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By Claudio José Martins da Silva

A planta siderúrgica da TKCSA possui em seu sistema de distribuição de gás dois flares (bleeders) que possuem funções distintas durante o regime normal de operação. O flare 2 é responsável por queimar o gás de alto forno de baixo poder calorífico, gerado no início do processo de partida do alto-forno até que o gás atinja as características adequadas para o aproveitamento e ser direcionado para o gasômetro. Já o flare 1 trabalha em conjunto com o gasômetro no processo de controle de pressão e vazão excedente de gás, quando da redução intempestiva de consumo de gás de alto forno. O presente trabalho apresenta a solução implantada pela TKCSA para garantir, sob quaisquer condições de fornecimento de energia elétrica, a operação dos equipamentos elétricos e de todo o sistema de automação e controle operacional dos flares. Podemos dizer que a operação do flares torna-se autônoma e relação ao sistema elétrico e sistema de automação e controle da distribuição de gás de alto forno. O sistema implantado promoveu uma elevação na segurança operacional dos flares, já que, a autonomia operacional impede o apagamento da chama eliminado a possibilidade de lançamento de gás cru na atmosfera.

Jul 31, 2018

By Zuhair A. Munir

"The use of self-propagating combustion reactions to synthesize metallic, ceramic, and composite materials is described. The limitation of this process because of the porous nature of its products is discussed. The formation of dense bodies through the simultaneous application of pressure is shown for a metal-matrix composite. The effect of an external electric field on the synthesis of ceramic and composites is described. The nature of the effect of the field on the mechanism of synthesis is analyzed theoretically and experimentally. The use of the self-propagating combustion to synthesize intermetallic thin films is presented for the Ni-Al and Ti-Al cases. The formation of functionally gradient materials (FGM) by centrifugally-assisted self-propagating high-temperature synthesis is described.IntroductionThe use of self-propagating combustion reactions for the synthesis of a large number of simple and complex materials has been described in numerous publications. These have been amply discussed in several review articles [1-4]. The many benefits of this method of materials synthesis are commonly examined in light of its most significant limitation: the porous nature of its products. The porosity in the products of self-propagating high-temperature synthesis (SHS) is an intrinsic characteristic of the process and its elimination has been the focus of numerous attempts. Various experimental methods have been used to accomplish this goal."

Jan 1, 1994

By G. Sachs, G. Espey

It is well known that high residual stresses are created in tubing by the sinking process, in which no internal tool or mandrel is used.l-4 In this process, the wall thickness is usually slightly increased.4,5 In tube drawing with a plug, the residual stresses are gradually reduced with increasing reduction of wall, and, by the conventional approximation methods of stress measurement, no stress is detected in tubing in which the wall reduction is over 50 per cent of the total reduction in cross-sectional area.l,6 It has also been observed that higher stresses are set up by the use of wide-angle dies than by acute dies.? 'he actual stress distribution in drawn tubing has been investigated by a few workers,7"9 but has not been related to the conditions of the drawing process. Some attempts have been made to correlate accelerated cracking tests for stresses in brass products with the magnitude of the circumferential stresses and the condition of the metal. l-10 Materials and Preparation The material used in this experiment was commercial cartridge-brass (70 per cent Cu, 30 per cent Zn) tubing in the straightened and annealed condition.† This tubing was of various outside diameters and had a wall thickness of 0.032 in. It was sunk to 1/2-in. outside diameter by means of an experimental 10,000-lb. hydraulic draw-bench, with a maximum drawing speed of 8 ft. per minute. All dies were of 1/2-in. diameter. Various die materials and contours were used in order to study the effect of die design on residual stresses in the tubing; the specifications for the dies are given in Fig. I. Castor oil was used throughout as lubricant. Chattering occurred in sinking some of the tubing, particularly when dies having the more acute angles were used, but the tubes showing chatter marks did not differ markedly from those with a smooth surface regarding the magnitude of residual stress. The source of the chattering has not yet been revealed. The wall of the tubing becomes thicker during s nking, as previously observed.4,5 The increases in wall thickness were 3, 7 and 9.5 per cent on the average for 6, 20 and 33 per cent reductions in diameter, no effect of the contour being noticeable. The reductions mentioned throughout this investigation do not consider this fact, but are reductions of the outside diameter. For the evaluation of the residual stress two fundamentally different methods were used. The approximation methodl,ll of splitting a certain length of tubing was employed to obtain a bird's-eye view of the effect of various drawing conditions on the circumferential stress measured by the diameter change occurring On splitting. For

Jan 1, 1942

By G. Sachs, G. Espey

It is well known that high residual stresses are created in tubing by the sinking process, in which no internal tool or mandrel is used.l-4 In this process, the wall thickness is usually slightly increased.4,5 In tube drawing with a plug, the residual stresses are gradually reduced with increasing reduction of wall, and, by the conventional approximation methods of stress measurement, no stress is detected in tubing in which the wall reduction is over 50 per cent of the total reduction in cross-sectional area.l,6 It has also been observed that higher stresses are set up by the use of wide-angle dies than by acute dies.? 'he actual stress distribution in drawn tubing has been investigated by a few workers,7"9 but has not been related to the conditions of the drawing process. Some attempts have been made to correlate accelerated cracking tests for stresses in brass products with the magnitude of the circumferential stresses and the condition of the metal. l-10 Materials and Preparation The material used in this experiment was commercial cartridge-brass (70 per cent Cu, 30 per cent Zn) tubing in the straightened and annealed condition.† This tubing was of various outside diameters and had a wall thickness of 0.032 in. It was sunk to 1/2-in. outside diameter by means of an experimental 10,000-lb. hydraulic draw-bench, with a maximum drawing speed of 8 ft. per minute. All dies were of 1/2-in. diameter. Various die materials and contours were used in order to study the effect of die design on residual stresses in the tubing; the specifications for the dies are given in Fig. I. Castor oil was used throughout as lubricant. Chattering occurred in sinking some of the tubing, particularly when dies having the more acute angles were used, but the tubes showing chatter marks did not differ markedly from those with a smooth surface regarding the magnitude of residual stress. The source of the chattering has not yet been revealed. The wall of the tubing becomes thicker during s nking, as previously observed.4,5 The increases in wall thickness were 3, 7 and 9.5 per cent on the average for 6, 20 and 33 per cent reductions in diameter, no effect of the contour being noticeable. The reductions mentioned throughout this investigation do not consider this fact, but are reductions of the outside diameter. For the evaluation of the residual stress two fundamentally different methods were used. The approximation methodl,ll of splitting a certain length of tubing was employed to obtain a bird's-eye view of the effect of various drawing conditions on the circumferential stress measured by the diameter change occurring On splitting. For

Jan 1, 1942

By David Newman

Multiple seam underground coal mining is ubiquitous in Appalachia. Many coal properties have from two to ten or more economically mineable coal seams. Because of the ability to penetrate 600-feet to 1,000-feet or deeper into the mountainside leaving panels of web pillars separated by barrier pillars, highwall mining is a hybrid between surface and underground mining. As a result, many of the ground control problems commonly associated with multiple seam underground mining exist with multiple seam highwall mining. These include: i) superjacent mines, subsidence and caving propagating to overlying seams and ii) mines, pooled water and the potential for inundation resulting from a iii) breakthrough between an active highwall mine and abandoned underground mines in the same or superjacent seams, the presence of overlying or underlying mine workings where iv) pillar columnization in the active mine is not possible, and v) the question of whether to mine ?top-down? or ?bottom-up.? Case histories are presented from southeast Ohio where the Middle Kittanning No. 6 and Lower Kittanning No. 5 seams are successfully highwall mined with 20-feet to 40-feet of largely shale interburden. A highwall miner was caught in a highwall collapse in the Middle Kittanning No. 6 seam when it was overmining auger workings in the Lower Kittanning No. 5 seam. Multiple seam interaction caused by the overmining transferred overburden stress onto the Lower Kittanning No. 5 seam. The overburden concentrated through web pillars initiated auger web pillar failure, resulting in roof collapse and subsidence in the Lower Kittanning No. 5 seam that propagated up to the Middle Kittanning No. 6 seam. A second case history involves multiple seam highwall mining in southeast Kentucky. The A3 Rider, A3, B2, and C1 seams are being highwall mined around abandoned underground mines in the A3 and B2 seams and augering in the A3 Rider. Because of spoil storage constraints for the surface contour mines, the highwall miner follows the active pits in each seam so a standard sequence of ?top-down? or ?bottom-up mining does not exist. The planning and engineering design considerations associated with each case history is presented along with geotechnical information. In the case of the highwall collapse a back analysis is presented of the stability and safety factors for the auger webs, highwall miner web pillars, and barrier pillars.

Jan 1, 2009

By G. E. S. Valadao, J. D. Miller, C. L. Lin

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake poremicro structure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 m, length of 500 m and height of 4000 m. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: 1) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method,2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4)some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By S. E. Cook

This article uses the case of the Royal Bafokeng Nation to argue that royalties and dividends from mineral resources, if managed well, can provide direct benefits to the surrounding community even while the state collects its share of mining revenues through taxation. The key to this model is the effective management of the resource income flowing into community coffers. Where some of this income may fund urgent interventions in the community, a portion of the income can also be used to establish an intergenerational wealth fund to meet the needs of future generations. As a depleting resource, minerals like gold and platinum are not a sustainable source of income, and must be replaced over time by more regenerative income streams. These strategies and dynamics are manifest in the Royal Bafokeng Nation?s status as both community and quasi-municipality, a labour hosting and a labour sending community, a mine operator and a mine owner. The Royal Bafokeng Nation also owns one of South Africa?s largest community-based investment companies, which channels revenue derived from platinum deposits into a broad investment portfolio that in turn funds an aggressive social development program for 150,000 people living in twenty-nine rural villages.

Jan 1, 2013

By E. Eccleston

The ConRoast process for the production of platinum group metals involves the use of a fluidized bed reactor for the removal of sulphur from ore concentrates by roasting prior to smelting in a DC-arc furnace. Test work was carried out in 2007 at Hazen Research in Golden, Colorado to provide the data necessary for a commercial roaster to be designed by Technip. This paper discusses the rationale behind the test work, the goals for calcine composition to be used as smelting furnace feed, the results of various roaster operating parameters in terms of calcine composition (particularly residual sulphur and the fate of trace elements), and the impact of the results in terms of a commercial roaster design.

Jan 1, 2009

[Adams, Douglas K General Electric Co., P.O. Box 2331, Denver 1, Colo. Adams, Frank E U.S. Steel, 919 Kearns Bldg., Salt Lake City, Utah Alger, Van Kaiser Steel, Sunnyside, Utah Allan, Andrew Thompson Creek Coal & Coke Corp., Glenwood Springs, Colo. Allen, Earl W Mine Safety Appliances Co., 257 Rio Grand St., Salt Lake City, Utah Allen, Thomas Chief State Coal Mine Inspector, State Services Bldg., Denver, Colo. Anderson, Nephi W :Book Cliffs Coal Co., Dragerton, Utah Anderson, W. J Texaco, Inc., 845 N. 5th E., Price, Utah Ankeny, Marling J U. S. Bureau of Mines, 5308 Roosevelt St., Bethesda, Md. Arentzen, E. M Lee-Norse Co., Charleroi, Pa. Arentzen, L. E Lee-Norse Co., 2975 18th St., Boulder, Colo:]

Jan 1, 1961

By Clarence Zener

The internal friction of nonferrous metals vibrating at low stress amplitudes has so far always been successfully interpreted in terms of inhomogeneities of one sort or another. Examples are the fluctuation of stress across a specimen vibrating transversely,1,2,3 the stress inhomogeneities due to the elastic anisotropy and partial random orientation of the individual crystallites, localized weak regions introduced by cold-working,6'7 grain boundaries and possibly twinning planes.8'9 Perfect single crystals are, by definition, homogeneous. Actual single crystals usually, perhaps always, contains some imperfections. The present investigation was undertaken to determine whether the internal friction of single crystals may likewise be attributed to inhomogeneities. This study was made possible through the gift of a large single crystal of 70-30 alpha brass by H. L. Burghoff, of the Chase Brass and Copper Co. The specimen, 3.i in. in diameter and 10 in. long, was similar to samples previously described by Mr. Burghoff. Experimental Method The experimental method used has previously been described in institute papers.5'6'9 The measure of internal friction adopted here, I/Q, is X the logarithmic decre- ment, a measure used by some writers, and is also X the specific damping capacity, a measure used by other writers. In all measurements the stress level was kept so low that the measurements were independent of stress level. In all measurements in which the temperature was varied, observations were made as the specimen slowly cooled from its highest temperature. The specimen was vibrated transversely. Observations were made at the fundamental frequency and at the first overtone, of about 620 and 1710 cycles per second, respectively. No attempt was made to avoid acoustical losses. Experimental Results The specimen was annealed for several hours at 450°C. The temperature dependence of the internal friction was then determined from room temperature to 400°C. As shown in Fig. I, the internal friction increased by only a factor of 2 from room temperature to 300°C., then by a factor of 100 during the next Ioo° interval. These measurements are consistent with the view that the observed internal friction is the superposition of two distinct parts. One, dominant at room temperature, is nearly independent of temperature. This part may be accounted for by acoustical losses and by transverse thermal currents. It was not further investigated. The second part, when plotted in the manner of Fig. I, lies upon a straight line. Therefore it has a heat of activation H; i.e., it varies with temperature as Internal friction e-H/RT [I]

Jan 1, 1943

By Clarence Zener

The internal friction of nonferrous metals vibrating at low stress amplitudes has so far always been successfully interpreted in terms of inhomogeneities of one sort or another. Examples are the fluctuation of stress across a specimen vibrating transversely,1,2,3 the stress inhomogeneities due to the elastic anisotropy and partial random orientation of the individual crystallites, localized weak regions introduced by cold-working,6'7 grain boundaries and possibly twinning planes.8'9 Perfect single crystals are, by definition, homogeneous. Actual single crystals usually, perhaps always, contains some imperfections. The present investigation was undertaken to determine whether the internal friction of single crystals may likewise be attributed to inhomogeneities. This study was made possible through the gift of a large single crystal of 70-30 alpha brass by H. L. Burghoff, of the Chase Brass and Copper Co. The specimen, 3.i in. in diameter and 10 in. long, was similar to samples previously described by Mr. Burghoff. Experimental Method The experimental method used has previously been described in institute papers.5'6'9 The measure of internal friction adopted here, I/Q, is X the logarithmic decre- ment, a measure used by some writers, and is also X the specific damping capacity, a measure used by other writers. In all measurements the stress level was kept so low that the measurements were independent of stress level. In all measurements in which the temperature was varied, observations were made as the specimen slowly cooled from its highest temperature. The specimen was vibrated transversely. Observations were made at the fundamental frequency and at the first overtone, of about 620 and 1710 cycles per second, respectively. No attempt was made to avoid acoustical losses. Experimental Results The specimen was annealed for several hours at 450°C. The temperature dependence of the internal friction was then determined from room temperature to 400°C. As shown in Fig. I, the internal friction increased by only a factor of 2 from room temperature to 300°C., then by a factor of 100 during the next Ioo° interval. These measurements are consistent with the view that the observed internal friction is the superposition of two distinct parts. One, dominant at room temperature, is nearly independent of temperature. This part may be accounted for by acoustical losses and by transverse thermal currents. It was not further investigated. The second part, when plotted in the manner of Fig. I, lies upon a straight line. Therefore it has a heat of activation H; i.e., it varies with temperature as Internal friction e-H/RT [I]

Jan 1, 1943

By G. Knight

"Results of a program of dust research carried out at the Mines Branch Laboratory, Elliot Lake, indicate that dust-concentration estimates vary greatly, depending on the sampling instrument, the assessment technique and the properties of the dust cloud. The wide range of the ratio between the estimates by any pair of instruments shows that the correlation between the health hazard and dust-concentration estimates by most existing sampling instruments must be questionable. Important studies are being carried out to permit the definition of mine environments in more precise technical terms. The influence of size selection, the physical property measured, composition and sampling period on the assessment of the health hazard are discussed."

Jan 1, 1969

By W. E. Lamont

The Federal Bureau of Mines conducted research to develop methods of removing phosphorus from the earthy, calcareous hematite ores of the Birmingham, Ala., iron district while simultaneously improving the grade and recovery of the iron values prior to furnacing. An attempt was also made to identify the phosphorus minerals present in the ores. The ores contained about 36 percent iron, 12 to 16 percent CaO, 15 to 20 percent hydrochloric acid insolubles, and 0.30 to 0.36 percent phosphorus. Fractions containing 5 to 15 percent phosphorus were isolated from the ores. Collophanite, Ca3P2O3?nH2O, a member of the apatite group, was the only phosphate mineral identified. Beneficiation methods using flotation and reduction roasting with magnetic separation yielded good grade iron concentrates, but were not as effective for reducing the phosphorus content of concentrates. Reduction roasting followed by fine grinding, magnetic separation, and acid leaching gave iron concentrates containing 62.5 percent iron and 0.04 percent phosphorus with an iron recovery of 82.9 percent and a phosphorus rejection of 93.7 percent. Reoxidation of reduced magnetic concentrates followed by acid treatment gave iron concentrates containing 58.1 percent iron and 0.02 percent phosphorus with 89.6 percent recovery of the iron and 96.5 percent rejection of the phosphorus.

Jan 1, 1973

By Lidia Rangel Roveta

O processo de aciaria da ArcelorMittal Aços Planos América do Sul tem um abastecimento de diário de Cal em torno de 420 ton. O processo de abastecimento deste produto, que consiste da programação, liberação de portaria e descarregamento não estava satisfatório, considerando o tempo de permanência de caminhões na portaria aguardando liberação e consequentemente custos com diárias e alimentação. Visando otimizar este processo, a partir do resultado da analise dos procedimentos de descarga, utilizado atualmente, foi implementado como plano de ação um sistema automatizado de agendamento de descarga de Cal que, após 15 dias de implantação resultou na redução de 66% no custo de pagamento de diária, além de previsão de ganho futuro em frete.

Aug 16, 2017

By G. Taylor

"The Iron Ore Company Of Canada's Carol Project is located in Labrador City, Newfoundland. Labrador City is some 912 air kilometers northeast of Montreal, and 417 ratl kilometers north of Sept-Iles, Quebec.Over 2,800 employees work at the Carol Project to produce some 20.0 million tonnes of concentrate and 10.5 million tonnes of pellets annually.In 1979 our Training Department started to develop the DACUM System of training for our Concentrator Operations Department.DACUM is an individualized, self-learning, training program. It is both a curriculum plan and an evaluation instrument.To date, the DACUM System has been completed for all occupations in the concentrator and work will commence shortly to develop DACUM for our Pellet Plant and Mine Operations Departments."

Jan 1, 1982

Study on Flotation Experiment of Complex Copper-Lead-Zinc Polymetallic Sulfide Ore in High Altitude Area and its Industrial Application

Sep 13, 2010

By Johannes Münzer

Regeneradores são elementos importantes em uma usina siderúrgica. Eles são os responsáveis pelo aquecimento do ar de sopro aplicado no alto-forno a partir do aproveitamento da energia contida nos gases do processo de produção de ferro gusa. Dessa forma, os regeneradores estão diretamente associados ao processo siderúrgico. Durante do seu ciclo de trabalho, o qual se denomina campanha, problemas podem ocorrer devido a variações operacionais indesejadas, falhas de projeto, entre outros fatores. Num ambiente onde o tempo cessante de um equipamento gera enormes custos, a solução é desenvolver soluções customizadas que minimizem essa interrupção. Cada uma das partes do regenerador tem funções únicas e consequentemente soluções únicas, que visam o reparo no estado da arte com menor custo.

Aug 17, 2017

By C. E. Jordan

The Tuscaloosa Metallurgy Research Center of the Bureau of Mines, U.S. Department of the Interior, is investigating the recovery of phosphate from beneficiation slime, as part of the Bureau's efforts to conserve mineral resources through increased use of wastes. Phosphate equivalent to about two-fifths of U.S. production is discarded annually in the wastes. Exploratory flotation tests on the plus 5-um fraction of a slime sample showed promise for a classification-flotation technique. Onsite classification tests at six phosphate washing plants were conducted with a two-stage hydro cyclone system designed to recover the plus 5-um material. The cyclone underflows contained 8.3 to 19.1 percent P2O5, and the recovery of the plus 5-um PZOS values ranged from 81 to 95 percent. The percent P2O5 recovery from the total slimes ranged from 38 to 47 percent. Batch-flotation studies are currently being conducted.

Jan 1, 1978

By E. Martinez

The effect of ultrasonic energy transmitted through a liquid on chrysotile asbestos was investigated. Ultrasonic energy was effective in fiberization of chrysotile crudes as well as standard grades of milled asbestos fibers. Treated samples of several grades of milled fibers had increased wet bulk volumes and decreased settling and filtration rates compared to untreated fibers. Ultrasonics may be a method for fiberization of chrysotile without decreasing length or use of chemical additives that alter surface properties. Cavitation of the liquid on the surface of fiber bundles is believed to be the cause of the fiberization. It was found that ultrasonic energy greatly increased the rate of precipitation of latex on asbestos. When chrysotile asbestos fibers require additional opening or fiberization, the usual method employed is some type of high speed impact or grinding to open the fibers and produce a larger surface area. These methods always cause some degradation in length due to breaking of fibers. In addition, the efficiency of mechanical methods decreases as the diameter of fiber bundles decreases. Chemical methods have been proposed and it is claimed that fiberization down to individual fibers of 200-300 A diam is possible with some wetting agents. However, large amounts of reagent are required, approximately EDWARD MARTINEZ is with Central Research Laboratories, American Smelting and Refining Co., South Plain-field, N.J. TP 63H226. Manuscript, Aug. 12, 1963. Discussion of this paper, submitted in duplicate prior to Mar. 15, 1964, will appear in SME Transactions, September 1964, and AIME Transactions, 1964, vol. 229. 50 pct of the weight of fiber treated, and some of the wetting agent remains on the surface of the chrysotile and cannot be removed by any solvent which does not destroy the asbestos.' This investigation was directed at determining whether ultrasonic energy transmitted through a liquid would be effective in fiberizing chrysotile asbestos. Samples of asbestos crudes and commercially milled fibers were treated; settling and filtration rates of treated and untreated milled fibers were obtained. EQUIPMENT A Westinghouse Corp. ultrasonic cleaning system WEHH was used in this investigation. See Table I for a breakdown of this ultrasonic unit. RESULTS AND DISCUSSION Fiberization of Chrysotile Crudes: Samples of chrysotile crudes were pulled apart with tweezers so that coarse bundles of fiber approximately 1/16 in. in diam were obtained. The bundles were put into a bottle with 200 ml of methanol and the mixture placed into the ultrasonic tank for 30 min at a power output of 1200 w. The test was repeated using water instead of methanol. During the irradiation it was noted that the surfaces of the bundles were being fiberized. The liquid eventually became cloudy with dispersed solids. Fig. 1 is an electron micrograph of the fibers, some reduced to unit dimensions, and a fine material released by the ultrasonic energy. The platy particles in Fig. 1 were identified by electron diffraction and differential thermal analysis as brucite, Mg(OH)2, which must have been intergrown in the chrysotile crudes. Electron micrographs of bulk specimens of chrysotile have shown a fine material filling the interstices between tubular fibers.2,3 Electron diffraction patterns of the fine material collected after ultrasonic treatment indicate that it is amorphous. After decanting the solution, bundles of chrysotile remained somewhat decreased in diameter. Continuing the ultrasonic irradiation of the remaining material resulted in additional fiberization. The opening of the fibers occurred in both methanol and water. Cavitation of the liquid by the ultrasonic energy is undoubtedly responsible for the fiberization. When sound waves are transmitted through a liquid at a

Jan 1, 1963

By Jeff R. Reinson

The Diavik Diamond Mine is producing diamonds from two orebodies, the A154 South and A154 North kimberlite pipes, discovered beneath the waters of Lac de Gras. Innovative dike technology with appropriate water collection and treatment systems allowed Diavik to start open pit mining of the ore bodies in 2002. To allow planning, engineering, and implementation of sufficient water handling infrastructure, reasonably accurate estimates of groundwater inflow quality and quantity over the life of mine are required. Prior to mining, a numerical model using the continuum approach was developed for regional and site wide water management. After approximately two years of mining, groundwater inflows to the pit were found to exceed those predicted by the base case hydrogeologic model. The most likely explanation was flow through Dewey?s Fault zone. As this fault was not explicitly accounted for in the model, a detailed hydrogeologic investigation was conducted to evaluate its geometry and hydraulic properties. A multi-disciplined approach was used and involved core logging, fluid logging, geophysical logging, packer testing, a pumping test, and water quality sample collection. The results of the field investigation were used to update the conceptual and numerical models and to develop a Discrete Fracture Network (DFN) model to address small scale problems such as flow into future underground drifts. The updated numerical hydrogeologic models predict that up to 70 per cent of the groundwater inflow to the A154 N/S open pit is through the relatively narrow fractured rock zone associated with Dewey?s Fault. Consistent with the continuum model, the DFN model predicts that inflow to a drift excavated in Dewey?s Fault will be approximately 10 times the inflow to a drift excavated in competent rock. The DFN model provides a better understanding of the distribution of these inflows on a local scale over the length of the drift.

May 1, 2006