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By Nathan C. Rockwood

WHILE mining engineers have been searching in far corners of the country and of the world for hidden wealth there has grown up around us in nearly every city great wealth-producing mines calling for the investment of hundreds of millions of dollars and yielding products now sold for over half a billion dollars yearly-largely unknown and almost wholly neglected by mining engineers. But this neglect is explainable and excusable. They are industries of very recent origin-practically the growth of the last 25 years. They are in a very large measure the result of tremendous developments in engineering construction and the rapidly expanding use of portland cement concrete for structures of every description. Concrete as a material of construction is going through an evolution very much as did cast iron and other metals used in engineering; and this phase of the industry should appeal to the imagination of metallurgical engineers. At first iron was iron-a material of uncertain properties, owing both to small differences in chemical composition and in methods of manufacture. By successive steps iron was studied and knowledge of its properties developed-the striking effects of very small percentages of other minerals and of various heat-treatments.

Jan 1, 1924

By Eugene R. Rice

There are many methods for determining the meridian, but all of those in common use involve at least two separate observations, one for latitude and one for azimuth. Such observations made upon a south star at any hour are open to the objection of possible inaccuracy due to ignorance of the absolute refraction, and also to slow change in the altitude of the star when near the meridian. The method of observing a circum-polar star at elongation. besides requiring a separate observation for latitude, is open to the serious objection that clouds may obscure the star at the critical moment. Moreover, a tedious wait for the star to come to elongation is sometimes necessary. Many of us can recall 'long, cold, weary vigils, waiting for Polaris to reach elongation. For observing a circumpolar star at any hour, not only the latitude, but also the true time, must be known. This it is practically impossible to obtain, except in regions reached by the telegraph, and usually then one has to know the longitude also, in order to reduce " standard time" to " local time." The results obtained by this method, when the star is at culmination, are not very good, unless the true local time is absolutely known. The methods of obtaining the nleridian from the sun, by means of a solar attachment, or by direct observation, while good, are not absolute, by reason of refraction, change in declination of the sun, and small change in vertical angle, when the sun is near the meridian. For these two methods, latitude, time, and approximate longitude have to be known. In the method here described, only one observation is needed, and from it are computed azimuth, latitude, aud sidereal time. In other words, one call observe a circumpolar star—Polaris

Jan 1, 1911

By S. A. Falconer

The benefication of non-sulfide or non-metallic minerals by froth flotation has been practiced commercially for at least 30 years. In the pioneer stages of development of this flotation art, most of the promoters investigated were fatty acids or soaps that had been found to float sulfide minerals. When commercial application of froth flotation started to assume importance in the late 1920' s and 1930's, a great deal of fundamental research work was done in the laboratory (11-14, 19, 22, 23, 26, 29, 32). Among other subjects, this work included studies of the relative effectiveness of the different fatty acids and their salts on the flotability of various non-sulfide and non-metallic minerals. The successful present-day use of fatty acid and petroleum sulfonate type promoters results from better understanding of the principles of non-sulfide flotation plus the developnent of effective selectivity modifying agents. Many investigators have contributed to a greater appreciation of the numerous interrelated factors involved in fatty acid and soap flotation of non-sulfide minerals. Of these, mention should be made of recent fundamental studies by Tagart and Arbiter (31); Wolstenholme and Schulman (35); Schulman and Smith (28); Wark and his co-workers(3,4) Du FIietz(l5); and J. Leja(24). According to J. Rogers, K. L. Sutherland and E. E. and I. W. Wark(27), "the basic requirements for a 'collector' in flotation are that it shall form a film over the surface of the mineral to be floated and that this film should be oriented so that hydrocarbon (non-polar) groups form the effective surface." When modified in that way, the mineral surface possesses some degree of air avidity. All investigators would agree with Taggart, Taylor and Ince (33)that such a film can be produced only if the collector compound contains an active (polar) group to be attracted to the mineral surface, as well as the non-polar group. The commonly used anionic-type promoters for non-sulfide, non-metallic and metallic oxide ores include: 1. Fatty acids, and their soaps and emulsions. 2. Fatty acids residues — "pitches" and "foots." 3. Sulfonated and sulfated fatty acids and so-called "petroleum sulfonates." 4. Paraffin chain salts — sulfonated and sulfated higher alcohols. 5. Cyclic organic acids or salts, such as naph-thenic acid and naphthenates. Certain fatty acids are more effective than others as promoters for particular minerals under certain specified conditions. Some of the more costly fatty acids or collectors of the paraffin chain salt type may give improved selectivity in some instances and are being used commercially in a limited number of operations. Local availability may dictate the choice of the fatty acid used — for example, the use of palmoil fatty acid for flotation of copper carbonate ores in the Belgian Congo. Coconut oil fatty acids have also found limited use.

Jan 1, 1961

By Herty, C. H.

No attempt will be made here to review the previous work done by investigators on the general subject of inclusions, because it was discussed sufficiently in an early cooperative bulletin of this series (No. 36, 1928), and reference was then made to general bibliographies. The work described in this present bulletin deals directly with the study of the mechanism of deoxidation of steel with aluminum and the formation of inclusions containing alumina. Unquestion- ably, such inclusions are encountered in most steel-making practices and little has been done to determine their characteristics. Aluminum is used to ensure rapid deoxidation during the solidification stages of the steel. For this reason the possibilities of inclusion elimination are slight and alumina-containing particles will undoubtedly be present in the ingot. Besides this common practice, aluminum is often used in the ladle with other deoxidizing agents such as silicon and manganese. Ladle additions of aluminum are made to rimming steels to obtain the correct partial deoxidation desired in this type of steel. In killed steels the aluminum is added to ensure soundness, as far as blowholes are concerned, in the ingot. In either rimmed or killed steels, alumina or alumina-containing inclusions are found therein, the amount and type depending on the oxidation of the metal, the amount of aluminum added, and the addition of other deoxidizers.

Jan 1, 1957

By A. E. Chute

The shortage of sulfur is not only continuing but appears to be worsening, attended by steadily rising prices. At the same time emphasis on air-pollution abatement is also increasing. These two factors, a rising market and the growth of environmental attention, have encouraged producers to carefully review all possible sulfur sources. As a result, production of sulfur from hydrogen sulfide occurring in petroleum is receiving greater attention than ever before. Until about a decade ago, the practice of recovering sulfur from hydrogen sulfide separated from gases (either found naturally or generated in desulfurization of liquid petroleum) was wide1y recognized but contributed little to total free-world sulfur production. However, during the past ten years, the production of sulfur from this source has increased so rapidly that it now accounts for a substantial portion of total production. This trend shows no signs of slackening, and current forecasts predict that recovered sulfur may become the dominant source of supply within ten years, exceeding mined sulfur production. This paper is intended to list sulfur sources and relationships, and to discuss the potential of producing sulfur from petroleum. The processing involved, in addition to product storage and transportation will also be discussed along with important economic aspects of sulfur recovered from hydrogen sulfide. For many years, most of the world's elemental sulfur has been produced from salt domes, predominantly by the Frasch process. During the past decade, however, another production source has developed so quickly that it is expected to surpass the Frasch production sources within a short time. This new source lies in the petroleum gases and liquids from which dramatically increasing quantities of elemental sulfur are being recovered. In the phraseology of the trade, the sulfur so obtained is know as "recovered sulfur," a term which does not, as one might expect, include sulfur recovered from other sources such as smelter gases. The growth rate of recovered sulfur compared to that of Frasch sulfur, total elemental sulfur, and total Free World sulfur in all forms is shown in Fig. 1 Since 1963, sulfur consumption has exceeded production,with the natural result that the price of sulfurhas continually increased. The posted price reported for f.o.b. Port Sulphur, La., has risen from as low as $18 per ton in 1962 to $32.50 per ton in mid-1967. With freight and other charges, delivered prices have of course run much higher, amounting to $45 or $46 per ton on the east and west coasts. In some cases, spot sales for as much as $60 have been reported. Although it is playing an ever-increasing role in the sulfur market, recovered sulfur was originally a by-product of the removal of hydrogen sulfide from natural and petroleum refinery gases. Today, however, it is often the most valuable product of a multi-product processing facility. Since there are two major sources of recovered sulfur—production and refining processes —natural gas is included with liquid petroleum for purposes of this discussion. Sulfur from these sources is produced in the form of gaseous hydrogen sulfide which is removed from a gas stream and converted to elemental sulfur. Gases in which hydrogen sulfide occurs naturally are natural gas and the gas produced from a high=pres-sure crude=oil or condensate field.

Jan 1, 1969

By AIME AIME

American Institute of Mining Engineers. (Organized in 1871, and Incorporated in 1905.) OFFICERS. For the year ending February, 1906. Directors JAMES GAYLEY (President), R. W. RAYMOND (Secretary), FRANK LYMAN Treasurer). T. A. RICKARD NEW YORK, N. Y. CHARLES H. SNOW NEW YORK, N. Y. R. W. RAYMOND NEW YORK, N. Y. (Terms expire February, 1906.) JAMES GAYLEY NEW YORK, N. Y. FRANK KLEPETKO NEW YORK, N. Y. FRANK LYMAN NEW YORK, N. Y. (Terms expire February, 1907.) JAMES DOUGLAS NEW YORK, N. Y. JAMES F. KEMP NEW YORK, N. Y. ALBERT R. LEDOUX NEW YORK, N. Y. (Terms expire February, 1908.)

Jan 1, 1906

By Ivan E. Goodner, Charles H. Fulton

THE subject of the constitution of copper-iron mattes has received considerable attention in recent years by Keller,1 Bolles,2 Hofman,3 and Gibb and Philp.4 Still more recently Friedrich, Röntgen, Wiedmann, Heyn and Bauer, and Leroux have published, in some instances, elaborate researches on the various systems of the sulphides, and the sulphides and their respective metals, which enter into the constitution of mattes, and have added very greatly to the knowledge of the subject. The work of Friedrich has been especially fruitful. But to date no effort has been made to correlate the data obtained in the latter researches and apply then to the study of the product called " matte," which is made in such large quantities by copper and lead-smelters. In this paper we propose to determine, by metallographic and chemical means, the constitution of copper-iron and copper-lead mattes in the light of the recent data above mentioned. We do not discuss copper-nickel mattes or speisses (artificial arsenides). The paper is divided into three sections I. A review and discussion of the various binary systems of the metallic, sulphides, and the binary systems of various metals and their respective sulphides entering into the constitution of mattes; also a discussion of the physical and chemical properties of these sulphides. II. A description of the results obtained from the chemical and metallographic examinations of the samples of copper-iron and copper-lead-iron matte obtained from various plants.

Nov 1, 1908

By F. J. Chernosky

Most previous studies of coal flotation utilized chemically pure reagents. Since such reagents are not available in quantity, a study of various wmmercially available reagents as frothers was undertaken. Flotation procedures similar to those used in a large number of commercial coal flotation plants were employed. The reagents used were compared on yield-selectivity-wst basis. The selectivity was found to be relatively constant with yields above 70% but the reagent cost varied greatly. The types of reagents available were compared. In the past, a number of papers have been written on the use of various reagents as coal flotation frothers. For the most part, these have been an attempt to correlate the intrinsic chemical and physical proper- ties of the reagents or reagent groups to the floata-bility of various fine coals. Because of the type or nature of evaluations made, chemically pure reagents were normally used. Generally, these reagents are unavailable in commercial quantities. Therefore, the results obtained with these reagents were usually limited in usefulness to the plant operator or metallurgist. This paper presents the results of a study in which commercially available forms of various reagents were used as flotation frothers. Flotation procedures which would conform in general to those employed in a large number of commercial coal flotation plants were utilized. The objective of the test was to compare these reagents on yield-selectivity-cost basis, that is, 1) the yields obtained, 2) the ash levels obtained and 3) the reagent cost relating to these results. REAGENTS The reagents employed have been grouped into the following chemical classes: 1) aliphatic alcohols, 2) terpines, 3) glycols (synthetic water-soluble

Jan 1, 1963

By J. F. Shea, O. F. Tangel

Battelle Memorial Institute participated in a program for the General Services Administration aimed at developing a nickel-cobalt separation process that could be integrated in the Nicaro nickel plant. At the time the programwas being carried out, the Nicaro process was a straight-through operation, in which the ore was reduced and leached, after which the pregnant solution was boiled to produce a so-called "bulk precipitate" which contained virtually all of the nickel and cobalt which had been dissolved in the leaching step. The weight ratio of nickel to cobalt in Nicaro ore is approximately 15 to 20:l. The weight ratio of nickel to cobalt in the finished product had to be 100:l or higher to meet specifications. Because the Nicaro process embodied no nickel-cobalt separation step, the only way that a bulk precipitate of the specified nicke1:cobalt ratio could be produced was to so adjust roasting and leaching conditions that nickel would be selectively leached and most of the cobalt would be rejected with the tailings. The required selectivity, however, was achieved at the expense of nickel recovery, which was 5 or more per cent less than might have been obtained with the existing equipment, utilities, man power, etc., had selectivity been no object. The over-all purpose of the program was to develop a separation step that could be fitted into or onto the Nicaro facilities and which would permit the manufacture of a product that would meet the desired specifications and still permit the recovery of a maximum amount of nickel. Battelle suggested that this might be accomplished by reprocessing off-specification bulk precipitate and specifically suggested the process based on ammonium sulphate leaching followed by hydrogen reduction of the leach solution according to techniques developed commercially by Sherritt Gordon Mines Limited. Such a process would not only satisfy the objectives of the research but would present two additional advantages. (1) It would produce a separate cobalt product which could be further processed into metal, alloys, oxides, or salts. (2) It would yield nickel in metallic form which might be more generally marketable and command a slightly higher price per unit of nickel than the Nicaro oxide product. DESCRIPTION OF THE PROCESS Figure 1 is a flowsheet of the process. The essential features are: (1) Extraction of about 97 per cent of the nickel and about 85 per cent of the cobalt from bulk precipitate by a principal leach with ainmonium sulphate solution (Step A). Extraction of virtually all of

Jan 1, 1961

By L. F. Bishop

THE ore bodies of the Butte district1 are found in many different vein systems having many different structural characteristics; some are narrow with self-supporting ore but with weak walls; some are wide with weak or strong ore and weak walls; some of the veins dip steeply and others do not; some have well defined walls, and others, in the "horsetail" area, are mined to sample limits. Consequently, many types of stoping methods are used in mining these ores. The stoping methods used in the Anaconda Copper Mining Company's properties are the square-set and cut-and-fill. The square-set method is the principal stoping method used because, generally speaking, the ore and walls are weak, the ore is high grade, and good extraction is required. These square-set stopes may be classified as conventional, vertical slice, slot, timber rill, and Mitchell slice types. The conventional type square-sets are those of various shapes and sizes, mined by horizontal slicing to the boundaries of the stopes. The rock is slid to the chute and the filling is moved by gravity. The ore and waste may be handled with a scraper when local conditions require it. The vertical-slice square-set system is the type used in narrow veins that are mined in vertical panels. The slot stopes are stopes in wide veins that employ a slot across the vein instead of a con- ventional chute to handle the ore. The timber rill fs a type of square set in which the ore is mined as in inclined cut and fill but the square-set timber is used. The Mitchell slice is the type used for some broken or heavy ore blocks, or for pillar extraction between two converging slot stopes. The cut-and-fill method is used where the ore will stand without much support although the walls may be weak. The principal type of this method is the horizontal cut-and-fill, with mechanical scraping. The inclined cut-and-fill, or rill, stopes are used in some veins too narrow for scraping. The production from the various meth: ods in use for the second six months of 1944 are shown in Table I. [ ] This paper deals mainly with the vertical slice and slot types of square-set stoping, because of their effect on production locally and their potential possibilities here and in other districts, with sufficient reference to conventional square-setting for comparison.

Jan 1, 1945

By J. Gurland

The effect of four different second-phase additions on the strength of composite alloys with a common matrix was investigated. The four compositions each consisted of 85 pct by volume of silver with additions of 15 pct of either tungsten, molybdenum, tungsten carbide, or nickel. These particular additives were chosen because of their low mutual solid solubilities with silver at room temperature, the alloys consisting essentially of a dispersion strengthened silver matrix in which the second phase is distributed randomly. Test specimens were prepared by a powder metallurgy procedure consisting of ball milling the mixed powders, compacting, and sintering at 920°C for 1 hr in hydrogen. The constituent powders were of CP quality and of particle size between 2 and 10 ?. The compacts were subsequently hot pressed at 1000 psi and 1400° in an Inconel die, coined at room temperature at 60,000 psi and finally annealed and outgassed in vacuum at 800°F. The microstructures of the alloys are shown in Fig. 1, and the microscopically observed porosity grade was A-2 or better as evaluated by ASTM Recommended Practice B 276-54. The properties of the sintered compacts are listed in Table I, and the load-deformation curves in bending are shown in Fig. 2. The samples, of rectangular cross section, were loaded at the center of 58 in. span, and the reported stress was calculated on the basis of linearly elastic behavior in order to allow the comparison of specimens of slightly different dimensions. It is apparent that the tungsten, molybdenum, and tungsten carbide alloys exhibit very similar deformation curves. The moduli of elasticity were determined from the slopes of the stress-deflection curves at small loads. The measured values agree quite well with those calculated by the strength of materials approximation proposed by Paul1 for the elastic constants of mixtures, the calculated values being 15.0, 15.0, 17.4, and 13.4 million psi, respectively, for the tungsten, molybdenum, tungsten carbide, and nickel combinations with silver. The strength of the Ag-Ni composition is appreciably lower than that of the other three alloys. The discrepancy between the two groups is accounted for by the following characteristics of deformation and failure which were observed microscopically during the tests: A) The deformation of the W, Mo, and WC alloys did not involve the second phase particles to any appreciable extent. Slip and fracture took place in the silver-rich matrix alone, although the fracture path generally skirted the particles by favoring the phase boundaries. The deformation proceeded according to the following sequence: 1) formation of small, discontinuous microcracks in areas of the matrix adjacent to a particle, 2) general slip in the matrix and extension of cracks, 3) failure of specimens by propagation of cracks through matrix. The near coincidence of the 3 load-deflection curves suggests that the nature of the second phase particles does not decisively influence the plastic behavior of composite alloys of this composition as long as the particles do not undergo any considerable deformation themselves. B) A markedly different behavior was exhibited by the Ag-Ni composition where the relatively low flow strength is associated with the low yield strength of the nickel grains. Slip in the nickel grains was first observed at a stress of approximately 10,000 psi, although failure, at a later stage, took place by the propagation of cracks through the matrix. The ductility of this aggregate, in which both components deform plastically, is appreciably greater than that of the elastic-plastic composites. In summary: 1) The measured values of the moduli of elasticity of the composite alloys under discussion are in good agreement with the "strength of materials" approximation proposed by Paul.' 2) The overall plastic behavior of these particle-strengthened alloys is unaffected by the nature of the second phase particles, if the latter remain elastic. This work was supported by the Office of Naval Research. The experimental results are presented

Jan 1, 1962

By R. B. Booth, W. F. Linke

The continuous interest of the American Cyanamid Company in producing superior polymeric flocculants and dispersants for the mining industry has resulted in a broad, general study of the physical chemistry of mineral-polymer systems. The aim of this program has been to establish a sound theoretical basis on which practical problems could be analyzed, and which would lead to the development of new and improved flocculating and dispersing agents. This study has required the cooperative effort of physical, analytical, and polymer chemists, as well as engineers familiar with mining problems. This report summarizes the results of some of our investigations over the past two years. Further studies along these and other lines are in progress and will be reported in the near future. MEASURING FLOCCULATION IN THE LABORATORY The foremost problem in studying flocculation in the laboratory has been to establish reproducible methods of comparing and evaluating the effectiveness of various reagents. Previous workers have measured settling -rates 1,8 filtration rates2 , and sediment volumes3 . Direct observations of the floc size, or the clarity of the supernatant liquid, can also be used. AIthough these parameters are all interrelated, they do not always measure the same physical properties of the suspensions, and hence are not equally useful or reliable. Whatever the method of comparison selected. the testing procedure must be carefully defined and standardized. The results must be satisfactorily reproducible, and for practical purposes must accurately reflect the results obtained in mill use. In order to compare the data obtained in these various types of test, the physical nature of the flocculated system must be examined in some detail. In an unflocculated system, only the larger or denser particles (the "sands") settle at a useful rate. The sediment can be observed to build up from the bottom of the cylinder, while the fines remain in suspension for a long period of time. If the system is not disturbed, even the microscopic fines can be seen to classify themselves as they fall over a period of days. When a high molecular weight polymer is added to the system, the colloidal particles are tied together randomly in flocs, and the sands and fines settle together. The line of demarkation between solid and liquid phases moves downward from the top of the cylinder. The settling rate of the flocs depends on their size and on their effective density. For a given mineral sample, the larger the flocs, the faster the settling. Since the large flocs cannot pack as closely as small ones, they produce a sediment with more pore spaces, and hence of larger volume, which is easier to pump and to agitate. Although it is nearly impossible to measure individual floc sizes, it is relatively easy to determine settling rates and sediment volumes. Of these two, the settling rate is simpIer to measure, and hence generally more practical. Reproducible sediment volumes can only be obtained by allowing the solids to pack for a rather long period of time (e.g., hours to days), and although the volumes thus observed are directly related to the degree of flocculation (average floc size), it is often impractical to wait so long for the results.

Jan 1, 1961

By Louis, Jordan

THIS paper presents in an abbreviated form the chief points of interest in an investigation of the tarnish-resistant qualities of silver alloys, an investigation which has been carried out as a joint research by the Bureau of Mines and the Bureau of Standards and will later be reported in detail in an official publication from these bureaus. In 1923 a Commission of Gold and Silver Inquiry was created by a Resolution of the U. S. Senate to study the causes of the depressed condition of the gold and silver industry. In cooperation with this commission the Bureau of Mines made a preliminary survey to determine in what ways, if any, it might be possible to increase the uses of silver. One of the possibilities indicated by this survey was the development of silver alloys which should be non-tarnishing, or at least less-tarnishing, than the usual sterling silver (copper-silver). The preparation of a rather wide variety of silver alloys and the determination of their behavior under accelerated tarnish tests in the laboratory was therefore undertaken by the Bureau of Mines and Bureau of Standards as a joint investigation.

Jan 1, 1927

By C. G. Cheriton

The Bathurst mining district is located near the town of Bathurst on the north shore of the province of New Brunswick in eastern Canada. This region is the northeasterly extension of the Appalachian mountain system. The area is heavily forested and covered with a fairly uniform layer of glacial gravels and boulder clay. The relief is low, increasing to a few hundred feet in the north west and several hundred feet in the extreme southwest. Thus, rock outcrops are scarce and occur mostly along streams and ridges. These factors made conventional prospecting difficult and resulted in the district becoming an excellent place for the application of regional geological studies, air photo techniques, airborne and gound geophysical methods and soil sampling. Late in 1952, The Brunswick Mining and Smelting Company discovered a very large base metal sulphide body presently known as their No. 6 orebody. Early in 1953, another and even larger sulphide body was discovered and is known as the No. 12 ore body. Mining exploration was very active thoughout 1953 and in 1954, The American Metal Company discovered the orebodies which have been developed into The Heath Steele 'Mines. The location of these deposits is shown on figure one. In the latter part of 1954, The Anaconda Company became interested in the district and decided to make a geological study of this new and promising base rrietal area. The following paper presents the story of the application of modern geological and geophysical techniques, leading to the discovery of a large sul-nhidp liodv. The Bathurst district is generally underlain by the Tetagouche group of Middle Ordovician rocks.

Jan 1, 1961

By H. W. Gillett

CLYDE WILLIAMS has reminded me that in the fall of 1929, gave, in MINING AND METALLURGY, an account of the hopes and aspirations of Battelle Memorial Institute, which was then just swinging into initial operation; and that therein I remarked that B.M.I. should stand, as well, for Better Metallurgical Industries, since helping to better them was the Institute's aim. So he has suggested that some of the betterments of the past fifteen years might well be listed. A yearly summary of progress comes pretty close to the ultimate in futility, for everything proved of value in that year had its inception in earlier years, and everything really new has still to be proved. Plenty of things hailed as wonderful achievements for that year, by some enthusiasts invited to contribute to the summary, turn out in later years to be inglorious flops. But over a decade and a half, betterments that are really such become self-evident, and recounting some of them can be done without guesswork or wishful thinking. An inventory of what was known and utilized in 1929 compared to what is now known and used is not too hard to make. Perhaps the most clear-cut picture of what is known and used at a certain date is drawn by the handbooks, textbooks, and equipment catalogs of that date, with scientific periodical literature forecasting what knowledge may later be used when it is verified and assimilated. The tools available for production or for research limit the application of old and the finding of new knowledge.

Jan 1, 1945

By H. T. Kennedy, S. M. Avasthi

An equation developed for gaseous hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 0.73 percent when applied to 264 natural gas and condensate systems including 2,043 PVT points. Another equation developed for liquid hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 1.12 percent when applied to 346 crude oil systems including 1,759 PVT points. Both equations require composition of the mixture to be expressed as mole fraction of methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide, together with the characteristics of the heptanes-plus fraction in addition to the temperature and pressure. The equations cover wide ranges of the variables involved, and their accuracy is considerably better than that of other available methods. The equations were differentiated to allow calculation of the coefficients of isothermal compressibility and isobaric thermal expansion. (In this paper the coefficient of isothermal com-pressibility and the coefficient of isobaric thermal expansion will be expressed as compressibility and thermal expansion coefficient, respectively.) Equations to calculate these quantities are presented. INTRODUCTION Calculations of reservoir performance for petroleum reservoirs require accurate knowledge of the volumetric behavior of hydrocarbon mixtures, both liquid and gaseous. Compressibilities are required in transient fluid flow problems, and thermal expansion coefficients are important in thermal methods of production. An accurate laboratory investigation of the PVT behavior of each reservoir fluid encountered would be costly and time consuming. For this reason various correlations for predicting fluid properties have been developed and recorded in recent literature. Correlations have been presented in the form of graphs, tables and equations. Since an increasing number of studies are being conducted with the aid of electronic computers, recent efforts have been directed toward development of correla-tions suitable for computer programming. Application of computers permits the use of more complex correlations which otherwise are not feasible. Moreover, methods for predicting reservoir performance, particularly those based on the compositional material balance, depend upon the capability of accurately expressing the molal volumes and other fluid properties as functions of pressure, temperature and composition. The coefficient of isothermal compressibility c is defined by

Jan 1, 1969

By J. B. Clark

In multiphase ternary diffusion studies, plots of the variation bf the composition on the isotherm constitutes one of the most effective methods of presenting experimental results, especially if such plots are made in a manner which relates the composition path on the isotherm with the diffusion layer structure in the couple. Unfortunately, if different conventions for plotting are used serious misinterpretations occur readily, causing apparent disagreement between investigators who actually share the same viewpoint. A common convention for mapping these diffusion paths is needed at this time because with the increasing use of the electron-probe X-ray microanalyzer, a much greater number of ternary diffusion studies can be expected in the near future. In an effort to prevent unnecessary confusion in the future litera- ture, a convention for these plots is proposed, as outlined below. A hypothetical example of the use of these conventions is given in Fig. 1 where the path of composition through the diffusion structure of the 100 pct A/50 pct B, 50 pct C couple is plotted on the appropriate isotherm of the ABC system. The lower case letters relate the region in the diffusion layer structure to the appropriate composition on the ternary isotherm. 1) The diffusion path is plotted on the isothermal section corresponding to the diffusion temperature of the couple. 2) The terminal compositions of the plotted diffusion path are the initial compositions of the couple halves—provided infinite boundary conditions are maintained. If, in either couple half, infinite conditions are not maintained, then the path terminates at the composition of the exterior surface of the couple. If, at this surface, the composition varies with time or if the plotted path is time dependent, then the diffusion time should be noted beside the plotted path. 3) A solid line crossing a single phase field (e.g., line a-b in Fig. 1) denotes an existing layer of that phase in the diffused couple. 4) A dashed line crossing a two-phase field parallel to the tie lines (e.g., line g-h) represents an interface between the two phases with interfacial compositions designated by the ends of the tie-line. The line represents no spatial extent. 5) A solid line crossing a two-phase field so as to cut tie lines (e.g., line b-c or line j-k) represents a locally equilibrated columnar two-phase layer. The solid line should cut those tie lines which correspond to the lateral interfacial equilibria along the columnar

Jan 1, 1963

By R. C. Earlougher

Jan 1, 1970

By Joseph Moses Botbol

In passing the judgments essential to his trade, the geologist may be assisted by two new methods. These will enable him to (1) arrange the minerals of a selected group of base metal mining districts in the order of their typicalities and (2) compute the degree of mineralogic association between the model so derived and a district external to the model. It must be remembered, of course, that the methods discussed in this article are no more powerful than the structure of the model used and the data available. The geologist who employs these techniques must still exercise his expertise

Jan 1, 1970

By Nathan C. Rockwood

THE title of this paper, I understand, was suggested by professional mining engineers as an opportunity for someone to pose problems rather than to offer solutions for them, but the paper will merely attempt to pose some of the production problems of the mineral aggregates industry in such manner as to create professional interest in their solution by the mining engineer, geologist, geochemist and the metallurgical engineer versed in mineral-dressing technique. DEFINITION OF MINERAL AGGREGATES "Mineral aggregates" may be defined as fragments of any rock or mineral used to supply bulk or volume or substance for a given purpose. For example, mineral aggregates are used in portland-cement concrete to provide bulk with the expenditure of the least feasible amount of cement binder. Mineral aggregates are used without portland cement or bituminous binder in highway and railway roadbeds to provide substance, to carry loads. Mineral aggregates are used in filters for water and sewage, to provide substance for the liquid to trickle through. These are only a few typical uses of mineral aggregates. For all these uses, strength, toughness, resistance to abrasion, and durability are usually prime requisites; so, while theoretically mineral aggregates may be of any mineral composition, what really is desired is a mineral composition as nearly inert under the conditions of use as anything of earthly origin can be. EXPLORATION AND POSSIBILITIES OF DEVELOPMENT The distribution of deposits of mineral aggregate is universal, since almost any part of the earth's crust can be used; even the top soil is sometimes used in stabilized surfacing for highways or airport runways. Nevertheless there is ample opportunity for exercise of the talents of the mining engineer and the geologist in finding the particular deposit that will be most economical to develop, keeping in mind such considerations as: (1) quality and mineralogical characteristics of the material; (2) size and permanency of the market; (3) final cost of opening and development of the deposit; (4) selection of location of plant; (5) methods and costs of distribution of the product in comparison with both present and possible future competition; (6) selection of the proper type of operating equipment; (7) estimation of probable waste products and their disposal. These are typical but there are other considerations also. Because profit margins are far smaller than in any comparable mining operation, it is all the more logical to assume that a higher degree of expert knowledge is desirable to make a success of a mineral-aggregates business. The industry has much engineering talent in its operating branch, but it lacks, to a considerable

Jan 1, 1943