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By W. G. Q. Johnston, J. S. Fox

"A semi-continuous belt of Aphebian magnesian extrusive and related sub volcanic rocks has been delineated by the authors over a distance of 150 kilometres in the central La Ronge lithostructural domain in Saskatchewan. They range in composition from peridotite to basalt and attain true thicknesses of up to 800 metres. For the most part, they are confined to a basal position in the La Ronge/Wasekwan metavolcanic sequence, and appear to have been extruded onto sialic crust. However, at Lynn Lake, Manitoba, in the eastern continuation of the domain, similar rocks seem to be found only at a relatively high stratigraphic level.Although metamorphism seems to have obliterated any quench textures that may have existed in these rocks, ultramafic pyroclastics, pillows and amygdules as well as intercalated, fine-grained clastic sediment attest to the volcanic nature of these rocks. Bulk chemical analyses indicate that these rocks are heterogeneous, with komatiites, tholeiitic picrites and even rocks with some of the characteristics of boninite all being present. The close temporal and spatial relationship of ""boninites"" and komatiites in the belt may suggest a high degree of Aphebian mantle inhomogeneity in the domain.Nickel-copper mineralization has been found in differentiated tholeiitic stocks within the La Range domain (e.g., at Lynn Lake), but none has yet been found in the ultramafic volcanics. However, the tholeiitic picrites do host one economic gold deposit - the Agassiz Mine at Lynn Lake .Because of the depleted nature of their mantle source, the ""boninites"" of the domain are not considered to be likely hosts for mantle-derived nickel sulphide mineralization. However, the opposite is true of the komatiites, and this points to the need for whole-rock geochemistry in setting priorities for nickel exploration in the belt. In contrast, all of the magnesian rocks of the domain probably have the same gold potential. Inasmuch as the geophysical response to gold mineralization in the domain is likely to be unpredictable, lake-sediment geochemistry, followed by base-of-till and/or alteration oriented lithogeochemistry, should be emphasized during gold exploration."

Jan 1, 1981

By A. Mortazavi, H. Nasab

"The storage of petroleum products on surface is associated with difficulties and limitations. Accordingly, a viable alternative is to excavate underground space in rock and provide a safe way for oil storage. Soft rocks such as salt domes provide good conditions from environmental and operational points of view. The potential for high-volume storage and low permeability are encouraging aspects for oil storage in salt domes. The complicated shape of oil storage caverns, the complicated behavior of salt rocks, and boundary conditions associated with large underground openings are important challenges in the design of oil storage caverns. The aim of this paper is to delve into the stability and deformation mechanisms of storage caverns created in salt domes. A parametric study of effect of the cavern size, orientation, and depth is carried out as a function of ground stress regime. The stress field and deformation mechanisms are calculated for each case aiming at providing design guideline.INTRODUCTIONOne of the most popular soft rock that is used for underground oil storage is salt rock (halite). Salt rock has particular characteristics which makes it suitable for oil storage. Salt rock has several advantages for oil storage, these are: high production rate, high degree of availability, short filling period, high level of safety and low permeability [1]. The low permeability is due to the fact that halite deforms in a plastic manner over a wide range of pressures, temperatures and rates of deformations. This property prevents joints or gaps opening up in the formation, thus preventing the escape of liquids and gases. The state of stresses around the cavern in salt domes depends on the depth of the cavern (initial stresses and rock mass temperatures are increasing with depth), the in-situ stress state within the rock mass, and the internal oil pressure in the cavern. Furthermore, the salt creep behavior and the cavern geometry are influencing stress redistributions during loading and unloading phases.Rock mass structure, cavern geometry, material behavior and cavern operation patterns require complex physical models to describe the load-bearing behavior of the geomechanical structure. The determination of stress, strain and deformation in the rock mass due to cavern construction and operation are complex problems which can be evaluated employing numerical tools such as the Finite Element Method (FEM) or Finite Difference Method (FDM). In this study, the finite difference method was used to evaluate the behavior of oil storage cavern in salt rock."

Jan 1, 2015

By Z. Y. Ma, H. Y. Yang

The process of microwave-ultrasound assisted leaching of valuable metals from copper anode slime was proposed in this paper. Design of experiments has been used to study the effect of the main leaching parameters, such as microwave power, ultrasound power and reaction time. The central composite design (CCD) was used to predict the maximum leaching efficiency of copper, tellurium and selenium. The experimental data obtained were fitted to a second-order polynomial equation, and they also were analyzed by analysis of variance (ANOVA). The 3-D response surface plots and the contour plots were applied to determine the optimal conditions. The optimum conditions of microwave-ultrasound assisted leaching process were: microwave power 834W, ultrasonic power 638W and reaction time 403s. Under these conditions, the experimental leaching efficiency of copper, tellurium and selenium were 98.88±0.56% 98.96±0.78% and 98.57±0.67%, respectively, which agreed well with the predicted values.

Jan 1, 2014

By S. D. Tolgyesi

Kidd Creek Background ? Located in Northern Ontario, Canada ? Underground base metal mine ? Operating since 1966 ? Total of 125Mt mined to date (2.43% Cu, 6.60% Zn) ? Current plan at 2.4Mt/Y (6575t/D) Current Practices ? Evaluating stope margins to ensure that value is added ? Scheduling sulphide and Cu stringer ore to limit oxidation in passes ? Scheduling to maintain uniform grades to concentrator ? (SOPs highlight problem stopes on mine plans, and limit blast sizes in those stopes which may contain sulphides prone to oxidation) ? Scheduling high-Pb stopes to avoid spikes to concentrator ? Providing weekly, monthly and long-term forecasts ? Reconciling mine and mill production ? Underground grade and dilution estimates by mine supervision ? Terminate mucking when grade becomes sub-economic ? Laser cavity surveys to provide feedback and improve Designs Cut-off Grades ? Ore value is obtained from copper, zinc and silver ? Ore outlines at 2% copper equivalent used to guide stope planning; sulphide outlines obtained from contacts while copper stringer outlines drawn from block model (kriged) ? Datamine block model and CADD software used to evaluate alternative stope shapes ? Stopes classified as waste, incremental, or full-cost based on margin calculations for each stope ? Incremental ore may be mined if it does not displace fullcost Ore Conclusions ? Grade control remains an important function for optimizing the ore extraction at Kidd ? The scope of the function has changed to a scheduling focus ? A change in grade control practices over time has not led to significant changes in concentrator feed ? The lead and iron sulphide content of the ore display upwards trends and may require more attention in the future ? The key function of field observations has shifted to flagging exceptions and terminate mucking at grade cut-off

May 1, 2003

By R. J. McCarthy

In-pit Crushing and Conveying (IPCC) is increasingly being considered by mining companies as a means to reduce their dependence on trucks and thus, fuel, tires, labour, etc. There is potential for great savings in operating costs which ultimately can mean better economics for a mining project. Vale has considered the application of IPCC at its Moatize coal project in Mozambique. Up to three studies have been conducted with the latest, at a pre-feasibility level, showing some promise. This paper explores the mine planning and IPCC engineering elements required in an IPCC study, their application to the Moatize project, and the drivers which most impact the viability of IPCC at Moatize.

Aug 1, 2013

This paper presents the results of research aimed at proposing new solutions in the area of belt conveyor elements. Many factors, such as energy consumption costs, and operating costs of belt conveyor elements, including belts, idlers and drives have an impact on the operational costs of conveyors. The paper presents special tests of new materials for the bottom cover of an energy-saving belt conveyor, which decrease rolling resistance. It also presents large-scale in-situ tests of a high-output belt conveyor for the purpose of simultaneous measurements of various types of conveyor belts (standard vs several energysaving types) under typical operating conditions of a lignite surface mine. Improvements in materials used for the bottom belt covers, supported by specially developed comprehensive tests of the new types of belts have provided valuable results of various proposed solutions. Since the tests of belts were done at exactly the same time and in the same operating conditions, direct comparison of the results is valid and should lead to a substantial decrease in the conveyors? drives? energy consumption, which will improve the effectiveness of belt transport and minimize its negative influence on the environment.

Aug 1, 2013

By N. W. Xu, M. D. Wei, F. Dai, B. Li

"Chevron notched samples achieve general acceptance for measuring the Mode-I (opening mode) fracture toughness of rocks. The cracked chevron notched semi-circular bending (CCNSCB) sample, which is developed from the International Society of Rock Mechanics suggested the cracked chevron notched Brazilian disc method, has recently received much attention. However, these chevron notched methods have not been fully mastered, some ideal assumptions based by their theories and formulas, such as the straight-through crack assumption (STCA), have not been verified detailedly. Fractures of CCNSCB specimens were numerically simulated considering different heterogeneities, geometrical and mechanical parameters. The results show that, the real fractures of CCNSCB specimens are never satisfied with the STCA. In fact, micro fractures not only occur in the notch tip but also the two chevron edges. Consequently, the crack front features prominently in a shape of parabolic curve, far from being straightthrough. Moreover, curvature of the crack front is only affected by shape of the chevron ligament. Cracks usually start from two sides of the notch tips rather than center of the notch width, and propagate deviating from the postulated fracture routes. These fracture mechanisms induce errors with the measurements, and thus more attentions should be paid to the real fractures of the chevron notched samples for measuring fracture toughness more accurately. INTRODUCTIONWith the increasing requirement of people for resources and energies, frequent rock engineering activities have been conducting, such as underground excavation, oil exploration and deep burial of nuclear waste. Many problems appear in rock fracture. Consequently, there are more and more attentions paid in rock fracture mechanics due to its broad application prospects for solving these engineering problems. Since Mode-I (opening mode) fracture is the most common failure mode in rocks, Mode-I fracture toughness is a primary parameter to predict rock mechanical properties in actual engineering, and thus its accurate values are necessary to the researches of rockburst, rock mass slope stability, rock cutting, hydraulic fracturing, tunneling, et al. Therefore, it is thus significant to evaluate and study relevant methods to obtain the reliable value."

Jan 1, 2015

By David E. Pearson

"Western Canadian coking coals are located in the Rocky Mountains arid foothills of British Columbia and Alberta. They are typical of non-marine coals, characterized by total sulphur contents of less than one per cent and with ash contents of 10-30 weight per cent. This mineral matter is composed principally of kaolinite and quartz.The petrographic compositions of most of the coking coals which constitute the 2.065 billion tonnes of British Columbia's measured reserves, and the compositions of the metallurgical coal currently exported from Alberta, show them to be rich in the inertinite macerals, macrinite, fusinite and semifusinite. When the mean maximum reflectance of vitrinite in oil/Romax) is used as the coal rank parameter, this high inertinite content is reflected in the lower volatile-matter yields, but the relatively inert character is also displayed by lower free swelling indices (PSI), lower maximum dilatations, lower maximum fluidities and lower coke strengths than other coals of the same rank, but richer in the reactive macerals, vitrinite, exinite and semifusinite. Despite these reduced values in the so-called caking tests, inertinite-rich coals produce strong coke.A system of classification of coking coals is introduced which is based on rank, as indicated by Ro max, and either petrographic composition, maximum dilatation, maximum fluidity or, to a lesser extent, PSI and volatile-matter yield. Six principal coal groups can be distinguished among coking coals using this versatile classification. Inertinite-rich coals are assigned to the Keystone Group (GI), Balmer Group (G3) or Moura Group (G4), each group being named for a coal typical of that population ofcoals. Reactive-rich coals are assigned to the Pittston Group (G2), Kellerman Group (G5) or Big Ben Group (G6). A multiple-regression analysis of coal quality versus price shows how the value of coking coal in the Japanese market appears to be related to reflectance and the free swelling index, and confirms the economic viability of the classification.British Columbia's measured reserves of coking coal contain representatives of four of these groups; Balmer Group (73%), Moura Group (/6%), Pittston Group (3.4%) and Kellerman Group (7.6%).This analysis of the quality of Western Canadian coking coal indicates that despite the need for large proportions of inertinite-rich coking coal in blends produced in the Japanese steel industry, there is nevertheless a demonstrated overabundance of Balmer Group and Moura Group coals available to the international coking coal market."

Jan 1, 1980

By Narasimha Mangadoddy, Balraju Vadlakonda

"Bubble size distribution, bubble rise velocity and gas and solids hold-up are the key major hydrodynamic parameters that are extensively used for column flotation design and performance evaluation. The distribution characteristics of mean gas hold-up is studied using electrical resistance tomography (ERT) coupled with pressure transducers (PT) in column flotation. The ERT technique facilitates non-invasive and nonintrusive visualization of different flow regimes even in the presence of particles in a column flotation. The effect of superficial gas velocity, feed flow rate and slurry height in the column on mean gas hold-up and its radial distribution has been analysed for both two-phase and three phase flows. Experimental results show ERT coupled with PT is suitable as an online monitoring tool to provide useful information on the three-phase flow hydrodynamic parameters of the column flotation. The tomography images, which were generated using a modified sensitivity back projection algorithm, are employed to explore the influence of parameters in two phase flow in column flotation. Mean gas and solids hold-up values extracted from ERT have been critically analysed for the column operating in various flow regimes. Gas hold-ups and solid hold-ups results using ERT are in very good agreement with conventional estimation and correlations obtained using pressure transmitter methods. Meanwhile, the results show that the gas hold-ups in the centre region increase constantly with an increase in the superficial gas velocity, whereas solid hold-ups distribution is very heterogeneous for high gas velocity. Furthermore, the results also indicate that ERT is a very powerful tool for diagnosing the 'inside' flow behaviour of gas –liquid–solid three phase flow in columns operating for a wide range of flow regimes.INTRODUCTIONColumn flotation is perhaps the most significant technological innovation in flotation machinery and its successful introduction in mineral processing plants. There has been a lot of attention in understanding the various mechanisms that take place during operation. Due to many reasons column flotation has been found to yield better performance than conventional flotation cells, particularly with fine particles (Honaker & Mohanty, 1996). Due to complex flow behavior in nature, the performance of column flotation influenced by on flow characteristics of the process, (Jena, Biswal, Das, & Reddy, 2008). Previously basic research is carried out to evaluate the effect of the hydrodynamic parameters on performance of column flotation (Finch, J.A.;Dobby, 1991). Many techniques have been developed that could be used to experimentally analyse the hydrodynamics of column flotation. Tomography techniques are well sound to investigate the hydrodynamics for process equipment. Among that, Electrical resistance tomography (ERT) has been used in various industrial investigations for visualization of the concentration profiles and characteristics of the fluid dynamics in gas–liquid two-phase systems (Wang, Dickin, & Mann, 1999; Williams, R.A; Wang, 2000). ERT is an imaging technique to analyse the internal flow behavior non-intrusively. ERT provide very useful tools for measuring and monitoring of column flotation process on line. Due to its high speed capability, low cost measurement, robust sensors, ERT is considered to be the most powerful tool among other tomography techniques such as positron emission tomography (PET), magnetic resonance imaging (MRI), optical and infrared tomography. Application of ERT has extended in process systems due to its improved speed of data acquisition, sensitivity, flexibility and noise immunity. In multiphase flow of bubble columns, gas hold-up and solid hold-up are explored by using the coupling of ERT and difference pressure method (Jin, Han, Yang, & He, 2010)."

Jan 1, 2016

By Dennis Z. F. Mraz

"Because rock salt and pot ash formations contain particles capable of elastic deformation, the material has usually been compared with various rheological models containing elastic elements. Extensive laboratory testing of salt and potash samples resulted in various theoretical conclusions based on conditions quite different from those in a deep mine. It is felt that sufficient data have now been collected from underground measurements and observations to demonstrate the inelastic behaviour of salt masses in a deep mine. The conditions in deep salt strata can be defined as near hydrostatic, because the acting pressures are very high compared to the negligible elastic limit of the salt. The pressure field and creep around the single opening is a function of its shape, size and age. The same factors, together with extraction, determine the behaviour of the mining a rea. The application of the correct analytical method in mine design can significantly improve the excavation techniques and predetermine the long-term behaviour of openings."

Jan 1, 1973

By C. -G. Berg, J. T. Tuominen

Since the beginning of the 20th century, energy efficiency in copper smelting has been improved by a factor of 30 as a result of adopting autogenous smelting processes with more and more efficient waste heat recovery systems, increasing use of oxygen enrichment and countless smaller improvements. Nevertheless, energy in the form of electricity and fuels continues to be the biggest contributor to smelter operating cost. Metallurgists around the world are under constant pressure to find ways to save those precious megajoules wherever they can. One area that is often neglected is the removal of water contained in concentrates. Copper flotation concentrates, as delivered to a smelter, typically contain some 8–12% moisture. This moisture must be removed and the only way to do this is by evaporation, which consumes a lot of energy. Several studies have shown that the most efficient way of removing this moisture is to use a steam- heated indirect dryer—the least efficient way being the feeding of wet concentrate directly into a smelting furnace. Even in the most efficient smelters that employ modern steam drying, the energy needed to remove the moisture from the concentrates constitutes over 15% of the total energy consumption of a smelter – acid plant complex. The major steps that have been taken in the past to lower the energy consumption of moisture removal are the use of drying in general and the adoption of steam drying. The energy efficiency of concentrate drying has been improved by 25% over the last 20 years. The latest giant leap in this area, the Kumera Heat Recovery Dryer, is the result of Kumera’s long-term development in improving the efficiency of concentrate drying. The Heat Recovery Dryer is a novel application of steam drying that uses the waste heat from dryer exhaust gas for drying concentrates, thus, cutting the energy consumption by a further 30%. This paper discusses energy consumption in copper smelting in general and analyzes the energy consumption of concentrate drying in detail. Different dryer types are compared especially from the perspectives of energy consumption and environmental emissions. Applicability of different energy sources for drying is evaluated and discussed. The principle of the Kumera Heat Recovery Dryer is presented along with results from extensive continuous pilot plant tests. Potential applications and the feasibility of Kumera Heat Recovery Drying technology are discussed.

Jan 1, 2019

By J. Currie, J. McManus, R. Chenier

"Cominco Copper Division's Valley Mine is located in the Highland Valley of British Columbia, approximately 275 km by air northeast of Vancouver. The nearest towns are Logan Lake, located IS km to the east and Ashcroft, located about 50 km to the northwest.Preproduction stripping of rock and overburden at the Valley Mine's Lake Zone Pit began in mid-1982 following a decision to discontinue mining in the adjacent Jersey Pit. Equipment and mining methods were carried over from the Bethlehem Copper operations which, with Valley Copper Mines, were merged into Cominco in December 1982.Blasting practices, as carried over from the Bethlehem pits, were designed to provide the fine fragmentation required to meet production requirements using the Bethlehem crusher. However, after mining the first few benches of the Lake Zone Pit, it became apparent that overblasting at the pit limits was causing a number of bench failures, as well as contributing to an over-all reduction of the material strength of the rock mass forming the southwest wall of the pit.With present ultimate pit plans calling for the southwest wall to be as high as 300 m, Valley staff realized that potential slope stability problems should be dealt with as early as possible. This philosophy would enable experimentation on phase pit walls in order to attain the optimum slope angle on the ultimate pit wall.As part of an over-a ll slope stability program, a controlled blasting program was initiated at the Lake Zone Pit in March 1983. In this program, Valley engineering and production staff worked together with Golder Associates in establishing design criteria and evaluating the results. This program resulted in a marked improvement in the soundness of pit walls while maintaining the required degree of fragmentation."

Jan 1, 1985

By L. Szecowka, M. Poskart, Siwka M. . J.

Oxides of nitrogen, created during combustion, are the most hazardous components of atmospheric pollution. However, it is possible to limit the negative influence of hazardous components on the natural environment. An experimental appartatus was built to determine the influence of the following "primary methods" on the reduction in concentration of NOx: air staging, reburning and flue gas recirculation. The influence of the simultaneous usage of the primary methods on reduction in NOx emissions was also examined. A significant increase in the efficiency of NOx reduction was achieved in two cases.

Jan 1, 2004

By A. R. Trusiak, C. Bazin, D. Hodouin

"The On-Stream Analyzer has proven, and is still proving to be, an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the analyzer results by using a real-time material balance program to calculate the mass flow rates within the streams of a circuit for process control, analysis and optimization as well as for the detection of sensor malfunction. The material balance algorithm improves measurements and give good estimates of unmeasured variables during normal operating conditions. The potential and limitations of the method are illustrated using results of an application to the Line 3 flotation circuit of Brunswick Mining and Smelting, New Brunswick.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants isincreasing. Commercial OSAs include a sampling system that collectssamples from various streams of a circuit and exposes thesamples to an X-ray beam. The sample then generates X-ray pulsesthat are converted into assays using multilinear regression programs(Leroux and Franklin, 1994). The estimated assays arepassed to the flotation operators via operator consoles, or to controlloops of various degrees of complexity (McKee, 1991), whichmanipulate reagent addition, aeration rate or froth thickness toensure an adequate operation of the plant. Although this applicationrapidly pays for the purchase of the OSA, one should ask:""Could we get more from the OSA?"""

Jan 1, 1995

By W. Lodge, G. Rasmussen

"The carbon-in-pulp (CIP) process has been the dominant gold recovery technology since the 1980s. During all this time carbon measurement, and control of the carbon transfer pumps has been largely manual in nature. Such manual operation inevitably limits process efficiency, potentially resulting in higher gold solution losses, and higher cost of circuit operation. Based on the authors’ experience, average plant solution loss is in the range of 0.02-0.03 ppm Au, as opposed to the general industry target of 0.01 ppm Au or less. Gekko Systems, in conjunction with Curtin University’s Gold Technology Group, has developed a carbon concentration meter, the ‘Carbon Scout’ meter. The meter automatically measures carbon concentration in all tanks, providing more frequent and more precise data. Combined with SIMCIL, a CIP circuit process model which is used to determine the optimum set points for the circuit, the meter should ensure lower gold solution losses, and more efficient operation of the carbon circuit. This paper will review they critical factors for good carbon management, the development of the meter and results from the first plant installation. Additional benefits of the Carbon Scout, including improved health and safety and the opportunity to measure other key variables in the leach/adsorption circuit from one central location will also be described.INTRODUCTION The carbon-in-pulp (CIP) process was first introduced to the gold industry in the early 1950s at the Carlton Mill in the USA (Fast, 1988), with the modern version of CIP becoming fully developed with large scale installations in South Africa in the late 1970s (Laxen, 1982). CIP quickly became the technology of choice for new operations, and for the retrofitting or upgrading of existing operations. In the 1980s the carbon-in-leach (CIL) circuit configuration became the process design of choice due mainly to its lower capital costs. With 40 years of operational experience, CIP/CIL for gold recovery is now mature a technology, whose operations and limitations are well understood. To extract further efficiencies from such technologies, by improving recoveries and/or reducing operating costs, is challenging and may require new approaches to circuit management. Gekko Systems, in association with the Gold Technology Group at Curtin University, has developed the Carbon Scout, an automated carbon measurement device. This device replaces manual measurement of carbon concentration in carbon adsorption tanks, providing more frequent and more accurate data for control of the CIP process. Data from the Carbon Scout can be used to automatically control the carbon forwarding pumps."

Jan 1, 2018

By D. Adiguzel

In this research, providing the sustainability of production quality was aimed for a quarry which is located in Istanbul western part of Turkey and producing concrete aggregates with different types of rock. First, research field was divided in 3 different areas in accordance with the geological differences and parameters that control their product quality, limit values of standards and effect levels were determined. Concrete aggregate conformity tests which are stated in international standards were applied on samples which were taken from these 3 different areas and physical, geometric and chemical properties of each rock type were revealed. The properties of the 3 different types of rock which were produced in the quary were determined and the binary blends were composed. Blending studies were conducted with linear programming technique. In the linear programming model, the cost of aggregate production was aimed to be minimal. The limit values that meet literature and national standards for usability of aggregates in concrete were defined as constraints in the linear programming model and evaluated with objective functions, thus the most suitable aggregate blends were composed. In conclusion, to provide the sustainability of product quality, the most appropriate product blends were composed for the research field and the usability of this model for those quarries were revealed.

Aug 1, 2013

By A. V. Lyamin, J. P. Wang, A. J. Li, Z. Qian

"For general stability analysis of rock slopes, rock mass strength and rock mass disturbance are definitely should be considered. In addition, the impact of earthquakes must be taken into account. In fact, the rock mass strength is very difficult to be assessed which causes the difficulty of analysing rock slope stability. Therefore, an empirical failure criterion, the Hoek-Brown failure criterion, has been proposed. It is one of the most widely accepted approaches to estimate rock mass strength. The rock mass disturbance is important and was found having significant influence on evaluating rock slope stability, especially for rock slope with poor quality rock mass. In the Hoek-Brown failure criterion, the disturbance factor can represent the level of the rock mass disturbance which would provide a reasonable basis for estimating rock mass strength.This research will not only discuss the slope factor of safety, but also consider the influence of the seismic force on rock slope stability assessment using pseudo-static method. In practice, only horizontal seismic coefficient is used. Various magnitudes of the disturbance factor and recommended blasting damage zone thickness are also taken into account. The blasting damage zone thickness considered ranges from 0.5 to 2.5 times of slope height. The research results have potential to be extended and then sets of comprehensive stability charts can be provided for the rock slope stability evaluations. They will be convenient tools for practising engineers. In this study, finite element upper bound and lower bound limit analysis methods are employed. Their applicability has been investigated in some previous studies. The differences between upper bound and lower bound solutions are less than ±10% which would provide reasonable and acceptable range for rock slope stability safety factor estimation."

Jan 1, 2015

By W. Dietzel

Fracture mechanics based techniques are used to gain insight into the phenomenon of stress corrosion cracking (SCC) and to develop guidance for avoiding or controlling SCC. From constant extension rate experiments under rising load or rising displacement conditions the susceptibility of high strength steels, aluminum, magnesium and titanium alloys to SCC and hydrogen embrittlement can be assessed. Such tests on pre-cracked specimens are also well suited for studying the mechanisms leading to SCC by employing appropriate models for the degradation of metallic materials which take into account the uptake of atomic hydrogen from the corrosive environment. Measurements of crack growth resistance curves using the crack tip opening displacement as fracture parameter can be compared with simulated R-curves obtained from modeling of the mechanism of hydrogen embrittlement. The materials investigated are a high strength steel and a magnesium alloy both exposed to environmental conditions which fostered the uptake of hydrogen.

Jan 1, 2010

By W. A. Jones

"The Ross mine, a subsidiary operation of Hollinger Consolidated Gold Mines, Limited, is near the north end of lot 1, con. II, Hislop tp., Ontario. The property comprises the north half of lot 1, con. II, and the south onethird of lot 1, con. III. It is readily reached by a good motor road from the village of Ramore, 7 1/2 miles to the southeast on the Ontario Northland railway. The mine is being developed to a depth of 1,500 feet, and the current daily production rate is approximately 300 tons. From the inception of operations in March 1935 until December 31, 1945, 692,000 tons of ore, with a total value of $5,762,685, was milled . The silver to gold ratio of 1.48 to 1 is unusually high for Ontario gold mines.TYPE OF 0REBODIES AND MINERALIZATIONThe orebodies consist of lens-shaped and pipe-like stringer lodes and tabular vein zones composed of parallel quartz stringers. The host rocks are steeply inclined eruptive breccias and tuffs, striking N.70°W., intruded by very small stocks of red syenite. The orebodies appear to be spatially related to an intricate system of fault planes. Hydrothermal alteration is widespread and is not zonally related to individual quartz stringers. The wall-rocks contain abundant fine-grained pyrite, but gold is confined to the quartz stringers.RELATIONSHIP TO REGIONAL STRUCTURELack of outcrops has prevented the detailed mapping of the Keewatin complex in the vicinity of the Ross mine with the degree of success that has been achieved in the Porcupine area.A northwesterly trending belt of slates and greywackes, bounded by faults, forms the central part of a broad anticlinal arch about 3 1/2 miles north of the Ross shaft. Lava flows forming the south flank of the structure face south toward the mine. If the sediments are to be tentatively correlated with the large areas of Keewatin slates and greywackes of the Porcupine area, it must be assumed that they are younger than the lava flows and that they have been down-faulted."

Jan 1, 1954

By Siavash Zamiran, Abdolreza Osouli

"One of the most concerns of room and pillar mining system is subsidence of the ground surface due to coal mining particularly in room and pillar mines. Subsidence of ground surface is a result of floor, pillar, or roof failure of the mine. At the same, due to many difficulties associated with surface disposal facilities of coal refuse, some mining companies are trying to use underground space as a disposal storage place. In this study, stability and subsidence analyses of an underground coal mine located in the Illinois Basin are conducted. This room and pillar mine was abandoned and later on was used as a storage place to accommodate the coal fine refuse with slurry backfilling method. The geological stratigrophy and geomechanical properties of the mine floor and roof were collected. Floor and pillar stability analyses were conducted for areas with various extraction ratios. The stability of the mine was evaluated both prior and after slurry backfilling. The floor and pillar stability analyses results of the mine due to moisture exposure after slurry backfilling are discussed. The subsidence potential due to mine failure is also evaluated.INTRODUCTIONA typical lithology of coal seams in the Illinois Basin consists of weak underclay stratum. The immediate weak underclay causes frequent floor instability problems in Illinois underground coal mines. There are two different stages in assessing floor stability of the mines where slurry backfilling is planned. The first stage is during the mining operation when weak underclay layer squeezes under pillar stress and results in punching or bearing capacity failure. The second stage is after slurry backfilling. During this stage, the slurry material soaks non-durable floor layers and causes strength reduction in floor material. Pillar stability conditions should also be taken into account during both the operational period and after the slurry backfilling."

Jan 1, 2015