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By S. M. Hossaini, M. Ataei, H. Moosavi

The abstract highlights the importance of pillar stability in underground coal mines and the influence of rock mass strength and joint orientation on pillar behavior. The study employs numerical modeling using the distinct element code (UDEC) to investigate the impact of these factors on pillar stability. The research considers different joint orientations and varying rock mass strengths, analyzing parameters like stress distribution, displacement, and failure patterns. The findings reveal that both joint orientation and rock mass strength significantly affect pillar stability, with specific combinations leading to reduced safety factors and increased deformation. The study concludes by emphasizing the importance of considering these factors in pillar design for safe and efficient mining operations.

Apr 4, 2022

By T. S. Lundström, B. D. Marjavaara, I. A. S. Larsson

"The flow field in a rotary kiln, used in an iron ore pelletizing process, was investigated using a three-dimensional computational fluid dynamics model. The model is isothermal, downscaled and simplified. The objective was to examine the possibility of capturing the unsteady motion of the flame seen in the real kiln. The results from the simulations were compared with recorded images of the real process. The results demonstrate the possibility of quickly getting an overview of the flow field in the kiln. The main, unsteady behavior of the flame was captured. The model may be used as a tool in the ongoing work of improving and optimizing the pelletizing process.IntroductionThe pelletizing process, in which the crude iron ore from a mine is upgraded into pellets, is a process involving large amounts of hot air flowing in complex geometries. Flow control is a crucial factor in this process to maintain high pellet quality. The rotary kiln is one of the last steps in the pelletizing process, and this is where the pellets are sintered to increase their strength and metallurgical properties. The kiln burner produces a flame that supplies the entire pelletizing process with the necessary heat.Kiln burner flames are large diffusion flames arising from a jet of fuel from the burner issuing into a concentric confining cylinder with a surrounding coflow of air, called secondary air. To enable combustion, the secondary air needs to be entrained into the fuel jet. This mixing of the fuel and air is the slowest step in the combustion process and therefore affects the efficiency of the combustion. The rate of entrainment depends on the momentum ratio between the burner jet and secondary air. The higher the momentum ratio, the faster the entrainment rate and, consequently, the faster is the fuel/air mixing.The kiln of interest in this study differs from kilns used in other industrial processes in both geometry and operating conditions. A distinguishing feature is the large amount of secondary air being induced through the kiln hood and then transported to earlier stages in the process as air or exhaust gas. The secondary air therefore has a substantial momentum, implying that the resulting flow field has a significant impact on the mixing and combustion process in general and the flame shape and stability as well as combustion efficiency in particular. A systematic study of the factors influencing the dynamics of the flow field in the kiln, neglecting the combustion, is therefore justified."

Jan 1, 2016

By Finn Ouchterlony

INTRODUCTION Much of present fracture toughness testing con¬cerns chevron notched specimens (Newman Jr., 1984) since these, in principle, require neither fatigue precracking nor more registration than failure load to determine fracture toughness. Two such specimens which can be made from diamond drilled rock cores with minimal machining are the Short Rod (Barker, 1977) and the Chevron Edge Notch Round Bar in Bend¬ing or CENRBB Specimen (Ouchterlony, 1980). Even if the precracking property is especially valuable for a material like rock, practice has made the relative advantages of these chevron notched specimens much less apparent (Ouchterlony, 1982; Ouchterlony and Sun, 1983). Enough remains, however, to have the Commission on Testing Methods of the International Society for Rock Mechanics (ISRM) focus on them as standard configurations in a "Suggested Method for Determining Fracture Tough¬ness of Rock Material", which is in preparation. This paper presents material which supports the ISRM effort: 1. An experimental compliance calibration of the Chevron Bend (CENRBB or CB for short) and re¬sulting formulas. 2. Specimen tolerances, evaluation formulas, and loading rate requirements relating to both Short Rod and Chevron Bend Specimens of suggest¬ed standard proportions. 3. Some fracture toughness values obtained with the Chevron Bend Specimen. This material is mainly based on two reports (Ouchterlony, 1984 and 1985). CALIBRATION OF THE CHEVRON BEND SPECIMEN Preliminaries The specimen and basic notation is shown in Figure 1 together with a straight notched variety (SECRBB). Subscripts c and s are sometimes used below to distinguish between them. Assuming linearly elastic conditions the load point compliance [ ]

Jan 1, 1986

By Peter C. Badgley

Three tectonic provinces within the Cordilleran System, are analyzed in terms of tectonic framework. (1) Precambrian terrain of North-Central Colorado; (2) The Pacific Northwest; and (3) The San Andreas-Garlock fault system and associated features. In each case a close relation- ship is seen to exist between: (I) Arcuate mountain development; (2) Precambrian basement fabric; (3) Major fault patterns; and (4) Major mineral occurrences. The arcuate trends developed when the basement was still mobile. Later competent deformation rejuvenated pre-existing lines of weakness. Because of the pre-existing arcuate framework, the rejuvenated faults frequently act as conjugate shears (strike-slip faults) flanking the old arcs. The conjugate shears intersect to form wedge- shaped plates. When such plates move forward along boundary strike-slip faults in response to post basement orogenic forces, new secondary fracture systems are generated in the country rock flanking the advancing wedge. The apex regions of the wedges are particularly favorable for detailed exploration.

Jan 1, 1959

By Helmut Mischo

For more than 100 years, diamond mining has been Namibia?s most important mining sector. Today, it provides the highest foreign currency income for the country?s development. Since the late 1970s, offshore mining of diamonds has gained more importance and now more than 60 percent of Namibia?s generally high-quality stones come from those offshore deposits, with a steady increase expected for the coming years. Diamonds in Namibia The mining industry is one of the three pillars of the Namibian economic development, along with tourism and fishing. Diamond mining is one of the two main mining activities in Namibia and diamond mining operations are rapidly moving from onshore to offshore deposits. This article provides a comprehensive overview of the current and future situation of the Namibian mining industry, with a special focus on the tasks and new technical developments for the successful excavation of beach and marine diamond deposits. The different deposits and the adequate applied mining technologies and methods are shown in examples.

Jan 1, 2011

By F. C. Appleyard

As one of the more important Industrials Minerals, gypsum occupies a significant place in the economy of the United States, particularly in that segment which can be loosely called the Construction Industry. For many years, products made from gypsum have been a major building material, and the usefulness and versatility of these products is such that their widespread use is expected to continue. In 1968, according to U.S. Bureau of Mines statistics, the value of all gypsum products sold in the United States was 405,000,000 - and although this value has dipped from the 1964 high of $ 432,000,000, it is expected to trend upward in the next few years to equal and surpass this figure as the construction industry recovers from its current squeeze of "tight money" and high interest rates. There are many factors to be measured in determining the potential value of any mineral deposit, and how it might fit within its particular industry. What, then, are the qualities which a gypsum deposit must have in order to profitably participate in the four hundred million dollar plus business which is the gypsum industry? First let's consider the geology of gypsum, the geographic distribution of deposits, and the more important factors such as size, grade, capital requirements, and operating cost. Then, an understanding of the uses of gypsum, various types of products, and location of markets would be helpful, along with such other factors as the structure of the industry, price trends, etc.

Jan 1, 1970

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence induced by underground coal mining activities, especially longwall mining operations, can cause various problems to interstate highways ranging from structural integrity to drivability to safety. Accurate subsidence prediction, correct influence assessments and effective mitigation measures are the keys to ensuring the safety of highway traffic. The surface subsidence prediction program, called comprehensive and integrated subsidence prediction model (CISPM), was developed based on the principle of influence function method and has been validated with a large number of subsidence measurements. In this paper, the techniques to use the predicted final surface movements and deformations for assessing their influence on the integrity and functionality of highway structures — such as road surface pavements, concrete slabs and transverse joints — vehicle dynamics, comfort level and drivability are presented. A number of mitigation measures to protect the highway structures and to ensure traffic safety are proposed, along with an application case.

By M. J. Richards

Spontaneous combustion caused by the movement of air through the waste is a major problem. Combat methods attempt to exclude oxygen rich air, but little is known about airflow through the waste. The use of a tracer gas technique to monitor the flow of nitrogen from an injection hole during inertisation is described. Correlations are drawn between barometric pressure changes and the nitrogen entering the waste. As no information was obtained about airflow and oxidation zones, a second experiment was conducted to sample from the waste, but the results were inconclusive. A finite element method developed to model the pressure and airflow distribution, under steady state and nitrogen injection conditions is outlined

Jan 1, 1987

By J. Loeb, R. Ramanathan, P. Cameron

All mining operations, including iron ore, maintain a focus of continuous improvement and asset optimisation in their operations. As all the operations in the Mine-to-Mill value chain are inter-dependent, available technologies that address efficiencies across the value chain are once again in the spotlight as companies are driven to improve productivity and maximise mine site profits to increase return on capital invested. Core to continuous improvement is the need to understand the baseline and the impact of changes to the process. In this paper, we discuss some of the key attributes in the mine to mill process, including their influence on productivity and cost, the need for direct measurement and areas where they should be applied. Many initiatives can be considered to improve mine to mill processes. Mining operations are planned and executed based on designs and models to achieve the operation’s objectives. However, there are many variables in the different parts of the value chain, such as blasting, material handling, crushing and screening. Measurement of the key attributes establishes the baseline for Mine to Mill (or Pit to Plant) performance which is necessary to understand the impact of any proposed improvements to the process design and execution and to monitor the outcomes on an ongoing basis to sustain the improvements that have been implemented. We have focused this paper on two types of measurement – blast movement and particle size of materials through the mine to mill process. Several innovative technologies are already available to measure these attributes and assist operations improve productivity and mine site profits.

Mar 2, 2022

By J. C. Bradbury

The Illinois State Geological Survey's program in industrial minerals is twofold-the gathering of information on mineral raw materials and the generation of data on the use of these materials. The first function is carried out by the Industrial Minerals Section and the Clay Resources and Clay Mineral Technology Section of the Geological Group, and the second is the responsibility of the Chemical Engineering Section of the Chemical Group. Gathering in formation on raw materials includes both mapping of resources and fundamental geological research. Recent and current research projects include studies relating lithologies of limestones to their physical properties, investigation of sulfur dioxide reactivity of various types of limestone, lithostratigraphic studies of limestones of Mississippian age, investigations of heavy minerals in Cretaceous, Tertiary, and Pleistocene sands, studies of the environments of clay deposition, electron microscope studies of clays and limestones, and investigation of long-term expansion in ceramic products. A relatively recent development that relates more to dissemination of information than to research is environmental geology. This affects the Survey's industrial minerals program chiefly by stimulating the study of rock and mineral resources in metropolitan areas and reporting the results for the land- use planner as well as the engineer or mineral producer. The Survey's program of research on the use of industrial minerals was expanded and diversified in 1966. Incorporating a minerals beneficiation lab, the program is designed to develop new uses for existing mineral resources and to assist producers in implementing these ideas: Projects of the minerals engineering program have included the separation of a feldspar concentrate from certain glacial outwash and river sands, recovery of kaolinite from the waste from silica sand operations, development of the use of an Illinois clay as a binder for pellets, and investigations into the use of fly ash and fluorspar mine tailings.

Jan 1, 1970

By P. M. Hawley

Kennecott Corporation, in joint venture with Galactic Resources Ltd., recently began operation of an open pit gold mining and milling facility near Columbia, South Carolina. The deposit consists of two ore bodies (North and South deposits) hosted in deformed and altered meta-volcanics and meta-sediments of the Carolina Slate Belt. This paper describes the rock mechanics and engineering geology investigations conducted for design of interim, ultimate and final reclamation slopes for the South Pit. Emphasis includes the successful use of drill core orientation techniques to confirm complex geologic structure at depth; the development of a three-dimensional rock mass competency model, incorporating surface mapping data, results of bench mapping documentation, field index testing and laboratory testing; and kinematic assessments for design of optimum slopes.

Jan 1, 1991

By M. B. Haggerty, Joe Welna

The Minnesota Department of Transportation is constructing a stormwater storage facility (SSF) along Interstate 35W (I35W) south of downtown Minneapolis, MN. The project will provide storm surge capacity reducing the frequency with which major precipitation events result in flooding of I35W. The design consists of six, 42-foot diameter, 90-foot deep, adjacent underground shafts providing 14.7-acre feet of storage. Construction challenges include high groundwater with variable glacial outwash deposits. Constructability and ground variability were managed using construction manager general contractor (CMGC) project delivery. CMGC provides an environment for collaboration and innovation starting in the design phase and carrying through construction. This paper provides an overview of key efficiencies and collaboration examples implemented on the I35WSSF project which were aided by CMGC delivery.

Jun 13, 2023

By C. J. Bise, P. Bucks

Central Appalachian coal reserves are a valuable natural resource in high demand, both domestically and internationally, justifying efforts to increase percentage recovery through pillaring. Unfortunately, the challenge associated with pillar extraction introduces additional safety risks during the activity. Although pillaring developed prior to mechanized mining, current technology and mining practices have made this form of mining highly modernized. However, current fatality trends suggest that work still needs to be done to control the residual risk that is not controlled by modern practices, such as those having a personnel-performance-based component. This paper investigates the application of modern coal pillaring techniques and will present a risk-management-based strategy that targets personnel-performance-based risk, in order to improve the ability of safety engineers, managers and trainers to provide training programs addressing the needs of pillaring sections.

Jan 1, 2012

By Brendan Donnelly, Jung-Hoon Sul, Lasitha Piyathilaka, Sanghyun Jeong, Benjamin Probyn

The chains of armored face conveyor (AFCs) are constantly in contact with water and wet coal, which results in a significant proportion of unplanned downtime experienced on longwall equipment due to corrosion. While reverse osmosis (RO) is one of the most prevalent water treatment methods for reducing salinity and dissolved solids in coal mining, its impact on the corrosion of the AFC chains has not been well studied. This work studies the direct effects of RO water on the corrosion of AFC chains. Immersion tests followed by surface micromorphology analysis and corrosion indices indicate that the RO water increased the corrosion rate of the AFC chains due to the reduced tendency of preventive films on the chains.

May 1, 2024

By Georgene Renner, Chee Theng, William Gleason

"More than 6,300 people attended SME’s 2016 Annual Conference & Expo in Phoenix, AZ and many of them made the trip to the conference to take part in the excellent technical sessions that are presented on a yearly basis by the Society.Holding true to form, this year’s conference was full of options. In fact, this year there were 121 technical sessions and 751 presentations to chose from. The following is a sample of some of the technical sessions as seen through the eyes of the editors of Mining Engineering and SME technical papers.SME Sections Sharing Success: Changing thePublic Perception of MiningThis session was a workshop on how several local sections were effective in getting the message out to their communities and schools about the value of the extractive minerals industry. Several sections shared their outreach successes, including the Mining in Society merit badge activities by the Minnesota Section by Julie Lucas and SME’s participation in the World Scout Jamboree in Japan by Frank McAllister.Dan Alexander highlighted activities by the Pittsburgh Section, such as preparing minerals kits and pamphlets for elementary school classes and regional science fairs. The West Virginia University Student Chapter used the kits as handouts at their local gem and mineral show. School speakers in full mining gear were especially interesting to the young children.Other speakers were Michael Linn, Paradise Valley Unified School District — Business and School Partnerships; and Greg Kruse, Central Wyoming Section of SME — What makes a successful section?Engineering Competency ModelAmerican Association of Engineering Societies and the U.S. Department of Labor, with a grant from the United Engineering Foundation, developed a guide to the set of skills necessary for success in the engineering community -- Knowledge – Skills – Abilities — needed for all disciplines.Various engineering societies are now writing the Tier 5 occupation-specific requirements. The Competency Committee is charged to write concise and discipline-specific mining engineering, mineral processing engineering, geological engineering, and geophysical engineering by Sept. 30, 2017."

May 1, 2016

By Craig J. Nelsen, J. Leroy Schutz

The Carache Canyon Prospect consists of a hypabyssal breccia pipe which intrudes a gently dipping sequence of Cretaceous Mancos Formation and Mesa Verde Group shales and sandstones. This sedimentary sequence is intruded by a number of Oligocene (34-30 Ma) calc- alkaline sills. The formation of the breccia pipe and its subsequent gold mineralization is related to the emplacement of an alkaline intrusive complex dated between 30-26 Ma. An exceptionally large block within the pipe provides compelling evidence that brecciated sills and sedimentary rocks form a relict stratigraphy that collapsed 400-800 ft (120-240 m) below their counterparts outside the pipe without substantial changes in stratigraphic position. Native gold and sulfide mineralization within and around the pipe occurs in fractures that are primarily controlled by competency differences between sills and sedimentary rocks and secondarily controlled by ductility contrasts between the relatively brittle Mancos Formation hornfels and the more ductile Menefee Group shales. The resulting pattern of gold mineralization is a series of stacked, tabular, mineralized sills and sandstone separated by barren shale in an annular region along the southwest margin of the pipe. A series of near-vertical, subparallel, sill and sandstone breccias separated by barren or weakly mineralized shale breccia occur within shallow levels of the pipe.

Jan 1, 1990

By D. B. Sikka, R. B. Bhappu

Porphyry-type copper-molybdenum (Cu-Mo) deposits typically occur in the Phanerozoic rocks and have been well-documented. During the past two decades, a number of porphyry-type Cu-Mo deposits that range in age from 1055 Ma to 2970 Ma have been identified in the Precambrian rocks of Australia, Canada, China, Finland, India. Namibia and Zambia. The Malanjkhand porphyry copper deposit M.P., India is estimated to contain 789 Mt (870 million st) averaging 0.83% copper (mill headgrade); 0.004% molybdenum; 0.2 g/t (0.006 oz/st) gold; 6 g/t (0.175 oz/st) silver and a cap of 7.5 Mt (8.2 million st) of oxide ore averaging 0.8% copper. The economic potential of the expanded copper mining milling, smelting and refining complex is expected to yield cathode copper 118.6 kt (130,700 st); molybdic oxide 830 t (914 st); gold 1.9 t (61,732 oz); silver 46.6 t (1.5 million oz); sulfuric acid 240 kt (264,500 st), copper from leach dumps 11.5 kt (12,600 st); nickel 24 t (26,400 st); cobalt 84 t (92,600 st); bismuth 16 t (17.6 st); selenium 48 t (53 st), tellurium 4.8 t (5.3 st).

Jan 1, 1995

By R. Venugopal, V. K. Saxena, A. K. Mukherjee

"Coal, iron and manganese ore samples were exposed to different ultrasonic intensities of 250, 300 and 350 W/L for five minutes and to an ultrosonic intensity of 270 W/L for different time durations of 3, 5 and 7 minutes. The ultrasonically treated samples showed reductions in D80 particle diameters of 6 percent for the coal samples, 5.95 percent for the iron ore samples and 35.63 percent for the manganese ore samples during grinding. The ultrasonic treatment was also observed to assist in reducing ash content in the coal product by 8 percent and to reduce manganese losses in rejects by about 5 percent. Ultrasonic treatment was concluded to be capable of assisting in the comminution of friable ores more prominently than the hard and porous materials.IntroductionComminution is an important unit operation in the mineral-processing, cement-making, powergeneration and pharmaceutical industries. But most of the milling technologies are considered to be energy inefficient, with less energy consumed in real size reduction and most of the energy consumed in the machine. This is more critical for the mineralprocessing industry because of the growing need to exploit lower-grade ore bodies and process rejects (Blazy et al., 1994; U.S. Department of Energy, 2005). Low-grade ores require crushing and grinding to liberate the valuable minerals, which are further separated from gangues by various beneficiation methods such as gravity separation, flotation and leaching. Various studies have been carried out to minimize energy consumption during milling by developing pretreatment methods that can initiate new fractures or improve the fracture density in materials before comminution. These studies were mainly focused on chemical additives; thermal, ultrasonic and microwave treatments; and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Bearman, Briggs and Kojovic, 1997; Gaete-Garreton, Vargas-Hermandez and Velasquez-Lambert, 2000; Kumar et al., 2010; Wang, Shi and Manlapig., 2011, Singh et al., 2012).The fragmentation effect of ultrasonic fields in solids has been investigated since the 1950s, and Gärtner was probably the first researcher who attempted it (Gaete-Garreton, Vargas- Hermandez and Velasquez-Lambert, 2000). Sound waves can propagate in solids in the form of longitudinal waves, shear waves and surface waves, and in thin materials as plate waves.In surfaces, fractures and interfaces, various types of elliptical or complex vibrations of the particles make other waves possible. During ultrasonic-vibration treatment, cavitation bubbles nucleate, grow and collapse, generating microjets, whose impacts on the particles initiate microcracks. The ultrasonic waves can enhance the nucleation, growth and coalescence of flaws, caused by tensile or shear stress. The mechanisms operating in the materials and inducing these stresses have been identified as spall and compression-induced tensile microcracks, nucleating at preexisting flaws. These mechanisms are driven by the shock wave and cavitation effects in the surrounding fluid (Chen, Huang and Shih, 2003)"

Jan 1, 2016

By E. Allen Hendt

It is a pleasure to be invited to speak before a gathering of executives representing America's leading mineral companies, I welcome this opportunity, particularly because it comes at an important period in the development of U.S. commodity policy. This morning, I discussed our general commodity policy primarily in the. Context of the north-south dialogue between developed and developing countries. This afternoon, I would like to focus more specifically on potential cartel activity and U.S. mineral import dependence.

Jan 1, 1978

By James K. Hallenburg

Geophysical borehole logging is a valuable and inexpensive tool for coal deposit evaluation, development, and production. In addition to the usual determinations of depth and seam thickness, geophysical borehole logs can effectively and accurately determine the coal ash, moisture, and heat contents in situ. Location and evaluation of the partings can be done quickly and accurately. Overburden character determination, such as roof competence, dewatering parameters, ripability, trace element content of the coal and overburden, and sulfur content can be done with existing tools and techniques. The quality of such determinations depends upon the quality of planning and calibration.

Jan 1, 1984