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Jan 1, 1941

By George Breyer

DURING the past 25 years the steelmaker has experienced some difficulty in producing steel to meet the standards established by the metallurgist. In contrast to the past, when a chemical specification of broad limits was the only requirement, he now has to employ such tests as microscopic, macroscopic, tensile, impact, Magnaflux and even X-ray and supersonic. The development of these tests has more than set the pace for a manufacturing process of which the exactness still hinges to an important degree on the ability of the furnace operator. In our efforts to produce steel, and especially alloy steel, to meet the exactness of modern engineering specification, many factors must be taken into account. It is not sufficient to make a good heat of steel in the furnace and then be satisfied that the job is done, since there are many pitfalls between the furnace and the finished product. The literature abounds with information on melting practices, deoxidation methods and slag control, but the lack of positive information about what happens when the steel is teemed into molds is quite evident. Such questions as what is the proper mold size, shape and thickness; which is the best mold coating; what is the best rate of pour for any given steel, and what is the effect of cooling rates on quality, are still answered by opinions. It is acknowledged that a poor heat of steel cannot be improved in the pouring pit. On the other hand, a good heat can be ruined by improper handling after it leaves the furnace.

Jan 1, 1947

By Jacques B. Wertz

Among the parameters to be considered in the continuous search for new base-metal deposits, there often is a stratigraphic controlling factor that seems instrumental in the localization of ore. In British Columbia, for instance, the Upper Triassic as well as Lower Jurassic volcanics mixed with sediments are a useful indication in the search for copper while, in some parts of Australia, rhyolite bodies seem to be the favorable indicator, and this always within the geosynclinal environment. In Arizona, this stratigraphic factor becomes highly significant and it will be shown here that a large number of ore deposits are to be located around the flanks of ancient calcareous basins or depressions, preferentially corresponding to a certain optimum thickness as revealed by isopachs. The Martin limestone, of Devonian age, is already known for its basal O'Carroll bed which coincides with mineralization at places, and this is a relatively minor control. However, several limestone basins outlined by isopachs are in reality of greater importance as they localize mining districts. Indeed, most mines are found to coincide with a specific thickness of limestone while occurring simultaneously close to major, regional fracture intersections. The regional fractures in question were interpolated and extrapolated from known, important fault expressions, integrating quite well with the existing geology and further confirmed by minor criteria such as contacts, igneous plugs, axes of elongation of batholiths, dikes, etc. Although elements of subjectivity remain, this grid of fractures can be used quite successfully as a working hypothesis in the search for ore. Results of the present study which superposes major structural

Jan 1, 1971

By P. E. Baker

An experimental study of heat flow in steam flooding was carried out with steam displacing water in a plane-radial fluid-flow model. Temperature distributions in the model reservoir, overburden, and substratum were measured at frequent intervals during flooding by means of a fixed array of thermocouples. Heat losses to overburden and substratum and the division of heat between the steam and hot-water zones in the reservoir were calculated from the temperature data by performing numerical integrations over the appropriate volumes. Temperature profiles and heat distribution results are presented. Some results were (1) the fraction of injected heat that is lost to overburden and substratum, when expressed as a function of time, did not depend on injection rate; (2) a significant portion of the injected heat was contained in the hot-water zone ahead of and underlying the steam front in the reservoir. The division of heat between the steam and hot-water zones did depend on injection rate; and (3) considerable gravity override was observed. The experimental results are compared with those of several published theoretical studies of heat transfer in hot-fluid injection; approximate agreement on heat losses is found with some of the most idealized theories. A valid comparison cannot be made in regard to steam us hot-water zone; basic interpretation of the hot-water zone, in terms of a vertical steam front, is clouded by gravity override in the experiments. INTRODUCTION The experimental study reported here primarily concerns two problems of heat transfer in steam flooding that have economic and engineering importance. These are (1) the fraction of injected heat lost to the overburden and substratum, and (2) the division of the remaining heat between a zone containing steam and a zone of hot water at lower-than-boiling temperature. The volume of the steamed region, which has a direct effect on oil recovery, can be calculated readily from these results. Several valuable theoretical studies have been published on this problem, but no experimental tests of the theories have previously appeared. Tests were needed because the effects of the necessary simplifications in the theories could not be determined otherwise. The basic, untested theoretical problem is the effect of "decoupling" heat and mass transfer, and the resulting inability to include the effects of heat transfer and condensation on fluid flow. The theoretical problem solved so far has been a heat transfer problem in which fluid is present as a heat carrier and flows in a stipulated manner, either linear or plane-radial. The simplifications that have sometimes been made in regard to thermal conductivity by, for example, Marx and Langenheim,l Lauwerier2 and Thomas3 apparently do not have an important effect on heat loss calculations, although the results of the different methods disagree to a certain extent, as shown by Spillette4 and by Ramey.5 A recent paper by the author6 compared the results of experiments in hot-water flooding with several theoretical results and showed a rather poor agreement. It will be seen that the experimental heat loss results for steam flooding, however, show acceptable agreement. These comparisons are discussed in a later section. EXPERIMENTAL APPARATUS AND PROCEDURE The system studied was one in which a sand pack, initially water saturated and at a uniform temperature, was flooded with steam at a constant rate and temperature. The temperature distribution in the "reservoir" and adjacent "strata" was measured with an array of thermocouples, and heat losses were determined from these measurements. The sand pack contained no oil because the only concern of the experiments was heat flow, and it was important to have the flow pattern as simple

Jan 1, 1970

By Albert Sir Kitson

THE manganese ore deposits of the Gold Coast, British West Africa, occur in very ancient rocks, of both sedimentary and metamorphic types. In. certain respects they strongly resemble those of India and Brazil, as contrasted with those of Tertiary age in Georgia. Viewed from the present condition of the maganiferous rocks, the oldest deposits are in the sediments. Later than these are the progressively metamorphosed representatives of these sediments; youngest are the products of decay and degradation with the concentration of manganese oxide of both areas. The oldest occurrences are in argillaceous and siliceous phyllites and slates, which show only a moderate amount of metamorphism. They belong to a series which also includes mudstones, sandstones, grits, conglomerates and subordinate limestones, with tuffs and lava-flows largely of basic types. To this series I have given the name Birrim. Its age is unknown, for no definite fossils have been discovered in it. As the characteristics of these non-fossiliferous strata at many places are the same as those of strata in many parts of the world that are suitable for the preservation of fossils and that contain them, it is assumed that the Gold Coast deposits are pre-Cambrian. These rocks of the Birrim series have normally a northeast-southwest strike and are folded, but not to any very great degree except in certain belts., From the Eastern Province of the Gold Coast they may be traversed across their strike for more than 600 miles to the extreme northwestern corner of the Northern Territories. Thence. they probably extend much further into French Territory.

Jan 5, 1927

By C. P. Walker

Determining the distance to remote objects by observing the time required for sound to traverse the intervening space is an old practice. Attempts have been made to use this method for determining the fluid level in oil wells but as far as the writer is aware it was not found to be practicable, because vibrations in gas in the audible frequency range do not travel as well and as far as low-frequency pressure waves, which are capable of transmitting a greater amount of energy than can be transmitted by audible waves. Wood, in his book "Sound," states that in a given medium the range of sound transmission will vary inversely as the square of the frequency. The fact that the sound from a whistle having a low tone has a much lower attenuation rate than that from a whistle of high pitch is well known. Also, the pressure waves caused by cannon fire often rattle windows at points so distant that no sound of the cannon is heard. In 1932 P. E. Lehr and H. T. Wyatt, of the Shell Oil Co., experimented with the principle of the concussion, or pressure-wave echo, method of determining fluid levels in oil wells. They released compressed gas into the top of the casing, thereby creating a pressure wave, which traveled down the well and back again. Their experiments proved conclusively that, with the proper apparatus for recording the echoes and determining the velocities at which the waves travel, the method could be used successfully for determining fluid levels in oil wells. Wells are often equipped with from one to three tubing catchers and these together with the top of the liner are frequently above the fluid. Each of these obstructions reflects a part of the pressure wave. In such wells there may be, therefore, as many as five pressure-wave reflections. Thus it is obvious that in order to identify the various reflections and to determine therefrom the fluid level in a well it is necessary to obtain a graphic record of these reflections.

Jan 1, 1937

By S. Harries Daddow

IN order to get an idea as to the strength of steel rails, it will be well to review the tests to which iron rails have been subjected. In England, Mr. Ashcroft found that the best 80 pound rails broke under a 300 pound weight, falling 15 feet. In Germany the Society of Railway tyfanage1-s determined 011 and have long applied a test of 1000 pounds falling 101/2 feet, as the standard which all first-class iron rails must reach. In this country no inspection nor test is applied, but tests made show that iron rails fro; our most reliable makers, break under a G foot fall of a 1500 pound drop as an extreme test, most of those tested breaking under a far less test; some breaking with less than a 3 foot fall of the same weight. Everywhere where steel has been used, engineers have come to the conclusion that some test is required to show the regularity and strength of the product. As compared with iron, the tests which steel will stand are wonderful. After numerous experiments partially based on the experience of the rail-mill at Graz, belonging to the Southern Railway of Austria, the Society of German Railway Managers fixed upon a test of 2000 pounds falling 138 feet. They found that this test represented the steel which suited their necessities, and also found that with steel of otherwise average purity, this test represented about one-half per cent. of carbon, and made it a rule to take no steel containing under three-tenths of a per cent. of carbon, because it was too soft. They expressed a hope that a harder steel could soon be made tough enough to stand the same test. I n England, a test was adopted of 2240 pounds, falling 15 to 17 feet on the rail on heavy bearings. This test has been found satisfactory under heavy traffic on average road-beds, and has been invariablyPILLAR of coal, which are designed and left in our mines as the means of supporting the overlying strata of our coal-beds, and securing protection to the miner, are not only insufficient for these purposes, but the most objectionable means of providing the desired security to life and property. Though such pillars are left at a great sacrifice to the owners of collieries and mineral lands, loss to the resources of the commonwealth, and ultimate privation to the public, they defeat the very ends for which they are designed, and not only do not secure life and property, but are as fatal to the one as ruinous to the other. Propositions.-It is eminently desirable that the resources of the Common wealth-particularly our mineral wealth in anthracite coal, which is limited-should be carefully utilized and made available, not only to ourselves but our posterity. Yet, speaking as an anthracite miner, we are wasting our resources of coal with a recklessness which will bring ruin in the end, unless checked, not only to the iron manufacturing interests of the East, whose chief protection, in competition with the iron-masters of the interior, lies in a cheap and abundant supply of anthracite furnace fuel, but to the best interests of the State. It is, consequently, not only desirable, but necessary, that we should realize every ton of coal from each colliery, and every acre of coal area, in order that our resources may not be wasted at present, to breed want in the future, and to realize the greatest present benefit to the mine, the miner, and the public. It is not possible, however, to secure these ends, if we continue to leave, as we do at present, from one-third to one-half our resources in anthracite as pillars in our mines. But our sad bills of mortality, our abandoned collieries, and our yawning mountain-sides, present ample evidence that even this enormous waste of coal, though left for the purpose of protecting life and property, is as totally inade-

By Roscoe C. Clark

In a previous technical note' by Walter Rose, evidence is offered in support of the contention that "the possibility of describing oil recovery features in terms of capillary pressure phenomena has not been established entirely." It is not the purpose of this note to present further discussion of this possibility but rather to point out that the argument presented there does not appear to be generally valid. In the cited note' reference is made to the experiments of Welge2 wherein it was shown that when water was displaced by oil from a core the pressure in the water phase was less than in the oil phase but that when this oil was then produced by water drive the pressure in the water phase was greater than in the oil phase. Rose has concluded from these observations that conditions of static equilibrium did not obtain since the fluid saturations were such that phase discontinuities seemed unlikely. The argument from which this conclusion was drawn is based on the contention that "the pressure is always greatest in the non-wetting phase at each static interstitial interface of contact with the wetting phase." This premise appears to have been reached from a consideration of capillary phenomena in cylindrical tubes, although it may a1so hold for other types of pore geometry, hut as will be shown below it does not hold for all pore shapes and hence is not generally applicable. Since the pore structure of porous media such as reservoir rocks i- in general so complex as to defy exact description. it is undoubtedly of great value to establish a model in terms of pore shapes of known geometry, provided of course that the limitations of the model are recognized. That the limitations of the capillary. or cylindrical, tube model have not always been fully recognized will be evident from the following discussion of a pore of different shape hut one which may a. logically he considered a.; the capillary tube. The pore space to be considered is that shown in Fig. 1, which may be thought of as the "hole in a doughnut."* Consider the interface, A-B-A', between two immiscible fluids, P, and P2, which interface meets the solid alone a line, A-C.A'-C'. The interface A-B-A' is the surface of a spherical segmen† while the line of mutual contact be-

Jan 1, 1950

By F. W. Robinson

THE temperature coefficient of electrical resistance of pure metals is high and therefore the resistance increases rapidly with rising temperature. In 1871, Siemens suggested the use of this property as an accurate means of temperature determination. Owing to practical difficulties, particularly the contamination of the metal and consequent permanent change in its resistance and its resistance-temperature relation, this method fell into disrepute as a practical standard until revived later by Callendar and Griffiths, and subsequently by Holborn and Wien, all of whom showed that the earlier difficulties were not inherent in the method but incident to the mode of protection of the resistance coils. Following .the work of these investigators, the problem of temperature measurement by this means has been the subject of careful study and has now assumed an importance second only in practical adoption to the thermo-electric method. It is generally recognized, both here and in Europe, that the standard temperature scale should be the thermodynamic as it permits the evaluation of high temperatures on the basis of the radiation laws of Stefan and Bolzmann, of Rayleigh, and of Wien and Planck, on a scale consistent with that obtained by means of the gas thermometer at low temperatures. Lord Kelvin showed that only. a very small correction, amounting to about +0.7° at 1000° C.-almost within the limits of experimental errors-is necessary to adjust the constant-volume nitrogen thermometer to the ideal thermodynamic scale.

Jan 9, 1919

By S. Tandanand, Powell. L. R.

The US Bureau of Mines assessed the geological effects on the ratio of maximum subsidence and extraction thickness, known as the subsidence factor, to develop a simple method for predicting the maximum subsidence. The study is restricted to the Northern Appalachian Coal Basin where data were collected from 13 coal mines. A model previously developed to relate the subsidence factor with the lithology and with the width and depth of working panels was used in the assessment. The result shows the possibility of determining maximum subsidence without resorting to a rigorous method.

Jan 1, 1985

By Hugh M. Roberts

The important place in the economic life of the country that is occupied by the United States Geological Survey and the various state surveys is appreciatcd by most members of our Institute. To the public at large, the functions of these surveys are no doubt largely unknown, and taken for granted. Possibly a realization of the value of the work of these government branches is brought home most fully to that group of our members whose duties as examining engineers and mining geologists take them to mines and prospects in many different parts. The examining engineer or geologist is usually seeking for a judgment on the value of an enterprise from the standpoint of the useful minerals that may or may not be present; he must also attempt some prediction as to future market prices. On his opinion rests the determination of the expenditure of money, which rendered into other language means the expenditure of human effort. An opinion on an exploring venture or the reasoning out of the probable extensions of an orebody requires among many other things a background of knowledge covering the geologic horizons not only of an immediate area but of the surrounding area, a knowledge of the structural geology and of the causes that have operated to form the ores as they are. The great storehouses of this knowledge are the statistics, reports and maps issued by the various geological surveys. They supply the groundwork for additional observations. To these, reference is always made when going into a new district. The technique of work in the field and laboratory, and to some extent the hypotheses that underlie our methods of approach, have been formed by men such as Van Hise, Leith, Kemp, Spurr, Emmons and Lindgren, who developed their powers in the service of the geological surveys. In addition to whatever originality of thought, or power to observe facts and analyze them, may be our portion, we require, in the application of the arts and sciences, a knowledge of what has already been done. We stand on the shoulders of those who have gone before, and the extent of our vision often depends upon the thoroughness with which we form earlier work into one whole and make use of it.

Jan 1, 1935

Jan 1, 1957

By H. Case Willcox

AERIAL photographic surveying and mapping is not new or unknown to geologists. However, it has been utilized but little before, principally because it is only within the last few months that practical means of adapting this method to the requirements of petroleum companies have been discovered. No American aerial survey company has taken up aerial surveying and mapping as an engineering service to be offered to petroleum companies and their geologists for use in undeveloped and jungle-covered petroleum areas. This method of surveying and mapping, however, is used by the War Department, the U. S. Reclamation Service, and Geological Survey, and the corresponding Departments of the Canadian Government. ADVANTAGES OF AERIAL PHOTOGRAPHIC SURVEYING AND MAPPING The advantages of aerial photographic surveying and mapping to petroleum companies and their geologists are many. One of the most valuable is presented in the very first phase, or the exploration period. It is assumed that, when convinced that petroleum possibilities are present, a petroleum company has secured a concession of 8000 sq. mi. of unexplored area in Eastern Venezuela. The company may either have the entire area surveyed and mapped by the aerial photographic method, or send its chief field geologist up in an airplane so that he, from-an aerial reconnaissance, may reject certain portions that, for geological reasons, the company would not be interested in. He will then point out the regions that are to be surveyed and mapped. After the air-work is completed, the results are brought down, developed, and printed; then the resulting "contact prints" are given to the field geologist. They may be roughly assembled to give a general idea of the property in its entirety, or they are in shape to be examined in adjoining pairs under the stereo-scope. With this instrument, the geologist is enabled to make a minute examination of surface indications. The work of assembling and constructing a complete general or detailed map, according to the scales desired by the petroleum company and for the later office use, is continued by the aerial photographic company.

Jan 3, 1925

By Orville R. Lyons

THE Russellton preparation plant of Republic Steel Corp., located north of Pittsburgh, Pa., prepares 3 1/2x0-in. Thick-Freeport coal by means of a 13-ft 6-in. diam Chance cone and 16 No. 7 Deister tables. The plant feed ranges between 370 and 410 tons per hr, of which approximately 31 pct is ¼x0-in. size, and the plant reject ranges between 14 and 16 pct of the feed. The 3½xY4-in. washed coal, the cone product, is dewatered and desanded by a double-deck Parrish-type shaking screen 46 ft long and 7 ft wide. The 1¼x¼-in. portion is further dewatered by two 4x12-ft single-deck vibrating screens. The ¼x0-in. washed coal from the tables is distributed to three 54x70 in. Bird centrifuges. The dewatered centrifuge product is combined with the product of the de-watering screens prior to loading into railroad cars. During the early part of 1951 complaints were received from officials at Republic's coke ovens concerning the moisture content of Russellton washed coal. The records revealed that during the first half of 1951 the shipped washed coal moisture averaged

Jan 1, 1954

By D. M. Wyslouzil

Standard testing methods are described that are presently used for the selection of grinding equipment. Correlation between laboratory batch grinding tests and pilot plant continuous tests are established by means of particle size distributions and flotation results. Conventional and autogenous grinding circuits are discussed showing the relationships of the controllable circuit parameters.

Jan 1, 1982

By Michael P. Robinson

It has been suggested that streaming potentials are not nomlally logged because the streaming potentials known to be generated across mud filter cakes are substantially cancelled by streaming potentials generated in contiguous shale beds. Laboratory measuments of streaming poterztials acrons hand specirnens of shale have been adduced as evidence to support the suggestion. The experiments show that streanzing potential depends on the resistivity of the equilibrating solution and on pressure drop. Meizsurenlents were made perpendicular to the bedding planes of the shales. The mechanism of streaming potential generation in shale which the suggested cancellation theory iniplies has been critically examined. Conclusions reached are tested by comparing self potentials logged before and immediately after changing the resistil~ity (but not the weight) of mud in a borehole. The resultant SP change is found to equal the theoretical electrochetnical potential change, i.e., cancellation of .strearning potential is independent of mud resistivity. Since streaming po/entials generateal across mud filter cakes depend critically upon mud reistivity, shale .strearlling potential in situ must he equally sensitive. Using plausible values for the pemleahility, porosiy arzd compressibility of shale, the van Ererdingerl-Hurst approach shows that the pressure drop between horehole pressure and formation pressure in a radially honzogeneous shale is unlikely to coincide with the zone of filtrate invasion. If, perchance. this coincidence occurs with one mud a chatzge 10 a second must result in non-coincidence, i.e., a .YP logged in the second mud should show a streaming potenlial. The dilernrna may he overcome by postrrlating: (I) perrneabilities of shale7 parallel to their beddine planes greatly exceed their cross-bedding permeabilities; (2) a resistivity-sensitive mud cake of low permeability forms either on the face of, or probnhly in the lanlinations of, many shales. These postulates are examined with reference to the pres.sure and SP histories of the McClosky and Aux Vases zones in the Illinois Basin and some srcpport for them found. It is concluded that a definitive solultion to the streaming potential problem does not exist. INTRODUCTION Recently Gondouin and Scala' published a contribution to the streaming potential problem which is notable particularly for the elegance of its experimental techniques. The conclusions drawn by Gondouin and Scala from their studies amplified those previously suggested by Schehck'. In essence they suggested that the streaming potentials known to develop across mud filter cakes" are not normally observed on SP logs because they are largely cancelled by streaming potentials generated in adjacent shales. This suggestion appears so reasonable that many workers in the logging field will be prone to accept it. We incline strongly to the view that the suggestion is basically correct. Nevertheless, it is important to realize that the cancellation hypothesis in the form put forward by Gondouin and Scala does not appear to meet all the known experimental facts. It is the principal intention of this note to call attention to what appears to be a flaw in the relevancy of the experimental evidence adduced by Gondouin and Scala and to suggest an alternative hypothesis to remove it. The consequences of the new hypothesis are compared with field data which, we believe, are unique. A second but not less important purpose of this note is to emphasize that even the new hypothesis does not fully explain all field observations. Hence we conclude that further study of the streaming potential problem is required before it can be said that a definitive solution to it has been attained. The bare experimental bones of laboratory data on streaming potentials appear to be as follows. 1. A streaming potential is developed across a mud filter cake. This streaming potential is virtually independent of cake thickness but depends on the mud resistivity. The relationship is of the form, 2. A streaming potential is developed across a shale. This potential is independent of shale thickness but depends on the resistivity of the permeating solution if the shale has been first equilibrated in this solution. The relationship is of the form, The relationship in (1) was determined first by Wyllie3, confirmed by Gondouin and Scala and qualita-

By B. F. Zwick

The entire production of oil in Ecuador so far has come from the Santa Elens Peninsula, Province of Guayas. Both the shallow fields of the northern and the deeper fields of the southern part of the peninsula have been in constant exploitation, though the former are of doubtful economic value. In Table I herewith, which commences with the total amounts produced by the various companies up to 1940, annual company totals are given for the succeeding years. The figures for 1944 have been partly estimated. Table 2 gives figures on casinghead gasoline. Shell Company of Ecuador (formerly known as Anglo-Saxon) has continued active exploration in the Oriente region east of the Andes, and during 1944 the Company's first wildcat well was spudded in. International Ecuadorean Petroleum Co. (formerly International Petroleum Co., Limited) has pursued an active exploration campaign since the latter part of 1939, and a drilling string was placed in operation about a year later. A second string of tools was added during 1943 and a third a few months ago. Ten wildcats, all dry, have been completed in this period, two wells are drilling at the present time and other locations are on the program. Seven of the wells thus far drilled are in the area between Guayaquil and the Santa Elena Peninsula, one up the Daule River beyond Balzar, one on Puna Island in the Guayas Estuary and one in the northern province of Esmeraldas. Both the present drilling wells are in the Guayaquil-Santa Elena zone. The situation in regard to concessions has changed during the past four years because I.E.P.C. has made its selections from the extensive Daule-Guayas Study Concession, as a result of which large tracts were returned to the Government; because of the expropriation of the holdings of the "Ecuapetrol," a German concern whose acreage has passed into other hands; the Peruvian-Ecuadorean boundary settlement, which has reduced Shell's holdings somewhat; and the transfer of most of the holdings of the Cia. Minero-Petrolera del Pacifico to I.E.P,C. The greater part

Jan 1, 1945

By R. Ward Grosz

The Robinson mining district in east-central Nevada is itself a century of study in the changing economics of the mining business. It began as a boom and bust area. In the district today, just west of Ely, Nev., the hills are pockmarked with the tunnels and shafts sunk in a frantic scramble for gold and silver before the turn of the century. But as the economics of dwindling reserves, rising costs, and changing markets were stamping out the efforts of the gold and silver seekers, copper took over as the king of the Robinson district. Today, Kennecott Copper Corp. has four open pit mines in the district and is planning a fifth. From these mines, Kennecott produces nearly 40,000 tpy (tons per year) of copper. In its hundred years of history, the district has produced more than $1 billion in mineral values, a richer treasure than that from the more famed Comstock Lode of Virginia City, Nev. Prospectors had reported copper outcroppings in the Robinson district as early as 1872. But the first significant copper orebody was not discovered until 1901. In that year, Dave Bartley and Edwin Gray exposed the top of the porphyry orebody that would become the Ruth mine in a shaft at a depth of 120 ft. Subsequently, other larger orebodies were discovered nearby which have resulted in this area being one of the leading copper producers in the country for some 60 years. Following a period of development and exploration, the Ruth mine started production in 1915 and continued as a prosperous underground mining operation until 1948. The mining industry in Nevada experienced the same increasing cost of labor and supplies that all other mining areas had to contend with, and by 1948 the Ruth mine was no longer profitable. The mine was closed down on August 8 of that year. Now, two decades later, the mine is to produce again. The key factor in the case history of

Jan 1, 1969

By L. J. Cabri

The calculation of metallurgical balances for precious metals is very dependent on a precise mineralogical understanding of the distribution of each element. Determination whether the precious metals occur as dilute solid solutions in major minerals is not always easy because of the relatively high levels of detection (9200-500 ppm) of the precious metals by the most common methods of in-situ analysis (e.g. electron microprobe). Particle Induced X-ray Emission (PIXE) analysis of sulfides from Izok Lake, N.W.T., Canada and from the Hilton mine, Mount Isa, Australia with a proton beam (proton microprobe) confirms solid solution of Ag in chalcopyrite from both deposits. In addition, chalcopyrite and sphalerite from Izok Lake both contain indium.

Jan 1, 1984

By Charles H. Jacoby

In 1774 a Swedish chemist, C. W. Schule, first recognized manganese as an element. That same year Schule's associate, J. G. Gahn, isolated the element manganese for the first time. In 1856 the Bessemer process of steelmaking gave birth to the economic importance of manganese. Later, in 1882, Robert Hadfield discovered high manganese steels. Although the primary use of manganese is in the ferroalloy industry, two additional important uses for manganese are making chemicals and dry cell batteries. Manganese is also vital to plant and animal life. Various chemical compounds of manganese are used in fertilizers, feeds, glass manufacture, paints, varnishes, and for numerous medicinal and chemical purposes. For the study of industrial minerals and rocks, only the chemical and battery grade material is of concern, but for the sake of comparison, metallurgical aspects are included in this presentation. Although currently the world's largest consumer of manganese, the United States is producing only minor amounts of ore at the present time. This is due primarily to the fact that although huge deposits of manganese occur within our borders, all are of such low grade as to be economically unfeasible to mine. For many years various government agencies and segments of private industry have devoted sizable sums of money and time in an attempt to upgrade ores from the various deposits, and also in an attempt to recover manganese from blast furnace slags. In view of current world prices, and the quantity of high grade material available, there is little likelihood that any of these approaches will be found to be economically feasible in the near future. Geology and Mineralogy Mineralogy There are over one hundred minerals that contain manganese. These minerals vary from those with compositions that are predominantly manganese to those having only minor percentages. [ ] Geology From a geological standpoint most manga¬nese deposits are complex. In general, it can be said that all primary deposits of manganese are carbonates or silicates. The most productive and profitable have been those of sedimentary origin and residual concentrations. Examples of these residual types of deposits are associated with the metamorphosed lodes of Madhya, Pradesh, India, and the lateritic deposits of Orissa and Bihar, India; nodules in the residual clays of the Philippine Islands, U.S. southern Appalachians and Arkansas, Ghana, and Brazil. Sedimentary manganese deposits are best exemplified by the Nikopol district of Russia and the Tchiatouri area of Georgia, USSR. Hydrothermal replacements are characterized by the rhodochrosite deposits of Butte and Phillipsburg, Mont. In general, the hydrothermal type deposit has not resulted in any large tonnages being produced, but may have given

Jan 1, 1975