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By Yngve Jordal, Sverker Hartwig

The IVAR Project is Norway's largest sewer project presently under construction. One part of it is an 8.1 km (26 575 ft) long, 3.5 m (11 ft 6 in.) diam tunnel, bored in one year. The tunneling project has been running smoothly; however, not everything has been easy. A few of its features are highlighted in this paper: The use of 9 0 (12 cu yd) muck cars on a double track back-up in such a comparatively narrow tunnel. Employing only four men in the tunnel, including the loco driver. A quartzite dyke - 96% quartz with 350 MPa (50 000 psi) and more compressive strength - turned out to be 640 m (2 100 ft) thick instead of the predicted 90 m (300 ft). Passing under a gaseous swamp with only same 5 m (16 ft 5 in.) of rock cover on top.

Jan 1, 1991

By Wm. Ross Wayment, Innes P. Grantmyre

INTRODUCTION It has been recognized for some time that major changes in mining methods will be required in the near future. Two types of factors contribute to this need for change. Intrinsic factors include ground control problems associated with mining at increasing depths, noise, dust, toxic fumes, and logistics problems which arise from operation in a cyclical fashion. Extrinsic factors include competition for labor from industries offering safer and less difficult work, pressure for less impact on the environment, and changing economic and political conditions. The search for new mining methods has resulted in extensive research being carried out on such novel approaches as thermal fragmentation, high-pressure water jets, sonic drilling, microwave fragmentation, and laser cutting, among others. Joy Manufacturing Co. has elected to concentrate on impact breaking in stopes as a first generation continuous hard rock miner. IMPACT BREAKING Fragmentation techniques show a drop in specific energy as efficiency improves. Specific energy is the energy consumed per unit volume of rock removed and is affected by such variables as rock material properties, fragmentation method used, operator skill, tool design, etc. Mechanical fragmentation methods generally have specific energies much lower than that of the more novel methods. Table 1 shows impact breaking to have an efficiency exceeded only by that of drill and blast methods and it is this high efficiency which led Joy to impactors as the subject for research on potential mechanisms for continuous mining in hard rock.

Jan 1, 1976

By P. James

"INTRODUCTION Control of target stream acidity is widely used in MIW (mining influenced water). Tailoring pH (a measure of acidity) finds application for controlling key chemistry in both process and waste streams. Traditional lime addition for neutralization and precipitation is most often used but has high reagent costs and results in large amounts of mixed metal sludge requiring costly disposal. A new adaptation of BPS’s patented DEMET™ technology (Dynamic Electrolytic Metal Effluent Treatment) platform offers a potentially improved and “reagentless” alternative to traditional chemical addition for pH adjustment. Electricity rather than chemical addition utilized in BPS’s proprietary approach controllably tailors target stream pH. The method offers a simple, low-cost processing technique yielding cleaner treatment chemistry. BPS’s “green” approach may yield lower operating (OPEX) and life cycle costs and significant reductions (up to 50%) in sludge generation compared to conventional lime treatment. It can also allow new opportunities to generate revenue via selective recovery of valuable processing byproducts. Specific savings and revenues depend on the target site chemistries, details, and processing goals. A more detailed discussion of the process and its operational principles may be found in Reference One.[1] Here application of the BPS treatment to POx (Pressure Oxidation) leaching as an alternative to traditional chemical addition is examined. An example operation process flow for gold mining is considered.[2] Promising processing points for potentially replacing conventional processes with DEMET are noted. The possibilities for lowering OPEX costs, lessening sludge creation, and capturing various valuable byproducts and residuals are examined. Financial life cycle benefit estimates of the principal gains provided by DEMET application to the example operation are noted. Extension and generalization of the analyses to a wider range of scenarios is explored."

Jan 1, 2016

By Nathaniel Arbiter

In contrast to pyrometallurgy's 6000year history in metals production, hydrometallurgy is of relatively recent origin. The earliest reference to it was in the 16th century, with the first applications to copper in the 17th and 18th centuries. In the 19th century, increased demands for pure metal resulted in the development of electrolytic refining, and early in this century electrowinning. The rapid growth in copper production in the 20th century, particularly in the United States and Chile, stimulated the development of new technology for leaching and for the recovery of copper from leach solutions. In the past 25 years, solvent extraction has become a major factor by permitting novel leaching technology that produces dilute or complex solutions. In addition, solvents other than sulfuric acid, and chemical methods for precipitating copper metal are now of increasing interest. These are trends that should grow in importance with the need to process lower grade and more complex materials. The evolution of copper hydrometallurgy is reviewed. Key factors in recent major developments are presented with details of specific operations and with trends for the future indicated. The relative importance of copper hydrometallurgy is compared with that of pyrometallurgy in the light of probable changes in ore supplies and character.

Jan 1, 1994

By Daniel Connor, O&apos

The Cal-Sag Relief Sewer is a 2.6 m (8 ft 6 in.) diameter 9.1 km (5.7 mile) rock tunnel bored in dolomite for the Metropolitan Sanitary District of Greater Chicago. Included in the project are 18 shafts varying in depth free 70 m (230 ft) to 41 m (135 ft). This paper discusses how Healy/Vanessa reduced costs by eliminating conventional hand excavation by hoisting muck from a high production Robbins TBM (Tunnel Boring Machine) through small diameter drilled shafts and using a trailing rail-utility backup system.

Jan 1, 1985

By J. F. Brune, A. Verma

"Face ignitions in underground coal mines are a major risk for underground mining operations, as they can lead to methane or coal dust explosions. The 2010 disaster at the Upper Big Branch Mine resulted in 29 fatalities due to a methane and coal dust explosion initiated from a face ignition. Much research has been conducted to mitigate face ignition hazards, from water sprays to installing passive and active explosion barriers. Despite the increased use of water sprays in U.S. coal mines, there have been more than 50 documented face ignitions in the U.S. underground coal mines since 2010, indicating that this hazard still prevails. This paper will examine the statistics of face ignitions and gas explosion in U.S. coal mines based on MSHA data. It will study factors contributing to these face ignitions and outline best practices for their prevention based on experience and practices worldwide. INTRODUCTION Methane and coal dust explosions are one of the major causes of coal mine disasters in the U.S. and around the world. Such disasters have resulted in the large number of fatalities and loss of mine infrastructure. The recent explosion at the Soma coal mine in Turkey has caused the death of 301 miners (Mining Turkey, 2014). As documented by U.S. Mine Safety and Health Administration (MSHA, 2015a), the U.S. coal mining industry has also experienced several catastrophic mine explosions with accidents at Upper Big Branch mine, Darby mine, Sago mine and Jim Walter Resources No. 5 mine in the last decade, causing the deaths of almost 60 miners. Every explosion requires a source of ignition, the right amount of fuel and oxygen. In underground coal mines, methane acts as a fuel while ventilation air acts as a source of oxygen. The source of ignition may vary from spontaneous combustion, electrical equipment and switchgear, mechanical heat sources, face ignitions due to friction rock-on-rock or from cutter bits and lightning strikes. Under the right conditions, energy of less than 0.3 mJ is sufficient to ignite methane-air mixtures (James, 2007) that can result in a catastrophic explosion. Much research has been done to mitigate the methane explosion hazard by proper dilution, continuous monitoring of methane and elimination of ignition sources. Historical studies indicate that face ignitions are the major cause of explosion in underground coal mining operations worldwide (Belle, Carey, and Robertson, 2012). Statistics shows that most mine disasters were started from a small face ignition, which turned into a major explosion fueled by additional methane and coal dust (Belle et al., 2012). To investigate face ignition hazards, researchers must study potential ignition sources as well as potential explosive atmospheres near mechanical coal cutting operations. Statistical analysis of U.S. coal mine face ignitions reported by the U.S. Mine Safety and Health Administration (MSHA, 2015b) shows that several factors are responsible for face ignitions."

Jan 1, 2016

By Baha Abulnaga

Slurry pipelines are used in a number of countries to convey processed ore mixed with water over long distances from remote mine sites to ports or plants for further processing. In Egypt and Sudan, numerous mineral resources are scattered in remote areas. Through the years, Egyptian geologists have identified 268 sites for metallic ores and 386 sites for industrial nonmetallic minerals. A large portion of these sites are in the Eastern Desert in an area called the Nubian Shield. Similar sites are found in the Sudan where mining contributes to less than 1 percent of the gross domestic product (GDP). There are three important components of infrastructure needed to develop these resources ? power, water and transportation. While Egypt is able to satisfy 70 percent of its needs in iron ore from the Gadideh Mine in the Western Desert, it needs to expand its other resources to reduce imports heavily sedimented. Dredging of these sediments and transporting them by slurry pipelines would enhance an industry of bricks or agricultural development based on tailings technology often used in mining. This article explores the potential for slurry technology for opening new mines in the desert or recuperating the sediments of the Nile. The technology by itself would be new to both countries and would benefit from collaboration, particularly to de-silt the Nasser-Nubia Lake.

Jan 3, 2010

By K. V. S. Sastry, K. D. Lofftus

Mathematical modeling and computer simulation are two valuable quantitative tools that are being effectively applied to mineral process- systems. This paper presents an up-to-date assessment of process modeling and simulation, identifies a number of associated challenges and opportunities and discusses in detail sane of the aspects of applying the current state-the art modeling and computational tools.

Jan 1, 1989

By J. Kretschmann, N. Nguyen

"The Vietnamese economic growth of more than 5% per year leads this country to an enormous demand for raw materials. In the duration of ongoing expansion, the big challenge in the coming decades will be to make this process as sustainable as possible when it comes to economic, environmental and social objectives. Risk management especially in occupational safety and health (OSH) in enterprises is one of the most important tools to achieve this aim. But until now, this has not been taken into priority by Vietnamese coal mining enterprises. Main reasons for this situation can be found in deficient legislative conditions and in non-synchronized risk management systems. In contrast, Germany has implemented an adequate legal system and the German mining industry has gained lots of experiences in risk management, especially in occupational safety and health. This paper seeks to point out specific challenges how to improve occupational safety and health in Vietnam by transferring and applying German methods and standards."

Jan 1, 2011

The Awareness and Preparedness for Emergencies at the Local Level (APELL) program is a process that helps people prevent, prepare for and respond appropriately to accidents and emergencies. APELL was developed by the United Nations Environment Program, in cooperation with industry groups, governments and local communities. Since its beginnings in1988, the program has been implemented in more than30 countries. APELL is a tool for bringing people together to allow effective communication about risks and emergency response. The program provides a common-sense approach to accident prevention and response.

Jan 1, 2003

By H. Ipek

Industrial grinding machines used in the mineral processing industries are mostly of the tumbling mill type. These mills exist in various types: ball, rod, pebble, autogenous, and semi-autogenous. Balls and rods are traditionally media shapes used in the tumbling mills. In resent years, as an alternative to balls, grinding charges with various shapes are being used. Cylpebs are slightly tapered cylindrical grinding charges with length equaling diameter, and all the edges being radiused. Cylpebs of equal diameter and length have 50% greater surface area and 45% greater weight than balls of the same material. In addition, they have 9% higher bulk density than steel balls, or 12% higher bulk density than cast balls. An important advantage of cylpebs over balls is that cylpebs produce narrower granulometric distribution due to their shapes. However, some discrepancies were found in the literature regarding the milling performance of cylpebs in comparison with balls (Chi, 2004). In recent studies, Chi (2004) has provided detailed information on cylpebs and has compared these to balls in relation to media mass, size distribution, surface area, and input specific energy. Ipek (2006) has investigated the effects of cylpebs and balls with equal mass and surface area on the breakage rate of quartz, using cylpebs and balls separately. Similarly, Lameck and Moys (2006) have investigated the effects of balls and worn balls on breakage rate of material using worn balls as grinding environment. However, no study has attempted to investigate the effects of grinding environment other than balls on the brekage distribution. As indicated by Prasher (1987), the breakage distribution function is independent of the following variables in ball mills: hold-up (Mika et al., 1967; Kelsall et al. 1969), mill speed and ball load (Herbst and Fuerstenau, 1972), media load and ball density (Kelsall et al., 1973), mill diameter (Malghan and Fuerstenau, 1976), and powder charge (Shoji et al. 1980). The aim of the present paper is to compare the effects of cylpebs and balls on the breakage distribution function of quartz with respect to same mass and same surface area. BACKGROUND Comminution as a rate process is called kinetic approach. Studies on the kinetic approach are reviewed by Oner (2001). Oner states that grinding kinetics are based on studies by Kolmogorov in 1941 and that Robert (1950) is the first to suggest this approach. Later, Melzak, Loeveday, and Reid have improved the grinding kinetics equation; and, Austin and Lynch have conducted two basic studies on the analytical solutions of these equations. Considering the results of studies comparing the size reduction mechanisms, it has been accepted that breakage constitutes of two operations. These two basic operations, first defined by Epstein (1948), are those of selection of material for breakage and the distribution of breakage material to particle sizes smaller than the initial size (Lynch, 1977). Epstein defined the two operations as: ? Pn(y), the probability of breakage of a particle size in the nth step of the breakage process. ? F(x,y), the cumulative distributions by weight of particles of size x<y arising from the breakage of a unit mass of a size y. Probability of breakage is called a selection or a breakage-rate function (Si). Characteristics size distribution after breakage is called a breakage distribution or appearance function (Bi,j). Due to the difficulties in representing particle size distributions mathematically and constantly, the batch equation based on particle size fraction is suggested. Thus, as is the case in breakage distribution and specific rate of breakage, the breakage parameters were defined by batch grinding experiments conducted in laboratories (Oner, 2001). When effective breakage occurs in the mill, the breakage of material with single feed size fraction usually fits first order grinding kinetics and the specific rate of breakage values can be calculated through the slope of semi-log plot. The values of the breakage distributions are deduced from the size distributions at short grinding times where there is mainly size 1 material breaking and only small amount of smaller sizes to rebreak (Austin et. al., 1984). B values can be calculated by using BII. [ ] where j is the top size of the charge, Pi(t) is the cumulative percent undersize of i th size interval at the short grinding time which gives no more than about 30% broken out of the top size interval. Cumulative primary breakage distribution, Bi,j, is also defined in an empirical form by [ ] where xi is the top size and Bi,j is the weight fraction of primary breakage products. The parameters F, ? and ß define the size distribution of the material being ground. On plotting size versus Bi,j on log scale, the slope of the lower portion of the curve gives the value of ?, the slope of the upper portion of the curve gives the value of ß, and F is the intercept as in Fig.1. [ ]

Jan 1, 2009

By Sigurd L. Lamhauge, Karl Gunnar Holter, Svein E. Kristiansen

An innovative sprayable waterproofing membrane in combination with the traditional Nordic method of waterproofing with polyethylene foam sheets was used for the waterproofing of the tunnel. The sprayable membrane was integrated in the final sprayed concrete lining in a sandwich structure, hence constituting a composite water-proof lining based on sprayed concrete. The spray able membrane was applied in areas with small to moderate water ingresses, making up approximately 50% of the total area requiring waterproofing in the tunnel. State-of-the-art application technology with a computerized spraying robot was used. A consistent application of the required thickness at a high speed was thereby achieved.

Jan 1, 2007

By Christopher M. St. John, Tony F. Zahrah

Empirical and numerical methods are the two extremes of the tools available for the seismic design of subsurface excavations and underground structures. Both have their limitations: when relying on purely empirical methods directly relevant experience may be scant; site data may be insufficient to justify a comprehensive dynamic analysis. The primary purpose of this paper is to review the analytical tools available to the design engineer of subsurface excavations and underground structures. Particular attention is devoted to simplifed models that appear to be applicable in many practical cases.

Jan 1, 1985

By S. E. Phillipson

The Mine Safety and Health Administration?s (MSHA) Roof Control Division (RCD) collects a variety of geological and engineering information pertaining to mining conditions in surface and underground mines throughout the United States. Recently, lineament analyses, trends of geologic structures, and inferred stress directions based on mapping at mines with problematic ground conditions, have been integrated into a GIS. The incorporation of different kinds of information into the same geographic coordinates and map projection, placed on digital geologic maps, allows site specific data to be evaluated in a regional geospatial context, identifying trends in the orientation of horizontal stress or patterns of structural geologic features. As more information is collected, the GIS will evolve as a tool for district- and basin-wide evaluations of controls on ground instability, and may evolve into a predictive tool for some kinds of geologic hazards. In addition to the geologic and geotechnical evaluations, the GIS also serves as a searchable database of previous mine investigations. The database can be searched for a variety of criteria, and the results displayed in real geographic coordinates to find the locations of previously visited mines or to evaluate mine fatality and injury data. This not only allows old reports to be found, but also places the information in a geospatial context with respect to neighboring mines or geographic areas. The GIS also has the capability to serve as a digital mine map repository, where maps can be stored in digital, georeferenced format for display in relation to each other and various themes of interest. This allows evaluation of multiple seam mining interactions and proximity to other mines, and on a national level could serve as an abandoned mine map database.

Jan 1, 2008

By Steven E. Mischler, Jay F. Colinet

The study analyzes the impact of the Continuous Personal Dust Monitor (CPDM) on reducing overexposures to coal mine dust. It compares compliance sampling data before and after the implementation of the CPDM and the 2014 MSHA dust rule. The results indicate a significant reduction in the percentage of samples exceeding the dust standard for various mining occupations, highlighting the effectiveness of the CPDM in improving miners’ health and safety.

Feb 22, 2022

By Yao Zhou

Under the United Nations Convention on the Law of the Sea (UNCLOS), the international seabed area (Area) and its resources are the common heritage of humanity (CHH). Patent rights can be incompatible with the CHH doctrine and its underlying principles because patent holders might charge unjustifiably high prices to license patented technology for exploring and exploiting the Area’s resources (creating a "patent holdup" situation), might choose not to license, or might license exclusively when doing so would contravene CHH principles. However, a reasonable patent licensing regime can contribute to sharing the benefits derived from the Area and promote environmental sustainability. Provisions of the UNCLOS that stipulated compulsory technology and financial transfers were removed in the 1994 Agreement relating to the Implementation of Part XI of the UNCLOS but to promote equity and sustainability I propose a voluntary licensing regime modeled on the concept of reasonable and non-discriminatory patent licensing that has been used in other contexts. The International Seabed Authority or another entity will need to coordinate and promote this licensing regime through governance of intellectual property derived from the Area. This proposed approach can better effectuate the CHH doctrine and its underlying principles.

Sep 1, 2014

By William D. Leech

Lebanon used a TBM for the firsttime to excavate a tunnel in the country. A main beam TBM, built in 1979, bored the 3.8 m (12.5-ft) diameter by 4,020 m (2.5-miles) Madiq Tunnel. The TBM bored through karstic terrain of dolomitic limestone, limestone and marly-limestone rock having near horizontal beds with more than twelve faults crossing the axis of the tunnel. The TBM also encountered more than six major karst features, filled with various combinations of boulders, clay, void space and water. The excavation through these collapsed-breccia zones drastically slowed the TBM?s progress. When complete, which the Madiq Tunnel is a part, the Kesrouane Water Project along the coast will bring fresh and irrigation waters to the parched and heavily populated region north of Beirut. The paper will describe the tunnel geologic features, karst genius, TBM upgrades and performance, and TBM/karst difficult situations

By S. J. Schatzel

Longwall coal mine operators in the US are required to ventilate multi-panel longwall districts but may have little or no knowledge about what happens to the ventilation air between the inlet evaluation points (IEPs), bleeder evaluation points (BEPs), and bleeder fans. The effectiveness of bleeder performance can directly influence the ability of a ventilation system to remove and dilute coal bed methane emissions. Consequently, the performance of coal mine bleeders is an important aspect of underground worker safety. U.S. coal mining stakeholders have acknowledged their belief that the T- junction split at the longwall face tailgate corner is very important in controlling the distribution of ventilation air. The percentage of air directed inby towards the bleeders and bleeder fan and outby to the submains is often not well-defined and can vary over the life of a longwall panel. To obtain direct measurements of bleeder performance, a tracer gas, sulfur hexafluoride (SF6), was released into the intake air stream along the panline of active longwall panels and in the bleeder/gob ventilation air inlets of an inactive panel. Tracer gas sampling was conducted underground using tube bundles attached to permissible vacuum pumps in the gateroads, former gateroads, and bleeders. Surface tracer gas monitoring was also conducted from operating gob boreholes and from bleeder fans. Testing was performed on multiple longwall panels which included various phases of longwall development and variable path lengths of ventilation air transport to bleeder fan installations. The applied methodology defines and describes coal bed gas pathways, rates, and volumes of movement at the bleeder/gob interfaces, and indicates flow rates for air/gas mixtures within these gobs. These findings are reported for three stages of longwall extraction using direct field-based measurements. Changes in the T-junction ventilation air distribution over the life of a longwall panel and its variable effect on panel ventilation airflow are discussed. These findings will assess the effectiveness of commonly applied ventilation strategies for improving air distribution and ventilation controls to meet statutory requirements and to achieve the desired ventilation patterns through multiple phases of longwall panel extraction.

Jan 1, 2011

By Jerry C. Tien

Changes and the pace of change in China’s coal industry have been extraordinary during the past several years. At least 35 of the 94 former coal bureaus have been restructured into different mining companies and groups. Some of the more productive and efficient ones were further strengthened through consolidation and expansions. And several have even formed, or are in the process of forming, strategic alliances with utility companies, railroads, ports and chemical companies to secure additional reserves and coal sales. In addition, the improvement in coal pricing during the past two years has enabled China’s coal industry to move ahead with some needed changes. Coal mining accidents, though, remain a major concern for the Chinese government. Accidents remain high even though the government has made efforts to shutdown more than 55,000 unlicensed, unsafe small coal operations throughout the country.

Jan 1, 2003

By E. Snyders

Two alternative processes for the manufacturing of zircon products were investigated by the South African Nuclear Energy Corporation (Necsa). These were the synthesis of doped-zircon pigments from plasma dissociated zircon, and an upgrading process to convert an inferior grade of zircon into a superior opacifier for ceramic applications. A solid-state reaction process was used to produce doped-zircon pigments. The influence on the colour intensity of the pigments on a ceramic tile were compared for milled and un-milled plasma dissociated zircon (PDZ) material, prior to calcination. Pr-yellow and V-blue zircon pigments produced from PDZ with different degrees of dissociation, were also evaluated. The second zircon beneficiation process entails the upgrading of an inferior grade of zircon to a superior opacifier for ceramic applications. A calcining process in the presence of mineralizers was used to produce the product in a conventional muffle furnace. A pre-milled inferior grade zircon concentrate, with a relatively high iron and alumina content generally not suitable for high quality ceramic applications, was used in this study. The influence of the upgrading process on the opacifying properties of the zircon material was compared to that of commercially available prime grade zircon opacifier products currently being produced in South Africa. The influence of a calcining step in the presence of mineralizers with regard to the milling characteristics of the treated zircon material was also evaluated.

Jan 1, 2005