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By Erica J. Wanless, Ghislain Bournival, Seher Ata, Jose Hamilton Tavares

In froth flotation valuable particles are captured by bubbles and transferred to a froth layer where bubbles are in close proximity. Bubble coalescence frequently occurs in flotation, especially in the froth layer. The coalescence of two bubbles causes a release of energy, which may expel particles from the bubble surface. A series of experiments were carried out to determine the effect of bubble interfacial properties on the detachment of particles upon the coalescence of capillary-held bubbles of 2 mm in size. The interfacial properties of the bubbles were changed by the addition of low molecular weight alcohols, namely 1-pentanol or methyl isobutyl carbinol (MIBC). Using esterified glass particles (? = 43 °) with a 10 % and 90 % cumulative passing diameter of 47.2 and 92.5 µm, respectively, as model particles, it was found a certain concentration of frother, different for each additive, is needed in order to observe a reduction in the detachment of particles. In the presence of frother, the detachment was evaluated at approximately 65 % which was a considerable reduction in the detachment compared with the value of approximately 85 % found in the absence of frother. Frother molecules changed the properties of the airwater interface. Upon the coalescence of two bubbles, the release of energy caused the merged bubble to oscillate; effectively resulting in the detachment of particles. The addition of frothing agents augmented the elasticity of the bubbles, which appeared to be related to the detachment of particles. Whereas frothing agents are generally used to prevent bubble coalescence and stabilise the froth phase, only transient stability is imparted. The results suggested that an additional role of frothers in flotation is to decrease the detachment of particles from bubble surfaces. The type and concentration of frother can be strategically selected to improve metallurgical recovery as an economic incentive.

Jan 1, 2016

By Adrian Dance

Newmont Ghana Gold Limited?s Ahafo operation have been working with Metso Process Technology & Innovation (PTI) since early 2009 to increase mill throughput from a combination of controlled blasting practices and optimised primary crusher and grinding circuit conditions. For such Mineto- Mill projects, PTI?s methodology is termed Process Integration & Optimisation (PIO). Ahafo operate a SAG mill, ball mill and pebble crusher (SABC) circuit that processes a range of primary ore of varying hardness from different pits which is blended with soft oxide material. The PTI study focussed on ball mill limited material from the Apensu open pit. Following a benchmarking study of all blasting, crushing and grinding practices in January 2009, PTI recommended changes in both blasting and crushing conditions in order to generate a finer feed size to the SAG mill. Additional operating changes in the grinding circuit were recommended. A series of trials were conducted in November 2009 where three blasts were fired using a different blast design (hole diameter and explosive type) in the same area of the Apensu pit as the benchmarked material in January 2009. Top and bottom benches (or flitches) from each blast were sent exclusively to the grinding circuit and the material was tracked using PTI?s SmartTag? system. The results from the six trials showed a significant increase in primary ore throughput at a reduced blend of oxide material. Ahafo have since standardised on these modified blasting conditions for all Apensu ore zones and have been able to sustain higher throughput compared to historical performance on similar material. This paper summarises the phases of the PIO project, the changes made in operating practices and the outcomes of the blasting trials that validated the predicted increase in mill throughput.

Jan 1, 2012

By L. H. Shang

The 319 Al-Si alloy is one of the most prominently used aluminium-based alloys in motor vehicle and engine applications, Microporosity present in 319 alloy castings reduces the load bearing capacity of the castings, The quantitative prediction of microporosity levels in Al-Si castings has been a subject of much interest for several years. In this research a new criteria function, tf 1,98 R13° (tf: local solidification time, R: cooling rate) was developed by multiple regression analyses, correlating thermal data from simulation studies to experimentally obtained microporosity values. This new criteria function gives a general prediction of microporosity in 319 Al-Si castings.

Jan 1, 2005

By Eric Pirard

"A mineralogical and trace element analysis was performed on the Küre historical slags in order to evaluate the possible recovery of copper and cobalt. Reflected light microscopy, electron microprobe and image analysis were combined to determine the Cu and Co distribution in the slag.The results indicate that 81% of the total cobalt is chemically combined in the fayalite whereas only 3.4% is in the mechanically entrapped sulphides. The remainder being in hercynite and wiistite. On the other hand, 95% of the total copper is in the sulphide phase.This kind of applied mineralogical investigation gives invaluable information when it is performed preliminary to metallurgical experiments.IntroductionThe recycling of metallurgical slags is a growing business. The operation is directed toward recovering base metals (Cu, Pb, Zn), and by-products (Floyd and Mackey, 1981).Two reasons are invoked to explain metallic losses in slags: (1) mechanical entrapment of matte globules in the silicate melt; and (2) chemically combined metals in the slag-forming phases. Obviously, a chemical analysis of the slag cannot distinguish between those two modes. Grinding and flotation of the liberated sulphides have often been used to evaluate the importance of mechanical entrapment (Mechev, 1970; Imris , 1982).Recent studies in applied mineralogy of pyrometallurgical products (Bérubé et al., 1987; Pignolet et al., 1986) have demonstrated the benefits of quantitative mineralogical analyses of slags. Optical microscopy together with electron microprobe and image analysis offers a powerful and easy way of quantifying the relative importance of mechanical and chemical losses."

Jan 1, 1991

By Kyle Paulsen

The Cameco Key Lake mill began processing U-bearing waste rock from the McArthur River mine in 2000. This ore often contains elevated levels of calcium (>4% by mass), resulting in less than favourable conditions in parts of the Key Lake mill, yet still contains U3O8 at a concentration of about 0.3%. To recover the U3O8 and reject as much calcium as possible, modifications were made to the grinding circuit in late 2007 to include a gravity concentrator. The concentrator allows this mineralized waste to be processed separate from the regular blend material, rejecting calcium and concentrating U3O8, thus improving the operating conditions in areas such as SX. This will be presented in greater detail along with results and further work.

Aug 1, 2010

By G. R. Webber, P. J. Whittaker

"A multielement (Au, Cu, Pb, Zn, Ni, c-, Ag, As, Hg, Co, and S) geochemical rock sampling survey was carried out in 1977 in the Munro Township area of Ontario to assess the application of rock geochemistry for gold exploration in the region. Detailed sampling with analysis for gold and arsenic was done in 1986 in the immediate vicinity of the Croesus Mine.Samples of quartz veins and rock formations were taken in regional traverses and in more detail near old showings, prospect pits, and trenches. Quartz, graywacke, carbonate rock, and rhyolite contain the highest concentrations of gold for samples taken away from the old workings. Ultramafic rocks and gabbro have uniformly low gold. Basalt samples have slightly higher geometric means, but individual samples contain high gold concentrations. Multielement highs are mostly in mineralized quartz samples. Gold distribution is independent of other elements in most other rock types. Samples near old showings possess elevated concentrations of gold indicating that prospecting for individual mineral deposits by bedrock sampling is feasible. Concentrations of gold greater than 100 ppb are mostly within 30 m of old workings. Those samples which contain greater than 1000 ppb Au were obtained from quartz veins, basalt, graywacke, and rhyolite.High concentrations of gold were not notably concentrated near the Contact Fault although some anomalous samples came from near and on both sides of the fault. Arsenic concentrations are elevated near the Contact Fault. Detailed sampling near the Croesus Mine suggests that gold was introduced with faulting, alteration and quartz veining. Gold and arsenic have been added to the wallrock in the vicinity of the main veins."

Jan 1, 1989

By R. C. Beard

"Heap leaching, currently being applied in the treatment of low-grade ores in the south western United States, is shown to have potential for use in north western Ontario. The history and operation of the process are described, and cost comparisons are given.IntroductionHeap leaching is a simple, low-cost method of recovering gold from low-grade ore. Although it is not currently being used in Canada on a production scale, it is being used extensively, and successfully, in the southwestern United States as well as elsewhere in the world. Especially suited for large deposits of very low -grade ore, it also appears to be practical for use on small, high-grade deposits because it avoids the high capital costs of mills. Eveleth (1980) and others suggest that the capital and operating costs required for heap leaching are approximately 20% and 40% respectively of conventional milling methods.Northwestern Ontario is noted for its large number of undeveloped, small, high-grade gold deposits. Although there are a number o f larger and higher-grade deposits in the area as well, it is the relatively small undeveloped deposits which would benefit most from heap leaching, if it could be demonstrated to be a viable extraction method.To assess the significance of these small deposits, the Ontario Ministry of Natural Resources recently commissioned a consultants' study of the gold reserves in certain parts of northwestern Ontario. This report, titled ""Feasibility of Small-Scale Gold Mining in Northwestern Ontario"", by J.N. Neilson and R.C.E. Bray (1981, OGS Open File Report 5332), documents 106 known gold deposits having sufficient information to calculate gold reserves. A total of over 7.8 million tons having a weighted average grade of 0.19 oz of gold per ton were compiled in the proven, probable and possible categories, with an additional 8.2 million tons in the speculative category. Many of these deposits could be mined by open-pit methods."

Jan 1, 1983

By P. J. Mackey

"The metal producing industries in Canada and in the U.S. in many ways owe their technical beginnings to Welsh technology. The first copper smelter in Canada started in 1849-50 with a Welsh reverberatory furnace and skilled furnacemen brought across from Swansea to operate the equipment1- The Rocky Mountain smelting industry began with the installation of furnaces resembling the Swansea smelters(2). It was only later that the North American industry developed newer and improved methods. This article briefly describes the metallurgical history of the Lower Swansea Valley, being that section of land stretching northward from Swansea along the banks of the River Tawe, and bordered by hillsides east and west of the river. The Valley has had a classic cycle of development and decline common to industrial areas of Britain which grew in the Industrial Revolution. Perhaps more than any other area today, the Swansea Valley represents a complete cycle of use from agricultural to the peak of industrial development through to decline and dereliction. The conditions which made the Tawe Valley attractive to certain industries were laid down nearly 300 million years ago with the Carboniferous swamps and forests which covered the area, later forming the south Wales coalfield. As a result of glacial action and the deposit of glacial outwater and alluvial gravels, the valley adopted the traditional configuration, with its rocky sides occasionally remaining exposed. Up to probably about the 16th century, the Lower Swansea Valley was similar in use and appearance to many other valleys in the region. From the 14th century, the natural oak woodland had provided a continuous source of timber to produce charcoal for iron making as well as for structural purposes. Agriculture was the main activity in the valley in this period, but it was likely that the farmers also mined small amounts of coal by way of ""bell pits"", and adits into the coal seams."

Jan 1, 1999

By D. Royston

In SAG mills fed with a variety of ore types, hard packing between the shell lifters can come and go depending on rock type and rock size distribution and the presence of a binder. Packing can appear in all sizes of SAG mills, and can be tenacious. High ball impact forces (depending on ball size) in larger mills may compact and encourage packing. Packing can have a negative impact on milling performance and a change in shell liner design may be required to remove it. However shell liner design changes need to be managed with care to ensure liner reliability. In smaller mills control of packing can extend shell plate wear-life and may help to maintain milling performance in fixed-speed mills through the liner wear-cycle.

Jan 1, 2012

By M. Kamyab

Transportation of fluid and slurry (fluid and solid particle mixtures) in a pipe and annulus space has been the focus of numerous studies. There are different parameters to be considered when studying slurry transportation. These include slurry velocity or flow rates; fluid properties such as density and rheology; and solid particle properties including concentration, density, shape and size. Also the angle of the flow conduit, rotation of the pipe and possible eccentricity of the annulus are other factors which influence slurry transport characteristics. Although a number of analytical, numerical and empirical equations as well as numerical simulations have been developed for studying the flow and slurry transport characteristics, the results need to be validated against either field or lab data. As performing field tests is costly and time consuming, conducting simulations at the laboratory scale appears as a good alternative. Different flow loops have been designed to study slurry transport behaviour in different science and engineering disciplines including oil and gas and mining. However, few of these consider, in particular, cuttings transportation in small size annulus space. The flow characteristics appear to be very different when slurry travels within a small size annulus, in particular when the fluid velocity is high. In this study, a review of some of the existing slurry flow loops will be conducted. Then the details of a slurry loop, which has been designed and commissioned for the purpose of studying cuttings transport in a small size annulus space for applications in drilling mineral exploration wells using coil tube technology, will be presented.

Aug 1, 2013

By C. Zangerl, T. Strauhal, S. Perzlmeier, M. Holzmann

"In high mountainous regions, deep-seated rock slides are often observed in foliated metamorphic rocks such as paragneisses, micaschists and phyllites. Given that comprehensive investigations of deepseated rock slides are extraordinary costly and therefore are rare, most studies are related to investigations in the surroundings of infrastructures and human settlements. In the framework of this study there is an excellent opportunity to gain new insights in the fundamental processes and mechanisms of slowly moving deep-seated rock slides from a case study in the surrounding of a large dam reservoir in Austria. New fundamentals for comprehensive slope stability analyses and hazard assessments and sound prognoses focussing on the long-term stability and deformation behaviour of slopes under changing boundary conditions (e.g. impounding of a reservoir) and/or concepts for mitigation measures can be obtained. Within this contribution, geological field surveys, deformation monitoring, geophysical and drilling data were analysed and presented. Based on the compiled and analysed data, some key-properties of the rock slide will be presented, whereby special attention will be given on the geometry and internal structure, the slope kinematics, as well as hydrogeological and geomechanical aspects.INTRODUCTIONIn high mountainous regions, deep-seated rock slides are often encountered in highly foliated metamorphic rocks such as paragneisses, micaschists and phyllites (Agliardi et al. 2012). Critical situations may occur when deep-seated rock slides fail in a rapid manner characterised by very high sliding velocities, and/or when they develop into long run-out rock avalanches. However, many rock slides in foliated crystalline rock masses either do not move at high velocities nor do they accelerate seriously and form extremely rapid slides. Displacement rates in the range of a few millimetres or centimetres per year are common for this type of rock slide (Bonzanigo et al. 2007, Tentschert 1998, Watson et al. 2007). Nevertheless, some case studies show an activity behaviour characterised by acceleration phases reaching velocities of even metres per day. However a slope collapse is not expected and these slopes decelerate to much lower base activities. The trigger for these phases can be manifold and include heavy rainfall and snow melt, initial reservoir impounding and water level fluctuations, changes in the slope’s equilibrium state due to antecedent slow deformation processes, ongoing erosion processes along the toe of the slope, and others (Zangerl et al. 2010)."

Jan 1, 2015

By D. Marotte, M. David

"A new exploration procedure is proposed for volcanogenic massive sulphide deposits of the Abitibi belt. ""Samples"" of acidic volcanic rocks (Si02 > 60%) were compiled from the literature. From the 574 samples collected, 322 were used in each of a number of experiments. Forward inclusion linear discriminant analysis performed on the untransformed geochemical data shows a general depletion in Na20 and CaO along with an enrichment in MgO for a ""proximal"" group of samples relative to a ""distal"" one. The percentage of misclassified samples reaches 20% to 30%, but test sets shows good stability.The exploration procedure was applied to the Normetal deposit, where the authors took 160 samples during the summer of 1977. It quickly leads to the definition of targets for more detailed exploration together with a good recognition of the old known deposit.IntroductionVolcanogenic massive sulphide deposits in the Abitibi belt (Quebec) are mainly found in rhyolites or acidic pyroclastics in the uppermost portion of a calc-alkaline volcanic series (Descarreaux, 1972). The deposits are thought to have formed syngenetically by the action of volcanic hydrothermal exhalations during the waning episode of a felsic volcanic cycle (De Rosen Spence, 1976). Alteration pipes of disseminated sulphides are commonly present. Metal deposition from hot springs, initiating convection cells in a submarine environment, may have been the dominant process in ore formation (De Rosen Spence, 1976)."

Jan 1, 1981

By Derek E. McBride

"Exploration work in the Beardmore - Tashota area has led to a reinterpretation of relationships between gold mineralization and the geologicalevolution ofthe area. The host volcanic rocks form two parallel volcanic belts connected by a much smaller cross-cutting band, which trends northeast from Beardmore to Tashota. This connecting band consists of mafic and felsic volcanic, plus clastic sedimentary rocks in a sequence conformable with the contact of the Onaman Lake Batholith to the east. A metamorphic aureole or incorporated xenoliths are lacking along this major contact and the only intrusive relationship observed is chilling between mafic dikes and a cold host granite in proximity to it. Granite dikes are totally lacking in the volcanic succession, or the overlying sedimentary sequence. A major part of this sequence consists of a polymict basal conglomerate with granite boulders and volcanic clasts in a fine-grained chloritic matrix. The nearest source for these boulders is the Onaman Lake batholith.Gold mineralization in significant economic quantities (+ 50 000 ounces) occurs at the top or above the mafic volcanic succession as quartz bands. In the Northern Empire Mine, the band is conformable, folded, boudinaged and the mineral zoning shows a relationship to variations in the host rock, not structural overprinting. In general, where the host mafic tuff is medium-grained, the quartz band is thicker, up to a metre wide, and carries economic grade; where the tuff is finer-grained and bedded, the band is very thin and low grade.Stratigraphic control and metal zoning shows that the mineralization formed as part of the development of the volcano- sedimentary succession. The other major deposits in the area (Leitch and Sturgeon River) have a similar structural history suggesting that they are also syngenetic in terms of the stratigraphic development. Regionally, these deposits were emplaced prior to any significant tectonic deformation but at the end of the mafic volcanic event.The mafic activity was related 10 a period ofextension which caused the volcanic troughs to develop along centres of rifting. The hiatus at the end of this event permitted extensive hydrothermal systems to form and deposit siliceous exhalite bands within sedimentary or terminal mafic volcanic environments in promixity to major thermal sources. Subsequently, the Kenoran Orogeny deformed the entire succession into upright folds with a sub-vertical schistosity. Evidence shows that the deposits have remained intact since deposition."

Jan 1, 1987

By N. Tounsi

The use of analytical modeling of continuous chip formation in conjunction with orthogonal cutting experiments was presented in the open literature to identify the coefficients of material constitutive equation within the practical range of stress, strain, strain rate, and temperature encountered in metal cutting. Identification of reliable constitutive data was hampered by a lack of a reliable model for the prediction of the primary shear zone thickness that affects directly the effective strain rate field. An original analytical model to determine the primary shear zone thickness is proposed in this paper. It is based on the mechanics governing the material flow in the primary shear zone. Based on the distribution of the hydrostatic pressure and the forces measured from orthogonal cutting tests, the model that describes the thickness of the primary shear zone is derived. To validate the model, FE simulations of chip formation using DEFORM3D were carried out for different materials and cutting conditions. The results of the analytical model are in reasonable agreement with FEM results.

Jan 1, 2006

"IntroductionIn the 1970s, environmental concerns and associated liabilities were a new and unknown aspect of corporate risk. Today, social concerns and the associated conflicts that they can generate constitute a rapidly expanding aspect of risk. Although not a new phenomena — the Bougainville copper mine was forced into closure in 1988 — social risk has emerged as considerably more important, and increasingly visible, in the last few years. Social risk is now an aspect of all mining activities which needs to be calculated into project assessments, and to be managed throughout the life of a project. While social risk has a number of aspects at the corporate level, such as company image and shareholder relations, at the level of the individual project, its primary component is social acceptability, and the principal tool for managing it is the Social Licence to Operate.Social Risk in Latin AmericaThroughout Latin America there are newly modernized mineral codes and economic systems introduced over the last ten years which, together with new environmental legislation, look very much like regulations in developed countries. To the corporations, the existence of these instruments means that the risks from the environmental issues associated with the project are known; they are legislated, defined, quantifiable and hence manageable.It seems ironic that, just when comprehensive regulations for the environmental management of mining have been put in place throughout Latin America, there arise an increasing number of challenges to mining activities. For, in spite of the apparent guarantees provided by these new legislative reforms, communities in Latin America today are more frequently standing up and taking exception to the presence of mining companies, or the ways in which the companies are conducting themselves. The viability of projects becomes threatened because they are considered socially unacceptable, a phenomenon that we describe as social risk. These challenges are less about opposing mining activities than many people would think. Rather, they are based on an increasing desire on the part of the local population to have some measure of control over their own future, and to participate in the development process from the earliest stages."

Jan 1, 2000

By Anton Sizo, Alexey Klyashtorin

The Gunnar uranium mine operated from 1953 to 1961 on the shore of Lake Athabasca, in 1964 the site was abandoned, and the mine pit flooded. In 1981, the pit was found to be stratified with a chemocline at ~70 m by a sharp change in conductivity and TDS. The uranium concentration was ~700 μg/l on the surface, 320 μg/l at 50 m, and 2,900 μg/l at 110 m. The Ra-226 concentrations were 0.1, 0.06, 0.12, and 0.4 Bq/l. By 2017, the chemocline was ~60 m deep. The highest uranium concentration was 1150 μg/l and the lowest concentration (220 μg/l) was attributed to the chemocline. In the deeper column, the uranium content varied around 750 μg/l. The uranium distribution down the pit profile was aligned with DO, ORP, and TDS. Ra-226 averaged to ~0.4 Bq/l, Ra-226 and uranium profiles were inversely related with the respective maximum and minimum attributed to the chemocline. The uranium and radium amount accumulated in the pit by 2017 was 3,420 kg and 2,163 GBq, respectively. The uranium and radium apparent accumulation trend estimates to 64 kg/y and 41 MBq/y, respectively. A stable chemocline and no concentration gradients in the other parts of the pit suggest that the contaminants are unlikely to inflow from the bottom opening or outside the pit, but rather are mobilized from the pit walls. The contaminants are not in a steady state, and concentrations of both uranium and radium are likely to increase slowly in the future if no remediation occurs.

Jan 1, 2020

By J. G. Pearson, F. H. MacDougall, A. G. Galley

The difference in age, host rock lithology, alteration and style of mineralization indicates a fundamental difference in the format ion of gold deposits in the Flin Flon and Amisk Lake areas. The Flin Flon area contains early quartz-sulfide-gold veins fo rmed within intermittently active fractures and later plutonic hosted deposits thought to be generated in a porphyry system. In the Amisk Lake area two types of gold occurrences are recognized: I) gold-quartzcarbonate- sulfide veins within or flanking fault zones and 2) structurally and stratigraphical ly controlled zones of dissem inated and vein type sulfide-gold mineralization within extrusive and intrusive rhyolite and dacite porphyries. Both types of deposits are set within supracrustal rocks. are accompanied by intense alteration haloes and were formed prior to the major deformation event suggesting an early, epigenetic hydrothermal origin.

Jan 1, 1986

By J. -M. Bosgiraud, G. Armand, S. Dewonck, L. Richard-Panot

"The Meuse/Haute-Marne Underground Research Laboratory (URL) is located on the eastern boundary of the Paris Basin. The URL started to be built in 2000 (shaft sinking operations) in the framework of ANDRA’s (French national radioactive waste management agency) research program aimed at determining the feasibility of a reversible deep geological disposal of high-level and intermediate-level long-lived radioactive waste (HLW, IL-LLW). Its underground drifts are used to study the Callovo- Oxfordian claystone layer between 420 m and 550 m in depth.The ongoing research program (started in 2006) following the “Technology Readiness Level” (TRL) Scale is more dedicated to technologies improvement and demonstration issue of the different disposal components, even if characterization and monitoring studies are still ongoing.In rock mechanics, at the main level of the URL (located at 490 m), construction and evolution of disposal cells of different size are studied for HLW and IL-LLW packages. A step by step approach, started in 2006, is carried out based on comparison of HM behavior of parallel drifts excavated/supported by different construction methods. These various configurations give insight of the influence of construction method on the EDZ extent and evolution and on the progressive loading of the support, which are key issues to design the Cigéo disposal drifts and excavations.The concept of disposal cells studied for HLW consists in horizontal steel lined micro-tunnels 80 m long and 70 cm in diameter. Several campaigns of tests have been carried out since 2009 in order to demonstrate the feasibility of excavating such micro-tunnels and study their behavior under different conditions (with and without back filling the annular gap between the rock and the casing, watertight or not casing). A full scale demonstrator representative of the benchmark concept has also been excavated, to study its behaviour under thermal loading with heat produced by electrical heaters."

Jan 1, 2015

By D. B. Haas

THE HYDRAULIC TRANSPORT of solids is becoming increasingly prevalent throughout the world. Major long-distance slurry pipelines currently in operation transport commodities such as coal and various ore concentrates distances of up to hundreds of miles. In the United States, a number of large-diameter, high-tonnage pipelines are under consideration for the transport of Western Plains coal to markets up to 1000 miles away. In these and other applications, the solids are generally quite fine, with 14 mesh being a typical limit of particle size for long-distance (over 100 miles) slurry transport. There are applications where it might be practical to transport solids consisting of larger particles distances of up t o 100 miles. Deposits of high-quality metallurgical coal are found in the inner foothills belt along the eastern edge of the Rocky Mountains on the Alberta-B. C. border. There are few existing railroad s and the possibilities of constructing extensions are limited because of environmental and economic factor s. In these circumstances, the most efficient transportation system might consist of a pipeline to transport the coal from the mine to beneficiation plants located near existing railroads 50 or 100 miles away. Such systems would minimize environmental effects, capital cost s and operating costs. To determine whether such a system would be technically feasible, experimental testing is needed to determine the energy requirements for transporting coarse coal in a pipe line. Currently, run-of-mine metallurgical coal is crushed to less than 1 1/2 inches before going to the beneficiation plant. In the proposed scheme, coal of this size would be transported through a pipeline to the beneficiation plant located at the railroad. The Transportation Development Agency and the Department of Supply and Services have awarded a contract to the Saskatchewan Research Council to study pipelining of coarse coal in pipelines ranging from 4 inches to 12 inches in diameter.

Jan 1, 1977

By G. Armand, A. Noiret, D. Seyedi, J. Morel

"Clay formations in their natural state exhibit very favorable confining conditions for repository of radioactive waste because they generally have a very low hydraulic conductivity, small molecular diffusion and significant retention capacity for radionuclides. Nevertheless, one concern regarding the hydromechanical behavior around drifts in such claystone is the associated pore pressure field disturbance during excavation works. In the short term, the very low permeability leads to an almost “undrained” condition, meaning that the stress change due to face advance will create volumetric strains leading to an increase or decrease of pore pressure. If the effective stresses reach the failure level, the induced damage around these excavations might change the favorable properties of such formations. To demonstrate the feasibility of a reversible deep geological disposal of high-level and intermediate-level long-lived radioactive waste (HLW, IL-LLW) in the Callovo-Oxfordian claystone (COX) formation, the French national radioactive waste management agency (Andra) started in 2000 to build the Meuse Haute-Marne underground research laboratory (M/HM URL). The present paper illustrates observed pore pressure changes during excavation of drifts (˜5 m diameter), of micro tunnels (˜0.7 m diameter) and a borehole (˜0.15 m diameter). All these openings are parallel to the major horizontal stress at the main level of the M/HM URL. In drifts parallel to the major stress (i.e., when the initial stress field in the drift section is quasi-isotropic) an important increase followed by a drop of pore pressure is observed in the horizontal plane at the drift wall. These observations emphasize the impact of the in situ stress state and rate of excavation on the pore pressure and provide important insight of the hydro mechanical behavior of the COX claystone and the relationship between pore pressure and excavation induced fractures zone."

Jan 1, 2015