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By K. G. Thorne, L. J. Cabri, L. R. Fyffe, D. R. Lentz, D. Hoy

"Mineralization at the Main zone of the Clarence Stream gold deposit in southwestern New Brunswick occurs within a parallel series of quartz veins that occupy a NE-trending, steeply north-dipping, brittle-ductile shear zone related to the nearby terrane-bounding Sawyer Brook fault. This deformation zone cuts volcaniclastic sedimentary and volcanic rocks of the Silurian Waweig Formation, and is intruded by mantle-derived East Branch Brook gabbroic dikes and a number of felsic dikes. Intermittent shear-zone reactivation during local magmatic activity induced heterogeneous deformation and alteration of the country rocks and dikes. The terminal phase of shearing is associated with narrow pegmatite-aplite dikes that grade laterally into granophyric granite, and into an auriferous quartz vein. Gold, aurostibite, and gold-antimony intergrowths, predominantly with vein quartz, are associated with a low ƒO2 sulfide mineral assemblage (pyrrhotite, arsenopyrite, and berthierite) that has a sulfur isotopic signature consistent with a magmatic source. Gold saturation and deposition occurred episodically between 300° and 360°C at low activity of sulfur, predominantly in response to pressure reduction during brittle failure combined with the effects of decreasing temperature and sulfidation reactions during fluid-wall-rock interaction. Geochronological studies demonstrate that the timing of the emplacement of the pegmatite-aplite dikes and associated auriferous veins overlap with that of the Early Devonian Magaguadavic granite. Moreover, the composition of the dikes is consistent with their derivation from this granite as late fractionates. The Main zone of the Clarence Stream deposit is therefore interpreted to be intrusion-related, with the Magaguadavic granite being the ultimate source of the gold-bearing fluids. La minéralisation de la zone principale du gisement aurifère de Clarence Stream dans le sud-ouest du Nouveau Brunswick occupe une série de veines de quartz parallèles dans une zone de cisaillement fragile-ductile de direction NE et à pendage abrupt vers le nord apparentée à la faille de Sawyer Brook avoisinante qui délimite deux terranes. Cette zone de déformation recoupe les roches volcaniclastiques et volcaniques de la Formation de Waweig d’âge Silurien et est recoupée par les dykes de gabbro d’East Branch Brook, d’origine mantellique, ainsi que par divers dykes felsiques. La réactivation intermittente de la zone de cisaillement durant l’activité magmatique locale a entraîné la déformation et l’altération hétérogènes des dykes et de l’encaissant. La phase finale du cisaillement est associée à de minces dykes d’aplite-pegmatite qui passent latéralement à des granites granophyriques, puis à des veines de quartz aurifères. L’or, l’aurostibite et les intercroissances d’or et d’antimoine principalement associées aux veines de quartz sont associés à un assemblage minéral de sulfures à faible ƒO2 (pyrrhotite, arsénopyrite et berthierite) présentant une signature isotopique du souffre compatible avec une source magmatique. La saturation en or et la précipitation a eu lieu épisodiquement entre 300° et 350°C dans des conditions de faible activité de souffre, principalement en réponse à la baisse de pression durant la rupture fragile ainsi qu’aux effets de la baisse de température et aux réactions de sulfuration durant l’interaction entre le fluide et l’encaissant. Les études géochronologiques indiquent que l’âge de la mise en place des dykes de pegmatite-aplite et des veines aurifères qui leur sont associées coïncide avec le granite de Magaguadavic, d’âge Dévonien Précoce. De plus, la composition des dykes est compatible avec une origine provenant de ce granite sous la forme de phases fractionnées tardives. Le gisement principale (Main zone) de Clarence Stream est ainsi considéré comme étant associé aux intrusions, le granite de Magaguadavic étant la source ultime des fluides aurifères."

Jan 1, 2008

"Polycom, a new approach to ore processing based on pressure comminution, is obviously a very attractive alternative to conventional processing methods.Since a full-scale pilot plant was commissioned in 1986, more than 125 commercial installations, with capacities up to 1000 t/hr, have gone ahead.Already successfully used in processing cement clinker, limestone, coal, and other minerals, Polycom high pressure grinding results in:o Significantly reduced capital costs, because smaller units can be used m new installations;o Capacity increases of up to 100% in existing facilities; and o Operating economies that include energy savings of 20% or more, and reduced wear parts consumption.1. IntroductionAutogenous or semi-autogenous mills in conjunction with rod or ball mills are used with preference for ore processing. Most ball mills are of closed-circuit design and operate with mechanical classifiers (spiral or rake classifiers) or hydrocyclones. In other words, the ores undergo wet primary grinding, since slurries are required for the downstream separation stages anyway. This paper presents a new grinding system based on high pressure comminution of ores. This grinding process allows:- Energy savings of up to 20 % or more- Capacity increases of up to 100 % and more- Reduction of wear costs- Smaller units for new installation and thus- Reduced investment costsThese advantages are highly interesting for both new installations and conversion projects, particulary in cases where an increasing hardeness of the ore, i.e. rising Bond Work Index, reduces the output of the plants or where the metal assay of the ore decreases and the capacity of the existing systems has to be increased. POLYCOM high-pressure grinding rolls have established themselves with great success already for grinding cement clinker, granulated blast furnace slag, limestone, cement raw materials, coal and other materials.Meanwhile more than 250 high pressure grinding rolls have been installed worldwide. Capacities up to 1.000 t/h with roller diameter up to 2.8 m and drive units up to 2.400 kW are installed."

Jan 1, 1991

By N. W. Kirshenbaum

"The Marconaflo slurry system was originally developed to reduce costs and solve technical problems in the marine transport of mineral cargoes. In the short time since its inception, it has been found to offer economies and advantages for land-based and in-plant materials handling. This efficient method of reclaiming and slurrying particulate materials at very high pulp densities can be directly utilized in a wide variety of mineral process systems. These include: storage-reclaim applications, where even cohesive, compacted materials can be reclaimed from settled storage ""on demand""; the growing number of hydrometallurgical operations wherein slurried materials are processed to extract or yield metals; certain applications associated with pyrometallurgical treatment; and as a means of augmenting the performance of conventional mineral dressing equipment, such as thickeners.INTRODUCTIONIn the continuing effort to lower costs of producing minerals and extracting metals, the field of handling and transportation often receives too little attention from those engaged in the mining and winning of ores and metals. This comment, which pertains to ferrous and non-ferrous as well as to non-metallic producers, is especially pertinent to products having relatively low value, where transport costs can be a major portion of the delivered selling price to the minerals receiver.One method which was developed recently for the purpose of reducing costs and solving technical problems in marine transport and handling of mineral cargoes is the MARCONAFLO slurry system. A notable feature of this system is its versatility; in addition to its use in marine transport1*, some of its diverse applications have included the mining and reclaiming of tailings2 and in-plant materials handling3. As the concept and fundamentals of this system have been well explained previously4,5, the mechanics of the system will not be elaborated upon here. Rather some specific ways in which MARCONAFLO can be applied to processing and extraction will be explored."

Jan 1, 1973

By Margaret Anne Stephenson

Today, in Australia, it is increasingly common to see agreements between Indigenous peoples and resource companies being achieved generally as Indigenous Land Use Agreements or agreements pursuant to the ?right to negotiation? process under the Native Title Act 1993 (Cth). Despite progress in this area, resource development on Indigenous lands is not without its challenges for both the resource proponents and the Indigenous parties. History demonstrates that resource development on Indigenous lands has produced struggles between the traditional owners of the land and the resource proponents. In Australia their relationship is generally defined by issues of access to land and assuring continued access to the land for the life of the project. In this context, divisions in Indigenous communities often emerge. The proposed resource project can have the effect of polarising members of an Indigenous community. It may be regarded by some traditional land owners as an advantageous opportunity for the community and by others as a hazard to country and culture. The process of agreement making has proved not only a test for the Indigenous community but also for the resource proponent. In this paper we undertake a contemporary case study of a proposed Australian resource related-development project on Indigenous lands. This project involved a multi-billion gas hub precinct proposed at James Price Point in the Kimberley region in Western Australia. The James Price Point proposal produced a litany of challenges for all parties. The traditional owners faced fundamental social and human rights issues, including a minority opposition to the project, the project's potential cultural heritage impact, the threat of compulsory acquisition of their native title interest by a State government due to an initial failure to settle an agreement, a fracture of their unsettled land claim and a minority rejection of the agreement ultimately reached. Additionally, the ?green? lobby also rejected the proposed gas hub on environmental grounds bringing the green lobby into direct conflict with both the traditional owners in favour of the project and the resource proponent. Ultimately, Woodside announced its decision not to proceed with the proposed gas precinct at James Price Point, in April 2013. In this paper we analyse the complexity of the James Price Point gas hub negotiations with the traditional owners which resulted in an Agreement that promised to deliver substantial benefits for the Indigenous communities. We question why such a favourable and beneficial agreement for the Indigenous community also produced the plethora of challenges and concerns and we consider how future negotiation processes could be better structured to avoid the difficulties that have confronted Indigenous land owners and resource proponents alike.

Aug 1, 2013

By Eddy Dénommé, Deni Villeneuve

"Niobec mine, a producer of pyrochlore concentrates since 1976, became a producer of ferroniobium in 1994 and achieved accreditation to the ISO 9002 standard in 1995. The goal of ISO 9002 is to ensure that the products supplied to clients regularly meet their specifications, through explicit work standards and procedures throughout the production process, from deposit appraisal to ferroniobium production.A key element of ISO 9002 implementation at Niobec consists of the quality control procedures applied to the raw materials: the ore fed to the mill and the pyrochlore concentrate fed to the reduction plant. These controls extend from exploration, deposit appraisal, mine planning and reserves estimation, mining, mineral processing and, finally, ferroniobium production. The implementation of ISO 9002 has allowed more efficient control of the quality of the final product sold to clients. It requires interactive team work, the role of the geologist being to relate all information pertaining to raw material and product quality to the geological framework of the deposits."

Jan 1, 1997

By Mike Dry, Rod Dry

If humanity is truly serious about reducing emissions of carbon dioxide into the atmosphere, today’s power plants burning fossil fuels will have to be replaced by power plants that do not emit CO₂. Unless carbon capture/sequestration becomes practical, the new power plants will be hydroelectric, wind, solar or nuclear installations. Hydroelectricity requires the appropriate geography. Solar installations can only deliver power as and when sunshine is available, and wind installations when the wind blows. Therefore, power from these sources will be intermittent, but the demand for electricity does not follow the patterns of sun and wind. That will require large-scale electricity storage and/or load following by the remaining power suppliers, increasingly so as the use of fossil fuelled power generation declines. Modern nuclear power plants are designed for demand following. However, operating at lower than design output has a negative impact on the economics of nuclear power plants because the overall cost of the electricity they generate is dominated by capital cost. Primary (blast furnace) iron smelting is responsible for a significant part of global CO₂ emissions because the reagent used is carbon. Were it available in sufficient quantity (and at a low enough cost), hydrogen could replace carbon in the manufacture of raw direct reduced iron (DRI), using technology such as modified HYL (Tenova Hyl, 2018) or Midrex (Ravenscroft, 2017). This paper examines a scenario in which, instead of demand following, nuclear power stations are operated at their design capacities and surplus power is used to generate hydrogen in off-peak periods. This hydrogen is then used to replace carbon in the manufacture of raw steel.

Jan 1, 2020

By G. Belzil, F. Robichaud, M. Fullam

"The Goldex mining and milling complex is operated by Agnico-Eagle Mines Ltd. and is located in the Abitibi greenstone belt of Northwest Quebec, Canada. The mill operates presently at a throughput of 8,250 tpd with gold grade varying between 1.8 and 2.2 g/t. The ore is very high in gravity recoverable gold (GRG) at about 92% and as such a significant emphasis was placed on the gravity circuit. Commercial production started in 2008. Average gold recovery is 93.5% with about 68% of gold recovery coming from the gravity circuit. Over the course of the first several years of production, several gravity audits were carried out. In 2009, a complete gravity audit was completed, including ore, classification, Knelson Concentrators, and the gold room. In 2011, an audit was undertaken of the flotation circuit to determine the efficiency by which GRG is floated. Large samples of flotation feed and tails were collected and process for GRG content. This allowed a link between gravity and overall recovery to be made. This paper presents results of the audits and the development of a model linking gravity and overall gold"

Jan 1, 2012

By J. D. Clucas, N. Verbaan, T. Grammatikopoulos, D. B. Dreisinger, C. Forstner, M. Aghamirian

"Search Minerals is currently exploring the Port Hope Simpson (PHS) Rare Earth Element District in southeastern Labrador, Canada. The Foxtrot Rare Earth Element (REE) Project in the PHS District has a 43-101 resource estimate consisting of 3,410,000 tonnes of Indicated Mineral Resources and 5,850,000 tonnes of Inferred Mineral Resources. The indicated and inferred resources contain 1.07% and 0.98% total rare earth element oxide (including yttrium), respectively. The dysprosium and neodymium grades are particularly attractive at 218 ppm Dy2O3 and 1687 ppm Nd2O3 for the indicated resources and 208 ppm Dy2O3 and 1494 ppm Nd2O3 for the inferred resources. The mineralization remains open along strike and at depth and is only one of a number of attractive exploration targets in the Port Hope Simpson area. The REE minerals fergusonite and allanite are present. The ore can be beneficiated by gravity, magnetic separation and flotation to a recovery of +80% for the individual REE. Acid bake and water leaching may be used to extract REE into solution for subsequent purification and recovery. The extraction range for single stage leach tests were 91-96% for Nd, 84-87% for Tm and 92-94 % for Dy with modest acid consumptions. INTRODUCTIONSearch Minerals Inc. (Search) is exploring the 100% owned Port Hope - Simpson District in Labrador, Canada for rare earth elements (REE). This District is approximately 135 km by 12 km in size, and is highly prospective for heavy and light rare earth elements. A total of 11 REE prospects have been discovered in the District to date, including the Foxtrot. In addition, Search is exploring in the 100% owned Henley Harbour region and has joint ventures with Quest Rare Minerals in the Strange Lake region, and with Great Western Minerals Group in the Red Wine complex, all in Labrador. These exploration locations are illustrated in the Figure 1. The focus of this paper is the investigation of the mineralogy and processing of Foxtrot REE materials. The Foxtrot resource falls within the claims held by Search in the Port Hope Simpson REE District. The infrastructure available at Foxtrot is excellent with a deep water port, air strip and road and power infrastructure at Port Hope Simpson. Over $7 Million has been spent to date on exploration and development of the District. The Foxtrot has been explored using prospecting geochemical methods, geophysics (airborne and ground), channel sampling of surface outcrops, mapping and three phases of drilling (18,934 m total)."

Jan 1, 2012

By Grant L. Anderson, Richard C. Rice, Richard L. Jentgen

"Data for underground mine-hoist ropes determined in the Ontario Special Rope Tests were obtained, encoded and analyzed statistically. Prior 10 refined statistical analyses, these data were subjected la characterization studies and preliminary analyses to allow trends to emerge that could be used to guide and facilitate the refined analysis. The data were characterized by determining distribution s for a wide range of variables including remaining strength, service life in terms of lime and hoisting cycles, outer-wire torsion values, elongation during tensile testing, diameter reduction, location of strength loss and the strength lasses associated with corrosion rating and lubrication rating , This paper describes the more important relationships between remaining strength (or, conversely, strength loss) as the dependent variable and some of the principal independent variables mentioned above.IntroductionBoth productivity and safety in underground mines could be improved if mine-heist rope Iife and reliability could be predicted more accurately . As a result, hoist-rope failure processes and their effects on rope life and remaining strength need to be quantified and related in such a way that improved retirement criteria can be developed. This is true whether the failure is incipient or actual or whether the failure mode is by corrosion , wear, fatigue or a combination of these factors."

Jan 1, 1984

By W. N. Wallinger

The mine and concentrator of Cyprus Anvil Mining Corporation are situated in south-central Yukon, some 120 miles north of Whitehorse. The large lead-zinc concentrator employs conventional crushing and grinding , followed by differential flotation, to produce selective lead and zinc concentrates, as well as a mixed lead-zinc (bulk) concentrate. Since the commencement of operations in 1969, the concentrator has undergone expansions and modifications which have increased the capacity to 10,000 tons per day, and afforded some metallurgical improvements.

Jan 1, 1978

By David G. Meadows

During the last decade Antofagasta Minerals? Los Pelambres Mine has dramatically increased its ore throughput following the fast initial phase ramp up through a series of planned incremental expansions. The original 85,000 mtpd, two SAG line plant was commissioned in 1999 and rapidly exceeded nameplate tonnage in only a few months. Following this, the inclusion of a pebble crushing circuit resulted in throughputs in excess of 114,000 mtpd and a recent, final third line SAG and ball mill addition have taken the plant to over 175,000 mtpd even with increasing ore hardness and changing ore feed characteristics. The progressive changes are described in this paper together with how the technical challenges have been met.

Jan 1, 2012

By J. Ji

Oxygen requirement during acidic pressure oxidation of sulphide concentrates can he as high as 800 kg/(m3.h) in the first compartment of an autoclave when the total oxidation residence time is shortened to 30 minutes. To achieve such a high oxygen transfer rate while maintaining satisfactory oxygen utilization, a pilot plant campaign was launched at the Placer Dome Research Centre in 1998 to measure the oxygen mass transfer coefficient in a 5 m3 pressure vessel at a total pressure close to 500 psig with a 30 HP gassing agitator. Maximum oxygen flowrate to the pressure vessel was designed at 3 600 kg/h. In this paper, a great deal of information is provided on the gassing agitator, pressure vessel. measurement procedure and results. Without oxygen sparging, the oxygen mass transfer coefficient is 2 600 h-1 with a mixing power input of 5.0 kW/m3 in solution. With oxygen sparging, the oxygen mass transfer coefficient increases to 3 500 h-1 with a mixing power input of 4.0 kW/m3 in solution.

Jan 1, 2004

By M. Holmes, R. Molnar, E. Norton, K. Baxter, J. Riordan

The Boleo Copper-Cobalt-Zinc-Manganese Project of Baja Mining Corp. is situated adjacent to Santa Rosalia on the Baja Peninsula of Mexico. The El Boleo ore is a mixed oxide-sulfide deposit with major values in copper, cobalt, zinc and manganese. The metallurgical process designed to treat the El Boleo orebody involves a sulfuric acid leach in seawater using oxidative and then reductive leaching to maximize metal extraction. The leach solution is separated from the barren solids via counter current washing through a series of high rate thickeners. Copper is recovered using conventional SX-EW processing as cathode. Zinc and cobalt are extracted from the copper SX raffinate after iron and aluminum precipitation. The CSIRO DSX solvent system (Versatic® 10 and LIX® 63 mixture) are used in this extraction. Manganese remains in the DSX raffinate and is recovered by soda ash addition as a high quality manganese carbonate precipitate. Zinc and cobalt are acid stripped from the loaded DSX solvent. Zinc is then re-extracted away from cobalt using Cyanex® 272 extractant and stripped into a highly concentrated strip liquor (+100 g/L Zn) and directed to either a spray dryer or a granulator for production of zinc sulfate monohydrate. The zinc solvent extraction raffinate, containing cobalt, advances to another SX circuit using Cyanex® 272, for the recovery of cobalt as cobalt cathode. In this paper, the detailed results from bench and integrated pilot plant testing for zinc recovery from the El Boleo ore will be described. The results of this testing are currently being used to engineer the commercial plant at El Boleo.

Jan 1, 2008

By Fernando Romero Lage

The purpose of this paper is to analyze detailed crushing and screening configurations and the interrelationship as they relate to mass flow balance, operating efficiency, plant availability and final production. The entropy of ore bodies limits the standardization of crushing and screening plants, however, consideration for a continuous and sensible assessment of the mass flow balance of the circuit will yield the best achievable results. Since energy costs have continuously risen in the last few years, it is imperative that these circuits offer low power requirements and low operating expenses. The paper will detail how the efficient implementation of continuous mass flow balance in the application of crushing and screening plants will generate quality improvement and process improvement, which will translate into bigger production and energy savings.

May 1, 2010

By Jun Deng

The aim of this paper is to study the scientificity and reliability of three coal gas indices used to predict coal fire disasters, namely Graham?s ratio, CO/CO2 ratio, Litton ratio and their different characteristics and service conditions. Data from a programmed temperature experiment were applied to check their veracity and accuracy. Each index performed well in detecting the level of a fire. We conclude that it is better to redefine the definition through experimentation before applying a given index. Integrated analysis of the results can provide reliable reference data for predicting spontaneous combustion of coal.

Aug 1, 2013

By Janis A. Shandro

The mining sector is a major economic driver for Canadian, and British Columbian communities. In parallel strong commitments have been made by industry to the well-being and sustainability of associated communities. However, these dimensions are the least understood. Especially lacking are focused regional investigations that compare the well-being and sustainability of communities dependent on different resources sectors. It is hypothesized that this type of comparative analysis will help to foster a greater understanding of what makes a resource or mining community healthy and sustainable. This paper describes research that examined community-level indicators associated with well-being (e.g. education, income and employment) and sustainability (e.g. economic diversity). The indicators were derived from Canadian Census data for 31 British Columbia resource-based communities (with a focus on mining) during a period of time (1991 to 2001) when resource sectors experienced an economic downturn. Our findings identify that during this decade, mining communities differed significantly from other resource-based communities, and comparative analysis of census derived indictors illuminate challenges that mining communities in British Columbia face with respect to wellbeing and sustainability (such as economic diversity, unemployment, and population loss). To contribute to the mining sector?s efforts towards meeting their commitments to communities, this paper concludes by proposing strategic opportunities aimed at the enhancement of mining community sustainability for policy-makers, communities, and the mining industry to consider.

May 1, 2011

By David J. Forrester

"CANMET’s research into underground coal mining is primarily conducted at the Cape Breton Coal Research Laboratory (CBCRL), established in 1981 to conduct safety research in underground coal mines. Located close to Canada’s largest underground coal producer, in the Sydney Coalfield of Nova Scotia, CBCRL’s program also includes the two western underground coal operations. CBCRL is a relatively small laboratory with a staff of thirteen — eight professionals and five support staff — with an annual budget of over $1 million. In order to maintain effective research response, flexibility is key and staff are increasingly working in project teams, crossing traditional section ties and also drawing from specialist expertise elsewhere within CANMET.CBCRL’s research activities have had a substantial impact on the Canadian underground coal mining industry, particularly in Cape Breton. CBCRL contributed to Cape Breton Development Corporation’s (CBDC’s) threefold reduction in lost-time accidents in the 1980s. Also, in the last four years alone, CBCRL’s work has enabled CBDC to save over $17 million in improved utilisation of reserves and cost savings. The work embraces the three traditional areas of mine environment, strata mechanics and mining technologies, however the current direction has been strongly influenced by recent external and internal factors. It is timely to review progress and recent directions."

Jan 1, 1996

By X. Yuan

"The processing behaviours of ores such as their liberation characteristics in comminution and their response in separation processes are affected by their mineralogical characteristics. Key ore characteristics which are relevant to processing, such as mineral proportions, mineral grain size, grain shape and mineral associations are routinely measured at the micro-scale in polished section using optical microscopes and SEM-based automated mineralogy systems. The application of X-ray micro-tomography to mineral processing provides the means to quantify these important micro-textural characteristics in three dimensions, removing the stereological issues encountered when measuring volumetric information in two-dimensional polished sections. In this paper we present several examples of ore textures to illustrate where X-ray micro-tomography can be applied successfully to obtain quantitative measures of ore characteristics which are useful in a variety of process modelling applications.INTRODUCTION X-ray tomography has been used as a tool in medicine for some years and is being applied in a wider range of fields including geology, palaeontology and mineralogy. In this paper we present some applications of X-ray tomography in mineral processing applications being developed at JKMRC. The availability of SEM-based automated mineralogy systems such as MLA and QEMSCAN has seen the increased use of quantitative mineralogical data measured in two dimensions in the design, operation and simulation of mineral processing plants. When the ore is amenable to measurement by X-ray tomography this technique can provide quantitative data for characteristics such as mineral grain size, shape, mineral associations and liberation in three-dimensions. The advantage of measuring these characteristics in three-dimensions is that the stereological issues which bias measurements made on polished sections are removed. X-ray tomography also quantifies the location of mineral grains relative to one another in space - a useful descriptor of ore texture. Like many measurement techniques X-ray tomography has advantages and disadvantages when compared to other techniques. One limitation is that the ability of the X-ray tomography system to discriminate between minerals is a function of the X-ray attenuation of those minerals. While the X-ray attenuation of many common minerals is sufficiently different for X-ray tomography to distinguish between them, there are some where the overlap in X-ray attenuation makes discrimination on the basis of this characteristic alone impossible. An example of this would be chalcopyrite and magnetite. However where the ore mineralogy is suitable to apply X-ray tomography, the technique provides some exciting opportunities to explore the relationship between texture and ore processability."

Jan 1, 2012

By J. I. Mathis

"The failure that was utilized for developing this model was a double bench-scale failure, approximately 20 m in height, in the Misery pit at BHP Billiton’s EKATI mine site. The bench that failed was excavated in biotite schist. Due to previous problems with bench-scale toppling failures, this bench was excavated with a 70° inclined, 30 m deep preshear. Upon exposure, the wall was very clean with half-barrels commonly observed from the pre-shear operation.In August 2003, a bench failure of about 1000 t occurred in this pre-sheared biotite schist (Fig. 1). Upon examination it was noted that the foliation that paralleled and dipped at 70° into the face when excavated was approximately horizontal at the top of the failure (Fig. 2). While the failure mode itself appears complex, the failure was apparently driven by three factors:• a low-angle, low-frictional strength fault or discontinuity at the base of the failure area;• water either contributed meteorically from precipitation and/or from permafrost melt; and• foliation planes providing a viable toppling geometry once toe block motion began to occur.The above details are illustrated in Figure 3.After considerable thought and analysis, a model was postulated for the failure.It is thought that the entire failure had been triggered by displacement of a toe block (Fig. 4). This toe block is bounded on the back by foliation, the bottom by a low-angle, lowstrength fault, and the front by the bench face. Water pressures behind the bench face developed forces on the block as can be seen in Figure 5. These forces were sufficient to induce block motion. As can be seen in the relative shear strength diagram in Figure 6, only a small amount of water is necessary in the face to initiate block displacement. Note that in this figure, a simplistic piezometric pressure distribution was assumed."

Jan 1, 2004

By M. Vallée, J. -P. Charette, D. P. Gold

"The Oka Carbonatite and Alkaline Complex is a Lower Cretaceous intrusive body of the Monteregian petrographic province. Carbonate rocks of various types, and associated alkaline rocks of the ijolite and okaite suites, are distributed in a double ring-dyke structure 4 Yi miles long by 1 1/2 miles across. Alnoite and alrioite breccia pipes intrude all rocks of the Complex and indicate, from inclusions, that a cover of Palaeozoic rocks existed at the time of emplacement.The results of radiometric, magnetic and gravity surveys of the Complex are compiled and discussed both with respect to the regional pattern and, locally, the bed-rock geology. The Complex is characterized by high-intensity anomalies.Exploration activities started during 1953, and mining operations began in 1961 on the property of St. Lawrence Columbium and Metals Corporation, at one time the world's largest producer of niobium concentrates. Because of the boudinaged and fractured nature of many of the rocks and the variability in grade of the ore minerals, the role of the mining geologist is both demanding and exacting. Rock types are varied and their mutual relation-ships ambiguous, the minerals are rare and complex, and close geological control of the ore is needed in the mine and in the mill. Closely spaced diamond drill holes are needed for mining control, and the ore-waste contact is defined mainly by assay results.In the exploration for 'carbonatites' in Eastern Canada, aeromagnetic surveys are judged to be the best exploration tool, followed in decreasing order by the search for circular structures on aerial photographs, regional gravity surveys and radiometric surveys."

Jan 1, 1967