Search Documents

By Dong-min Lee

As the construction industry is becoming more large-scaled and complex, the BIM technology has been utilized throughout the industry. Since 2008, the construction industry in South Korea (Korea) has required carrying on BIM-based project continually. According to this trend, BIM S/W market, as well as BIM library market is also gradually activated. Many countries have already been establishing Web-based BIM library market, also Korea has been trying to establishing this Web-based BIM library market. In this study, through market research of Web-based BIM library market of advanced countries including the U.S.A. and U.K., establishment strategy of BIM library market to be derived by late starters that introduce BIM such as Korea, Japan and China was deduced based on current establishment status of BIM library market in Korea. In addition, deal with an issue that a clear revenue-sharing system between business principals of Web-based BIM library market is not available at the current stage was presented as a factor of inhibiting activation of BIM library market. So in order to offer a reasonable revenue-sharing strategy in BIM library market as conceptual level, a methodology and process of applying Game theory being used for deriving. It is expected that a reasonable revenue-sharing model between business principals would be presented as its standard of BIM library market to be more activated in the future.

Aug 1, 2013

By Harry V. Warren

Introduction Any person concerned with the welfare of mining in British Columbia cannot help being perturbed by the fact that the industry, to an alarming extent, is living on its capital. The great majority of mines and mining camps of today represent a heritage handed down by the prospectors of yesterday. It is true that mining engineers, geologists, mineral dressers, metallurgists, and their fellow scientists and engineers have played an honourable, indeed a vital, part in he1ping to make our producing mines, often after costly and extensive underground development and extended researches. It is also true that the mineralization at the Sullivan, Britannia, and Copper Mountain mines was all discovered before the turn of the century. Likewise the Cariboo, Bridge River, Hedley, Ymir, Rossland, Boundary, Slocan, Salmo, and Portland Canal mining areas, although they had not all been developed, were all known more than fifty years ago. Furthermore, every one of these camps owed its discovery and eventual exploitation to the fact that encouraging ' mineralization occurred at the surface. Where would the mining industry of British Columbia be today had those precious outcrops been buried beneath twenty to forty feet of glacial drift or other overburden? Anybody familiar with the geology and geography of British Columbia will probably agree that finding new mining camps is going to be an increasingly difficult and costly business: disappointments there will be in abundance. Nevertheless, most persons will probably also agree that other valuable mines and even mining camps await discovery by those who will prove resourceful and lucky enough to unearth them. It has become increasingly obvious to the authors of this paper that any new too1s which can aid either prospectors or engineers in their search for new orebodies should be welcome. This paper outlines our efforts to develop biogeochemistry and related techniques to the point where they may be considered as useful tools in the search for hidden mineralization.

Jan 1, 1950

By N. R. Paterson, D. G. MacKay

"The geology of the Mattagami mining camp, while of particular economic significance, is unfortunately obscured by a very thick mantle of overburden. For this reason geo-physical methods have been relied upon heavily in exploring the area. Geophysical data over five important sulphide discoveries show how targets are selected for drilling and how effective geophysics has been in assisting subsequent development programs."

Jan 1, 1960

By Denis Thibodeau

his paper describes a study of an altered mining extraction and the resulting Rockmass response at VALE?s Creighton Mine. Typically, the deep mining zones have strict stope extraction guidelines to ensure safety and productivity; however, these guidelines offer low flexibility or few options for stope sequencing. The 402 O. B. being in a good rock mass, at moderate depth and stress regime at Creighton, offered an opportunity to drive a more flexible mining sequence with stopes and a pillar. A three-phased approach was used to mitigate risk of the mining plan: 1- Numerical modelling to fully anticipate rock mass response to the proposed mining sequences. 2- In situ seismic monitoring to collect stress and seismic activity data. 3- Analysis of the in situ data to correlate to the modelling results. The creation and the extraction of a pillar in the 402 O. B. was successfully completed. The recorded seismic activity agrees well with the numerical modelling since most of the seismic activity is localised in the hangingwall where the deviatoric stress corresponds to an early damage process. The moderate levels of deviatoric stress cause localised failure with low level of seismic activity.

May 1, 2013

By Lawrence D. Hoy, Armand Savoie, Pierre Trudel, Ghislaln Tourigny, Robert Crépeau, Lao Kheang

"Recent fluid inclusion and stable isotopic studies in the Bousquet mining district have identified spatial and temporal trends in mineralization temperatures and isotopic compositions of vein forming fluids. These studies indicate that mineralizing temperatures were lower during sterile vein formation (T=200-300°C) than during auriferous vein formation (T = 300-400°C), and that 8 80 values of minerals in sterile veins are lower by 1-3 %o than in associated auriferous veins. In addition to these small differences in 8 80 within individual mineralized zones, a trend of increasing 8 80 values of vein minerals is identified from west to east across the district, with 8 80 of vein minerals increasing by4-6%o. Quantitative evaluation of potential causes of the observed oxygen isotopic shifts suggests that the best explanation for these trends is the derivation of the mineralizing fluids from an isotopically inhomogeneous terrain in which the fluid isotopic compositions are controlled by the isotopic compositions of the host lithologies due to high rock/water ratios in these source terrains. This inhomogeneous source terrain is interpreted as consisting of the Blake River Group volcanics (low 8 80 component) and the adjoining Kewagama and Cadillac Group sediments (high 8 80 component).The genesis of the hydrothermal fluids is attributed to crustal heating during metamorphism, with the fluids representing metamorphic dewatering products and/or fluids incorporated during deposition and burial of the host lithologies. Ductile deformation of the fluid source regions impeded fluid migration during metamorphism; the ultimate release of the mineralizing fluids is attributed to the penetration to depth of vertical structures (fault and shear zones) during brittle deformation of the crust under waning metamorphic conditions. Release of fluids caused by this puncturing of the closed hydrologic source regime produced a localized zone of lowered pressure, drawing fluids from adjacent lithologies toward the fault zones, feeding further hydrothermal fluid upwelling. Au mineralization resulted from chemical processes related to cooling of the hydrothermal fluids and/or interaction with lithologies encountered during fluid migration; the level of crust at which Au deposition occurred likely migrated upward with the thermal anomaly caused by hydrothermal fluid upwelling, eventually reaching the level of current exploitation. Cessation of fluid flow along the vertical structures is attributed to inadequate recharge of the hydrothermal systems as fluid contents were depleted in the lithologies proximal to the vertical structures and/or sealing of the structures by mineral deposition."

Jan 1, 1990

By Floyd Smith

Based on underground observations made in .the coal mines of the Dominion Coal Company Ltd., this paper deals with the stress phenomena in the approach roads and headways and in the gob areas associated with the longwall method of total extraction. The deformation of roadways during development and the deformation of roadways during the total extraction period is delineated and presented in graphical form .. Conclusions are made as to the feasibility of the introduction of the retreat method of longwall extraction in one of the colhenes. The importance of future studies are enumerated, especially. those pertaining to the determination .of the opti.m.um sizes of protective pillars and to increasing the efficiency of the current methods of artificial roadway support.

Jan 1, 1967

By T. W. Wlodek

Abstract A simplified method of fatigue testing full-dimension, as-rolled, non-machined, mining drill rods is very desirable to the mining and steel industries in the classification of steels available on the market, through the evaluation of their fatigue limits and endurance strength. In this paper one such simplified method is presented and analysed. The preliminary results show many advantages of this method, such as simplicity and constancy of loading. The type of loading applied more or less simulates the working conditions of the outside fibres of the mining drill rods. Additional advantages of this method are the possibility of testing under dry and wet conditions, its quietness, and its ease of operation. Specially designed adaptors and specially applied techniques of fixing and preparation of samples make possible the breaking of a quarter-octagon hollow drill rod in a free length of uniform section in a rotating beam machine. At first glance this seems to be difficult to achieve. In the first preliminary test three different lots of steel were used. S-N curves under dry conditions were determined. These curves permit of the classification of the drill rods on the basis of the fatigue limit and endurance strength of the outside fibres of the metal, which is dependent to a greater or lesser extent on the effect of surface decarburization, surface imperfections, and special surface treatments. The average slope of the S.N curve in the damaging zone, and the fatigue limit in equal tension-compression rotating bending, were determined for SAE 1080, chromium-molybdenum and nickel-chromium-molybdenum mining drill rods. INTRODUCTION The fatigue limit and the endurance strength of mining drill rod steels are of interest to both the mining and the steel industries. These industries are greatly interested in lowering the cost of mining by reducing the consumption of these steels per ton of ore exploited.

Jan 1, 1951

By R. H. Beaton

"About 1905, a plant was constructed at C1ayburn, in the Lower Fraser valley, 4'5 miles east of Vancouver, to process shales from Sumas mountain into heavy clay products. In time, mining operations were found to be more favourable on the opposite side of the mountain, and by 1913 a plant, which soon became the centre of activities, was completed at Kilgard. Destroyed by fire in 1949, the plant was rebuilt on modern lines, and a second plant was established at Abbotsford, six miles to the west. The Company, from its beginning, has grown with development of the Province. In recent years, operations have kept abreast of latest developments, particularly in materials handling. Latest innovation has been the complete conversion of fuel from Bunker C oil to natural gas. In 1957 the Company became associated with Harbison Walker Refractories, Limited, a leader in its field in the United States, and its title was changed from Clayburn Company, Limited, to Clayburn-Harbison, Limited. Currently, the Kilgard plant produces sewer pipe, agricultural tile, and flue liner; the Abbotsford plant, refractories and facebrick. Improvement of products and development of new ones are tasks of a recently-completed testing and research laboratory.Almost all ware produced is marketed in Western Canada or Washing-ton State. The Vancouver area absorbs the bulk of structural clay products."

Jan 1, 1959

By M. Rebolledo, N. Mora, G. Zarate

For decades, the mining industry has been focussed to find an efficient and economically attractive process for the leaching of chalcopyrite. Jetti Resources has developed a novel hydrometallurgical alternative to extract metals of value from mineral ores that the mining industry has struggled to process. Jetti’s catalytic technology, whilst being especially advantaged for extracting copper from low-grade and highly refractory minerals, such as chalcopyrite, seamlessly integrates with existing heap leaching methods and downstream processing operations. The technology uses a catalyst which weakens the metal-sulfide bond in the crystalline structure of the chalcopyrite mineral and alters the structure of the passivation layer allowing the leaching process to continue. Metallurgical test work was conducted to examine the effect of ore variability, in terms of grade and copper deportment. The results presented in this study highlight the amenability of the technology and demonstrate that it is possible to enhance leaching performance of copper primary sulfides over a wide range of copper grades, from 0.1 to 2.2%. Further, it is concluded that despite the copper grade, the tests with increasing chalcopyrite content render copper recoveries up to 4 times higher compared to the tests under non-catalyzed conditions. Jetti’s catalytic technology is currently being evaluated at larger scales, namely a commercial dump leach operation and 50-tonne crib tests. The results obtained thus far are compared to the results from conventional sulfide heap leaching tests. INTRODUCTION For decades, the mining industry has been focussed to find an efficient and economically attractive process for the leaching of chalcopyrite. Chalcopyrite (CuFeS2) is the most abundant and recalcitrant of the copper sulfides (Singer, 2017). Owing to its abundance and economic importance, it is the most demandable natural source for copper worldwide. In fact, the projected demand for copper is further expected to rise much higher beyond the current demand by the year 2020 (Panda et al., 2015). Therefore, it becomes imperative to find low intensity hydrometallurgical technologies for the extraction of copper from chalcopyrite in ores of such low-grades that are un-economic to concentrate and to augment the supply by extracting copper from ores with complex mineralogy that cannot be concentrated (Watling, 2013).

Jan 1, 2019

By B. Dubé, R. Friedman, J. Oliver, R. Aubertin, M. Burson, G. Panneton, M. Hamilton, J. Ayer

"The Detour Lake gold deposit is located within the northwestern limit of the Archean Abitibi Subprovince of the Superior Province. Mineralized zones are hosted by a sequence of pillowed and massive flows, hyaloclastite units, and altered ultramafic rocks, and are commonly oriented parallel to a series of high-strain zones that are co-planar to the regional-scale Sunday Lake Deformation Zone. Early in its kinematic history, the Sunday Lake Deformation Zone placed older (2.72 Ga) volcanic rocks of the Detour Lake Formation over younger (2.70 Ga) sedimentary rocks of the Caopatina assemblage. Gold mineralization is also parallel to the position of a laterally persistent siliceous rock unit, the 2.725 Ga ‘Chert Marker Horizon.’ The Chert Marker Horizon coincides with the boundary between the mafic-dominated upper Detour Lake Formation and the ultramafic-dominated lower Detour Lake Formation. Stratigraphic and geochronological data suggest that the Chert Marker Horizon is a deformed felsic volcaniclastic unit. At a cut-off of 0.6 g/t Au, the Detour Lake deposit contains 17.26 million ounces of Au within 445.9 million tonnes of rock grading 1.20 g/t Au. Gold occurs in shear-hosted and extensional vein arrays within rocks of the upper and lower Detour Lake Formation and within the Chert Marker Horizon. The Detour Lake deposit has many of the characteristics of a greenstone-hosted, quartz-carbonate vein deposit; its very large size may be attributed to large-scale rheological controls resulting in the formation of dilatant sites in permissive rock units."

Jan 1, 2012

By A. Drouin, D. Lemieux, C. Chouinard

"A gold bearing pyrite concentrate was treated at the demonstration scale (15 t/d) for the extraction of gold using a cyanide-free process. The pyrite was depressed in the flotation circuit in order to promote the flotation of copper and to achieve a sufficient copper grade to meet the copper smelter criteria. However, the recoveries of copper were 80% and only about 50% for the gold was found in the copper concentrate. The balance of the gold (50%) and copper (20%) contained in the pyrite concentrate as a reject from an overall flotation circuit. The gold grade in the pyrite concentrate is 5.40 g Au/t and copper about 0.77%. About 170 tons of pyrite concentrate were processed in the DST demonstration plant. The concentrate was first oxidized using a fluid bed to produce a calcine. Copper was then extracted as copper sulphate using diluted sulphuric acid. The residual solid was submitted to the DST chlorination process for gold extraction. Thereafter, the gold was recovered from the pregnant brine by precipitation over silica using DST proprietary process. The maximum gold recovery by chlorination was 90%. The average gold recovery by cyanidation of these calcines was 71%.IntroductionDundee Sustainable Technologies (“DST”) has developed a chlorination process as an alternative to the conventional cyanidation process for the extraction of precious metals from ores or concentrates. The technology offers viable and efficient gold recoveries and the ability to handle refractory ores and contaminated material (As, Hg, etc..). The process was successfully demonstrated on hundreds of samples provided by various mines, exploration and development projects and has evolved from laboratory experiment to demonstration at an industrial scale.DST’s chlorination process operates in a closed loop circuit, which implies that no liquid effluents are generated. The chemistry and process design allows precious metal deposits containing base metals to be treated viably. The tailings from the process are inert and non-toxic, sulphide depleted and thus non-acid generating. The efficiency of the process has demonstrated excellent gold recoveries within a fraction of the time needed for cyanidation to obtain similar results. The company completed in 2015 the construction of the first industrial demonstration plant operating with the DST technology. The plant has a capacity of 15 tons per day of mineral concentrate, and the ability to extract gold and silver utilizing DST chlorination technology.DST has tested its chlorination technology at demonstration scale on the refractory pyrite concentrate containing 5.40 g Au/t and 0.8 %copper. This auriferous pyrite concentrate, was by-product of copper concentrate respecting the copper smelter norms, is produced in a country where cyanide is prohibited and refractory to cyanidation. The pyrite concentrate was initially processed successfully (gold recoveries: > 90%) by the DST technology at laboratory (2011: 20 kg) and pilot (2014: 5 tons) scales to extract gold. About 170 tons of this pyrite concentrate were processed in the DST demonstration plant located in Thetford Mines."

Jan 1, 2017

By J. C. Johnson

Underhand mining with cemented mill tailings for backfill has proven to be a safe and effective alternative to conventional overhand mining for rockburst prone mines. The ability of the cemented sandfill to survive a rockburst shock wave without failing has been observed at mines in the Coeur d?Alene Mining District many times in the last twenty years. To better understand the dynamic loading of this commonly used support material the National Institute for Occupational Safety and Health (NIOSH) performed laboratory experiments using a split Hopkinson Pressure Bar (SHPB) to quantify the maximum stress and energy absorption of cemented mill tailings from the Galena mine. Cylindrically shaped cemented backfill specimens aged 28 days were placed in the split Hopkinson pressure bar testing apparatus and a dynamic load was applied. The measured peak dynamic compressive strength of the cemented sandfill was 10.6 MPa (1540 psi) and is approximately twice the static unconfined compressive strength (UCS) of 5.5 MPa (800 psi). These test data showed about 95% of the initial energy was reflected away from the backfill and only 5% of the energy was absorbed. This may help to explain why backfilled stopes could withstand seismic events up to 3.5 Richter magnitude (Ml). When a compressive rockburst wave impacts a stope a large amount of the stress and energy is reflected away. The reflected wave is a tensile wave which creates tensile cracks and spalling in the entire wall of the stope. The backfill supports the damaged wall rock and holds it in place. Some of the stress and energy of the rockburst is transmitted into the backfill and because the backfill is being dynamically loaded it has a strength that is twice its static value and absorbs a substantial amount of rockburst energy. Although mining in deep underground mines is an extremely hazardous occupation, the use of underhand mining with cemented backfill for static and dynamic ground control increases the safety of the workers.

May 1, 2007

By Brad Simser

The Brunswick No. 12 Mine is a 10 000 tonne per day producer of lead-zinc-copper-silver ore that has been in operation since 1964. Mining of this multiple lens deposit is primarily by blasthole stoping techniques between 400m and 1200m below surface. The combination of a high overall extraction ratio and high horizontal stresses (twice the vertical) has elevated the induced stress regime to levels comparable to much deeper operations. Improved mine design, and a better understanding of how the rock mass responds to mining in high stress environments is essential to improve overall recoveries and maintain safety. Seismic monitoring has proven to be an essential tool at Brunswick, for both short-term safety of workers, and long-term strategic planning. Practical case studies illustrate how seismic data, particularly source parameter information, can be used to measure the rockmass response to mining and improve mining layouts in difficult regions. As the global trend continues towards mining in deeper, higher stress environments (e.g. South African Witswatersrand Basin, Sudbury Basin) and as local extraction and thus ground stresses continue to increase in existing deposits, seismic monitoring will play a critical role in mining safely and economically.

May 1, 2003

By Magnus Evertsson, Johannes Quist

HPGRs have since introduced in the 1980s (Kellerwessel, 1993; Schönert, 1988), now become integral comminution units at several minerals processing plants around the world. Even though a lot of the initial issues concerning performance, availability and wear have been addressed and solved there are still phenomena and aspects which can be improved and understood further. Schönert and Sander (2002) presented experimental results and a mechanistic model including the internal force dynamics between the rollers and the compacted bed. They derived expressions for the pressure distribution involving most of the influencing terms and effects. However, in order to solve the differential equations several of the terms vanish by assumptions. The Schönert and Sander model reflects the experimental data in many aspects but the predicted shear force distinctly deviates from the experimental results at the angular position of the peak pressure level. This finding suggests that the particle to particle interaction and breakage process in the different zones seen in Figure 1 are complex and difficult to model using analytical models. A numerical modelling approach using DEM does not require the same amount of assumptions and simplifications of boundary conditions. Hence such modelling may provide further knowledge and vital understanding. In this paper the breakage process is simulated in order to investigate the shear slip behaviour and how it relates to different operating variables. A laboratory scale HPGR corresponding to the experimental setup used by Schönert (2002) have been modelled in EDEM (DEM-Solutions). The bonded particle model (BPM) is used for modelling quartz particles (Potyondy, 2004). The breakage model strength parameters are calibrated against interparticle breakage experiments in an Instron 400RD compression device. The contact model parameters are calibrated using calibration methods developed by Quist (2015). The floating roller dynamics are modelled using a spring-damper system. Results present insights regarding the interparticle slip behaviour as well as the frictional tangential force distribution on the rollers. The simulated roller pressure distribution shows good correspondence with previously reported findings in the literature.

Jan 1, 2016

By S. Yadav, T. G. Murthy, C. Saldana

"An experimental study has been carried out in order to study the deformation of porous brittle materials under plane strain indentation. Gypsum, which is well known model system for understanding the behaviour of soft rocks, is used in this study. The effect of wedge angle is investigated in this research through this series of experiments, using wedges of 3 different apical angles. High-speed, high-resolution images are captured using a CMOS camera during the experiment. The images obtained are analyzed using a Particle Image Velocimetry (PIV) algorithm in order to obtain the evolving velocity, strain-rate and strain fields.INTRODUCTIONThe problem of indentation, which is usually referred to in the context of hardness testing is ubiquitous as a material characterization technique for a large class of solids. Mechanical properties of materials such as yield stress, flow stress, fracture toughness, elastic moduli etc. can be related to the hardness of a given solid. The indentation problem involves a given material or solid (whose properties are to be determined) indented by a relatively harder material (indenter) allowing the solid to undergo plastic deformation, which is then related to the yield stress of the material. The problem of indentation and its variants see many applications ranging from mining and petroleum industry, infrastructure industry, manufacturing, and biomedical sectors. Indentation has been extensively studied in metals, with accurate measurement of deformation parameters, stresses and comparison with analytical solutions. On the other hand, understanding of indentation in other class of solids such as cellular solids, porous solids, rocks, and soft solids is still nascent. In case of rocks, a comprehensive understanding of the indentation problem is very crucial because of the obvious applications in mining, petroleum and infrastructure sectors. The inherent porosity, the brittle nature of the rocks, adds to the complexity of indentation in these porous brittle solids. Various theoretical models with degrees of simplifying assumptions have been proposed to study the indentation in rocks. The most common model used in the study of indentation in rocks is a cavity expansion model, wherein a blunt indenter indenting into a rock is approximated with the expansion of cylindrical or spherical cavity in an elastic-plastic material. Complementary studies in understanding fracture initiation and propagation due to indentation has been largely based on the studies of traditional brittle materials such as glass."

Jan 1, 2015

By Edward Sampson

Bases of National Power At a time when the economy of the world is in a particularly troubled state it is appropriate to examine some problems of the distribution of natural resources. I should like particularly to call attention to the remarkable increasing demand for natural resources, to give an analysis of the demand for certain mineral resources, and to direct attention to some problems in satisfying this demand. All industrial power is based on natural resources and the most basic of these are soils, energy resources, and mineral resources. There is a strong interrelation of these resources, more than is obvious, and I shall take up certain aspects from the point of view of a geologist. Few nations are well endowed with all three of the kinds of natural resources I have mentioned and much has been done by some small countries whose peoples are industrious and enterprising and where conditions for free world trade have been favourable. However, major industrial power is dependent on a substantial endowment of all three classes.

Jan 1, 1949

By Arthur Dubé

An account is given of the developments brought about in the last fifteen years by metallurgical research in the field of heat treatment of steels. The practical aspects of these developments are especially emphasized. Methods of representation of the phase-change during austenitizing and sub-critical transformation of austenite are described and the importance of time-temperature-transformation charts for the planning of heat treatment cycles is shown. Special copies such as retained austenite and internal stresses developed on quenching are also discussed in some detail. Due to the interest shown currently in these problems, it has been thought advisable to describe briefly the underlying principles and present some of the results already available.

Jan 1, 1945

By J. A. Meech, G. R. Baiden

"A dynamic simulation of a mine-mill complex has been conducted using networked microcomputers (IBM PC/AT and IBM PC/XT). These models allow simultaneous operation of an open pit using shovels and trucks, a primary crusher, and a secondary crushing plant. Each process transmits information via the network, linking all operations together. The effects of blasting, ore quality, equipment utilization and configuration on productivity can be studied either interactively or from a report listing at the end of each shift. Programs are menu driven leading the user through the decisions required in day to day operations. The mine-mill simulator is currently being used as a teaching tool at Queen's University to provide senior mining and mineral processing engineering students with an experience and appreciation for the operating problems across the mine-mill interface. The need for coordination and close communication between the mine and mill can be aptly demonstrated using these models. The simulator could be used to contribute to the training of operating personnel in a real mining operation. INTRODUCTIONThis paper describes a computer simulator that is capable of showing the interactions and operating strategies between a mine and a secondary crushing plant. The simulator uses two models developed at Queen's University; one for open pit mining and the second for secondary crushing. PITSIM is a dynamic shovel/truck haulage model origin2lly developed by P.D.D. Chick (1) and K.G. Fytas (2) to solve shovel/truck scheduling problems. CRUSHSOFT is a dynamic secondary crushing plant model developed by R.J. Tucker (3) and C.A. Harris (4) to study alternative operating and control strategies in a crushing plant."

Jan 1, 1987

By T. G. Joseph, K. Barron

A strain-softening constitutive relationship is introduced that describes the post-failure stress-strain curve for rock regardless of whether the rock is intact or broken. The core of this relationship is an “apparent friction” concept that relates the post-failure apparent cohesive and frictional characteristics of the rock to the strain. The relationship can be determined for a given rock via a series of triaxial strength tests establishing the peak strength and corresponding strain for a range of confining pressures, together with the determination of the base angle of friction via a simple tilt test. The postulates and assumptions used in deriving this relationship are verified from results of tri-axial tests on both intact and broken rock. This strain-softening relationship is then applied to coal. Having determined the post-failure stress-strain curve for coal specimens, this information can then be used in a finite element program, such as Phase 2, to examine the post-failure characteristics of coal pillars. Using example data, the strength of coal pillars of different width/height ratios are estimated and compared with well-known empirical pillar size-strength relationships. In addition, the post-failure stress-strain behaviour of a coal pillar is compared with an empirical relationship reported in the literature.

Jan 1, 2003

By H. M. Lizama, R. L. Stephens

Secondary leaching of previously leached supergene copper ore has been developed and implemented at Teck’s Quebrada Blanca operations. This consists of using in-situ leaching techniques aided by geophysics to recover the residual metal value from dormant copper leaching heaps. These heaps of crushed and agglomerated ore had been leached 20 years previously but still contained significant copper values. The concept was first tested on a 3,200 m² sector, where injection wells introduced leaching solution into a production zone and electro-resistivity tomography was used to track solution movement within. Operating parameters such as well spacing and injection flow rates were determined. Copper recovery and leaching performance were evaluated based on solution and metallurgical balances. Both ferric leaching and bacterial leaching were enhanced through strategies to pull air into the heap. Positive results from the initial test prompted a larger, industrial pilot test on a 60,000 m² area and 97 injection wells. This larger test obtained a copper recovery of 30% in 457 days. Secondary recovery is now being implemented to all of the abandoned heaps at Quebrada Blanca and has become a production stream. This technology has the potential of wide application to mature copper heap leach operations, and Teck has patented the process and associated methodologies. INTRODUCTION Heap leaching of copper secondary sulphides has been carried out at Quebrada Blanca (QB) since 1994. Ore from the supergene deposit was crushed and agglomerated prior to leaching. Originally, the ore was leached in 6 m lifts stacked one on top of another, known as a static pad configuration. However, in 1998, after the second lift, the operation changed to a dynamic pad configuration; the ore was leached in a single lift and the resulting residues were removed to make way for fresh ore (Yáñez, Ahlborn, & Ramos, 2007). The first two static lifts were left in place and served as a foundation for the dynamic lifts above. Those two buried lifts of leached residues, some 16.8 million tonnes and covering an area of approximately 0.71 million m², remained buried under the dynamic pad.

Jan 1, 2019