Mineral Processing
I. Kursun Unver; M. Terzi
Abstract
Today coal is among the most important energy sources. In order to meet the world's energy demands, low-calorie lignite with a high ash content is generally used in the large capacity coal-fired thermal power plants. As a result of coal firing, wastes such as fly ash, slag, and flue gas are also produced. ...
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Today coal is among the most important energy sources. In order to meet the world's energy demands, low-calorie lignite with a high ash content is generally used in the large capacity coal-fired thermal power plants. As a result of coal firing, wastes such as fly ash, slag, and flue gas are also produced. Subsequently, toxic trace elements within coal are transferred to wastes such as slag, fly ash, and flue gases. Large amounts of these, which are usually stored in collection ponds or stockpiles, are problematic in terms of environment. Although coal fly ash (CFA) has been utilized in construction and several other industries for decades, its current ratio of utilization is still quite limited. As an important fact, CFA also contains many valuable metals including germanium (Ge), gallium (Ga), vanadium (V), titanium (Ti), and aluminum (Al). In addtion, coal and CFA can be regarded as alternative sources of radioactive elements. Therefore, they also have a great potential in terms of the precious metals and trace elements they contain. In this study, the present literature on the distribution of trace elements in coal and coal ash during firing and ore preparation processes and their recovery possibilities with mineral processing practices are reviewed. While many research works on the subject clearly indicate that the large amounts of the ashes produced from firing of coal could be problematic in terms of environment, many studies and practices also show that coal combustion products also have a great potential in terms of the precious metals and trace elements.
Exploitation
S. Soltani-Mohammadi; A. Soltani; B. Sohrabian
Abstract
Due to the nature of the geological and mining activities, different input parameters in the grade estimation and mineral resource evaluation are always tainted with uncertainties. It is possible to investigate the uncertainties related to the measurements and parameters of the variogram model using ...
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Due to the nature of the geological and mining activities, different input parameters in the grade estimation and mineral resource evaluation are always tainted with uncertainties. It is possible to investigate the uncertainties related to the measurements and parameters of the variogram model using the fuzzy kriging method instead of the kriging method. The fuzzy kriging theory has already been the subject of relatively various research studies but the main weak point in such studies is that the results of the fuzzy estimations are not used in decision-making and planning. A very common, but key, tool of decision-making for mining engineers is the tonnage-average grade models. Under conditions where measurements or/and variogram model parameters are tainted with uncertainties, the tonnage-average grade model will be uncertain as well. Therefore, it is necessary to use the fuzzy tonnage-grade model instead of the crisp ones, and the next analysis steps and decision-makings are done accordingly. In this paper, the computational principles of the fuzzy tonnage-average grade curve and a case study regarding its usage are presented.
F. Abbasi; M.H. Khosravi; A. Jafari; Ali Bashari; B. Alipenhani
Abstract
The instability of the roof and walls of the tunnels excavated in coal mines has always attracted the attention of the miners and experts in this field. In this work, the instability of the main tunnels of the mechanized Parvadeh coal mine in Tabas, Iran, at the intersection with coal seam is studied. ...
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The instability of the roof and walls of the tunnels excavated in coal mines has always attracted the attention of the miners and experts in this field. In this work, the instability of the main tunnels of the mechanized Parvadeh coal mine in Tabas, Iran, at the intersection with coal seam is studied. The main tunnels of this mine show significant horizontal displacements due to the complex ground conditions and great depth. The behavior of the rock mass surrounding the tunnel is investigated using various experimental methods, and according to the results obtained, the surrounding rock mass has squeezing conditions. In order to analyze the stability of the main tunnels, a series of 2D and 3D numerical modelings are performed using the FLAC2&3D finite difference software, and the results obtained are compared with the actual displacement values recorded in the walls of the main tunnels of the mine. The analysis results show that the tunnels under study are unstable with a steel frame support, and therefore, the use of different support systems for the stabilization is investigated. The results of modeling different types of support systems show that the use of shotcrete instead of galvanized sheet (as strut) does not have a significant effect on the reduced displacements. Also although the installation of steel sets is very effective in preventing the displacement of the walls, due to the swelling problems in the tunnel bottom and the placement of the conveyor and haulage rail, it cannot be used in practice. Finally, the use of truss bolt has yielded good results, and it can be proposed as a new support system in these tunnels. In addition, the modeling results show that in case the coal seam is higher than the tunnel foot, less displacement will occur in the tunnel walls compared to the other cases. In other words, changing the tunnel level in the future excavations can help reduce the displacements.
Serhii Hryhorovych Nehrii; Tetiana Oleksandrivna Nehrii; Oksana Viktorivna Zolotarova; Valentyn Anatolyovich Glyva; Andrii Mykolaiovych Surzhenko; Oksana Mykolaivna Tykhenko; Nataliia Burdeina
Abstract
The studies of risk factors on which the safety of miners depends are relevant. These factors include temperature and air velocity within roadways, relative air humidity, dust, noise and vibration, lighting, clutter, limited working space, the difficulty of work, and the collapse of roof rocks. Their ...
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The studies of risk factors on which the safety of miners depends are relevant. These factors include temperature and air velocity within roadways, relative air humidity, dust, noise and vibration, lighting, clutter, limited working space, the difficulty of work, and the collapse of roof rocks. Their greatest concentration is in the technological zones of longwalls, so it is important to determine the priority of taking into account the risk factors in certain zones for planning measures for labor protection in underground coal mining. Therefore, a matrix of priority of risk factors for technological zone longwalls is proposed. The matrix is based on a survey of experienced and well-informed scientists and engineers of coal mines (experts). Fifty experts are involved in the survey.The matrix assesses the priority of risk factors, and considers the technological zones of the longwalls for the planning labor protection measures. The zones of operation of the excavation machines and the end-sections of longwalls are defined as the most safety-critical. Less safety-critical, but also dangerous, are the zones of protection means and the zones of connection of the longwalls with the roadways. The level of a certain risk factor is determined for each zone. The highest priority should be given to the collapse of roofs, dust, clutter of the working space, and the severity of the miners' work. For each risk factor included in the matrix, the technical and organizational measures for labor protection are proposed to reduce the level of injuries for miners.
M. R. Samadzadeh Yazdi; M. Abdollahi; S. M. Mousavi; A. Khodadadi Darban
Abstract
Although bioleaching of chalcopyrite by thermophilic microorganisms enhances the rate of copper recovery, a high temperature accelerates iron precipitation as jarosite, which can bring many operational problems in the industrial processes. In this research work, the bioleaching of chalcopyrite concentrate ...
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Although bioleaching of chalcopyrite by thermophilic microorganisms enhances the rate of copper recovery, a high temperature accelerates iron precipitation as jarosite, which can bring many operational problems in the industrial processes. In this research work, the bioleaching of chalcopyrite concentrate by the thermophilic Acidianus brierleyi was studied, and the microbial growth, copper dissolution, iron oxidation, and jarosite precipitation were monitored in different initial pH (pHi) values. Bacterial growth was greatly affected by pHi. While the bacterial growth was delayed for 11 days with a pHi value of 0.8, this delay was reduced to nearly one day for a pHi value of 1.2. Two stages of copper recovery were observed during all the tests. A high pHi value caused a fast bacterial growth in the first stage and severe jarosite precipitation in the later days causing a sharp decline in the bacterial population and copper leaching rate. The copper recoveries after 11 days were 25%, 78%, 84%, 70%, 56%, and 39% for the pHi values of 0.8, 1.0, 1.2, 1.3, 1.5, and 1.7, respectively. Sulfur and jarosite were the main residues of the bioleaching tests. It was revealed that the drastic effect of jarosite precipitation on the microbial growth and copper recovery was mainly caused by the ferric iron depletion from solution rather than passivation of the chalcopyrite surface. A slow precipitation of crystalline jarosite did not cause a passive chalcopyrite surface. The mechanisms of chalcopyrite bioleaching were discussed.
Patrick MUHIZI
Abstract
Excessive amounts of fluoride present in underground water sources are a major health concern worldwide. This study presents a new way to address the global health issue of high fluoride concentrations in groundwater using the abundantly available and cost-effective adsorbent material activated kaolinite ...
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Excessive amounts of fluoride present in underground water sources are a major health concern worldwide. This study presents a new way to address the global health issue of high fluoride concentrations in groundwater using the abundantly available and cost-effective adsorbent material activated kaolinite clay “WR@KN”. The physical and chemical activation methods are employed to enhance its adsorption capacity. The optimum conditions for fluoride removal are determined through batch adsorption experiments, with a maximum adsorption capacity of 0.745 mg/g at pH 6, a particle size of 10 µm, a mixing speed of 210 rpm, a temperature of 24 °C, an initial fluoride concentration of 5.5 mg/L, a dose of 0.7 g activated WR@KN, and a contact period of 240 minutes. WR@KN successfully removes fluoride ions from 5.5 to 0.28 mg/L. The Langmuir isotherm model is found to be the most suitable for describing the adsorption behavior of fluoride on the WR@KN surface with an R2 of 0.99984. The adsorption kinetic modeling shows that the pseudo-second-order model is the best fit with 0.754 mg/g, indicating that the fluoride adsorption process is chemisorption. The exothermic nature of the fluoride adsorption process is confirmed by a negative value of ΔH° (-77.08). The regenerated WR@KN adsorbent could remove fluoride effectively for the first four cycles but its performance deteriorated in the subsequent cycles. Increasing the ionic strength enhances the fluoride removal efficiency. Overall, the results suggest that the WR@KN adsorbent can be a promising material for cost-effective fluoride removal from groundwater.
Exploitation
M. Mohseni; M. Ataei; R. Khaloo Kakaie
Abstract
Production planning in mineral exploitation should be undertaken to maximize exploited ore at a minimum unplanned dilution. Unplanned dilution reduction is among the ways to enhance the quality of products, and hence, reduce the associated costs, resulting in a higher profit. In this way, firstly, all ...
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Production planning in mineral exploitation should be undertaken to maximize exploited ore at a minimum unplanned dilution. Unplanned dilution reduction is among the ways to enhance the quality of products, and hence, reduce the associated costs, resulting in a higher profit. In this way, firstly, all the parameters contributing to unplanned dilution in underground stopes and specifically the cut-and-fill stoping method are identified. Secondly, the parameters are weighed using the fuzzy-Delphi analytical hierarchy process. Thirdly, the most effective parameters are selected among the pool of effective parameters. Finally, in order to present a novel classification system for an unplanned dilution assessment, a new index called stope unplanned dilution index (SUDI) is introduced. SUDI represents the extent to which a cut-and-fill stope is susceptible to unplanned dilution. That is, having the value of this index, one may classify the cut-and-fill stopes into five groups according to robustness versus unplanned dilution: very strong, strong, moderate, weak, and very weak. SUDI is applied to10 stopes in different parts of Venarch Manganese Mines (Qom, Iran). In this way, a semi-automatic cavity monitoring system is implemented in the stopes. The regression analysis method shows that there is a relationship between SUDI and the actual unplanned dilution in equivalent linear overbreak/slough with a correlation coefficient (R2 = 0.8957).
Mineral Processing
Sahil Thakur; Ravi Kumar Sharma
Abstract
Slope stability is critical for infrastructure safety, particularly in seismically active regions. This work evaluates the stability of a slope along the Baroti-Reyur road in Himachal Pradesh, located in Zone 5, using a novel combination of Limit Equilibrium Methods (LEMs) and Finite Element Methods ...
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Slope stability is critical for infrastructure safety, particularly in seismically active regions. This work evaluates the stability of a slope along the Baroti-Reyur road in Himachal Pradesh, located in Zone 5, using a novel combination of Limit Equilibrium Methods (LEMs) and Finite Element Methods (FEMs). The analysis examines natural slope conditions and the impact of sustainable mitigation measures, including retaining structures and bioengineering techniques, under the static and dynamic conditions. The soil model incorporated a modulus of elasticity (E) of 90,000 kN/m², and a poisson's ratio (v) of 0.3 to reflect realistic slope-soil-structure interactions. Retaining structures such as gravity, cantilever, and gabion walls (4 m, 6 m, and 5 m high) were constructed using M30 RCC and Fe500 steel. Bioengineering measures featured deep-rooted grasses like Vetiver and Broom grass to improve soil cohesion (c), shrubs like Lantana camara for surface stability, and trees like Albizia lebbeck to reinforce deeper soil layers. These vegetation-based interventions enhanced slope resilience, while promoting ecological restoration. Theoretical LEM analysis revealed marginal stability, with static FOS values of 1.1 and pseudo-static FOS of 1.05. GEO5 pseudo-static analysis indicated critically low FOS value of 0.88 for dynamic saturated conditions, improving to 2.01 with retaining structures. FEM analysis using PLAXIS 2D provided more detailed insights, capturing complex soil-structure interactions with a static FOS of 1.028 and dynamic FOS of 0.994. By combining FEM with sustainable mitigation strategies, this work offers a framework for resilient slope stabilization, ensuring safety, while promoting environmental sustainability in seismically active regions.
Exploitation
F. Soltani; P. Moarefvand; F. Alinia; P. Afzal
Abstract
The traditional approaches of modeling and estimation of highly skewed deposits have led to incorrect evaluations, creating challenges and risks in resource management. The low concentration of the rare earth element (REE) deposits, on one hand, and their strategic importance, on the other, enhances ...
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The traditional approaches of modeling and estimation of highly skewed deposits have led to incorrect evaluations, creating challenges and risks in resource management. The low concentration of the rare earth element (REE) deposits, on one hand, and their strategic importance, on the other, enhances the necessity of multivariate modeling of these deposits. The wide variations of the grades and their relation with different rock units increase the complexities of the modeling of REEs. In this work, the Gazestan Magnetite-Apatite deposit was investigated and modeled using the statistical and geostatistical methods. Light and heavy REEs in apatite minerals are concentrated in the form of fine monazite inclusions. Using 908 assayed samples, 64 elements including light and heavy REEs from drill cores were analyzed. By performing the necessary pre-processing and stepwise factor analysis, and taking into account the threshold of 0.6 in six stages, a mineralization factor including phosphorus with the highest correlation was obtained. Then using a concentration-number fractal analysis on the mineralization factor, REEs were investigated in various rock units such as magnetite-apatite units. Next, using the sequential Gaussian simulation, the distribution of light, heavy, and total REEs and the mineralization factor in various realizations were obtained. Finally, based on the realizations, the analysis of uncertainty in the deposit was performed. All multivariate studies confirm the spatial structure analysis, simulation and analysis of rock units, and relationship of phosphorus with mineralization.
Rock Mechanics
Sahrul Poalahi Salu; Bima Bima
Abstract
Expansion of mining pit is associated with an increased risk of slope instability and high costs. This is because changes in geometry of the mine slope significantly affect slope stability, alter the stripping ratio, and potentially threaten the continuity of mining operations. Therefore, this research ...
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Expansion of mining pit is associated with an increased risk of slope instability and high costs. This is because changes in geometry of the mine slope significantly affect slope stability, alter the stripping ratio, and potentially threaten the continuity of mining operations. Therefore, this research work aimed to investigate the impact of changes in geometry of mining pit on slope stability to provide insight into safety, economic assurances, and ensure the sustainability of mining operations. This research work was applied by the 2D numerical modeling method using the Slide Software V. 6.0 Rocscience to analyze geometry of mining pit and impact on slope safety factors. The investigation was conducted at Pit Block A of Pt. Hikari Jeindo, managing nickel mining activities in the Langgikima District, North Konawe, Regency, Southeast Sulawesi Province, Indonesia. The results showed that the modeling method successfully showed changes in slope geometry, ensuring safe and economically viable slope safety factors. However, to obtain a more comprehensive understanding of slope stability conditions, a 3D numerical modeling method is required to capture the area affected by expansion of mining pit.
V. Sarfarazi; K. Asgari
Abstract
In this investigation, the impact of confining pressure on the tensile strength obtained by point load test (PLT) is examined by particle flow code in two dimensions. In this regard, at first, a numerical model is calibrated using the Brazilian experimental test results. The tensile strength of the model ...
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In this investigation, the impact of confining pressure on the tensile strength obtained by point load test (PLT) is examined by particle flow code in two dimensions. In this regard, at first, a numerical model is calibrated using the Brazilian experimental test results. The tensile strength of the model material is equal to 2.5 MPa. Secondly, PLT is performed on the numerical models with dimension of 15 cm × 50 cm. The rectangular models are tested by PLT under the presence of the confining pressure. The loading rate is 0.001 mm/min, confining that the pressure is changed with the 13 different values of 0 MPa, 0.002 MPa, 1MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3MPa, 3.5 MPa, 4 MPa, 5MPa, 6 MPa, 9 MPa, and 11 MPa. The results obtained show that the vertical tensile crack develops through the model under a low confining pressure, while several shear bands are developed in the models under a high confining pressure. The number of shear cracks is augmented by augmenting the confining pressure. Is(50) is the augment by augmenting the confining pressure. Also a new criterion is rendered in order to determine Is(50) based on the confining pressure.
Exploration
Vivek Sharma; Ravi Kumar Sharma; Pardeep Kumar
Abstract
In the present work, the empirical correlations between standard penetration test (SPT) N-values versus shear modulus (Gmax), and Peak Ground Acceleration (PGA) amplifications for sub-Himalayan district-Hamirpur, Himachal Pradesh (India) consisting of highly variable soil/rock strata at different ...
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In the present work, the empirical correlations between standard penetration test (SPT) N-values versus shear modulus (Gmax), and Peak Ground Acceleration (PGA) amplifications for sub-Himalayan district-Hamirpur, Himachal Pradesh (India) consisting of highly variable soil/rock strata at different depths and across the terrain are evaluated. In the first stage, the N values obtained from SPTs are conducted in the field at 184 locations covering the studied area. The shear wave velocity for each soil profile of each borehole is calculated using the best available correlation in the literature. Further, the seismic response parameters are evaluated for these values using the ProShake software. Finally, the empirical relationships between maximum shear modulus and SPT value for different soil types are determined along with the ground motion amplifications. The amplification factor for Bhoranj sub-division varies from 1.40 to 2.60 and from 1.28 to 2.30, 1.20 to 2.10, 1.22 to 1.85, and 1.22 to 1.70 for Barsar, Nadaun, Hamirpur, and Sujanpur, respectively. The studied area consists of variable soil strata including clay, silt, sand, conglomerate, sandstone, and mixture thereof. The correlation between shear modulus and N value is coherent with already reported correlations for regular soils. The amplification factor reported for the sites plays an important role in planning infrastructure in the region. The correlations between maximum shear modulus (Gmax) and SPT value for hilly terrain comprising of highly complex geological formations such as mixed soil and fractured rocks presented in the study are not available in the research work carried out earlier.
A. Zolfaghari; N. Barzegar; M. Amini
Abstract
The gypsum mineralization occurred in the form of Satin Spar and Selenite in the south and southwest of the Fars province in the folded Zagros zone. In this region, Satin Spar mineralization has been formed as stratiform between the red marl and siltstone units of Late Miocene–Pliocene in Agha ...
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The gypsum mineralization occurred in the form of Satin Spar and Selenite in the south and southwest of the Fars province in the folded Zagros zone. In this region, Satin Spar mineralization has been formed as stratiform between the red marl and siltstone units of Late Miocene–Pliocene in Agha Jari, Bakhtiari, and the Gachsaran formations. The reserves of Satin Spar in this area are at least 200,000 tons. Satin Spar due to its chatoyancy, has been able to distinguish itself from gypsum. This beautiful light phenomenon (chatoyancy) results from the regular and parallel arrangement of the Satin Spar fibers. The mineral was first identified by its physical properties, and then by the X-ray diffraction analysis. They were also examined by scanning electron microscopy for its structure and also the structure of fiber crystals and their optical properties. In order to examine the polishing condition of Satin Spar, several samples of this gemstone were also selected for fantasy and Cabochon cut. For the first time in Iran, the exploration of Satin Spar gemstone in the Fars region can be a model for its discovery in the other evaporative formations in the country.
Environment
Sphiwe Emmanuel EMMANUEL Mhlongo; Francis Amphose Dacosta; Armstrong Kadyamatimba; George O Akintola
Abstract
South Africa has 6100 documented abandoned mines. The government is responsible for the management and rehabilitation of these mines to address their environmental problems, physical hazards, and socio-economic issues. In general, rehabilitating abandoned mines involves making a series of critical decisions ...
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South Africa has 6100 documented abandoned mines. The government is responsible for the management and rehabilitation of these mines to address their environmental problems, physical hazards, and socio-economic issues. In general, rehabilitating abandoned mines involves making a series of critical decisions about the strategies to be implemented in rehabilitating the major features of these mines. This paper presents an expert system developed to aid in selecting appropriate strategies for rehabilitating abandoned mines in South Africa. This system is known as the Expert System for Selection of Strategies for Rehabilitation of Abandoned Mines (ES-SRSA). The ES-Builder (Version 3.0, McGoo software) was used to design the knowledge and rule-based components of the expert system. The rules of the expert systems were developed based on the documented knowledge of the problems of abandoned mines in South Africa and the information gathered by the researcher through visits to selected abandoned mine sites in the country. The ES-SRSA provides 45 recommendations of suitable strategies for dealing with the different problems of features such as underground entries, mine waste, surface mine excavations, silos and orebins, and other features like dilapidated buildings/infrastructure. Most of the rules of this expert system encourage the repurposing and reuse of these mine features to improve the social and economic status of the host communities. The use of this expert system has the potential of contributing to the reduction of the risks of implementation of ineffective strategies for the rehabilitation of abandoned mines in a country like South Africa.
Environment
Kushai Caleb Aluwong; Mohd Hazizan bin Mohd Hashim; Suhaina Ishmail
Abstract
In the past, assessing water quality has typically involved labor-intensive and costly processes such as laboratory analysis and manual sampling, which do not provide real-time data. In addition to tasting bad, drinking acidic water on a regular basis can result in acid reflux and recurrent heartburn ...
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In the past, assessing water quality has typically involved labor-intensive and costly processes such as laboratory analysis and manual sampling, which do not provide real-time data. In addition to tasting bad, drinking acidic water on a regular basis can result in acid reflux and recurrent heartburn while high total dissolved solids water can cause kidney stones, especially when the hard water content is more than 500ppm. With growing concerns about water quality, there is a need for continuous monitoring of pH and TDS levels in surface and groundwater sources. To address this, a cutting-edge wireless sensor system leveraging on Internet of Things (IoT) technology has been developed. This system incorporates top-notch pH and TDS sensors known for their accuracy, durability, and environmental compatibility. Integrated with microcontrollers featuring wireless communication capabilities, these sensors enable seamless data transmission to a central server through IoT protocols like cellular networks. The collected data is processed and calibrated to ensure reliability and precision. The IoT platform connected to the central server manages device connectivity, data storage, and analysis, making real-time data accessible via user-friendly web or mobile applications with interactive graphs and dashboards. Power-saving features are implemented to optimize battery life in remote and off-grid locations, and weather-resistant enclosures protect the sensor nodes from harsh environmental conditions. By deploying this wireless-based sensor system, users can gain valuable real-time insights into water quality in surface and groundwater monitoring locations.
R. N. Singh; A.S. Atkins; A.G. Pathan
Abstract
Ground water and surface water create a range of problems in lignite mining utilizing surface mining methods. In order to create a safe and economic mining environment, it is essential to carry out mining after dewatering the rock mass surrounding the lignite mines by advance dewatering techniques. This ...
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Ground water and surface water create a range of problems in lignite mining utilizing surface mining methods. In order to create a safe and economic mining environment, it is essential to carry out mining after dewatering the rock mass surrounding the lignite mines by advance dewatering techniques. This paper briefly describes the ground water regimes including pressure gradients associated with various lignite deposits together with the practical examples of some important lignite deposits in the world. An effective method of controlling ground water in multi-aquifer environment in lignite deposits is to carry out rock mass dewatering using borehole pumps. This approach will help reducing the inflow rates of ground water to the mining excavation and also increase the effective strength of the overburden strata, thus, increasing the slope stability of the mining excavations. The main theme of this paper is to present a case history analysis of Thar lignite deposit in Sindh, Pakistan which has lignite reserves of some 193 billion tonnes. The paper presents a proposed method of dewatering the Thar prospect together with an assessment of the quality of aquifer water which can be used to improve the quality of life of people inhabiting in the Thar Desert area of Sindh, Pakistan. Water samples from three aquifers were collected from nine different locations and were analyzed in the laboratory for evaluating their physical and chemical characteristics. The test results indicated that the aquifer water can be classified as (sodium+ potassium) – chloride type water with a TDS range of 1000 to 20,000 mg/L. Consequently, this ground water is classified as brackish (saline water) requiring treatment before it can be utilised for domestic or industrial consumptions. It should be noted that this ground water does not contain heavy metals and toxic metals including arsenic, mercury and lead or cyanide. However, results indicate that groundwater from a few locations contained traces of silver (<4oppb)Owithozinc0<0.1ppm.
Rock Mechanics
Mahdi Bajolvand; Ahmad Ramezanzadeh; Amin Hekmatnejad; Mohammad Mehrad; Shadfar Davoodi; Mohammad Teimuri; Mohammad Reza Hajsaeedi; Mahya Safari
Abstract
Bit wear is one of the fundamental challenges affecting the performance and cost of drilling operations in oil, gas, and geothermal wells. Since identifying the factors influencing bit wear rate (BWR) is essential, and the ability to predict its variations during drilling operations is influenced by ...
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Bit wear is one of the fundamental challenges affecting the performance and cost of drilling operations in oil, gas, and geothermal wells. Since identifying the factors influencing bit wear rate (BWR) is essential, and the ability to predict its variations during drilling operations is influenced by environmental and operational factors, this study aims to develop an Adaptive Bit Wear Rate Predictor (ABWRP) algorithm for estimating the BWR during drilling operations for new wells. The structure of this algorithm consists of a data transmitter, data processor, deep learning-based bit wear rate estimator, and a bit wear updating module. To develop a model for the BWR estimation module, data from two wells in an oil field in southwest Iran were collected and analyzed, including petrophysical data, drilling data, and bit wear and run records. Both studied wells were drilled using PDC bits with a diameter of 8.5 inches. After preprocessing the data, the key factors affecting the bit wear rate were identified using the Wrapper method, including depth, confined compressive strength, maximum horizontal stress, bit wear percentage, weight on bit, bit rotational speed, and pump flow rate. Subsequently, seven machine learning (ML) and deep learning (DL) algorithms were used to develop the bit wear rate estimation module within the ABWRP algorithm. Among them, the convolutional neural network (CNN) model demonstrated the best performance, with Root Mean Square Error (RMSE) values of 0.0011 and 0.0017 and R-square (R²) values of 0.96 and 0.92 for the training and testing datasets, respectively. Therefore, the CNN model was selected as the most efficient model among the evaluated models. Finally, a simulation-based experiment was designed to evaluate the performance of the ABWRP algorithm. In this experiment, unseen data from one of the studied wells were used as data from a newly drilled well. The results demonstrated that the ABWRP algorithm could estimate final bit wear with a 14% error. Thus, the algorithm developed in this study can play a significant role in the design and planning of new wells, particularly in optimizing drilling parameters while considering bit wear effects.
M. Eftekhari; A. Baghbanan; H. Hashemolhosseini
Abstract
The cracked Brazilian disc (CBD) specimen is widely used in order to determine mode-I/II and mixed-mode fracture toughness of a rock medium. In this study, the stress intensity factor (SIF) on the crack-tip in this specimen is calculated for various geometrical crack conditions using the extended-finite ...
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The cracked Brazilian disc (CBD) specimen is widely used in order to determine mode-I/II and mixed-mode fracture toughness of a rock medium. In this study, the stress intensity factor (SIF) on the crack-tip in this specimen is calculated for various geometrical crack conditions using the extended-finite element method (X-FEM). This method is based upon the finite element method (FEM). In this method, the crack is modeled independently from the mesh. The results obtained show that the dimensionless SIFs for the pure modes I and II increase with increase in the crack length but the angle in which pure mode-II occurs decreases. For the mixed-mode loading, with increase in the crack angle, NI value decreases, while NII value increases to a maximum value and then decreases. The results obtained from the crack propagation examinations show that the crack angle has an important effect on the crack initiation angle. The crack initiation angle increases with increase in the crack angle. When the crack angle is zero, then the crack is propagated along its initial direction, whereas in the mixed-mode cases, the crack deviates from the initial direction, and propagates in a direction (approximately) parallel to the direction of maximum compressive load.
F. Razavi Rad; F. Mohammad Torab; A. Abdollahzadeh
Abstract
Considering the importance of Cd and U as pollutants of the environment, this study aims to predict the concentrations of these elements in a stream sediment from the Eshtehard region in Iran by means of a developed artificial neural network (ANN) model. The forward selection (FS) method is used to select ...
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Considering the importance of Cd and U as pollutants of the environment, this study aims to predict the concentrations of these elements in a stream sediment from the Eshtehard region in Iran by means of a developed artificial neural network (ANN) model. The forward selection (FS) method is used to select the input variables and develop hybrid models by ANN. From 45 input candidates, 13 and 14 variables are selected using the FS method for Cadmium and Uranium, respectively. Considering the correlation coefficient (R2) values, both the ANN and FS-ANN models are acceptable for estimation of the Cd and U concentrations. However, the FS-ANN model is superior because the R2 values for estimation of Cd and U by the FS-AAN model is higher than those for estimation of these elements by the ANN model. It is also shown that the FS-ANN model is preferred in estimating the Cd and U population due to reduction in the calculation time as a consequence of having less input variables.
Rock Mechanics
A. Akrami; M. Hosseini; H. Sodeifi
Abstract
Hydraulic fracturing is used in the oil industry in order to increase the index of production and processing in the wells whose efficiencies have been dropped due to a long-term harvest or the rocks around the wells are of low permeability. Since the hydraulic fracturing operation is costly, it is of ...
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Hydraulic fracturing is used in the oil industry in order to increase the index of production and processing in the wells whose efficiencies have been dropped due to a long-term harvest or the rocks around the wells are of low permeability. Since the hydraulic fracturing operation is costly, it is of special importance to the project managers to determine the pressure required for hydraulic fracturing and the suitable pump for this operation. The numerical modelings used in this work are aimed to investigate the fracture pressure in the carbonate rocks of Bangestan reservoir in Ahvaz, Iran, and to determine a relationship between the pressure required for fracturing and the confining pressure. In this work, unlike the other ones in this field, the developed numerical models had no initial crack or fracture, and the path of the crack and how the crack grows were studied without any pre-determination and presumption. The results obtained show that, in most cases, the crack starts from the central part of the sample, and is extended to its two ends. The crack extension direction was along the borehole axis inside the sample and perpendicular to the lateral stress. The numerical modeling results were well-consistent with the experimental ones, indicating that the pump capacity constraints in the laboratory could be overcome through numerical modelings.
Rock Mechanics
M. Lak; M. Fatehi Marji; A.R. Yarahamdi Bafghi; A. Abdollahipour
Abstract
The explosion process of explosives in a borehole applies a very high pressure on its surrounding rock media. This process can initiate and propagate rock fractures, and finally, may result in the rock fragmentation. Rock fragmentation is mainly caused by the propagation of inherent pre-existing fractures ...
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The explosion process of explosives in a borehole applies a very high pressure on its surrounding rock media. This process can initiate and propagate rock fractures, and finally, may result in the rock fragmentation. Rock fragmentation is mainly caused by the propagation of inherent pre-existing fractures of the rock mass and also from the extension of the newly formed cracks within the intact rock due to the explosion. In this work, the process of extension of blast-induced fractures in rock masses is simulated using the discrete element method. It should be noted that, in this work, fracture propagation from both the rock mass inherent fractures and newly induced cracks are considered. The rock mass inherent fractures are generated using the discrete fracture network technique. In order to provide the possibility of fracture extension in the intact rock blocks, they are divided into secondary blocks using the Voronoi tessellation technique. When the modeling is completed, the fracture extension processes in the radial and longitudinal sections of a borehole are specified. Then a blast hole in an assumed rock slope is modeled and the effect of pre-splitting at the back of the blast hole (controlled blasting) on the fracture extension process in the blast area is investigated as an application of the proposed approach. The modeling results obtained show that the deployed procedure is capable of modeling the explosion process and different fracture propagations and fragmentation processes in the rock masses such as controlled blasting.
F. Hadadi; B. Jodeiri Shokri; M. Zare Naghadehi; F. Doulati Ardejani
Abstract
In this paper, we investigate a probabilistic approach in order to predict how acid mine drainage is generated within coal waste particles in NE Iran. For this, a database is built based on the previous studies that have investigated the pyrite oxidation process within the oldest abandoned pile during ...
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In this paper, we investigate a probabilistic approach in order to predict how acid mine drainage is generated within coal waste particles in NE Iran. For this, a database is built based on the previous studies that have investigated the pyrite oxidation process within the oldest abandoned pile during the last decade. According to the available data, the remaining pyrite fraction is considered as the output data, while the depth of the waste, concentration of bicarbonate, and oxygen fraction are the input parameters. Then the best probability distribution functions are determined on each one of the input parameters based on a Monte Carlo simulation. Also the best relationships between the input data and the output data are presented regarding the statistical regression analyses. Afterward, the best probability distribution functions of the input parameters are inserted into the linear statistical relationships to find the probability distribution function of the output data. The results obtained reveal that the values of the remaining pyrite fraction are between 0.764% and 1.811% at a probability level of 90%. Moreover, the sensitivity analysis carried out by applying the tornado diagram shows that the pile depth has, by far, the most critical factors affecting the pyrite remaining
M. Esmailzadeh; A. Imamalipour; F. Aliyari
Abstract
The main aim of mineral exploration is to discover the ore deposits. The mineral prospectivity mapping (MPM) methods by employing multi-criteria decision-making (MCDM) integrate the exploration layers. This research work combines the geological, alteration, and geochemical data in order to generate ...
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The main aim of mineral exploration is to discover the ore deposits. The mineral prospectivity mapping (MPM) methods by employing multi-criteria decision-making (MCDM) integrate the exploration layers. This research work combines the geological, alteration, and geochemical data in order to generate MPM in the Kighal-Bourmolk Cu-Mo porphyry deposit. The overlaying of rock units and fault layers was used to prepare the geological layer. The remote sensing and geological studies were employed in order to create an alteration layer. For generating the geo-chemistry layer, the stream sediment and lithogeochemical data were utilized. The lithogeochemistry layer was categorized into 9 ones including Cu, Mo, Bi, Te, the alteration indices (e.g. potassic, phyllic, and propylitic), and the geochemical zonality indices (e.g. Vz1 and Vz2). In addition, the stream sediment layer was categorized into 6 layers including Cu, Mo, Bi, Te, and the geochemical zonality indices (e.g. Vz1 and Vz2). By examination of the created layers, the consistency of the potential areas was verified by field surveys. Afterward, the weights were assigned to each layer considering the conceptual model of porphyry copper systems. Consequently, the layers were integrated by the fuzzy gamma operator technique, and the final MPM was generated. Regarding the generated MPM, 0.86% of the studied area shows a high potential porphyry mineralization, and these areas are proposed for the subsequent exploration drilling locations.
Vanshika Bhardwaj; Kanwarpreet Singh
Abstract
Natural hazards are naturally occurring phenomena that might lead to a negative impact on the environment and also on the life of living beings. These hazards are caused due to adverse conditions of weather and climate events, and also due to certain human activities that are harmful to the environment. ...
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Natural hazards are naturally occurring phenomena that might lead to a negative impact on the environment and also on the life of living beings. These hazards are caused due to adverse conditions of weather and climate events, and also due to certain human activities that are harmful to the environment. Natural hazards include tsunamis, earthquakes, volcanic activity, landslides, etc. Among these natural hazards, landslides are among the most common natural hazards resulting in loss of life and property each year, leading to socio-economic impact; thus to avoid such losses, a comprehensive study of landslides is required. Landslides generally occur in hill region with steep slopes, heavy precipitation, loose shear strength of soil or due to many human activities like afforestation or construction activities. To resolve the problem of landslides in a hilly region, much research is conducted annually, providing a predicted landslide susceptibility zonation (LSZ) mapping of the area of research. The predicted landslide susceptibility maps are verified based on the past landslide data, an area under the curve (AUC), and other methods to provide an accurate map for landslide susceptibility in any area. In this study,93 research articles are reviewed for analysis of LSZ, and various observations are made based on the recent trends followed by various researchers over the world over the past ten years. The study can be useful for many researchers to practice their research on landslide susceptibility zonation.
M. Babaei; M. Abedi; Gh. H. Norouzi; S. Kazem Alilou
Abstract
This work presents the application of a geostatistical-based modeling approach for building up electrical properties acquired from a geophysical electrical tomography survey deployed for the purpose of porphyry Cu exploration at the Takht-e-Gonbad deposit, in the central domain of Iran. Electrical data ...
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This work presents the application of a geostatistical-based modeling approach for building up electrical properties acquired from a geophysical electrical tomography survey deployed for the purpose of porphyry Cu exploration at the Takht-e-Gonbad deposit, in the central domain of Iran. Electrical data were inverted in 2D along several profiles across the main favorable zones of Cu-bearing mineralization to image electrical resistivity and chargeability properties. Upon tight spatial correlation of these geophysical properties and Cu mineralization (i.e. Cu grade), electrical models were constructed in 3D through geostatistical interpolation of 2D inverted data to provide insights into the geometry of probable ore mineralization. Anomalous geophysical zone that was coincident simultaneously with higher values of electrical chargeability and resistivity, was in accordance with the main body of high Cu grades generated from exploratory drillings. It reveals that the porphyry-type Cu mineralization system in this area has strong geophysical footprints controlled mainly by rock types and alterations. Note that these physical models supply valuable pieces of information for designing the layout of further exploratory drillings, constructing geological characteristics, separating non-mineralized form mineralized zones, and resource modeling.
