Search Documents

By R. E. G. Caines, P. Alport

"Operating heavy equipment in Labrador, where the winters are 8 months long and the temperature frequently drops below -40°F (-40°C) for days and sometimes weeks presents unique problems in both the operation and maintenance junctions. Winterization programs must be well designed and implemented at the proper time. These programs must include the proper selection of fuel oil, engine oil, hydraulic oils, greases, cooling system fluids, etc. More often than not, modifications have to be made to the original equipment in order that it can be operated safely and economically in the Canadian North. Manufacturers usually design equipment for a less harsh environment and the user makes adaptations by trial and error.Operators have to be trained for the proper operation on ice- and snow-covered roads in an open-pit mine. Special emphasis must be put on haulage road conditions. In this paper, the authors will cover some specific maintenance procedures, equipment modifications and operator training problems experienced by the Iron Ore Company of Canada in its open-pit operation in Labrador.IntroductionT he Iron Ore Company of Canada is engaged in open-pit mining , concentrating and pelletizing of iron ore. The company operates in two provinces, Quebec and Newfoundland (Fig . 1) . The Knob Lake operation "", based in Schefferville, Quebec, has mine sites located both in Labrador and Quebec . The Caro l Lake Project is situated in Labrador, 25 kilometres east o f the Quebec border at Labrador City. The Carol operation mines, concentrates and pelletizes it s o re before rail transportation to the seaport o f Sept-lies via the Quebec North Shore and Labrador Railway."

Jan 1, 1984

By George Brien, O&apos

The history of the lighting of mine workings dates back to the early part of the 18th century, when small candles known as tallow dips, were used. These were set or held in a lump of wet clay. When looking for gas the flame of. the candle was reduced to a mere glimmer by surrounding the wick below the flame with clay. The candle was then very cautiously raised from the floor toward the roof, the observer screening the brighter portion of the flame with his hand and watching for the first appearance of the pale blue cap above the flame, even at that time, known to indicate the presence of gas. When this appeared the candle was lowered quietly and its flame extinguished before attempting to drive out the gas. A very common and dangerous practice adopted at that time was to get rid of the gas by firing it. This was done by a person selected for his nerve rather than for his caution. Dressed in a? suit of dampened sackcloth or leather, this man well termed a "fireman", would lie prone on the floor of the roadway and light the gas above him by raising his candle fastened to the end of a long stick. If he survived, which was not always the case, he would withdraw promptly to fresh air after the flame had passed over him.

Jan 1, 1924

By Barry James

"This paper discusses past and current energy use patterns in the mining and manufacturing sectors of the industrial minerals industry. Information is presented on the primary energy input types as purchased by the industry, the quality and form of the energy actually required by the various production processes, and the residual form of this energy, either embodied in the product or rejected in gaseous and liquid waste heat streams. With the continuing concerns about the availability of energy combined with the rapidly increasing cost of energy as a production input, the reduction of energy usage through improved efficiency will undoubtedly be an increasing priority for the industry during the 1980s. Reduced energy consumption through investment to improve energy efficiency appears to be advantageous from both the corporate and national perspectives.IntroductionEnergy, like labour and materials, is one of the basic production input s to the various mining, processing and manufacturing production stages in the industrial minerals industry. Energy costs, as a percentage of total production costs, have been well above the average for industry in Canada, accounting for more than 50 cents out of every dollar in the most extreme cases. Consequently, energy has always been a relatively important management concern in the industrial minerals industry.The energy supply and price situation in Canada and internationally has been changing rapidly since 1973, following a long period characterized by declining real energy prices and an abundance and wide choice of energy supplies. It is generally accepted that energy prices will continue to increase rapidly, and that there will be uncertainties about the long-term continuity of supply of some energy types. In essence, a period of relative stability has been replaced by a period of relative uncertainty. In such a changing situation, a reassessment of the role of energy as a production input is appropriate.The following sections outline some of the effects of the changing energy scene on the industrial minerals industry. These effects are dealt with primarily in terms of energy costs, because, in most circumstances, a change in the cost of energy as a production input is the end result of both energy price and energy supply changes."

Jan 1, 1981

By Paul Guliov

Preliminary investigations of stone resources were conducted in the La Range, Johnson Lake-Pelican Narrows-Deschambault Lake and Creighton-Amisk Lake regions of Saskatchewan. The work identified a rich variety of accessible, attractive and technically promising stone resources. Ordovician dolomites in various combinations of red, buff, yellow, grey and purple are very dense and take a very good polish. These are classified as marbles in the industry and some rival the famous marbles of Verona, Italy. A wide variety of attractive granites have been identified. Among these is a jade green stone (charnockite) and ornamental banded granites (gneisses). A dark greenish to black stone (amphibolite) with white and red veining resembles the well-known Verde Antique variety of Vermont and Italy and surpasses it aesthetically and in engineering properties. Some of these stones have been displayed at Canadian and United States expositions where they received an enthusiastic response from the international stone industry. More detailed evaluation and test quarrying of promising deposits are required. Such work could be rewarding to the industry as some stone varieties in the province have the potential for gaining international markets.

Jan 1, 2001

Diverse and considerable energies are associated with mobile equipment operated and maintained on mine sites. Loss of control of these energies is a common cause of injury on mine sites and this is well recognised by the mining industry. In 2006, 4 multi-national mining companies formed the Earth Moving Equipment Safety Round Table (EMERST), with the aim of engaging collectively with the manufacturers of equipment to accelerate improvements in mining equipment design. Originally focused on surface mining equipment, and particularly haul trucks, the focus of EMESRT widened to include underground and exploration equipment. Since 2006, EMESRT has maintained a program of regular visits and other engagements with a steadily increasing number of manufacturers. The membership of EMESRT has also increased, with 15 companies being members in 2012. An initial step undertaken by the EMESRT members was the development of ?Design Philosophies? which drew of the collective experience of mining companies to identify potential unwanted events which cause equipment related injuries and illness. A technique for analysing risks associated with operation and maintenance tasks, the Operability and Maintainability Analysis Technique (OMAT), was subsequently developed and trialled. In 2011, the EMERST members resolved to propose a common form of safe design information to be requested by all members companies during procurement, and the resulting EMERST Design Evaluation for Equipment Procurement (EDEEP) process was launched at MINExpo in Las Vegas in September 2012. The outcomes of OMAT risk assessment and control activities are integrated during this process into a common ?Safe Design Information? template for communication to prospective purchasers. The aims of requesting manufacturers to follow this process are to provide equipment purchasers with a common way of assessing how well the issues in the EMESRT Design Philosophies are addressed in the equipment design; and to provide manufacturers with additional information for use during equipment design. The process involves identifying priority tasks based on frequency and the severity of the consequences of potential unwanted events identified in the EMESRT Design Philosophies; undertaking a task-based risk assessment of priority tasks in conjunction with site-based personnel; evaluating the effectiveness of control measures; and providing information about safe design features in a standardised format.

Aug 1, 2013

During heap leaching of secondary copper sulphide ores operated at low heap temperatures and high levels of leach solution salinity, copper recovery is usually unsatisfactory, due to a slow chemical and bacteriological leaching of the covellite minerals either formed from leaching of chalcocite or naturally occurring in ores. A laboratory test program was conducted to investigate the effect of leach solution temperature in the range of 20 to 50°C on copper extraction during stirred reactor, bottle roll, and short column leaching of fresh or heap leached secondary copper sulphide ores. It was demonstrated that increasing heap temperature is an effective approach for improving recovery of copper from secondary copper sulphide ores. A review of the technologies available for heating heap leach solution or decreasing solution salinity to improve copper recovery from secondary sulphide ore indicates that an integration of copper concentrate pressure leaching with heap leaching is potentially a cost-effective approach. A copper flotation concentrate sample was tested through pressure oxidation with the use of heap leach solutions of varying strengths for the repulping of the concentrate in order to examine its effect on pressure oxidation performance. The test results indicate that use of heap leach solution of high salinity in the pressure oxidation process does not cause a negative impact on the process performance for copper extraction, sulphide oxidation, and recovery of gold (if present) from pressure leach residue, and has additional advantages of removing the bacterially inhibitory aluminum from heap leach solution and generating more acid and ferric iron in the pregnant leach solution. A flowsheet configuration for full integration of the copper concentrate pressure oxidation with heap leaching of secondary copper sulphide ore is proposed and discussed.

Jan 1, 2014

By N. C. Karmakar, Y. V. Rao, M. Aruna

No one can properly work without sufficient light and this is especially so in mines where conditions are difficult. Artificial lighting is very important for the night shift to provide a safe and efficient working environment, which must be evenly illuminated with no obvious dark spaces and a minimum amount of glare. During an illumination survey of a large mechanized surface mine, it was found that the illumination level varied and was not uniform throughout the length of the road; it was high at one side of the road instead of at the centre. There were also different combinations of lamps, with angles of light arm varying from 35º to 70º. In this respect, an experimental study was carried out with a fabricated telescopic light pole to uncover the optimum design parameters of lighting installations. The analysis was done by plotting isolux contours for fixed installations and drawing graphs for various combinations of luminaries, reflectors, light arm angles, and height of lanterns by plotting the horizontal angle of the light arm along the abscissa, and the contour area along the ordinate. The study revealed that the design parameters of the lantern are mainly dependent on the type of luminaires. It was revealed that the pot reflector with a combination of tubular bulbs produces a wide distribution of light, and contributes towards a reduction of luminaries when installed in longer roads.

Jan 1, 2005

The process of gold recovery by gravity concentration is incorporated in the metal recovery flowsheet at seven Newmont Mining Corporation owned mining operations in Australia, North America and Africa. In 2009 gold recovered by gravity processing was equivalent to nine percent of Newmont's total gold sales of 5.3 million ounces. This paper will discuss these applications in detail including a review of plant flowsheets and presentation of recent operating results. Operating performance will be discussed with reference to ore characterisation procedures, interpretation of results, design considerations and optimisation practices as they relate to the recovery of gold by gravity concentration.

Jan 1, 2011

By R. D. Prettie

Wood preservation may be defined as the art of protecting wood from decay. In its broadest sense, however, it includes a much wider field. It might be more properly de-fined as the art of protecting wood from destructive agents, such as decay, insects, marine borers, mechanical wear, etc. The earliest data on record for the preservation of organic bodies is found in Egyptian manuscripts. The bodies which we call mummies were impregnated with antiseptics, of which the principal were natrum (sodium sesqui-carbonate), sodium chloride, and sodium sulphate. After being steeped in the solution, they were subjected to either a boiling or baking process in a bituminous preparation. The first attempts in Europe to preserve timber were made by the Greeks and Romans. They extracted essential oils from the juniper and cypress trees, and either rubbed these oils into the wood they wished to preserve, or bored thousands of small holes in the wood and poured the preservative oil into the holes. The famous statues of Jupiter and Diana were carved out of wood. The ceremony of pouring in the preservative oil by the High Priests was a religious pageant of great importance, of which there are many records.

Jan 1, 1926

By S. Shairp

"After cooling and thickening, slurry from the second stage of the Hudbay zinc pressure leach circuit is filtered and washed on a belt filter prior to disposal. At times, the belt filter can be a bottleneck to the process. Preliminary studies show that filterability of the second-stage (HAL) autoclave leach residue can be indicated by particle size distribution of the filter feed and filtered residue cake. In particular, the Volume Weighted Mean Diameter, D[4,3], generated by a laser diffraction particle size analyzer from samples of HAL Filter feed, shows residues that filter more poorly have a lower Volume Weighted Mean Diameter than those that filter better. INTRODUCTIONHudbay produces cast zinc metal from blends of zinc concentrates at its metallurgical complex in Flin Flon, Manitoba, Canada, using Sherritt’s two-stage pressure leach process (Collins et al., 1994; Collins et al., 1995; Barth et al., 1998; Shairp et al., 2006). Pressure leaching replaced the original roastleach- electrowinning process in 1993.Filtration for the second-stage (HAL) leach residue originally consisted of two stages of vacuum drum filtration with intermediate cake repulping stirred tanks. As part of Hudbay’s 777 Project, with a designed increase in cast zinc production, a pre-feasibility study by SNC-Lavalin Inc. showed that losses of soluble zinc in the zinc pressure leach residue could be reduced by installing more efficient filtering and washing equipment. Based on laboratory performance, capital cost, installation ability, and potential operating cost savings, a 70 m2 Filtres Phillipe belt filter was chosen for the HAL residue, and commissioned in 2000/2001.When the HAL belt filter is performing well, there is no pooling of water on the surface, moisture content is relatively low, and subsequent analysis shows that water soluble zinc content is relatively low. There have been occasions where the filter has performed poorly with respect to the aforementioned parameters. Aside from the filter experiencing mechanical difficulties, there are several variables affecting leach residue filtration:"

Jan 1, 2012

By A. M. A. Mohamed, F. H. Samuel, S. Valtierra, H. W. Doty, A. M. Samuel

"The influence of Fe, Mn, Cu and Mg alloying additions, Sr modification and grain refinement on the microstructure of as-cast and solution heat-treated Al-10.8% Si alloys was investigated using optical microscopy and EPMA techniques. The results showed that the modification effect of Sr diminished with increasing Cu and Mg additions, due to Sr-Cu-Mg interactions. Strontium caused segregation of AlzCu in areas away from eutectic Si regions, and altered the precipitation sequence of the a-Ah5(Fe,Mn)3Siz iron intermetallic from post-dendritic to pre-dendritic, with the phase observed within the a-Al dendrites. Depending upon the alloy Fe and Mn content, a coarser variation (""sludge"") of the a-Fe phase occurred, in the form of polyhedral shaped particles. The AhCu phase dissolved almost completely during solution heat treatment, while Al5Cu2Mg8Si6, sludge, and a-Aln(Fe,Mn)3Siz phases persisted in all alloys, particularly at high Mg and Fe levels. The f3-Al5(Fe,Mn)Si phase dissolved partially in Sr-modified alloys, the dissolution becoming more pronounced after solution heat treatment."

Jan 1, 2006

By H. Lorenzen, D. Buyze

"Magnesium-bearing salts occur in the Zechstein Basin in the north eastern part of the Netherlands at a depth of 1500m to 2500 m.Exploration results justified the exploitation of these salts by means of solution mining for the production of refractory grade magnesium- oxide. This paper discusses design criteria, operation parameters, and methods used for magnesium chloride solution mining by Noordelijke Zoutwinning B. V. (NOZO), an operating company of Billiton International Metals B. V.A unique variation of widely used solution mining techniques has been developed for mining the complex Veendam salt deposit. NOZO extracts salt through deviated wells with a set of parallel, suspended tubings. Cavern fluid pressure is maintained close to that of overburden rock. These special design features provide an answer for the complex characteristics of the minerals, halite, carnallite, bischofite and kieserite, from which a solution rich in magnesium is generated. Dissolution chemistry and rock mechanical behaviour of these salts are unlike those of rock salt. Throughout a few years, NOZO demonstrated adequate process control while they continue improving the operation.IntroductionBilliton, a wholly owned company of the Royal Dutch /Shell Group of Companies, is active in metal exploration, mining, processing, and trading, mainly in the non-ferrous sector.Since 1972 Billiton has been active with solution mining magnesium salts in the northeastern part of the Netherlands, in the Province of Groningen, near the city of Veendam . Solution mining techniques were developed in conjunction with the ""Koninklijke/Shell Laboratorium Amsterdam"" (KSLA) and the ""Koninklijke/Shell Exploration and Production Laboratorium"" (KSEPL), Rijswijk. The company's objective is to produce magnesia sinter (MgO) from magnesium-chloride brine (MgClz) and de-carbonated dolomite (CaO.MgO). The magnesia produced serves as base material for the manufacturing of refractory bricks, used for furnace linings in the steel industry."

Jan 1, 1986

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 W. Mueller, M. Rocheleau, E. Dimroth

The paleogeographic evolution of the Abitibi Belt is subdivided into three phases, namely: 1) a phase of the growth of a submarine volcanic chain, 2) a phase of the emergence and growth of volcanic islands and 3) a phase of uplif t and erosion of volcanic islands. Isostatic calculations suggest that the volcanic sequence in the south of the Abitibi Belt rests on oceanic basement or on the mantle; the volcanic sequence in the north of the belt rests on about 13-14 km of tonalitic basement. 10-15 km of plutonic material accreted to the volcanic islands during paleogeographic phases 1 and 2, and caused the uplif t during paleogeographic phase 3.

Jan 1, 1984

By R. A. Sproule

Abitibi Greenstone Belt ? ~2.745 to 2.680 Ga (U-Pb zircon ages) ? Several lithologically-distinct and structurally repeated(?) assemblages ? Represents: ? Allochthonous terranes? ? Single autochthonous terrane? ? Combination of the above Volcanology of Komatiites in the Abitibi greenstone belt ? Tisdale and Kidd-Munro assemblages have channelized flows ? Pacaud and Stoughton-Roquemaure assemblages DO NOT have channelized flows ? Only Tisdale and Kidd-Munro assemblages are mineralized

May 1, 2003

By H. Yoshida, H. Hatta, T. Suzuki

"The effect of the copper and magnesium contents and quenching rate during quenching on the age hardening behavior of 2000 series aluminum alloys was investigated. For the higher copper-containing specimens as conventional alloys, like AA2024, precipitation of the stable phases increased as the quenching rate decreased under the as-quenched conditions. The maximum hardness after the artificial aging of air cooled(AC) specimens was much lower than that of the water quenched(WQ)specimens. On the other hand, for the lower copper-containing specimens, coarse precipitation did not increase even in the case of the AC. The age hardening behaviors of the WQ and AC were very similar such that the maximum hardness and aging rate were almost the same. Many parts of the fine precipitates that increased the hardness were thought to be the GPB zone or fine S’ phase for the WQ and relatively coarse S’ phase for the AC. From the calculated CCT(continuous cooling transformation)diagrams, the lower copper-containing specimens could maintain the copper and magnesium in the solid solution state during the AC, so they could be quenched at a rather slower quenching rate like the AC.INTRODUCTIONThe 2000 series aluminum alloys, containing copper and magnesium as the major chemical components, are some of the well-known heat treatable aluminum alloys. These alloys have a high quenching sensitivity, thus the age hardening ability of these alloys decreases with as low quenching rate. To prevent the decrease of the age hardening ability, quenching is done by a method such as water quenching, which is not very efficient in an industrial situation, because the method requires such large equipment. For these alloys, reducing the quenching sensitivity helps them to be produced in a rather convenient way. For example, 6000 series alloys such as A6063 have low quenching sensitivity, thus they could be quenched by only air cooling just after extrusion and they do not need water quenching. Based on these reasons, investigations of these alloys with high copper and magnesium contents have been conducted in the past to find a way to lower the quenching sensitivity by adding transition elements such as manganese, chromium and zirconium (Kanno, Suzuki, & Itoh, 1986; Suzuki & Itoh, 1986; Kanno, Sakuma, Muromachi, & Watanabe, 1988). However, very few studies have focused on the quenching sensitivity of the lower copper and magnesium containing alloys because of their usage for structural components with high strength, and most of the past studies have used only the fast quenching method like water quenching. On the other hand, from our recent results, there is a possibility to lower the quenching sensitivity of 2000 series alloys with lower alloying elements. In this paper, the effect of the copper and magnesium contents with lower alloying elements and quenching rate, especially in case of slower quenching rate than conventional quenching method, on the age hardening behavior of the 2000 series alloys is investigated by the hardness measurement, structure observation and thermal analysis."

Jan 1, 2018

By S. R. McCutcheon, D. R. Lentz

"Abstract - The 12.1 Mt Brunswick No. 6 Zn-Pb-Cu-Ag massive sulfide deposit (New Brunswick, Canada) lies between two subaqueous felsic volcanic formations near the base of the Middle Ordovician Tetagouche Group. The footwall comprises rhyodacitic pyroclastic rocks (Nepisiguit Falls Formation), whereas the hanging wall comprises a sequence of rhyolitic flows, breccias, and hyaloclastites (Flat Landing Brook Formation), with an age difference of less than 3 m.y. The Brunswick No. 6 deposit is a proximal autochthonous deposit with a well-zoned massive sulfide body and a basal Cu zone that, at depth, develops into a stockwork stringer sulfide (feeder) system. The massive sulfides are capped sharply by a layered magnetite-chert unit that extends regionally beyond the deposit. The deposit has a keel shape (sheath) formed by the F1F2 interference pattern. The heterogeneous ductile deformation and upper greenschist-grade regional metamorphism has transposed many of the epigenetic stockwork structures and alteration within the host sequence. Hydrothermal alteration is much more extensive, both vertically and laterally, in the footwall (a few 100 m) than in the hanging wall (<100 m). Anomalies farther up in the hanging wall sequence seem to be associated with independent alteration systems related to the rhyolite domes. The least-altered footwall units exhibit keratophyric alteration (albite or adularia) and weak Mg enrichment (chlorite). More intense micaceous (sericite and Mg-rich chlorite) alteration occurs around the footwall sequence. The transposed stockwork stringer sulfides are typically composed of Fe-rich chlorite (± sericite, ± silica) with pyrite, pyrrhotite, chalcopyrite, arsenopyrite, and sphalerite. The (Fe2O3T+MgO)/(Na2O+K2O) and base metal alteration indices are the best practical lithogeochemical vectoring tools at this deposit. Sommaire - Le gîte de 12.1 Mt de sulfures massifs de Zn-Pb-Cu-Ag Brunswick No.6 est localisé entre deux formations volcaniques felsiques sous-marines situées près de la base du Groupe de Tetagouche d’âge Ordovicien Moyen. Le mur consiste en roches pyroclastiques rhyodacitiques (Formation de Nepisiguit Falls) tandis que le toit consiste en une séquence de coulées, de brèches et d’hyaloclastites de composition rhyolitique (Formation de Flat Landing Brook); la différence d’âge entre les deux est de moins de 3 m.y. Le gisement Brunswick No. 6 est un gîte autochtone proximal comprenant un corps de sulfures massifs clairement zoné ainsi qu’une zone cuprifère basale qui passe progressivement à un stockwork de filonnets de sulfure en profondeur (feeder). Les sulfures massifs sont abruptement surmontés d’une unité laminaire de chert et de magnétite dont l’extension par delà le gisement est régionale. Le gisement affecte la forme d’une quille (fourreau) résultant d’un patron d’interférence F1F2. Plusieurs des structures épigénétiques du stockwork et des patrons d’altération de l’encaissant ont été transposés par la déformation ductile hétérogène ainsi que par le métamorphisme régional au faciès des schistes verts. L’altération hydrothermale est beaucoup plus importante, tant verticalement qu’horizontalement, dans le mur (quelques 100 m) que dans le toit (<100 m). Les anomalies situées plus haut dans le mur semblent être reliées à des systèmes d’altération indépendants associés aux dômes de rhyolite. Les unités les moins altérées du mur une altération kératophyrique (en albite ou en adulaire) ainsi qu’un faible enrichissement en Mg (chlorite). Une altération en mica (séricite et chlorite magnésienne) plus intense est présente autour de la séquence du mur. Les sulfures du stockwork de filonnets transposés consistent typiquement en chlorite ferrifère (± séricite, ± silice) accompagnée de pyrite, de pyrrhotite, de chalcopyrite, d’arsénopyrite et de sphalérite. L’indice d’altération (Fe2O3T+MgO)/(Na2O+K2O) et l’indice des métaux usuels sont les outils d’exploration les plus appropriés dans ce gisement."

Jan 1, 2006

By M. B. McClenaghan

"Abstract- The Ontario Geological Survey completed a regional till sampling project between 1984 and 1988 in the Black River Matheson (BRiM) area of northeastern Ontario. The project was designed to aid mineral exploration in the area by documenting the Quatemary stratigraphy and by providing a database of till geochemistry. This paper summarizes the results from the sonic overburden drilling component of the BRiM project carried out in areas of thick drift (> 5 m). Results from till sampling in areas of thinner drift (<5 m) have been presented in a separate paper. Approximately 1100 till samples were collected from 225 sonic drill holes. For each sample, the non-magnetic heavy mineral (> 3.3 S.G.) and fine (-250 mesh) till fractions were analyzed geochemically and visible gold grains were recovered by panning.Gold and other multielement geochemical data were plotted using proportional symbols to high­ light anomalous areas and to demonstrate how to evaluate and interpret a very large geochemical dataset. Thresholds for identifying anomalous concentrations of Au in till samples, defined using the 95th percentile, are 1500 ppb and 12 ppb for the heavy mineral and fine fractions, respectively. The heavy mineral fraction of older tills and to a lesser extent, Matheson Till, display a number of significant gold anomalies in the study area, which in a few cases, are associated with base metal anomalies. The vertical position of gold anomalies in Matheson and older tills varies from directly on bedrock to several meters above the bedrock surface and can provide information of relative ice transport distances."

Jan 1, 1994

By D. Assmus, S. Daly

"Poor fragmentation, high toe areas, excessive shovel wear and tear and frequent re-drilling and blasting of certain tough waste rock zones in the Lomex pit in the early 1980snecessitateda better understanding of these zones.A combination of geotechnical mapping, penetration rate data, toe elevation contouring and observations on shovel and drill performance were used to determine the character and extent of these zones. This complementary information was brought together by the geotechnical mapper and the explosives supervisor.Distinct zones with particular geological characteristics were determined. A classification system with three types of blast and dig-ability was developed for the Lomex pit and later applied to the Valley pit, with considerable success. The three blast zone types are called ""poor"", ""f air"", and ""good"". This system will be described in detail.The explosives supervisor adjusted the blasting parameters to each zone, in particular, pattern spacing and burden. The resulting powder factors showed considerable variation between the poor, fair and good zones within each pit as well as between the two pits. Pattern geometry and length of collar were also adjusted to improve fragmentation. Cost savings resulted from less re-drilling and less wear and tear on drills and shovels in the poor zones and more efficient use of explosives in all the zones. An annual estimated cost savings of well in excess of $1,000,000 is realized at Highland Valley Copper. A by-product of the mapping was the determination of unstable structures and water flowing zones. Blasting was then adapted to this information for enhanced slope stability."

Jan 1, 1992

By A. A. Iranzadeh

The performance of a tunnel boring machine (TBM) depends on the efficiency of the cutters, which can be influenced by geological conditions and rock mass properties. In this study, a three-dimensional numerical model, based on a discrete element method, was used to evaluate the effects of joint orientation and its spacing on the fragmentation process by a TBM cutter. Several models were constructed to study the effects of variable orientation; these models incorporated different spacing, variable spacing, different orientations on the fragmentation process, and different sections of the block model. Three parameters, consisting of induced tensile stress, induced shear stress and maximum displacement, were calculated. The stress in each section that forms chips was considered as critical stress; critical joint spacing and orientation in each section were determined. Results show that the critical orientation was in the range of 45 to 60º, where there was a possibility to achieve the maximum penetration rate. The critical joint spacing was 200 mm and, by increasing joint spacing, the value of critical stress decreased significantly. Furthermore, joint orientation could influence more than joint spacing in the rock cutting process.

Jan 1, 2009