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By P. H. S. W. Kulatilake

The presence of discontinuities strongly affects the mechanical and hydraulic behavior of rock masses. Joint geometry networks play a vital role in civil, mining, and petroleum engineering projects associated with jointed rock. The need for a realistic representation of joint geometry in rock masses has been recognized. The first part of the paper shows how to build three-dimensional stochastic joint network schemes and also shows how to perform validation studies for these schemes using joint data from the Stripa mine, Sweden. Due to the existence of complex joint patterns, mechanical behavior of jointed rock masses usually exhibit scale effects and an-isotropic properties. A correct understanding of the mechanical properties (strength and deformability) of jointed rock masses is important for designing and performance estimation of structures build in and on rock masses. Beyond a certain volume, the mass proper-ties of the rock may remain essentially constant with respect to the effect of joints. This minimum volume may be used as the element size to represent the equivalent properties of a statistically homogeneous rock mass volume which contains a significant number of joints. This volume may be termed as a "Representative Elementary Volume" (REV) and may be of great importance for engineering purposes. Investigations are underway at both the 2D and 3D levels to look into the possibility of establishing relationships between REV mechanical properties and joint geometry parameters. Recently developed joint geometry modeling schemes are linked with existing distinct element codes (both 2D and 3D) to create a stochastic/deterministic stress analysis approach in achieving the goal. Results obtained so far in this direction are presented in the second part of the paper.

Jan 1, 1992

By John S. Brock

During 1964 and 1965 a mineral exploration program was carried out over an area of approximately 250 square miles, located in the Anvil-Vangorda Creek area of east central Yukon, 125 miles northwest of Whitehorse. The Vangorda deposit, a massive lead-zinc sulphide body discovered in 1953, was centred in the area proposed for exploration, a northwest trending belt located between the southwestern flank of the Anvil Range and Pelly River. Exploration for base metals in the remote Anvil area had previously been restricted by poor metal markets in the late 1950's. Regional geologic information was also limited except for publication of a scale 1 inch to 4 mile map by the Geological Survey of Canada in 1961. To effectively explore this area, a combination of geophysical and geochemical methods were essential due to extensive overburden cover varying in depth from a few feet to over 300 feet. (Figure (i) Key Map) Dynasty Explorations initiated the first comprehensive regional exploration program in the Anvil area, utilizing saturation prospecting methods employing geologic, geochemical and geophysical methods. The program involved an approach demanding continual modification of technical and physical logistics. After a total of 12 months of field work involving an expenditure of approximately $450,00, massive sulphides were discovered which subsequently proved to be an economic orebody. Thirteen properties had been acquired and explored. Ten separate geophysical anomalies had been outlined by a combination of magnetic, electric and gravimetric survey techniques of which five were tested by rotary drilling and two by diamond core drilling. The discovery of the Faro deposit was a direct result of this program.

Jan 1, 1971

By Thomas P. Oxford

The impact of recent legislation on Florida phosphate industry operations has been dramatic. The most significant influences are described: the National Environmental Policy Act of 1969; the Federal Water Pollution Control Act Amendments of 1972; and implementation of the Florida Environmental Land and Water Management Act of 1972. Further discussion includes: critical examination of the recently completed EPA Areawide EIS; potential effects of the Resource Conservation and Recovery Act of 1976; the Surface Mining Control and Reclamation Act of 1977; current local and state laws; and summary of studies on radiochemical effects of mining, seepage from gypsum ponds, and dewatering of waste clays.

Jan 1, 1979

By John L. Halls

Modern business practice dictates that in order to ensure the economic optimization of investment, the size of any investment venture must be such that every increment of capital invested in such a venture yields at least a corporate minimum acceptable rate of return. This practice is based on the premise that alternative investment opportunities capable of yielding the minimum corporate return are immediately available. If a mining corporation is to make the maximum use of its investment funds, any capital investment in a mining property must comply with the above practice. The most important parameter in estimating ore reserves is the cut-off grade which is used to separate material into ore or waste. The cut-off grade is calculated on the basis that material of cut-off grade produces sufficient revenue to cover the estimated costs of mining and processing through to sales, including depreciation and produce a pre-determined profit. Ore reserves so estimated are adequate for determining the magnitude of an orebody but do not provide a sound basis for determining plant size and therefore capital investment in a new property or for expansion consideration on an existing property. From a financial analysis of this one ore reserve it is impossible to ascertain whether each increment of capital investment is providing the minimum acceptable rate of return, Other difficulties associated with the calculation of a cut-off grade including the determination of depreciation and the amount of pre-determined profit to be included in the cut-off grade calculation are outlined in the text. The proposed solution to determine optimum ore reserves and plant size for new properties avoids the complication of calculating a cut-off grade by computing a series of ore inventories using arbitrarily selected cut-off grades. A comparison of the cash flows generated by production from such ore inventories using incremental financial analysis clearly indicates the ore reserve and plant size which will best serve the corporation's investment and metal production goals. Incremental financial analysis of a corporation's operating mines and prospects assists management in assessing the comparative expansion and investment possibilities of each property for increasing or maintaining metal production on a long term basis.

Jan 1, 1969

By Ben E. Adams

The Duval Corporation Sierrita copper and molybdenum mining complex is located approximately twenty-three miles south of Tucson, Arizona. The original open pit mine, Esperanza, was put into operation in 1958 and utilized one tailings dam until the Sierrita operation began in 1970, and a second pond was started. Both tailings operations continued to be operated separate and independently of each other until 1977, when the Esperanza Mill was temporarily shut down, and the Esperanza Tailings Dam was retired from service. Except for short periods of use, no new tailings were put on the surface. With the reactivation of the Esperanza Mill in 1979, the Esperanza tailings were combined with the Sierrita Mill tailings and put on the Sierrita Dam, leaving the Esperanza Dam in a retired state.

Jan 1, 1984

By Jack S. Watson, Rasika Nimkar, Robert M. Counce, BRADLEY BENNETT, Patrick Zhang

This study level process design represents an economically viable method for extracting thorium dioxide and other rare earth elements from monazite ore. This paper incorporates results from the 2019 capstone project from the honors Design Internship in Green Engineering in Chemical and Biomolecular Engineering. In this activity, senior students in Chemical Engineering at the University of Tennessee (UT) focused on the development and study of a process for the recovery of thorium dioxide and P2O5 from monazite. While not mandated, the process offers rare earth oxides as attractive byproducts. The project focused on recovery of byproducts rather than the creation or addition to waste streams. Additionally, (1) the process economics relied heavily on recovery of rare earth byproducts, (2) thoriumhandling portions of the process could be effectively segregated from rare earth and phosphate handling portions of the process, and (3) thorium and uranium content of waste streams should be carefully managed and eliminated where possible.

May 29, 2020

By Nasser Madani, Yerbol Tussupbekov, Sergei Sabanov, Zarina Mukhamedyarova

A case study was conducted on a metal mine operating in Kazakhstan, in which problems were associated with use of a complicated and outdated ventilation system and its high expenses. The mine needs to reconsider its existing ventilation system and identify the risks associated with operational losses when using this ventilation system. The aim of this study was to develop an efficient risk analysis method capable of estimating operational risks and financial benefits of the existing mine ventilation system. The developed risk analysismethod considers ventilationmodelling, riskmodelling, and financialmodelling.Ventilation modelling comprises ventilation simulation and ventilation financial simulation. In risk modelling, the number of risk events occurring with the use of existing ventilation system and the operational losses during these events is estimated. Financial modelling considers operational losses and ventilation financial simulation benefits and uses a dynamic cash flow model to estimate how cost variability influences the cash flow. As a result, the improved ventilation system attains an additional NPVa ranging from 3.2 to 8.5 million US$ at the corresponding defined probability of 90%. The results of this study reveal that the developed risk analysis method can efficiently estimate the financial benefits of ventilation modelling and consider risk events and their total operational losses associated with use of the existing ventilation system. This approach provides a range of possible outcomes and helps with deciding whether the ventilation system is appropriate or whether it should be updated to better suit the project financial benefits.

Jun 3, 2020

While there have always been mining activities on the outcrops of the copper deposits around Tsumeb, large scale mining activities in Namibia only started in colonial times. Originally focusing on the known deposits, the then German Geological Survey and independent geologists soon discovered significant deposits all over the country. This eventually lead to intensive mining operations all over the country on copper, gold, diamonds, fluorspar and finally uranium. Ever since those days, mining has been one of the major economical factors of Namibia?s development, as shown in picture 1. In the Central Namib Desert mining on base metals started in 1901, and first uranium deposits were discovered as soon as 1910, later followed by others, this did, however, not lead to any mining activities on those uranium deposits in the following decades. [ ] The upswing in the use of nuclear energy in the 1960s and early 1970s triggered some extensive uranium exploration worldwide and also in Namibia. Several airborne radiometric overviews were conducted by the Geological Survey at this stage and eventually the first uranium mine was commissioned in 1976. In the following three decades, the focus of prospecting activities in Namibia shifted away from uranium again. However, since 2000 the forecast for a developing and growing global economy and its even stronger growing energy demand have triggered a large number of nuclear energy projects worldwide, thus increasing the installed nuclear energy generation capacity from 387 GW today to more than 490 GW in 2025.

Jan 1, 2011

By C. V. Deutsch, T. Acorn

Understanding and managing risk is of increasing concern for the mining industry. Although methods exist to model geologic uncertainty based on stochastic modeling techniques and multiple realizations, there are few approaches to manage this geologic uncertainty in pit optimization. Block values can be penalized if the block uncertainty is high, but the goal here is to consider the reserve risk within the pit. This paper presents an approach for pit optimization that considers all realizations simultaneously with a heuristic pit optimizer. The heuristic algorithm maximizes value and also penalizes reserve risk. The inclusion of multiple realizations provides access to the risk or uncertainty in the total pit value. Considering this information permits an active risk management approach that can manage the uncertainty in the reserves within the entire pit.

Jan 1, 2018

By Swades Kumar Chaulya, Vikash Kumar, Sushma Kumari, Naresh Kumar, Girendra Mohan Prasad, Monika Choudhary

During harsh weather conditions, the presence of fog, dust in the environment degrades the image’s quality, which affects the visibility of drivers of heavy earth-moving machinery in opencast mines. Due to low visibility, mining operations cannot be carried out as drivers are easily prone to accidents. This paper proposes a technique that includes developing a vision enhancement system called perceptive driving assistant system for increasing visibility of real-time video of the road in front of the vehicle for operators of heavy earth-moving machinery at opencast mines during harsh weather conditions to overcome the problem. The system consists of high-quality Internet Protocol cameras and thermal cameras for real-time image processing and other well-defined devices, which is quite capable of enhancing the visibility of the image, outlining edges of the road, and detecting obstacles present on the path of operators for smooth driving and reducing threat of accidents. A high-speed graphical processing unit has been used for quality-performance parallel computing, which is well suited for real-time operations to empower fast real-time operations. The calculated frame per second (fps) of image enhancement, object detection, and edge detection is 17.91, 15.91, and 25.09 fps, respectively. The actual frame rate is 26.07 fps, and after applying the algorithm, the final frame rate is 19.65 fps. The calculated accuracy of the object detection model is 81.23%. Field trials indicate that the developed system has performed adequately during foggy weather.

Sep 21, 2022

By SONGHE WANG, YI XUE, PENG HOU, CAIHUI ZHU, XUANYE JIAO, Feng Gao

The abstract discusses the challenges of coalbed methane development in China due to low coal seam permeability. It highlights protective layer mining as a method to reduce in-situ stress and enhance permeability for improved gas drainage and disaster prevention. The study involves experimental and numerical simulations to analyze gas migration and permeability changes during stress release. It includes a stress-strain-seepage coupled test on coal, development of a mathematical model for coal seepage under mining unloading, and a numerical model based on the Wulan coal mine to explore in-situ stress release, permeability evolution, and gas drainage in an unloaded coal seam. The aim is to demonstrate the effectiveness of combining protective layer mining and gas drainage technology for gas outburst risk elimination.

Mar 14, 2022

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2018

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2017

By Qiang Wang, Jiaqiang Yu, Chunhui Fan, Yong Wang, Changyu Jin, Jun Bai, Yu Lu

Accurate ore blending necessitates an in-depth understanding of movement trajectories of fragments and the spatial evolution of the displacement field in the bench during blasting, Accurate ore blending is currently one of the most complex challenges faced by mining engineers. In light of this problem, a systematic study was conducted in this paper using neural network and numerical simulation based on field monitoring data. A nonlinear mapping relationship was established between the mechanical parameters of rock mass and the displacements of the monitoring points. The measured displacements of monitoring points under blasting were input into the neural network, which used back-calculation to derive the mechanical properties of the rock mass. These parameters were then applied in a forward calculation to analyze the movement trajectory of the monitoring points. The results showed that the calculated displacements were in good agreement with the monitoring results during the. The average relative errors in the horizontal and vertical displacements were 4.12% and 15.2%, respectively. Furthermore, the muckpile profile was in an inverted recumbent “S” shape after bench blasting, which was consistent with the actual shape of the muckpile. This verified the rationality and accuracy of the method proposed in this study. Finally, the movement trajectories of particles in the bench and the spatial evolution law of the displacement field during bench blasting were determined based on the calculation results, offering theoretical support and fundamental information for accurate ore blending.

Dec 16, 2023

By Haitao Wang, Shen Wang, Dongyin Li, Yongjia Xu, Jinzhao Liu, Xiangjun Chen

The safe and efficient driving of the roadway along the gob is becoming an increasing challenge due to the influence of the integrity and bearing capacity of the side coal and rock mass in the gob under the roof cutting mining mode. The mechanism of protection of the gob-side roadway is shown by modeling the influence of roof cutting and the application of a destress technique on the lateral coal and rock mass zones. The distribution characteristics of stress, displacement, and fracture in the overburden are analyzed by numerical simulation method under the three working conditions. The results indicate (1) construction of row holes and blasting can form artificial structure’s fracture plane above the roadway, which can effectively cut the connection of overburden. The artificial structure’s fracture plane decreases the peak value of the lateral coal body’s support pressure. The peak point and the critical location of the stress reduction area are both transferred to the deep part at the same time, providing adequate space for the gob-side roadway. (2) The stress arch foot in the lateral rock mass rises to the rock layer at the bottom of the roof cutting plane after top cutting, as does the high-pressure area of deviator stress. The fracture plane prevents lateral coal and rock mass instability and limits the negative effects of roof deformation above the gob-side roadway. (3) The triangle slip fracture zone moves to over the roof cutting drilling zone due to the fracture plane, showing a high position compared to its original zone.

Jul 11, 2023

By Gang Yang, Manchao He, Chengzhang Gao, Jun Zhang, Yayun Li, Jun Yang, Shilin Hou, Ben Liu, Yajun Wang, Jianning Liu

To explore the mechanism of roof directional breaking in gob-side entry formed automatically without coal pillars, the numerical simulation was used to study the deformation movement of roof, the deformation evolution of roadway, and the stress distribution of roadway under roof directional breaking and non-roof directional breaking. Based on the results, the deformation movement of roof is divided into three stages: the goaf roof collapse stage, the basic roof deformation stage, and the basic roof stability stage. The goaf is filled with gangue due to the broken expansion characteristics of the collapsed rock under the roof directional breaking. Due to the supporting force of gangue, the deformation of the basic roof under the roof directional breaking is smaller than that under the non-roof directional breaking, which reduces the influence of the deformation of the basic roof on the deformation of the roadway roof and improves the integrity of the roadway. At the same time, roof directional breaking cuts off the stress transfer path of partial roof, which weakens the peak stress convergence on the arc side, transfers the peak stress convergence to deeper, and improves the stability of roadway. Finally, a field test was carried out to further verify the accuracy of the numerical simulation. The field test results are in good agreement with the numerical simulation results. The roadway deformation is small and meets the requirements of safety production. It is proved that roof directional breaking plays a positive role in improving the stability of the roadway.

Dec 22, 2022

By Dushasan Kundu, B. N. Shivakiran Bhaktha, Khanindra Pathak, Sarbojit Mukherjee

Mine safety and quality of life of miner working in underground mines depend to a large extent on mine illumination and communication. The provisioning of reliable, safe, and cost-effective illumination is critical, particularly in underground gassy coal mines. To prevent firedamp explosion by electrical switching operation in coal mining industry requires implementing intrinsically safe illumination circuit. The luminaire design also needs to be certified and installed properly. The current illumination systems installed inside mines require a lot of energy which is obtained from nonrenewable resources. In this work, the design and implementation of solar-powered optical fiber-based illumination are studied and implemented in the Jhanjra underground coal mine, Eastern Coalfield Limited, and a Li-Fi-based communication system for underground coal mines is proposed. Silicate optical fibers of various core diameters and numerical apertures are characterized for illumination applications and their efficiencies are reported. The possibility of achieving optical fiber-based solar, laser, and hybrid illuminations in underground mines is discussed. The design and fabrication of a Fresnel lens-based solar tracker for solar illumination are also presented. The optical fiber-based illumination system is installed in an underground coal mine and the illumination of over 70 lux is achieved at the work plane. Finally, optical fiber-based illumination and simultaneous basic Li-Fi communication are demonstrated and will be beneficial to the underground coal mining industry.

Apr 14, 2023

By Avula Rajashekar Yadav, Sreenivasa Rao Islavath

Barrier pillars and gateroads play a vital role for the safe exploitation of coal from the panel in the longwall workings. The barrier pillars and gateroads are subjected to the front abutment and side abutment loads during the retreat of the panel. These structures may fail if the developed load on them is higher than their strength. The stability of the longwall structures such as barrier, gateroads and face is paramount in extracting the coal from the panel safely. For this, a deep longwall mine in India is chosen for the study using a 3D numerical modelling technique. In this paper, three critical conditions such as scenario 1 (no side goaved-out panel), scenario 2 (with side goaved-out panel) and scenario 3 (with two side goaved-out panels) are taken. For each scenario, five retreat distances such as 100, 125, 150, 175 and 200 m are considered for detailed investigation. The development of vertical displacement in gateroads, vertical stresses on barriers, vertical stress concentration factor, abutment zone and yield zone for longwall face are extracted and analyzed. Also, the safety factor of the barrier and longwall face is estimated considering the Hoek–Brown rock mass failure criterion. From the study, it is observed that the maximum vertical displacement of 121 mm in TG3 at scenario 3 for a retreat distance of 200 m and a minimum vertical displacement of 33 mm in TG2 for a retreat distance of 100 m at scenario 2. The development of vertical stress on the barrier is found to be between 8.78 and 13.40 MPa, and the safety factor of the barrier lies in between 1.56 and 1.80. The study also revealed that the yield zone at the longwall face lies within 2 to 3 m.

Dec 29, 2023

By Raja V. Ramani

Discussion in this section of the Handbook is limited to the working environment of miners, the mine workers themselves, and the machines used in mining (Fig. 11.0.1). The contents emphasize personnel health and safety aspects and engineering design and control practices to ensure a productive health and safety environment. Reference is to the health and safety of the individual miners as well as to the safety of the working environment. This Handbook also contains references to health and safety regulations in Chapter 3.2 and environmental protection in Chapters 3.4 and 7.3.

Jan 1, 2008

By Nikhil Dhawan, SHAILA MIR

The emerging problem of electronic waste has promoted the interest in exploring metal recovery from secondary sources under the umbrella of urban mining. This study presents the physical and chemical characterization of various components present in end-of-life laptops to help ascertain the sites of metallic values and develop sustainable and environment-friendly recycling. The recycling potential of a laptop is evaluated by sequential disassembly, separation, and characterization of components such as body (49.8 wt.%), printed circuit board (9.7 wt.%), hard disk drive (4.9 wt.%), and battery (12.4 wt.%). The printed circuit boards comprise metallic values, majorly copper (25 wt.%), tin (5.8 wt.%), and lead (3.1 wt.%). The precious metals (Au, Ag) with an economic advantage are abundantly present in electronic components such as integrated circuits, capacitors, resistors, and processors. Critical elements such as lithium, cobalt, and rare earth elements are detected in the discarded laptops' batteries and hard disk drives. The recycling potential representing the amount of material that can be recycled in various components, depending on the type, concentration, and purity, is determined in the range of 36–100%. On average, a unit laptop contains~ 386 g of Cu (14.45 wt. %), 49.73 g Co (1.86 wt. %), ~346 mg Ag, ~141.2 mg Au, ~650 mg of rare earth elements (Nd, Dy). This study presents a database for investigating integrated and economical recycling techniques from different components of a laptop, and an overall process flow is also proposed.

Jul 24, 2021