 Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
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- Evaluation of using waste pinecones as an eco-friendly additive to
water-based mud
Authors: Hani AL Khalaf, Nagham Alhaj Mohammed , Gabriella Federer
Pages: 1 - 11
Abstract: This study is investigating the possibility of using pinecones as additive materials to develop a water-based drilling mud. Pinecones are environmentally friendly agricultural wastes and have no practical applications. Therefore, this study is of great importance in that it highlights the investment of these natural waste materials in practical fields. The study focused on the effectiveness of pinecone powder in a water-based drilling mud. To this end, an experimental study on five types of pinecones (Austrian pinecones, Black Hills Spruce, Sitka Spruce, Norway Spruce, and White pinecones) was performed and tested to determine their ability to reduce filter loss and also the effect of those eco-friendly materials on the rheological properties and density of the mud. In the study, 26 samples of water-based mud mixed with the different types of pinecones at different concentrations based on the weight of mud sample (1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%) were used to perform the experiments. The results of the study showed that pinecones have a great ability to reduce filter loss, particularly Norway Spruce cones, which, based on this study, are considered the superior type with a concentration of 3 wt%.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.1
Issue No: Vol. 37, No. 2 (2022)
- Development of Water-Based Drilling Fluid in Mitigation of Differential
Sticking Tendency
Authors: emine yalman, Gabriella Federer-Kovacs , Tolga Depci
Pages: 13 - 21
Abstract: The objective of the study is to design a drilling fluid that prevents differential pressure pipe sticking tendency caused by drilling fluid with fly ash that is an industrial waste generated from the combustion of coal. To this end, drilling fluid samples were prepared with different particle sizes obtained through the sieving and grinding process and increasing concentrations of fly ash. Differential pipe sticking tests of the samples were performed by applying 3.447 MPa (500 psi) pressure and using a Fann Model 21150 Differential Sticking Tester in order to determine how the coefficient of sticking and torque reading varied with the fly ash. From the results, it was observed that the coefficient of sticking and torque reading of the water-based drilling fluids decreased up to a specific concentration as the concentration of fly ash increased. Furthermore, particle size analysis illustrated that the coefficient of sticking and torque of the drilling fluid differs depending on the particle size of fly ash introduced. The drilling fluid designed with ground fly ash demonstrated lower sticking coefficient and torque reading than that of drilling fluids formulated with raw and sieved fly ashes. The experimental study revealed that fly ash is a promising additive in the mitigation of differential sticking tendency caused by water-based drilling fluids.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.2
Issue No: Vol. 37, No. 2 (2022)
- Field investigations of deformations in soft surrounding rocks of roadway
with roof-bolting support by auger mining of thin coal seams
Authors: Ivan Sakhno, Svitlana Sakhno, Alla Skyrda
Pages: 23 - 38
Abstract: Coal auger mining is a promising technology used for excavating thin coal seams. The efficiency of auger mining is largely related to the stability of mine roadways in the influence zone of the coal-face. Roof bolting systems are promising in such conditions. An adequate choice of roof bolting parameters is only possible if one understands the features of the stratification of the rocks and stages of deformation of the array in auger mining. Modern monitoring methods of the condition of rocks are based on the use of mechanical benchmarks, sounding of the mine array and the use of optical devices. There are few studies concerning roadways with auger mining. The innovations presented in this manuscript are a determination of the research results of the in-situ processes of rock deformation around a roadway in auger mining which will help to better understand the features of deformation processes in the technological method and design an adequate support system. Some field studies were undertaken in order to investigate the geo-mechanical processes that can be observed while auger mining a roadway with fully grouted bolts of 2.4 m in length. The research included monitoring rock stratification with the help of mechanical telltales, the convergence in the roadway using contour benchmarks, measurements of altitude and rock falls, and visual observations. The presented results show that roof-bolting can be used to support the roadways for auger mining.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.3
Issue No: Vol. 37, No. 2 (2022)
- Architectural complexities and morphological variations of the sediment
waves of Plio-Pleistocene channel levee backslope of the Indus Fan
Authors: Ehsan Arif, Ji Youliang, Khurram Shahzad , Saad Mashwani, Hadayat ullah, Muhammad Zaheer
Pages: 39 - 54
Abstract: The architecture of the turbidity current sediment waves exhibits intricate morphologies and patterns on the Indus Fan channel levee backslope. The sediment waves are present on the channel levee of Plio-Pleistocene age and are absent in the deeper sections of the study area. The architecture of channel levee backslope on the Indus Fan is poorly understood. We used seismic interpretation techniques and modelling by utilizing high-resolution seismic data to approach this problem. The morphological variations in wavelength, crest dimensions and potential wave formation patterns suggest the autogenic and allogenic processes associated with wave development. Wavelengths reach up to 1473 m with an average of 486.84 m and the height of the levee ranges between 10 m and 60 m (average 30 m). The angle of the channel levee and dimension of the sediment wave here are independent of each other. Low angle levees have accommodated high dimension sediment waves and vice versa at multiple points downslope. Characteristically, the waves have formed on the outer levee (usually left) of the channels marked by steep margins suggesting that flow overspill caused the development of the waves. Generally, the younger sediment waves followed the patterns of older sediment waves, but the varying trends are often observed in the study area. The patterns of the sediment waves towards the younger sections of the levee indicate the modified and varying architectural style of growth. Sediment waves are generated by downslope turbidity currents. However, the deformation features have also possibly triggered the development of sediment waves.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.4
Issue No: Vol. 37, No. 2 (2022)
- An investigation of the effect of initial bubble diameter on the bubble
trajectory in the flotation column cell using CFD simulation
Authors: Narjes Khorasanizadeh, Mohammad Karamoozian, Hossein Nouri-Bidgoli
Pages: 55 - 66
Abstract: The effect of initial bubble diameter on the bubble motion pattern in a flotation column has been studied by the twophase computational fluid dynamics (CFD) method. The two-phase simulations have been done using the volume of a fluid (VOF) model in ANSYS® Fluent® software. The computational field was a square cross-section column with a width of 0.1 m and a height of 1 m into which air was interred as a single bubble from the lower part of the column by an internal sparger. An experimental test has been also performed and the simulated results have been validated using the values obtained for the bubble rise velocity. A comparison of the simulation and the experimental results has confirmed that CFD can predict the bubble rise velocity profile and its value in the flotation column less than 5% relative to the experimental values. Then the simulations have been repeated with a 20% decrease and increase in the initial bubble diameter to investigate the effect of bubble diameter on the bubble flow pattern. The investigations have shown that as the bubble diameter increases, the velocity decreases and the bubble rises in a more zigzag direction as a result of two counter-rotating trailing vortices behind the bubble increasing.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.5
Issue No: Vol. 37, No. 2 (2022)
- Development of a 3D numerical model for simulating a blast wave
propagation system considering the position of the blasting hole and
in-situ discontinuities
Authors: Mojtaba Yari, Daniyal Ghadyani , Saeed Jamali
Pages: 67 - 78
Abstract: Blasting operations are one of the most important parts of geotechnical and mining projects. Most rocks naturally have a series of discontinuities that significantly affect their responses to blast waves. In this paper, the propagation of a blast wave in one intact rock and four rocks with different joint conditions are simulated by a 3-dimensional distinct element code. The results showed that the joint in the model acted as a wave barrier and passed part of the waves, absorbed a portion, and reflected the remaining part into the model. In other words, a discontinuity reduces the energy of the wave and causes more wave attenuation. In addition, a shorter distance between the joint and the hole causes slower wave propagation and greater damping. Moreover, the results showed that the smaller the angle between the discontinuity and axis of the blast holes, the more stress occurs in the rock bench.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.6
Issue No: Vol. 37, No. 2 (2022)
- The efficiency of a small sized hand-made shaped charge
Authors: Vječislav Bohanek, Mario Dobrilović, Barbara Štimac Tumara , Siniša Stanković
Pages: 79 - 85
Abstract: Shaped charges are widely used in many different fields. The two main users of shaped charges are the military, where shaped charges are used as a weapon against armoured targets, and the oil industry, to perforate wells. Very often, shaped charges are the subject of scientific research focused on optimising shaped charge parameters and increasing the efficiency of shaped charges. Considering a significant number of parameters affecting the penetration depth, the optimization of shaped charge parameters is a complex process. This paper describes research on the efficiency of small handmade shaped charges. In this research, two methods are used, the first one involves simulations with numerical software and the second one is site testing. AUTODYN software was used for the numerical simulations. One of the simulations was focused on the shape and velocity of the shaped charge jet and the second on the penetration of the jet into the target material. On-site efficiency of shaped charges at different standoff distances was tested. The experimental result was compared with the AUTODYN simulation result for hand-made shaped charges placed at a distance of 90 mm from the target material. The results of the simulations agree very well with the results of the site tests. Some advantages and disadvantages of each approach are also observed.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.7
Issue No: Vol. 37, No. 2 (2022)
- Effects of a pillarless, center-out stoping pattern on haulage drift
performance and ore tonnage at risk
Authors: Wael Abdellah
Pages: 87 - 96
Abstract: (e.g. pyramidal sequences) on the performance of mine haulage drifts (e.g. ore access units), the tonnage of unmined ore at risk, and the required quantity of fill material. Using RS2D software, a two-dimensional, elasto-plastic finite-element model for a haulage drift located at 1200m below the surface in the orebody’s footwall has been built. The spread of yielding zones into the rock mass around an access drift and unmined stopes is used to assess mine haulage drift stability and estimate the amount of unmined ore at risk owing to local mining activity. The findings are presented and discussed in terms of the size of failure zones, the number of tonnes of unmined blocks at risk, and the amount of backfill materials required, all in relation to the mining stage. The findings show that haulage drift stability is rapidly diminishing. The drift roof begins to deteriorate at an early stage (after mining step 3). In the drift roof, left wall, floor, and right wall, failure zones measured 1.55m (step 3), 2.28m (step 4), 2.57m (step 5) and 1.88m (step 5) accordingly. After mining step 4, there was a total of 905 m3 of unmined ore at risk (4100 tons), and after mining step 5, a total of 1500 m3 (30 tons) of back fill material was required to strengthen stopes.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.8
Issue No: Vol. 37, No. 2 (2022)
- Determination of detonation front curvature radius of ANFO explosives and
its importance in numerical modelling of detonation with the Wood-Kirkwood
model
Authors: Barbara Štimac Tumara, Mario Dobrilovic, Vinko Skrlec, Muhamed Suceska
Pages: 97 - 107
Abstract: Unlike most military high explosives, which are characterized by an almost plane detonation front, ammonium nitratebased commercial explosives, such as ANFO (ammonium nitrate/fuel oil mixture) and emulsion explosives, are characterized by a curved detonation front. The curvature is directly related to the rate of radial expansion of detonation products in the detonation driving zone and the rate of chemical reactions, and it is one of the characteristics of nonideal explosives. The detonation theories used to model the nonideal behaviour of explosives require both reaction rate and rate of radial expansion to be known/specified as input data. Unfortunately, neither can be measured and what is mostly used is a link between these rates and parameters which can be more easily measured. In this paper, the Wood-Kirkwood approach of determination of radial expansion through the radius of detonation front curvature and the electro-optical technique for experimental determination of detonation front curvature of ANFO explosives is applied. It was shown that an experimentally determined radius of detonation front curvature vs charge diameter, incorporated in the Wood-Kirkwood detonation theory, can satisfactorily reproduce experimental detonation velocity-charge diameter data for ANFO explosives, especially when the pressure-based reaction rate law is also calibrated (D=1.3 and k=0.06 1/(μs/GPaD)).
PubDate: 2022-03-15
DOI: 10.17794/rgn2022.2.9
Issue No: Vol. 37, No. 2 (2022)
- Experimental and numerical research of jointed rock mass anisotropy in a
three-dimensional stress field
Authors: Pavel Verbilo, Maxim Karasev, Nikita Belyakov, Grigirii Iovlev
Pages: 109 - 122
Abstract: Joints often have a significant influence on material characteristics. The discontinuities’ coalescence mechanism and complex jointed rock mass structure as a composite need to be further explored. In this study, compression and shear tests were carried out on a jointed rock mass. The purpose of the jointed rock mass behaviour study was to determine the deformation-strength dependencies and to determine the parameters for a quantitative assessment of the joints’ influence on mechanical characteristics. The results show that compression strength depends on the materials’ structure, and there is a detailed description of the joints’ orientation influence on stress-strain dependencies during compression experiments. The numerical method used in this study could be used for the modelling of composite materials and their properties.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.10
Issue No: Vol. 37, No. 2 (2022)
- Power consumption management and simulation of optimized operational
conditions of ball mills using the Morrell Power model: A case study
Authors: Hojjat Hosseinzadeh Gharehgheshlagh, Sajjad Chehreghani, Sahand Haghikia
Pages: 123 - 135
Abstract: The amount of comminution or fineness of minerals in a mill can be described by various parameters, the most important of which is d80 (80% passing size). The purpose of this study is to investigate and simulate the optimal operating conditions of a ball mill in a copper processing plant. The actual operating conditions in the intended mill are performed with a 300 tph tonnage, a 267 second retention time, and a discharge d80 = 53 μm. Laboratory studies showed that the optimal economical and metallurgical recovery of copper in this plant is achieved in 65 μm ≤ d80 ≤ 75 μm with Flotation Recovery (R) = 90.16%, Economical Efficiency (EE) = 93.04% and Separation Efficiency (SE) = 88.64%. In this study, having the optimal d80 for the concentration unit, the mill data, and utilizing Excel Software and the Morrell method, first the total power for the optimal set of d80 was calculated, which is equal to 7790 to 8005 kW. Then, according to these power values, the corresponding retention times were calculated, which are equal to 236 and 247 seconds respectively. Finally, utilizing the retention time-tonnage relationship and taking into account the specific filling of the mill, the optimal corresponding tonnages to the obtained retention times were calculated, ranging from 324 to 340 tph. The results of these studies showed that by reducing the level of comminution from d80 = 53 μm to 65 μm ≤ d80 ≤ 75 μm, in addition to increasing flotation efficiency to R = 90.16%, EE = 93.04% and SE = 88.64%, about 4.21% to 7.09% energy savings and an 8.00% to 13.33% tonnage increase will occur.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.11
Issue No: Vol. 37, No. 2 (2022)
- Assessment of excavation intersections’ stability in jointed rock masses
using the discontinuum approach
Authors: Anatolii Protosenya, Maria Vilner
Pages: 137 - 147
Abstract: During ore deposit development, vast networks of excavations are designed, and the volume of their intersections reaches 10%. At excavation intersections, the prediction of stress-strain state changes is complicated due to spatial geometry, the cross-coupling effect, construction sequence, etc. Mechanical properties of rocks, joint set parameters and the initial stress field also have a significant impact on stress redistribution. According to studies, up to 40% of the total number of failures in excavations occur during their intersections’ construction or reinforcing. Loads on the intersection support in accordance with existing methods are determined as for single excavations with an equivalent span and defined as the width of the larger excavation. The trend towards the intensification of mining, an increase in depth and the complexity of mining and geological conditions also complicate stress state assessment. Existing approaches need to be revised and updated for a more accurate prediction of the stress-strain state at intersections, and should consider spatial geometry, joint sets and initial stress field parameters. In this research, discrete element numerical modelling in 3DEC is done and the results are compared with existing empirical methods. Numerical models are created in a spatial setting and contain explicit representations of joints in the rock mass. Models are verified based on in-situ data, and the obtained results show a difference of up to 2 times in comparison with empirical results. This indicates that the reliability of the existing empirical methods is low, which may lead to stability loss on an intersection. Therefore, empirical methods should be updated. This can be done on the basis of numerical modelling, which shows sufficient convergence with in-situ data.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.12
Issue No: Vol. 37, No. 2 (2022)
- Landslide susceptibility assessment of the City of Karlovac using the
bivariate statistical analysis
Authors: Marko Sinčić, Sanja Bernat Gazibara, Martin Krkač, Snježana Mihalić Arbanas
Pages: 149 - 170
Abstract: A preliminary landslide susceptibility analysis on a regional scale of 1:100 000 using bivariate statistics was conducted for the City of Karlovac. The City administration compiled landslide inventory used in the analysis based on recorded landslides from 2014 to 2019 that caused significant damage to buildings or infrastructures. Analyses included 17 geofactors relevant to landslide occurrence and classified them into four groups: geomorphological (elevation, slope gradient, slope orientation, terrain curvature, terrain roughness), geological (lithology-rock type, proximity to geological contacts, proximity to faults), hydrological (proximity to drainage network, proximity to springs, proximity to temporary, permanent and to all streams, topographic wetness) and anthropogenic (proximity to traffic infrastructure, land cover using two classifications). Five scenarios were defined using a different combination of geofactors weighted by the Weights-of-Evidence (WoE) method, resulting in five different landslide susceptibility maps. The best landslide susceptibility map was selected upon the results of a ROC curve analysis, which was used to obtain success and prediction rates of each scenario. The novelty in the presented research is that a limited amount of thematic data and an incomplete landslide inventory map allows for the production of a preliminary landslide susceptibility map for usage in spatial planning. Also, this study provides a discussion regarding the used method, geofactors, defined scenarios and reliability of the results. The final preliminary landslide susceptibility map was derived using ten geofactors, which satisfied the pairwise CI test, and it is classified in four zones: low landslide susceptibility (57.05% of the area), medium landslide susceptibility (20.63% of the area), high landslide susceptibility (13.28% of the area), and very high landslide susceptibility (9.03% of the area), and has a success rate of 94% and a prediction rate of 93% making it a highly accurate source of preliminary information for the study area.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.13
Issue No: Vol. 37, No. 2 (2022)
- Effect of grinding media on the milling efficiency of a ball mill
Authors: Gamal S. Abdelhaffez, Ahmed Abd Elmajeed, Haitham Magdi Ahmed
Pages: 171 - 177
Abstract: The size of grinding media is the primary factor that affects the overall milling efficiency of a ball mill (e.g. power consumption and particle size breakage). This article tackles the lack of a design tool that could help choose the ball loading composition in mills. Such a tool enables the maximization of the exposed surface area per unit energy (cm2/J). The effect of ball load composition, by varying the grinding media size distribution (e.g. alternatively by mixing four groups of 19.5, 38 mm; 19.5, 50 mm; 38, 50 mm and 19.5, 38, 50 mm), on the milling efficiency of a laboratory scale ball mill has been investigated in this article concerning ball number, total surface area, and ball weight. The results reveal that the amount of required energy is close in values, per each ball loading mixture, concerning three characteristic parameters. The amount of required energy varies between 3.22 kWh/st & 3.65 kWh/st. Moreover, the new surface area per unit energy (e.g. cm2/J) significantly influences milling efficiency. In contrast, the ball weight has a minor effect. This study would be helpful in industries in which comminution is part of the process, such as mining and cement industries.
PubDate: 2022-03-15
DOI: 10.17794/rgn.2022.2.14
Issue No: Vol. 37, No. 2 (2022)
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