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By Andrukaitis. E.

The increasing use of electronic equipment by the Canadian Forces has increased the importance of electric power. A power source that is packed with energy and yet light, small and durable is the common request of military users. However, this needs to be achieved while also addressing the requirements of safety, reliability and low temperature performance. The potential use of fuel cells in a military environment has become a possibility in several areas in the 21st century. Some examples of power source requirements and the materials related R&D required to give better, higher energy power systems in the future will be discussed.

Jan 1, 2005

By G. V. Theja, V. B. Maji

Large infrastructure projects like tunnel excavations, underground constructions face innumerable risks. For successful completion of these projects, it is essential that we foresee and understand risks that could occur during different phases of the project. One of the risks affecting underground excavation projects is the inaccurate performance prediction of TBMs. As this could severely affect the project, resulting in lower advance rates and could also result in changing the excavation machine or method, due to difficulties in excavation, thereby increasing the overall cost of tunnelling. This makes performance prediction of the TBMs as one of the crucial aspects in tunnelling, as a precise estimation of its performance is required for planning and estimation of time and cost of the tunnelling projects. This performance prediction of TBM is a challenging geotechnical problem that is intricate and complex in nature, this is possibly due to the fact that TBM performance prediction involves understanding the rock fragmentation process in wide range from micro-scale (i.e. the interaction of surface of rock material and cutter tip) to macro-scale (including the interaction of rock mass and TBM). Thus in order for the performance prediction model to be efficient, parameters of both TBM specifications and ground conditions have to be considered. Various models have been proposed by researchers since the early phases of TBM application, these studies resulted in the development and improvement of numerous penetration prediction models. Most of these models consider the geotechnical parameters that are input to the model to be consistent along the TBM drive and neglect the uncertainties in parameters that occur. And so to improve the predictive capability of these models and to incorporate the above uncertainties, the penetration rate is modeled as a stochastic variable depending on the geotechnical and TBM parameters, its statistical distribution is determined and is used to characterize the penetration rate instead.

Jan 1, 2015

"This contribution is concerned with adaptive processing decisions, where the process parameters are optimally adapted to the varying properties of the material input stream. Our starting point is the geometallurgical paradigm that the varying properties of the input stream are considered known e.g. from a geometallurgical model of the mined ore body, and optimal processing parameters are computed from them, by finding the parameter seaming optimal in a computer simulation.This approach however has to work with a lot of uncertainties: The prediction of the geometallurgical ore parameters can only be done with some geostatistical uncertainty. The parameters themselves are only proxies for true ore properties. Model prediction can differ relevantly from actual process results, due to model simplifications. Due to these uncertainties the computed processing choices can turn out to be inferior to simple non-adaptive processing. In this contribution we focus on the uncertainty of the ore properties and analyse this effect systematically, by modelling this uncertainty effect mathematically and in computer simulations. The most important findings are:(a) Processing choices not taking into account the uncertainty sometimes even perform worse than simple non-adaptive processing, for the sole reason of ignoring the uncertainty effect.(b) Ore properties, not adequately reflected in the ore description, might require different approaches, in which the observed processing behaviour feeds back into process control.(c) Bayesian decision theory allows computing optimal processing choices combining the information from the mine (geostatistical predictions) and from the process feedback. These choices give much more robust choices and do not suffer from the drawbacks described for the simple approach we started from.These new approaches can substantially improve the performance of adaptive processing in existing plants."

Jan 1, 2016

By J. Y. Kim

This paper presents a novel action recognition method for observing human workers using interactions between actions and related objects on an internal construction site. This method can be used to measure work rates for labour productivity monitoring. This monitoring is critical because the performance of a construction project is significantly impacted by labour productivity. However, construction sites are generally crowded with a large number of workers and objects. Such congestion disrupts the accurate, automatic recognition of construction workers? actions. This congestion is one reason that existing automatic action recognition studies of construction areas mainly focus on workers? actions themselves. However, the crowded conditions mean that sites could offer a great deal of clues that could be used for automatic action recognition. According to psychological studies, interactions clearly take place between human actions and related objects, such as between hammering and a hammer. Humans use these interactions to recognize actions or objects more accurately. On the construction site, workers, materials, tools, and equipment are carefully planned out ahead of actual construction. The categories of workers and objects are pre-defined and, as noted, specific interactions define relations between worker actions and objects. In this paper, the interactions are limited to human workers and their hand-held objects. Action recognition results can be combined with hand-held object information to improve recognition accuracy. With the limited interactions, experiments in this paper show a significant improvement in action recognition. This paper describes the utilization of these interactions to improve construction action recognition accuracy based on human skeleton data and 2D color video from Microsoft KINECT sensor.

Aug 1, 2013

By J. L. Feng, F. Zhang, S. K. Hu

"Cracking is one of the most serious damages in tunnel linings, which is often observed by in-situ inspection to tunnel engineering. It is difficult to better characterise for the deformations from continua to discontinua by the traditional continuum mechanics due to emerging of crack initiation, crack propagation, and coalescence, at several scales. In this paper, the process of failure that was from micro damage to macro crack in concrete tunnel linings under experimental load conditions, was quantitatively simulated by the combined finite-discrete element method (FDEM). Comparison of the simulating results with that obtained by the full-scale test of concrete lining under different loading conditions in the literature was respectively good agreed and shows that such FDEM technique is appropriate to model the continuousdiscontinuous problems. The present study indicates that the FDEM technique could be benefit to quantitatively evaluate the stability and damage level of tunnel lining system. INTRODUCTIONMost damage to tunnel linings is caused during the construction phase, which can emerge in a form of single macro cracks or even large-scale spalling. The cause of such damage is mostly the occurrence of, either impermissibly large contact stresses resulting from high thrust loads combined with production and installation tolerances in the segments resulting in a geometrical lack of fit (Maidl et al., 2012; Transportation Research Board, Basic Research and Emerging Technologies Related to Concrete Committee, 2006), or unallowable tensile/shear stresses appearing in the tunnel linings under complicated loading conditions (Ansell, 2010). Such a macro failure phenomenon may also be regarded to as a result of growth, coalescence, initiation of microcracks in tunnel linings due to the complicated loading action, and even potentially lead to an instability or collapse of the local or entire tunnel system. Much work has been devoted to investigate for the characters of micro and macro cracks, the influence factors of damage patterns, the settlement of a tunnel, the width, length and density of lining cracks, especially from classifiedly and qualitatively (Wang, 2010; Huang et al., 2013). However, the safety evaluation of tunnel is definitely required to not only inspect in situ, but further also quantify computing and analyzing for tunnel lining systems, so as to provide a global viewpoint of process of the tunnel deformation, which aims to help for subsequent decisions, e.g. controlling traffic flow or immediately repairing task. Additionally, the design of lining thickness and its structural analysis that is mostly determined by previous experience and similar construction examples is also needed to be improved."

Jan 1, 2015

By K. Morin, C. -Y. Hon, G. Lachapelle

"Air-sampling results suggest drill operators working inside environmental drilling cabs at an open-pit gold mine in Nunavut, Canada, are at risk of exposure to asbestos and silica (quartz). The authors installed RESPA® CF Vortex HyperFLOW® units, which showed promising results under laboratory conditions. The goal was to evaluate the effectiveness of these units under actual working conditions. Personal and area air sampling was conducted in drilling cabs with and without the unit and a Wilcoxon rank-sum test was performed to compare the results. Particulate concentrations were significantly lower in drill cabs with a unit installed than in those without.RÉSUMÉ Selon les résultats d’une campagne d’échantillonnage de l’air, les foreurs travaillant dans des cabines de forage environnemental dans une mine d’or à ciel ouvert du Nunavut, au Canada, risquent d’être exposés à l’amiante et la silice (sous forme de quartz). Les auteurs ont installé des unités RESPA® CF Vortex HyperFLOW®, lesquelles of frent des résultats prometteurs en laboratoire. L’objectif est d’évaluer l’efficacité de ces unités dans des conditions de travail réelles. Des échantillons de l’air inhalé par le personnel et dans les aires de travail ont été évalués dans des cabines de foreuses équipées ou non de cette unité ; un test de Wilcoxon (également appelé test de la somme des rangs de Wilcoxon) a été mené afin de comparer les résultats. Les concentrations particulaires étaient considérablement plus faibles dans les cabines de foreuses équipées d’une unité que dans celles en étant dépourvues.INTRODUCTIONGenerally, mining operations are associated with a variety of occupational hazards. In an open-pit gold mine in Nunavut, Canada, drill operators are routinely exposed to asbestos (primarily amosite) and silica (quartz)—two naturally occurring substances in the ore that is to be drilled (Table 1). Inhalation is the primary route of exposure for these two hazards, which are associated with respiratory health effects such as asbestosis and silicosis, respectively. In addition, asbestos and silica are classified as human carcinogens by the International Agency for Research in Cancer (2001, 2011). Given the toxicity of these two agents, it is imperative that precautions be taken to minimize the risk of exposure of the mine’s workforce. To address this matter, the mine has an exposure-control plan, which includes the provision of personal protective equipment, personal hygiene facilities, training, and a medical surveillance program. Furthermore, the mine performs occupational exposure assessments or air sampling on a regular basis because the morphology of the ore changes rapidly with respect to asbestos and silica content."

Jan 1, 2017

By X. -G. Chen, E. M. Elgallad

Direct chill (DC) cast ingot plates of 2xxx alloys have been increasingly used for large mold applications in the plastics and automotive industries. A novel heat treatment practice for Al-3%Cu-1%Mg DC cast ingot plates has been developed, involving solution treatment, furnace cooling to the desired aging temperature and holding for appropriate time at the aging temperature. The mechanical properties of the plates were studied for different combinations of aging temperature and time, using hardness measurements and tensile testing. The evolution of the strengthening precipitates was investigated under different cooling rates corresponding to cold water quenching, still-air cooling and furnace cooling, using electrical conductivity measurements. The results showed that by applying the novel heat treatment, the cast ingot plates could provide a wide range of combinations of strength and ductility satisfying the design specifications of large molds. This, in turn, offers a practical solution for the fabrication of extremely large DC cast plates combining between good mechanical properties and low levels of residual stress using the shortest possible heat treating cycle.

Jan 1, 2015

By G. O. Crowell

This paper gives the history of the celestite deposit, now being mined by Kaiser Celestite Mining Ltd., near Sydney, Nova Scotia. Mining and milling procedures are covered, and the regional and local geology of the area are described, including the origin of the celestite.

Jan 1, 1971

By A. Bezama

For over a decade European countries have addressed contaminated sites by developing technologies for managing both polluted soil and groundwater. This development has not only been driven by health and environmental aspects, but also because of economic pressures, as the remediation and redevelopment of derelict areas can be a meaningful alternative to undeveloped areas for the establishment of new industrial, recreational, housing and service locations. In most developing countries, however, the subject of contaminated sites is a new environmental issue that authorities have recently started to deal with. Among these countries, Chile has just started to prepare the country's legal context as well as to foster the formation of research and investigation groups that will deal with the exploration, investigation and management of contaminated sites. That requires a comprehensive technical, scientific and legal support in this stage. Goal of this article is to present the state-of-the-art technologies for site remediation currently applied in industrialized countries, in order to identify the most interesting approaches that can be implemented within the Chilean situation, especially considering the influence of the copper mining industry on the soil and groundwater quality of the environment surrounding their production facilities.

Jan 1, 2007

By A. H. Duffield

"Forming part of the Prairie Evaporites, the sylvinite layer mined at Alwinsal underlies the Blairmore quicksands and the water-bearing Devonian formations. Production is achieved by a method of trackless, continuous mining of rooms, leaving pillars for natural support. The paper describes the development of the mine, and the equipment and organization employed in the operation and maintenance of the underground facilities."

Jan 1, 1972

By S. Manning, W. Morris

Mineral exploration assessment file information has long been considered a useful resource for developing mineral exploration strategies, and one of the most common data sets fled in assessment reports is ground magnetic surveys. The new Earth Resources and Land Information System database (ERLIS) now provides a method for rapidly accessing all references to a specific area through a series of raster images. The ERLIS provides access to the Assessment File Research Imaging (AFRI) database which comprises geo-science mineral exploration assessment file data, Mineral Deposits Inventory (MDI), together with provincial aeromagnetic data from the Ontario Ministry of Northern Development and Mines(MNDM). Conversion of the raster images of ground geophysical data to vector data files together with the concatenation of grids from adjacent claims provides a method for constructing high resolution magnetic regional images. The value of this resource is demonstrated through the construction of a single composite magnetic image derived from eight assessment file grids for an area south of Kirkland Lake, Ontario, within Pacaud and Catharine Townships. The composite grid of magnetic data provides a map with resolution that is not achieved by currently available Ontario Geological Survey airborne data sets. Details contained within the new high resolution image, permit the differentiation of lithologies and their boundaries, fault orientations and the location of alteration zones with magnetic response.

Jan 1, 1997

By L. Xia, B. Hart, J. Nigim, Z. Chen

"Grinding ore is an important step in the flotation process. Not only does grinding reduce particle size and liberate minerals, it also creates conditions for reactions to occur on particle surfaces that can aide or inhibit flotation. There have been numerous studies examining various grinding regiments and the effect on flotation pulp chemistry, including autogenous grinding and using media of variable composition. There have been however, few studies looking at the effect of variability in grinding media size on pulp chemistry and subsequent flotation. This study attempts to link changes in pulp chemistry in response to variations in grinding media size to flotation recovery. It uses probes mounted in the grinding chamber (pH, Eh, DO, and conductivity) to monitor pulp chemistry changes during grinding of a Cu-Zn ore. Surface chemistry analysis by ToF-SIMS was performed on sphalerite from the mill discharge. Activator and depressant species were monitored on the mineral surfaces and their presence was evaluated in the context of variability in pulp chemistry linked to differences in grinding media and its ball size.INTRODUCTIONIt has been widely recognised that not only does grinding reduce particle size and liberate minerals but the grinding environment has a large effect on the flotation of sulphide minerals. This effect is attributed to Eh change, iron hydroxide coating on surfaces, oxygen reduction, precipitation from solution and galvanic coupling (Grano, 2009). As early as 1960, it was reported that after grinding the ores in an iron mill the natural floatability of sphalerite was reduced significantly (Rey and Formanek, 1960). Kocabag and Smith (1985) studied on the industrial circuits showing that the depression of sulphides flotation in a steel mill is possibly due to the coating of iron oxidation products. Peng, Grano, Fornasiero, and Ralston (2003a, 2003b) found that iron contamination from grinding media plays a dominant role in depressing galena and chalcopyrite flotation. Huang, Grano, and Skinner (2006) reported the same observation in the flotation of arsenopyrite."

Jan 1, 2016

"The asbestos mining industry in the Eastern Townships of Quebec has early recognized the undesirable side-effects associated with mineral production, such as air pollution, noise and unsightly waste dumps. In order to efficiently achieve the industry's aim of eliminating or minimizing these objectionable features of mining, all of the asbestos producers in Quebec interchange information, knowledge and design dealing with the environmental control measures through the Environmental Committee of the Quebec Asbestos Mining Association.The paper describes what has been done and what is planned for the future in the various problem areas, such as control of dust emitted during the open-pit drilling operation, control of dryer stack emissions, control of the environment in ore, fibre and tailings handling operations, rehabilitation of the countryside covered by waste dumps, and many others."

Jan 1, 1971

By J. W. Rogers, S. K. Schwartz

"The Cape Breton Development Corporation (CBDC) is a federal Crown corporation which operates two coal mines (Phalen and Prince Collieries), a coal preparation plant, a railway, a central workshop and a deep water shipping facility.The Sydney coal field consists of 11 major seams, which range from 0.8 m to over 3.7 m in thickness. Of the 2.4 billion tonnes of known coal resources in the field, approximately 550 million tonnes can be mined with present mining technology. These parameters define reserves which extend more than 8 km beneath the ocean to a depth of 1200 m. With today’s design and present high production faces, the colliery life is projected at approximately 20 years."

Jan 1, 1996

By X. -P. Zhang, L. N. Y. Wong

Shale gas exploitation initiated in North America has rapidly extended worldwide. Hydraulic fracturing is an emerging field technique for stimulating the gas reservoir. The study of cracking processes, particularly crack coalescence, is vital for a successful hydraulic fracturing to enhance the gas exploitation. Experimental studies have observed that the size effects of the constituent particles are significant on the cracking behavior of the rock specimens. To further investigate the size effects, the bonded-particle model (BPM), which is based on the discrete element method (DEM), is adopted in the present research. In flaw-containing specimens, by varying the crack resolution (?= a/2R), which is the ratio of half flaw length (a) to particle size (2R), the size effects on cracking behavior under compressive loading are studied. By keeping the flaw length constant, the particle size is varied independently in the BPM analysis. Decreasing the crack resolution increases the first crack initiation stress, but it has no obvious effects on the uniaxial compressive strength. The trajectories of the first cracks and secondary cracks hence generated have a higher resolution and are well-defined in those specimens possessing a higher crack resolution. On the contrary, in lower crack resolution specimens, the macroscopic first cracks appear to be wider and less continuous. These findings from numerical simulation clearly demonstrate particle size effects on cracking behavior. Special attention should be paid to these effects in future numerical study using the bonded particle model.

Jan 1, 2015

By M. Ghamgosar, Erarslan N.

Rock cutting includes many unknown parameters which result in different consequences of the different cutting conditions. However, based on the current suggested models for rock cutting, there are some critical parameters that control the fracture initiation and propagation in the rock domain. In general, there are two major cutting tools are used in rock cutting: drag bits and indenters. Different mechanical attacks of cutters result in different fracture models. For example drag bits break the rock parallel to the rock surface, which is called ‘undercutting’ while indenters cut rocks by pressing normal to the rock surface. Both tools cause rock failure by inducing tensile cracks in the rock. However, drag bits induce more tensile cracks compared with the indenters. The full benefits of improvement in rock cutting efficiency will arise from a clear understanding of rock fracture mechanics principles. Therefore, fracture mechanics principles will be applied to the rock cutting as the rock fragmentation process is based on the rock fracturing. The Oscillating Disc Cutting (ODC) has more advantages than drag bits and disc cutters. The forces transmitted back through the cutting head are much lower with ODC. Although ODC attacks rock in much the same way as drag bits, a combination of the oscillating action of the cutter and the undercutting mode produces the lower cutting forces and causes rock fatigue. Fatigue phenomenon in rock has advantages for the rock breaking by applying less effort and energy due to the cyclic loading. The aim of this study is using the Extended Finite Elements Analyses (XEFM) numerical modelling for simulating the ODC cutting with different cyclic loading conditions. An accurate prediction of numerical investigation requires detail laboratory experiments. A series of laboratory tests were performed to obtain the fracture toughness values of our Monsonite rock samples under various cyclic amplitude and frequency values. The numerical results showed different types fatigue damage mechanisms due to the various cyclic loading conditions. Thus, modelling and understanding the crack propagation behaviour depending on different amplitude and frequencies are believed very important for the dynamic rock cutting researches and rock cutting machine manufacturers.

Jan 1, 2015

By Eurípides do Amaral Vargas Jr., J. A. de Mello Franco

"It is frequently necessary to excavate a tunnel for Civil Engineering purposes, or wells for petroleum exploitation, in laminated rock mass like schists or phyllites or in highly foliated gneisses. The determination of the pre-existing in situ stresses is essential, in order to assure the stability of these excavations. In most cases, the pre-existing triaxial stress field is arbitrary in relation to the tunnel or well axis. For these rock masses the concept of Generalised Plane Strain can be correctly utilized.There are closed form solutions for the calculation of stresses in anisotropic rock masses under Generalised Plane Strain conditions (Lehknitskii, 1981 and Hong , 1994). Based on these analytical solutions, established for the cases of Generalised Plane Strain, a synthetic problem will be formulated: the theoretical in situ stress tensor acting on this rock mass will be determined, with the aid of Bayesian Inverse Problem Techniques, as developed by de Mello Franco (2009). Additionally, the reliability of results obtained will be evaluated, in accordance with the research performed by this author. INTRODUCTIONThe Inverse Problem Technique, as developed in the paper, is based on the definitions and concepts obtained from the current literature and used for the solution of Inverse Problems, but the innovation to be presented is the utilisation of Bayesian Techniques and the determination of the reliability of the results obtained. This will be shown in a synthetic example where the determination of the in situ stress tensor, from strain measurements in a drill hole is supposedly performed. It is assumed that this drill has its axis arbitrarily placed in relation to the rock mass. Generalised Plane Strain conditions will hold for use with problem. The equations of Beltrami – Mitchel, in agreement to Lekhnitskii (1981) and Ong (1994), will be used in this synthetic case, for calculating strains, hypothetically measured in the hole before the final excavations. Finally a synthetic example for the determination of the in situ stress in a fully anisotropic rock mass, based on Bayesian Techniques and its reliability, developed in de Mello Franco (2009) is presented."

Jan 1, 2015

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimizing the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give account of the uranium processing optimization journey embarked on over the years; namely, the operational trade-offs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper.

Jan 1, 2020

By S. Kashani Nejad, M. Bellino, K. Collins, C. Tovee, J. Godwin

Motivated by safety considerations, logistical issues, transportation cost savings, product diversification, and marketing preferences, several uranium producers are revisiting their business models and supply chain configuration and, instead of selling dried yellowcake to downstream refineries, they are moving to build in-house calcining facilities. Drying and calcining plants are relatively low-cost facilities to build and operate. The execution period of a typical yellowcake drying and calcining project is also relatively short and alternative construction methodologies, such as modularized solutions, are available. The drying and calcining technologies used for yellowcake are relatively mature, environmentally contained, and well supported by qualified vendors. The drying and calcining circuits also seamlessly integrate with upstream and downstream operations. These either produce a dried yellowcake or calcined U3O8 which are notably safer and easier to transport and market. This paper presents an overview of the recommended technology and project development considerations for yellowcake drying and calcining facilities.

Jan 1, 2020

By J. J. Brummer

The possibility of diamonds occurring in Canada was first raised by W. H. Hobbs in 1899, who concluded: "that the apex of the fan of diamond distribution probably lies somewhere in the strip of the territory bordering James Bay on the east." This was based on the occurrence of diamonds in surficial sediments at various locations south of the Great Lakes. There are two recorded discoveries of drift diamonds in Ontario: (a) the Peterborough Diamond, 33 carats in size, poorly documented and found sometime before 1920;and (b) the Jarvi Diamond, 0.255 carat, found during 1971 in Sheraton Township near Timmins . Both discoveries were in surficial sediments and their source(s) have not been located. During 1960, Selco Exploration Company Ltd. started a heavy-mineral sample program of river gravels in the James Bay Lowlands of Ontario. This was continued by Canadian Rock Company Ltd. (1962-1963) and the Ontario Division of Mines (1973). The surveys discovered the presence of kimberlite minerals in gravel samples from streams draining the Moose River Basin. A total of 53 pyrope grains, four magnesian ilmenites and one grain of chrome diopside were identified from 32 sample locations. A study of the distribution of these minerals suggested the kimberlite source rocks to be located along the north margin or within the Kapuskasing gravity "high" in the area immediately south of James Bay. The Jarvi Diamond, found on an esker east of Timmins, could well have originated from this area. During 1965, an esker was sampled by the Geological Survey of Canada, and the results attracted attention to the area south of Lake Abitibi. At 9 out of 34 sites sampled along the Munro esker, Lee recorded the presence of pyrope garnets and very minor chrome diopside.

Jan 1, 1978