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By Pierre Gouvin, Michael Oakland

"This paper covers the rapid response methods used to monitor the emergency response to damage to an historic structure. An architectural gem, the latest incarnation of the old south Church was completed in 1875, utilizing local conglomerate (pudding stone), combined with brownstone and other materials to make an incredible showcase for priceless stained glass and other details epitomizing the height of the American Industrial Revolution. As part of required American with Disabilities retrofits to the adjacent Metropolitan Boston Transit Authority Station (MBTA), a support of excavation system was implemented with tradition sheet piles. During excavation (SOE) it was determined that Jet Grouting would need to supplement the sheeting to close openings in the SOE. During Jet Grouting, the eastern side of the structure was bisected, and lifted over 2 inches up and to the south. The movement occurred rapidly, within minutes, and subsided when Jet grouting was discontinued. The paper will describe the nature of the immediate response to get a real time monitoring program established, and the follow on monitoring program that ensued to provide the needed information to the stakeholders about this critical structure to evaluate stability, safety and to develop a long term remediation plan. The real time systems and instruments used consisted of Automated Motorized Total Stations (AMTS) and Automated Crackmeters. The Paper will describe the techniques used to control construction in safe manner.INTRODUCTIONThe Old South Church of Boston was constructed in 1875 and is one of the best examples of High Victorian Gothic Architecture in the Northeast. (Fig. 1) shows the newly constructed Old South in 1882. The Roxbury Conglomerate used to construct the church combined with large stained glass window by Clayton and Bell of London provides its unique appearance. Like most of the structures constructed in Boston’s Back Bay at that time, the church is founded on timber piles which penetrate the fill and organic soils to bear in the upper Boston Blue Clay. The churches interior includes high vaulted plaster ceilings and a 1920’s E. M. Skinner organ with exposed pipes as long as 32 ft. in length. The Church was added to the list of National Historic Landmarks in 1970 and is a featured Boston attraction."

Jan 1, 2017

By S. C. Tadolini, P. Mills

"INTRODUCTION This research produced a shotcrete formulation that extends beyond stabilization and can be used to restore the structural integrity of damaged infrastructure. The primary challenge was to develop a shotcrete or gunite with structural strength within a few minutes to prevent parasitic loading and allow ingress into damaged structures within a few minutes of the mix formulation being applied. This also applies to mining conditions where rapid support of progressive failures can minimize failure. An additional benefit was the discovery that the product had extremely high adhesion properties in addition to high flexural strengths. The approach to product design was the development of “single bag” dry mixes that are entirely self-contained, can be rapidly transported anywhere in the field or underground, and be deployed using simple equipment. Dry mix eliminates issues relevant to high shear water mixing, as water is added in the form of a mist at the point of delivery; thus low W/C can be achieved. However, as there is no onsite powder mixing, the product must have a high degree of inherent homogeneity. A commercial version of this material is currently offered as Minova’s Tekcrete Fast® product which has been successfully deployed in the mining industry and is currently being used in civil, construction and tunneling operations. The material can rapidly stabilize unstable ground in metal/nonmetal and coal mines. This paper described the technology development, product testing results and applications in mining and civil applications. BACKGROUND The original development of this product was to complete rapid stabilization of shock damaged structures, which falls outside the purview of normal construction and mining practices, due to the critical time issue and the nature of the damaged structure. The stabilization of damaged structures requires materials and equipment that can be rapidly deployed to place materials that have very rapid strength development. These materials need to be placeable at a distance to provide some degree of safety to the responders. In addition, the materials must be able to adhere to structural surfaces that have not been specially prepared and conditioned, and may also be highly fractured, dusty, wet, and quite possibly hot or extremely cold. The technology for the rapid delivery of large volumes of cementitious materials to vertical or even overhead surfaces currently exists. Pneumatic delivery (shotcreting) has been used in construction for over 100 years (American Shotcrete Association, 2014). Shotcreting has played a major role in structures like the Washington D.C. Metro subway system and been used in underground mining applications routinely to serve as part of the primary and secondary support system when used in conjunction with traditional roof bolts. Numerous rapid setting cements are commercially available. They are used for rapid repair of surfaces such as bridge decks, pavements, and commercial floors, as well as structural repairs of vertical and overhead surfaces. Few of these products are specifically marketed for use in shotcrete applications. The majority of rapid setting cements are based on, or at least contain, Portland cement as a principle component. Other components are added that help provide early strength, such as high alumina cement (HAC), organic polymers, chemical accelerators (which can also be added during concrete batching), and calcium sulfate hemihydrate (e.g. gypsum plaster) (Lea, 1971). Cementitious mortars prepared with some of these cements can achieve compressive strengths of 6.8 – 13.8 MPa (1,000-2,000 psi) within 1 hour. However, Portland cement mortar and concrete typically require many weeks of proper curing to reach significant levels of their ultimate strengths, even when used with set accelerators. Also, high early strengths require the use of large proportions of Portland cement in the concrete mix, which can lead to high heat evolutio"

Jan 1, 2017

By B. Aydin, A. S. Aloglu, S. Kahraman, E. Saygin

"The coal strength parameter is used in operations such as the selection and design of mechanical excavators and coal crushing/grinding equipment. However, coring or cutting prismatic specimens from coal for the standard strength tests is difficult, and sometimes not possible. For this reason a method for the indirect determination of coal strength from easy tests would be useful. In this study, the predictability of coal strength from the needle penetration test was investigated. This is a very easy and practical test method. Point load and needle penetration index (NPI) tests were carried out on coal specimens from Çayirhan coalfield in Turkey. The point load indexes were converted to the uniaxial compressive strength (UCS) values by using the general conversion factor. The UCS and NPI values were evaluated using regression analysis. A strong linear relationship was found between the two parameters. The conversion factor for the UCS-NPI ratio is 0.35 for the tested coal samples. It is concluded that the UCS of coal can be predicted from the NPI.IntroductionKnowledge of coal strength is important for the selection and design of mechanical excavators and coal crushing and grinding equipment. Uniaxial compressive strength of coal is used in designing pillar dimensions in room and pillar mining. Coals always contain bedding planes and cleats; they are also brittle and fragile. Therefore, coring or cutting prismatic specimens from coal for the standard strength tests is difficult, and sometimes not possible. For this reason, a method for the estimation of coal strength from easy tests would be useful.The needle penetration test is a nondestructive index test that is applicable both in the field and the laboratory and does not require any special sample preparation. The test has been used for the estimation of physical and mechanical properties of weak or soft rocks (Okada et al., 1985; Yamaguchi et al., 1997; Takahashi, Noto, and Yokokawa, 1988; Uchida et al., 2004; Aydan et al., 2006; Aydan, Watanabe, and Tokashiki, 2008; Aydan, 2012; Erguler and Ulusay, 2007; Park, Obara, and Kan, 2011; Ulusay and Erguler, 2012; Aydan and Ulusay, 2013; Aydan. Sato, and Yagi, 2014). This study investigates the predictability of coal strength from the needle penetration test."

Jan 1, 2017

By Türker Hüdaverdi, Özge Akyildiz

"Efficiency of blast operations depends on fragmentation, overbreak, muckpile profile anddisplacement, vibration, airblast, flyrock and damage to wall or slope stability. To provide all these conditions at the optimal level, determination of rock mass properties (in-situ block size, joint spacing and orientation) is the very first step during design stage of rock blasting. Image analysis software is used not only to determine the fragmentation level of muckpile but also to characterize the bench face. In this study, an image analysis software was used to determine apparent block size of bench face and to measure blast fragmentation of muckpile. The source of errors and the vital points to be taken into consideration were explained for bench face characterization andfragmentation measurement. Since it provides much better results than previous techniques and it is not intrusive to production process, image analysis technique is considered as one of the most efficient and preferred way for fragmentation analysis. Besides these advantages, there are some weak points of image analysis software. Lighting is one of the most important factors for photographs captured for in-situ block size analysis and fragmentation analysis. Lighting determines shadow formation. In an ideal image, particles are clearly delineated by soft shadows. If shadows are too strong (dark), analysis suffers. Appropriate scale should be replaced onto blast muckpile during site measurements. The location of the scale in image affects the results of analysis. Also, the densityand orientation of discontinuities should be considered during application of image analysis technique to characterize bench faces. In this study, image analysis software was applied in thesandstone, limestone quarries of Istanbul region and an open pit boron mine. All image analysis, evaluations and results were made based on the site measurements."

Jan 1, 2017

By K. Gardner

"Many deposits have a geological model developed early in the project stages, which is not always reviewed or modified as the project matures and production commences. Conversely, ongoing pressures, due to a combination of declining head grades, a push for increased revenue and a multitude of other reasons, leads to processing plant modifications, with the primary aim being to increase production. Often, the ore deposit knowledge is not sustained or developed during the operational stages to the level carried out during the prefeasibility and feasibility study phases. This results in the variability within the deposit being poorly understood and a lack of data and knowledge being available to support (and ideally optimise) operations particularly in an environment where the flow sheet has changed and ore feed requirements are complex.INTRODUCTION This paper presents a case study of ore deposit knowledge development and corresponding process plant operating strategy at the Ladolam Gold Deposit, commonly referred to as the Lihir gold deposit in Papua New Guinea. The gold deposit is located in a tropical equatorial climate on the east side of Lihir Island in the New Ireland Province of Papua New Guinea. Gold mineralisation was discovered in 1982, and was followed by a major exploration campaign by a joint venture between Kennecott (Rio Tinto) and Nuigini Mining Limited. The first drillhole was drilled in 1983, and after an extensive period of drilling consisting of 343 holes for 83,500 m, the final Feasibility Study was completed in 1992. The feasibility study was based on a Reserve base of 37.9 Moz in refractory sulphide ore, with gold extraction proposed to occur via whole ore pressure oxidation due to the refractory nature of the mineralisation. The Lihir Special Mining Lease (SML) was granted in 1995 to a new PNG company – Lihir Gold Limited, and Rio Tinto established Lihir Management Company to develop and operate the mine on behalf of LGL. Mining and processing of the deposit commenced in 1997. Newcrest Mining Limited purchased Lihir Gold Limited in August 2010, and subsequently completed a major plant upgrade including the installation of additional grinding, autoclave and carbon-in-leach capacity. Post commissioning of the upgrade, Newcrest has continued to increase throughput and production. A reinvigorated ore body knowledge development program has significantly assisted this process in identifying operating strategies for the process plant and delivering recovery improvement projects to address declining head grade and recovery due to increased stockpile feed and flotation circuit use."

Jan 1, 2017

By Shuo Zhang, Wenying Liu

"In dump leaching, the efficiency of metal extraction from ores is strongly influenced by the mechanisms of fluid flow. Particle size distribution acts as a fundamental parameter in the determination of fluid flow properties in packed ore beds. In this study, we investigated the particle size distribution in dump leaching by using image analysis technique. The results showed that the particles in the dump varied from smaller than 2 cm to larger than 200 cm in diameter. P80 was calculated to be 200 cm, which was significantly higher than the historical data used by the operation. P25, P50 and P80 were found to increase non-linearly with increasing depth towards the toe of the dump, suggesting the segregation of fine and coarse particles. The image analysis results were verified by applying the rock fragmentation models. The model with the Swebrec function was found to be in better agreement with the image analysis results. Future research will investigate the effect of particle size distribution on the behaviour of fluid flow.INTRODUCTION Fluid flow plays an essential role in the extraction of valuable metals using heap/dump leaching (Amos et al., 2009). The rates of the chemical leaching reactions and microbial activities determine metal concentrations in the leachates and therefore the efficiency of the metal extraction. The reaction rates are influenced by two fundamental processes: transport phenomenon and reaction kinetics (Bouffard & Dixon, 2001). The transport phenomenon refers to the percolation of fluids through channels and pores in a packed ore bed, which carries lixiviants and reaction products to/from ore surfaces by convection and diffusion. The percolation rate of the leaching solution is determined by the hydraulic conductivity of the packed ore bed, which is a function of the permeability and the degree of saturation (Guzman et al., 2008). Permeability, an intrinsic property of a packed ore bed, is strongly influenced by the particle size distribution of the ore grains (Bouffard & Dixon, 2001). Hence, the objective of this study was to investigate the particle size distribution in dump leaching."

Jan 1, 2017

By R. Yost

"This paper describes a case study that illustrates how detailed geological engineering results were communicated to address a range of stability challenges in a producing mining environment. Instead of using standard geological engineering terminology, findings and recommendations were communicated as mine design options and mining responses to accommodate possible slope instabilities and associated risk. The resulting medium- to long-range mine plan integrated the potential slope instabilities and associated mining responses to provide a higher probability of planned resource extraction. It also reduced the potential for long-lasting production and processing delays.RÉSUMÉ Cet article décrit une étude de cas illustrant l’intérêt de la communication de résultats détaillés de géologie appliquée pour résoudre un éventail de difficultés relatives à la stabilité dans un environnement minier en production. Plutôt que d’utiliser une terminologie classique de géologie appliquée, les résultats et les recommandations ont été communiqués sous forme d’options pour la conception d’une mine et de réponses dans le contexte minier permettant de surmonter les éventuelles instabilités des pentes et les risques associés. Le plan de mine sur le moyen à long terme qui a résulté intégrait les instabilités potentielles des pentes ainsi que les réponses connexes dans le contexte minier afin de renforcer la probabilité de l’extraction des ressources prévue. Il réduisait également la possibilité de retards durables dans la production et le traitement.INTRODUCTIONSlope failures in an active mining operation are unscheduled but expected events, in the sense that the geotechnical design often assumes the potential for slope failure but cannot predict exactly when a failure will occur. Unfortunately, the geotechnical engineering cycle—characterization, slope design, displacement monitoring, instability management, and failure remediation—that is necessary to manage slope-failure risk is not always well known or understood outside the geotechnical engineering profession. The first introduction many personnel have to geotechnical engineering is when a slope failure starts to develop and appears to threaten the safety and livelihood of their workplace.At that point, the task of communicating the risk management of slope failure falls to the geotechnical engineer, who must summarize analytical methodology, design concepts, monitoring trends, and analysis results, frequently to an audience with limited exposure to the geotechnical field. All too often, the response has been to present a risk-management plan in the vernacular of geological engineering— using terms such as factor of safety (FOS), pore-pressure reduction, and slope unloading—instead of expressing the problem and solution in more readily understood mine production terms."

Jan 1, 2017

By A. G. Doll

"Many power-based grinding models exist, and most operators are familiar with Fred Bond's ""third theory"". Bond's model is most commonly used to describe primary and secondary grinding to product sizes above, for example, 100 µm. Operators sometimes use Bond's equation to describe grinding in situations where it is not appropriate, such as fine grinding below 50 µm. Using an alternative model would be a better choice in this situation.Bond's equation is one in a large family of models. Related equations better suited to fine grinding include the “signature plot”, Von Rittinger's model and Charles' equation. These models have a similar form to Bond's and can be fit to industrial regrind mills and laboratory tests using the simple regression tools in the charts of computer spreadsheets. Operators will find that fine grinding calculations are both easier and more accurate when using the alternative equations to fit their regrind milling surveys or when performing laboratory regrind mill scale-up for plant design.None of these models are new: Charles' equation was published in 1957 and Von Rittinger's model was proposed in 1867. A quick refresh how to apply these equations can turn these oddities from the undergraduate curriculum into useful tools for plant optimization. They can be fit to any type of mill including stirred and tumbling ball mills.IntroductionBuilding a case for fine grind modelling requires reviewing some theory before building a framework for doing fine grinding calculations. The actual calculation procedure recommended is easy and can be applied by plant metallurgists. Don’t be frightened by the theory; the end result is reasonably simple.The observation that mineral breakage is related to the absorption of energy is usually attributed to Von Rittinger (1867). Lynch and Rowland (2005) describe that the ability to empirical test and calibrate energy models of breakage didn’t exist until the widespread adoption of electric motors in the mining industry during the 1930’s and 1949’s. A series of technical papers published by the Allis Chalmers company during the 1940’s demonstrate that they were attempting to do such a calibration using Von Rittinger’s model which is usually stated as: “the energy consumed in the size reduction is proportional to the area of new surface produced.”"

Jan 1, 2017

By Krishna Parameswaran

"This paper discusses energy use and conservation in the primary copper industry and illustrates eco-efficiency considerations, using select examples of practices at ASARCO LLC, an integrated primary copper producer and others in the industry that promote eco-efficiency. The World Council for Sustainable Business Development first publicized the concept of eco-efficiency at the Rio Earth Summit in 1992. Eco-efficiency is a management concept linking environmental and economic performance and is aimed at generating added value for a business through, among other things, increased resource and energy conservation and reduced environmental impacts throughout the life cycle of the product or service. This concept differs from sustainable development in that focus is only on economic and environmental factors and does not include social considerations. In the metal mining and processing context, this added value can be realized by implementing practices that promote conservation of water and mineral resources, conservation of energy, minimization of waste, reduced emissions and effluents and increased recycling. The examples from the primary copper industry used to illustrate eco-efficiency considerations include: water and energy conservation in mineral processing, adoption of flash and bath smelting processes, emission reduction and process improvement associated with fire-refining, implementation of green chemistry in electrorefining, promoting product stewardship initiatives and fostering renewable energy project on disturbed mined lands.INTRODUCTION ASARCO LLC (Asarco) was organized in 1899 as the American Smelting And Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co-products. Grupo México, S.A.B. de C.V acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, molybdenum, selenium and tellurium. Asarco operates three open-pit mines and mills, two leach, solvent extraction-electrowinning (SX-EW) plants and a copper smelter in Arizona and a copper refinery in Texas."

Jan 1, 2017

By M. Kawata, T. Amano, T. Miyamoto, K. Shibayama

"The High Pressure Acid Leach (HPAL) plant of Taganito HPAL Nickel Corporation (THPAL), located in Taganito, Philippines, with a nameplate capacity of 30,000 Ni-t/year started commercial operation on October 2013. The plant load was smoothly ramped up and it achieved monthly production equivalent to 33,000 Ni-t/year in 2016. Partial improvement of the plant capacity for the achievement of 36,000 Ni-t/year, as evaluated from the current operation progress of each system is planned for 2017. In this paper, aside from presenting the progress of the plant ramp-up, research and development activities such as the reduction of nickel loss and the improvement of filtration capacity which was achieved by particle size control of ZnS precipitates in the Zinc Removal system are also discussed.INTRODUCTION Taganito HPAL Plant Project History of THPAL Taganito HPAL Nickel Corporation (THPAL) was incorporated in August 2008, as a joint venture of three (3) companies, namely Mitsui Corporation with 15% share, Nickel Asia Corporation (NAC) with 10% share and Sumitomo Metal Mining Corporation (SMM) with a controlling stake of 75%. Aside from its capital share, NAC’s Taganito Mining Corporation (TMC) supplies the ore for the HPAL plant located in Taganito, Claver, Mindanao, Philippines. The objective of THPAL is to produce 30,000 MT of nickel and 2,600 MT of cobalt as mixed (Ni/Co) sulfide by treating nickel laterite ore in the Philippines and exporting to Japan as raw material for SMM’s Niihama Nickel Refinery (NNR) for the next 30 years. In other words, 1.15 wt% of nickel in ore is refined to 99.99 wt% nickel in electrolytic nickel. The mixed (Ni/Co) sulfide is shipped to NNR and SMM provides the technology and management personnel to THPAL plant as well as sulfuric acid which is the main reagent for HPAL process. Figure 1 shows the location of THPAL and current relationship between the stake holders.The Characteristics of THPAL Plant In terms of plant design, a 2-train system is applied for the HPAL circuit considering the reliability of the process, facility and avoidance of whole plant shutdown due to HPAL troubles. The technical data, operation know-how and improvements gained from the successful operation of Coral Bay Nickel Corporation (CBNC) which was established in April 2002 were reflected in THPAL’s plant design. As for the H2S plant, a more economical design was considered which is different from CBNC."

Jan 1, 2017

"The successful commissioning and ramp up of the Albion Process™ at the GPM Gold Project relied on the successful scaling up of the process from batch and continuous pilot plant campaigns (Voigt et al., 2015). Critical information about reaction kinetics and residence time, grind size and pulp density were determined at the laboratory scale and successfully applied to the commercial scale. A limitation of small scale testwork, is that some parameters cannot be measured reliably and scaling up is a function of the physical size of the equipment which isn’t possible to test with laboratory scale equipment. Oxygen mass transfer rate is one such parameter since this is a complex interaction of many factors including slurry temperature, solution and slurry chemistry, slurry viscosity, agitator type, dimensions and power, oxygen bubble residence time, oxygen purity, tank geometry and oxygen injection technique. Oxygen generation represents an important operating cost for the Albion Process™. Pivotal to the Albion Process™ operating economically at atmospheric pressure is the capability to efficiently transfer oxygen while utilising as much oxygen injected to the process as possible. To respond to this Glencore Technology developed the HyperSpargeTM supersonic gas injector. This paper compares the HyperSparge™ against other sparging techniques to quantify the benefits of oxygen injection via a supersonic gas jet on scale up of the oxygen mass transfer system. The paper then examines plant survey data from the GPM Gold Project to demonstrate the very high oxygen utilisation that can be achieved with a correctly designed oxygen mass transfer system.INTRODUCTION One of the main challenges in chemical reactor design is the scale-up of processes from the laboratory to industrial scale. Processes which cannot be faithfully simulated with an experiment at the laboratory scale face challenges due to the physical dimensions and complexity of full scale operation. One example of this is the design of oxygen mass transfer systems in atmospheric oxidative leaching circuits such as the Albion Process™. A number of constraints associated with the use of laboratory scale equipment to design full scale circuits are involved in gas mass transfer processes in agitated slurries such as the Albion Process. Chiefly, typical laboratory and pilot size equipment lacks the required volume to provide useful design data without relying on empirical correlations: the specific agitator power input is artificially high, the bubble residence time in the vessel is artificially low, the oxygen partial pressure at the base of the vessel is artificially low and the oxygen delivery method may differ significantly to the industrial process. Further, the dynamic nature of the process introduces additional impacts on gas mass transfer, including the presence of solids, recycle streams and minor elements, plus the variances within the reality of a process plant such as disruptions or variance of feed quality."

Jan 1, 2017

By A. J. Monhemius

"This paper reviews the history of modern iron-control processes in hydrometallurgy. Attention is paid to processes developed in the electrolytic zinc industry for removal of iron from zinc sulfate leach liquors and the problems faced by the industry in the safe disposal of the iron residues produced by these processes. Past lessons learned are projected onto current efforts to develop hydrometallurgical processes for treatment of copper sulfide concentrates. It is argued that any attempt to create a “hydrometallurgical copper smelter” will fail, unless methods are developed that can recover iron in a form that can be directly used by the steel or pigment industries.RÉSUMÉ Cet article passe en revue l’histoire des procédés modernes de contrôle du fer en hydrométallurgie. Il accordera une attention particulière aux procédés développés dans l’industrie du zinc électrolytique pour l’élimination du fer dans les liqueurs lixiviantes de sulfate de zinc anhydre, ainsi qu’aux problèmes rencontrés par l’industrie en termes d’élimination sans danger des résidus ferreux générés par ces procédés. En projetant les leçons tirées du passé sur les efforts actuels, on pourra développer des procédés hydrométallurgiques pour le traitement de concentrés de sulfure de cuivre. Beaucoup prétendent que toute tentative de créer une « fonderie de cuivre hydrométallurgique » échouera à moins de développer des méthodes permettant de récupérer le fer sous une forme pouvant directement être utilisée par les industries sidérurgique ou des pigmentsINTRODUCTIONThis paper resulted from an invitation to the author from the CIM’s Historical Metallurgy Committee to give a presentation on the early developments of iron control in hydrometallurgy. This was to take the form of a plenary lecture at the 4th Symposium on Iron Control in Hydrometallurgy, which formed part of the 28th International Mineral Processing Congress, held in Quebec City in September 2016.I was naturally flattered that the invitation was to give the lecture at an IMPC, the prestigious conference series that has been held since the 1950s. That this particular IMPC was to include the 4th Symposium on Iron Control in Hydrometallurgy, a conference series held only every 10 years, made the invitation even more appealing and appropriate. This was because I had been co-chairman of the First Symposium on Iron Control, together with my erstwhile colleague, John Dutrizac, which was held 30 years ago in Toronto."

Jan 1, 2017

By Z. Jin, D. DePaoli, P. Zhang

"Phosphorite, or phosphate rock, is the most significant secondary rare-earth resource. It contains high amounts of phosphate-bearing minerals along with low contents of rare earth elements (REEs). In Florida, about 19 Mt of phosphate rock are mined annually and most are used to manufacture fertilizers using a wet process, in which sulfuric acid reacts with phosphates to produce phosphoric acid and phosphogypsum. In the wet process, REEs are also leached out into solution and eventually get lost in the leaching residue and phosphate fertilizer. Recovering REEs from Florida phosphate rock in the wet process will be beneficial to broadening rare-earth availability, improving the quality of phosphoric acid product and protecting the environment.This study focuses on the influences of wet-process operating conditions on REE leaching efficiency. The results indicate that REE leaching efficiency increases with phosphoric acid addition in the initial pulp. At a temperature of 75 °C, a stoichiometric ratio of sulfuric acid (H2 SO4 ) to calcium oxide (CaO) of 1.05 and a weight ratio of liquid to solid of 3.5, REE leaching efficiency reached a relatively high value of 52.82 percent. The trends of REE leaching efficiency were similar to those for phosphoric acid (P2O5 ). Extensive tests on the leaching residue showed that during leaching, about 90 percent of the REEs were released from the phosphate rock but only 52.82 percent ended up in the leaching solution. This phenomenon can be attributed to two factors: (1) the effect of phosphate ions (PO4 3-) in the solution, which caused REE ions to form REE phosphates and be precipitated into the leaching residue, and (2) the influence of large amounts of anions such as sulfate (SO4 2-), dihydrogen phosphate (H2 PO4 -) and hydrogen phosphate (HPO4 2-) anions as well as the polar molecule H3 PO4 , which surrounded the REE cations and formed an ion atmosphere that prevented the PO4 3- from contacting and combining with REE cations. Interaction of these two opposite effects determined the REE distribution between leaching solution and residue."

Jan 1, 2017

"The Metropolitan St. Louis Sewer District (MSD) in Missouri, the country’s fourth largest sewer system, is upgrading its storm and wastewater infrastructure in a 23-yearlong, $4.7 billion initiative called “Project Clear.” Historically, during times of intense precipitation, the current sewer system becomes overwhelmed. The primary goals of this project are to improve water quality and to alleviate many wastewater concerns in the St. Louis region by planning, designing and building community rainscaping, system improvements and an ambitious program of maintenance and repair.Part of the system renovation has focused on constructing underground tunnels for storm water storage, permitting controlled drainage of runoff, and preventing overflows into rivers and streams. Construction plans for these storage tunnels called for eight vertical intake and ventilation shafts to be bored from the ground surface. These shafts will then be intercepted in the bedrock at a depth of about 150 ft (45.7 m) during the excavation of the 3,000 ft (915 m) long underground tunnel that will be about 28 ft (8.5 m) in diameter. According to John Deeken , a geotechnical engineer with Black & Veatch Corp. and construction manager for the Maline Creek project, the drilling and blasting technique for creating the shafts was ruled out because the project was located in a residential neighborhood. “We could have used rock coring or a cutter head, but the drop shaft for this project is constructed within 10 ft (3.05 m) of an existing 108 in (274 cm) diameter sewer main,” Deeken said. “We had to take precautions to avoid damage to it.”A primary planning mandate of all MSD Project Clear phases requires minimized impact on traffic and residents. The canister drilling method enabled work to be confined to the median of a residential boulevard running perpendicular to the side street without detouring traffic. In addition, canister drilling offered a highly-precise means to create the shafts, leaving a smooth-sided borehole, right on target. Ground conditions in this 132 in (3.35 m) diameter intake shaft were wet due to the high groundwater levels and close proximity to the Mississippi River. “They’ve been finding shale in 2 to 6 ft (0.6 to 1.8 m) layers between weathered layers of Mississippian limestone,” said Dan Spiecher, technician at Center Rock (CRI). “The 2 ft (0.6 m) layers we can punch through. The 6 ft (1.8 m) layers slow us down.”"

Jan 1, 2017

By Marc Raithel, Sven Schröer, Lilma Schimmel, Dimiter Alexiew

"The Geotextile Encased Columns (GEC) deep foundation system for embankments and dikes on soft soils was introduced some 20 years ago and is now considered State-of-the-art in Germany, Europe and, step by step, worldwide. The GECs consist of compacted non-cohesive granular fill similar e.g. to common gravel columns with one decisive difference: they are confined in a high-strength, high-modulus, flexible geotextile “cylinder” (encasement). This engineered element with parameters being adaptable in a wide range provides a decisive tool to control and optimize the behavior of the GEC foundation system. Consequently, the GECs work properly even in extremely soft soils, and a wide range of fills inclusive of sands can be used. In the meantime vast design and technological experience is available and codified design methods exist. Initially the paper briefly describes the general idea, the basics and specifics of design, construction technology, materials, restrictions and optimal application areas. Then it focuses on three informative case studies. They are briefly presented focusing for brevity only on the most important facts and experience inclusive of the most meaningful data of short- and long-term measurement programs.INTRODUCTIONWhen considering embankments on soft soils, generally two groups of solutions exist:Unsupported embankments; there are four main options:a) build up embankment extremely slowly waiting for sufficient consolidation after every stage;b) replace the soft soil partially or totally;c) install a high-strength basal reinforcement providing overall and local stability and allowing much faster embankment construction;d) combine c) with strip drains to accelerate consolidation and thus the construction process additionally (Fig. 1, left).Today, practically only option ""d"" is of practical relevance. Despite all the pros and cons, the common attribute of all non-supported options is that local and overall stability (Ultimate Limit State-ULS) can be achieved and controlled, but not the short- and long-term settlements (Serviceability Limit State-SLS). The latter can be significant, e.g. up to 30% of the nominal planned embankment height. Supported embankments (Fig. 1, right): the main common idea is to over-bridge the soft soil layers by supporting vertical elements of different types: rigid piles, trench walls etc. or by ""softer"" solutions of different column types (compacted, cemented, mixed-in-place etc.). Herein the borderlines between “piles”, ""pile-similar elements"" and ""soil improvement” are fluent and depend on country, traditions, codes etc. The common attribute of the “supported” schemes is a minimized settlement. Twenty years ago a new specific solution was launched: the Geotextile Encased Columns (GEC), which is discussed in more detail below."

Jan 1, 2017

By Ian Ewart, Trevor Bergfeldt, Gourab Satapathy, Ajay Patel

"Conventional electrowinning (EW) of nickel from sulfate electrolytes is complicated by several factors including the requirement for a diaphragm cell to separate the anolyte and catholyte and the need to minimize nickel mist emissions. Developed and commercialized by emewCorporation, this novel process electrowins high purity nickel cathode (99.5%) from copper refinery bleed streams using the proprietary emew vortex EW technology. The emew nickel process incorporates high flow rate in an enclosed cylindrical EW cell operating at high current densities that overcomes the challenges of conventional nickel EW and completely eliminates the risk of nickel mist emissions. The tubular cathodes are easily harvested and mitigate the effect of plating stresses inherent in nickel EW. The present paper describes the emew nickel process and its most recent application to copper refinery bleed streams at full-scale.INTRODUCTION To meet the stringent demand of customers, nickel producers are giving prime importance to production of high purity nickel cathodes. The major challenge for refineries is to improve cathode quality and appearance despite fluctuating electrolyte impurity levels. The basis of achieving good quality cathode includes the control of electrolyte impurities and consistency of specific process conditions. The commercial operation of emew nickel technology has been successfully implemented and has demonstrated the ability to produce high quality nickel cathode from refinery bleeds. This paper emphasizes the importance of upstream impurity removal to achieve the required nickel emew feed composition by evaluating the benefits of using selective precipitation as a purification scheme with the aim of improving the overall nickel recovery while ensuring suitable nickel concentration in the advanced electrolyte is achieved. Nickel electrowinning is similar to other electrowinning processes that employ insoluble metal anodes & cathodes. It requires the passage of direct current between two electrodes that are immersed in a conductive, aqueous solution of nickel salts. For the recovery of nickel from solution, the most common methods are electrowinning and hydrogen reduction. Electrowinning usually occurs from sulfate, chloride or mixed sulfate/chloride electrolytes. In sulfate electrolytes, nickel electrowinning cells are normally designed to achieve specific criteria as outlined below (Robinson & Tuppa, 2002):"

Jan 1, 2017

By Nathan W. Iverson, David S. Graham, Paul J. Axtell

"The Highway 53 relocation project in Virginia, Minnesota, involves construction of a very tall bridge across a currently inactive iron ore mine pit. The inactive pit is partially flooded and serves as the community’s drinking water source. The 1,132-ft long new bridge is a three-span, plate girder structure. Two intermediate, approximately 200-ft tall piers are located within the pit.The foundations for the two piers consist of groups of 30-in diameter piles which, despite the contradiction in terms, are essentially very large micropiles. Extremely challenging and highly variable subsurface conditions exist at the site, ranging from uncontrolled iron ore mine waste fill to some of the hardest rock on earth that can also be highly fractured and abrasive. Despite the conditions, large diameter (30-in) micropile foundations up to 175 ft deep were successfully installed using down-the-hole hammer methods and full-length permanent casing under an extremely aggressive construction schedule.Full-scale foundation load testing using the Statnamic rapid loading method was also conducted in support of the design and construction but under a separate pre-design phase contract. This paper describes the unique aspects of this foundation project, including design, construction, and load testing of the large micropiles.INTRODUCTION AND BACKGROUNDIn 1960, a segment of Trunk Highway 53 (TH-53) in Virginia, Minnesota, was built on land owned by iron ore mining interests. As part of the roadway easement agreement, Minnesota Department of Transportation (MnDOT) was to be given notice three years prior to termination of the easement. In 2010, MnDOT received notice that the mining interests wished to access the ore. Through negotiations in 2010, MnDOT and the mining interests agreed to a 2017 date for abandoning the existing section of roadway. During this period, MnDOT needed to procure project funding, satisfy environmental permitting requirements, and acquire new right-of-way to permanently reroute TH-53 and keep it open to traffic. This was no easy task due to the existing mine pits surrounding the area.The E-2 alignment option shown in Fig. 1 was ultimately selected for the rerouted highway in 2014. The new highway segment includes a three-span bridge across the currently inactive Rouchleau Mine Pit. The inactive pit is partially flooded and serves as Virginia’s drinking water source. The 1,132- ft long new bridge is a three-span, plate girder bridge. Two intermediate approximately 200-ft tall piers are located within the pit. Fig. 2 is a conceptual rendering of the bridge."

Jan 1, 2017

By Dzianis Proshchanka, Yoshi Izumi, Koji Mitani, Ayuna Kitaura

"A new pile driving and drilling navigation system has been developed. It utilizes the commonly used surveying total station, combined with an innovative reticle. Conventional crosshairs have been replaced by a concentrically circular reticle called Baum. It allows for easily performed measurements of central axes of cylindrical objects such as piles, chimneys, electricity poles, etc. This provides several significant advantages compared to other existing systems. It is cost-effective as only one operator is required to control deviations in positioning and inclination. Furthermore, repetitive reinstallation of the instrument is not required for every pile driven or hole drilled. It is also a safer method, as workers have no need to be near a pile driver or drilling machine to perform the measurements. With Baum Station, necessary measurements can be performed away from the actual work area. Moreover, it is highly accurate with real-time solutions, as three-dimensional orientation information for the pile/drill is obtained simultaneously with the pile being driven or the hole being drilled. This allows for the highest levels of precision-control and correction to minimize eccentricity of the intended center positioning.INTRODUCTIONBackgroundIn foundation construction for structures, pile foundations are widely used for deep bearing strata. There are two patterns to driving piles: vertically or obliquely to the ground. The shapes of the piles are normally cylindrical. Vertical pile foundations are employed as the foundations of many structures due to their high workability. There is a problem however, which is that this method does not bear measurement data as construction accuracy is visually checked. On the other hand, tilted pile foundations are rarely employed because it is too difficult to ensure construction accuracy. In addition, commonly used percussion methods create noise and vibrations when the piles are hit, while there are advantages that thinner piles are available, ensuring earthquake-resistance, as tilted piles curb horizontal displacements of structures, which may be caused by earthquake ground motion. However, current requirements of cost reduction bring professional attention to tilted pile foundations, which can be driven reasonably and economically with much research of tilted piles having been carried out to improve their capacity. Also, a method of screwing piling has been developed, which produces small amounts of noise and vibrations. This method has solved tasks of workability and environmental burdens, and is becoming more and more common. However, there is a necessity to develop a method to accurately measure angles of piles’ axes in order to drive piles into the ground with appropriate angles. It is also expected to find out a way to control construction information, such as correction amount and driving record."

Jan 1, 2017

By Federico Pagliacci

Continuous Flight Auger (CFA) technique represents an important technological advance in the construction of piles in soft soils. The possibility of excavation under the water table with no need for drilling fluids, along with high productivity, have resulted in this technique’s becoming widespread in many countries. However, CFA technology has limitations because of its difficulty in penetrating hard layers and cross strata with cobbles and boulders. In these situations, pile verticality may be an additional problem. The Cased Augered Pile (CAP) technique consists of penetrating the soil with an auger housed in a casing. Two independent rotary heads sliding along the rig mast operate the auger and the casing. By adjusting the height of the casing shoe and auger bit according to soil type, it is possible to drill piles in very severe conditions - in the presence of cobbles and boulders - and to socket the pile into the rock. The use of a steel casing enables improved pile verticality. Therefore, the CAP technique is also used to construct secant piles to be used as diaphragm walls. The limitations of this technology are the depth, usually no more than 27 m (88 feet), and the size of the rig that supports the drilling tool, no less than 70 t (77 short tons) in working conditions. This paper illustrates CAP technology, the drilling system, and the characteristics of concrete and steel reinforcement and offers a case study of the Palermo-Carini second railway line, which used CAP to construct the new 30 km (18.6 mi) railway line, 20 km (12.4 mi) of which passes through the very congested downtown area of Palermo. More than 300,000 m (186.4 mi) of piles have been drilled in dense calcarenite formations with unconfined compressive strength of 15-25 MPa (2,200-3,600 lb/inch2), soft clay,

Jan 1, 2017

By Maurizio Siepi, Paul van Horn, John Coupland, Julian Crawley

"TTMJ is the acronym for the Slurry (Diaphragm) Wall Tension Track Milled Joint currently in development as part of the European Union's innovative and far-reaching Horizon 2020 initiative (FTI Pilot-2015-1 720579). The TTMJ Project has been specifically set up to deliver this versatile new step-forward in Slurry Wall technology. The TTMJ System is protected by patent in Europe and the USA, and is currently under development by a consortium comprising Trevi SpA (Italy), Arup (Netherlands) and CCMJ Systems (UK). The principles of the TTMJ System together with the installation process are herein described in general terms. The system is still under development with field trials scheduled for early 2018, so some of the detail will not be disclosed at this stage. It is the intention of the Authors that the results of these field trials and a more complete description of the System will be presented in a paper we intend to submit for the DFI/EFFC International Conference on Deep Foundations and Ground Improvement to be held in Rome, Italy in June 2018. The final section of this paper explains how the TTMJ system can be applied to a common application of slurry wall construction; deep circular or multi-cell shafts. The system can be used to construct shafts more easily and at less cost than current methods. It also allows shafts with smaller internal dimensions to be constructed than is currently practical.INTRODUCTIONCCMJ Systems (UK) realised that an innovative new approach to forming joints in both Slurry (Diaphragm) Walls and Secant Pile Walls would provide greatly improved joint integrity to greater depths, to the overallbenefit of retaining wall quality, across the world-wide foundations industry.In particular this new system is designed to:??Increase the effective depth range of Slurry Walls (especially walls excavated by grab) and Secant Walls??Remove the requirement for Stop-ends or Joint Formers??Allow for a Shear Key at the joint??Allow for a Water Stop to be installed at the joint??Permit Continuous Reinforcement across the joint??Optimise Reinforcement Density and hence Concrete Flow??Facilitate joints in corner panels eliminating the need for “L” shaped cages and reducing largesingle-pour concrete volumes and slurry storage capacity requirements.??Enable the construction of smaller-dimensioned square and circular deep shafts (especially useful for city-centre sites) than is possible with current methods.CCMJ Systems approached other industry specialists with a view to forming a development team to explore the possibilities for this new technique."

Jan 1, 2017