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By E. A. Bekchurina, Yu. P. Morozov

"This paper presents the results of a study of the concentration of flotation froths in tapered chutes. The tests were conducted on lab and full-scale plants, and the results obtained were mathematically processed. The kinetics of monophase recovery from a stationary flotation froth, hydrodynamics of froth flows traveling in a tapered chute were investigated. The effect was studied of the mass fraction of the valuable component in the chute feed, yield of the chute’s overflow, and chute design on the concentration performance. Processing of the collected data revealed the general laws of the process and allowed to develop a technique for modeling concentration of the flotation froths of sulphide copper ore in a tapered chute to predict the performance without testing. It was found that concentration in tapered chutes allows to obtain products that are comparable in quality with froths after one or several cleaner flotation stages.INTRODUCTIONThe present production expansion rates require continuous improvement in the grade of flotation concentrates, while the grade of the mineral feed is constantly deteriorating. This leads to a significant complication of flotation flowcharts. Flowcharts become multi-staged with multiple cleaner flotations, negatively affecting the production costs.In recent years, researchers are paying close attention to the processes occurring in the froth layer in the flotation cells. Improving the concentrate grade is facilitated by secondary concentration of minerals in the froth layer, which consists in fixing the hydrophobic particles released as a result of the coalescence of the bubbles of the upper layer when moving downward at the liquid-gas interface of the froth layer. In this case, the released hydrophilic particles, trapped in the froth layer as a result of mechanical removal, migrate from the froth together with the liquid phase."

Jan 1, 2018

By Paul Worsey, Matthew Coy

In the blasting industry, many different techniques are used to estimate and examine the effects of varying explosives and blast designs on the breakage of a rock mass. The overall objective is to find a cost-minimized blasting solution that also conforms to the legal and environmental concerns related to blasting. A major drawback to current blasting methods is the inability to account for "caprock," or a thick overlying layer found in sedimentary rocks that creates large amounts of oversize blasted material, especially on the top of a muck pile. This can lead to underestimating oversize in shots with massive top layers. A better fundamental understanding of blasting processes with caprock is required.

Jan 1, 2018

By T. Holmes, S. Davison

"A surge bin at Agrium’s Vanscoy potash operations has been plagued with flow, wear, and corrosion issues since being built in 1967. The culprits? The bin’s carbon-steel construction, geometry, and the resultant funnel-flow pattern are the root causes. An investigation and cost analysis indicated that hopper redesign and retrofit would increase production and reduce maintenance and capital costs. The retrofitted bin provides safer, more reliable operation and has a much longer predicted working life. Using this example, the authors describe bulk-solids-flow theory and highlight the importance of customizing bulk-material-handling-system design using appropriate flow properties to improve reliability, safety, and cost effectiveness.RÉSUMÉ Depuis sa construction en 1967, un réservoir intermédiaire de l’exploitation de potasse Vanscoy d’Agrium connaît des problèmes de débit, d’usure et de corrosion. Les responsables ? La construction en acier ordinaire du réservoir, sa géométrie et la structure de débit en résultant au niveau de la carotte en sont les causes fondamentales. Une étude et une analyse des coûts indiquaient que la restructuration et la rénovation de la trémie permettraient d’augmenter la production et de réduire les coûts d’entretien et en capital. Un réservoir rénové permet de renforcer la sécurité ainsi que la fiabilité de l’exploitation, et sa durée d’activité prévue en est augmentée. En se fondant sur cet exemple, les auteurs de l’article décrivent la théorie du débit de matières solides en vrac et insistent sur l’importance de personnaliser la conception du système de manutention des matériaux en vrac à l’aide de propriétés rhéologiques adaptées afin d’améliorer la fiabilité, la sûreté et la rentabilité.INTRODUCTIONIn early 2013, Agrium’s Vanscoy Potash Operations (VPO) engaged Jenike & Johanson Ltd. (J&J) to provide testing, consulting, and structural engineering services related to proposed modifications to the 270 t special standard product surge bin, which Agrium planned to undertake during a two-week shutdown in August 2013. The bin, which had been plagued with flow, wear, and corrosion issues for its entire working life, was essential for the continuous operation of two of VPO’s compaction plants and for efficient dispatching to loadout. The bin often experienced product hang-ups, clumping on the walls, and plugging at the hopper outlet. Two recent unscheduled mill shutdowns had been partially attributed to flow issues in the bin due to clumping and product plugging up at the screws. These problems increased maintenance costs, limited production capacity, and degraded product quality. Holes and paper-thin sections in the bin walls discovered during a 2013 inspection revealed the potential for major hot material leaks or even structural failure. Either issue would stop plant operations until the bin could be repaired or bypassed. Clearly, the bin cone had reached the end of its life and required replacement."

Jan 1, 2018

By M. Ranjbar, M. Khosravi Rad, A. Tohry

"The filling degree is defined as the volume ratio of the load inside the mill, which determines the power drawn from the motor, as long as the filling degree is not more than the optimum level. As the filling degree increases beyond the optimum level, the impact energy inside the mill will decrease and as a consequent, the mill power output will also decrease. Therefore, the mill filling degree is a key parameter in evaluating the grinding circuit performance, as it determines the mill reaction to the input feed. Since this parameter has an impact on the mill capacity, measuring the mill load is vital for control and optimization of grinding process. As in Choghart Processing Plant no instrument is available to measure the AG mill filling degree, an empirical model based on the bearing-oil pressure is proposed. The AG mill filling degree was related to the differences between the average pressure of input and output bearings, the circulating load and power drawn. It was shown that a quadratic model could relate the mill filling to the above mentioned measurements. This model showed that when the power drawn and circulating load decreases the bearing-oil pressure needs to be checked. If the bearing-oil pressure increases the feed rate needs to be decreased and steel ball be charged to the mill to increase the grinding and prevent mill overloading. INTRODUCTION The feed quality (size and hardness) affects the grinding process in AG mills. Reducing the top feed size and increasing the ore hardness reduce the mill efficiency and increase the particles with critical dimensions inside the mill. These will result in increasing the mill filling degree and reducing the mill throughput and efficiency (Wills and Finch, 2015). The volume ratio of the load inside the mill is called filling degree, which determines the mill power drawn. It is believed that if more energy is mainly spent on grinding (Wills and Finch, 2015). Therefore the mill power draw is used as a mean to control the mill efficiency."

Jan 1, 2018

By V. F. Petrov, E. P. Olberg, S. V. Petrov

"The study was carried out using process solutions produced during cyanidation of gold-bearing concentrates from a gold-processing plant. It was found that the water contained a significant portion of thiocyanate (7910.0 mg/L), cyanide was virtually not present. The metals occurred primarily as iron (355.0 mg/L) in the form of ferrocyanide. Cyanide recovery was conducted using an ozone treatment process with reactors developed by the Environmental Department of Irgiredmet. The process design ensured complete utilization (100%) of O3, thus equipment operation safety increased.The recovery of free cyanide from thiocyanate was 76.6%, which corresponded to 5.12 kg of NaCN (100%) per 1 m3 of solution. Recovered NaCN can be used for recycling in hydrometallurgical processes.The operating costs estimation showed that the production cost of a tonne of recovered cyanide was US$1288.7, considering the prices of energy and commercial sodium cyanide in Russia in 2017, i.e. recovered cyanide is cheaper than commercial cyanide by 55.8%.INTRODUCTION Depletion of oxidized gold-bearing ores readily amenable to cyanidation has shifted focus to large-scale processing of primary ores with high sulphide content. Primary ores processing flow sheets involve gravitational and/or flotation concentration with subsequent treatment of produced gold-bearing concentrates. Typically, concentrates reporting to cyanidation contain considerable amounts of sulphur that can interact with CN- and further formation of SCN-. The use of refractory gold liberation methods (bacterial liberation, ultra-fine grinding) provides activation of this side reaction up to complete consumption of free cyanide in a short period. This makes water recycling unviable and impractical.The interaction of the sulphur content in concentrates and cyanide contributes substantially to consumption of NaCN required for efficient gold recovery. Inappropriate consumption of the main reagent achieves dozens of kilogram per tonne of material to cyanidation, and reaches approximately 100% when gold is recovered from activated sulphide-containing products (e.g. by ultra-fine grinding)."

Jan 1, 2018

"The most common comminution testing methods and the associated analytical procedures provide average values and do not capture the variability in breakage behaviour of ore particles. Therefore, plant designs and process performance predictions use only average values; hence, the inherent variability that exists within an ore domain translates into variation in process performance. This paper discusses the drawbacks of using the average approach to impact comminution testing and plant design. It considers breakage intensity from a single-particle testing perspective. To clearly delineate breakage behaviour of each broken particle, an experimental technique using the JK Drop Weight Tester (JKDWT) has been developed by which actual comminution energy per particle and breakage intensities were measured directly. Four different ore types in ranges of -45+37.5mm and -22.4+19mm were tested at three energy levels of 0.1, 0.25, 0.5 kWh/t and six energy levels of 0.5, 1.0, 2.0, 2.5, 3.0 and 4.0 kWh/t, respectively. Sieved results of individual particles, notionally, t5, t10 and t50 showed the presence of large variability in their breakage behaviour, which was not captured by the standard JK impact breakage testing approach. In addition, the original JKMRC model is modified by introducing a third parameter, ‘Emint10’ which describes the minimum energy required to produce the minimum percent t10 for a given ore type and its significance is tested statistically. These results suggest that the analysis of breakage variability may lead to more robust plant designs. Perhaps, the most useful insight from this work is to extend single particle breakage model developed by JKMRC to a comminution percentile envelope which may provide a more detailed picture of ore breakage variability. INTRODUCTION Rock consists of mineral grains, pores, voids and cracks that may differ markedly in size/density which make rock a heterogeneous material by nature. The degree of heterogeneity in rock affects its breakage characteristics where these variations increase local differential strain and stress within a stressed rock (Scholz, 1968) and it depends on many factors such as rock genesis, alterations, etc. One important aspect of this heterogeneous feature is presence of a large amount of experimental scatter in rock breakage results when considered from a quantitative perspective (Bieniawski, 1967; Liu, Roquete, Kou, & Lindqvist, 2004)."

Jan 1, 2018

By Francisco Sena Leite, Thomas Palangio, Vinicius Miranda

With an increasing pressure to find efficiencies in the mining industry, operations are looking for continuous improvement tools to validate blasting procedures, a crucial and often overlooked area of the process. Using case studies completed at both small and large-scale mining operations, this technical paper proposes a practical methodology for pattern expansion studies, taking into account terrain parameters, rock quality and explosive strength. This technical paper will use a series of tools geared towards an economical continuous improvement procedure, using UAV particle size analysis to optimize blasting based on “generalized reduced gradient” for non-linear problems, with cost savings being the main objective. For the validation of this methodology, one scenario was created based on the operation’s budget: an economical continuous improvement plan that relied on manual data collection methods in order to baseline and optimize procedures.

Jan 1, 2018

By Malcolm Clark, Robin K. H. Falconer

There are a number of likely impacts from mining operations, but a key issue is uncertainty about the environmental effects of sediment plumes created by disturbance to the seafloor and discharge of processed waters. The New Zealand National Institute of Water and Atmospheric Research (NIWA) is undertaking a research project to improve understanding of such impacts (relevant to both mining and trawl fisheries), by examining the extent and persistence of sediment plumes, the immediate impact and subsequent recovery of seafloor exposed to these plumes, and the effect on functioning of ecologically significant species. The project will use a combination of field survey experimentation with in situ observations and controlled laboratory-based experiments. The field work begins in May 2018 when an area of up to 1km2 at depths of 400-500 m on the Chatham Rise, 450 km east the New Zealand South Island will be subjected to disturbance by an upgraded former NOAA Benthic Disturber. The suspended sediment load created by the disturbance will be tracked and monitored, with the effects on seafloor animals examined by pre-and post-disturbance sampling. A wide range of seafloor sampling, benthic landers, towed cameras, oceanographic moorings and water column monitoring will be carried out over a three week period. Monitoring surveys will be repeated in 2019 and 2020 to determine the longer-term resilience and recovery of disturbed communities. The laboratory-based side of the programme, also starting in 2018, involves holding live deep-sea corals and sponges in tanks at NIWA, and exposing them to various levels and duration of particle loads in the water in order to reveal lethal thresholds as well as sub- lethal effects of settled and suspended sediment.

Jan 1, 2018

By Fuqiang Zheng, Shuai Wang, Feng Chen, Yufeng Guo, Guanzhou Qiu, Tao Jiang

"The direct reduced iron powder and Ti-V-rich material was prepared from vanadium titanomagnetite concentrate by solid-state reduction-magnetic separation. The result indicated that under the studied conditions, adding KS can effectively improve the metallization rate of pellets. 2% KS was well mixed with vanadium titanomagnetite concentrate to make the pellets. The green pellet was preheated at 900 ? for 6 min. The preheated pellet was reduced at 1050 ? for 100 min, then crushed and ground to more than 80% was below 0.045 mm. The direct reduced iron powder and Ti-V-rich material were separated from the slurry by wet magnetic separation at 800Gs. The TFe content of magnetic material was 90.63%, and the Fe recovery rate reached 96.53%. The TiO2 and V2O5 contents of Ti-V-rich material were 28.40 % and 1.64 %, respectively. The TiO2 and V2O5 recovery rates were 69.05% and 96.82%, respectively. 1. Introduction The ilmenite and rutile are the main titanium resources which can be used in the present technical level and economic conditions[1,2]. However, with the rapid development of China’s economy, the market demand of titanium products is increasing sharply. The current supply of ilmenite and rutile cannot meet the needs of chemical industry[3]. China is rich in vanadium titanomagnetite concentrate which contains abundant titanium and vanadium resources. The TiO2 and V2O5 content of vanadium titanomagnetite concentrate are usually about 7% and 0.3%, respectively[4]. Because the TiO2 and V2O5 grades are low, it generally requires pre-concentrated to Ti-V-rich material before extracting the titanium and vanadium. Therefore, it is vital to find effective processes for pre-concentrating the titanium and vanadium in vanadium titanomagnetite concentrate. There are many methods[5-13] developed or under development to pre-concentrate Ti-V-rich material from vanadium titanomagnetite concentrate, including the blast furnace process, pre-reduction electric furnace process, to utilized vanadium titanomagnetite concentrate are direct reduction-electric furnace smelting, sodium salt roasting-direct reduction-electric furnace smelting and direct reduction-magnetic separation and so on. The blast furnace process and other methods cannot effectively utilize the titanium and vanadium resource due to the technical or environmental problems[9]. In this study, the vanadium titanomagnetite concentrate was obtained from Panxi region of China, the reserves of which account for 11.6% of vanadium and 35.17% of titanium all over the world[3]. The preparation of direct reduced iron powder and Ti-V-rich material based on reduction-magnetic separation is proposed. The process utilizes a new catalyst for titanium ore reduction in rotary kiln followed by magnetic separation. Using this novel technology, the titanium-vanadium and iron are successfully separated. Compared to the traditional reduction of Ti-bearing ore, the reduction temperature reduced to 1050 ?, leading to higher efficiency, lower energy consumption and investment, and broader applications."

Jan 1, 2018

By Yuki Koshino, Kenji Kaneko, Yasuhiro Aruga, Takuya Maeda

"In general, there is a strong correlation between dislocation characteristics and mechanical properties of aluminum alloys. In this study, dislocation characteristics of tensile deformed Al-Mg alloys were examined by transmission electron microscopy. An Increase in the solute concentration, ranging between 0.3 and 1.1%, Mg leads to increase in strength and decrease in uniform elongation. The accumulation of dislocations during the tensile deformation is observed in lower strain as the concentration of solute Mg in the alloy is higher. It is believed that the solute Mg in Al-Mg alloy promotes the accumulation of dislocation during the tensile deformation resulting in the decrease in elongation.INTRODUCTION The influences of the amount of Mg concentration on the tensile properties of Al-Mg alloys has been investigated by many researchers. It has been understood that the tensile ductility of Al-Mg alloy is higher for the Al-Mg alloys with higher Mg concentration beyond 2 mass% (Mukai, Higashi, Hirano & Tanimura, 1993). Uchida and Yoshida (1995) reported the formation of microbands during the tensile deformation due to the localization of dislocations, and the amount of microbands were reduced when the Mg concentration of the Al-Mg alloy was increased from 3 to 9 mass%. Their study suggested that the dynamic recovery of dislocation was retarded due to the increase of the Mg concentration during the tensile deformation, which resulted the increase in ductility. On the other hand, in the case of Al-Mg alloys with the Mg concentration less than 3 mass%, the reason why the ductility of Al-Mg alloys decreases with increasing Mg concentration has not been sufficiently investigated. In general, the Mg concentration used for automotive usage is less than 1 mass%, in the case of Al-Mg-Si alloys (Aoki, 2013). Therefore, to clarify the roles of Mg in the low concentration range on ductility of aluminum alloys and to elucidate its mechanism contribute to alloy design of Al-Mg-Si alloys having good formability."

Jan 1, 2018

By S. A. Lolon, J. F. Brune

"INTRODUCTION In underground longwall coal mining, the mined-out areas or gobs frequently contain methane which can form explosive methane-air mixtures. Historically, there have been many events of mine fires and explosions recorded in the United States and other countries that have demonstrated the existence of such explosive mixtures, herein referred to as Explosive Gas Zones (EGZs), inside and around the perimeter of bleeder-ventilated longwall gobs (Loane et al., 1975; Lynn et al., 1986; Elkins, et al., 2001; McKinney et al., 2001; Dziurzynski and Wasilewski, 2012; Brune, 2013). The risk of mine explosions can increase if the EGZs migrate out from the gob into the surrounding mine entries. Several factors can induce EGZs outflowing from the gob, but the most common cause is the fluctuating barometric pressure. Atmospheric pressures change regularly every day but can fluctuate abruptly and become increasingly hazardous in adverse weather conditions. Other sudden pressure changes can result from roof falls, failing ventilation controls and fan outages. Any such fluctuation of mine ventilation pressure will disturb the pressure differential between the gob and the surrounding mine workings and may cause EGZs to outgas from the gob. The correlation between major mine explosions and abrupt barometric pressure changes has been studied and confirmed for explosions in coal mining countries including the United States, South Africa, Australia, and Poland (Hosler, 1948; Boyer, 1964; Kissell et al., 1973; Fauconnier, 1992; Hemp, 1994; Wasilewski, 2014; Belle, 2014; and Lolon, 2017). Disastrous mine explosions appear to happen more frequently during stormy weather, which, in the United States, typically occurs during the late fall and winter seasons. ROOT CAUSE AND EFFECT OF GOB BREATHING Gob breathing is the result of the pressure differential between gob internal and external pressures caused by external atmospheric pressure fluctuations that occur naturally as a result of gravitational and thermal forces in the atmosphere (Lindzen and Chapman, 1969). Other major and sudden pressure changes may be caused by fan failures, failures of ventilation controls or roof falls can also cause an unexpected gob breathing. Normal barometric fluctuations occur every day but usually do not pose an explosion risk as they occur gradually so gob pressures have sufficient time to equilibrate. More extreme fluctuations associated with cyclonic weather systems and storms often result in more rapid and larger drops or rises in barometric pressure (Hosler, 1948; Fauconnier, 1992). A study by Lolon (2017) found that the timing of historical mine explosions showed consistency with the occurrence of abrupt and intense barometric variations."

Jan 1, 2018

By S. M. H. Haddad, M. Saghaeian, R. Hejazi

"Due to limited water resources in mineral processing plants, increasing the efficiency of iron tailing dewatering system in order to obtain more usable water is very important. In this research, flocculation process, as one of the best method for water recovery, was investigated by using one organic cationic and three anionic types of flocculants with different dosages (10, 20, 30 g/ton) and iron ore tailing slurry (8 % w/w solidity) in series of graduated cylinders and obtained results were compared. it is observed that for tailing sample, the anionic flocculants have a significant effect on the settling rate of solid particles compared to the cationic types. Furthermore, effects of temperature (10, 23 and 43 ºC) and pH (2, 7 and 12) on the rate of settlement and turbidity was studied by utilizing the best flocculant. Findings showed that by increasing the amount of flocculant dosage, sedimentation rate went up and turbidity decreased. Comparison the out-put data of tests indicated that at temperature 23 °C and pH=7, the best results for both of faster settling rate and producing more clear water were reached. It should be considered that lower temperature has a more negative effect on the sedimentation rate and overflow water quality. So it will be predicted that for cold seasons, the consumption of the flocculant powder would be higher than the moderate or warm seasons. Also, coagulation/flocculation was evaluated by applying organic cationic coagulant added to anionic flocculant in three different times. Different ratios of coagulant to flocculant was examined (70%:30%, 50%:50%, 30%:70%) as well. Overall, utilizing coagulant had desirable influence on sedimentation experiments and obtaining high quality water. 1- INTRODUCTION In mineral Factories, among the important processes, solid-liquid separation process due to limited resources of water is very important and operates on iron ore tailing in settling tank as thickener in order to gain clear water for preventing water loss and applying again in plant units (Ciftci and Serhat Isik, 2017). Iron ore tailing include inharmonious compounds of iron oxides, silicates and aluminum-silicates. The percentage of solid in the tailing usually changes between 5 and 10 percent (Dash et al., 2011). One of the major problem about dewatering of tailing in thickener is solid-liquid separation of slurries with high stability because of fine particles. It means that rate of sedimentation is very slow and recovered water quality is inappropriate. This issue can be solved to a large extent by factors such as pH control, ionic strength and flocculation/coagulation process which results in aggregation of particles so that settlement by gravity is happened (Dash et al., 2011)."

Jan 1, 2018

By Junto Nishiwaki, Shinji Kumai

"Mechanical and physical properties of the impact welded dissimilar metal joints are controlled by joint interface morphology. An intermediate layer (IML) is often formed at the joint interface and this deteriorates the interface quality in some metal combinations. Numerical and experimental studies were performed in order to examine the formation mechanism of the wavy interface and intermediate layer for explosive welded Al/Cu dissimilar metal joints. The impact welding process consists of (1) high-speed oblique collision of metal plates, (2) metal jet emission and large deformation and temperature increase at collision point and (3) rapid cooling at the joint interface. Euler-Lagrange coupling method, smooth particle hydrodynamic (SPH) method and modified laplacianFoam (LF) method were linked together to simulate a series of processes from (1) to (3), and the final interface morphology including the formation of IML was reproduced. The wavy morphology (wave-height, wavelength) and the position and composition of IML formed at the joint interface of Al/Cu joints were quantitatively in good agreement with those reproduced by numerical analysis. Our simulation results are useful for the control of the interface morphology, reduction of the amount of IML, and improvement of the mechanical properties of the impact welded dissimilar metal joints.INTRODUCTIONImpact welding is a kind of solid state joining method providing extremely high joint strength for both similar-and dissimilar metal combinations. Explosive welding and magnetic pulse welding are representative methods to achieve the impact welding. By a high-speed oblique collision between two metal plates, a metal jet is emitted from the collision point. The metal jet can remove any oxide films and contaminations on the plates and produce an active refreshed surface. Consequently, good metallurgical bonding can be achieved even for dissimilar metals (Crossland, 1982). Solid metals deform like fluids under the high pressure condition at the collision point and characteristic wavy interface is formed. In addition to the wavy interface, an intermediate layer (IML) is often formed at the joint interface in some metal combinations. Elimination or reduction of the amount of IML at the joint interface is desired since the excessive IML formation along the joint interface causes a large reduction in physical and mechanical properties. Formation of IML is considered to result from characteristic thermal history at the joint interface including partial melting due to the local temperature increase and successive rapid cooling behavior at the joint interface. In order to control the IML formation at the joint interface, it is necessary to reveal both heating and cooling processes at the joint interface. However, it is impossible to observe the phenomenon occurring at the joint interface and also difficult to investigate the temperature change at the joint interface directly during the impact welding. Therefore, simulation or numerical analysis is indispensable to overcome this problem. In the present study, the explosive welded Al/Cu joint, which is prone to form IML at the joint interface, was selected for the research. By using a newly developed numerical analysis method, not only the formation process of wavy interface, but also the local temperature increase and successive temperature decrease at the joint interface were reproduced. The formation process of IML was investigated by using both numerical analytic and experimental results."

Jan 1, 2018

By J. B. Boisvert, D. S. Silva

"Drillhole placement involves benefits, costs, and constraints. Benefits are related to the drilling campaign value, which includes maximizing “indicated” and “measured” resources. Costs include drilling, rig movement, and access construction. Constraints include infeasible areas, maximum and minimum angles of drilling, maximum depth of drilling, and budget. Manually planning drillholes that meet these constraints is suboptimal. A framework for straight drillhole optimization that accounts for benefits, costs, and constraints is presented. The method aims to maximize the value of resources converted from “inferred” to indicated and measured. The framework is demonstrated for a Nevada gold deposit and outperforms manually selected drillholes.RÉSUMÉ Le choix de l’emplacement d’un trou de forage s’accompagne d’avantages, de coûts et de contraintes. Les avantages sont liés à la valeur d’une campagne de forage, qui comprend l’optimisation des ressources « indiquées » et « mesurées ». Les coûts englobent le forage, le déplacement de l’appareil de forage et la construction des routes d’accès. Quant aux contraintes, elles portent sur les zones impraticables, les angles maximums et minimums de forage, la profondeur maximale de forage ainsi que le budget. La planification manuelle des trous de forage répondant à ces contraintes est sous-optimale. Cet article présente un cadre relatif à l’optimisation des trous verticaux de forage tenant compte des avantages, des coûts et des contraintes. Cette méthode vise à optimiser la valeur des ressources converties de la phase « ressources présumées » à celle de « ressources indiquées et mesurées ». Ce cadre est appliqué à un gisement aurifère du Nevada et donne de meilleurs résultats que les trous de forage sélectionnés manuellement. INTRODUCTIONDetermining the optimum location of infill drilling has been studied because the high cost of drilling suggests that using fewer drillholes is preferred, and targeting locations of the deposit that are locally uncertain should result in better mine planning decisions and increased profit of the operation. Existing methods for optimizing drillhole locations consider minimizing the kriging variance (KV) as the objective and are mostly restricted to two dimensions (Soltani-Mohammadi & Hezarkhari, 2013a, b; Soltani- Mohammadi, Safa, & Mokhtari, 2016)."

Jan 1, 2018

By Sastry Putcha, Vamshi Vemula, Aneesh Goly, Kumar Allady

Current dynamic testing practice to obtain pile total capacity will not yield optimum capacity due to the strain incompatibility between the side and tip resistances during driving. Superposition of end of initial drive- static tip capacity and the peak static skin capacity during beginning of restrike and adding them is the preferred method. The FDOT method determines independent pile static tip and skin capacities in real time analyzing appropriate blows from the embedded tip and top data of the Embedded Data Collectors (EDC). This data is collected through a wireless radio transmitter, receiver, and laptop software. The approach utilizes EDC tip and top data and nonlinear single degree of freedom system to satisfy force and energy equilibrium with a global genetic inversion analysis. Top impacted energy equals at pile tip as sum of Static, Damping and Inertial energy providing independent tip resistance. With EDC sensors as boundary conditions, pile is divided into desired segments and using global inversion techniques one dimensional equation is solved for independent skin friction for every blow. EDC data compared close static load test results. The EDC - FDOT method has enabled cost effective 100% testing of driven piles cost effective. INTRODUCTION Historical documentation has shown that not only driven piles have a long history of usage but also continues to advance unceasingly till today. Historians placed the first pile driving using timber piles in the 4th century BC. While modern pile driving systematically started around nineteenth century, the credit for conceiving the idea of the applicability of wave equation to driven piles goes to David Victor Isaccs of Australia. His 1931publication “Concrete Pile Driving Formulae” provides the basis for modern pile driving using stress wave theory. He felt that the dynamic formulae then in use lacked the capability of detecting integrity and hence developed stress wave theory. This work was further developed starting in 1938 by W.H. Glanville and colleagues of British Building Research Board as they developed the first solution to the wave equation. But these early efforts have really taken off only with the advent of computers. E.A.L. Smith (1960) published ‘Pile Driving Analysis with the Wave Equation’ and provided first numerical solution to the wave equation. Within few years, the FHWA funded research and in due course this effort ushered the era of externally instrumented pile driving.

Jan 1, 2018

By O. A. Velasquez, A. R. Kumar

"Dust generated on underground mechanized coal mining faces is a health and safety hazard. Continuous miners deployed underground usually have an integrated flooded-bed dust scrubber mounted onto the machine that arrests the generated dust from close to the face and cleanses the air around it. However, the impingement screen might get clogged depending on the coal seam being worked. This necessitates the cleaning of the screen which in turn, reduces the overall availability of the scrubber and, hence the continuous miner. A novel non-clogging screen has been developed at the Department of Mining Engineering, University of Kentucky. The proposed impingement screen is built up of three individual aluminum screen units 1.5 mm thick and separated by 3 and 2 mm respectively. The screens have long vertical slits measuring 6 mm. A water spray continuously keeps the screen wet and provides for the filter element to arrest the dust particles. The slits force the dust-laden air to make sharp turns. The dust particles cannot change directions rapidly, impact one of the three screens and are separated out based on their momentum. Preliminary computational fluid dynamics (CFD) models have indicated significant cleaning efficiencies in the respirable range at the expense of much lower pressure drops. Results indicated by CFD models and supported by laboratory experiments have been discussed in this paper.ACKNOWLEDGEMENT The authors acknowledge the National Institute for Occupational Safety and Health (NIOSH) for funding this research. Dr. Thomas Novak, Professor of Mining Engineering, is also acknowledged for his continued support and encouragement. INTRODUCTION Continuous miners are ubiquitous in coal mining around the world. The miners are operated against bling headings, ensuring adequate flow of air at the face could be difficult. The minimum requirement of ventilation airflow quantities at those coal faces are legislated to dilute dust generated to harmless levels. New dust rules promulgated recently have further called for lower exposure levels of personnel working underground (Courtney) (MSHA, 2014) (NIOSH, 2010). Water sprays are also installed at strategic locations and serve as powerful air-movers. The sprays capture some amount of dust generated while cutting. In addition to this, usually, all continuous miners are equipped with a flooded-bed dust scrubber as shown in Figure 1 to capture the dust from close to the extraction drum (Chao & De-sheng, 2000) (Wala, Vytla, Huang, & Taylor, 2008) (Organiscak & Beck, 2010)."

Jan 1, 2018

By B. Skrotzki, E. Augenstein, C. Rockenhäuser

"The aluminium alloy 2618A is an Al-Cu-Mg alloy with additions of Fe and Ni, which is designed for long-term operation at elevated temperature in transportation and aerospace industries. The alloy degrades due to coarsening and dissolution of GPB zones and coarsening of S-Phase precipitates (Al2CuMg). This work investigates the overageing process at the application relevant temperatures of 190 °C for durations ranging up to 25,000 h. The nm-sized precipitates were selectively imaged along the <001>a direction of the Al matrix using dark-field transmission electron microscopy. The resulting images were then evaluated and allow the statistically relevant determination of radii distributions and the average radius of the precipitates dependent on temperature and heat treatment duration. Ostwald ripening of the S-phase does not describe the ageing process adequately. Instead, the evolution of GPB zones during the initial ageing regime needs to be considered in addition to the coarsening process of the S-phase. DSC measurements were performed to determine the presence of GPB zones in different ageing states. This will allow a quantitative description of the ageing process and a comparison to samples aged under external load.INTRODUCTION Alloy 2618A is an Al-Cu-Mg alloy, which is part of the 2XXX series of aluminium alloys. It is used in aerospace and transportation industry due to its desirable material properties for long term operation at elevated temperatures (Polmear, 2006). Fe and Ni are added to form intermetallic compounds, which retain microstructural stability at elevated temperatures (Bergsma, Li, & Kassner, 1996; Elgallad, Shen, Zhang, & Chen, 2014; Oguocha, Yannacopoulos, & Jin, 1996; Wang & Yi, 2006). The size and distribution of the nm-sized S-phase formed from the supersaturated solid solution (SSSS) during heat treatments mainly controls the strength (Khan, Starink, & Yan, 2008; Liu, Zhang, Ding, Sun, & Chen, 2003; Parel, Wang, & Starink, 2010; Shih, Ho, & Huang, 1996; Wang, Starink, & Gao, 2006). The S-phase has the composition Al2CuMg and is orthorhombic under equilibrium conditions (Heying, Hoffmann, & Pottgen, 2005; Perlitz & Westgren, 1943). Early experiments proposed the following decomposition of the S-phase sequence during heat treatments (Hardy & Heal, 1954; Silcock, 1961):"

Jan 1, 2018

By G. P. Karmakar, K. K. Chandan

"The drilling mud is an essential part of the drilling process, which plays a major role in keeping safe and efficient oil and gas well drilling. In the oil industry, bentonite clay dissolved in water produces the simplest type of drilling muds. Bentonite clay contains montmorillonite particles. These particles are dispersed uniformly in water and such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds. The bentonite clay easily dissolves in water and increases the viscosity of the water, which is one of the most important properties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for building up of the viscosity of the clay-water system. The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil and gas well drilling process. The behavior of drilling mud greatly depends upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations. In this work, a comprehensive study has been carried out to find out the effect of added polyacrylamide (PAM) polymer, surfactant, pH and salt concentrations on the dispersion/ flocculation characteristics of bentonite clay-water system. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. The flocculation rate has also been found to be better under higher pH conditions. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.INTRODUCTIONIn the oil industry, bentonite clay dissolved in water produces simplest type of drilling muds. Bentonite clay containes montmorillonite particles. These particles are dispersed uniformly in water. Such dispersions are used in various industrial products like paints, ceramics, pesticides and drilling muds (Akther et al., 2007). The bentonite clay easily hydrates in water and increases the viscosity of the mud system (Razi et al., 2013; Meng et al., 2012). Bentonite clay in the drilling mud increases the viscosity which is one of the most important prop erties of a drilling mud. Bentonite has the highest swelling capacity, which is responsible for the building up viscosity of the clay-water system (Sonmez et al., 2013). The drilling mud is an essential part of the drilling process, which plays a major role in keeping a safe and efficient oil or gas well drilling (ASME, S. S. C., 2005). The flocculation behavior of bentonite is one of the major concerns for the performance of the water-based drilling mud in the oil or gas well drilling process. This behavior of drilling muds greatly depend upon the quality and quantity of bentonite clay, as well as the additives that are used in their formulations (Yu and Amanullah, 2005; Akther et al., 2007). Bentonite particles form aggregate under certain conditions including high temperature, and high concentration (Luckham and Rossi, 1999). If the quality of bentonite is not sufficient to accomplish intended viscosity of the muds, it is essential to add certain additives to increase the viscosity and prevent aggregation of the system (Razi et al., 2013). The anionic polymer bearing sample can build up inter-particle bonds between the polymer and clay particles. The addition of various additives like, polymers control the dispersion and enhance the viscosity of the mud by controlling the flocculation of montmorillonite particles in bentonite dispersion (Heller and Keren, 2002; Mahto and Sharma, 2004)."

Jan 1, 2018

By Tong Gao, Jingyu Qin, Xiangfa Liu, Zengqiang Li, Yaoxian Zhang

"The recycling of aluminum materials is a green industry while Al–Si–Fe is a typical scrap aluminum alloy. The key point of recycling Al–Si–Fe alloys is to separate Al and Fe. A method by introducing Al–Si–Fe alloy into Mg melt has been investigated in this work. A separation layer with gathered Fe–rich and Al–poor Fe3Al0.7Si0.3particleswereobtained at the bottom of the cooled ingot, indicating that ß–Al5FeSi phase evolves to Fe3Al0.7Si0.3,and quantities of Al are released to the upper Mg matrix simultaneously. However, the evolution of Al3Fe by adding binary Al–Fe alloy into Mg melt is different. It is supposed that element Si plays an important role in the phase evolution procedure, thus affects the performance of this method.INTRODUCTIONThe rapid development of aeronautic, automotive and aerospace technologies strongly depends on the consumption of materials while sustainable development is the future direction. Aluminum is a recyclable material and Fe is one of the most common impurities. Fe can be introduced into Al alloys by adding low–purity alloying materials and by using unprotected ferrous crucible, tools, or equipment (Belov, Eskin, & Avxentieva, 2005; Lu& Dahle, 2005).For instance, wear–resistant rings are usually inserted into piston head when producing Al–Si pistons and an infiltration procedure by putting the cast iron rings into Al melt before casting is always essential. As a result, both the re–melting of pistons and the reuse of Al melt for infiltrating rings lead to the enrichment of Fe element, which can be even high to5 wt.%(Viala, Peronnet, Barbeau, Bosselet, & Bouix, 2002).It is widely known that coarse ß–Al5FeSi particles will form in high Fe–contained Al–Si–Fe alloys which is harmful for the mechanical properties. In the past decades, several methods to eliminate the harmful effect of ß–Al5FeSi have been investigated which can be widely referred (Munson, 1967; Lee, Kawamura, Inoue, Cho, & Masumoto, 1997; Suárez–Peña& Asensio–Lozano, 2006; Eidhed, 2008).These methods can be divided into two kinds. One is to aggregate and remove the Fe–rich phase through the methods of centrifugation, gravity filtration or magnetic separation. The other way is modifing the morphology of flake–like ß–Al5FeSi by overheating the melt or adding neutralized elements. However, these traditional methods are rarely used due to respective disadvantages, while the commonly used method in industries is using primary aluminum for dilution. However, only less than 30wt.% of scrap Al can be added into primary Al melt for each melting work while it also results in the decrease of product quality simultaneously(Zhang, Liu, & Liu, 2016)."

Jan 1, 2018

By M. Somppi, Z. Yamak

"Gold producers invest significant effort in mining, processing, and creating an intermediate gold doré product. Nonetheless, equal effort should be extended to the final handling and processing of the doré bar, and managing the high-purity gold produced at the fine-gold toll refiner. This detailed attention to bullion handling and refining provides rigor and confidence that the mine site is achieving, through fair and controlled methodology, the most appropriate value for the final product. With the above in mind, the following study explores the importance of preparing a set of site best-practices for bullion handling and specifically, detailing the peculiarities of sampling methodologies and the impact on assays.INTRODUCTION Gold and silver handling practices are common place at mine sites and refineries. The practices include but are not limited to smelting, ingot casting, weighing practices, and secure transportation. Proper handling and processing of the bullion material ensures that the mine site is achieving the true value of the final product. Various handling aspects can critically impact the perceived value of the bullion. A few of these particulars include weight tracking, scale recertification and calibration, refining and melting practices, melt temperature measurement, sampling, pouring, bar cleaning, furnace technology and crucible selection, and assaying. Nevertheless, this report discusses and focuses on the importance of proper sampling and molten-metal temperature measurement and their potential impact on the final doré bar value. Refining or re-melting operations achieve a proper measure of the precious metal content of its bullion when the sample accurately represents the whole bar. At first this task appears seemly straightforward, however, taking a representative sample can be challenging and is also one of the most important tasks for valuing gold during the settlement stage at the precious metal refinery. Various bullion sampling methodologies exist; including: dip sampling, granulation, drilling, cutting, and vacuum pin sampling. The Royal Canadian Mint (2009) indicated in their technical review of refinery operations that pin sampling is one of the best methods for cases where representative sampling and accuracy are required, e.g. to determine the payable metal content. Pin sampling consists of inserting a sealed glass vacuum tube (Figure 1) into the molten metal; when the molten metal contacts a purposely-designed weak portion of the glass, the seal breaks and the metal is suctioned into the hollow centre (Figure 2)."

Jan 1, 2018