Mine Openings Research Articles

EVALUASI ANALISIS GEOTEKNIK PADA TAMBANG TERBUKA BATUBARA PIT NORTH WEST PT ANAK TAMBANG INDONESIA JOB SITE PT ADIMITRA BARATAMA NUSANTARA, KALIMANTAN TIMUR

On a mine slope there will be a driving force and a resisting force. The mine slope will collapse if the driving force is greater than the resisting force. Thus, the principle of mitigating mine slope failure is to reduce the driving force or increase the resisting force. PT Adimitra Baratama Nusantara intends to develop a new mining area in the North-West area within the IUP area. Therefore, it is necessary to carry out a geotechnical study that focuses on slope stability analysis to support open-pit coal mining plans based on data from geotechnical investigations in the field, secondary data and geotechnical laboratory test data. Geotechnical modeling for slope stability analysis was carried out using the Finite Element Method because the overburden and interburden sedimentary rocks of coal seams are considered to have behavior approaching elasto-plastic, so that it will provide results that are close to the actual situation in the field. Modeling and slope stability analysis of the mine opening design represented by section-01 and section-03 with the height of each opening being 126 m and 119 m shows that the high-wall and low-wall slope designs are not yet stable, so a re-design is necessary. with the mine opening floor simulated at level -110 and level -90.

Determination of the type of arched carbon fiber reinforced fastening of the preparatory opening for the conditions of the «Dniprovska» mine in weakly metamorphized rocks

The object of study is an arched carbon fiber-reinforced support of constant cross-section in a layered massif of weakly metamorphosed rocks. The article presents an analysis of the possible use of arched fiber-reinforced support of constant cross-section in a layered massif of weakly metamorphosed rocks for the conditions of the «Dniprovska» mine (Ukraine) around the preparatory opening. An analysis of the stability of mine openings in Western Donbas mines has shown that it is necessary to modernize the support system by introducing carbon fiber. The main reason for the low stability of the opening is the insufficient load-bearing capacity of the support, while its technical characteristics do not take into account the complex mining and geological conditions. The increase in stresses at mining depth is associated with impact safety, which is a serious problem during mining. Metal arch supports are deformable and have high rock loads and require a high level of energy absorption, i. e., to be very strong and flexible to withstand significant loads and avoid large displacements of the opening walls. Carbon fiber-reinforced plastic is able to ensure the stability of the fastening system and eliminate the existing disadvantages of typical metal arch fasteners, namely, high labour intensity, low production speed and high weight of the structure. In this article, the stress-strain state for the specified conditions and the carbon fiber-reinforced plastic arch support of constant cross-section was analyzed using the SolidWorks software product, taking into account the physical and mechanical properties of carbon fiber-reinforced plastic and layered rocks. Taking into account the results of laboratory tests of an equivalent layered array on a press made of PLA and carbon fiber, the dependence of deformations of the equivalent array with increasing load was established. The use of arched carbon fiber supports of various cross-sections can ensure the opening stability by reducing the intensity of stresses around its contour. On the basis of this study, a rational arched composite support of constant cross-section was proposed for the conditions of the «Dniprovska» mine. The obtained results indicate the need for further research, which will be considered in the author's future works.

The regional economics of mineral resource wealth in Africa

AbstractWe study the regional economics of mineral resource activity in Africa. Using geocoded data on mine openings and closures in Africa, we document that mining regions experience local economic booms while a mine is in operation. We then explore how mineral resources affect non‐mining regions. Non‐mining regions might be affected by mining activity due to deliberate government policies (e.g. regional redistribution) or due to various inadvertent country‐level macroeconomic adjustments (e.g. Dutch‐Disease‐type effects or declining institutional quality). Our results suggest that mineral resources have heterogeneous effects on non‐mining regions. Politically important regions benefit economically, while generic non‐mining regions are, in general, worse off. Exploring mechanisms, we find that these spatial patterns arguably emerge due to both deliberate government policies as well as Dutch‐Disease‐style macroeconomic adjustments that harm regions specializing in sectors other than mining.

Machine Learning-Based Classification of Rock Bursts in an Active Coal Mine Dominated by Non-Destructive Tremors

Rock bursts are dynamic phenomena in underground openings, causing damage to support and infrastructure, and are one of the main natural hazards in underground coal mines. The prediction of rock bursts is important for improving safety in mine openings. The hazard of rock bursts is correlated with seismic activity, but rock bursts are rare compared to non-destructive tremors. The five machine learning classifiers (multilayer perceptron, adaptive boosting, gradient boosting, K-nearest neighbors, and Gaussian naïve Bayes), along with an ensemble hard-voting classifier composed of these classifiers, were used to recognize rock bursts among the dominant non-destructive tremors. Machine learning models were trained and tested on ten sets of randomly selected data obtained from one of the active hard coal mines in the Upper Silesian Coal Basin, Poland. For each of the 627 cases in the database, 15 features representing geological, geomechanical, mining, and technical conditions in the opening as well as tremor energy and correlated peak particle velocity were determined. Geological and geomechanical parameters of the coal seams and surrounding rocks were aggregated into a single GEO index. The share of rock bursts in the database was only about 8.5%; therefore, the ADASYN balancing method, which addresses imbalanced datasets, was used. The ensemble hard-voting classifier most effectively classified rock bursts, with an average recall of 0.74.

Impact of Artisanal Gold Mining in Community Conserved Areas with High Biodiversity Using a Multi-Criteria Approach: A Case Study in Colombia

Artisanal small-scale gold mining (ASGM) using mercury affects community agreements for the conservation of forests (CoS) and lakes (CoH), which have a high level of biodiversity in the Peasant Reserve Zone of the Cimitarra River Valley (ZRC-VRC) in Colombia. In this research, a multi-criteria approach (MCA) was applied to analyze the impact of ASGM. This analysis is based on the community environmental agreements to preserve CoS and CoH areas, the ecological importance of these areas, as well as the results of mercury dispersion in the Cimitarra river basin, with concentrations found 40 km downstream of the mining area of 0.09 µgTHg L−1 in the Cimitarra river, 0.07 µgTHg L−1 in the CoH, and 0.01 mgTHg kg−1 in the tissues of macrophytes, as well as the increase in deforestation since 2020 in the CoS, due to a 1.8% (990 ha) loss of forest cover, with 693 ha of the forest cover loss coinciding with areas related to the opening of new mines. The MCA showed that the main impact is found within the criterion Social and armed conflict, followed by Deforestation. This research offers recommendations to reduce impact scores, such as the implementation of a sustainable development plan (PDS) of the ZRC-VRC, and it highlights the urgent need to safeguard the community conservation areas.

Arching of force chains in excavated granular material

The physical arch and the arch effect are related to many geotechnical problems, such as the stability of mine openings, a tunnel’s shape, and disaster prevention. However, observing the arch in geo-material is challenging due to Earth’s invisible force network distribution. The arch shape is a critical parameter related to the arching effect, which is still an open question. Specifically, the force network evolution after local excavation in granular material is revealed using the photo-elastic technique, and the system pressure variation is calculated qualitatively in particle scale according to the G2 algorithm. Besides, the force chain arch is formed by strong force chains, which are important in redistributing the stress field. The principal direction of the spatial correlation colormap represents the direction of the strong force chains in the network. Based on this preferred angle between the strong force chain and the horizontal direction, a simplified force chain arch trajectory is iteratively rebuilt. Then, the total force chain distribution is studied considering both G2 and the total length of strong force chains, with the corresponding results demonstrating a relationship between the changes in these characteristics and the force chain arch formation.

Influence of dip angle of lithologically nonuniform interburden on horizontal mine opening stability during driving

Influence of dip angle of lithologically nonuniform interburden on horizontal mine opening stability during driving

Water Chemical Analysis of Surface Water Runoff from Iron Ore Mine Void at Tanjung – Bone, South Sulawesi.

The main problem in open-pit mining activities is the remaining mine openings as voids after mining activities end. The interaction between rock, water and air can cause dissolved rock chemical elements to cause polluted water. A study of this phenomenon was carried out in a void in the Tanjung area. An abandoned iron ore mine left a void with a depth of 13 meters. Furthermore, around the void existed two stockpiles of mined ore. Therefore, the void and the stockpiles may act as pollutant sources that can reduce surface water quality. In the rainy season, the water from the void flows out as a runoff downstream through a tributary. This study is intended to analyze the chemical concentration of runoff water from the void. Field observation was done to identify rock formation, and measured pH, turbidity, total dissolved solids (TDS), and electrical conductivity(EC) of water on site, and collected 10 water samples from the river and tributary. Field data was completed with laboratory chemical analysis for water major elements of K+, Na+, Ca2+, Mg2+, Cl−, SO4 2−, CO3 2− and HCO3. The results of the analysis of the TDS test with a minimum value of 4 mg/l and a maximum of 607 mg/l. turbidity value 0 to 21.4 NTU, pH value 2.9 to 8.2, EC value 165.6 ms/cm to 316 ms/cm. Plotting the concentration of the major elements into Trilinear Piper Diagram shows that water is as CaMgSO4 water type based on their major elements. Changes in water quality at voids, stockpiles and areas around the mine indicate that potential water pollution is generated from existing stockpiles.

Bat use of abandoned mines throughout Nevada

AbstractAbandoned mines offer important roosting habitat for several species of bats throughout the western United States. Currently, abandoned mine reclamation programs are tasked with closing abandoned mines to ameliorate safety, health, and environmental hazards found in and around these sites. Without appropriate pre‐closure evaluations to determine use of mine workings prior to closure, bats that depend on abandoned mines may be negatively impacted. To mitigate impacts of abandoned mine reclamation on bats, surveyors typically conduct pre‐closure biological evaluations and recommend wildlife compatible closures (e.g., bat gates) for ecologically important sites. Due to hazardous conditions found in many abandoned mines, internal surveys cannot always be conducted, and external surveys are not reliable for determining underground habitat or inferring past, future, or potential use of mines by bats when they are absent during external surveys. The purpose of our study was to use internal mine surveys to examine relationships between abandoned mine use by bats and characteristics of the mine and landscape, including portal area and shape, number of portals, mine depth, elevation, proximity to water and land use type. We found that surface features including land use type, distance to water, and elevation were associated with bat use, as were several mine features including depth of workings and portal shape. To best conserve sensitive species of bats, it is essential that pre‐closure biological evaluations be as detailed as possible to enhance biological understanding of species' roosting associations and distribution throughout the landscape. Further information will best facilitate development of ecologically sound closure recommendations for abandoned mine openings.

Distribution System Dewatering in Coal Mining at PIT Sena Sungai Lilin District, Musi Banyuasin Regency, South Sumatra Province

The purpose of this research is to calculate the total design discharge of water entering the mining site in the sena pit of PT Putra Muba Coal (PMC), design the appropriate shape and dimensions of the sump to accommodate the amount of water entering the mining site and calculate the number of pumps needed to remove water entering the mine to the settling pond. The source of water entering the mine area comes from rainwater entering the mine opening, water runoff from the rainwater catchment area in the area around the mine opening, and groundwater rise. Based on the results of the analysis of rainfall data for 2013-2022, a rainfall plan of 77, 225 mm/day, rainfall intensity of 9.714 mm/hour with a rainfall return period of 2 years was obtained. The rainfall catchment area at the research site is 72,936 m2 with a discharge generated of 0.03 m3 / second and groundwater discharge of 0.00812 m3 / second. To remove the water entering the mine, it is flowed naturally into the sump with dimensions of 50 m length, 14 m top width, 13 m bottom width, and 5 m depth. The dimensions of the open channel are planned with a channel width of 32 cm, a flow depth of 28 cm, a wet cross-sectional area of 13.6 cm2, a wet circumference of 97 cm, a hydraulic radius of 9.25 cm, and a channel length of 233m. The water in the sump is pumped into an open channel. The pump used has a maximum discharge of 150 m3 / hour and a total pump head of 11.8712 m with a pipe diameter of 6 inches.

Geology and Groundwater Quality Analysis for Clean Water and Irrigation of Sanga-sanga District, Kutai Kartanegara Regency, East Kalimantan Province

The research locations are in two sub-districts, namely Sanga-Sanga District, Samarinda City and Palaran District, Kutai Kartanegara, East Kalimantan Province The research method used in this study is geological mapping, then laboratory analysis. The well water sample data used is 2 sample water which is considered to represent the research area. Geological conditions in the study area there are 3 rock units where the rock units of the oldest are the Sanga-sanga sandstone unit, the Bantuas sandstone unit and alluvial deposits. For geomorphological units, it is divided into 6 forms, namely the eroded hill unit, the remaining hill, the Alluvial Plain, swamp, river body, disposal and mine opening. Based on the results of the piper diagram analysis Groundwater is included in the type of magnesium bicarbonate with carbonate hardness (secondary alkalinity) > 50% groundwater is dominated by alkaline soil (Ca + Mg) and weak acids (CO3 + HCO3), and based on the results of the stiff diagram analysis, the research area is included in the type of calcium carbonate (CaHCO3) and Magnesium Carbonate (MgHCO3). The assessment of groundwater quality for irrigation purposes concluded that the analyzed sample could be used as irrigation water.

A review of Open Channel Design for Mine Dewatering System Based on Environmental Observations

The purpose of mine dewatering system is to control runoff water that enters mine openings so that the mining process is not disturbed. The rainfall discharge (Q) is 0.0951 m³/second and the runoff discharge (Q) is 0.69 m³/second, making the total mining discharge entering the location 0.781 m³/second. The open channel design has dimensions of Channel wall slope (α) = 60°, Water depth (h) = 0.73 m, Channel depth (d) = 0.83 m, Channel base width (B) = 0.73 m, Surface width (b) = 1.57 m, Wet cross-sectional area of channel (A) = 0.92 m², and Channel wall length (a) = 0.97 m. The sedimentation pond has the following dimensions and compartments: Total length (l) = 104 m; width (b) = 8 m; depth (H) = 4 m; partition width = 4 m; partition depth = 4 m; partition length = 7 m. It consists of 3 compartments: conditioning compartment, separation between solids and mine water, and flow with an area of 277 m² per compartment. The sedimentation pond volume is 3094 m³ with a total area of 830 m². The results of the study obtained information that to control runoff water entering mine openings, a pond capacity as a settling site was needed of more than 3094 m³ with a maximum dredging time of settling pond particles that can be done once every 10 months.

Impact of past mining activities on water quality in a karst area in the Cévennes region, Southern France

Sampling and analysis of groundwater and surface water were conducted to assess the potential impacts of abandoned mines on water quality in a karst area in Southern France. The results of multivariate statistical analysis and geochemical mapping revealed that water quality is affected by contaminated drainage from abandoned mine sites. Acid mine drainage with very high concentrations of Fe, Mn, Al, Pb and Zn was identified in a few samples collected from mine openings and near waste dumps. In general, neutral drainage with elevated concentrations of Fe, Mn, Zn, As, Ni and Cd was observed due to buffering by carbonate dissolution. The contamination is spatially limited around abandoned mine sites, suggesting that metal(oid)s are sequestered in secondary phases that form under near-neutral and oxidizing conditions. However, the analysis of seasonal variations in trace metal concentrations showed that the transport of metal contaminants in water is highly variable according to hydrological conditions. During low flow conditions, trace metals are likely to be rapidly sequestered in Fe-oxyhydroxides and carbonate minerals in the karst aquifer and the river sediments, while low or no surface runoff in intermittent rivers limits the transport of contaminants in the environment. On the other hand, significant amounts of metal(loid)s can be transported under high flow conditions, primarily in dissolved form. Dissolved metal(loid) concentrations in groundwater remained elevated despite dilution by uncontaminated water, likely as a result of the increased leaching of mine wastes and the flushing of contaminated waters from mine workings. This work shows that groundwater is the main source of contamination to the environment and highlights the need to better understand the fate of trace metals in karst water systems.

ASSESSMENT OF ROCK SLOPE STABILITY IN A HUMID TROPICAL REGION: CASE STUDY OF A COAL MINE IN SOUTH KALIMANTAN, INDONESIA

PT.X, a coal mining company in South Kalimantan, Indonesia, plans to use the highwall mining method to excavate marginal reserves on the final slope to maintain production. However, the stability of the slope and determination of the highwall mining dimensions are major concerns due to unfavourable rock mass conditions caused by intensive weathering and tectonics. This paper aims to evaluate the feasibility of highwall mining in the study area using empirical, analytical and numerical methods. The innovation of this research is the integration of these methods, which include rock mass classification, analytical calculation of load and rock support strength, 2D and 3D numerical modelling, and estimation of recovered coal from the highwall design. The initial condition assessment using rock mass classification and analytics calculation of the mining geometry model determined mine openings and pillar dimensions. Numerical modelling re-evaluated the geometry models to obtain an optimal design. The suggested optimal thickness, mine opening, web pillars, and barrier pillars are 3.20, 3.00, 3.50, and 4.00 m, respectively, with four web pillars in one panel at Seam-C and 2.50, 3.00, 3.50, and 4.00 m with four web pillars in one panel at Seam-D. The recovery of coal for Seam-C and Seam-D is estimated to be 40.54%. Deformation was found to have the closest relationship with the dimensions of the mine opening, and the safety factor is most sensitive to changes in the depth of the mine opening. This study provides a reference for future highwall mining in Indonesia and other regions with similar conditions.

The impact of mining on the environment in Morocco

The mining sector is one of the pillars of economic growth, although it still has a negative impact on the environment. Mines have a significant impact on the environment in Morocco, both ecologically and socially. Mining as a source of income and economic development also has crucial consequences. In environmental terms. The opening of mines often leads to the destruction of local ecosystems. From this, deforestation, biodiversity loss and habitat fragmentation are frequent consequences of mining. In addition, mineral extraction can result in air, water and soil pollution due to the use of toxic chemicals and the release of fine particles. This has disastrous effects on water quality, the health of local populations and aquatic ecosystems. Mines also have significant social impacts. Local communities may be displaced from their ancestral lands, losing their livelihoods and their connection to their natural environment. Mine workers may be exposed to hazardous working conditions and high health risks. The Moroccan government has taken measures to mitigate the environmental impacts of mines, such as adopting stricter environmental regulations and promoting more sustainable mining practices.

Assessing the feasibility of underground space in mines and mine openings for radioactive waste disposal

Assessing the feasibility of underground space in mines and mine openings for radioactive waste disposal

Numerical Analysis of Groundwater Effects on the Stability of an Abandoned Shallow Underground Coal Mine

This work systematically quantifies groundwater’s effect on the roof stability of underground openings in shallow coal mines and indirectly assesses the potential for sinkhole formation. A specific stratigraphy was analyzed where the opening instability can lead to sinkhole formation, given the geological conditions, the overburden stratigraphy, and the depth of the openings. The groundwater recharge was investigated as an individual rainfall infiltration (short-term) and as groundwater dynamics (long-term), representing the accumulation of infiltrated rainwater with time. In the latter case, two approaches were employed for the porewater pressure calculation: (a) phreatic line with hydrostatic conditions and (b) steady-state flow based on constant groundwater head on the vertical boundaries at the model’s edges. The safety analysis was based on a simplified statics model relating the stability to the bending of the roof, and numerical analysis was employed for the stress analysis. The short-term safety remained unaffected as rainfall water accumulated on the aquitard to form perched water. The long-term safety deteriorated due to the increase of the tensile stresses in the roof of the underground openings with the rise of the groundwater table. The phreatic line approach is the most conservative, resulting in lower safety than steady-state flow.

Methodology for the estimation of mining face stresses using rock core diametrical deformation

In-situ stress measurements usually take place away from the underground mine work areas to capture the pre-mining stress tensor. However, mining face stresses around drifts, ramps, and stopes in underground mines are quite different from pre-mining stresses due to the excavations created by mining activities and the presence of geological structures. Therefore, investigating the development of an effective and practical method to estimate mining-induced stresses near a mining face should prove useful in practice. This study presents a simple and practical methodology based on rock core deformations for determining mining-induced stresses near underground mine openings, such as drifts and crosscuts where the near-field stresses in the sidewalls, the back, and the face could be of concern to the stability of the opening. The analytical solution developed in this paper can be used to determine the major and minor principal stresses near the mine opening in a plane perpendicular to the borehole axis and parallel to the free mining face. The analytical solution has been validated with published test results of laboratory experiments on rock cores extracted while subjected to uniaxial compression. It is shown that the results presented by the proposed method agree well with the applied stresses measured in laboratory experiments.

Novel Hybrid MPSI–MARA Decision-Making Model for Support System Selection in an Underground Mine

An underground mine is a very complex production system within the mining industry. Building up the underground mine development system is closely related to the installation of support needed to provide the stability of mine openings. The selection of the type of support system is recognized as a very hard problem and multi-criteria decision making can be a very useful tool to solve it. In this paper we developed a methodology that helps mining engineers to select the appropriate support system with respect to geological conditions and technological requirements. Accordingly, we present a novel hybrid model that integrates the two following decision-making components. First, this study suggests a new approach for calculating the weights of criteria in an objective way named the Modified Preference Selection Index (MPSI) method. Second, the Magnitude of the Area for the Ranking of Alternatives (MARA) method is proposed as a novel multi-criteria decision-making technique for establishing the final rank of alternatives. The model is tested on a hypothetical example. Comparative analysis confirms that the new proposed MPSI–MARA model is a very useful and effective tool for solving different MCDM problems.

TECHNICAL DESIGN OF MINE DRAINAGE SYSTEM IN LIMESTONE MINING AT UP. PARNO, KARANGASEM VILLAGE, PONJONG DISTRICT, GUNUNGKIDUL DISTRICT, REGION YOGYAKARTA SPECIAL

UP. Parno is a limestone mining company operating in Karangasem Village, Ponjong District, Gunungkidul Regency. UP. Parno has an IUP with an area of 5.7 hectares by implementing an open mining system (surface mining) with the quarry method. Surface mining affects the surface due to climate. When it rains, the falling rainwater can pool in the mining area and around the lower mining openings. If it is dry, no rainwater enters the mining area. Thus, an adequate mine drainage system design is needed. Water discharge is the main thing to determine a good mine drainage system design. Based on the results of the calculation of rainfall data from 2011 to 2020, it is known that the planned rainfall is 101.70 mm/day, and the rainfall intensity is 43.77 mm/hour with a five-year return period of rain. The purpose of making an open channel is to drain rainwater that enters the mining area and drain runoff so that the mine road does not stagnate. The designed open channel has dimensions of b = 1.50 m; B = 1.00 m; d = 0.60 m; h = 0.50 m; a = 0.60 m. Culverts function to drain water from open channels that cut off haul roads. The culverts required are made of smooth cement surface, with a diameter of 0.35 m. The water flowing by the open channel will go to the settling pond to be purified first before flowing into the river around the mining area. The settling pond is designed to consist of three compartments with an area of 264 m2 each and 666 m3 volume. Dredging of sediment in settling ponds must be carried out every 10 months and 13 days.