Mining Engineering Commons^™

Theoretical Research Advances And Applications Of The Dynamic Metamorphism Of Coals, Liu Hewu, Jiang Bo, Song Yu, Du Zhigang, Zhang Kun, Hou Chenliang, Yang Wenjie, Huang Nini

Coal Geology & Exploration

Background The dynamic metamorphism of coals, a significant type of coal metamorphism, represents a fundamental research topic of coal geology. The research achievements have been widely applied in fields such as coal resource evaluation, the prevention and control of coal mine gas, and the exploration and exploitation of coalbed methane (CBM), holding great significance for gaining a deep understanding of the microscopic mechanisms underlying coal deformation and metamorphism, coal and gas outbursts, and CBM occurrence. Method Based on a literature survey and analysis, this study presents a systematic review of the development history of research on the dynamic metamorphism of …

Hydrodynamic Evolution Simulations And Safety Assessment Of The Deep Reinjection And Storage Of High-Salinity Mine Water, Xu Zhimin, Chen Weixiao, Sun Yajun, Zhang Jian, Chen Tianci, Liu Qi, Chen Ge, Hua Jingfan

Coal Geology & Exploration

Objective In some mining areas of North China-type coalfields, large volumes of high-salinity mine water produced during coal mining pose dual challenges: high treatment costs to meet discharge standards and the waste of mine water resources due to inefficient utilization before discharge. In recent years, the deep reinjection and storage technology for high-salinity mine water has provided a new approach to this issue. To achieve this technology, it is essential to understand the flow field evolution during mine water reinjection and address reinjection-induced safety problems. Methods This study investigated coal mine A in Jiangsu Province as an example. Using the …

Intelligent Path Planning For Drilling Arms In Rock Bolting In Coal Mines Based On An Improved Rrt Algorithm, Zhang Xuhui, Xie Yanbin, Lei Mengyu, Song Chengzhi, Dong Zheng, Wang Zeyao, Wang Tenghui, Tian Sihao, Zhang Qinhuan

Coal Geology & Exploration

Objective Against the background of intelligent coal mining, automated underground rock bolting has become a core demand in enhancing the tunneling efficiency and safety of roadways. However, the path planning of drilling arms suffers from a low degree of automation, cumbersome posture adjustment, low operational stability, and insufficient drilling accuracy in complex underground environments. Methods To address these issues, this study developed an intelligent path planning method for drilling arms in rock bolting in coal mines based on an improved rapidly-exploring random tree (RRT) algorithm. First, a goal-biased guidance strategy was adopted to narrow the sampling range, and an update …

Advances In Research On Borehole Geophysical Exploration And Associated Equipment For Advance Detection Of Underground Water Hazards In Coal Mines, Wu Qiang, Wang Xianhui, Yang Donghui, Xiao Wenhao, Cui Zhuangjie, Chen Han, Sheng Zhen, Zeng Yifan

Coal Geology & Exploration

Background Deep coal mining is facing increasingly complex hidden disaster-causing factors, including faults, collapse columns, water accumulation in goaves, confined water in coal seam floors, and hydraulically conductive fracture zones. In this context, conventional modes based on ground exploration, roadway geophysical exploration, and drilling verification suffer from limitations in terms of detection distance, positioning accuracy, dynamic perception, and real-time feedback. In contrast, borehole geophysical exploration extends the detection space into coal-rock masses using underground boreholes, enabling the acquisition of information about continuous physical properties around, between, and ahead of boreholes. Therefore, this technology provides important support for the advance detection …

Novel Connotations Of Green Exploration Oriented To Mine Ecological Restoration, Hu Zhenqi, Zhang Fan, Zhao Yanling, Liang Yusheng

Coal Geology & Exploration

Background Mineral resource exploitation inevitably causes ecological damage, while its green solution is rooted in green exploration. Currently, green exploration refers to activities aimed at avoiding, eliminating, or mitigating ecological pollution and damage caused by exploration operations, as well as those intended for the restoration of the ecosystem damaged in the exploration process. However, besides focusing on the exploration process, green exploration should provide geological guarantees for ecological restoration following resource exploitation. [Methods] In this study, the novel connotations of green exploration are proposed first. In other words, green exploration, which should be oriented to the demand for mine …

Philosophy And Methodology For Predicting Deep Coal Resources: A Case Study Of The Carboniferous-Permian Strata In The Ordos Basin, Cao Daiyong, Wei Yingchun, Ning Shuzheng, Wang Xin, Zhu Wenhao, Li Jingqi, Wang Anmin, Qiao Junwei, Xu Xiaotao, Hou Yuehua

Coal Geology & Exploration

Objective In China, deep coal resources hold considerable potential, exhibiting promising prospects for exploitation and utilization. Therefore, gaining a clear understanding of deep coal resources provides a prerequisite and foundation for both the national strategic planning of coal resources and the scientific development and utilization of deep coal resources. Research Thinking From the perspective of the current situation of coal resources in China, this study determined the occurrence characteristics and categories of deep coal resources. Accordingly, it proposed a philosophy and workflow for predicting the resources, followed by the prediction of deep coal resources in the Carboniferous-Permian strata of the …

Advances In Research On Techniques For Petrographic Analysis And Tests Of Coals And Their Applications In China, Song Xiaozhong, Zhang Qun, Fan Zhangqun, Jiang Wenping

Coal Geology & Exploration

Background Techniques for petrographic analysis and tests of coals are critical to the accurate characterization of coals, oil, and gas, providing pivotal geological bases for coalfield exploration, formation condition investigation of coal deposits, clean and efficient coal utilization, and hydrocarbon resource evaluation. China's coal petrology commenced nearly a century ago, having progressively evolved into a key field serving the national energy strategy from the early-stage component identification and genetic investigation of coals. A standardization system suitable for the petrographic analysis and tests of coals with distinctive Chinese characteristics has been established. This system has found applications in industrial fields including …

Tectonic Genetic Mechanisms Of Burnt Rocks In The Upper And Middle Reaches Of The Yellow River Basin, Sun Qiang, Hu Xin, Wang Shuangming, Ding Xiaoying, Geng Jishi, Wu Jiakun, Wei Shaoni, Luo Donghai

Coal Geology & Exploration

Objective The upper and middle reaches of the Yellow River basin represent significant coal bases of China, while burnt rocks formed by the high temperature of coal fires greatly affect the safe and green coal mining in this region. Therefore, investigating the distribution patterns and geological genetic mechanisms of burnt rocks in this region is of great scientific significance and practical value. Methods This study systematically investigated the distribution range and patterns of burnt rocks in the upper and middle reaches of the Yellow River basin. Using analysis of geological processes, this study explored the geological genetic mechanisms and primary …

Industrial Development Of Coalbed Methane Exploitation In China: A 30-Year Retrospective And Future Prospects, Meng Shangzhi, Li Yong, Qin Yong, Li Guofu, Tang Shuheng, Xu Fengyin, Wang Yanbin, Zhang Shouren, Zhang Cong

Coal Geology & Exploration

Background The founding of China United Coalbed Methane Corp., Ltd. in 1996 signals the entry of the coalbed methane (CBM) exploitation in China into the industrial development stage. A systematic summary of the development history, key technologies, and future trends of China's CBM industry is of great significance for gaining a deeper understanding of CBM exploitation patterns and promoting the high-quality development of the CBM industry. Based on a systematic investigation of relevant domestic and international literature, this study presents a comprehensive analysis of the industrial development process of CBM exploitation in China, including development stages, technological evolution, and future …

Advances And Prospects Of Design Optimization Technologies For Differential Development With Three-Dimensional Well Patterns For Deep Coalbed Methane Reservoirs: A Case Study Of The No. 8 Coal Seam In The Ordos Basin, Yan Xia, Fang Jianlong, Mou Chun, Meng Peilong, Wang Yuan, Yu Xiang, Fei Shixiang, Feng Yanqing, Zhao Longmei, Li Meng, Cui Yuehua, Chi Runlong, Yang Qing, Huang Li, Zheng Xiaopeng, Yin Zesong, Wang Congcong, Ma Limin, Zhang Shuang, Liu Shirui, Zhang Yang, Guo Jiali

Coal Geology & Exploration

Objective Design optimization for gas reservoir development serves as a key approach to the efficient exploitation, enhanced primary recovery, and elevated efficiency with reduced costs of deep coalbed methane (CBM). Methods In this study, the most extensively developed Ordos Basin in China was investigated as an example to explore the significant heterogeneity of the geological conditions of deep coal seams. Based on a fine-scale geological investigation of over 3 000 wells across the basin, this study systematically revealed the heterogeneity of the key parameters of deep coal reservoirs, including reservoir distribution, reservoir-cap rock assemblages, coal seam structure, and gas-bearing properties. …

Analysis Of Coal Seam Water Sources Based On Hydrochemistry And Water Isotopes, Wei Dong, Wang Hao, Wang Chungang, Wang Xiaodong, Liu Wei, Wang Qiangmin, Liu Quanhui, Zhou Zhenfang, Wang Yutong

Coal Geology & Exploration

Background The northern Yuheng mining area exhibits the widespread occurrence of water-bearing coal seams. This unique hydrogeological phenomenon poses a serious challenge to efficient mine roadway construction and safe coal mining in the mining area. The recharge sources of the coal seam water remain poorly understood, representing a primary bottleneck in the prevention and control of coal seam water hazards. Methods This study aims to reveal the recharge sources and evolutionary mechanisms of coal seam water in the northern Yuheng mining area. By integrating methods including hydrochemical analysis, isotope analysis, and inverse hydrogeochemical simulation, this study systematically investigated the hydrogeochemical …

Technologies And Typical Cases For The Prevention And Control Of Water Hazards Associated With Burnt Rocks In The Yushenfu Mining Area, Wang Shidong, Wang Hai, Ji Zhongkui, Zhu Kaipeng, Han Qiang, Xue Xiaoyuan, Chen Pan, Zhao Kaixing

Coal Geology & Exploration

Background Brunt rocks are widely distributed in the Yushenfu mining area, predominantly occurring along rivers and gullies. These rocks are characterized by well-developed pores and fractures and weak to extremely strong water-yielding capacity, posing serious threats to roadway tunneling and mining for coal in the same layer or underlying them. Methods This study aims to effectively prevent and control water hazards associated with burnt rocks and reduce their threat. Through field surveys, statistical analysis, field experiments, and exemplary applications, along with exploration and monitoring and related analyses, this study analyzed the distribution of burnt rocks in the Yushenfu mining area …

Progress And Prospects Of Geothermal Resource Monitoring Technology, Hao Wenjie, Li Shengtao, Wang Huang, Liu Donglin, Wang Wanli, Qin Junsheng, Jin Xianpeng, Shen Jian, Liu Shuai, Yao Yahui, Hao Shuli, Ren Tao, Liu Zhe, Meng Xianwei, Hou Deren, Ren Xiaoqing, Jia Xiaofeng, Wen Dongguang

Coal Geology & Exploration

Background Geothermal resources represent a renewable energy source characterized by abundant reserves, extensive distribution, high stability and reliability, and green and low-carbon attributes. China has led the world in the direct utilization of geothermal energy for many years. Geothermal resource monitoring, which lays the groundwork for geothermal exploration, exploitation, and utilization, provides critical data required to determine dynamic changes in geothermal reservoirs and their surrounding geological environments, ensure long-term sustainable geothermal exploitation and utilization, and achieve the refined management and protection of geothermal resources. Advances In the narrow sense, geothermal resource monitoring technology is primarily applied to individual wells. In …

Multi-Objective Optimization And Performance Investigation Of Cementing Materials With High Thermal Conductivity Based On Response Surface Methodology, Zhao Yongzhe, Li Wenhao, Wang Yijie, Han Yongliang

Coal Geology & Exploration

Objective Geothermal energy has emerged as a strategic clean energy for the low-carbon transformation of the world's energy mix. Correspondingly, its efficient exploitation and utilization are crucial to the early achievement of the goals of peak carbon dioxide emissions and carbon neutrality. For geothermal resource exploitation, the thermal conductivity of cementing structures determines the efficiency of heat transfer from strata to geothermal well casings, establishing it as a key factor influencing the efficiency of geothermal energy extraction. Therefore, the research and development of cementing materials with high thermal conductivity can provide robust support for efficient geothermal resource exploitation.Methods The …

Key Technologies For Artificial Intelligence-Based Inversion Of The Borehole Transient Electromagnetic Method In Coal Mining Areas, Fan Tao, Hao Yue, Zhang Peng, Li Ping, Zhao Zhao, Zhao Rui, Liu Qiang, Yan Junsheng, Song Xianzhe, Liu Borui, Chen Changyuan, Li Bo

Coal Geology & Exploration

Background Using directional boreholes, the borehole transient electromagnetic (TEM) method enables near-field excitation and the simultaneous reception of three components within a borehole. This method can effectively avoid interference from ferromagnetic materials in roadways, thereby significantly enhancing the detection accuracy and range. Therefore, this method is widely applied to the detection of underground concealed water hazards in coal mines. However, there is a conflict between the accuracy and efficiency of current inversion methods for borehole TEM data, and existing technologies are insufficient to simultaneously meet the demands for high efficiency and high precision in the detection of concealed water hazards. …

Development And Prospects Of Underground Intelligent Drilling Rigs For Coal Mines, Yao Ningping, Li Quanxin, Lu Qianhai, Peng Guangyu, Zhang Gang, Zhang Youzhen

Coal Geology & Exploration

Background In coal mines, underground intelligent drilling rigs serve as critical equipment for gas extraction and water hazard prevention and control. With increasing mining depth, extreme operating conditions, including elevated gas concentration and high in situ stress, pose challenges to conventional drilling modes. Progress This study presents a systematic review of the evolutionary history of intelligent drilling rigs in China from the 13th to the 14th Five-Year Plan, dividing it into three stages: semi-automated operation, whole-process automated operation, and initial intelligent drilling. In the semi-automated operation stage, technologies for remote control within a viewing distance and automatic loading and unloading …

Discrete Fracture Network Application To Rock Slope Stability In An Open Pit Mine, Elvis Karikari Mensah, Erzah Ackah, Reginald Hammah, Hani Mitri

Journal of Sustainable Mining

The stability of rock slopes in open pit mines is crucial for the safety and efficiency of the mining operation. Conventional stability analysis methods, such as kinematic and limit equilibrium analyses, primarily focus on identifying structural failure mechanisms and evaluating their factors of safety. Although insightful, these approaches do not accurately estimate failure volumes and block locations due to their limited consideration of joint frequency and persistence, which are key parameters in understanding block geometries. Discrete fracture network (DFN) modelling addresses these limitations by explicitly simulating rock mass discontinuities in 3D, which automatically incorporates joint spacing and persistence.

This paper …

Optimization Of Cyanide Leaching Process Based On Grain Size And Slurry Density In Artisanal Small-Scale Gold Mining In Tatelu Area, North Sulawesi, Indonesia, Dadan Mohamad Nurjaman, Harmin Sulistiyaning Titah, Adji Kawigraha, Ipung Fitri Purwanti, Wahyu Hidayat

Journal of Sustainable Mining

Artisanal and small-scale gold mining (ASGM) in Tatelu Village, North Sulawesi, has shifted from mercury amalgamation to cyanide leaching. However, gold recovery remains inefficient, requiring process optimization. This study uses multiple linear regression analysis to evaluate the influence of grain size and slurry density on gold dissolution. The results indicate that grain size plays a dominant role in leaching efficiency, while slurry density, pH, temperature, dissolved oxygen (DO), and cyanide concentration have statistically insignificant effects (p > 0.05). Laboratory tests show that finer grain sizes enhance dissolution, with the highest recovery rate of 89.08% achieved at 75% passing through 44 …

A Comprehensive Survey Of Artificial Intelligence Applications In Predicting Mining-Induced Subsidence, Deformation, And Landslides: Strengths, Limitations, And Future Trends, Long Quoc Nguyen, Dung Ba Nguyen, Minh Tuyet Dang

Journal of Sustainable Mining

Mining activities often cause mining-induced ground deformation, including subsidence and landslides, and related geo-environmental impacts, posing significant risks to infrastructure and safety. This study conducts a systematic assessment to identify, categorize, and evaluate AI-based methods (machine learning, deep learning, and hybrid models) for predicting and monitoring mining-induced ground deformation. The literature search was performed across major scientific databases, using predefined keywords and selection criteria, resulting in a final dataset of relevant peer-reviewed studies. The reviewed works were classified into three methodological groups: traditional machine learning, deep learning-based approaches, and hybrid methods. The results show that ML still dominates in terms …

Mining And Sustainable Development In Sierra Leone: The Role Of Institutional Quality, Ibrahim Massaquoi

Journal of Sustainable Mining

While mining can drive economic growth, create jobs, and promote infrastructural development, it also poses risks to the environment, human health, and social well-being. Therefore, to achieve sustainable development, responsible mining is crucial. This study empirically examines the role of institutional quality in the mining-sustainable development nexus in Sierra Leone. With the use of the planetary pressures-adjusted human development index (PHDI) as a comprehensive measure of sustainable development, the study is able to integrate economic, social, and environmental dimensions. The autoregressive distributed lag (ARDL) model confirms the existence of both short-run and long-run dynamics. The results of the study show …

Geological Environment’S Dynamic Responses And Damage Reduction-Oriented Geological Guarantee In Coal In-Situ Conversion, Wang Shuangming, Geng Jishi, Sun Qiang, Shi Qingmin, Liu Lang, Wang Shengquan, Yang Yuru, Yuan Shihao, Zhang He, Hu Xin

Coal Geology & Exploration

Objective Coal in-situ conversion (ISC) emerges as an important transformative technology for clean and efficient utilization of coal resources. However, safe and stable coal ISC is currently restricted by two major bottlenecks: an unclear understanding of the mechanisms underlying the geological environment’s dynamic responses and a lack of damage reduction-oriented geological guarantee. Methods To construct a damage reduction-oriented geological guarantee system for safe and green coal ISC, this study, from the perspective of the geological environment’s dynamic responses throughout coal ISC, elucidates the scientific connotations of both the dynamic responses and the geological guarantee in coal ISC. Based on the …

Theory And Key Technologies Of Collaborative Management And Control For Groundwater Protection, Treatment, And Utilization In Coal Mining Areas, Dong Shuning, Wang Hao, Guo Xiaoming, Dong Xingling, Qiao Wei, Wang Xiaodong, Zhang Xiyu, Zhang Wenzhong, Zhu Kaipeng, Hu Yunhao, Zhou Zhenfang, Duan Jianhua, Miao Hechao, Wang Tiantian, Wang Hai, Xue Jiankun

Coal Geology & Exploration

Background and Methods To mitigate the contradiction between abundant coal resources and scarce water resources in China, this study proposes a collaborative management and control solution for groundwater protection, treatment, and utilization in coal mining areas. From a theoretical perspective, this study investigates the propagation chains of both the coal mining disturbance to groundwater and the responses of groundwater systems to engineering interventions. Furthermore, it elucidates the core idea, scientific connotation, and technical architecture of the collaborative management and control and explores key technologies involved. Results and Conclusions A technical system based on accurate prediction and precise monitoring, covering treatment-protection …

A Review Of Full-Lifecycle Management Practices For Blue Mining Centered On Sustainable Development And Resource Efficiency, Hou Zhengmeng, Zhang Shengyou, Chen Qianjun, Sun Wei, Zhang Tian, Cai Nan, Huang Liangchao, Wang Qichen, Shi Tianle, Xu Xiaochuan

Coal Geology & Exploration

Against the backdrop of China’s goals of peak carbon dioxide emissions and carbon neutrality, along with the growing demand for critical minerals, this study presents a systematic review of domestic and international literature and engineering cases. Based on the Blue Mining concept proposed by Langefeld’s team of the Clausthal University of Technology and from the perspective of planning forward, this study organizes key technologies, treatment pathways, and essentials of full-lifecycle management used to transition mines from single-purpose stopes to multifunctional infrastructures. Centered on four guiding principles, i.e., energy, ergonomics, water resources, and circularity, this study reviews the synergetic planning process …

Latest Advances In Research On Co2-Enhanced Coalbed Methane Recovery, Sang Shuxun, Liu Shiqi, Li Dianshang, Zhang Shouren, Xu Tianfu, Han Sijie, Zhou Xiaozhi, Huang Fansheng, Liu Tong, Tian Yuchen, Zhang Helong, Niu Qinghe, Chen Yongchun, Zhang Bing, Wu Jie

Coal Geology & Exploration

Background The CO₂-enhanced coalbed methane recovery (CO₂-ECBM) technology integrates greenhouse gas emission reduction and enhanced CBM recovery, holding great significance for achieving the goals of peak carbon dioxide emissions and carbon neutrality of China and ensuring national energy security. However, due to limitations of insufficient fundamental research and some technical bottlenecks, the engineering application of the CO₂-ECBM technology remains in the engineering test stage. This study reviews the latest advances in research on the mechanisms, evaluation methods, and technical systems of CO₂-ECBM and explores key scientific issues and technical pathways for geological …

Key Issues And Research Prospects Of The Commingled-Production Compatibility Of Deep Superimposed Coalbed Methane Systems, Guo Chen, Wang Shuangming, Qin Yong, Xu Fengyin, Sun Xueyang, Xia Yucheng, Hou Enke, Wang Sujian, Sun Qiang, Wang Shengquan, Tang Shengli, Yang Xiankuo, Gao Junzhe, Li Ruiteng, Shi Kang

Coal Geology & Exploration

Objective In recent years, significant breakthroughs have been achieved in the exploration and exploitation of deep coalbed methane (CBM), which has emerged as a major area for the reserve growth and production addition of CBM in China. Variations in the temperature and pressure conditions of deep formations inevitably cause substantial differences in the commingled-production compatibility of deep and shallow superimposed CBM systems. Therefore, revealing the depth effects of the commingled-production compatibility is critical to enhancing the efficiency of the multi-layer commingled production of deep CBM and even coal-measure gas. Methods Using a systematic literature survey of the exploration and exploitation …

Ecological Restoration Strategies Based On Plant And Soil Characteristics For Dumps Of Surface Coal Mines In Cold Arid Regions, Wang Hao, Li Haichao, Jiang Xinjun, Cao Shumiao, Yang Fan, Wang Qiangmin, Xu Ganggang, Shi Hui

Coal Geology & Exploration

Objective The dumps of surface coal mines in cold arid regions represent ecologically vulnerable areas formed under extreme disturbance. However, a lack of systematic studies on the vegetation and soils in dumps, including their spatial variation patterns and synergistic mechanisms caused by vertical differences of the dumps, leads to insufficient theoretical bases for formulating differential ecological restoration strategies in engineering practice.Methods By integrating field ecological surveys and physicochemical tests in the laboratory, this study investigated the dump with elevations ranging from 2498 m-2632 m of the Heishan coal mine on the northern slope of the Tianshan Mountains, Xinjiang. Based …

Advances In Research On Eco-Geological Environment Monitoring Of Underground Coal Mining Areas Based On Airborne Remote Sensing, Li Jun, Zou Zhaohui, Zhang Chengye, Wang Yi, Cheng Yang, Xu Lianhang, Zhang Jinhe, Liu Chuanrui, Liang Lixia

Coal Geology & Exploration

Background Timely and effective monitoring of the current status of eco-geological environment holds great significance for scientific decision-making regarding both geological environment protection and ecological restoration in underground coal mining areas. Owing to its advantage of large-scale and rapid monitoring, airborne remote sensing technology has emerged as an important approach to the eco-geological environment monitoring of mining areas. Advances This study first clarifies relevant concepts of eco-geological environment monitoring, as well as the monitoring requirements and contents specific to underground coal mining areas. Accordingly, it presents a summary of the advances in research on airborne remote sensing technology for the …

From Follower To Leader: Seismic Coal Exploration Techniques In China Over The Past 70 Years−In Celebration Of The 70th Anniversary Of Ccteg Xi’An Research Institute (Group) Co., Ltd., Cheng Jianyuan, Wang Yunhong, Wang Baoli, Li Gang, Li Yuteng, Qin Si

Coal Geology & Exploration

Background After 70 years of innovation and development, China has successfully transformed from a follower into a leader in both high-resolution surface seismic coal exploration techniques and underground in-seam seismic exploration techniques for coal mines. Furthermore, it has achieved disruptive innovations in intelligent seismic-while-mining (SWM) and seismic-while-tunneling (SWT) techniques. These achievements have established China’s worldwide leading position in the overall development of seismic coal exploration techniques.Advances In terms of high-resolution surface seismic coal exploration techniques, China has undergone four development stages: arduously catching up, striving to follow, keeping pace with continuously, and overtaking international counterparts with advanced techniques during …

Sealing Performance Evaluation Criteria And Profile Optimization Of The Volumetric Cavities Of Positive Displacement Motors For Directional Drilling, Kuang Yuchun, Hu Xin, Zhou Jingpei, Luo Jinwu, Liu Yihui, Han Yiwei

Coal Geology & Exploration

Objective Constrained by complex stratigraphic conditions in underground coal mines, directional drilling faces challenges such as low efficiency when encountering medium-hard and hard formations. Positive displacement motors (PDMs) with a diameter of 89 mm are commonly used for directional drilling. Their efficiency is primarily influenced by the sealing performance of their volumetric cavities, which further significantly affects the drilling efficiency. Methods Based on the structural characteristics of the three-dimensional (3D) volumetric cavities of PDMs and the simulation method of two-way fluid-structure interactions, this study proposed the criteria for quantitatively evaluating the efficiency and volumetric cavity performance of PDMs, followed by …

Table Of Contents, The Editors

Coal Geology & Exploration

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