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By AIME AIME

BEGINNING Thursday, July 16, the National Broadcasting Co. is broadcasting from 6:30 to 6:45 p.m., over its nationwide network and possibly also by short wave a series of eleven radio programs dealing with the contributions of engineers to the prosecution of the war. The series is being arranged and sponsored by a committee of representatives of the national engineering societies, R. L. Sackett, chairman. The committee began its deliberations before Pearl Harbor and had scripts under way on blackouts, bombs, and damage to structures. The declaration of war emphasized the importance of the proposed radio program. The National Broadcasting Co. and the Office of Civilian Defense enthusiastically endorsed the committee's proposal and have been generous in their help and approval of scripts so far submitted. Controversial matters are included in the broadcasts and changes will be made when requested by O.C.D. up to the minute that a program goes on the air. In this way the latest and authoritative information will be given.

Jan 1, 1942

By A. M. Starfield

The study of strain waves in rock over the past decade has, for the most part, been an investigation related, but not applied, to rock blasting; the design of rock blasts has proceeded on a basis that is independent of strain wave research. This duality is reflected in the paper by Dr. Clark.1 While the greater part of the paper is devoted to a discussion of spherical waves in elastic and visco-elastic media, it is in an entirely unrelated section, the section on scaling and cratering, that the practical approach to rock blasting is found. Work done by the U. S. Bureau of Mines, as described in the paper by Duvall, Atchison, and Fogelson,2 has established a correlation between crater dimensions and the peak compressive strain in the rock. Strain wave measurements have thus been used to compare explosives but have not, as yet, been applied to the planning of a production round once an explosive has been selected. The optimum burden, for instance, is still determined either by experience, empirical formulae (e.g. that of Langefors 3), or a cratering experiment and the theory that has been developed around that proposed by Livingston.4 Even then there is some ambiguity in applying deductions from short, concentrated explosive charges to the long charges often used in practice (although Bauer 5 reports doing this with considerable success) and wave theory has until recently thrown no light on this problem, being confined, with only a few exceptions, to spherical charges. The hesitation in applying strain wave theory has probably been due to two questions that have not been answered satisfactorily: just how important is the strain wave in rock breakage, and if it is important, under what conditions will the wave break rock? This paper is an attempt to answer the first question, to avoid the second question by an admittedly oversimplified assumption, and then to investigate the implications of this assumption for blasting with long cylindrical charges.

Jan 1, 1967

By George Otis Smith

In the utilization of natural resources owner, operator, and consumer* should share the attendant benefits. Development needs to be planned under terms recognizing fully the interests of all concerned, for ally undue advantage given to any one of these participants is apt to involve even greater and disproportionate injury to one or both of the others. For this reason it is well to preface any consideration of needed reforms in legislation affecting the disposition of public land with a survey of certain fundamental principles that determine the general conditions of a11 land transfers preliminary to development, utilization, and production. The disposition of any undeveloped natural resource, whether timber, oil, coal, or water power, as a transaction to which land owner and prospective developer are parties, must be based in theory upon a division of expected returns.' Whatever the terms of such disposition, neither party can reasonably ask for anything other than an equitable division of the returns. Under this analysis three and only three questions need to be discussed; namely, what are those profits, how is this division to be accomplished, and what is the equitable basis of division ? The answer to the third question should probably be found by applying to the problem the principles of theoretical sociology, and the question need not be mentioned further at this time, inasmuch as it does not involve the practical considerations to be kept in mind in connection with the other questions, which are concerned with only the measure of returns and their division. That is to say, whether the land owner's equity is to be stated as 95 per cent, ox as 6 per cent, of the profits attending the development of the particular resource, no change would be necessary in the method to be adopted of arriving at the closest approximation of the prospective total profit. If on this basis we now compare the two methods of disposing of

Jan 1, 1915

By J. Morgan Clements

The manufacture of coke in Peru, as practiced at the coalmines of the Quishuarcancha and Goyllarisquisca districts, is intermediate between the primitive coke-heap and the bee-hive oven. The method of coking is quite simple. In constructing the coal-heap, preparatory to burning, the ground is first leveled, and a simple stack of stone and clay is built, giving the bottom, to a height of 6 ft., approximately 6 ft. of external diameter. The size of the stack varies in different districts, but is generally 9 ft. high, and slightly smaller at the top than at the bottom. The walls of the heap are from 12 to 14 in. thick, which allows an inside diameter of from 3.75 to 4 ft. These walls are pierced at intervals by three or more tiers of openings or flues, connected with the central flue. The radial flues have a diameter of about 5 in. and are built with a gentle upward slope. The stack (shown in Fig. 1) is permanent; and in this respect the practice in Peru differs from other primitive practices in which nothing is permanent except the yard. Above the permanent 6-ft. portion of the stack there is added a cap of clay, about 3 ft. high, which contracts toward the top, where it has an inside diameter of about 2 ft. This clay cap is temporary, and frequently has to be renewed after each burning. Before charging the coal, there are first built, from the lowest tier of flues upon the ground, a number of temporary flues, leading from the central stack out to the edge of the coal-heap, and constructed of blocks of coal for the greater part of the distauce, the outer edge alone being of rough stoue. The coal is then piled up over these flues and around the stack to a height of about 6 ft. The bottom flues are the only ones that

Jan 1, 1905

By E. R. Borcherdt

IT is notable that the first large-scale mine operation equipped entirely with detachable bits was the Badger State mine of the Anaconda Copper Mining Co. in Butte, Montana, just 30 years ago. This mine in 1922 was producing approximately 1200 tons of ore per day. Much of the data presented in C. L. Berrien's article1 describing the development and installation of the Hawkesworth detachable drill bit were obtained from these operations. As in any pioneering effort, no precedent existed and many difficult problems required solution, so that the changeover to detachable bits at all Butte hill mines was not completed for 6 years. There was widespread disbelief as to the probable efficiency of the new installation.

Jan 2, 1953

By Frederick N. Rhines, Robert F. Mehl

Relatively few data have been collected on the rates of diffusion in ternary solid solution systems. In general it does not seem worth while to gather extensive data for such systems until the factors that determine the rates of diffusion in binary systems are better understood. But the rates of diffusion in a ternary system of limited solid solubility, in which the terminal solid solution is in equilibrium with an intermediate phase and may thus be represented as a quasibinary system, represents a case of special interest. In this case, where by reason of the association of the two solute metals in an intermediate phase a special attraction of the two solute atoms may be safely assumed, some interaction of these atoms during simultaneous diffusion in the solvent lattice might be expected. It has frequently been proposed that molecular solid solutions exist in quasibinary and in other ternary (and binary) solid solutions. There is no direct evidence for such solid solutions; arguments based upon the supposed anomaly in certain physical properties1 are hardly important; unexpected density relationships have proved deceptive;2 suggestions of molecular solid solutions have been made on the basis of solution laws in their application to certain systems, but without result;3 attempts to find lattice parameters in the solid solution Al-MgZnz, which cannot be calculated from the separate effects of magnesium and zinc and might therefore be taken as evidence for a molecular aggregation, have given negative results.* Fundamentally, methods for the determination of the state of molecular aggregation in solution depend upon the kinetic behavior of the particles constituting the system. If it could be shown that the two solutes in a quasibinary ternary system diffuse in molecular proportions, despite a radical difference in the separate rates of diffusion of each solute when diffusing alone in the solvent lattice, some basis for the concept of molecular solid solution would be afforded. Freche5 examined the rates of

Jan 1, 1940

By Frederick N. Rhines, Robert F. Mehl

Relatively few data have been collected on the rates of diffusion in ternary solid solution systems. In general it does not seem worth while to gather extensive data for such systems until the factors that determine the rates of diffusion in binary systems are better understood. But the rates of diffusion in a ternary system of limited solid solubility, in which the terminal solid solution is in equilibrium with an intermediate phase and may thus be represented as a quasibinary system, represents a case of special interest. In this case, where by reason of the association of the two solute metals in an intermediate phase a special attraction of the two solute atoms may be safely assumed, some interaction of these atoms during simultaneous diffusion in the solvent lattice might be expected. It has frequently been proposed that molecular solid solutions exist in quasibinary and in other ternary (and binary) solid solutions. There is no direct evidence for such solid solutions; arguments based upon the supposed anomaly in certain physical properties1 are hardly important; unexpected density relationships have proved deceptive;2 suggestions of molecular solid solutions have been made on the basis of solution laws in their application to certain systems, but without result;3 attempts to find lattice parameters in the solid solution Al-MgZnz, which cannot be calculated from the separate effects of magnesium and zinc and might therefore be taken as evidence for a molecular aggregation, have given negative results.* Fundamentally, methods for the determination of the state of molecular aggregation in solution depend upon the kinetic behavior of the particles constituting the system. If it could be shown that the two solutes in a quasibinary ternary system diffuse in molecular proportions, despite a radical difference in the separate rates of diffusion of each solute when diffusing alone in the solvent lattice, some basis for the concept of molecular solid solution would be afforded. Freche5 examined the rates of

Jan 1, 1940

By Raymond Mancha

A test of any fan requires the determination of such data as fan pressure, air volume handled by the fan, and power input to the fen shaft. When testing operating mine fans of the centrifugal type, test methods have been employed, for the sake of convenience, that permit great latitude in detail of procedure resulting in wide variance in results by different investigators. Some controversial aspects of field fan testing are the result of past failure to define clearly the various forms of fan pressure and to a lack of understanding of the accurate procedure for the measurement thereof. Also, the anemometer for air-volume measurement, although convenient, if carelessly used and maintained is subject to a wide error range with variation in method of application and in instrument accuracy. The appearance of the axial-flow type of mine fan offers the possibility of refinements in field testing that were impractical with the centrifugal fan. First of all, the fan inlet and outlet are more sharply defined, giving closer agreement as to just where the fan begins and ends; thus there is less disagreement as to the proper location for measurements of fan pressure. The area of passage into the inlet of an axial-flow mine fan usually constricts, causing high air velocities with accompanying steadiness of flow. Thus the fan inlet offers an ideal location for accurate air-volume measurements with the pitot tube, the proper use of which is well established by code. Thereby the controversial aspects of such measurements are eliminated. Use of the Pitot tube also facilitates a more accurate measure of fan pressure, since the individual pressures measured can be properly weighted, as will be explained later. Determination of power input to the axial-flow mine fan operating in the field is subject to the same inaccuracies as with the centrifugal fan if the axial-flow fan is also belt driven. However, because of the higher rates of rotation usual with axial-flow fans, direct-driven units are more numerous and it is unnecessary to assume a drive efficiency, thus eliminating one possible source of error. It is the purpose of this paper to define and explain the various types of pressure measurements involved in a field test of an axial-flow mine fan, and to further explain the proper use of the Pitot tube when measuring pressures and volumes. DefinitioN of Fan Pressures The two fan pressures most commonly discussed are fan total and fan static pressure, each of which has the same meaning regardless of whether the fan is blowing, exhausting, or blowing and exhausting, as in the case of a fan with ducts connected to both outlet and inlet. Fan total presscre is the amount by which the total pressure of the air delivered by the fan exceeds the total pressure of the air received by the fan. This pressure is a measure of the maximum amount of the work done on the air by the fan that is available for external use.

Jan 1, 1942

By Raymond Mancha

A test of any fan requires the determination of such data as fan pressure, air volume handled by the fan, and power input to the fen shaft. When testing operating mine fans of the centrifugal type, test methods have been employed, for the sake of convenience, that permit great latitude in detail of procedure resulting in wide variance in results by different investigators. Some controversial aspects of field fan testing are the result of past failure to define clearly the various forms of fan pressure and to a lack of understanding of the accurate procedure for the measurement thereof. Also, the anemometer for air-volume measurement, although convenient, if carelessly used and maintained is subject to a wide error range with variation in method of application and in instrument accuracy. The appearance of the axial-flow type of mine fan offers the possibility of refinements in field testing that were impractical with the centrifugal fan. First of all, the fan inlet and outlet are more sharply defined, giving closer agreement as to just where the fan begins and ends; thus there is less disagreement as to the proper location for measurements of fan pressure. The area of passage into the inlet of an axial-flow mine fan usually constricts, causing high air velocities with accompanying steadiness of flow. Thus the fan inlet offers an ideal location for accurate air-volume measurements with the pitot tube, the proper use of which is well established by code. Thereby the controversial aspects of such measurements are eliminated. Use of the Pitot tube also facilitates a more accurate measure of fan pressure, since the individual pressures measured can be properly weighted, as will be explained later. Determination of power input to the axial-flow mine fan operating in the field is subject to the same inaccuracies as with the centrifugal fan if the axial-flow fan is also belt driven. However, because of the higher rates of rotation usual with axial-flow fans, direct-driven units are more numerous and it is unnecessary to assume a drive efficiency, thus eliminating one possible source of error. It is the purpose of this paper to define and explain the various types of pressure measurements involved in a field test of an axial-flow mine fan, and to further explain the proper use of the Pitot tube when measuring pressures and volumes. DefinitioN of Fan Pressures The two fan pressures most commonly discussed are fan total and fan static pressure, each of which has the same meaning regardless of whether the fan is blowing, exhausting, or blowing and exhausting, as in the case of a fan with ducts connected to both outlet and inlet. Fan total presscre is the amount by which the total pressure of the air delivered by the fan exceeds the total pressure of the air received by the fan. This pressure is a measure of the maximum amount of the work done on the air by the fan that is available for external use.

Jan 1, 1942

By Jon Kogut

This paper describes three programs, currently in use within MSHA, for graphic analysis of accident frequency data. The first program, TREND, plots confidence bands for curved trends in data compiled over a period of time. In addition to detecting statistically significant upward or downward trends, the program can be used to determine whether an observation at a particular time deviates significantly from the historical pattern. The second program, POIPORP, plots interval estimates for the risk of accident in each of several environments, given an observed number of incidents and exposure time at each environment. POIPORP is designed to quantify the uncertainty implicit in incidence rates based on limited information and to facilitate statistically valid comparisons among the rates. The third program, CINDY, plots dynamically adaptive control charts for accident or injury experience at a given location. These charts are used to detect statistically significant departures from a changing standard or a previously established trend. All three programs are written in FORTRAN IV, utilizing DISSPLA and IMSL. They exemplify forms of statistical analysis that would not be practical without a computer. Use of the programs is illustrated with applications to coal mine fatality and injury experience.

Jan 1, 1983

By W. M. McCardell, W. O. Winsauer, M. Williams

The mechanism by which an electrical potential difference is developed between two salt solutions separated by shale is shown to be a consequence of the electrical double layer of the shale surfaces. A mathematical derivation is presented to show -the dependence of the potential on the shale characteristic.? and on the concentration of the salt solutions. The equations developed describe adequately the potential-concentration behavior of a long shale core. The equations also describe the variation of potential of sand-shale mixtures with variation of clay content. Ion adsorption i* an important factor in he developments of the surface charge on the shale. and electrical resistivity and ion transference number data are emlployed to estimate the increase of surface charge with concentration. Since the potential is shown to be dependent on the characteristics of the particular .system. water salinities estimated from the potential log by previously proposed methods may be low in some rase;. INTRODUCTION That the electric well log exists today may he attributed to the ingenuity of the Schlumberger brothers who adapted to the logging of wells techniques which were originally developed as surface prospecting methods for the location of ore bodies Empirically it was found that the potential curve of the electric log usually gave values for clean sands which were negative with respect to the values for shales. It was suggested that the potential was responsive to porosity. It was postulated in explanation? that the potential was the sum of a streaming potential, which differed for sands and shales, and of an "electro-chemical" potential of undetermined origin. Mounce and Rust in 1943 showed that the streaming potential is small in most cases and that the potential is generated by a process in which shale and a salinity difference play-essential party. Dickey.:' in the same year, concluded that the potential is dependent upon adsorptive properties of reservoir rock. Wyllie in 1949. and Wyllie and Patnode, in 1950, measured the potential-: between two salt solutions separated by barriers of either naturally-compacted or artificially-compacted shales and concluded that the potential can be expressed by where E is the potential R is the gas content F is Faraday's constant T is the absolute temperature are the activities of the two uni-univalent solutions These authors postulated that shale. in the ideal case is impermeable to the migration of negative ions. Any potential less than the "ideal" shale potential was considered to be due to imperfections in the shale barrier. Although the studies by Wyllie and Patnode of the development of the shale potential are fairly recent. investigators in fields other than well logging have discussed the mechanisms responsible for analogous potentials over a period of several decades. Although it is evident that much thought has been devoted to the question of the origin of the potential observed in wells, it is also apparent that all of the explanations presented to

Jan 1, 1953

By D. B. Dowling

The interest which has been aroused in prospecting for oil in the foothills of southern Alberta, and in the oil possibilities of the known gas fields situated in the less-disturbed areas, called for a much closer examination of the structure, thickness, and composition of the underlying rocks of the region than had hitherto been made. The areal geology of the larger part of the great plains was outlined by Dawson, McConnell, and Tyrrell, between 1881 and 1885. The foothill area was not critically examined at that time, owing to the time which would have been required for its proper study and the difficulty that was found in recognizing in the foothills the divisions which had been adopted in the mapping of the formations of the plains. This was due in great measure to the paucity of exposures in continuous sections of the lower divisions of the Upper Cretaceous. Since the pioneer work on the plains was published, the beds which form continuations south into Montana have been critically examined, The Canadian beds arch over the end of a flat anticline which rises to the south; and two sections in Montana, one on each side of the anticline, help to explain some of the difficulties previously encountered in the mapping of the measures found in the foothills. The index map, Fig. 1, shows the area studied, and its relation to southeastern Alberta, and to Montana. Problems of Correlation The principal difficulty experienced in correlation was in connection with the measures known as the Montana group. The beds of this group did not seem to agree in the two Montana sections. They showed the same differences to some extent as are encountered in comparing the foothill measures with those of the plains. The Montana group in Dakota and Manitoba consists of a series of shales of marine origin. In the eastern Montana section two sandstone members appear, leaving a shale member at the top and another

Jan 1, 1916

By A. E. Lillstrom

IN the development of iron mines and production of iron ore from the Marquette range, drilling blast-holes is an important phase of the mining cycle. The ground drilled in ore production can be classified into two main categories, soft hematite and hard hematite or magnetite. Within these categories the material exhibits a wide range of penetrability by percussion drills. Development work encounters various types of rock. Slate and altered basic intrusives constitute the softer types commonly encountered. Harder materials are represented mainly by greywacke, quartzite, iron formation, and diorite. Prior to the first tungsten carbide trials in late 1947 and early 1948, hard-rock and ore drilling was done with steel jackbits starting at 21/4-in. diam. These were reconditioned by hot milling. Automatic or handcrank 31/2-in. drifters were employed, mounted on Jumbos, posts and arms, or tripods, depending upon the working place. With the exception of shaft sinking jobs where 55-lb sinker machines were and still are used with 1-in. quarter octagon steel, the other production and development mining utilized 11/4-in. round and Leyner-lugged steel. The following properties have been selected as typical examples wherein carbide bit applications have proved economical. The Mather mine "A" and "B" shafts and Cleveland-Cliffs Iron Co. mines are soft ore mines where insert bits are used in rock development only. The Greenwood mine, Inland Steel Co., Champion mine, North Range Mining Co., and Cliffs shaft mine, Cleveland-Cliffs Iron Co., are hard ore mines where all drilling is done with tungsten carbide bits. Mother Mine "A" Shaft In the Mather mine "A" shaft and other soft ore properties where only rock development work is done with the tungsten carbide bits, several types and makes of bits have been tried since early 1948. The greatest proportion of failures have been at the connection end, although the early trials with the 13 Series Carset 11/2-in. bit used in conjunction with 31/2 -in. automatic-feed drifters, showed an equal amount of shattered inserts. To combat this shattering, the 31/2 -in. drifters were replaced by 3-in. drifters, thus eliminating, for the most part, insert failures. However, the attachment end of the rod continued to be the main source of trouble. The greatest amount of failure was in the stud or at the upset section approximately 2 in. behind the drive shoulder of the rod. Heat treatment was changed several times as well as the composition of the alloy studs. Since this failed to correct the trouble, a decision was made to change to a heavier attachment section. Timken 11/2-in., type M, bits were then employed and showed an exceptional improvement. The rods are discarded when the thread contour shows sharpening or wear on the shoulder. It was also learned that the Timken insert did not show as rapid gage and cutting edge wear as did competitive makes, and footage per use increased by approximately 50 pct. Prior to the Timken trials the average life per bit at the Mather mine "A" shaft on 6-ft change chain-feed drifters was 500 ft, and the rod life at the connection end was 50 ft. The Timken bit with chrome-plated thread averaged 1200 ft, and rod life increased to as much as 500 ft. However, the life of the connection end was much better on shorter length drill rods or in places where machines with 34-in. change were used. The bit thread continued to be the point of ultimate failure with thread strippage, constituting the cause for discard of bits. In one of the new development headings, harder rock was encountered for approximately 800 ft, dropping the life per bit to a low of 90 ft with shank and thread life of rods dropping to approximately 125 ft average. The stripped bits were then welded to the rods, increasing the life per bit by 75 to 100 pct. The rod transportation for main level development was not a problem so intraset rods were tried. Intraset rods have tungsten carbide inserts set into the rods proper by the manufacturer and can be obtained with chisel or four point bits. This type of rod eliminates the need for any connection and the steel being a special alloy will show more feet drilled per rod. The first trial was made with eight rods, and final results averaged 350 ft per rod, six of the rods worked the life of the bit end, and two broke shanks at less than 50 ft. The preceding example showed a considerable improvement, so additional steel of the same type was purchased, but its use has been limited to main level drifting only, because of the handling problem involved in transportation of the complete rod to mine shops for resharpening. Further trials are being made on improving the life per detachable bit by chrome plating. To date, the chrome plating shows an improvement of approximately 100 pct. However, final results will not be known until the present long term trials have been completed. Mother Mine "B" Shaft In November 1947, tungsten carbide bits were first tried at the Mather mine "B" shaft. The use of 1%-in. Carset 13 Series bits, for drilling the 72-hole, 7-ft shaft round, decreased the drilling time from an average of 41/2 hr per round required with steel bits, to 2 hr with insert bits. The best drilling time for

Jan 1, 1952

By Will H. Coghill

FLOTATION has been so closely allied with the sulfide minerals and their early and associated oily reagents that the term "oil flotation" has erroneously been applied to the entire flotation process. Today, the term "chemical flotation" might be used to advantage. Flotation literature has dealt primarily with the removal of sulfides. from non-sulfide gangues, and the separation of one sulfide from another.. Now, the application of the process to the separation of nonsulfide minerals is coming to the fore; and from the standpoint of the number of commercial minerals involved, the flotation of nonsulfides offers the larger field. Here, soap or soap-forming substances, such as the fatty acids and their derivatives, are used; hence there may well be a subdivision of the chemical flotation process called "soap flotation." Early experimenters learned that it was easy to form a froth or foam that would carry a part or all of the ore charge over the lip of the flotation machine; but this could not be regarded as flotation because of the lack of selectivity. Doubtless soap was one of the first reagents tried, and doubtless it was rejected on account of its gangue-carrying properties. Now this same gangue-carrying ability makes soap an acceptable reagent, for we are dealing with that, which among sulfides, is considered "gangue." As in the flotation of sulfides, so in the flotation of nonsulfides, the selective flocculation of the mineral and the dispersion of the gangue are the first objectives. In fact, these two phenomena epitomize flotation. They depend upon the unlike surface properties of the respective minerals; and, as long as the components of an ore have unlike surface properties, a separation is possible, at least in theory. Often in nonsulfide flotation it makes little difference which mineral floats and which is depressed; generally only a separation is sought.

Jan 1, 1932

By J. C. Cordell, C. F. Weinaug

A study of the behavior of retrograde condensation from gas mixtures was made in the presence and absence of sand in order to determine if the condensed liquid would re-vaporize in the Presence of sand. Methane-butane and methane-pentane mixtures that would form liquids by retrograde condensation when produced from a constant volume cell were used. The methane-butane mixtures of similar composition were produced by three different methods. The first two were charged into an empty cell and were produced in one case within a period of 9 hr and in the other within a period of 3 days. The third mixture was charged to a sand-packed cell and produced within a period of 9 hr. The curves relating composition of the produced gas to pressure obtained from these experiments show that equilibrium was maintained as long as liquid was condensing. However, during the portion of the pressure decline where the condensed liquid should be revaporizing, equilibrium was maintained only when the mixture was produced from the sand-packed cell. The methane-pentane mixture is produced only in the presence of sand. The data obtained for this system also show that equilibrium is maintained at all times during the pressure decline. These results indicate that revaporization is aided rather than prevented by the fact that the condensate "wets the sand." The significance to the petroleum industry of the behavior of hydrocarbons in the retrograde region is becoming increasingly important because a large percentage of reservoirs being discovered today arc of the gas-condensate type. The important characteristic of a gas-condensate reservoir is the retrograde condensation of a liquid phase throughout the reservoir if the pressure is allowed to decline. In order to prevent the loss of this retrograde liquid in some of these reservoirs, they are "cycled"; that is, the material produced from the reservoir is processed to remove the heavier hydrocarbons and the light fractions are returned to the reservoir to maintain the reservoir pressure. Another method of producing these reservoirs is Pressure depletion. There are other methods but they are not in general use. Although a large number of factors are involved in determining the optimum method of producing a reservoir, only the problem of whether the retrograde condensate resulting from pressure depletion will revaporize from sand at equilibrium conditions is considered in this paper. Also the data are limited to the methane-n-butane and the methane-n-pentane systerns at loo°F and one type of sand. Three types of tests were run in order to compare the revaporization of retrograde liquid formed in a cell with that formed in a sand-packed cell, and to establish the effect of time. The results of tests presented in this paper indicate that both time and the presence of sand promote the revaporization of

Jan 1, 1949

INTRODUCTION Much discussion has been generated over the years among geologists and engineers as to the ideal drill-hole configuration and spacing for evaluating various types of mineral deposits. Little can be found in the literature about the outcome of the programs, probably because of their subjective nature and the then lack of suitable means of scientific testing. In years past the drilling patterns and sequence were almost entirely determined by the experience and personal bias of the senior engineer, geologist, or project manager on the job. However, planning a drilling program- spacing, pattern, sequencing, etc.-is simply a specific case of sample design, or the design of a sampling program. Having been exposed in the preceding chapter to the theory of regionalized variables, and having learned something about the tools for measuring correlation, or lack of correlation, among samples within a given mineralogical population, we are now prepared to apply these concepts and new-found parameters to a scientifically designed mineral sampling program, be it by drilling or other means. FACTORS IN SAMPLING DESIGN It was shown in Chapter 8 that three major factors should be considered in any mineral

Jan 1, 1980

By Ihor A. Kunasz

Lithium minerals occur predominantly in pegmatites which contain mineral assemblages derived from the crystallization of postmagmatic fluids or from the metasomatic action by residual pegmatitic fluids. They have been the traditional sources of raw materials for ceramic and chemical industries. However, with the discovery of Searles Lake, brines became new sources of lithium. Indeed, the 1960s may well be referred to as the "brine decade" because several brine bodies of significant economic importance were discovered. In the United States, the brines of Clayton Valley, Nevada, presently exploited by Foote Mineral Co., and the Great Salt Lake of Utah, to be exploited by the Great Salt Lake Chemicals Corp., have been defined as major sources of lithium. Also a lithium-bearing brine has been discovered in Chile. Following the termination of the AEC purchase program in 1959, several companies such as Maywood Chemical Co., American Lithium Chemicals, and Quebec Lithium Corp. were forced to close down their operations. Nevertheless, with the development of new applications in glass ceramics, air conditioning systems, synthetic rubber, and metallurgy (aluminum potlines), the lithium industry grew steadily, and with the potential application of lithium metal in batteries and nuclear reactors, a healthy growth can be foreseen. New products and new applications are likely to stimulate exploration for expanded reserves as well as the search for new sources from which lithium could be extracted economically. Geochemistry of Lithium Lithium is the third element in the periodic table. It is the lightest of all the metals, having an atomic weight of 6.938. Its ionic radius is 0.60A and its charge is + 1. The geochemistry of lithium has been extensively studied and has been summarized by Rankama and Sahama (1950), Goldschmidt (1937), and Hortsman (1957). The distribution of lithium in igneous rocks is controlled by its size and its charge, and by the (MgO+FeO)/Li2O ratio. In the early stages of crystallization of a magma, that ratio is very large. Consequently, both magnesium and iron are removed by ferromagnesian minerals in preference to lithium which is then concentrated in the residual magma. This results in an enrichment of lithium in silicic rocks and pegmatites (Strock, 1936). Pegmatites are coarse-grained igneous rocks formed by the crystallization of postmagmatic fluids. Minerals within pegmatites may also form by metasomatism (Jahns. 1955). Genetically, the pegmatites are associated kith neigh- boring intrusives. Mineralogically, granitic pegmatites contain feldspar, quartz, and mica as the main constituents and a variety of exotic elements such as lithium, beryllium, tantalum, tin, and cesium, which may or may not occur in economically significant concentrations. Detailed studies by numerous investigators (Cameron et al., 1949, 1954; Hanley et al., 1950; Jahns, 1953, 1955; Page et al., 1953) indicate that pegmatites often exhibit an internal zonal arrangement, with each zone containing a specific suite of minerals. The lithium minerals are usually found in the intermediate zones, and although as many as 13 zones have been recognized by Cameron, a complete zonal arrangement is rarely found. Zoning of pegmatite bodies has also been observed on a regional basis. The regionally zoned pegmatite sequences exhibit mineral assemblages and complexity according to their respective distance from the granitic bodies to which they are genetically related (Mulligan, 1965). Lithium is also found in small proportions in a variety of rocks. The average lithium

Jan 1, 1975

By Robert Phelps

A STUDY of solid solutions has long been a source of interest because of the conditions -controlling their formation. X-ray investigations so far have been conducted with the idea that there were two types of solid solutions. In the first type, an atom of the solute was supposed to replace an atom of the solvent in the crystal lattice. In the second type, an atom of the solute was supposed to lie in one of the interstices between the atoms of the solvent. These pictures both require that the sizes of the atoms must play an important part in the process of solution. It is the purpose of the present investigation to study the mechanism of solid solution, using pure silver as the. solvent, and pure aluminum as the solute. X-ray measurements show that these elements have the same "shape" of atomic domains (they both crystallize as face-centered cubes) and that their atomic diameters differ by less than one per cent.1 The results of the present investigation point toward a chemical rather than a physical picture of the nature of solid solution, and make the older' pictures merely special cases of a more general picture. The new theory has the advantage, too, that it offers a rational explanation of certain phenomena which hitherto have been only interesting detached facts. The aluminum-silver system which was, chosen for this study has been studied by various methods by several workers. By means of thermal analysis Gautier2 and Petrenko3 have determined the phase diagram. Hansen4 studied the aluminum-rich alloys by means of thermal and microscopic analyses. , He showed that at high temperatures silver dissolved in aluminum to the extent of 47 per cent by weight at 5600 C. But this solubility decreased to 1 per cent at 200° C. Westgren and Bradley5made an extensive X-ray study of these alloys. They used the change in the lattice parameter of silver as a criterion of the solution

Jan 1, 1932

By W. E. Crandall

The No. 4 shaft and hoist at Hecla Mining Co.'s Star mine have been in operation for seven months, and as development of new mining areas proceeds in the lower portions of the mine, the system is being depended upon more extensively for personnel and material handling requirements. The hoist plant is handling full payloads, at rated speeds, over a vertical distance of 5650 ft. One of the special features of this hoist is its precision braking control under all hoisting conditions. Tests indicate that emergency stops can be made with safe deceleration rates and minimum rope and conveyance oscillation.

Jan 1, 1971

By D. K. Sarin

The sub-level caving mining method has been applied in base metal mines in Canada under a wide range of ore body and wall rock conditions. This method has been used for primary, as well as secondary mining of both small and large ore bodies of varying ore values. Early experiences of almost all operations were somewhat disappointing. This paper details the initial problems encountered, the design changes made and solutions evolved. Additional experience and the development of operating skills, have helped the method gain acceptance as a viable method for the mining conditions to which it has been adopted.

Jan 1, 1981