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By Lucas van Latum

A Model for Safety Swiss cheese metaphor of safety layers Image »Multiple layers with independent, often transient failure modes »For a loss to occur, all layers must fail independently and simultaneously ??Latent? failures are due to inherent system flaws ??Active? failures are due to unsafe acts

May 1, 2011

By G. D. Garland

"IntroductionALTHOUGH the presence of rock salt in the Carboniferous basin of northern Nova Scotia has been known for at least one hundred and twenty years, and salt has been mined at Malagash continuously since 1919, certain characteristics of the deposits make exploration by drilling or surface examination difficult. The surface rocks of the basin are, in general, of Pennsylvanian age, while the salt occurs in the Mississippian Windsor group. The latter rocks are brought to the surface only along anticlinal folds, or as irregular fault blocks. Because of the limited areal extent of these Windsor exposures, and their complicated internal structure, geophysical surveys, especially gravimetric, can be of considerable aid in outlining the more favourable areas.The present paper describes the results of recent investigations by the Dominion Observatory, in cooperation with the Nova Scotia Department of Mines. It includes a regional study of that section of the Cumberland basin lying between Springhill and Malagash ( Figure 1), and a much more detailed survey of the immediate vicinity of the Malagash deposit itself. This deposit had been studied by Miller (6, 7) with the torsion balance nearly twenty years before, and a direct comparison between the results given by the two types of instruments is therefore possible."

Jan 1, 1955

By A. Khan

The purpose of this paper is to demonstrate the value of identifying and optimizing throughput constraints by utilizing a Constraint Model. This will be achieved by first understanding the overall concept of Operational Excellence, Continuous Improvement and Theory of Constraints as practiced within Vale Canada Limited. Next, the value of utilizing a Constraint Model is demonstrated by primarily identifying constraints. The applications in utilizing Constraint Models will be demonstrated, including the primary benefit of identifying constraints. The remainder of the paper will focus on how to properly setup a Constraint Model using discrete simulation (regardless of simulation software). Benefits of understanding the severity of constraints and movement of the bottleneck will be recognized. The paper will conclude with the summary of real applications within Vale Canada Limited.

Aug 1, 2013

By N. Ahern, M. Barbanell

Mercury is often present in gold ores and can be released during processing. In view of health and environmental concerns related to mercury, the mining industry takes leadership in the responsible management of mercury. This paper reviews various aspects of mercury management, including an overview of mercury deportment in typical gold processing flowsheets; trends in mercury legislation impacting the international flow and management of mercury in the gold mining industry; and treatment, storage and disposal options for mercury and mercury containing materials.

Jan 1, 2014

By Jerry M. Whiting, Neil J. Duncan

"Does Canada need a mining industry? Isn't it a chronically depressed collection of businesses that pollute the air and water and tear up the countryside? Wouldn't it be better if Canada's investors devoted their attention to high-technology endeavours, tourism, and other relatively pleasant tasks?Probably the answer to whether Canada needs a mining industry in the 21st century is to look at the real mining industry that is in operation today. The facts indicate that mining is a very important contributor to Canada. It has certainly encountered some challenging times during periods of recession, and it face s severe and continuing problems of cost and competition in world markets. However, uneconomic mines have been closed, others suspended, and productivity has risen dramatically with employment at 77 000, down from 101 000 in 1981. The country's metal and non-metal mines, metallurgical plants and semi-fabricated metals industries employed an estimated 378000 workers in 1986, and paid wages than any other sector of the Canadian economy. This effort resulted in the production of 60 different metals, non-metals and structural minerals valued at $13.5 billion.The trade aspects of the mining industry are of paramount importance. If there is a reason for this situation to change during the next century. it eludes the authors. Canada has the well-developed expertise to discover, evaluate, develop, operate and profit from existing and new businesses based in an enormous area endowed with a nearly unbelievable variety of mineral resources. Many countries throughout the world must rely on producers like Canada, if they are to maintain and/or improve their standard of living."

Jan 1, 1988

By A. R. Farkoosh, K. Korgiopoulos, McGill University, O. Rodop, L. A. Villegas Armenta

"New generation of Al-Mg-Si alloys with thermally stable dispersoids that prevent recrystallization and grain growth during hot deformation are currently used in automotive components requiring good formability. Alloy chemistry controls the phase formation especially age-hardening precipitates, dispersoids, and primary intermetallic which have pronounced effect on grain structure, strength and formability. In this work, thermodynamic calculations have been used to predict the effects of varying levels of Si (0.5-1.5wt%), Mg (0.5-1.5wt%) and Mn (0.1-2.5wt%) on phase selection. Thermodynamic calculations have been performed in equilibrium and non-equilibrium conditions via the FactSage™ software using the FTlite database. Selected compositions have been cast, heat treated, extruded and characterized through scanning electron microscopy with energy dispersive spectroscopy and electron channeling contrast imaging techniques. The calculations showed that at the hot deformation temperature of ~540 oC, exceeding certain Mg and Si levels would lead to retained *-Mg2Si intermetallics and Si particles at the grain boundaries in addition to a-Al-(Mn,Fe)-Si. It was found that retained *-Mg2Si phase which adversely affects formability can be avoided for Si+2Mg levels lower than 2.3wt%. FactSage calculations also showed that increasing Mn from 0.5wt% to 1wt% leads to an increase in the amount of dispersoids (from 1wt% to 2wt%) that can potentially slow down recrystallization and grain growth during hot deformation and improve formability. Calculations at room temperature also show that for an alloy with 0.7wt% Mg, excess Si beyond 0.7 wt% promotes the precipitation of Si clusters in the Al matrix that accelerate natural age-hardening. Results were confirmed by experimental investigation.INTRODUCTIONAluminum alloy 6082 (Al-Mg-Si) is used in the automotive industry because of its high strength, and good weldability (I. J. Polmear, 2006). The alloy is age-hardenable through the precipitation of ß-Mg2Si and its precursors, and the recrystallization is usually inhibited by Mn- and Cr-containing dispersoids formed through high temperature heat treatments (I. Polmear & Couper, 1988). However, it is known that minor changes in alloy chemistry (Mg/Si ratio) can have significant influences on the ductility and formability of these alloys by altering phase selection and the resultant microstructure (Gupta, Lloyd, & Court, 2001; McQueen & Celliers, 1997; Zajac, Hutchinson, Johansson, & Gullman, 1994). For automotive applications where wrought alloys (usually extrusions) are cold-formed to produce suspension components, the chemistry of the alloys and the extruded structure are of crucial importance as they determine the formability at room temperature (Asensio-Lozano, Suárez-Peña, & Vander Voort, 2014). In this study, thermodynamic calculations along with experimental investigations were carried out on the Al-Mg-Si system to understand their phase formation and precipitation hardening as a function of alloy composition."

Jan 1, 2016

By William D. Swank, Prabhat K. Tripathy, Tedd E. Lister, Eric S. Peterson, Delon C. Haggerd

More than half of the primary neodymium, produced directly from ores, is being used to manufacture neo magnets. Neodymium, being a critical element in supply, has attracted considerable interest worldwide to recover this metal from a variety of waste streams. From among different recycling processes, hydriding-dehydriding can prove to be highly effective in recycling discarded neo magnets present in consumer electronics. In the present study, manually removed magnets from discarded Hard Disk Drives (HDDs) were subjected to the hydriding-dehydriding process in order to evaluate the resultant products for the re-fabrication of the magnets. The paper describes the effect of experimental parameters on both the hydriding and dehydriding processes as applied to different magnet chemistries.

Jan 1, 2014

By Daniel D. M. Adams

In 2004, Rio Tinto started a major project to implement Mine Monitoring and Control (MMC) systems worldwide. A detailed selection processes was undertaken and migration to a standard system was started. Today systems are operating around the world and serve as the core of to many business processes. Implementations include highly union areas, large mines, centrally managed mines, and remote areas. Each implementation has unique challenges but all are working towards the common goal with common systems. This paper reviews two projects that Rio Tinto has deployed in diverse conditions. The projects are the Rossing Uranium upgrade from the original Wenco system to the common standard and Iron Ore of Canada?s general technology upgrade. Also discussed is the future of mining at Rio Tinto, specifically the drill automation projects, and how it is utilizing the common standard MMC systems.

May 1, 2010

By Carol Odell

This paper was prepared as a brief for Prospectors and Developers Association of Canada (PDAC) to guide input at a series of round tables carried out by the Federal Government in response to the 38th Standing Committee on Foreign Affairs and International Trade (SCFAIT) report, on ?Mining in Developing Countries and Corporate Social Responsibility?. This document mandate is to provide background information, analysis and recommendations on the practice of Canadian exploration and mining companies abroad. This research was based on 11 case studies of Canadian companies which have experienced conflicts or controversies overseas. All case studies were assembled through an extensive literature review of publicly available documentation and communications with representatives of the mining companies to assist in deepening the insights into the drivers of the conflicts and the needs of Canadian companies in similar situations. The case studies include both exploration and mining operations. Our analysis begins with the identification of general and case specific drivers of conflict/controversy in each case study. Company names are kept confidential and only anonymous results are presented. We make ample use of simple flow charts and schematic diagrams to explain how contextual drivers and aggravators and company drivers and mitigators play varied and interrelated roles in conflicts. The diagrams also illustrate the cumulative analysis of drivers including the linkages among drivers/aggravators/mitigators across different domains (social, governance, NGO/media and company). Finally, we discuss needs of companies and propose recommendations for addressing social responsibility and human rights concerns.

May 1, 2007

By Ahmad Ghahreman, Denver Cowan, Yeonuk Choi

"Previous testwork by the authors has indicated that both granular coconut shell based activated carbon and a new microporous carbonaceous bead, Lewatit® AF 5, are highly effective in improving the oxidation kinetics and decreasing the elemental sulphur yield when assisting the atmospheric oxidation of pyrite. While the two carbon catalysts show similar results and improvements to the pyrite oxidation, there are differences between them. For example, the activated carbon assisted oxidation showed faster kinetics than the AF 5 assisted oxidation, while elemental sulphur seemed to remain adhered to the surface of the AF 5 after oxidation when much of the elemental sulphur formed during the activated carbon assisted tests was found in the oxidation residue. The objective of this paper is to investigate the differences between the two catalysts through the use of scanning electron microscopy, photography, Raman spectroscopy, surface chemistry analysis, and Brunauer-Emmett-Teller (BET) surface area analysis. With this investigation the authors should be able to achieve a better understanding of the surface chemistry of the two carbon catalysts (i.e. functional groups, charges, acidity etc.) and help explain the strengths and/or the weaknesses of the catalysts when applied to the atmospheric oxidation of pyrite.INTRODUCTION Previous research conducted by the authors, indicated that both a granular coconut shell based activated carbon (activated carbon) and a microporous carbonaceous bead, Lewatit® AF 5 (AF 5), acting as a catalyst enhanced atmospheric pyrite oxidation in ferric sulphate media by approximately 40% when compared to unassisted oxidation and that elemental sulphur yields were increased from 23% to approximately 69 and 63% when assisted by AF 5 and activated carbon respectively (Cowan, Jahromi, & Ghahreman, 2017). The study indicated that although total pyrite oxidation assisted by the two catalysts was similar, differences were noticed in the impact that the two catalysts had on the outcome of the oxidation. Kinetic curves in the Cowan et al. study indicated that atmospheric oxidation of pyrite seemed to reach completion after 48 hours of oxidation when assisted by activated carbon. A similar trend was noticed in the kinetic curves for oxidation when assisted by AF 5, however the oxidation curve did not reach completion until approximately 96 hours (Cowan et al., 2017). This observation indicated that the kinetics of pyrite oxidation are enhanced by both catalysts, oxidation kinetics are much faster when assisted by activated carbon rather than AF 5."

Jan 1, 2017

By Yi-xin Zhoa

The characteristics of coal bumps are analyzed based on the microseismic data from No.8935 workface in Xinzhouyao coal mine, Datong Mining Group. The geology of this workface is characterized by the thick sandstone roof and coal seam, both with relative higher stiffness and strength. In order to investigate the mechanism and precursors of coal bumps occurred in No.8935 workface, the locations of microseismic, the relationship of microseismic energy and frequency and the spectrum of microseismic signals are analyzed. The result shows that the coal bumps in No.8935 workface were mainly induced by the seismic caused by roof failure. The coal pillar near the goaf is more easily to bump. The statistics results indicate that the coal bumps were mainly occurred in the gate road near the pillar, less than 50m ahead of mining face and located in the hard roof adjacent with coal seam. Moreover, the frequency, energy, b-value and frequency spectrogram of microseismic events were found to decrease before coal bumps. It was found that the frequencies of the microseismic events before coal bumps mainly concentrate upon 5~60Hz. The sudden decreasing of frequency and increasing of amplitude of microseismic events can be regarded as a precursor of coal bumps.

Aug 1, 2013

By Eric J. Grimsey, Don C. Ibana, David E. Grimsey

The segregation process as applied to nickel laterite ores involves the formation of gaseous nickel and iron chlorides which are subsequently reduced to form ferronickel on the surface of a solid carbon reductant. A fundamental study of the process has been carried out using limonite, nontronite and garnierite ores. The study highlighted the significant impacts that ore mineralogy and carbon addition have on the amount of nickel which is segregated rather than retained within the ore due to in-situ reduction. These important aspects affecting nickel recovery and the success of the process are discussed in this paper.

Jan 1, 2017

By Todd Kennedy, Kurt Tischler

"This paper presents the field experience of Siemens with regard to Gearless Drives in the mining industry … We consider the elapsed production hours of Siemens Gearless Drives to be extensive enough to provide a reliable estimation of availability calculated on the basis of data representing repair time, downtime, and operating time. The users of Siemens Gearless Drives confirm an availability of more than 98% after exclusion of some major issues. The paper addresses all of these major issues of Siemens Gearless Drives, describes successfully applied corrective measures, explains the influences on the design of the drives, and lists the downtimes associated with each of these issues. INTRODUCTIONThe first Siemens Gearless Drive in mining began operation in 1980 and was installed on an iron ore grinding mill. As of September 2011, 40 Siemens Gearless Drives will have accumulated 136,000 machine days of operating time. According to pure rules of statistical analysis, this accumulated operating time may be too low to be used for a sample of field data to provide precise statistical values of availability, however we consider it large enough to provide indicative values of worthwhile consideration. This paper deduces the availability statistics of Siemens Gearless Drives in the mining industry from information received from end users and factors in all major issues that Siemens has experienced with our Gearless Mill drives. This paper does not consider Gearless Drives in other industries such as the cement industry. The cement plants, especially in the northern hemisphere, interrupt production for several months in the winter. This lengthy downtime is used to maintain the complete plant including the mills, their motors and their drives. The mining industry has more stringent and higher production requirements. In the mining industry, production must run 24 hours per day, 365 days a year."

Jan 1, 2012

By Margaret Armstrong, Chris Roth

Abstract -Estimating ore reserves for vein type deposits is a two-stage procedure: first, calculate the geometry of the vein system, and second, estimate the grades within this system. The grade estimation can only be consistently performed if the vein geometry - its size, shape and orientation - has been correctly characterized. Getting the size and shape of the different veins right means that the ore tonnages will not be artificially inflated, e.g., by falsely classifying host rock as veins. Similarly, correctly estimating their orientation and location helps mine management decide on the appropriate mining technique, selective or not. When applying geostatistics to estimate the vein geometry all available information needs to be used and not just the standard lithologic indicator of being or not being in a vein.

Jan 1, 1998

By A. Manouchehrian, M. Cai

"Rockburst, which often occurs around underground openings in highly stressed hard rocks, is a sudden and violent unstable rock failure and is associated with energy release. Rockburst is very dangerous to workers and mining equipment, and it has been a major concern for deep underground construction and mining. Before excavation, rocks are loaded under a true-triaxial condition. Upon excavation, the rocks at the excavation boundaries are loaded in the maximum principal stress direction and unloaded in the minimum principal stress direction and this provides a necessary condition for unstable rock failure to occur. Understanding rock behavior under true-triaxial unloading condition is critical for developing measures to control unstable rock failure in underground construction.In this article, an explicit FEM tool is used to simulate rock behavior under true-triaxial unloading condition, with a focus on analyzing stable and unstable failure and the released energy during failure. Firstly, a uniaxial compression test was simulated. The results indicated that the adopted numerical tool was able to simulate stable and unstable failure by varying the Loading System Stiffness (LSS). In this research, Loading System Reaction Intensity (LSRI) was proposed as an indicator to identify stable and unstable failure. Secondly, unstable rock failure under true-triaxial unloading condition was simulated. A rock specimen was loaded in three directions; the lateral pressures (s3 and s2) were kept constant and the vertical stress (s1) was increased to a pre-defined stress. The specimen was suddenly unloaded in the minimum principal stress direction (s3) and loading in the s1 direction was continued until failure occurred. Different LSS values were considered and the results showed that the LSS influenced the failure mode; a soft loading system resulted in more violent failure and released more energy than that in a stiff loading system. The influence of specimen height to width ratio on rock failure was also investigated. It was found that failure in taller specimens was more violent than that in shorter specimens. Insights gained from the simulation are useful for better understanding of the influencing factors on the released kinetic energy during unstable rock failure and to find means to control rockburst damage in engineering practice."

Jan 1, 2015

By Guy Brouillard

A bow-tie analysis is a safety review methodology that uses a structured approach that can be qualitative or quantitative to document the potential risk of safety incidents. The bowtie diagram itself provides a powerful graphical representation of the threats barriers, events, and recovery measures which are readily understood by the "non-specialist". This presentation will discuss how mining operations can use this valuable tool within their operations to understand the risks and apply the appropriate safeguards toward reducing these risks to acceptable levels.

Jan 1, 2014

By S. Koppalkar

ABSTRACT: The development and evolution of the gravity recoverable gold (GRG) test procedure at McGill University is reviewed in this paper. Since the late 1980s, the research group led by the late Professor André Robert Laplante at McGill University has undertaken fundamental studies and applied research of the Knelson concentrator to develop a sustainable method of estimating GRG. Historically, a concept of “free gold” was used, and it was de?ned as the gold that could be separated and recovered from gold ore by amalgamation. Due to health and safety hazards, the practical use of amalgamation has declined. Around 1994, a methodology using a 3-in Knelson concentrator to measure gravity recoverable gold was established at McGill University. As a result of more than 10 years of improvement and optimization, this technique has become a standard method of evaluating GRG for gold ores, gold plant streams and platinum group metals. By 2006, about 200 GRG tests were carried out at McGill University on ores from all over the world. Recently, a modi?ed version of the GRG test (a simpli?ed test) was developed to provide a quick and rough estimate of the GRG in a sample; this simpli?ed test has the advantage of reduced mass, processing time and cost. To recognize and honour the contributions made by the late Professor Laplante towards the establishment of a standard test procedure for assessing gravity recovery potential, the authors propose that the GRG test be named after Laplante.

Jan 1, 2010

By François Charette

High stress conditions in weak rock masses lead to large deformation and breakdown of the rock material, while stress release events in hard rock mines can lead to sudden and usually violent rock failure. Typical support systems combine various reinforcement and support mechanisms to provide the required convergence control and retainment, but results are often mitigated by failure of surface liners, shotcrete and tendons. The paper reviews differing requirements of support and reinforcement for different failure types. In addition, the mechanical performance of a new reinforcing tendon is presented and analysed in view of the field requirements. Field tests results are presented.

May 1, 2011

By M. J. S. Innes

Abstract This paper is an account of an investigation made by the Dominion Observatory with a gravity meter and magnetometer over sulphide concentrations at East Sullivan, Val d'Or, Que., in June, 1947. The topographic relief over the area does not exceed 20 feet. The overburden varies from 0 co 50 feet. The west orebody had been outlined by extensive drilling. The average density contrast between the sulphide body and surrounding rocks is 0.5. Two hundred and sixty gravity and one hundred and ninety magnetic stations were observed. The results are shown on contour sketches. A derailed account is given of the methods employed to reduce the gravity observations. The survey shows that both gravimetric and magnetic methods are useful in delineating sulphide deposits under the conditions in which they occur at East Sullivan. The results indicate that the buried contact of the syenite intrusive southeast of the orebody could be traced with the gravimeter and chat the magnetometer was of little value for that purpose. Gravity anomalies due to the varying depths of overburden are negligible as compared to the magnitude of the total anomalies. Introduction The project was first suggested at a meeting of the Associate Committee on Geophysics of the National Research Council in September, 1946. At that time it was pointed out that the accuracy and speed of operation of the new gravity meters made them of special importance for geophysical prospecting and it was highly desirable to have an objective test of the performance of an instrument of this kind in delineating an orebody of known dimensions and density characteristics. Several years ago, a private company did some work with a gravimeter over the Amulet deposits, near Noranda. Unfortunately, the topography there is rather rugged, with hills and ravines exceeding 100 feet, so that the topographical effects rendered it impracticable to distinguish between anomalies due to the sulphides and those due to surface irregularities. An orebody of a typical nature, where the disturbing topographical corrections were not excessive, was therefore sought.

Jan 1, 1949

By R. Lanthier, A. Broussaud, J. C. Guillaneau, D. Hodouin

This study presents a method for upgrading the information extracted from the measurements given by the sensors of a pilot grinding circuit. For that purpose raw signals are combined to process models for extracting, through filters, the best information on the process state. Two different filters are used; one is based on steady-state mass balance constraints and the other one uses dynamic mass balance equations allowing for material accumulation in the equipment. The filters are designed and tuned with the help of a grinding circuit dynamic simulator and are then implemented in the pilot plant. Their performances and usefulness are discussed.

Jan 1, 1989