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By George B. Clark

7.1-1. Introduction. The fundamentals of blasting involve both the properties of explosives and of the rock being blasted. While the knowledge of property correlation between rocks and explosives for most effective blasting is far more complete, many quantitative evaluations have been made. Four of the most important explosive properties appear to be energy density, bulk density, rate of energy release, and the pressure-time history of the gases produced. Important rock properties are density and porosity strength, and energy absorption properties, including the effective moduli of elasticity. Rock structure also has a marked effect on its breaking properties, i.e., joints, bedding, fractures, alteration, etc. Several mechanisms enter into rock fragmentation by blasting. These include slabbing, radial fracturing, crushing, and bursting by the gas bubble. All of these factors are closely related to properties of both explosives and rock. Slabbing depends upon the character of the first generated stress wave, whose shape and magnitude are a result of the pressure generated by the explosive, its time history, and the resultant response of the rock, including its ability to sustain the stress wave. Actual slabbing, in turn, is a function of the magnitude and shape of the pressure pulse and the tensile strength of rock. Further fragmentation depends to a great extent upon the amount of gas in the bubble and its energy and pressure. Blasting rounds are best designed by taking the above factors into consideration. This is effectively accomplished by use of cratering curves which relate breakage- parameters to the explosive energy. Optimum depths from single charge cratering curves must be adjusted to changes in shot geometry and related to multiple hole blasting. Blasting damage may occur from either air blast or ground waves, and in the latter ease may be due to direct vibration or to settlement caused by vibration. Technical information indicates that blasting damage is often

Jan 1, 1968

By R. W. Gurry

In the course of a series of measurements of the rate of diffusion of carbon in austenite at about 960°C. (1760°F.) and III0°C. (2030°F.), it became necessary to determine carbon concentration when austenite is saturated with graphite, because of indications that the hitherto accepted value of the solubility of graphite in this temperature range is too low. Specimens of carbonyl iron were saturated at temperature in a hydrogen-toluene atmosphere which was in equilibrium with graphite. The carbon conteDt of the steel was measured either by combustion or by the loss of weight after substantially complete decarburization in an atmosphere of hydrogen saturated at room temperature with water vapor. The absence of carbide or graphite as a phase at temperature was demonstrated by microscopic examination of saturated specimens that had been drastically quenched, The mean result of concordant ments-—taeats-is-^that gamma iron saturated with respect to graphite contains 1.39 per cent carbon at 957°C .(i755°F.) and 1.89 per cent at III0°C. (2030°F.). These two values, plotted along with what appears from the literature to be the best value (0.69 per cent) at the iron-graphite eutec-toid temperature (738°C. or I360°F.), yield a curve that is almost linear, and which, continued upward through a short interval, leads to a limiting solubility of 1.98 per cent at the iron-graphite eutectic temperature II35°C. (2075°F.) instead of the commonly accepted value of about 1.7 per cent. Experimental Procedure The samples of carbonyl iron, with the exception of those for microscopic examination, were cylinders 3.8 cm. long, 0.475 cm. in diameter. They were placed in a graphite holder and suspended in a vertical furnace, the temperature of which was controlled precisely by means of the resistance of the platinum winding.' In the empty furnace the range of temperature over a distance of 4 cm. at the heat center was 9°C. (I6°F.) but at a given location the temperature remained within +o.5°C. (o.9°F.); it was measured by inserting a platinum-rhodium couple calibrated at the melting point of palladium, 1555°C. Since the presence of the sample probably improved the uniformity of temperature, it was decided to consider the average temperature of the sample to be 3°C. lower than the maximum measured in the empty furnace with the same setting of the controller. Data were obtained in the vicinity of two temperatures, 960°C. (I760°F.) and III0°C. (2030°F.). The samples for microscopic examination, 2.2 cm. long, 0.475 cm. in diameter, were suspended individually on pure iron wire; for these no temperature correction was applied. The carburizing gas passed into the furnace was dry, oxygen-free hydrogen saturated at room temperature with toluene; this quickly produced on the

Jan 1, 1942

By R. W. Gurry

In the course of a series of measurements of the rate of diffusion of carbon in austenite at about 960°C. (1760°F.) and III0°C. (2030°F.), it became necessary to determine carbon concentration when austenite is saturated with graphite, because of indications that the hitherto accepted value of the solubility of graphite in this temperature range is too low. Specimens of carbonyl iron were saturated at temperature in a hydrogen-toluene atmosphere which was in equilibrium with graphite. The carbon conteDt of the steel was measured either by combustion or by the loss of weight after substantially complete decarburization in an atmosphere of hydrogen saturated at room temperature with water vapor. The absence of carbide or graphite as a phase at temperature was demonstrated by microscopic examination of saturated specimens that had been drastically quenched, The mean result of concordant ments-—taeats-is-^that gamma iron saturated with respect to graphite contains 1.39 per cent carbon at 957°C .(i755°F.) and 1.89 per cent at III0°C. (2030°F.). These two values, plotted along with what appears from the literature to be the best value (0.69 per cent) at the iron-graphite eutec-toid temperature (738°C. or I360°F.), yield a curve that is almost linear, and which, continued upward through a short interval, leads to a limiting solubility of 1.98 per cent at the iron-graphite eutectic temperature II35°C. (2075°F.) instead of the commonly accepted value of about 1.7 per cent. Experimental Procedure The samples of carbonyl iron, with the exception of those for microscopic examination, were cylinders 3.8 cm. long, 0.475 cm. in diameter. They were placed in a graphite holder and suspended in a vertical furnace, the temperature of which was controlled precisely by means of the resistance of the platinum winding.' In the empty furnace the range of temperature over a distance of 4 cm. at the heat center was 9°C. (I6°F.) but at a given location the temperature remained within +o.5°C. (o.9°F.); it was measured by inserting a platinum-rhodium couple calibrated at the melting point of palladium, 1555°C. Since the presence of the sample probably improved the uniformity of temperature, it was decided to consider the average temperature of the sample to be 3°C. lower than the maximum measured in the empty furnace with the same setting of the controller. Data were obtained in the vicinity of two temperatures, 960°C. (I760°F.) and III0°C. (2030°F.). The samples for microscopic examination, 2.2 cm. long, 0.475 cm. in diameter, were suspended individually on pure iron wire; for these no temperature correction was applied. The carburizing gas passed into the furnace was dry, oxygen-free hydrogen saturated at room temperature with toluene; this quickly produced on the

Jan 1, 1942

By K. D. Jacob, W. L. Hill

Fluorine recovery in the United States has been restricted chiefly to manufacture of ordinary superphosphate and wet-process phosphoric acid. However, there is an expanding use of fluorine by industry in the form of hydrofluoric acid. Improved methods for recovering fluorine from phosphate rock would yield an adequate supply of fluosilicates and a substantial contribution to the hydrofluoric acid requirement. THE bulk of natural phosphates is comprised of calcium phosphates, which are usually apatites;' calcium aluminum phosphates such as pseudowavel-1ite; and aluminum phosphates, which occur in extensive deposits, notably on Grand Connetable Island." Nearly all deposits of current commercial value are apatite, often with admixed material of other classes. In the trade coarsely crystalline material, mainly fluorapatite of igneous origin, moves as apatite, whereas the fine-grained material of sedimentary origin is marketed as phosphate rock. The latter classification includes the phosphate shales in western North America. Although several genetic varieties of phosphate rock are recognized, most known reserves are of marine origin. Calcium phosphate is concentrated from Florida land pebble and Florida hard rock deposits and from Tennessee brown rock deposits. Phosphate Rock as a Fluorine Carrier: More than two decades ago Reynolds and Jacob surveyed the fluorine content of commercial phosphate rock from various parts of the world. Later these samples were re-analyzed by a new and more reliable method of determining flourine. The revised results with interim additions of new samples, published a few years ago in a brief summary," are shown in Figs. 1-3. Through the points representing the respective varieties of rock medial straight lines are drawn. In some instances the lines are well defined by the points; in others, where scattering renders the position of the best line uncertain, the greater weight is given points near the end of the covered range. Wherever distinct varieties are not recognized among regional deposits the custom is to identify the sample with the geographical location of the deposit. Although all rock varieties cannot be classified with certainty, the plotted results exhibit three distinct types of rock in which the F to P2O5 ratio diminishes, remains sensibly constant, and increases, respectively, as the grade of rock increases. Existence of two types of Florida land pebble, Fig. 1, is supported by additional results recently supplied by a producer." Generally speaking, phosphate rock from continental deposits carries considerably more fluorine, and apatite and insular phosphates less, in proportion to the phosphorus content than is required by the formula for fluorapatite. Exceptions to this are apatite from Canada and certain samples of Florida waste-pond phosphate. The manner in which excess fluorine is held and the nature of the carbonate in carbonate apatite are discussed in recent articles. High-grade calcium phosphates with F to P2O5 ratios less than 0.05 have been found in Curacao, Christmas Island," Mexic,13 and elsewhere. The calcium aluminum phosphates and aluminum phosphates aften carry notable amounts of fluorine. The F to P2O, ratio for one sample of pseudowavel-lite concentrate was 0.05." Aluminum phosphate from Grand Connetable Island is very low in fluorine, whereas some aluminum phosphate minerals" carry as much fluorine as highly fluorinated phosphate rock. Fluorine in Domestic Phosphate: The curves shown in the figures permit interpolation of the F to P2O5 ratio corresponding to the midpoint of selected ranges in grade of any one of the several varieties of phosphate. Multiplication of the interpolated ratio by the mid-range grade (P2O5) yields a figure for the percentage of fluorine in this grade. Then, with the use of the mid-range grade, the amount of fluorine held in phosphate reserves can be estimated, see Table I. Accordingly, on Jan. 1, 1950, the fluorine complement of known domestic reserves exceeded 420,000,000 long tons of the element. A previous figure," deduced in 1940 by a simpler procedure

Jan 1, 1955

By G. G. Gunther, C. L. Boeke

DISCUSSION I. M. Symonds, (Cia. Minera de Penoles, Monterrey, N. L., Mexico)—Messrs. Boeke and Gunther have written most interesting papers describing their zinc de-leading operations. Mr. Gunther was kind enough to show me his operation last fall. Aside from the excellent results, I was most impressed by the ease of control. I had expected a difficult operation requiring careful control and supervision, but found one requiring little attention. The only disappointing fact of the separation is the poor copper recovery in the concentrate of the delead-ing float. The final zinc concentrate still has about 3 pct chalcopyrite, assuming the copper is chalcopyrite, and adversely affects the zinc grade. If the copper mineral is free, the poor recovery is probably due to the high cyanide concentration. Fortunately, about 75 pct of the copper is recovered before the pulp goes to the zinc circuit. Mr. Gunther's remarks about proper cyanide to zinc sulphate ratios cannot be overemphasized. Although our experience has been confined mostly to the conventional lead-zinc separation, we have found these ratios most important, and more important in the mill than in the laboratory. The laboratory appears to give optimum results over a wider range of reagent control than the mill, especially in regard to the effect of cyanide. In handling relatively high grade ores in the mill we usually find that ratios of cyanide to zinc sulphate of 1 to 10 or 20 or higher work best. Where there is a substantial amount of chalcopyrite present it has been noted that cyanide in the range of 0.02 to 0.10 lb per ton of ore is often beneficial in zinc rejection and possibly in copper recovery in the lead concentrate, while larger amounts, say 0.20 to 0.25 lb per ton, will float more zinc and cause a serious rejection of chalcopyrite. On an ore with 15 to 20 pct zinc content we have had to use 0.8 to 1.2 pounds of zinc sulphate per ton of ore with the above cyanide to obtain optimum results. Some time ago we made a laboratory study following Parral and Santa Barbara practice on an ore which had never a very satisfactory rejection of zinc in the lead concentrate. The results were not encouraging and a mill test was not run. Since then the study has been reopened using in the laboratory fresh zinc concentrate from the mill instead of one made in the laboratory. A reasonably clean lead float from the zinc concentrate was obtained. It has been checked several times and each time the zinc concentrate made in the mill responds and the one made in the labora-

Jan 1, 1953

By G. G. Gunther, C. L. Boeke

DISCUSSION I. M. Symonds, (Cia. Minera de Penoles, Monterrey, N. L., Mexico)—Messrs. Boeke and Gunther have written most interesting papers describing their zinc de-leading operations. Mr. Gunther was kind enough to show me his operation last fall. Aside from the excellent results, I was most impressed by the ease of control. I had expected a difficult operation requiring careful control and supervision, but found one requiring little attention. The only disappointing fact of the separation is the poor copper recovery in the concentrate of the delead-ing float. The final zinc concentrate still has about 3 pct chalcopyrite, assuming the copper is chalcopyrite, and adversely affects the zinc grade. If the copper mineral is free, the poor recovery is probably due to the high cyanide concentration. Fortunately, about 75 pct of the copper is recovered before the pulp goes to the zinc circuit. Mr. Gunther's remarks about proper cyanide to zinc sulphate ratios cannot be overemphasized. Although our experience has been confined mostly to the conventional lead-zinc separation, we have found these ratios most important, and more important in the mill than in the laboratory. The laboratory appears to give optimum results over a wider range of reagent control than the mill, especially in regard to the effect of cyanide. In handling relatively high grade ores in the mill we usually find that ratios of cyanide to zinc sulphate of 1 to 10 or 20 or higher work best. Where there is a substantial amount of chalcopyrite present it has been noted that cyanide in the range of 0.02 to 0.10 lb per ton of ore is often beneficial in zinc rejection and possibly in copper recovery in the lead concentrate, while larger amounts, say 0.20 to 0.25 lb per ton, will float more zinc and cause a serious rejection of chalcopyrite. On an ore with 15 to 20 pct zinc content we have had to use 0.8 to 1.2 pounds of zinc sulphate per ton of ore with the above cyanide to obtain optimum results. Some time ago we made a laboratory study following Parral and Santa Barbara practice on an ore which had never a very satisfactory rejection of zinc in the lead concentrate. The results were not encouraging and a mill test was not run. Since then the study has been reopened using in the laboratory fresh zinc concentrate from the mill instead of one made in the laboratory. A reasonably clean lead float from the zinc concentrate was obtained. It has been checked several times and each time the zinc concentrate made in the mill responds and the one made in the labora-

Jan 1, 1953

By I. D. Shah

A roasting procedure for synthetic copper sulfide which results in a reproducible transient melting at 450° and 470°C is described in this paper. Possible causes for this melting phenomenon are suggested, and also a procedure to avoid it during the roasting. This melting is believed to be responsible for the occasional occurrence of stickiness in the commercial roasting of copper sulfide concentrate. Many workers have studied the roasting of copper sulfides, but only Lewis et al. have reported that fusion and, in some cases, fusion with "boiling" occurred in the neighborhood of 450°C. The DTA and TGA apparatus, the materials used in this investigation, and the discussion of chemical reactions occurring during the CuS roasting are described in an earlier publication. CuS, in the form of either pellet or powder, was heated at 280° to 330°C in a flowing air or 30% 02: 70% N2 atmosphere. Heating was continued at this temperature until no further weight increase due to sulfates formation was observed on the TGA thermogram. This is believed to be due to the inability of SO, to diffuse out from the sulfate layer on the surface of the pellet, thus halting the sulfate-forming reactions. Hereafter, the sample oxidized in this manner will be referred to as "partially oxidized CuS." X-ray analysis and microscopic examination of a polished cross section of a partially oxidized CuS pellet showed the following order of layers starting from the center of the pellet: Cu2S, Cu2O, CuO • CUSO4, and CuSO4. A bare thermocouple inserted in the center of a partially oxidized CuS pellet (2.5 g) did not indicate any noticeable change in the temperature of the pellet when melted at 450° to 470°C in an inert or oxidizing atmosphere. During the preparation of a partially oxidized pellet, the temperature of a CuS pellet increased by 50°C due to the exothermic formation of sulfates in air at 320°C. The endothermic peak associated with the melting phenomenon at 450°C is shown in [Fig. 1.] A CuS pellet (0.2 g) was oxidized in flowing air (150 cc per min) at 10°C per min up to 320°C and held there for about 2 hr. Then, N2 replaced air and heating was continued up to 500°C. The exothermic peak at 320°C represents an overall formation of sulfates, and an endothermic peak at 450° to 470°C represents the melting phenomenon. To observe the melting visually, a small (50 mg), partially oxidized CuS pellet was heated (in static air) in a hot-stage microscope. The melting phenomenon was observed on an auxiliary TV screen. The sample

Jan 1, 1976

By Carl Wagner

J. Pearson (British Iron and Steel Research Association, London, England)—Dr. Wagner has referred to the work of Richardson and Dancy and Gellner and Richardson on the reduction at 900 °C of wiistite films on iron. He has assumed that iron ions and electrons migrate backwards to the iron-wustite interface and that the reduced iron grows on the metal substrate. This would be a possible explanation of the results of these workers were it not for the fact that, as stated by Gellner and Richardson but not stressed, this growth in the center of the specimen can occur even

Jan 1, 1953

By Gerhard Derge

THE extension of metallurgical control of steelmaking processes has always made it desirable to have some quick method for determining the oxygen content of molten steel. To meet the practical demands of the steel industry, this method must also be simple enough so that the sampling can be done by the regular furnace crew. This requirement was kept in mind continually in the work to be described. An oxygen value is required for proper control, whether it be of a rimming steel or of a fully killed steel. However, two factors have discouraged the development of such direct methods: I. The reaction C + FeO -+ Fe + CO is rapid enough to make the correct sampling of the bath a difficult problem. The most generally accepted means of circumventing this difficulty have been the aluminum-killed bomb test of McCutcheon and Rautio1 and the aluminum-killed spoon test of Herty.2 The theory of these tests is that all of the oxygen in the iron is converted to A1203, which can then be determined by chemical methods. Even when simplified so that the analysis is made by a measurement of turbidity, this method is too slow to be used in routine control. Furthermore, the results obtained have never been entirely satisfactory, and some of the reasons for this will be discussed later in this paper. 2. The ordinary chemical methods of analysis for oxygen in steel are not reliable. The only analysis that seems to possess sufficient dependability to be of value is vacuum fusion,3 and the apparatus and technique developed for this have been too complex and slow for routine work. INDIRECT METHODS Indirect methods of estimating the oxygen have been resorted to in mill practice. Generally these depend upon the chemical equilibria involved. The oxygen in the bath is related to other components in the slag or metal that can be analyzed more readily. These methods have many difficulties in common. Steelmaking processes involve a complicated set of interrelated reactions, all of which tend to approach equilibrium at varying rates. The degree to which any particular equilibrium is approached, is not , well established. Moreover, a proper use of theoretical equilibrium constants requires a more extensive knowledge of the activities of the reactants than we now have. This is well illustrated by the irregularities observed when trying to determine the oxygen in the metal by its ratio to the iron oxide in the slag. Equilibrium relations may be used more readily if they are evaluated by plant experience, but the extent of approach to equilibrium remains an undetermined variable and lack of an entirely satisfactory means of determining oxygen for the calibration is felt keenly. For example, the statistical analysis of the relation between carbon and oxygen4 5 illustrates that even in a single plant wide variations exist under normal conditions of operation. Nevertheless, this is one of the best methods now

Jan 1, 1943

By John E. O’Rourke, Kevin M. O’Connor, Pamela H. Rey

INTRODUCTION The resurgence of coal mining activity in the United States, brought on by the spiraling costs of fossil fw1 energy in the Seventies, has come at a time of intense public concern for the quality of the environment. Notwithstanding pressure on our economy to develop alternate sources of fue1 energy to the import of oil, the legislatures of several states have reacted to public concern over the environment by passing strict regulations aimed at con- trolling the subsidence effect s of underground mining. Agencies of the federal government charged with assistance to the mining industry, including the Department of Energy and the Bureau of Mines, have sponsored a number of instrumentation and field measurement projects aimed at the development of subsidence prediction models that can aid the mine operator's task of subsidence control. There are good empirical models developed in Europe for subsidence prediction, but they were made possible by a large body of mining-induced subsidence data collected there over a long period of time. No com- parable subsidence data base exists in the United States, and consequently empirical modeling of subsidence is not a realistic approach for our near term needs. Moreover, the geologic and topographic diversity of the several coal regions in the United States is expected to necessitate the development of several empirical models, each one expected to be relevant to its own region. Because of the time and costs that are likely to be involved in an empirical modeling approach, it is considered more expedient and cost effective to develop a general, mechanistic model for subsidence prediction purposes. In order to develop such a model, it is necessary to investigate and quantify the mechanics of the subsidence process from the mine level up to the ground surface. The series of projects discussed in this paper are designed to achieve this objective and include the following work: (1) the identification of geotechnical instrumentation that will pro- vide mine level overburden and surface subsidence data. (2) a field demonstration of selected instruments, and (3) documentation of case histories for complete subsidence mechanics, using the demonstrated and preferred instruments. An identification of feasible instrumentation and monitoring techniques was completed by Woodward-Clyde Consultants (WCC) in 1977 (O'Rourke and others). This paper discusses a demonstration of those instruments at a mine in Utah, and at two subsequent projects, currently underway at longwall mines in Colorado and West Virginia. 'he latter two projects when complete will provide documented case histories of subsidence mechanics. The process of optimizing subsidence instrumentation and monitoring techniques to the conditions encountered during installation and monitoring for these underground mines is shown to be an evolving one, and one which has had some notable successes to date. INITIAL DEMONSTRATION The initial design and demonstration of selected monitoring systems was carried out at the SUFCO No. 1 mine, near Salina, Utah. The instrumented panel was approximately 152 m wide. 640 m long. and was 290 m to 320 m deep. The mined height of coal. seam averaged 2.4 m. The mining method was room and pillar using continuous mining machines. This method allowed some monitoring of the supported condition during development, and eventually allowed monitoring of a caved system when both chain pillars and room pillars were extracted on retreat. The two instrument systems shown on Table 1 were selected from the earlier feasibility report for demonstration at SUFCO No. 1. Collectively, the two systems, one for a fully-supported mining method and the other for a fully-caved method, incorporate most of the instrumentation to be found within all five systems listed in the earlier feasibility report. The instrumentation includes surface, subsurface and mine monitoring installations. All of the SUFCO instruments selected to meet the specifications of the general instrument types listed on Table 1 were manually operated. That is, data from the installed system could only be obtained while a person was there to physically observe or operate the system readout. Automatic data recording equipment was available for some installations, but the objectives were to keep the systems as simple as possible for the demonstration project. A complete description of the surface, sub- surface and mine level instruments, and the demonstration project results are given in WCC (1982), and selected features are discussed in this paper.

Jan 1, 1982

By Wilson T. Lundy

The history of the production of sulfur from salt domes in Louisiana and Texas originated with the operations of the Union Sulphur CO. at Sulphur, La., followed by the Freeport Sulphur Co. at Bryanmound, Tex. Including the present development of Grande Ecaille by the Free-port Sulphur Co., which constitutes the tenth dome to be equipped for the production of sulfur in the Gulf Coast, less than 10 per cent of all the known domes have proved to contain sulfur in commercial quantities. The Grande Ecaille salt dome is in the tidal marsh of the Mississippi River delta in Plaquemines Parish, Louisiana. It is 10 miles southwest of the right descending bank of the river approximately 45 miles below the city of New Orleans and is within 4 miles of the shore line of the Gulf of Mexico. Terrain Characteristic of the delta region, the terrain consists of a low, flat, uninhabited area of marsh land intersected by many shallow lakes and bayous. With the exception of salt grasses, the region is devoid of vegetation and presents, in all directions, an unobstructed path to the vagaries of the winds. The general character of this area can be best visualized from the mechanism of its formation.' Offshore bars formed enclosing long narrow lagoons between the bar and the inner shore line, the lagoons communicating with the sea by means of tidal inlets. The water in the lagoons, being comparatively quiet, favored the deposition of fine debris composed of sand carried into the lagoons by action of the waves, tides and river-borne sediments from the land surface. As this material accumulated the bottoms of the lagoons were built up and eventually salt grasses obtained a foothold. The successions of growth and decay of these grasses formed a brown fibrous mat varying in depth from a few inches to several feet. This mat of vegetation virtually floats on an ooze that is several feet thick and is composed of alluvial sediments and very fine sand, and the whole is underlain by an unctuous clay. The decayed vegetation from the upper layer when dried has a peaty appearance.

Jan 1, 1934

By L. C. Graton

Although marked by numerous well-known attributes of its own, gold does not possess a kind and range of physical, chemical and geological characteristics wholly different and apart from those of other metals. Instead, it is merely one of the family of metals, with its individual and distinctive traits subordinate to the underlying family relationships and resemblances. The geologist concerned with pure science will pursue, therefore, the same general course and will examine the same broad kinds of facts and interrelations when studying the occurrence of gold as when studying that of copper or cadmium, or any other metal. But when we come to consider the use and economics of the metals, we discover that gold differs strikingly from all the others. Gold, in short, is unique, not by virtue of its inherent characteristics, but because of a peculiar and concerted psychological regard in which it is held. It will be evident, therefore, that the geologist who would deal with gold supply must give far greater weight to economic considerations than is required in his contacts with any other metal. If the geologist be called the scientist of occurrence, and the economist the scientist of use, the economic geologist stands as the necessary link between them. Perhaps it is in part because the economic geologist has made himself more familiar with the science of occurrence than with the science of use and has thus in some degree failed to bridge effectively the gap between the two fields, especially with regard to gold, that the usen1 of gold now appear to be in a state of general concern and even of alarm for the security and adequacy of future supplies. In the case of no other mineral commodity do the users, as a rule, trouble themselves greatly about the adequacy of supply except in so far as that may affect the price which they shall have to pay for the commodity. Oversupply, with resulting low price, they regard as a gift of good fortune. As to long-term undersupply, they are generally content to go ahead on faith, leaving the producer to discover as best he may the means for meeting their requirements or the inventor to find a substitute. But history has shown that for gold a different situation exists. While

Jan 1, 1931

By J. N. Butler, R. J. Morris

A series of organic collectors has been developed which successfully float synthetic secondary uranium minerals, such as autunite, carnotite, and torbernite. Recoveries up to 97 pct have been obtained. With cleaning of rougher concentrates, ratios of concentration as high as 15:1 are possible on head assays of 0.10 to 0.50 pct U 3 O 8. Additions of certain base metal salts aid in recovery and materially increase the rate of flotation and selectivity of the collectors for the synthetic minerals. Flotation tests on natural uranium minerals have not yet equaled results obtained on the synthetics, although these collectors do give better results than conventional collectors for nonsulfide minerals. RAPID increase in mining and milling uranium ores during the past seven years and the discovery of large tonnages of uranium-bearing material too low in grade to stand the cost of leaching have developed considerable interest in possible methods for beneficiating these marginal ores. Such ores are generally classed as those containing less than 0.10 pct U3O8. Development of a beneficiation method that would give both high recovery and high ratio of concentration would also make possible the beneficiation of higher grade ores and would provide higher grades of feed to existing leaching plants. Although considerable research and testing on physical or physico-chemical beneficiation of domestic uranium ores has been done in the past, to the best knowledge of the authors only a single application of physical beneficiation is now in operation on a commercial scale. Flotation has been attempted on the basis of mineral association rather than by direct concentration of the contained uranium minerals. Flotation studies conducted on this project on certain ores gave recoveries of 60 to 70 pct of the uranium by the use of conventional flotation agents such as oleic acid, but ratios of concentration were in the order of 1.5:1 to 2.5:1. Subsequent cleaning to upgrade the concentrates rapidly increased losses in the cleaner tailings, which were not later refloated in the rougher flotation. Selection of Collector: In selecting desirable organic collectors for these oxide systems, a thorough study was made of the relationship between structural characteristics and collector activity by an examination of the behavior of a number of different functional arrangements present in a variety of organic molecules, (see Fig. 1). It is generally accepted that a collector must have a relatively long-chain hydrocarbon radical and a chemically reactive elec-trophilic center. Such a requirement could be met by a large number of compounds, but steric effects at the uranium mineral surface, solubility, compat-ability with aqueous systems, air avidity, bond strength at the mineral surface, interfacial concentration of the collector, and diffusion rate of the formed complex from the air-water interface eliminated many as unsuitable for this purpose. Preliminary investigations were completed of possible collector designs consisting of aliphatic and aromatic hydrocarbon radicals attached to stable combinations of nitrogen, oxygen, sulfur, and halogen electrophilic centers, Fig. 1.Tests were made to determine melting point spans, solubility of mineral-collector combinations in various solvents, reactions with soluble uranium salts, contact angles, and floatability by semi-quantitative beaker methods.' Contact angle determinations were not too useful because of the fine particle sizes of available mineral samples. From the foregoing study it appeared that nitrogen-sulfur electrophilic centers coupled with straight-chain saturated alkyl hydrocarbon radicals would hold the most promise for floating secondary uranium minerals. As the dithiocarbamate compounds can be made to combine these attributes they were selected for further study. The dithiocarbamates form a parallel structure to the xanthates, with the fortuitous exchange of

Jan 1, 1957

By Noel Stearn

OF THE many instruments devised for the measurement of magnetic anomalies, the ordinary dip needle, by virtue of its superior simplicity of construction, facility of manipulation, and definiteness of interpretation, seems to merit serious attention as the instrument most readily applicable to the detection of magnetic anomalies of the higher order of magnitude. , In spite of the fact that it has been used for many years for the discovery of iron ore in Europe and in the Lake Superior region of America, its capabilities as a geological instrument have not yet been thoroughly plumbed. The Wisconsin Geological Survey, under Dr. W. 0. Hotchkiss, E. F. Bean, and H. R. Aldrich, has been most thorough in developing the technique of the instrument, and the results it has obtained have aroused a general interest in a more widespread use of geomagnetics as an exploration method and the dip needle as a geological instrument. The simplicity of the instrument is an especial advantage, as it can be used by anyone, regardless of his technical training; but to insure useful results not only is a knowledge of the background of geomagnetics necessary but also an understanding of the principles of the instrument itself.

Jan 1, 1928

By John McDonald

THE amount of published literature in the field of mechanical proper-ties of magnesium alloys is not great; particularly with respect to rolled alloys. Haughton and Prytherch1 have summarized most of the articles to 1937, including their own work on sheet. Although many papers can be found dealing' with the technology of magnesium and the alloys now in commercial use, there does not seem to be any work dealing exclusively with the variation in properties of rolled alloys as caused by changes in alloy composition. Comparison of published data reveals considerable discrepancies in, properties of alloys of the same composition, probably due to differences in the details of working and heat-treating followed by different workers. The purpose of this paper is to study the proper-ties of alloys in conditions where the effect of such differences have been eliminated. It is well known that the strength and ductility of metals are functions of the working and heat-treating they have received, as well as of their chemical composition. In comparing alloys with respect to these proper-ties, therefore, all possible combinations of the variables of the fabrication procedure ought to be carried out on each alloy. One or more of these treatments will produce the highest ductility, or strength, or both. These highest properties would then be selected as characteristic of each alloy, and alloys would be compared on the basis of those properties. Thus a separation of the effect of composition and that of working and heat-treating would be achieved. In this paper, however, a compromise with completeness has been made by carrying out a restricted number of treat-ments. As a consequence, the properties obtained are not necessarily the best that the alloy is capable of exhibiting; but since all alloys have been treated by the same method, the results ought to be comparable. The elements selected for the study comprise a class that will alloy easily with magnesium, and that are relatively cheap. Each was added in different amounts, up to a limit that varied with the element.

Jan 1, 1939

By V. R. Garfias, R. V. Whetzel, J. W. Ristori

Since the entry of the United States into global war, virtually all data and information necessary for compiling figures on world petroleum consumption have become unavailable. This situation undoubtedly will continue until the world petroleum industry can return to a peacetime basis. During the past 10 years, the authors, by publishing annual estimates of .world consumption, have attempted to emphasize the importance of a yearly world-wide survey of petroleum supply and demand. It is beconling more and more evident that statistics for the United States alone can no longer give a comprehensive idea of the state of the petroleum industry, even within the United States itself. Therefore, when conditions in the industry again become normal, it is the hope of the authors that those bureaus equipped to do so will carry forward the study of petroleum supply and demand on a world-wide basis. Enough data and information are available, however, to attempt a rough estimate of world output of crude petroleum and petroleum substitutes for 1942, which to some extent may reflect the trend of world consumption. This estimate by countries, as compared with the output in 1941, is shown in Table I. The world production of crude petroleum and petroleum substitutes for 1942 is estimated at 2,208,000,000 bbl., or a decrease of 171,000,000 bbl. under 1941. Crude production is believed to have decreased by about 200,000,000 bbl., (about 9 per cent); while petroleum substitutes increased by 28,500,000 bbl., (nearly 20 per cent). The decline of crude output in the United States is estimated at 19,000,000 bb1.—less than 2 per cent; while that in foreign countries is estimated at 180,000,000 bbl., or more than 20 per cent. The marked decline abroad is due largely to losses in Venezuela and Colombia, where the lack of ocean transportation became the controlling factor, and in the East Indies and Burma, where military invasion brought about the destruction of the fields. The production of petroleum substitutes in 1942 apparently reached a new high figure of 7.5 per cent of the total world petroleum output. The important features of petroleum production outside of the United States are the changes that have taken place during the year in the supply of the Axis countries. In Japan the output for 1941 was estimated at 8,800,000 bbl., 5,500,000 of which were petroleum substitutes. It is believed that the output of synthetic oils during 1942 substantially increased, raising the total interior production of Japan to nearly 10,-ooo,ooo bbl. Also, during 1942 Japanese armed forces gained possession of oil fields having a normal peacetime output of about 78,000,000 bbl. per year. The production of these areas for 1942 is estimated at some 23,000,000 bbl., which indicates that Japan is now getting at least 33,000,000 bbl. a year, which exceeds by 8,000,000 bbl. Its

Jan 1, 1943

By J. W. Ristori, V. R. Garfias, R. V. Whetzel

Since the entry of the United States into global war, virtually all data and information necessary for compiling figures on world petroleum consumption have become unavailable. This situation undoubtedly will continue until the world petroleum industry can return to a peacetime basis. During the past 10 years, the authors, by publishing annual estimates of .world consumption, have attempted to emphasize the importance of a yearly world-wide survey of petroleum supply and demand. It is beconling more and more evident that statistics for the United States alone can no longer give a comprehensive idea of the state of the petroleum industry, even within the United States itself. Therefore, when conditions in the industry again become normal, it is the hope of the authors that those bureaus equipped to do so will carry forward the study of petroleum supply and demand on a world-wide basis. Enough data and information are available, however, to attempt a rough estimate of world output of crude petroleum and petroleum substitutes for 1942, which to some extent may reflect the trend of world consumption. This estimate by countries, as compared with the output in 1941, is shown in Table I. The world production of crude petroleum and petroleum substitutes for 1942 is estimated at 2,208,000,000 bbl., or a decrease of 171,000,000 bbl. under 1941. Crude production is believed to have decreased by about 200,000,000 bbl., (about 9 per cent); while petroleum substitutes increased by 28,500,000 bbl., (nearly 20 per cent). The decline of crude output in the United States is estimated at 19,000,000 bb1.—less than 2 per cent; while that in foreign countries is estimated at 180,000,000 bbl., or more than 20 per cent. The marked decline abroad is due largely to losses in Venezuela and Colombia, where the lack of ocean transportation became the controlling factor, and in the East Indies and Burma, where military invasion brought about the destruction of the fields. The production of petroleum substitutes in 1942 apparently reached a new high figure of 7.5 per cent of the total world petroleum output. The important features of petroleum production outside of the United States are the changes that have taken place during the year in the supply of the Axis countries. In Japan the output for 1941 was estimated at 8,800,000 bbl., 5,500,000 of which were petroleum substitutes. It is believed that the output of synthetic oils during 1942 substantially increased, raising the total interior production of Japan to nearly 10,-ooo,ooo bbl. Also, during 1942 Japanese armed forces gained possession of oil fields having a normal peacetime output of about 78,000,000 bbl. per year. The production of these areas for 1942 is estimated at some 23,000,000 bbl., which indicates that Japan is now getting at least 33,000,000 bbl. a year, which exceeds by 8,000,000 bbl. Its

Jan 1, 1943

By C. R. Whitney, G. N. Maniar, D. R. Muzyka

Previous results have shown that Pyromet 860, an Fe-Ni-base heat-resistant alloy, is stable at temperatures as high as 1500°F for aging times as long as 100 hr. This Paper describes the results of long-time creep-rupture testing at 1050" to 1400°F at various stress levels. Times as long as 37,660 hr were employed. The effects of time, temperature, and stress on the precipitates and their morphologies were studied by optical and electron microscopy, X-ray and electron diffraction, and microprobe techniques. phase, containing cobalt, nickel, and molybdenum, was detected after extended exposures from 1200" to 1400°F and careful study was performed to describe the kinetics of its formation in this alloy. µ phase formation apparently has little effect on the elevated-tem-perature properties of Pyromet 860. For times as long as 500 hr at 1300°F and below, with µ phase present, m significant effects on ambient temperature properties were noted. For longer times at 1300°F and after 1400°F exposure, the effects of u phase on ambient temperature tensile strength properties are not clear due to y' effects and grain boundary reactions. Electron-vacancy, N,, numbers were calculated using different methods described in literature and correlated with the present findings. In the selection of alloys for use in gas turbine applications, structural stability ranks as a primary criterion. High-temperature strength and cost are also of major concern. With these factors in mind, Pyromet 860 alloy, an Fe-Ni-base superalloy was designed. This alloy combines the cost advantages of Fe-Ni-base alloys such as A-286, 901, and V-57 with improved strength and structural stability'1,2 and no tendency to form the embrittling cellular 77 phase. A previous study3 reported on the stability of Pyro-met 860 at temperatures from 1375" to 157 5°F and times up to 100 hr. That study showed that the y' precipitates increased in size and separation and decreased in number with an increase in time or aging temperature. No deleterious phases were found to occur. In the present work, samples from four production heats were subjected to long-time creep-rupture testing at 1050" to 1400°F at various stress levels. Various heat treatments were used on the starting samples and tests were run up to 37,660 hr. The effects of time, temperature, and stress on the precipitates and their morphologies were studied by optical and electron microscopy, X-ray and electron diffrac- tion, and microprobe techniques. Electron vacancy numbers, Nv , calculations were made by TRW.4 Experimental results are correlated with the Nv data used to predict occurrence of intermetallic phases such as a phase. EXPERIMENTAL PROCEDURE Mechanical Tests. Material for the present study came from four production size heats of Pyromet 860 alloy, weighing from about 3000 to about 10,000 lb. All of these heats were made by vacuum induction melting plus consumable electrode vacuum remelting. The nominal analysis for this alloy is compared with the actual analysis of the four heats in Table I. Sections of these heats were forged to 9/16-in. round bar,3/4-in. square bar, 3-in. round bar, 4-in. square bar, and a gas turbine blade forging about 16 in, long, about 6 in. wide, and weighing about 20 lb. In general, all forging of this alloy is done from a 2050°F furnace temperature. Longitudinal test blanks were cut from the centers of the smaller bars, from mid-radius positions for the 3- and 4-in. bars, and from the air foil of the gas turbine blade and heat-treated according to the procedures outlined in Table 11. Heat treatment A is the "standard treatment" recommended for this alloy for best all-around strength and ductility. Heat treatment B is a modification of treatment A for improved tensile strength at moderate temperatures. The treatment coded C was designed for treating large sections according to a procedure previously described.' Heat treatment D was developed to yield optimum stress relaxation characteristics at 1050°F for a steam turbine bolting application. After heat treatment, the test blanks were machined either to plain bar creep specimens with a gage diameter of 0.252 in., to combination smooth-notched stress-rupture bars with a plain bar diameter of 0.178 in. and a concentration factor of Kt 3.8' at the notched section, or to notch-only specimens. All specimens conformed to ASTM requirements. Metallography. Most of the creep-rupture tests were continued to failure. A few bars were fractured as smooth or notch tensiles after creep-rupture exposures. After fracturing, ordinary metallographic sections were made primarily in gage areas adjacent to fractures to represent a "high-stress" region and through specimen threads to represent a "low-stress" region. All metallographic sections were made in a longitudinal direction with respect to the test specimen axes. For optical microscopy, the samples were etched in glyceregia (15 ml HC1, 5 ml HNO,, 10 ml glycerol). For XRD analysis, the phases were extracted electrolytically in two media: 20 pct &Po4 in H20 for selective extraction of y' and 10 pct HC1 in methanol for carbides and other phases.

Jan 1, 1970

By C. R. Dale

The need for instruments to measure the movement of fluids and gas in wells has been recognized by engineers for many years. Information regarding flow in the producing interval has a direct bearing on completion practices in new wells and also provides information on the production characteristics of the well. Many hours of engineering time are spent in planning and completing wells but knowledge as to whether or not the original planning has produced the desired results has not always been complete. Many questions such as the following often arise: Why is it that two wells are completed under supposedly identical conditions, yet one well is a good one and the other is a poor one? Are the sands that look the best on the electric log contributing to the production? These and many other conditions in the producing well need to be under- stood in order to develop more efficient production practices and to improve on methods of completing new wells. It is the purpose of this paper to briefly describe one type of instrument, outline the methods of running the equipment and show the results of surveys made under various conditions. With an understanding of the use of this type of survey its importance can be evaluated in relation to the problems encountered by the operator. DESCRIPTION OF INSTRUMENT The instrument is a velocity recorder employing a clock-controlled 16mm film for recording the rpm of an extremely sensitive rotor which is rotated by the flow of fluids or gas in a well. The helical-vaned rotor and shaft, weighing one-half of one ounce are an integral unit exposed to the well fluids and are the only moving parts not enclosed in the fluid-tight housing. No packing or fluid seal of these parts is necessary and the shaft is mounted top and bottom on special jeweled bearings. Fig. A is the lower part of the instrument showing rotor and shaft with the protecting housing sleeve removed. The rpm of the rotor is recorded on the moving film by a combination electrical and optical system. The record is a series of dashes on the film, each dash and space representing twenty (20) revolutions of the rotor. (Film record of survey made in California well showing station recordings at various depths.) As the movement of the film is controlled by the clock the number of dashes and spaces in one minute of film travel represents the rpm of the rotor. The range of the instrument is from 0 to 2,500 rprn. The barrel or housing is 1-11/16 in. OD and seven feet long. Various types of expanding fluid traps are attached to the lower end of the instrument to direct the flow through the 1 in. orifice containing the rotor. The fluid trap for upward flow is shown in Figs. B and C. This assembly consists of eight arms with light spring

Jan 1, 1949

By C. R. Dale

The need for instruments to measure the movement of fluids and gas in wells has been recognized by engineers for many years. Information regarding flow in the producing interval has a direct bearing on completion practices in new wells and also provides information on the production characteristics of the well. Many hours of engineering time are spent in planning and completing wells but knowledge as to whether or not the original planning has produced the desired results has not always been complete. Many questions such as the following often arise: Why is it that two wells are completed under supposedly identical conditions, yet one well is a good one and the other is a poor one? Are the sands that look the best on the electric log contributing to the production? These and many other conditions in the producing well need to be under- stood in order to develop more efficient production practices and to improve on methods of completing new wells. It is the purpose of this paper to briefly describe one type of instrument, outline the methods of running the equipment and show the results of surveys made under various conditions. With an understanding of the use of this type of survey its importance can be evaluated in relation to the problems encountered by the operator. DESCRIPTION OF INSTRUMENT The instrument is a velocity recorder employing a clock-controlled 16mm film for recording the rpm of an extremely sensitive rotor which is rotated by the flow of fluids or gas in a well. The helical-vaned rotor and shaft, weighing one-half of one ounce are an integral unit exposed to the well fluids and are the only moving parts not enclosed in the fluid-tight housing. No packing or fluid seal of these parts is necessary and the shaft is mounted top and bottom on special jeweled bearings. Fig. A is the lower part of the instrument showing rotor and shaft with the protecting housing sleeve removed. The rpm of the rotor is recorded on the moving film by a combination electrical and optical system. The record is a series of dashes on the film, each dash and space representing twenty (20) revolutions of the rotor. (Film record of survey made in California well showing station recordings at various depths.) As the movement of the film is controlled by the clock the number of dashes and spaces in one minute of film travel represents the rpm of the rotor. The range of the instrument is from 0 to 2,500 rprn. The barrel or housing is 1-11/16 in. OD and seven feet long. Various types of expanding fluid traps are attached to the lower end of the instrument to direct the flow through the 1 in. orifice containing the rotor. The fluid trap for upward flow is shown in Figs. B and C. This assembly consists of eight arms with light spring

Jan 1, 1949