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By E. E. Thurlow

The Geology Div. of Northern Pacific Railway Co. has adapted to its exploration efforts field procedures for geochemical sampling and semi-quantitative analysis which have been developed through research by the U. S. Geological Survey. The sampling is done in conjunction with reconnaissance geologic mapping on aerial photographs or during field checking of maps which have been prepared largely by photo-geologic interpretation. Stream sediment or soil samples are taken and readily soluble combined heavy metals are extracted with ammonium citrate followed by colorimetric titration with dithizone at the sample site. The effectiveness of this approach has been demonstrated both in positive and negative results, thereby assisting in the elimination of large areas of land from further immediate attention and in providing targets for followup exploration. An occa sional sample is submitted for spectrographic analysis as a check on the possible presence of other elements of economic significance. Field laboratory procedures are also being implemented for determining molybdenum, mercury, and other metals which may be valuable in themselves or useful as pathfinder elements in outlining mineralized areas. A lead-zinc occurrence in Oregon and a copper deposit in Montana were readily detected and outlined by stream sediment and soil sampling and a heavy metal anomaly that lacks obvious interpretation has been found in northwestern Montana. Detailed mapping and additional sampling are followed by other exploration techniques if warranted. Northern Pacific's program of reconnaissance mineral evaluation of company-owned lands and adjoining areas was outlined in a paper presented at the American Mining Congress meeting in Las Vegas four years ago. That report included policies and procedures with respect to mineral development on Railway Co. lands and may be referred to for information on these matters.1 In a sense this paper is a progress report on the use of geochemical prospecting in Northern Pacific's continuing mineral evaluation program. At this time there are positive results but as yet there is no real success story in the form of a minable ore body. GEOCHEMICAL PROSPECTING PROCEDURES The decision to use geochemistry as a reconnaissance exploration tool must be followed by research into sampling and analytical methods and into the interpretation of results. Various analytical methods were tried and evaluated by the Geology Div., including hot and cold acid extraction with and without fusion of the sample, panning and magnetic separation followed by dithizone testing of the magnetite, and cold aqueous extraction of metallic ions followed by indicator tests. Samples were first sent to the laboratory for analysis; later field laboratories were established and now virtually all testing is done at the sample site. It was concluded that, where applicable, the quickest dependable methods for reconnaissance use are the dithizone field tests for readily extractable heavy metals. This involves the simultaneous treatment of a sample, usually of soil or stream sediment, with two immiscible liquids; one a cold aqueous extractant (ammonium citrate) and the other a solution of dithizone in toluene or xylene.2 Dithizone is a colorimetric indicator that reacts quantitatively with copper, lead, zinc, and several other metals to form colored complexes in organic solvents. Results may be expressed in ml of 0.001 pct dithizone that are required to reach the blue end point, or calibration of the test results can be carried out with standard solutions of zinc; conversion factors would then be expressed in ppm, zinc equivalent. Calibration of dithizone solution with zinc standards indicates that 1 ml of 0.001 pct dithizone is equivalent to approximately 0.25 ppm of zinc. An authoritative report on dithizone field tests authored by H. E. Hawkes in the June-July 1963 issue of Economic Geology* states "The appeal of these techniques has been the simplicity and speed of the determinations as compared with more tedious laboratory determinations of trace metals in weathered rocks, soils, or plant materials. This obvious appeal, however, has often been more than matched by misuse of the method in such a manner that the results are

Jan 1, 1964

By A. D. Mutch

IT has long been known that there are wide variations in the thermo-electric potential of pyrite. In the last few years a study of this variation and other properties of pyrite was carried out at the University of Toronto by F. G. Smith on specimens of pyrite from many localities.1-3 As a result of these studies the pyrite geothermometer was developed by Professor Smith. The calibration of the pyrite geothermometer is based on the assumption that "crystals of any one electronically conducting mineral species deposited at a high temperature have a more positive thermo-electric potential than crystals deposited at a low temperature, and the thermo-electric potential varies continuously between any given limits of the temperature of deposition." The cause of the variation was postulated to be crystal discontinuities, such as lineage boundaries. As yet this postulated relationship has not been established as fact. On theoretical grounds it is indicated that the thermo-electric potential of pyrite or any other partial conductor is dependent upon a number of factors as well as the temperature of formation. For this and other reasons there is ground for doubt as to the validity of the relationship postulated above. To date a large number of readings have been made with the pyrite geothermometer which have been recorded in terms of the calibration of the instrument in degrees centigrade. So far most of the pyrite tested by this technique has been in association with gold ore. The values for the temperature of formation obtained in these tests appear to be reasonable and, in relation to geological problems, to vary in the right sense. Determinations on some specimens not in association with gold ore have given readings that appear to be much too high, taking into account the probable maximum temperature of the host rock. To sum up, although many determinations made with the. pyrite geothermometer appear to give reasonable values for the temperature of formation of the pyrite, there are at the same time other readings which seem anomalous. On the basis of an examination of available results of work with the pyrite geothermometer, two problems must be considered: 1-the validity of the calibration of the pyrite geothermometer; and 2-the nature of the distribution of the thermo-electric potentials of pyrite in relation to the specific problems that have been examined. In this paper the academic problem relating to the validity of the calibration of the pyrite geothermometer will not be discussed. Instead, the variations of thermo-electric potential of pyrite in association with gold veins will be discussed with regard to specific examinations. The first of these two examinations deals with the distribution of thermo-electric potentials of pyrite in association with a gold vein and was carried out in the McIntyre Porcupine Mine, Schumacher, Ont., in the summer of 1949 as part of a study with this technique. The second problem deals with variations of thermo-electric potential of pyrite in gold ore specimens from all over the world. The specimens used in this study were part of the private collection of Frank Ebbutt, geologist for Howe Sound Exploration Co. Results of Detailed and Reconnaissance Studies In discussion of the results of determinations made in these two studies the values of thermo-electric potential in millivolts will be used. It will be noted that in some of the diagrams the determinations are recorded in terms of pyrite geothermometer temperatures. Fig. 1 is a calibration chart relating, pyrite geothermometer temperatures and thermo-electric potentials. A full discussion of the technique is given in the original paper by F. G. Smith.' Briefly, the determinations are made by placing two stainless steel probes, one hot and the other cold, against the surface of the pyrite crystal being tested. The thermo-electric potential that is developed is read with a null-point potentiometer that is calibrated in what

Jan 1, 1952

By R. F. Holub, E. Franco, T. B. Borak, K. J. Schiager

INTRODUCTION According to a recent analysis by Schiager et al.(1981), inhalation of radon daughters continues to contribute the largest risk from exposure to radioactive materials in underground uranium mines. The American National Standards Institute (1973) has published a concensus standard for radiation protection in uranium mines. According to this standard, a monitoring system for radon daughters must be capable of measuring the annual accumulated exposure in working level months within an uncertainty interval of 50% at the 95% confidence level. To satisfy this criterion, uranium mining companies in the USA have adopted a procedure consisting of single or periodic measurements of the air concentration of radon daughters. All of the measurement methods sample a known volume of air through a filter. After a specified delay interval, the filter is analyzed for radioactivity. The exposure rate from total airborne potential alpha energy in units of working level (WL) is estimated from the measured activity on the filter. For control purposes, this measurement establishes whether or not a work area is safe for occupancy by miners. For routine dosimetry, the concentration estimated from the grab sample is assigned to the appropriate work area. It is then assumed that the concentration of radon progeny is equal to the average of the two measurements at the beginning and end of the specified interval. Meanwhile, the work locations and exposure times of each miner are recorded on the daily time card and verified by the shift supervisor. Most cards provide space for 15-minute time intervals. The exposure in working-level hours (WL-hr) for each shift is obtained by summing the time spent in a given location multiplied by the exposure rate (WL) assigned to that location.The exposure of an individual miner to radon progeny is summarized on a weekly basis and commonly reviewed each month. These values are then accumulated in units of working level- months (WLM) during the calendar year. EVALUATION TECHNIQUE AND RESULTS The evaluation of grab sampling methods for monitoring exposure to radon progeny is presented in two sections. The first section examines each method individually according to accuracy, precision, and uncertainties attributed to human errors. The second section includes an analysis of procedures which are common to all measurement methods. The ultimate goal is to determine whether a specific measurement method, or grab sampling in general, can fulfill the criterion that the annual accumulated exposure of each miner be known to within ± 50% at the 95% confidence level. In addition it is essential that the above criterion be satisfied at an acceptable cost to the mining company. The results of each testing procedure are presented in terms of the contribution of the relative uncertainty in the estimates of cumulative WLM. Each of these are then combined to form a figure of merit for the complete monitoring system. The method of combining statistical uncertainties and interpretation of the results is subject to some debate. However, since all of the tested parameters enter into the final computation of WLM multiplicatively, we have used the commonly accepted procedure of combining the squares of the relative uncertainties. We have also assumed that each of the uncertainties is derived from independent random variables and the covariance of any two variables is zero. A description of each grab sampling measuring method is given in Table 1. Also included is the equation used to compute WL from the measured quantities. Accuracy (U A) Our definition of accuracy is based on the uncertainty inherent in any method which attempts to estimate potential alpha energy without unambiguously determining the concentration of the three unknown radioisotopes, RaA, RaB and RaC. (For simplicity, the RaC and RaC' nuclides are referred to in combination as RaC.) The inherent uncertainty strongly depends on the mixture of these three components at the time of measurement.

Jan 1, 1981

By H. Sakurai, M. Kato, F. Tanaka

The Mitsubishi Continuous Copper Smelting/Converting Process employs an electric furnace (CL- furnace) for settling the slag/matte mixture formed in the smelting furnace. The conditions in the CL- furnace change its settling efficiency, resulting in high variability of copper losses in slag. Modifications of the operation and maintenance procedures for the CL-furnace have significantly and sustainably reduced the copper losses in Gresik smelter to below 0.7%. A series of flow patterns evaluation in the CL-furnace demonstrated how the chemical reactions and settling conditions of the CL-furnace has been improved by the new operating procedures. Settling mechanisms for the matte droplets in the CL-furnace is also discussed using image analysis of solidified slag. INTRODUCTION The Mitsubishi Continuous Copper Smelting/Converting Process employs an electric furnace (CL- furnace) for settling the slag/matte mixture formed in the smelting furnace. Since the top-blowing in the S- furnace agitates the molten bath strongly, matte droplets are dispersed over the slag phase when melts flow out of the S-furnace. Thus, the CL-furnace has an important role to settle and recover matte droplets efficiently. Since many papers have ascribed major part of copper losses to matte droplets suspended in slag (Tanaka 2007; Genevski et al., 2008; Starodub et al., 2016), flow patterns of slag in the CL-furnace can affect greatly on the profitability of smelters which have adopted the Mitsubishi process. PROCESS DESCRIPTION Figure 1 illustrates the Mitsubishi process schematically. The Mitsubishi process is the only system for continuous production of blister copper from copper concentrates and consists of 3 furnaces connected by enclosed launders those ensure the minimum emission of fugitives. In a smelting furnace (S-furnace) copper concentrates are fed with flux, oxygen-enriched air to form a mixture of slag and matte which cascades down to a slag-cleaning furnace (CL-furnace). The CL-furnace settle matte droplets in the mixture on the crucible from which matte is siphoned to a converting furnace (C-furnace), while discharging the cleaned slag (CL-slag). The C-furnace converts matte to blister copper by the top-blowing of oxygen- enriched air.

Jan 1, 2019

By J. J. Mulligan

Introduction Coal is found in every major geographic region through-out Alaska and in two offshore areas. Since about 1852, more than 100 small mines have opened and closed. In 1981 and 1982 production was almost entirely from one mine in central Alaska. Clearly, the utilization of Alaska's abundant coal resources presents political, economic, and technical problems that are far from solution. Location and Physical Features Figure 1 illustrates the geographical and geological similarity between Alaska and the western US. Alaska's Arctic region generally resembles Wyoming and the Dakotas. The Brooks Range is an extension of the Rocky Mountains. The central region of Alaska between the Brooks Range and the Alaska Range bears a general resemblance to the basin and range country of the western US. The southcentral and southeastern regions have a similar resemblance to the Sierra Nevadas and the West Coast. The Arctic, the central, and the southcentral regions have major coal fields. The southeast region has scattered occurrences. The topographic, climatic, and economic characteristics of each are different. These differences have a large effect on practical mining methods. Description of Alaskan Coal Coal deposits known in Alaska are almost all of Cretaceous or Tertiary age, much younger than the Carboniferous coal deposits of eastern and midwestern states. Consequently, most Alaskan coals have a higher moisture content and a lower heat value. Most Alaskan coals also have a much lower sulfur content. Low volatile bituminous, and anthracite coals occur in Alaska, but most Alaskan coals range downward in rank from high volatile bituminous to subbituminous and lignite. Alaskan coals are similar to coals of the northern Great Plains and the Rocky Mountains. Arctic Region Northern Alaska Coal Fields Northern Alaska coal fields are by far the largest group of coal deposits in Alaska (Fig. 2). Coal-bearing rocks extend from the foothills of the Brooks Range about 160 km (100 miles) northward to within about 80 km (50 miles) of the Arctic coast. The principal known occurrences are between the Colville River and the western coast. However, coal has been found eastward almost to the Canning River and westward under the Arctic Ocean. The northern Alaska coal fields are in a series of Cretaceous rocks that suggest a deltaic depositional environment. The beds tend to occur in series of up to eight or nine beds totaling 6-9 m (20-30 ft) of coal. However, beds 6-12 m (20-40 ft) thick have been reported, and beds 1-3 m (3-10 ft) thick seem to be relatively common. Including thin seams, coal in some places makes up about 10% of the stratigraphic section. However, no area has been explored in sufficient detail to block out any large body of reserves or to make reliable estimates of the total resource. Observation points in drill holes and along river and stream banks are few and far between. Coals in northern Alaskan fields tend to range in rank from bituminous, where moderately folded and faulted in the foothills, to subbittuminous in the gently folded rocks under the coastal plain. Coals toward the eastern extremities of the coal fields may be of Tertiary age and lower in rank, but the same general correlation between degree of folding and increase in rank can be expected. Some higher rank coals in the foothills belt are known to have coking properties but most, and possibly all, require

Jan 1, 1984

By J. J. Scott

This investigation utilizes three dimensional photo-elastic techniques to determine the stress distributions in the pillars and the roof of a room and pillar mine model. Castolite plastic was used for the construction of the model in which a stress pattern was developed by the stress freezing process. Analysis of the stress pattern was accomplished by observation of points in slices from the model with a polariscope and solving the data thus obtained by the shear-difference method. Slices through the centerline, edge of pillar and centerline of span were investigated. The results of this work provide information on the overall stress distribution in points of stress concentration in compression, shear and tension, show relative magnitude of stress throughout the model and indicate directions of the most important stress values. A generalized roof bolt pattern is developed for room and pillar mines based on the stress distribution. A digital computer was used in the reduction of data and proved to be extremely useful for investigation of this type. Underground excavations disturb the equilibrium of the earth's crust and a core of fracture, or altered stress distributions exists around the openings. This fact is well known by mining operators and investigators in the rock mechanics field. Analysis of the stress distribution in the areas around mine workings is a most difficult problem and one which has no simple and direct solution. Some of the approaches used by investigators in attempts to study stress distribution around mine openings involve mathematical analysis, photoelastic techniques, statistical analysis, model studies on brittle materials and observation of fracture patterns. Models involving imbedded strain gauges, gelatin models using imbedded strings to show internal movement, and many other unique laboratory techniques are employed. Work is also being done in mining operations where load cells, strain gauges, photostress material, convergence plugs, dynamic plugs, etc., are used to measure strain which can in turn be used to obtain stress. Some of these devices measure strain from which stress may be derived. All approaches to the solution of stress distribution are hampered by the fact that the earth is not a homogeneous, isotropic and elastic media. Geologic faults, fractures, bedding planes, vugs, variations in material composition, variations in grain size and structure, etc., make it extremely difficult to obtain results which can be universally applied to mining operations. The purpose of this investigation will be to demonstrate the use of three-dimensional photoelastic techniques to obtain the stress distribution in the pillars and roof of a room and pillar mining operation. This method utilizes full analysis of interior points, and thus it may be that small tensile or shear stresses found in the investigation will prove to be of greater significance than the more obvious points of stress concentration found by two-dimensional techniques. A digital computer was employed to simplify and to shorten the time necessary to obtain final results. Application of the computer to problems of this type may enable future investigators to attempt more elaborate analyses than have been previously considered feasible. THEORY Three Dimensional Stress Analysis-Shear Difference Solution:' Photoelastic studies are based on the fact that an optically isotropic transparent solid becomes optically anisotropic when subjected to forced deformation; the degree of optical anisotropy being proportional to the deformation of the material. There are two fundamental laws which govern photoelasticity: 1) Light is polarized in the directions of the principal stress axes, and is transmitted only on planes of principal stress. 2) The difference in principal stresses is proportional to the difference in the indices of refraction along the planes of principal stress. One method used in three-dimensional photoelastic work is to examine a slice of the object by normal incidence and oblique incidence. In normal incidence,

Jan 1, 1964

By D. O. Wyble

Five water-driver fields, for which pressure predictions had been made within a few years after discovery, were re-studied when four to five years of additional pressure and production data became available. It was fortnd that forecasts of the pressure in water-dri~fe reservoirs may be subject to considerable unccrtainty. Predictions car be erroneous when there is insufficient presswe history to define the cllaracteristics of the aquifer, and when there are errors in the pressure, production or geologic data. INTRODUCTION The efficient operation of an oil or gas reservoir requires that the important characteristics of the reservoir be determined soon after its discovery. It is especially desirable to evaluate the pressure-production relationship quickly, for this relationship provides a basis for deducing the type of production mechanism that is operative, and for making pressure predictions. The pressure predictions, in turn, provide a basis for calculating efficient rates of production, determining whether water or gas should be injected, etc. The importance of pressure prediction is such that forecasts should be made as accurate as possible, and the limits of error well defined. Historically, pressure forecasts for some fields have proved very accurate, while for others the forecasts were so erroneous that they resulted in the adoption of wrong, or at best, unnecessary production practices. Pressure predictions made for water-drive fields are especially subject to error. Accurate forecasting for these fields requires that much be known not only about the reservoir proper but about the adjacent water-filled rock as well. The water-containing rock, or aquifer, may extend for many miles, and often there is only meager data regarding its thickness, permeability and porosity. Much of the information must be inferred from the previous pressure behavior of the reservoir. A brief pressure history may provide little information about the characteristics of the aquifer. Hence, pressure predictions made early in the life of water-drive fields can be incorrect. The work described in this paper was done to determine the degree of reliability which can be expected of pressure predictions made within a few years after water-drive fields are discovered. Five fields, for which the original pressure predictions had been based on less than seven years' history, were re-examined with the aid of four to five years of additional pressure data. Where the predictions were inaccurate, the reasons for failure were ascertained. The studies were accomplished by use of the electric reservoir analyzer.' The analyzer was first adjusted to repeat the original pressure-production match using the same values for the various parameters as were used in the original study. Then, the actual production rates experienced during the time elapsed since the initial study were set into the analyzer, and the pressure behavior indicated by the machine for this period was compared with that which actually OCcurred. Where the pressure profile traced out by the analyzer deviated from the observed field behavior, the analyzer was readjusted to obtain a better over-all match. The old and the new solutions were compared to determine the reasons for any differences. COMPARISON OF PREDICTED RESERVOIR PRESSURE BEHAVIOR WITH ACTUAL PERFORMANCE Field A The original pressure-production match is entirely adequate as evidenced by the pressure match of the field's history subsequent to Jan., 1952 (see Fig. 1)'.

By Louis A. Rosales, Kanji Ono

The anomalous behavior of hydrogen in iron is examined and a new model is proposed It is postulated that hydrogen single and di-interstitials are in equilibrium with each other. When the binding enthalpy of the di-interstitial, B, is assumed to be about 10 kcal per mole, the predicted temperature dependence of the solubility agrees reasonably well with the reported data. Effective diffusiuity is calculated assuming the di-interstitials to be immobile. Since the number of mobile single interstitials is greatly reduced at lower temperatures, the effective diffusivity is decreased. A good agreement in the temperature dependence of diffusivity between theory and experiment is provided with B - 10 kcal per mole. The predicted diffusivity is also a function of total concentration of hydrogen and this appears to be Partly responsible for the large scatter in the reported data. HYDROGEN is known to form an interstitial solid solution with iron.''' At elevated temperatures, it has been well-established that hydrogen enters iron in the dissociated form and occupies the interstices, and that diffusion of hydrogen in iron is via the interstitial mechanism. The concentration, c, permeability, P, and diffusivity, D, of hydrogen in iron have been separately determined and are consistent with each other under the steady-state condition for temperatures above approximately 400°C; that is, the relationship P = c-D holds. At lower temperatures, however, anomalous behavior of hydrogen in iron has been observed by many investigators. The results of experimental studies4-'' of the diffusion of hydrogen in iron are summarized in Fig. 1, in which the values of D are plotted against the reciprocal temperature. Although there is an increasing divergence in observed values of D with decreasing temperature, the values of D at temperatures below approximately 200°C are definitely small as compared with the extrapolation from high-temperature data. The lines shown bracket the region containing the most probable data. The observed values of c6," are plotted against the reciprocal temperature in Fig. 2, where the dashed lines represent Geller and sun's'' most probable isobars at 1 and 100 atm. At high external hydrogen pressure and low temperatures, the values of c observed are higher than those expected from high temperature data. It is generally accepted that certain trapping mechanism is responsible for the anomalies, but the nature of the trapping mechanism has not been clarified. Various types of hydrogen traps were suggested in the literature, such as "rifts" in the lattice dislocations, voids, microcracks, and so forth. However, no quantitative account of the observed behavior has been given in terms of these trapping mechanisms. Formation of methane in hydrogen-charged steel was found by ~odgurski." This appears to explain the existence of the so-called "residual" hydrogen,4 but not the observed anomalies of hydrogen in iron. McNabb and Foster' proposed a mathematical analysis in terms of a trapping mechanism. However, the physical significance of the traps was not clarified. The necessity of evaluating five parameters in their theory made comparison with experiment difficult. In the present paper, a model is proposed in which the anomalous behavior of hydrogen is attributed to the formation of hydrogen di-interstitials at lower temperatures. In this model, it is postulated that single and di-interstitials are in equilibrium with each other. (The hydrogen di-interstitial is to be distinguished from a hydrogen molecule which may exist in voids.) It can then be shown that most of the anomalies can be explained by assuming that the di-interstitials are virtually immobile and that the binding enthalpy of the di-interstitial, B, is approximately 10 kcal per mole. Predictions of the theory agree with the available experimental data reasonably well. THEORY The basic postulate of the present analysis is that single and di-interstitials are in equilibrium with each

Jan 1, 1969

By W. A. Krivsky, R. Schumann

Relaxation calculations were made to find the temperature distribution in the refractory wall surrounding a tuyere pipe. One set of boundary conditions approxiwated those of a standard copper converter while a second set represented a hypothetical,thermally insulated tuyere pipe. The pvonounced cooling effect of the tuyere is related to the problem of tuyere accretions and tuyere bunching. PARTICULARLY severe service conditions are encountered in the tuyere zone of a basic copper converter during the matte blow. High-temperature gradients result from the juxtaposition of the hot charge and the tuyere pipe carrying cold air. Refractory temperatures near the tuyere mouth vary rapidly with time when the blast is turned on or off. One of the most serious problems is the formation of magnetite accretions around the tuyere mouth, which occurs very rapidly under some operating conditions. As a result, continual punching of the tuyeres is necessary to maintain a satisfactory rate of converting. Thus, if some means could be devised for keeping the tuyere pipes fully open without necessity for punching, a considerable saving should result from reduction in labor cost, maintenance of full capacity operation, and reduction in refractory costs. Recent quantitative studies of the FeO-Fe,O,-SiO, system1 have shown that the solubility of magnetite in iron-silicate slags decreases rapidly with de- creasing temperature in the range of copper converting temperatures. Data taken from the previous work are shown in Fig. 1. Thus the formation of "horns" and accretions around the tuyere mouth can result simply from the freezing out of magnetite on the cooler areas of refractory immediately adjacent to the tuyere pipes. One might expect to find a correlation between the severity of magnetite formation and the area of refractory surface which is cooled below the freezing point of the slag (corresponding to magnetite precipitation). Magnetite itself has a very high melting point (1597°C) so that the accretions are for all practical purposes infusible. The accretions might be dissolved by increasing the silica content of the slag and at the same time raising the temperature, but this approach is not feasible because it results in rapid corrosion of the basic refractory lining of the converter as a whole. In order to understand better the problems involved in tuyere design and operation, it seems essential to have at least a semiquantitative idea of the thermal conditions in the tuyere zone. Accordingly, this paper presents results of thermal calculations for an idealized copper converter tuyere. These calculations follow the so-called relaxation

Jan 1, 1960

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The Vermilion range extends from the vicinity of Tower to and beyond the ""international boundary, crossing into Canada at the eastern end of Hunter's Island. Merchantable bodies of ore have been discovered at but two localities along this extent, at Tower and at Ely, twenty-one miles east.The iron bearing formation of this range occupies the lowest position geologically of any of the Lake Superior iron formations, being placed by Van Rise and Clements in the Archean, as shown from the following succession:Lower Huronian Intrusive granites, granite porphyries, dolerites, and lamprophyresKnife Lake slatesAgawa formation (iron-bearing) Ogishke conglomerate(Unconformity.)ArcheanIntrusive granites, granite porphyries, and some greenstonesSoudan formation (the iron-bearing formation). (Minor unconformity.)Ely greenstone, an ellipsoidally parted basic igneous and largely volcanic rock The ores of the Vermilion series occur in the Soudan formation (the Agawa iron bearing rocks are not of commercial importance).At the Minnesota mine at Soudan the ore is a dense, hard hematite, occurring in irregular connected and disconnected lense shaped bodies in the jasper, which is intricately infolded in the ellipsoidal greenstone or green schists, so called on account of a characteristic ellipsoidal parting. The strike is about east and west and the dip approximately vertical, with a westerly pitch. The underground workings at this mine are some 4,500 feet in extent east and west, and over 1,500 feet in depth. The structure here is probably the most complex in the Lake Superior iron districts. Above the iron bearing formation, geologically, comes the basal conglomerate of the Lower Huronian, carrying large boulders and Masses of the iron bearing rocks."

Jan 1, 1920

By G. Robert Ganis

The folded Appalachians are a physiographic province of eastern North America extending from Nova Scotia to Alabama. The province strikes through the state of Pennsylvania (see Fig. 1) comprising roughly 20 percent of the state and it is here that the focus of this paper will attend. The province is a thick sedimentary sequence which was compressed into a folded mountain belt by the Appalachian Orogeny which terminated at the end of the Permian. The stratigraphy contains both carbonate and non-carbonate rocks as a reflection of the depositional environment at any specific time and place during the Paleozoic geosynclinal accumulation. Although a great deal of variety and difference exists in the geology from one end to another, a common thread of structural and stratigraphic style exists. Carbonate rocks, limestones and dolomites, comprise a substantial percentage of the total Appalachian stratigraphy and are interbedded with clastic materials such as sandstones, siltstones, and shales. The carbonate rocks are extensively mined and collectively represent a vast economic resource.

Jan 1, 1983

By R. W. Freedman

The gas chromatographic method, devised by the Bureau of Mines for analyzing routine mine air samples, was compared with the infrared method used for confirmatory determination of methane in mine air. While maintaining the specificity of the infrared method for methane determination, the gas chromatographic method is more precise, much more rapidly performed, and more convenient.

Jan 1, 1968

By Robert A. Medower

This paper will review the operational benefits of applying contemporary control technology to balance the blast to a cupola. Reported benefits from existing installations include reduced channelling, higher pour temperature, reduced oxygen consumption, lower coke consumption & reduced emissions.

Jan 1, 2001

By M. R. Shadnam

This contribution provides an assessment of research and development efforts to optimize SOx, NOx and mercury capture in flue gas. Coa, characteristics and combustion conditions in a power plant have an impact on the types and concentration of flue gas pollutants. These factors can also affect the amount of pollutant removed. This contribution would also provide a comparative study of the technologies that holistically aim remova, of SOx, NOx and mercury altogether in coal-fired power plants. A portion of this contribution provides background information on regulatory drivers.

Jan 1, 2010

By Thomas D. E.

Discussion at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair, of a paper published in Trans. Instn. Min. Engrs., 1916, vol. L., page 482, comprised the author's written response to suggestions made in previous discussion

Dec 1, 1916

By L. G. Austin

If S (x) is the specific rate of breakage of size x and B (x, y) (see Table 1 for Nomenclature) is the cumulative breakage distribution function, the Herbst Fuerstenau2 assumption is that Inserting this assumption into first-order grinding equations it has been shown" that there are then simple analytical solutions to the grinding equations, as shown in Table 2. In this context "plug flow" is defined as all material passing through the mill in the same length of time, the residence time t. The term "n fully-mixed" means that the mill has a residence time distribution" which can be treated as if the mill were n equal fully mixed sections in series. In addition it has been shown that the assumption of Eq. 1 also leads to simple analytical solutions for closed-circuit, steady-state grinding with an ideal classifier at the mill exit returning oversize to the mill feed. The solutions are also given in Table 2, with µ as the ideal classifier cut size, C the circulation ratio, and Q (x) the size distribution of the circuit product. The specific surface area of these size distributions is where the density-shape factor k. is assumed to be constant with size. In practice, most methods of size analysis or area [ ] measurement have a finite lower limit, so that the integration is really performed from xm, to xm, For a realistic degree of grinding the value of So is dominated by the fine sizes because of the 1/x factor. Consider batch grinding of a feed of size y to y + dy. The batch grinding solution given in Table 2 is then [ ] The fresh surface area produced is the area of the fines plus the area of the original material remaining minus the area of the original material, [ ] Little error is introduced by neglecting the last term on the right-hand side since at t = 0 it is zero, and when t is significant the first term dominates because of the fine sizes produced. In addition, the form of P (x, t) for [ ] realistic values of S (x) 2t ax° is such that the major fraction of fresh surface produced is contained within the bottom 10% of weight of broken material, that is, for sizes for which P(x, t) < 0.1 (providing y is not near x.,). Thus for surface area purposes Eq. 3 can be approximated by [ ] becomes providing again that the feed sizes are coarse relative to xmi. Then the fresh area production is and W is the mass in the mill. The rate of surface production is WK, and the specific surface is Kt. From Table 2, the specific energy is mt/W so surface production per unit energy is [ ] Surface produced per unit energy input = KW/m (8) where m is the energy input of the mill. Clearly, identical reasoning applies to open-cycle, plug-flow grinding, with t replacing t, and Eq. 8 is obtained again. Considering open-cycle, fully mixed grinding, similar reasoning gives P(x) - t S(x) for surface area purposes, and

Jan 1, 1974

By Qinghua Song, Jianhong Chen, Shan Yang, Zhiyong Zhou

"The development process of Metal Resources Technical and Economic Evaluation Expert System (MRTEEES) is introduced in the aspects of requirements analysis, design of the expert system, main functions of the expert system and features of the expert system. The system is based on C/B/S mixed mode and uses ASP.NET technology with .Net Framework being chosen as the development platform and metal resources database providing data support at the bottom layer. The system is an auxiliary management system for metal resources technical and economic evaluation and has the basic functions of auxiliary decision analysis, metal resources database management, data management and comprehensive query. Technical and economic evaluation model can be set up by users independently according to at which stage a project is, mainly including exploration stage, development stage and production stage, and according to the mining methods, for example underground mining, surface mining and in-situ leaching mining. Then, the technical and economic evaluation parameters can be generated. By inputting the value of each parameter in a simple and convenient way, the evaluation results can be directly calculated out and shown in the form of diagrams among others, and feasibility evaluation report can also be automatically generated, making the technical and economic evaluation process accurate and efficient. As the system can achieve the functions of scenario analysis, sensitivity analysis, shareholder’s returns analysis, horizontal comparison of different projects, it can improve the ability of project senior decision makers for rapid response to the rival and meet the demand of pricing negotiations. IntroductionWith the arrival of a new round of industrialization upsurge in both developing and developed countries, growth of demand for metal resources is entering a new stage. Population involved in the new industrialized countries is about four times that of all previous industrialized countries, implying resource consumption increases dramatically both in speed and in quantity. It is a must to seize the strategic opportunity of developing and utilizing metal resources around the world to lay abundant resource base for national industrialization. Objectively speaking, global configuration of metal resources is an inevitable tend. Presently, many issues, for example, resources exploration, mining, merge of mining companies, metal trades, mining financing, etc., generally show the feature of globalization. For the reality that competition for metal resources is becoming fiercer, industry standards of mineral resources will undoubtedly be improved. Occupying large scale mineral resources with high grade and developing them with low cost is the base for the survival of mining companies and metal resources merchants. With the growing demand of global investment in mineral resources exploration, which is at the upstream of the industry chain, geological exploration industry is promising. Globally building market relationships for mineral resources exploration companies is key to their sustainable development. Developing large and super-large deposit with low cost is also an important approach to enhancing core competence of a country or an enterprise. Mining companies around the world are rushing to purchase mineral resources globally. However, in different countries, economic, financial and tax systems for mineral resources vary greatly, and mining and processing techniques, technical parameters and equipment selection also change a lot. Thus, pro-phase research work is necessary for feasibility evaluation of mineral resources projects and it can be time wasting if taken in the traditional way. It is necessary to accelerate the process considering the complex and rapidly changing international situation."

Jan 1, 2017

By John D. Abbatt, H. B. Newcombe

The Eldorado Epidemiology Project formally began in late 1978. It consists of a retrospective cohort study, to be followed by and to leave in place the mechanism for a prospective cohort monitoring program. These present and future activities are intended to merge into one another. The current study includes all Eldorado employees past and present for whom records are available. The objectives of the undertaking are - 1) to obtain cause-and-effect, dose-response data with which to evaluate the risks to workers in radon and radon daughter containing atmospheres, and to provide additional quantitative information on which to base possible improvements in working conditions; 2) to identify any dead employees of E.N.L. whose cause of death suggests that a potential compensation claim right exists for their survivors, and to similarly identify living ex-employees of E.N.L. whose work histories and states of health suggest potential compensation claim rights. The nature of the study has been determined by the history of Eldorado, which will be described briefly. Eldorado began (as Eldorado Gold Mines) in the late 1920&apos;s, operating relatively unsuccessfully in Manitoba. In 1930-31 the emphasis shifted from gold to uranium, and what became the Port Radium mine was first staked. From the very early 1930&apos;s until 1942 the company&apos;s purpose was almost entirely devoted to the mining of pitchblende - uranium ore - from the Port Radium site, and the extraction of radium from this ore at the Port Hope refinery in Ontario, a process from which the uranium was a largely stockpiled byproduct. In 1942 the company was requested by the Canadian government to accelerate the production of ore, and of uranium. At the same time, all its stockpile of uranium (then being stored in silos as a "waste" product which might later "come in") was acquired for the Manhattan Project. In 1944 the company shares were bought by the Canadian government and the company itself became Eldorado Mining and Refining (1944) Limited; it has operated as a Crown corporation ever since. The name was changed to Eldorado Nuclear Limited in 1968. The Port Radium mine was closed in 1960, and since 1953 the Beaverlodge uranium mine complex has operated on the northern shores of Lake Athabasca. Radium production was discontinued in 1954 when the radium circuit was taken out of the refinery, and since that time the refinery&apos;s products have been various types of refined uranium (uranium dioxide, uranium trioxide and uranium hexafluoride) plus metallic uranium. The refinery, of course, processes the company&apos;s own yellowcake but as it is one of only five refineries in the western world, most of its work consists of custom refining for a large variety of customers. In addition to the mining and the refining operations, there have been three other divisions involved, and these are, respectively, Aviation, R. & D., and Exploration, in addition to the financial, corporate, administrative and support activities. MATERIAL AND METHODS The human study population (Abbatt, J.D. et al., 1980) consists of all Eldorado employees who have ever worked for E.N.L. and for whom records are available. The total nominal roll to December 31, 1980 is approximately 21,000 and consists of employees of the Mining, Refining, R. & D., Aviation and Exploration Divisions, as well as a relatively small number of other employees (Head Office, etc.). The basic epidemiologic design, as has been mentioned, is for a retrospective cohort study merging into a prospective cohort study, and depending very heavily upon automated record linkage and file matching. The original design called for an initial assembly of the bulk of the nominal roll, prior to the first of two matches with the National Mortality File. The first of these two matches is now complete and the second is to be separated from it in time by 18 months to two years. The second match will be the definitive match prior to the analysis, the interpretation of the data, and the publication of the results. The period between the two matches was designed to permit completion of the nominal roll, including: - addition of previously missing individuals and groups, elimination of duplicates, and amplification of identifying information, - assembly of work histories and exposure information for each individual, - digestion and application of lessons and modifications resulting from the first match with the National Mortality File at Statistics Canada, - preparation of files for the definitive second match. The analysis of data will be carried out by the National Cancer Institute of Canada Epidemiology Unit based at the University of Toronto. This group, with whom Eldorado Nuclear has a memorandum of understanding, have for a variety of reasons, including their familiarity with record linkage and their expertise, been members of the Project Team since

Jan 1, 1981

By R. Q. Shotts

This paper is a review of recoverable reserves of bituminous coal in the Southern Appalachian area, according to the latest published estimates. A few comparisons are made, some apparent trends are discussed, and some comments are made regarding the limitations of present estimates. The definition of Southern Appalachian area used in this report is somewhat arbitrary. It includes all the bituminous coal deposits of Alabama, Georgia, and Tennessee. All of West Virginia has been excluded. The East Kentucky and Virginia counties included were selected in connection with a literature study the writer made in 1959 of possible coal supply areas for the Tennessee Valley Authority. The selected counties were considered to be the only ones from which TVA might expect to obtain coal. The availability of coal from some of these counties is doubtful, but no other East Kentucky counties were considered more than remote possibilities. With these limitations, the Appalachian area covered is that from which producers of electric power and steel and commercial coal users, located in the Southeastern U. S., may expect to obtain their supplies of coal. Of course, it is recognized that coal from the eastern interior fields is also available to many of these same organizations. RANK AND QUALITY OF THE COALS Practically all the coals in the Southern Appalachian region are of high volatile A bituminous rank. An occasional sample indicates a slightly lower rank, but such samples may be oxidized or otherwise not representative. Some thin beds in Lookout Mountain and Sand Mountain in Alabama and Georgia, are low volatile bituminous coals, but they have not been mined extensively in modern times. There is a possibility that some of the deeper beds along the southeastern edge of the Warrior field of Alabama are near the Low-medium volatile bituminous dividing line. The Sewanee bed and some other minor ones of the Southern Tennessee field, some of the lower beds in Virginia, many beds in Sand and Lookout Mountains in Georgia and Alabama, one or more beds in the Coosa field, possibly some lower beds in the Cahaba field, and most of the beds along the southeastern edge of the Warrior field and the southern end of the Sequatchie anticline of Alabama, are of medium volatile bituminous rank. The quality of the Southern Appalachian coals is highly variable. Some of them, particularly such prevailingly thin ones as the Black Creek bed of Alabama and the Straight Creek bed of Kentucky, are unusually low in mineral matter— probably the lowest in the U. S. With the exception of certain beds and local areas, Alabama and East Kentucky coals probably have as low average ash and sulfur content as can be found in any sizeable coal area in the country. The sulfur content of Southern Appalachian coals is also variable, but few beds are consistently high in sulfur. In Alabama, sulfur generally increases from southeast to northwest across the Warrior field, but this trend is not quite as clear in the other states. A few beds in Northern Tennessee are prevailingly high in sulfur. All Southern Appalachian coals are potential coking coals if they can be prepared to meet chemical requirements. Only a comparatively small part of the medium volatile A bituminous coal, but most of the medium volatile bituminous coal mined is actually used for coking purposes. An estimate of reserves of coking coal under the requirements of present practice, could be compiled comparatively easily, but this probably has never been done. The reserve of coal that can be coked as an ingredient of a suitable blend is probably many times the size of the reserves of coal that will yield suitable blast furnace and foundary coke without blending. WHAT CONSTITUTES ECONOMICALLY RECOVERABLE COAL RESERVES? When one first realizes the vast extent of the coal-bearing rocks in the Southern Appalachian area, (see Fig. 1) the thought is likely to occur that the supply of coal is inexhaustible. This is particularly true on realizing that in some of the basins of thicker coal-

Jan 1, 1962

By H. Wilton Clark

VARYING in thickness and in number from place to place, coal seams in the Canadian Rockies also range in pitch from nearly horizontal to vertical, sometimes with overturns. Over the entire coal-bearing area there are considerable differences of rank in coals of the same geological age, and there are marked differences in ash content and wash-ability characteristics. Correlation of seams at mining operations within a few miles of each other has often proved impossible. These factors influence mining methods, and, of course, production results. The oldest coal formations of western Canada are of Lower Cretaceous age, as the carboniferous sediments are marine and contain no coal. Coal is also present in formations of Upper Cretaceous and Tertiary ages. The rank of coal varies from semi-anthracite in some operations in the Kootenay and Luscar formations of the Lower Cretaceous in the Rockies to lignite in the Tertiary fields of the Saskatchewan prairies. Fig. 1 shows the general extent of the formations. The pitching seams, chiefly Lower Cretaceous, occur in the western belt of the Rocky Mountain foothills and the eastern slopes of the Rockies themselves. (The road to Tent Mt. strip pit, elevation 7000 ft, is shown on p. 832.) Formations extend from the U. S.-Canadian boundary for several bundred miles in Alberta and continue for a similar distance in British Columbia. Present geological estimates show a probable reserve of the order of 25,000 million tons of coal ranging from high volatile bituminous to semi-anthracite, with a large percentage of coking coal, constituting one of the major world reserves of that type. It should be noted that although the quoted estimate probably errs on the conservative side, the question of access to the seams in a mountainous terrain will always be a problem; a wide divergence may exist between actual reserves and the quantities of coal economically recoverable. An excerpt from the Canadian government Report of the Royal Commission on Coal 1946 states that conditions favorable to coal formation were intermittent and these intervals relatively brief in comparison with periods in which no coal was formed. Conditions were favorable to the growth or accumulation of vegetation in one area, while fresh water sediments and marine shales were being deposited in other areas. During periods of emergence the coal deposits were subjected to erosion or were covered by coarse sands and gravels from the mountains, whereas during submergence they were covered by fine clays deposited in embayments of the sea. During some of the periods of coal formation, volcanic activity deposited beds of fine volcanic ash and dust with the coal-forming vegetation. Coal deposits reach their greatest development in the mountains and thin rapidly to the east into the plains area, where they are deeply buried beneath younger sediments. For example, in the Fernie area of southeastern British Columbia there are in places 22 seams having an aggregate thickness of 150 ft in a stratigraphic interval of 3500 ft, whereas at Cole-man in the Alberta Crowsnest area the measures are only 800 ft in thickness and contain a maximum of five seams aggregating about 47 ft of coal. At Belle-vue, 10 miles further east, the measures are reduced to 430 ft with only three seams aggregating about 37 ft of coal. Subsequently the tremendous forces involved in the upthrust of the Rocky Mountains produced great displacement of the coal-bearing formations and at the same time a change in geologically young coals from low to high rank. The floor or footwall of most seams consists of carbonaceous shales, which are almost as adaptable to bending as the coal seams themselves. The seams show very few cleats or cleavage planes and have been so weakened structurally that as mined 50 pct or more will pass through a ¼-in. screen, seldom

Jan 1, 1955