[Analysis of early diagnosis and prevention techniques for occupational pneumoconiosis based on patent perspectives in China's coal industry].

Occupational pneumoconiosis in the coal industry is an occupational disease that seriously endangers coal miners' health. Early diagnosis and prevention techniques are significant in controlling its incidence rate and reducing its harm. This article takes the patent data related to the early diagnosis and prevention of occupational pneumoconiosis in the coal industry, published from 1985 to 2021, as the research object. It uses tools such as the Derwent Data Analyzer (DDA) software, the Patyee Database, and the PatSnap Database to analyze the technological development trend and characteristics in this field from aspects of growth trend, primary patent holders, IPC classification layout, value, and research and development hotspots. The results show that the number of patent applications in this field indicates a rapid growth trend, mainly in the hands of Shandong Energy Group Co. Ltd., Shandong University of Science and Technology, China University of Mining and Technology, and other institutions or enterprises. Patent technology mainly involves spray dust reduction, dust removal fans, dust masks, and other aspects with high patent value and innovation ability. This article provides a new perspective and reference for preventing, diagnosing, and treating occupational pneumoconiosis in the coal industry.

Integrated Evaluation of Financial Risk in Coal Industry Restructuring: A Model of Linear Regression and PCA.

Aiming at the integrated evaluation problem of financial risk in coal industry restructuring, a model of linear regression and PCA is put forward. This paper studies the univariate correlation and multivariable mixed correlation between the main business income and the book value of fixed assets and nonfixed assets in the statements of coal listed companies and gives the correlation function between the variables by using a variety of univariate linear, univariate nonlinear, and binary linear regression methods. It also points out that the coal enterprises in China are basically in the stage of increasing scale income at the present stage and can continue to achieve rapid increase in profits through mergers and acquisitions and other expansion methods. At the same time, it is also concluded that nonfixed assets, namely, intangible assets and human capital, contribute more to the main business income of coal enterprises in China, which objectively proves the correctness of our thinking of developing knowledge economy.

Using homing pigeons to monitor atmospheric organic pollutants in a city heavily involving in coal mining industry.

Coal is the most extensively used fossil fuel in China. It is well documented that coal combustion detrimentally affected air quality, yet the contribution of coal mining activity to air pollution is still largely unknown. Homing pigeons have been applied to assess the occurrence of atmospheric pollutants within cities. Herein, we sampled homing pigeons from both urban and mining areas in a typical coal industry city (Datong, China) as biomonitors for assessing local air pollution. Target organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were frequently detected in lung, liver, and fat tissues of the pigeons. The pollutants were predominately accumulated in lung, validating that respiration was the main accumulation route for these compounds in homing pigeons. In addition, pathological damage examination in lung and liver tissues revealed that the exposure to atmospheric pollutants impaired pigeon health. While the concentrations of PCBs and OCPs were similar in pigeons from urban and mining areas, the concentrations of PAHs were higher in pigeons from urban area. In contrast, more elevated levels of PBDEs (particularly BDE-209) were found in the mining area, which was consistent with the greater pathological damages and particulate matter levels. Unlike coal combustion, coal mining activities did not increase atmospheric PAH exposure to homing pigeons, but intensified PBDE contamination along with increasing emission of particulate matters. Overall, homing pigeons are promising biomonitors for assessing the respiratory exposure and risk of atmospheric pollutants within cities.

Analysis of the Characteristics of CH4 Emissions in China's Coal Mining Industry and Research on Emission Reduction Measures.

CH4 is the second-largest greenhouse gas and has a significant impact on global warming. China has the largest amount of anthropogenic coal mine methane (CMM) emissions in the world, with coal mining emissions (or gas emissions) accounting for 90% of total energy industry emissions. The results of CH4 emission inventories from previous studies vary widely, with differences in the spatial and temporal dimensions of gas emission factors of belowground mining being the main points of disagreement. Affected by the policies of "eliminating backward production capacity" and "transferring energy base to the northwest", China's coal production layout has changed greatly in the past ten years, but the closely related CH4 emission factors have not been dynamically adjusted. This paper investigated 23 major coal producing provinces in China, obtained CH4 emission data from coal mining, calculated CH4 emission factors in line with current production conditions, and studied the reduction measures of coal mine gas emission. According to the CH4 emission data of China's coal mines in 2018, 15.8 Tg of methane is released per year in the coal mining industry in China, and 11.8 Tg after deducting recycling. Shanxi Province's CH4 emissions are much higher than those of other provinces, accounting for 35.5% of the country's total emissions. The weighted CH4 emission factor of coal mining in China is 6.77 m3/t, of which Chongqing is the highest at approximately 60.9 m3/t. Compared with the predicted value of the IPCC, the growth trend of CCM has slowed significantly, and the CH4 utilization rate has gradually increased. This change may be aided by China's coal industry's policy to resolve excess capacity by closing many high-gas and gas outburst coal mines. In addition, the improvement of coal mine gas extraction and utilization technology has also produced a relatively significant effect. This paper determines the distribution of methane emissions and emission sources in China's coal mining industry, which is useful in formulating CCM emission reduction targets and adopting more efficient measures.

Facemasks and ferrous metallurgy: improving gasification reactivity of low-volatile coals using waste COVID-19 facemasks for ironmaking application.

The global pandemic response to COVID-19 has led to the generation of huge volumes of unrecyclable plastic waste from single use disposable face coverings. Rotary hearth furnaces can be used to recover Zn and Fe from non-recyclable steelmaking by-product dusts, and waste plastic material such as facemasks could be utilized as a supplementary reductant for the rotary hearth furnace (RHF), but their fibrous form makes milling and processing to appropriate sizing for RHF application extremely challenging. A scalable method of grinding facemasks to powder by melting and mixing with Welsh coal dust reported herein provides a solution to both environmental challenges. The melt-blended PPE/coal dust shows a dramatically improved CO2 gasification reactivity (Ea = 133-159 kJmol-1) when compared to the untreated coal (Ea = 183-246 kJmol-1), because of improved pore development in the coal during the pyrolysis stage of heating and the catalytic activity of the CaO based ash present in the facemask plastic. The results are promising for the application of waste facemasks in recycling steelmaking by-product dusts in rotary hearth furnaces and may also be suitable for direct injection to the blast furnace subject to further study.

Modeling health impacts of air pollutant emissions from the coal-fired power industry based on LCA and oriented by WTP: a case study.

Coal-fired power plants are one of the major sources of coal consumption in China; they discharge various air pollutants and cause serious human health damage. There is an urgent need to focus on the associated health effects. Thus, this study aims to advance an integrated life cycle assessment (LCA)-based health damage model to quantify the health burden of air pollutant emissions from coal-fired power generation (CFPG) and to achieve an economic interpretation of health damage. A case study of the Zaozhuang coal-fired power project was conducted to better visualize and mitigate the impacts. The results reveal that willingness to pay (WTP) for health damage caused by the CFPG project in 1 year amounted to USD 15.71 million, and the total amount of life lost was 155.81 years. During the CFPG process, coal combustion caused the most health damage, respiratory disease was the type of damage with the greatest influence on health, and SO2 was the air pollutant that causes the most serious health damage. The model developed in this study can be broadly applied to assess the potential life loss due to air pollutant emissions from CFPG systems. The identified key points for health damage prevention can also be used as practical solutions for decision-making regarding the prioritization of control sources for environmental management.

The Effect of the Coal Industry on Indoor Radon Concentrations in eMalahleni, Mpumalanga Province of South Africa.

ABSTRACT: South Africa has rich coal deposits concentrated in the northeast of the country, and as a result, most of the country's coal mining is located in this region. Two of the principal coalfields exploited are the Witbank and Highveld coalfields, located in the Mpumalanga province. Coal contains trace quantities of the naturally occurring radionuclides whose mass concentration can be enhanced by anthropogenic activity. The radioactive fallout from these activities could lead to elevated radon concentrations indoors. Two towns, Secunda and eMalahleni, were identified due to their proximity to coal-based industries. A previous study investigated whether these industries caused elevated radon levels in Secunda homes but found a lower-than-expected average concentration of 76.4 ± 7.6 Bq m-3. This was attributed to either the prevailing wind depositing the radioactive fallout to neighboring towns, such as eMalahleni, or the type of industrial activity. This paper builds on this study by investigating whether elevated radon levels are found in homes in eMalahleni. Measurements were performed in 22 homes during December 2019, and the average indoor radon concentration was calculated as 122.1 ± 8.5 Bq m-3. The cause of these elevated levels was then investigated, and it was found that even though the coal industry contributes to elevated radon levels, the town's underlying geology seems to be the primary contributor.

Towards sustainable coal industry: Turning coal bottom ash into wealth.

Although the world is gradually moving towards renewable energy resources, the coal industry will continue to be a major energy supply sector in the foreseeable future. However, by-products such as coal fly ash (CFA), coal bottom ash (CBA), and boiler slag are generated during coal combustion, and have become a significant environmental concern. There is an urgent need for transdisciplinary efforts in research, policy, and practice to reduce these by-products substantially. Many studies have focused on the environmental management and comprehensive utilization of CFA. As a comparison, less attention has been paid to CBA. Therefore, this critical review provides a holistic picture of CBA, from the generation, fundamental characteristics, environmental concerns to potential applications, and benefits analysis. Based on the fundamental characteristics, CBA can be considered as a sustainable and renewable resource with great potential to produce value-added materials. High-value applications and current research related to CBA, including construction and ceramic industry, wastewater remediation, soil amelioration, energy catalysis, valuable metals recovery, and material synthesis, are systemically presented and compared. It emphasizes the environmental and economic benefits of the sustainable applications of CBA as well. Particularly, it indicates that CBA is a promising candidate in normal, lightweight, self-compacting, and ultra-high-performance concrete, which shows a reduction in both energy consumption and greenhouse gas emissions during concrete production. This work provides new insights into the greener and sustainable applications of CBA, and it will offer a practical guide for the sustainable development of the coal industry.

Correlating bacterial and archaeal community with efficiency of a coking wastewater treatment plant employing anaerobic-anoxic-oxic process in coal industry.

Coking wastewater (CWW) contains various complex pollutants, and biological treatment processes are frequently applied in the coking wastewater treatment plants (CWWTPs). The present work is to evaluate the contaminants removal of a full-scale CWWTP with an anaerobic-anoxic-oxic process (A/A/O), to reveal function of bacterial and archaeal community involved in different bioreactors, and to clarify the relationship between the performance and microbial community. Illumina Miseq sequencing of bacteria showed that ß-proteobacteria dominated in three bioreactors with relative abundance of 60.2%~81.7%. 75.2% of sequences were assigned to Petrobacter in the bioreactor A1, while Thiobacillus dominated in A2 and O with relative abundance of 31.8% and 38.7%, respectively. Illumina Miseq sequencing of archaea revealed a high diversity of methanogens existed in A1 and A2 activated sludge. Moreover, Halostagnicola was the dominant archaea in A1 and A2 activated sludge with relative abundance of 41.8% and 66.5%, respectively. Function predicted analysis explored that function of bacteria was similar to that of archaea but the relative abundance differed from each other. A putative biodegradation model of CWW treatment in A/A/O process indicated that A1 and A2 activated sludge mainly reduced carbohydrate, protein, TN, phenol and cyanide, as well as methane production. Bacteria in the bioreactor O were responsible for aerobic biotransformation of residual carbohydrates, refractory organics and nitrification. The redundancy analysis (RDA) further revealed that removal of COD, TN, and NO3--N, phenol and cyanides were highly correlated with some anaerobic bacteria and archaea, whereas the transformation of NH4+-N was positively correlated with some aerobic bacteria.

Online evaluation method of coal mine comprehensive level based on FCE.

An online evaluation method of coal mine comprehensive level based on Fuzzy Comprehensive Evaluation method (FCE) is proposed. Firstly, following the principles of fairness, systematicness and hierarchy, taking research and development, production, sales, finance, safety and management as the first level indicators, a set of multi-level evaluation indicator system of coal mine comprehensive level combining objective and subjective evaluation indicators is established. Secondly, according to the characteristics of the indicator system, the specific process of FCE of coal mine comprehensive level is given. Then, taking SQL Server as the database management system and C#.NET as the development language, a set of B/S structure online evaluation system of coal mine comprehensive level based on FCE is designed and developed. Finally, the proposed method is applied to Coal group PM for test. The application shows that the method proposed can provide an efficient and convenient online evaluation platform to evaluate the comprehensive level of coal mines for the Coal group, and the horizontal and longitudinal comparison of the evaluation results can urge the coal mines to maintain their advantages and avoid their disadvantages, which is of some significance for improving the overall competitiveness of the Coal group.

[Correlation analysis of newly diagnosed coal worker's pneumoconiosis and GDP in Hubei Province from 2006 to 2015].

Objective: To analysis the distribution characteristics of coal worker's pneumoconiosis in Hubei Province during 2006-2010 (the 11th Five-Year Plan period) and 2011-2015 (the 12th Five-Year Plan period) , and its correlation with the gross domestic product (GDP) of Hubei Province from 1986 to 2015. Methods: In September 2019, the data of newly diagnosed coal worker's pneumoconiosis reported in Occupational Disease and Occupational Health Information Monitoring System from 2006 to 2015 and the GDP data from 1986 to 2015 in Hubei Province were collected. The distribution characteristics of time, region, enterprise size, industry and economic type of coal-worker's pneumoconiosis and its correlation with GDP were analyzed. Results: In 2006-2015, 3807 new cases of coal worker's pneumoconiosis were reported in Hubei Province. The time distribution generally ascended as a wave trend. The number of new cases reached its peak in 2013 (722 cases) . GDP growth continued between 1986-1995, 1996-2005 and 2006-2015, especially in 2006-2015. New cases of coal worker's pneumoconiosis were mainly distributed in Huangshi city, Yichang city and Enshi prefecture, accounting for 82.40% (3137/3807) of the total cases. The proportion of new cases in Huangshi city was higher than that in Yichang city and Enshi prefecture (χ(2)=272.66, 243.19, P<0.05) . New cases were mainly distributed in coal mining industry (3103 cases, 81.51%) , small-sized and medium (1675 cases, 44.00%) , and private enterprises (1621 cases, 42.58%) . The rank correlation (r(s)) of coal worker's pneumoconiosis in 2006-2015 with GDP in1986-1995, 1996-2005 and 2006-2015 were 0.157, 0.144, 0.200, respectively, and there were no significant differences (P>0.05) . Conclusion: The coalworker's pneumoconiosis in Hubei Province are mostly distributed in small and medium-sized private enterprises, and the regional distribution is concentrated in Huangshi city, Yichang city and Enshi prefecture. The concentration of cases is closely related to the number and energy production of local coal mines. There is no correlation between the growth of GDP and the distribution of cases.

Effects of commodity on the risk of emphysema in South African miners.

PURPOSE: To examine associations between mine commodity such as coal, platinum, or diamonds and emphysema among South African miners at autopsy. METHODS: We examined the association between mine commodity and emphysema using the Pathology Automation (PATHAUT) database, 1975-2014. Exposure was characterized as longest tenure in each commodity. We constructed separate multivariable logistic regression models for black and white miners. Smoking was assessed in a sub-analysis of white miners. RESULTS: Among black miners, coal mining was significantly associated with increased odds of emphysema [OR = 2.39 (95% CI 1.86, 3.07)] when compared to gold mining. Asbestos was also associated with significantly increased odds of emphysema among black miners [OR = 1.47 (95% CI 1.01, 2.12)]. No associations between commodity and emphysema were observed among white miners. Cumulative years of exposure and age at death were significant predictors for emphysema for both black and white miners. Smoking was a significant predictor of emphysema in the sub-analysis of white miners with smoking information, but no effect of commodity was observed. CONCLUSIONS: We observed a significant association between coal mining and emphysema among black miners. Adverse health effects of coal mining are evidenced by more than twofold increase in emphysema among black coal miners compared to gold miners. This suggests that South African Coal miners are exposed to high dust concentrations or more damaging components compared to other commodities, resulting in elevated risk of emphysema.

Waste sludge derived adsorbents for arsenate removal from water.

Aqueous arsenate [As(V)] was removed using an aluminum-based adsorbent (ABA) and coal mine drainage sludge coated polyurethane (CMDS-PU) prepared using alum and coal mine sludge, respectively. Their As(V) removal efficiencies were compared with each other and granular ferric hydroxide (GFH). The mineralogy and surface chemistry of materials were determined using wavelength dispersive X-ray fluorescence (WD XRF) and Fourier transform infrared spectroscopy (FTIR), respectively. The angle-resolved X-ray photoelectron spectroscopy (AR-XPS) studies confirmed As(V) retention on the adsorbent surfaces. The adsorption kinetics data were fitted to pseudo second-order rate equation. The faster As(V) uptake kinetics of GFH and ABA (GFH > ABA > CMDS-PU) were attributed to their large pore volume and mesoporous nature. Langmuir adsorption capacities of 22, 31 and 10 mg/g, were achieved for GFH, ABA and CMDS-PU, respectively. As(V) adsorption on GFH, ABA and CMDS-PU was endothermic. GFH and ABA were efficient over a wide pH range (3-10). In column studies, GFH, ABA, and CMDS-PU successfully treated 23625, 842, and 158 bed volumes (BVs) and 2094, 6400, and 17 BVs of As(V)-contaminated water with 9.5 and 27 EBCT, respectively (at pH = 6.0, Asi = 600 µg/L). The GFH and ABA have a potential to be used at large-scale aqueous phase As(V) remediation.

Embryonic exposure to soil samples from a gangue stacking area induces thyroid hormone disruption in zebrafish.

The total accumulative stockpiles of gangue from long-term coal mining exceed 1 billion tons and occupy 182 square kilometers, and 50 million tons of additional gangue are generated per year in Shanxi, a major energy province in China. The objective of this study was to examine whether exposure to village soils affected by gangue stacking would disrupt thyroid hormone system homeostasis and eventually affect endocrine system and development, using zebrafish (Danio rerio) as a model organism. The zebrafish embryos were exposed to village soil leachates at 0, 1:9, 1:3 and 1:1 from 1 to 120 h postfertilization (hpf), and the sample caused a dose-dependent increase in the mortality and malformation rate, and decrease in the heart rate, hatching rate and body length of zebrafish larvae. Importantly, the soil leachate alleviated the whole-body triiodothyronine (T3) and thyroxine (T4) levels at higher concentrations, and altered the expression of the hypothalamic-pituitary-thyroid (HPT) axis-regulating genes crh, trh, tshß, nis, tg, nkx2.1, pax8, hhex, ttr, dio1, dio2, ugt1ab, trα, and trß and the PAH exposure-related genes ahr2 and cyp1a. These findings highlight the potential risk of thyroid hormone disruption and developmental toxicity from soil samples around coal gangue stacking areas.

How does vertical integration promote innovation corporate social responsibility (ICSR) in the coal industry? A multiple-step multiple mediator model.

This paper aims to demonstrate the impact of coal enterprises' vertical integration on the performance of innovation corporate social responsibility (ICSR) and to elaborate its specific transmission path through financing structure and market power. This paper takes the data of A-share listed coal company from 2008 to 2017 as samples, uses input-output table method to measure the degree of vertical integration, and explores the relationship between the four factors through multiple linear regression and Bootstrap method. We found that: (1) the vertical integration of coal enterprises has positive incentives for the promotion of ICSR. (2) Financing structure and market power play a chain intermediary role in this process of incentive. (3) In areas with high marketization process, vertical integration has more significant incentive effect on ICSR. The paper extends the research on the relationship between vertical integration and innovation, which provides a reference for the improvement of China's supply-side reform and corporate social responsibility (CSR) fulfillment policy. It is helpful to promote the sustainable development of the coal industry, stimulate the innovation vitality of enterprises, and improve the fulfillment of CSR.

Using chemical experiments and plant uptake to prove the feasibility and stability of coal gasification fine slag as silicon fertilizer.

Coal gasification fine slag (CGFS) is a kind of industrial waste that is generated from entrained-flow coal gasification with a high content of 0.5 M hydrochloric acid (HCl)-extractable silicon (Si). Si fertilizer has been widely used in agriculture to enhance the mechanical properties and yield of crops. An evaluation was actualized by analyzing HCl-extractable Si fractions and X-Ray diffraction (XRD) of different treatments (acid, alkali, salt, grind, calcination, temperature, and time) for CGFS samples and other Si source materials. The results showed that CGFS had stable HCl-extractable Si concentrations of 60 ± 2 g/kg except in the calcination treatment, which decreased the content of extractable Si by 28.2%. Furthermore, under the same processing conditions, CGFS showed a higher content of extractable Si than other Si source samples. Moreover, a rice growth experiment was carried out for 120 days in a different mass incorporation of CGFS in the greenhouse. The strength index and total Si content of the stem proved that using CGFS at 5 wt.% markedly promoted the growth of rice. The study indicated that an appropriate application of CGFS as a Si resource to an agricultural field could be considered as a viable option for safe disposal of this industrial waste.

Comprehensive evaluation on low-carbon development of coal enterprise groups.

Scientifically evaluating the level of low-carbon development in terms of theoretical and practical significance is extremely important to coal enterprise groups for implementing national energy-related systems. This assessment can assist in building institutional mechanisms that are conducive for the economic development of coal business cycle and energy conservation as well as promoting the healthy development of coal enterprises to realize coal scientific development and resource utilization. First, by adopting systematic analysis method, this study builds low-carbon development evaluation index system for coal enterprise groups. Second, to determine the weight serving as guideline and criteria of the index, analytic hierarchy process (AHP) is applied using integrated linear weighted sum method to evaluate the level of low-carbon development of coal enterprise groups. Evaluation is also performed by coal enterprise groups, and the process comprises field analysis and evaluation. Finally, industrial policies are proposed regarding the development of low-carbon coal conglomerate strategies and measures. This study aims mainly to guide the low-carbon development of coal enterprise groups, solve the problem of coal mining and the destruction of ecological environment, support the conservation of raw materials and various resources, and achieve the sustainable development of the coal industry.

The use of zeolite-based additives for immobilising iron during pressure filtration of coal refuse slurry.

Pressure filtration of coal refuse slurry has the potential to provide a concentrated solids stream that can be stacked, thereby offering multiple environmental benefits. However, potential leachates from the solids stream can impact the environment. In that context, this study performed preliminary investigations of the application of zeolite-based additives to adsorb metals leaching from coal refuse slurry at low pH. Additives were added to the coal refuse slurry, which was filtered using bench- and lab-scale pressure filtration units. Results indicated that the overall filtrate flux and cake moisture characteristics were not significantly affected by the addition of additives up to 20% (by weight of solids). It was shown that adsorption as high as 80% was achieved by using the additives to capture iron. It was concluded that the finer additive with less silicon content was more effective in capturing iron. The results showed that the thickener feed stream leached out less iron than the thickener underflow stream. The adsorption process was not significantly affected by slight variations in initial iron concentration in the solution. The use of lower pH water on the filter cakes treated with the additive showed minimal release of iron and manganese into the aqueous phase.

Polycyclic aromatic hydrocarbons in soil of the backfilled region in the Wuda coal fire area, Inner Mongolia, China.

The Wuda coal fire area in Inner Mongolia, China, has existed for 50 years and been controlled by digging and backfilling for many years. However, few studies have focused on its impact on the local environmental and ecological systems due to emission of organic contaminants from the backfilled region. In the study, topsoil samples were collected at a 0-5 cm depth from the backfilled region of the Wuda coal fire area, which has existed for five years. The samples were analyzed for 16 priority control contaminants, namely polycyclic aromatic hydrocarbons (PAHs), with a standard operation procedure and high-performance liquid chromatograph (HPLC). The results showed that the total mass contentration of 16 PAHs (∑16PAHs) ranged from 279 to 8258 µg kg-1, with an average value of 2853 ±â€¯2948 µg kg-1, which exceeded the stipulated limit for heavily contaminated soil (1000 µg kg-1). Among the 16 PAHs, 2- and 3-ring compounds accounted for more than half of ∑16PAHs. Furthermore, the results show that the main contaminants were the naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), chrysene (Chr), and benzo[b]fluoranthene (BbF) in this area (24.8%, 51.1%, 3.9%, 4.5%, and 5.7% of ∑16PAHs, respectively). The diagnostic ratio of FLA/(FLA + PYR) exceeded 0.4 and IcdP/(IcdP + BghiP) was less than 0.5, indicating gentle smoldering or spontaneous combustion of coal fire, which differs from traditional coal burning. The environmental health risk or specifically the cancer risk (CR), calculated using the surface soil of the backfilled region, was 2.84 × 10-6 for adults and 1.01 × 10-6 for children, thus indicating potential cancer risks. Therefore, PAHs pollution in the surface soil of the backfilled region in the studied coal fire area is an issue that deserves urgent attention.