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The importance of understanding the behaviour of cemented paste backfill (CPB) within the framework of the effective stress concept is highlighted in this paper. Only through an understanding built on this concept can problems such as barricade loads, the rate of consolidation and arching, be fully understood. The critical importance of the development of stiffness during the hydration process, and its impact on factors such as barricade loads, is used to illustrate why conventional approaches that implicitly ignore the effective stress principle are incapable of capturing the essential components of CPB behaviour.

May 1, 2007

By G. Knight

"Results of a program of dust research carried out at the Mines Branch Laboratory, Elliot Lake, indicate that dust-concentration estimates vary greatly, depending on the sampling instrument, the assessment technique and the properties of the dust cloud. The wide range of the ratio between the estimates by any pair of instruments shows that the correlation between the health hazard and dust-concentration estimates by most existing sampling instruments must be questionable. Important studies are being carried out to permit the definition of mine environments in more precise technical terms. The influence of size selection, the physical property measured, composition and sampling period on the assessment of the health hazard are discussed."

Jan 1, 1969

By Eugene Barsky

"At present, theoretical concepts of gravitational separation processes are mainly limited by the study of the interaction between a flow and a solitary particle. Then the main conclusions of this analysis are applied to a mass process. However, this analysis is absolutely insufficient, because some elementary phenomena such as the ingress of coarse particles into the fine product output and vice versa cannot be interpreted from its standpoint. It is also impossible to predict the results of the classification of a material with a specific granulometric composition on a specific apparatus on its basis.In the present paper, an extended model of the process is suggested. The model is based on the behavior of all the particles of a specific narrow size class, and not on that of an individual particle. Similarity criteria of the process, which were empirically derived previously, are obtained from the analysis of this model.INTRODUCTIONIn case of gravitational separation, a part of solid phase moves, as a rule, vertically upwards with the flow, while another part settles against the flow. This flow is extremely complicated and chaotic due to various random factors. Among these factors are mass interactions of particles with each other and with the apparatus walls, non-uniform character of concentration and velocity fields, turbulent vortices and local fluctuations, real particles shape difference from spherical one, etc.Particles rotation results in a transverse force (Magnus' effect). At the motion of a non-rotating particle in a non-uniform velocity field, a transverse force also arises (Saffman's effect).A great number of publications have been devoted to the account for all these factors in two-phase flows in recent decades. Very complicated models have been developed, but the problem has not been completely solved as yet [1, 3].At the same time, simplified models of the behavior of a solitary particle in a flow are being developed. Despite their schematic nature, such models often prove to be useful for establishing general laws of the process and its similarity criteria [1]."

Jan 1, 2016

By J-P. Rossetti, A. Guerin, M. Jaboyedoff, L. Baillet, A. Mariscal, J. D'Amato, D. Hantz

"The processes leading to the fall of rock compartments from rock walls are poorly known as well as their velocity. It ensues that quantitative prediction of the failure time for a rock compartment which is presently stable, is not possible by a purely geomechanical approach. However a quantitative probabilistic prediction of rockfalls at the scale of a rock wall is possible if the spatial-temporal rockfall frequency can be determined or estimated (Hantz, 2011). For a better knowledge of failure processes and frequency, rockfalls have been detected in several rock walls, using annual terrestrial laser scanning, allowing comparison of the frequencies in different geological conditions. For one of these rock walls, the spatial detection have been completed by a precise dating of the events, using a quasi-continuous photographic survey (one photo every 10 mn), allowing the study of the influence of meteorological factors.The precise dating of rockfalls has been carried out for the Saint-Eynard cliff which towers above a residential area of the town of Grenoble (French Alps). The South-East facing cliff consists in bedded limestone gently dipping North-West and located at an elevation between 850 m and 1100 m. The surveyed zone is about 750 m large and 250 m high. Between 01/02/2013 and 26/11/2013, 65 rockfalls ranging between 0.01 m3 and 20 m3, have been detected by diachronic comparison of laser scanner data and dated by comparison of photographic images. The temperature at the elevation of the cliff has been calculated from the temperature measured (every 5 mn) at a meteorological station located at an elevation of 245 m and 2.5 km away from the cliff, using a temperature gradient of 0.003°C/m (D’Amato et al., 2014). The precipitation were measured 900 m away from the cliff at an elevation of 469 m. Different meteorological conditions have been defined: (a) “freeze” qualifies days with negative mean temperature (but with a thaw period, except for two days); (b) “thaw” qualifies days with positive mean temperature, but following a freeze day; (c) “rain” qualifies days with precipitation.Table 1 shows the rockfall temporal frequency for the different meteorological conditions. It appears that the frequency is about 6 times higher the freeze days, 2.5 higher the thaw days and 3 times higher the rain days than days without freeze, thaw or rain."

Jan 1, 2015

By Hossein Aminian, Daniel Hodouin, Claude Bazin, Claude Jacob

"Solvent extraction followed by electrowinning (SXEW) is an economical option for the processing of low grade and oxidized copper ore. Phenomenological models were developed to simulate the copper solvent extraction and the electrowinning processes. The two models were linked together to make a SX/EW simulator. The simulator is used to predict the operation of the mines Gaspe pilot plant put in operation in 1996. Results confirm the potential of the simulation that would subsequently be used for student training, process optimization and to assess the performances of control strategies.INTRODUCTIONSolvent extraction followed by electrowinning (SXEW) has become in the last two decades a key process for the recovery of copper from solution obtained by leaching low grade copper ore. Several operations have been commissioned in North and South Americas in the last decade (Arbiter, 1994). In Canada, Gibraltar Mine (Scott, 1991) operates a SX plant followed by electrowinning (EW) to produce copper cathode from leached low-grade ore dumps. From 1996 to 1997 Mines Gaspe operated a pilot plant to test the economical feasibility of leaching an oxidized copper ore, followed by solvent extraction and electrowinning of copper. Despite copper SX/EW processes have the reputation of being low cost operations, plant engineers should always look at way to make the plant more efficient. Process models provide an economic platform to learn, control and ultimately optimize the operation of a plant.Several models have been independently proposed to simulate the SX process (Cadman and Hsu, 1970; Medina Gomez, 1980; Wilkinson and Ingham, 1983; Garcia et al., 1988; Aminian et al., 1997) and the EW process (Bryson, 1981; Barton and Scott, 1992; Barton and Scott, 1993). However few papers, if any, deal with the integration of the two process models into a single simulator of a SX-EW plant. This paper describes the development of an integrated simulator for the SX-EW process and shows some steady-state simulation runs of an actual SX-EW pilot plant. The paper consists of four sections. The first section shows the general layout and principles of operation of a SX-EW plant.The second section describes the SX model while the third section deals with the process model used for the copper electrowinning process. The last section shows how the two process models are linked to simulate the operation of the Gaspe pilot plant."

Jan 1, 1999

By Les Johnston

_ BACKGROUND - About EPCOR - Genesee Generating Station - Phase 3 Expansion _ TECHNOLOGY SELECTION - Selection Criteria - Combustion Options - Flue Gas Emission Control Options _ STAKEHOLDER VIEWS _ PROJECT STATUS _ EPCOR is an integrated utility company for water, gas, electricity and technology services. _ EPCOR has about 1.6 million customers in Alberta, Ontario, Manitoba, BC, and the U.S. Pacific Northwest. _ EPCOR Generation Inc. operates three power stations in Alberta which were in operation before deregulation, including the coal-fired Genesee Generating Station. _ EPCOR Power Development Corporation owns generating stations in Alberta, BC and Washington State and will be building the Genesee Phase 3 expansion.

May 1, 2002

By L. Shasko, M. Hurlbert

As climate change is increasingly perceived as a problem, and fossil fuel based power production options are increasingly limited through regulatory restrictions and public distaste, future options become constricted. Reflexivity and social learning elicited through qualitative and mixed research methods offer important insight into what future power production pathways might be. Given factors of cost, baseload requirements, and energy density, options such as nuclear may be increasingly accepted. This paper explores this literature and possible methods of pursuing the reluctant acceptance of nuclear energy.

Jan 1, 2020

By D. J. Thorkelson

New data indicate Wernecke Breccia-associated iron oxide copper-gold (IOCG) deposits likely formed from moderate-temperature, high-salinity, non-magmatic brines. The breccias formed in an area underlain by a sedimentary sequence that locally contained evaporites (potential source of chloride and possibly sulfur) and was thick enough to produce elevated fluid temperatures. Metals (Fe, Cu, Co, U) were probably derived from host strata, transported as chloride complexes, and precipitated due to changes in fluid temperature and pressure during brecciation. These new data suggest that the spectrum of genetic models for IOCG deposits that typically invoke formation from magmatic or hybrid magmatic-non-magmatic fluids should be expanded to include those systems that formed in a non-magmatic environment. Modifications to the definition of IOCG systems are proposed that reflect the degree of involvement of magmatic and/or non-magmatic fluids and the nature of the mineralizing environment. A division into magmatic, non-magmatic, and hybrid magmatic-non-magmatic IOCG types is suggested. Typical magmatic end-member IOCG deposits include Lightning Creek and Eloise, Australia. Hybrid magmatic-nonmagmatic IOCG examples include Ernest Henry and Olympic Dam, Australia. The Wernecke Breccia and Redbank deposits are suggested as possible representatives of non-magmatic IOCG end members. Endmember magmatic IOCG deposits have similarities to some porphyry deposits, whereas non-magmatic IOCG end members share characteristic with some sediment-hosted Cu deposits, suggesting that the range of IOCG deposits may form a link between intrusive- and sediment-related deposits

Jan 1, 2007

By Masami Nakamoto

Controlled thermolysis of gold(I) thiolate complex, [C14H29(CH3)3N][Au(SC12H25)2], at 180 °C for 5 h under an N2 atmosphere produces novel gold nanoparticles passivated by alkyl groups derived from the precursor complex, the TEM photograph of which shows spherical particles with average diameter 26 nm. Since Brust et al. reported the two-phase reduction of AuCl4 - by NaBH4 to afford monodispersed gold nanoparticles passivated by alkanethiolate ligands (1), plenty of preparative investigations on gold nanoparticles (2,3) and its surface modification (3,4) have appeared, because of their potential applications in microelectronics (5). However, those preparative methods generally involve the reduction of AuCl4 - by reducing agent NaBH4 in the presence of suitable organic stabilizers such as alkanethiol (1-4), phosphane (5), quarternary ammonium salts (6), surfactants (7) or polymers (8). On the other hand, O?Brien et al. recently reported the preparation of organically capped gold nanoparticles at 190 °C, where tri-n-octylphosphine oxide and/or n-octadecylamine are used both as a reaction medium and as a passivating ligand (6), but this procedure also needs NaBH4 as reducing agent. Our strategy of novel preparative method of gold nanoparticles is the combination of reductive elimination of thiolate ligands and simultaneous attachment of organic moiety on the growing nuclei. Gold(I) thiolate complexes with ammonium cations were useful for our preparative method. We now report the controlled thermolysis of gold(I) thiolate complexes, [R(CH3)3N][Au(SC12H25)2] and [R(CH3)3N][Au(SC6H4-p-R?)2] (R= C14H29, C12H25; R?= C8H17, CH3), under an N2 atmosphere, where the powder of gold(I) thiolate complexes completely melts to afford the precursor liquid and then the liquid gradually decomposes. In spite of no use of reducing agent and solvent, reduction reaction is thermochemically induced to afford novel gold nanoparticles passivated by alkyl groups rather than by alkanethiolate ligands. Figure 1a shows a typical transmission electron microscopy (TEM) image of gold nanoparticles prepared by thermolysis of [C14H29(CH3)3N][Au(SC12H25)2] at 180 °C for 5 h, indicating a controlled growth of spherical gold nanoparticles. As shown in Fig. 1b, these spherical gold nanoparticles display the size distribution ranging from 5 to 50 nm. Although the particle size is larger than that of thiol-derivatized gold nanoparticles (less than 5 nm) prepared by NaBH4 reduction (1-3), the aggregation of gold nuclei is smoothly regulated and the growth of core gold is limited to be 26 nm in average diameter in spite of thermal procedure.

Oct 1, 2003

By R. W. Diamond

Introduction THE Sullivan mine and the milling, smelting, and refining operations of the Consolidated Mining and Smelting Company are sufficiently well known to make unnecessary anything more than a very brief account of the events which led up to this Company's branching out into the chemical industry. This development is the result of the 26 per cent sulphur content of the Sullivan ore. Seventy-five to eighty per cent of this sulphur enters the mill tailing, which is stocked at Kimberley. The remainder, contained in the lead and zinc concentrate, is burned off in the first treatments at Trail. Prior to this new development, the sulphur gas was wasted to the atmosphere. In spire of its great dilution with air and discharge from stacks at high elevations above the plant, some damage to vegetation close to the plant was experienced. It had always been apparent that this sulphur should be recovered and utilized if possible, at the same rime relieving, or curing, the smoke nuisance, and constant studies with this in view had, therefore, been maintained. One of the early conclusions reached was that the Canadian prairies would ultimately require large quantities of phosphate fertilizers, as had been the experience of older countries, and that these fertilizers would constitute a large outlet for sulphuric acid which could be made from smelter gases. This conclusion prompted a widespread search for phosphate rock, particularly in British Columbia and western Alberta, with the result that low-grade beds were discovered in the Crowsnest district and to the north therefrom through extensive areas (1). Following these discoveries, an experimental plant was built at Trail for the production of triple superphosphate in order to facilitate field-tests in fertilizing prairie lands.

Jan 1, 1934

By Walter I. Nelson

THE geology of the Copper Mountain mine has been ably described by Dr. Victor Dolmage in Memoir 171 of the Geological Survey. Reference is invited to that paper for a more extended description of the geology of the ore deposits than will be given here. The important orebodies of the mine occur in fragmencal volcanic rocks, parallel with and adjacent to the gabbro of the Copper Mountain stock. In the mine area, the contact strikes N.45°W. and dips either vertical or steeply co the southwest. For a distance of 500 feet or more from the contact, the fragmental rocks have been intensely metamorphosed both dynamically and hydrothermally. The dynamic effects are reflected in the foliation and fracturing parallel with the contact, which occurs throughout the mine, and the volcanic rocks within this foliated zone are, in places, highly schistose. Superimposed upon thi.s structure is a system of fine, straight, parallel frac-tures that strike nearly normal to the foliation (and contact) and dip between 65° and 75° to the north; it is with this last-described fracture system that the ore minerals are structurally associated. The fractures are mineralized with bornite and, to a considerably less extent, with chalcopyrite and some pyrite. A notable characteristic is the extreme fineness of the fractures; even in high-grade ore they are rarely larger than pencil lines. The tenor of the ore, therefore, varies directly with the fracture spacing. Replacemcnr of the host-rock between two or more fractures, varying in degree from finely disseminated sulphides to masses of nearly solid bornite up to 18 inches wide and 2 to 3 feet long, is not uncommon in the higher-grade portions of the orebodies. Two structural types of orebody are recognized in local nomenclature: the 'contact' orebodies, so-called because they occur along the contact; and 'outlying' orebodics, which are enclosed in the volcanics. The former arc tabular or lenticular bodies elongated along the strike and dip of the contact. The 'outlying' orebodies are coniform, chimney-like masses roughly elliptical in plan; with depth, their roots plunge at steep angles toward the contact. All of the orebodies are cut by a number of light-coloured granophyre and felsite porphyry dykes. These dykes-the so-called 'mine' dykes -enter the mine area from the north, curve gently southeasterly across the orebodies, and then cross the contact into the gabbro at the south end of the mine. All the dykes dip vertical to steeply east.

Jan 1, 1941

By E. V. Neelands

THE Canadian Malartic mine is in Western Quebec, about fifty miles east of Noranda and forty miles south of Amos on the Canadian National railway. The recently constructed branch of the railway from Rouyn to Senneterre passes half a mile north of the mine. HISTORY he property was discovered in 1923 'by St. Barbe Sladen, H. S. Kennedy, and J. C. Carroll, who were prospecting for an Ottawa syndicate and found gold in a small quartz vein near the present workings. Five claims were staked and were optioned to an exploration company, who allowed the option to lapse after surface sampling and diamond drilling eighteen holes. Some months later, the property was sold to Malartic Gold Mines, Limited, who carried on development until 1929. A vertical shaft was sunk and exploration work done on three levels, supplemented by diamond drilling 16 surface holes and 62 underground holes. The work indicated that the important ore occurred in two silicified.zones in schisted greywacke which intersected west of the shaft and were believed to be controlled by a drag-fold. The ore grade was not considered sufficiently favourable to war-rant an operation, and work was terminated. With the advance in the price of gold to $35 per ounce, interest was revived and a new Company, Canadian Malartic Gold Mines, Limited, was incorporated for further development. The shareholders of the old Company accepted a new position under which their interests were protected, and sufficient treasury shares were optioned to Ventures, Limited, and Sudbury Basin Mines, Limited, to provide funds for further exploration of the prop-erty to determine whether, under the new economic conditions, profitable operation would be possible, and, if advisable, to provide the equipment for production. Additional claims were acquired, bringing the total area up to 1,029 acres.

Jan 1, 1939

An essential tool for every step ? Early field survey ? Handheld satellite phones ? Portable satellite phones ? Exploration and Drilling ? Handheld satellite phones ? Portable satellite phones ? Production ? Handheld and portable ? Fixed Satellites systems ? Asset tracking systems Main applications via satellite ? Voice and Fax communication ? Internet access and E-mail ? Video conferencing ? Interconnection to mobile phones, 2 way radios, long range WIFI ? Equipment Tele-maintenance ? Telemedicine ? Crew and morale calling ? Vehicle and asset tracking

May 1, 2006

By W. Curlook, V. G. Papangelakis, M. Baghalha

A pressure acid leaching process has been developed for the extraction of metal values, nickel, copper, cobalt and zinc, from base metal smelter slags. The basic concept contemplates cooling the smelter slags through solidification sufficiently slowly to induce a good measure of crystallization; and subsequently, after fine grinding, to pressure leach such slags at around 250°C while applying oxygen overpressure, utilizing smelter byproduct sulphuric acid. High levels of extraction of the slags' metal values are thereby achieved. It has been shown that if the same slags are quenched thereby producing an amorphous structure, the resulting metal extractions are very low. The process is applicable to smelting furnace throwaway/discard/dump slags, as well as to in-process converter slags. By extracting the bulk of the residual base metal values in the throwaway/discard/dump slags, the resulting leached residues are rendered virtually benign vis-à-vis the external environment.

Jan 1, 2004

By F. Malek

At Creighton Mine, magnitude events are a regular occurrence due to depth and major seismically-active structures. Over the last ten years, major advances have been made in research and development to develop strategies for the management of these major events. Today, the number of rockbursts has been drastically reduced at the mine and damage due to seismic events, when they occur, is often minimal. This paper describes the evolution and implementation of appropriate geomechanics strategies, designs, and practical ground control measures undertaken for the management of seismicity at Vale Inco?s Creighton Mine. A description of the research and development approach, implementation, and ground control strategy is provided for placement of enhanced support systems to manage the consequences of magnitude events at Creighton

May 1, 2009

By A. E. McIlhinney, I. E. Puddington, C. E. Capes, A. F. Sirianni

"Two main problems are associated with the removal of pyritic sulphur from coals. The first is due to the fine state of dissemination of pyrite, which requires grindin1 to a very fine size to accomplish liberation. The second problem is caused by the similar surface chemical characteristics of coal and pyrite, which complicates separatio11 methods based on this property. In the work described here, the problem of fine particle size was overcome by using the selective oil agglomeratioa method developed at the National Research Council of Canada. Recovery of more than 90% of the combustible values was possible, even with particles only a few microns in diameter. Experiments using conventional chemical depressants for pyrite met with little success. It was found, however, that pyrite may be rejected during coal agglomeration through treatment with the iron.oxidizing bacteria, thiobacillus-ferrooxidans. The conditions for maximum pyrite separation are described and possible mechanisms by which the bacteria act are discussed."

Jan 1, 1973

By Rosaire Emond

Le concept du forage horizontal a été développé voilà de nombreuses années. Différents types de plate-formes permettant le forage horizontal depuis une cheminée ont été conçus par divers manufacturiers ou opérateurs miniers. Entre autres, on connaît bien la griffe de montage Alimak à laquelle peut être fixée une plat-forme sur laquelle est montée une foreuse. En 1992, Ross-Finlay a développé sa propre plate-forme de forage qui à notre opinion améliore la flexibilité du concept du forage horizontal, en augmente la productivité et en diminue le coût d?ensemble tout en assurant une sécurité accrue des travailleurs. Tel que montré à la figure 1, la plate-forme employée à la Mine Kiena est composée d?un toit de protection contre les chutes d?objets et de deux passerelles de forage de forme carrée. Le toit et les passerelles sont fixées à une structure de 6.5 m de longueur équipée de deux assemblages de rouleaux (non montrés à la figure) permettant de faire glisser l?ensemble sur des rails Alimak. L?angle du toit et des passerelles peut être ajusté pour des cheminées dont le pendage varie de 65 degrés à 85 degrés.

Oct 1, 2001

By F. Roemer, D. Goldmann, T. Elwert

Tantalum is an important minor metal for the production of high performance capacitors. Approximately 60% of the annual tantalum production is used in this application. Despite its high price of 298 US$/kg (average price 2010–2014), at the moment, no recycling from end-of-life products takes place. In the established recycling processes of waste electrical and electronic equipment (WEEE), tantalum is lost in the slags of copper smelting, where it is highly diluted. An economic recovery is not possible at that point. Although tantalum must therefore be extracted from the WEEE stream before it enters smelting, no industrial recycling processes exist. The main reasons are its low concentration in the WEEE stream, lack of information about tantalum bearing devices, technical difficulties of extraction, and conflicts of interests regarding the recycling of other valuable metals in WEEE. In this paper, the results of a cooperation research project are presented. The aforementioned challenges are addressed and a novel tantalum recycling process is developed. Small pilot scale experiments show that a mechanical processing route can produce marketable tantalum-concentrates of 30% tantalum with yields between 60 and 70%. This is reached through a manual pre-sorting of potentially tantalum bearing products followed by a combination of an optimized comminution, sieving, air classifying, eddy-current (EC), and two stage magnetic separation. Key to the implementation of this process was a detailed survey of the tantalum concentrations in different products carried out by the industrial partner.

Jan 1, 2016

By P. Srinivasan

Corrosion is a major operational problem in amine-treating plants causing significant expenditures each year, Corrosion may become more severe when the amine plants contain process contaminants ? namely heat-stable salts. The heat-stable salts enter the plants with feed-gas streams and makeup-solution, and/or are produced within the plants by reactions of alkanolamine and available carboxylic-acid anions, This work investigated interaction corrosion effects that may exist in amine-treating plants containing a mixture of heat-stable salts, The investigation was experimentally carried out in a 5 kmol/m3 monoethanolamine (MEA) solution containing 0,20 mol/mol carbon dioxide (CO2) loading at 80°C under atmospheric pressure using carbon steel 1018, Six heat-stable salts, including formate, oxalate, bicine, acetate, thiosulfate and chloride, were tested with a series of salt combinations, Potentiodynamic Polarization, Tafel Extrapolation, and Cyclic Polarization were used for revealing corrosion behavior, determining corrosion rate, and examining the pitting tendency, respectively, Results show that thiosulfate induces the most corrosive environment when present either individually or in the form of salt mixtures.

Jan 1, 2005

By Raymond S. Suglo

Increasing depths of mining coupled with the mechanization of most underground mining operations have led to growing complexities in the mine environments with the production of large amounts of gaseous and particulate contaminants. Over 100,000 lives have been lost due methane gas and dust explosions in coal mine workings in both the US and Canada since 1900 when the methane concentrations exceeded stipulated levels in some workings. There is therefore the need to constantly assess and evaluate the performance of the existing mine ventilation systems to maintain safe and acceptable mine environmental conditions in workings to meet the requirements of federal, state or provincial laws. This paper uses the results of continuous monitoring of methane concentrations conducted in selected development headings in coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems in the control of methane gas concentrations in the headings. The results show that the average quantities of fresh air required to dilute, disperse and remove methane concentrations within set levels of one minute varied from 5.43 m3/s in Heading #11 (Condition 2) to 27.97 m3/s in Heading #10 (Condition 1) and this represented about 12 to 26% of the quantities required to dilute methane concentrations to safe levels within one minute under Condition 1 and 32 to 139% under Condition 2. The average dilution times in the headings studied were less than 8 minutes. The forcing efficiencies of the auxiliary systems in the headings studied ranged from poor to excellent implying that the auxiliary ventilation systems were capable of controlling the methane concentrations below statutory levels but may not be able to cope with large and unusual methane concentrations in the headings. This study is important to prevent methane gas and coal dust explosions in coal mines and thus avoid any loss of lives and property.

May 1, 2001