone No. 8 of the Wuda Coalfield (North China)

Coal fires have received increasing attention due to their environmental, economic, and social impacts. Their significant influence on coal properties is widely documented by geophysical and geochemical methods.The present paper demonstrates, by means of coal petrological methods, significant changes of microstructure, optical appearance, and optical properties of medium-rank (bituminous) coals affected by an underground coal fire. The studied changes are suggested to result from distinct oxidative and thermal alterations induced by a high-temperature regime (temperatures over 800°C) encountered in the coal fire zone No. 8, Wuda Coalfield. The investigated coal seam No. 9 represents a high volatile A bituminous coal and is dominated by vitrinite, followed by inertinite with minor amounts of liptinite. The microstructure of the coal-fire affected coals facilitate a broad spectrum of characteristic features. The microscopic analyses revealed development of (1) non-tectonic fissures and non-tectonic fractures, (2) distinct micropores, (3) dark oxidations rims, and (4) bright spots interpreted as incipient mesophases. Optical properties were characterised for megasporinite and vitrinite. In the examined megasporinite a noticeable anisotropy and distinct granular appearance was observed. In the investigated coals both a dominant increase as well as a minor decrease in both random and maximum vitrinite reflectances were documented for (1) coal grains and (2) dark-rimmed vitrinite at non-tectonic fissures and non-tectonic fractures. In addition, also a characteristic bimodal vitrinite population was measured. The increase in bireflectance was clearly documented for two sub-zones within the coal fire zone No. 8. The applied Kilby's cross-plots suggested a large overlapping of the data sets of R'max and R'min, indicating marked changes in vitrinite structure. The applied coal petrological approach revealed distinct changes to the coal's microstructure, appearance, as well as to optical properties induced by the underground coal fire. The presented coal petrographic approach may help determine the extent of coal fires in coal mines and the direction of propagation of coal fire front.

Impact of underground coal fire on coal petrographic properties of high volatile bituminous coals: A case study from coal fire zone No. 3.2 in the Wuda Coalfield, Inner Mongolia Autonomous Region, North China

The Wuda Coalfield located in the Inner Mongolia Autonomous Region, North China is known as one of China's major source of prime coking coals and a site of well-researched and well-documented underground coal fires. The underground coal fire at the coal fire zone No. 3.2 is situated in the active coal mine of Suhai-Tu, located in the north westerly part of the Wuda Coalfield.The present paper investigates the impact of the underground coal fire on the coal seam No. 10 by application of coal petrographic methods, including detailed characteristic of macerals and other coal components, maceral analysis, microstructural analysis, and vitrinite reflectances performed on (1) coal grains lacking impurities, microfractures, dark oxidation rims, (2) on dark-rimmed vitrinite, as well as (3) on low-temperature semi-coke. The investigated coal seam No. 10 represents a high volatile A bituminous coal and is dominated by vitrinite, followed by inertinite with minor amounts of liptinite and by non-isotropic low-temperature semi-coke. The microstructure of the oxidatively and thermally altered coals is represented by (1) extensive non-tectonic microfissures and non-tectonic microfractures i.e., shrinkage microfractures, leading to defragmentation of coal grains, (2) dark oxidation rims observed at grain margins, non-tectonic microfissures and microfractures, and by (3) devolatilisation micropores. Random vitrinite reflectances measured in (1) coal grains lacking impurities, microfractures, and dark oxidation rims, and in (2) dark-rimmed vitrinite at non-tectonic microfissures and fractures reveal significant lateral variations. The presence of low-temperature semi-coke and its marked lower reflectance values are indicative of thermal alteration induced by the underground coal fire in the coal fire zone No. 3.2. The results obtained from the performed analyses of organic matter point to both low-temperature oxidation and low-temperature-pyrolysis processes. The applied coal petrological approach revealed characteristic changes to the coal's microstructure, its petrographic composition, as well as to optical properties induced by the underground coal fire.

Using spatiotemporal remote sensing data to assess the status and effectiveness of the underground coal fire suppression efforts during 2000–2015 in Wuda, China

China, the largest coal consumer in the world, is one of the countries that experience the most coal fires. Hence, it is critical for China to monitor coal fires and carry out coal fire monitoring, assessment, and appropriate suppression work. The Wuda coalfield, located in China's Inner Mongolia Autonomous Region, was selected as the study area. This paper was aiming to analyze spatiotemporal changes of coal fires located in Wuda of China from 2000 to 2015 and focused on the assessment of fire protection project during 2006–2008. Landsat Thematic Mapper and Enhanced Thematic Mapper Plus images were used to detect changes in coal fires over the last 16 years by utilizing a generalized single-channel method to retrieve land surface temperature data and natural breaks extracting coal fire zones. The results showed that: 1) the changes of coal fires area represented obvious three stages: Stage I (2000–2006) was before the fire suppression project with fire spread and expansion; Stage II (2006–2008) was the implementation of this project with rapid reduction of fire area; Stage III (2008–2015) was after this project with stable fire area at a low level; 2) the fire suppression work was highly successful; the area of coal fires basically remained at 192.98 ha, a reduction by 45.74% from 2000 and 62.40% from 2006 (before fire suppression projects); 3) fire suppression work in the south (zone F) and in the northwest (zone A) was the most successful, while some new patches sporadically appeared in other regions (zone B, C and D); 4) coal fire suppression methods have led to significant destruction of local geomorphology; 5) it was difficult to completely extinct coal fires underground with current suppression method. Compared with previous studies, this research paid more attention to the estimation of fire suppression projections which provided an available way for environment decision makers and coal energy producers to qualitatively assess the status and effectiveness of coal fire suppression projects.

Modeling of the equivalent permeability for an underground coal fire zone, Xinjiang region, China

Underground coal fires (UCFs) constitute severe disasters, yet the quantification of the process of coal fire propagation, the first step in knowing how to extinguish a UCF, remains a great challenge even after decades of research. An important feature for understanding oxygen supply to a coal fire is the permeability of the UCF zone. Here, we propose a model for a typical UCF zone based on an analysis of the deformation of the overlying rocks caused by the UCF. We delineate the physical boundaries of the UCF and show how the zone includes both porous media and fractured zones. We then attempted to quantify the permeability of these porous and fractured zones and use the quantitative model to design, build, and employ an elementary UCF air/smoke flow experimental apparatus to run a permeability experiment. Subsequent to the experiments, we used simulation software to build a numerical model of the experimental apparatus. Calculated results from the numerical model agreed reasonably well with results from the physical experiments, though for this model to be applied in practice to quantify UCF propagation, further research on problems such as the size and distribution of the fractures and the relationship between the fractures and stress in the rock matrix will be required.

Analysis of coal fire dynamics in the Wuda syncline impacted by fire-fighting activities based on in-situ observations and Landsat-8 remote sensing data

Coal fires are a global catastrophe for valuable coal resources, the environment, human health and safety. Fire-fighting activities are the approach to limit these catastrophic influences and to extinguish active coal fires. The Wuda syncline in Inner Mongolia is one of the biggest coalfields suffering from coal fires in China, and is one of the coalfire areas globally, which has been analyzed most comprehensively. Massive fire-fighting activities have been undertaken to quench coal fires in the Wuda syncline. Particularly, activities such as blasting and excavation have accelerated since the year 2010. Influence of fire-fighting activities on coal fire dynamics is a significant topic but has rarely been reported yet. Although airborne and spaceborne earth observation data holds the potential to monitor extinguishing activities, this data is rarely applied for this purpose. Airborne thermal scanner data is cost intensive to fly, and spaceborne Landsat-7 scanner system with a thermal band at 60m spatial resolution in 2003 led to a limited exploitation of this valuable data source. Just recently, Landsat-8 satellite data, with a thermal infrared band of 100m spatial resolution is available since early 2013 and is able to fill this gap. We conducted in-depth in-situ surveys on coal fires and fire-fighting activities in the Wuda syncline in May 2014 after visiting the Wuda coalfield in 2012. We integrated our in-situ observations and thermal anomalies extracted from both Landsat-8 and Landsat-7 (SLC-on, acquired before the scanner failure) satellite data using an automated moving-window thermal anomaly extractor (regional anomaly extractor, RAE), and analyzed coal fire dynamics impacted by fire-fighting activities and the state of coal fires in the Wuda syncline. Results show that after over 4years of efforts to fight against coal fires in the Wuda syncline, the Nos. 1–7, No. 9, No. 12, and No. 13 coal fire zones are extinct. However, the No. 8, No. 10, No. 11, and No. 14–No. 18 coal fire zones are still active, and furthermore three novel coal fire zones have evolved. In the light of in-situ surveys in the Wuda coalfield, these active and newly developed coal fires are mainly attributed to extinguishing related activities, such as the blasting and excavation in fire affected areas, which lead to the exposure of pure coal seams, weathered coal pillars, and coal waste piles to the outside air. The contact of this coal and coal remnants with oxygen triggers spontaneous combustion of coal and further develops to coal fires. Additionally, time-series analyses of extracted thermal anomalies suggest that coal fires propagate eastward according with the dip direction of coal seams in the Wuda coalfield.The regional thermal anomaly extraction tool (RAE) can delineate thermal anomalies with a high accuracy, which is confirmed by our in-situ surveys. This paper is the first investigation on dozens of Landsat satellite images to evaluate the state of coal fires within one year, which is more accurate compared to previous approaches analyzing merely one or several satellite images to assess the state of coal fires during one year period.

Monitoring subsurface coal fires in Jharia coalfield using observations of land subsidence from differential interferometric synthetic aperture radar (DInSAR)

Coal fires in the Jharia coalfield pose a serious threat to India’s vital resource of primary coking coal and the regional environment. In order to undertake effective preventative measures, it is critical to detect the occurrence of subsurface coal fires and to monitor the extent of the existing ones. In this study, Differential Interferometric Synthetic Aperature Radar (DInSAR) technique has been utilized to monitor subsurface coal fires in the Jharia coalfield. Results showed that majority of the coal fire-related subsidence were concentrated on the eastern and western boundaries of the coalfield. The magnitude of subsidence observed was classified into high (10–27.8 mm), low (0–10 mm) and upliftment (−10–0 mm). The results were strongly supported by in situ observations and satellite-based thermal imagery analysis. Major subsidence was observed in the areas with repeated sightings of coal fire. Further, the study highlighted on the capability of the methodology for predicting potential coal fire zones on the basis of land surface subsidence only. The results from this study have major implications for demarcating the hazardous coal fire areas as well as effective implementation of public safety measures.

Mapping Land Subsidence Related to Underground Coal Fires in the Wuda Coalfield (Northern China) Using a Small Stack of ALOS PALSAR Differential Interferograms

Coal fires have been found to be a serious problem worldwide in coal mining reserves. Coal fires burn valuable coal reserves and lead to severe environmental degradation of the region. Moreover, coal fires can result in massive surface displacements due to the reduction in volume of the burning coal and can cause thermal effects in the adjacent rock mass particularly cracks and fissures. The Wuda coalfield in Northern China is known for being an exclusive storehouse of prime coking coal as well as for being the site of occurrence of the maximum number of known coal fires among all the coalfields in China and worldwide, and is chosen as our study area. In this study, we have investigated the capabilities and limitations of ALOS PALSAR data for monitoring the land subsidence that accompanies coal fires by means of satellite differential interferometric synthetic aperture radar (DInSAR) observations. An approach to map the large and highly non-linear subsidence based on a small number of SAR images was applied to the Wuda coalfield to reveal the spatial and temporal signals of land subsidence in areas affected by coal fires. The DInSAR results agree well with coal fire data obtained from field investigations and thermal anomaly information, which demonstrates that the capability of ALOS PALSAR data and the proposed approach have remarkable potential to detect this land subsidence of interest. In addition, our results also provide a spatial extent and temporal evolution of the land subsidence behavior accompanying the coal fires, which indicated that several coal fire zones suffer accelerated ongoing land subsidence, whilst other coal fire zones are newly subsiding areas arising from coal fires in the period of development.

The New Fire Prevention Materials Using in the Coal Fire Zones-Foamed Gel

Coal fires are emerging as a global threat with significant economic, social and ecological impacts, besides the loss of energy resources those fires cause air and water pollution and emit enormous amounts of green house gases (carbon dioxide and methane), how to prevent and extinct the fires has been a worldwide issue. According to the respective limitation and characteristic of gel fire prevention materials and foam fire prevention materials, a new thinking of foamed gel coal fire prevention materials is put forward creatively. Foamed gel that includes the characteristic of gel and foam possessed the property of accumulation. It also has the performance of sealing and secluding oxygen. This paper describes the composition and characteristic of foamed gel, as well as the laboratory production process. For large coal fire zones, the new fire prevention materials (Foamed Gel) have a broad application prospect.