Search Documents

By J. H. Kelley

In this paper, we show that the methane emission and the dust generation in under-ground mining currently and in the future pose operational, health and safety conditions which adversely Impact face productivity and worker satisfaction. One solution is the use of a dual-aircourse system of ventilation. In this concept, one aircourse captures and exhausts to the surface the dust generated and the methane emitted in coal/mineral fragmentation while a second aircourse provides workers with cleaner air for breathing and comfort. Various dual-aircourse configurations adapted to the Variable Wall Miner are analyzed and compared with conventional mining in gassy seams, indicating a marked reduction in the required air quantity and the number of aircourses.

Jan 1, 1996

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

Following the recession of 2001, restrained consumer spending, declines in domestic manufacturing and industrial output, and increased unemployment led to a lack-luster year in the domestic economy. In 2002, the U.S. real gross domestic product (GPD) grew only 2.4%. Significant production declines in the U.S. metals industry were registered by copper, lead and zinc producers. Steel producers, despite a slight improvement in shipments, continued to face strong foreign competition, higher energy costs and lower prices for their products. Homebuilding and other domestic construction sectors— major consumers of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above 2001 levels. A strong U.S. dollar relative to other national currencies continued to weaken the competitive stance of U.S. metal and non-metal mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2003

By Xiaohong He, Qing Yu, Kaixiang Zhang, Rui Guo, Minghua Lin, Haoyu Miao

With the increasing depth of coal mining, the coal mine shaft traverses’ strata conditions become more and more complex. Shafts are often located in deep thick strata with unstable aquifers, and coal mining requires short-term rapid drainage of aquifers; the additional stress caused by aquifer water drainage is the direct cause of the shaft-lining failure. Over the years, many experts have conducted research on the shaft-lining damage caused by the consolidation and subsidence of the soil layer induced by the long-term drainage of the aquifer. On this basis, this paper conducts an in-depth study of the dynamic change of the pore water pressure of the aquifer in the short-term drainage and its influence on the response of shaft-lining strain and surface subsidence. The result shows that the Mandel effect of pore water pressure around the shaft-lining is obvious at the beginning of drainage, and the pore water pressure suddenly increases; the increase is independent of the drainage rate, which leads to the sudden increase of the shaft-lining strain value unrelated to the drainage rate. The result also shows that with the gradual dissipation of pore water pressure, the increase of shaft-lining strain is positively related to the drainage rate and negatively related to the drainage distance, and the variation trend of horizontal strain is greater than that of vertical strain, which appoints the main cause of shaft-lining damage.

Mar 16, 2023

By A. D. S. Gillies

Loss of visibility due to the occurrence of atmospheric fogging in underground mine airways can lead to a reduction in travel times and loss of production efficiency, an increase in the frequency of vehicular and foot traffic accidents and difficulty in checking rock surfaces for instability and loose material. Where hot and humid surface air meets colder underground air, conditions for fog formation nay be present. Further, suspended particulate matter from diesel exhausts or stoping operations together with slow movement of air along passageways nay contribute to formation. The study describes an investigation being undertaken with the cooperation of Kennecott's Ozark Lead Company to identify causes of the problem.

Jan 1, 1982

By R. Schlüter

"The “Biohydrometallurgical Center for Strategic Elements (BHMZ)” is a cooperation of 13 departments of the Technical University Bergakademie Freiberg fostering interdisciplinary research along the whole (bio-) hydrometallurgical process chain to extract indium and germanium from sulphide ores. Research comprises methods to (i) bring the respective metal from the source material into aqueous solution and (ii) different approaches to extract pure metal or metal-containing materials from the solution. Within the BHMZ the Department of Underground Mining Methods deals with the design and implementation of an underground testing facility for bacterial in-situ stope leaching in its own “Research and Educational Mine”. The intention is to investigate innovative approaches for leaching technologies by crack initiation due to hydraulic fracturing or water pressure blasting under consideration of leaching kinetics and underground conditions. It is planned to set up two testing units comparing energy input and the metal output of conventional (blasting) as well as one of the innovative technologies. Aim of subproject is to establish an innovative and sustainable method ready for up-scaling. BACKGROUND Metals like copper and zinc mainly occur as sulphide ores in nature. Due to the insolubility of these sulphide minerals the respective metal is commonly extracted by pyrometallurgical processing methods. These methods require several steps of enrichment of concentrates such as flotation and roasting (Figure 1) under extensive energy utilization. Additionally, this arouses the emission of sulphur dioxide gas which can have a negative impact on the environment in form of acid rain, as long it is not caught by sulphuric acid facilities (Schippers et al. 2011). However, to treat the ore on the surface either open pit or underground mining operations are necessary. This implies operation steps from excavating, loading, and conveying/hauling, to dumping with the sub-processes crushing and stashing. Due to the tendency of increasing depth, more complex ores and decreasing ore grades of the mineable deposits as well as increasing energy and environmental costs these conventional mining and processing methods become in general more costly and difficult to apply. Hence, hydrometallurgical processes and especially the suitability of bioleaching as an alternative in-situ method for future mining projects should be examined. Leaching by means of microorganisms is a combination of mining and processing by converting the insoluble metal into an aqueous form. This technology is an economically beneficial and environmentally friendly alternative to pyrometallurgical processing methods especially for primary and secondary low grade ores. Mainly the extraction of copper but also of zinc and lead from sulphide ores is state-of-the-art in surface leaching operations like heap and dump leaching (Figure 1)."

Jan 1, 2015

By Isabel F. Barton, Matthew J. Gabriel, CARSON ROBERTS, JOHN LYONS-BARAL, LEON DUPLESSIS, Mark D. Barton

Geometallurgical assessment of orebodies in the mining industry typically relies on bench-scale or lab-based characterization techniques. In this study, we investigate drone- and tripod-based field hyperspectral imaging as a potential addition to the geometallurgy toolkit in multiple applications. This pilot study tests hyperspectral imaging for largescale mineral mapping in and around the active Lisbon Valley copper mine, including natural exposures, previously producing U-V mines, highwalls, dumps, and leaching sites. Tests include different (supervised and unsupervised) mineral data classification methods, varying mineral spectral reference libraries, comparison with ground-truth geological and spectroscopic mapping and sampling, and integration with LiDAR data. The results show that hyperspectral scans can produce spatially registered maps of the distribution of different spectrally active mineral types over dumps, highwalls, leach pads, and natural outcrops. Clays, other phyllosilicates, carbonates, and sulfates showed up particularly well. The sensor was also able to distinguish dry from lixiviant-saturated areas and map different clay types on the leach pads, and shows promise for differentiating types and health of vegetation. These results suggest that hyperspectral imaging, if coupled with robust ground-truthing, can be a useful complement to existing geometallurgical techniques in the mining industry, such as geological mapping, blast hole sampling and automated mineralogy identifications, and handheld spectrometry. In particular, hyperspectral imaging has promise for mapping the distribution of acid-consuming minerals; mapping the distribution of swelling, sliming, and heap-blinding clays; and pinpointing problem areas on heap leach pad surfaces.

Feb 10, 2021

By M. Bai

The influence of mining on the hydro-geomechanical environment is greatly constrained by alternating mining geometries. The limiting magnitudes of surface subsidence and groundwater flow over the mining area, as a result of geometry changes, can be reasonably predicted through a coupled finite-element model introduced in this paper. Verification of the model has been tested using real and conceptual case studies which reveal that changes in strata conductivities are strongly related to the strata deformation induced by mining. The greatest modification of hydraulic conductivities occurs within the caving or severely fractured zones. The study indicates that narrowing the panel face width will substantially reduce both the intensity and extent of mining damage to the overlying strata, limit surface subsidence and constrain the change in hydraulic conductivity to a reduced scale and smaller extent, particularly as mining depth increases.

Jan 1, 1993

By Michael S. Moats, John Bailey Fletcher

The performance of grinding media can be misrepresented in marked ball wear tests due to galvanic interactions between dissimilar media. The possible galvanic interaction of media materials during marked ball wear tests has not been adequately explored. Corrosion rates and potentials of modern high carbon steel and high chromium white iron grinding media materials were measured using electrochemical testing as a function of pH and chloride content in a simulated mill water. The results replicate previous research with the high chromium white iron sample being more noble (higher corrosion potential) and corrosion resistant (small corrosion current) than high carbon steel. Using the experimental data and corrosion theory, the effects of galvanic coupling on corrosion rates were calculated to examine what could happen during a marked ball wear test or when a mixed media charge is present. This analysis indicates that high carbon steel can cathodically protect high chromium white iron leading to significant decreases in the corrosion rate (up to 99%) of this material during marked ball wear tests. The magnitude of the protection is a function of the pH of the mill water.

Dec 21, 2022

By Gary N. Weinrich

Large surface mining projects in sparsely populated regions of the West have the potential to create disruptions in an area's social and economic character with potential effects on man that can far outweigh the physical and ecological effects on man's environment. The data and analyses involved in addressing the socioeconomic issues are additional to those traditionally associated with surface coal mining, such as those concerning land reclamation and water quality. Appropriate socioeconomic studies in conjunction with mine-planning can identify the potential problem areas in order that project measures can be taken to maximize the beneficial impacts and minimize the adverse effects of surface coal mining. The information required to conduct such socioeconomic analyses, available data sources, and the applicable analyses are described. Overall impacts of some proposed Western surface mines are summarized and potential mitigating steps discussed.

Jan 1, 1975

By K. Avarmaa, P. Taskinen

"The solubilities of rhodium (Rh) in a molten silver alloy in doré-smelting conditions for treating copper refinery slime at temperatures of 1,000 to 1,300 °C were measured using a high-temperature equilibration-quenching technique and direct phase analysis by electron probe X-ray microanalysis. The results obtained indicate that the solubility of rhodium in molten silver is very limited: only 0.04 to 0.26 weight percent at 1,000 and 1,300 °C, respectively. The thermodynamic properties of rhodium in molten silver were estimated from the solubility data. The compositions of the solid rhodium alloys in equilibrium with molten silver-rich doré metal were also measured in this study. The excess rhodium in the doré alloy will precipitate during the refining as solid, greater than 99 weight percent Rh.IntroductionSilver refining is a core step of the processes of anode slime treatment and precious metals recovery in copper refineries (Hait, Jana and Sanyal, 2009; Ludvigsson and Larsson, 2003). It separates the oxidic materials, such as nickel oxide (NiO) and barium sulfate (BaSO4), from metallics after the de-coppering and de-selenation steps of the anode slime, and refines the silver bullion from the undesired elements present (Cooper, 1990; Hyvärinen, Lindroos and Yllö, 1989). Doré metal is a silver-rich alloy which after the smelting step will be refined electrolytically, and the remaining constituents of gold as well as the platinum group metals (PGM) will be subsequently recovered in their own processing stages.Because of low concentrations of PGMs in copper, they are typically soluble in the doré metal in anode slime treatment. This can be concluded from their binary phase diagram data with silver (Massalski et al., 2007). One exception is sometimes encountered in the anode slime smelting operations if the smelter feedstock is rich in rhodium, as may be the case if the raw materials contain secondary raw materials such as e-scrap. The solubility of rhodium in solid silver is less than 0.04 weight percent (Królas and Sternik, 1995), and its solubility in molten silver is highly uncertain. The only experimental information in the literature (Królas et al., 1993; Elliott, 1985) suggests that the silver-rhodium alloy system at 960 °C forms a eutectic, which locates less than 2 °C below the melting point of pure silver (Arblaster, 2015). Early observations (Rössler, 1900) propose that rhodium is insoluble in molten silver even if solid silver-rhodium solutions have been recently produced on a nanoscale (Kusada et al., 2010).The aim of this study is to measure experimentally the solubility of rhodium in molten silver at doré metal smelting and refining temperatures. The silver alloy used to mimic the doré alloy contained silver and about 1 weight percent of the alloying elements copper, gold, palladium, rhodium and tellurium. The experiments were carried out in metal-slag equilibria with nitrogen-oxygen mixtures as the atmosphere, employing an equilibration-quenching technique and using direct phase composition analysis by electron probe X-ray microanalysis (EPMA) (Jak, Hayes and Lee, 1995)."

Jan 1, 2017

By CADEN VITTI, Barbara J. Arnold

Mine tailings, the byproduct of mining and mineral processing, are increasingly mass produced as a result of increased demand for metals and minerals as well as the advancement in technology that allows for the exploitation of lower-grade ores. Lower grades can increase the volume of tailings that may contain new gangue minerals that should be evaluated for the presence of critical minerals and other valuable metals. The practice of reprocessing, while relatively new, is crucial to reducing environmental damages, obtaining valuable critical minerals from waste, and contributing to more sustainable repurposing and disposal methods. With the increase in tailings dam failures in recent years, there is a large motivating factor in remining and removing the potential hazard to benefit the safety of potentially impacted communities. In analyzing the perspectives of various domestic and international studies, this literature review will determine the feasibility of reprocessing and reutilizing mine tailings waste for a more sustainable future while exploring current practices that have benefitted ecosystems and communities.

Jan 1, 2022

By Chuang Sun, Feng Luo, Guo‑dong Li, Xue‑qing Li, Tuan He

The mining-induced failure of the coal seam floor is essential for water inrush. The mining disturbance to the floor, especially in the thick coal seam, is severe, and the water inrush risk is also higher than that in regular thick coal seam excavation. The superposition of many stresses, including in situ stress, mining-induced stress, and confined water pressure, must be considered in the prediction of the floor failure depth. This study adopted the elasticity analysis, FLAC3D numerical simulation, and on-site acoustic wave test comprehensively. The thick coal seam working face of the Zhong-Yu coal mine affected by confined water was selected as the engineering background to study the characteristics of the floor failure. Based on elastic foundation theory and the superposition principle, the mechanical model and the failure depth criterion of the floor were established, respectively. The distribution and evolution of mining-induced stress and the plastic zone in surrounding rock during the mining process are obtained by FLAC3D. In addition, the changes in the P-wave wave velocity in the floor before and after mining were compared and studied by the acoustic wave test method. The range of floor damage depth is determined on the basis of the above research.

Jun 8, 2022

By T. E. Masoner

The struggle to get the minerals industry seriously interested in high intensity wet magnetic separation* has been difficult. The high capital cost of the equipment, the lack of basic research, the lack of operating information, and the diverse characteristics associated with different minerals and ores have prevented the development and use of HIMS-W on a wide scale. The Climax Molybdenum Company, a Division of American Metal Climax, Inc., located at Climax, Colorado, was among the first companies in the Americas in recent years to support the development of HIMS-W to recover weakly magnetic minerals on a large scale. The Climax Molybdenum Company, one of the world's largest underground mines, processes about 40,000 tons per day of ore, from which about fifty million pounds of molybdenum disulfide are produced each year. By-products include tungsten, iron pyrite, tin, and some monazite.

Jan 1, 1968

By J. D. Miller, C. L. Lin

From mine to mill, the 3D characterization of particles ranging in size from meters to micrometers is now possible. A brief review of X-ray tomography for mineral processing is given with recent advances considered, such as high-speed scanning and image analysis procedures to describe important particle properties, including size, shape and composition. Considering these new 3D characterization tools, applications in mineral processing are discussed for high-resolution X-ray microtomography (HRXMT) laboratory analysis of particles ranging from 20 mm to 5 μm, with a voxel resolution of about 1 μm, including (1) multiphase particle characterization by HRXMT and comparison with scanning electron microscopy (SEM), (2) particle damage state as a result of blasting/comminution, (3) liberation characterization to describe expected separation efficiency, (4) exposed grain surface area analysis to explain the flotation of locked particles, and (5) floc size, shape and water content for polymer-induced flocculation. Finally, applications in mineral processing for plant-site analysis using high-speed X-ray computed tomography (HSXCT) are examined, including, for example, coal washability analysis, the analysis of crusher plant products, and the analysis of pebble phosphate products from central Florida. Scanning rates on the order of 1 kg/min for particle sizes ranging from 150 mm to 1 mm are possible, with a voxel resolution of about 100 μm. For coarse particles smaller than 5 to 10 mm, high scanning rates of more than 300 t/h may be possible at a voxel resolution of about 1 mm.

By A. Bhargava, V. Nasri

Traditionally, secant piles have been utilized to provide temporary support during excavation for shafts and cut-and-cover tunnels. As an alternative, the secant piles can be included into the permanent structure, where they serve as the envelope sustaining the lateral loads and gravity of the permanent structure in addition to supporting the excavation during construction. This has several benets, such as shorter building times and lower excavation costs. Recent construction of an approach structure and an underground station as part of Montréal, Canada’s Réseau Express Métropolitain (REM), one of the biggest transit systems in North America, was completed with remarkable success using this. In this paper, a case study based on a project that employed secant piles as the permanent liner is presented. Techniques to guarantee a watertight construction with over a century of service life are described, along with a variety of structural and waterproong methods applied to create an economical design.

Jun 23, 2024

By Cesar Carrasco, Heath Arvidson, Mark Forster

Block models built to represent the geology and rock characteristics of mineral deposits represent huge complex data sets, which form the basis of strategic and business planning, and public reporting of Mineral Resources and Mineral Reserves. Recent advances in cloud computing and database technology developed for the Internet of Things offer a different way of working with these critical data sets. Enabling a cloud based, open data structure with high performance data analytics capability presents a compelling improvement in governance and a democratization of ore body knowledge that can lead to automation use cases that support the digitalization of mining.

Jun 25, 2023

By J. Noll, C. DeGennaro, C. Zhou, J. Srednicki

"The personal dust monitor (PDM) (model PDM3700), as well as other electronic devices, can cause electromagnetic interference (EMI) which can disrupt the operation of some proximity detection systems (PDSs). A 15 cm (6 inch) minimum separation distance between the miner-wearable component (MWC) of the PDS and the electronic device usually avoids these disruptions, but due to the amount of equipment on a miner’s belt and the method of wearing the PDM in some situations, this distance can be difficult to always reliably maintain. Another method of reducing EMI effects is utilizing magnetic field shielding. The shielding capability of several different materials was investigated by surrounding the PDM with the material and quantifying the EMI. A copper mesh pouch reduced the EMI from a PDM3700, allowing a minimum separation distance of 10 cm (4 inches) instead of 15 cm (6 inches) as shown in a previous study for an unshielded PDM. A MU-metal box had a better shielding effectiveness, as it further reduced the minimum separation distance to less than 7 cm (2.8 inches). Shielding reduced the EMI of the PDM with MU-metal providing better results than the copper mesh. These materials may be beneficial for shielding individual components of the PDM or for constructing a shielded pouch. However, before the advantages of a shielded pouch can be determined, the effects of just the shielding material (metal) on the PDS needs to be quantified. INTRODUCTION According to statistics from the Mine Safety and Health Administration (MSHA), 43 miners have been fatally struck or pinned by a continuous mining machine (CMM) since 1984. In an effort to prevent future striking and pinning fatalities from occurring, proximity detection systems (PDSs) have been developed and are required on all operating CMMs in underground coal mines, with the exception of full-face CMMs, by 2018 (MSHA, 2015)."

Jan 1, 2018

By Richard C. Corson

The new 9300 TPD sinter plant being built for China Steel Corporation is incorporating the latest computer technology for plant control systems. The control system will use a central computer and distributed micro-processors to control instrument loops and switching logic in the blending yard and sintering plant. All plant functions, including combustion and fan controls, will be controlled by remote microprocessors located throughout the plant, and connected by a communications link to the centrally located computer and control room. The design, programming, construction and operation of a microprocessor based control system presents new challenges to the control engineer. With microprocessors in the control system, more power exists in the individual control loop and many supervisory functions may be added at the loop level. The specification of the microprocessor system and the resolution of hardware design and control system design can lead to development of powerful systems capable of higher level control and optimization functions

Jan 1, 1981

By Malte J. M Gurgel

Subsurface spatial planning is becoming increasingly important in view of competing underground applications. This development is influenced by global agreements to reduce greenhouse gas emissions. Therefore, precise knowledge of the underground space is a basic prerequisite for future applications. The three-dimensional registration and reliable georeferencing of underground infrastructures can establish a holistic geodata basis for such tasks. Those tasks are discussed both for the development of energy projects such as deep geothermal energy as well as for storage applications. Research on geothermal energy has been carried out at RWTH Aachen University as part of the SuperC project in a license field in the Aachen area since 2001. Recently, this research has been extended to include monitoring aspects in the overlapping GEObservatorium Aachen field. The documentation and visualization of underground activities using photogrammetric methods like Structure from Motion is discussed based on recent research in sites for the final disposal of radioactive waste. Finally, both applications provide an outlook on supporting underground projects by using high-resolution geodata.

Feb 1, 2025

By D. Wenstrup, K. Perry, J. Hatfield, P. Sainato, B. Lusk

Concrete-infused cloth is used in several civil and mining surface applications whose circumstances are similar to some of those in underground mining. A feature of this material is that it cannot be overhydrated. In underground conditions, however, the excess supply of water to the cloth for hydration could lead to muddy and potentially unsafe working conditions, as well as resource wastage by supplying more water to the construction site than is needed. The objective of this study is to verify the water-to-cloth ratio and study the effect of hydration level on the strength of the Concrete Cloth product. We found that the strength increases with increased hydration up to a 1:2 water-to-cloth ratio by weight, after which the strength holds steady regardless of additional hydration. This confirms the 1:2 water-tocloth ratio by weight for hydration and confirms that strength is retained even if the cloth is excessively hydrated.

Jan 1, 2014