Advancing respirable coal mine dust source apportionment:a preliminary laboratory exploration of optical microscopy as a novel monitoring tool

Exposure to respirable coal mine dust(RCMD)can cause chronic and debilitating lung diseases.Real-time monitoring capabilities are sought which can enable a better understanding of dust components and sources.In many underground mines,RCMD includes three primary components which can be loosely associated with three major dust sources:coal dust from the coal seam itself,silicates from the surrounding rock strata,and carbonates from the inert‘rock dust’products that are applied to mitigate explosion hazards.A monitor which can reliably partition RCMD between these three components could thus allow source apportionment.And tracking silicates,specifically,could be valuable since the most serious health risks are typically associated with this component-particularly if abundant in crystalline silica.Envisioning a monitoring concept based on field microscopy,and following up on prior research using polarized light,the aim of the current study was to build and test a model to classify respirable-sized particles as either coal,silicates,or carbonates.For model development,composite dust samples were generated in the laboratory by successively depositing dust from high-purity materials onto a sticky transparent substrate,and imaging after each deposition event such that the identity of each particle was known a priori.Model testing followed a similar approach,except that real geologic materials were used as the source for each dust component.Results showed that the model had an overall accuracy of 86.5%,indicating that a field-microscopy based moni-tor could support RCMD source apportionment and silicates tracking in some coal mines.

Study on the Safety and Prevention Technology of Coal Mining under the River in Xingyuan Coal Mine

Coal mining-induced surface subsidence poses significant ecological and infrastructural challenges, necessitating a comprehensive study to ensure safe mining practices, particularly in underwater conditions. This project aims to address the extensive impact of coal mining on the environment, infrastructure, and overall safety, focusing on the Shigong River area above the working face. The study employs qualitative and quantitative analyses, along with on-site engineering measurements, to gather data on crucial parameters such as coal seam characteristics, roof rock lithology, thickness, water resistance, and structural damage degree. The research encompasses a multidisciplinary approach, involving mining, geology, hydrogeology, geophysical exploration, rock mechanics, mine surveying, and computational mathematics. The importance of effective safety measures and prevention techniques is emphasized, laying the foundation for research focused on the Xingyun coal mine. The brief concludes by highlighting the potential economic and social benefits of this project and its contribution to valuable experience for future subsea coal mining.

Fire monitoring in coal mines using wireless underground sensor network and interval type-2 fuzzy logic controller

From the view of underground coal mining safety system, it is extremely important to continuous monitoring of coal mines for the prompt detection of fires or related problems inspite of its uncertainty and imprecise characteristics. Therefore, evaluation and inferring the data perfectly to prevent fire related accidental risk in underground coal mining (UMC) system are very necessary. In the present article, we have proposed a novel type-2 fuzzy logic system (T2FLS) for the prediction of fire intensity and its risk assessment for risk reduction in an underground coal mine. Recently, for the observation of underground coal mines, wireless underground sensor network (WUSN) are being concerned frequently. To implement this technique IT2FLS, main functional components are sensor nodes which are installed in coal mines to accumulate different imprecise environmental data like, temperature, relative humidity, different gas concentrations etc. and these are sent to a base station which is connected to the ground observation system through network. In the present context, a WUSN based fire monitoring system is developed using fuzzy logic approach to enhance the consistency in decision making system to improve the risk chances of fire during coal mining. We have taken Mamdani IT2FLS as fuzzy model on coal mine monitoring data to consider real-time decision making (DM). It is predicted from the simulated results that the recommended system is highly acceptable and amenable in the case of fire hazard safety with compared to the wired and off-line monitoring system for UMC. Legitimacy of the suggested model is prepared using statistical analysis and multiple linear regression analysis.

Mechanics of rib deformation—Observations and monitoring in Australian coal mines

The risk of fatalities from rib failure is still prevalent in the coal mining industry. This risk has prompted further research to be conducted on rib deformation in order to understand the mechanisms of rib failure,with the long-term objective being to improve rib support design. This paper presents the results of ACARP research project C25057, which investigated the mechanics and drivers of rib failure. The results of rib deformation monitoring at three different mines in Australia provide rib deformation characteristics for overburden depths ranging from 160 to 530 m. Monitoring includes deformation during development drivage conditions and during the longwall retreat abutment stress environment. The rib deformation monitoring covered three different seams: the Goonyella Middle Seam, Ulan Seam, and Bulli Seam in the Bowen Basin, Western Coalfield, and Southern Coalfield, respectively. The observed mechanisms driving the rib deformation ranged from bedding shear failure along weak claystone bands to vertical shear fractures to kinematic failures driven by shear failure dilation. The variation in mechanisms of rib failure, together with the seemingly consistent method of rib support design, prompts the question: what exactly is the role of rib support?

Analysis of the Risk of Water Breakout in the Bottom Plate of High-Intensity Mining of Extra-Thick Coal Seams

In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site monitoring means combining borehole peeping and microseismic monitoring, combined with the theoretical analysis to analyze the danger of water breakout in the bottom plate. The results show that: 1) the theoretically calculated maximum damage depth of the bottom plate is 27.5 m, and its layer is located above the Austrian ash aquifer, which has the danger of water breakout;2) the drill hole peeping at the bottom plate of the working face shows that the depth of the bottom plate fissure development reaches 26 m, and the integrity of the water barrier layer has been damaged, so there is the risk of water breakout;3) for the microseismic monitoring of the anomalous area, the bottom plate of the return air downstream channel occurs in the field with a one-week lag, which shows that microseismic monitoring events may reflect the water breakout of the underground. This shows that the microseismic monitoring events can reflect the changes of the underground flow field, which can provide a reference basis for the early warning of water breakout. The research results can provide reference for the prediction of sudden water hazard.

EFT/B interference transmission model and method of anti-interference in a coal mine monitoring substation

Coal mining monitoring system has been enforcing tests for the immunity of Electromagnetic Compatibility(EMC) since 2006.However,not all monitoring substations can pass the Electrical Fast Transient/Burst(EFT/B) immunity test and the explosion-proof test simultaneously.In order to enhance EMC,the EFT/B interfere transmission model was presented at the substation power port,after the EFT/B test method was used to analyze the monitoring substation power ports.Hence,a low-pass filter was designed by using the simulation software PIPICE and an anti-jamming method was proposed by way of a parallel connection of the discharge interfere circuit and the low-pass filter.The improved complex EMI filter was made up of an interference discharge device and a filter.The dynamic equivalent circuit was proposed for the EFT/B immunity test.As a result,the monitoring substation has passed the EFT/B immunity and explosion-proof tests with the complex filter.It is concluded that the complex EMI filter has significantly enhanced the immunity of the coal mining monitoring system.

A coal rib monitoring study in a room-and-pillar retreat mine

The National Institute for Occupational Safety and Health(NIOSH)conducted a comprehensive monitoring program in a room-and-pillar mine located in Southern Virginia.The deformation and the stress change in an instrumented pillar were monitored during the progress of pillar retreat mining at two sites of different geological conditions and depths of cover.The main objectives of the monitoring program were to better understand the stress transfer and load shedding on coal pillars and to quantify the rib deformation due to pillar retreat mining;and to examine the effect of rib geology and overburden depth on coal rib performance.The instrumentation at both sites included pull-out tests to measure the anchorage capacity of rib bolts,load cells mounted on rib bolts to monitor the induced loads in the bolts,borehole pressure cells(BPCs)installed at various depths in the study pillar to measure the change in vertical pressure within the pillar,and roof and rib extensometers installed to quantify the vertical displacement of the roof and the horizontal displacement of the rib that would occur during the retreat mining process.The outcome from the monitoring program provides insight into coal pillar rib support optimization at various depths and geological conditions.Also,this study contributes to the NIOSH rib support database in U.S coal mines and provides essential data for rib support design.

In-situ measurement and distribution of flue gas mercury for a utility PC boiler system

The in-situ instrumentation technique for measuring mercury and itsspeciation downstream a utility 100 MW pulverized coal (PC) fired boiler system was developed andconducted by the use of the Ontario hydro method (OHM) consistent with American standard test methodtogether with the semi-continuous emissions monitoring (SCEM) system as well as a mobile laboratoryfor mercury monitoring. The mercury and its speciation concentrations including participate mercuryat three locations of before air preheater, before electrostatic precipitator (ESP) and after ESPwere measured using the OHM and SCEM methods under normal operation conditions of the boiler systemas a result of firing a bituminous coal. The vapor-phase total mercury Hg(VT) concentration declinedwith the decrease of flue gas temperature because of mercury species transformation from oxidizedmercury to particulate mercury as the flue gas moved downstream from the air preheater to the ESPand after the ESP. A good agreement for Hg°, Hg^(2+) and Hg( VT) was obtained between the twomethods in the ash-free area. But in the dense particle-laden flue gas area, there appeared to be abig bias for mercury speciation owing to dust cake formed in the filter of OHM sampling probe. Theparticulateaffinity to the flue gas mercury and the impacts of sampling condition to accuracy ofmeasure were discussed.

基于Landsat遥感影像的平庄西露天矿植被恢复效果与归因分析

监测与评估生态脆弱区煤矿排土场植被恢复效果,厘清植被变化的驱动因子,能为排土场植被恢复的可持续发展提供技术和数据支撑。现有的利用长时序遥感数据进行矿区植被变化及其驱动机制的相关研究,缺少对矿区尺度下排土场全生命周期植被恢复的精细刻画,缺乏专题指标以定量描述排土场植被恢复力。针对上述问题,以平庄西露天矿的3个外排土场为研究对象,基于Landsat遥感影像生成了研究区逐年的最大INDV数据,采用时序趋势分析法对排土场植被进行全周期精细时空监测,并利用植被恢复力评价区域尺度植被恢复效果。最后,使用多元回归残差法定量分析气候变化和人类活动两类主要驱动因子对排土场植被变化的影响。实验结果表明:①2008—2023年间,3个排土场的植被指数都呈上升趋势,不同植被覆盖等级的面积比例逐步上升,绝大部分区域已经恢复至露天开采前的水平;②排土场植被恢复力呈现“先增后降再趋于稳定”的特点,山后排土场恢复力最强,其次为三家排土场,太平地排土场恢复力相对较弱;③在植被改善区,主要呈现人类活动主导影响、人类活动和气候变化共同影响2类驱动模式;在植被退化区,还存在气候变化主导影响模式,尤其在三家排土场,人类活动和气候变化共同作用影响较大。

Effects of seasonal air temperature variation on airflow and surrounding rock temperature of mines

In underground mines, high air temperatures in the summer months lead to an increase in inlet airflow temperatures. This leads to seasonal thermal pollution in the mines. This paper examines the dynamics and effects of seasonal variation in surface air temperatures and surrounding rock temperatures in deep coal mines. It also examines temperature variations in the main ventilation circuit, working face, and surrounding rock. The study results revealed that airflow temperatures were significantly affected by seasonal air temperature variations. The greater the distance was between the inlet and the wellhead of the ventilation shaft, the less the effect was on temperature. Moreover, slight temperature variations (1.0-3.0 ℃) were observed between various points on the return route during the summer months. Airflow temperatures along the airflow inlet to the return route of the working face first decreased, but then increased. The temperature field of the surrounding rock increased gradually with increased distance between the mine roadway and inlet, with recorded rock temperatures as high as 40.53 ℃. The radius of the heat-adjusting layer was between 28 and 33 m.

基于D-InSAR技术的杨伙盘矿区地表形变监测与分析

【目的】煤炭资源的开采引发一系列的生态环境问题,地面塌陷问题尤为严重,而地表形变监测是修复生态环境问题的首要工作。【方法】InSAR技术作为一种面监测技术,已成功应用到煤矿地面塌陷监测中,本研究利用雷达差分干涉测量(D-InSAR)技术,计算2020年8月至2022年10月间共31景Sentinel-1A数据。【结果】在监测期内,开采工作面的地表共形成3个形变中心,分别位于301和303盘区的工作面,地表在煤矿开采后进入快速形变期,之后开始缓慢形变,直至趋于稳定状态。【结论】D-InSAR技术对于此类地面塌陷问题,相较于点监测技术,具有先天的优势,能够快速、准确地获取整个工作面的形变情况,对煤矿生态环境问题的改善起到了指导作用。

Ground control monitoring of retreat room–and–pillar mine in Central Appalachia

In order to study pillar and overburden response to retreat mining, a ground control program was conducted at a Central Appalachian Mine. The program consisted of several monitoring methods including a seismic monitoring system, borehole pressure cells in the pillars, and time-lapse photogrammetry of the pillar ribs. Two parallel geophone arrays were installed, one on each side of the panel with the sensors mounted 3 m into the roof. A total of fourteen geophones recorded more than 5000 events during the panel retreat. A MIDAS datalogger was used to record pressure from borehole pressure cells(BPCs)located in two adjacent pillars that were not mined during retreat. A series of photographs were taken of the pillars that had the BPCs as the face approached so that deformation of the entire rib could be monitored using photogrammetry. Results showed that pillar stability and cave development were as expected. The BPCs showed an increase in loading when the face was 115 m inby and a clear onset of the forward abutment at 30 m. The photogrammetry results displayed pillar deformation corresponding to the increased loading. The microseismic monitoring results showed the overburden caving inby the face, again as expected. The significance of these results lies in two points,(1) we can quantify the safe manner in which this mine is conducting retreating operations, and(2) we can use volumetric technologies(photogrammetry and microseismic) to monitor entire volumes of the mine in addition to the traditional point-location geotechnical measurements(BPCs).

Research on inversion high mining pressure distribution and technology of preventing dynamic disasters by MS monitoring in longwall face

Under two rock strata combination conditions, over 10,000 microseismic events were received with microseismic location monitoring technology which possessed by the author＇s studying team, used in fully mechanized coal face of Huafeng Mine of Xinwen Coal Mining Group Co., Shandong Province. On the basis of the achievement of the location results, the conclusions were drawn as follows： On the basis of the achievement of 3D strata fracturing situation and the section plane of microseimic events in different areas, the relationship between spatial structure of overlying strata and mining pressure field was found, and we might describe distribution range of dynamic pressure of advance pressure and lateral stress around long face, and range of structure ad-tivation. Quantitative guidance to prevent dynamic disasters was provided. The practice in coal mine got a effective results. According to the FLAG3D soft numerical simulation of diameter drilling hole （the diameter is 300 mm） to relieve pressure in specified geological condition in Huafeng Mine, the right distance of two dirlls is 2.5 m and the right depth is 12 m. The research pro-vided basic guiding and practical experiences for the underground microseismic monitoring and disaster prevention in side slopes or tunnels engineering.

Twenty years of coal mining-induced subsidence in the Upper Silesia in Poland identified using InSAR

The paper presents the results of terrain subsidence monitoring in Poland's Upper Silesian Coal Basin(USCB)mining area using Differential Interferometry Synthetic Aperture Radar(DInSAR)and Persistent Scatterer Interferometry(PSI).The study area accounts for almost three million inhabitants where mining which started in the 19th century,has produced severe damage to buildings and urban infrastructures in past years.The analysis aimed to combine eight different datasets,processed in two techniques,coming from various sensors and covering different periods.As a result,a map of areas that have been exposed to subsidence within 3045 square kilometers was obtained.The map covers a period of twenty years of intensive mining activities,i.e.1992-2012.A total of 81 interferograms were used in the study.The interferograms allowed not only to determine subsidence troughs(basins)formed from 1992 to 2012 but also to observe subsidence development over time.The work also included five sets of PSI processing,covering different temporal and spatial ranges,which were used to determine zones of residual subsidence.Based on InSAR datasets,an area of 521 square kilometers under the influence of mining activities were determined.Within the subsiding zones,an area of 312.5 square kilometers of the rapid increase in subsidence was identified on the interferograms.The study of combined different InSAR datasets provided large-area and long-term information on the impact of mining activities in the Upper Silesia Coal Basin.

基于D-InSAR技术的矿区地表沉陷监测研究

矿山开采可能诱发各种地质灾害,威胁矿区的社会稳定和居民的生命财产安全,快速准确监测矿区沉陷可有效预防地质灾害。本文以山西省大同煤矿为研究对象,获取2022年10月至2023年3月共13景Sentinel-1影像,基于合成孔径雷达差分干涉测量技术(Differential Interferometric Synthetic Aperture Radar,D-In SAR)进行地表沉陷监测研究,获取大同煤矿地表累计沉陷量,使用已有研究成果对比验证了本实验结果的可靠性。结果表明,大同煤矿沉陷分布较广,主要分布在大同市南郊区西部以及南郊区、怀仁市、左云县和山阴县四县市交界处,监测期间最大、平均沉陷量分别为381.43 mm、13.88 mm,总沉陷面积约为207.91 km2,根据7个重点沉陷区的时空变化特征及演化规律发现沉陷呈现持续扩张趋势,推断地表沉陷仍会持续较长时间。研究证明了In SAR技术在矿山开采沉陷监测的可靠性,为矿产资源管理工作提供新的技术方法,研究结果可为矿山开采沉陷治理和地质灾害防控提供参考依据。

D-InSAR技术与SBAS-InSAR技术在矿区地面沉降监测中的应用研究

为了对D-InSAR和SBAS-InSAR两种技术在矿区地面沉降监测中的应用能力进行对比分析,以山东省济宁市某采矿工作面为主要研究区,选取2022年11月2日—2023年8月29日期间26景Sentinel-1A数据,分别利用D-InSAR和SBAS-InSAR两种技术获取了该工作面的地面沉降信息,首先从沉降区域的时空演变特征和沉降面积分布等方面对两种技术进行了对比分析,进一步通过同期实测水准数据对两种技术得到的结果进行了精度验证。研究结果表明,D-InSAR和SBAS-InSAR两种技术监测到的研究区内最大累积沉降量分别为69 mm和59 mm,识别出沉降量大于10 mm的区域面积分别为0.60 km^(2)和0.87 km^(2),其中,沉降量大于30 mm的区域面积分别为0.10 km^(2)和0.17 km^(2)。与水准监测数据对比可知,两种InSAR技术得到的监测结果与真实沉降情况相吻合,在部分沉降漏斗中心区域,地面沉降量超过InSAR技术可监测形变梯度,两种技术的监测精度都大幅降低。相对于SBAS-InSAR技术,D-InSAR技术获取的累积沉降量值更大,但其抵抗误差干扰的能力较弱,而SBAS-InSAR技术能够更好地消除大气相位效应等误差的影响,得到的地面沉降结果在空间分布上更连续平滑。本文研究对利用InSAR技术监测矿区地面沉降具有一定借鉴意义。

基于InSAR监测数据的采煤沉陷特征及稳定性分析——以江苏省沛县矿地融合示范区为例

为查明江苏省沛县采煤沉陷区时空发育特征、发展趋势及其危险程度,更好地指导地质灾害防治与生态环境修复工作,在煤矿开采资料分析和野外调查成果的基础上,开展基于多期Sentinel-1卫星的合成孔径雷达干涉测量数据技术的地表沉降监测。通过采煤沉陷区2018—2022年InSAR监测数据进行地表变形分析得知:2018—2022年,采煤沉陷区地表已沉降0.139~0.558 m,2022年6—12月采煤沉陷区地表沉降速率为0~2.159 mm/d;已稳沉沉陷区(老采空区)沉降量已接近最大值,沉降速率逐渐减小并趋于0,未稳沉沉陷区(新采空区)沉降量和沉降速率从0开始并逐渐增大;2022年底尚存在未稳沉沉陷区面积约18.45 km 2,主要分布在张双楼煤矿等煤矿近5 a开采区域。采煤沉陷区InSAR监测数据可以较好地反映这一时期的变形特征,研究可为沛县采煤沉陷区综合治理工作提供科学依据,亦可为其他类似区域采煤沉陷区特征分析和综合治理工作提供参照。

New development of hydraulic fracturing technique for in-situ stress measurement at great depth of mines

In-situ stress measurement using the hydraulic fracturing technique was made at Wanfu Coal Mine in Shandong Province, China. To solve problems caused by great measuring depth and extra thick overburden soil layers in the mine, a series of improved techniques were developed for the traditional hydraulic fracturing technique and equipment to increase their pressure-enduring ability and to ensure safe and flexible removal of the sealing packers with other experimental apparatus. Successful in-situ stress measurement at 37 points within 7 boreholes, which were mostly over 1000 m deep, was completed. Through the measurement, detailed information of in-situ stress state has been provided for mining design of the mine. The improved hydraulic fracturing technique and equipment also provide reliable tools for in-situ stress measurement at great depth of other mines.

A model of unsafe behavior in coal mines based on game theory

Behavior choice, coal mine monitoring, and control intensity are combined in a general mathematical model established from the perspective of a behavioral game. A case study is provided with effective conditions of monitoring provided. This paper defines the expected value difference of control return and behavior cost difference and discusses the measurement and optimization of variable indexes, including the monitoring intensity and costs of control. The results imply that the control of unsafe behavior can be more effective when monitoring and control of coal mines are both improved. Monitoring will be useful when the rewards for displaying safe behavior, and the monitoring of unsafe behavior, are improved to a high level.

基于InSAR的煤矿地表形变监测研究

为进一步探究煤矿地表形变的更多细节内容,以双鸭山矿区煤田地煤矿开采造成的地表形变问题为研究案例,应用合成孔径雷达干涉测量(InSAR)技术展开研究,基于InSAR的煤矿地表形变监测原始图像,通过对原始图像进行解译和细节处理得到研究区域沉降量分布、沉降量与开采距离之间的关系,以及沉降量与时间的关系等,结合现场实测方法对本次基于InSAR的煤矿地表形变监测的准确性进行对比检验,检验结果显示,针对剖线上的58个节点的数据相关性分析而言,当显著水平取0.05时,相关系数最小值为0.256;当显著水平取0.01时,相关系数最小值为0.330。通过查表对比后可知,剖线水准测量值与InSAR测量值具有较好的相关性。证明水准测量值和InSAR测量值也无显著差异。若以水准测量结果代表地面沉降的真实情况,则本次InSAR监测值可反映出研究区内整体沉降情况,证明本次基于InSAR的煤矿地表形变监测方法较具准确性,具有一定的应用价值。