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By A. Zarei-Hanzaki, O. Golmahalleh, S. M. H. Hosseini, H. Azizi-Alizamini

The main importance of acicular ferrite microstructures arises from their desired combination of mechanical properties in comparison with the bainite and ferrite-pearlite microstructures. Several factors affect the microstructural transition from bainite microstructure into the acicular ferrite one. As is well established any factor corrupting the prior austenitc grain boundaries nucleation potential, such as the thin layer of allotriomorph ferrite and the austenitc deformation inhomogenities may promote the acicular ferrite formation instead of bainite. Accordingly, this study deals with the effects of the aforementioned features on the acicular ferrite formation in low carbon microalloyed steel. The results indicate that the formation of strain-induced ferrite at the prior austenite grain boundaries accompanied by deformation inhomogenities in the austenite grains change the effectiveness of allotriomorph ferrite on acicular ferrite formation from active to inert one.

Jan 1, 2004

By John S. Stevenson

The Twin ''J' mine is on mount Sicker; 8 miles by road northwest from Duncan; on Vancouver island. It includes the old Lenora; Tyee; and Richard III mines; formerly under separate ownership but now under the single ownership of Twin "J' Mines; Limited.

Jan 1, 1954

By Frank Lemy

This paper presents an application of digital face mapping in an underground mine. Based on photographs it was possible to construct discontinuity maps, which were used to characterise the rock mass. The results were compared favourably with values obtained through scanline and area sampling mapping for the same site. The case is made for digital mapping as a safe, fast, and efficient way to characterise rock mass structure for engineering purposes.

May 1, 2001

By Diego L. Romero, Joy P. Romero

"IntroductionThe purpose of this paper is to explain the theory and demonstrate the industrial applications of electrostatic separation. Wabush Mines' use of this type of processing for the concentration of iron ore is unique in the industry. Other minerals are concentrated electrostatically but the process is not widely used.Typical minerals separated by electrostatic separation techniques are:Non-ConductorsAnhydriteApatiteBariteBastnasiteBerylCalciteChrysotileCorundumDiamondEpidoteFeldsparsFluoriteGarnetGypsumHornblendeKyaniteAcmiteAugiteBrookiteCassiteriteChalcopyriteChromiteColumbiteCopperDaviditeEuxeniteFerberiteFrankliniteGalenaGoldGraphiteHematiteMica (Biotite)Mica (Muscovite)MonaziteOlivinePerovskiteQuartzScheeliteSideriteSillimaniteSpheneStauroliteSulphurTopazTourmalineXenotimeZirconConductorsIlmeniteIlmenite-( High Iron)IlvaiteKoppiteMagnetiteMarmatiteMolybdenitePyriteRutileSamarskiteSphaleriteTantaliteWolframiteWulfeniteThe limitations of this process are:1. There must be a difference in conductivity between the minerals being separated.2. The size range must not be very wide.3. The specific gravity of minerals being separated should be similar or the minerals to be pinned should be lighter. 4. The feed must be dry.5. The particle shape should be more or less uniform. 6. The feed must not be high in true middling particles."

Jan 1, 1989

By B. Coupal, F. D'Hennezel

Sorption measurements show that peat moss has much stronger affinity for oil than straw, which is currently used. Microscopic studies of peat moss show a highly porous and fibrous material, and this property, associated with the phenomenon of selective absorption, had been used to absorb oil. Laboratory experiments show that peat moss absorbs up to eight times its weight of oil. Field tests have proved that peat moss can be an effective absorbent and can be used on a large scale.

Jan 1, 1972

By A. Haque

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

Jan 1, 2015

By Neda Zangeneh

Production efficiency from low permeability gas shales require techniques to optimize hydraulic fracture completions. One completion strategy involves the simultaneous or near simultaneous hydraulic fracturing of multiple horizontal wells to maximize the fracture network area and stimulated reservoir volume. However, changes to the in-situ stress field caused by an earlier hydrofrac on subsequent hydraulic fractures are not accounted for in traditional hydrofrac design calculations. Presented here are the results from a set of transient, coupled hydro-mechanical simulations of a rock mass containing two wellbores using the discontinuum-based distinct-element method. The results demonstrate the influence of stress-shadows generated by a hydraulic fracture on the development of subsequent hydrofracs from an adjacent well. It is shown here that these interactions have the potential to change the size and effectiveness of the hydraulic fracture stimulation by changing the extent of the hydraulic fracture around the secondary well.

Jun 1, 2012

By S. J. Schofield

INTRODUCTION ONE of the greatest and most interesting problems of economic geology is to discover criteria bearing on the persistence of ore in depth. It is a question which is very much to the fore in connection with many of our important mines in British Columbia, and, as is to be expected, it is a most controversial one. The present paper, summarizing the views of the writers concerning the possibilities, in some of the mining districts of the Province, for the persistence of commercial ore to greater depths than have been, or are at present, mined, is offered as a basis for a general discussion on the subject and to call attention to the need for renewed study and research on the problem. Sooner or later-at some depth or other-individual ore-shoots become impoverished and bottom. In many mines where this has happened, either at the same or at a lower horizon, another ore-shoot, which had no surface outcrop, has been encountered and has continued downward until it, in turn, has pinched out. The Kolar (Mysore, India) gold field, for instance, presents interesting examples of this recurrence of ore-shoots at depth (1). For many years these mines have been under the management of Messrs. John Taylor and Sons. On more than one occasion they have persisted in sinking or drifting on barren quartz or along a narrow fracture for many hundreds of feet before values were again encountered. Their earliest experiment in such bold development took place at a depth comparable to that at which most mines in British Columbia are considered to be bottomed. In the past, is has been concluded that the ores in British Columbian mines do not go below approximately 2,000 feet, and to that depth only in a few instances. Consideration of the depth to which ores have been mined in the Province appears to support this view. The figures shown in the accompaning table have been gathered from various sources and are approximate.

Jan 1, 1935

By Samuel Nunoo

Gibraltar Mine is an open pit copper-molybdenum mine in central British Columbia. The stability and potential failure modes of pit walls in the Granite Pit are controlled by the orientations of joints and faults. The structural geology also has an impact on as-mined bench geometries. Geotechnical mapping and surveying were conducted using stereo photographs and photogrammetry software. Detailed digital terrain models were constructed to determine the pit wall geometry and the locations and orientations of larger structural features. The pit wall geometry is compared to conventional survey results and the mapped structures are compared to results from a nearby geotechnical borehole.

Aug 1, 2013

By D. Sbarbaro

In many modem concentrators the use of supervisory systems in their grinding circuits has meant more consistent operations and increases in capacity. These systems rely on a series of specific algorithms that uses different pieces of information and drives actions over the process. One of these algorithms is the ball mill overload detection, which plays an important role in any supervisory strategy designed to maximize ore feed rate in wet grinding circuits. This paper introduces different overload detection algorithms, and compares them in terms of the time taken to detect the overload condition. This comparative analysis is based on highly noisy power draw measurements obtained in an industrial plant.

Jan 1, 2007

By S. N. Yu

Tele-operation manipulators applied in this paper are systems for the remote handling and management of pyroprocessing related facilities in an Argon cell of the KAERI (Korea Atomic Energy Research Institute). Generally, these kinds of systems are composed of a master-slave system and its peripherals installed along the wall of the cell, with the master transmitting the user?s own motion to the gripper directly. This study introduced various considerations and modifications to improve the remote handling performance. The analysis of an operator's ability using his/her own upper arm motion range while manipulating the MSM, and considerations of its manipulation margin and the related tool modifications are also included. Finally, the test results of several remote handling tasks are presented, and an adequate operation strategy for the tele-operation system of hot-cell type facilities is proposed.

Aug 1, 2013

By K. Soucek, J. Ptácek, A. Hastíková, R. Kukutsch, P. Konícek, P. Waclawik

"Cable bolts are used frequently as a secondary support system (with steel arch support) in difficult stress-strain conditions of deep coal mines. The load transfer mechanism of cable bolts depends on several factors, such as the strength, deformation and geometric properties of the bolts, resin and the surrounding rock mass so-called cable-resin-rock system (CRR system). The bonding length and bolt/borehole diameter ratio strongly influence the final bearing capacity of the CRR system.The study presents the behaviour of CRR system during a pull-out test which is usually used in the carboniferous rock mass in the Czech part of the Upper Silesian Coal Basin. A series of 28 pull out tests were performed on 3-m-long cable bolts, with various combinations of borehole diameters and bonding lengths, to understand this behaviour. Boreholes were drilled into a solid rock mass consisting of fine-grained sandstone to guarantee similar conditions during the pull-out tests. Video inspection and measurement of borehole diameters were performed to determine their quality and real diameters. Three characteristics were observed from pull-out test results: ultimate pull-out load; displacement of the end of bolt and system stiffness. Numerical modelling by FEM (Finite Element Method) was used to determine the stiffness of the CRR system for variable bolt/borehole ratios and bonding lengths each under constant load. A linear elasto-plastic model and a mohr-coulomb model were used for cable and resin-rock respectively. The results of the experiment may contribute significantly to improving of the methodology of cable bolts installation as well as the design of used cable bolts."

Jan 1, 2015

By Jin Li

The tensile properties and microstructure of AZ91 Mg alloy before and after equal channel angular extrusion (ECAE), and the fracture behavior during tensile testing for as-extrusion and ECAE AZ91 were investigated. The alloy was performed ECAE from one to eight passes at 498K. The elongation decreased with the pass number increasing after ECAE. Grains were refined, partial coarse ß-Mg17Al12 phase fell to pieces, fine ß-Mg17Al12 precipitated in the AZ91 Mg alloy after ECAE. During tensile test the a-Mg/ ß-Mg17Al12, a-Mg/Al8Mn5 interface and the grain boundaries in a-Mg matrix acted as the crack initiation sources. The frequency of micro-cracks at the a-Mg/ß-Mg17Al12 interfaces and grain boundaries increased after ECAE, which accelerated the growth and coalescence of the micro-cracks during tensile test and resulted in the decrease of elongation of AZ91 Mg alloy by ECAE.

Jan 1, 2006

Real Time Monitoring of Cemented Paste Backfill Introduction Methods ?how to instrument a Long Hole stope Key Results from 2 case studies: barricade pressures and displacement, in-stope pressures Importance of Real Time Monitoring How binder, rise rate, cement content affect fence pressures

May 1, 2010

By C. W. Eggert

"The idea for this talk came to me last year when I was attending the Canadian Gold Metallurgists Meeting. I talked about it to a friend of mine who is an authority on mineral dressing, particularly the theoretical end of the business. He remarked that this was an excellent technical note, why don't you write it up. This is what I have for presentation this morning. I hope in presenting this type of idea in this way it is in keeping with the tradition of the Canadian Gold Metallurgists which was to function on a not too sophisticated level and where operators could get together and trade ideas in an informal way.My basic thesis is that it should be possible to evaluate screen analyses by the application of the standard statistical probability theory. In any statistical analysis the sample is the first consideration. If we look at existing methods of size evaluation we find it is usually based on the fact that a given particle will pass one square aperature and not another. One system of standardizing how these aperatures will be set up is based on Rittenger' s work with the ratio of hole sizes proportional to the square root of 2. Keeping in mind the limitation we have accepted this as our method of 11 sizing"" in attempting to apply standard statistical methods to screen analysis."

Jan 1, 1968

By A. Dave Mackintosh

Historical closure data has provided a description of the stress distribution patterns occurring around mine openings and enabled the development of a time ? distance plot predicting the location of the stress peak and its migration away from mine openings with time. Data collected from active mining areas during the 1970?s and 1980?s indicated the peak appeared to stabilize approximately 135m (450 ft.) from openings after four years. The region of high load and accompanying poor ground conditions in which the peak was centred was spread over approximately 45m (150 ft.) to 60m (200 ft.). Recent data from new development headings cut adjacent to 25 year old extraction areas suggests load transfer takes place over a much greater distance and time frame than predicted.

May 1, 2001

By C. Gu

Flow field design is critical for PEM fuel cells. The flow field design can affect reactant distribution to the catalyst surface, water management, thermal management and current collection. Therefore, it has tremendous impacts on the fuel cell performance and durability as well as reliability and operational flexibility. In this paper, an optical method is used to study the reactant distribution in the flow field channels of two commonly used flow field designs, straight channel design and serpentine channel design. Images of the flow patterns are shown followed by discussions of the flow patterns.

Jan 1, 2005

By Ali Hashemi, Anna P. Perry

The PQ Deeps (PQD) is a production zone located at Newmont’s Musselwhite Mine in northern Ontario. Development started for the PQD in late 2017, and the first stopes were mined starting in early 2021. Unlike most historic longitudinal stoping of narrower orebodies at Musselwhite, the PQD is a wider orebody following the plunge of a fold hinge and is extracted primarily by transverse stoping. Some geotechnical challenges were experienced during early stoping efforts, necessitating design changes throughout late 2021 and early 2022 to optimize the stope design. This work describes the mining methods and design changes to transverse PQD stoping based on geotechnical lessons learned during early stoping efforts.

Jan 1, 2023

By D. Virely, M. Gasc-Barbier, J. Guittard

"The valleys of the Dordogne and the Vézère (France) have been inhabited since prehistoric times, as evidenced by the famous site of Lascaux. A few miles away, the village of La Roque-Gageac is also a very popular tourist destination (about 1.5 million tourists per year): The village is sandwiched between a massive limestone cliff and the Dordogne river. The collapse of a cave roof high above the village in January 2010 led us to characterize instability together for the cave and the whole cliff and propose a adapted instrumentation to monitor the fracture openings in the rock mass that are linked to climatic variations. Measurements have been going on and been recorded for nearly 4 years. They point out the role of thermal stress fatigue in the breakdown of the rock mass. In this paper we describe the site under study, the instrumentation and its main results. INTRODUCTIONThe phenomenon of thermal fatigue has been very little studied as far as rocks are concerned, whereas it is rather well characterized for other types of materials: Elsevier published a journal dedicated to fatigue (International Journal of fatigue). In the case of rocks, thermal phenomena and their impacts on mechanical behavior have been analyzed from a micro-structural point of view, and it is now well-known that an increase in temperature causes a dilatation of crystals (Arnould et al., 2004; Berest & Weber, 1998). This dilatation may lead to the development of inter-granular traction and compression stresses, and if those stresses are greater than fracture strength, inter-granular and intra-granular cracks may take place. On the other hand, the fatigue phenomenon (cyclic repetition of a temperature variation which is less extreme than the one that may lead to this inter-granular or intra-granular fracture) is a phenomenon which has not been much studied.The principal studies on thermal fatigue on rocks come mainly from the field of geomorphology, particularly in connection with the analysis of the evolutions of past climate that can explain the present shapes of those landforms: those studies remained essentially qualitative and not quantitative. Le Ber & Oter Duthoit (1987) proposed a thermal and thermodynamic approach to analyse the disaggregation of rock masses. This analysis is dedicated to the study of paleoclimates and was implemented to better understand the formation of slope deposits in order to propose transfer models permitting the reconstruction of the climactic conditions contemporary to their appearance. Since deterioration in the cliff only appears after several cycles, it means that it is a gradual and irreversible deterioration which leads to an increase of the « disorder ». Seen from a macroscopic system point of view, this irreversible evolution is quantified by the internal creation of entropy."

Jan 1, 2015

By T. Scully

Since early days in coal mining, it has been known that some coals and the carbonaceous materials associated with them will heat and fire spontaneously. Many theories have been advanced to account for this phenomenon, but it is only within comparatively recent years that any scientific research has been carried out to determine the causes of this heating, the conditions which bring about its occurrence, and the reason why different coals heat with a varying degree of readiness. So far, this research has not cleared up these points entirely, but a great advance has been made in our knowledge of the matter. In general, any coal will fire spontaneously, although with a varying degree of readiness, provided conditions for its doing so are favourable enough. These conditions are that the coal must be in a fine state of division, that sufficient oxygen must be present for rapid oxidation, and that the air current passing must be so small that it is insufficient to carry off the heat produced by this oxidation. Many other minor factors, however, contribute to bring about spontaneous heating, either by producing initial heat themselves or by inducing the other major conditions.

Jan 1, 1931