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By Roorda H. J, R. R. Saddington, Curlook W

THE copper-nickel sulfide ore deposits of the International Nickel Company of Canada, Limited contain the minerals pyrrhotite, pentlandite, and chalcopyrite. In the extraction of the nickel, copper, and iron, much of the processing involves oxidation of the metals as well as sulfur. Roasting plays a predominant role at several stages in the operations which prepare the constituent metals for refining. Copper, nickel and iron concentrates of various grades, ranging from low-grade nickeliferous pyrrhotite to high-grade nickel sulfide, must be partially or completely oxidized. Figure 1 shows the main points at which roasting is conducted at INCO. Roasting experience at INCO dates back to the time when lump ore was partially roasted in heaps. It has progressed through single hearth roasters, sinter machines, multiple-hearth roasters, flash roasters, and more recently has centered on the development and utilization of fluid bed roasters. The primitive, slow, and inefficient method of heap

Jan 1, 1961

By Dorsey Hager

THE rapid increase of water troubles in the Mid-Continent oil fields is causing much alarm. Troubles occur at Towanda, Eldorado, Augusta, Cushing, Blackwell, and Healdton, although they had, not been acute in the Mid-Continent field until about two years ago, when the unusual conditions in the deeper oil fields were first encountered. California faced the same situation, but, thanks to aggressive measures, has largely overcome the dangers. The following analysis of water trouble may throw some light on the subject and be of assistance in solving the problems involved. WATER TROUBLES CLASSIFIED The presence of water in large quantities in oil sands has the following results: 1. Diminishes oil production. 2. Diminishes casing-head gasoline production: (a) By curtailing the gas flow. (b) By making the use of vacuum pumps unsuccessful. 3. Increases lifting costs: (a) By making it necessary to pump large quantities of water, which requires. a fast motion and long stroke (third hole). (b) By requiring the use of compressors for air lift. (c) By causing break-downs and delays due to the high speed necessary to pump water. (d) By making it necessary to treat "cut" or emulsified oil. Oil production is seriously curtailed by the presence of large quantities of water. Lease records show that wells are shut down 40 to 60 per cent. of the pumping time where serious water trouble occurs. While a small quantity of salt water may cut the paraffine and keep the oil moving, several hundred feet, or a hole full of water, effectually "kills" the oil

Jan 10, 1918

By Charles Austin

IT has long been known that plain high-carbon steels may be susceptible to graphiti-zation below the A, critical, but no data have been available to indicate what factors cause and tend to inhibit graphite formation. Two recent publications1,2 have shown that the factors controlling graphitization below the A, are different from those operating above the A, inversion where commercial graphitization of malleable iron begins. Furthermore, for plain high-carbon steels graphitization below the critical point does not appear to be related to ordinary chemi-cal analyses. Many years ago it was recorded' that the rate of graphitization at subeutectoid tem-perature is not a maximum just below the A, critical, but at some lower temperature, which Austin and Norris have shown to be about 670°C. Indeed, work done in our laboratory has demonstrated that it is im-possible to spheroidize certain steels in the temperature range of 650° to 710°C. with-out the formation of considerable amounts of graphite. However, if the temperature is maintained just below the A, (720°°C,) these same steels may be completely sphe-roidized at constant temperature. In previous studies1,2,4 on 1 per cent plain carbon steels graphitization was en-countered during prolonged tempering. The limited number of steels studied did not provide sufficient data to permit adequate study of the factors controlling this graphi-tization. Accordingly, a limited statistical investigation was undertaken, utilizing 18 steels of similar chemical analyses, fur-nished by four steel companies, who also supplied information regarding the history of manufacture.

Jan 1, 1940

By Robert L. Hoss

The application of Muskat's differential equations for predicting the performance of a solution gas-drive reservoir to the Fullerton field indicates that a recovery may be expected of 14,030 bbl per acre under primary depletion, and 15,910 and I7,190 bbl per acre, respectively, under the two pressure-maintenance programs analyzed. In this analysis it is assumed that fluid properties are the same throughout the reservoir, that the core data used are typical of the Clear Fork limestone in the locality, and that injected gas is completely diffused through the pay zones. The economic study of the three recovery programs considered indicates that the one in which 60 pct of the produced gas is returned to the formation is the most profitable. Introduction The purpose of this paper is to consider the effect of pressure maintenance by gas injection on the ultimate recovery of oil from a solution gas-drive reservoir. This prediction of reservoir behavior is the result of calculations based on the equations presented by M. Muskat in the Journal of Applied Physics, March 1945. Reservoir The reservoir analyzed is the Fullerton field in Andrews County, West Texas. It is situated on a broad anticlinal structure with approximately 330 ft of closure, and extends approximately eight miles north and south and five miles east and west. The areal extent is taken as 16,642 acres. The producing horizon is the Lower Clear Fork limestone of Permian age, occurring at depths from 6650 to 7350 ft. It is divided into four zones. For the purposes of this study, the fluid characteristics in all zones are assumed to be the same. Therefore an equivalent zone is assumed of thickness equal to the sum of the thicknesses of the four zones, or an average of 216 ft. The reservoir contains 3,586,991 acre feet of producing limestone, with an initial volume of stock tank oil in place of 918,-403,100 bbl. The average connate water saturation is 24.0 pct. The permeability ranges from 6.7 md. to 12.6 md., and the porosity ranges from 7.7 pct to 11.4 pct, except for occasional cavernous streaks. Based on these values, the limestone may be considered intergranu1ar.l Production histories and material-balance studies have indicated that the driving mechanism is solution gas. Water levels have been established. Theory It is possible to express mathematically the change in residual oil saturation with pressure decline in a solution gas-drive reservoir as being equal to the change in the physical properties of the fluids present in the reservoir as this pressure decline occurs. Essentially these equations, in differential form as presented by M. Muskat,2 express quantitatively the instantaneous net effect

Jan 1, 1948

Large GDP increases in the Pacific Rim countries have been accompanied by similarly large increases in demand for oil products. In the case of residual fuels, this demand has been tempered by the substitution of other energy products such as coal or gas.In the region's developing and newly industrialised nations, it has not been possible to make the very large investements in infrastructure which allow other energy sources to be used for transportation. As a result, GDP growth has been mirrored in the demand growth for automotive fuels. Other non-sustitutable products such as lubricants have also benefitted by the region's GDP growth.The combination of a number of years of sustained growth, coupled with increasing quality requirements is now stretching the upgrading capacity of the region's refineries. If, as seems likely, the region continues to enjoy a high GDP growth rate, then this will be accompanied by increasing reliance on finished products coming out of the Middle East. The owners of the most simple form of refinery in which crude is simply distilled and the naphtha reformed into petrol will face major capital investments. If they decide not to bear this cost, they will face increasing problems in selling their surplus residual fuel oil at an economic price. Quality will become an increasingly important issue. Not only in the well publicised areas such as unleaded petrol, but also for products such as lubricants which play a major role in the efficiency of modem equipment. Quality of service such as hours of opening, ease of access, and service station facilities will also become increasingly important as the oil companies use these to attract customers and gain brand differentiation.

Jan 1, 1990

By Thomas Egleston

The uncertainty of finding the exact equivalents fortechnical expressions in different languages has led me to think that a glossary of furnace-terms would be useful to members of the profession. I was led, some years ago, to prepare a small one, which has been found so very useful, that I have arranged one for presentation to the Institute, for four different 'types of furnaces, in the hope that it may prove of use to those who are in the habit of consulting foreign technical journals, I was further induced to make the attempt in the hope that it might tend to make the terminology less complicated than it now is, and also to make it more uniform over larger districts. The idea of referring to a drawing which expresses exactly what is meant, resulted from the necessity of presenting such subjects to students, and will, it is hoped, prove much more useful than the mere dictionary arrangement in alphabetical order. The drawing of the blast-furnace was prepared for me by Mr. J. P. Witherow, of Pitsburgh ; the drawing of the open-hearth furnace by Mr. S. T. Wellman, of Cleveland, and the reverberatory furnace by Mr. John Fritz, of Bethlehem. The bloomary-furnace is taken from my own paper* on Bloomaries, but, in order to have a complete furnace, I have introduced into the drawing of those used at Saranac the guard-plate used at Ironville. The interest which has been taken in the preparation of this paper by those gentlemen who have contributed the drawings, has been supplemented by gentlemen in Europe who have taken the trouble to read the proof. In France it has been read by Mr. Lodin, of the School of Mines, and by Mr. Chaper, of Paris, and in Germany by Dr. Wedding, of Berlin, and Mr. Luhrman, of Osnabruck. The preparation of the paper has been much more difficult than was anticipated, and its value has been very much enhanced by Dr. Raymond's kind assistance and cooperation; and to him, as well as to all the other gentlemen, Iam very much indebted. It was at first proposed to add to the paper the names of all the tools used in these various furnaces. It was found, however, that this would make such

Jan 1, 1888

By Blandine Arseneault

The Raglan Mill had been in production for less than a year when the initial toxicity tests on the effluent revealed that it was defined as ?toxic? under regulations. Testwork was begun to address the fundamental reasons for the toxicity and a systematic approach was initiated to identify causes. Elimination of the problem presented a challenge once the main conclusion identified high dissolved solids as the principal culprit. In particular, normally benign soda ash (sodium bicarbonate) reagent additions used in milling, was identified as the main contributor to the problem. Following analysis of all requirements and safety considerations, a concept to recycle 100% of the mill process water was pursued. In addition to meeting regulatory requirements, this project would have numerous positive benefits to the operation, including reducing fresh water consumption and lowering costs.

Nov 1, 2002

By L. S. Darken

THE manufacture and treatment of metals comprises operations whose effectiveness depends in large measure upon diffusion phenomena. The significance of such phenomena has, for a few simple cases, long been understood, but in more complex cases it has not been adequately recognized. This paper presents a mathematical analysis of some of the cases in which diffusion leads to the formation of a new phase within the metal, and this analysis provides a basis for interpreting quantitatively many apparently diverse experimental observations recorded in the literature, some of which are outlined in the following pages. OBSERVATIONS RECORDED IN LITERATURE An outstanding instance is the general type of phenomenon in which diffusion of an element into an alloy is followed by a phase change, which most frequently is a reaction (precipitation) of the diffusing element with one or more components of the alloy to form a compound. Thus in certain alloys heated in contact with oxygen not only the usual oxide scale appears but, in addition, beneath the surface, a well-defined zone in which free oxide particles are dispersed with notable uniformity. This zone, commonly referred to as the subscale or zone of internal oxidation, is remarkable in that the visible boundary between it and the unaltered metal is usually sharp. Such a subscale, which appears to have been recognized first in oxidized copper alloys, has been described and studied by C. S. Smith,1 by Rhines,2 and by Rhines, Johnson and Anderson;3 but it appears also in other alloys when they are exposed to conditions that bring about the precipitation of some compound, not necessarily an oxide. Another clear case of this same kind is the diffusion of carbon into a steel containing an element such as molybdenum, chromium, vanadium or tungsten, whose carbide is less soluble in iron than iron carbide, the result being that some part of that element is precipitated as a dispersed carbide. A similar phenomenon may occur on the welding of two alloys each of which contains one of a pair of elements that react to form a compound or a new phase of any sort. But in addition to the precipitation of a compound formed from the diffusing element, other effects may result merely from the presence of the diffusing element. For instance, if homogeneous austenite, nearly saturated with respect to carbon, is heated in contact with silicon in the absence of oxygen, one would expect to find, behind the several iron-silicon phases analogous to a scale, a zone of austenite containing dispersed carbide, because of the fact that silicon decreases the solubility of carbon in iron. As still another example, oxidation of an alloy may result in diffusion toward the surface of one or more of the constituents; for instance, during oxidation of a steel containing an element such as copper, which is less prone to oxidation than iron, there is a notable enrichment of copper just beneath the scale-metal interface. As an example of a yet more

Jan 1, 1942

By W Farnworth, D Fergusson

Estimation of productivity is a key factor in the design of hydraulic mines and in assessing their economic feasibility. A published Russian formula for hydraulic mining monitor cutting rates overstated productivity by up to 2 tonnes per minute (251%) when applied to Solid EnergyÆs hydraulic mines. A new formula, taking into account additional productivity factors, was derived by Solid Energy and produced an acceptable correlation between predicted and actual cutting rates inNew Zealand and overseas hydraulic mines, with an average error of approximately 0.1 tonnes per minute.   Another key factor in hydraulic mine design is the transport of coal slurry via flumes. Solid Energy carried out a series of 80 full scale tests in a surface flume installation, varying the gradient and coal:water ratio. Both steel flumes and plastic-lined flumes were evaluated. A modification of the Chezy Open Channel Flow formula, including a factor for slurry density, gave a reasonable correlation between actual and predicted flows. It is believed that this Solid Energy formula is suitable for the design of flume installations for hydraulic mining.

Jan 1, 2004

By R. J. Wygal, J. Naar

An equation for three-phase (water, oil, gas) imbibition oil permeability is developed, assuming the water to be the dominant wetting fluid. Oil isoperms are obtained for consolidated sandstones characterized by 1/pc2 = CS*. The evolution of an oil-gas system imbibing water from Swi to(Sw,imb )max is shown to proceed along a line of constant oil saturation with increasing oil permeability and decreasing gas saturation. When the gas satuation cannot be reduced further, the system evolves along a line of constant Sg with decreasing oil saturation and permeability. The initial gas saturation is shown to reduce markedly the effect of complete wetting by either oil or water on flow performance. INTRODUCTION Imbibition oil isoperms are required for performance prediction when a well is producing water, oil and gas. This situation occurs in multiphase displacements such as underground combustion, steam injection and the water flooding of highly depleted reservoirs. In a recent paper,1 a model was presented for the prediction of two-phase imbibition characteristics. This paper extends the imbibition model to the case of three phases by assuming that the water is the dominant wetting fluid. The following results were obtained from the model: (1) an analytical expression of oil isoperms; (2) oil isoperrns as functions of reduced water, oil and gas saturations, valid for all sandstones having a capillary pressure curve which can be approximated by 1/PC = CS*; and (3) evaluation of the three-phase flow performance as dictated by complete wetting by either oil or water. The agreement between predicted and observed oil recovery in the presence of a gas phase, reported in Ref. 1, is a partial support for the present development. However, experimental data are not available at this time to check fully the model predictions. Perhaps this paper will stimulate the collection of such data. The imbibition model of a porous medium has been described previously, and the reader is referred to the paper of Naar and Henderson1 for details. In brief, the model is formed by the random interconnection of straight capillaries, with a provision for the blocking of the non-wetting phase by the invading wetting fluid. The following expressions were derived from the model. 1. The amount of oil blocked by the invading water is

By J. I. Mathis

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

Jan 1, 2004

By Victor Benavente

La lixiviación es un proceso hidrometalúrgico que permite obtener el cobre de los minerales que lo contienen, aplicando una disolución de ácido sulfúrico, agua y agentes oxidantes. Este proceso consiste en que los minerales son sensibles al ataque de soluciones ácidas y oxidantes. En ese sentido, el objetivo del texto fue determinar la respuesta de los sulfuros secundarios de cobre a la lixiviación ácida y oxidante utilizando cloruro de sodio como portador de cloruro al sistema de lixiviación. El desarrollo de las pruebas y la ejecución de las mismas, definiió el proceso de lixiviación para minerales sulfurados de Minera Pampa de Cobre.

Sep 12, 2011

By Ernst-Ulrich Reuther, Alexander Donmen

Mine ventilation in the German coal mining industry is concerned mainly with problems of thermal environment arising from greater depths and with increasing emission of methane gas. The development of computer techniques over the past ten years for solving these and ancillary problems is reviewed. The emphasis from a planning and control point of view falls mainly on ventilation network calculations, temperature predictions and advance estimates of methane emission.

Jan 1, 2014

By Christopher Riley

A relatively unexplored lead zinc deposit lies about 12 miles northwest of Revelstoke, B.C., in the highly metamorphosed Monashee Group of rocks of the Shuswap Terrane, Precambrian in age. Host rocks are of sedimentary origin and consist of gneisses, schists, marbles and quartzites with intermediary types. The marbles and quartzites provide good horizon markers. Using these it is possible to interpret the controlling structure which is a syncline overturned to the north, dipping south at about 45°, and plunging east at about 12°. The syncline is truncated at about halfway of its length on a peak on the west side of which a partial cross section together with superimposed minor folds may be seen. The quartzites and the two marble beds may be traced over much of the structure. There are two lodes, above the marble and below the quartzite, which converge eastward and which are the exposed edges of the same host bed -an impure limestone.

Jan 1, 1961

amounted to about 2000 metric tons. The total output is increasing from year to year. Marine salt is now produced in Haiti in quantity sufficient to supply nearly all the requirements of this Republic, so production tax is now collected. Central America Guatemala-The major production of salt in Guatemala is solar salt derived from sea water, but the Indian population prefers salt derived by boiling coastal marine earth. Salt is taxed by the Government. The industry has been beset by controversies in recent years, especially following the revolution of October 1944. The Government issued a decree in August 1940 designed to control production and price of salt. The creation of a salt consortium was provided for and marketing was to be governed by production quotas. It is understood that the Government pool was later dissolved and the industry is now under older laws whereby production and sales have no limits. South America Panama-Output of salt in Panama in a very recent year was 11,000 net tons of solar-evaporated sea salt. A Government bank is in charge of output and distribution of the product. Colombia-Rock-salt deposits are known in five places-Zipaquira, Nemocon, and Sesquile, in the Department of Cundinamarca, the Cumural y Upin near Restrepo, and San Miguel y Barital, near Medina in Meta Intendency. The latter deposit never has been worked on account of its inaccessibility. Saline springs are worked in four locations. The largest producer among marine salinas is Manare but it is now planned to make Bahia Honda the largest. Some evaporated salt is made in vacuum pans. The deposits at Zipaquira, Nemocon, and Sesquile are believed to occur in the domal type of deposit. All the salt resources are under Government control. Venezuela-The salt industry in Venezuela is under Government control and is taxed. Taxes in recent years, however, have been reduced for salt used in curing hides and salting meats, fish and fish products. Production has approximated 25,000 metric tons yearly but may now be considerably above that figure. The basin on the peninsula of Araya, State of Sucre, which at present is the only important source of salt, could produce at least 175,000 metric tons if more ground were provided-a larger supply than the entire country could consume. This unique landlocked basin of nearly 1000 acres lies 12 ft below sea level. Ecuador-Salt is a Government monopoly in Ecuador and is produced chiefly by solar evaporation close to the shore. The main producing center is on the Santa Elena peninsula, which supplies about 90 pct of the salt. Small fields are at Punta Arenas, Payana, and Chara-

Jan 1, 1949

Temperature Sensitive Polymers as Efficient and Selective Flotation Collectors

Sep 13, 2010

By D. W. Levinson, L. E. Tanner

DURING the course of an investigation of the zirconium-iron-tin system the zirconium-iron system was reexamined up to 55 pct* Fe. The alloys pre- visible melting3 and X-ray diffraction studies were made of samples of the alloys. The ferromagnetic properties of ZrFe2were determined by Professor P. W. Selwood* using a modified Faraday balance.4 The zirconium-rich portion of the phase diagram is presented in Fig. 1 and compared with the work of Hayes et al.1 The maximum solubility of iron in ß is somewhat decreased while the eutectic temperature is raised. There seemed to be no change in the eutectic composition of 16 pct Fe. Since the base material was so low in iron content, it was possible to establish the maximum solubility in a between 0.017 and 0.025 pct Fe at the eutectoid temperature. The observation of fine ZrFe, particles in the micro structure of a specimen of 0.012 pct Fe alloy quenched from 700°C indicated that the solubility drops below this composition at 700° C and lower. Further study was made of the intermediate phase ZrFe2. wallbaum5 identified the compound initially as ZrFe2 with a C 15 (MgCu2) structure, placing it at 55 pct Fe stoichiometrically. Hayes et al.1 believed they found the phase at about 47.2 pct Fe and called it Zr2Fe3 but reverted to ZrFe, in the discussion of their paper.6 Jordan and Duwez7 confirmed Wallbaum's work as well as finding the same single-phase structure to about 62.3 pct Fe or Zr0-61 Fe2-18. In order to establish the ternary phase relations in the zirconium-iron-tin systema the exact position of this phase had to be known. This was accomplished by X-ray diffraction, visible melting, and metallographic techniques. Elliott8 obtained a single-phase ZrFe2 X-ray diffraction pattern from an alloy of about 55 pct Fe. This was confirmed in the present study with an alloy of 54.81 pct Fe. However, extra lines (attributable to a or ß zirconium) were found in diffraction patterns of the 47.42 and 49.83 pct Fe alloys. The melting characteristics of these same alloys were studied by suspending 47.42, 49.83, and 54.81 pct

Jan 1, 1960

By Jr. Watts

The American Mining Congress and the U.S. Bureau of Mines have formed a collaborative research team to develop, implement, and evaluate a comprehensive control strategy to reduce diesel particulate matter concentrations without degrading other air quality parameters at an underground noncoal mine. Other participating organizations include Caterpillar, Inc., the Mine Safety and Health Administration, and the University of Minnesota. After extensive baseline information and air quality data are collected, available control strategies to reduce diesel particulate matter exposures will be implemented, individually or in combination, and evaluated. This paper discusses the objectives and protocol of the collaborative effort to evaluate diesel particulate control technology.

Jan 1, 1995

By D. M. Wyslouzil

"Micron or sub-micron size gold inclusions in sulphide minerals cannot be extracted by conventional cyanidation. The gold surfaces must first be exposed by decomposition of the sulphides. As an alternative to roasting, pressure oxidation was found to be a most satisfactory method to decompose the sulphides and expose the gold particles. For cyanidation the pressure oxidation pulp has to be neutralized and stabilized with lime. It was found that thiourea can extract the gold directly from the pressure oxidation pulp without pH adjustment and oxidant addition. The main obstacles against the common use of thiourea are circumvented by a recently described control method of the emf during leaching.INTRODUCTION Amalgamation and cyanidation are the most conventional processes for gold extraction. The prerequisite for gold extraction is the possibility of gold surface to be contacted by mercury or by the cyanide solution. Encapsulated gold has little chance of contact and this leads to poor extractions.The reasons why a gold ore may be refractory are: micron or sub-micron size gold particles included in the sulphide minerals, such as pyrite and arsenopyrite; presence of and association with antimony, arsenic, tellurium and carbonaceous minerals. Some alternative processes, such as double oxidation(1,2), pretreatment with lime , H202, chlorine and Caro's acid, roasting and thiourea leach, have solved some of the problems of ""refractory"", but the sub-micron gold in sulphide minerals still shows little response. Roasting and the cyanidation of the calcine was one of the most successful approaches for this type of gold ore.There are two disadvantages to the roasting process: (1) the generation of sulphur, arsenic, antimony and mercury containing gases is undesirable and the control is extremely expensive; (2) gold particles might be fused in the roasted product and the oxidized base metals in the calcine might reduce the cyanidation efficiency. In recent years the pressure oxidation process has been considered as one of the more effective and satisfactory methods to decompose the sulphide minerals and expose the gold surface to the cyanide leach solution. The pollution problem could be better controlled and the gold extraction is more amenable."

Jan 1, 1985

By Nadia C. Miller

In situ metals research to characterize the hydrology of a fractured crystalline rock mass in under-ground mine stopes is discussed. The objective of this study was to find the potential direction, velocity, and concentrations of a lixiviant plume, should leaching solvents (lixiviants) escape from a test stope. The study was conducted by the U.S. Bureau of Mines at the Colorado School of Mines Experimental Mine in Idaho Springs, CO. Since this was a method evaluation site, the lixiviant was simulated using water and acceptable tracers. The site is located in moderately fractured Precambrian migmatite-biotite gneisses of the Idaho Springs Formation. The data required for the characterization were obtained from geologic maps and reports, core logs, and air and water permeability tests. The acquired data were analyzed and applied to a computer model that calculated' the characteristics of a lixiviant plume originating at the stope. A sensitivity analysis showed that dispersivity, ground water velocity, fracture porosity, and fracture spacing had notable effects on the concentration of the plume. Assuming a saturated rock mass, the lixiviant plume would disperse to undetectable levels in a very short time because of a high fracture density at the mine site.

Jan 1, 2010