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By Zhiqing Zhang, Changyun Chen, Qing Liu, Lin Lin, Zhihong Jia, Guangjie Huang, Lipeng Ding

The effect of interrupted quenching (IQ) treatments on natural aging and bake hardening response of Al-Mg-Si alloy was investigated by hardness measurements, tensile test, differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The results show that interrupted quenching at 100oC could effectively suppress natural aging and improve bake hardening response. The optimized interrupted quenching treatment is 100oC for 45min, which gives the alloy a relatively low T4 temper strength and higher bake hardening response. The formation of highly dense cluster(2) during the interrupted quenching could be the reason for suppressing the natural aging and accelerating the precipitation of ß? phase during the paint bake treatment. In addition, interrupted quenching at higher temperature (170oC) results in unfavorable properties in both T4 temper and paint bake treatment. The formation of large precipitates is responsible for these undesired effects.

Jan 1, 2015

By E. E. Mason

THE Myrtle group of mining claims is situated on Barkerville mountain in the Cariboo mining district of British Columbia, west of the old mining town of Barkerville. An 1,800-foot adit, known as the Shamrock tunnel, was driven in 1935-36 from the Barkerville road and in the general direction of the Myrtle group. It was proposed to enlarge this adit to more convenient section, extend it 2,500 feet int0 Myrtle ground, and from there drive a main entry 3,000 feet along the length of the group. Several laterals were also to be driven off this main entry as part of the tunnel schedule. It was thus originally proposed to drive 5,500 feet of new adit and 1,800 feet of laterals, a total of 7,300 feet of new work. Work was commenced with a bulldozer on April 21st, 1941, cutting a bench on the hillside for a plant site. The power plant was ready for operation on August 8th. Slashing and re-timbering of the old adit rook longer than was expected. It was found that 57 per cent of the length required timbering, chiefly by fore-poling, and there was also trouble in several sections with swelling ground. First round in the new face was taken on September 17th, when a 2-shift daily schedule was commenced. Due to delays in delivery of electrical equipment, it was not possible to add the third shift until November 14th. From then on, a 3-shift daily schedule was maintained with the exception of holidays and fortnightly change Sundays until August 1st, 1942, when shortage of labour caused the dropping of a shift. All work was suspended on August 14th. The ground through which the tunnel passed was such that the driving was often interrupted by the need of protective timber at the face. Further, crews were continuously employed timbering behind the face, and in maintenance of timbered sections in swelling ground. Roughly 980 feet of the new workings are now timbered, about 21 per cent of the total.

Jan 1, 1942

By Robert F. Shurtz

This paper discusses and compares methods of statistical analysis of the information relating to the evaluation of an asbestos deposit. From a study of 10-ft. lengths of drill core, the separate effects of visual evaluation errors were determined, as well as the deviations between evaluators and the deviations produced by a slight displacement in the center lines of the check drill holes. The importance of careful statistical analysis of such information is stressed.

Jan 1, 1966

By R. D. Westervelt

IN JULY 1954, the first iron ore from the deposits in the Knob Lake vicinity was mined and shipped to Seven Islands. The beginning of the production may well be the greatest advance in Canadian economy in the past fifty years. In 1955, the Canadian iron ore output was more than twice that of 1954, an in-crease due principally to the iron ore shipments from the Knob Lake area. Previous to this, Canada's iron production was 1.85 per cent of the world's output. Now, this percentage has risen to approximately 5.5 per cent and shows every indication of increasing further as the production rate from the area is increased. In 1955 the Iron Ore Company of Canada shipped over 7 million tons of iron ore and expects to ship over 10 million tons in 1956. Present facilities may be enlarged to handle up to 20 million tons per year. If the expected I 0 million tons per year are exported, Canada's iron exports will be second only to her wheat and newsprint exports. Before production began from the Knob Lake deposits, years of development were necessary in the area. Geologists spent several summers mapping the general area in order to unravel the complicated stratigraphy and petrology. Particular attention was paid to the mapping of the iron formation and all stages of alteration from fresh iron formation to ore were observed.

Jan 1, 1957

By N. A. Beier, N. Slingerland

"Oil sands tailings impoundments rank among the largest (spatially) in the world, covering a total of approximately 220 km2 of northern Alberta, Canada. A preliminary geomorphic design for an oil sands tailings storage facility (TSF) landform was completed with the goal of eventual closure and delicensing in mind. This paper outlines methods identified during the design process that streamline closure when implemented early in the mine planning and TSF design stages. With most oil sands TSFs currently in active operation (and some still in the planning stages), geotechnical engineers and mine planners have the opportunity to make operational and design decisions, such as those outlined herein, that are likely to improve the geotechnical and environmental performance of the landform post closure. ¦ KEYWORDS Alberta, Athabasca oil sands (AOS), Landform design, Reclamation, Sand dam, Tailings storage facility (TSF) RÉSUMÉ Les bassins d’accumulation des résidus issus des sables bitumineux font partie des plus grands (en termes d’espace) au monde, et couvrent au total environ 220 km2 dans le nord de l’Alberta, au Canada. Une conception géomorphologique préliminaire a été réalisée pour le modelé d’une installa¬tion de stockage des résidus (ISR) issus des sables bitumineux en gardant à l’esprit la fermeture et le retrait de permis à terme. Cet article présente les méthodes identifiées pendant le processus de conception qui simplifient la fermeture lorsqu’elles sont mises en oeuvre dès les premières étapes de planification de la mine et de conception de l’ISR. La plupart des ISR issus des sables bitumineux se trouvent dans des exploitations actives (dont certaines en sont encore aux étapes de planification), aussi les ingénieurs géo¬techniques et les planificateurs miniers ont la possibilité de prendre des décisions en termes d’exploita¬tion et de conception, telles que celles présentées ici, qui pourraient améliorer la performance géotechnique et environnementale de la phase suivant la fermeture du modelé. ¦ MOTS CLÉS Alberta, assainissement, barrage de sable, conception du modelé, installation de stockage des résidus (ISR), sables bitumineux de l’Athabasca (SBA)INTRODUCTION The Athabasca oil sands (AOS) underlie 140,200 km2 of land in northeastern Alberta, Canada. Oil sands located within 100 m of the original surface account for 4,800 km2 of the total area and are considered to be economically mineable (Figure 1; ERCB, 2009). Bitumen, the thick, tar-like substance contained in the AOS, is extracted through open-pit mining and in-situ methods. During mining, the overburden is first removed as waste and the sandy, bitumi¬nous ore (“oil sand”) is transported to processing facilities via conveyor belts and 400 t trucks. Warm and hot water, as well as process aides such as caustic soda, are mixed with the oil sand, creating a slurry from which bitumen is mobilized and extracted. The resulting slurry waste product is called “tailings” and contains mineral solids, process water, and small proportions of unrecovered bitumen (Masliyah, Zhou, Xu, Czarnecki, & Hamza, 2004; Sobkowicz & Morgenstern, 2009)."

Jan 1, 2019

By K. Soucek, J. Ptácek, A. Hastíková, R. Kukutsch, P. Konícek, P. Waclawik

"Cable bolts are used frequently as a secondary support system (with steel arch support) in difficult stress-strain conditions of deep coal mines. The load transfer mechanism of cable bolts depends on several factors, such as the strength, deformation and geometric properties of the bolts, resin and the surrounding rock mass so-called cable-resin-rock system (CRR system). The bonding length and bolt/borehole diameter ratio strongly influence the final bearing capacity of the CRR system.The study presents the behaviour of CRR system during a pull-out test which is usually used in the carboniferous rock mass in the Czech part of the Upper Silesian Coal Basin. A series of 28 pull out tests were performed on 3-m-long cable bolts, with various combinations of borehole diameters and bonding lengths, to understand this behaviour. Boreholes were drilled into a solid rock mass consisting of fine-grained sandstone to guarantee similar conditions during the pull-out tests. Video inspection and measurement of borehole diameters were performed to determine their quality and real diameters. Three characteristics were observed from pull-out test results: ultimate pull-out load; displacement of the end of bolt and system stiffness. Numerical modelling by FEM (Finite Element Method) was used to determine the stiffness of the CRR system for variable bolt/borehole ratios and bonding lengths each under constant load. A linear elasto-plastic model and a mohr-coulomb model were used for cable and resin-rock respectively. The results of the experiment may contribute significantly to improving of the methodology of cable bolts installation as well as the design of used cable bolts."

Jan 1, 2015

By A. M. Glendinning

"IntroductionLocationTHE PROPERTY of Aunor Gold Mines, Limited is in Deloro township, Ontario, about three miles southeast of the town of Timmins. It consists of a group of eleven claims located between those of Buffalo-Ankerite Gold Mines, Limited, and Delnite Gold Mines, Limited.GeologyThe ore zone at the Aunor mine consists of a narrow band of fine grained pillowed andesite, irregular bands of 'brown to green carbonated andesite, and lenticular bodies of quartz feldspar porphyry. The zone strikes N.80°E., dips 60 North, and has been traced for 5,000 feet across the property. It varies in width from 0 to 250 feet and is bounded on the north and south by masses of dark bluish-grey tale chlorite schist. These schist bands have widths up to 500 feet.The ore occurs in a series of parallel and branching veins confined to the limits of the zone. These veins tend to terminate and die out on the footwall schist contact, striking generally parallel with the ore zone. In wide sections of the zone, 150 to 250 feet, the veins range in width up •to 3.5 feet and may occur in two or three horizons across the width of the zone, each mineable independent of the other. They tend to dip a little flatter than the general dip of the zone. Where the zone is narrow, the veins are so closely spaced and numerous they can be mined together and in some places the complete zone has been mined from schist to schist."

Jan 1, 1953

This paper comprises a description of on-stream analysis instrumentation, including sample handling, X-ray optics and data processing. It also includes a discussion of some typical applications of an on-stream analyzer as related to the mineral processing industry. Introduction T WO automatic X-ray spectrometers have been developed for the simultaneous analysis of as many as six elements in a given sample. These instruments, namely the On-Stream Analyzer and the new Vacuum Simultaneous Spectrometer, have been designed specifically for process control in industry where large numbers of static samples or a number of flowing sample streams must be analyzed continuously with both speed and accuracy. This paper is concerned particularly with the application of these instruments for the continuous analysis of dynamic samples. The Instruments The On-Stream Analyzer and the Vacuum Simultaneous Spectrometer are intended to serve industry by offering two basic approaches to the problem of continuous sampling of flowing sample streams. The On-stream Analyzer (Figure 1) is designed for the completely automatic and unattended analysis of flowing sample streams in a programmed cycle of operation.

Jan 1, 1965

By S. Kashani-Nejad

The kinetics of the thermal decomposition of samples of Mg2(OH)3Cl.2H2O that were obtained by a novel leaching technique applied to a commercial magnesium electrolysis feed were investigated under ambient atmosphere. Thermogravimetric (TG) Analysis showed that decomposition of Mg2(OH)3Cl.2H2O exhibited a single intermediate stage wherein crystalline water was lost at roughly 108 °C. Conversion of the resulting Mg2(OH)3Cl to MgO, HCl and 1120 occurred at temperatures above 398 °C. Thermal decomposition of anhydrous Mg2(OH)3Cl was seen to be consist of two stages. Both stages exhibit first order kinetics with respect to the weight percent of Mg2(OH)3Cl remaining in the sample. However, the rates of decomposition in the two stages were significantly different. Detailed analysis of the kinetic data suggested that the rate of decomposition of Mg2(OH)3C1 was controlled by the rate of removal of the gases released. The change in decomposition rate during the course of the experiments was explained by HCI being released in stage 1 and followed by release of H2O in stage 2.

Jan 1, 2004

By H. Groeneveld, C. A. Connally, P. J. Hoenmans, W. L. Mason, John J. Justen

"A miscible displacement pilot, using a slug of LPG driven by separator gas, was conducted in the Cardium Reservoir of the Pembina Field. The injection pattern was a 10-acre, inverted, isolated five-spot. Upon completion of the LPG-gas phase, an .experiment was conducted using a slug of water followed by gas. Calculated performance of the pilot is compared with actual performance. Equations are developed to cakulate the distribution of LPG into zones of varying permeability, to estimate the progress of the flood at different times in the various zones, and to estimate gas rates after breakthrough. The analysis indicates that permeability stratification was a dominant factor in con-trolling oil recovery and that oil was completely displaced from the swept pore volume. The results of the pilot indicated that miscible flooding is a practical means of pressure maintenance in this reservoir. The total recovery from the pilot area was good in spite of the early breakthrough of LPG. The effects of stratification were reduced by injecting a slug of water into the partially swept reservoir."

Jan 1, 1960

The principles and utility of in-situ coal gasification are discussed, and a first field test conducted by the Alberta Research Council in 1976 near Forestburg, Alberta, is described. The test was carried out in a 12-ft subbituminous coal seam under 60 feet of cover. Within this seam, a 30 by 60-foot block , containing approximately 650 tons of coal, was delineated by four injection/production holes which were oriented to take advantage of the natural fracture system in the coal. Linkage between holes was established by reverse combustion and gasification was accomplished by injecting air into the ignited coal. No steam was injected but operating pressures were adjusted to utilize formation waters for partial carbon -steam gasification. The coal gasification runs lasted six weeks and gasified an estimated 900 tons of coal ,' during sustained periods of gasification, a fuel gas with heating values of between 110 and 150 Btu/scf was obtained. Plans are now being developed for excavating the test site and inspecting the subsurface cavities created by gasification.

Jan 1, 1977

By Z. Zhao, B. Li

"Fractures are the key channels for fluid flow and mass transport in fractured rocks of low/negligible matrix permeability. In single rock fractures, surface roughness causes fluid flow in tortuous paths, and reduces the overall fracture conductance. A number of empirical models have been proposed to relate the reduced hydraulic aperture to the mechanical aperture due to surface roughness, which were revisited and compared. Using two of those relationships between hydraulic apertures and mechanical apertures, we studied the influences of local surface roughness of fractures on fluid flow and solute transport processes at the macroscopic scales of fracture networks. The results show that fracture roughness can affect the flow rates and residence time to varying extent, mainly depending on the empirical models between hydraulic apertures and mechanical apertures. However, fracture roughness has negligible influences on the general patterns of fluid flow (channeling) and solute migration (e.g., travel paths and shape of breakthrough curves). This is because the connectivity of a fracture network is mainly determined by other geometrical parameters (fracture positions, orientations, and lengths), rather than roughness or apertures. INTRODUCTIONIn fractured crystalline rocks of low or negligible matrix permeability, fluid flow and contaminant migration mainly occur within the connected fractures. An understanding of fluid flow and contaminant migration in fractured rocks is a crucial issue in many deep underground projects, e.g. underground repositories for radioactive waste, CO2 sequestration, enhanced geothermal systems, oil and gas production, etc. Rock fractures are typically rough-walled, and surface roughness appears to have first order control on the mechanical and hydraulic behavior of single rock fractures (Boutt et al., 2006).It is well known that the mechanical aperture of a rock fracture is usually larger than its hydraulic aperture, due to fracture surface roughness (Tsang and Witherspoon, 1983). However, for naturally fractured rocks including numerous discontinuities, the effects of this reduced hydraulic aperture in local fractures on macroscopic fluid flow and solute transport in complex fracture systems still remain unclear. Many previous studies assumed identical hydraulic and mechanical apertures in discrete fracture network models for simplicity (Min et al., 2004; Zhao et al., 2011). Therefore, the main objective of this study is to evaluate the influences of local surface roughness of fractures on fluid flow and solute transport processes at the macroscopic scales of fracture networks, by employing the empirical models that relate the hydraulic aperture to the mechanical aperture."

Jan 1, 2015

By F. S. Su, P. Z. Pan, X. T. Feng, F. Yan, W. W. Ji

"This paper aims to simulate the spalling failure behavior in hard rock based on a self-developed numerical model, i.e. a rock discontinuous cellular automaton (RDCA). A crack initiation and propagation criterion is proposed based on the plastic strain, which is used to link the continuity and discontinuity during the failure process. The discontinuities of rock, such as cracks and other internal boundaries, are represented by discontinuous displacement functions, i.e. tip enrichment and step enrichment. The partition of unity is used to improve integral precision of the elements intersected internal boundaries, which is traced by a level set method. Arbitrary crack geometries can be conveniently represented and it does not require any remeshing in the modeling of crack initiation, propagation and coalescence. Numerical modeling of excavation in hard rock using RDCA is conducted. The spalling failure process of hard rock induced by excavation is well simulated. The depth and shape of hard rock spalling failure are good agreement with in situ observation.INTRODUCTIONThe excavation in rock mass is more and more popular. At the same time, the disasters, such as rock burst, rock spalling and falling etc, induced by excavation are quite prominent. Numerical modeling is an important way to help us understand the failure mechanism of rocks. Many numerical methods have been used to simulate the excavation of rock mass. For example, the finite element method (FEM) (Karakus and Fowell, 2003), the discrete element method (DEM)(Cundall and Strack, 1979, Labra et al., 2008), Finite difference method (FDM)(Zhu et al., 2009), Element Free Galerkin Method (Belytschko et al., 1994), Discontinuous displacement analysis (DDA) (Shi, 1988) and Boundary element method (BEM) (Katsikadelis, 2002, Chen and Hong, 1992) are commonly found in the stability analysis of excavation in rocks. In the modeling of crack propagation or excavation, most of these methods are tedious since the internal boundaries have to be consistent with the element boundaries. And in many cases, the remesh has to be conducted. In recent years, people are interested in particular types of FEMs, such as the extended finite-element method (XFEM), the particle discretization scheme finite-element method(PDS-FEM(Hori et al., 2005, Oguni et al., 2009)), the combined finite-discrete element method (FEM/DEM) (Munjiza and Wiley, 2004, Cai, 2008) and spectral-element method(Gharti et al., 2012) etc."

Jan 1, 2015

By Kaiwen Xia, Bibhu Mohanty, Per Svedensten, Sheng Huang

"The mechanics of crushing and grinding operations in mining and excavation processes has been investigated in a laboratory simulation study. It employs a multi-particle bedded rock target, which is subjected to multiple impacts. The impact set-up consists of a Hopkinson pressure bar and a Piston-holder system. The apparatus, employing a 38 mm diameter pressure bar, was used to apply varying but calibrated dynamic loading force on the rock particles. The energy consumed by the sample during fragmentation was determined by considering the energy carried by the incident wave and the reflected wave. The Pistonholder system is used to hold rock samples and to recycle fragments after each test for particle size analysis, for single as well as multiple impacts. The feed size selected was in the range of 9.5 to 12.7 mm for all rock samples, and the impact velocity was set at 14 m/s. Two strong granitic rocks and a relatively weak limestone were the target rocks. The resulting particle size distribution after each set of impacts, ranging from single to 10 consecutive impacts, were analyzed, and various size distribution functions (i.e. Rosin- Rammler, Swebrec, Grady and Gilvarry functions) were fitted to compare their suitability in predicting the fragment size distribution for each rock type. INTRODUCTIONCrushers are widely used in the mining industry all over the world. Understanding fragmentation behaviour of rock under crushing process is fundamental to improved productivity and efficiency in mining operations. This is particularly so as all subsequent size reduction processes such as crushing and grinding are far more energy intensive than the initial blasting process employed in breaking of in situ rock. A considerable body of experimental studies exists on the behaviour of rock crushers for specific rock types in order to aid in the design of various types of crushers. However, these studies are mainly site specific, that is, the results are largely empirical, and the fundamentals of fracture process that lead to size reduction have not been dealt with adequately. Most such studies have attempted to link the input parameters, such as feed size and crusher parameters, with output particle size, and global energy expended in the process. However the physical mechanism of crushing process is still not well understood. First of all, the energy consumed by the rock sample is hard to calculate during standard crushing or grinding tests; secondly, multi-particle test is hard to perform in the laboratory due to irregular shape of the subject rock sample. In This paper, describes a laboratory crushing apparatus for multi-particle rock samples, with sufficient control of the energy expended in the process, with a view to relate creation of new fracture surfaces in the size reduction process."

Jan 1, 2015

By Henri-Louis Jacob

Le Québec dispose de ressources en silice abondantes et diversifiées, pouvant convenir dans l'ensemble à la plupart des usages industriels. Dans les terrains Paléozoïques des BassesTerres du Saint-Laurent et des Appalaches, les ressources identifiées comprennent les grès quartzitiques purs du Croupe de Potsdam (Cambrien), exploités notamment à Saint Canut au nord de Montréal comme source de sable de silice pour l'industrie du verre; les arénites quartzitiques des Formations de Val-Brillant (Silurien moyen) et de Kamouraska (Ordovocien inférieur) exploitées dans l'est du Québec comme source de fondant métallurgique; les grès friables de la Formation de Guigues (Ordovicien) au Témiscamingue, à partir desquels on produit des sables de silice utilisés notamment en fonderie et en filtration. Dans la province structurale du Grenville, au nord du fleuve Saint-Laurent, les métaquartzites purs du Supergroupe de Grenville représentent une source importante de silice pour la production de silicium, de ferro-silicium et de carbure de silicium. Des veines et amas de quartz ont aussi été exploités un peu partout au Québec comme source de fondant métallurgique ou de silice ultra-pure pour la production de silicium métal. Quelques dépôts de sables naturels, généralement d'origine marine ou deltaïque sont finalement exploités dans la région de Montréal comme source de sable pour des usages n'exigeant pas un produit de haute pureté.

Jan 1, 2001

By Laura A. Sanders

Mineral scale formation is prevalent in numerous mining operations. Such scale formation can occur in the direct-contact heat exchangers ahead of an autoclave. In these heat exchangers, the incoming slurry comes into contact with steam in a stage-wise fashion, which is re-circulated from the downstream flash vessels to heat the slurry in stages ahead of the autoclave. Calcium sulfate scaling causes severe problems in mining operations where increased temperatures are involved due to rising temperatures promoting calcium sulfate scaling through a decreasing solubility. In a number of these operations, the scale formation can occur in the presence of mineral solids, where fine-grained charged particles are at concentrations in excess of 35%. Scale prevention is not difficult in standard aqueous systems; however, the presence of solids leads to significant deficiencies in the prevention of scale due to the adsorption of the polymer onto the charge solids instead of the polymer interaction with the scale. Therefore, a technical solution to prevent mineral scale build up occurring in presence of pulp slurry in mining operations is needed. Several novel antiscalant technologies were developed and evaluated which provided a substantial improvement in the scale prevention in such systems.

May 1, 2013

By Clemens Kuhnert

"Nickelhütte Aue GmbH is specialized in the recycling of waste materials containing non-ferrous metals. We treat nickel, copper, cobalt, vanadium, molybdenum and precious metal containing materials like spent catalysts, ashes, dusts, grindings, liquids, slurries and sludge's as long as they contain one or a combination of the above mentioned metals. In our pyrometallurgical works we produce non-ferrous metal concentrates suitable for further treatment in our hydrometallurgical plant where we refine Ni-, Cu-, Co- and V-chemicals. Our production is based on synergy effects due to the combination of pyro- and hydro-metallurgy. As an example we can mention our heat recovery system and internal recycling of by-products. Furthermore, the use of alternative fuels instead of fossil fuels contributes to the economic and environ-mentally friendly treatment system.INTRODUCTION Nickelhütte Aue GmbH (NHA) can look back on nearly 400 years of tradition as a pyrometallurgical works and recycling company. The existence since its foundation in 1635 as a blue dye works shows responsible and successful action in the past. Therefore, we see highest customer service, minimization of interferences with nature by closing material cycles and maximized health and occupational safety protection by avoiding injuries and diseases, still as our future duties. These duties are evaluated and monitored by an integrated management system that meets the standards of DIN EN ISO 9001, 14001, 50001 and BS OHSAS 18001. We commit ourselves to the observance of all juridical and customized demands. The management and the department managers perceive their model function. We require responsible action from all employees. To protect the continuity of our enterprise, we will also perform in future continuous improvement of products and their quality, as well as steady progress in the areas of environment protection, health protection and industrial safety. Equally the effectiveness and propriety of the management system is checked and developed regularly. In order to obtain the objectives resulting from this policy, our company determines activities and measures by involving all employees."

Jan 1, 2017

By Daan Maijer, Wade Marquardt, Robert MacKay, Steven Cockcroft, Farzaneh Farhang Mehr

"To comply with the new Corporate Average Fuel Economy (CAFE) standards, the automotive industry is aiming to reduce weight and increase the power and efficiency of small displacement engines through the application of forced induction technologies. As an example, there are now several 2.0 litre turbocharged engines in production, producing in excess of 240 hp. To meet the need for improved fatigue properties in the engine blocks used in these high-output engines, a new water-cooled chill technology is under exploration at UBC in partnership with General Motors and Nemak. A series of experimental techniques were used to assess the capability of the new chill to extract heat from an A319 casting in the vicinity of the main bearing bulk head. The results show that this method has the potential to achieve a reduction in secondary dendrite arm spacing thus meeting the new microstructural specifications for these engines.INTRODUCTION The automotive industry is working to meet the stricter efficiency requirements laid out within the CAFE (Corporate Average Fuel Economy) regulations (Bastani, 2012; Cole, 1995; Mackay, 2011; Miller, 2000), while at the same time not sacrificing performance. One approach is to increase the use of lightweight materials, which leads to a decrease in the overall vehicle weight and fuel consumption (Cole, 1995; Mackay, 2011; Miller, 2000). Other approaches include smaller displacement engines and gas-electric hybrid drivetrains. However, one trend that is becoming clear, is a greater emphasis on force induction gasoline engines. This allows for weight reduction to be achieved with smaller displacement engines without sacrificing performance. One consequence of this approach is that the engine block materials are subject to higher in-service thermal and mechanical cyclic loads (Cole, 1995; Miller, 2011; Heysler, 2001) The fatigue properties of an alloy are strongly affected by a number of the, as-cast, microstructure features including, Secondary Dendrite Arm Spacing (SDAS), porosity and eutectic lamella spacing (including intermetallic ß-Al5FeSi platelets) (Mackay, 2010a; Mackay, 2010b; Viet-Duc, 2015; Casellas, 2005). It is generally accepted they can act as fatigue initiation sites and that a reduction in their size will result in an improvement in fatigue performance. For a given alloy chemistry, one of the key parameters affecting the length scale of all three is cooling rate (Mackay, 2000)."

Jan 1, 2017

By P. Müller, W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"Abstract -The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was Iow, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization .Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This mode] does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5% of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipitation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994

By F. R. Nogas

"Because of the elements of uncertainty and instabilitp associated with single-enterprise communities, there is increasing interest in the alternatives to developing additional new communities of this nature. Gulf Minerals Canada Limited has chosen a unique alternative means to accommodate employees at a new uranium mine/mill complex at Rabbit Lake in Northern Saskatchewan. Gulf has adopted a fly-in program which moves their staff from a 450-mile radius, in and out of the on-site facilities, on a 7-day rotation."

Jan 1, 1976