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By R. L. Minckler

PETROLEUM industry forecasts are constantly made and revised but are not in the nature of predictions. Particularly in the field of demand, many of the factors are far beyond control by the producing industry. Supply reacts on demand and demand reacts on supply. Competent economists in the oil business forecasted a year ago, on the basis of experience, that demand would now be at a much lower level than it is. This increased demand increased the price of crude oil and products, and in turn those increased prices have brought forth increased supply. A reduction in demand would lead to a reduction in supply. Shortages are now world-wide, and costs of secondary importance, so if there were extra supplies in California they would be moved into what are termed "unnatural markets." For example, Argentina is in the market today for California gasoline; that is an unnatural market because of the greater transportation distances from California to Argentina than from normal sources.

Jan 1, 1947

By AIME AIME

ON May 5, the Washington, D. C., Section, A.I.M.E., devoted its meeting to the many-sided and perplexing question of mineral stock-piling for peace. Opening the symposium, Harry J. Wolf, of the War Production Board, outlined the problem under six heads: (1) Technical. Mechanical, chemical, or metallurgical importance of specified materials, emergencies that might arise, relative scarcity, and critical value of stock piles during emergencies. (2) Economic. Cost to Government, influence of Government stocks on commercial relationships and markets, effect of availability of items as a con¬structive influence on industry, Administration policies now and during postwar period. (3) Legislative. Need for immediate legislative action, need for legislation on postwar conditions as well as on current requirements, a constructive basic policy to prevent political manipulation. (4) Military. Consideration of re¬quirements and supplies bearing on national safety and needed for manufacture of equipment, and adequate reserves of scarce materials for research or experimentation by military agencies. (5) International. Interests of the United Nations in contradistinction to those of the United States; effects of nonisolation policy on nature, location, and administration of stock piles. (6) Negative stock-piling. Question of United Nations' legislation to prevent stock-piling by Axis nations after the war and who shall purchase stock-pile materials and during what periods.

Jan 1, 1943

By Blair R. Benner

This paper describes the installation and operation of a Texas Nuclear on-line silica analyzer (NOLA) coupled with a Leeds and Northrup Microtrac particle-size monitor (Microtrac) at U.S. Steel's Minntac taconite concentrator. An automatic sampling system provides the NOLA with samples of final concentrate. After the sample is analyzed for silica by the NOLA, it is pumped to the Microtrac for size and surface area measurement. A sample is analyzed every six minutes, providing the control room with the silica concentration, the percent passing 270, 400, and 500 mesh, and an equivalent Blaine surface area number. When fed a slurry of final concentrate containing between 20 and 70% solids and 5 to 6% silica, the NOLA analysis is within ±0.2% of the wet chemistry silica. The agreement between the Microtrac output and standard screen analyses is ±1.2% at 270 mesh; ±1.5% at 400 mesh, and ±2% at 500 mesh. The poorer disagreement at the finer sizes is mainly due to inaccuracies in screening at 400 and 500 mesh. The agreement between Microtrac surface area a d laboratory Blaine surface area is about 9 ±80 cm 2/g. These instruments provide rapid and reliable feedback information to the concentrator and feed forward information to the agglomerator.

Jan 1, 1984

By B. M. Larsen, K. Heindlhofer

Jan 1, 1945

By Hans Lundberg

AFTER the war years, great activity has been shown in geophysical exploration for ore. The appreciation by mining and government geologists of geophysical techniques and results is largely responsible for the popularity of these methods. In Canada, plans are being made to study, by geophysical methods, the structure of a portion of the Pre-Cambrian shield in the hope that such studies will not only give a clearer picture of the geology, but will be of direct aid to the mining companies when selecting areas for detailed prospecting. Although geophysics thus has become more popular, some engineers are still reluctant to employ the methods to their full extent. Allotted funds are often rather low, so that the least expensive

Jan 1, 1947

By C. G., Fink

The dissolution of gold by cyanide solutions was studied by determining the time required for the solvents to dissolve gold leaf. Minute traces, even 0.5 ppm, of sulphide ion retard the dissolution of gold, and this behavior cannot be accounted for by the presently accepted hypotheses involving oxygen-depletion or thiocyanate formation. On the other hand, traces of the salts of lead, bismuth, mercury, and thallium considerably accelerate the dissolution. The beneficial effect of lead is dependent upon the pH and cyanide ion concentration of the solution.

Jan 1, 1950

By Elmer W. Pehrson

OPINION seems widely divergent as to where we stand with respect to future mineral supply. From some quarters we hear that the United States is about to become a "have-not" nation and about to experience the evil consequences such a situation would entail. Others claim that we are still a treasure house of stored-up mineral wealth, the surface of which barely has been scratched. The data to be presented here support the conclusion that neither of these viewpoints is correct and that we are far from exhaustion of those mineral resources that are basic to our industrial economy. However, exhaustion is well advanced in a number of important subsidiary minerals so that we can no longer drift along with the easy-going philosophy that the earth will provide. The time has come when we must recognize the true situation and do something about it.

Jan 1, 1945

By S. E. Haszko

SEVERAL new XGa2 intermetallic compounds, Table 1, where X is a rare earth, having the AlB, structure were prepared as part of a continuing study of the magnetic and structural properties of rare-earth alloys.' In this note, the crystallographic results of these compounds are presented. Chart, Eq. 121 for the data in Fig. 1 can be adequately represented by The corresponding standard free-energy change is AF; = -4.576 T log K = -20,900 + 10.20T [5I At low nitrogen concentrations the ratio of mole fraction to weight percentage is a constant so that the mole fraction X of nitrogen is given by X = 0.0392 [%NJ. At low values of X, the activity and the concearation approach each other, hence K, = 0.0392 K,, where K, is expressed in terms of the mole fraction of nitrogen. Hence Eqs. [4]. and [5] become

Jan 1, 1962

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, graduate engineer, aged 44, with over 22 years' experience in connection with the development of large coal and coke properties in different parts of the country, desires position as general manager or general superintendent of large bituminous coal producer, or will take an interest and the management of a smaller operation. No. 258 Member, aged 41, mining engineer, manager or general superintendent, 20 years' experience, 10 years in Mexico, 5 years Western States, 5 years abroad. Guarantee results, fluent Spanish, excellent references. New York interview. No. 282. Member, technical mining graduate, 10 years' experience, especially in design, erection, construction and purchase of power and mining equipment and supplies, desires position in purchasing department. Married, aged 32, employed at present, references furnished. No. 295.

Jan 6, 1916

By D. R. George

Preliminary research has identified several organic and aqueous solutions that are effective absorbents for SO, from simulated smelter gas containing 0.3 to 2% SO2. These SO2 loaded solutions are also compatible to the reaction of H2S and SO2 to precipitate a readily filtered elemental sulfur. The economic removal of SO2 and production of elemental sulfur from stack gases discharged by base- metal smelters is a challenging goal. The magnitude of this task is illustrated by the estimate that about 3.5 million tons of SO2 are discharged to the atmosphere by smelters annually in the U.S. The SO2 concentration of the gases ranges from about 0.5 to more than 3%. As the sulfur content of SO2 is 50% a potential production of 1,750,000 tons of sulfur per year is indicated.

Jan 1, 1970

By Richard L. Gordon, Charles J. Johnson

Electric power demand doubles about every ten years, and because of the associated burgeoning fuel requirements, power stations absorb over half of the coal output in the United States. Throughout the 1960's, demand for coal utilized to generate electricity grew at an average annual rate of 6.5% but coal producers held back greater expansion because they expected nuclear plants to proliferate faster than they actually did. Even so, the growth rate is expected to continue at the 1960's rate until at least 1976. The continuation of the 6.5% growth rate beyond 1976, however, will require additional orders for coal-fired plants during the early 1970's. In fact, plants consuming a total of 130 million tons of coal must be ordered in the next few years. If the requisite plants materialize, total 1980 coal output for electrical power generation will be approximately 600 million tons.

Jan 1, 1971

By B. P. Bellport

When tunneling crews set world records in rates of advance by boring up to 403 ft in a single day and 6851 ft in a month, then the age of rapid under- ground excavation is near at hand with its attendant economies. Boring machines excavate tunnels with uniform diameters and smooth walls and only about 5% overbreak compared to 20% overbreak experienced by conventional drill-blast methods. This advantage minimizes the concrete required for lining and because a circular section is more nearly self-supporting there is less of a need for supports before the concrete is placed. In addition, laser beam guidance improves the accuracy of excavation with boring machines. In the first successful application of laser guidance for boring machines in the Navajo Indian Irrigation Project, the final excavation was within 5/8 in. of the established line and grade over a 10.079- ft advance.

Jan 1, 1971

By James S. Browning

The Mineral Resources Institute and State Mine Experiment Station of the University of Alabama conducted Humphreys spiral tests on fine coal waste from nine preparation plants of Alabama strip mining operations to determine the feasibility of recovering low ash and sulfur fuel meeting steam coal specifications. The ash in the samples ranged from 9 - 5l%, and the total sulfur ranged from 0.4J- 2.39%. Continuous laboratory tests using a Humphreys spiral gave good recovery of the coal with excellent rejection of the ash and pyritic sulfur. Coal recoveries of 83.6 - 94.1% were achieved from the different samples. Ash content of the clean coal products fell within a range of 5 - 12.2%, with a total sulfur content of 0.62 and 1.10%. In quality, the products were comparable or superior to those now being shipped from the preparation plants.

Jan 1, 1980

POSITIONS VACANT A steel manufacturing company is desirous of securing an assistant superintendent for its plant. Experience in open-hearth plants and in rolling mills particularly desirable. No. 112. Opening as assistant superintendent of a non-ferrous smelting plant. Man with metallurgical experience preferred but chief essential is ability to handle men. No. 114. ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, aged 41, mining engineer, manager or general superintendent, 20 years' experience, 10 years in Mexico, 5 years Western States, 5 years abroad. Guarantee results, fluent. Spanish, excellent references. New York interview. No. 282. Member, technical mining graduate, 10 years' experience, especially in design, erection, construction and purchase of power and mining equipment and supplies, desires position in purchasing department. Married, aged 32, employed at present, references furnished. No. 295.

Jan 7, 1916

By Parviz Montazer, Robert King, William Ubbes, Gideon Chitombo

This paper describes the results of a detailed study that was undertaken to define the spatial distribution of permeability within a five meter thick envelope around the CSM/ONWI room. Detailed fracture orientations and distribution were determined through mapping of the walls of the opening, logging of oriented core, and visual examination of borehole walls with a borescope and a T.V. camera. Over 3,500 measurements were made from which the three dimensional distribution of fractures was determined. Two principally different testing equipment designs and various methods of air injection tests were used in all boreholes to identify and characterize conductive fractures. Through analizing the distribution of permeability and fracture index around the room a zone of blast damage of approximately .5 m thickness was delineated. The effect of stress modification seems to extend farther into the host rock to approximately 3.5 m depth.

Jan 1, 1982

By G. Y. Chin, W. L. Mammel

The problem of selection of the active slip systems for a crystal undergoing an arbitrary strain has been analyzed by Taylor and by Bishop and Hill. The Taylor analysis is based on a principle of' virtual work, and involves finding, among numerous cotnbinalions of slip systems that satisfy the imposed strain, the combination in which the sum of the glide shears is a minimum. Previously, Taylor has treated the case of axisymmetric flow when slip occurs on (111)(110) (or {110)(111)) systems only. His analysis has now been extended by computer methods to the cases of slip on {112}(111) and {123)(111) systerns and of mixed slip on {110), {1 12), and (123) planes with a common (111) slip direction, all of which are important in the deformation of bcc crystals. The results are computer-plotted as contours of the ratio of the floe strength to the critical resolved slzea-r stress for slip, for axial orientations distributed throughout the standard stereographic triangle. Implications of the computer results to texture develop,merit, texture hardening, and dislocation theories oj work hardening are discussed. WhEN a single crystal is extended in the usual tension test, the lateral dimensions can change relatively freely. In this case, the glide shear produced by slip on a single slip system is sufficient to accommodate the (tensile) deformation. Since slip is governed by a critical resolved shear stress law (the Schmid law'), the single active slip system is one for which the stress, resolved on the slip plane and in the slip direction, is the highest among the several equivalent slip systems. This amounts to saying that a value M = U/t = y/~ is a minimum among the equivalent systems, where M is the inverse of the familiar Schmid factor (a and E refer to tensile stress and strain, and T and y refer to resolved shear stress and shear strain). A grain embedded in a polycrystalline aggregate, on the other hand, cannot freely change its shape due to constraint from its neighbors. In this case, slip from five independent slip systems (to accommodate five independent strains) is generally required.' Based on the principle of virtual work and assuming that the critical resolved shear stress for slip is the same for all systems, Taylor hypothesized that, among all combinations of (five) slip systems which are capable of accommodating the imposed strain, the active combination is that one for which the sum of the absolute values of the glide shears is a minimum. Again, this is equivalent to saying that the value of M = CjlyjI/ is a minimum, in analogy to the single slip case. Taylor aminimum,analyzed the case of {111)(110) slip for fcc metals, and applied the analysis to crystals undergoing axisymmetric flow, that is, the same macroscopic shape change as the poly crystalline aggregate under uniaxial tension (or compression). For the twelve equivalent {111}( 110) slip systems, there are 384 independent combinations of selecting five systems to satisfy the five independent linear equations of imposed strain.4 Taylor calculated the value of M for each combination* and obtained the active com- *A number of the independent combinations were omitted from consideration in Taylor's original work (see Ref. 5). bination (minimum M) for a number of axial orientations distributed throughout the standard stereographic triangle. Later work by Bishop and Hill*'8 showed that Taylor's least-shear hypothesis was equivalent to a maximum work principle which they advanced. Using the simplified Bishop and Hill method for {111)(110) slip, Hosford and Backofen' obtained detailed contours of constant minimum M for the same axisymmetric flow case. In contrast to {111}(110) slip in fcc metals, slip in bcc metals is generally described as occurring on {ll~)(lll), {112)(111), {123) (111) systems as well as mixed slip composed of all three. Since the direction cosines of the slip plane normal and the slip direction enter as a product in the Taylor analysis, the Taylor solutions of ,M for {110)(111) slip are identical to those for { 111} 110) slip. The other three cases of slip, however, have not been solved. In view of the numerous combinations of slip systems involved in the calculations, the Taylor analysis is clearly oriented toward computerized solutions. THE TAYLOR ANALYSIS In order to obtain the active combination of (five) slip systems by solving for the minimum value of M = we first express the (small) strain components E,, with respect to the cubic axes 1, 2, 3 ([loo], [010], [001], respectively) of the crystal, in terms of the sum of the glide shears yj from slip systems j: where n, and n,j refer to direction cosines of the slip plane normal, and dri and dsi to direction cosines of the slip direction, of slip system j, all referred to the cubic axes. In practice, the strain components are given with respect to the specimen axes X, y, 2. These components are readily converted to ers through the tensor transformation where irk and 1,~ are the direction cosines between the two sets of coordinate axes.

Jan 1, 1968

By W. G. Oldham

By monitoring the capacitance of abrupt p-n junctions it is possible to follow the motion of substitu-tional impurities. A p-n junction is formed by growth of silicon from an Al-Si alloy on an n-type silicon sutstrate at a temperature in the range 650" to 750°C. The diodes are etched and sorted for consistent V-I and capacitance behavior and separated into groups. After irradiation, each set with an unirradiated control set is annealed to various temperatltres for 10 mm and the capacitance remeasnred. For very heavily doped diodes (-1019 per cm3) observable capacitance changes occur at neutron fluences of >1015 per cm 3. The results may be interpreted in seceral ways, the simplest of which is to assume simple vacancy diffiision with small impurity -racancy interaction (at the diffiision, i.e. annealing temperature of 700°C). In this interpretation it is found that a typical vacancy makes about 1024 jumps and travels about 10-5 cm before disappearing. The required effective annihilation center density is about 1016per cm3 . Estimates of the vacancy-impurity interaction can be made and the above numbers correctecl, but for arty reasonable assumptions the number of vacancy sinks connot be much reduced. ThE complete annealing of radiation induced defects requires that the vacancies and interstitials either recombine, travel to the surface of the crystal, or travel to an annihilation center, e.g., a dislocation or a precipitate. If the interstitial is ignored except as a possible vacancy annihilation center at low temperatures,* the motion of vacancies may be followed by monitoring the corresponding motion of substitutional impurities. pfister2 has measured the enhanced diffusion of impurities in an asymmetric shallow diffused silicon structure by optically monitoring the junction movement. In these experiments we monitor instead the capacitance of a heavily-doped deep symmetric p-n junction. The sensitivity for this method is several orders of magnitude higher than in Pfister's technique, mainly for two reasons: 1) the junction capacitance of a heavily-doped junction is sensitive to impurity movements in the Angstrom range* com- and 2) the junction may be far from the surface which is a major annihilation center for vacancies. THE EXPERIMENT A p-n junction is formed by the epitaxial growth of silicon from an A1-Si alloy on a silicon substrate at a temperature in the range 650° to 750°C. The technique used is the transport of an aluminum melt through a temperature gradient.4 A 10-mil thick aluminum disc is sandwiched between two silicon wafers and the assembly raised to about 650° C with a temperature gradient normal to the sandwich. After about 8 hr the upper (hotter) wafer has been entirely transported and deposited epitaxially on the substrate wafer. The substrate and overgrowth resistivity are measured with a 4-point probe. The as-grown structure is lapped until the wafer is about 1/2 mm thick with the junction in the center. Contacts consisting of electroless nickel covered by electroplated rhodium are applied to both the p and n sides. The wafer is diced into square dice 1/2 to 1 mm on a side and the dice are etched sufficiently to remove approximately 1 mil of silicon. The following results are all for aluminum (p-side) and antimony (n-side) doped specimens with NA =3x 1018 per cm3, ND = 2-8 x 101A per cm3. The diodes are sorted for consistent V-I and capacitance behavior and separated into groups. After irradiation, each set with an unirradiated control set is annealed and the capacitance remeasured. A special capacitance measurement method is used to insure a low sensitivity to shunt resistance. The diode is voltage driven and the current monitored by a phase lock amplifier. It is possible to adjust the detector phase to a point where shunt resistances as low as 100 O have no effect on the reading. The diodes in this study have a capacitance in the range 1000 to 5000 picofarads and a shunt resistance in the range 100 to l06 O depending on the stage of the anneal. THEORY The theoretical problem is twofold: 1) The computation of the amount of impurity diffusion and hence the impurity profile resulting from a given amount of vacancy motion, and 2) the computation of the capacitance from the impurity profile. A comparison of the theoretical and experimental capacitance (in particular the changes) yields the amount of vacancy motion. Vacancy Motion. A convenient parameter to measure the total amount of vacancy motion is Jv the total number of vacancy jumps per unit volume. Although this parameter varies with position in the crystal, owing to vacancy annihilation at the surfaces, it is approximately independent of position far from the surfaces, i.e. in the junction region. In terms of the number of vacancies per unit volume Nv and the vacancy diffusivity given by

Jan 1, 1970

By Robert L. Clayton, Arthur Baker

Two massive sulfide zinc-copper ore bodies are in quartz-sericite schist (probably formed by regional metamorphism of sediments) and andesite of the Precambrian Yavapai Series, on opposite sides of a large rhyolite mass. The Copper Queen ore body is conformable with bedding of its schist host rock, but the Old Dick ore body probably crosscuts the strata. A lens of low-grade mineralization in chlorite schist, associated with the Old Dick ore body, crosscuts through 150 feet of strata. The ore bodies are almost entirely enclosed by premineral faults with less than 150 feet of displacement. The minerals of the ores are pyrite, sphalerite, and chalcopyrite, with minor arsenopyrite and galena and small amounts of intimately associated chlorite, sericite, and calcite. Old Dick sphalerite-chalcopyrite intergrowths have mutual boundaries, and sphalerite grains contain abundant exsolved chalcopyrite. Copper Queen sphalerite-chalcopyrite intergrowths have extremely ragged boundaries, the sphalerite contains no exsolved chalcopyrite, and the ore overall has a schistose texture. The pre-mineral fault on the hanging wall of the Copper Queen ore body has had 100 feet of post-mineral displacement. Wall rocks of the Old Dick ore body locally have been sericitized. Andesite and quartz-sericite schists for at least several hundred feet around both ore bodies have been chloritized erratically and contain traces of copper.

Jan 1, 1968

By H. Sigurdson, C. H. Moore

Extensive studies have been carried out on electric furnace and blast furnace slags obtained in the winning of iron from its ores. These slags normally consist of elements of the gangue minerals present in the ores, as well as the added flux materials. In consequence, melts of CaO, MgO, Al2O3 and SiO2 can be considered as representing typical slag compositions. When a slag of this composition cools, it usually crystallizes according to predictions possible from an equilibrium diagram of these constituents, providing the melt is not undercooled to form glass. The melt is either viscous or fluid, depending upon the ratio of binary cations to silica, and crystallizes easily or forms a glass for the same reasons. If the melt is not overheated so that carbides of the metal components of the slag are formed and if the composition of the slag is so adjusted that it has a high fluidity, liquid equilibrium is attained and the slag can be held in a liquid state for extended periods of time. Upon tapping, the slag crystallizes into minerals, the type and proportion of which are determined by the melt composition. Since equilibrium is attained, the holding period is not critical. In melts containing a large increment of titanium, however, the normal slag procedures are not applicable. Titanium, as one of the atomic transition elements, is, at elevated temperatures, capable of being reduced to form metalloid compounds much more readily than the refractory oxides present in normal slags. In consequence, an oxide melt containing titanium never reaches equilibrium in a reducing environment, but continues to shift its composition until cooled. If melts of this nature are cooled and samples submitted to metal-lographic and X ray analysis the course of reaction and crystallization in this type of slag can be determined. Preparation of Slag The slags investigated fell into the system CaO-MgO-TiO2-Al2O3-SiO2 and were produced from ilmenite ores reduced by carbon in an electric furnace. Since the equilibrium series1 and the laboratory smelting of ilmenite2 are described in two of the accompanying papers, detailed description of the smelting procedure is not required here. However, certain essentials must be mentioned. Two types of melts were used to produce slags studied in this investigation. The first series of smelts made to determine proper flux addition were produced in a 4 lb Ajax induction furnace. The charge, consisting of ore with the proper flux addition, was heated in a graphite crucible until fluid, held fluid for a sufficient time period to obtain 1-5 pct FeO content, and poured. Because of the small size of the charge only the final sample of these melts could be examined. In the melts made in the 50 lb arc furnace, however, grab samples taken at 10 min. intervals between time of initial melting and final pouring were available for examination. These samples allowed a much clearer picture of the course of reaction and crystallization. amounts of ferrous oxide and reduced titanium compounds is opaque to transmitted light. Therefore, all petro-graphic studies had to be made on polished slag sections. A representative sample of slag was cut or broken, mounted in a thermosetting plastic, ground flat using 400 grit silicon carbide, the coarse scratches removed with 600 grit silicon carbide and polished on billiard cloth using levigated alumina. Rouge was avoided because of the entrainment of the red particles in pores in the slag, causing a possible confusion with some of the mineral phases. In order to prevent sample projection above the plastic surface red bakelite was used to hold the sample, and backed up with clear lucite. In this manner sample labels could be permanently retained in the mounting. The polished samples were examined on a Bausch and Lomb metallograph at magnifications of 250 X, 500 X, 1000 X and 1800 X. The instrument was equipped for examination of specimens under bright field illumination and with crossed nicols. A magenta tint plate to aid in color tone differentiation was also used. Petrology of Slags In order to determine the composition and mineral relatinos of a previously unreported system petrologically, it is essential that the starting composition, reaction temperature and final composition be known. The chemical composition of the ilmenite ore used in these smelts is given in Table 1, and the complete analysis of a typical high titanium, low iron slag is given in Table 2. In the winning of TiO2 from ilmenite by a smelting process it is necessary to produce a slag which will melt at an economically feasible temperature, remain molten as the iron is removed by reduction, be fluid enough to be readily removed from the furnace, contain a high percentage of TiO2 and a low percentage of reduced titanium com-

Jan 1, 1950

FOREWORD5 INTRODUCTION 7 ACKNOWLEDGMENTS II BERGBÜCHLEIN TRANSLATION OF THE TEXT 17 HISTORY AND BIBLIOGRAPHY OF THE Berghüchlein 49 NOTES ON TRANSLATION AND ACKNOWLEDGMENTS 63 THREE ILLUSTRATIONS FROM THE EARLIER UNDATED EDITION 65 [ ]

Jan 1, 1949