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By E. R. Lea

The B. M. & S. orebodies, consisting of the No. 6 (Brunswick) and the No. 12 (Anacn Leadridgz, have the distinction of being the first major 1base metal ore deposits to be found in the Province of New Brunswick. They are massive sulphide de-posits consisting of pyrite (pre-dominantly) and base metal sulphides, and they carry values in lead, zinc, copper, and silver. These orebodies are localized within favourable drag fold structures believed to be related in their origin to external forces set up in the area subsequent to the primary regional folding. Both orebodies are characterized by the presence of magnetite 'iron formation' which, in certain 'Portions of each orebody, may be found as relics within the massive sulphides. Studies show the magnetite to be the first metallic mineral within the ore ?zones, followed by pyrite, Sphalerite, galena, and finally chakopyrite. The shape of these massive pyritk orebod:es as well as the distribution of values within them is controlled to a large degree by the ore-ore drag fold structures. A possible relationship is discussed between the basic intrusives in the area ?and the magnetite deposits. It is suggested that a large portion of ?the iron content of the massive suplhedes has been derived from the earlier magnetite. Intermittent movements in the area during the sulphide mineralization are believed to belong to the last stages of deformation in the area. These late movements may have been caused by the intrusion of the granite into the area. The granite may have a genetic relationship to the B. M. & S. orebodies.

Jan 1, 1958

The cost benefits of controlling dilution of extracted ore have been very well understood by miners and mining professionals for many years. However, as we strive towards more mechanization, the dilution factor has been compromised in order to fit ?equipment? that is better suited to provide improved safety and productivity. Alternately, the drilling and ground support is accomplished by handheld drilling. In 2007, a short study, commissioned by CAMIRO (Canadian Mining Industry Research Organization) on the safety of hand held drilling vs. mechanized drilling, concluded that the risk of injury with handheld drills was seven times greater than with mechanized drills. Armed with this data, MEDATech Engineering proposed to the CAMIRO group to fund development of a ?MICRO Bolter?.

May 1, 2009

By L. R. Bower

"This paper describes a highly versatile variable speed unit with a torque multiplication feature as a direct replacement for a fluid coupling .The unit is comprised of a modulating clutch with torque converter and lock-up options.The UCD does not start or stop the motor. This is carried out in the normal manner.The UCD continually monitors and rapidly regulates the output speed to the requirement of a set point demand from input signals or a pre-set program with full manual override.The pre-set program can include start and stop ramps, top speed and minimum speed regulation and also mid-speed set point with security for man-riding, etc. Speed variation is from zero to 100% on a constant duty basis.The input signals can be from any source, e.g. belt weigher. load profile bunker probes, mine monitoring system, etc.The UCD when fitted with a torque converter has a torque multiplication feature which automatically provides a starting torque up to two and a half times greater than the full load torque without exceeding the normal motor power levels.IntroductionIt is common practice in the mining industry to drive conveyors, whether they be belt or chain, through a transmission system incorporating a fluid coupling between the driving motor and gear-box .However, there are drawbacks and in an effort to attain a better degree of drive and control, two-speed motors - inverters cycle- converters - hydrostatic drives, etc ., have been introduced."

Jan 1, 1986

By Noel Brien, O&apos

General: National Asbestos Mines Limited has operated an asbestos mine and mill near Thetford Mines, Quebec, since 1958. As a result of additional exploration of the orebody in 1962-63, it became apparent that long-range mining plans would have to be revised to allow for a large increase in both ore and waste tonnages. It was decided that the task of checking out possible mine designs could best be analyzed by a computer to obtain data from which an optimum open-pit configuration could be plotted. Object: It was desired to arrive at an optimum open-pit configuration with an over-all pit slope of 45 degrees and a minimum operational width of 200 ft. at the bottom. Calculations were based on assay values from diamond drill holes in cross sections of the mine. The computer's assignment was to select and describe, by coordinates, the optimum cross section for the mine. Mine engineers then assembled the various optimum sections to produce the pit outline. As this would not necessarily result in a practical mining arrangement, the computer also provided alternate solutions,

Jan 1, 1965

By R. H. Sheaphim

THE RECENT and continuing activity in the Boundary district, British Columbia, makes the publication of this paper timely. The following description and discussions are based on two years' experience in the district as Field Manager and Geologist for Attwood Copper Mines, Limited. The Attwood project was organized by Dr. D. F. Kidd to re-examine the Boundary mining camp. Thanks are due to Dr. Kidd, both for his intelligent guidance during the project and for his permission to publish this paper. Much of the data and many of the interpretations presented are credited to the work of, and to discussion with, Dr. W. H. White, Consultant Geologist, who worked for two field seasons on the project. However, the author assumes the responsibility for this presentation. Dr. C. D. A. Dahlstrom worked with the author during the latter stages of the project. His assistance and advice are gratefully acknowledged.

Jan 1, 1956

By M. L. Wacker

"Cigar Lake high-grade uranium mine in Saskatchewan is operating after 25 years of test mining, construction, and mine flood remediation. Factors include ground stability, groundwater control, radiation exposure, and ore handling. A 10 year test program resulted in validating “jet boring”, a non-entry mining method involving artificially freezing the orebody and surrounding rock; tunnelling to develop access crosscuts below the orebody; installing cased pilot holes through ore; extracting ore using rotating high-pressure water jets within pilot holes; and cavity concrete backfilling. Ore slurry is prepared underground, pumped to surface, and trucked to McClean Lake mill for processing to uranium concentrate.RÉSUMÉ Après 25 années d’essais sur les méthodes minières, de construction et d’assainissement suivant les inondations à la mine, l’exploitation de minerai à haute teneur en uranium Cigar Lake, localisée dans la province de la Saskatchewan, est opérationnelle. Les principales difficultés concernent la stabilité du terrain, le contrôle des eaux souterraines, l’exposition aux rayonnements et la manutention du minerai. Un programme d’essai de 10 ans a abouti à la validation du « forage à érosion », une méthode minière qui consiste à congeler artificiellement le corps minéralisé et les roches environnantes ; à creuser des tunnels pour développer des travers-bancs d’accès en dessous du corps minéralisé ; à installer des puits de fondation pilotes à travers le minerai ; à extraire le minerai à l’aide de jets d’eau à haute pression dans les puits pilotes ; et à remblayer les cavités avec du béton. La boue de minerai est préparée sous terre, pompée vers la surface puis transportée par camion jusqu’à l’usine de concentration de McClean Lake pour le traitement afin d’obtenir du concentré d’uranium.INTRODUCTIONThe Cigar Lake deposit is in northern Saskatchewan, 660 km north of Saskatoon, Saskatchewan, Canada, at the east edge of the Athabasca basin (Figure 1; Bishop, Mainville, & Yesnik, 2016). The operation is jointly owned by Cameco Corporation, AREVA Resources Canada Inc., Idemitsu Canada Resources Ltd., and TEPCO Resources Inc. Cameco has been the operator of Cigar Lake since January 2002. The discovery hole was drilled in 1981. Commercial production was declared in May 2015 and the Phase 1 operation will have a mine life of 15 years."

Jan 1, 2017

By Nessetech Consulting, L. A. Cisternas, E. D. Galvez, S. H. Kuan, L. H. Saw

"In Malaysia, there were two rare earths processing plants namely Asian Rare Earth (ARE) and the Malaysian Rare Earth Corporation Plant (MAREC) in Perak, which were operated until 1992 and were subsequently closed due to problems pertaining to disposal of large amount of radioactive waste. Recently, Lynas Advanced Materials Plant (LAMP) has become one of the largest rare earths processing plant in the world producing rare earth elements (REE) in Gebeng, Pahang. The primary raw material is lanthanide concentrate (LC) which is imported from Mount Weld mine in Australia and shipped to Malaysia. LC is produced from lanthanide ore after mining and mineral processing. The ore has a lower impact than Bayan Obo, Mountain Pass and adsorbed clay deposits, given the small footprint of the mine itself and the remoteness of the location. The type of ore being mined (rare earth phosphates: carbonatite, monazite) may have higher thorium content than bastnasite ore from the Chinese or American mines but still far below radiation concerns. This paper was written to review the processing flowsheet at the Lynas Advanced Materials Plant (LAMP), the environmental impact associated with the processing of the said ores and the sustainability of the operation.INTRODUCTIONRare earth minerals are one of a set of 17 minerals or chemical elements which consists of yttrium and scandium, as well as the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Despite their importance, rare earth minerals rarely exist in economically viable concentrations and they are usually difficult to extract. Rare-earth minerals create strong magnets when added to magnetic elements such as iron, and are useful for the production of electronics systems as well as electric cars. They are also used extensively in automotive catalytic converters, fluid cracking catalysts in petroleum refining, wind turbines, phosphors in colour televisions and flat panel screens, displays for mobile phones and laptops, rechargeable batteries, and various medical devices. The elements are typically split into two subgroups: the cerium sub-group of ‘‘Light’’ rare earth elements (LREEs) which includes La to Eu and the yttrium sub-group of ‘‘Heavy’’ rare earth elements (HREEs) which include the remaining lanthanide elements, Gd to Lu, including yttrium (Gupta and Krishnamurthy, 1992; Jordens et al., 2013; Trifonov, 1963). Scandium, however, when it is classified as a rare earth element, is not included in either the LREE or HREE classifications (Gupta and Krishnamurthy, 1992; Jordens et al, 2013). Half of the world’s 110 million tons of reserves exist in China while other sizable deposits are found in Russia, United States, Brazil, India, Australia, Canada, and Greenland. The countries known to be actively mining REE are China, Russia, India, Brazil and Malaysia (Hao et al., 2015). Among these countries, China has the largest REE production, accounting for more than 93% of global supply (Yap, 2015). The critical metal report (Moss et al. 2011) listed 14 economically vital raw materials that are prone to supply disruption and concluded that supply disruption would threaten the goal for cleaner transport and sustainable energy since rare earth metals are used in products using green technology, such as hybrid/electric vehicles, carbon capture systems, wind power generation, low-energy lighting, and energy efficient flat-screen displays."

Jan 1, 2016

"IntroductionIn the 1970s, environmental concerns and associated liabilities were a new and unknown aspect of corporate risk. Today, social concerns and the associated conflicts that they can generate constitute a rapidly expanding aspect of risk. Although not a new phenomena — the Bougainville copper mine was forced into closure in 1988 — social risk has emerged as considerably more important, and increasingly visible, in the last few years. Social risk is now an aspect of all mining activities which needs to be calculated into project assessments, and to be managed throughout the life of a project. While social risk has a number of aspects at the corporate level, such as company image and shareholder relations, at the level of the individual project, its primary component is social acceptability, and the principal tool for managing it is the Social Licence to Operate.Social Risk in Latin AmericaThroughout Latin America there are newly modernized mineral codes and economic systems introduced over the last ten years which, together with new environmental legislation, look very much like regulations in developed countries. To the corporations, the existence of these instruments means that the risks from the environmental issues associated with the project are known; they are legislated, defined, quantifiable and hence manageable.It seems ironic that, just when comprehensive regulations for the environmental management of mining have been put in place throughout Latin America, there arise an increasing number of challenges to mining activities. For, in spite of the apparent guarantees provided by these new legislative reforms, communities in Latin America today are more frequently standing up and taking exception to the presence of mining companies, or the ways in which the companies are conducting themselves. The viability of projects becomes threatened because they are considered socially unacceptable, a phenomenon that we describe as social risk. These challenges are less about opposing mining activities than many people would think. Rather, they are based on an increasing desire on the part of the local population to have some measure of control over their own future, and to participate in the development process from the earliest stages."

Jan 1, 2000

By Y. Kashiwaya, J. Yagi, P. R. Austin

The problems of global environment and resources have become important issues in recent years, and the iron and steelmaking industry is requested to decrease energy consumption and carbon dioxide emission. The improvement of efficiency of ironmaking system is one of the countermeasures for these problems because more than a half of total energy input to the integrated steelwork is input to the ironmaking system. Various approaches to improve the blast furnace process have been made. The authors examined their performances through mathematical simulations of blast furnace operation, and confirmed the improvement of blast furnace efficiency under some operating conditions. The ironmaking system consists of various processes, and the materials and the energy are transported among these processes. Thus it is necessary to evaluate the efficiency of the novel operation of blast furnace based on the ironmaking system. In this study, the balances of material and energy on ironmaking system that consists of blast furnace, coke oven, sintering and hot stove processes were analyzed. The operation status of each process in the system was adjusted according to the results of the operation simulation of the blast furnace under novel operating conditions. The analysis clarified the effect of the blast furnace operation on the energy balance and CO2 emission of the ironmaking system.

Jan 1, 2015

By J. L. Wilson

"Many modern concentrators with VSD driven SAG mills still rely on the control room operator to manually adjust the speed in reaction to increasing bearing pressure. All too often, the problem with this strategy is by the time the operator reacts with a sudden speed increase, the SAG Mill is likely already on its way to loading up. To assist the new operators, the SAG Mill at B2Gold’s Fekola Mine in Mali needed a robust control that could handle load changes and unmeasured disturbances with minimal operator intervention. With modern Distributed Control Systems (DCS) powerful enough to run advanced control, they often have Model Predictive Control (MPC) blocks built in or available as an “add-on” license, and thus MPC can be readily implemented within the modern concentrator with a relatively low added capital cost. This paper discusses an implementation of two single output MPC controllers to control the SAG Mill at Fekola. This was implemented using the existing signals and advanced control blocks available to the installed DCS.INTRODUCTION Many modern concentrators with VSD driven SAG mills still rely on the control room operator to manually adjust the speed in reaction to increasing bearing pressure. All too often, the problem with this strategy is that by the time the operator reacts with a sudden speed increase, the SAG Mill is likely already on its way to loading up. The next step the operator may take may be to cut back the feed rate, or production until the SAG is once again stable. With this sudden reaction comes an abrupt change in SAG rotational speed and power consumption that sends a surge of material down the circuit as the mill suddenly ejects more pulp. Furthermore, choosing a higher rotational speed can lead to higher than normal liner wear as the cataract overshoots the toe of the charge and impacts the liners. After start-up at B2Gold’s Fekola Gold Mine in 2017, the SAG mill was being controlled manually. The SAG rotational speed was adjusted manually by the operator in step changes depending on whether the SAG bearing pressure was increasing, decreasing or stable. During this time of manual control, the SAG fresh feed rate was also adjusted to a tonnage setpoint with a PID controller. Generally, the SAG fresh feed rate setpoint was kept at a target value, but then the feed rate was throttled back if the SAG mill or grinding circuit showed signs of overloading. The extra challenges were that the operators had limited experience and were concurrently learning how the plant operated. Also, they were also occupied with managing situations in the rest of the plant. Often their attention was drawn away from the SAG mill and during that time, the SAG Mill would load up before they could react."

Jan 1, 2019

By B. J. Keating

"AT PRESENT, it is not certain that any of the sulphide de in the Province of Nova Scotia attain the lower grade limit of 60 per cent sulphides over the minimum area of 1,000 square feet suggested as cut-off specifications for inclusion in this Symposium. However, several of them do include massive sections of substantial size and others represent concentrations of sulphide material that are well above average. It is felt, therefore, that a tentative classification of the deposits and presentation of their geological settings are justified and may help round out the genetic aspects of this study. Accordingly, data considered to be the most pertinent are assembled here in the event that some may fit into larger-scale patterns of mineralization that may take shape as a result of this investigation.The three principal massive sulphide deposits in Nova Scotia are the Stirling, the Smithfield, and the Walton. The locations of these are shown on the accompanying key-map (Figure 1).Three other deposits, the locations of which are also indicated on the map, are the Meat Cove, Rocky Brook, and Gays River de¬posits. Although these fall far short of the minimum dimensions and grade specifications referred to above they are singled out because they have received more than passing attention and are illustrative of the mineralization types to which they belong."

Jan 1, 1960

By Martin P. Raffield

Placer Domes? Campbell Mine, situated in northwestern Ontario, is undergoing an assessment of the efficiency of the operation which is necessitated by the low gold price and a reducing ore reserve grade. A decision has recently been taken to move away from a functional based departmental structure (underground, engineering, geology, etc.) towards a team-based system where crews, engineers, geologists and supervisors are responsible for the planning and operation of a particular area of the mine. The objective is to improve communication and understanding of the goals and achievements and to ensure a forum is available for the generation of ideas. It is intended to increase the accountability and decision-making ability of the teams in an effort to achieve the mines? safety and production targets. This paper presents a critical review of the progress of this organisational change process and its successes and failures at the time of writing.

Oct 1, 2001

By B. Wasmund, M. Parravani, M. Jastrzebski, Z. Coull

"One of the main drivers of overall profitability of pyrometallurgical vessels is refractory lining campaign life. Increased economic pressure to improve vessel life requires innovative solutions to the problem of refractory cooling. Hatch has recently developed a high-intensity, waterless cooling system that bridges the performance gap between external shell cooling and internal water-cooled copper elements. External shell cooling has a limited effectiveness in protecting the refractory lining, because it is thermally insulated from the hotface of the lining by its thickness. This situation does not improve until the lining itself has become worn near the end of the campaign. The patented technology developed by Hatch overcomes this problem by positioning high-velocity air-cooling channels within the lining, closer to the hotface where the cooling benefits can be realized throughout the entire duration of the campaign. The current paper presents the development and application of Internal Air Cooling technology as well as results from the pilot campaign in an operating commercial vessel. Various adaptations for this novel, cost-effective and inherently safe system are also discussed."

Jan 1, 2015

By Peter J. Franklin

"Short-term mine planning of open pits is an activity that has historically been carried out by hand. Typically, the use of computers has played little part in this type of mine planning. This paper describes the objectives and the procedures involved in short-term mine planning, comments on the type of computer systems available, and describes in detail a computer-aided short-term planning and scheduling system known as STEPS.IntroductionThe mine planning department of any o pen-pit mining operation performs a wide variety of different tasks. However, their primary concern is the preparation of detailed long-and short-term mine plans. These mine plan s will define the long-term operating strategies and definitive everyday working plan s for the ongoing development of the open pit.In this day and age, when operating costs have spiralled upwards due to inflation , and product revenues have decreased due to depressed economies and poor markets, it is vitally important for all aspects of the mining operation, including mine planning, to be efficient and cost effective.There are numerous options available for planning engineers when generating a mine plan. A cost effective mine plan must investigate all these options and select the optimum. When using manual planning techniques, it is often impossible to evaluate all the available options. To do this, and to produce an optimum mine plan, a computer is required.This paper discusses mine planning, with emphasis toward the short-term plan and comments on how the processes may be computerized. It also describes in detail, a computer software system called STEPS, which has been designed as an interactive graphics, computer-aided short -term mine planning and scheduling tool."

Jan 1, 1985

By M. Fiset, D. Belley

"To better understand the wear process of various materials that may be used as blades on snow removal equipment, the first step is to evaluate the influence of the load applied and the moving speed on road wear rates of one type of steel and three types of polymers. While the behavior of steel conforms to Archard's law, wear rates of polymers increase to a power of ex of the load applied according to a model implying that the wear of these materials is due to fatigue. The wear rate of some of the polymers varies considerably in terms of speed, unlike the steel. The wear resistance of some of these polymers outclasses the steel tested as long as the speed is not too great. They, therefore, present interesting alternatives for snow removal on more fragile surfaces such as sidewalks and zone made of inter-block slabs.IntroductionSince the dawn of the Industrial Revolution, the massive use of machines has brought with it a number of different problems regarding wear. Snowplowing roads, parking lots and sidewalks is an activity that generates enormous expense in a country such as Canada. To better understand these wear processes and in the hope of stimulating new approaches designed to reduce the costs related to this sector of activity, this paper presents the behaviour of several materials (steel, polymer and rubber) as they wear on an asphalt-fines matrix surface lubricated with water. Also discussed is the effect of various parameters such as the load applied and speed."

Jan 1, 1990

By C. W. Langenberg, D. E. Macdonald, R. S. Strobl

"The successful marketing of Alberta coals will increasingly depend, to a large degree, on an extensive coal quality information base. This information, at present, is generally based on a deliverable, cleaned coaland is confined to existing mine sites. Coal quality information is not as well understood for raw in situ coal outside of mine sites and even less is known about the geological factors that control it.If new uses and markets for Alberta coal are to be developed, such as gasification, coprocessing, and exploiting high rank coals for combustion, it will be imperative that the coal quality parameters important for these utilizations be known. These parameters need to be known for existing deliverable coals and, just as important, for as yet unexploited in situ coal. Factors such as the Cl, No, K, Co, P and trace element contents should be addressed to meet the requirements of these new utilizations.The geological characterization and explanation of what factors control these coal quality parameters is part of research being done at the Alberta Geological Survey. In-seam vertical profiling has been undertaken within the plains and foothills/mountains coals to determine exactly where coal quality variations occur and why. In the Ardley coal zone at the Highvale Mine it has been found, for example, that the ash content of the mined coal is made up of discrete partings and of microsized particles associated with inertinite macerals. The in-seam characterization of coal seams will lead to a better understanding of in situ coal quality variations, leading to new uses and markets for Alberta coal."

Jan 1, 1993

By D. H. Stonehouse

"ALTHOUGH final statistics are not yet available concerning Nova Scotia' s mineral production for 1958, it is estimated that the value will be slightly lower than that of 1957. In making this statement it is but fair to say that one year ago a reduction in mineral value was also forecast (for 1957 as compared with 1956) and final figures from the Dominion Bureau of Statistics ($68,058,743) indicated, instead, an increase of $2,000,000 over 1956. However, 1958 did bring problems to the industry which would indicate a drop in production value. The estimates figure for 1958 is $64,000,000. COAL Coal production came from 28 mines, 5 less than were operating since 1957. There were 5,269,896 tons of coal produced by 1,978,512 man-days' labour, for a tons per man-shift of 2.66 (0.05 higher than during 1957) or an increase of 1.9 per cent over the 1957 all-time high for this Province. This record has been established as a result of concentrated efforts to mechanize the coal mines of the Province, and it is hoped that it will be bettered during 1959. Collieries which showed some production for 1957 and none for 1958 were the McGregor at Stellarton, the Franklin at Sydney Mines, the MacLellan, the Rose bank No. 2 and the Rose bank No. 3 at Inverness."

Jan 1, 1959

By Ahmad Ghahreman, Lin Li

"In this study, the Fe(II)/Fe(III) redox reaction kinetics on the surface of pyrite, have been investigated in a 0.5 mol L-1 sulfuric acid solution for a temperature range of 22 to 65°C. Based on mixed potential theory, chronoamperometry is introduced to study the Fe(II)/Fe(III) kinetics by subtracting the current density of pyrite oxidation in an iron-free acidic solution from that in an iron-containing solution at the same applied polarized potential. Tafel behavior was established by this method to analyze the kinetics of the Fe(II)/Fe(III) redox reactions. The results showed that exchange current densities increased slightly with temperature, however remained on the order of 10-5 A cm-2. The activation energy for Fe(II) oxidation and Fe(III) reduction on the pyrite surfaces was calculated to be 102.0 and 32.7 kJ mol-1, respectively. Anodic transfer coefficients also increased, from 0.24 to 0.39, with increasing temperature, which indicates a weakened n-type semiconductor property at higher temperatures. Electrochemical impedance spectroscopy measurements have indicated that at lower anodic over potentials the charge transfer is the rate determining step of pyrite oxidative dissolution in sulfuric acid solution. In the presence of Fe ions, the major contribution of the total current density comes from the Fe(II)/Fe(III) redox reaction. INTRODUCTION Pyrite, an abundant sulfides mineral in the nature, is commonly considered a valueless gangue mineral frequently associated with other valuable sulfide minerals such as chalcopyrite, or metals such as gold, or coal (Lin & Say, 1999). Pyrite oxidation has been the subject of extensive research in view of gold metallurgy, as oxidation of pyrite is the initial step to break down the pyrite lattice and expose the encapsulated fine gold particles (Gasparrini, 1983). Fe(III) ion and dissolved oxygen (DO) have generally been considered as the two most important oxidants with respect to pyrite oxidation, having been studied extensively in previous research (Zheng, Allen, & Bautista, 1986; King Jr & Lewis, 1980). The process of pyrite oxidation can be viewed as a series of reactions amongst pyrite, ferrous, ferric and oxygen in which pyrite is initially oxidized by the dissolved oxygen in water forming ferrous (Eq. 1), and then the ferrous also is oxidized by he dissolved oxygen to form ferric (Eq. 2). The ferric, produced by reaction 2, then could potentially oxidize pyrite (Eq. 3) and convert to ferrous."

Jan 1, 2017

By G. M. Ritcey, V. M. McNamara

"In the processing of gold ores by the cyanidation route, effluents which are discharged to the tailings areas can contain up to several hundred parts per million of cyanide in complex combination with similar quantities of heavy metals. Complicating this obvious problem of waste control are concentrations of thiosalts and thiocyanates which are roughly equivalent to the amounts of cyanide species. Although most gold mills are located in thinly populated areas, such contaminants can represent a potential environmental problem due to the various limitations exhibited by on-property ponding.The former Extraction Metallurgy Division of CANMET recognized the problem and, in early 1974, invited representatives of the gold mills to Ottawa to discuss the situation. At that meeting members of the Division presented a ""state of the art"" literature survey of cyanide abatement technology for waste solutions, together with preliminary cost estimate data(1). Shortly thereafter, Environment Canada, together with Environment Ontario, decided upon a guideline of 0.1 ppm (0.1 mg/l) total cyanide content as tolerable for an effluent stream which is discharged, in any manner, to the watershed."

Jan 1, 1978

By G. R. Sadowski

"Large subhorizontal joints have been found in the foundation excavations in basalt and granite of Brazilian Dams. Some spread for hundreds of square meters showed slickensides—polished surfaces plus striations—and laminations interpreted as related to shear displacement, what substantially reduced their shear strength and imposed special reinforcement measures against the potential sliding of overlying concrete structures. The geological characteristics of these discontinuities have raised speculations related to their origin, be it related to mechanisms of bulging, cambering or to some tectonic or primary geological event.Several geologists and engineers from the northern hemisphere including Terzaghi already showed to be concerned with their role in granite foundations while in the southern regions Brazilian authors have found similar occurrences but also affecting individual lava flows of continental flood basalts in the foundations of major dams of the Parana Basin, which they designated under the particular name of “fault-joints”. This double-standard designation is self-explanatory of the difficulties involving their origin and related geomechanical properties: faults or just shear joints?Recently, similar features were encountered in the foundations of large dam constructions in anorogenic granites inserted in the realm of the Brazilian Amazon, where some of these discontinuities exhibit features common to tectonic thrusting combined with deep tropical weathering.The evidence of preshearing along the surfaces of such fractures, also associated to products of deep weathering, reduces their geomechanical strength substantially, suggesting values of ultimate phi spanning 12 to 28°. The detection of these descontinuities during initial investigation phases continues to be a major complex task in geological risk evaluations surveys. Trenching associated to some geophysical exploration techniques, although considered to be very basic exploration techniques are still the suggested methods for their forecast and previous determination."

Jan 1, 2015