Search Documents

By M. K. Jain, Z. T. Xu, M. Bruhis, V. Hegedekatte

"Strain rate and temperature dependent deformation conditions are present during elevated temperature forming of aluminum and other metallic materials. While many constitutive laws have been proposed to represent such deformation conditions, a closer investigation often reveals their limited applicability in terms of fit to the experimental data, and interpolation within and extrapolation outside of the range of experimental stress-strain curves. This is often because material-specific primary deformation mechanisms of temperature-dependent strain and strain rate hardening are poorly captured. In the present work, the Voce-Kocks constitutive model based on mechanics of dislocations storage and annihilation has been found to be suitable for many metallic materials. The model was modified to include the effect of temperature dependent shear modulus. The modified model is then employed to represent the experimental data obtained from uniaxial tensile tests on AA7075-O sheet at elevated temperatures and strain rates. Also, hot gas bulging tests were conducted to verify the applicability of this model. Further, finite element simulation of the hot gas bulge test was performed by incorporating the model as a user material subroutine. Good general agreement was observed between the experimental and FE model predicted results. Some sources of discrepancy in the prediction are also discussed.INTRODUCTION There has been much interest in light-weighting of automobiles from automotive related industries to reduce overall carbon footprint and increase energy efficiency of the vehicles. Aluminum alloys, and especially the medium-strength 5xxx and 6xxx series alloys, have been the primary focus in the last 3 decades to reach the above environmental goals (Huo, Hou, Zhang, & Zhang, 2016) whereas aerospace industry has traditionally focused on high strength 7xxx series aluminum (Al-Zn-Mg-Cu) alloys for structural components (Deng, Yin, & Huang, 2011). Recently, there has been much interest in high strength 7xxx series aluminum as a replacement for heavier steel automotive structural parts such as A-pillar, B-pillar, side impact beams etc. (Harrison & Luckey, 2014). This is both interesting and challenging since the above aluminum structural parts will need to not only meet impact safety standards but also possess sufficient formability for manufacturing such complex parts. Since the formability of high strength 7xxx series materials is quite poor at room temperature, much interest has focused on improving both formability and final part strength via high rate hot stamping, in-die quenching, and subsequent artificial ageing process steps (Kumar & Ross, 2016)."

Jan 1, 2018

By N. Campbell

"The fault under consideration follows a northerly trend past the west; side of the original settlement of Yell ow knife; which is situated 600 miles; north of Edmonton and 400 miles from the Northern Alberta Railway; terminus at Waterways; Alberta. The mining properties chiefly concerned; include the southern part of the Giant claims; on the east side of the fault; and the Con-Rycon-Demelt claims; on the west side 3 1/2 miles to the south.; Geological data were also obtained from the eastern part of the A.Y.E.; property; which lies south of the Giant claims; and from the Negus; Meg; Yellorex; and Kam properties; which are south and southeast of the ConRycon-; Demelt claims (see Frontispiece; also Fig. 5).Recognition of the major faults in the Yellowknife Bay area, including the West Bay fault, which appears to be the greatest, resulted from the work of A. W. Jolliffe (formerly of the Geological Survey of Canada) in 1935 and subsequent years. It has been stated with little exaggeration that these faults rank with the largest known steeply dipping dislocations of the earth's crust.In the winter of 1939, a mineralized shear zone named the 'Creek vein' was found on the Giant property. It was noted that the space relationship between this shear zone and a body of quartz-feldspar porphyry is roughly the same as that between the Con C-4 shear zone and a body of acid flows lying north of the Con property. Coupling this relationship with the assumption that the movement along the fault is dominantly horizontal, it was postulated that the Giant shear zone represented the faulted extension of the Con C-4 shear zone.As geological information became more extensive, certain weaknesses in this concept became apparent, and when spectacular orebodies were discovered on the Giant property in 1944 the question of possible faulted extensions became an important consideration. Consequently, in the spring of 1944, an extended investigation was undertaken, the results of which are embodied in this paper."

Jan 1, 1954

By A. Proulx

Durant les années 1955 à 1961, plusieurs campagnes d?exploration ont été menées sur la zone Bond dans la partie sud-ouest de l?anneau nord de la carbonatite d?Oka (propriété de Niocan, figure 1). Les zones minéralisées HWM1 et HWM2 sont découvertes à l?ouest de la propriété. Un des forages, le S-60, avait intercepté 80 mètres de minéralisation à 0.71% Nb2O5 à l?est des zones HWM1 et HWM2 mais aucun autres travaux d?exploration n?avaient été réalisés sur cette interception minéralisée. En 1995, Niocan réalise une campagne de forage pour mieux définir la zone minéralisée recoupée par le forage S-60. En 1997, une seconde campagne de forage détermine un tonnage de 14.37 Mt avec une teneur de 0.66 % Nb2O5 pour la zone S-60 (Marcotte et Gagnon, 1997). Le complexe carbonatitique d'Oka se situe à environ 35 km à l?ouest de Montréal sur la rive nord du lac des Deux-Montagnes. Sa formation remonte au Crétacé précoce (entre 117 à 123 Ma). La carbonatite d?Oka fait partie de la suite d'intrusions alcalines que constituent les collines Montérégiennes. Le complexe a une forme allongée (7.2 km par 2.4 km) orientée NO-SE (figure 1). Il est intrusif dans des roches précambriennes constituées d?anorthosites au nord et de gneiss charnokitique au sud (Gold, 1963) appartenant à la Formation de la colline d?Oka. Les gneiss au contact du complexe sont fénitisés sur une épaisseur qui peut atteindre jusqu?à 60 mètres. Les roches carbonatitiques forment la série dominante du complexe et elles sont composées principalement de calcite (> 50 %) à gros grain et parfois rubanées. Les minéraux accessoires les plus communs sont la biotite, le pyroxène, la monticellite, la magnétite, l?apatite, la forstérite, la mélilite, le pyrochlore, la pérovskite, la niocalite, la pyrite et la pyrrhotite (Gold, 1963).

May 1, 2003

By G. G. Manekar

MOIL Limited (formerly Manganese Ore India Limited), a Government Enterprise, under the Ministry of Steel, Government of India, produces about 1.1 million tonnes (T) of manganese ore annually from three opencast and seven underground mines. The underground operations are mining using an overhand cut and fill method. The orebody is too narrow for the use of larger equipment and the poor to fair rock mass quality limits the size of stable excavations. Prior to the 1990s underground support consisted primarily of timber square sets in tandem with timber chocks and props. As mine production requirements increased throughout the 1990s led to larger opening sizes and more modern support practices. Research was conducted on ground support design based on rock classification and empirical techniques for designing ground support. Based on the findings and field trials, the Company adopted full column cement grouted cable bolts for back support. Instrumented field trials, using extensometers and load cells on the cable support confirmed the support effectiveness. Stope design was based on two and three dimensional stress modeling which resulted in a significant increase in stope dimensions. The rock mechanics studies for safe stope design were carried out using numerical modeling tool in two and three dimensions for the analysis of stresses. Based on the findings, the safe stope geometry with new stoping parameters was introduced. The earlier stope length of 30 mtrs were changed to 60 mtrs with in situ rib pillar at the cross cuts and in situ post pillars to be left-out in the stope. This leads the formation of of panel comprising of three stopes, for production, supporting and filling. For mechanical handling of ROM in stopes Side Discharge Loaders (SDL) were introduced. The above changes have improved the face productivity from 2?3.5 T with manual operation and 9 T with SDL. The above rapid mining operations has improved the stope productivity but reduced the stope life from 6 to 3 years. For the improvement of the stope availability, further studies were conducted by numerical modeling of stress analysis. The related studies confirmed that with the existing supporting system and proper instrumentation, level interval could be increased up to 45 mtrs from the existing 30 mtrs at deeper levels. At present below 12th Level interval is 45 m at Balaghat Mine. For future mechanization program for introduction of Single Boomers, LPDT, Cutting Machines etc for the development headings rock mechanics studies are underway. The paper provides details of rock mechanics studies that were carried out to study efficacy of the cable bolt support, safe stoping parameters and increased level interval for the improvements in safety, production and productivity at Balaghat Mine.

Aug 1, 2013

By E. J. Debicki

"At the 1992 PDAC Convention, Norman Keevil announced the formation of the Exploration Technology Division (ETD) of the Mining Industry Technology Council of Canada (MITEC). It was evident that base metal reserves in Canada were declining and that the cost of discovering a deposit in Canada was increasing. Coordinated research to develop new exploration technologies was required to discover the next generation of ore-bodies. The ETD was formed in response.The mission of the ETD is to contribute to the survival, profit, and growth of the Canadian mining industry by improving the efficiency and effectiveness of mineral exploration through development of innovative technology by man-aging and coordinating applied cooperative research. In addition, it is the intent of the ETD to become the principal agency by which cooperative research funds are transferred to researchers from the mining industry. The division is industry driven, industry funded and industry managed.The ETD’s Three-Year Plan has focussed80% of its research funds toward two objectives, improving the efficiency of exploration for VMS deposits and establishing the parameters necessary to discover the next Hemlo deposit. The remaining 20% is allocated to other projects, with the current emphasis on geophysics.In 1995, corporate members total twenty-three major mining companies accounting for90% of the exploration expenditures in Canada. The ETD is currently managing ten cooperative research projects totalling $4.6million. Other projects, estimated at $1.6 mil-lion, are currently under development."

Jan 1, 1996

By Dharmendr Kumar, Pradip, Sivakumar Subramanian, Beena Rai, Venugopal Tammishetti

The separation efficiency in a mineral processing plant is generally assessed and reported in terms of elemental assays constituting the minerals of interest. However, different minerals comprising of same elements behave differently under similar process conditions. Thus, it is imperative to track the mineral composition thank elemental composition of different streams in a processing plant. The availability of automated mineral analyzers such as QEMSCAN and TESCAN in recent times has made it possible. However, due to the high cost and expertise required, their adaptation in day to day monitoring of operations is not yet a common place. X-ray diffraction (XRD) profile fitting (Rietveld Refinement) is another technique which can provide estimates of mineral proportions in a sample. The results of Rietveld Refinement however are affected by coating of fines on coarse particles, method of sample preparation, particle size distribution of sample, elemental substitution in mineral crystal lattice. In the present work, we propose a simple and efficient method for quantitative estimation of minerals in iron ores using elemental assays and thermo-gravimetry analysis data. The minerals (hematite, goethite, gibbsite, kaolin and quartz) are identified using powder XRD analysis. It is also observed that goethite contains Al substitution in the crystal lattice. The samples were analyzed for %Fe, %Al2O3 and %Silica using chemical analysis. The measured Loss on Ignition (LOI) in the sample is contributed from goethite, gibbsite and kaolinite phases. LOI from gibbsite and goethite occur in temperature range 250–350°C and LOI from kaolinite occur in temperature range 400–700°C. According, LOI are determined in two different temperature ranges that are 100–400°C and 400–850°C. We have used the data to successfully determine the mineral compositions of iron ore samples. We have also employed a data reconciliation algorithm on the calculated data for further improvement and consistency of our results. Our method is very convenient for quick estimation of mineral proportions in a sample. The proposed method can also be used for quantitative phase estimation in bauxite ores and red muds.

Jan 1, 2016

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 T. Rigg, J. N. Stone

"The process described has been developed to utilize low-grade scrap -turnings, borings, tin cans and other types of ferrons scrap which currently has been of limited or no use in conventional steelmaking processes. If scrap of this type can be converted into high-purity iron by chemical means then there is a potential saving of several million tons of metal annually in North America.The process is chemically quite simple and consists of dissolving ferrons scrap in hydrochloric acid, followed by evaporation and crystallization of the resultant solution to yield ferrons chloride crystal.s. These crystals are dries, briquetted and converted to non sponge by reduction in hot hydrogen. The HCl produced from the reduction step. is absorbed in water and the hydrochloric acid so produced is returned to the dissolver circuit. The hydrogen produced from the initial dissolution of the scrap is used to reduce the ferrons chloride. Purity is maintained by bleeding off impure chloride solutions from the evaporator-crystallizer circuit, and converting these chlorides to oxides and HCI in a high-temperature spray roaster. The HCl produced in the roaster is absorbed in water and the hydrochloric acid returned to the dissolver."

Jan 1, 1970

By Rob Kelso

The PISCES Goals ? To conduct research and develop programs to enable and promote planetary surface exploration ? To host international tests and technology demonstrations at the PISCES Test Site. ? To promote STEM education, inspiring students by connecting Hawaiian culture to space exploration and settlement. - economic and workforce development ? To involve the commercial sector, spinning off technologies to help the local Hawaiian economy. ? To develop a full-scale, technically valid, analog lunar/Martian outpost on Hawai`i Island.

May 1, 2013

By Tugba Cebeci, Bahjat Khoshaba, Bern Klein, Libin Tong, Andrew Bamber

"Sensor-based sorting technologies have potential to pre-concentrate low grade subeconomic ores through discarding the barren waste particles. However, the inability of sensors to accurately discriminate ore from waste is a barrier to prevent their wide applications. The present study focuses on the development of more intelligent sensing systems by using correlation and regression analysis of X-ray fluorescence (XRF) sensor responses on the copper ore samples obtained from Chile. The responses obtained through XRF scanning were reported both in the form of counts and the grades of elements. Linear and multiple linear correlation analyses were made between the XRF counts and the copper grades obtained through chemical analysis. Both the heterogeneity of the ore particles and the matrix effect in the XRF measurement are discussed in the study.INTRODUCTIONSorting can not only discard waste rocks away from the concentrator but also recover metal bearing ore particles that would be lost to the waste dump. The benefits of ore sorting include reduced energy consumption, water and reagent usage in the downstream operations (Bamber, 2008; Gunson, Klein, Veiga, & Dunbar, 2012; Kleine & Wotruba, 2010; Knapp, Neubert, Schropp, & Wotruba, 2014; Kobzev, 2014; Lessard, de Bakker, & McHugh, 2014; Mazhary & Klein, 2015; Robben, Wotruba, Robben, von Ketelhodt, & Kowalzcyk, 2013). X-ray fluorescence belongs to sensor-based sorting technologies and Xrays are a high energy-high frequency form of electromagnetic radiation inhabiting the region between the ultraviolet radiation and gamma rays (Shackley, 2011). Recent XRF sorting studies on low grade copper ores were carried out at MineSense Technologies Ltd. aimed at increasing the capacity related to improving the understanding of ore heterogeneity as the basis for developing semi-bulk or bulk sorting systems (MineSense Technologies Ltd., 2016)."

Jan 1, 2016

By Fatemeh Saeidi, Luis Marcelo Tavares, Malcolm Powell, Mohsen Yahyaei

"Understanding a single breakage mechanism is fundamental to the development of breakage testing techniques appropriate for mechanistic modelling of any breakage equipment. In the light of this insight, it is also possible to compare any two breakage events in a mechanistic manner. This paper presents a new method to compare breakage mechanisms of two-point impact with compression, different in their applied strain rates. This approach regards a single breakage event as a process affected by three sub-processes; first fracture, capture and spatial distribution of fragments. Spatial distribution is influenced by the kinetic energy of fragments and their brittleness. Using this methodology allows us to examine how each sub-process is influenced by applied strain rate and its impacts on progeny size distribution. For this purpose, two rock types of widely different strength, magnetite and silicate, were tested at various energy levels using the impact and compression mechanisms. To isolate the effect of spatial distribution of fragments, particles were forced to remain in the breakage zone. In this condition, similar progenies were generated from compression and impact mechanisms at similar energy levels. However, allowing natural distribution of fragments, coarser progeny was produced from compression of silicate. Additionally, using this approach provides a physical meaning and explanation for rock strength parameters such as A×b in the t10-Ecs relationship. INTRODUCTIONComminution models are rapidly progressing toward a destination that enables us to explain the complete physics of a breakage process as well as the properties of the ores. Eventually, they will be able to take into consideration the micro-events that take place during the comminution process (Bourgeois and Banini, 2002). Thus, considerable efforts have been made in the last few years in the area of ore breakage characterisation to comprehend and unlock a single breakage process that has been treated as a black box event in the majority of conventional methods. In this paper, an attempt is made to explain the effect of applied strain rate on the breakage properties of rock by using the knowledge that has been gained by understanding a breakage event. This is particularly important due to its application for various comminution devices that operate within a relatively broad range of speed."

Jan 1, 2016

By Sanat Talmaki

Construction and mining worksites pose unique challenges to workers and equipment operators due to their dynamic and unstructured nature. Narrow haul roads, crowded work spaces and presence of workers and equipment in close proximity, combined with large blind spots and overall poor visibility afforded to operators lead to collisions and run-over-type accidents between equipment, workers, and other entities that may be present on the jobsite. Operations that involve machine-infrastructure interaction, particularly in the case of concealed infrastructure such as excavation and drilling lead to unintended strikes between the equipment?s end-effect or and the infrastructure. Such accident-prone scenarios can be avoided by providing operators with real-time feedback and warnings using 3D visualization and proximity monitoring of the entities present in the equipment?s vicinity. Thus the jobsite in the real world is abstracted and represented in a 3D virtual world. However, this requires the ability to create a seamless link between real-world sensors present on the equipment and/or the jobsite and the virtual environment. This paper describes a non-restrictive acquisition allocation framework that allows position and orientation sensor streams from construction and mining job sites to be used for updating 3D virtual scenes in real-time for providing vital collision avoidance warnings to equipment operators.

Aug 1, 2013

By Stephan Day

Comments on Robust M3 to Protect Water Quality ?Regulatory and philosophical thinking have tended to evolve at decade scale since 1970s. ?Mines typically last more than a decade. ?Robustness is defined by the ability to adapt to new realities. Managing Water Quality in BC ?1973 ?BC Pollution Control Objectives ?1977 ?Federal Metal Mine Liquid Effluent Regulation (Fisheries Act) ?Late 1980s ?Philosophy of ?Designing for Closure? ?1990s ?Designing for Acid Rock Drainage Management ?2000s ?Awareness of need for water quality management in general, regardless of acidity

May 1, 2010

By K. E. Haque

"This paper is a brief overview of the role of oxygen in cyanide leaching of gold feeds (e.g. ore, concentrate). As the majority of gold occurs in the elemental state (Au °), its oxidation is of vital importance for dissolution in the cyanide lixiviant. The cyanidetion at high pH is favourable for the oxidation of Au° with a mild oxidant such as air or oxygen. Beside oxidation of gold, deleterious effects of soluble sulphides, arsenates, antimonates on cyanidation of gold can be alleviated by preaerating the leach slurry with air or oxygen (i.e. preaeration process).If gold is refractory due to its occlusion in sulphides, silicates, tellurides, etc. then gold liberation is possible by roasting in the presence of oxygen or by leaching under oxygen pressure. The data in the recent literature indicate that reactive oxygen supplied by H202, Na202, Ca02 or 03 during cyanidation can accelerate considerably gold oxidation-cyanidation and yield high gold recovery in much shorter leach time. The information compiled in this review leads to the conclusion that oxygen plays a vital role in the dissolution of gold in cyanide lixiviant."

Jan 1, 1992

By W. M. G. Heeley

In the province of Alberta the coal measures dip at so many different angles, between the horizontal and the vertical, that many different systems of haulage are in use. I will, however, only touch briefly upon the general -systems in use, and devote the major portion of this paper to a discussion of endless-rope haulage and its adaptibility to various conditions in coal mines; dealing in particular with the endless-rope haulage that was installed at Brule during the month of August 1923. In coal seams that are approximately level, and newly opened, hand-putting or tramming from the face is the cheapest, but when the mine is further developed tramming is out of the question, and the use of ponies is the next consideration. The time arrives, however, when mining reaches a point where the economical haulage of coal by horses cannot be done profitably, and then some system of mechanical haulage must be installed. The installation of any system should be carefully considered before any particular type of haulage is adopted, because a great deal depends upon the grade or dip of the seam. Motor haulage is impossible to operate profitably on a grade of over 6 per cent and, while it is possible to use ponies, on short runs, up to 9 per cent, some other means of main and secondary haulage must be installed when a 9 per cent grade, is exceeded. I will, therefore, deal first with secondary haulage, because even though a main haulage is established, secondary haulage can be used to feed the main haulage.

Jan 1, 1925

By J. G. Peacey, G. Csicsovszki

The target of this study was to clarify the role of lead on the dissolution of gold in the (NH4)2S2O3-Cu leaching system via chronopotentiometry, linear sweep voltammetry and chronoamperometry. It was found that the dissolution of gold was significantly increased with lead concentration up to 10 mg/1 Pb in the system of 0.1 M (NH4)2S2O3 and 50 mg/1 Cu. \/oltammograms suggested that the anodic dissolution of gold was virtually independent of lead concentration in the range of 1-10 mg/1 in 0.1 M (NH4)2S2O3 solution while in solutions containing copper as well, addition of lead increased the anodic dissolution of gold.

Jan 1, 2011

"Developed by CRIRSCO, IRT is a document that draws on the best of the CRIRSCO-style reporting standards. These reporting standards are recognised and adopted world-wide for market-related reporting and financial investment.The IRT is not an international reporting code and does not supersede existing national reporting standards. Rather it is a guideline that encapsulates the content of these standards for the benefit of the international mining industry and its various stakeholders.The template is a 'living document' that is continuously updated and improved as new national laws, rules, codes and guidelines are created or amended.The International Template is advisory only and where national codes already exist, these will take precedence. The International Template is intended to assist those countries that either do not have a reporting code or whose code is outdated, to produce a new code consistent with international best practice. It also provides a consolidated version of national codes that reflects their compatible international components and may thus be used in comparisons with other international reporting systems. The word 'Template' is used advisedly to indicate that this document is a model for code development and does not in itself constitute a 'code' which implies that it has legal or other regulatory force.From this point forward, the Template includes words that imply a mandatory action, such as ""requires"", ""applies"", ""must"" etc. This is to enable the Template to be easily adopted by countries and organisations wishing to do so, and does not imply that the Template itself is a mandatory reporting standard.INTRODUCTION2 In this edition of the International Reporting Template (""The Template""), important terms and their definitions are highlighted in bold text. The guidelines are placed after the respective Template clauses using indented italics. They are intended to provide assistance and guidance to readers for interpreting the application of the clauses in the Template.Indented italics are also used for Appendix 1 — 'Generic Terms and Equivalents"", and Table 1 —'Check List of Assessment and Reporting Criteria' to make it clear that they are also part of the guidelines for the application of the Template.Appendix 1 contains a table of generic terms and their equivalents, designed to avoid unnecessary duplication or ambiguity in the textAppendix 2 provides Rules of Conduct for Mineral Resource and Mineral Reserve estimators that may be considered in addition to the Codes of Ethics or Practice normally applying to members of professional institutions."

Jan 1, 2003

By R. A. Nemchek

ABSTRACT Concentrator plant design has evolved from large numbers of small grinding mills to small numbers of large mills. Consequently, plant performance often hinges on the productivity of a single large semi-autogenous grinding mill. Industry attempts to address the grinding mills’ critical nature frequently result in specifications that can be made simpler, more economical, and better focused on the project’s goals. This paper surveys current specification writing practices and proposes an improved approach recognizing that product design, procurement, manufacturing, and quality are interrelated in a successful project. The lessons learned here can apply to all types of machinery specifications.

Jan 1, 2014

By C. Zangerl, W. Fellin, M. Holzmann, B. Hofer, S. Perzlmaier

"Four deep-seated rockslide systems were investigated and are under surveillance by TIWAG (Tyrolean hydro-electric Company) since the mid-1960s after impoundment of Gepatsch reservoir began. These rockslide systems consist of several individual sliding masses (slabs) which show variable activity from zero to a few centimetres per year. The focus in this paper will be on the findings for the transient deformation behaviour of the Hochmais slab which is part of the “Hochmais-Atemkopf” rockslide system.The rock mass has slid over moraine deposits in the last post-glacial period and was in equilibrium (or slow to extremely slow moving, respectively) until the filling of the reservoir began. During the initial reservoir filling in summer 1964 considerable movements had been observed over a length of 1000 m accompanied with an activation of the Hochmais slab. Geological investigations, additional surface and subsurface measurement showed that the sliding mass is characterized by an en bloc movement and the deformation accumulates within a several metre thick shear zone located within the moraine. In contrast to the deformation characteristics for the first impoundment process (1964 – 1966) where the magnitude of deformation occurred during impoundment, the maximum amount of deformation since 1967 occurs during the drawdown of the reservoir. Based on long term measurement it can be shown that the magnitude of deformations per year correlates with the minimum storage level in the reservoir. Other external influences such as precipitation and snowmelt have no observable impact on the deformation characteristic of the landslide. On the basis of long-term data series it was possible to determine the factors of influence and to elaborate a conceptual mechanical model which describes the transient deformation behaviour of the Hochmais slab induced by the drawdown of the reservoir. The mechanical model considers the reduction of uplift forces in the highly fractured and permeable rock slab during drawdown as well as increasing seepage forces in the less permeable moraine material."

Jan 1, 2015

By I. Demers

The abandoned Manitou mine site covers an area of approximately 190 ha near Val d?Or, Quebec. This old site has been generating acid mine drainage for several decades. In 2006, a partnership was established between the Quebec Ministry of Ressources Naturelles (MRN) and Agnico-Eagle Mines to reclaim the Manitou site using tailings from the nearby Goldex mine. These neutral tailings were to be deposited on top of the Manitou site. An extensive study was performed to evaluate specific reclamation scenarios to control acid mine drainage using Goldex tailings as cover material. The article first describes the global approach used for this evaluation, which includes in-situ hydrogeological monitoring, tailings characterization, laboratory column tests, and numerical modelling. Of the thirteen column tests, three were conducted to evaluate the parameters affecting the performance of covers made of Goldex tailings placed over the spillage area of the Manitou site. Geochemical and hydrogeological parameters were assessed during the leaching column tests for almost two years. The tests aimed at evaluating the effect of water table level and monolayer cover thickness on the overall performance. The testing procedure involved monthly leaching and measurement of geochemical parameters. Results indicate that water table position is the most important factor affecting the monolayer cover performance to control AMD. Based on these results, it was established that the water table must be located near the interface between the Goldex and Manitou tailings to effectively reduce AMD generation. Cover thickness also has an impact on cover performance, which is however less significant than the water table position. The testing scenario with a water table located at the interface with a one-meter Goldex tailings cover showed progressive improvement in effluent quality.

Aug 1, 2013