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By M. K. Boateng, K. Awuah-Offei

"Language barrier in a workplace affects workers’ productivity and safety. The objectives of this paper are to: (1) review the various approaches for breaking language barriers among miners; and (2) analyze the costs and benefits of these approaches, and make recommendations on the way forward. The authors achieve these objectives by reviewing the current approaches in breaking language barriers among miners. The review reveals that some of these approaches can be expensive with less benefits. Thus, it is concluded that mining companies should carefully select the optimal approach to break language barrier. INTRODUCTION Multi-national mining companies have expanded their operations into non-traditional mining destinations to grow and meet market expectations. For instance, Newmont Mining Corporation has about 14 operations and projects located in Africa, Asia, Australia and America (Newmont Mining Corporation Operations and Projects, 2015). Similarly, Freeport-McMoRan operates about 14 mines in North America, South America, Southern Asia, and Africa (Freeport-McMoRan Inc., 2015). Some mining companies have also attracted expatriate workers into their workforce. For example, Ma’aden, the Saudi Arabian mining company, in its 2013 annual report states that 34% of its total employees are expatriates (Ma'aden, 2013). Expatriates constitute a key source of skilled labor and facilitate skill transfer. The success of many international operations relies greatly on expatriate performance (Erbacher, D'Netto & Espana, 2006). Even companies that do not expand their operations into other foreign countries still have to deal with language barriers due to changing language demography of the country and the areas from which labor is sourced. For example, the language composition of the workforce and languages used in South African mines is diverse with miners proficient in Afrikaans, English, Zulu, Xhosa and others to varying degrees (Research Focus (Pty) Ltd, 2011). As a result of these trends, most mines today operate with a multinational workforce. This means cultural differences, including language barriers, exist among the miners. Marschan-Piekkari, Welch and Welch (1999) emphasize the fact that language problems become prominent as companies internationalize and grow their operations into more countries. According to a survey by Forbes, language barrier affects operations. For example, business owners acknowledge that language proficiency may promote a safer work environment (Rubin, 2011). A research has shown that language and cultural barriers in a workplace contributes to reducing workers’ productivity, increasing accidents, and hurts employers’ ability to recruit, hire and retain workers (Morris, 2002). Hence, mines are making efforts to break language barriers in their operating environments. Ma’aden, for instance reported in 2013 that 1,506 of its employees received training in English as a second language (Ma'aden, 2013)."

Jan 1, 2016

By Bauer, Steve, Colin Goodwin, Gerald, Randy Dempsey, Courtland

"The City of Ottawa’s Combined Sewage Storage Tunnel consists of two interconnected tunnels totaling 6.2 km with a diameter of 3m including access shafts and hydraulic structures which connect to the City’s most critical sewers. This tunnel will be built 15m to 30m below ground in the downtown core adjacent to, and crossing below, the Light Rail Tunnel, which introduces additional considerations in terms of sequencing and risk mitigation. The City embarked on a unique Procurement Process to address the risks involved with a large tunnel project and those associated with tunneling below downtown, underneath and adjacent to UNESCO World Heritage Sites, and connecting to live critical sewers. This paper describes the unique procurement approach employed and the contractual risk mitigation measures developed to provide the best value while minimizing risk. Specific features include Market Sounding, using a Fairness Commissioner, Contractor Prequalification and Risk Mitigation Measures in the Tender documents. INTRODUCTION This paper describes how the City of Ottawa (the City) and the project design team developed a strategic Procurement Process and Tender that incorporated industry best practices for technical and contractual risk management for the Combined Sewage Storage Tunnel (CSST) project. The process was unique in that, while it employed a systematic review of project risks, it also solicited input from industry, stakeholders and provincial and federal partners to develop the request for Tender for this traditional design-bid-build project. Key drivers for this approach were initiated from the City’s concerns for cost control, cost certainty and overall project risk mitigation. To address these concerns, the City implemented the risk review and mitigation process right from the project design team selection. It was critical that the project design team embraced this risk management philosophy and carried it through each phase of the project. This paper serves as an excellent resource for municipalities or other owners embarking on a similar tunnel project, on how to properly apply industry best practices and the benefits of using them."

Jan 1, 2016

By P. Henderson, M. E. Morris, W. A. Johnson, F. D’Alessandro, D. Wilton

"The objective of this research is to develop and apply computer models to evaluate the potential lightning impacts on underground coal-mining. These models can then be utilised to assist in the design of effective controls. This project will provide a significantly improved level of knowledge and control over current lightning abatement techniques. The findings may also be applied to open cut and coal preparation situations. Computer modelling identified that by isolating cased boreholes from underground conductive media such as roof mesh, and placing spacings between roof mesh the risk of an ignition can be reduced by more than a factor of ten. These controls should be applied in conjunction with minimising the potential for a flammable atmosphere to exist underground and ensuring that there is no transmission medium for the lightning to reach the atmosphere. INTRODUCTION The objective of this research was to develop and apply computer models to evaluate the potential lightning impacts on underground coal-mining. These models could then be utilised to assist in the design of effective controls. If successful this project would provide a significantly improved level of knowledge and control over current lightning abatement techniques. The direct potential for harm from lightning has long been recognised for the surface facilities of coal mines. However recent events at Blakefield South in NSW on January 5 2011 (DTI, 2011) and at Sago mine in the USA in 2006 (MSHA, 2007) have suggested that there is potential for lightning to cause significant damage to the underground workings of a coal mine. A very detailed analysis carried out by as part of the MSHA investigation into the SAGO disaster by Sandia Laboratories identified at least ten other incidents over the past thirteen years where lightning had probably caused the ignition of a sealed goaf area of a mine (SANDIA, 2011). In addition there is a long history of lightning related incidents in South African coal mines (Geldenhuys, 1985). Fortunately in those cases no lives were lost. The event at Blakefield South has suggested that there may be the potential for ignition to occur in an active longwall goaf. The potential for a lightning strike to ignite a flammable atmosphere in an underground coal mine has been demonstrated from the past experience both here and overseas. It requires three things: • Lightning • A mechanism to convey the lightning underground to the flammable atmosphere • A flammable atmosphere."

Jan 1, 2016

By Kevin Fitzpatrick, Carmen Scalise, Patrick Jensen

"The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) owns and operates the Tunnel and Reservoir Plan (TARP) system which was adopted in 1972. TARP is a network of 110 miles of deep tunnels and ultimately 3 large reservoirs to combat waterway pollution and flooding within a 350 square mile area served by combined sewers. The original TARP concept included additional tunnels to convey CSOs from the largest storms to the reservoirs. With the initial TARP tunnels complete and the reservoirs nearing completion, MWRDGC commissioned hydraulic and hydrologic modeling studies to analyze the benefits of additional conveyance tunnels. These updated studies optimized the configuration of additional tunnels considering integration with potential future local sewer system upgrades. The alternatives considered several routes of 25, 30, and 35 foot diameter tunnels, ranging from 10 to 18 miles. Alternatives were analyzed based on projected reductions to basement flooding compared to the relative costs. TUNNEL AND RESERVOIR PLAN After World War II the Chicagoland area underwent rapid growth and development. With the Metropolitan Water Reclamation District of Greater Chicago's (MWRDGC) service area becoming increasingly impervious, the flat Chicago landscape was increasingly at risk of significant flooding. In the mid and late 1950's, Chicago experienced multiple extreme storm events that had significant impacts on the city and generated the momentum necessary to initiate what would ultimately become one of the world's largest civil works undertakings. In 1957 a Flood Control Coordinating Committee was formed, consisting of representatives of the MWRDGC, Illinois Department of Public Works, Cook County, and the city of Chicago, to review various plans and develop recommendations for a course of action. With more than 50 alternative concepts being identified, the Tunnel and Reservoir Plan (TARP), which itself is a composite of various alternatives, was adopted the by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) in 1972. The need to adopt a long term plan was further influenced by the Clean Water Act, which was enacted only 8 days prior."

Jan 1, 2016

By Rick Bearce, Minsu Cha, Mike Mooney, Yuanli Wu, Lisa Mori

"Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. Chamber pressures can reach 3-5 bar yet the vast majority of testing is performed under atmospheric conditions. This paper illustrates how pressure influences foam stability and conditioned soil behavior, and how atmospheric test results must be viewed in the context of expected chamber pressures. Torsional shear strength, compressibility and abrasivity of foam conditioned sand were found to be ideal when the void ratio was above the ASTM-determined maximum void ratio, achieved by sufficiently expanding the soil grain structure with foam, herein when the foam injection ratio at pressure exceeded 45%. Otherwise, the engineering properties of foam conditioned sand were not ideal, i.e., appreciable torque and abrasivity, low compressibility. INTRODUCTION Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. The formation soil at the cutterhead must be transformed into a highly compressible, low shear strength and low permeability medium within the excavation chamber to allow effective EPB performance. This behavior must be maintained for a certain residency time while the soil is in the chamber and screw conveyor. The vast majority of published studies on conditioned soil behavior have been performed under atmospheric conditions (Quebaud et al., 1998; Bezuijen et al., 1999; Psomas and Houlsby, 2002; Vinai et al. 2008; Thewes et al., 2012; Peila, 2014); however, the desired soil behavior must occur under chamber pressures that can reach 5-7 bar. The influence of pressure on conditioned soil is significant and is dramatically different than behavior under atmospheric pressure (Williamson et al., 1999; Mori et al., 2015). This paper illustrates how pressure influences conditioned soil behavior and how atmospheric test results must be viewed in the context of expected chamber pressures. The influence of pressure on foam bubble size (including with time) is shown through digital image analysis. The influence of pressure on foam half-life is also investigated. The compressibility, shear strength, and abrasivity of conditioned soil under pressure is presented and explained in terms of density, soil and air compressibility and porosity."

Jan 1, 2016

By L. Vinnett, J. Yianatos, S. Flores

"A numerical conditioning analysis for mineral recovery estimation was performed for industrial flotation plants, considering the copper (Cu), molybdenum (Mo) and iron (Fe) separability. A modified relative condition number, ?, was presented that allowed sensitivity analysis to be evaluated for the component recovery by means of an analytical formula. This closed form made it possible for the error propagation to be determined from feed, concentrate and tail grades with different orders of magnitude. The ? parameter can be evaluated using available grade data from the design criteria or historical mass balances, in which the variability is typically unknown. Reconciled data from different Cu/Mo concentrators were employed to evaluate the effect of small numerical disturbances in the grade data on the mineral recovery estimation. Higher error propagation was typically observed for Fe. The Mo minerals presented numerical problems, mainly in second cleaners and in the first cell of rougher banks. Lower condition numbers were observed for Cu due to the higher flotation rates.Mass-balance data reconciliation without redundancy was evaluated for a typical Cu/Mo flotation circuit using relative error minimization. Significant relative errors in the mineral recovery estimation were obtained with nonreconciled data in ill-conditioned problems. Negligible improvements in the mineral recovery estimation because of the data reconciliation with regard to the nonreconciled approach were obtained in well-conditioned problems. In addition, the improvements in mineral recovery estimation by using Cu, Mo and Fe in the data reconciliation were nonsignificant with respect to using only the best-conditioned component in well- and ill-conditioned problems.Despite the effort in data reconciliation and data repetition, poor performance may be obtained in ill-conditioned problems, which can deteriorate the flotation rate characterization. The error propagation has a negative impact on the mineral recovery of the first cell, which may significantly bias the flotation rate characterization of both valuable and nonvaluable elements.IntroductionMass balances have been extensively used in flotation processes to determine the mass flowrates (production) and mineral recovery (efficiency) of valuable minerals. Simple relationships for steadystate processes based on the feed, concentrate and tail grades can be obtained by taking a black-box approach. However, the calculation of concentrate flowrates from different components of the system, such as size fractions, chemical elements or minerals, does not satisfy the mass-conservation principle because of measurement errors (Smith and Ichiyen, 1973; Romagnoli and Sánchez, 2000). Mass-balance data reconciliation allows for obtaining a unique solution that satisfies the total and component mass balances, making small adjustments to the process data and taking advantage of the information redundancy (Narasimhan and Jordache, 2000). This methodology, which is based on a constrained weighted least-squares minimization, has proved to be robust when measurement errors are normally distributed, in the absence of gross errors.Commercial software has been developed to conduct massbalance data reconciliation in flotation processes, including MATBAL (Algosys, 2002), BILMAT (Algosys, 2013), JKMultibal (JKTech, 2013), BILCO (Caspeo, 2013) and HSC Chemistry (Outotec, 2013), which accomplish the reconciliation using known data accuracy in the optimization problem. The data accuracy can be obtained by sampling a stream n times in a run, known as repeats, each with independent chemical assays. Some unmeasured variables can be estimated using the measuring redundancy and sensor location. At present, grade and flow rate sensors may be incorporated in flotation to conduct real-time mass balances. However, a lack of sensor calibration and maintenance for suitable online measurements hinders the quality of the information. In"

Jan 1, 2016

By Aldo Bellone, Francesca Rossano, Massimiliano Bringiotti

"In 2004 works started for the now completed seven-level automated car park accommodating 480 parking spaces inside the pre-existent “Morelli cave”, located in a strategic area in Naples. Since 470 BC Greeks initiated the growth of the fascinating world of the underground Naples, of which this cave belongs. It seems that once here the god Mithras was worshiped. It’s also became a quarry for tuff extraction and in 1600s it became an aqueduct serving the area. In 1853 the Bourbon Tunnel, a project commissioned by King Ferdinand II of Bourbon to allow easy escape from the Royal Palace in case of riots, was connected to this network of tunnels. The cavern became an air raid shelter during the Second World War, then a deposit of cars and motorcycles in the '50s and' 60s, a disposal area and it has been abandoned in the last 40 years before it’s new utilization. INTRODUCTION Over time, the overcrowding and congestion of major cities’ historic centres has led to seeking spaces underground that can accommodate activities and car parks, as in the case of the Morelli cavity, site of the future car park by that name. Before describing its characteristics, design solutions, and executive problems, it is necessary to introduce the site historically into the broader landscape of the cavities present below ground in the municipality of Naples. The province of Naples, which includes the area of the Municipality of Naples, has a large number of cavities. The existence of “Naples underground” is connected with the morphological and geological conformation of its territory, consisting of tuff stone which has entirely special features of lightness, brittleness, and stability. The first transformations in the territory’s morphology, taking place thanks to the Greeks starting from 470 BC, initiated the growth of the fascinating world of Naples underground. These transformations were dictated by water provision requirements, which led to the creation of underground cisterns to collect rainwater, and by the need to recover construction material to erect the buildings of Neapolis. In subsequent centuries, the city’s expansion led to the construction of a proper aqueduct, which allowed drinking water to be collected and distributed thanks to a series of cisterns linked to a dense network of tunnels. During Roman rule, the existing aqueduct was expanded and perfected, but with the rise of the Angevins in 1266, the city saw great urban expansion, which obviously corresponded with increased extraction of tuff from the subsoil to construct new buildings. This confirmed a particular feature of Naples: that of having been generated from its own innards, with buildings rising directly above the quarry that provided their building material."

Jan 1, 2016

By Matteo Cortinovis, Giuseppe Gelmi

"INTRODUCTIONEdilmac dei F.lli Maccabelli (hereinafter referred to as Edilmac) has recently developed a special civil engineering application using the Raise Boring technology with the assistance of Inrock MGS (Magnetic Guidance System). Applying the Paratrack Magnetic Guidance System coupled with a directional mud motor to the drill string allows a better accuracy compared to standard drilling, as showed in our tests. This is the first time the Paratrack System has been applied to the Raise Boring technology. RAISE BORING METHOD STATEMENT The Raise Boring technology was born in North America during the Sixties. In 1962, Ingersoll and Robbins were the first companies to produce Raise Boring Machines (RBM). The technology was first used in the underground mine industry, in order to bore ventilation shafts and passes through different levels, thus reducing the cost of haulage. The Raise Boring method is only feasible in stable rock conditions. The Raise Boring method consists of drilling a small diameter pilot hole that reaches a tunnel located at the bottom of the drilled hole. Once the pilot hole reaches the tunnel, a reamer head is installed at the end of the drill string and pulled up, creating the hole with the designed diameter (Figures 1 and 2). The main equipment, which is required to perform Raise Boring activities, is the following: •,An RBM; •,A tricone bit; •,Drilling rods; •,A reaming head; The standard mucking of the pilot hole is done with water or bentonite mud. For the last 30 years, Edilmac has developed a mucking process, which uses compressed air with the addition of foam or a small amount of water for dust control.Pilot hole tricone. The drilling of the pilot hole is usually performed with a tricone bit having a diameter between 11” (27.61 cm) and 15” (38.10 cm) (Figure 3). High strength rods. They generally have a diameter ranging from 10” (25.40 cm) to 12 ?” (32.70 cm) (Figure 4), depending on the length and the final diameter of the shaft."

Jan 1, 2016

By Brian Gettinger, Jim Schlaman, Alston Noronha

"INTRODUCTION The public understanding of green solutions today is based on the definition of sustainability adopted by the Brundtland Commission (World Commission on Environment and Development) in 1987: “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” Over time this initial definition evolved to identify three distinct factors impacting sustainability that are often referred to as the “Triple Bottom Line”: Economic, Environmental and Social. The triple bottom line approach seeks to drive outcomes that create maximum value for all stakeholders. In the last ten years purveyors of water and wastewater tunnel solutions have found themselves on the wrong side of a politically polarizing issue in the crosshairs of politicians, environmental activists and community groups branding tunnels as expensive, “gray” and not-sustainable. Tunnels under design were stopped and large planned tunnel programs were delayed or canceled. Therefore being sustainable and “green” is not simply using natural vegetation, but creating an asset that meets current and future needs and will not become a future liability. As this paper will discuss, tunnel projects embody a sustainable triple bottom line project well, are equally sustainable as green infrastructure, and have begun to gain awareness for their sustainability. GREEN INFRASTRUCTURE CHANGES TUNNELING LANDSCAPE The green movement quickly swept across the nation in the mid to late 2000’s and was a hot topic in the media and at all the local, regional and national industry conferences. Politicians espoused the benefit of green infrastructure including job creation, urban renewal, aesthetics, property values economics and sustainability. The political microscope was focused the closest on stormwater and wastewater management, particularly in communities responding to combined sewer overflow (CSO) consent decrees from the Environmental Protection Agency (EPA). As communities with CSO problems evaluated their long term control program (LTCP), local government officials and planners began to balk at the huge price tag required for compliance and began looking for alternatives. “Green” infrastructure was proposed as lower cost solution that could be used to offset capital-intensive “gray” infrastructure like new sewers, storage tanks, tunnels, and treatment facilities. In addition, including green infrastructure in a previously negotiated LTCP required a reset on the entire planning process, additional studies and more planning which would push capital investment further off into the future, subsequently delaying unpopular user rate increases. As a result, tunnel projects as well as trenched conveyance and treatment plant projects that had not yet started construction were stopped, delayed or substantially changed."

Jan 1, 2016

By T. Faulkner, S. A. Richards

"The Scale-Distance formula is one of the primary means of determining the maximum amount of explosives that can be safely detonated at one time by a single delay. This paper describes a method of applying the Scale-Distance formula to the entire mining area using gridded surfaces. Using this technique, the operator can better determine the economic impact of nearby structures on the mine plan. INTRODUCTION As the surface mining of coal and stone encroaches near populated areas, precautions must be taken to minimize blast vibration damage to protected structures. The common method employed to minimize vibration damage is not to reduce the total amount of explosive in the hole (which would negatively affect fragmentation), but rather to introduce delays to reduce the amount of explosive detonated at any point in time. The Scale-Distance formula, an industry-accepted standard, may be used to calculate the maximum weight of explosive that can be detonated at one time without damaging the structure. This information may then be used to determine the number of delays required for each hole. Detonators make up a large part of the cost of blasting. At roughly $15 per detonator an additional detonator in the hole can be significant. It is normal to set off hundreds of holes at in one shot. An additional detonator in each hole can cost additional thousands of dollars per shot. The number of detonators is also a function of the depth of the holes and the hole spacing. Being able to accurately forecast the economic impact of blasting near structures improves a company’s ability to make informed decisions on how to approach property owners. Operators basically have three options when dealing with property owners: 1. Buy the property and blast without restriction 2. Negotiate with property owner for a waiver to allow unrestricted blasting 3. Comply with the legal blasting restrictions This paper proposes a method for the engineer to forecast for all points in the proposed mining area the impact of nearby structures upon the blast design. Being able to create a contour map and ultimately estimate the number of delays required for the entire forecasted mining area, the engineer can create accurate economic forecasts of the cost of blasting. The objective is to reduce the level of uncertainty in the forecast of the blast component portion of the forecast."

Jan 1, 2016

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and galvanodynamic and chronopotentiometric techniques were used to characterize the effects of DXG-F7®, a commercial smoothing agent, on copper electrodeposition onto 316L stainless steel from a synthetic electrolyte containing 40 g/L copper (Cu2+), 160 g/L sulfuric acid (H2SO4) and 20 mg/L chloride (Cl-) at 40oC. The findings were compared against results using HydroStar® 4208, a modified polysaccharide. The nucleation overpotential and plating potential observed in cyclic voltammetry and galvanodynamic testing showed that neither DXG-F7 nor HydroStar significantly polarized acidic copper electrodeposition. Subtle differences between the additives were found during EIS testing and modeling, but more research will be needed to fully understand these differences. Surface-roughness measurements of two-hour deposits indicate that DXG-F7 and HydroStar produced smoother deposits as their concentrations in the electrolyte increased. No difference in the surface roughness of deposits was detected between the additives. Based on the experimental evidence resulting from the laboratory testing, no significant difference was found between DXG-F7 and HydroStar at 20 mg/L Cl- concentration, with the exception that DXG-F7 dissolves more easily in water than HydroStar. Introduction Cathode deposits obtained from acidified copper sulfate electrolyte(s) without organic additives are often soft, coarsely crystalline and nodular (Sun and O’Keefe, 1992). Therefore, small amounts of organic additives are added to the electrolyte to produce level and dense cathodes during copper electrowinning. The action of organic additives is thought to be due to their adsorption on the surfaces of the newly formed copper grains. Hence, any copper grain that grows excessively fast adsorbs a layer of organic additive, which inhibits growth. The result is a smoother and harder deposit of suitable purity (Sun and O’Keefe, 1992). In part I of our four-part series on the examining of copper electrowinning smoothing agents, a review of previously published work on organic additives used during copper electrowinning was presented (Moats, Luyima and Cui, 2016). In the review, it was noted that many tankhouses had switched from guar to other saccharide-based products such as HydroStar and DXG-F7."

Jan 1, 2016

By A. Mull, J. Weyer, J. Brune

"The “Reiche Zeche” mine in Freiberg, Germany, a 600-year-old lead-zinc-silver mine with extensive open mine workings, experiences severe ventilation losses due to leakage. Much air leaks into abandoned workings, decreasing the airflow available to active working areas. Usually, this leakage occurs in remote areas that lack transportation infrastructure like roadways or rail, making it difficult to haul construction materials to the sites to erect passive ventilation controls such as stoppings, regulators and seals. Transportation distances make it impractical to hand carry traditional construction materials, such as bricks and concrete. Alternative materials, such as brattice, foaming polymers, concrete canvas, and some innovative ventilation control designs have been investigated for this purpose. The suitability of the materials investigated depends on many factors including the pressure it can withstand, the ease of transportation, and workability. Impacts of mine water must be considered, as the Reiche Zeche is below drainage and experiences significant inflow of water. Researchers must consider the effects water inundation as well as how the stopping construction material reacts to being exposed to acidic mine water. INTRODUCTION Problem Statement Mining in the area around Freiberg, Germany began in the 12th century. The mine is used for research, mining engineering education, tourism and air conditioning for a local hospital. The first records of mining in the Reiche Zeche are from around 1384. Due to the strength and competency of the host rock, many of the oldest workings still stand and remain open today, although they may not be accessible. Reiche Zeche also connects to several other, closed mines in the area that are largely unmapped. This allows air to leak into neighboring mines, reducing the air available to ventilate to the working areas of Reiche Zeche. In order to improve ventilation efficiency, it is necessary to control the ventilation and reduce leakage by constructing seals, stoppings and regulators. A challenge with building traditional seals and stoppings in the Reiche Zeche is that the old workings lack transportation pathways or rails. Also, the lack of compressed air, water or electricity makes it difficult to operate power tools and drills. This means that construction materials must be hand carried – some over distances of several kilometers. Figure 1 shows a typical drift in the Reiche Zeche. Researchers investigated using lighter, more easily transportable materials including concrete canvas, expanding polyurethane and polyurea foams, and brattice. The applicability and utility of these materials depends on a variety of factors including the ventilation air pressure, chemical resistance to acidic and mineral-laden mine waters, ease of transport, and ease of construction. Stoppings and seals must be substantially constructed so that they remain tight and do not require maintenance. It is also important to consider the toxicity of the construction materials in case of a mine fire."

Jan 1, 2016

By James Parkes

"The proposed Baltimore Red Line light rail system includes a 3.4 mile downtown tunnel (DTT) with five underground stations. The design of the underground stations involved overcoming several challenges, including limited right-of-way, high groundwater and uplift pressures, and metamorphic rock within the station depths. An innovative design was developed to maximize the internal station space while minimizing cost. The station designs use slurry walls for temporary and permanent support and groundwater control. Depths within rock are supported with cast-in-place concrete walls, the thickness of which are minimized through the use of permanent rock anchors for support of the rock mass and slurry wall toes. Permanent tiedown anchors are used for uplift resistance, which minimizes the station depths, volume of rock excavation, and the volume of deadweight concrete. Design considerations regarding individual elements and overall integration of the slurry walls, CIP walls, and multiple anchor types are presented.INTRODUCTION The Baltimore Red Line (BRL) project is a proposed light rail transit line for the Maryland Transit Administration (MTA) that runs east to west through Baltimore City and County. The project includes the Downtown Tunnel (DTT) consisting of 3.0 miles of twin running tunnels, two portals, five underground stations, and a pedestrian tunnel, as shown in Figure 1. The tunnels have an outside diameter of 21.8 feet and are designed to be mined using pressurized face tunnel boring machines (TBMs). The stations, portals, and the pedestrian tunnel are designed as cut-and-cover structures using slurry walls (concrete diaphragm walls) for both temporary support of excavation (SOE) and permanent structural walls. The dimensions of the five underground stations are summarized in Table 1. Design challenges included limited right-of-way (ROW), challenging soils conditions, strong metamorphic rock within the station depths, and high groundwater conditions. The final station designs included innovative use of slurry walls, tieback anchors, rock anchors, and tiedown anchors."

Jan 1, 2016

"Outotec’s TankCell® e500 flotation cell was commissioned during 2014 at the Kevitsa Mine in northern Finland. The TankCell® e500 is the first cell in this size class (500m3) to be run in an operational duty and it has been working as the first rougher in the copper flotation circuit. Treating around 850tph with an average grade of 0.3% Cu the TankCell® e500 has run with an average copper recovery of 71% and an average enrichment ratio of 50. In addition the cell has proved to be very energy efficient, operating with a specific energy of around 0.4kW/m3 under production conditions. This presentation will provide a review of the installation and operation of the TankCell® e500 at Kevitsa and will summarize the results found in the published literature from the various testing campaigns conducted around the cell. INTRODUCTION The TankCell e500 was installed and commissioned at the Kevitsa mine in northern Finland in 2014. Post startup the cell was initially run for testing and optimization with various test campaigns undertaken. but was subsequently taken into a production duty (Mattson et al., 2015a). At Kevitsa the cell is run as the first copper rougher replacing the previous two copper roughers (both 160m3) in this duty. The unit is running at between 38-40% solids at a feed rate of approximately 850tph. Since operational the average copper recovery from this single cell has been around 71% copper. This is typically with an enrichment ratio of around 50 being fed with an average head grade of 0.3% copper. More details on the circuit configuration and production performance of the e500 at Kevitsa can be found in Mattson et al., (2015a) and Murphy et al., (2016). In addition through the optimization program with the use of a variable speed drive controlling rotor speed it was found the the e500 was very energy efficient under production conditions. During this work the cell was found to run at a specific energy of around 0.4kW/m3 which exceeded design expectations (Xia et al., 2015)."

Jan 1, 2016

By Hiroyuki Tamaru, Futoshi Kusumoto, Kosuke Tanimura, Atsuyuki Kimura

"SUMMARY The Hachinoshiri tunnel is a 2,469 m long two-lane road tunnel on the Chubu-Odan Expressway. Since more than 70% of the total tunnel length consists of low strength rock masses the competence factor of which is less than 1.0, it is expected that a self standing span cannot be achievable because of no ground arch to be established. The tunnel was thus designed with tunnel support patterns forming multi-arc early ring closure that can develop the load-carrying capacity estimated from the exerted earth pressure, Po, which can result from the competence factor, cf. The tunnel support pattern was selected based on the competence factor at tunnel face, then the subsequent tunnel support patterns were determined with reference to the monitoring data. The tunnel construction adopted full-face excavation accompanied by early ring closure using a 330 kW road header. The proposed construction methods at this tunnel site have turned out ensuring tunnelling in massive squeezing rock, so that they can be verified as reasonable tunnelling technologies, clarifying the relationship between the characteristics of the mechanical behaviour of the tunnel and its design parameters. INTRODUCTION The presence of highly weathered mudstone having the competence factor less than 1.0 where the tunnel became unstable with the early ring closure having the distance to early ring closure, Lf, of 6 meters, resulting in difficulty in maintaining the inner section of the tunnel, prompted a substantial amount of high strength double support and replacing of the tunnel support (Sato et al., 2015). Based on the mechanical characteristics learned from the construction, the mechanical stability of multi-arc tunnels was investigated using 3D FDM analyses with respect to the ratio of the radius for early ring closure, r3/r1, and the distance to early ring closure, Lf, so that tunnel support patterns for early ring closure can be established in terms of the competence factor, of, which was employed for a 725 m long section. Consequently the tunnel support patterns for early ring closure which can be determined from the competence factor became applicable to tunnel construction. The relationship between the characteristics of the mechanical behaviour of the tunnel and its mechanical parameters was also clarified. The early ring closure method adopted ensured tunnelling in massive squeezing rock, verifying its effectiveness in stabilizing the tunnel."

Jan 1, 2016

By Rolf Christiansson, Daniel Johansson, Urban Åkeson, Henrik Ittner, Mats Olsson

"This paper presents two recent studies on the extent of blast damage after excavation in crystalline rock. The Swedish Transport Administration and the Swedish Nuclear Fuel and Waste Management Company (SKB) are both under regulations to limit excavation damage during construction of tunnels. SKB is also required to limit the Excavation Damage Zone (EDZ), as this could be a potential flow path for radionuclides in the planned repository for spent nuclear fuel. Presented in this paper are investigations of blast damage from three tunnel sites, a road tunnel, an experimental tunnel in Äspö Hard Rock Laboratory and an underground subway depot. As expected the fractures resulting from the bottom charge are both longer and more frequent then those mapped in the column charge. The results show that the requirement to limit blast damage according to Swedish regulations was fulfilled for the column charge at the three studied sites.1 INTRODUCTION The Swedish Transport Administration (TRV) and The Swedish Nuclear Fuel and Waste Management Company (SKB) have both recently completed studies related the extent of blast damage from modern explosives after excavation. SKB studies focused on blast damage from pumpable emulsion explosives for underground construction (Ittner and Bouvin 2015) and hydraulic connectivity in the EDZ (Ericsson et al. 2015). TRV had a broader focus with different types of explosives including blasting for both road cuts and tunnelling with pumpable emulsion explosives. Investigations by means of geophysics were also conducted (Olsson et al. 2015). High demands on perimeter control and excavation damage is usually required for underground constructions with a long operation time, such as public tunnels for transport or underground repositories for nuclear waste. This paper presents the findings of recent Swedish studies and aims to discuss the topic in a broader context."

Jan 1, 2016

By Faruk Oksuz, Cary Hirner, Ray Brainard

"Key project participants, including owners, engineers, and contractors continually seek for sound and structured decision analysis on how to select the best contracting method for successful project delivery. In addition to being burdened with technical challenges, lack of resources, budget shortcomings, regulatory requirements, and bureaucratic and politically mandated obstacles, the project participants need a reliable decision analysis model on the best project delivery method. The pendulum of choice for contracting continually swings back and forth between traditional design-bid-build and alternative delivery options such as design-build, progressive design-build, construction manager at risk, and public-private-partnership. For large tunnel projects, the decision process is further complicated due to contract packaging options as well as risks in underground construction. Contracting strategies for large tunnels require thorough consideration of performance, risk, quality, operability, cost and schedule. This paper compiles an array of decision making criteria and tools for an unbiased and balanced evaluation and ranking system in the procurement of large tunneling projects. INTRODUCTION Successful project delivery hinges upon meeting the owners’ expectations and key performance indicators. Large tunneling programs benefit from a thorough understanding and successful implementation of project delivery options by key project participants including the owners, engineers and contractors. The key to success is a collaborative advancement of project as the key project participants knowledgably address the applicable management, performance, risk, quality, cost, operability and schedule considerations throughout a project realization cycle. PROJECT REALIZATION CYCLE All projects have customary planning, design, construction, commissioning and operation phases that may seem to be sequential but in reality that are well integrated and dependent on one another. A glitch in any phase of a project realization cycle could hinder a successful outcome and none of the project partners are immune to consequences whenever and wherever they may surface."

Jan 1, 2016

By G. Bulut, Ü. Yenial

"The use of recycled water in flotation has significant effects on flotation and selectivity because the recycled water contains many dissolved compounds and ions that alter the chemistry of the system. In this study, the effects of calcium, magnesium and sulfate, which are abundant components in recycled water, were investigated on galena, sphalerite and pyrite flotation using pure minerals and a complex sulfide ore by conducting bench-scale flotation, microflotation and zeta potential measurements. The bench-scale flotation tests indicated that higher recoveries of galena and sphalerite are obtained when water is recycled, due to higher concentrations of ions in recycled water. However, there was a critical ion concentration for galena recovery. The microflotation tests showed that galena recoveries at different pHs in recycled water are lower than in tap and distilled water. Pure sphalerite recoveries improved in recycled water in the bench-scale test with ore. Pure pyrite was depressed with recycled water as well. Zeta potentials became less negative with increased calcium and magnesium ion concentrations due to their adsorptions, and the presence of sulfate ions was seen to increase the negative charges of sphalerite and pyrite, conversely for galena. IntroductionWater is among the most important elements for mining and mineral processing. The distance to water sources is one of the major factors for mine site selection. The mining and mineral processing sector needs and consumes large quantities of water. In Chile in 2014, the copper mining sector alone consumed 12.7 m3/s fresh water for 1.189 tons of ore processing, and recycled 74 percent of the consumed water (Chilean Copper Commission, 2015). A plant that does not reuse or recycle any water will require 1.9 to 3.0 m3 of water per ton of ore processed (Gunson et al., 2012). Many stages of mineral processing, such as grinding, gravity concentration, dense medium separation, wet magnetic separation, flotation and hydrometallurgical operations, use large volumes of water (Schumann, Levay and Ametov, 2009).In mineral processing plants, the process water is recycled from the tailings dams, thickener overflows, and dewatering and filtration units. Wet concentration processes can require large quantities of water. Flotation, the most common process, typically takes place at 25 to 35 percent solids by mass. Most flotation plants practice at least some water reuse and recycled. Modern mines and mineral processing operations generally aim for zero water release (Levay, Smart and Skinner, 2001). In most cases, water quality has been found to affect flotation performance, and this interaction remains under investigation."

Jan 1, 2016

By C. Vass, A. Noble

"The chemical treatment of mine-influenced waters is a longstanding environmental challenge for many coal operators, particularly in Central Appalachia. Mining conditions in this region present several unique obstacles to meeting NPDES effluent limits. Outlets are often located in remote areas with challenging terrain where conditions do not facilitate the implementation of large-scale commercial treatment systems. Furthermore, maintenance of these systems is often laborious, expensive, and time consuming. Many large mining complexes discharge water from numerous outlets, while using environmental technicians to assess the water quality and treatment regime multiple times per day. As an alternative solution, this paper describes the ongoing research and development of automated chemical treatment systems for mine water discharges. The current work explains the development of a bench-scale prototype that has been used to evaluate various monitoring, notification, and control strategies. Results from this testing are compared to present day practices to show the costs and benefits of implementing an automated treatment and monitoring program. INTRODUCTION Background The National Pollution Discharge Elimination System (NPDES), per Section 402 of the Clean Water Act, requires permitting of all point source discharges from coal mines. This program dictates that all water leaving a permitted boundary, whether it be process water or storm water, must leave through a monitored NPDES outlet. These permitted NPDES discharge points, also denoted outlets, outfalls or monitoring points, must meet a rigorous set of effluent limits to maintain compliance. Common effluent limits monitored by coal companies include but are not limited to iron, manganese, aluminum, total suspended solids (TSS), and pH. Raw mine water is often deficient in meeting these effluent limits, and as a result, various treatment processes are required to bring the water into compliance prior to environmental release. Depending on the mining and geologic conditions, water monitoring and treatment programs can constitute a significant operating cost for the mine operator. In Appalachia, acid mine drainage (AMD) constitutes one of the most significant and widespread water quality challenges that must be treated per NPDES guidelines. AMD is a general lowering of water pH that occurs when water and sulfide minerals interact within oxidizing conditions in coal and metal mining. Acid Rock Drainage (ARD) is a similar term that applies more generally to non-mining causes such as highway construction and other large-scale excavations. Today, mine influenced waters (MIW) is becoming more popular as the general term referring to all types of mining-induced water issues. AMD has been researched substantially over the last 30 years, with investigators studying various causal mechanisms and treatment strategies (e.g. Gazea, 1996; Ziemkiewicz, 1998; Skousen, 2000; Kleinmann, 2001; Johnson, 2003; Akcil, 2006; Kalin, 2006). This research has produced several pragmatic results, which provide numerous methods to predict, prevent, and treat AMD."

Jan 1, 2016

By Chris Ashton, Andreas Rädle, Taner Aydogmus

"The Contract C310 is part of the current biggest infrastructure project of Europe “Crossrail” which is a major new cross-London rail link project and comprises the construction of the North Woolwich Portal, Plumstead Portal and the twin tube Thames Tunnels with a length of approximately 2.6km. Two Mix-Shield TBMs (Diameter 7.12m) were driving through differing challenging ground conditions (Thanet Sand, Gravels, Flint and Chalk) below the ground water table. The two tunnels were underpassing several listed buildings, sensitive structures, operational railway tracks with low overburden and close to existing subway tunnels in an urban environment. Several additional measures as compensation grouting, micro piles and an intensive monitoring has been carried out to ensure a safe tunnelling process. PROJECT OVERVIEW CROSSRAIL Project Crossrail Crossrail is currently the biggest infrastructure project in Europe which has been developed to serve London and the southeast of England. The project includes the construction of twin-bore tunnels on a west-east alignment under central London and the upgrading of existing National Rail lines to the east and west of central London. The new rail track, as shown in Figure 1, starting in Shenfield/ Abbey Wood in the east of London and ending in Reading / Heathrow Airport in the west of London, includes the construction of nine central area stations, providing interchange with London Underground, National Rail and London Bus services, and the upgrading or renewal of existing stations outside central London.Altogether there will be 118km of new rail tracks, including 42km of tunnels and 40 train stations. After completion in 2018, Crossrail expects 200 million passengers per year (Tauriainen, Rädle, Ingram 2013)."

Jan 1, 2016