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By Collin Bartlett, H. Storch

"Modern metallurgical processes operating with oxygen enriched air, such as the Outotec Flash Smelter and Flash Converter, generate very concentrated SO2 off-gas, which in combination with Outotec sulphuric acid plant technology allows the production of high pressure steam to be used for power generation. Outotec combines well proven technology of sulphur burning plants for this purpose with metallurgical plants.The application of Outotec’s proven LURECTM process enables processing of SO2 gas of up to 25 vol.-%. This process maximizes the energy recovery from the SO2 oxidation at a suitable high temperature level which can be turned into high pressure steam. The application of the Outotec HEROSTM heat recovery system enables the generation of low pressure steam from the absorption energy released at the intermediate absorption step. Additionally, energy is also recovered in the acid coolers for boiler feedwater pre-heating.The concept of integration of high and low pressure steam in combination with the pressurized operation of the boiler feedwater deaerator, thus heating up the boiler feed water to temperatures around 160…170°C, enables indirect transfer of low pressure steam (for deaerator operation) into more valuable high pressure steam, which improves the degree of heat recovery. This is the characteristic of Outotec’s HEROS+TM process.The increased generation of high pressure steam will in turn enable the generation of more electricity when compared to a standard traditional sulphuric acid process."

Jan 1, 2014

By M. Scobie, G. R. Baiden

"This paper describes recent developments at Inco Limited, Ontario Division, in the field of information systems for automated mining. A CA TV cable network has been combined with a broad spectrum radio antenna system to allow the supply of voice, data and video services to underground mining. The system formed the basis of a field experiment at the Copper Cliff North Mine of the Ontario Division in 1990.The experimental information system was developed to supply underground mining with voice, data and video services to mobile and stationary locations. In order to test the communication system, telephones and radios were linked together with the outside phone lines for voice communication. Stationary data was implemented on a SCADA (Supervisory Control and Data Acquisition) system for mine monitoring and control using PLCs (Programmable Logic Controllers), while using personal workstations for the mine planning and engineering functions. Stationary video was installed in the experiment to observe crushing, conveyor transfer points and skip dumping areas. Mobile data and video were tested by the teleoperation of an LHD. The functions supplied to the vehicle were monitored through a computer, with control being maintained through a standard radio interface and real time video pictures for the operation of the machine.This paper discusses the field testing of the information system and results achieved to date. It concludes by discussing the options considered to be open to provide information systems for future automated mining."

Jan 1, 1992

By H. W. King

"Cryogenic engineering is concerned with components and machines which operate for long periods of time at temperatures within a few degrees of absolute zero. The absence of a ductile-brittle transition is thus the prime component of the specification for a suitable low-temperature alloy. The word "" cryo"" means ""frost-forming"" , and this leads to the second component of the alloy specification, which is resistance to corrosion in humid atmospheres. Further, although most early applications of low-temperature alloys were limited to the storage or transportation of liquified gases, an increasing proportion of alternative energy storage and conversion technologies are being based on the availability of high-field superconducting solenoids. The third basic component of the specification for a low-temperature alloy is thus the absence of a low-temperature ferromagnetic transition.Although the firs t two of these components of the specification can be met by using austenitic stainless steels, many of these supposedly "" non-magnetic"" alloys have been found to undergo martensitic transformations to ferromagnetic phases at very low temperatures. In addition, steels which remain structurally stable may still exhibit other magnetic transitions, e.g. to antiferromagnetic or superparamagnetic states. The successful application of these alloys in cryogenic engineering has thus required an initial basic study of the types of magnetic transition that can occur in such concentrated solid solutions, followed by a more applied study directed at an alloy formulation which will induce beneficial magnetic states at low temperatures."

Jan 1, 1981

By H. W. Hughes

"The Wasamac Gold Mines mill, situated 10 miles from Rouyn-Noranda on highway 59, commenced milling April 1st 1965 at a rate of 700 tons per day. This has gradually increased to over 1200 tons per day in December. The mill has done up to 1400 tons on occasion.The ore was formed in the Wasa shear zone by means of replacement. The minerals which replaced the original rocks were carbonates, quartz, pyrite, chlorite, gold and silver. Work index varies from 9. 6 on the chlorite to 11. 6 on the quartz. The gold is very finely disseminated throughout the gangue and while associated with the pyrite is not included in the pyrite. Very seldom is gold found or seen in the free state.Test work showed a medium fine grind of 85 to 90 per cent was necessary to achieve a 95.00 per cent extraction. Straight cyanidation time of 30 to 36 hours was indicated. This has been borne out by subsequent mill performance with a grind around 87 per cent minus 200 mesh and extraction ranging from 95 to 96 per cent.When it was decided to bring the Wasamac property into production, the Bicroft Uranium Mines Ltd. crushing and grinding units together with one pebble mill and the pachuca tanks from Dyno Uranium Mines Ltd. were purchased.Wasamac crusher house and mill buildings are of laminated wood construction, covered with 5/ 8th inch plywood and corrugated iron sheeting."

Jan 1, 1966

By Chan-ho Park

As the building has recently become bigger, higher, and freeform, a technology called BIM(Building Information Modeling), which is a key technology that integrates construction and IT(Information Technology), has been rapidly introduced and expanded. Because BIM technology offers various benefits, countries that introduced BIM early has been actively promoted. However, misperceptions of BIM are prevalent in countries such as South Korea that have adopted it relatively late, with lack of awareness of its fundamental purposes. Under these circumstances, transparent and quantitative performance assessment needs to be executed in order to eliminate the misperceptions, and to explain and revitalize the BIM introduction. These quantitative performance measure KPI (Key Performance Indicators) to be measured should be prioritized. As derive performance indicators in terms of the four types (financial, customer, internal processes, learning and growth), and performance management systems, Uses the BSC to seek a balance between short-term financial goals, values and the value of long-term goals. Uses the BSC(Balanced Scorecards) to derive performance indicators in terms of the four types (financial, customer, internal processes, learning and growth), and performance management systems, seeking a balance between the value of short-term financial objectives and the value of long-term objectives. Through this, the KPI (Key Performance Indicators) which is used for measuring the effect of the BIM will be generated and also the method that can determine whether the generated KPI figures are objectively inter-connected will be suggested as well.

Aug 1, 2013

By M. Timberlake, A. J. Jonaitis

"The DENVER Tube Press is a simple, high pressure (1500 PSI (100 bar)) filtration unit, developed for processing difficult-to-dewater materials and to produce a handleable filter cake and clear filtrate product.Lab and Pilot testwork conducted in Australia on coal fines (55-70% -35 micron (400 mesh)) have shown that total moisture contents of less than 20% are consistently achieved in the final cake products from the Tube Press.currently, these coal super fines are sent to waste due to uneconomical mechanical dewatering methods, which were only able to reduce total moisture levels in excess of 30%. Calculated, throughput rates for the 500 series Tube Press exceeded 1700 kg/hr (3750 lbs/hr). Feed solids concentration requirements are between 45 and 50% to achieve these results.INTRODUCTIONThe DENVER Tube Press is an automatic membrane high pressure filter press, which operates at hydraulic water pressures up to 1500 PSI (100 bar). The Tube Press was developed in the late 1960's by Charlestown Engineering, st. Austell, Cornwall, England, formerly a division of English China Clays, Ltd., to address more effective methods of moisture reduction of micron-size china clays. The Tube Press reduced moisture sufficiently to produce a hard surface-dry, handleable cake and clear filtrate discharge, which was recycled into the process. This development work was conducted using a 200 Series Tube Press (200 mm diameter x 2500 mm long filter surface)."

Jan 1, 1993

By Behzad Vaziri Hassas, Firat Karakas, Esra Tanisali, Mehmet S. Çelik, Ahmad Hassanzadeh

Coagulation is basically an aggregation process where particles settle under the influence of interfacial forces with electrostatic forces playing a governing role. Although particle morphology consisting of shape and roughness dictates the physical encounter of two particles, their eventual coagulation is not only influenced by columbic forces but also other interfacial forces such as hydrophobic interaction, which affects the extent of aggregation of particles through increasing the distance of interaction. Roughness is well known to increase the effective contact angle on hydrophobic surfaces and also enhance interfacial forces. In this study, the effect of morphology of particles and particularly roughness on the settling velocity and in turn coagulation tendency was investigated. Batch settling tests (BSTs) of different particle morphologies were investigated as a function of pH. Two different morphologies of silica particles were utilized with the same particle size distribution (PSD) including smooth-spherical and rough-spherical (Etched). Rough particles were prepared by acid etching technique using hydrofluoric (HF) at different time intervals (15-300 sec). Etched samples were identified and quantified by optic profilometry. Settling test results showed that the settling velocity of particles in a suspension of 2% solids in the massive settling region is significantly affected by particle morphology of the suspension. Coagulation results further revealed that aggregation of rough particles is faster than smooth-spherical particles. Coagulation results are elucidated on the basis of particle morphology and its effect on distance of separation through hydrophobic forces.

Jan 1, 2016

By Daniel J. Corkery

Mines in Canada and the United States are subject to regulations limiting ammonia, nitrate and nitrite levels in mine effluents released into the environment. The primary source of these nitrogen compounds is typically explosive used in blasting operations, as ammonium nitrate (AN) remains a significant component of most explosives used in the mining industry. The amount of AN entering a local water drainage system is related to site conditions, explosives used, explosive handling and blast efficiency. Mining operators acknowledge AN loss to mine water from blasting operations. However, the mechanisms by which ammonia, nitrite and nitrate are entering the water drainage system, or the relative contribution of specific mechanisms, may not necessarily be assessed or monitored adequately. Characterization of these mechanisms, through systematic investigations, allows a mining operation to focus its efforts on reducing AN loss. This paper outlines a strategy for investigating the mechanisms through which AN enters the mine water drainage system and methods to mitigate this loss. This strategy includes collection and analysis of data to identify and quantify the AN loss mechanisms, design and implementation of tests to mitigate this loss, and assessment of the results. Such investigations are not intended to be a separate one-time project, but part of a long-term process of continual feedback and optimization that is related to the collection and reporting of AN levels for regulatory purposes. The implementation of the strategy must be tailored to each mine?s requirements and existing conditions.

Oct 1, 2010

By P. R. A. Andrews, R. K. Collings

"SUMMARYIn cooperation with the Ontario Ministry of Natural Resources, selected deposits of Potsdam sandstone in the Ottawa-Kingston area were core-drilled and evaluated by CANMET as potential glass and foundry sand. Analyses of cores ranged from 84.6 to 98.5% Si02, 0.09 to 0.65% Fe203' and 0.07 to 2.10% A12°3' The cores were largely composed of white to grey, relatively tough sandstone. Impurities included iron as pyrite, iron oxides and staining on the quartz grains; carbonates as calcite; and aluminum oxide as feldspar. Beneficiation included size reduction to grain size, about 600 um, by jaw, roll and cone crushers, and grinding in a muller-mixer. Removal of fines was achieved by attrition scrubbing and washing. Further removal of impurities was achieved by reverse flotation of pyrite, iron oxide, feldspar, and carbonate minerals employing both anionic and cationic collectors. Flotation resulted in a substantial improvement in the quality of most samples; analyses of quartz concentrates showed 98.5 to 99.7% Sial> 0.022 to 0.156% Fe203' and 0.07 to 0.62% A1203. Further reduction of the iron content by wet magnetic separation and acid leaching also was investigated. On the basis of the samples submitted, sands/ones from six of the seven deposits studied have potential as sources of glass sand. Foundry sand tests were inconclusive because of the small quantities available for study."

Jan 1, 1986

By Nigel J. Cook

"Detailed mineralogical examination of gold-bearing rocks, ores, concentrates and other samples should be considered an integral part of any study of a deposit for which exploitation is being planned. Adequate mineralogical study, although time consuming and often costly, can significantly improve understanding of the mineralization, can help to optimize the results of any metallurgical testing and can be of great value in case of potential trouble-shooting. The advantages and disadvantages of various examination techniques are discussed with reference to a number oj mineralogical studies oj Canadian gold-bearing samples.IntroductionVarious authors, notably Gasparrini (1983), Harris (1989) and Henley (1990), have stressed that mineralogical study of gold ores is critical to successful and efficient beneficiation. Only in cases where diagnostic cyanide leach testing is successful can detailed mineralogical examination be disregarded. Such examination of gold-bearing rocks and metallurgical products is all too often neglected because the methods involved are believed to be time-consuming, costly, and may carry a considerable degree of inaccuracy. Commonly, bulk metallurgical testing is, carried out without prior or concurrent mineralogical examination, causing the results of the testwork to be difficult to interpret, or in some cases, misleading. This, in turn, may lead to> significant delays to the project at the feasibility stage or mean that understanding of the sample is limited, preventing the introduction of prudent modifications at a later stage if problems arise. Mineralogical studies may guide the successful implementation of a metallurgical test program."

Jan 1, 1990

By John A. Herbst, Gerald H. Luttrell, Jaisen N. Kohmuench, Aaron Noble, Michael J. Mankosa

The HydroFloat TM is an innovative fluidized-bed separator that can substantially increase the upper particle size that can be successfully treated by flotation. Recent studies conducted using laboratory, bench-scale and pilot-scale equipment indicate that this technology can be used to float coarse sulfide middlings that cannot be recovered by conventional flotation machines. Recent data collected from pilotscale tests conducted at a base metal concentrator indicate that this technology can float middlings particles as large as 850 microns in diameter containing as little as 1% exposed hydrophobic mineral. As such, the crossover of this technology into the base metals industry has the potential to substantially reduce grinding costs and increase concentrator recovery/capacity through the use of split-feed circuitry. The split-feed concept, which is often used for upgrading industrial minerals, involves segregation of the feed into more than one size class followed by subsequent upgrading using mills/separators/reagents specifically optimized for each size class. In this article, a split-feed circuit is described that utilizes two stages of classifying cyclones in conjunction with the HydroFloat_ separator. The circuit is designed to recover, recycle and regrind coarse middlings containing small amounts of valuable mineral while simultaneously rejecting coarse well-liberated siliceous gangue so that mill throughput can be increased. Simulation data conducted using well-known process models suggest that this approach can increase existing primary mill capacity by up to 25% with only modest investments in new classifying and flotation equipment.

Jan 1, 2016

By D. Yu, T. A. Utigard, M. Barati

"Sulfation roasting of nickel concentrate to generate water-soluble metal sulfates was investigated as an alternative process to smelting for the recovery of valuable metals. The kinetics of dissolution of various species of the calcine in three leachants was studied; hot water, dilute HCl, and concentrated HCl. The results indicated that dissolution of sulfates by hot water at 90 ºC is achieved within 30 minutes. In order to increase the recovery of the valuable metals, acid leaching is necessary due to the existence of ferrite in the calcine.INTRODUCTIONInvestigations on the sulfation roasting of nickeliferous sulfide ores or concentrates were mainly carried out in 1950’s to 1990’s to generate water soluble non-ferrous metal sulfates followed by metal recovery by leaching (Stephens, 1953; Thornhill, 1954, 1961; Fletcher and Shelef, 1964a, 1964b; Fletcher and Hester, 1964; Frankiewicz, 1977; Norrgran, 1983). Commercialization of the sulfation roasting process was only performed by Falconbridge Ltd. (Thornhill, 1961; Boldt, 1967), which employed a sulfation roast process on nickeliferous pyrrhotite at 680 oC where Ni, Cu, and Co were leached and Fe2O3 was produced for the iron industry. In 1965, 118,342 tons of pyrrhotite was processed, however because of the huge SO2 emissions (no acid plant) relative to the nickel production and the poor economics, this plant was shut down.Nickel production from sulfide ores via pyrometallurgical means, especially the electric furnace smelting process, is a major emitter of SO2 to the environment and a big energy consumer (Warner, Diaz, Dalvi, Mackey, Tarasov and Jones, 2007). Nowadays, due to the more stringent environmental regulations as well as the need to reduce energy consumption, metal production by sulfation roasting is gaining more attention as an alternative process to smelting. The main focus of this paper is to investigate the extent and rate of leaching of valuable metals from the sulfation roasted nickel calcine, aiming to maximize the metal recovery and minimize the dissolution of iron species."

Jan 1, 2012

By L. B. Smith

Introduction The property of Wright-Hargreaves Mines, Limited is situated at the northeastern end of Kirkland lake, Ontario. It lies immediately east of the Lake Shore mine, and about in the centre of the Kirkland Lake camp. The district is served by the Swastika-Rouyn branch of the Temiskaming & Northern Ontario railway, the town of Kirkland Lake being four miles northeast of Swastika, which is 63 miles north of Cobalt and 392 miles north of Toronto. The mine is developed by three shafts and has more than twenty-eight miles of underground workings. There are two main producing veins, which lie in a porphyry boss 1,350 feet wide. Milling started in May, 1921, and to-date (January, 1933) the mine has produced gold to the value of $21,770,183. Present production is at the rate of 800 tons of ore per day. For a description of the geology, reference may be made to the report by E. W. Todd on the Kirkland Lake Gold Area (1). Structure and Ore Deposits The two major productive veins on the Wright-Hargreaves property are known as the North vein and the South vein. In the vicinity of the shafts these veins are approximately 550 feet apart. A third vein, known as the Inclined vein, has been worked from its junction with the South vein at the 2,000-foot level to its intersection with the North vein at the 800-foot level. This inclined vein has to date been found only in the area east of the eastern major north-south fault. The main North vein and South vein have a general vertical dip, although local rolls and post-ore faults throw certain sections out of line. From the surface to 3,900 feet, the North vein is displaced south less than 200 feet, and the South vein at the same horizon is almost perpendicularly beneath the surface showings.

Jan 1, 1934

By A. O. Sfriso

"Numerical modelling is becoming universal in rock engineering practice. Most applications focus on the prediction of failure loads of 2D problems, where the numerical models are useful extensions to analytical methods and experience-based design criteria. For 3D problems and problems where the assessment of serviceability indicators – displacements, ground-structure response, etc. – are of importance, the selection of the constitutive models themselves and the implications of the selection of material parameters may have a very heavy impact on the reliability of the model outcome and its predictive capability.This paper overviews basic common aspects of constitutive equations used in practical rock engineering and summarizes some challenges that are frequently observed when reviewing numerical models performed for routine problems in rock engineering. INTRODUCTIONNumerical methodsFrom a philosophical perspective models, either analytical or numerical, are idealizations of a perceived reality. For us engineers, models are just tools we use to guide our judgement and understanding of the problem in hand. When dealing with problems in rock engineering, we resort to a wide range of techniques:1. Closed form solutions like confinement-convergence methods for circular tunnels: these methods satisfy equilibrium and compatibility requirements at the cost of a crude simplification of the material behavior and geometry;2. Limit analysis methods, like bearing capacity formulas: lower bound methods satisfy equilibrium but sacrifice compatibility, and upper bound methods do the opposite. Material behavior must be simple, geometry admits limited freedom;3. Limit equilibrium methods, like method of slices for slope stability: they satisfy restricted forms of equilibrium, do not satisfy compatibility requirements, require simple material behavior but have a much greater flexibility on geometry;4. Numerical methods, where a mesh is employed to discretize the problem geometry: when properly formulated, these methods satisfy equilibrium and compatibility requirements and give reasonable approximations to the behavior of very complex geometries and construction sequences. Very little restrictions remain on geometry and material behavior, but the cost of calibrating the material parameters can be very high."

Jan 1, 2015

By Y. Tang

"Rare earth elements (REEs) have many key applications in traditional and advanced technologies. A shortage of several critical REEs is expected due to the discrepancy between the availability of REEs from REE deposits and the REE demand from the market. REE recovery and separation from secondary resources such as uranium wastes and recycled materials might help balance the shortfall in a cost-effective way. This paper presents data concerning the recovery of heavy REEs (HREEs) from uranium raffinate. It also discusses the design, commissioning, and operation of a solvent extraction pilot plant for the separation of REEs.RÉSUMÉ Les éléments des terres rares (ÉTR) trouvent de nombreuses applications importantes dans les technologies classiques et de pointe. On prévoit une pénurie de plusieurs ÉTR critiques en raison des divergences constatées entre la disponibilité des ÉTR provenant de gisement d’éléments des terres rares, et la demande d’ÉTR sur le marché. La récupération et la séparation des ÉTR à partir de ressources secondaires telles que les déchets générés par le traitement du minerai d’uranium et les matériaux recyclés pourraient contribuer à équilibrer cette pénurie de manière rentable. Cet article présente des données relatives à la récupération des ÉTR lourds (HREE, de l’anglais heavy REEs) à partir de raffinat d’uranium. Il aborde également la question de la conception, de la mise en service et de l’exploitation d’une usine pilote d’extraction par solvants pour la séparation des ÉTR INTRODUCTIONSignificant amounts of strategic specialty heavy rare earth elements (HREEs) are present in waste streams in Saskatchewan uranium operations. Selective precipitation including neutralization, oxalate, and double-salt precipitation, as well as sulfide precipitation, ion exchange (IX), and solvent extraction (SX) are commonly used technologies for the recovery and purification of rare earth element (REE) solutions. REE oxalate precipitation can effectively remove Fe, Al, Ca, Si, and other impurities by taking advantage of the solubility difference between REE oxalates and impurities in the acidic solution (Xu, 2005)."

Jan 1, 2018

By W. Roy Dunbar

"The Porcupine area is in northern Ontario at the intersection of N. Lat. 48° 30' and 81° W. Long. It is 125 miles due north of the Sudbury nickel range. Practically all the mineral production of this area has come from the townships of Tisdale, Deloro, Whitney, and Ogden, in order of importance. The accompanying map of the Porcupine area and its extensions to the east and west (Fig. 4) has been included to show what I consider to be an essential objective of this paper, a perspective for exploration.The discovery of gold ore in the Porcupine area at such an early date resulted from the extension of the Temiskaming and Northern Ontario railway and exploratory survey lines north into unexplored territory, for the early history of Porcupine is inextricably tied to the exploration along Niven's survey lines and the extension of the railway north from Cobalt to Nellie Lake. The following are the more significant events leading to the discovery of gold in Porcupine.1896-E. M. Burwash, employed by the Ontario Bureau of Mines, examined the country along Niven's base line and noted quartz veins that carried traces of gold. He was attached to Niven's survey party.1899-The late W. A. Parks reported on the geology of the portage route from Mattagami river to Night Hawk lake, for the Ontario Bureau of Mines. He noted the occurrence of gold in quartz veins and reported “I regard the region south of the trail to Porcupine lake as giving promise to the prospector"". He also was attached to Niven's survey party.1901-Charles Camsell, while prospecting for the Algoma Central railway, did some work on a vein occurrence carrying low gold on ground now known to be part of the Hollinger mine (3).1907- Extension of the Temiskaming and Northern Ontario railway to Nellie Lake.1909- Bannerman followed up Indian story about occurrence of coal, and found iron formation. He remained to prospect and found the gold-bearing vein of the Scottish Ontario property."

Jan 1, 1954

By K. S. Raja, F. Battick, B. Pesic

"CeO2 doped with lower valence cations, such as Y3+, Sm3+, Gd3+ etc. is considered as electrolyte material for low temperature SOFC. Doping introduces additional oxygen vacancies and improves ionic conductivity. This work describes the preparation of yttria-calcia doped-ceria precursor material, its sintering in DC and AC field methods, and characterization of sintered electrolytes with respect to the ionic conductivity. Doped precursor materials were prepared by a controlled co-precipitation process. Sintering of prepared, pelletized particulates was carried out using three different methods such as: 1) conventional; 2) spark plasma sintering; and 3) an alternating current field at 1125°C (AC assisted sintering). The mechanism involved in the conductivity improvement as a function of defect density, grain boundary area and phase stability will be discussed. INTRODUCTIONThe performance of SOFCs depends highly on the properties of materials. Subtle variations in the composition, microstructure, or density of SOFC components can considerably alter the power output capabilities of fuel cells. Early SOFCs utilized zirconia based electrolytes but efforts in lowering the operating temperatures of SOFCs have prompted investigations into several other oxygen ion conductors – often modified with dopants to either promote the formation of oxygen vacancies or to stabilize a vacancy rich high temperature phase – such as bismuth oxide, lanthanum gallate, and ceria.The transport of oxygen ions through the electrolyte first begins with diffusion into the material. While this is generally a surface kinetics phenomenon, it is safe to say that it is highly dependent on oxygen pressure and vacancy gradients. The role of the cathode in SOFCs is to reduce oxygen at the electrolyte surface creating an O2– ion gradient which induces permeation into the material. Once inside and under the influence of a potential field, O2– ions migrate by a vacancy hopping mechanism, Catlow, C.R.A. (1990), effectively exchanging positions throughout the matrix until they reach the anode and react, thus leaving the matrix."

Jan 1, 2012

By Gang Mei, Nengxiong Xu, Yanlin Zhang

After open-pit mining finishes, an iron mine with steeply inclined ore-bodies will generally transform to underground mining. Non-pillar sublevel caving method, with horizontal slice mining from up to down, is commonly used for mining deep ore-bodies under the open-pit bottom. As horizontal slice mining proceeds, a gradually enlarging goaf will be formed under the open-pit bottom, the rocks surrounding the handing and heading sides of the goaf will collapse continuously, and then these results in rock-mass failure with large deformation and displacement in the open-pit slope. Based on FLAC3D, a modeling approach to predict pit slope deformation and failure induced by transitioning open-pit to underground mining is proposed in this paper. This method mainly consists of three procedures of modeling, i.e., mining modeling, landslide modeling, and filling modeling, of which landslide modeling is the core of the proposed approach. In the procedures of modeling with FLAC3D, iteration non-convergence is taken as a local failure criterion of pit slope. When iteration calculation cannot converge, the sliding modeling will start by deleting some elements with large displacements, and finish until convergence. Before modeling landslide, several displacement contours of rock-masses in the pit slope are searched out, and each contour is an approximate possible sliding surface of the open-pit slope. From these contours, the most proper one is selected as the slope sliding surface by using the iteration calculation convergence and minimum element deletion as the judgment condition. Landslide modeling is then realized by removing the elements outside the slope sliding surface. Finally, to demonstrate the effectiveness, the proposed approach is used to simulate the process of open-pit to underground mining at Yanqianshan Iron Mine, and to predict the deformation and failure characteristics of open-pit slope during underground mining. The case study results show that: the prediction of the slope stability determined by using our method is consistent with that calculated by using the limit equilibrium methods.

Jan 1, 2015

By J. A. Espinosa-Guillen, J. A. Lopez-Molina, S. García, J. A. Valencia-Quintanar

"The design and implementation of grouting treatments in rock masses are procedures that require continuous adjustment of parameters and criteria to optimize the results. In this proposal we describe a set of tools that enhance decision-making for this type of jobs particularly in dam projects. The methodology is focused on hydrogeological zoning of the site and its constant update combining engineer’s experience with artificial intelligence techniques to integrate the site knowledge; as well as the evaluation of grouting results for different scrutiny scales, with special attention on the relationship between water absorption and grout consumption. INTRODUCTIONSeveral methodologies for design, implementation and evaluation for grouting rock masses have been developed for the solution of specific problems and tested in diverse geological conditions. Each of these methodologies is focused on results evaluation for different scrutiny scales (Table 1) and is employed to assist decision-making before or during the grouting process.Some methods define specifications for grouting each stage of the borehole, making theoretical, semi empirical or experience-based considerations to define basic parameters as maximum pressure, maximum volume, grouting time, flow rate, etc. Ultimately each approach aim to optimize the injection process, adjusting volumes or the grouting time required to obtain satisfactory results, reducing risk of creating new flow paths or unnecessary grout travels, and enhancing the mixture properties to achieve adequate penetrability and long-term behaviour. Some of these criteria have been widely used in dam projects, for example the concept of Grouting Based on Facts to define the maximum pressure and volume (Ewert, 1997), the GIN method (Lombardi & Deere, 1993; El Tani, 2012), or the North American standards based on Apparent Lugeon measures (Naudts, 1995; Bruce 2011); on the other hand, there are relatively new criteria that have shown good results for dam grouting as the Aperture Control Method (Bonin et al., 2012; Carter et al., 2012) or the Real Time Grouting Control Method (Stille et al., 2012)."

Jan 1, 2015

By A. Perucho, J. P. Harrison, A. Bedi, L. Alejano, L. Lamas, A. Sofianos, A. M. Ferrero, R. Migliazza, R. Olsson, J-F. Mathier

"In 2010, the Eurocode for Geotechnical Design, EN-1997-1:2004 (CEN, 2004), informally known as Eurocode 7 or EC7, became the Reference Design Code (RDC) for geotechnical design – including rock engineering design – within the European Union (EU). EC7 is one standard within the comprehensive Structural Eurocode suite, which as a whole has been also adopted by a number of other countries beyond the EU. EC7 is thus becoming a key design standard for geotechnical engineering worldwide.As part of the Structural Eurocode suite, EC7 requires designs to adhere to the principles of Limit State Design. However, it is not clear that current rock engineering design practice can satisfy this requirement. In addition, evidence is accumulating that EC7 is currently difficult to apply to, and may even be inappropriate for, rock engineering design. These issues may be due to the fact that the development of EC7 to date took place without any formal input from the international rock mechanics and rock engineering community.In early 2011 under the auspices of CEN (Comité Européen de Normalisation / European Committee for Standardisation), EC7 entered a formal period of maintenance which was aimed at improving the applicability and ease-of-use of the Code. This maintenance cycle will conclude in 2020 with the publication of a revised version of EC7.This paper describes a number of critical aspects for rock engineering in the context of EC7, inparticular the following:– the history of the Structural Eurocodes and the concepts they embody;– the nature of Limit State Design and the challenges and opportunities it poses for rock engineering design;– the formal means by which the Structural Eurocode maintenance cycle proceeds;– the plans currently being developed for improving EC7 with regard to rock engineering design and construction;– the unique and vital opportunity for the entire international rock mechanics and rock engineering community to comment on the Code and make suggestions for its improvement."

Jan 1, 2015