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By B. E. Jones

"The area of uranium deposition is situated within the Churchill Province on the western edge of the Wollaston Iithostructural domain where it underlies the eastern edge of the Helikian Athabasca Formation. The Collins Bay deposit is 6 miles north-northeast of the Rabbit Lake mine. Two principal zones of uranium mineralization are described.The ""A"" zone is a partly eroded, high-grade pod of metal oxide and arsenides sheathed by clay-like minerals. It trends north-northeast and lies under 25 to 40feet of water. Uranium mineralization is localized at or adjacent to the unconformity between the Athabasca Formation and the basement rocks. The basement comprises a granitoid Archean terrain overlain by paragneisses of the Aphebian Wollaston Group. ""A "" zone ore contains phyllosilicates, quartz, pitchblende, rammelsbergite, pararammelsbergite, carbonaceous material, galena, gersdorffite, niccolite, carbonate and a trace of sphalerite.The ""B "" zone lies 6,000 ft south of the ""A "", and subcrops under till cover. It is a partly eroded zone composed of metal oxide and arsenides which occur within variably altered Athabasca Formation. Minerals recognized are phyllosilicates, pitchblende, niccotite, gersdorffite, millerite, carbonaceous material, pyrrhotite, skutterudite and a trace of galena. The Athabasca Formation varies from 90 to 160ft thick. Granitoid gneisses of probable Archean age and paragneisses of the Wollaston Group underlie the deposit. An easterly dipping thrust fault transects its length.The deposit is typical of the ""unconformity-type"" uraniumnickel deposits of the Athabasca Basin. Observed features fit well with the ""diagenetic-hydrothermal"" model for such deposits, as envisioned by Hoeve and Sibbald (/978)."

Jan 1, 1980

By L. A. Melis, J. W. Rowson

"Cluff Mining has successfully operated a gold recovery plant at its Cluff Lake operation in northern Saskatchewan to recover gold f rom Phase 1 uranium leach tailings. The operating circuit consists of tailings repulping, grinding, cyanidation, carbon-inpulp, gold recov ery, and cyanide destruction by acidification, volatilization and re-neutralization. The process is described and operating data and metallurgical results from the operation are provided.INTRODUCTIONCluff Mining, a Saskatchewan partnership, is owned 20 per cent by Cameco and 80 per cent by Amok Ltd. /Ltée. (Amok), manager and operator of the partnership.The current operation includes the Phase II uranium mining and milling facilities, located at Cluff Lake, 700 km north of Saskatoon, capable of processing 300 000 tonnes o f ore to produce about 4 000 000 lb UPs (1500 tonnes of uranium) per year.The Phase I operation was initially established to process the very high grade ""0"" uranium orebody from 1980 to 1983. The leach tailings from the Phase I mill operation were found to contain elevated level s of gold . These high gold values were partially due to the gravity pre-concentration step included in the uranium recovery circuit, and to the naturally high levels of gold associated with the uranium mineralization in the""0"" orebody .During the Phase I operation some 6475 tonnes of leach tails were produced and stored in a total o f 2916 large concrete containers (vaults). This method of storage was, at the time, deemed to be the preferred method of temporary storage for the tailings.This temporary storage of high-grade gold tailings facilitated the reclamation and reprocessing of the leach tail s for gold recovery. The primary reason for reprocessing the Phase 1 leach tails was to provide for long-term permanent disposal of the material as an admixture with Phase II tailings in the Cluff Lake tailings disposal area. Although there was limited tonnage, the high gold content in the material made the in stallation of a gold recovery circuit economically justifiable."

Jan 1, 1989

By Robert B. Parsons

"It is quite likely that more than a handful of junior exploration companies will receive some startling news from their accountants this spring when 1989s tax returns are being prepared. These companies could find that, for the first time ever, they will have to write a cheque to the federal government on account of a new federal capital tax which became effective July I, 1989IntroductionMany mining companies which have never had to pay a federal income tax are finding that they indeed have a tax liability for 1989. Non-producing companies, such as junior exploration companies, almost automatically assume that they don't have to pay any income tax. But, a new tax imposed under the Income Tax Act catches especially the company that has no income.Effective July 1, 1989, a federal capital tax (some call it a corporation minimum tax) is payable by any corporate carrying on business in Canada where the corporation has ""taxable capital"" exceeding $10 million. As a result of the popular use of flow-through shares in recent years, many junior exploration companies are finding that their balance sheets show capital stock over $10 million, and that they are consequently caught by the new tax. Further, some of these companies are finding, to their chagrin, that the tax for 1989 was due on February 28, 1990, and that non-deductible interest is ticking away on unpaid taxes."

Jan 1, 1990

By T. Yalcin

"This paper describes the development of a process flowsheet designed to provide high dewatering rates and to bring about savings in tailing disposal costs. The flowsheet comprises a hydrocyclone, a settling cone and a thickener arranged in closed circuit. The mill tailing, after pulp density adjustment, is fed to the hydrocyclone which yields two products. The underflow product is sent to the settling cone for further dewatering. The overflow product, together with the settling cone overflow, goes to the thickener which, with the aid of flocculants, gives a clear effluent and a relatively dilute underflow. The latter combines with the original mill tailing to form the hydrocyclone feed. Solids finally leave the system in the settling cone underflow which can reach pulp densities of up to 78%, making it suitable for direct disposal or for use as mine backfill.Some discussion is included for the selection and sizing of equipment required for this process. INTRODUCTIONDewatering is an essential process for the disposal of mill tailings which forms an added burden in milling practice, often with little or no return. It is, therefore, desirable to conduct this process as economically as possible. One way of reducing costs would be to increase the rate of dewatering so that savings can be made in the size of dewatering unit s which would lead to lower capital and operating expenditures.A common method of dewatering mill tailings is gravity sedimentation which is frequently carried out with the aid of flocculation. In most cases, flocculation greatly enhances the sedimentation process, but only until a pulp density of 50% to 55% is reached in the settled material.Centrifugal sedimentation in hydrocyclones can provide high pulp densities rapidly, but does not result in a clear effluent.This paper outlines a suitable combination of gravity and centrifugal sedimentations that results in an over-all high rate of dewatering. The system developed produces a material of high pulp density while at the same time giving clear effluent."

Jan 1, 1989

By C. A. Rowland

"Plant owners and operators, plant designers and grinding mill manufacturers are giving much attention to the design and manufacture of autogenous and semi-autogenous grinding mills, particularly the mills that have large diameters and draw power up to 10,000 hp and greater. Reliable designs giving long operating lives are required in today 's ore processing plants.This paper reviews bench-scale and pilot-plant testing to determine first if the ore is suitable .to be ground by these methods and then reviews the data obtained from pilot-plant testing that is used to select the mills and the grinding circuit. The paper then discusses the use of the pilot-plant results to design the mills. The most important pilot-plant data used for mill design are power and the amount of ball charge to be used. The mill size selected is a combination of these factors. Pilot-plant data not only establish power requirements, but can be used in the selection of the type of drive, variable speed or fixed speed, and the operating procedure to be followed. This leads into the mill control circuit to be used. The total charge in the mill, the type of drive and mill discharge arrangements are needed in the calculation of stresses and bearing loads. Conclusions reached from pilot-plant work are used to obtain data for process design, and autogenous and semiautogenous mill design should be part of any test program incorporating either or both of these grinding methods."

Jan 1, 1981

By D. A. Trotter

"Low-pressure sodium light sources have been available for several years, but have not received wide acceptance in underground mining. This is because they are difficult to operate using DC power, they are not an intrinsically safe light where explosive gases may be encountered and they give poor colour rendition.With the need for energy conservation, several Canadian hard-rock metal mines are now changing their lighting to low pressure sodium, as it has the highest efficacy of any light source in terms of lumens per watt. Studies have pointed out several other advantages as well. Glare can be controlled, they penetrate fog well, they are easily maintained, they have a long life and they give the highest visual acuity when compared to other types of lighting. As well, in an underground mine, contrast is much more important than colour for task identification. For close work, the colour problem is alleviated with the use of cap lamps.Case studies are presented from Canadian practice. These show how the lights are modified for underground use, calculations preceding light installation, and how and where the lights are installed in the underground environment. Mention is made of worker reaction to the lights and possible physiological effects.IntroductionThe importance of good underground lighting to the total environment of mining cannot be overemphasized. In addition to the obvious benefits of improved worker morale, available studies show that good lighting practices reduce accident severity and frequency as well as increase production."

Jan 1, 1982

By R. Mariano

"The ability to optimise a concentrator from mill feed to final products requires a process simulator that integrates comminution, classification and separation stages. A key part of any such integrated process simulator is the inclusion of a model of mineral liberation in comminution to predict the particle composition distribution of the comminution products. This need was recognised by Gaudin (1939) who proposed a model of liberation based on the cubic fracture of a mineral texture composed of cubic grains of two minerals.This paper describes the development of a texture-based model of mineral liberation that builds on the method proposed by Gaudin. The approach described here, termed the JK-Gaudin Random Liberation model (JK-GRLM) uses as its basis the measured, volumetric mineral texture data that can be quantified for a given ore using X-ray micro-tomography. The textural data required as inputs for the JK-GRLM include the mineral grain size distribution. While the Gaudin model (in common with other existing liberation models) is a two-mineral (or two-phase) system, the JK-GRLM extends the approach to multimineral systems of up to 15 individual minerals, making it more widely applicable.An example of the application of the JK-GRLM to a base metal sulphide ore is provided. In the example the JK-GRLM is used to simulate the breakage of the measured ore texture and the particle composition distributions of the simulated progeny particles are compared to the measured particle composition distributions of ore that has been physically broken.The ability to calibrate this mineral liberation model with measured ore texture will allow it to be applied in greenfield situations where geometallurgical programs measure texture and in brownfield applications as a key part of integrated process simulations. The development of this model enhances our ability to simulate mineral processing operations as an integrated system."

Jan 1, 2016

"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 G. E. Agar, J. J. Barrett

"Traditionally, batch bench-scale flotation tests have been used for evaluating flotation reagents by comparing the results of tests done with various additions of the reagent in question. Usually, comparisons are made of the concentrate grade and recovery or some figure of merit involving an empirical combination of both. In some cases, statistical methods have been used to make the comparison and even to identify optimal combinations of reagents.None of the preceding technology utilizes the fact that flotation separations can be described by relatively simple kinetic equations that will serve not only to quantitatively describe the influence of a reagent, but will also aid in designing an optimal separation procedure. Examples of the use of a first-order rate equation for evaluating the impact of a reagent addition and for optimizing the reagent addition are given.IntroductionThe classical method of evaluating flotation reagents is to conduct batch bench-scale tests while varying one factor at a time. Some of the shortcomings of this technique have been pointed out and statistical design and evaluation of experiments has been advocated. Although the statistical approach is superior to the one-at-a-time method, it still is dependent on the results of a batch test conducted for a specific duration.That flotation is primarily a rate process than can be described by a first-order rate equation has been recognized for a long time, but the application of this knowledge to the evaluation of reagents has received little attention. In this work, it is demonstrated how the parameters of the first-order rate equation can be utilized to evaluate the influence of reagents on flotation."

Jan 1, 1983

By M. J. Michaud, M. J. Lavigne

"Abstract - North American Palladium Ltd. operates its Lac des Iles open pit palladium mine 85 km north of the city of Thunder Bay, Ontario. The Roby Zone deposit occurs within the mafic/ultramafic Lac des Iles Intrusive Complex (LDI-IC), which was created by multiple pulses of magma of varying composition within several closely spaced chambers. Chaotic lithological distribution, the presence of magmatic breccias, and the rarity of rhythmic layering suggest a dynamic intrusive environment with disruptive magma pulses. As of December 31, 2001, measured and indicated resources for the 950 m long by 815 m wide Roby Zone deposit totalled 159 Mt grading 1.55 g/t Pd, 0.17 g/t Pt, 0.12 g/t Au, 0.05% Cu, and 0.05% Ni at a palladium cut-off grade of 0.7 g/t. The Roby Zone contains an additional 73 Mt of inferred resources at similar grades.The Roby Zone is dominated by varitextured gabbro containing pipes and pods of breccia, and large blocks (~60 m across) of varying lithology. Mineralization at Lac des Iles occurs as: (1) a PGEand base metal-rich magmatic matrix of breccia (breccia ore); (2) mineralized dikes or sills (gabbronorite in North Roby ore); (3) lower-grade mineralization in varitextured units that are host to the distinctive breccia ore and envelope the North Roby ore; and (4) high-grade mineralization associated with strong silicate alteration exemplified by high-grade ore.The close spatial association of the mineralized breccias with both varitextured units and silicate alteration leads to an interpretation that the energetic magma that created breccia was charged with a dissolved fluid, and that this deuteric fluid exsolved at high temperatures to migrate through crystal mush, enhancing crystallization along its pathways, resulting in variable grain size. This transformation occurred at high temperature and produced sulfide-poor, varitextured gabbro-hosted mineralization exemplified by some of the mineralization in the North Roby Zone, and also found throughout the Roby Zone. The association of hydrous silicate alteration with mineralization can be explained by continuing fluid migration during cooling and continued metal transport. Résumé - North American Palladium Ltd. opère la mine à ciel ouvert de Lac des Iles située à 85 km au nord de Thunder Bay, Ontario. Le gisement Roby Zone est encaissé dans le complexe mafique/ultramafique de Lac des Iles (LDI-IC), lequel représente une intrusion polyphasée créée par plusieurs pulses magmatiques de différente composition à l’intérieur de chambres magmatiques fermés. La distribution chaotique des lithologies, la présence de brèches magmatiques, et la quasi-absence de litage rythmique suggèrent un environnement magmatique dynamique perturbé par l’introduction de nouveau magma. Au 31 décembre 2001, les ressources mesurées et indiquées s’élevaient à 159 millions de tonnes titrant 1,55 g/t Pd, 0,17 g/t Pt, 0,12 g/t Au, 0,05% Cu, et 0,05% Ni, pour une teneur de coupure de 0,7 g/t Pd. De plus, la Roby Zone contient 73 millions de tonnes de ressources inférées à une teneur similaire.La Roby Zone est principalement encaissée dans un gabbro de texture hétérogène (varitextured) caractérisé par des cheminées et des lentilles de brèches et des énormes blocs (environ 60 m de diamètre) de plusieurs lithologies. Au Lac des Iles, la minéralisation en EGP et en métaux de base se retrouve dans la matrice magmatique de brèches (breccia ore), dans des dykes ou des sills minéralisés (gabbronorite dans la zone North Roby ore), comme minerai de basse teneur encaissant le minerai de brèche (breccia ore) et enveloppant la zone North Roby. Du minerai de haute teneur est également associé avec une forte altération en silicates dans la zone high-grade ore.L’étroite association spatiale entre les brèches minéralisées et les unités de texture variée (varitextured) et l’altération en silicate suggère que le magma énergique qui a causé la bréchification était chargé de fluides. Ces fluides deutérique"

Jan 1, 2001

By L. H. Rajala, K. H. Singh

"This paper presents the results of a detailed feasibility study carried out to investigate whether a low-grade deep underground mine of Falconbridge Nickel Mines Ltd., closed since 1975, could be made more productive and profitable by the introduction of new mining technology. For this purpose, recent advances in mine design and development concepts, larger and better designed machines, such as hydraulic drills, high-pressure down-the-hole machines, LHDs, new blasting concepts, more efficient and improved stoping methods, and ground control technology were considered. Technical and economic analyses incorporated the latest computer-based techniques. The mine was reopened in 1979 and the paper concludes with an assessment of actual progress and performance compared with that planned and forecast.IntroductionThe East Mine orebody, located between the Falconbridge Mine and Inco's Cryderman Mine in the Sudbury District of Ontario, has been in production since 1956. From 1956 to 1978, about 5.6 million tons of ore had been mined from this ore zone. The ore body is low grade and was developed as a cut-and-fill operation. Due to high operating costs, the mine has been shut down several times during economic downturns. The latest closure was in 1975 due to a lower demand for metal.In 1978, investigations were initiated to assess the economic and technical feasibility of mining this ore using new developments in mining technology. In this study, consideration was given to the application of bulk mining methods with a potential for higher productivity, trackless development utilizing efficient LHD machines and hydraulic drills, new blasting and fragmentation concepts, and new ground control technology. Advanced computer techniques, such as finite element, for mine design and rate of return with discounted cash flow analyses for the economic comparison- of various mining options were utilized for a rapid and comprehensive assessment during the feasibility stage."

Jan 1, 1981

By A. J. Hyett, R. D. Reichert

"A laboratory and field research program was conducted to investigate the major factors influencing bond capacity of grouted cable bolts. The results indicate that cable bolt capacity most critically depends on the grout uniaxial compressive strength (UCS), the radial confinement, and the embedment length.In the laboratory &apos;split-pipe&apos; tests were conducted using P VC, aluminum and steel pipes to provide radial confinement, and field test sites were chosen in granite, limestone and shale rock masses. For both datasets higher capacities were obtained under conditions of higher radial confinement. A correlation between the two was obtained through a comparison of the radial wall stiffness of the laboratory pipes with that of the field boreholes as measured using a high pressure dilatometer. Cable bolt capacity was found to increase with embedment length though not in direct proportionality.The use of low water cement ratio grouts (<0.40) can increase cable bolt capacities by 50% to 75%. This effect is maximized under conditions of high radial confinement. However, the use of super thick grout paste (0.30 and less) may be both impractical and undesirable, first because of their limited pumpability and second because of their inconsistency in strength. Grouts with a water cement ratio of between 0.35 and 0.40 are recommended for practical cable bolt applications."

Jan 1, 1992

By Guy Chevalier

QCM?s pellet plant, located in Port-Cartier, Quebec, produces up to 8.6 million tons of iron ore pellets annually. Four different types are produced: three for blast furnace operations and one for direct reduction furnaces. The paper presents the scientific approach that led to the installation of new process equipment to improve the reducibility of direct reduction pellets (DR pellet). The findings, the equipment selection and some post start-up modifications are presented. This low silica DR pellet is used in Midrex and HyL shaft furnaces. A good DR pellet has to meet strict chemical, physical and metallurgical specifications. An important metallurgical property is its ability to release oxygen when exposed to reducing gases. Considering that the market for DR pellets is expanding and being aware that reducibility is critical for our clients, a program to improve the latter was undertaken. Test work showed that one factor which has a negative effect on reducibility is the proportion of particles larger than 75 microns. Knowing that the best way to reduce the amount of coarse particles was to close our open grinding circuits, we began evaluating the most suitable classification equipment applicable to our process operations. We settled on hydro-classifiers based on their very sharp cut and their low operating costs. In light of the hydro-classifiers performance it was also decided to replace the hydro-cyclones of an already closed circuit.

May 1, 2003

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

The scanning electron microscope (SEM) was primary developed for imaging applications. With the introduction of the Si(Li) energy dispersive spectrometer (EDS), simultaneous imaging and x-ray microanalysis became possible. However, long working distance and high current were needed because the position and small solid angle of the EDS detector. The high spatial resolution is generally obtained at short working distance with a SEM. Unfortunately x-ray microanalysis is never performed in the best imaging conditions. The annular silicon drift detector system is inserted below the objective lens which gives a higher solid angle (up to 1.3 sr). In consequence, a lower working distance and probe current can be used. An improved spatial resolution becomes possible during x-ray microanalysis. With this x-ray detector installed on a cold-field emission scanning electron microscope, quantitative x-ray microanalysis with high spatial resolution at low beam energy and low current becomes possible with the possibility of using the various different type of imaging at the same time. Also, since the count rate can be as high as 1,500 kcps, which lowers significantly the detection limit of elements as well as the minimum feature sizes of different phases that can be distinguished.

Jan 1, 2014

By R. A. Rabnett, G. Paget, Patrick Walsh

"Tumbler Ridge, Canada&apos;s newest resource community, has been developed differently than have been other resource communities.Since its conceptualization, emphasis has been placed on the establishment of a traditional municipal government at early a stage as possible.Planning f or the community goes back to 1977. By then, extensive study by provincial agencies had shown a new resource town would be required to exploit north east coal. The Ministry of Municipal Affairs, in conjunction with a consultant named R.A. Rabnett began the extensive Tumbler Ridge conceptual plan.The results of the conceptual plan are evident in the organizational and planning goals of Tumbler Ridge. In every aspect from the election of officials to some financial matters, the town functions as a normal municipality. With the resource companies of the North East Coal Development within its municipal boundaries. Tumbler Ridge has been able to debenture its capital projects against its municipal tax base.The town&apos;s ability to function as a normal municipality is enhanced by its control over Crown land it has purchased from the province. This gives it further control over the development of the community and helps in establishing agreements with the resource companies and the provincial government to ensure that housing and service needs are met. While resource company representatives sit on certain municipal committees, their roles are advisory in nature.The community continues to move toward full municipal status and will have a fully elected Council by 1986.BackgroundPlanning for the development of northeast British Columbia coal resources began in 1976 under the aegis of the provincial Cabinet Committee on Coal Development. A series of subcommittees were established including a Townsite/Community Development subcommittee. The Ministry of Municipal Affairs chaired this subcommittee and continued as the lead agency for the provincial settlement planning effort over the period 1976 to 1981."

Jan 1, 1983

By Irving Wigden

The world is fast becoming information based. Mine companies migrate business infrastructures to be handled electronically. Suppliers move onto the worldwide web. In this ?e-world? successful suppliers will recognize they no longer trade in just equipment, but in knowledge. Companies can no longer just provide products and services, but instead must find ways to harness their knowledge to provide new value for customers. Mine customers will be attracted to suppliers that can help them streamline the process and use Information Technology to optimize operations, increase profit, reduce cost and enhance shareholder value. With the continued move to industry standard communications and software platforms, technology that formerly stood alone can now be integrated with other technologies. This creates more powerful systems that mine operators can use quickly, easily and cost effectively. These unified architectures improve productivity, provide higher asset optimization and allow more informed decision-making. As a leading supplier of process automation solutions for the industry, ABB provides a dynamic range of such control systems. These systems are designed for instrumentation controls, variable speed drives, electrical distribution, electrical equipment and related services for Mine Automation. Enhanced by ABB´s new family of integrated software solutions ? collectively known as Industrial IT ? ABB´s control and Scada systems place you in the best position to optimize your plant, process and enterprise operations. The paper discuss system integration and installation of High-Tec system in an underground mine. ABB has the ambition to be a System Integrator and co-operate with partners in different areas of technology. To day it is a problem to find one Supplier that can be responsible for the complete Automation System. The design of the system is also much depending of the design of the mine and also which caving procedure that is used in the current mine. Much of the work must be done in a feasibility study and during the design phase. If there is careful planning and consideration during these phases is vital in order to avoid costly changes during the commissioning phase. The paper will also include a presentation of the benefit of using Automation in an Underground Mine, and how important the integration of the Human Being is to the Automation System. The most profit gained in mining industries are received when the mines can reduce internal and external disturbances in the production flow and speed. Must of the experience and discussed in this paper is from advanced technology, that has been developed in Scandinavian and adopted of LKAB in Kiruna. The author of this paper has been responsible för the Automation projects in the Kiruna Mine during 1994 - 1999. These projects include: Broadband communication of data, audio, compressed video in one data stream. Control System for Haulage -1045m Automation of Load Haulage and Dumping machines (LHD) Control of Production Drilling Riggs from a Central Control Room.

May 1, 2002

By D. Raicevic

After more than 93% of the uranium is extracted from Elliot Lake uranium ores by a sulphuric acid leaching process, the leach residue (tailings) contains small amounts of uranium and radioactive isotopes, particularly radium-226, which is the most serious health hazard. Heavy metal components and pyrite are also present, along with the gangue minerals. Currently, over /000 acres of the Elliot Lake area are covered with these tailings, which contain over five million tons of pyrite. Because of constant oxidation of the pyrite by bacteria (thiobacillus) and the presence of moisture, pyrite slowly generates sulphuric acid, which steadily leaches the metal-bearing constituents from the tailings. The seepage-flows of the dissolved contaminants, although often quite low in volume, have an environmental impact on the Elliot Lake area. Although these seepages are treated and most of the contaminants removed and impounded, a small amount of the radioactive contaminants reaches Lake Huron via the Serpent River. This paper describes a flotation approach for treatment of the Elliot Lake uranium tailings to produce new, decontaminated tailings practically free of pyrite, with radium, thorium and uranium contents considerably reduced. The decontaminated tailing produced, which comprises about 75% by weight of the current uranium tailings, appears to be suitable for mine backfill. Because mine backfilling normally uses about 50% of the plant tailings, the surface storage of about half of the uranium tailings, therefore, would be eliminated by this process. Mine backfilling would also increase the mine production and thus enlarge the over-all uranium resources due to recovery of the ore from pillars. The pyrite concentrate produced from the current uranium tailings would be suitable for sulphuric acid production. The possibility of uranium recovery, and disposal of radium and thorium from the concentrates produced, is now being studied at CANMET.

Jan 1, 1979

By H. D. S. Miller

"This paper introduces a new approach for the design of rib pillars. The approach involves an empirical method for pillar design and a discussion of the pillar stability used for open stope mining methods.The empirical method predicts the degree of stability of rib pillars. Pillar load is estimated using two and three dimensional numerical modelling. Rock strength and the shape effect of pillars are used to account for pillar strength. The method has been calibrated with case histories from Canadian open stope metal mines and is compared with other methods used [or pillar design.INTRODUCTIONThe role of rib pillars in open stope mining is to provide stability to a mining block by limiting rock mass displacements and restricting the exposure of a rock mass in stope backs and stope walls. They also provide flexibility in ore extraction by dividing a stope block into multiple working faces.The use of backfill in open stope mining methods has reduced somewhat the need for optimum pillar design. In contrast to permanent pillar methods, the dimensions do not need to be minimized because the pillars are usually recovered in a later stage of mining. However, the consequences of poor pillar design are often overlooked and can still be severe. A pillar that does not perform its intended role may result in excessive stope or pillar sloughing, difficult and expensive pillar recovery, loss of permanent access and remedial costs such as development rehabilitation, artificial support or low productivity.Pillar design concepts of the past were not developed for open stope mining conditions and generally have not been confirmed for open stoping. The focus of this paper is to introduce an empirical design relationship specifically for open stope pillars. It provides a stable, yielding or failed pillar assessment for a given design."

Jan 1, 1989

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By D. Mills, W. H. S. Lawson

"The need to make repairs is seldom a major consideration in the design, fabrication and installation of major components of electrical generation plants. Repair welding, however, is a fact of life in the electrical generation industry, for restoration of degradation in service, from cavitation of hydraulic turbine runners, to corrosion and fatigue damage in pressure vessels. In making weld repairs to carbon and low-alloy steels, the largest source of trouble is hydrogen embrittlement and related post-weld cracking. Various strategies have been developed to control problems from this source, including post-weld heat treatment, the use of nickel-base alloy filler metals and the temper bead welding technique. Each of these basic strategies is being applied as circumstances require; each strategy must, however, be implemented in a manner that reconciles weldment structure and hardness, degree of restraint and service environment with the consequences of unsatisfactory performance of the repaired component.IntroductionMajor working components of electric generating plants are specified and installed on the basis that, wherever technically and economically feasible, they will retain functional capacity without major repairs for the twenty-five-plus years of normal plant lifetime. Nevertheless, repairs are often required, and welding is usually an essential feature of the work. Remedial welding may be performed to correct design or fabrication errors which become evident only at the time of component installation. The most common causes of requirements for repair involve corrosion, fatigue or related processes which prove more aggressive than expected during service. Increasingly, our planning for future repair requirements is related to continual improvements which are occurring in nondestructive evaluation technology. As components are periodically reinspected during their service life, fabrication induced defects may be revealed for the first time quite late in the life of the component. When this occurs, repair must be considered wherever inaccessibility of a flaw makes it impossible to prove its inactivity. Finally, there are certain components, for instance in hydraulic turbines, which cannot be economically made or used without the expectation of service induced wear. Here, periodic maintenance welding must be regarded as a normal event."

Jan 1, 1981