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By X. L. Song, G. W. Zhang, F. Y. He, X. Xiao, L. L. Huang

This paper presents the design of a model and process simulation of a vertical mill based on a population balance model. The simulator, Simulink, which is a systematic modeling tool within MATLAB, was used for the simulation. The model will simulate the real time variation trend of each size fraction in the feed material to the vertical mill, as well as, the size distribution of the batch grinding products. Breakage distribution and selection functions are calculated based on batch grinding laboratory experiments using Back-calculation method. The simulated size distributions correspond with those in the actual mill operation having a relative error of less than 0.50%. This work lays the foundation for future research on modelling and simulation of a closed circuit grinding operation consisting of a vertical mill with hydrocyclone classifier.

Jan 1, 2016

By M. O. Makwarela, M. W. Erwee, K. Bisaka

"Energy efficiency in mining and minerals processing forms part of Mintek’s long-term research strategy which includes a specific programme designed at overcoming the challenges faced by the South African pyrometallurgy industry.The electric smelting industry is currently severely constrained by the global economic downturn as well as by the availability and increasing cost of electricity. Efficient utilisation of electricity through energy recovery systems and improved smelting process flowsheets can significantly contribute towards creating sustainable operations.Apart from efficient engineering design and solid process control, smelting of either cold or hot pre-reduced ores has been shown to decrease furnace electricity consumption by more than 40%. Various methods of solid-state reduction tests have been carried out at Mintek in order to select the most appropriate process option in the context of the South African industry. This paper summarises a subset of the results obtained, specifically on pre-reduction tests done on South African chromite and manganese ore pellets.In this set of tests, it was found that the use of an organic binder, together with B2O3 as flux, promotes manganese ore pre-reduction, but retards the pre-reduction of chromite. By pre-reducing the manganese ore feed, significant cost savings can be achieved in subsequent smelting processes and there is potential to minimise manganese losses as a result of fuming, due to possible lower operating temperatures."

Jan 1, 2016

By Matthew Grzelak, Gulsah Erinc, David R. Chapman

"The third phase of the Bagram Drainage System project at Bagram Air Force Base in Afghanistan included construction of a shallow, 540-m long, 1.8-m inside diameter drainage tunnel. The tunnel penetrated mostly stiff to hard clayey and silty soils. The contractor’s Value Engineering Change Proposal (VECP) to use pipe-jacking with a microtunnel boring machine (MTBM) instead of the specified two-pass Earth Pressure Balance method was evaluated and supported using hand calculations. Contractor support was provided throughout the project by providing design reviews and instrumentation monitoring during construction. This paper compares the value-engineering proposal to the specified method and describes the construction conditions encountered. INTRODUCTION As part of a larger improvement project at the Bagram Air Force Base in Afghanistan, a shallow, 540-m long, 1.8-m inside diameter drainage tunnel was constructed to provide additional capacity for Coyote Creek to pass below several critical structures, including taxiways and the main runway, for mitigation of recurring flooding (see Figures 1 and 2). Overburden over the tunnel crown ranged from about 3 m to 5.5 m. An existing cast-in-place twin barrel concrete culvert runs approximately parallel to the new tunnel and is within about 8 m at its closest point. The contractor’s Value Engineering Change Proposal (VECP) to the specified two-pass Earth Pressure Balance (EPB) method (steel ribs and lagging or steel liner plate with a carrier pipe later grouted in-place) called for installation of the required drainage pipe by pipe-jacking (one-pass installation) using a slurry microtunnel boring machine (MTBM). The critical nature of the operations at the air base resulted in significant construction coordination challenges and a greater than usual need to avoid excessive settlements. Substantial restrictions were placed on drilling of investigative borings and installing instrumentation near runways and taxiways due to drill mast height. The prime contractor was SERKA TAAHHUT INSAAT A. S. (SERKA), the microtunneling subcontractor was Ludwig Pfeiffer Microtunnel GmbH & Co.KG (Pfeiffer), the jacking pipe designer was Gollwitzer Pipe and Shaft Technology GmbH (Gollwitzer), and the contractor’s tunnel engineer was Lachel & Associates, Inc. (Lachel). Lachel provided contractor support throughout the project including preparation of a VECP/Design Summary (including interpretation of existing and new geotechnical information), design reviews for jacking pipe, estimating settlement of an existing drainage structure above the new tunnel, and instrumentation planning, monitoring, and analysis during construction."

Jan 1, 2016

By Robin Dill, Wei Song, Andrew Perham, Leo Martin

"AECOM completed a subsurface exploration program for an 18-foot diameter, approximately 4-mile long rock tunnel project in Hartford, CT. The tunnel crosses the regional geologic trend through the middle of a sedimentary basin, passing through four separate rock formations, including two volcanic flows. Faulting is prevalent, with at least 15 faults encountered during the site investigation. Severe artesian flows were also experienced in several of the borings, requiring highly specialized drilling equipment. Sixty-two borings and associated testing were performed to characterize the structural geology, hydrogeology, rock properties and ground conditions. A phased program was carefully planned and implemented with participation of geotechnical and geologic specialists, with thoughtful evaluation along the way to react to the ground conditions encountered, and make appropriate refinements. This paper will discuss the subsurface program details; the integrated efforts used to effectively characterize the ground; and will summarize the final characterization presented in the GBR. PROJECT DESCRIPTION The South Tunnel Conveyance and Storage Tunnel project is part of the Metropolitan District (MDC’s) Long Term Control Plan to address discharges to various water bodies throughout the greater Hartford area. This program includes a main conveyance and storage tunnel; a tunnel boring machine (TBM) launch shaft and retrieval shaft; adit tunnels with associated drop shafts and connection structures; consolidation conduits and manholes; and a tunnel pump station (TPS) at the downstream end of the main conveyance tunnel. AECOM is serving as prime designer for the MDC on this project. The main conveyance tunnel (hereinafter referred to as the “South Tunnel”) will be a deep rock tunnel with an invert depth of approximately 180 feet at its downstream end and approximately 218 feet at the TBM retrieval shaft. The tunnel will have a finished diameter of 18 feet. The tunnel will rise in grade at a slope of 0.1 percent to its upstream end. Total invert depth along the deep tunnel alignment ranges from about 180 ft. to as high as 320 feet. The total length of the tunnel will be 21,754 feet. The South Tunnel will be constructed using a shielded TBM and fully lined with pre-cast concrete segments."

Jan 1, 2016

By Marco Aurelio Piangatelli, Massimiliano Bringiotti, Ferdinando De Angelis

"The construction of the three connecting tunnels between the east side and the west side of station C13, adjacent to the Vistula river, has a long and complex history, as they cross beneath one of Warsaw’s main road arteries (Wislostrada). After the attempt to excavate the first tunnel, the face of the tunnel collapsed on the night of August 13, 2012, and a volume of about 10,000 cubic meters of liquid mass (water, silty soil and sand) entered and flooded the west side of the station, which was filled with more than seven meters of material. Fortunately, the workers managed to escape, but machines and equipment were lost. This is the story of how the tunnels were completed, by adopting soil improvement, jet grouting, GRP bars, ground freezing and a careful choice of work steps. INTRODUCTION The Centrum Nauki Kopernik station on Line II of the Warsaw Underground is located alongside to the Vistula river (Figure 1). This station hereinafter is referred to as station C13.The station consist of three parts: the east and west part, and three connecting tunnels 40 meters in length with a large cross section (170 m2).. It includes the rails along the sides and the platform along the centre. The reason for the underground connection of two shafts with a tunnel is due to the presence of a road tunnel (Wislostrada, hereinafter called WS), which must be underpassed by the new metro line (Figure 2).The existing tunnel (Wislostrada) was built many years before, between diaphragm walls, and some foundation structures interfere with the underground tunnel. The challenge was to build the connectors without stopping the traffic of vehicles along the highway above. All works took place in very difficult geological and groundwater conditions due to the presence of Vistula alluvial deposits with poor mechanical characteristics. The soil profile consists of relatively loose sands on top, and silts overlying high plasticity Pliocene clays highly disturbed by the effects of the repeated over-sliding of glacial moraine deposits."

Jan 1, 2016

By Shinichi Konda, Gary Nishimura

"Thousands of years ago large glaciers carved much of the landscape in Puget Sound, depositing abrasive and granular soils including cobbles and boulders along with layers of clay and sand. Tunneling in this geology – common throughout much of the northern and Midwestern U.S. – is challenging and can be unpredictable. The use of pressurized face tunneling, most commonly with EPBs and slurry type machines, has made excavation in this geology more efficient, but difficulties still remain. Through analysis of recent projects in Seattle, Washington, USA, the authors draw conclusions as to the best TBM designs and operational parameters for this variable, abrasive and often difficult ground. Performance data is analyzed with an eye towards advancements that could further improve TBM tunneling in glacially deposited soils. INTRODUCTION Over the past several ice ages, extensive glaciers reaching across much of North America transported large amounts of soil and rock as they moved across the land. The substantial weight of the ice sheets mixed together a wide range of soil types along with a variety of rocks and boulders of all sizes. Many rock formations were reduced to pebbles or particles containing highly abrasive characteristics. Any boulders able to survive were generally comprised of harder materials which were scattered throughout the soil. This highly variable mixture of abrasive soils and high strength boulders can be found in many areas across the Puget Sound and other regions of the country. Wherever they are encountered, they often create a difficult and unpredictable mining environment for both equipment design and operation. Modern TBMs are optimized early in the design process for specific types of geology, and unexpected conditions can require extensive modifications. In addition, several operational parameters need to be adjusted to balance ground characteristics, and advance rates can be significantly affected in mixed and rapidly changing soil conditions. Both EPB and slurry machines can be used successfully in these conditions, provided their respective operating criteria are met. Ideally, an EPB is operated with a relatively thick muck consistency, which accommodates moderate changes in soil permeability and maintains a reliable pressure differential through the screw conveyor. However, this also causes higher wear on rotating components and requires more energy at the cutterhead. Alternatively, slurry machines typically operate best with a more fluid muck consistency that can be easily pumped through the extensive piping system. This tends to reduce the wear on the cutterhead and the power requirements of the cutterhead drive system, but also makes the machine more sensitive to changing soil conditions. Generally, the slurry piping system is also more capable of controlling high face pressures, although the screw conveyor of an EPB can also be designed to accommodate most high-pressure conditions."

Jan 1, 2016

By K. V. Raj

"The development and advancement of computational fluid dynamics (CFD) has made it possible to better understand pollutant flow and distribution in deep open pit mines. Open pits located at higher latitudes, especially in the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during much of the winter. A three-dimensional CFD model of an actual open pit mine in the Arctic was developed to analyze the problem of pollutant growth during inversion, and mitigation of the pollutants through improved ventilation schemes. Due to the availability of mine-specific data, such as contaminant concentrations and coordinates of sampling locations, the actual 2013 pit geometry was used for model validation Concentrations predicted by the selected realizable ?-e turbulent model are compared to measured pollutant concentrations at the open pit. Pollutant concentrations at selected locations showed differences, but remained within the same order of magnitude in most cases. INTRODUCTION Computational fluid dynamics (CFD) has emerged as a useful tool for ventilation modeling in underground mines (Edwards and Hwang 1999, Purushotham and Bandopadhyay 2009, Wala et al. 1998, Xu et al. 2011). Application of CFD in open pit mines has been limited, however, since most open pit mines located at lower latitudes do not encounter considerable ventilation problems. Open pits located at higher latitudes, especially the Arctic and sub-Arctic, face a unique problem due to atmospheric temperature inversion, which is prevalent during winter. A number of Russian researchers have tried to understand the air inversion and resulting pollutant transport problem by modeling air flow phenomena in open pit mines (Baklanov and Burman 1996, Baklanov 1984, Baklanov 1995, Belousov 1985, 1989, 1995). Much of their work, however, was based on numerical models and methods of finite difference. Baklanov (2000) applied a modified ?-e and a ?-l CFD model to air flow phenomena on various terrains. More recently, Choudhury (2011) used the COMSOL CFD package for modeling pollutant transport for an idealized open pit mine. Collingwood et al. (2012a, 2012b) used a two-dimensional model for fluid flow and contaminant transport at an Arctic open pit mine. The authors have also previously presented work on CFD modeling of an actual open pit mine at high latitude (Bandopadhyay et al. 2014, Raj et al. 2015a). However, the CFD work done by the above-cited researchers lacked model validation with field-measured data. Validation of a developed model is important in assessing the quality and accuracy of the predicted results. In general, experiments are done numerous times in controlled environments to assess the validity of collected data. There are two types of assessments used in CFD simulations: (1) verification and (2) validation. Model verification is checking the accuracy of the computer codes during the implementation phase of a real-world problem, within the specific limits of accuracy (Oberkampf and Trucano 2002). Since, the pollution transport model presented in this paper used the commercial ANSYS-FLUENT CFD package, verification is not needed as the program has been tested widely, and verified numerous times."

Jan 1, 2016

By John Reilly

"INTRODUCTION Successful management of megaprojects, meaning delivery within budget, on time and according to expectations, is a fundamental requirement. Many projects have been successful, some have not. This paper reviews megaprojects1, drawn from the author’s projects over the last 50 years, with “lessons-learned” and a summary of recommendations that, if implemented, would improve megaproject management and delivery. Characteristics of these projects are summarized – including outcomes related to key factors such as politics, management, organizational structure, contracting methods, cost estimates, risk and other elements. The projects include the Washington D.C. Metro, Boston Southwest Corridor, LA Metro, Toronto Rapid Transit Expansion Program, BART San Francisco, MARTA Atlanta, London Underground and the Washington State Highway megaprojects – including the SR520 Floating Bridge and the Alaskan Way tunnel. Other projects that illustrate successful, innovative management and contracting methods include the Madrid Metro (low-cost delivery), the Sydney Northside Storage tunnel (outturn cost, alliancing) and the Lake Mead tunnel (working in partnership, risk management). KEY ISSUES A characteristic of megaprojects is that their complexity increases exponentially with size (Reilly 2010, Galloway et al. 2012). These projects are very visible politically, have many stakeholders who must be satisfied and generally span many years and political election cycles. To be successful they must meet expectations, function efficiently, and be delivered under, at or close to budget and schedule. There is a widely-based perception that large, complex projects are always delivered late, over budget and with problems. Specific examples include projects such as Tren Urbano in Puerto Rico – $1.28 billion over initial budget (+133%), the Silver Line Transitway Project in Boston – $286 million over budget (+90%), the London Jubilee Line Transit Project – 2 years late and £1.4 billion (+67%) over budget, the Channel Tunnel Rail Project – £3.7 billion (+80%) over budget, Denmark’s Great Belt Link rail and road link (54% over budget), the 2003 Woodrow Wilson bridge tender in Virginia (72% over estimate) and Boston’s Central Artery Project – several billion (perhaps 100%) over what would have been a realistic initial budget and years late (Reilly 2001c, 2004a; Salvucci 2003)."

Jan 1, 2016

By Guy Reed, Russell Frith, Kent Mctyer

"Coal pillar design has historically been based on assigning a design factor of safety (FoS) or stability factor (SF) to coal pillars according to their estimated strength and the assumed overburden load acting on them. Acceptable FoS VALUES (have been assigned based on past mining experience, and at least one methodology includes the determination of a statistical link between FoS and probability of failure (PoF).The role of the pillar width-to-height (w/h) ratio has long been established as having a material influence on both the strength of a coal pillar and its potential mode of failure. However, there has been significant professional disagreement on using both FoS and w/h ratio as part of a combined pillar system stability criterion, as compared to using FoS in isolation. The argument is that, as w/h ratio is intrinsic to pillar strength, which, in tum, is intrinsic to FoS, it makes no sense to include w/h ratio twice in the stability assessment. At face value, this logic is sound.However, this paper will argue that there is a valid technical reason to bring w/h ratio into system stability criteria (other than its influence on pillar strength), as it is related to the post-failure stiffness of the pillar, as measured in situ, and its interaction with overburden stiffness.When overburden stiffness is bought into pillar system stability considerations, two issues emerge. The first is the width-to-depth (W/H) ratio of the panel, in particular whether it is sub-critical or super-critical from a surface subsidence perspective. As a minimum, this directly relates to the accuracy of the pillar loading assumption of full tributary area loading. The second relates to a reevaluation of pillar FoS based on whether the pillar is in an elastic or non-elastic (i.e., post-yield) state in its as-designed condition, as relevant to maintaining overburden stiffness at the highest possible level.The significance of the model presented is the potential to maximise both reserve recovery and mining efficiencies without any discernible increase in geotechnical risk, particularly in thick seams and higher depth of cover mining situations. At a time when mining economics are, at best, marginal, removing potentially unnecessary design conservatism without negatively affecting safety is of interest to all mine operators and is an important topic for discussion amongst the geotechnical community."

Jan 1, 2016

By Vladislava A. Ignatkina, Fillip O. Milovich, Vladimir A. Bocharov

"Complex research of flotation concentrates of monomineral fractions of chalcopyrite, sphalerite, galena, pyrite, pyrrhotite included methods of adsorption of collectors, surface compounds by IR ATR, and surface films of flotoreagents by TEM. They revealed that the proportion of the parts of thionocarbamate (TC) and dithiophosphate had an effect on the adsorption rate of the components of minerals, on the presence of characteristic bands, and, what is an important, visualized surface film of organic flotation reagents on the particles of concentrates by TEM. The predominance of thionocarbamate in a composition selectively increases the adsorption rate constant of the components and recovery of chalcopyrite compared with sphalerite and galena. The highest flotation rate using TC is characteristic for chalcopyrite (0.62 min- 1) in case of individual use, and it's in combination with butyl xanthate (25% butyl xanthate or 3:1) 0.89 min-1 too. We studied the ternary blend - dithiophosphate: thionocarbamates: butyl xanthate. The increase of the proportion of butyl xanthate in combination reduces the contrast of the flotation rate among all sulfides.Practice flotation of refractory sulfide copper-zinc ores of the Urals (content sulfide iron - 75- 95%) confirmed that the use of a combination of selective collectors increases selective recovery of copper sulfide minerals up to 50% at the first fraction that is the conditioned copper concentrate. New selective sulfhydryl collectors resulted in high levels of recovery of copper into a concentrate - more than 90% - against 70-72% (butyl xanthate) from copper-pyrite ore. Low floatability of iron sulfides has been obtained by selective sulfhydryl collectors. Using weak selective sulfhydryl collectors can reduce pH into collective or selective flotation from pH 10-10.5 to pH = 7.2-7.5, which improves the quality of individual concentrates of nonferrous metals and their recovery. The same is true for polymetalic sulfide ore. The volume of gold recovery also increased."

Jan 1, 2016

By Ralph J. Holmes

"An accurate knowledge of the chemical, mineralogical and physical characteristics of ores and mineral products that are mined, processed and sold commercially is crucial to resource definition, effective resource utilisation, plant design, process control, metallurgical accounting and finally quality control to ensure that contract specifications are met and equitable payment is received for product sales. However, the responsibility for sampling is often entrusted to personnel who do not fully appreciate the significance and importance of collecting fully representative samples for analysis, and they seem satisfied as long as some material is collected and returned to the laboratory for analysis. Furthermore, sample stations incorporated into the design of new plants are often the first casualties when cost cutting exercises commence. There is really little point in accurately analysing samples if they are not representative in the first place, because the resultant analyses can be seriously biased and the effort taken to carefully analyse such samples is largely a waste of time and resources.Ultimately, a poor knowledge of the characteristics of ores and mineral products limits the ability of mining companies to optimise the life of ore resources and plant performance, and failure to meet final product specifications can have disastrous consequences, including price penalties and more seriously loss of sales contracts and significant revenue losses due to poor sampling practices at the point of sale. Consequently, it is critical that sampling is given the attention it deserves as the first important step in the quality measurement chain. The golden rule for correct sampling is that all parts of the ore, concentrate, slurry or other material being sampled must have an equal opportunity of being collected and becoming part of the final sample for analysis."

Jan 1, 2016

"INTRODUCTION While the United States coal mining uses prescriptive regulation under the Title 30 Code of Federal Regulation enforced by the Mine Safety and Health Administration (MSHA), Australia uses a risk based approach. Australian regulation is individual to each state. In Queensland, Australia this risk based approach to address principal hazards is underwritten by the Queensland Coal Mining Safety and Health Act of 1999 and the Coal Mining Safety and Health Regulation of 2001. Each Queensland Mine is required to have an overarching Health Safety and Environment Management System, of which Safety Management Plans are an element. “Safety Management plans (SMP’s) are intended to formalise the process by which mines address principal hazards and other related matters to ensure the safety of mine personnel.”7 THE QUEENSLAND CONTEXT In Queensland, the basic elements of a coal mine’s safety and health management system must provide for risk identification and assessment, hazard analysis, hazard management and control, and the reporting and recording of relevant safety and health information and data.5 (Part 2 Division 1 Section 6(a-d)) The initial guidance for writing Safety Management Plans comes from the Approved Standard for Mine Safety Management Plans and Guidance Note QGN09- Reviewing the Effectiveness of Safety and Health Management Systems. The Guidance Note and Approved Standard are supplemental to the Act and Regulation, and put in place to provide more clarity around the topic. The definitions in this section come from the Approved Standard and are included to provide context for those who may not be familiar with Australian or Queensland law and regulation. A hazard is defined as a source of potential harm or a situation with a potential to cause loss, while a principal hazard is a hazard with a potential to cause multiple fatalities. A risk is the chance of something happening that will have an impact upon objectives which is measured in terms of consequences and likelihoods. It is important to be able to make the distinction between a hazard and a risk. For instance, a lion is a hazard, while the risk associated with a lion is getting eaten. As defined by the Queensland Approved Standard for Mine Safety Management Plans, a Safety Management Plan (SMP) requires a systematic definition of all the actions necessary to ensure that mining operations are carried out safely. A SMP includes, but is not limited to organisational structures, planning, activities, responsibilities, practices, risk identification, audits and reviews.7 The goal of a SMP management plans is to mitigate the risks to bring them to an As Low As Reasonably Achievable (ALARA) level."

Jan 1, 2016

By A. Simon, J. Weyer, J. Brune, V. Zhiteneva

"Reiche Zeche is a lead-zinc-silver deposit in Freiberg, Germany, that was mined for over 800 years. Since 1969, Reiche Zeche has been a teaching and research mine with numerous adits for dewatering large amounts of inflowing water. Infrequent metal water quality monitoring in the 1980-1990s and flooding of the mine in 2002 led to a lack of relevant data. New measurements were taken at different level adits and ore veins for comparison to historical values, revealing pH levels as low as 1.95, conductivity as high as 22000 µS/cm, and an overall trend towards less acidic waters. INTRODUCTION Reiche Zeche is part of the Himmelfahrt Fundgrube, a former iron ore mine in Freiberg, Germany, in the Erzgebirge mining region of Saxony. The polymetallic sulfide ore found in Freiberg was mined from 1168 to 1969, and though it is no longer producing ore, Reiche Zeche remains as a teaching and research mine for the Technische Universität Bergakademie Freiberg. The most important ore minerals mined were sphalerite, galena, pyrite, chalcopyrite, and silver, and important gangue minerals include calcite, fluorite, barite, siderite, and quartz (Zänker et al 2002). Over one thousand ore loads were mined from this region during operation, which was ceased in 1969 after the lower part of the 700 meter depth was flooded, leaving only the top 200 meters under the surface open for research and teaching. Mined materials from this region can be separated into high grade ore and waste rock. High grade ore, composed of pyrite, sphalerite, galena, chalcopyrite, and arsenopyrite, was brought to surface for smelting during mine operation, and spaces were backfilled with waste rock, which is the primary site of sulfide oxidation and acid mine drainage (Haubrich and Tichomirowa 2002). The waste rock includes remnants of ore from ore loss, veins which were too small to mine, or ore minerals within host rock. Waste rock is primarily composed of biotite gneiss, with sulfides including jarosite, gypsum, minor anglesite, scorodite, and sulfur (Haubrich and Tichomirowa 2002). When weathered, the gneiss forms clay minerals such as illite and kaolinite (Haubrich and Tichomirowa 2002)."

Jan 1, 2016

By Greg Watson, Dennis Ofiara

"TBMs have been used in mining in decades past, but their use has been limited and sporadic, due to both perceived and actual application difficulties. With new technology and mounting success stories, this is changing. For both coal and metals mining, deep ore bodies require long access tunnels, and an efficient and economical method of reaching those deposits. Today, mining engineers are considering TBMs as part of the overall mine development plan. Planned TBM mine drifts are not only longer, but have more complicated trajectories. Mine development TBMs will have to cope with varying geology, potential for high water inflows, steep gradients, and high temperatures. TBM systems are being planned to cope with such difficulties. TBM systems will be considered and increasingly deployed for mine development, even if commodity prices remain low. TBMs can satisfy the need for increased productivity, better life of mine infrastructure, and safety. Effective conveyor systems are essential to support TBM operation in many mining applications. Many mine development tunnels are slopes, driven down at the steepest practical gradient to reach the deep ore body. Conveyors are often the only safe and effective way to haul the TBM muck form such tunnels. This paper will review the historical use of TBMs in mining, and will discuss the 2015 status of TBMs and conveyor systems in mining, and the special requirements and adaptable features needed in order to make efficient TBMs a reality in mines worldwide.HISTORICAL USE OF TBMS IN MINING APPLICATIONS The first successful hard rock TBM was invented in 1954. Over the next decades, TBMs have been used in many mining applications: Mine access drifts in several Spanish mines •,White Pine Copper Mine, USA •,Selby Coal mine drift, UK •,Coal slopes in Appalachia, USA •,German coal mines accdess drifts, several mines •,Magma Copper San Manuel, USA •,Cape Bretton Undersea Coal Slopes, Canada •,Stillwater Mines, USA"

Jan 1, 2016

By N. Prenn

"INTRODUCTION The 2014 SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (the SME Guide) has been adopted by the Society for Mining, Metallurgy, and Exploration, Inc. (SME). The SME Guide is recommended as a minimum standard and a basis for developing industry best practices in the classification of Mineral Resources and Mineral Reserves for public and private purposes. The Guide is therefore strongly recommended to be used by members of this organization. The SME Guide was updated in 2014 to include CRIRSCO (Committee for Mineral Reserve International Standards) core definitions, and it is envisioned that the U. S. Securities and Exchange Commission (SEC) will adopt the SME Guide in 2016. However, as of the end of 2015, the SEC Industry Guide 7 remains the standard for the U.S. reporting of Mineral Reserves. This paper will cover the classification of Mineral Resources and Reserves, a discussion of Modifying Factors, and the classification definitions and guidelines. The definitions and guidelines contained in this report are from the SME Guide. FRAMEWORK FOR MINERAL RESOURCE AND MINERAL RESERVE CLASSIFICATION Figure 1 illustrates the classification of Mineral Resources and Mineral Reserves using the Guide. Mineral Resources are divided into three classifications of Inferred, Indicated, or Measured while Mineral Reserves include Probable and Proven classifications. These classifications reflect improved knowledge and confidence of the deposit from the top of the figure to the bottom. In other terms, the deposit risk also decreases from top to bottom.The relationships in Figure 1 reflect different levels of geoscientific knowledge and different degrees of technical and economic evaluation. Mineral Resources can be estimated on the basis of geoscientific information with input from other disciplines to establish reasonable prospects for eventual economic extraction. It was not too many years ago that the classification of a Mineral Resource was based on the evaluation of a limited set of factors that included spatial drill hole and grade distribution (kriging variance, as example), distance to the closest hole, and number of samples used to estimate a block grade. These are still important considerations, but classification following the Guide must also take into account sample integrity, sample QAQC, database integrity and completeness, geological understanding, and geological and grade or quality continuity. In addition, a general consideration of the Modifying Factors, to establish reasonable prospects for eventual economic extraction, adds complexity to the classification."

Jan 1, 2016

By R. Addison, T. Swendseid, R. Kehmeier, D. Larsen, J. Uhrie

"The development of a mining project necessarily progresses through many steps, beginning with the identification of a mineral resource and continuing through project construction. Several classifications of engineering study development are described, including preliminary economic assessment (PEA) or scoping studies, prefeasibility studies (PFS), feasibility studies (FS) and regulatory codes, each with a specific project organizational objective. This paper addresses the PEA, PFS and FS types of reports that are used by companies to evaluate projects, meet regulatory requirements and seek financing. The minimum requirements for engineering studies, focusing on the needs of financial institutions considering investment in a project, are outlined. IntroductionThe financing of mining projects in recent years has come under increased scrutiny by financial institutions owing primarily to an increasing percentage of projects whose capital expenditures had overrun project budgets or had failed to produce the economic returns anticipated during the project development process. Often, unfavorable project outcomes are not the result of widespread failures of the project engineering process but arise from inadequate engineering in limited specific areas of the project scope, such as overestimated mineral reserve, inadequate mine design, insufficient metallurgical testing or underestimated capital costs. Mill facilities and process infrastructure typically are responsible for up to 80 percent of the capital expenditures required by greenfield mining projects. They are often the project areas where capital costs are inadequately developed, and consequently are the areas highly scrutinized by financial institutions. This paper offers a perspective on the level of engineering expected by financial institutions as a prerequisite to committing support to developing mining projects.The evaluation of a mining project from exploration through development and production is a lengthy and complicated process. Mine development commitment activities for a potential project are initiated when a mineral resource is identified and continue through to the start of construction. The technical feasibility and the economic viability of each project are determined during the phases of mine development with more detailed engineering data required at each stage. There are at least four levels of engineering studies during development that are commonly acknowledged by the mining industry:"

Jan 1, 2016

By M. Gunter, M. Buzon, B. McNamee

"A Google search on talc asbestos will yield over 500,000 hits – the reason being the growing number of civil lawsuits in this area. Historically the litigation was centered on amphibole-containing industrial talc. There was no debate these talcs contained amphiboles, but the issue was the definition of asbestos. Ultramafic hosted talcs, however, are formed in such a way as to not favor the formation of amphiboles in the talc; they can occur in the surrounding black-wall, also the serpentinite host rock is in direct contact with the talc. Thus allegations can be made non-asbestiform amphiboles or non-regulated serpentine group minerals can occur in the final products. INTRODUCTION Gunter (1994) wrote the following in regard to the question “What is asbestos? “The question yields different answers depending upon the audience. To a mineralogist, asbestos is a mineral form. To an engineer, it is an industrial material with several useful properties. To a medical doctor, it is an agent that might cause certain diseases. The third answer invokes several more issues: to a lawyer, a possible lawsuit; to a news reporter, a story; to an asbestos abatement worker, a job; and to a public school administrator or a parent, a nightmare.” The main function of that article was to try and provide background information to be taught at the college level to help students understand some of the issues associated with the use of asbestos in our modern society, and especially its use as a fireproofing agent in schools and public buildings. At that point in time one of the main issues was asbestos abatement as the mining and use of asbestos was waning as its health risks became more clearly known in the occupational setting. Now over 20 years later the current issue we are dealing with herein is “asbestos” occurring naturally in talc. This is a well know concern for those in the talc industry and they have been working on methods to ascertain if their products contained “asbestos” since last century. As such our articles will focus more on issues emerging from recent litigation, and the confusion that occurs, especially in the “asbestos” nomenclature as the mineralogist, engineers, doctors, and lawyers previously mentioned try to communicate. And lastly we need to remain cognizant of the fact that people are still dying of mesothelioma in the US. As a last resort to recoup expenses as they are dying they often respond to the TV advertisements we’ve all no doubt seen."

Jan 1, 2016

By Greg Sanders, Michael Gilbert, James G. Shaughnessy

"A new raw water intake from the South Holston River to the Kingsport water treatment plant is under construction. The exploration for the 335 meter long horseshoe shaped tunnel design took advantage of the site topography along the alignment to better define the complex geology consisting of Knox Limestone and Sevier Shale formations separated by a fault zone. To assess the geological conditions and to determine the extent of the fault zone, a 183 meter long horizontal boring and geophysical investigation was performed along a portion of the tunnel’s horizontal alignment. Explorations defined the fault zone width at approximately 5 meters and packer testing along the alignment provided a means of estimating groundwater inflows. As the tunnel excavation advances, comparisons of exploratory data versus encountered conditions will be made. This paper provides details on the geotechnical investigation, lessons learned, and the influence of the geology on the tunnel design. PROJECT OVERVIEW The Kingsport WTP is supplied with raw water via the South Holston River. The City of Kingsport (City) owns and operates the Kingsport Water Treatment Plant (WTP). The existing raw water intake system, consisting of pumps, power supply, raw water piping and appurtenant facilities has been determined to be vulnerable to failure. The original Raw Water Pump Station (RWPS) was constructed in 1928 as part of the original Kingsport WTP project. The 1928 RWPS operated until 1970 when it was replaced by the existing RWPS. This existing system still utilizes the 1928 piping and piping tunnel. Improvements to the RWPS hydraulics and capacity are required to meet the City’s future water treatment needs. The system extracts water from the South Fork of the Holsten River and coveys it via three pressure pipelines to the WTP. The conveyance piping exits the RWPS, ascends approximately 23 m up a near vertical rock outcropping then enters a 120 m long tunnel. Upon exiting the tunnel the piping continues underground to the WTP. The drill and blast tunnel is horseshoe shaped and nominally 3.3 m high by 3.3 m wide. The easternmost 62.3 m of the tunnel is without any type of support. The remainder is lined with concrete. According to the City of Kingsport, the concrete lining was installed in the 1970’s as part of upgrades to the facility. An evaluation of the current facilities concluded that the conveyance piping was in poor condition and required replacement."

Jan 1, 2016

By Carlton M. Ray, William P. Levy, Thomas Lindberg

"The District of Columbia Water and Sewer Authority (DC Water) is implementing its $2.6 billion DC Clean Rivers Project to reduce combined sewer overflows to the District’s receiving waterbodies and mitigate chronic sewer flooding in District neighborhoods. The First Street Tunnel project is a major component of the DC Clean Rivers Project, designed to mitigate sewer flooding and basement backups in the District’s historic and densely populated Bloomingdale neighborhood. Bloomingdale has been historically affected by sewer flooding and was severely impacted by four storms in the summer of 2012 that caused significant damage to homes, the environment and public property. As a result, DC Water accelerated the design and construction of the First Street Tunnel in order to mitigate the effect storms have on the undersized sewers serving the neighborhood. The infrastructure designed to mitigate flooding, including the tunnel, are located within the highly urbanized neighborhood – with some structures being less than ten feet from residents front door steps. The success of a large public works project of this magnitude and in this unique location depends on a well informed and supportive public. With the local community impacted by flooding but concerned about heavy construction impacts, this paper details the components of a successful public outreach plan and lessons learned throughout the design and construction process. Early identification of community mitigation, working cooperatively with stakeholders and frequent dissemination of accurate information required the project team to establish a culture of problem solving collaboration with the community. BACKGROUND Chronic Flooding in the Northeast Boundary Sewershed The Northeast Boundary sewershed, in which the Bloomingdale neighborhood is located, is served primarily by a combined sewer system and has a long history of chronic flooding problems during moderate to severe storm events. The sewer system that serves the Northeast Boundary drainage area was constructed by the Federal Government in the late 1800's when developed areas of the District terminated at what is now Florida Avenue. Since construction of the system, population within the sewershed area has grown at an exponential rate. In meeting the growing needs of the population, the District experienced development that transformed previously low-density rural areas into new communities. Impervious areas have increased drastically since the sewer system was constructed and consequently, the existing sewer system does not have the capacity to convey storms with return frequencies beyond the 2-year storm without flooding. As a result of the capacity limitations, many of the low-lying areas have become chronic flooding areas due to the surcharging of sewers."

Jan 1, 2016

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