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By H. Stocker, C. E. Makepeace

"This paper presents the statistical analyses of several sets of data acquired in several programs of sampling of radon daughters in uranium mines. The measurements were taken over periods of days or weeks for given locations or location occupations within these mines. Because the sampling applies to specific intervals of time and specific locations, a method is suggested f or the eventual application of a monitoring program which would be suitable on an annual basis for these locations. The present data and analyses thereof are not justifiably applicable to a monitoring regimen on an annualbasis, without a number of additional assumptions.The aim of the present analyses of concentration measurements is the determination of the minimum number of measurements required to achieve an annual radon daughter exposure estimate, for individual workers, having an error no greater than 50% at the 95% confidence level. The criterion of accuracy is taken from a statement in the American National Standard, Radiation Protection in Uranium Mines (ANSI NI3.8-I973), and is currently used, in somewhat modified form, as a guide to uranium mining licensees in Canada. Uncertainties associated with occupancy time are ignored in the present analysis. IntroductionOne of the principal aims of any scheme of radiation protection is that of improving the accuracy of exposure estimation for workers. The example presented here is from the area of radon daughter exposure estimation for uranium miners. The conventional means of estimating workers' exposures is grab sampling of radon daughter concentrations combined with occupancy time weighting in the various work and travel locations. Uncertainties exist in each of these components, and in an environment of highly variable radon daughter concentrations (such as an active uranium mine) one is always uncertain as to the representativeness of the grab sample (compared to the average concentration) unless a sophisticated monitoring scheme has been implemented based on previous experience in such an environment.Improvements in the accuracy and precision of employee radon daughter exposure records depend, primarily, on three factors;"

Jan 1, 1980

"The Pierre Beauchemin Mine attained commercial production in January 1989, and went on to produce 23 968 ounces of gold for the year, 3% higher than forecast. Underground development was accelerated to prepare the way for the production of an estimated 40 000 ounces in 1989.IntroductionThe Pierre Beauchemin Mine is located nine miles west of the city of Rouyn-Noranda (Fig. I).As a result of the amalgamation with Sullivan Mines in October 1987, the mine is now entirely owned by Cambior Inc.The Eldrich deposit was discovered in 1953and began production in 1955, closing in 1962 following the decrease in gold prices and the simultaneous decrease in silica content in the ore, which was sold to the Noranda smelter for flux. A total of 717 000 tons grading 0.14 oz Au/t were produced during this period.From July 1984 to October 1987, an underground exploration program was carried out by Sullivan on the Eldrich mining concession and the nearby Flavel property. The first phase of the program included reinstallation of surface facilities and dewatering of the Eldrich Mine. Following the completion of the first phase, extensive exploration was carried out, including a major program of diamond drilling. It was then decided to deepen the shaft to a depth of 1800 ft to access a new zone called the No.5 Zone .Following the amalgamation with Sullivan in October 1987, Cambior assumed the role of operator for the project, and continued the shaft deepening work that had already been started. A feasibility study was completed in April 1988 and the Cambior board of directors approved a production decision for the Eldrich-Flavel project.The preproduction program extended from May to December 1988 and was aimed at preparing the stopes in the upper part of the mine and at developing the mine infrastructure at the bottom of the mine.The mine was officially opened in August 1988. Cambior renamed the project the Pierre Beauchemin Mine in recognition of Pierre Beauchemin's pioneer-work."

Jan 1, 1990

By Derek Harvey

"The paper briefly describes the development of the Eickhoff ESA60 roadcutter which is based on the old and well used principles of the shearer loader. It is intended to show that the machine offers a viable alternative to the normal methods used for driving roadways and also for coal production . References are made to installations currently operating in Europe with applications ranging from roadway drivage to pillar recovery. The paper also looks at possible applications in Canada.IntroductionThis paper is an attempt to show how the principles used in mechanical cutting, conveying and roof support are being applied to a development system capable of catering to a variety of situations and conditions. It is also intended to illustrate how the same system can be used as a total mining system for the mining of many minerals.In order to give some sort of time perspective to the age of the principles, reference can be made to an article in Coal Mining & Processing which states:- During World War II the Germans developed the "" panzer"" or armoured face conveyor.- After the war the English developed power cutters or trepanners that were mounted on the face conveyor, this then developed into the shearer.- The first shearer was produced by the Anderson Company in England in 1950 and shortly after that the Eickhoff Company started manufacturing shearers in German y.- The first hydraulic roof support was produced in 1954 by Gullick.This is a potted history of the three major components of the new system, i.e.:- Mechanical cutting element based on the shearer.- Transport element based on the panzer.- Optional roof support based on the hydraulic face supports.It can therefore be said that since the "" youngest"" of the elements was produced in 1954 the principles of the system in respect of the rapid change in mining equipment are in fact old.Of the three major components the most important is the cutting element since the major benefits of the system are to be obtained from this."

Jan 1, 1985

By Robert B. Parsons

"While it might seem like heresy to suggest that ""taxation"" can be a source of financing, never the less some generous tax rules can considerably enhance the tax savings pertaining to a particular expenditure or project. A basic tax knowledge, and careful tax planning, can optimize government participation in a project. INTRODUCTIONIn trying to identify sources of financing for a project, ""government"" as a source of funding is normally thought of in terms of government grants, loan guarantees, interest rate buy downs, property tax waivers, hydro subsidies, and so on. Generally, such concessions are somewhat difficult to obtain, especially in the current period of apparent fiscal restraint. One source of government funding which should not be overlooked is the income tax regime, and, at the provincial level, the various provincial mining tax regimes.While the taxpayer would not normally view a tax system as a potential source of government financing, nevertheless various federal and provincial rules applicable to the mining industry can offer attractive tax deductions - and tax savings - with respect to particular expenditures. In fact, it is not unusual for a civil servant to refer to a tax deduction as a tax ""subsidy"". For example, in the right circumstances, the cost of a smelter expansion in New Brunswick would cost the operator only 31 cents on the dollar, with the federal and provincial governments paying for the other 69 cents by foregoing tax revenues (Table I). In a sense, such tax savings could be compared to a government grant equal to 69% of project costs. Of course, not every project expenditure will generate that degree of government funding. The fact of the matter is that the percentages of tax savings attached to different expenditures cover a wide range, depending on a complex mix of factors. The point to understand is that the tax rules can offer some valuable savings, even after tax reform, and that a basic knowledge of the tax rules can yield some fruitful rewards."

Jan 1, 1989

By H. W. Smith, D. Guerin

"This paper describes the development of a dynamic model for a full- scale (64 tonnes/hr) grinding circuit consisting of an open-circuit rod mill feeding a ball mill operating in closed circuit. The object of constructing such a model is to investigate the static and dynamic behaviour of potential control schemes. Model selection, data processing and parameter estimation are discussed, and static and dynamic results of simulations are presented. Conclusions are drawn with regard to the adequacy of the model for such studies, and likely limitations on control of such circuits.IntroductionThe model developed here is intended to represent the grinding behaviour of the grinding circuit at the Lake Dufault division of Falconbridge Copper Mines Ltd. This circuit has been fully described elsewhere. At the time of the work described, the ball mill discharge was fed to a four-cell flotation bank , the tailings of which are combined with the rod mill discharge in the cyclone feed pump sump. As the emphasis in this study is on grinding behaviour, and as only I per cent of cyclone feed material is removed in these cells, no attempt has been made to include flotation behaviour in the simulation. One effect of the presence of flotation cells in the grinding circuit is, however, to necessitate somewhat finer grinding than might otherwise be needed: this will have effects on mill parameters.The paper is organized as follows. First the selection of models is discussed, paying particular attention to the problem of selecting simple, yet adequate, flow models for the mills. Then data gathering is described. The method of deriving mill model parameters is explained, and the results presented. Mass balancing of cyclone data and the determination of cyclone model parameters are described. The linking of the models into a full simulation is outlined, and sta tic and dynamic results presented. Finally, the results are discussed and conclusions drawn ."

Jan 1, 1980

By P. Au, P. Patnaik, H. Saari, D. Y. Seo, S. Bulmer

Ti-48Al-2Cr-2Nb-xW (where x = 0, 0.5, and 1 at. %) powders were consolidated by hot isostatic pressing (HIP). The consolidated samples were solution heat treated above the a-transus followed by stepped cooling to room temperature. Selected samples were subsequently aged at 950 °C for up to 72 hours. The post-heat treatment microstructure was examined by optical and electron microscopy. It was found that increasing holding time above the a-transus generated a more homogenous microstructure. Utilizing the stepped cooling sequence, especially with a transition temperature of 1270 °C, massively transformed gamma (Ym) was diminished. Aging caused coarsening of the fully lamellar microstructure in the 0%W and 0.5%W samples while almost no coarsening occurred in the 1 % W sample. Precipitates began to form during aging in samples containing W. The precipitates at the lamellar interfaces are fine and have a needle like shape, while precipitates at the lamellar grain boundaries are coarse and circular in shape. The size and number of the precipitates depend on aging time and the level ofW content.

Jan 1, 2006

By I. G. L. Sinclair

"ABSTRACTTill geochemistry was the principal exploration tool employed by Selco in the investigation of a zinc prospect in Lanark Township, Ontario. The geochemical studies were undertaken after the discovery at surface of marble boulders containing bands of sphalerite and lesser amounts of galena.The source of these mineralized boulders was sought by means of B-horizon soil geochemistry, followed, where appropriate, by back-hoe trenching and till sampling. The thickness of the tiff in this part of Ontario seldom exceeds 3 m or 4 m and it was generally possible to sample complete profiles of the till and thus to obtain detailed information concerning the dispersion of zinc. Drilling and trenching at the up-ice extremity of the zinc dispersion trains showed the source of the float to be sub-economic bands of sphalerite in the Grenville marble. IntroductionTill geochemistry was used extensively by Selco during the period 1975 through 1980. It was the principal exploration technique employed in a program seeking carbonate-hosted lead-zinc deposits of the Balmat-Edwards type in the Grenville rocks of southeastern Ontario. This paper describes the use of the method to locate the bedrock source of a group of sphalerite boulders found at the surface near the village of Hopetown in Lanark Township (Fig. I) . Geochemical investigations at this locality were the subject of a previous publication by the author (Sinclair, 1979).All of the analytical work related to this project was done by Bondar-Clegg & Co. Ltd. in their Ottawa laboratory. In all cases the -80 mesh fraction of the till was analyzed. The total zinc content was determined by atomic ab sorption spectrometry after hot aqua regia digestion; readily extractable zinc was determined by atomic absorption after samples had been cold-leached for 18 hours in an ammonium citrate hydroxylamine hydrochloride solution, the pH of which was adjusted to 8.5"

Jan 1, 1986

By S. Huang, K. Xia

"During crushing, rock particle is subjected to complicated loading and the particle shape influences the fragmentation outcome. Thus, a highly controlled laboratory test is desired to establish the relation between the loading and the fragmentation parameters for better understanding the rock crushing mechanism. In this work, a split Hopkinson pressure bar system in combination with high speed cameras is utilized to carry out a dynamic ball compression test, in which the spherical rock sample is adopted to avoid the shape effect. Using the elasticity theory, the history of the axial symmetric tensile stress perpendicular to the diametrical direction along the loading axis is determined, from which the loading rate and the dynamic indirect tensile strength are calculated. With the aid of the moment-trap technique, the total energy absorbed by samples is accurately determined from the one-dimensional wave analysis. Furthermore by considering the kinetic energy of the sample fragments using the high speed camera snapshots, the surface energy is determined for each sample. The relations between the loading rate and the fragmentation parameters, i.e., the number of fragments and the surface energy are established. The application of this method to a granitic rock shows that it is flexible and can be applied to the crushing study of generic brittle solids. INTRODUCTIONCrushers are widely used to break rocks to extract specific minerals in the mining industry, and to obtain rock fragments with desired size distribution in construction industry. During crushing, the breakage of particles can be in either the single-layer mode or the multi-layer mode. In the single-layer mode, the particle breakage can be assumed to be isolated, in which the interaction between particles can be ignored. It is thus suggested by many researchers that highly controlled single particle test should be performed to establish the relation between the input mechanical energy and size reduction for better understanding the crushing mechanism (Yashima et al., 1987; Tavares, 2007; Pitchumani et al., 2004)."

Jan 1, 2015

By R. F. Dawson, A. S. Bagnall, K. Barron

"At Smoky River Coal Limited (SRCL), economic occurrences of structurally thickened coal deposits form attractive surface mining targets. These steeply dipping, structurally complex deposits require that special attention be given to pit wall design and operational practices.Where anchor support is feasible, there is potential for reducing footwall waste requirements and/or increasing coal recovery. SRCL has used rock anchors to support footwall slopes since 1985. This paper outlines design considerations and performance of rock anchor support systems at SRCL.Three case histories are included that illustrate the design process for supporting steeply dipping footwall slopes using rock anchors.IntroductionWestern Canada contains vast reserves of high grade coking coal largely located in two belts within the Rocky Mountain Foothills straddling the Alberta/British Columbia border. There are about one billion tonnes of ""clean"" coking coal reserves (Romaniuk and Naidu, 1986) situated near existing mining infrastructure. Within the reserve areas shown in Figure I, a total of six producers operate 10 large mines linked with ports situated on Canada's west coast. Al! of the producers operate conventional shovel/truck surface pits.Surface mineable reserves within some of the mountain coal mines are located on dip slopes or where the geologic structure has thickened the coal near the surface, creating low strip ratio targets. Footwall slopes in these mines are developed parallel to bedding, thus minimizing waste extraction and preventing undercutting of potentially unstable strata. The base of the mineable coal measures in both north and south regions is marked by massive quartz sandstone units (Torrens Member and Moose Mountain Member) which often form the footwall. Footwalls developed within this basal sandstone unit can attain very high unbenched heights often with little risk of instability. In cases where the footwall is developed on weaker strata above this basal unit, stability considerations control slope height when bedding dips exceed about 30°. In these situations it is desirable to assess the benefits of artificial support to increase the unbenched footwall slope height."

Jan 1, 1995

By R. F. Dawson, A. S. Bagnall, K. Barron

"At Smoky River Coal Limited (SRCL), economic occurrences of structurally thickened coal deposits form attractive surface mining targets. These steeply dipping, structurally complex deposits require that special attention be given to pit wall design and operational practices.Where anchor support is feasible, there is potential for reducing footwall waste requirements and/or increasing coal recovery. SRCL has used rock anchors to support footwall slopes since 1985. This paper outlines design considerations and performance of rock anchor support systems at SRCL.Three case histories are included that illustrate the design process for supporting steeply dipping footwall slopes using rock anchors.IntroductionWestern Canada contains vast reserves of high grade coking coal largely located in two belts within the Rocky Mountain Foothills straddling the Alberta/British Columbia border. There are about one billion tonnes of ""clean"" coking coal reserves (Romaniuk and Naidu, 1986) situated near existing mining infrastructure. Within the reserve areas shown in Figure I, a total of six producers operate 10 large mines linked with ports situated on Canada's west coast. Al! of the producers operate conventional shovel truck surface pits.Surface mineable reserves within some of the mountain coal mines are located on dip slopes or where the geologic structure has thickened the coal near the surface, creating low strip ratio targets. Footwall slopes in these mines are developed parallel to bedding, thus minimizing waste extraction and preventing undercutting of potentially unstable strata. The base of the mineable coal measures in both north and south regions is marked by massive quartz sandstone units (Torrens Member and Moose Mountain Member) which often form the footwall. Footwalls developed within this basal sandstone unit can attain very high unbenched heights often with little risk of instability. In cases where the footwall is developed on weaker strata above this basal unit, stability considerations control slope height when bedding dips exceed about 30°. In these situations it is desirable to assess the benefits of artificial support to increase the unbenched footwall slope height."

Jan 1, 1995

Adaptive processing is often related to the mineral composition of the mining block currently processed. The portions of waste, ore and secondary product minerals considered are always positive and typically sum to 100% (i.e. a composition). A typical solution to predict block averages of spatially dependent quantities would be block kriging. However, kriging is based on spatial correlations and it has been repeatedly shown that correlations of compositional data are spurious and blurred by the constant sum constraint. Aitchison (1982) proposed a general solution for compositional problems, based on transforming the compositional data to a set of logarithms of ratios of components, and analysing the transformed scores. The transform is chosen to be invertible to ensure that no information is lost in the process. This methodology avoids spurious correlation problems and ensures coherence between results obtained with different subcompositions. Pawlowsky-Glahn and Olea (2004) adapted the approach for point-support geostatistics, allowing the prediction of point compositions from spatially neighbouring data, without the artefacts induced by standard multivariate cokriging. Unfortunately upscaling the results of this approach with block cokriging is not straightforward, because of the nonlinearity of logratio transforms. Furthermore, we have to consider those nonlinearities created by the dependence on the block composition of extraction efficiency and processing costs of the possible processing choices. This paper proposes a solution for predicting the conditional expectations of the benefit of processing the block with each processing choice using geostatistical simulations of the local values of the composition and the resulting block integrals. The computation for a large number of blocks can be done efficiently using Cholesky decomposition. The approach also allows the calculation of prediction errors for expected compositions and expected benefit at almost no additional computational cost. Such compositional approach is necessary, for example when processing choices depend on proportions of certain minerals after other components have been removed; or if processing alters the composition in a multiplicative way, by partially removing a portion of some components.

Aug 1, 2013

By Yugo Mitani, Tatsuya Kato, Chiharu Tokoro, Abdullah Al Mamun

Acid mine drainage (AMD), which is a major source of mining pollution, often contains ferric and/or ferrous ions together with several toxic elements. The ferric and ferrous ions in AMD precipitate in several mineralogical forms after neutralization, and the ferric/ferrous precipitates become the main component of the sludge generated after AMD treatment. The precipitates are also good absorbents for several toxic elements. To avoid generation of voluminous sludges and the re-dissolution of toxic elements from the sludge, it is very important to generate well-draining and efficiently adsorbing sludges by controlling the mineralogical form of the ferric/ferrous precipitates. Green rust, which is ferric and ferrous hydroxide, is a double layer hydroxide which is able to sorb several toxic elements. The green rust transforms to goethite or lepidocrocite by rapid oxidation, whereas it transforms to magnetite at ambient temperature by slow oxidation. The magnetite is also good absorbent especially for toxic cations and it makes a compact sludge due to its magnetic properties. We investigated the magnetite generation process at ambient temperature in detail. The magnetite generation process can be divided into three steps; (i) oxidation of Fe(II), (ii) Fe(II) surface complexation to Fe(III) hydroxide, and (iii) crystallization of magnetite. More magnetite can form when the oxidation rate is slower than the crystallization rate, and optimum conditions for its formation are at pH 9.5 with mild agitation. Ferrihydrite is the most common precipitate and it is able to sorb many different toxic elements. However, it drains badly and its solid/liquid separation properties are poor. We investigated the removal mechanism of several toxic elements by co-precipitation with ferrihydrite. We confirmed that the removal mechanism by co-precipitation partly involved surface precipitation when the initial ratio of toxic elements to ferric ion was high, although the main mechanism was always surface complexation. When surface precipitation occurred, highly efficient toxic element removal with ferrihydrite could be achieved.

Jan 1, 2016

By V. I. Lakshmanan

Rare earth elements and yttrium (REEs+Y) are being used in the making of hybrid electric cars, catalytic converters, wind power generators, LEDs, hard disc drives, flat panel displays, and portable electronics. Currently China produces more than 95% of REEs+Y, which has made REEs+Y a critical strategic resource. Process Research ORTECH Inc. (PRO) has developed the innovative mixed-chloride (HCl+MgCl2) solvent extraction processes for recovery of REEs+Y from their ores. The HCl leaching system provides the opportunity to regenerate the acid, while the presence of MgCl2 in the lixiviant enhances the activity of the hydrogen ion by orders of magnitude, making the lixiviant very aggressive and resulting in high recoveries of REEs+Y. Solvent extraction steps are used for separation and purification of REEs+Y from other value metals or impurities including iron, zirconium, hafnium, uranium, thorium, niobium, tantalum and titanium. Direct individual separation of REEs+Y in a mixed chloride system allows avoiding the additional process steps of precipitation and dissolution in HCl. The resulting process has a simplified flow sheet that is closed-loop and environmentally friendly.

Jan 1, 2014

By Ian Sherrell, Michael Pirie, Riddhika Jain

"Conventionally, direct reduced iron (DRI) mixed with char from rotary furnace discharge is cooled down before separating the char via magnetic separator. The DRI must then be reheated for further downstream processing (i.e. smelting). Outotec has developed the PyroMagTM specifically to conserve thermal energy during this separation process. DRI is cleaned by feeding hot particles directly after reduction onto a rotating surface just above a stationary magnet assembly. This allows hot feeding of the clean DRI to the downstream equipment which renders the entire process more energy efficient.Continuous testing of the PyroMagTM was performed to verify design and separation. Because the use of DRI/char was not practical for test use, the pilot plant testing was conducted using a magnetite/sand mixture heated up to and beyond the Curie temperature of magnetite. The separation was efficient for both cold and hot processing with recoveries varying from 98.6% to 99.74%. As expected, the recoveries decreased to as low as 83.99% as the temperature was increased beyond the curie temperature of magnetite (585°C). Long term separation was thermally efficient and sustainable.INTRODUCTIONMagnetic drum separators are widely used in the mineral processing industry. These low to high intensity magnetic separators are used to concentrate various magnetic material, such as iron ore, and less magnetic materials, such as ilmenite and garnet from silica and other contaminantsThere are multiple classes of magnetism based on the effect that each material displays while in and out of a magnetic field. In a simplified fashion, which is more appropriate for mineral processing, the magnetic susceptibility of a mineral is used to define it as being ferromagnetic, paramagnetic or nonmagnetic. In this respect, minerals with varying degree of magnetic susceptibility can be selectively separated with different types of magnetic separation equipment in different stages of a process flow sheet. The lower strength magnets are employed early in the process to remove highly magnetic fractions. Later stages utilize greater magnetic fields for capture of less magnetically susceptible material."

Jan 1, 2016

By Vic Casaletto

"IntroductionThe Canadian mining industry is under immense pressure to compete with foreign mine operations. The very survival of the Canadian mining industry is threatened by lower ore grades, environmental pressures, high cost of labour, unfriendly tax laws toward exploration and the increasing cost of new technology. In order to compete in the world market, Canadian producers and their suppliers are rethinking age old customer-supplier relationships in favour of preferred supplier relationships which can improve the profitability and enhance the competitive position of both partners.This paper attempts to redefine partnerships with suppliers in the context of a ""win-win"" objective. It will outline the measurable benefits to both partners through a representative product which highlights the keynote structure of any successful supplier partnership The Status Quo...Mines all over North America are plagued with the same recurring questions, ""Who has the best product for my operation at the lowest price... How do we know a product will perform to a supplier's projections after the sale...What do we do if the product fails to perform as expected?"" These questions have been asked by underground mining operators for decades but rarely have long-term solutions with measurable results been achieved.The LHD industry is one example of the status quo where partnerships will provide large gains toward technological advancement, reducing mobile equipment costs. The underground mining industry is out of sync with their surface counterparts in the open pit business.Partnerships with suppliers in the open pit world are not only a standard practice but a culture which has existed for decades. Open pit operators enjoy concepts which fix their mobile equipment costs for the life of the mine and hold the equipment supplier accountable for performance and fleet economics for 60 000 service hours and longer.Manufacturers are attempting to transfer this culture into the underground mining industry. Figure I illustrates the significance of a capital driven decision."

Jan 1, 1994

Bahuerachi Project Characteristics Why it?s nicer at Bahuerachi Mexico is a mining country Low political, regulatory and trade risk Low social/permitting risk Proximity to infrastructure Road Power grid (8 km) Rail line (25 km) High grade zones (skarns), CRD and near surface oxide component are sweet spots to the overall system. Size of low grade system points to potential long mine life?and numerous new targets developing. Timelines-2006? 90 to 100 combined RC and core holes to go! MAIN ZONE Drilling ? Goat ?Finish Mid April ? Main Zone, going North, depth of testing dependent, estimated for May ? North Lobe-May ? Commission independent resource estimate by May 06 for results of first pass drilling to date ?tonnesand grades ?Main Zone Milestone. ? Continue infill or expanded drilling to July (minimum) ? 1stpass RC scheduled until September OTHER Targets ? Begin drill testing North Skarn target Mid-April, minimum 5 drill holes, 1,000 meters. Ongoing expansion of target with surface work (mapping) ? Road to Colome(Skarnin north of Main Zone) as part of porphyry program ? Tule(southern) porphyry and skarn system-soils and mapping OUTSTANDING events Metallurgical report on floating and leaching tests (Sulphide/oxides).

May 1, 2006

By R. K. Kandasami

"Naturally occurring geomaterials such as sandstone, limestone and other soft rocks, residual soils are composed of a particulates held together through a cohesive matrix, usually composed of argillaceous or siliceous cementing agents. Geo-materials such as these have been reconstituted in the laboratory using ordinary Portland cement in lieu of the naturally occurring cohesive matrix, in addition to using sand particulates. This cohesive frictional granular ensemble is an ideal model material for understanding the mechanical behaviour of transitional geomaterials such as soft rocks. An important consequence of this cohesion that pervades the inter particulate system is the enhanced tensile strength when compared to a purely granular ensemble. The assessment of strength of these soft rocks and cemented sands is often understood in the framework of continuum mechanics, i.e. considering the cemented sand to be a continuum, and performing simple elemental tests such as uniaxial compression or tension tests. A simple model to describe the behaviour of these cemented sands has been to use elements such as springs, sliders, and dashpots in parallel to describe the existence of a cohesive and frictional component of strength (Jiang et al. 2007). In the framework of continuum mechanics, the mechanical response of these cemented sands have been modeled using traditional plasticity theory, for example utilizing variants of the traditional Mohr Coulomb model, Modified cam clay (Sun and Matsuoka 1999) etc. The typical sand models are amended to include the effects of cohesion, as proposed by Lagoia and Nova (1995).The mechanical response of cemented sands is understood to be transitional to the behaviour of a typical particulate assemblage and a quasi-brittle material. However, the effect of length scale in these material systems has not been investigated. This paper presents a series of uniaxial compression experiments conducted on weakly cemented sand specimens of various sizes. The effect of length scale in these weakly cemented sands is investigated through unconfined compression tests."

Jan 1, 2015

By B. R. Casement

"Managing safety on the basis of after-the-fact reaction to accidents, can never be more than partially successful. Injuries will occur as long as the underlying potential for them still exists. Unless unsafe actions and conditions are systematically decreased, no program can have more than a short-term success.The pro-active Bullmoose loss control process, instead, focusses on heightening awareness of work habits, to prevent incidents by reducing their potential.Any safety program will be doomed to failure if the development of safe work habits depends on the safety supervisor or a safety committee. At Bullmoose the focus is on the critical actions out of which losses emerge. The successful application of performance-related feedback is achieved by taking safety, health, and environmental concerns into consideration on every level, and, by doing the right thing in every job done.What is an Exceptional Loss Control Program?If an accident in an organization creates a flurry of interest, resulting in ""cracking down"" on violations for a short period of time then an ""exceptional"" loss control program exists. Unfortunately, exceptional here does not refer to the effectiveness of quality of the program but to the fact that the organization is managing loss control by exception. The degree of management attention in an ""exceptional"" safety program varies over a period of time, remaining low as long as the rate of losses stays within management's acceptable control limit (Fig. I). When the losses rise above this, management becomes motivated to begin ""exceptional"" efforts to manage losses. When the rate falls again to within the accepted limit, efforts to control losses take a back seat.Such a strategy guarantees that losses will be tolerated or ignored as long as the actual rate is below the acceptable limit. Simply to lower the limit would not reduce losses, but would result in an increased number of flurries of management attention to loss control. This ""on-again, off-again"" style of management teaches supervisors and others that basic loss control is not as important as are statistics."

Jan 1, 1993

By Fred G. Hewett

Cassiar Mine in northern British Columbia began development in 1952. The deposir is found on rhe west limb of rhe McDame Synclinorium in a Mississippian serpentinite body. The serpenltntte, one of the McDame l ntrusives, imrudes Sylvester Group . rocks, which comprise a Lare Devonian to Early M1ss1ss1pptan eugeosync/inal sequence of argillites, quarrzires and volcanics. The foorwall conracr berween Sylvester Group rocks and rhe serpenrinire is a marked zone of broken and incomperent argillite and graphitic schist. The less marked hang- 111gwall contacr 1s a band of indurated argillite. The JurassicCretaceous emplacemenr of the Cassiar Graniric Barholilh is responsible for mosr of the numerous )aims, faulrs and shear zones found in the serpentinite body. Faulting occurred borh before and after asbestos formation. Asbestos is mined from an open pit ar rhe rate of 4,535 ronnes daily. It passes from the pir along a rramline to the mill, where it is concen/rared into nine direcr milling grades. Packaged fibres travel ro over 40 counrries around rhe world for use in the texrile, cemenr and other industries.

Jan 1, 1984

By J. Chenier, M. Boissoneault, D. Ducharme, R. Schonewille

The operation of Falconbridge's Sudbury nickel smelter has undergone significant change since the production was consolidated to a single electric furnace in 1994. In the late 1990's a capital program of about $100 MM (Cdn) was undertaken to expand and modernize the smelter. This project, known as Smelter 2000, was mainly driven by the need to process the new concentrate produced at Falconbridge's Raglan operation in northern Quebec. Included in the scope of the project was the installation of dry concentrate handling facilities, modifications to the roaster feed preparation system, installation of a matte granulation system and modification of one of the converters. Improvements to in-plant hygiene were also an important part of the Smelter 2000 project. Over the past 5 years much has been learned about the challenges in treating two significantly different concentrates. More recently, the introduction of a third concentrate from Falconbridge's new Montcalm operation near Timmins, Ontario has added another dimension to the operation. This paper will describe how the main challenges from the past 7 years have been overcome and discuss the path forward for the Sudbury Smelter Business Unit.

Jan 1, 2005