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By S. Carsten, S. Subramanian, R. Vasant Kumar, S. Vimalnath

"The effect of EPS components namely protein, polysaccharide and biosurfactant purified from Pseudomonas fluorescens was investigated for the bioremediation of Pb(II) ions in aqueous solution. Two parameters, namely the amount of EPS component and the concentration of Pb(II) ions were optimized for maximum Pb(II) ions uptake. The EPS components interacted with Pb(II) ions were characterized using energy dispersive X-ray analysis (EDAX) to ascertain the presence of Pb and by attenuated total reflection-Fourier transform infrared spectroscopy (ATR–FTIR) to reveal the functional groups involved in Pb(II) binding. The maximum Pb(II) binding capacities of protein, polysaccharide and biosurfactant were found to be 11.4, 0.55 and 0.11 mg mg-1 respectively. The biosorption processes followed the Langmuir model. The Gibbs free energy (?G0) values of -23.6, -20.9 and -23.2 kJ mol-1 for Pb(II) biosorption by protein, polysaccharide and biosurfactant respectively, attested to spontaneous, chemisorption processes. The ATR–FTIR results revealed the presence and involvement of amino, hydroxyl, carboxyl, phosphate, and methyl functional groups in Pb(II) binding and EDAX analysis confirmed the interaction of Pb with EPS components. The Pb(II) binding mechanisms of EPS have been discussed. The results demonstrate the potential of the purified EPS components of P. fluorescens for removal of Pb(II) ions from aqueous solution INTRODUCTION Waste water containing toxic metals from various industries pose a serious threat to human health and ecosystem. For treating such waste water, conventional methods like chemical precipitation, coagulation, evaporative recovery, electrodialysis, floatation, flocculation, ion exchange, reverse osmosis, nanofiltration, ultrafiltration are used (Lakherwal et al., 2014). These methods have some disadvantages like toxic sludge generation, incomplete metal removal and high cost (Singh and Gadi, 2012), necessitating the search for cheaper and efficient alternative methods. Bioremediation is one of the emerging alternatives where bacteria, fungi, yeast, algae and other biological substances are used as sorbents to remove toxic heavy metals (Vijayaraghavan, et al., 2015). Recently, the bioremediation potential of extracellular polymeric substances (EPS) of microbial origin has attracted attention. However, for Pb(II) removal, there is a paucity of literature focusing on EPS."

Jan 1, 2018

By J. Seifert, L. Hunter, P. W. Conrad, S. Rosenthal

"The goal of the protocol for reclaiming in-pit tailings ponds to exceed federal and state regulations was to develop a series of steps that can be followed to design, operate, and reclaim a tailings disposal pond that will develop into grazing land with a wetland for open pit sand mines in warm dry climates. By incorporating a wetland into the reclamation design, the post mining land use gives back to both the wildlife as a source of water as well as providing for a diverse range of post mining land use including but not limited to livestock grazing and ranch land use. An example design was completed using this protocol to demonstrate how the protocol can result in in a well-designed, reclaimed tailings disposal pond. BACKGROUND In an industry plagued with decaying historic mine sites, the public’s perception of mining appears to be poor. While modern mines are closely monitored and generally managed by ethical professionals, history still influences how the public perceives the mining industry. From collapsing abandoned underground workings to historic tailings dam failures, the failure to account for the environment in the past seems to affect public perspective on mining today. In a 2013 “Opinion Former Survey,” a survey conducted through interviews with a diverse range of stakeholders in various gold companies, it was noted that the most serious challenges facing the mining industry were environmental concerns and the permitting challenges associated with them (Council). In another article, this time focusing on Australian citizens and their perspectives of the mining industry, it was found that the majority of those surveyed had a big concern over the environmental impacts of mining especially when it comes to water quality and quantity (Scan). The statistics portrayed in these articles illustrate that today’s mining engineers needs to make more of an effort to change the public’s perspective of mining by being more environmentally aware. These engineers should be continuously asking themselves what they could be doing better from an environmental perspective to ensure that history is not repeated and that natural resources are used as efficiently as possible."

Jan 1, 2018

By V. A. Masloboev, A. V. Svetlov, D. V. Makarov

"The methods of heap leaching are considered to be the most promising for the low-grade copper-nickel raw materials. The article presents intensification capabilities of the process. Objects of research: the low-grade copper-nickel ores of Moncheplutone deposits (Moroshkovoye Lake, Nyud Terrasa, Nittis-Kumuzh’ya-Travyanaya (NKT), as well as the copper-nickel ore dressing tailings of the “Kola MMC” JSC. The following directions for the intensification of the low-grade copper-nickel raw materials heap leaching have been considered: preliminary electric pulse destruction (EPD) of ore; ore crushing and further sulfuric acid agglomeration. The impact of sulfuric acid concentration (1-3%) on the extraction of non-ferrous metals kinetics from the copper-nickel ore dressing tailings under various conditions of the percolation leaching has been studied. INTRODUCTION The low-grade grade sulfide ores at the abandoned and producing deposits, overburden rocks, mill tailings and non-ferrous slag are thought to be one of the large-scale sources for non-ferrous metals, on the one hand. On the other hand, they are known to be the subjects of emergency environmental danger. For this reason, the use of mine dumps and tailings, as well as the remained ores left in the ground as raw products, and at the same time decreasing the load on environment, are considered to be the pressing ecological and economic issue (Chanturia et al., 2012). Methods of heap hydrometallurgical and bacterial leaching are sure to be potentially productive for processing such low-grade and technogenic raw materials (Petersen, 2016). The early studies of hydrometallurgical method possibility to process copper-nickel ores of the Murmansk region deposits were launched in the seventies of the previous century (Golovko et al., 1978). For referencing purposes, the main types of impregnated ores from the deposits Zhdanovskoye, Kaula, Sopchinsky Plast and Lovnoozerskoye were selected. The metal content varied, as %: 0.46-1.49 of nickel, 0.01-0.62 of copper. In the first experiments, the solution containing 150g/l of H2SO4 and 135g/l of NaCl, was used in the capacity of leaching reagent. The possibility of underground metals leaching from the ores of the Lovnoozerskoye deposit was justified due to the performed laboratory and further large-sized tests."

Jan 1, 2018

By Ifeanyichukwu Nweke

"Aluminium rolling processing from ingots to cold rolled coils comes with a lot of challenges especially in controlling defective products in casting, hot mill and cold mill operations. Hence this study focused on reducing defects at mills and cast-house using six sigma approaches. The use of six sigma approach will help the production experts to determine the gap between its operation and world class process. Practical data from First Aluminium Rolling mills were presented and analysed and mini improvement projects were proposed based on organisation need to achieve excellence. This study encourages aluminium alloy industries to pursue process improvement projects on the basis of analysis on data obtained from their shop floor, hence ensuring that through this, recovery is improved and cost of poor quality is reduced.INTRODUCTION Engineer Bill Smith while working at Motorola in 1986 introduced a new concept in which a set of techniques and tools are used for process improvement by controlling variations (defects). These tools and techniques are explained by an acronym DMAIC. D DEFINE the problem M MEASURE the variables in the problem A ANALYSE the variables of the problem I IMPLEMENT and verify the solution to the problem C CONTROL the solution to sustain it Most times in six-sigma approach, variations in the process that results in defects and customers’ dissatisfaction are targeted at 3.4 defects per million opportunities. There are numerous methods six sigma application use to achieve quality results and innovative strategies. Improving the quality of process through these methods helps identify and reduce variations which paves way for organisational excellence. In this study, it is encouraged to use six sigma techniques to improve aluminium rolling operations and other aluminium processing activities, the benefits of such improvement concept include: • Satisfy the voice of the customer (VOC) • Minimise costs • Maximise Profits • Build Good Team • Implement Profitable Project"

Jan 1, 2018

By Richter, E. Charikinya

"Mineral processing unit models require information on particulate properties such as particle size, solids flowrate and mineralogical composition to model their operations. Process models that describe the separation process can be classified based on the level of information required from the ore, i.e. the feed stream to the separating unit. The most comprehensive level of mineral processing models is the particle-based modelling approach. Particle based modelling describes a modelling approach where mineral composition, mineral liberation and textural information of particles making up the process streams is used in modelling. The advantage of this approach is that all model streams carry particle level information (size, liberation, shape). This information is obtained by applying automated mineralogy techniques such as Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) analysis which provide accurate and detailed information on process stream particle properties. Currently the use of liberation information in modelling and simulation is rare, due to the limited number of separation models that liberation data as input. The objective of this study is to develop a particle based model for a dry magnetic separator, where mineralogical information is used directly to simulate a dry magnetic separator operation. Magnetic separation tests were carried out on high, medium and low grade magnetite ores using a laboratory magnetic separator. Streams from the separator were sampled and sized for chemical and liberation analyses. A sized mass and elemental balance around the magnetic separator was carried out. The elemental assays of each stream were converted to mineral quantities and a sized mineral balance was done. QEMSCAN measured liberation data was reconciled to the mineral balance based on mineral quantities obtained from chemical assays. This was followed by the development of a particle based model that calculates the trajectory of a single particle based on its mineral composition and textural properties. The model was tested on experimental data and was able to predict the effect of variation in process feed stream mineralogical attributes (liberation, grade, particle size) on magnetic separation performance. Results of this study highlight the benefits of the particle based modelling approach. INTRODUCTION The extraction of mineral values from ore requires liberation of the value minerals from the gangue followed by their separation. Liberation is achieved by size reduction operations (Desmond, 2008; Fuerstenau and Abouzeid, 2002). Separation of gangue material from value mineral takes place in various mineral upgrading stages such as classification, magnetic separation and flotation. In these concentration stages value minerals are separated from gangue minerals based on the physical properties of the ore particles making up the feed such as size, liberation, volume of magnetic material and density. The success of separation is related to the liberation of the feed particles, the performance of the separation technology applied, as well as the inherent characteristics of the feed material (Leißner et al., 2013)."

Jan 1, 2018

By S. A. Bogidaev, M. Yu. Tiunov

"The paper describes the results of the flotation tests with complex rare metal ores from deposits in the Trans-Baikal Territory. Correlations between the quality of produced wolframite, hubnerite and mica concentrates with or without the presence of various alkaline modifiers are determined. Commonly, rare metal ores contain minerals of comparable value to main elements recovered in processing plants using gravitational methods. The paper describes the results of flotation recovery of valuable minerals – main and associated – from gravity tailings of deposits in the Trans-Baikal Territory. It was found that gravity tailings from the first deposit contained fine-grained wolframite, mica (muscovite, lepidolite etc.), feldspar; hubnerite, scheelite, beryl, fluorite, rubidium-containing muscovite from the second deposit, correspondingly. This paper presents the results of the stage flotation tests with the production of tungsten (wolframite, hubnerite), fluorite and mica concentrates from gravity tailings. Figure 1 demonstrates the flowsheet of tungsten ore minerals and mica stage flotation from gravity tailings of the first deposit.Wolframite can be floated using oleic acid with the presence of soda ash, a complexing collector (IM-50), under slightly alkaline conditions in combination with a nonpolar collector [1, 2, 3, 4]. The study included wolframite flotation using the combination of two alkaline modifiers. Flotation of wolframite was performed after pulp desliming, using tall oil saponified with soda ash. The recovery of wolframite in the concentrate of rougher flotation reached 80-85%; the concentrate contained up to 1% of tungsten oxide that can be upgraded to a saleable product using gravitational methods. This procedure was tested during flotation of wolframite, tantalite-columbite and pyrochlore, and provided high performance regardless of a season, at pulp temperatures of 8-10°C, though fattyacid collectors are significantly inefficient at such low temperatures due to low solubility, dispersion and increased collector consumption, consequently. The introduction of two alkaline modifiers in pulp appears to improve these characteristics.The first stage of the tests was focused on increase of iron-bearing tungsten ore minerals recovery from gravity tailings and stabilization of the cold pulp flotation process."

Jan 1, 2018

By V. Panayotov, M. Panayotova

"Wastewater from ores processing is often polluted by molybdate and sulfate (SO42-) ions. Sorption is one of suitable methods for removing those pollutants when presenting in low concentrations. This work reports results on adsorption of sulfate and molybdate ions on metal modified (with barium - Ba and lead - Pb) and organic reagent modified (with Hexadecyl-trimethyl-ammonium bromide - HDTMA) clinoptilolite. Zeolite’s modification with Pb, Ba and HDTMA increases its uptake capacity with respect to Mo(VI) at pH 3, with the uptake capacity decreasing in the order CL-Pb > CL-HDTMA > CL-Ba. Lead-modified clinoptilolite shows high uptake with respect to Mo(VI) in acidic, neutral and slightly alkaline conditions. The presence of SO42- in concentrations twice higher than the amount of Mo(VI) do not interfere with the Mo(VI) removal by CL-Pb. Zeolite’s modification with Ba and Pb renders it able to immobilize SO42- from water in the pH range 3-9. Kinetics of the uptake process is best described by the pseudo-first order kinetic equation. Increasing the initial concentrations of Mo(VI) and SO42- increases the removed amount of pollutants. INTRODUCTION Wastewater from copper-molybdenum ores processing is often polluted by molybdate and sulfate ions. Molybdenum (Mo) migrates easily in water and consequently the Mo polluted areas could extend for hundreds and thousands of meters (Ryzhenko, 2010). Molybdate anion is the only Mo(VI) species in natural water, i.e. at pH > 6.0. Its median freshwater hazardous concentration affecting 5% of the species (HC 5.50%) is 38.2 mg Mo/L (De-Schamphelaere et al., 2010). The marine water chronic toxicity (HC 5.50%) is assessed at 5.74 mg Mo/L (Heijerick et al., 2012). The predicted no-effect concentrations (PNEC) are 12.7 mg Mo/L and 1.92 mg Mo/L correspondingly for freshwater and marine water (Heijerick et al., 2012a). When sulfates present in drinking water in excess of 250 mg/L they cause a cathartic action (especially in children) in the presence of sodium and magnesium, and when the concentration exceeds 600 mg/L, diarrhea. When sulfate-rich effluents are discharged into the environment, they may increase the acidity of water bodies and soils (Guimarães and Leão, 2014). Because of the adverse effects to human health and the environment, limits are set for SO42- concentrations in waters and wastewaters in the range of 250 / 500 mg/L."

Jan 1, 2018

By E. Emelyanenko, P. Solozhenkin, J. Yagudina, O. Ibragimova

"To recover tetrahedrite-tennantite series minerals from porphyry copper-pyrite ores by the froth flotation method, further research on thiol collectors is launched to promote the utilization efficiency of copper ores. In the present paper the adsorption mechanism of the collectors on tennantite surface has been investigated by computational modeling and FTIR-spectroscopic analysis, which have revealed that the decrease in prognosis of collector activity evaluation (PCAE) for tennantite is in the following order: BX (-0.34318), AEROPHINE 3418A (- 0.61756), AERO 5100 (-14.18857). The lower PCAE the stronger the ability of the collector to interact with the mineral surface of tennantite and form the stable complex. More kinetic reliable conditions to form suitable adsorption layer and rupture of the liquid interlayer with AERO 5100 have been observed by FTIR spectra due to decrease of the intensity and stretching and bending vibrations of water (less than 20 and 65%, respectively). In order to verify the feasibility of AERO 5100 as a collector the industrial flotation tests have been conducted. Flotation performance has improved significantly with the stadially grinding and preflotation of tennantite in intercycle copper flotation that allows to avoid desliming of the fragile mineral and minimize loss of Cu and As in tailings. The recovery of copper in copper concentrate increases by 3.9% with the grade maintained.INTRODUCTIONCopper is one of the first metals extracted and the main material of choice for different high-technology applications today. Currently 80% of the world's copper comes from copper sulfide ores. However, due to the depletion of high-grade copper ores in the world and constantly growing demand for copper, the need to develop processes and technologies to treat copper resources from additional sources such as mine tailings, low grade deposits, industrial wastes and deposits with high impurity levels such as As and Sb will continue to increase (Miller and Craig, 1983). The beneficiation processes of copper-pyrite ores consisting of tennantite-tetrahedrite series minerals are generally complex. Tetrahedrite-tennantite minerals occur as fine anhedral grains intermixed with grains of galena, sphalerite, chalcopyrite, pyrite and other sulfides (Saharova, 1966). The mineralized zones of Southern Urals, Russia deposits correspond with these ore types but tennantite-tetrahedrite series are more abundant in ores at the Uzelginskoye deposit, some samples of which contain 70% of copper in tennantite form (Seravkin et al., 1994). This deposit differs from other similar copper-pyrite ores by thin mutual ""germinating"" minerals and higher content of arsenic (up to 0.8-1 %) which create additional considerable problems in enrichment (Solozhenkin et al., 2016)."

Jan 1, 2018

By Alexander V. Epiforov, Stanislav V. Balikov

This paper describes of processing tests of 8 flotation concentrates containing precious and base metals by pressure oxidation (POX) method. Concentrates 1 and 2 were gold-copper concentrates. Zinc and silver were by-products in these concentrates. These concentrates were processed by POX with following cyanidation of POX solid residues, copper solvent extraction and zinc carbonate precipitation. The recoveries of gold, copper, silver and zinc from these concentrate were 98, 99, 30 and 99%, respectively. Concentrates 3 and 4 were lead-zinc concentrates. Silver was by-product in concentrate 3. Gold, silver and copper were by-products in concentrate 4. Concentrate 3 was processed by POX with following reduction smelting of POX cakes for primary lead recovery and zinc carbonate precipitation from POX solution. The recoveries of lead and silver into ingot were 96 and 98%, respectively. The recovery of zinc was 99%. Concentrate 4 was processed by POX with following zinc carbonate precipitation and reduction smelting of POX cakes. Copper was precipitated from the POX solution using sodium sulphide prior zinc precipitation. The recovery of zinc into carbonate concentrate was 99%. The recoveries of lead, gold and silver into lead bullion were 95, 99 and 98% respectively. The recovery of copper into sulphide concentrate was 99%. Concentrate 5 was gold-pyrite concentrate, and concentrates 6-8 were double refractory gold-arsenopyrite concentrates. Silver was by-product in these concentrates. These concentrates processed by POX and CIL. The recovery of gold from concentrate 5 was 98%, and from concentrates 6-8 was 85-90. Low gold recovery from concentrates 6-8 was associated with preg-robbing factor. The recovery of silver from gold-sulphide concentrates did not exceed 10-20%. The low silver recovery was associated with argentojarosite formation that is resistant to cyanidation. The flowsheets for complex processing of precious and base metals sulphide flotation concentrates based on this test work results were proposed.

Jan 1, 2018

By Y. Tang

"Rare earth elements (REEs) have many key applications in traditional and advanced technologies. A shortage of several critical REEs is expected due to the discrepancy between the availability of REEs from REE deposits and the REE demand from the market. REE recovery and separation from secondary resources such as uranium wastes and recycled materials might help balance the shortfall in a cost-effective way. This paper presents data concerning the recovery of heavy REEs (HREEs) from uranium raffinate. It also discusses the design, commissioning, and operation of a solvent extraction pilot plant for the separation of REEs.RÉSUMÉ Les éléments des terres rares (ÉTR) trouvent de nombreuses applications importantes dans les technologies classiques et de pointe. On prévoit une pénurie de plusieurs ÉTR critiques en raison des divergences constatées entre la disponibilité des ÉTR provenant de gisement d’éléments des terres rares, et la demande d’ÉTR sur le marché. La récupération et la séparation des ÉTR à partir de ressources secondaires telles que les déchets générés par le traitement du minerai d’uranium et les matériaux recyclés pourraient contribuer à équilibrer cette pénurie de manière rentable. Cet article présente des données relatives à la récupération des ÉTR lourds (HREE, de l’anglais heavy REEs) à partir de raffinat d’uranium. Il aborde également la question de la conception, de la mise en service et de l’exploitation d’une usine pilote d’extraction par solvants pour la séparation des ÉTR INTRODUCTIONSignificant amounts of strategic specialty heavy rare earth elements (HREEs) are present in waste streams in Saskatchewan uranium operations. Selective precipitation including neutralization, oxalate, and double-salt precipitation, as well as sulfide precipitation, ion exchange (IX), and solvent extraction (SX) are commonly used technologies for the recovery and purification of rare earth element (REE) solutions. REE oxalate precipitation can effectively remove Fe, Al, Ca, Si, and other impurities by taking advantage of the solubility difference between REE oxalates and impurities in the acidic solution (Xu, 2005)."

Jan 1, 2018

By Kris De Bruyne

Since 2013, GSR has undertaken 4 exploration campaigns, which focused on environmental baseline monitoring (marine biology), resource definition and technological change. The seabed nodule collection vehicle has a significant influence on the achievable production rate and is for that reason thought to be a serious risk in developing an economical viable mining operation. GSR is currently working on a pre-prototype of a seabed nodule collection vehicle. The program, called ProCat, started in 2015 and will take up to end of 2019. ProCat can be split up in 2 phases: ‐ ProCat#1 [2015 – Q2 2017]: separate parallel testing of the nodule collection- and driving mechanism (Tracked Soil Testing Device Patania I – TSTD Patania I). The trafficability was tested in-situ; the collection mechanism was tested in a laboratory. Phase 1 has been completed successfully in September 2017. ‐ ProCat#2 [Q3 2017 – end of 2019]: the knowledge acquired during the first phase was used in this 2nd phase. Both collection mechanism and driving mechanism were integrated into the design of a pre-prototype seabed nodule collection vehicle (Pre-Prototype Vehicle Patania II – PPV Patania II). This pre-prototype vehicle will be used for a simulated mining test in Q2 of 2019 in the GSR- and BGR license area. The main objective of the ProCat research program, and especially the 2nd phase, is to integrate the nodule collector on the tracked chassis and develop an operating vehicle causing minimal environmental impact hereby validating the requirements for a full scale polymetallic nodule collection vehicle in the actual operational environment of the CCFZ. Following the ProCat project, GSR is working towards a system-integrated mining test once exploitation regulations have been agreed by the ISA and its member States.

Jan 1, 2018

By Shahid Islam, Lucian Bogdan

Deep and large diameter drilled shafts use mostly bundles of Grade 60 (415 MPa) reinforcing bars as longitudinal reinforcement with rebar splices to make it longer. Lower Grade steel requires large number of bars which result in rebar congestion and difficulty in placing concrete. This leads to increased labor cost for fabrication and installation. By utilizing larger size and higher strength threadbar, the congestion of rebar can be reduced significantly and bundling of bars can be avoided. The lap splices are replaced with simple threaded couplers and end hooks are replaced with end terminators. Threadbar conforms to ASTM A615-15 and can be epoxy coated if required for corrosion protection. This paper describes an attractive value engineering of replacing Grade 60 (415 MPa) bundle of rebars with larger diameter Grade 75 (515 MPa), Grade 80 (550 MPa) and Grade 100 (690 MPa) threaded bars and threaded couplers in some specific drilled shaft projects in the USA. INTRODUCTION A drilled shaft which may also be referred to as drilled piers, caissons, cast-in-drilled-hole piles and bored piles is the key element to the foundation of massive structure. They are used for tall buildings, bridges and foundations for other applications such as retaining walls, sound walls, signs, or high mast lighting. Drilled shaft foundations are typically 3 to 12 feet (0.9m to 3.7m) in diameter cast-in-place deep foundation elements constructed in a drilled hole that is stabilized to allow controlled placement of reinforcing steel and concrete. Drilled shafts for transportation structures are commonly used to depths of up to 200 ft (61m) in the USA. Drilled shafts can be installed in a variety of soil and rock profiles, and are most efficiently utilized where a strong bearing layer is present. The reinforcing cage is typically lowered into position within the hole and then concrete placed through the center of the shaft, flowing from bottom to top through the reinforcement to fill the hole.

Jan 1, 2018

By Venkataramana Runkana, Pradip Gautham, Beena Rai, Sreedhar Reddy

"IT enabled platforms are the key to provide an integrated view of the business activity or an enterprise as a whole. Attempts to integrate all functions in an enterprise such as mine-to-market initiatives, wherever and to whatever extent implemented, have provided significant benefits to the industry. The transformative potential of IT enabled integration platforms is illustrated in this communication from our own work in this field. TCS PREMAP (Platform for the Realization of Materials and Products) is a knowledge-driven engineering design and development platform which leverages modeling and simulation and artificial intelligence into the engineering design process. We illustrate the customization of this generic platform for the design and optimization of mineral processing plants in an integrated manner. TCS PEACOCK (Process and Equipment Analytics for Optimization and Control) has been developed to enable automation of data analytics in the operating plants. We illustrate its utility and power in improving the plant performance with the help of case studies from our work on pelletization of iron ores and optimization of flotation plants. INTRODUCTION We are living in an exciting digital era. With the advent of cloud computing and social media on the one hand and rapid advances being made in several research areas of interest to us in the minerals and metals industry such as artificial intelligence (AI) & machine learning, robotics, unmanned vehicles including drones, big data analytics, 3D printing, sensor technologies, renewable energies and internet of things (IoT), many disruptive transformations in our industry are on the horizon. Recent advances in information technology (IT) and knowledge engineering, in combination with appropriate domain expertise, that is, our enhanced understanding of the underlying science of mining and mineral processing operations and the availability of a variety of powerful modeling-simulation tools make it possible to address the challenging problems facing the mining and mineral processing industry, in an integrated manner."

Jan 1, 2018

By Bo-Hyun Kim, Mark K. Larson

"While faults are commonly simulated as a single planar or non-planar interface for a safety or stability analysis in underground mining excavation, the real 3D structure of a fault is often very complex with different branches that reactivate at different times. Furthermore, these branches are zones of non-zero thickness where material continuously undergoes damage even during interseismic periods. In this study, the initiation and the initial evolution of a strike-slip fault was modeled using the FLAC3D™ software program. The initial and boundary conditions are simplified and mimic the Riedel shear experiment and the constitutive model in the literature. The FLAC3D model successfully replicates and creates the 3D fault zone as a strike-slip type structure in the entire thickness of the model. The strike-slip fault structure and normal displacement result in the formation of valleys in the model. Three panels of a longwall excavation are virtually placed and excavated beneath a main valley. The characteristics of stored and dissipated energy associated with the panel excavations are examined and observed at different stages of shear strain in the fault to evaluate bump potential. Depending on the shear strain in the fault, the energy characteristics adjacent to the longwall panels present different degrees of bump potential, which is not possible to capture by conventional fault simulation using an interface.INTRODUCTIONThis paper is part of an effort by the National Institute for Occupational Safety and Health (NIOSH) to identify risk factors associated with bump-prone potential in highly stressed ground conditions. More specifically, this paper reports an exploratory effort with an unconventional approach using a numerical tool to try to better understand a possible scenario where bump risk might be increased—that is, a scenario involving a strike-slip fault. The objective is to assess whether a numerical tool might be useful or practical in forecasting bump potential associated with a strike-slip fault for a typical, structural geologic setting."

Jan 1, 2018

By Jessica M. Wempen, William G. Pariseau, Michael K. McCarter

"Quantitative analysis of mine-wide subsidence at the kilometer scale and details of stress distribution about an advancing longwall face are estimated using an adaptation of the finite element method. The method is well suited to the tasks at hand. For greater realism, variability of strata properties is taken into account as are the effects of joints and cleats on elastic moduli and strengths. Evolution of pillar stress and entry closure remote from the face is readily quantified in a series of analyses that simulate face advance. Computed results compare favorably with the evolution of closure measurements about an instrumented pillar in a two-entry headgate. The appropriateness of the finite element method is confirmed. This method is based on first principles that avoid empirical schemes of uncertain applicability and numerical models “calibrated” by fitting computer output to mine measurements.INTRODUCTIONMine-induced seismicity is intimately related to strata mechanics associated with longwall coal mining and room and pillar mining, as well. Strata deformed beyond an elastic limit often tend to fail rapidly by brittle fracture and, thus, to emit acoustic signals in the form of elastic waves. Understanding the induced seismicity in coal mining offers the potential for early warning of hazardous conditions. Many years of experience with seismic phenomena associated with hardrock mining suggest considerable complexity should be expected. However, recent coal mine studies (Pariseau, 2014; Pariseau, 2015; Pariseau and McCarter, 2015; Pariseau and McCarter, 2016) have shown high correlations of seismicity with element failures in finite element simulations. The main lesson learned from these studies is one elaborated by Iannacchione et al (2005); deviation from normal activity is an early warning of ground control difficulty. For example, an abrupt increase in seismic event rate, or equivalently, an increase in element failure in finite element simulation of panel advance, is a cautionary indication for ground control. Present and past study results demonstrate the effectiveness of finite element simulations for mine design and early detection of potential ground control issues."

Jan 1, 2018

By S. Gering, R. Ruiz, C. H. Calderon-Arteaga, J. Barrios

"INTRODUCTION Located in the northeast corner of Zacatecas State, Mexico, the Peñasquito Operation is comprised of the Peñasco and Chile Colorado (Brecha Azul) deposits. Open pit mining (pre-stripping) began in 2010 and full production commenced during 2011. The open pit mines feed both a sulphide concentrator (mill) and a heap leach pad. The project is owned by Goldcorp, Inc. Penasquito is a poly metallic deposit with Au, Ag, Zn and Pb being recovered as payable metals. As a consequence of lower grade ores expected with advancing mine-life Peñasquito is facing a declining metal production profile. To maximize returns and asset value plant modifications including the addition of a carbon pre-float circuit and a pyrite leach circuit to improve recovery are currently being undertaken. This carbon pre-float circuit will enable the recovery of precious and base metals from carbonaceous sediments. This material is currently being stockpiled. With the associated increase in complexity in the process circuit, the requirement of the ore control system to accurately predict ore feed characteristics is critical to maximizing metal recovery at the Penasquito operation. The addition of the carbon pre-float circuit was also a key driver in allowing the Chile Colorado open pit to be developed. These conditions alongside Goldcorp’s drive to increase profitability, and maximize net asset value has created challenges. These challenges are numerous and are multifaceted, however the ability to accurately route materials from the ore control system is critical to site success, and some of these challenges have been overcome by the adoption and implementation of a new ore control (OC) technology. Examples of these technological innovations in the ore control program are discussed in this paper and include improvements in geo-modeling, material routing and reconciliation. Successful implementation of these elements has led to significant improvements in selectivity, performance, and data management, while reducing the variance between planning and execution, thus helping to drive overall improvement across the operation."

Jan 1, 2018

By T. M. Russell

"Face mapping is a simple but invaluable means of geological and geotechnical data acquisition whereby intact rock properties, rock mass properties, discontinuity properties, and structural orientation can be assessed. Although traditionally done via direct contact with the mapping face through techniques such as line mapping or window mapping, remote face mapping using various digital techniques has become increasingly popular in recent years. Sishen is a large open pit mining operation requiring a comprehensive geotechnical data-set to evaluate pit wall design and stability with the necessary level of confidence. Geotechnical borehole data, face mapping data, geotechnical laboratory testing data, and implicit structural models provide the main sources of this information. Although a large geotechnical borehole database has always been maintained at the mine, face mapping has in the past been restricted to sporadic and isolated stability assessments. In 2013 the mine acquired a terrestrial laser scanner with the resolution, photographic capabilities, and software required to carry out geotechnical face mapping. A face mapping procedure was set up based on accepted face mapping methods, the data requirements of the mine, and capabilities of the laser scanner system. Mapping data obtained from the scans was integrated into the Acquire geological data management system, a purpose-designed structured query language (SQL) database system used for storing the mine’s geotechnical data. Within the geotechnical design process, having face mapping data available has improved confidence in the properties of the rock mass and structural environment, allowing for better definition of geotechnical design sectors. Overall, the face mapping and geotechnical analysis features of the terrestrial laser scanner in use make it an invaluable geotechnical data capture tool, provided a system is in place to store mapping data in a manner that allows for meaningful rock mass and structural information to be produced. IntroductionFundamental to the geotechnical design process is the acquisition of a reliable and complete geotechnical data-set. Geotechnical data acquisition will typically commence during the early stages of a project and continue well into the operational life of the mine, with the data confidence progressively increasing as the amount of data captured increases. Sishen mine currently bases all open pit geotechnical designs and geotechnical risk assessment on geotechnical borehole data in conjunction with interpreted structural models. Boreholes are logged and the data is captured in an ongoing process. This process forms the initial step in the geotechnical design and risk assessment process whereby the raw data is used to classify the strength properties for each lithology, provide inputs for geotechnical block models, and ultimately provide the inputs for slope design analyses. To date, borehole data has provided the only largescale, organized data-set for input into geotechnical analyses at Sishen. Although borehole data is the best and most comprehensive form of geotechnical data, there are some shortfalls that can be addressed by other data collection methods. These shortfalls are as follows."

Jan 1, 2018

By R. Darlington, S. Ji

"High pressure die casting is a promising process to make thin-wall components with high dimensional accuracy and excellent surface quality. However, the non-uniformity is one of the important features in castings. The inhomogeneity in tensile properties and microstructural characteristics were studied for the castings with different thicknesses made by high pressure die-cast Al-Mg-Si alloys. For the local mechanical properties in the die-castings, the casting skin provided the highest, whereas the casting centre provided the lowest yield strength, UTS and elongation. The yield strength, UTS and elongation were significantly decreased towards the casting centre. The microstructural inhomogeneity is characterised by the segregation of coarse fragmented dendrites, the reduction of solute concentrations of Mg and Si, and the increase of porosity level from the surface to the centre of castings. The growth velocities of eutectic a-Al phase estimated using the Jackson-Hunt model confirm that the growth variation is larger in the thin castings than that in thick castings.INTRODUCTION Inhomogeneity is an inherent characteristic in as-cast microstructures of a variety of alloys because of their non-uniform chemistry, microstructure, defects, topology and the resultant mechanical properties in the different ranges of localization (Campbell, 2003). Generally, three types of inhomogeneities characterise casting microstructures, which include (a) the casting defects of shrinkage and gas porosity, misruns, cold shuts, inclusions, hot tears and hot spots; (b) the non-uniform microstructure from the surface to the centre of castings; and (c) the non-uniform microstructure from the dendrites grown from primary solidification and the structure formed during the subsequent eutectic solidification in inter-dendritic regions. The chemical composition and the morphology between the primary dendrites and the inter-dendritic eutectics also differ in the as-cast microstructure. Obviously, the inhomogeneity is different in the castings obtained from different casting processes."

Jan 1, 2018

By C. H. Veloso

"Starch is the most widely used depressant in the reverse cationic flotation of iron ores. There is however, an indication from recent studies, that other polysaccharides may successfully replace them. When starches are used in the flotation of iron ores in the presence of quartz as gangue mineral, their strong adsorption on the surface of iron oxides can be explained by the molecular conformation between the available sites on the mineral surface and two hydroxyls of starches. However, when the gangue minerals are iron-bearing silicates, the strong interaction with starch can occur on these minerals since they have the same surface behaviour as iron oxide. In this work bench scale tests were conducted in order to generate scientific knowledge about other alternatives depressants for the flotation of iron ores. A magnetic pre-concentrate from a skarn iron ore processing plant was used as feed material for flotation tests. The reverse flotation approach was used to upgrade the iron content by removing complex ironbearing silicates. The depressants used in this study were: corn starch, dextrin, carboxymethyl cellulose (CMC) and humic acid. The tests were performed under different pH conditions in order to try to relate the efficiency of depression to the pH used during flotation. The results show the important role of pH as each depressant reached its best performance at different pH values. At alkaline pH the corn starch showed best depression performance while the humic acid is more efficient at pH close to neutrality.INTRODUCTIONIron corresponds to approximately 6% of earth’s crust composition (McDonough and Sun, 1995). It is the most used metal in our lives, some of its properties as resistance and facility to be shaped makes is replacement very difficult. The primary sources of iron on our planet are minerals. The iron-bearing minerals most commonly found in nature and economically exploited are magnetite [Fe3O4], hematite [Fe2O3], goethite [FeO(OH)] and siderite [FeCO3] (L O Filippov et al., 2014). These minerals are commonly associated with other minerals (most of the time not economically exploited) forming the so-called iron ore. Iron ore is the source of primary iron for the world’s iron and steel industries."

Jan 1, 2018

By A. Singh, C. Da Corte

"South Africa possess the biggest fluorspar reserves in the world followed closely by China. In light of the current commodity downturn this paper explores the use of Dense Media Separation (DMS) as a coarse pre-concentration method for two fluorspar deposits located in South Africa in which the dominant gangue is carbonate present in the form of dolomite and calcite. Heavy Liquid Separation indicated that conventional pre-concentration of the drill core samples from both deposits would result in unacceptably high fluorite CaF2 losses. At a maximum CaF2 loss to floats of 5% the benefit of DMS would be economically marginal and difficult to justify as a conventional pre-concentrator. In light of cashflow constraints, a twin flowsheet was proposed for the sole purposes of upfront cash generation in which the majority (67-77%) of the CaF2 would report to a high grade flotation plant in 38-41% of the mass whilst the rejects would be stockpiled for flotation at a later stage. Considering the proposed twin flowsheet approach the high grade product split was achieved using DMS and this paper documents the challenges encountered and results achieved. INTRODUCTION Fluorspar is the commercial term for the mineral fluorite (calcium fluoride, CaF2). Worldwide production of fluorspar is dominated by four countries namely China, Mexico, Mongolia and South Africa. Although South Africa is the fourth largest producer, it has the largest fluorspar reserves closely followed by China (U.S. Geological Survey, 2017a). Fluorspar is broadly categorized into two grades namely acid grade also referred to as acidspar (>97% CaF2); and sub-acid grade (ceramic and metallurgical grade) commonly referred to as metspar (=97% CaF2). Acid grade fluorspar is used for the production of hydrofluoric acid (HF) which in turn is used for the manufacture of fluorocarbons and semi-conductors in the electronics industry; metal processing; the production of insecticides, herbicides and cleaning detergents, and the manufacture of uranium tetrafluoride used to concentrate the uranium isotope 235 for use as a nuclear fuel (British Geological Survey 2010; Miller 2001). Ceramic grade fluorspar (85-95% CaF2) is used in the ceramic industry as a flux and opacifier in the production of glass and enamels. Ceramic grade fluorspar is also used to make coatings for welding rods and as a flux in the steel industry. Metallurgical grade fluorspar (60-85% CaF2) is primarily used in the steel industry as flux to reduce the melting temperature and remove impurities in steel making. Similarly metallurgical grade fluorspar is also used as flux in cement production to reduce energy consumption (British Geological Survey 2010; Miller 2001)."

Jan 1, 2018