Search Documents

By J. C. Smock

THE magnetic and polaric properties of magnetite, or magnetic iron ore, are fundamental facts in magnetism. The disturbing effect of this mineral upon the magnetic needle in land surveying must have been very early observed. The difficulties arising from this source are still almost insurmountable in making accurate surveys in districts where this ore occurs to any extent, either as a rock

Jan 1, 1876

By R. W. Marrs

Kimberlite contains a unique assemblage of minerals and exhibits a characteristic pattern of spectral reflectance in the visible and near-infrared wavelength region. This spectral pattern is readily discerned in well exposed kimberlite outcrops, but becomes increasingly difficult to identify when outcrops are partially covered by vegetation or soils derived from nonkimberlitic materials. Detection of poorly exposed kimberlite diatremes is possible using multispectral imaging techniques where spectral bands are chosen to optimize contrast between the kimberlitic soils, nonkimberlitic soils, and vegetation. Careful processing of the multispectral data is essential to separate the spectral signature of kimberlite from the signatures of other components of the scene.

Jan 1, 1986

By Willard H. Tracy

The method of seismic reflection prospecting has many times been compared to sound ranging, a process that became familiar to many during the World War. According to this very simple theory, the dynamite goes off and sends out a compression wave, which meets a reflecting horizon and returns to the surface, where it is recorded and the elapsed time of its travel in the earth accurately determined. Computations are then made on the general theory that the longer the elapsed time, the greater the depth of the reflecting bed. While this serves to give an idea of the fundamental basis of the process, it suggests a simplicity that does not exist in the life history of the various waves set up by a dynamite explosion in the earth. To begin with, a seismic wave in the earth does not obey the same simple laws of propagation that apply to a sound wave in the air. The property of strength in shear possessed by solids introduces a factor that sets such waves apart from the ordinary air waves. Also, the transmission charactcristics of the earth vary widely from place to place, and a fairly accurate knowledge of the space relationships of these variations is necessary if the final results are to be understood. Besides the waves recorded and used in the reflection computations, there are many

Jan 1, 1940

By Willard H. Tracy

The method of seismic reflection prospecting has many times been compared to sound ranging, a process that became familiar to many during the World War. According to this very simple theory, the dynamite goes off and sends out a compression wave, which meets a reflecting horizon and returns to the surface, where it is recorded and the elapsed time of its travel in the earth accurately determined. Computations are then made on the general theory that the longer the elapsed time, the greater the depth of the reflecting bed. While this serves to give an idea of the fundamental basis of the process, it suggests a simplicity that does not exist in the life history of the various waves set up by a dynamite explosion in the earth. To begin with, a seismic wave in the earth does not obey the same simple laws of propagation that apply to a sound wave in the air. The property of strength in shear possessed by solids introduces a factor that sets such waves apart from the ordinary air waves. Also, the transmission charactcristics of the earth vary widely from place to place, and a fairly accurate knowledge of the space relationships of these variations is necessary if the final results are to be understood. Besides the waves recorded and used in the reflection computations, there are many

Jan 1, 1940

By George L. Heath

This paper is devoted chiefly to the coal-fields of the western part of the province of Chili and the eastern part of the province of Shansi; but the outline of this belt will give some idea of the extension of the coal-fields over northeastern China. This part of China is topographically divided into: (1) the mountainous peninsula of eastern Shantung; (2) the coastal plains, extending W. and SW. from the gulf of Pechili; and (3) the mountains and table-lands N. and W. of the coastal plains. The plains extend N. and W. from the gulf to within from 10 to 25 miles of the Great Wall, while their SW. extension covers western Shantung and reaches W. along the Yellow river almost to the southern boundary of Shansi. A line joining the mapped coal-fields, shown in Fig. 1, almost gives the western boundary of the plains; since these areas lie on the border of the plains—except the Tsê Chou field, which is on the table-land, 20 to 25 miles from that border. The coal-fields which have been mapped and investigated by the author are shown in Fig. 1. The one at and around Tongshan is known as the K'ai-p'ing coal-field; the one W. of Peking has been called the Wang-p'ing coal-basin; the one SW. of Pao-ting and N. of Chêng-ting may be called the Lingshan coal-field; and the one at and around Tsê Chou is known as the Tsê Chou coal-field. I. The K'ai-p'ing Coal-Field. As is shown in Fig. 2, most of this field lies in the coastal plains, and is therefore covered by alluvium and loess, which have buried the older rock-beds, and the more gentle and older topographic outlines, to such an extent that most of the re-

Jan 1, 1902

By W. H. Coghill, A. M. Gow, M. Guggenheim, A. B. Campbell

The object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the ((bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a comprehensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific variables, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this '(new philosophy" consists of using power as an index of the mill operation, and investigating grinding from the standpoint of set and induced varisbles, with emphasis on the latter.

Jan 1, 1935

By Alexander Gow

THE object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the "bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a compre-hensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific varia-bles, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this "new philosophy" consists of using power as an index of the mill operation, and investigating grind-ing from the standpoint of set and induced variables, with emphasis on the latter.

Jan 1, 1934

CONTENTS CATES, LOUIS S.-Factors Affecting Bank Slopes in Steam-shovel Operations. Discussed by Fred Hellman, Louis S. Cates, W. D. B. Motter, Jr., George S. Rice 1 CRANE, W. R.-Mine Subsidence in the Red Iron Ore Mines of the Birmingham District, Alabama. Discussed by George S. Rice, W. R. Crane, Louis S. Cates : 3 Factors Affecting Bank Slopes in Steam-shovel Operations Discussion of the paper of Louis S. CATES, presented at the New York Meeting, February, 1925, and issued, as Paper No. 1360-M, with MINING AND METAL-LURGY, August, 1924. FRED HELLMAN, New York.-My experience with shovel mining has been restricted almost entirely to Chuquicamata as far as operation is concerned. We had there an unusual condition in that the rock is cohesive because of the salts in it, so that you can probably work higher banks than is possible in most places. Recently they have reduced the height of the banks and have found that lower bank affords better working condition than the higher bank. It took two years of experimentation to determine the best height of bank for that particular mine. Each mine should be considered by itself and, to state off hand the best height of bank. for any given mine is impossible. We worked the high banks in Chile without much trouble. We adopted high banks in the beginning in order to obtain the minimum expense in railway approaches at that time. The first plan was for 50 ft.; then to get production started with the smallest possible expenditure of money, the approach to the deposit was changed and the first bank had an ultimate height of about 180 ft. We worked that bank; quite success-fully, but I do not think that it could be done anywhere else.

Jan 7, 1925

By Reich G. Gaertner

Almost every mining engineer who has had charge of extensive underground workings will have observed how often directions as to course and levels, deduced from careful theodolite measurements, have been slighted or disregarded by mine-foremen and shift-bosses, and how often these tedious measurements had to be repeated, even for minor works, such as ventilation-drifts or winzes, in order to carry them on with the required or desirable regularity. Besides the time and care absorbed by theodolite surveys, there is still another inconvenience, namely, the interruption of transportation during the time of observation, and, in heavily producing mines, the loss consequent upon such interruption. In proposing a subsidiary instrument to the theodolite, it is my purpose not to present a new one, but simply to recommend to the consideration of American mining engineers one which has been in use in nearly all the prominent mines of Europe for many decades, and has there fulfilled its purpose admirably. I refer to the mining or hanging compass (Fig. 1). At my urgent request, the firm of Keuffel & Esser, of New York, have lately constructed this instrument in a form which adapts it better to use in this country. By the addition of the trigonometer, the banging compass becomes at once an instrument which will prove of value even in the hands of foremen and practical miners, who have little or no knowledge of trigonometrical calculations. Probably many will say that me have no use for needle-instruments ; that our modern theodolites are of such perfect description, and leave so little to be desired, that the introduction of a compass would look like a step backwards compared to the fine results obtained by angle-instruments. I concede all that, and do not pre-

Jan 1, 1886

By Donald C. Moore

INTRODUCTION Published laboratory procedures used by the major crusher manufacturers for estimating crusher size are based upon techniques developed in the mid 1940's. Specifically, the two largest U.S. crusher manufacturers are using the Bond impact procedure. Although the procedure is still in use, there is little confidence in the results. Unless the laboratory results fall within a preconceived range, personal experience is used for selecting the number of crushers and connected horsepower (Coleman, 1978). There have been numerous theoretical studies of the communition of particles. However, no procedure has been widely acclaimed for predicting crusher power requirements. Experimental studies have included breakage by slow compression, slow speed impact and high speed impact. Theoretical results have increased our knowledge of the comminution process, but the procedures have not been capable of analyzing the complex mechanism of industrial crushing machines. The purpose of this chapter is to review the empirical crushing procedures that have been used, including advantages and disadvantages. A new procedure which has been in development at Allis-Chalmers Corp. from 1977 to 1982 is detailed. Actual results of the new procedure on a concentrator feasibility study are included. EXPERIMENTAL GOALS The goals of a laboratory crushability procedure are accurate predictions of: (1) Rock crushability, measured as energy per unit mass. (2) Crusher product size analysis. A procedure capable of predicting these parameters should be inexpensive and require a minimum amount of sample. CRUSHABILITY TESTS Bond Impact Procedure F. C. Bond (1946) detailed the development of the pendulum impact device that is still used by the leading crusher manufacturers (Bond; Rexnord, 1976). The device (Fig. 1) is comprised of two bicycle wheels with 13.6 kg steel hammers tangentially attached to the rims. The hammer faces are 50 mm apart at rest. On opposite ends of the hammers lifting

Jan 1, 1982

By W. L. Maxson

GRINDING is one of the major problems in present-day milling practice, and in many cases, it represents one of the main items of expense. It becomes necessary from time to time, to compare grinding practice in one plant with that in another plant, and in making such comparisons, it would be very desirable were there available accepted standards of grinding resistance for the materials involved. Such a set of grinding constants would also be of considerable value in planning new grind-ing installations. There have been some tests published, notably those of Lennox,1 which have been generally cited as a basis for such comparisons. Most of the tests made have been based upon open-circuit grinding, in which a weighed sample of the ore was crushed to pass a certain mesh, and was .then ground under certain conditions, either wet or dry. Grinding was continued until a certain desired fineness was attained, and the compari-sons based on the grinding time, or the samples were all ground for a certain specified length of time and comparison based upon the screen analysis of the products. Such methods have been acceptable where the ore was to be ground in open circuit. However, in modern milling practice, many grinding problems involve closed circuits wherein the oversize returns to the mill and a large circulating, load builds up. A method of testing that does not take the circulating load into consideration might yield results quite different from those to he expected in practice, because the minerals in the ore that offer maximum resistance to grinding will accumulate in the circulating load up to an equilibrium value. Thus the nature of the ore charge in the mill at any instant may differ greatly from that of the new feed, with a consequent error in the rate of grinding determined by such a method.

Jan 1, 1933

By Oliver Hopkins

As prefatory to the body of this paper, a few general statements will be made (1) in regard to the history and importance of the asbestos industry, (2) as to the principal sources of the raw material, and (3) as to the types and modes of occurrence of asbestos. While the modern asbestos industry is comparatively new and its growth during the last decade or two has been marvelous, asbestos has been known and used in a small way for probably 2,000 years-at least since the time of the Roman Empire. Pliny refers to it as "the funeral dress of kings" and Plutarch records its use as lamp wicks. In the middle of the 18th century the deposits of the Ural mountains were opened up and the first factory for the manufacture of asbestos goods was established. But, owing to the limited demand for the goods, the industry disappeared and interest lapsed until about 50 years ago. Since 1860, the asbestos industry has made wonderful strides, and each year sees new uses to which the material can be put, and hence an increased demand and an increased output. Of the three great producers of asbestos, Canada, Russia, and the United States, Canada stands pre-eminent, producing from one-half to three-fourths of the world's supply; Russia comes second, producing ,in 1911 about two and one-half times ,is much as the United States. In 1912 the Canadian production,1 including both asbestos and asbestic, was 131,260 short tons, valued at $2,979,384; while during the same year the production of the United States2 was 4,403 tons, valued at $57,959. Canada holds the first place in the production of raw asbestos, while the United States holds the first place in its manufacture.

Jan 9, 1914

Jan 1, 1932

By E. C. Wade, R. D. Valentine

This paper describes a computer applications engineering system and it's use to apply a thermal dryer fan motor in a coal preparation plant. The computer hardware and software systems are described to indicate the general approach taken and a specific case study is reviewed to show how computer power is brought to projects in the coal industry.

Jan 1, 1983

By C. V. Millikan

When a flowing oil well is being drilled in with cable tools, it is difficult to determine when an additional streak of pay sand is drilled. By placing a gas meter on the gas-release line from the oil and gas separator, any increase in volume of gas that comes with oil production is recorded. In addition to the better knowledge of sand conditions, these data are a valuable aid in determining the size and depth of shots, plugging off water, and estimating ultimate production. The meter also gives a record of operation while the well is drilling in; and if allowed to remain on the well after completion will give information that may lead to a more efficient recovery of the oil from the sand. A VERTICAL cross section of any oil sand will show great variation in porosity and oil content. In some sands, the entire thickness contains oil, the variation being only the degree of porosity or oil content, but more often the pay streaks are distinctly separated by shells or barren streaks. These pay strata vary in number and may be thin or thick. The total thickness of the sand may be several tens of feet while the part containing oil may be only 1 or 2 ft. thick. The amount of production is not proportional to the thickness of the sand but rather the thickness of the pay streaks. If the total thickness of the sand or the amount that can be drilled is small, or if the initial production is small, the depth at which each stratum of pay is encountered can be determined sufficiently accurately for all present economic purposes. However, when drilling through sand of considerable thickness, giving large initial production, especially where conditions necessitate that the production go through the same gas trap with that from one or more wells already producing, it is difficult to determine the depth at which the pay strata are encountered even accurately enough to guide the placing of shots, and small pay streaks are apt not to be recognized at all.

Jan 9, 1925

By Alden B. Greninger, Alexander R. Troiano

The crystallographic mechanism for the austenite-to-martensite trensformation has been deduced from the results of the following new experimental determinations: (I) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite—and thus the relationship between the martensite lattice and the martensite plate, and (2) the measurement and analysis of the change in positions that a volume of austenite unclergoes when it transforms into a crystal of martensite. For the latter study, a new tool was developed, the stereographic analysis of shear. Lattice relationship.—Thirty-five separate 50-gram melts of an alloy containing about 22 per cent nickel and 0.8 per cent carbon were prepared in a high-vacuum furnace. This alloy is all-austenite at room temperature; grain size was about I cm. Specimens of the alloy were cooled to about — 70°C. to form a few martensite crystals, and suitable specimens were ground and polished on a surface parallel to a single martensite plate, exposing the martensite crystal for an area of 1 mm. or more. Four martensite cystals from four diffierent ingots were prepared in this manner; the largest crystal of this group is illuslratecl in Fig. I. Back-reflection Laue patterns were obtained from martensite crystals (and the matrix austenite) both before and after tempering. The locations of the basal-plane pole of martensite was checked by means of oscillating crystal X-ray patterns. All four crystals studied yielded the same solution ( ± 0.5°), and these relationships are expressed in gnomonic projection in Fig. 3.* The narrow dark-etching bands often visible in martensite "needles" were found to be parallel to (112) and thus are undoubtedly twin bands in the martensite crystal.

Jan 1, 1941

By Alden B. Greninger, Alexander R. Troiano

THE crystallographic mechanism for the austenite-to-martensite transformation has been deduced from the results of the following new experimental determinations: (I) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite-and thus the relationship between the martensite lattice and the martensite plate, and (2) the measurement and analysis of the change in positions that a volume of austenite undergoes when it transforms into a crystal of martensite. For the latter study, a new tool was developed, the stereographic analysis of shear. Lattice relationship.-Thirty-five separate 50-gram melts of an alloy containing about 22 per cent nickel and 0.8 per cent carbon were prepared in a high-vacuum furnace. This alloy is all-austenite at room temperature; grain size was about I cm. Specimens of the alloy were cooled to about -70°C. to form a few martensite crystals, and suitable specimens were ground and polished on a surface parallel to a single martensite plate, exposing the martensite crystal for an area of I mm. or more. Four martensite cystals from four different ingots were prepared in this manner; the largest crystal of this group is illustrated in Fig. I. Back-reflection Lane patterns were obtained from martensite [ ] crystals (and the matrix austenite) both before and after tempering. The locations of the basal-plane pole of martensite was checked by means of oscillating crystal X-ray patterns. All four crystals studied yielded the same solution (±0.5°), and these relationships are expressed in gnomonic projection in Fig. 3.* The narrow dark-etching bands often visible in martensite "needles" were found to be parallel to {112} and thus are undoubtedly twin bands in the martensite crystal.

Jan 1, 1941

By Alden B. Greninger, Alexander R. Troiano

The crystallographic mechanism for the austenite-to-martensite trensformation has been deduced from the results of the following new experimental determinations: (I) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite—and thus the relationship between the martensite lattice and the martensite plate, and (2) the measurement and analysis of the change in positions that a volume of austenite unclergoes when it transforms into a crystal of martensite. For the latter study, a new tool was developed, the stereographic analysis of shear. Lattice relationship.—Thirty-five separate 50-gram melts of an alloy containing about 22 per cent nickel and 0.8 per cent carbon were prepared in a high-vacuum furnace. This alloy is all-austenite at room temperature; grain size was about I cm. Specimens of the alloy were cooled to about — 70°C. to form a few martensite crystals, and suitable specimens were ground and polished on a surface parallel to a single martensite plate, exposing the martensite crystal for an area of 1 mm. or more. Four martensite cystals from four diffierent ingots were prepared in this manner; the largest crystal of this group is illuslratecl in Fig. I. Back-reflection Laue patterns were obtained from martensite crystals (and the matrix austenite) both before and after tempering. The locations of the basal-plane pole of martensite was checked by means of oscillating crystal X-ray patterns. All four crystals studied yielded the same solution ( ± 0.5°), and these relationships are expressed in gnomonic projection in Fig. 3.* The narrow dark-etching bands often visible in martensite "needles" were found to be parallel to (112) and thus are undoubtedly twin bands in the martensite crystal.

Jan 1, 1941

By Carl S. Westerberg

Coal preparation practice and trends follow, among other factors, production trends in any given area. Considering an area the size of a state, some broad predictions may be made after a review of the annual production records. As this paper is concerned with coal cleaning in Utah, data on its production record are pertinent. Table 1 shows the percentage relation of coal production in Utah to the national total as a single figure up to 1935 which includes all recorded production. From 1935 through 1947 these data are presented by years. It is evident from these data that the production of Utah coal is ascending. The reason for this trend is industrial growth in the West resulting in a population shift which accounts for more people than the normal increase would supply together with Utah's relatively fortunate geographical location and its abundance of good-quality coal. Utah is also hopeful of supplying more coal in the future for West Coast power generation.I Utah is not unique among coal-producing states in anticipating greater production in the future. Coal Age states, " . . . it is now evident that a billion-ton yearly production of anthracite and bituminous by 1960 is not impossible." At present it is about 610,000,000 tons, the all-time high in 1947 was approximately 687,803,000 tons. In view of the trend outlined above, obviously more new mines will be required to produce the necessary tonnage. These in turn will require more mechanical cleaning capacity. Whether the required new plants will be built by present operators of mines and mechanical cleaning plants or by others now in the business of producing coal or expecting to enter it is of no consequence in this discussion. The fact is— they will be built.

Jan 1, 1950

By W. J. West, T. D. Mueller, J. E. Warren

Two methods are used to obtain the relatiorlship between ratio of gas to oil permeability and gas saturation. One method is to calculate a curve from field measurements of reservoir behavior: the other is to measure the relationship on a core .sample in the laboratory. The curves resulting from these TWO methods arc often comparer1 and seldom found to agree. The most important reason for the nonagreement is often overlooked. This reason is that the performance k9/k0 curve is calculated with the assumption of uniform pressure and saturution throughout the reservoir. To show the differerence between performance type kg/k0 curves and laboratory type kg/k0 curves. two performance type kg/k0 curves for two different production rates were calculaled from the production perforrnance of a hypothetical reservoir for which a laboratory type curve was assumed. Production performance of the hypothetical reservoir bras calcu- lated by use of international Business Machine's 701 Computer. The perfortnance type kg/k0 curves differed from the laboratory curve for the hypothetical reservoir. The performance type crrrve for the lowest production rate most nearly coincided with the laboratory curve. INTRODUCTION Predictions of oil reservoir performance are often made with the aid of complex numerical calculations. An important quantity required in these calculations is the ratio of gas permeability to oil permeability (kg/k0 )at a particular gas saturation. Two methods arc used to obtain a relationship between this ratio and gas saturation. The curves resulting from these two methods are called performance kg/k0 curves and laboratory kg/k0 curves. The performance curve is obtained from field measurements of reservoir behavior. Particular kg/k0 values are calculated from the producing gas-oil ratio, the cumulative reservoir withdrawals, the original oil in place, the average reservoir pressure, and the PVT properties of the reservoir fluids. The particular kg/k0 values are then plotted against the average rcservoir gas saturations for the entire history period. In order to use this derived kg/k0 relationship for performance predictions, a curve through these points is extrapolated to higher gas saturations. The laboratory kg/k0 curve is obtained from measurements made on core samples. Saturation is maintained uniform throughout the core during these measurements. The kg/k0 curves obtained with these two independent methods are often compared and seldom are found to be the same. Various reasons have been offered for the lack of correlation. One is that insufficient core? were obtained to derive a curve representative of the reservoir rock. Another is that laboratory methods have failed to reproduce reservoir conditions. The most important reason for the noncorrelation has been often overlooked because of the difficulty in evaluating its effect. This reason is that the performance or field kg/k0 curve is calculated with the assumption of uniform pressure and saturation throughout the reservoir. In any

Jan 1, 1956