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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 …

Municipality Of Bayamón V. Exxon Mobil Corp. (2025): Bringing Racketeering Charges For Climate Justice, Ilinca C. Johnson

Pace Environmental Law Review

Environmental justice communities should have their climate change damages heard in the courtroom. One means to increase environmental justice claims is through claims under the federal Racketeer Influence and Corrupt Organizations (RICO) Act. Using Municipality of Bayamón v. Exxon Mobil Corp. (2025) as a model, this Article suggests a novel RICO case strategy to pursue climate damages for marginalized communities. Fundamentally, environmental justice RICO claims involve careful case design based on the climate-related damages a marginalized community has faced because of the long-term deception by fossil fuel actors upon those communities. Pursuing such claims forwards the intersectional issues faced by …

High-Throughput Robotic Ethanol Inhibition Assays For Engineered Thermophilic Biofuel Strains, Kevin He, Daniel Olson, Marybeth Maloney, Anthony Lanahan

Wetterhahn Science Symposium Posters

Ethanol stress assays are commonly used to evaluate microbial tolerance, metabolic adaptation, and fermentation performance. However, manual liquid handling introduces variability across replicate wells and small-volume pipetting steps, limiting reproducibility and throughput. This study developed an automated OT-2 robotic workflow to generate replicated ethanol concentration gradients for high-throughput inhibition assays in engineered thermophilic biofuel strains. Kinetic plate-reader measurements were used to quantify ethanol-dependent growth responses under anaerobic fermentation conditions. The reasearch question is: How do engineered thermophilic biofuel strains differ in ethanol-dependent growth inhibition under anaerobic fermentation conditions, and can automated robotic assays improve the reproducibility of these measurements? Can …

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 …

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 …

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 …

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 …

Key Techniques For Volume Fracturing Of Deep Coalbed Methane Reservoirs And Their Applications: A Case Study Of The Daning-Jixian Block, Li Shuguang, Xiong Xianyue, Zhen Huaibin, Bai Kunsen, Ji Yuan, Yuan Pu, Li Zhongbai, Zhu Weiping

Coal Geology & Exploration

Background Deep coalbed methane (CBM) reservoirs generally exhibit ultra-low porosity and permeability, high stress, predominance of nanopores, and complex fracture propagation. These characteristics complicate reservoir stimulation, thereby restricting the enhancement in single-well productivity and commercial exploitation. Since 2019, technologies for deep CBM recovery have evolved from volumetric acid fracturing, which highlights the enhancement of matrix permeability, into large-scale volume fracturing focusing on the elevation of both the fracture network scale and proppant efficiency. In 2023, ultra-large-scale volume fracturing aimed at maximizing estimated ultimate recovery (EUR) was further developed. However, the implementation of this novel technique poses challenges such as a …

Damage Evolution Of Coal Reservoirs Under Cyclic Disturbances And Optimization Suggestions For Deep Reservoir Stimulation, Chen Shida, Pu Yifan, Zhao Longmei, Li Xiang, Huang Li, Tang Dazhen, Zhang Yafei, Li Song, Tao Shu

Coal Geology & Exploration

Objectives and Methods During volume fracturing or multi-round hydraulic fracturing of deep coal reservoirs, pressure fluctuations induced by the propagation of fracture tips and fluid accumulation within fractures cause cyclic perturbations to surrounding rocks. To clarify both the mechanical responses of coals and the mechanisms behind fracture evolution within coal reservoirs under such cyclic perturbations, this study conducted triaxial cyclic loading-unloading tests on high-rank coals under varying confining pressures, stress amplitudes, and loading modes. In combination with field engineering data, this study proposed strategies for optimizing deep coal reservoir stimulation. Results and Conclusions The stress-strain curves of coals under cyclic …

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 …

Development Path And Prospects Of Technologies For Detecting Hidden Hazards In Coalfield Fire Zones, Deng Jun, Wang Jinrui, Ren Shuaijing, Song Zeyang, Wang Caiping, Li Yaqing, Lu Junhui, Qu Gaoyang

Coal Geology & Exploration

Background Hidden hazards in coalfield fire zones are characterized by limited detectability, rapid evolution, and multi-hazard coupling, posing major challenges to the safe coal mining and related ecological restoration. Methods This study aims to achieve the fine-scale identification and risk control of hidden hazards in coalfield fire zones. Based on a systematic review of the genetic mechanisms and spatial distribution patterns of coalfield fire zones, this study summarizes the characteristics of three primary fire zone types: outcrop/surface fire zones, shallowly buried fire zones, and deeply buried underground burnt-out areas and fire zones within old coal pits. Multi-dimensional hazards caused by …

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

No abstract provided.

Instruments For Simulation Experiments On Coal-Rock Dynamic Disasters In China: Current Status And Key Challenges, Yuan Liang, Tang Haopeng, Ma Yankun, Wu Hua, Zhang Yachao, Jiao Biao, Wang Hao

Coal Geology & Exploration

Background Coal-rock dynamic disasters represent engineering disasters caused by the instability of the multi-phase and multi-field coupling of coal strata under mining disturbances, severely restricting the safe exploitation of deep coal resources. Elucidating the disaster-inducing mechanisms lays the foundation for exploring effective monitoring and early warning, along with prevention and control technologies, while instruments for simulation experiments provide crucial tools for investigating the mechanisms. Gradually increasing scientific and technological level has contributed to the continuous improvement in China's independently developed instruments for simulation experiments on coal-rock dynamic disasters. However, as engineering activities progressively extend toward deep parts, the multi-phase and …

Development History And Prospects Of Geological Guarantee In The Coal Industry: A Review, Liu Feng, Liu Wenming, Dong Shuning, Wang Hao, Cheng Jianyuan, Liu Zaibin, Fan Tao, Ma Liang, An Lin, Chen Baohui, Yan Zicheng, Jiang Bici

Coal Geology & Exploration

Background In China, the coal industry serves as a ballast stone and stabilizer for rapid socio-economic development and national energy security. Despite huge reserves, China’s coal resources are characterized by uneven spatial distribution, diverse coal seams, complex geological structures, and significantly different mining conditions. During coal mining, unclear geological conditions frequently lead to the abandonment of tunneling roadways, poor mining continuity, frequent equipment relocation, and the abrupt onset of concealed geologic hazards. These challenges ultimately result in difficult advancement of mining face, frequent casualties, and considerable economic losses. Geological guarantee represents a crucial foundation and key technology throughout the shaft …

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 …

Advances In Geological Guarantee Technologies For Safe, Efficient, And Intelligent Coal Mining In China, Sun Siqing, Miao Yaowu, Jia Lilong

Coal Geology & Exploration

Background Coal mining geology provides the foundation for efficient coal mining, as well as hazard prevention and control. Based on the revision to China’s normative documents entitled Regulations on Geological Work in Coal Mines and Detailed Rules for Geological Work in Coal Mines, the exploration of technologies for coal mining geology, and considerable experience in coal mine production practices, this study systematically reviews the advances in geological guarantee technologies for safe, efficient, and intelligent coal mining in China over the past four decades.Advances Six aspects of advances have been primarily achieved in geological guarantee technologies in China: (1) The …

Mechanisms Underlying Coal Instability During Coal And Gas Outbursts Induced By Deep Mining, Zhang Chaolin, Li Yunfu, Li Zhonghui, Wang Enyuan, Yang Shiji, Chen Jiawei, Wang Meng

Coal Geology & Exploration

Objective The gradual depletion of shallow coal resources drives a shift to the mining of deep coal seams. However, the complex deep mining environment significantly increases the potential risks and severity of coal and gas outbursts. Therefore, there exists an urgent need to investigate the mechanisms underlying the mechanical instability of coals under deep mining, aiming to provide guidance for the safe mining of deep coal mines.Methods By integrating physical experiments, numerical simulations, and theoretical analysis, this study investigated coal and gas outbursts under burial depths of 500 m, 1000 m, and 1600 m and established a multi-field coupling …

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 …

Analysis Of Typical Cases And Development Trends Of Coalbed Methane (Coal Mine Gas) Drainage Techniques In Coal Mining Areas, Hao Shijun, Jiang Wenping, Zhang Jing, Du Xinfeng, Mo Haitao, Duan Huijun

Coal Geology & Exploration

Background In the coal mining areas of China, coalbed methane (coal mine gas) occurs under complex conditions, rendering it difficult to achieve its efficient resource exploitation and effective hazard control using a single technique.Advances As indicated by the current state of the research, development, and engineering application of coalbed methane (coal mine gas) drainage techniques in China in recent years, the drainage methods can be classified into three categories according to their spatial arrangements: surface drainage, underground drainage, and surface-underground combined drainage. Furthermore, the surface and underground drainage methods can be subdivided into four types based on their temporal …

Biogeochemical Mechanisms Behind Water Quality Evolution And Valuable Element Reutilization Of Abandoned Mine Drainage: A Review, Wu Pan, Huang Jiangxun, Li Qingguang, Zhang Ruixue, Li Bo

Coal Geology & Exploration

Background Abandoned mine drainage, also known as acidic mine drainage (AMD), represents a major pollution source in mining areas while also serving as an important carrier of strategic critical metals and underground space utilization. In China, water pollution stemming from coal mining is more severe in the south than in the north. This spatial pattern is jointly shaped by climatic conditions, geological settings, and mining history. Advances From the perspective of the environmental geochemical frontier, this study presents a systematic review of AMD formation and evolution mechanisms, as well as technologies for water pollution prevention and control, resource recovery, and …

Pathways And Modes For Prevention And Control Of Acid Mine Drainage-Induced Pollution In China, Liu Guo, Chen Qian, Gan Xinzhu, Tang Jie, Zhu Mingtan, Fan Jiajun, Ren Shuang

Coal Geology & Exploration

Background Mining activities in polymetallic sulfide mines significantly disrupt regional hydrogeochemical equilibrium, leading to the formation of acid mine drainage (AMD). Consequently, severe pollution of aquatic environments occurs, posing a threat to regional water resource security. To lay the foundation for the prevention and control of AMD-induced pollution, it is necessary to investigate the formation and evolution mechanisms of AMD and establish a low-cost, sustainable risk management and control mode. Methods Based on field sampling and literature research, this study made statistics of the hydrochemical characteristics of AMD from different polymetallic sulfide mining areas across China and elucidated the processes …

Advances In Research On The Quality, Influential Factors, And Contamination Prevention And Control Technologies Of Mine Water In Representative Coal Mining Areas Of China, Xu Guangquan, Zhang Haitao, Liang Miao, Chen Xiaoqing, Li Zixuan, Li Xu, He Jianghui

Coal Geology & Exploration

Background Mine water represents a major type of water body produced during coal mining. Investigating its quality, influential factors, and contamination prevention and control technologies is of great significance for environmental protection and the sustainable utilization of water resources in coal mining areas.Methods Based on field surveys and literature review, this study systematically analyzed the quality and formation mechanisms of mine water in representative coal mining areas of China. Furthermore, it explored the advances and primary challenges in current research on technologies for the prevention and control of mine water contamination and proposed major directions for future research. Advances …

Geophysical Responses And Their Statistical Relationships With Lithium And Kaolinite Contents For Lithium-Rich Coals In The Yangquan Mining Area, Chen Tongjun, Xu Haicheng, Li Wan

Coal Geology & Exploration

Objective China, representing the world's largest consumer of lithium resources, suffers from a limited endowment of conventional lithium resources, rendering it inevitable for China to seek to develop and utilize abundant coal-hosted lithium resources. Through a comparative analysis of coal samples from the lithium-rich No. 8 and the ordinary No. 15 coal seams in the Taiyuan Formation, Yangquan mining area, Shanxi Province, this study explored the statistical relationships between the lithium and kaolinite contents and geophysical responses. Accordingly, the feasibility of the indirect detection of coal-hosted lithium resources using geophysical methods was assessed. Methods First, by testing the lithium content …

Underground Tunnel Drilling Technology And Equipment For Coal Mines In China: A 50-Year Retrospective And Prospects, Tian Hongliang, Li Wangnian, Li Quanxin, Yao Ke, Liu Jianlin, Chang Jianghua

Coal Geology & Exploration

Bcakground Underground tunnel drilling in coal mines represents an indispensable key means for the safe and efficient coal mining, precise disaster prevention and control, and geological transparency of coal mines. This study presents a systematic review of the development history of underground tunnel drilling technology and equipment for coal mines in China over the past 50 years, during which the technology and equipment have evolved from technology introduction to independent innovation and from following to keeping pace with and even to overtaking international counterparts.Advances Initially, this study expatiates on both the important position of coal resources in the national …

Key Techniques And Application Of The Zdy15000ldk High-Power Automatic Directional Drilling Rig, Li Quanxin, Zhang Gang, Fang Peng, Xing Wang, Yao Ke, Zhang Rui, Zhang Boyang, Zhao Xuefeng, Shi Yang, Sun Hanyu, Jia Qian

Coal Geology & Exploration

Objective For deep mining of coal mines, conventional directional drilling rigs face challenges including high labor intensity, limited control accuracy, a low intelligence level, and failure to meet the demand for efficient gas drainage. Meanwhile, high-power automatic drilling rigs encounter technical bottlenecks in automation, control accuracy, and process intelligence in this context. To address these issues, this study proposed an integrated and systematic solution—the ZDY15000LDK high-power automatic directional drilling rig. Methods Using a compact structural layout, a drill rod handling system was developed, consisting of a drill rod loading/unloading manipulator with four degrees of freedom and an automatic drill rod …