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By A. Hashempour, D. Javani

"Selection of an optimal bit is a critical issue in drilling engineering. Specific energy (SE) and Cost per Foot (CPF) are the most common methods for evaluation of bit efficiency and optimal bit selection. The major shortfall of both methods is that they do not directly account for geological and geomechanical parameters of formations being drilling. In this paper, results of using the two foregoing methods are compared using Formation Drillability (FD) method, which directly accounts for geological and geomechanical parameters of a formation. This method combines various geological and geomechanical parameters and yields a dimensionless parameter indicating the formation drilling hardness (drillability). Results of this study show that the amount of energy, cost and time spent for drilling a unit volume / length of an identical formation may vary in different wells. This is due to the fact that geological and geomechanical characteristics of a formation may vary among wells and even within short intervals of a single well. Therefore, an optimal bit may not be appropriately selected, if drilling and economical parameters are the only factors considered and the formation geological and geomechanical specifications are ignored.INTRODUCTIONMany authors such as Bilgesu, Al-Rashidi, Aminian, and Ameri (2000) and Clegg (2006) conducted research in the evaluation of bit performance and optimum bit selection. Almost all of them tried to establish a good relationship based on geomechanical parameters. Primary examples are the research done by Ubaldi (1999), Macini, Magagni, Da Dalt, and Valente (2007)."

Jan 1, 2015

By J. E. Ryan

General Description Due to the extreme cold weather experienced in Flin Flon during the winter months, thought and precaution were necessary in the design of the plant buildings. The machine shop, carpenter shop, drill shop, and coal plant buildings are similar in the building materials used in their construction. They are sided with two-inch shiplap, insulated with celotex and asbestos paper, and covered with corrugated iron on all side-walls. Roofing consists of 2 by 4 lumber on edge, laminated, and further covered by celotex and three-ply roofing. These buildings are heated by means of unit heaters. The heaters are primarily steam-heated radiators, through which the air of the buildings is circulated by electrically-driven fans. Our machine shop is located to the east of, but central to, the main operating buildings of the mine and plant, and is so connected by a net work of tracks as to be able to serve all portions of the entire plant conveniently. The building is divided into two bays, the main bay 53 ft. by 340 ft., and the east bay 24 ft. by 340 ft. The shop office and drafting room, a two-story annex 24 ft. by 30 ft., is located on the west side of the shop. The arrangement within the shop is such as to house conveniently the several departments, namely, heavy machine tool section, repair floor section, boiler shop heavy tool and floor section, blacksmith heavy tool and forge section, tool room, electric welding rooms, stock room, tin and copper shop, and electrical parts and armature winding and repair shop (see Figure 1). All the heavy tools, the repair floor section, and railway tracks are so located in the large open bay as to be fully serviced by an electrically operated 15-ton bridge crane, with a span of 50 feet and a travel the full length of the shop. A standard-gauge railway track, branched off the main line, penetrates the full depth of the building. This track lies along the extreme east side of the main bay, allowing easy entrance and movement of rolling stock and heavy machinery, loaded on standard flat-cars, to the repair floors in the main bay. Eight jib cranes, affixed to building columns, further facilitate the heavy repair work throughout the various shop divisions. Our light and heavy machine tools are standard equipment, not unlike tools used in mine, mill, and railway shops.

Jan 1, 1935

By Michael K. Watkeys, Jacobus E. Potgieter, E. Guy Charlesworth, Carl R. Anhaeusser, Roger L. Gibson, Alexander F. M. Kisters

Intrusive features of cupriferous noritoids from the deeply eroded Proterozoic granite-gneiss terrane of the Okiep Copper District in South Africa illustrate the emplacement of basic magmas into a mid- to lower-erustal environment. The small, easterly trending intermediate to basic intrusions of the so-called Koperberg Suite display a wide variety of geometries, occurrence and emplacement modes, including dike-, sill- and plug-like bodies. Coeval granulite-facies metamorphism, partial melting and ductile deformation of country rock gneisses during intrusion of the basic magmas led to emplacement and dilation processes of the intrusions which differ significantly from those described for dikes and sills at shallow crustal levels. Regional tectonic stresses are largely negligible due to very low differential stress [( )] during deformation and intrusion, which permits emplacement at high angles to the principal compressive stress and which follows favorably inclined structural anisotropies. Dilation of the basic intrusions is largely determined by compositional differences of host rocks and occurs by thermal erosion, i.e., assimilation of wall rock gneisses. Low length-to-width ratios of basic to ultrabasic dikes and predominantly diapir-like outlines of mesocratic bodies are indicative of low viscosity contrasts between the mafic magmas and high-grade metamorphic host-rock gneisses. Buoyancy-controlled ascent of the basic to intermediate intrusions is expressed by a broad compositional zoning of basic bodies with respect to the granite-gneiss stratigraphy. Various intrusion modes within the stratigraphic column of the granite-gneiss sequence reflect a lithological and structural stratification of the seemingly homogeneous granite-gneiss terrane.

Jan 1, 1994

By L. Van Wyk, J. Fernandez, J. Suarez, L. J. Diaz, A. Uria, D. Breeuwer

"Ventilation is an essential component of any underground mine, playing a vital role in ensuring the health and safety of workers, and a mine’s continuous operation. At a time when mining companies are increasingly having to move to deeper underground operations in pursuit of high-grade ore-bodies, the search is on for more efficient ventilation systems that will allow mining to be carried out at even deeper levels whilst ensuring the protection of workers and the maximisation of productivity through temperature management and the lowering of energy costs. Mining companies today are looking for innovative ways to deliver new technologies and procedures to enhance their mine’s profitability. Energy consumption by mine ventilation systems is higher than ever due to stringent specifications of underground equipment (primarily combustion engine emissions), air quality standards and mining at deeper levels which all require more powerful ventilation systems. With energy costs associated with operating ventilation systems being a mine’s second-highest cost of production after labour, finding the optimal ventilation solution is critical to a mine’s performance. Proper fan design remains a major factor in reducing capital expenditures (CAPEX) and operational expenditures (OPEX), which means that there are compelling reasons for making use of comprehensive factory testing at full power before fans are dispatched to site to simulate the mine’s current and future design requirements, and thus verify the fan’s effectiveness in ‘real’ conditions.INTRODUCTION A primary mine fan is considered the heartbeat of the entire mine ventilation system, drawing fresh air from the surface and providing a safe environment for miners. A ventilation system’s lack of performance often leads to a reduction in acceptable air quality levels for underground working operations and can potentially have an adverse impact on production rates."

Jan 1, 2019

"This paper presents results of ongoing research being carried out at the University of New South Wales into improved methods for estimating rock mass strength. In this paper the rock mass strength of Hawkesbury Sandstone is assessed. An estimate is first made based on an extensive database of intact rock strength data being collated by the author and the assumption that the rock mass strength can be determined following the GSI approach. The resulting strength envelope is then compared with nine documented case studies where stress induced failure has occurred in tunnels excavated within Hawkesbury Sandstone. The case studies cover a range of conditions:• construction dates from 1880s to 2006• spans from 3.2 to 12.5 m• depths from 17 to 124 m• excavation methods of drill & blast, roadheader and TBM.Finite element modelling is used to assess the likely magnitudes of the stresses present at the time of failure. The finite element models are interrogated to provide the values of major and minor principal stresses in and around the mapped failure zone. Failure and stable points are then compared to the rock mass strength envelope(s) of Hawkesbury Sandstone derived using the Hoek-Brown criterion and spalling criteria. The Hoek-Brown rock mass strength envelope differentiates between the ‘failed’ and ‘stable’ zones remarkably well.INTRODUCTIONStress induced failures of rock masses are fortunately rare in civil tunnelling. However, when they occur they provide an opportunity to calibrate an assumed rock mass strength criterion. This paper compares an estimate of rock mass strength for the Hawkesbury Sandstone with the following cases where stress induced failure occurred in tunnels excavated within Hawkesbury Sandstone.• Cataract & Devines Tunnels of the Upper Canal (Upper Nepean Scheme)• Malabar Outfall Tunnel• Sydney liquefied petroleum gas (LPG) Storage Cavern• Northside Storage Tunnel• Cross City Tunnel• Lane Cove TunnelTwo-dimensional finite element modelling is used to assess the likely magnitudes of the stresses present at the time of the failures. The principal stresses are then compared to the assessed rock mass strength envelope(s) of Hawkesbury Sandstone derived using the 2002 Hoek-Brown criterion (Hoek et al., 2002) and the spalling criterion suggested by Diederichs (2007)."

Jan 1, 2015

By J. -C. Parisien-La Salle, D. Blais, G. P. Demopoulos

"In this work the dissolution, precipitation and adsorption behaviour of gold in acidic iron sulphate media containing small amounts of chloride ions is investigated via batch laboratory tests and OLI thermodynamic calculations over the temperature range 25-250°C. Chloride ions may be present in industrial pressure oxidation/pressure leaching (POX/PL) operations due to elevated water salinity levels or due to intentional addition as is the case of the CESL Copper Pressure Leaching Process. Thermodynamic calculations show that AuCl4 - may form depending on the free Cl-/Au ratio and temperature, its stability increasing with increasing Cl- concentration and decreasing with increasing temperature. On the other hand during POX/PL, we know that massive precipitation of iron in various hydrolysis products and compounds occurs. Hence of interest is the question how AuCl4 - that may form during leaching interacts with the iron precipitation products. Gold(III) chloride was found to co-precipitate with iron(III) (oxy) hydroxides and arsenates forming in the autoclave but not with natrojarosite. Upon further investigation it was discovered that activated carbon added in the autoclave (as done in CIL) acts as preferential sink for the mobilized gold, hence opening the potential for the development of a direct cyanide-free gold recovery process in acidic sulphate leach reactors.INTRODUCTIONThe recovery of gold from ores and concentrates has evolved over the years with processing routes becoming increasingly complex. Given the high value of gold, any reduction in losses during recovery operations constitutes an important economic benefit. One such loss that needs to be addressed is the potential solubilisation of gold during pressure oxidation (POX) of refractory sulphidic gold feedstocks. For example, Agnico Eagle Mines reported a loss in gold recovery due to the formation of a gold chloride complex (Garofalo, 2009). Gold is known to form complexes in solution, such as gold(III) chloride, if an excess of chloride ions are present. The fate of such soluble gold chloride during pressure oxidation and the subsequent neutralization of the acidic discharge slurry will determine if gold is lost or recovered in the downstream cyanidation operation. Thus it is of interest to know under what conditions gold chloride may stay soluble or co-precipitate along primary (formed in the autoclave) or secondary (formed during neutralization) precipitates. Furthermore, the mode of co-precipitated gold, such as adsorption on iron compounds, like goethite and hematite (Machesky et al., 1990; Nachayev, 1984); substitution in one of the precipitated phases; or finally chemical reduction to metallic state would have consequences in terms of gold recovery."

Jan 1, 2012

By E. J. Burrough

MR. J. J. McIntyre (International Coal & Coke Company, Ltd., and McGi1livray Creek Coal & Coke Company, Ltd., Coleman, Alta): Mr. Burrough's excellent paper, Metallurgical Coals of the Crowsnest Area, seems especially timely now, when the need for developing iron industries in the west, as well as in the east, is receiving so much attention. His -thorough review of the 'coking' industry is an especially valuable contribution, along with which the following brief remarks on coking in the Crowsnest Pass area of British Columbia and Alberta may be in order. When the Crowsnest Pass line of the Canadian Pacific railway was built there were great expectations for the non-ferrous metal industry; quite a number of smelter's were al-ready in operation in British Columbia and the northwestern United States, and further expansion was confidently expected. The suitability of the medium-volatile coking coals of the Pass for making metallurgical coke had been recognized from the time the fields were first explored. By the time the mines were fairly well developed there was already a market to war-rant the building of coking plants, and a common belief that expansion of the market would require a large coking industry. The first coke production was from plants built by the Crowsnest Pass Coal Company, Ltd., at Fernie, B.C. in 1903, and the International Coal and Coke Company, Ltd., at Coleman, Alberta. These plants were followed by others built by the Crowsnest Pass Coal Company, at Michel, B.C., by West Canadian Collieries, Ltd., at Lille, Alberta, and by Leitch Collieries, Ltd., at Passburg Alberta, and by a plant at Hosmer, B.C.

Jan 1, 1951

The quality of refractory bricks and castables could be determined by direct measurements of their material properties such as elastic properties, porosity, density, etc. using conventional static or non-destructive testing (NDT) dynamic techniques. Quality monitoring of refractory linings is much more challenging and complicated. The static methods require undesirable drilling and sample extractions from the furnace structure. A more desirable alternative is the use of NDT techniques for material quality estimation. The Acousto Ultrasonic-Echo (AU-E) technique is a new stress wave propagation approach for monitoring the quality of refractory linings in operating furnaces. In this paper, the conceptual methodology for the AU-E technique is described, the capabilities and limitations are expanded, and the results from two case studies are discussed.

Jan 1, 2005

By K. A. Clark

A meeting between representatives of the Scientific and Industrial Research Council of Alberta and the Deputy Minister of Mines for Canada was held at Edmonton in May, 1929, for the purpose of formulating a co-operative plan for carrying forward studies in aid of the development of commercial methods for utilizing the bituminous sands of Alberta. It was agreed that to the Alberta Research Council should be allocated the general problem of investigation of the processes for the separating of bitumen from the sands, including studies of methods of emulsifying, dehydrating and otherwise preparing separated bitumen for industrial applications. It was further agreed that during the present year the work of the Alberta Research Council should be to continue its laboratory investigations of points of design of its separation plant; to further perfect its separation procedure; to recondition its existing separation plant at Dunvegan Yards, Edmonton, in the light of laboratory studies and to operate it for the purpose of demonstrating its efficiency; to carry on tests in emulsifying and dehydrating or otherwise preparing separated bitumen for industrial application; and on the basis of the experience gained in the operation of the preliminary plant at Dunvegan Yards to prepare and design and, as far as possible, to proceed with the erection of, a semi-commercial separation plant at a site to be chosen, probably at the bituminous sand deposits near McMurray, Alberta. This paper presents, in the main, a progress report of the carrying out of this programme.

Jan 1, 1929

By B. W. Raymond, D. W. Zandee

"IntroductionCoal deposits are found in many regions in Canada and vary widely in their age, quality and rank. All classifications of coal except anthracite are found in significant quantities in this country.Deposits in the Maritimes are mainly bituminous; Lignite is found in Saskatchewan and Ontario and sub-bituminous coal in the plains region of Alberta. The Rocky Mountain coalfields of Alberta and British Columbia contain low and high-volatile bituminous coal and, in a few places, semi-anthracite. The British Columbia interior contains deposits of semi-anthracite, bituminous, sub-bituminous coals and lignite. The Yukon and Northwest Territories also contain substantial deposits of bituminous coal and lignite.Currently Nova Scotia produces both thermal and metallurgical coal, Saskatchewan produces lignite and Alberta produces both sub-bituminous and bituminous coal for thermal purposes. Large deposits of metallurgical coal are now being exploited in the Rockies arefl of British Columbia and Alberta by open pit methods. The raw coal is treated in large capacity preparation plants to remove refuse and upgrade the product to a consistent metallurgical quality with respect to ash, moisture, volatile matter and coking properties.The treatment of coal involves crushing, screening and cleaning by dense medium, jigs, water-only cyclones, tables and froth flotation to produce a diverse range of coal products differing in quality and size for various end uses.The chapter on Crushing and Screening Circuits was concerned mainly with crushing of metalliferous ores to produce a concentrate of one or more valuable minerals which normally constitute a small portion of the original mass of the material treated.Coal differs physically from ores in many ways such as lower specific gravity, relatively large volumes but low tonnage of product, and its habit of absorbing moisture requires extensive dewatering processes more complicated than settlement and filtration. Most significant, for this paper at least, is the fact that crushing coal is not as energy intensive and much smaller equipment is applicable.Crushing and screening of ores is intended to reduce the size of all constituents as quickly and efficiently as possible to allow liberation of the mineral particles. The crushing of coal is different in that the coal is not the minor constituent and the production of fines, in the initial stages at least, is highly undesirable. The basic objectives of crushing coal are the reduction of run-of-mine material to sizes suitable for cleaning or further reduction of coal to market sizes."

Jan 1, 1989

By P. E. Cavanagh

THE Ontario Research Foundation has developed a family of dry magnetic concentrators which, when used in conjunction with a dry grinding mill such as an Aero-fall mill, will allow the production of a completely dry magnetite concentrate. Previous experience with extrusion of iron ore and with pelletizing of fine iron concentrates suggested that it might be possible to develop a method particularly suited to the agglomeration of completely dry concentrates which might have some practical advantages over other methods of agglomeration. Pelletizing is the preferred method of agglomerating very fine iron ore concentrates. Magnetite concentrate is fod to the pelletizing equipment in the form of a moist filter cake. Binders and plasticizers may be added if necessary, and the moisture content must be increased or adjusted to the percentage necessary to give good balling action and satisfactory green strength in the resulting moist pellets. The moist ore with a closely controlled water content of about 7 to 12 per cent moisture may be rolled into pellets by a snow-balling action in a pelletizing drum, a Lurgi pan, or a Mac-Dowell disc pelletizer. The resulting green pellets are fired by one of several alternative processes to produce a hard pellet which has sufficient strength to withstand handling and shipping.

Jan 1, 1957

By G. Vibert Douglas

It often happens that the field geologist encounters a fault in ground where there is little to guide him with regard to the throw, or vertical displacement, and the heave, or horizontal displacement. The following construction gives both of these components of the fault, and the writers hope that it may prove a help to others. The construction is applicable to both normal and reversed faults. Briefly the procedure is as follows: Take a point which is common to the faulted geological feature and to the fault plane and on the downthrow side of the fault. Move this point in the horizontal plane in the direction indicated by the fault striæ. Rebat the point down to the plane of the fault and obtain its throw. Next consider the other side of the fault and truncate it down by the amount of the throw just determined. Then project the line of the geological feature through to the trace of the fault-plane at the lower horizon. The result is the relative positions of the two parts of the original geological feature as severed by the fault. In Figure r, let us consider a typical normal fault, that is, a fault in which the hanging-wall has gone down relative to the footwall. This characteristic, or its alternative, the reversed fault, is determined by observation on the ground. Let AB be the line of any geological feature such as the edge of a dyke, vein, or bedded sediment. The plane of which AB is the trace may have any dip; in the present case let us say 70° right. Let FF be the trace of a fault-plane which may have any dip; let us say 35° left in this case.

Jan 1, 1928

By I-H. Jung, J. Kim

"Mg alloys are extensively used as light structural materials in modern industry. Mn and RE (rareearth) metals are effectively used as alloying elements to enhance the properties of Mg alloys. Therefore, the thermodynamic database of those alloys is important in the Mg alloy design and processing. Critical evaluation and optimization of all available literature data for the Mn-RE systems were conducted to obtain reliable thermodynamic functions. The Mn-RE systems shows systematic changes in the phase diagrams and thermodynamic properties with increasing atomic number in the lanthanide series. This systematic approach for all RE elements allows to resolve inconsistencies in the available experimental data. INTRODUCTIONRare Earth (RE) metals are widely used in many industrial fields including permanent magnet, electronic materials and structural materials. As a small addition of RE can enhance magnetic, electronic, optical and mechanical properties of numerous materials, the usage of the RE is still expanding regardless of the strategic control of their supply.Magnesium alloys are getting great scientific and industrial attention as the lightest structural materials. One of the drawbacks of Mg alloys is their poor formability at room temperature due to the limited slip system with hcp crystal structure. Recently, several studies (Farzadfar et al., 2011; Sandloebes et al., 2010; Stanford, 2010; Stanford et al., 2008; Yan et al., 2010) show that the additions of small amounts of RE can considerably enhance the ductility of Mg alloys. Therefore, a lot of research on Mg-RE alloys is undergoing to clarify the role of RE on the enhanced deformation mechanism and to find out the most optimum Mg alloy compositions. In order to respond to the need of Mg-RE alloy development, a large thermodynamic database for Mg alloys containing RE has been developed with critical systematic analysis and optimization of the entire RE series data. This includes the thermodynamic database of the Mg-RE (Kang et al., 2009), Mg-RE-RE (Kang et al., 2009), Mg-Al-RE (Jin et al., 2011; Jin et al., 2010), Mg-Zn-RE and Mg-Mn-RE systems."

Jan 1, 2012

By K. Esmaieli

The Synthetic Rock Mass (SRM) approach has the potential to capture the mechanical behavior of large rock samples. In order for the method to be used with confidence it is necessary to gain a good understanding of the factors that influences its analysis. This paper reports on a series of numerical experiments, based on field data from a large underground mine, to investigate the influence of intact rock mass strength of a constructed (SRM). A jointed rock mass defined by three fracture sets was simulated by a Discrete Fracture Network (DFN) model. The generated fracture network was subsequently embedded into six different intact rock samples, simulated by a bonded particle model in PFC3D, generating six SRM samples. Each intact rock sample was 7 m × 7 m × 14 m and assigned different mechanical properties. The first intact rock sample was assigned a uniaxial compressive strength of 205 MPa and an elastic modulus of 104 GPa with the UCS and elastic modulus values of the other samples downgraded by 10% until the weakest sample had a UCS value of 121 MPa and an elastic modulus value of 61 GPa. All SRM samples were loaded under uniaxial compression to obtain the complete stress strain curve. It was observed that the compressive strength of the rock mass samples decreased by 10% following the same trend as the rock material strength. However, the elastic modulus of the rock mass samples decreased non-linearly with reduction of the elastic modulus of the rock material. The Poisson's ratio of rock mass samples does not change with decrease of rock material properties. For the post-peak behaviour the results show that both the brittleness index and the residual strength of rock mass samples decreased as the rock material properties degrades.

Aug 1, 2013

By W. M. Tupper

Municipal governments recognize the importance of aggregates in the local economy and the need to manage this resource in the interest of the public good. They have encountered problems with regulating the industry and the dichotomy between the urban need and the rural source. They have suffered from a lack of financial benefit, an adequate aggregate inventory, provincial strategy, economic information and public understanding. A provincial strategy for ensuring the availability of aggregate supplies to developing areas of the Province is essential. The Province should also be responsible for licensing, research, technical expertise on rehabilitation, public education and financial assistance. Upper-tier municipalities (regions or counties) should assume responsibility for resource management, including resource availability, demand characteristics, truck routing, phasing of resource development and sequential land-use planning. Area municipalities (towns and townships) can best determine the social and environmental impact of a specific aggregate development proposal and should therefore have the primary responsibility for the location of new pits and quarries. They should also have the authority to supplement provincial regulations concerning operating standards and the phasing and standards of site rehabilitation.

Jan 1, 1978

By Ifeanyichukwu Nweke

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

Jan 1, 2018

By A. Musschoot

"The paper will review general types and designs of vibratory feeders, describing briefly the design features and characteristics that apply to the application of specific types. Control considerations for selecting types will be dis• cussed, such as fixed or adjustable, manual or automatic, individual or multiple bank, and process requirements. Design parameters for hopper openings and installation geometry will be discussed, including consideration of material size distribution, segregation, moisture content and other characteristics, based on practical applications and experience as well as theory. Pan designs and the selection of pan materials will also be discussed with reference to wear, corrosion, impact and practical economic factors."

Jan 1, 1972

By John Rowson, Caitlin Brown, Kebbi Hughes, Joseph Esslifie-Dughan

The McClean Lake mill in northern Saskatchewan, Canada, is operated by Orano Canada Inc. and has been in production for the last 20 years. The tailings preparation process at the mill has been designed with decommissioning in mind, to produce tailings that are geochemically stable over the long-term within the site’s tailings management facility. Twenty years of study have contributed to a detailed understanding of geochemical and geotechnical properties of the McClean Lake tailings. Validation of the tailings properties has occurred through in-situ sampling campaigns conducted initially every year, and later every five years. Each sampling campaign has applied the same rigorous sampling procedure to provide data with useful correlations year over year. Each campaign result compares elements such as the inherent variability of the tailings, consolidation of the tailings and variations in the tailings placement methods. We will discuss lessons learned from seven sampling campaigns over 20 years and present data to show the reliable tracking of geochemical evolution of the in-situ tailings over time; providing opportunities for continuous improvements.

Jan 1, 2020

By R. Darlington, S. Ji

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

Jan 1, 2018

By A. Henk, C. M. Aruffo, K. Fischer

"Geomechanical reservoir modeling offers a valuable tool to predict tectonic stresses, in particular the local perturbations in orientation and/or magnitude which occur at lithological boundaries and faults. The paper presents a workflow for building and calibrating such geomechanical models. The numerical simulations are based on the Finite Element method and can range from field-scale models to smaller, highly detailed submodels of specific fault blocks. The approach considers the reservoir-specific characteristics with respect to subsurface geometry (lithostratigraphic boundaries, faults), mechanical properties and ambient stress field. During the subsequent calibration stage calculated stresses are compared to stress data actually observed in borehole data. Poorly constrained input parameters are iteratively modified within reasonable limits until a satisfactory fit between calculated and measured stresses is achieved. This validated model can then be used for stress predictions between wells and in undrilled parts of the reservoir, respectively. The workflow is applied to two case studies - a large gas field in Northern Germany and a CO2 sequestration project in Australia – to test and illustrate its practical value. INTRODUCTIONDetailed knowledge of the tectonic stress field is crucial for the optimal exploration and use not only of conventional and unconventional hydrocarbon reservoirs, but also for deep geothermal reservoirs, carbon capture and storage (CCS) projects as well as underground mining and nuclear waste repositories. Any reliable stress prediction is hindered by the observation that the magnitude and orientation of the stress field can vary significantly – not only in time, but also in space. Such spatial stress variations comprise all scales, i.e., from the scale of lithospheric plates down to the grain-scale. On the reservoir- and fault blockscale, the local stress field can be influenced by faults and different mechanical properties of lithologies (Sassi & Faure, 1997). The resulting variations in stress magnitude and/or stress orientation are commonly referred to as stress perturbations and give rise to a unique, reservoir-specific stress pattern (Yale, 2003). Thereby, local stress fields can deviate by up to 90° in orientation and several tenth of Megapascal (MPa) in magnitude from regional trends."

Jan 1, 2015