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By A. Haque

"This paper describes an improved formulation of an analytical shear strength model developed by Haque & Kodikara (2012) by incorporating the failure of regular concrete/rock joints subjected to CNS condition. Sokolovskii’s analytical solutions developed for failure stress of slopes have been found to be effective in this regard. The analytical models have been validated for predicting the shear behaviour of concrete/rock joints subjected to various CNS loading conditions. The model has been found to accurately predict the dilation, normal stress and shear stress behaviour for a regular triangular saw-tooth joint up to the peak shear stress. Moreover, the peak shear stresses of concrete-rock joints with asperity angles ranging from 5 to 27.5o compared reasonably well with the available laboratory test results.INTRODUCTIONA new shear strength model for elastic regular triangular concrete/rock joints loaded under Constant Normal Stiffness (CNS) boundary condition has been developed by Haque & Kodikara (2012). The salient feature of this model is its capability of accurately estimating the normal and shear stresses of joints with shear displacements under CNS condition by incorporating the elastic deformation of asperities. However, the shear strength model of Haque & Kodikara (2012) for the elastic asperities cannot be directly employed to predict the peak shear stress of a joint experiencing plasticity under applied loads. Therefore, the model inevitability requires articulation of an appropriate shear failure criterion simulating the boundary conditions of the loaded asperity to predict the peak shear stress and corresponding normal stress and dilation behaviour of concrete/rock joints. Sokolovskii (1960) developed a set of analytical solutions for failure stress of slopes comprising c-??soils, which can be exploited effectively to simulate the failure condition as encountered for loaded regular triangular concrete/rock joints (Seidel & Haberfield, 2002)."

Jan 1, 2015

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

By B. Oraee-Mirzamani

One the most important tasks after excavation of tunnels is the implementation and installation of a support system. Tunnel collapse poses a safety hazard and can cause worker injuries. In addition, it may have a severe economic impact because tunnel collapse can stop production and ore transportation. Therefore, an appropriate and well-designed support system is necessary for collapse prevention and to help stabilize the tunnels. In this research, we suggest a support system for the Parvade1 underground coal mine. The study case is a common mining roadway tunnel in the E1 longwall panel in this mine. To design an appropriate support system, we used the finite element method (Phase2 software). The results of this research can be used to design support systems for future tunnels in this mine and any coal mine that has similar conditions.

Aug 1, 2013

By D. W. Davis, P. Landais, L. J. Robb

Nodules of carbonaceous matter have been observed in several Archaean peraluminous granites adjoining the gold- and uranium-bearing Witwatersrand Basin. These nodules, which resemble solid bitumen, usually replace uraninite or uranothorite and are paragenetically late. They show many similarities to kerogen seams and nodules associated with the conglomerate horizons in the Witwatersrand Basin, including composition, maturation, intimate association with uraninite, and a late paragenesis. U-Pb isotope ratios for granite-hosted and Witwatersrand kerogens define a single, albeit somewhat diffuse, Ph-loss discordia suggesting an upper intercept age of circa 2300 Ma. Carbon isotope analysis indicates lighter Ol3C values for the granite-hosted nodules than for the sediment-hosted kerogen seams. Raman spectroscopy indicates that granite-hosted kerogen is more highly ordered than Witwatersrand seam kerogen. A model is presented which links the granitoidand sediment-hosted organic matter to an event of oil generation in the Witwatersrand Basin circa 2300 Ma ago. Light hydrocarbons migrated through the sediments and into underlying/adjacent granitic rocks, undergoing polymerization and accumulation in response to radiation accompanying the presence of high-uranium phases.

Jan 1, 1994

By Fred G. Hewett

Cassiar Mine in northern British Columbia began development in 1952. The deposir is found on rhe west limb of rhe McDame Synclinorium in a Mississippian serpentinite body. The serpenltntte, one of the McDame l ntrusives, imrudes Sylvester Group . rocks, which comprise a Lare Devonian to Early M1ss1ss1pptan eugeosync/inal sequence of argillites, quarrzires and volcanics. The foorwall conracr berween Sylvester Group rocks and rhe serpenrinire is a marked zone of broken and incomperent argillite and graphitic schist. The less marked hang- 111gwall contacr 1s a band of indurated argillite. The JurassicCretaceous emplacemenr of the Cassiar Graniric Barholilh is responsible for mosr of the numerous )aims, faulrs and shear zones found in the serpentinite body. Faulting occurred borh before and after asbestos formation. Asbestos is mined from an open pit ar rhe rate of 4,535 ronnes daily. It passes from the pir along a rramline to the mill, where it is concen/rared into nine direcr milling grades. Packaged fibres travel ro over 40 counrries around rhe world for use in the texrile, cemenr and other industries.

Jan 1, 1984

By J. C. Hampton, L. A. Matzar, C. R. Gamwell

In geomechanics, conducting uniaxial or triaxial compression tests require samples to be prepared to a certain length-to-diameter ratio. This ratio is typically defined as 2:1 (length to diameter) and is accepted as a common standard for all materials on which mechanical properties testing is performed. Variations in sample length can cause changes in measured strength properties across multiple material types, such as cement, rock, or soil. Within the oil and gas industry, it is not uncommon to receive samples for technical services work that are slightly under or exactly the length requirement before surface grinding and sample preparation. Many of these samples are discarded from uniaxial and triaxial compression tests and used in another manner; therefore, it is necessary to study the length-to-diameter ratio in efforts to understand the limits and validity of testing samples that are slightly out of the 2:1 ratio. This paper discusses uniaxial compression tests performed using Berea sandstone and a standard cement mixture of 2.54-cm diameter to study changes in rock strength and properties. Compressive strength for each lengthto- diameter ratio over a range of 0.5:1 to 2.2:1 was measured. The investigation was extended to study near-end effects, where the sample length is near, but not exactly twice the diameter. It was discovered that the cement samples conformed reasonably well to the suggested ASTM correction factors. The sandstone did not conform to the correction factors and further analysis is required to develop a correction factor unique to the material. Near end effects, in both the cement and Berea, were found to increase compressive strengths, especially when the L/D of the samples was increased slightly over a 2:1 L/D.

Jan 1, 2015

By M. Specht, D. Pörzgen, W. Lorenz, A. /. Buhr, R. P. Racher

The introduction of the near net-shape casting process at CORUS Staal IJmuiden in January 2000 required changes of secondary metallurgy processes including a development towards more aggressive slag compositions in the steel ladle. Therefore the steel ladle lining has been changed from fired andalusite bricks to magnesia-carbon bricks and, most recently, to fired spinel bricks to withstand the severe slag conditions. In comparison to the andalusite bricks the new steel ladle linings have a higher thermal conductivity. This requires the capability to keep the lining warm by ladle preheaters to sustain the overall thermal stability of the steel ladle in case of interruptions during hot cycling of the ladles.

Jan 1, 2004

By C. A. Clark

The Chagres Smelter is located 80 kilometres north of Santiago - Chile, in the middle of an agricultural valley which is also one of the poorest districts in the country. This condition sets the main focus for the smelter's Corporate Social Responsibility (CSR) programmes, which ultimately aim at building self sustainable social and economic capital in accordance with the local capacities. With the help of Anglo American's SEAT (Socio Economic Assessment Toolbox), a corporately developed instrument designed to help the operations understand the needs of the communities and the impacts of those operations, the Chagres Smelter implemented several programmes, such as the CETTA (Experimental and Applied Technology Transfer Centre) programme. This project started in 2003, and consists of creating a centre for the transfer of sustainable techniques and skills for the small agricultural and livestock producers that live in the rural areas near the Chagres Smelter. Its main impacts are: Improved production quality (goat cheese and bee honey) and access to relevant markets, improved training and self-sustainability levels of producers, enhanced socio-economic level of the District's inhabitants by improving their income earning opportunities and technical knowledge, creation and promotion of a local brand as a symbol of quality products from the valley and a positive environmental impact of good breeding and native flora protection practices in the area. Other relevant social programmes are the 'Environmental Strivers', which created a recycling centre in the community; and the 'Beautiful Valley" project, which provides management knowledge and skills to local youngsters and leaders who can contribute to finding solutions for local environmental needs.

Jan 1, 2007

By L. H. Thorleifson

Demand for both gem and industrial diamonds is very strong. Synthetic production supplies industrial uses, but synthetic gems remain inferior and expensive, so the large gem market is supplied by mining. Several major mines have been depleted, and the market is receptive to new sources of high quality gems. Canada's Precambrian terrane, extending across the Canadian Shield and under the Phanerozoic cover of the Plains and Hudson Bay, has excellent potential for diamonds, but exploration conditions are difficult due to recent glaciation. Early world exploration relying on recognition of diamond in alluvial sediments was adequate to launch pre-1900 production from India, Brazil, and Africa. Exploration success in Canada, as was the case in Russia and other more recently discovered sources, however, had to await large investments in effort supported by advanced science and technology. Canadian exploration in many ways is similar to that in other regions, relying on analysis of tectonics, indicator minerals, geophysical surveys, and multiple stages of drilling and sampling. Very different from other regions, however, is Canada's surficial environment, in which recent glaciation has caused fresh indicator minerals to be transported hundreds of km. Exploration accelerated in Canada after 1960, first in Ontario and the Arctic Islands, then in Saskatchewan in 1988, and most importantly after the Chuck Fipke - Stew Blusson discovery at Lac de Gras, Northwest Territories, in 1991 that led to the billion-dollar BHP - Dia Met Ekati Mine that opened in 1998. In 2003, production from Ekati is expected to be supplemented by that from the similar and nearby Diavik Mine of Rio Tinto and Aber, currently under construction. These mines will bring Canadian output to over 10% of world supply, and will position Canada with Botswana and Russia as world leaders in production of high quality gem diamonds. There could be other mines as well, as sites across the Arctic and in the south from Alberta to Québec are being explored by an array of companies, including De Beers, other majors, and several juniors.

May 1, 2001

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 D. Y. Li, C. D. Ma, T. Zhou, T. J. Cheng

In this paper, a number of experimental tests are carried out to study the strength difference on rectangular prismatic marble specimens with different height-to-width (H/W) rations. The specimens have a nominal size of 45×15 mm in the compressive cross-section (W×T) and different heights (H = 22.5 mm, 45 mm, 60 mm and 90 mm). It is to say that the height-to-width ratios are equal to 0.5, 1.0, 1.33 and 2.0, respectively. The quasi-static uniaxial compressive tests are finished by a servo-controlled INSTRON machine (the strain rate at about 10-5/s), and the dynamic compressive tests are finished by a diameter of 50 mm cylindrical SHPB apparatus (the strain rate reaching about 101/s). The rock failure process of marble specimens is captured by a high speed camera in order to distinguish the fracture propagation behaviour. It is found that the compressive strengths increase when the H/W ratio of marble specimen changes from 2.0 to 1.0 due to the end clamping effect both for quasi-static and dynamic loads. However, when the H/W ratio changes from 1.0 to 0.5, the apparent compressive strengths decrease both for the two loading conditions. The strength decrease of short marble specimens may be attributed to the change of failure mode from shear to slabbing, which can be identified by the fracture patterns of the specimens. Based on the uniaxial compressive tests, the slabbing strength of the marble was found to be about 40% of its UCS for the specimens with a nominal height-to-width ratio of 2.0. In addition, it is found that the dynamic increase factors (DIF) are affected by the specimen’s aspect ratios. It implies that the same aspect ratios should be used to compare the dynamic and static compressive strength of rocks. Meanwhile, both the static and dynamic tensile strengths of the marble are obtained by the Brazilian disc tests. The ratio of the dynamic tensile strength to the static tensile strength of the marble is about 2.68.

Jan 1, 2015

By J. E. Armstrong

"Pinchi Lake and Bralorne Takla mercury mines; Canada's only producing mercury mines during the past war (1939-1945); occur within the Pinchi Lake mercury belt. This belt is in central British Columbia; and is approximately 150 miles long extending from southeast of Fort St. James northwest to the headwaters of Omineca river.During the field season of 1937 cinnabar was discovered by J. G. Gray of the Geological Survey in Permian limestone on the north shore of Pinchi lake, where the main showings of the Pinchi Lake mercury mine were later developed. Following the publication of Gray's report claims were staked in the spring of 1938, and later that year were optioned to the Consolidated Mining and Smelting Company, and in June 1940 a reduction plant with a rated capacity of SO tons a day was brought into operation. In 1943 the plant had a capacity of more than 1,000 tons a day. The grade of ore treated was reported to average S to 10 pounds of mercury a ton, and production during the years 1940 to 1944 exceeded 4,000,000 pounds. The Bralorne Takla mercury mine, which is 90 miles northwest of the Pinchi Lake mercury mine, was brought into production in November 1943 with completion of a 50-ton mill. During the next 10 months more than 100,000 pounds of mercury were recovered, and the grade of the ore was reported to average 15 to 20 pounds of mercury a ton. During the war, production from these two properties was far in excess of Canadian requirements, and Canada was able to supply the United Kingdom and United States with part of their need.s. Both properties ceased operations during 1944, and, due to an excessive supply of mercury, have not yet reopened. The Pinchi Lake mercury belt lies along a northwest-trending major fault zone called the Pinchi fault zone (Fig. 1). This zone is approximately 150 miles long and varies in width from 200 to 1,000 feet . It forms the northeastern edge of a northwest trending fault belt up to 10 miles or more wide in places. In general the northeastern margin of the Pinchi fault zone represents the contact between closely folded, stratified Permian rock:s on the southwest and Mesozoic formations and Omineca intrusions on the northeast. It seems probable that the fault zone marks the site of major thrust faulting from the southwest and that the Permian rocks moved up with respect to the Mesozoic formations. Intense faulting occurs in the Permian rocks within the fault zone. There the more important faults trend north and northwest, dip steeply west and southwest, and may join a major low-angle thrust fault at depth."

Jan 1, 1954

By Bong Sun You

AZ31 magnesium plate of 300mm in width and 40mm in thickness was produced by horizontal continuous casting machine, and its microstructures were analyzed on the surface and in the plate interior. The defect formation on the surface and subsurface, such as side cracks, buckling, pores and segregation, was very sensitive to the casting condition and processing parameters. Especially, casting speed and secondary cooling were the most dominant parameters to control the solidification behavior of magnesium melt, for example the position and shape of the solid/liquid interface in the mould. The cyclic marks on the surface were obvious because the plate were drawn by 4-step cycle and can not be removed. The average grain size of as cast plate measured as 50-65µm at the near surface and 300-400µm in the center of the plate was relatively small because secondary cooling water was applied to control the surface quality resulting in rapid solidification of the melt in the mould.

Jan 1, 2006

By K. Nagy

To support the implementation of its integrated SHEQ Policy, Cameco has undertaken an environmental leadership initiative with the goal of moving beyond regulatory compliance and significantly reducing environmental impacts in five key areas: air emissions, treated water quality and quantity, energy use and greenhouse gas emissions, and waste generation. To ensure environmental leadership becomes routine business practice, it was necessary to integrate the initiative into Cameco?s programs and management systems at the corporate and operational levels. Operations based environmental leadership strategies and action plans have since been developed, as well as a corporate reporting system to monitor Cameco?s environmental performance.

Aug 1, 2010

By Theophile Yameogo

The rock mechanics literature has documented the challenges, failures and successes of tunneling through weak rocks. Cases usually deal with low RMR rock masses or high stresses in a fractured zone. With the combination of 5MPa water pressure, 14 RMR ground with clay infillings and ground freeze walls, the case of the 510-8225N development drift at McArthur River is certainly much more challenging, especially when high grade uranium production is at stake. The article explains the excavation and the ground control techniques that were used to overcome the challenges of development at the Unconformity in the Athabasca Basin.

Aug 1, 2010

By Robert A. Creaser, Iain Mitchell, Robert L. Linnen

Abstract - The Bermuda Zn-Pb showing is hosted by dolomitized Blue Fiord Formation of Devonian age, located east of the Ensorcellement dome on the Grinnell Peninsula of Devon Island. Fluid inclusions in hydrothermal calcite indicate that the mineralization precipitated from low-temperature, highly saline brines. The ?34S compositions of sphalerite, galena, and marcasite range from 16.1‰ to 35.2‰. Consequently, the Bermuda showing is interpreted to be Mississippi Valley-type (MVT) mineralization. The apparent age of mineralization has been determined by the Rb-Sr method from sphalerite separates, and a Late Devonian age of 357 ± 50 Ma (MSWD=65), with an initial 87Sr/86Sr ratio of 0.7083 ± 0.0020 is indicated. This date, within error, is the same as the Polaris deposit. This suggests that the mineralization formed during the Ellesmerian Orogen, although it is also possible that mineralization is associated with extension, related to the opening of the Sverdrup basin. The strontium and sulfur isotopes and fluid inclusion analyses indicate the involvement of a brine that acquired its salinity from interaction with evaporites, lower in the stratigraphic succession. The Polaris mine is the type deposit in the Cornwallis Zn-Pb district and is hosted by the Thumb Mountain Formation. The results of this study are significant because they demonstrate that regional brine movement is more widespread than previously recognized, and that MVT mineralization in the Cornwallis Zn-Pb district is not restricted to the Thumb Mountain Formation.

Jan 1, 2004

By J. H. Rickard, D. H. Watkinson

"Abstract - Detailed petrographic and quantitative (electron microprobe, SEM-EDS) mineralchemical analyses of sulfide ore from the 100 orebody at the Copper Cliff North mine, Copper Cliff, Ontario, reveal numerous stages of ore development. Sharp contacts between weakly mineralized quartz diorite and blebby to massive sulfides indicate multiple intrusive events within the Copper Cliff offset dike. A spatial association of sulfides and hydrous minerals, such as amphibole, biotite, chlorite and epidote, suggests that most primary ore has been affected by later hydrothermal fluids. Sulfides are often enclosed or bordered by these secondary silicate phases. The ore consists primarily of pyrrhotite, pentlandite, chalcopyrite, with trace michenerite, cobaltite/gersdorffite, irarsite, hessite, tsumoite, and bismuth tellurides.Geological and petrological comparison of the 100 orebody and the adjacent 900 and 890 orebodies has revealed distinct similarities in ore distribution. Data show that the 100 orebody is depleted in platinum-group elements (PGE) relative to the 900 orebody. Platinum-group elements from the 100 orebody may have been hydrothermally remobilized and partly emplaced in the 900 orebody, in adjacent veins, or in magmatic breccia. Analysis of Cu, Ni, and PGE assay data of ore samples has characterized their distribution among the eight different ore textures in the orebody. There is a strong association between Pt and interstitial sulfide, and to a lesser extent massive sulfide, but little correlation between chalcopyrite-rich ore and PGE in the 100 orebody, unlike many other deposits in the Sudbury region."

Jan 1, 2001

By R. Gordon, J. Palich, W. Qian

The EarthProbe DCIP system deploys tightly spaced electrodes connected to a centralized data acquisition system that enables arbitrary selection of current and potential electrodes through relays. Rapid data collection (approximately 1000 readings per hour) and advanced signal processing allow for efficient use of conventional and novel arrays and the removal of natural and cultural noise. What is unique about the system is its electrode and borehole cable design, which allows seamless integration of borehole and surface measurements. EarthProbe operates in four configurations - surface, borehole, borehole-to-borehole, and surface-to-borehole (a variant of the borehole-to-borehole configuration).

Jan 1, 2011

By William H. Emling

With profitability pressures in heavy industry increasing, many producers are turning to predictive maintenance as a means of harvesting untapped value from their production assets. Corporations are losing their maintenance and processing core competencies through attrition. As capital budgets are being trimmed, manufacturers are consolidating operating units into fewer, more profitable routes. Maintenance functions, however, typically receive low priority when investment is made, since many companies consider maintenance costs as ?overhead?. Condition-based monitoring, integrated to Level I and Level II process inputs, is seen as the most cost-effective solution to the implementation of predictive maintenance strategies. This paper will review the evolution of preventive and predictive maintenance programs, highlighting examples of successful application of integrated condition monitoring.

May 1, 2001

By C. E. Cartwright

That the construction of the Pacific Great Eastern railway has not been accompanied by an immediate and great development of traffic is not due to lack of natural resources in the district traversed, but to conditions that have delayed their development. Prior to the commencement of construction of the railway there was no inducement to prospect for any other mineral than gold, on account of lack of transportation. The war began soon after the commencement of construction; diverting practically all capital that might have been available for opening up the country; and since the war, capital has continued shy of new investments. If the war had not occurred it is probable that prospecting and development would have been carried out concurrently with the railway construction. Moreover, much of the district is covered deeply with drift, marine and alluvial deposits, rendering prospecting for lode mines a more expensive and slower proceeding than can generally be undertaken by the ordinary prospector, without capital. On the other hand, the presence of large porphyry dykes, granitic intrusions, and the finding of rich float in places are indications that rich miIY.ral deposits probably exist in several localities in the Lillooet district, in the Cariboo proper, and also nearer the coast. Two or three mines producing the tonnage of the? Britannia would materially alter the earnings of the railway and pay interest on the bonds. There are, however, other possibilities, in addition to large metaliferous mines, in the non-metallic minerals of the district.

Jan 1, 1925