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By T. B. Nolan, R. N. Hunt

In terms of present metal prices, analysis of extant records of the Eureka district indicate past production of the magnitude of $200,000,000 in recovered silver, lead, and gold. Production to date has been thoroughly oxidized ore from massive replacements, fissures, manta, and pipe-like bodies-in large part from the massive Eldorado (middle Cambrian) and Hamburg (middle to late Cambrian) dolomite horizons. In the productive area of about 6 square miles carbonate rocks comprise 80 per cent of the section, which includes early Cambrian to late Ordovician horizons. Four-fifths or more of the district's production came from a block of Eldorado dolomite in Ruby Hill that was moved in over younger horizons on strands of a regional thrust fault. The lower 500 to 600 feet of the block was much fractured and brecciated and became host to the ores. The Ruby Hill fault, a late normal fault, limits the Ruby Hill block of dolomite on the north for its entire length of nearly a mile and terminates the downward extent and exploitation of its ores. It introduced an hiatus of some 40 years in the district's development. Drilling of the past 20-odd years, followed by underground work, has now exposed the down-faulted extension of the Ruby Hill block of Eldorado dolomite and its contained ores, dropped 1800 feet in a dip shift to depths beneath the surface of 2000 to 3000 feet. The ores at depth are the sulfide counterpart of those mined in early years on the footwall side of the fault. The ores of the district may be attributed to the same source as the intrusive quartz diorite outcropping in a limited way south of Ruby Hill but found at depth elsewhere in drill holes. The long north-south axis of the district, its anticlinal structure, its major faults, and the distribution of the intrusives and, in their relation to the surface, the ores themselves, all suggest that erosion has not cut deep enough to expose the extent of intrusives and the ores consequent upon them.

Jan 1, 1968

By D. R. Parrish, F. F. Craig

In some respects, forward combustion (alias: fie-flooding, underground combustion, in-situ combustion, dry combustion) is an efficient oil recovery method. For example, its displacement efficiency (as much as 95 percent in reservoirs with high porosity and high oil saturation) is good. In its use of heat, however, forward combustion is grossly inefficient. Most of the heat generated during forward combustion is wasted. About one-fifth of the heat is picked up by the incoming air and re-used (regenerated); the remainder is left behind the combustion zone and ultimately is lost. Compressed air is expensive, and heat generated from compressed air via underground combustion is too valuable to be thrown away. Improvement is needed. Since the early 1950's, improvements in forward combustion by addition of water injection have been discussed, particularly in the patent literature, with increasing frequency.'-'' These concepts are based on the fact that relatively inexpensive water can be used to pick up much of the heat that is ordinarily wasted during forward combustion, and transport it forward to a more useful place, thereby reducing the amount of air required to move a heat front through the reservoir. Several approaches have been proposed. Merriam and Squires1 taught that a combustible (fuel) gas should be injected along with the air and water. This, however, would give at least a tendency toward reverse combustion instead of forward combustion, and would reduce the velocity of the heat bank, defeating the primary purpose of the water injection. Pelzer2 described primarily a batchwise method of forward combustion and water flooding. He advocated burning part way through a reservoir with forward combustion, then switching from air to water injection alone to push the heat toward the producing wells. Though possible, this method has serious disadvantages, the major one being that, by the time water injection is started, much of the heat has been irretrievably lost to the overlying and underlying formations. We have described what is considered a practical Combination Of Forward Combustion And Water-flooding (COFCAW).3,4 Air and water are injected simultaneously (or alternately) after a small heat bank has been formed by forward combustion. Some of the injected fluid fills up the region behind the heat bank; the rest enters the heat bank. Upon encountering heated rock, the water is converted into steam, which then flows ahead of the combustion zone and displaces much of the oil in place. Only enough air is injected to provide heat for vaporization of the water and to compensate for reservoir heat losses. Since the size of the heat bank is minimized, heat losses also are minimized. Because of more efficient oil displacement ahead of the combustion zone, fuel consumption is reduced. Too, unlike a forward combustion zone that cannot move until all fuel at a point has been consumed, COFCAW leaves some

Jan 1, 1970

Who's Who in Mineral Engineering 1977 - SME Membership Directory of the Society of Mining Engineers of AIME

Jan 7, 1977

By Paul E. Melancon, Vincent C. Kelley, Dale F. Kittel

Uranium of the Grants region occurs predominantly in continental sandstones of the upper part of the Jurassic Morrison Formation, but significant lesser deposits are found in limestone of the Jurassic Todilto Formation and in black shale of the Cretaceous Dakota Formation. The deposits are disseminations that form runs ranging from a few hundred tons to several million tons. The ore consists mainly of uraninite, uraniferous carbonaceous material, coffinite, and such secondary oxidized minerals at tyuyamunite, carnotite, and uranophane. In sandstone, the ore runs were locallized by mudstone, interstitial carbonaceous material, and primary sand channel trends. In limestone, ore deposition was related to folds and fracture zones. The great bulk of production has come from the Ambrosia Lake mines in the Grants district and the Jackpile and Paguate mines in the Laguna district. The ores, which generally have been 0.20 to 0.30 per cent U3O8, are treated at mills operated by Kerr-McGee Corporation, Homestake-Sapin Partners, and The Anaconda Company, all in the Grants district. In 14·years after discovery in 1950, the deposits had yielded concentrates valued in excess of $800,000,000. Since deposition of the Jurassic host rocks, a geologic history involving tilting, faulting, erosion, changing ground-water environments, and oxidation has considerably influenced the existence and character of the deposits. It is evident that their ongm is not simple. However, a degree of agreement appears probable for a pre-Dakota age for the original ore runs, and, at Ambrosia Lake, two principal stages of ore formation, separated by Laramide faulting, are recognized. All earlier ores have been modified by Quaternary oxidation, solution, and enrichment during which time much secondary tyuyamunite, metatyuyamunite, carnotite were formed.

Jan 1, 1968

By J. T. Ryan

SAFETY practice or the elimination of accidents in our coal mines is specifically a problem of management. It cannot be delegated to any governmental agency except that the various coal-producing states do and should have some minimum safety standard laws. However, the legislative method of attempting to control mine accidents is ineffective because of the delay between the necessity and the action. It will always be impossible to keep our various state mining laws up to date; and when the law says you must do a certain thin there is a tendency to do this and no more. Unless the scheme for setting up state regulations is so flexible that when a new hazard develops it can be immediately and adequately covered and the whole responsibility for accident elimination placed undivided on the

Jan 1, 1937

By A.S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130°F. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric Pressure and by heat transferred to it from rock at high temPerature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. Methods Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1943

By A. S. Richardson

AIR conditioning, or air cooling, for the improvement of ventilation in the Butte mines has come into increasing use during the past 10 years. In part, the methods practiced have been described in previous publications of the Institute, but some improvements on earlier methods have been made and a number of new features have been developed. This paper is presented as a record of progress made, and for the sake of completeness describes all general features of the work. The need for air conditioning in the ventilation of mines in the district arises from the fact that the temperature of the ground and mine water has shown a very great increase with increase in mining depth, and has now reached a maximum of slightly over 130°F. The most difficult part of the ventilation problem is the maintenance of temperature and humidity of a satisfactory standard in the working places, especially on the lower levels. Although ordinary ventilation is adequate to maintain good conditions in most of the working places it is subject to a number of limitations at great depth. Most important among these limitations is that with increase in depth the air becomes heated before it reaches the working places, both by compression from increase in atmospheric Pressure and by heat transferred to it from rock at high temPerature, so that its capacity for lowering temperatures is greatly reduced before it reaches the operating zone. Increasing depth of mining also increases the distance traveled by the air in its passage through the mine, and this causes a corresponding increase in resistance to air flow, so that there is greater difficulty in maintaining even the same volume in circulation. Thus, in the face of a demand that the ventilating system have a very much greater capacity to remove heat from the mine, the tendency is for that capacity to diminish. The only evident alternatives were (I) the opening of additional air shafts to increase the volume of air in circulation, (2) an extension of the existing system that would be subject to the same limitations, or (3) the adoption of an entirely different method such as air cooling. Fortunately for an economic solution of the problem, the mean annual temperature of the surface atmosphere at Butte is about 40°F., with very low relative humidity in summer, so that there is unlimited natural cooling power at a temperature range adaptable to air-conditioning methods. Methods Two similar methods of air conditioning are used, as necessitated by service requirements and dependent upon the equipment available. In one, which is the more important and has the greater cooling capacity, water is circulated in a closed circuit, and, alternately, first absorbs heat from warm mine air and then dissipates it in the surface atmosphere by cooling at a cooling tower. The second

Jan 1, 1943

By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By Robert Gilman Brown

The original power-plant of the Standard Company has been described* by Mr. T. H. Leggett, late president and manager of the company; but since the presentation of his paper considerable additions have been made, which will be found interesting because of the engineering features involved and of the attainment of a high degree of flexibility with the inflexible, two-wire, alternating system of electrical transmission. Although these additions have been completed during the last year, they constitute, to a large extent, only the carrying out of plans that belonged to the original conception of the installation. The regular operation of the water-power through the winter proved very difficult; there was a considerable length of ditch to be kept open, and, as the stream is small and any freezing night may stop the whole flow of water, there was the .additional trouble of having no reserve to draw upon. The rule for the winter is, that after a night of hard frost water begins to move in the canon before noon on all but the coldest days. To obviate the nuisance of the anchor-ice, and to make available all of the water, a dam of sufficient height to impound several days' run of water has been built across the canon, 3875 feet above the power-house, and provided with pressurepipe well below the surface. In place of the 1571 feet of pipeline from penstock to power-house, there has been substituted a line 3875 feet long to bring water direct from the dam. The dam is of logs, cribbed up in squares of about 12 feet, ballasted with earth and rock and sheathed on the water-face with 3-inch plank.

Jan 1, 1897

By Sydney H. Ball

AMERICAN consumption of industrial diamonds has increased five fold in the past 25 years and today accounts for 15 to 20 percent of the world's sale of rough diamonds. In another decade the value of industrial diamonds sold may well equal or exceed that of gemstones. It is generally understood that industrial diamonds are one of the strategic minerals being stocked by the Government in the present crisis to ensure rapid and efficient armament production. Diamond die making is a trade largely confined to artisans in Switzerland and in certain parts of France. Today, in addition to turning out pilots, we should train expert artisans in diamond die making, for thousands of miles of tremendously small-gauge wire will be needed to make the instruments by which the efficiency and safety of these pilots is assisted.

Jan 1, 1941

By B. M. Larsen, T. E. Brower

For some years we have been carrying on a rather comprehensive investigation of the occurrence of oxygen in liquid open-hearth steel. This investigation was interrupted by the war emergency and is therefore incomplete, with many questions still answered only partially, if at all; yet it seemed worth while to present a report of progress on this difficult field of research, if for no other reason than to promote discussion and further investigation of this important problem. The significance of such studies depends in large measure upon the accuracy of measurements of oxygen content in liquid steel while it is still in the furnace or as it flows into the ladle, or thence into the mold and there is, as we shall show, good reason for believing that the main source of uncertainty is in the sampling, not in the analytical method as such. The difficulty arises from the fact that any method of sampling is of itself apt to alter the amount of oxygen in solution in the liquid steel, because this oxygen is in a readily reactive condition. On the one hand, being usually present at a concentration appreciably in excess of that corresponding to equilibrium with the carbon then present, it may decrease rapidly in percentage by reaction with carbon and evolution of CO, especially if the liquid metal is in any way shaken or brought in contact with a cooler solid surface. On the other hand, it may increase rapidly by ab- sorption of oxygen from a slag, a furnace atmosphere, or from air. These circumstances, which are inherent in the problem, as well as our conclusion that, despite the considerable amount of careful work already done, there is still no method of sampling liquid steel acceptable as an unquestioned standard, ed us to undertake systematic comparisons of oxygen content of large numbers of samples taken: (I) by a single method at different positions and levels in the bath; (2) at the same place by different sampling methods; and (3) from bath, tapping stream and pouring stream. The different sampling methods yield somewhat different values and there is as yet no way to tell with certainty which is the most accurate. But the general reproducibility and consistency of the results give us some confidence in certain inferences we draw from them: namely, that the "spoon" method of sampling, properly carried out, gives somewhat more consistent results than the "bomb" method, as it has usually been practiced; that, in the bomb method, an aluminum cap is preferable to a steel cap; that the oxygen content of liquid steel in a finished heat is substantially the same all over the bath at the same level, and tends to decrease at lower levels further from the slag interface; also that it tends to decrease, and to decrease erratically, from furnace bath to tapping stream entering the ladle. Accordingly it seemed desirable to report these observations in detail as a first step, so that the reader may judge their significance as a contribution towards solution of the main problem, which is to find a means of pre-2

Jan 1, 1945

By Thomas T., Read

E DUCATION for the mineral industry was at first a single comprehensive curriculum, but it was early recognized that the main basis of mining is physics, while that of metallurgy is chemistry. The first school to offer curricula leading to degrees in mineral industry education in the United States (1853) had separate ones in mining and metallurgy. The Columbia School of Mines (the first really successful one) had only a single curriculum when it opened in 1864, but within a few years had so reorganized its work that it offered curricula in mining, metallurgy, geology, chemistry, and civil engineering. Interest in the metallurgy or geology curricula was slight at first, and for the next 30 years the great majority of Columbia students took the mining curriculum, probably partly because it contained nearly as much geology as the geology curriculum, practically all the metallurgy, and most of the chemistry, and partly because of the degree awarded for it. Other schools kept their mining curricula equally broad, and as late as 1900-1910 men were graduating as mining engineers who were practically as well prepared to make geology or metallurgy their life work, as they were for mining. Gradually, however, the subject matter of mining geology and metallurgy became so enriched through research and development that separate curricula in them became worth while; their progressive development is the subject of another chapter. Mining curricula also began to be somewhat diversified, and schools in areas where coal mining was of outstanding importance began to offer options in coal mining, the earlier curricula having been chiefly aimed at metal mining. The petroleum industry began its meteoric rise about the same time as mineral instruction in this country, but little more of applied science attended its birth than had attended such ancient practical arts as copper and iron

Jan 1, 1941

By E. R. Kaiser

COAL research during 1942 was directed in an important degree toward the solution of problems of wartime importance. A wider selection of coals for carbonization to meet the increased demand for coke, and the improved utilization of lower-grade coals for boiler fuel were made possible by fundamental studies on cod and ash behavior that had been started several years ago. The coal industry's interest in the work of the various laboratories brightened significantly as results were demonstrated on smokeless combustion in stoves, on stokers without coke trees, and on pulverized firing of forge furnaces. Despite the limitations of priorities and scarcity of materials, the mineral industries building of the West Virginia University was completed and equipped with facilities for research on coal min

Jan 1, 1943

By AIME AIME

THE PAPER, "Surface Effects on Assay Beads Caused by Metals of the. Platinum Group," presented by J. L. Byers, before the Institute of. Metals Division at the February meeting of the Institute, is the subject of interesting discussion, an abstract of which follows. The original paper is available at Institute headquarters as a Preprint. Member-What assurance have you that the percentage of metals, as stated, is really an accumulation?

Jan 1, 1932

By Thomas D. West

The occasional reports of progressive furnace-men, giving the results of physical tests to prove the superior qualities of their pig-irons, have encouraged the writer to believe that the time is ripe for the discussion of such work, and the inauguration of some correct system by which the furnace-man and the founder could make intelligent comparison of the elements of strength, deflection, contraction, and chill presented in pigmetal. In most cases the physical tests now made by furnace-men define but one quality in the iron, and are generally too vague to permit any true comparison. For example, one furnaceman tells us he can punch holes in his cast-iron, wishing it to be inferred that the iron is very soft and strong. Another furnace casts a long wedge, the thin end running to a knife's edge, which is supposed to prove the fluidity of the iron, for the founder's benefit. Another casts in square-cornered " chills," to define the hardness or softness of the metal. To the writer's knowledge these tests are not advocated by their originators as suitable for standards; and they are, to his mind, but evidence of unrest on the part of progressive furnace-men, who feel that something should be done in the line of physical tests. The writer knows of no furnace-men who make and keep records of the strength of their iron obtained by means of tests made on recognized standard testing-scales ; but he does know of a prominent furnace-salesman, who, not long ago, came into possession of a 1-inch square bar that stood 1400 pounds

Jan 1, 1897

By J. R. Stone, G. D. Storm

Design features and operating methods of ASARCO's new unit for the continuous melting and casting of tough pitch copper at Perth Amboy are described. Preliminary studies made for determinitzg economic feasibility and design details are also presented. Cathodes are preheated with oil and melted in an electric furnace at 40-ton per hr rate, from whence the molten copper is fed simultaneously to the wire bar casting wheel and the continuous casting of cakes and billets. In the early 1950's the copper refining furnaces at ASARCO's Perth Amboy plant reached a point where major expenditures would have to be made for replacement of the furnaces and the auxiliary equipment. The problem was whether to continue with the standard reverberatory furnaces or to consider continuous melting in electric furnaces. Reverberatory furnaces have been used for years in the copper industry and for some 50 years at the Perth Amboy plant. Reverberatory melting practice, however, imposes certain restrictions. First, labor costs are high, usually requiring three shifts per day. Secondly, they operate on a batch basis, the conventional operation being a 24-hr cycle including

Jan 1, 1961

By R. H. Lee

WITHOUT doubt, one of the most frequent and serious annoyances connected with the practical running of a blast-furnace, especially in single-furnace plants, is caused by low steam, in spite of the fact that all boilers at blast-furnaces have grates for burning coal, and that coal is more or less continuously burned upon them, from three to a dozen men being pretty constantly engaged around the boilers as firemen or coal- and ash-handlers. At times, when the furnace is ? tight," all available men are put on to assist the regular firemen; yet sufficient steam cannot be got to keep the engines up to their regular number of revolutions, while the stoves, deprived of the gas which has been sent to the boilers, run cold, so that, when the furnace loosens-up and resumes the regular rate of driving, the blast is very considerably below normal temperature, and a.' cold," or at best a " high-sulphur," east is the result. Again, it often happens that a furnace, running at its best, becomes temporarily a little too hot; the pressure rises; the amount of gas made' is diminished; the steam soon commences to go down; and a small scaffold is likely to form before the furnace has been brought back to the proper rate of driving, and thus enabled to take its regular amount of blast. The usual remedy is either to "jerk" the furnace by a sudden, brief intermission in blowing, or to cool the furnace by lowering the heat of the blast; but if the lower blast-temperature be maintained too long, the hearth and descending stock may be cooled below the " critical temperature " mentioned by Mr. .Johnson, and the furnace may go to the other extreme, and become cold. This is especially the case when coal or coke, high in sulphur, is used:

Jul 1, 1906

By Henry S. Washington

I. INTRODUCTION. DURING the last twenty years or so the chemical investigation of rocks has made great advances, and it is now generally recognized that a knowledge of the chemical composition is as essential as that of the texture or mineral composition-if not more so-for the proper classification of rocks and study of their origin and relationships. Rock-analyses have vastly increased in numbers and, what is of greater importance, in quality. New and improved methods permit of greater accuracy than was possible in the early days, and the list of chemical constituents frequently determined has risen from the seven or eight of the greater part of the nineteenth century to twenty or more. Indeed, rock-analyses with determinations of so many constituents are now commonly made by the chemists of the United States and Australia, while in Germany, Great Britain, France, and Italy the rarer constituents are determined more frequently than formerly. As a consequence of this modern, accurate work, it has been discovered that some elements which were formerly supposed to be rare are of wide-spread occurrence and are often present in considerable amount. The fact is further being developed that the elements tend to show certain relations of occurrence or abundance in connection with each other. This is a fact which is applicable to the rarer elements, and which also finds a broad geological and petrological expression in the recognition of petrographic provinces. We are beginning to obtain some definite, though as yet rudimentary, knowledge of the distribution of the elements among igneous rocks. Some of the results along these lines obtained by study of the vast accumulation of analytical data now available are well known to petrologists, while others do not seem to be so gener-

Sep 1, 1908

By George C. Heikes

ALTHOUGH the application of light metals in war materiel increased during the year, based on the number of uses, the trend in aluminum and magnesium production in 1944 was characterized by a sharp decline in the production of both metals accompanied by a further accumulation of large Government reserve stocks. Several primary reduction plants were curtailed to prevent building excessive inventories. By the end of the year, however, a lively revival of war production took place when resistance stiffened on the western front in Europe. Production of primary aluminum ingot was reduced from over 90,000 tons per month at the start of the year to 45.000 tons per month by the end of the year.

Jan 1, 1945

By L. K. Eigenbrod, F. Notaro

Enactment of Public Law 91-173 (Federal Coal Mine Health and Safety Act of 1969) has placed new responsibilities on the mining industry. The new law, aimed at eventually solving the problem of pneumoconiosis, sets new respirable dust standards at 2 mg per cu m. Techniques employed to date have been shown to lack total effectiveness in meeting the prescribed standards. Since it is possible that even the new standards will eventually have to be lowered to effectively attack the medical problem, the need for new and more reliable methods of assuring clean respirable air will intensity. This paper presents, in a preliminary manner, both the present technical capability and growth potential of cryogenic technology for supplying miners with clean breathing air. Work with two sizes of prototype supplied-air (cryogenic-liquid) respiratiors in Union Carbide's Fawn Coal mine, will be described. Other potentially fabricable systems will be discussed and a preliminary assessment made of the potential cost of introducing cryogenic air breathing systems in coal mine service.

Jan 1, 1972