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Jan 1, 1922

Jan 1, 1922

By Robert Wamsley, W. E. Jones

ONE of the earliest problems in the life of any community is the provision of an adequate supply of water sufficiently free from all types of contamination to be suitable for domestic purposes. Generally speaking, the location of most communities is determined to a great extent by the availability of an adequate supply of satisfactory water. For a mining camp, that consideration cannot be foremost. Here, the ore takes first place, and the men who mine it must do the best they can under the existing conditions. If there is no local source of water, it must be brought from some distant source or must be found by sinking shafts or drilling wells. Fortunate indeed is the mining company that discovers a commercially valuable ore deposit beside a never failing creek full of pure water, with sufficient water rights available, because the acquisition of water in any other manner nearly always involves not only a considerable period of time but the expenditure of considerable money. The experience of Climax Molybdenum Co. demonstrates the measures that sometimes are necessary in order to provide a suitable supply of water. The Climax mine and mill are on the Continental Divide, about 13 miles northeast of Leadville. The elevation of the domestic part of the camp varies from a minimum of 11,320 ft. to a maximum of approximately 11,550 ft. above sea level, and, as is common at such altitudes, the near-by streams that might be suitable for a water supply are small and intermittent, usually flowing only during the summer months. The only streams of any size in the immediate vicinity of Climax are the Ten Mile and Arkansas Rivers. The headwaters of Ten Mile River are on the Company's property, and its water has been used for the domestic supply. The headwaters of the Arkansas River are about 2 miles distant and have not been used as a source of supply by the company. During the past 11 years of the production of molybdenum at-Climax, the number of families living there has increased from about 45 to 283, and the population has increased from about 200 to 1200 persons. Consequently, the capacity of the water-treatment facilities, and the amount of water available, had to be increased to meet the requirements of the camp. As early as 1932 it was recognized that the water in Ten Mile River would not continue to be adequate for domestic purposes and after considerable discussion it was decided to drive a drift through the major fault in an effort to find additional water. This drift was completed in 1935 and tapped sufficient water to make the supply adequate. This water was treated in a tank underground, where lime was added, and was then piped into the domestic supply lines. At about the time this line was completed, the presence of fluorine in harmful concentrations was discovered in the water. This problem was submitted to the International Filter Co. and in November 1937 a plant of its design was put in operation for treating the water to remove the fluorine. This plant proved entirely successful,

Jan 1, 1945

By RAY LYMAN WILBUR

SINCE boyhood I have had a keen interest in mining engineering. To see the prospector with his pack outfit and his pan, followed by the assayer and the trained engineer, has always had -something of the lure of romance for me. It is appropriate that the American Institute of Mining and Metallurgical Engineers should hold a general meeting in California, since this State has long been a home of mining engineering. Here, after the early open methods of mining, it has been necessary for the universities to train men in geology and mining, so that the earth could be penetrated and the rich ledges opened. In the eighty years in which the mines of California have been offering experience to the miners of the world, we have seen mining engineering evolve from a comparatively simple art, covered largely by rule of thumb, into a complex group of specialties, each utilizing the very latest discoveries in the various fields of physical sciences. Mining, too, has become a great business requiring large financial support and the most careful handling. Those mining engineers who have applied new processes in special fields have thus been able to give a wide-flung range to their activities in all parts of the world. The hand of nature in distributing minerals over the surface of the earth has compelled the mining engineer to become a modern pioneer, facing the heat of the tropics as well as the frozen regions of the north. There has been a marked cosmopolitan aspect to mining engineering, since the engineer had to go wherever the prospector discovered favorable leads. This has meant dealing with the harshest of conditions, the handling of labor of all sorts, the control of sanitary conditions, and relations to all forms of transportation. Naturally this has called on some of the very best minds in all countries to unlock the stores of hidden wealth. To make them available for civilization has been the job of the mining engineer.

Jan 1, 1929

By W. C. Ellis, E. S. Greiner, M. E. Fine

C. H. Samans and W. R. Ham (Chicago, Ill., and Dix-field, Maine, respectively)-—For several years we have been studying transitions of this basic type in metals, alloys, glasses, etc. Usually, however, they are not so clearly marked as those which the authors have found, and hence are much more difficult to determine accurately. Since our studies indicate that most of them occur virtually unchanged (as far as temperature is concerned) regardless of the form in which the element appears, we believe that they are a characteristic of the atom. Specifically, we believe that there is an additional rotational degree of freedom possessed by the nucleus which has not been considered heretofore. This nuclear rotation is made up of several components, each related to the several quantum shells of electrons. In chromium there are four of these shells and hence four separate series of characteristic transition temperatures. The lowest temperature at which any transition occurs, based on the present state of our computations, is 125°K, 4° higher than the authors' value of 121°K. A convergence of this series, we believe, shows up at the higher temperature of 2085 °K, surprisingly close to the transformation temperature of 2103°K recently announced by N. J. Grant of M.I.T. for a body-centered to face-centered transformation in chromium. Likewise, our computations indicate a temperature of 311°K for the second transition temperature, reported by the authors as 310 °K. A convergence of this series, we believe, shows up at a higher temperature as the melting point at 2163°K. Although our work on these series must, in a sense, still be regarded as empirical, since we do not understand fully as yet just what the series mean, it is based on a reasonably firm picture. The individual constants, from which the various series are computed for each element, comes directly from the X-ray K absorption limit. Furthermore, the same basic method has accounted for transformation and melting temperatures in about 50 of the chemical elements, which is all we have tried thus far. In many cases the only known transformation is the melting point, but in others the occurrence of transformations or other transitions, equally as well marked as those of the authors, has been pointed out by others. These observations have assisted us greatly. Consequently we were very pleased to see the authors' excellent work in finding these two transitions in chromium. With these confirming data, our picture of this element is clarified considerably, so we expect that at least some of our work can be published in the near future. R. C. Ruder (E. I. du Pont de Nemours & Cu., Wilmington, Del.)—The authors' interpretation of these transitions in terms of 3d to 4s electronic structure transitions is most interesting. It would be interesting to have additional experimental evidence of such transitions from the temperature dependence of the Hall coefficient in the neighborhood of the property changes discussed in this paper. Simple theory15 suggests the Hall coefficient as a measure of the free electron (or s electron) concentration per unit volume. It has been shown that for paramagnetic'" and ferromagnetic1? metals the simple theory is in fact too simple. However, the existence of a discontinuity in the Hall coefficient would provide information which should aid both in our understanding of these transitions and the significance of the Hall coefficient in these metals. It was rather surprising that no significant paramagnetic effects were observed. In this connection the recent work of McGuire and Kriessman18 is cited. They measured the magnetic susceptibility of chromium from 20" to 1460 °C. They also observed no large change in the susceptibility although there might be a change in slope in the vicinity of the 40 °C transition. The existence of these 3d to 4s electronic transitions has been discussed in connection with the paramagnetic susceptibility behavior of nickel and nickel alloys.'"-" Assuming a correspondence principle between classical and quantum mechanical paramagnetic theory and using classical theory to calculate the effective Bohr magneton number from the Curie constant for substances obeying the Curie-Weiss law," it is found that the effective magneton number is a function of temperature. The process of calculation involves the inverse of the differential of the 1/x4 vs. temperature curve so that good and numerous data are necessary to obtain significant results. The data of Fallot23 show a discontinuous increase of about 12 pct in the effective magneton number between 850" and 900 oC, followed by a continuous increase up to the melting point. The data of Sucksmith and Pearce24 show a possible 8 pct increase. The older data of Terry25 and Weiss and Foex26 show a continuous increase. It is possible that small amounts of impurity atoms change these electronic transitions significantly. Fallot's23 data on a nickel alloy with 4.5 atomic pct Fe indicate that the discontinuity occurs around 1300 °C. Systematic investigation of the transition metals for transitions of this nature should provide information which would be very valuable for our understanding of these metals. The absence of antiferromagnetic structures in chromium has been shown by Shull27 using neutron diffraction techniques. M. E. Fine, E. S. Greiner, and W. C. Ellis (authors' reply)—The remarks by Drs. Samans and Ham are certainly very interesting, in particular those pertaining to the close agreement between the theoretically calculated values for transition temperatures in chromium and the experimental values reported by a number of investigators. This is a remarkable achievement and we shall look forward to a more detailed presentation of the method followed in their calculations. We do not believe that the transition in pure chromium near 40 °C remains temperature invariant with alloying, as was reported by Samans and Ham for a number of the substances that they studied. We have not done any work with alloys but base our belief on the results of earlier studies in which less pure chromium was included and considerably lower transition temperatures were observed. The transition tempera-

Jan 1, 1952

Edward Dyer Peters, the only child of Henry Hunter Peters and Susan Barker Thaxter, was born in Dorchester, Mass., June 1, 1849. From his father he was a descendant of the Peters family of Ipswich and Andover, Mass., whose earliest ancestor settled in Essex County in 1659; while upon his mother's side he descended from several old Hingham families, as well as from the Quineys and from Governor Bradford. Between the ages of fourteen and sixteen he was a student at the Episcopal School for boys in Cheshire, Conn. Near the school was an old tin mine, and he used to spend his Saturday afternoons exploring it. When Edward was sixteen, his father sold his property in South-borough, and for the next three years lived in Europe. Sept. 26, 1865, Edward entered the Royal School of Mines at Freiberg, Saxony. In the summer of 1867 he joined his family on Lake Geneva, and spent a part of the season in that vicinity, going to Chamounix and taking other trips. Extract from a letter to his father: Elbingerode, Harz, Aug. 30, 1868: I left Freiberg with my friend Lilienthal, on Wednesday the 19th of August, reached Leipzig in the evening and spent the night in that city: the next morning we took the cars and in the afternoon reached Eisleben, in Prussia, which was to be our first stopping-place; there are immense copper-mines and smelting-works at this place, and the method of working the mines is very peculiar ... The next morning we got up at five and spent the whole day in the smelting-works where I obtained a number of drawings of the furnaces they use here and a good many valuable data. Saturday morning we got up at four o'clock, and descended a mine about three miles from the town; the Director of this mine was one of the most intelligent and agreeable men that I ever met; he accompanied us in the mine and explained everything that was new to us. The system of mining at Eisleben is peculiar to this town, and is not used at any other place in the world; the copper ore comes in narrow, flat veins eighteen inches high, at the utmost, consequently the men work lying flat on their left side and using the pick with both hands: the ore is carried out of the side passages into the main ones, in very low waggons about twelve inches high, and four by two feet; the boys who pull these waggons have a board buckled to their left thigh and their left arm; they pass their bare foot through a strap in the waggon and wriggle along on their side dragging the waggon after them, with their foot, almost as fast as a man can walk above ground. In the afternoon we walked over to Hittstadt, about twelve miles, and remained there Sunday and Monday. Monday night, at ten o'clock we went out to one of the smelting-works, to see the refining of the copper; this is only done at night, so we worked there from ten in the evening till eleven the next morning, and came home all blackened up and with blistered hands, for our skin was not quite so tough as that of the workmen: at noon the same day we took the stage to Ascherls-leben, and then the train to Stassfurt, where there are immense salt-mines, as well as factories for the manufacture of bromium, which latter process is, however, kept a profound secret, so we had very little hope of seeing anything but the salt mines; we were talking with our landlord about our disappointment, that evening, when he told us that the director of the Bromium works was sitting in the next room with no company but his glass of beer, so we went over to him, introduced ourselves as Americans, and actually succeeded in persuading him that it could do his business no earthly hurt if he showed us his works; at last he consented, after making us give our word of honor

Jan 1, 1919

By K. Sallmann

Spurred by a variety of factors, coal flotation is making headway among the preparation plants of West Germany. The author gives some statistics on German coal flotation plants and information on the properties of the feed and quality of the derived products. Types of machines and reagents used, dewatering practices, tailings disposal, and thickening operations are covered. There is special emphasis on the many-sided problems that confront German coal preparation engineers. The coal mining industry of West Germany is concentrated in three coalfields: the first on the Ruhr and the Rhein rivers, the second on the Saar river, and the third near the frontier between Germany and the Netherlands, around the towns of Aachen and Erkelenz. The total run-of-mine production of these three coalfields amounts to 736,000 tpd which come from 145 collieries. There are 121 washeries, 43 of them with a flotation plant. The total throughput of these 43 washeries is 280,000 tpd, out of which 26,000 tons (9.3 pet of the washery feed coal) are cleaned by flotation. The capacity of the individual flotation plants varies within relatively wide limits, the average being 40 tph and the capacity of the largest flotation plant being 120 tph. During the last few years, the number and size of flotation plants have been steadily increasing, although flotation must be looked upon as an expensive and rather complex cleaning process. The considerations which have led to the widespread application of flotation may be summarized as follows: 1) In making coking coal, it is seldom possible to add uncleaned fines to the coke oven charge, as their ash content is too high. If, however, the ash content of the fines is reduced to a maximum of 7 or 8 pet, they can be admixed to the washed and crushed small sizes without difficulty. This means, naturally that revenue is increased since the price of coking fines is always higher than the price for dust or uncleaned wet fines. 2) To prevent silicosis and pneumoconiosis, water infusion and spraying of the coal are practiced much more today than ever before. As a result, moisture content of run-of-mine coal has markedly increased and the washery feed coal contains more and more slurry instead of dry dust. The price of slurry, how- ever, is very low, and in many cases it is impossible to sell filtered raw slurry with a moisture content of 20 to 25 pct and, at the same time, 20 to 25 pct of ash. Reduction of the ash content of these slurries improves the possibility of dewatering them and, in this way, also enhances the marketability of this product. 3) The new severe laws and regulations against pollution of air and rivers make it necessary to de-dust coal better than in the past and to reduce the quantity of the waste water from coal preparation plants and their solids content to a minimum. 4) Even if there were no compulsory reasons to clean the fines, flotation will often lead to an increase in the overall yield. Although not the only application, it appears that the treatment of coking fines is the primary field for the flotation process in coal preparation. It must not be overlooked, however, that a series of arguments may be advanced against flotation: 1) Flotation is an expensive process because, in addition to the cleaning operation itself, the dewatering of the froth and the disposal of the tailings is very costly. 2) Operation of a flotation plant requires well trained personnel. 3) Filtered froth has about a 20 pct moisture content and, therefore, if mixed with the cleaned small coal it causes an undesirable increase in water content of the coke oven charge. For this reason it is necessary to take additional measures for dewatering washed small coal and this, of course, entails additional expense. 4) Disposal of flotation tailings involves very difficult problems, particularly in the highly industrialized regions. An investigation covering 32 flotation plants of Western Germany shows the following composition and properties of their feed:

Jan 1, 1961

By H. J. Ramey

Conventional calculation of total system isothermal compressibility for a system containing a free gas phase involves, among other things, evaluation of the change of oil and gas formation volume factors and the gas in solution with pressure. Preferably, this information should be obtained from laboratory measurements made with particular oils and gases. Often, experimental measurements are not available. In this case, it is necessary to obtain pressure-volume-temperature relationships from general correlations such as those of Standing' for California oils. In order to speed estimates of compressibility, generalized plots have been prepared of the change of both oil formation volume factors and gas in solution, with pressure from Standing's correlations. A generalized plot for estimating the change in the two-phase (oil and gas) formation volume factor with pressure is also presented. Usually, the effect of gas dissolved in reservoir water upon the total system compressibility is neglected for gas saturated systems, due to the low solubility of gas in water. Results of this study indicate that the increase in total system compressibility caused by solution of gas in water is often as large as the compressibility of wafer, and can be magnitudes larger for low pressure systems. Generalized results for estimating the change of gas in solution in water with pressure are presented in tabular and graphical form. INTRODUCTION During the past decade, pressure build-up and drawdown techniques have gained an important place in reservoir engineering. Build-up and drawdown analyses are only two special applications of the broad field of transient fluid-flow theory. All solutions of transient fluid-flow problems contain a parameter called the total system isothermal compressibility. This property of fluids and porous rock is a measure of the change in volume of the fluid content of porous rock with a change in pressure, and it may vary considerably with pressure. Evaluation of total system isothermal compressibility is not difficult, but it is tedious and time-consuming. Often compressibilities are estimated roughly, or transient flow methods are neglected completely. The benefits of using accurate system compressibility in properly-executed build-up or drawdown analyses are: 1. Better planning of pressure build-ups may be achieved to avoid unnecessary loss of revenue due to excessively long shut-in periods, or to shut-in periods too short to yield useable data. 2. Better and more reliable estimates of static formation pressures for reserves estimates and rate performance estimates. 3. Reliable information for evaluation of well completion effectiveness, and planning and interpretation of well stimulation efforts. The purpose of this paper is to clarify the nature of the total system isothermal compressibility, and to present useful methods for estimation of compressibility, particularly for systems containing a gas phase. DEVELOPMENT Numerous publications have presented solutions to transient single-phase flow of slightly compressible fluids, stressing pressure build-up applications. In transient flow, a compressibility* term arises to permit volume content of fluids in porous rock to change as pressure changes. The basic nature of the compressibility term is usually taken for granted. Problems arise in practical applications of transient fluid theory because most published works consider only one flowing fluid—in an ideal porous system containing only one fluid. In 1956, Perrine2 presented an intuitive extension of single-phase flow pressure build-up methods to multiphase flow conditions. Later, Martin- established conditions under which Perrine's multiphase build-up method had a theoretical foundation. Perrine has shown that improper use of single-phase build-up analysis in certain multiphase flow situations can lead to gross errors in estimated static formation pressure, permeability and well condition. It is likely that, much pressure build-up data for oil wells should be analyzed on the basis of multiphase flow. For both single-phase and multiphase build-up analysis, the isothermal compressibility term in dimensionless time groups often should be interpreted as the total system compressibility. All real reservoirs contain one or more compressible fluid phases. In addition, rock compressibility can contribute in an important way to the total system compressibility. The proper total system compressibility expression may contain terms for compressibility of oil, gas, water, reservoir rock and terms for the change of solubility of gas in liquid phases.

Jan 1, 1965

The Nominating Committee for Institute Officers in 1953, John R. Suman, chairman, completed its work at the Annual Meeting in February, and has made its report to the Board of Directors. The President-Elect in 1953 serves as President in 1954. The ticket follows: For President-Elect and Director, Leo F. Reinartz; for Vice-President and Director, A. B. Kinzel and Lloyd E. Elkins; for Director, Hjalmar W. Johnson, Philip Kraft, Gail Moulton, Edwin L. Oliver, Philip Wilson, and Elmer Isern. Mr. Reinartz is a vice-president of the Armco Steel Corp., Middletown, Ohio. As required by the bylaws, brief biographical sketches of the nominees will be published in the July issues of the journals.

Jan 1, 1952

THE annual meeting of the Arizona Section was held at the Pioneer Hotel in Tucson on Dec. 10, 1951. Registration and ticket sales for the social functions started at 8:00 am and lasted throughout most of the day. There were 489 registrations, consisting of 216 members, 64 students, and 209 guests. Chairman Harrison Schmitt opened the Mining Geology Div. meeting and a short business session was held at which Dr. Charles Anderson of Prescott, Ariz. was elected chairman and Seton Williams of Tucson was elected secretary for 1952. Dr. B. S. Butler was program chairman with R. B. Mulchay as co-chairman at the technical program. Eldred Wilson spoke on Oxidation and Water Levels at Some Arizona Mines. George Kiersch spoke about Economic and Engineering Significance of Ground Water Localization in Limestones - Big Bend Country, Texas. Harrison Schmitt gave The Definition and Use of Terms in Mining Geology. These talks were followed by discussions. E. N. Pennebaker, A. D. Wandke, and H. Schmitt gave informal talks on foreign trips made during 1951, the meeting was then adjourned.

Jan 1, 1952

Discovery of a deposit of magnetite ore estimated at 3 million tons and of quality sufficient to warrant mining has been located near Reading, Pa. by the Bethlehem Steel Corp. Last January; the company spent nearly $400,000 for about 1750 acres of farm land which had been valued at only about $50 per acre. It is expected that a pilot shaft 18 in. in diam will be sunk some time this spring. The ore body, delimited by diamond-drilling by Sprague Henwood, is said to measure roughly 2000 sq ft and 1000 ft thick, beginning 1500 ft below the earth's surface. In a continuing search for strategic minerals, the Atomic Energy Commission expects to put eight to ten diamond drilling rigs into the area 11 miles southwest of Blanding, San Juan Co., Utah early this year. The Commission's primary objective is the Salt Wash member of the Morrison formation. Holes 140 ft deep are expected to be drilled, with solid bit drilling through overburden, mudstone, shale and sandstone overlying the area.

Jan 1, 1951

By Chung Yu Wang, Guy C. Riddle

There are found in nature upward of II2 minerals containing antimony, but only a few of them, listed in Table I, can be considered as antimony ore-forming minerals. Stibnite (Sb2S3), antimony sulphide or glance, is the principal ore of antimony. The oxide ores—cervantite, kermesite, valentinite, sernarmontite—occur sparingly in nature. Dry methods are generally adopted for the extraction of the metal. Electrometal-lurgical methods have had much attention in America and Germany and have not yet found, on economic grounds, practical or extended application, except in a few places. During recent years, treatment of the poor grades of the ore, especially sulphide, by ore-dressing methods, has commanded some attention and been adopted at a few plants. The impure sulphide of antimony, resulting from the liquation process, is called lLneedle," "liquated" or "crude" anti- mony, and the refined metal itself is called antimony "regulus." The different processes for the treatment of antimony ores are shown in the diagram of Fig. I. Liquation of Crude Antimony The first step in the smelting of antimony is a simple one, the process of LLliquation," which produces crude or needle antimony. Ores containing $ 50 per cent Sb are used in the liquation process for the production of crude. The temperature required for liquation is between 550' and 600°C. Ores to be liquated are broken to about walnut size. If the pieces are larger than this, the low heat used will not penetrate' effectively, and if they are smaller the ore tends to pack too closely for adequate penetration. A packed charge also prevents the free escape of the fused sulphide. Intermittent Liquation in Crucibles The unique type of furnace that is in use in China for smelting is not highly efficient but is simple in construction and operation. The furnace is generally built

Jan 1, 1944

By Arthur S. Huey

AS the end of the collegiate year approaches, the problem of student employment again becomes acute. This subject divides itself into two phases: (1) employment prior to graduation and (2) employment following graduation. "Experience is the best teacher," according to the old adage, and the student needs all that he can get. He is afforded every opportunity to reap from his books the theories and principles of scientific and engineering practice, and occasionally he is privileged to make field trips to observe the practical side of the subject. But it is not enough for one to know the theory and to observe its application; it is also desirable for the student to get the feel of the tools during his training Such opportunities can only be afforded the student if the major companies cooperate with the universities in giving the student part-time and vacation work.

Jan 1, 1932

By A. Long, A. Silverman, J. L. Kulp

Garth Crosby has written an excellent geologic description of the deposits surrounding the Gem stocks in the Coeur d'Alene district. The ore deposits in the area of the Gem stocks may hold the key to the age and mineralization history of the entire Coeur d'Alene district. A recent isotopic study10 of the Coeur d'Alene district in this laboratory illustrates that a classical geologic interpretation of these deposits, with its implications for the whole district, may lead to erroneous conclusions. For this reason it seems pertinent to submit a summary of these results and an interpretation of the mineralizing history of the Coeur d'Alene districts. Pitchblende from the Sunshine mine has been dated as 1100-1200 million years (m.y.) by Kerr and Kulp,11 and Eckelmann and Kulp.12 This pitchblende is known to predate the major sulphide introduction in the Sunshine mine, but it clearly follows the metamorphism and folding of the Belt Series. Recently, Goldich (personal communication) dated sericite from the Belt rocks as 1200 m.y. by the potassium-argon method. This date establishes a minimum Belt age if the sericite is of metamorphic origin and a maximum age if detrital. The Belt Series, therefore, is not latest Precambrian. Lead isotope ratios of galenas have been measured and model ages calculated by Bate, et all3 for the Sunshine mine, Farquhar and Cummingl4 or the Bunker Hill and Sullivan mine, and Cannonl6,18 for a few other deposits in the district. Galenas from similar deposits in Southern British Columbia have been measured by Bate, et al,23 Farquhar and Gumming,11 and Wanless and Leech." The new work in this laboratory includes leads from ten widely scattered mines north and south of the Osburn fault, and through a vertical distance of over 5000 ft (Star mine). Included in this group are the Hercules, Sunset, and Mountain Goat mines, which are adjacent to the Gem stocks. In addition, galenas from stringers which cut the Gem stocks in the Success and Sunrise mines and the Hercules hanging wall dike in the lower western portion of the Hercules mine, were included in the study. All of the above leads, except one, give model ages of 1300-1400 m.y. for the time of segregation from the parent material. The concordance of the common lead and U-Pb ages, the great horizontal and vertical uniformity of the lead ratios, the sulphur ratios of two Sunshine mine galenas and three galenas from the Edith, Page, and Hercules mines indicating average crustal sulphur, and the U23/Pb204 ratio inferred for the original lead environment, indicate that the entire mineralization of the Coeur d'Alene-British Columbia base metal belt was derived from a deep source and emplaced in the Precambrian. One sample of galena from sulphide stringers cutting the North Gem stock at the Sunrise Prospect mine gave a modern (i.e., Tertiary) lead ratio. This mine is located at the northern tip of the stock. The presence of modern lead suggests mobilization of some rock lead during the intrusion of the Gem stocks and their outliers. Larsen et al.l8 have dated the Gem stocks as Tertiary by the lead alpha method. If Coeur d'Alene mineralization was genetically related to Tertiary magma formation and intrusion

Jan 1, 1961

By E. R. Johnson

THE copper concentrator of the Braden Copper Co. is at Sewell, Chile, on the western flank of the main Cordillera of the Andes, at an air distance of approximately 50 miles southeast of Santiago, the capital of Chile. The region is mountainous and space is at a premium because of the rough terrain and the danger of snowslides. The ore, a porphyry copper, is mined by a block-caving method in the El Teniente mine. It is hauled to the crushing plant, a distance of 2.6 miles, through a tunnel because of the severe climatic conditions. The usual large, coarsely set, primary reduction machines found in many ore-treating plants are not required because of the mining method employed and the limiting 12-in. spacing of the grizzlies at the head of each ore pass in the mine. It is the purpose of this paper to describe the numerous improvements made in the crushing section of this large flotation concentrator during the past 15 years to increase the efficiency of the plant and to raise the daily output from around 20,000 to 30,000 tons. The reader should keep in mind that all changes were made within the existing building because of the limited space and the high cost of the heavy mill construction required to withstand the snow loads. The present plant, as well as the former, operates on a 24-hr, 7 days a week basis. FORMER PLANT The crushing plant commenced operations at its present site in 1921, the main equipment being No. 7 1/2 gyratories, followed by 48-in. horizontal Symons disk crushers. Fines were removed by 1-in. stationary grizzlies ahead of each unit. In 1924 a third stage of crushing was provided by the addition of 55 1/2-in. rolls in open circuit. During 1925, the Symons disks were replaced by 73 1/2-in. rolls. All the rolls were changed to closed circuit, with elevators and screens to give a final product of 9 pct plus 3-mesh. The flowsheet of a typical crushing section of this period is shown in Fig I. The ore was withdrawn from a common bin serving the five crushing sections in the plant by means of any number up to six 36-in. wide-apron feeders, which discharged onto a common conveyor belt. This conveyor was equipped with a magnetic head pulley and the crusher attendant was stationed near the discharge end to pick out pieces of mine timber that might be in the ore. The ore was discharged over a 1 3/4-in. spaced bar grizzly and the oversize of this grizzly was crushed by a No. 7 1/2 McCully gyratory crusher set at 1 3/4-in. opening on the closed side. The grizzly undersize joined the gyratory discharge and was conveyed to a set of 73 1/2 by 20-in. Garfield rolls set at I in. These rolls operated in closed circuit with a bucket elevator and two vibrating screens placed in parallel.

Jan 1, 1947

By William R. Rumbold

WHEN I was in South Africa during the latter part of 1904, there were three known tin-fields, which may be called the Cape Town, the Bushveld and the Swaziland fields. THE. CAPE TOWN TIN-FIELD. This district is situated near Kuils river, 20 miles west of Cape Town, and 5 miles from Kuils River station on the Cape Town & Stellenbosch Railway. The deposits are in granite, intrusive in the Malmesbury beds, which are supposed to be of Silurian or Cambrian age. The granite, resisting denudation better than the surrounding shales,, has formed low-lying hills, the highest of which, the Bottlelary Berg, is 1,510 ft. above sea-level. , The rock consists of quartz, orthoclase feldspar and biotite mica; tourmaline is also present. The feldspar occurs in large crystals. The rock is generally decomposed on the surface, and the decomposition sometimes extends as deep as 100 ft. This formation-granite intrusive in Silurian shales-extends for many miles to the northeast, but so far as I know the Kuils River deposits are the only ones now known to occur in it, though probably further prospecting will reveal other deposits. This particular discovery was accidental;. alluvial tin being found in the course of boring for oil. The Kuils River Deposit. This comprises both lode and alluvial tin. The lode strikes N. and S., and dips about 30° E. into the hill. It is 5 ft. wide, and composed of dense white quartz, in which pinkish-gray cassiterite is distributed in large crystals. The vein also contains considerable quantities of wolfram. Fig. 1 is a rough plan of the relative positions of the lode and the alluvial deposit, the latter, as shown, following the course of a stream, while the lode crops out on the hillside

Jan 7, 1908

By J. L. Schroeder, W. G. Talman

EXPERIENCE has shown that certain known natural conditions and other indefinite characteristics combine to make a mining area vulnerable to mountain bumps. Some of the known conditions are heavy overburden, an overlying stratum of strong non-elastic rock, a structurally strong coal seam that does not crush easily and yet is the weakest stratum in the series, and a floor stratum of more than ordinary firmness. The indefinite characteristics could include resistance of top or bottom of a coal seam to lateral flow, effect of immediate top and bottom strata, nature of the coal seam, and other factors about which very little is known. It is in this area that exhaustive study is needed to achieve positive control of the dreaded mountain bump hazard. In the Gary district, West Virginia, two of the five operating mines have areas known to be vulnerable to mountain bumps.These are the No. 2 and 6 mines, which are working the Pocahontas No. 4 coal seam. In this area the seam is overlain at a zero to 10-ft interval by the massive Eckman sandstone, which is about 100 ft thick in the vulnerable areas. Total overburden, consisting of shale, coal seams, and sandstones, ranges from 700 to 1400 ft where bumps have occurred (Fig. 1). The coal seam is 4 to 8 ft thick and has a weak columnar structure of very soft and spongy or woody coal. The immediate top is either the Eckman sandstone or hard shale, both of which provide generally good roof conditions for mining operations. The bottom ranges from medium to hard gray shale. The incidence of bumps in the Gary district dates from about 1930 and can be correlated to some degree with the increased rate of extraction attained with mechanical mining. During early years of operation at the No. 2 and 6 mines, most of the work was development and under comparatively light cover. As overburden became heavier, together with an increasing percentage of coal coming from pillar extraction, mountain bumps began to occur. Before 1945 they were much less severe than in later years, and because there were no injuries or fatalities, no records were kept. But by 1951 the incidence of bumps had increased to such extent that it became evident a mining system would have to be designed to eliminate or at least minimize these occurrences. Drawing on experience with modified versions of old systems and certain characteristics peculiar to the Pocahontas No. 4 coal seam, the district mining engineer, Martin Hayduk, outlined the essential factors for bump control in the Gary district. These control factors indicated: 1) The highly stressed area, which lies within the limits of convergence effects, moves at approximately the same rate as the retreating pillar line. 2) There is a decided softening of the periphery of blocks which is greatest and deepest on the gob side. 3) Blocks less than 45 ft wide never have been known to bump in the Pocahontas seams. Fig. 2 shows the mining plan based on these observations—a thin-pillar system with a minimum of secondary development. It was recognized from the start that the Hayduk system had certain limitations. When pillar work backed up to an inevitable surrounded block it was no longer applicable; also, burnt bottom and/or unknown factors reduced the system's effectiveness in certain headings. Since there was no way to eliminate the loaded block, it was decided to experiment with auger drilling to attain controlled release of this stored-up energy. The decision to auger was made after consideration of three separate plants, which were: 1) To cut the solid block into pillars of maximum size by driving away from the fracture line and at such a distance outby that development

Jan 1, 1959

By J. D. Livingston, H. E. Cline

The lamellar-dendritic transition in Sn-Pb alloys near the eutectic composition has been studied at high growth rates. Lamellar structures were found over a substantial range of tin-rich compositions, and this range extended to increasingly tin-rich concentrations as growth rate increased. These results are discussed in terms of stability and competitive-growth arguments. Various experimental and structural limitations to the rate of directional solidification are discussed. The rate of heat removal at the heat sink is the major experimental limitation. ReCENT interet1,2 in the use of fine composite structures produced by directional solidification of eutectic alloys makes it important to determine the range of composition and growth conditions that yield such microstructures. Because increasing growth velocities produce increasingly finer microstructures, it is particularly significant to determine the factors limiting the rate of solidification. Mollard and Flemings3 have shown that composite structures, free of primary dendrites, can be obtained in Sn-Pb alloys of off-eutectic composition. The composition range of composite structures was found to increase with increasing values of G/V, where G is the temperature gradient and V is the growth velocity. These results are in good quantitative agreement with an analysis of the stability of a planar eutectic interface.4 This analysis specifically predicts that over a small range of compositions stable lamellar structures will be obtained even for G/V = 0, hence, even at very high growth rates. The lamellar-dendritic transition in Sn-Pb alloys has also been analyzed with a model based on competitive growth between dendrites and the composite structure.576 This treatment, based on earlier work on organic eutetics,7 predicts that the composition range yielding composite structures in Sn-Pb will increase rapidly at high growth rates. An increase in the composition range of composite structures at high growth rates was recently observed in Cu-Pb alloys near the monotectic composition.8 In view of these results, and the predictions of the stability and competitivegrowth analyses, it was decided to study the lamellar-dendritic transition in Sn-Pb alloys at high growth rates. EXPERIMENTAL Using 99.999 pct pure materials, a series of Sn-Pb alloys were prepared containing 16.8 at. pct to 27.6 at. pct lead. (Eutectic composition is 26.1 at. pct Pb.) Ingots were extruded to 0.175 in. rod, and some rod was drawn to 0.070-in. wire. Directional solidification was accomplished in two different ways, Fig. 1. For growth rates up to 2 x 10-1 cm per sec, a 0.175 in. diam sample was placed in a graphite crucible 5 in. long with 0.250 in. OD and 0.035 in. walls. Samples were melted under flowing argon in a vertical, platinum-wound furnace, and solidified by driving the crucible downwards through a \ in. hole in a water-cooled copper toroid, Fig. l(a). An insulated chromel-alumel thermocouple was imbedded in the center of a representative sample, and moved with the sample during solidification. The local temperature is plotted against the distance travelled by the sample in Fig. 2. As the growth rate increased, the solid-liquid interface moved closer to the water-cooled toroid and the temperature gradient increased. At growth rates above 10-1' cm per sec, heat was not removed fast enough and the sample moved into the toroid in the liquid state. The curve for V = 2 x 10-1 cm per sec shows a plateau caused by incomplete removal of latent heat from the interface, a problem which will be discussed later. To improve the heat removal, the toroid was cooled by nitrogen gas precooled in liquid nitrogen. This allowed successful solidification at rates up to 2 x 10-1cm per sec. Higher solidification rates required still more effective heat removal. Samples 0.070 in. in diam were placed in graphite tubes 0.125 in. in diam with 0.020 in. walls. Instead of cooling by sliding contact with a cooled toroid, these thinner samples were sprayed or directly immersed into water, Fig. l(b). After solidification, samples were stored in liquid nitrogen until they could be examined metallographic-ally. The surface was prepared with a diamond-knife microtome, followed by a light etch. The presence or absence of tin dendrites, Fig. 3, or lead dendrites, Fig. 4, was noted by optical microscopy, usually of a transverse section near the center of the sample. Replicas of the surface were prepared and examined in an electron microscope to resolve the fine lamellar structures, Fig. 5. The structures observed at various compositions and growth rates are summarized in Fig. 6. Composite structures were observed at increasingly cin-rich compositions as growth rate increased. This transition from dendritic to composite structure with increasing growth rate was also demonstrated by solidifying half a sample at a slow rate and then suddenly increasing the growth rate by lifting the furnace and quenching the sample with a water spray. A longitudinal section of this sample, Fig. 7, shows that the tin dendrites, which extended ahead of the slow-moving composite interface, were bypassed by the composite when the growth rate was increased. The range of composite structures at high growth rates was limited by the appearance of primary lead dendrites on the tin-rich side of the eutectic composition. Observation of representative longitudinal

Jan 1, 1970

By S. Frederick Ravitz

IN recent years, two theories of the mechanism of flotation have received a great amount of attention. One of these is Ostwald's theory of linear flotation,1 according to which most collectors contain three active groups: a hydrophilic or water-loving, a metallophilic or mineral-loving, and an aerophilic or air-loving group. Under the action of these three groups, Ostwald considers a single ring of collector molecules at the three-phase air-liquid-mineral boundary sufficient to bring about the flotation of the mineral particle. Siedler, Moeller and Reddehase2 objected to this theory immediately after it was presented, but most of their objections were answered by Ostwald.3 Very recently, however, Wark and Cox4 have more adequately criticized this theory, and their criticism makes its validity appear doubtful. The other important recent theory is the "chemical" theory of flotation, proposed by Taggart and his coworkers,5 who maintain that "all dissolved flotation reagents, which, in flotation pulps, either by action on the to-be-floated or on thenot-to-be-floated particles affect their floatability, function by reason of chemical reactions of well recognized types between the reagent and the particle affected." In general, they appear to consider most flotation results to be brought about by purely chemical reactions between the collectors and the products of oxidation present

Jan 1, 1933

By AIME AIME

As already announced in the January Bulletin, this publication will be issued during the coming year monthly instead of bi-monthly as heretofore. Among other reasons for this change, it is desired to effect thereby the earlier transmission to members of important papers, lists of candidates for membership, and other items of timely information. Spokane Meeting and Excursions. Further details of the 97th meeting of the Institute have been sent to members in the Circular of May 8, 1909. The list of those intending to go on the excursion is filling up, and since preference in position of state-room or berth is given in the order of application, members and guests who expect to accompany the party and have not yet communicated with Mr.. Theodore Dwight, 29 West 39th St., New York, N. Y., are earnestly requested to do so without delay. For convenience of the members a summary of the additional information is here presented. A special train of Pullman cars will leave Chicago about September 15. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals during the entire trip, except during the Yellowstone Park tour. The general cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through. Yellowstone Park, occupying in all about 30 days. Special, accommodations on the train will be furnished at the following rates

Jun 1, 1909