Journal of Mining and Environement
Volume:13 Issue: 4, Autumn 2022

This research work aims to critically analyze the efficacy of inexpensive and rapid 2D electrical resistivity tomography (2D ERT) survey for sub-surface geological delineation of granite deposits. The research work involves six ERT profiles using the Schlumberger protocol with an inner and outer electrode spacing of 5 m and 10 m, respectively. In addition, the unmanned aerial vehicle (UAV) survey is also performed to obtain the terrain information of the studied area. At the same time, a few boreholes are drilled to validate the 2D ERT interpretations. The 2D ERT survey reveals that strong resistivity contrast enables inverted resistivity imaging to characterize the deposit such as topsoil (100-800 Ωm), fracture granite (800-2300 Ωm), and solid granite (> 2300 Ωm). The results obtained from UAV, 2DERT, and borehole survey are further processed to estimate the bedrock to topsoil ratio to assess the feasibility of the deposit. The bedrock to topsoil ratio, estimated by 2D ERT and borehole, is 3.2 and 2.2, respectively. At the same time, the combined UAV, 2D ERT, and borehole survey calculates the bedrock volume 3.2 times to topsoil. Thus the research work allows us to conclude that 2D ERT is an inexpensive, viable, and efficient technique for sub-surface geological documentation, and helps select appropriate mining methods.

The GIS-multi-criteria decision analysis (MCDA) techniques are increasingly used in landslide susceptibility mapping for predicting the future hazards, land use planning, and hazard preparedness. Identification of landslide susceptible regions helps in making a strategic plan for future developmental activities in the landslide-prone areas. It enables the integration of different data layers with varying levels of uncertainty. In this work, GIS-MCDA is applied to landslide hazard zonation for the Kullu district in Himachal Pradesh, India. The current work aims to evaluate the performance of the analytical hierarchy process (AHP) for the development of a landslide hazard map. The geographical information system is used for the preparation of the database, analysis, modelling, and results. The ArcGIS 10.0 software is used to integrate the input layers by assigning appropriate weights. Six landslide causal factors are used, whereby the parameters are extracted from an associated spatial database. These factors are evaluated, and then the respective factor weight and class weight are assigned to each one of the associated factors. The developed landslide hazard map is categorized into three risk zones. The current work may be of great assistance to regional planners and decision-makers in deciding on the most suitable risk mitigation measures at the local level to prevent the potential losses and damages from landslides in the region.

Geological modeling is an important step for the evaluation of natural resources. One option is to use a common geo-statistical modeling method such as Indicator Kriging (IK). However, there are specific problems associated with IK, the worthiest of attention is an order relation violation. Alternatively, some studies propose to use the Inverse Distance Weighting (IDW) method. Though again, there are certain limitations associated with the IDW geo-domain modeling application. In fact, the current IDW methodology does not cover the subject of anisotropic geo-domain modeling; thus it is only applicable for the isotropic cases. Therefore, this work proposes a previously unused geo-domain modeling–Anisotropic IDW, which underlies the concept of indicator variogram, allowing one to consider the spatial correlation of the domains. The experimental part in this work includes the comparison of anisotropic IDW, IK, and traditional IDW over the synthetic case study, which imitates a highly anisotropic geological behavior, and a more complicated real case study over a vein-type gold deposit from Kazakhstan. The case studies’ results illustrate that the anisotropic IDW can model the geo-domains more accurately than IK and the traditional IDW.

The major factors affecting tunnel stability include the ground conditions, in-situ stresses, and project-related features. In this research work, critical strain, stress reduction factor (SRF), and capacity diagrams are used for tunnel stability analysis. For this purpose, eighteen tunnel sections are modelled using the FLAC2D software. The rock mass properties for the modelling are obtained using the RocLab software. The results obtained show that tunnel deformations in most cases are within the safety limit. Meanwhile, it is observed that the rock mass quality, tunnel size, and in-situ stresses contribute to the deformation. The resulting deformations also affect SRF. SRF depends on the in-situ stresses, rock mass quality, and excavation sequence. The capacity diagrams show that the liner experience stress-induced failures due to stress concentration at the tunnel corners. This study concludes that tunnel stability analysis must include an integrated approach that considers the rock quality, in-situ stress, excavation dimensions, and deformations.

In Sidi Chennane, Central Morocco, the cost of phosphate mining is often influenced by problems bound to the existence of sterile bodies called derangements. These bodies consisting of a waste rocky material affect the sedimentary phosphate series, and thus disturb the phosphate extraction process. In this work, we attempt to analyze and quantify the economic impact of these sterile bodies on the cost of phosphate mining in Sidi Chennane. The work is carried out through a prototype model prepared as a real mining trench, using data collected during our internships in the Sidi Chennane mining field. The results of this work show that the cost of removing derangements increases the cost of phosphate mining for the entire cycle of production, drilling, blasting, ripping, dozing, loading, and hauling. It is concluded, therefore, that the outcomes of this work are of great importance for obtaining an accurate understanding of phosphate mining when confronted derangements. This can be adapted to analyze and interpret such similar structures in phosphate mines around the world (e.g. Taïba phosphate mine in Senegal).

In this work, an attempt is made to fit and identify the most appropriate probability distribution(s) for the analysis of seventeen rock samples including diorite, gypsum, marble, basalt, sandstone, limestone, apatite, slate, dolomite, granite-II, schist, gneiss, amphibolite, hematitle, magnetite, Shale, and granite-I using laser-induced breakdown spectroscopy. The graphical assessment and visualization endorse that the rock dataset series are positively skewed. Therefore, Frechet, Weibull, log-logistic, log-normal, and generalized extreme value distributions are considered as candidate distributions, and the parameters of these distributions are estimated by maximum likelihood and Bayesian estimation methods. The goodness of fit test and model selection criteria such as the Kolmogorov-Smirnov test, Akaike Information Criterion, and Bayesian Information Criterion are used to quantify the accuracy of the predicted data using theoretical probability distributions. The results show that the Frechet, Weibull, and log-logistic distributions are the best-fitted probability distribution for rock dataset. Cluster analysis is also used to classify the selected rocks that share common characteristics, and it is observed that diorite and gypsum are placed in one cluster.  However, slate, dolomite, marble, basalt, sandstone, schist, granite-II, and gneiss rocks belong to different clusters. Similarly, limestone and apatite appeare in one cluster. Likewise, shale, granite-I, magnetite, amphibolite, and hematitle appeare in a different cluster. The current work demonstrate that coupling of laser-induced breakdown spectroscopy with suitable statistical tools can identify and classify the rocks very efficiently.

This research work provides a bearing capacity equation for a circular footing placed on dense sand overlying loose sand and subjected to vertical and inclined loading, utilizing the limit equilibrium followed by the projected area approach. For the parametric study, the variables include upper dense sand layer thickness ratio (0.5 to 2.00), friction angle of upper dense sand (41° to 45°) and lower loose sand layer (31° to 35°), and applied load inclination (0° to 30°). The highest and lowest increases in bearing capacity are reported for friction angle combinations of 45°–35° and 41°–31° for various thickness ratios, respectively. For load inclinations of 0°, 10°, 20°, and 30°, bearing capacity is reduced by 43.51%, 72.17%, 85.64%, and 22.62%, 48.56%, 62.17% for friction angles of upper dense and lower loose sand layer combinations of 45° and 35° and at a thickness ratio of 0.5 and 2.0. Considering finite element results, the average deviation of the bearing capacity derived from the suggested equation at surface footing is 7%, 5%, 22%, and 23% for 0°, 10°, 20°, and 30° load inclinations, respectively. The proposed bearing capacity equation yield results that are compared with the available literature, with average deviations of 62%, 50%, 36%, and 36% for load inclination values of 0°, 10°, 20°, and 30°, respectively.

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.

This paper presents the numerical analysis of square and circular skirted footings placed on different sands using the PLAXIS 3D software. The numerical analysis is done using the Mohr-coulomb (M-C) yield criteria. The size of the footings is considered as 100 mm for both the square and circular footings. The three different friction angles (Ø) of sand 36˚, 40˚, and 42˚ are used to study the effect of sand compactness. The depth of the skirt (h) varies from 0B to 2B (B is the width of the footing). The surface roughness between skirt-sand and footing-sand is considered partially rough and completely rough. The interface friction factor (δ) for a partially rough and fully rough interface is taken as 2/3Ø and Ø. All the tests are conducted by applying a prescribed displacement (s/B) of 20% of the footing size. The results obtained from the present work reveal that the inclusion of structural skirts with the footings appreciably increases the bearing capacity and reduces the settlement of the footing by increasing the skirt depth. The results obtained show that the skirted footing is found to be more effective in loose sand compared to dense sand in increasing the bearing capacity. The numerical analysis results are also verified with the experimental results available in the literature and multiple regression model. This work shows that the prediction of the accuracy of the results is quite good with the experimental results and the generated regression model.

In this work, we simulate the frequency-domain helicopter-borne electromagnetic (HEM) data over the two-dimensional (2D) and three-dimensional (3D) earth models. In order to achieve this aim, the vector Helmholtz equation is used to avoid the convergence problems in Maxwell’s equations, and the corresponding fields are divided into primary and secondary components. We use the finite difference method on a staggered grid to discretize the equations, which can be performed in two ways including the conventional and improved finite difference methods. The former is very complex in terms of programming, which causes errors. Furthermore, it requires different programming loops over each point of the grid, which increases the program’s running time. The latter is the improved finite difference method (IFDM), in which pre-made derivative matrices can be used. These pre-made derivative matrices can be incorporated into the derivative equations and convert them directly from the derivative form to the matrix form. After having the matrix form system of linear equations, Ax = b is solved by the quasi-minimal residual (QMR). IFDM does not have the complexities of the conventional method, and requires much less execution time to form a stiffness or coefficient matrix. Moreover, its programing process is simple. Our code uses parallel computing, which gives us the ability to calculate the fields for all transmitter positions at the same time, and because we use sparse matrices thorough the code memory space, requires to store the files is less than 100 MB compared with normal matrices that require more than 15 GB space in the same grid size. We implement IFDM to simulate the earth’s responses. In order to validate, we compare our results with various models including the 3D and 2D models, and anisotropic conductivity. The results show a good fit in comparison with the FDM solution of Newman and the appropriate fit integral equations solution of Avdeev that is because of the different solution methods.

Estimating the costs of mine reclamation is a significant part of mine closure projects. One approach to mine reclamation is planting mine areas. In this approach, the optimum selection of plant types is cosidered a multiple-criteria decision-making (MCDM) problem. Once proper plant species are identified, it is required to estminate planting costs through statistical analysis. This work aims to introduce an algorithm for optimal plant type selection and a reclamation cost estimation model for open-pit mines. To this end, the plant species compatible with the sorrounding areas of Sungun copper mine are identified and ranked using the PROMETHEE technique. In this analysis, the main criteria are local landscape, pest resistance, plant growth ability, availability, economic issues, soil protection, water storage ability, and pollution prevention. Among the six plant types, Maple trees have the highest score (4.34). After that, to develop the reclamation cost estimation model, the data (99 datasets) is collected from the Sungun copper mine, Sarcheshmeh copper mine, and Chadormaloo iron mine. The variables in the database include soil gradation by graders, slope trimming and topography by bulldozers, the ripping and softening of the compacted soil, chemical fertilizers, natural fertilizers and mulch and biosolid, lime soil pH adjustment, herbicide, seedling, tree planting, workers and drivers, and fuel and maintenance. Regression analysis is performed to analyze the data, and a reclamation cost estimation model is developed with high accuracy (R2 = 0.78). On the whole, this study proposes an innovative, step-by-step, technical, and economic approach to the optimal selection of plant species, and presents a reclamation cost estimation model so as to promote the open-pit mine reclamation process.

The soil's physical and mechanical properties are obtained through laboratory or in-situ tests. The dilatometer is an in-situ tool in rock mechanics and geotechnical engineering, and is widely used in developed countries. In the advanced version of this device, a geophone receives ground vibration. Thus Vs [1] could be obtained at the depth of the blade. This research work investigates the feasibility and performance of the first electronic seismic sensor due to its lower cost, more life span, more sensitivity instead of the geophone, and the ability to transfer signal. These changes make it an online tool connected to Arduino[2], a platform so the digital or analog result could be transferred automatically. The test is carried out under construction of Bahar Shiraz station of Tehran Metro Line 6 at the depth of 30 m. The hammer generates a shear wave, and after amplification, the received signals are measured with the software. The shear wave velocity at the test site is obtained at 504 m/s. The result compared to Vs reported geotechnical investigation done by “Darya-Khak-Pey consulting engineers” for Metro line 6 shows a 10% deviation. It is suggested to conduct more comparative tests to check the results and calibrate. Using an 801-S sensor with more life span (of more than 60 million times) and the ability to connect to the internet with an Arduino board is the innovation applied to introduce a new generation of this tool in the engineering world.

Due to the increasing consumption of lime in the flotation process to increase the pH of the system and create an alkaline environment, as well as its gradual increase in cost, the attention of researchers has been drawn to perform flotation operations in a neutral environment. Halophilic bacteria have the potential to replace flotation reducers such as lime because flotation can be done with their help at neutral pH as well. Also, due to the buffer effect of sea water, which is the chosen medium for bio-flotation, the use of bio-flotation method reduces the use of drinking water, and also reduces the consumption of chemicals. In this research work, five types of halophilic bacteria are studied for pyrite bio-depression and chalcopyrite flotation. Bio-flotation experiments are conducted using Hallimond tubes, and the bacteria Halobacillus sp., Alkalibacillus almallahensis, and Alkalibacillus sp. had better performance in pyrite depression and chalcopyrite flotation than other bacteria. The recovery of pyrite depression when using them was 30.9, 30.3, and 34.0 %, respectively, and the recovery of chalcopyrite flotation by them was equal to 52.9, 68.6, and 55.7, respectively, which indicates the high selectivity of these bacteria in flotation. In addition to the above tests, the effect of the combination of these three types of bacteria on pyrite depression and chalcopyrite flotation was also studied. The results obtained indicate that in the combination (mix) test of all three types of bacteria (33.3% of each type), pyrite was depressed better than other tests, and its recovery was 27.5%, which was lower than the single bacteria tests. Also, the effect of the combination of these three types of bacteria on the flotation of chalcopyrite is investigated, and its recovery was 72.6%, which was higher than the single bacteria tests. On the other hand, considering that the recovery of chalcopyrite in the three-bacteria combination tests was is higher than the single-bacteria and two-bacteria tests, it can be concluded that the combination of all three bacteria can cause a better synergism and improve their performance in micro-flotation tests.

One of the most important tasks in conducting a laboratory research work is how to make the samples. The purpose of this research work is to create heterogeneous rock-like samples containing non-persistent notches. Regarding that, the molds with dimensions of 250 mm x 200 mm x 50 mm are made. A mixture of plaster and water with different mixing percentages is used to make the heterogeneous samples. Various techniques are also employed to create non-persistent notches on the samples. One of the methods to create a notch is to insert an aluminum blade into the groove of the mold, and finally, remove it after the plaster slurry has hardened. Due to the displacement of the blade and its tilting during slurring, the notches are out of the vertical position. In addition to the mentioned method, other methods such as water jet, cutting by thread, cutting by diamond wire cutting, cutting by rotary saw, and using hand saw are applied. Finally, using a hand saw to create a notch on the samples is chosen as the best method.

As the mass ratio of alumina to silica (A/S ratio) in bauxite decreases, the cost of alumina production by the Bayer process sharply increases. With the increasingly fierce competition in the alumina industry and the gradual reduction in bauxite grade, when the A/S ratio drops to 3-4, the Bayer process is challenging to meet the market competition and production requirements. In such cases, the alumina production by sintering method has a vast development prospect and application potential for low-grade bauxite ores. The low A/S ratio and the high iron oxide content are the difficulties in the alumina production by the sintering process. This work adopts the lime-soda sinter process for extracting alumina from bauxite samples (A/S ratio = 1.34 and 20.80% Fe2O3) of the Semirom mine in Iran. The effects of sintering parameters are investigated. The maximum alumina extraction (88%) was obtained by a CaO/SiO2 molar ratio of 1.2, Na2O/Al2O3 molar ratio of 0.9, and sintering temperature at 1250 °C for 80 min. Also 83% of alumina is extracted by decreasing the N/A ratio to 0.66, to decrease the sodium carbonate consumption for a more economical process. The sintered materials are leached with sodium carbonate solution, and aluminum hydroxide [Al(OH)3] is precipitated. Finally, pure alumina (Al2O3) is obtained with a purity of 98 % after calcination at 1200 °C for 2 hours.

In this research work, with a simple, safe, and environmentally friendly approach to hydrometallurgy, a method for the recovery of lithium (Li), cobalt (Co), and nickel (Ni) from LIBs is suggested. The cathode materials are leached by malonic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the first process, and by L-glutamic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the second process. In order to optimize the leaching parameters including temperature, organic acid concentration, ascorbic acid concentration, type of organic acid, pulp density, and time, response surface methodology (RSM) of the experimental design process is used. According to the results, compared to L-glutamic acid in the second process, the leaching recovery increase considerably with malonic acid in the first process. This normally occurs due to the higher solubility of malonic acid in water, which results in a better complexation and a higher chelation rate. By contrast, as solubility of L-glutamic acid in water is low, metal-acid surface reaction and poor complexation are unavoidable. According to the statistical analysis of the results and validation testing, optimal experimental leaching occurs at the reaction temperature of 88 °C, organic acid concentration of 0.25 M, ascorbic acid concentration of 0.03 M, pulp density of 10 g/L, and leaching time of 2 h, via which metal recovery of 100% Li, 81% Co, and 99% Ni is achieved. Before and after acidic leaching, the sample active materials are qualitatively and quantitatively analyzed using X-ray diffraction, X-ray fluorescence, particle size analyzer, scanning electron microscope, energy dispersive spectroscopy, and atomic absorption spectroscopy.

The tensile strengths of geomaterials such as rocks, ceramics, concretes, gypsum, and mortars are obtained based on the direct and indirect tensile strength tests. In this research work, the Brazilian tensile strength tests are used to study the effects of length and inclination angle of T-shaped non-persistent joints on the mechanical and tensile behaviors of the geomaterial specimens prepared from concrete. These specimens have a thickness of 40 mm and a diameter of 100 mm, and are prepared in the laboratory. Two T-shaped non-persistent joints are made within each Brazilian disc specimen. The Brazilian disc specimens with T-shaped non-persistent joints are tested experimentally in the laboratory under axial compression. Then these tests are simulated in the two-dimensional particle flow code (PFC2D) considering various notch lengths of 6, 4, 3, 2, and 1 cm. However, different notch inclination angles of 0, 30, 60, 90, 120, and 150 degrees are also considered. In this research work, 12 specimens with different configurations are provided for the experimental tests, and 18 PFC2D models are made for the numerical studies of these tests. The loading rate is 0.016 mm/s. The results obtained from these experiments and their simulated models are compared, and it is concluded that the mechanical behavior and failure process of these geomaterial specimens are mainly governed by the inclination angles and lengths of the T-shape non-persistent joints presented in the samples. The fracture mechanism and failure behavior of the specimens are governed by the discontinuities, and the number of induced cracks when the joint inclination angles and joint lengths are increased.  For larger joints when the inclination angle of the T-shaped non-persistent joint is around 60 degrees, the tensile strength is minimum but as it is closed to 90 degrees, the compressive strengths are maximum. However, an increase in the notch length increase the overall tensile strength of the specimens. The strength of samples decreases by increasing the joint length. The strain at the failure point decreases by increasing the joint length. It is also observed that the strength and failure process of the two sets of specimens and the corresponding numerical simulations are consistence.

Feasibility studies of mining and industrial investment projects are usually associated with uncertain parameters; hence, these investigations rely on prediction. In these particular conditions, simulation and modelling techniques remain the most significant approaches to reduce the decision risk. Since several uncertain parameters are incorporated in the modelling process, distribution functions are employed to explain the parameters. However, due to the usual constrain of limited data, these functions cannot significantly explain the variation of those uncertain parameters. Support vector machine, one of the efficient techniques of artificial intelligence, provides the appropriate results in the classification and regression tasks. The principal aims of this research work are to integrate the simulation and artificial intelligence methods to manage the risk prediction of an economic system under uncertain conditions. The financial process of the Halichal mine in the Mazandaran province, Iran, is considered a case study to prove the performance of the support vector machine technique. The results show that integrating the simulation and support vector machine techniques can provide more realistic results, especially when including uncertain parameters. The correlation between the net present value obtained from the simulation and the net present value is about 0.96, which shows the capability of artificial intelligence methods and the simulation process. The root mean square error of the support vector machine prediction is about 0.322, which indicates a low error rate in the net present value estimation. The values of these errors prove that this method has a high accuracy and performance for predicting a net present value in the Halichal granite mine.

Due to the high number and severity of tire burst accidents of dump trucks, the present work is conducted to identify and prioritize the effective causes of dump truck tire bursts using the fuzzy best-worst method (FBMW). The present work is conducted using content analysis and FBMW. First, by using focus groups and exploring the texts and events, and then these factors are weighted and then prioritized using FBMW. The results of the first phase show that the factors affecting the bursting of dump truck tires can be classified into 5 main categories of road conditions (six sub-categories), maintenance (six sub-categories), monitoring, and inspection (10 sub-categories), unsafe behavior (seven sub-categories), and tire conditions (five sub-categories). The results of the second phase also show that the tire conditions and unsafe behavior are the most important factors with a mean weight of 0.2252 and 0.1681, respectively. The results of the present work show that the most important cause is the monitoring of temperature, pressure, and tire conditions. Therefore, it can be concluded that in order to reduce these accidents, in addition to choosing the right tire, the conditions such as temperature and pressure inspection should be given a high attention.

In this work, the results of nearly 1400 stream sediment sample analysis are processed to better understand environmental pollution caused by mining activities in Eastern Iran. The stream sediment samples are analyzed for As, Sb, Fe, Cr, Ni, Co, Cu, Zn, Pb, Sr, and Hg. The mean concentration of these elements follows the decreasing order of Fe > Sr > Zn > Cr > Cu > Ni > Co > Pb > As > Sb > Hg. Based on the assessment of pollution, extremely severe enrichment factor Co (EF > 25), and high enrichment of Sb, Hg, Cr, and Sr (EF > 10) are detected. Specifically, Cr and Ni in southern stream sediments show significantly elevated concentrations compared to the others. The range of the contamination factor varies from CF < 1 to CF > 6 for most elements. Geo-accumulation index shows high contamination levels by Cr and Co and high to severe contamination by Sb. The risk indices are low for all elements except for As and Co in the eastern part of the studied area. Principal component analysis, Spearman correlation coefficient, and cluster analysis are used to demonstrate similarities and differences between the elements. Pollution indices show that contaminations in some samples are the consequence of gold mineralization. The high correlation of Cu, Zn, and Sb is due to the sulfide mineralization of gold. The high correlation of Cr and Ni corresponds to ultramafic rocks and ophiolitic series. This study focuses on the impact of mining activities, even at early stages on the dispersion of some heavy metals in stream sediments. Based on the results presented here, while most contamination in the target area is rooted in geochemical and mineralization processes, mining activity also contributes to soil pollution for certain elements such as Cu and Zn. The most affected stream sediments are those within the vicinity of mining areas and attention should be paid to potential risks to the environment particularly during gold mining activities.