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By B. H. Kim, S. J. Schatzel, K. M. Ajayi, G. S. Esterhuizen, D. W. H. Su, Z. Khademian

The stability of shale gas wells drilled through current and future coal reserves can be compromised by ground deformations due to nearby longwall mining. Depending on the longwall-induced rockmass permeability, the high-pressure explosive gas from the damaged well may reach mine workings and overwhelm the mine ventilation systems. This study uses geomechanical models to estimate the rockmass permeability induced by mining. A two-panel longwall model of a deep, 341-m-cover mining site in southwestern Pennsylvania is constructed in 3DEC to explicitly model the rockmass by a Discrete Fracture Network (DFN) technique. Stress-induced fracture apertures and permeabilities are calculated across the model and are validated against permeability measurements. A Fracture Flow Code (FFC) is developed to use these results to predict potential inflow to the mine should a gas well breach occur. One hundred DFN realizations are simulated, and the results show that for a gas pressure of 2.4 MPa, the average of the predicted inflow rates to this deep-cover mine is 0.03 m3 /s, significantly lower than the average inflow of 0.92 m3 /s for a shallow-cover mine (145 m deep) studied in the previous work (Khademian, et al. 2021). The result can help assess the potential hazards of a shale gas well breach for mine safety and evaluate the ventilation requirements to mitigate the risk

Mar 2, 2022

By W. C. Patrick

Introduction The availability of a thorough, simple-to-use roof fall classification system is desirable for several reasons. First, such a system would expedite the reporting of falls for the purposes of estimating material removal costs, analyzing damage levels, and complying with federal regulations to report falls in certain areas of the mine. Second, the classification system would allow the mining engineer to record falls routinely with little time and effort expended. This would encourage him to make observations concerning what type of roof support would work best in a given situation. Third, and probably most important, an adequate roof fall classification system is the first step toward developing a means of predicting the occurrence and extent of future falls. It was with these three reasons in mind that the following classification system was developed. The type of classification chosen reflects the background of the developer and the intended purposes of the system. Hylbert has proposed a geologic-based classification which groups falls as to structural and compositional origin. The need for similar systems is noted by Cox and by Ferm and Melton. Each of these researchers is confronted with a situation requiring a relationship between local geology and roof fall occurrence. Such a relationship would allow the prediction of the relative frequency of falls from a knowledge of local geologic features. The current research is aimed at fulfilling somewhat different requirements, as noted above. Fall geometry has been chosen as the basis of the classification system so fall type can be reported independent of local geological, environmental, and tectonic conditions. This approach parallels that used in the common slope failure classification with groups failures relatively independent of

Jan 1, 1977

By Louis D. Murino

Compared to coal or many metals industries, talc must be considered a small, specialty market catering to niches and dependent primarily on the physical attributes of the mined and processed mineral rather than the chemical attributes with copper, lead or uranium concentrate, the primary objective is the percent metal that ultimately is refined by the smelter, as opposed to the brightness, particle size distribution, trace impurities or morphology. The latter constitute the important determinants of where, how and why talc and similar industrial minerals are used. This paper addresses the talc market-place: where it is, how much of a market there is, who the producers are, available capacity, market growth, and marketing techniques.

Jan 1, 1984

By Sureshan K. Moothedath

This paper provides a mechanistic representation for floc formation, growth and degradation and presents results from an experimental study of batch flocculation in which step changes were made in the impeller speed, flocculant addition, and slurry concentration. A discussion of the experimental results is included in terms of the mechanisms of floc formation and size-change.

Jan 1, 1993

By Sadatoshi Ohmori, Simin Zhai, Devini Abeyawardena

A road tunnel is planned to be constructed in soft, high overburden ground of around 600 m in Japan by using the center drift advancing method. The dodging effect and early ring closure of the center drift were expected to reduce the displacement and deformation of tunnel and promote safe construction. The measurement result during construction was analyzed and those effects, which the displacement and deformation after the widening excavation decreased and its effect increased as the center drift radius increased, were confirmed by numerical analysis. Also, the effect of the early closure of center drift after widening excavation did not have much effect.

Jun 23, 2024

By Michael Fehler, Hidenshi Kaieda, Leigh House

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and independent1 y confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional we1l 1ogging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we be1 ieve that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrinsic rock properties.

Jan 1, 1986

By A. Palit, M. K. Mohanty

This investigation has concentrated on optimizing the newly developed Pansep linear screen and developing empirical models to predict the screening performance. Most empirical models developed in the past to predict the performance for industrial screens are suitable for the vibratory screens. Understandably, these models are deficient in predicting the performance of linear screens due to the difference in their operating principle. Thus, the main objective of this study has been to develop empirical models suitable for linear screens to predict the partition coefficient for a given size fraction as a function of the aperture size. The inadequacy of the conventional model equation originally developed for vibratory screen has been demonstrated and a modified equation developed to predict the partition coefficient as a function of the normalized mean particle size (d/d50c). In addition, new model equations have been developed for linear screens to predict the screening efficiency as a function of the separation size(d50) and to predict the separation size as a function of the screen aperture. It is believed that these model equations will be useful for the plant operators in selecting the mesh panels of correct aperture size and in predicting the product size distribution based on the selected aperture size.

Jan 1, 2003

By K. A. Natarajan

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration, namely, nitrogen, air and oxygen on ball war was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. 'Marked ball grinding, tests along with electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen towards wear (corrosive wear) is relatively small and abrasive wear appears to be significant. Rheological properties of the slurry-appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1983

By A. Iordanidis

Mining activities have recently been taken place in Vourinos mountain, northern Greece, exploiting the so-called ?olivinite?. A representative sample was collected from this mining area. Mineralogical analysis was conducted using X-Ray powder Diffraction (XRD). A thin section was prepared and analyzed under optical microscope. X-Ray Fluorescence (XRF) was employed for the chemical analyses of major, mi-nor and trace elements. Environmental Scanning Electron Microscopy coupled with energy dispersive x-ray analysis system (ESEM-EDX) was also applied for the characterization of the sample. Forsterite (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were the main mineral phases determined by XRD, with a 56% and 44% content respectively. Trace amounts of chromite spinels were also determined. Based on this characterization, the industrial rock proved to be a hartzburgite (a type of peridotite in petrological terms). Optical microscopy and ESEM-EDX provided similar observations and confirmed the above-mentioned results. XRF revealed a composition of 43.31 MgO, 44.25 SiO2, 9.98 Fe2O3, 1.40 CaO, 0.67 Al2O3, 0.22 MnO, 0.01 TiO2 and negligible amount of LOI (<0.1%). Trace elements with high concentrations were Cr (2678 ppm) and Ni (2044 ppm). The comprehensive characterization of this mining product suggested the suitability for various uses, such as refractories, foundry and slag conditioner. Additional experiments are being carried out for environmental applications, e.g. wastewater treatment.

Jan 1, 2006

By Sun K. Kim

Hydrometallurgical processes are not free of environmental regulations. A clear understanding of the regulations under which the minerals industry operates delineates processing requirements at early stages. This paper deals&apos; with federal environmental regulations with emphasis on the hazardous waste regulations promulgated in May, 1980. The procedure of EP toxicity test and an example of the test are described. Brief account is given of the current trend and future outlook of regulations.

Jan 1, 1982

By H. Para, A. Aguirre, G. Artadi

Mining is a very important economical activity in Peru which has been recently developed without considering environmental aspects. Here, we show an experience at the Milpo mine, situated 4,200 meters above sea level; a mining company that has the value of being one of few from the last decade that is engaged in consolidating a model of environmental protection. The model includes aspects of contamination prevention and control, with bioindicators such as pasture cultivation, vegetables, forests, and hydrobiological species breeding. Socially, through means of development programs in natural areas, forestation and support to rural agriculture, together with environmental education, it is being demonstrated that it is possible to ensure tangible results in environmental conservation and the well-being of the populations around the mine.

Jan 1, 1998

By Charles A. Maliszewski, James M. Galvin, Gerhard Urschitz

With obvious signs of deterioration, the double track, historically registered Bergen Tunnels as part of the commuter rail system in New Jersey waited for rehabilitation for a long time. Serious water in filtration not only caused operational and safety hazards for the electrified rail line but also deteriorated and structurally compromised the tunnel lining. An innovative rehabilitation program was developed to enlarge the tunnel and to provide a new waterproofing system and final lining. For the rock excavation and support New Austrian Tunneling Method (NATM) principles were utilized, while water tightness was achieved by installing a PVC membrane waterproofing system followed by a reinforced cast-in-place final lining. Experienced on-site supervision generated additional savings during construction by streamlining support elements based on geologic conditions encountered.

Jan 1, 2003

By Ihsan Berk Tulu, Mustafa Can Suner

The synthetic rock mass (SRM) approach is a relatively new method to study the mechanical behavior of rock masses. Recently, an SRM approach was established to estimate pillar strength from laboratory scale to in-situ dimension using the two-dimensional Universal Distinct Element Code (UDEC). In this study, the developed methodology is applied to the S-Pillar database to estimate pillar strength and failure mechanisms as a function of width-to-height ratio of the pillars. First, stone mine rocks are categorized into three as low-, medium-, and high-strength according to their uniaxial compressive strength (UCS). Later, laboratory-scale intact rocks are scaled-up to the average in-situ pillar dimensions by explicitly considering the naturally existing joint sets. It is found that the strength of the pillars with low-UCS are overestimated when compared to pillars with high-UCS. This observation is attributed to the high joint density of the pillars with high-UCS. After obtaining in-situ pillar strength, the width-to-height ratios of the pillar models varied from 0.5 to 2.0 to gain a robust understanding of pillar mechanical behavior. Tensile failure is found to govern the pillar behavior with the width-to-height ratio of 0.5 while the combination of tensile failure in rib elements and shear failure in the core

By Robert C. Freas, Donald D. Carr, Lawrence F. Rooney

Perhaps no other mineral commodities in this volume have as many uses as limestone and dolomite. These carbonate rocks are the basic building blocks of the construction industry, the material from which aggregate, cement, lime, and building stone are made. Carbonate rocks, and their derived products, are used as aggregates, fluxes, glass raw material, refractories, fillers, reactive agents in sulfur-oxide removal, abrasives, soil conditioners, ingredients in a host of chemical processes, and much more. Although the use of limestone and dolomite goes back before recorded history, new uses and products are continually being found. Carbonate rocks form about 15% of the earth&apos;s sedimentary crust and are widely available for exploitation. Found extensively on all continents, they are quarried and mined from formations that range in age from Precambrian to Holocene. Reserves of carbonate rock are large and will last indefinitely, although high-purity deposits may be absent or have limited availability in certain areas. Limestone and dolomite are so useful and so abundant that in 1989 about 798 Mt were produced in the United States. In fact, about 75% of all stone quarried or mined in the United States was carbonate rock. Sand and gravel was the only mineral commodity produced in greater quantity. In this chapter we have sought to provide the general reader an overview of carbonate rocks, their composition, distribution, production, and uses. The literature on the limestone and dolomite resources of the United States and Canada is so vast and diverse that one can easily become mired in print. We tried to list those references that are easily accessible and that provide the economic geologist with a starting point for more intensive study. The table listing selected references on limestone and dolomite resources in Canada and the United States reflects our attempt to be selective rather than exhaustive and to direct the reader to the best sources of detailed information.

Jan 1, 1994

By C. J. Hall

An investigation of multi-shaft airflow problems by the author in 1976 (1) was presented in the hope of arousing considerable written comment, but in fact-. only one contribution (2) was forthcoming. The investigation in this paper is taken several stages fur¬ther, because the matter is of major importance in many American hard rock mines with complex networks extending over thousands of meters vertically. The examples used have all been generated thermodynamical¬ly and checked by motive column (denisty) calculations. Dry air has been used to reduce the amount of time spent on the rather complex calculations, but it has been shown (3) that the principals developed apply equally well to air/vapor/water mixtures. Initially the subject is investigated using both thermodynamic and motive column analyses. The latter part of the paper concentrates on a motive column presentation. Both methods are, of course, equally valid and give identical answers to any situation when correctly applied, as is shown in the worked examples.

Jan 1, 1980

By Steven J. Kirk

In the past decade, many hardrock surface miners have revegetated dumps and tailings ponds to allow those waste disposal areas to blend more easily with the surrounding landscapes. Efforts have also been made to more creatively use the flat land resulting from the disposal of overburden and tailings. However, the mines which serve the best post-mining land uses are those that have been preplanned to incorporate such end uses. To more fully explore such a philosophy, interdisciplinary team from The University of Arizona conducted a study during 1974 and 1975 of six open pit copper mines in the Santa Cruz River Basin south of Tucson, Arizona for the purpose of investigating both interim and end-use possibilities for mine waste disposal areas. Among other reasons for the study, it was felt that alternatives for such waste areas would be more socially acceptable than barren dumps or tailings ponds. The team, known as the Mines Project Group, consisted of architects, engineers, and hydrologists. As it would have been economically infeasible to move the existing waste rock dumps or tailings ponds, preplanning was limited to the disposal of waste generated after the inception of the project. To better present their concepts, architecture professors Kenneth Clark and Fred Matter constructed a large-scale cardboard relief model of the mines and the surrounding Santa Cruz River Valley (1). The model was built at a scale of 1:12 000 (1 in = 1000 ft) with 30.48 m (100 ft) contour intervals and covered an area of 40.23 km by 32.18 km (25 miles by 20 miles) in scaled area. The mines being studied were cut into the model, but the proposed waste dumps and tailings ponds were built separately so different disposal configurations could be evaluated.

Jan 1, 1980

By S. Renslow, G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Clays are known to contribute to a wide range of mineral processing challenges. These challenges can haunt a plant from the pit, through the beneficiation plant and even to the tailings pond and process water. Each step that the clay is present potentially experiences significant and costly impacts to the process efficiencies. The effect of clay minerals on the performance of phosphate flotation was investigated. The investigation led to an understanding of the movement of clay through the beneficiation plant, the impact on reagent usage, and the overall flotation performance. INTRODUCTION With the decline in mineral feed grades, mineral processing will continue to face challenges. One significant challenge would be obtaining high recoveries of industry specified quality mineral concentrates with lower quality raw minerals. Other challenges may be the handling of the excess tails and process water being produced to maintain a mill’s production volumes. For example, increased levels of clay have been, and will continue to be, a topic of concern for many mines. Some of these concerns include environmental regulations associated with water storage and discharge, as well as beneficiation. Gonglun Chen reported that clays produced in the phosphate industry are generally colloidal and fine (90% < 45 µm) (Chen, 2006). As such, these clays can take 20-30 years to settle, in the absence of polymeric assistance. The settling of these clays is essential as an accidental discharge can lead to substantial impacts to the wildlife and ecosystem. The Environmental Protection Agency (EPA) has referenced cases where the discharge of water can result in fines in the tens of millions of dollars, and at times causing the processing plants shut down, depending on the volume and quality of this discharged water (EPA, 1997). The turbidity discharge criteria will vary from state to state. Florida’s Department of Environmental Protection has listed a turbidity maximum of 29 NTUs, or 60 mg/L total suspended solids, above the natural background condition (Florida Department of Environmental Protection, 2016). A lot of the literature has been focused on the impact of high levels of clay (>10%) on mineral processing. Farrokhpay has reported the significant impact of clay minerals on froth stability in copper flotation (Farrokhpay, 2012). He reported that clays can form a hydrophobic slime coating on the surface of bubbles, which can yield an increase in froth stability. Clay concentrations as low as 5% can have significant impacts on the rheological properties or slurry viscosities. Increased slurry viscosities can lead to either elevated pumping/processing energies being required, decrease in flotation efficiencies due to a decrease in bubble mobility through the pulp, or decreased throughput to manage these viscosities (Tu, 2005; Farrokhpay, 2013; Burdukova, 2014)."

Jan 1, 2017

By David M. Spatz

Ore deposit models are defined largely by physical geologic features that relate conveniently to remote sensing. New Landsat, SPOT, RADARSAT and other multispectral and hyperspectral sensors with improved spatial resolution are currently in development. Near-infrared and thermal airborne hyperspectral scanners hold outstanding promise for both mineral exploration and feasibility stage mapping at potential new mining projects. These scanners are capable of identifying silicification, differentiating silicate alteration types, and mapping compositional variations within igneous and metamorphic complexes. Research in &apos;mineral and rock spectrometry is helping to advance applications of remote sensing. Hyperspectral scanners are capable of differentiating compositional variations within individual mineral species. Innovative data processing techniques continue to enhance computer software applications and facilitate imagery analysis by the geologist. Today, . remote sensing imagery is commonly integrated with multiple data sets in GIS format to form the core data base for regional exploration programs.

Jan 1, 1995

By John F. Papp

Chromite is used both as a metallic and nonmetallic mineral. Chromite ore is used as the source of chromium by the metals industry and is used, without chemical alteration, in the refractory and foundry industries. Chromite ore is also the source of chromium for the chemical industry. On average worldwide far more chromite ore is used by the metallurgical industry than by any other industry. Thus, although the primary purpose of this chapter is to describe the nonmetallic uses of chromite, the metallurgical uses must also be discussed in order to provide a complete description of this commodity.

Jan 1, 1994

By C. P. Shen, H. C. Tsai, Bennie Chu, Y. S. Hsieh

The Pinglin tunnels are situated within the fold-and-thrust belt structural region in Taiwan, due to continent-arc collision and plate tectonic setting. The pilot tunnel TBM (§=4.8m) became stuck ten times with the standstills to date. The westbound main tunnel TBM (§=11.74m) was buried in a collapsing calamity. The main tunnel TBM shall identify and overcome the adverse geology with high volume of ground water ingress itself. This paper presents our experience and methodology through the adverse geology with Pinglin large TBM.

Jan 1, 1999