Coal Mining Operations Research Articles

Are the households in coal mining regions more vulnerable? A study in Talcher Coalfield of India

Undoubtedly, coal is playing an important role in shaping today’s world. But, excessive extraction of coal has created several adverse effects on the local economy as well as on the global economy. In this study, the households’ vulnerability to coal mining operations is assessed by taking two indicators, i.e., the livelihood vulnerability index (LVI) and livelihood effect index (LEI) in active coal mining and non-mining villages of Talcher Coalfields region of Angul district of Odisha, India. The mining village has shown more vulnerability than the non-mining village in both indices. In LVI, natural disaster, climate variation, and environmental quality (NDCVEQ) indicator is the dominant factor that greatly impacted the overall vulnerability level of the households followed by water (W), health (H), and finance (FIN). Out of the five capitals of LEI, natural capital and financial capital have been affected more due to coal mining activities in the mining village, than the non-mining village. This reflects that households in the mining village are more susceptible to various environmental related issues, and hence, they need to adopt adequate measures to cope up with the issues created from mining operations. Additionally, the mining companies are needed to undertake effective steps to curtail the negative externalities and protect the interests of the local inhabitants.

Experimental and Numerical Investigation of the Effect of Integration of a Flooded-Bed Scrubber into a Longwall Shearer on Airflow along a Coal Mine Longwall Face

Dust control is one of the most difficult challenges for underground coal mine operators, especially longwall mine operators. The most widely used dust control technologies at a longwall section are ventilation air and water sprays, whereas a continuous miner section has the added advantage of having a dust scrubber built into the continuous miner. To test the potential benefits of integrating a flooded-bed scrubber into a longwall shearer, the authors designed and built a dust scrubber system for a full-scale mock-up of a longwall shearer. The mock-up was installed in the longwall test gallery at the Pittsburgh Research Laboratory (PRL) for testing. Air quantity surveys were performed at different cross-sections of the test gallery at a fixed face-air quantity, but at different scrubber airflow rates to quantify the distribution of air in the test gallery. Subsequently, a computational fluid dynamics (CFD) model of the PRL test gallery was developed and validated. In this study, the effect of the flooded-bed scrubber on airflow pattern in the test gallery is investigated using the validated CFD model. This model can be used further to predict the dust capture efficiency of the scrubber and to develop new techniques to reduce dust concentration in longwall sections.

Difference Analysis of Disaster Types and Grading Control Technologies for Risk of Caving of Coal Roadway Roof

In view of the problem of a caving roof along different parts of the same roadway in a mine, this study classifies the mechanical characteristics of the local instability of the roof based on differences in the rock mass media and types of damage. We determine the factors influencing the quantitative relationship between the failure height of the roof and the environment to establish an indicator system for classifying the grades of risk of the roof caving. This is used to predict the height at which the roof caves along the roadway in a coal seam through fuzzy variable weighting analysis. We also develop software for the grading system of risks of caving of the roof and draw a grading map to represent this risk for a roadway in coal seam No. III in Zhaogu Coal Mine No. 2 in Jiaozuo City of Henan Province, China. According to the zoning characteristics of the coal mine, a targeted support design test is carried out in the same intake airway of working face 11030 of the mine. The results show that the proposed classification method conforms to safe practices in underground mining. The stability of the roadway during service and the grades determined using the proposed method were consistent. This has important theoretical significance and practical value for designing support for roadways and timely reinforcements in areas with a high-risk grade to guarantee the safe operation of coal mines.

Effects of geo-stress on the dynamic response of multi-physical field parameters during coal and gas outbursts under true triaxial stress

With the increase of the mining depth in coal mining operations, more coal and gas outburst (CGO) disasters are likely occur due to the increase in geo-stress. The limitations of conventional experimental methods prevent the observation of multi-physics parameters and dynamic effects during CGO. In this work, a customized coal mine dynamic disaster test system was used to analyze the evolution of multi-physics parameters such as gas pressure, temperature, and geo-stress during CGO. The influences of geo-stress on the energy sources of CGO were discussed and the response characteristics of the coal-gas flow in the roadway during the CGO were analyzed. Results show that during the CGO process, an increase in the geo-stress will decrease the gas pressure and rate of the pressure drop. The rate of geo-stress change gradually increases with an increase in the initial stress, and the peak impact force of the coal-gas flow increases with increasing geo-stress. The elastic strain energy released during CGO also increases with increasing geo-stress, however, it is less valuable than gas expansion energy. The contribution of geo-stress to the CGO depends on its influence on the gas expansion energy. Coal seam temperature variations are mainly manifested in the stress relief and abutment stress zones, and the flow velocity of CGO coal demonstrates alternating deceleration and acceleration cycles. Additionally, the obtained distribution characteristics of CGO coal exhibit log-normal patterns. These findings can help further understand the CGO mechanism and provide a reference for passive disaster reduction measures after outbursts.

Impact of Coal Mining on the Moisture Movement in a Vadose Zone in Open-Pit Mine Areas

Long-term dewatering of groundwater is a necessary operation for mining safety in open-pit coal mines, as extensive dewatering might cause ecological problems due to dramatic changes in moisture movement in the soil, especially in ecologically fragile areas. In order to evaluate the impact of the coal mining operation on moisture movement in the vadose zone and vegetation, this paper presents a quantitative methodology and takes the Baorixile open-pit coal mine as a study example. A long-term in situ experiment (from 2004 to 2018), laboratory analysis, and numerical modelling were conducted to analyze the mechanisms and relationship among the dropping groundwater level, the vadose-zone moisture, and the ecological responses in the grassland area. The experiment data and modelling results suggest that groundwater level dropping during open-pit mining operation has limited influence on the vadose zone, exhibiting a variation of capillary water zone within a depth of 3 m while the vadose zone and soil water zone were at least 16 m deep. The critical evaporation depth of ground water is 8 m. The long-term influence radius of groundwater dewatering is about 2.72 km during the Baorixile mining operation, and the groundwater level change mainly influences the lower part of the intermediate vadose zone and the capillary water zone below 16 m, with little influence on the moisture contents in the soil water zone where the roots of shallow vegetation grow. The results from this study provide useful insight for sustainable development of coal mining in ecologically fragile areas.

Thermochemical utilization of low rank coal and flotation concentrate

Flotation concentrates are waste material from coal mine operation. The process of steam gasification seems to be an attractive option for their economic utilization and an alternative to their potential combustion in boilers. The gasification process is characterized by both higher efficiency and lower emission of pollution than conventional combustion systems. In this paper the results of the steam gasification of low rank coal and flotation concentrate into hydrogen-rich gas at the temperature of 800 °C are presented. The reactivity for 50% carbon conversion as well as the maximum reactivity in this process were calculated for the samples studied.

Four-point dynamic leveling method for drilling platform application

PurposeIt is essential to level the drilling platform across which a drilling robot travels in a slant underground coal mine tunnel to ensure smooth operation of the drill rod. However, existing leveling methods do not provide dynamic performance under the drilling conditions of the underground coal mine. A four-point dynamic leveling algorithm is presented in this paper based on the platform attitude and support rod displacement (DLAAD). An experimental drilling robot demonstrates its dynamic leveling capability and ability to ensure smooth drill rod operations.Design/methodology/approachThe attitude coordinate of the drilling robot is established according to its structure. A six-axis combined sensor is adopted to detect the platform attitude, thus revealing the three-axis Euler angles. The support rod displacement values are continuously detected by laser displacement sensors to obtain the displacement increment of each support rod as needed. The drilling robot is leveled according to the current support rod displacement and three-dimensional (3 D) attitude detected by the six-axis combined sensor dynamically.FindingsExperimental results indicate that the DLAAD algorithm is correct and effectively levels the drilling platform dynamically. It can thus provide essential support in resolving drill rod sticking problems during actual underground coal mine drilling operations.Practical implicationsThe DLAAD algorithm supports smooth drill rod operations in underground coal mines, which greatly enhances safety, reduces power consumption, and minimizes cost. The approach proposed here thus represents considerable benefits in terms of coal mine production and shows notable potential for application in similar fields.Originality/valueThe novel DLAAD algorithm and leveling control method are the key contributions of this work, they provide dynamical 3 D leveling and help to resolve drill rod sticking problems.

A New Method for Determining Gob Methane Sources Under Extraction Conditions of Longwall Coal Mines

Underground coal mining operations produce large numbers of gobs that contain methane from mining coal seams and their adjacent coal seams. In longwall mining, gob methane is released to coal faces, presenting safety issues. Therefore, if gob methane sources can by identified accurately under extraction conditions, then efficient methane extraction strategies can be adopted to maximize the capture of methane from gobs and to control effectively methane flow to the coal face, thereby reducing safety risks. In this study, a new method to determine quantitatively gob methane sources under extraction conditions was proposed and tested in China’s Liyazhuang Coal Mine. Firstly, the isotope and gas composition of methane desorbed from coal cores of the mining seams and their adjacent seams, as well as methane collected from methane drainage boreholes at different heights in the gobs, were measured. Then, an isotope source model for calculating gob methane sources was established. Finally, based on isotope and gas compositions, the proportions of sources of gob methane that had been extracted from methane drainage boreholes were determined using the afore-mentioned model, and the extraction range that could maximize efficiently the control of methane emissions from each methane source was obtained.

Ecological risk assessment of coal mine area based on “source-sink” landscape theory – A case study of Pingshuo mining area

Coal mining play a fundamental role in promoting economic and social progress. However, intensive mining operations have brought enormous ecological risks, such as landform destruction, vegetation degradation and biodiversity loss. Based on the “source-sink” landscape and ecological risk assessment theories, this study proposes a new methodology to comprehensively analyze the mechanism of ecological risk and makes quantitative evaluation taking Pingshuo coal mine area as an example from 2000 to 2017. The results prove that the “source-sink” landscape theory is more consistent with the nature of ecological process to distinguish the ecological risk in mining area. Within the study period, the main risk source of mining areas is the environmental disturbance brought by mining production with a spreading trend, while the pollution risk caused by residents’ life is relatively low but the scope is large. The ecological niche of risk sink (a place where ecological risks disappear) in the study area improved as a whole, the ecological vulnerability and exposure coefficient of risk sink shows a decreasing trend from core mine area to outside, and the trend was not obvious at the end stage, testifying the protective effect of environmental governance. The striking increase areas of comprehensive ecological risk are mostly concentrated in the surroundings of mining production expansion, testifying mining practice has a significant adverse impact on the contiguous natural ecosystem. Any kind of pressure from coal mine operation, residents’ production and natural erosion in mining area should not be ignored, and the high risk areas are markedly clustered around the risk sources.

14-Month Water Quality Investigation of Coal Mine Discharge on Two Rivers in NSW, Australia: Implications for Environmental Regulation

Ineffective environmental regulation of effluent discharged from an underground coal mine operation has enabled water pollution within two highly valued Australian rivers. This study investigated the impacts on water chemistry of the Bargo and Nepean rivers as a result of the continuous disposal of mine effluent from Tahmoor Colliery over a 14-month period. Coal mine effluent was saline (2180 μS/cm) and alkaline (8.7 pH), and strongly modified the ionic composition within both rivers. Ecologically hazardous concentrations of several metals were found in mine effluent, including aluminium (858 μg/L), arsenic (59.7 μg/L), nickel (60.7 μg/L), and zinc (49.4 μg/L). The effluent also contained elevated total nitrogen (2.89 mg/L) and the waste discharge contributed 67% of the median flow volume in the Bargo River below the discharge point. The plume of saline- and metal-enriched contamination extended at least 9 km downstream past the discharge point, impairing water quality in both the Bargo and Nepean rivers. This study reveals more than a decade of ineffective regulatory and governance systems that enable Tahmoor Colliery to continually release inadequately treated mine effluent.

Enhanced Subsurface Subsidence Prediction Model Incorporating Key Strata Theory

Subsurface strata movements and deformations associated with longwall mining operations in underground coal mines could cause various disturbances to subsurface mine structures, ground water bodies, and coalbed methane reservoirs. In order to assess those disturbances correctly and to design effective and efficient mitigation measures, it is necessary to develop an accurate prediction model for subsurface strata movements and deformations. Decades of research have demonstrated that variations of stratification and lithology in the overburden have significant influence on the subsurface strata movements and deformations during ground subsidence process. The key strata theory states that the thick and hard key strata serve as the backbone of the overburden and control the movements of the thin and soft weak strata located above them. From an engineering standpoint, the overburden strata are subdivided into several individual groups by the key strata with each group consisting of a key layer at the bottom and weak layers overlying it. A new subsurface subsidence prediction model considering the key strata effects on subsurface strata movements and deformations has been proposed. In this method, elastic modulus, specific weight, tensile strength, and uniaxial compressive strength (UCS) of each layer are used to identify the key layers and to determine the needed subsurface subsidence parameters. The influence function method, proven to be accurate and versatile for surface subsidence prediction, was employed to predict the subsidence on each of the overburden layers from mining horizon progressively upward to ground surface with the assumption that the predicted subsidence on a given layer serves as the subsidence source for the layer immediately above. The enhanced subsurface subsidence prediction model has been demonstrated with an actual case to show its applicability and improvement.

Reduction of Dust in the Longwall Faces of Coal Mines: Problems and Perspective Solutions

Despite the increasing reliance on alternative and renewable energy sources in recent years, coal is set to continue being the most vital element of the global energy sector. The world coal supply (1,070 billion tons) shall last for 130 years with the current mining levels. In contrast to some large countries (such as the USA and Germany) reducing their coal production and consumption, Russia plans to increase the coal production levels as part of its strategy regarding the future of the coal mining industry. The annual volume of coal output is more than 440 million tons, 1/3 of which is extracted underground. The current and projected levels of underground coal mining present a set of issues pertaining to elevated dust concentration in the air and increased dust dispersion. High dust concentration in the air leads to damage to the skin, mucous membranes and respiratory organs of workers. Also, with high dust content, visibility in the longwalls decreases, the risk of injury and accidents increases. The present article deals with the formation of detrimental dust conditions that happen in the course of cleaning and preparatory mining operations in coal mines. The article reviews the international practices on dust reduction in coal mining operations and provides an overview of studies on dustiness levels and airborne dust composition in longwall faces of coal mines. It also presents mathematical models dealing with projections on dust composition, including projections on most hazardous dust particles the size of 0.1-10 and 0.1-35 μm. The article also presents a newly developed wetting method showing increased effectiveness.

DETERMINATION OF METHANE DESORPTION ZONE FOR THE DESIGN OF A DRAINAGE BOREHOLE PATTERN (CASE STUDY: E4 PANEL OF THE TABAS MECHANIZED COAL MINE, IRAN)

Underground coal mining is known as one of the major sources of methane emissions which mainly occurs after underground coal extraction. Rock strata in-situ methane can potentially be the most significant hazard in coal mining operations. To prevent or minimize the risks of methane emissions, methane drainage approaches have been adopted by coal mines. Rock mass methane drainage is the most efficient and effective approach toward controlling methane hazards as it prevents and reduces the frequency of methane emissions, outflows into the working area and sudden outbursts of methane and rocks. The method includes drilling boreholes from the tailgate side to the unstressed zone in the roof and floor strata above and below a working coal seam. The coal seam gas content in Tabas Parvadeh I is estimated to be about 16 m3 /t, which is relatively high. Based on exploration data, five distinct coal seams have been identified (B1, B2, C1, C2 and D) at the coal deposit and currently C1 is being worked. Considering the high value of C1 gas content and surrounding rocks, the Methane Drainage System (MDS) has been utilized for gas drainage. This paper tries to determine the desorption area which is essential and helpful for the selection of an effective drilling pattern into the adjacent coal seams. In this study, the methane drainage zone in the E4 panel of the Tabas coal mine was calculated using experimental equations and a drainage borehole pattern was determined.

Environmental investigation of pollutants in coal mine operation and waste dump area monitored in Ordos Region, China.

The increasingly severe emissions of greenhouse and poisonous gases from environmentally unsafe stockpiled coal mine waste dumps have urged people from the academia as well as the industry to focus on environmental impact assessment. In this study, one-year air pollutant monitoring was conducted at the Qipanjing coalfield in Inner Mongolia of China for determining the distribution pattern statue of pollutant exposure and its main driving factors. We used FTIR spectroscopy to measure the inorganic compounds in particulate matter with a diameter of less than 2.5 μm. The spatial and temporal distribution characteristics of leading pollutants, including PM2.5, PM10, SO2, NO2, O3 and CO were analyzed. Firstly, the research showed that the temporal and spatial distribution of pollutants in the coal mine waste area is non-homogeneous. Secondly, some meteorological parameters, such as wind speed, relative humidity, temperature, and rainfall, were found to have significant effects on air pollutant distribution. Stable atmospheric conditions were unfavorable for the diffusion of pollutants and prolong the pollution process. Finally, in the vicinity of coalfields, SO2 and NO2 are present in high concentrations in air. Primary reasons for such high values are coal mining-related activities and active mine fires. This study will help to offer valuable and detailed information for understanding and interpreting the pollution source.

How Do Mines Explode? Understanding Risk in European Mining Doctrine, 1803-1906.

Historians of risk and disaster have paid little attention to coal mining-an industry characterized by extreme risks and disasters-even though coal mine operators were concerned with the causes of explosions throughout the nineteenth and early twentieth centuries. This article goes beyond nationally oriented mining scholarship on coal mine safety and regulations to examine one form of industrial risk: how did European researchers understand the role of coal dust in mine explosions. It describes the complex factors involved in applying science and technology methodologies to solve industrial risk in this dangerous sector. It traces European countries shifting after 1882 to new types of mine experimentation sponsored by the state and mine owners to better mimic real-life situations, while French mining researchers continued to defend work in laboratory settings. French researchers converged methodologically with their colleagues only after the French Courrières mine catastrophe in 1906.

A critical investigation into spontaneous combustion in coal storage bunkers

SYNOPSIS Spontaneous combustion (SC) is a cold oxidation reaction that generates heat, causing a temperature rise of the reactant and leading, with limited heat dissipation, to self-ignition of the reactant, which occurs without an external heat source. Although not limited to coal, the most significant hazard of SC are the fires that occur in coal mining operations around the world. These fires pose a serious risk to the safety of workers in the mines as well as adverse effects on the environment, and can affect the quality of life for current and future generations. We investigated the occurrence of SC in raw coal storage bunkers with the purpose of compiling a decision analyser for engineers designing or working with coal storage bunkers. Specific experts were interviewed from different backgrounds and companies, followed by field research at a coal mine. The important factors affecting the possibility of SC occurring were the type of coal supplied to the bunker, the mining practice, and physical conditions around the bunker. The information presented here will assist in reducing the SC risk in raw coal storage bunkers. These findings, together with the systematic decision analyser developed, will assist design engineers and mine personnel to take early preventative steps in managing SC. The decision analyser was tested for many different scenarios and gave good guidance on how to minimize and prevent SC in bunkers. Keywords: bunkers, coal storage, spontaneous combustion.

Agricultural populations of Festuca pratensis (Poaceae) on the coal mining spoils in the forest-steppe of the Kuznetsk Basin, Russia

The study of meadow fescue agropopulations was conducted in the agricultural phytocoenoses, established on the leveled coal mining spoils in the forest-steppe zone of the Kuznetsk Basin mining region in Russia. In agrophytocoenoses the fescue is not a dominant species, as in the natural meadows of herbs and fescue, which occupied the area prior to spoiling. However, the presence of the meadow fescue in the newly established plant communities resulted in increasing their biological diversity and improving the forage quality. The species was shown to sustain in agricultural communities on the coal mining spoils for more than 25 years, whereas when sown on the zonal soils it maintains it presence for 4-6 years. The ontogenetic groups of the plant in all communities were found to be dominated by virginile, young and mid-aged generative specimen. By the 25th year of agricultural phytocoenoses development the vitality of the agropopulations decreased on the coal mining spoils, composed of both Quaternary and Permian sediments. The study showed for the first time that meadow fescue is a species with good potential to restore vegetation cover in the areas disturbed by the open coal mining.

Sonar mapping of abandoned water-logged underground coal mine and backfilling operation using underwater camera

Sonar mapping of abandoned water-logged underground coal mine and backfilling operation using underwater camera

Sonar mapping of abandoned water-logged underground coal mine and backfilling operation using underwater camera

Sonar mapping of abandoned water-logged underground coal mine and backfilling operation using underwater camera

Comparative Analysis of Three Implementation Model of Policies: Case Study in Acid Mine Drainage Management Policy in Indonesia

Policy implementation is one of the main elements of public policy to ensure that policy is successful in resolving all concerns and promoting the efforts made by the organization as a policy implementer. The implementation of public policies can be influenced by several factors, such as limited budget and human resources, lack of socialization, low commitment of authorized officials, including supervision and sanctions that have not been implemented properly. There are many models of public policy implementation, but policy implementation is still ineffective, especially in environmental policies. Some studies have been performed on the development of a policy implementation model with a range of methods and principles, three of them are policy implementation models developed by Van Horn-Van Meter; Grindle; Mazmanian and Sabatier. Those three methods are used respectively according to the existing conditions with different levels of achievement. The objective of this article is to assess the best model of policy implementation related to Acid Mine Drainage management policy of coal mining operations in Indonesia through a comparative study review. The results of the analysis show that the model developed by Mazmanian Sabatier is the most appropriate model to implement the policy of Acid Mine Drainage in Indonesia.