Coal Deposits Research Articles

An original set of nanometer-scale mineralogical analyses of cookeite and the implications for Li enrichment: No. 21 coal, Mengjin Mine, western Henan

Critical elements in coal deposits, such as lithium (Li), have attracted attention recently due to their economic value. Many studies have suggested that the high enrichment of Li in coals is predominantly associated with cookeite, a Li–bearing chlorite mineral of hydrothermal origin. However, the identification of cookeite in coal has primarily relied on indirect methods, owing to the low atomic number of Li, which presents significant challenges for precise observation. The Shanxi Formation No. 21 coal in North China is enriched in Li. This study established a nanometer–scale mineralogical analytical technique (including high–resolution transmission electron microscopy (HR–TEM), fast Fourier transformation (FFT), and standard mineral simulation single-crystal diffraction (SSCD)) for the identification of the cookeite and evaluated the Li enrichment mechanism and recovery in this coal (low–volatile bituminous to semi–anthracite) based on a model for the Li mineralization. The Li content of the No. 21 coal ranges from 25.2 to 203 ppm. The Li content shows a strong correlation with the ash yield, Al2O3, SiO2, and detrital elements, indicating a dominant aluminosilicate affinity and detrital origin. The major aluminosilicate minerals in coal are kaolinite, chlorite, and illite. The geochemical indicators (the Al2O3/TiO2 ratio and its relationships with the Zr/TiO2, Nb/Y, and Nb/Yb ratios) indicate that the sediment sources are determined to be intermediate–felsic igneous rocks, probably the Mesoproterozoic moyite (a type of K– feldspar granite) in the Yinshan Oldland. Additionally, the coal can be divided vertically into three sections (Sections I, II, and III), corresponding to three stages of peat formation. Overall, from Section I to Section III, the degree of detrital input increased, and the groundwater and marine influences strengthened and weakened, respectively. Section II exhibits anomalous Li enrichment mainly associated with reducing environments and the geochemical barrier caused by the interaction between infiltrating seawater and groundwater. The detrital kaolinite assemblage with authigenic minerals such as secondary REE–rich minerals (bastnasite), chamosite, and quartz, as well as the REY enrichment patterns, suggests that the No. 21 coals, mainly Section II, may have existed the hydrothermal alteration. Cookeite is identified primarily in Section II and coexists with kaolinite based on TEM observations, suggesting that the cookeite is of hydrothermal origin and formed from pre–existing Li–rich kaolinite. Most samples from Section II meet the mining grade of Be–Li–Nb–Ta ore deposits (Li2O > 0.2%). Thus, this study offers valuable insights into the extraction and recovery of Li from coal combustion residues, particularly when cookeite is the primary Li–bearing mineral.

Tetrafluoroboric Acid Digestion for Accurate Determination of Rare Earth Elements in Coal and Fly Ash by ICP-MS Analysis

Coal and coal-related fly ash often contain rare earth elements (REEs) that have the potential to be utilized as valuable mineral resources. Accurately determining the REE content in coal and fly ash is crucial for resource evaluation. The conventional approach involves using hydrofluoric acid (HF) to dissolve silicates and release REEs, which, however, prolongs the digestion process due to the additional step of complexing fluoride ions (F−) with boric acid (H3BO3). Determining the correct amount of H3BO3 for neutralization can be challenging, and in some instances, the binding of fluoride ions with certain lanthanides (Lns) hampers the accurate determination of all 14 naturally occurring rare earth elements in a single digestion batch by inductively coupled plasma mass spectrometry (ICP-MS). In this study, we present an alternative method that achieves the accurate determination of all 14 naturally occurring REEs using tetrafluoroboric acid (HBF4) followed by ICP-MS analysis. This approach eliminates the need for an F− complexing step. We tested this method on certified REE reference materials, including NIST 1632e (coal) and NIST 1633c (fly ash), as well as the REE geological reference material USGS AGV-1 (andesite). Our results demonstrated excellent recovery rates (relative standard deviation, RSD < ±10%), with a correlation coefficient (r2) exceeding 0.99. Using this method, we investigated the concentrations of all 14 REEs in coal and fly ash samples collected from various locations in the southwestern USA. This improved digestion technique streamlines the analysis process and enhances the accuracy of REE determination, facilitating a more comprehensive evaluation of REE-rich coal and fly ash deposits for resource exploration.

Biological reclamation of post-technogenic landscapes of Yakutia: problems and prospects

In the context of intensive industrial development in the Republic of Sakha (Yakutia), the issue of restoring technogenically disturbed areas is becoming increasingly relevant. Technogenic landscapes formed during the extraction of mineral deposits often have negative effects on the environment, and severe environmental conditions hinder the restoration of ecosystems affected by industrial activities. This study synthesized the long-term research results of scientists from the Research Institute of Applied Ecology of the North named after Prof., Dr. Savvinov (NEFU) on the study of succession and soil restoration processes in post-technogenic landscapes of placer deposits in the basins of the Anabar River and the Aldan River, as well as at the diamond and coal ore deposits in the Mirninsky, Aldansky and Neryungrinsky regions of Yakutia. Our study demonstrated that the effective restoration of technogenically disturbed landscapes is relevant to the use of seeds and planting materials from local flora in the biological stage of reclamation. On the dumps of ore deposits composed of rocks that are slowly weathered under hypergenesis conditions, effective restoration can be achieved only with the formation of technogenic soil. Due to the deficit of (decipher) PPP and (decipher)PSP, it is necessary to create a technology for the biological reclamation of disturbed lands with the use of alternative materials.

Effects of water-based SiO2 nanofluids on the wettability of coal dust and particle deposition characteristics

Coal wettability plays a crucial role in the prevention of coal mine dust and associated disasters such as coal and gas outbursts. Water-based SiO2 nanofluids have emerged as promising wetting agents because of their sustainable wetting effects on coal. However, the current research on the wetting characteristics of nanofluids has predominantly focused on small coal fragments, with limited studies on coal dust. This study aims to investigate the influence of water-based SiO2 nanofluids with varying particle concentrations on the wettability of coal dust via physical experiments. The findings revealed that the modification by nanofluids significantly reduced the contact angles of the coal dust particles with the particle size ranges of 60–80, 80–100, and 100–150 mesh, compared to the initial contact angles. Moreover, higher particle concentrations resulted in smaller contact angles. Notably, the wetting effects of the nanofluid modification on coal dust were particularly prominent for larger particles. Furthermore, compared with water immersion, nanofluid modification demonstrated a significantly more positive impact on the wettability of coal dust. Notably, the SiO2 nanoparticles exhibited a wide distribution and substantial adsorption capacity on the coal surface, enabling the formation of a hydrophilic structure coverage. This study contributes to a comprehensive understanding of the wetting behavior of coal dust when exposed to water-based SiO2 nanofluids. These findings underscore the potential of nanofluids to enhance coal dust prevention and control, and provide valuable insights for future research in this field.

‘Black Gold’ and Verticality: Geology, Labour and Mining Operations in the Territorial Construction of the Witbank Labour District

Scholars acknowledge the importance of geological knowledge in the growth of South Africa’s mining industry. While this acknowledgement extends to the analysis of the rise of eMalahleni (formerly known as Witbank) to the status of ‘premier coal supplier’ of the Union of South Africa, there is currently no specific historical analysis of the role of geological knowledge in the growth and development of the district’s mining industry. This article is a response to Kate (formerly Peter) Alexander’s call to study the history of mining with reference to the contribution of geological knowledge, and provides a detailed historical account of such a contribution to the development of the political economy of the mining industry of eMalahleni. 1 Using a wide range of archival sources, the article draws from literature on the production of vertical territory and takes as its starting point the role of scientific societies such as the Geological Society of South Africa and the South African Institute of Mining and Metallurgy in the creation of geological knowledge about the coal deposits of the former Transvaal. It then examines the roles of the Transvaal Geological Survey and the Geological Survey of the Union of South Africa, as well as geological maps produced by Alexander Graham in the creation of the Witbank Coalfield, to demonstrate how the development of geological knowledge and mining operations became processes that defined the constitution of the Witbank Labour District. The paper argues that the making of the Witbank Labour District as a coal-mining district was tied to the making of the Witbank Coalfield and that the making of the coalfield from which the district’s mining industry developed was a process in which the availability of labour was as crucial a factor in the expansion of its mining operations as scientific societies, shafts, drilling operations and expert geological knowledge.

Modelling of a multi-seam hard coal deposit using IT tools

With the rising demand for mineral resources, efficient deposit management has become a critical challenge in modern mining. This article underscores the significance of geological modeling in coal deposit management, emphasizing the essential role that digital deposit models play across various mine departments. It outlines the methodology for creating geological models, detailing steps such as data digitization, validation, model construction, calibration, and continuous updates. The article examines three specific deposit modelling software programs (Minex, MineScape, and Carlson) highlighting their unique features and suitability for multi-seam coal deposits. The findings include the development of contour maps, structural and qualitative models, and conducting economic analyses. Additionally, the article discusses the importance of modelling tectonic disturbances and creating qualitative maps for effective deposit exploitation planning. It concludes by emphasizing that the integration of information technology with geological expertise is crucial for precise planning and optimization of mining operations, leading to more efficient and sustainable resource management.

Restructuring substantial increase in natural gas reserves by coalbed methane (CBM) recovery

Coal deposits, especially hard coal deposits, contain in their structure large amounts of methane, which during exploitation is diluted through industrial ventilation and degassing technologies down to non-hazardous concentrations, reducing the major risk factor for the safety of workers and resources minerals. The amount of methane released and exhausted into the atmosphere by the degassing and ventilation stations of the mining units, in addition to being wasted instead of being used, is also a factor of environmental pollution, as a potential greenhouse gas (GHG). The environmental issues and the climate crisis faced by humanity compel the establishment of an Action Program on the methane issue, which includes the capture, recovery and exploitation of gas from active coal mines, or from virgin strata, from unexploited mining fields, with the help of currently available technologies and practices, which represent the chance to obtain clean energy and substantial climate benefits, in the short and long term. The solution to the use of methane gas from coal at active mining operations in Jiu a Valley - Romania, by burning it to obtain the thermal agent, brought important economic benefits by reducing energy costs and environmental protection by reducing methane emissions in the atmosphere. The present paper proposes an analysis of the benefits obtained as well as the development possibilities of methane usage for obtaining a clean fuel.

Water Waves – A Source of Clean Energy

The constantly developing world economy needs the energy necessary for the socio-economic development of the countries that constitute it. Easy access and low extraction costs determine the choice of energy source. The exploitation of high-energy deposits of energy raw materials is at such a high level that we are in danger of completely exhausting them. Concern for the state of the environment, which is directly influenced by the use of non-renewable energy resources, has resulted in a focus of interest in renewable energy sources. The authors used theoretical research methods, including: analysis of content and source documents, including reports and statistical data, synthesis, generalization and conclusions. The aim of the article is to demonstrate that in times of global energy crisis caused by the depletion of oil, gas and coal deposits, new technologies mark the beginning of a long road to taming the sea and its waves as a source of clean energy. The article will complement the critically assessed scientific works carried out so far on this topic in terms of their universality, as well as the identified gaps in relation to the use of sea waves for the needs of humanity, in terms of energy.

Features of design and work method of mining module at coal deposits in the Russian Arctic

Features of design and work method of mining module at coal deposits in the Russian Arctic

Tools available for methane recovery from mines belonging to C.E.H. Petroşani

Mine gas is present both in coals and in the surrounding rocks and basically consists of methane (some-times almost 100%) mixed with carbon dioxide (up to 5%) with nitrogen (a few percent) and traces of carbon monoxide. The genesis of mine gas can be related to the biochemical transformation of vegetation during the carbonization process. The degassing of coal bed has been established as an active method of reducing methane emissions due to the need to ensure the exploitation of the bed with high productivity and in safe conditions. The methane gas existing in the coal bed is captured through various types of drilling executed for this purpose, being directed through a system of pipes to the surface to the central degassing station from where it can be taken and directed for use for a specific purpose. From an economic point of view, it has been proven that methane recovery from coal mines is again a profitable activity for both the mining company and a possible investor. The volume of methane from the coal deposits in Jiu Valley is very large and can provide large quantities for the recovery of this gas. At the same time, there was already a market for this product in Jiu Valley made up of industrial and individual consumers.

Production of biodiesel from low-quality vegetable oils with a high content of free fatty acids by acid-catalyzed transesterification

Research on the production and application of cheap and renewable energy sources is one of the most relevant directions in modern science. They are imposed for a number of reasons, mainly due to the limited deposits of oil, natural gas and coal, the protection of the environment and the health of people. Unfortunately, the needs for such alternative energy sources are huge, and the possibilities for obtaining them are limited. On the other hand, low-quality vegetable oils obtained as waste products or as a result of improper storage or processing, as well as oils after use represent a valuable raw material and energy source. However, this necessitates the search for ways to utilize them by turning them into better quality products. The aim of the present work is to investigate the possibility of obtaining methyl esters of fatty acids (biodiesel), from vegetable oils with high acid values, by transesterification with acid catalysts, which includes the selection of suitable catalysts and conditions for optimal process progress.

Predicting surface mining influences in an integrated mining design and planning system

While planning the exploitation of a deposit, the volume and quality of coal in the longwall parcels are taken into consideration, however, designers must consider many other aspects and among them, the influence of the planned mining on the ground surface. This article presents the possibility of using the Subsidence module, integrated with mining planning tools, to perform approximate analyses of the mining influence on the surface. The assumptions of the calculation model used in the module are presented, including the general characteristics of the influence function used for forecasting. The results of the prognosis for two longwalls were compared to a reference solution routinely used to perform this type of prognosis. The differences resulting from the use of a simpler calculation model and a different method of calculating horizontal displacements were characterized. The advantages of integrating spatial data about the deposit, the projected exploitation, and its effects, which allowed a much faster assessment of the scale of projected deformations and basing the calculations on detailed geological and mining data, were also presented.

Modern design solutions in the design of boiler units, ovens and fireboxes burning solid fuel in a fluidified bed

Coal fuel has always played an important role in Russia’s fuel and energy balance due to its extensive reserves, availability in a number of regions and relatively low cost. Currently, coal flaring technology is widely used in domestic boiler plants, but it should be noted that this approach is more applicable for high-quality high-calorie coals with low ash content. In addition, flaring is sensitive to changes in the composition of the fuel and deviations from the specified values can lead to a decrease in the reliability of the boiler unit. There are also regions where there are deposits of low-grade coal that are not suitable for flaring. The problem of boiler sensitivity to the use of unspecified fuels, as well as the involvement of local low-grade fuels, can be solved by introducing circulating fluidized bed (CFB) combustion technology.

Characteristics of Coal Dust Deposition in Boiler Tail Gas Pipelines

Coal dust deposition in boiler tail gas pipelines can significantly affect boilers’ thermal and energy efficiency. This study investigates the deposition characteristics of coal dust particles in boiler tail gas tubes in variable cross-section tubes. Numerical simulations were performed using the Reynolds Stress Model and the Discrete Particle Model. User-defined functions coding is used to construct the particle deposition model in the particle deposition model. The study analyses the distribution of turbulent kinetic energy locations in the gradient tube, compares the distribution of particle deposition on its wall, and concludes that the deposition distribution of coal dust particles in the gradient tube is slightly different for different particle sizes. Smaller particles have a higher deposition efficiency in equal cross-section pipes than larger particles. Particle size also has a significant effect on pipe taper and expansion. The results of this study can provide theoretical guidance for optimising the design of boiler tail gas pipelines, improving energy efficiency, and reducing environmental pollution.

Characteristics of Coal Dust Deposition in Boiler Tail Gas Pipelines

Coal dust deposition in boiler tail gas pipelines can significantly affect boilers’ thermal and energy efficiency. This study investigates the deposition characteristics of coal dust particles in boiler tail gas tubes in variable cross-section tubes. Numerical simulations were performed using the Reynolds Stress Model and the Discrete Particle Model. User-defined functions coding is used to construct the particle deposition model in the particle deposition model. The study analyses the distribution of turbulent kinetic energy locations in the gradient tube, compares the distribution of particle deposition on its wall, and concludes that the deposition distribution of coal dust particles in the gradient tube is slightly different for different particle sizes. Smaller particles have a higher deposition efficiency in equal cross-section pipes than larger particles. Particle size also has a significant effect on pipe taper and expansion. The results of this study can provide theoretical guidance for optimising the design of boiler tail gas pipelines, improving energy efficiency, and reducing environmental pollution.

ЗЕМЛЕВЛАДЕЛЬЧЕСКАЯ АРИСТОКРАТИЯ РОССИЙСКОЙ ИМПЕРИИ И ЭКОНОМИЧЕСКОЕ ИСПОЛЬЗОВАНИЕ ЧАСТНОГО ПРАВА НА НЕДРА В ПЕРИОД "ИНДУСТРИАЛИЗМА" 1890-1914 ГГ.

Based on the study of archival materials (primarily from the funds of the Yusupov princes), the article considers the issue of the realization by the largest landowners of the Russian Empire in 1890–1914 of their right to the subsoil in order to increase the profitability of their estates. As it turns out, that economic strategy was characteristic not only of a small group of Ural owners, but also for many other titled aristocrats whose possessions were located in the central provinces and especially in the regions of Southern Russia (Donbass and the Caucasus), where huge reserves of mineral raw materials were discovered. The analysis of the relevant sources shows what significant opportunities for increasing revenue were provided by coal and oil deposits, and primarily, by the initiative and economic pragmatism of private landowners in organizing extractive production. As a rule, most aristocrats managed to increase their cash receipts immediately due to minimal organizational efforts. But in the future, with the expansion and complication of extractive production, landowners faced a lack of available funds. The way out of that was seen in selling their lands or in the corporatization of the enterprise, which guaranteed the aristocrats a certain dividend from profits, but transferred most of the capital and income of the estate into the hands of industrial or banking companies. In any case, the entry of the Russian economy in 1890-1914 in the “industrial” period turned out to be extremely profitable for the largest landowners, not only for purposes of developing their agricultural estates, but also in terms of the diversification of their economy, including through the active exploitation of mineral resources.

Challenges and effectiveness of IT tools used in mining for forecasting production parameters

The research examines the challenges and effectiveness of IT tools used in the mining industry for forecasting production parameters, a crucial aspect as mining operations become increasingly complex. Accurate forecasting is essential not only for optimizing efficiency, safety, and profitability but also for managing the high risks associated with the construction and operation of mining plants, which require long-term financial security and flexible production management. The study explores various IT solutions, such as advanced data analytics, machine learning algorithms, and simulation models, employed to predict key production parameters like ore quality, equipment performance, and resource availability. However, significant challenges, such as data quality issues, the integration of diverse data sources, and the need for specialized expertise, pose obstacles to the effective use of these tools. Despite these challenges, the research finds that IT tools can lead to more accurate forecasting, improved decision-making, and enhanced operational planning, provided that technical and organizational hurdles are addressed. The paper also highlights the importance of modern IT tools in mining production scheduling, demonstrating their advantages over older tools like MS Excel. By presenting examples from coal and copper ore deposits, the study shows that these modern tools not only increase the accuracy of production forecasts but also enable the creation of multiple scenarios and the rapid modification of schedules, which are key to maintaining the competitiveness and liquidity of mining companies.

ПРОМЫШЛЕННЫЕ ОТХОДЫ ДЛЯ ЗАКЛАДКИ ВЫРАБОТАННЫХ ПРОСТРАНСТВ УГОЛЬНЫХ И РУДНЫХ ШАХТ КУЗБАССА

Coal mining and mining enterprises are the basis of the Kemerovo region economy. Comprehensive assessment of their impact on the environment showed the activation of exogenous geological processes: dips formed over previously liquidated inclined and vertical mine shafts; waterlogging; drawdowns and landslides. In the flooded goaf spaces of mines the structure of rocks is disturbed, the fixing material of the workings is destroyed, forming dips and subsidence troughs. Traditional goaf backfilling technologies using cement, sand and gravel make products more expensive, what makes coal mining and mining enterprises in the region unprofitable. A significant reduction in the cost of backfilling is possible with the introduction of industrial waste disposal technologies - using them as components of hardening mixtures in the development of coal and ore deposits. Taking into account the mining and geological conditions of Kuzbass - powerful steep and inclined deposits, compositions of cement-free laying mixtures with the use of steel slags for the industrial implementation of chamber and floor-chamber development system were developed. Key words: stowing mixtures, steel slag, strength, structure, burnt rock, sludge.

Improving the Stability of Mining Slopes in Tarcha Coal Mine, Southwestern Ethiopian Deposit Through Geometric Adjustments

The Tarcha coal deposit, located beneath the Omo trachyte flows in the Omo‐Gibe River basin of southern Ethiopia, is actively mined using open‐pit methods for energy resources. However, these mines face significant slope instability issues. This study aims to assess and enhance the stability of the selected open‐pit coal mine quarries through field and laboratory analyses, supported by the limit equilibrium method (LEM) and the finite element method (FEM). Fieldwork involved detailed measurements of slope geometry and orientation, in situ rock testing, and soil and rock sampling for laboratory analysis. Results indicated that the rock quality designation (RQD) of the rocks ranged from 22 to 57.5, indicating rock quality from very poor to fair. Schmidt hammer tests revealed uniaxial compressive strength (UCS) values between 14.79 and 29.31 MPa. Soil analysis classified the soils as sand with low to high plasticity (8.89% to 31.86%) and a liquid limit range of 21% to 62.63%. Stability analyses using LEM and FEM on two critical slopes (MS‐1 and MS‐2) under saturated, unloading, and loading conditions indicated instability. However, geometric adjustments, such as reducing slope angle, decreasing slope height, and implementing benching, were found to significantly improve slope stability.

On the Possibility of Waste-Free Use of Mineral Resources of the Angrensky Brain Coal Deposit

The Angren lignite basin is a complex coal-kaolin deposit. Here, in addition to brown coal, there are large reserves of kaolin clays of two types - primary and secondary, occurring respectively in the soil and the roof of the coal strata. Secondary clays, in turn, subdivided into gray and variegated, which during overburden and mining of coal seams in the bulk go to the dump. Gray kaolins currently partially processed at the “Angren Kaolin” LLC factory in order to obtain enriched kaolin used for the production of building ceramics, etc.