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By Frank J. Anderson

IN the cement region of the Lehigh Valley, a difference of 2 to 3 pct in CaCO3 can make or break a new quarry development, and experience of the Dragon Cement Co. has shown that values of calcium carbonate, as reported from churn drill samples, have been increased as much as 6 pct on the average when the same area was diamond drilled. This calcium carbonate increase consequently lowered the values for silica, iron, and alumina, and made these sections much more attractive. Since 1950, the Dragon Cement Co. Inc. has been engaged in extensive diamond drilling in the local limestone of the Northampton, Pa., region, known as the Jacksonburg formation, and in the Lebanon, Pa., region in the Annville limestone, both of Ordovician age.

Jan 12, 1954

By E. V. Given

Designing a tailing dam is a major step toward fully integrated mill operation. In the case of large concentrators considerable planning is necessary, and the site of the tailing disposal area may very well dictate the location of the concentrator itself. Before a suitable location can be selected several pertinent factors should be investigated: estimated life expectancy of the mine and, if possible, approximate total tonnage; knowledge of daily mill capacity; and the possibility of future mill expansion. In addition, the area should be able to store tailing for many years and, from a cost and maintenance stand- point, gravity flow will probably be desired.

Jan 7, 1959

By Thomas A. Wright

No symposium on die casting could be complete without consideration of the methods of formula and impurity control. No consideration of control would be complete without discussion of that new tool of the analytical chemist and inspector, the quartz spectrograph. Just as there is an increased appreciation of the possible applications of the die-casting process and of die castings, so too is there, slowly but surely, of the spectrograph. At present the role of the instrument might well be compared with that of brass or magnesium die castings. Neither is as widely understood or known as they will be. Product specifications are increasing and are getting more explicit and often more rigid. The designer, metallurgist and production engineer or superintendent will be forced to depend more and more on the chemical laboratory. Sampling, as well as analyses, testing and inspection problems will grow. The chemical laboratory must meet its increased responsibility and use of the spectrograph will become more common. Advantages of increased precision, greater speed, lessened labor and often lower costs cannot be ignored. It will be the purpose of this paper in part to outline the respective fields of chemical and spectrographic analyses and to indicate where one may overlap the other and in part to indicate certain possible sources of contamination of zinc-base die-cast alloys in particular. COMPOSITION Aluminum.-Aluminum die castings are expected to conform to the specifications of the American Society for Testing Materials1† and the Society of Automotive Engineers2. The A.S.T.M. has recognized seven

Jan 1, 1935

By E. P. Peleider

DIAMOND drill research work was initiated at the School of Mines, University of Minnesota, in late 1949. The Drilling Symposium held in Duluth that spring highlighted the problem of high cost and core recovery and the need for controlled testing. An advisory committee made up of informed representatives of both mining companies and drilling companies was formed to suggest and advise on a program of drill research. A Hy-Mac hydraulic drill unit, see Fig. 1, especially designed for experimental testing, was obtained for this work by the School of Mines through the courtesy of the Carboloy Co. It is an extremely flexible unit, capable of exerting a forward thrust of about 1750 lb and turning at speeds from 650 to 2200 rpm. The feed arrangement is so designed that the advance can be set either at a constant rate or permitted to vary at a fixed Pressure, see Fig. 2. The

Jan 1, 1953

By E. P. Peleider

DIAMOND drill research work was initiated at the School of Mines, University of Minnesota, in late 1949. The Drilling Symposium held in Duluth that spring highlighted the problem of high cost and core recovery and the need for controlled testing. An advisory committee made up of informed representatives of both mining companies and drilling companies was formed to suggest and advise on a program of drill research. A Hy-Mac hydraulic drill unit, see Fig. 1, especially designed for experimental testing, was obtained for this work by the School of Mines through the courtesy of the Carboloy Co. It is an extremely flexible unit, capable of exerting a forward thrust of about 1750 lb and turning at speeds from 650 to 2200 rpm. The feed arrangement is so designed that the advance can be set either at a constant rate or permitted to vary at a fixed Pressure, see Fig. 2. The

Jan 1, 1953

By Andrew A. Blair

THE increased importance and value of chemical analysis in connection with metallurgical operations is largely, if not entirely, due to the increased accuracy of the analytical methods used for the quantitative determination of the foreign elements always associated with the metal operated upon. This applies especially in the working of iron and steel, and to the determination of the amounts of such elements as phosphorus, carbon, and silicon. The influence of greater or smaller amounts of these elements upon the physical properties of iron and steel will be better understood when the proper experiments shall have been made upon samples whose chemical composition is known with almost absolute certainty. From the present standpoint of analytical chemistry, it is easy to see that at least one reason for the failure of many attempts to solve this problem, is the inaccuracy of the analytical methods used. Even at the present time the frequent want of agreement (over and above the unavoidable error due to manipulation) between chemists working on the same sample, leads one to think that there is still at least a choice in the methods used. It is true that very frequently a faulty method in the hands of a skilful analyst may be made to give corroborative results

Jan 1, 1876

By Charles L. Elliot

Worldwide manpower utilization reached a new high at 10,482 professional man-months and expenditures increased to $19.9 million for mining geophysical activity during 1965. This is up from 9323 man-months and $14.5 million in 1964. Worldwide geophysical activity measured in percent distribution of the total manpower utilization and expenditures is presented in the accompanying Figs. 1 and 2. In terms of the total manpower utilization, ground surveys accounted for 61%, airborne surveys 18%, and mining geophysical research activity 21%. For expenditures, the breakdown was ground surveys, 49%; airborne surveys, 3901o; and research, 12%. Industry was responsible in general for 74% of the manpower utilization and 80% of the expenditures. Manpower costs in 1965 averaged $1900 per professional man-month.

Jan 11, 1966

By H. G. Doll

As a continuation of the earlier paper on the general subject of the SP log, a more complete analysis of certain features of the SP log in shaly sands is given. The pseudo-static SP in front of shaly sands is compared, on a theoretical basis, to the static SP in front of clean sands, as a function of the respective amount of shale and sand in the formation, and of the relative resistivities of the shale, of the uncontaminated part of the sand. and of the invaded zone of the sand. As a conclusion, the advantage of using reasonably conduc. tive mud in this case is shown. The discussion is illustrated by field examples. INTRODUCTION The discussion reported in the present paper is based on a theoretical analysis, and not on experiment. The field examples, joined to the text. are shown only as qualitative illustrations of the essential results of this analysis. Although the hypotheses made in the theoretical developments may perhaps be somewhat improved, it seems, nevertheless, that the results obtained account reasonably well for the actual phenomena, and give a fair approximation of their order of magnitude. The paper contains a mathematical analysis of a tri-dimen-sional distribution of potentials and current lines. due to spontaneous electromotive forces arising at the contact of shales and free electrolytes. as a function of the geometry and of the respective resistivities of the different media involved. It is assumed, although this hypothesis is not proven, that the emf's remain the same even if the shale occurs in very thin layers or in dispersed particles. It has already been pointed out 1,2,3 that, all other conditions being the same, the deflection of the SP log in front of a shaly sand is smaller than opposite a clean sand. When the thickness and the conductivity of a clean sand are large enough. the deflection of the SP log reaches a limiting value which is equal to the "static SP" of the clean sand. It is generally convenient to take the static SP of shale as the reference value or "base line." As a consequence, and for the sake of abbreviation, the expression. "static SP of a clean sand," is often used to designate the difference between the static SP of that sand and that of the shales, which difference is a measure of the total electromotive forces involved in the chain mud sand-shale. A similar limiting value is; also observed for the SP deflec-lion opposite a thick shaly sand, but it is smaller. just as if the total electromotive force involved were smaller in that case. This limiting value has been called the "Pseudo-Static SP" of the shaly sand. The static SP of a clean sand depends on the salinity of its connate water with respect to that of the mud, and, to a certain extent. on the differential pressure which controls the electro-filtration potentials, but it does not depend on the resistivity of the sand. On the contrary. the pseudo-static SP of a shaly sand depends not only on the salinity of its connate water and on the differential pressure, but also on the percentage of shale and on the resistivities of the shale, of the uncontaminated part of the sand, and of the zone invaded by the mud filtrate. If the three resistivities above were equal, the pseudo-static SP would be proportional to the percentage of sand in the shaly sand, and its departure from the static SP of a clean sand having the same connate water would simply be proportional to the percentage of shale. In that case, the pseudo-static SP of a shaly sand containing 10 per cent of shale would he 10 per cent less than the static SP of a clean sand. When. however. the sand is. on the average. substantially more resistive than the shale. the percentage of departure of the pseudo-static SP from the static SP of a clean sand is much larger than the percentage of shale. For that reason, the peaks of the SP log opposite shaly sands are systematically of smaller amplitude when the sands are oil-bearing than when they are water-bearing, all other conditions being the same. This feature is observed even when the sand beds are thick. and even when they do not contain a large percentage of shale. All this has already been described in all earlier publication", but mostly in a qualitative way. The present paper will analyze in more detail the action of the local SP currents which are generated inside of the shaly sands, and which are responsible for the abnormally low value of the pseudo-static SP. The quantitative computations have been extended to the general case of thin interbedded layers of sand and shale, where the resistivities of the shale and sand streaks do not have the same value: they are summarized in charts giving values of the pseudo-static SP of a shaly sand as a function of the different parameters involved. DEFINITIONS The static SP of a clean sand has been defined as the potential that would exist in the mud opposite that sand, were the SP current prevented from flowing. Such an ideal condition is represented on Fig. I-A. By analogy, the pseudo-static SP of a shaly sand can be defined as the potential that would exist in the hole, if the circuit shaly sand — surrounding shales — mud column were interrupted by the insulating plugs placed at the boundaries

Jan 1, 1950

By R. J. Charles, G. Agar

Experiments on single particles show that the amount of material created during impact that is finer than any chosen size is proportional to the energy of the impact. As the underlying principle of comminution, it might be stated that each unit of energy input to a given comminution system tends to add to the system an identical assembly of new particles and subtract an equivalent volume of larger particles. Thus, two of the consequences of the fact that each unit of energy tends to add identical assemblies of new particles to the system are: 1) on continued application of energy the total charge in any batch comminution system tends to assume the characteristics of this assembly, and 2) the process of comminution may be described by a relationship such as E = Ak-a. Recently Schuhmannl presented a theory of comminution which puts rational perspective on the extensive controversy surrounding most of the existent theories of comminution. With hindsight the origin of controversy can be ascribed to a relatively simple circumstance. In general, a progressive shift of a size distribution curve towards finer sizes is observed as energy is added to a comminution system. It is also observed that, with continued grinding, the size distribution curves usually change and appear to approach some constant shape. Inves-tigators generally felt that an appropriate method of relating and generalizing such data would be to consider the hypothetical case where particles in the system were uniformly subjected to comminution such that each of these particles, receiving its proportion of input energy, was transformed into a number of smaller particles of uniform size. Since the changes in shape of the size distribution curves during size reduction were clearly associated with the coarse particles in the system, it was also assumed that these changes accounted for little of the input energy and one could deal solely with the equilibrium shape towards which the size distribution curves tended. Although the unrealistic nature of the foregoing points of view was realized some justification was felt for such treatments since, in most cases, the resulting mathematical formulae could, by the adjustment of at most two parameters, satisfactorily describe experimental observation. Difficulties arose, however, in that the formulae required a specific influence of the feed size on the comminution process. In actual fact, the application of a feed size term in fitting experimental data was often found to be unnecessary or contrary to the above formulae. Secondarily, much discussion arose concerning the appropriate energy number that would relate the size change of one particle to the amount of comminution energy it received. As has been previously shown3 all the above theories that treat comminution as a continuous process of size reduction may be related to a proposition of the following form: dE = -Cfn [1] where dE is the increment of energy, dx is the size change, x is the particle size, and C and n are constants. It is now clear, as pointed out by Schuhmann, that Eq. 1 is inapplicable to comminution processes, since comminution cannot be considered other than as a discontinuous mixing process in which the overall size distribution of the product results from mixing, in various proportions, finished material with unfinished, and sometimes untouched, material. A striking illustration of this mixing phenomena may be obtained by comparing the size distributions of grinds in a typical batch ball mill with size distributions calculated on the basis of mixing various proportions of feed material with a ground material which obeys a power law size distribution relationship. Figs. la and lb illustrate such a comparison and the similarity of these figures indicates that mixing plays an important role in determining the overall shape of the product size distributions. Figs. la and lb illustrate, additionally, the underlying basis of the comminution theory presented by Schuhmann.' In the preliminary grinding of relatively close sized feed particles in a batch ball mill, one may visualize that, when a successful encounter of a ball with a feed particle occurs, then the particle undergoes severe size reduction and the size range in which the resultant particles reside is far removed from the size of the feed particles. After a number of feed particles are reduced by independent but similar impacts and one examines the size dis-

Jan 1, 1961

By Raymond H. Young, Paul Sennett

INTRODUCTION Kaolin clay, consisting largely of the mineral kaolinite, is widely used as a white pigment. In the United States, for instance, pigment kaolin production was nearly 6,000,000 tons in 1976 (1). Production for this year should be significantly above this level. Current prices for kaolinite 'pigments range from about $20.00/ ton to$260.00/tony,depending on the amount of processing needed to make the final product. Although much of this pigment kaolinite is used as an inert filler where product specifications are not very rigid, a large quantity of kaolinite is converted to products where very restrictive specifications exist. These specifications set severe limits on such properties as viscosity in a water suspension, particle size distribution, color, and brightness. This discussion will concentrate on methods available to improve the color and brightness of pigment kaolin and will review the advantages and problems associated with these various methods. The term "brightness" refers to the reflectance of the pigment to blue light (2). Since even the brightest commercial kaolins have a somewhat yellowish color, the blue reflectance (or brightness) is a reasonably good measure of their nearness to a perfectly white material. I KAOLINITE STRUCTURE AND SOURCES The mineral kaolinite is an aluminum silicate and can be represented by the formula (OH) 8Si4A14010. The formula is frequently written

Jan 1, 1979

By W. A. Hooker

This portion of Mexico is quite beyond the ordinary routes .of travel, and is seldom visited. Its mines have not the record of enormous wealth which has recently attracted foreign capital to other parts of the republic; but for many centuries it has been a mining country, and at some periods evidently a productive one. In 1881 the writer visited the State and spent some time in the inspection of the mines. The absence of published information regarding its mining industry is his apology for presenting to the Institute these notes on the subject. Oaxaca is, with one exception (Chiapas), the most southerly of the Mexican States. It extends from latitude 18o 20' to 15' 45' N.— about 180 miles, by some 300 miles, in an east and west direction, and embraces a large part of the Isthmus of Tehuantepec. The coast-line is wholly on the Pacific. The State has an area of 27,470 square miles, nearly that of the State of Maine, and a population estimated at one million, or thirty-six to the square mile. The great continental Cordillera which farther north and west expands into broad table-lands, is here converged into narrower limits and occupies the greater portion of the country; the main

Jan 1, 1887

By Fred Beasley

METALLURGISTS have, in the past ten years, overcome many difficulties of high zinc in lead blast-furnace slags. This problem was brought to the front at the close of the late war, by the price obtained for lead and the high cost of labor, fuel, and flux. The Port Pirie plant of the Broken Hill Associated Smelters, Australia, early in 1919 had increased the zinc oxide in its blast-furnace slags from 13.5 to 20 per cent., at the same time reducing the iron oxide in the slag from 33.5 to 25.6 per cent. These results were obtained by the following proceduret the addition of granulated slag to the roaster charge, 10 to 12 per cent., improved conditions of the crushing and mixing and roasting of the constituents of the sinter. By experiments and improve-ments the practice at this plant has developed a normal slag that carries 22 per cent. zinc oxide, and at times runs as high as 33 per cent. zinc oxide, with only slight furnace trouble. The granulated slag is used not, only as a diluent to the sulfur in the roaster charge, but also on account of its value as a slag-forming material and on account of the physical properties it imparts to the finished sinter. The ore is mixed with flux and given a double roast. All the first roasting is by sintering with the Dwight & Lloyd machines. The final roasting is performed partly by Dwight & Lloyd machines and partly by H. & H. pots. The charge to the blast furnaces consists chiefly of the final sinter, slag shells, siliceous and non-bearing sulfur, lead ores. High blast and ore columns are the practice. The greatest care is taken to obtain in the final sinter as low a sulfur content as possible.

Jan 2, 1925

By W. L. Chen

The Batac jig was first introduced in the US for fine coal cleaning in 1973 (Tackett, 1977; Hake, 1976). Since then, a total of six such jigs of various sizes have been installed in five US plants for a total capacity of 2346 t/h. The raw coal size ranges from 19 mm x 0 to 9.5 mm x 0-fraction sizes previously fed to heavy medium cyclones, Deister tables, or water only cyclones. Growing interest in the Batac jig as a replacement for the above equipment is due to the following reasons: • Unlike heavy medium cyclones, no magnetite is required. As a result, the operating cost of the plant is reduced. • The compactness of equipment is unique on a unit ton per hour basis as compared to other equipment. • Solid state electronic control of jig stroke length, frequency, and jig bed depth makes the equipment highly efficient. Installations of Batac jigs in the US as of June 1980 are shown in [Table 1]. Use of the Batac jig is even greater outside the US (Anonymous, 1980; Chen, 1980). Its use is not limited to fine coal but is applied to coarse coal as well, with 102 mm size in the feed (Zimmerman, 1975). In countries where consumption of magnetite associated with the heavy medium system of coal cleaning is considered a waste of iron ore resource, the Batac jig is regarded as the primary choice in the selection of cleaning equipment (Chen, 1980).

Jan 1, 1981

By Oberlin Smith

The experiments described in this paper are very incomplete and only preliminary to those I hope to make in the future. Having had a good deal of experience in cutting, forming and drawing sheet-metals, and feeling a great interest in the commercially new and wonderful metal, aluminum, I applied to my friend, Mr. A. E. Hunt, for some specimens in sheet-form, that I might, from time to time, test its working-properties in presses with which we happened to be experimenting at the works of the Ferracute Machine Company. The chances for such trials being accidental only, and the time having been limited to the last few weeks, no crucial experiments have been tried, and no exact data have been obtained for a rigid comparison with other metals. The results of what little we have done, however, are shown in the articles exhibited in connection with the reading of this paper, which comprise various cups, plates, boxes, bells and cartridge-cup and shells. For the latter I am indebted to my friend, Mr. Hobbs, of the Union Metallic Cartridge Co., who, at my request, ran several pieces of sheet-aluminum through the dies with which he was making brass cartridges. The specimens are rougher than they would be had the metal not been a little too thin for the particular dies which he happened to be running.

Jan 1, 1890

By M. Muskat, H. H. Evinger

ALTHOUGH the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.1 In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was. measured and an attempt was made to determine the effectiveness of 'sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to determine the effect of tamping were performed by Snelling and Hall,2 Small charges (20 grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.3 The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.5 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By Samuel Lasky

THE writer has been interested in determining the mineralogic dis-tribution of silver in the base-metal ore of the Ground Hog mine of the Asarco Mining Co. in the Central mining district of New Mexico.1 This ore consists of a varitextured mixture of sphalerite, chalcopyrite, galena and pyrite in a quartz gangue. The average ore contains 14 per, cent of zinc, 9.5 per cent of lead, 5 per cent of copper, and 10 oz. of silver per ton. Generally it is accepted that the silver in ores of this type, in which no definite silver minerals can be recognized, is contained in the base-metal minerals. Published assays of pure mineral specimens from many dis-tricts show that each of the base-metal minerals contributes in some degree to the total silver content of the ores, and to determine the pro-portionate amount contributed by each mineral in any specific ore it has been the practice to assay selected specimens of each mineral, the purity of which has been determined microscopically. There being no such assays available for the Ground Hog ore, and it being impract cable to have enough of them made to give average results, the writer resorted to a mathematical attack upon composite assays of large quantities of ore and concentrates. Surprising results were obtained, and it is the threefold purpose of this paper to present these results, to describe the mathe-matical method used, and to point out the value of using this method even when assays of pure specimens are available.

Jan 1, 1934

J. J. RUTLEDGE,* McAlester, Okla. (written discussiont).-Research work has often a more immediate and practical application to the in-dustries than even the investigators themselves realize, but coal mining has not attracted the investigator, except in so far as the mine-accident prevention work and fuel investigations are concerned. In future, the coal geologist will study the subsurface geology of the various coal seams as the petroleum geologist now studies the oil sands, and from the results of these studies the coal operator will be able to locate his shafts to the best possible advantage and to avoid faults that would interfere with underground work. There would have been many thousands of dollars saved, and perhaps some reputations, if a good stratigrapher. had been called into consultation in the southern part of Somerset County, Pa., where a local seam of coal, quite thick, was mistaken for the Pittsburgh seam, which, if ever present at that point, had long since been eroded. Why will the Quemanhoming coal carry more sulfur without injuring the grate bars than George's Creek Big Vein? Only the investigator can answer and yet the fact that the above is true means a greater price for the thinner coal. The owner of the land in Oklahoma receives one-fourth of the cotton crop produced by the tenant who farms his land and one-third of the

Jan 11, 1919

By H. H. Evinger, M. Muskat

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By M. Muskat, H. H. Evinger

Although the shooting of oil wells for the purpose of increasing production has been practiced since 1866, present-day shooting technique has been arrived at almost wholly by a process of trial and error. The difficulties attending either a theoretical analysis of the problem or an experimental attack become apparent when one actually embarks on a theoretical investigation or attempts to formulate an intelligent experimental program. The literature on the subject consists mainly of descriptions of current practice, scattered eye-witness accounts of events following the shooting of a well, and vague speculations on the mechanical processes involved. In contrast to quarry blasting, the results of oil-well shooting cannot be determined by means of visual inspection, and it is perhaps for this reason that only one attempt at what approaches a direct experimental attack has been reported in the literature.' In these experiments, charges of liquid nitroglycerin were exploded in holes drilled in a sandstone outcrop. In order to observe the character and extent of the resulting fractures, the rock was blasted away so as to expose the original shot holes. After all this had been done it was found impossible to distinguish the fracturing due to the original shots from that due to the subsequent blasting. The enlargement of the holes due to the pulverizing action of the shots was measured and an attempt was made to determine the effectiveness if sand tamping. Only five shots were made and few definite conclusions could be drawn. Some small-scale experiments to deter-mine the effect of tamping were performed by Snelling and IIalL2 Small charges (zo grams) of dynamite were detonated at the bottom of a cylindrical hole in a lead block and the resulting enlargement of the hole was taken as a measure of the effectiveness of the explosion. It was found that when the shot was tamped with a sufficient amount of sand or clay, the volume enlargement was approximately double that found when no stemming had been used. The properties of the explosives have been the subject of much study by the manufacturers, the U. S. Bureau of Mines, and various other agencies. For example, velocities of detonation for many commercial explosives are to be found in the Blasters' Handbook, issued by the Du Pont company. Many other properties are given in a treatise on the subject by Naoum.~ The shock wave that accompanies the detonation of high explosives has been studied photographically by Payman4 and others. The hydrodynamical theory of the shock wave has received much attention, and an extended theoretical treatment is given by Bateman.6 Two aspects of the well-shooting problem will be considered in this paper; namely, the fracturing of subsurface strata, and possible damage to casing. With respect to the former of these, several calculations have been made giving the stresses in the rocks surrounding the shot. In order to arrive at numerical results at all, however, it is necessary to introduce a great many simplifying

Jan 1, 1941

By John Sullivan

Resources for Freedom, a report by the President's Materials Policy Commission, commonly termed either the Paley report, after its chairman, or the PMPC report, was issued in June 1952. The data collecting and assembly work for its preparation were done in 1951. The statistical base in most cases was 1950. It reviewed our economy and predicted what it will be in 1975.* The bases for the predictions were given. Consideration was given not only to statistical data and trends but also to technological changes taking place and likely to take place in the ensuing 25 years that will affect our economy. The supply of raw materials was studied and predictions made as to the availability of supply and the sources in 1975. One of the industries covered was iron and steel. For the most part the report did not attempt to provide a curve showing annual growth for any industry or commodity. It contrasted 1950 with the probable status in 1975. Interpolation between these dates is difficult and the Commission did not intend that it be used for short interim intervals. It is possible in 1958 to show the actual changes from 1950. The magnitude of the changes illustrates the agreement with some interpolation of the Paley report. Statistical comparisons can be general only because the Commission did not postulate a linear change. A study of the iron and steel industry will show if the general predictions have been realized or if gross errors were made. This paper is concerned with such an analysis. It is concerned with the production and consumption of crude, not fabricated products. It attempts to bring various facets of technical and statistical information on the industry up to date.

Jan 8, 1959