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By W. Curlook

"A review is presented of a growing number of imperatives, some self-imposed, some imposed by society, which the mining and metals industry faces in carrying out its business. These imperatives bear on all activities from the exploration phase, through engineering, design, plant construction and operation, to decommissioning.IntroductionThe mining and metals industry must learn to cope with, i.e. manage, a growing number of imperatives. Some of these, such as the need for responsible stewardship of natural resources, the requirement to respect laws and regulations, the need to provide for safe and healthy workplaces, and the need to provide appropriate returns to investors of capital , have been with the industry for a long time (fable I). But the industry now faces additional imperatives that are growing in number and in importance (fable 2):• There is the growing concern about the impact of operations, not only on the workplace environment and the external environment, but also on the need to monitor not only the chemical concentrations in various effluents but to also monitor the effects of such emissions on the environment; i.e. there is a growing concern about the ""net"" consequences of operations.• There is the need for on-going improvement in productivity and safety to compete and survive in a global economy. The global business environment has become paramount.• There is the imperative to failsafe all designs, equipment and operational procedures, and having done that to provide for containment of unavoidable spills, and to have ready and in place systems for emergency response.• There is the need, indeed the imperative, to involve all employees in various quality improvement programs.• There is the imperative to face up to ""virtual elimination/zero emissions""; and• One must have waste management plans in place to cope with the need to reduce, reuse, and recycle; and• There is the need for decommissioning plans for all operations, for the restoration of business habitats to their original states (or better). Indeed, one must engage in the decommissioning exercise from day one, i.e. right from the time of design and commissioning."

Jan 1, 1992

By S. A. Kenzap

Risk & Uncertainty ? Uncertainty about a situation can often indicate risk, which is the possibility of loss, damage, or any other undesirable event. Most people desire low risk, which would translate to a high probability of success, profit, or some form of gain. Risk = Likelihood x Consequence Risk is the possibility of loss, damage, or any other undesirable event.

Oct 1, 2010

Presentation Topics ? Low and Intermediate Level Waste ? Project Location and Site ? Geological Setting ? Key Features ? Project Overview ? Licensing and EIS ? Next Steps DGR Waste Package Inventory Approximately 50,000 packages over 35 years: ? ~40,000 packages or 80% of inventory are LLW Bins ? ~7,000 ILW Shields (concrete boxes) ? ~2,000 resin liner packages

Oct 1, 2010

By A. M. Girodo

"Dorbyl Heavy Engineering has been manufacturing winders since 1949 mostly for the South African mining industry.Table 1 shows that the vast majority of winders have been double drum winders. At the greater depths with larger ropes being employed, it became apparent that multi-rope winders would be needed. The high stress variation in Koepe winder ropes at great depths especially beyond 2000 m, ruled out this possibility. Thus the original concept was borne for the Blair multi-rope winder where the stress level variations in the rope would be as per the well known, tried and tested double drum winder. The Blair multi-rope was also devised to increase payload by using multiple ropes.With the increasing costs of transporting men and material coupled with fact that orebodies are getting deeper, various feasibility studies have been carried out by South African mining houses. For this reason Dorbyl Heavy Engineering has done conceptual design work of both double drum and Blair multi-rope winders with diameters up to 8.5 m dia (still well within our manufacturing capabilities). These feasibility studies have looked at depths approaching 4000 m*.This paper covers the typical duties leading to the choice of single drum, double drum, Koepe and Blair multi-rope hoists on South African gold mines. A brief synopsis of Dorbyl hoists in use in the South African mining industry, with some indications of future trends, will be discussed.With current installed depths of wind approaching 2500 m, the Blair multi-rope hoist has been used extensively for the heavier payloads.Some of the main considerations pertinent to the design of the Blair multi-rope hoist are illustrated together with the implications of using this type of hoist to winding depths of3000 m to 4000 m in the foreseeable future."

Jan 1, 1995

By J. Donovan

Underhand cut and fill mining is being planned for selected areas at the David Bell Mine where high ground stresses have resulted in particularly challenging mining conditions. In order to test the placement and performance of a variety of underhand cut and fill paste mats three different designs have been installed and extensively instrumented along the A-Zone 9C ore sill. The sill is approximately 87m long, 4.0m high, and 5.0m average width. The sill was broken into 3 sections each of which will contain one of the sill mat designs. The underhand sill will be mined 3.75mW x 4.0mH, allowing for some overbreak while minimizing the risk of the back span exceeding the design limit of 4.0mW. Each test sill mat includes pre and post-support and includes 0.5m (18?) broken muck mat placed along the sill floor. Upon developing beneath these mats quantitative and qualitative measures will be used to determine which design is the most suitable for application in underhand mining at David Bell.

May 1, 2007

By W. G. Q. Johnston, J. S. Fox

"A semi-continuous belt of Aphebian magnesian extrusive and related sub volcanic rocks has been delineated by the authors over a distance of 150 kilometres in the central La Ronge lithostructural domain in Saskatchewan. They range in composition from peridotite to basalt and attain true thicknesses of up to 800 metres. For the most part, they are confined to a basal position in the La Ronge/Wasekwan metavolcanic sequence, and appear to have been extruded onto sialic crust. However, at Lynn Lake, Manitoba, in the eastern continuation of the domain, similar rocks seem to be found only at a relatively high stratigraphic level.Although metamorphism seems to have obliterated any quench textures that may have existed in these rocks, ultramafic pyroclastics, pillows and amygdules as well as intercalated, fine-grained clastic sediment attest to the volcanic nature of these rocks. Bulk chemical analyses indicate that these rocks are heterogeneous, with komatiites, tholeiitic picrites and even rocks with some of the characteristics of boninite all being present. The close temporal and spatial relationship of ""boninites"" and komatiites in the belt may suggest a high degree of Aphebian mantle inhomogeneity in the domain.Nickel-copper mineralization has been found in differentiated tholeiitic stocks within the La Range domain (e.g., at Lynn Lake), but none has yet been found in the ultramafic volcanics. However, the tholeiitic picrites do host one economic gold deposit - the Agassiz Mine at Lynn Lake .Because of the depleted nature of their mantle source, the ""boninites"" of the domain are not considered to be likely hosts for mantle-derived nickel sulphide mineralization. However, the opposite is true of the komatiites, and this points to the need for whole-rock geochemistry in setting priorities for nickel exploration in the belt. In contrast, all of the magnesian rocks of the domain probably have the same gold potential. Inasmuch as the geophysical response to gold mineralization in the domain is likely to be unpredictable, lake-sediment geochemistry, followed by base-of-till and/or alteration oriented lithogeochemistry, should be emphasized during gold exploration."

Jan 1, 1981

By Victor Maksaev, Marcos Zentilli

"Abstract - The Domeyko Cordillera, the westernmost uplifted crustal block of the composite High Andes of northern Chile (20°S to 28°S) hosts a narrow N-S trending belt of Late Eocene-Oligocene giant porphyry copper deposits, which include Collahuasi, Chuquicamata, El Abra, La Escondida, and El Salvador. These deposits are spatially and genetically associated with the closing igneous activity along this range, prior to a 30 km eastward jump of the magmatic front in response to tectonic plate interaction. The porphyry copper deposits are also spatially associated with a major intraarc strike-slip shear system, the Domeyko Fault System. Although the tectonic uplift of the 3000 m to 5000 m high range has generally been assumed to be mostly Miocene in age, field relationships suggest that the Domeyko Fault System and tectonic uplift were active as early as the Eocene, coinciding with porphyry copper emplacement between 41 Ma and 30 Ma. Apatite fission track (FT) thermochronology provides both age data and a time-temperature history for rocks since they cooled below a temperature of ca. 125°C (equivalent to a depth of 4 km to 5 km under normal geothermal gradients) on their way to the surface during exhumation, or after a heating event. Apatite FT data from the Paleozoic crystalline basement of the Domeyko Cordillera indicate that at least 4 km to 5 km of rocks were eroded during exhumation of this tectonic block between ca. 50 Ma to 30 Ma (Middle Eocene to Early Oligocene), a time that immediately precedes and overlaps with the emplacement of giant porphyry copper deposits. The FT data constrain the age and duration of a period of crustal thickening and extensive erosion known as the Incaic compression, an event recognized in the Andes of Chile and Peru. Assuming that cooling was due to denudation alone, modelling of the FT data allow estimation of denudation rates between 200 and 100 m/My during this period. In contrast, exposures of pre-porphyry Paleocene intrusives on the western edge of the Domeyko Cordillera reveal apatite FT ages that are concordant with biotite 40Ar-39Ar dates, indicating shallow emplacement, fast cooling and negligible exhumation. The apatite FT ages of the Chuquicamata and El Abra porphyry copper deposits are only marginally younger than their 40Ar-39Ar dates, implying fast cooling/exhumation of shallow mineralizing systems (ca. 2 km to 3 km). Their FT time-temperature history is compatible with extremely low rates of exhumation (ca. 50 m/My) since about 30 Ma (Early Oligocene). This limited extent of erosion, due to exceptional aridity, has greatly contributed to the preservation of rich supergene enriched blankets above some of the porphyry copper deposits.A model is proposed, which is consistent with field relationships, geochemical, and geochronological data. High relative velocities and intermediate-angle oblique convergence between the Nazca and South American plates in the Eocene-Early Oligocene led to intra-arc transpression partitioned into reverse faults of opposing vergence and a right-lateral shear system (the Domeyko Shear System) localized along the magmatic front. Crustal shortening and thickening led to uplift within the Domeyko Fault System and to erosion of at least 4 km to 5 km. Crustal thickening deepened the zone of magma generation, and magmas accumulated in the lower crust, allowing small volumes to rise rapidly to shallow levels along transtensional domains of the regional shear system. A similar model of crustal thickening and shortening before and during porphyry copper emplacement in zones of transtension may also apply to the Miocene-Pliocene giant porphyry copper province of central Chile."

Jan 1, 1999

By K. D. Eng, W. T. Tierney

"During the past century, the development of vehicular transportation has benefitted tremendously from the performance improvement in engines in a situation where low-cost, plentiful fuel supplies were the order of the day. Engine advances were enhanced by and also dictated fuel modification to better adapt the energy source to the power plant.In discussing the several aspects of the change in approach from ""an engine and its fuel to a fuel and its engine"", the authors touch on the following areas:1. Description of an engine concept that provides the needed flexibility in fuel appetite at good efficiency to cope with future requirement s.2. The constraints placed on liquid fuel resource energy utilization efficiency by special engine-required fuel properties and the fuel efficiency of the various engine types available.3. Future vehicle engine fuel sources. This review will put into perspective the problem associated with the net energy available from future fuel sources under extensive research and development at present.4. A brief review of test data to show that fuel-tolerant and fuel-efficient engines are viable and that, in a fuel-resource-limited future, they can be a ""light at the end of the tunnel.""The Texaco Controlled Combustion System (TCCS)The TCCS is a unique means for stratified charge operation of an internal combustion engine in such a manner as to eliminate the requirement for octane or cetane number specification for the fuel. Octane rating is an empirical engine test method that evaluates a gasoline's resistance to spontaneous ignition or ""knock."" Cetane is based on a different engine test, which determines a diesel fuel's ease of spontaneous ignition . High cetane number enhances cold starting and permits high-speed diesel engine operation. As one would expect, the fuels in current use cover a band when the two values, octane and cetane, are plotted against each other."

Jan 1, 1982

By L. Gasser, N. Bellinger, H. Awatta, A. Merati

As aircraft age, the extent of interactions between fatigue and other damage mechanisms, such as corrosion and fretting, increases. At present, however, there is no generally accepted methodology within the Aircraft Structural Integrity Program (ASIP) framework to account for the effects of these interactions on life and the residual strength of aging aircraft components. A comprehensive program is being carried out by the National Research Council Canada in collaboration with Analytical Processes/Engineered Solutions, using the Holistic Structural Integrity Process (HOLSIP) to address time and cyclic load issues. This approach predicts the evolution of a discontinuity state in a material from production to retirement. This paper summarizes the results of a study on the 2024-T3 aluminium alloy in different forms (clad and unclad), thickness, and specimen geometry. This study consisted of identifying the microstructural features associated with crack nucleation sites and relating them to the testing parameters and fatigue life. Several coupons were fabricated and fatigue-tested. The fracture surfaces were carefully examined, and the physical characteristics of the microstructural features found near the crack nucleation sites were analyzed. Effect of stress level, loading direction, coupon geometry and surface condition on the number of crack nucleation sites, and fracture origin size has been discussed. Four distinctive mechanisms were found to be responsible for crack nucleation: for unclad materials constituent particles, oxide residue, surface irregularities and for clad samples the clad layer was the sole fracture origin.

Jan 1, 2006

By Robert B. Parsons

"A joint federal/provincial/industry subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWG) has published an informative and readable report on taxation matters concerning Canada's mining industry. The report, which was presented to the federal and provincial mines ministers in September 1986, identifies and discusses key tax issues relating to this industry. The report is mandatory reading for anybody with an interest in mineral exploration or production in Canada.IntroductionIn 1986, Canada's federal and provincial mines ministers were presented with an important report concerning the taxation of this country's mining industry. This document is important for a number of reasons, two of the reasons being: first, the report contains an objective analysis of the key mineral taxation issues of the day; and, second, the report is the product of a cooperative exercise involving representatives of various facets of the industry and government. The report should be regarded as compulsory reading for anybody who has an interest in fiscal matters affecting mineral exploration and production.The ""Report on Fiscal Proposals"" was prepared by a subcommittee of the Intergovernmental Working Group on the Mineral Industry (IOWO). IOWO is a group of senior federal, provincial, and territorial government officials concerned with the analysis of mineral policy issues in Canada."

Jan 1, 1986

By Lawrence Devon Smith

"The concept of risk is well established in the mining industry. It is acknowledged when estimates of reserves are expressed as proven or probable, when mining and metallurgical recoveries are applied to the ore, and when contingencies are added to costs. However, it is difficult to provide a quantitative assessment of risk. The significant sources of risk in a mineral project and how these are addressed in project evaluations are discussed.The discount rate is examined as a fundamental means of reflecting risk in discounted cash flow evaluations. Current industry practice is discussed, and a methodology for the analysis of risk levels is proposed that assesses the constituent components of the discount rate: real interest, mineral project risks, and country risk.IntroductionThis paper examines the components of the discounted cash flow discount rate and proposes a method of estimating project-specific discount rates. The motivation for this work comes from experience of project evaluations in which owners and purchasers had agreed on virtually every aspect of the evaluation except how much the project was worth. Agreement was reached on reserves, grade, recovery, capital costs, operating costs, taxes, and, by combining these components, even on the final cash flow values. The only difference in opinion concerned the discount rate to be used in the calculation of the net present value. Depending on the life of the project, such differences of opinion can cause a variation of more than 50% in the value placed on a project! This is illustrated in Figure I."

Jan 1, 1995

By Sukumar Bandopadhyay, Arunapuram Sundararajan

"For the last three decades, the application of network planning has provided a basis for a formal and general approach to the discipline of project management. For fixed activity duration, a very simple algorithm commonly known as critical path method (CPM), gives the length of time required for the total project as well as indicates the activities which are vital to the completion of a project. Project Evaluation Review Techniques (PER T) on the other hand, generalize the above approach to recognize uncertainty in the activity durations by allowing them to be random variables. One of the misleading aspects of current "" PER T"" solution method is, however, the implication that there is a unique critical path. In general, any number of paths could be critical, depending on the particular realization of the random activity durations that actually occur. In this case, simulation can be utilized to estimate completion time of a project.In this paper, the concept of criticality indexing is discussed, and a simulation model application which defines the critical path based on the criticality indexing concept, to a longwall development - extraction network, is presented. The model also provides suitable scheduling of resources based on the resource constraints and smooth s out period-t o-period assignments. IntroductionThe successful management of large-scale projects require careful planning, scheduling , and coordinating numerous interrelated activities. To aid in these task s, formal procedures based on the networks and network techniques (variously called PERT or CPM) were developed. In its original form the completion time for individual activities of a project was assumed fixed and known in advance: this in turn led to the familiar algorithms for computing the critical path, earliest start time, slack, and so forth. The unreality of such an assumption is, of course , apparent in many contexts. Consequently, attempts were made to introduce probalistic activity completion times, allowing representation of the stochastic nature of most projects."

Jan 1, 1987

By R. B. Stein

"Countercurrent decantation circuits(CCD) are often employed in hydrometallurgy to effect solids-liquid separation in combination with a barren solution wash to reduce losses of valuable solution component(s) from the tails. Bechtel Corporation uses its BEMSIM flowsheet-modelling PC computer program to simulate a CCD circuit where the ""dirty"" wash solution contains significant amounts of soluble components. An algorithm successfully models this condition and is simplified to a single expression when the wash solution is a ""clean"" solution containing no solubles. The CCD calculation module is compared to operating data from uranium and nickel-cobalt CCD circuits.IntroductionHydrometallurgical process schemes have often relied on countercurrent washing methods to reduce soluble losses of valuable product in the tails. Commonly used equipment to effect this operation is a CCD circuit of N thickeners in series, where a slurry is fed to thickener I and a wash solution to thickener N; clear pregnant solution overflows thickener I and washed tails exit as underflow from thickener N. CCD circuits of this type are typically employed when the solids tend to slime heavily and where a filter is not economic.A typical CCD circuit usually employs from two to five thickeners and can employ either a ""clean"" washing solution of, say, pure water or else the hydrometallurgical circuit may generate a ""dirty"" barren solution containing an appreciable amount of soluble component which may be advantageously returned to the process as CCD wash solution. Various authors have treated the case for clean washing solutions (Svarkovsky 1977, Merritt 1970). For the case of dirty wash solutions, an algorithm has been developed to enable efficient modelling by the BEMSIM computer program, because the need for an accurate method to calculate soluble losses is required when performing an economic trade-off analysis of the value of product lost in the tails as a function of the number of thickeners."

Jan 1, 1990

By P. Karimi, A. Amini, H. Abdollahi, A. Mirzaeian

Due to detrimental effects of cyanidation process on the environment in gold industry, application of cyanide alternatives such as thiourea are being highly considered in recent projects. In this study, the extraction of gold from poly metal ore, using thiourea was precisely investigated. The representative sample contained 2.5 ppm Au and 160 ppm Ag. The sample was categorized as oxide gold ore, because the main part of its pyrite was changed to iron oxide and hydroxide such as goethite and lepidocrosite. According to mineralogy, the main gangue mineral was quartz. It shows that gold grains are free and interlocked with quartz matrix. Also, the presence of a high amount of silver in free and sulfide forms and also the low content of other sulfide minerals such as base metal sulfides is a remarkable point of these studies. In the gold extraction process with thiourea, there are several parameters that affect the rate of gold dissolution such as concentrations of thiourea as a gold lixiviant and ferric sulfate as an oxidant, pH and size fraction of feed and leaching time. The influence of these parameters on the gold dissolution rate were investigated and optimized. The results showed that the concentration of thiourea is the most influential parameter which could increase the gold recovery to 71% (at 10 g/kg sample). The optimal amount of ferric sulfate was determined as 6 g/kg sample. Also, the optimal levels of size fraction of feed and pH of solution were 88% under 75 micron and 2 as acidity; respectively. Leaching time was 6 hrs. In addition, this sample was leached with cyanide and the optimized values of size fraction of d88=75 microns, pH=10.45, 2500 ppm of sodium cyanide with time leaching of 24 hours were concluded for maximum recovery of gold in solution. Finally, the results of cyanidation tests were compared to the thiourea dissolution after optimizing all affected parameters in cyanidation process.

Jan 1, 2016

By P. D. Duever, P. J. Readyhough, P. L. Silveston

"The Plastojrost apparatus, developed by Ritter and Juranek in the 1960s has been modified primarily, to automatic temperature control. A limited investigation of carboniferous and cretaceous coal samples showed that both coals undergo the same changes when coked in the Plastofrost unit. Dilatometer plastic range and total dilatation correlated well with the Piastofrost plastic range for the carboniferous Appalachian coal, but not for the cretaceous western Canadian coal. Work to elucidate the characteristics of some western Canadian coals using the Plastofrost is in progress. IntroductionCoke quality is critically affected by the properties of the plastic phase in the coal-to-coke transformation. Since these properties exist in a coke oven and are not measurable, they are approximated by standard laboratory tests, such as free swelling index, plastometry, and dilatometry. Of particular interest to us is the anomalous behaviour of western Canadian coals of cretaceous origin. By many predictive methods, these coals should not produce coherent cokes. When coked in pilot scale test ovens, in fact, they produce cokes of good stability. They typically make up 20% of Japanese coking coal blends and are also used in South Korea, Mexico, Brazil, and several European countries. This anomalous behaviour has been studied in our laboratory<8.9.1O). Plastic properties or rheological tests examine just the external ramifications of the coal-to-coke transformation. To understand the process, however, microscopic examination of the coal and coke seems to be needed. The Plastofrost unit has been shown to be a convenient means to this end."

Jan 1, 1987

By Mark Liskowich

When is it the proper time to initiate engagement with various stakeholders, including Indigenous communities? This paper will demonstrate what stage of a project’s evolution is the appropriate time to initiate a stakeholder engagement plan. It will look at aspects to consider when identifying the communities to involve. It will describe the contents of a Stakeholder Engagement Management Plan as well and touch on how tried and true options analyses, such as a Multiple Accounts Analysis can be used to inform the results of the engagement, guide the development of your project and clearly document the engagement process. It will illustrate the benefits of initiating engagement at the appropriate point in your project’s schedule, and the limitations of doing so too early and at later stages of the project engineering. The benefits of this approach can be realized within any legislative Jurisdiction including the Canadian Environmental Assessment Act 2012 and Canada’s new Impact Assessment Act.

Jan 1, 2020

By P. K. Kaiser

3-D virtual reality (VR) visualization has opened new opportunities for complex 3D (x, y, z), 4D (x, y, z, t) or even nD data interpretation. The integration of common earth models (3D geologic data), mine models (3D excavations and stress), extraction models (1D time sequencing or mine sequencing) and nD monitoring data (e.g., seismic event parameters) into a common mining process model provides a platform for experts in various fields to better design, evaluate, monitor and modify mine plans throughout a mine?s life; from feasibility, through operation, to closure. Viewing seismic data in a stereoscopic VR environment within a mining process model offers data interpretation processes previously unavailable at lower dimensionality. MIRARCO has developed data analysis and viewing processes specifically designed to enhance microseismic and seismic data interpretation in a collaborative, immersive VR environment; bringing mine personnel and expert consultants together to evaluate data and make strategic decisions for cost effective and safe mining. Seismic events cause immediate hazards (rockbursts) and microseismicity causes gradual hazards through its cumulative effect in rockmass degradation. The focus of this paper is on understanding seismicity from a mine safety and mine planning perspective; in particular, how seismic migration patterns relate to the rockmass response to mining. The benefits of innovation in seismic data interpretation are significant, e.g., for hazardous work area identification, allowing better formulation of re-entry policies and workforce allocation planning, as well as allocation of effective support systems to strategic areas of elevated risk. Better understanding of the overall response of a mine to extraction also facilitates mine planning and design, assisting in reducing production costs and thus in enhancing profitability.

Apr 1, 2005

By A. C. Headon, K. W. Lam, D. P. Dautovich

"Microbiological activities affecting the performance of materials have been encountered in diverse situations within Ontario Hydro. Case histories of bacterial problems which are presented include ground rod corrosion at transformer stations, corrosion of a bare steel cooling water intake structure in Lake Huron and corrosion of steel components in a nuclear generation station vacuum building. Possible microbiological activities which may affect the corrosion behaviour of containers for the disposal of nuclear fuel waste in the future are discussed, as are bacterial actions suspected of causing an odour problem in residential water heaters.IntroductionBacteria are ubiquitous. Except by use of sterilization methods, bacteria -free environments are no t possible to find. Bacteria lie dormant in hostile environments, spread easily through air and water currents and reproduce rapidly under favourable conditions. Although different types of bacteria have different preferable conditions for growth, they are highly adaptive and in general, whenever there is a source of water and carbon (carbon dioxide or organic matter), there will be bacterial activities . These activities often induce or enhance costly metallic corrosion in industries and water odour problems in rural water supplies . Underground structures and systems in contact with natural water or water containing organic matter are most susceptible to bacterial attack.The types of metal-degrading bacteria , their characteristics and the conditions for growth have been reviewed extensively in the literature(1,2,3). There are several often encountered groups of bacteria which, through their metabolic processes, may lead to the degradation of metals. A large variety of bacteria produce corrosive in organic or organic acids as waste, such as the well known formation of sulphuric ac id by aerobic sulphur oxidizers . Anaerobic sulphate reducers produce hydrogen sulphide which is corrosive and has an obnoxious smell, slime-forming bacteria from slime which shelters sulphate reducers and iron bacteria oxidize ferrous to ferric ion which precipitates as hydrated oxides creating oxygen concentration cells . The following are bacterial problems encountered in Ontario Hydro. Although the number of recognized cases has been few, they show the diversity of location and environment where bacterial problems could arise. These include ground rod corrosion at transformer stations, corrosion of bare steel in a water intake structure, corrosion of steel in a nuclear generation station vacuum building and an odour problem in residential hot water tanks. In addition, possible bacterial- enhanced corrosion in containers for future disposal of nuclear fuel wastes are also discussed."

Jan 1, 1984

By W. G. Robinson

"MINING is one of Canada's most important industries and exploration is the life-blood of this dynamic and exciting business. The health and growth of the mining industry of tomorrow depends on the effort and thought that go into exploration today. The Members of the Geology Division of the C.I.M. are directly concerned with exploration, and it is fitting that this Division should periodically sponsor reviews of the thoughts and practices of the exploration com-munity. Accordingly, we have invited seven leading authorities to contribute papers dealing with specialized aspects of this field.Exploration is a science, or art if you will, that is constantly changing in keeping with our expanding knowledge of geology and technology. It started with the old-time prospectors who searched the wilds for exposures of ore, and made finds that developed into some of our most important mining camps. As more discoveries were made, they were able to relate certain types of deposits with particular geological conditions, laying the foundation for modern concepts of economic geology. The mapping by the early field parties lacked detail and usually served to outline the ""greenstone"" areas considered favourable for prospecting. More de-tailed studies through the years by government and company geologists led to new thoughts on the origin, emplacement and geological control of orebodies. The continuing diversity of opinion on these subjects indicates a need for further research, but each year sees an increase in our reserves of factual information."

Jan 1, 1967

By Arnold R. Pasieka, George V. Sotirow

"The object of this paper is to outline a computerized net cash flow approach for practical cutoff grade determinations. A cutoff grade carries not only geological but also economic value, in which costs are balanced against revenues. For different situations, cutoff grades are a &apos;standard of value&apos; that are determined for the purpose of classifying economic or uneconomic mineral reserves in a specified time frame. In a constantly changing technical and economic environment, the decision to develop or maintain a mining operation at its best economic potential, requires an appropriate cutoff grade strategy, a strategy consistent with short- and long-term operational and corporate objectives and one based on realistic marketing and metal prices forecasts. The use of a project evaluation computer program, in combination with specific corporate net cash flow requirements, shows the most promising and flexible team approach for cutoff grade optimization.IntroductionThe recent recession has had a devastating effect on the Canadian mining industry. Exploration and mining R&D expenditures have been critically reduced and now are believed to be below healthy levels. Ore reserves, mine life and cutoff grades are careening in several directions because of low base metal prices, relatively high costs and sensitive precious metal prices.These conditions demand an improved understanding of the terms ""ore"" and ""cutoff grades"" as they are applied to the planning process and day-to-day operations. ""Ore"" or &apos;ore reserves"" is a dynamic concept, reflecting a cumulative effect of changes in geological, technical and economic conditions in terms of material which can be mined at a potential profit. By contrast, if economics are not the primary consideration, the term ""mineral reserve"" or ""mineral inventory"" should be used to describe the mineral deposit. For different situations, cutoff grade is ""a standard of value"" determined for the purpose of classifying mineral reserves as economic or uneconomic in a specified time frame. The question of mining at average reserve grade or low-grade material during high metal prices is of paramount importance for cutoff grade strategy."

Jan 1, 1985