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By William Crowe Kellogg

By now the term AFMAG has been fairly well introduced to the mining industry. Several papers have been presented and published concerning AFMAG (references 1 and 2). However, the term AFMAG remains rather new to the industry, and the exact place which AFMAG occupies in the minerals exploration field is still somewhat uncertain in the minds of many who may have use for this new and interesting method of electromagnetic exploration for conductive minerals. It is the purpose of this paper to again review the basic theory of the AFMAG system, to describe and - illustrate the equipment and data presentation as used in aerial surveying, and to provide some idea of the cost and nature of airborne AFMAG surveys. This paper is primarily of a general descriptive nature and presents AFMAG theory in a schematic rather than mathematical form; emphasis is placed on the equipment, the present method of data presentation and survey operations, since it is believed that such, information will now generally best serve to inform the mining industry of the characteristics of the AFMAG system.

Jan 1, 1960

By J. M. Clark

(Wilkes-Barre Meeting, June, 1911.) For some years past, those interested in the development of the increasingly important mining industry of Canada, have urged the adoption by the Dominion Parliament of a federal mining-law, which would have the force and stability of statutory enactment. At present, placer-mining in the Yukon Territory, is governed by the Yukon Placer Mining Act. All other mining under federal jurisdiction is governed by 'Orders in Council and Ministerial Regulations. In the earlier stages of development, it is perhaps a matter of necessity that these important matters should be so dealt with; but it is now felt that the time has come when mining-rights in the extensive regions under federal control should be put on a permanent basis, -and that any changes required from time to time should be made only after full and open discussion in Parliament. A short sketch will suffice to indicate how vast and varied the interests affected really are. When the Dominion of Canada was constituted by the Imperial Statute known as the British North America Act of 1867 (which came into force by proclamation on July 1 of that year), it comprised only the present Provinces of Ontario, Quebec, Nova Scotia, and New Brunswick; but provision was made for the inclusion of Newfoundland, Prince Edward Island, British Columbia, Rupert's Land, and the North West Territories. Subsequently Rupert's Land and the North West Territories were acquired, the 'Crown Colonies of British Columbia and * SECRETARY'S NOTE.-Mr. Clark, an eminent Canadian lawyer, and joint author of the treatise on "The Law of Mines in Canada," has been requested by the Do¬minion Government to prepare a Federal mining-law, and presents this paper, by invitation of the Council, in order to obtain, if possible, useful suggestions from members of the Institute.-R. W. R.

Apr 1, 1911

By R. S. Rickard, H. D. Peterson, J. D. Miller, M. C. Fuerstenan

Pure chrysocolla is floated with chelating agents that form insoluble complexes with copper at ambient temperature. Complete flotation is obtained with potassium octyl hydroxamate as collector at pH 6. Flotation response is enhanced with increased temperature when low additions of hydroxamate are involved. A natural ore was floated with 0.4 1b per ton octyl hydroxamate at pH 6.5 and 58°C, and a flotation recovery of 76% was obtained with a concentrate grade of 31.6% copper. The flotation characteristics of the oxide copper minerals, malachite, azurite, and cuprite, have not presented the difficulty for concentration as have those of the copper silicate, chrysocolla. The copper carbonates and oxides respond reasonably well to flotation with conventional collectors, whereas chrysocolla will not respond to flotation with fatty acids or xanthates under normal flotation conditions. In this view then, other reagents will have to be devised to function as collectors for chrysocolla. The most obvious general class of reagents for this purpose would seem to be the organic copper chelating compounds. The utility of chelating agents as collectors in flotation systems has already been demonstrated. For example Vivian1 has floated cassiterite using ammonium nitrosophenylhydroxylamine. Holman2 studied the flotation of nickel oxide ores with dimethylglyoxime and also suggested the use of taurine on oxidized lead ores. A rather detailed study on the application of certain chelating agents to some flotation systems was presented by Gutzeit.3 This work indicated that the formation of surface insoluble chelates is probably responsible for flotation in many cases. The role that soluble chelating agents assume was also presented, that is with effective removal of polyvalent cations by complex formation, effective depression of quartz can be obtained. DeWitt and Batchelder4,5 have shown that oximes function well as collectors for chalcocite, malachite, azurite, and cuprite. Ludt and DeWitt6 have presented the possibility of using dyes, such as octyl malachite green, as a collector for chrysocolla. These works presented by DeWitt et al suggest that organic copper chelating compounds offer considerable promise for concentrating chrysocolla, but that the most suitable chelating reagent from the standpoint of cost and flotation response has yet to be determined. The present investigation was undertaken to study the flotation response of chrysocolla to selected copper chelating compounds, that is ethylenediamine, hexamethylenetetramine, potassium octyl hydroxamate, dimethylglyoxime, and benzoin a-oxime. EXPERIMENTAL MATERIALS Chrysocolla: The chrysocolla used in the microflo-tation studies was from New Mexico and analyzed 20.8% copper. X-ray diffraction showed this material to be amorphous in character, but some faint lines of quartz were noted. A natural oxide copper ore from Utah was also used in the investigation. This ore contains malachite principally but also contains chrysocolla and tenorite together with some sulfide copper. The sulfide copper comprises from 15 to 20% of the total copper content of the ore. Water: Conductivity water was used in the microflo-tation experiments, while Golden tap water was used in the experiments with the natural ore. Reagents: Reagent grade n-amyl alcohol was used as frother in the experiments with pure mineral, while MIBC was used in the work with the ore. Ethylenediamine, hexamethylenetetramine, dimethylglyoxime and benzoin a-oxime were reagent grade in quality. Pure potassium octyl hydroxamate was prepared as follows: 1) 1.0 mole of KOH in 140 cc of methanol was combined with 0.6 mole of hydroxyl-amine hydrochloride in 240 cc of methanol at 40°C (KC1 precipitates under these conditions and to effect complete removal of KCl, the system was cooled to 10°C and filtered), 2) a light methanol wash was then given the KC1 cake, 3) the filtrate was agitated at room temperature and 0.33 mole of the methyl ester of the organic acid (i.e. methyl octanoate) was

Jan 1, 1965

By E. S. Bumps, H. D. Kessler, M. Hansen

The titanium-rich end of the Ti-AI phase diagram has been determined to the compound TiAI3 (62.7 pct Al), thus joining the aluminum-rich portion previously investigated by others and completing the diagram. Micrographic analysis and X-ray diffraction were the chief methods used to determine the phase relationships. THE Ti-Al phase diagram has been investigated as part of a program on titanium phase diagrams for the Wright Air Development Center. Included in the available information concerning the phase relationships in titanium-rich Ti-A1 alloys is a brief statement by Brown' that: "aluminum raises the transformation temperature to 1000°C (183Z°F)." This observation is interesting in that it is the first example of a metallic alloying component raising the transformation temperature of titanium, and consequently widening the field of the a solid solution. Busch and Freyer' presented resistivity data which indicated the formation of titanium-rich solid solutions of 1 and 3 pct A1 alloys prepared by powder metallurgy methods. Duweza found that there is only one other intermediate phase other than the known compound TiA1, (62.7 pct Al). This phase, designated as y, is of variable composition; its crystal structure is of the AuCu type and is therefore based on the composition TiAl (36.02 pct Al). Earlier work on the constitution of the aluminum-rich alloys has been reviewed by Hansen, and need not be discussed here. The tetragonal crystal lattice of TiAl,, as found by Fink, Van Horn, and Budge," was confirmed by Brauer." Recently, Schubert7 has reported that TiA1, is homogeneous within a limited composition range; however, the solubility limits were not given. The Ti-A1 phase diagram as presented in. this paper was determined by micrographic analysis of alloys containing from 1 to 62 pct Al, annealed at and quenched from temperatures between 700" and 1400°C. The phases and phase ranges investigated extend to the compound TiA1, (62.7 pct Al) to join the aluminum-rich end of the system determined by other investigators, thus completing the diagram. Methods of Investigation Preparation of Alloys: Iodide titanium, 99.9+ pct pure, obtained from the New Jersey Zinc Co., and high-purity (99.99+ pct) aluminum sheet from the Aluminum Co. of America were used to make up alloy ingots weighing 10 to 20 g. Detailed descriptions of melting techniques have been presented previously for work on the Ti-Mo and Ti-Cb> nd Ti-Si" phase diagrams. Briefly, the melting practice consisted of arc melting an accurately weighed charge in a copper block crucible insert in a non-consumable tungsten electrode furnace, under helium at atmospheric pressure. All ingots were carefully weighed after melting to detect possible losses. Comparison of weight before and after melting showed no appreciable weight changes. Also, chemical analyses were in close agreement with nominal compositions, Table I. The diagram as presented is, therefore, based on nominal compositions. Alloys were prepared having the following nominal aluminum contents: 1 ... 36 (1 pct increments), 38, 40, 41, 42.5, 44, 45, 46, 47.5, 49 . . . 64 (1 pct increments), 67, 70, 80, and 90. Ingots with up to 14 pct A1 were cold-pressed various amounts in order to increase the rate of attaining equilibrium structures on heat treatment. The amount of cold deformation that could be applied decreased with increasing aluminum content, until alloys containing 12 pct A1 or more cracked after only a few percent deformation. Annealing Treatments: Samples annealed at temperatures of 700" to 1000°C were sealed in

Jan 1, 1953

By John C. Brower

Bolivia is nor a major gold producer but has produced continuously since pre Inca times. Production reached a peak in 1964 of about 4,000,000 grams and is currently about 1,000,000 grams. Production is mainly from the Tipuani River valley north of La Paz and is derived from Pleistocene basin fill: the Cangalli conglomerate and overlying terraces. Abandoned Pleistocene lake terraces south of La Paz in the Oruro area are another source of gold whose potential have not been realized. In both the Tipuani and Oruro areas, primitive hand methods are the principal means of production, with the exception of a single modern dredge. In spite of a long history of production, probably very little of the gold potential has been mined.

Jan 1, 1979

By G. K. Manning, W. E. Few

T has been known for some time that both'inter-granular carbide and intergranular oxide phases cause brittleness in molybdenum. Parke and Ham' indicated that 0.0025 pct 0 present in molybdenum after solidification from the melt was sufficient to induce intergranular brittleness during forging. However, material containing 0.06 pct C could still be forged. However, adding this amount of carbon to insure deoxidation causes the formation of carbides on freezing. These carbides are precipitated at grain boundaries, and Rengstorff and Fischer' have shown they have an unfavorable effect on the room-temperature ductility of molybdenum. Take? in 1928 proposed that the solubility of carbon was a constant value of 0.30 pct from room temperature up to 1800°C. In 1935, Sykes, Van Horn, and Tucker' obtained X-ray data suggesting that the solid solubility of carbon in molybdenum was between 0.07 and 0.09 pct at temperatures from 1500" to 2100°C. The a-solubility line for carbon was included in the Mo-C diagram given in the Metals Handbook as a tentative line based on the data of Sykes, Van Horn, and Tucker. In order to determine the partial phase diagrams for these systems, it was necessary to construct a high-temperature furnace suitable for heat treating molybdenum at temperatures up to 4000°F. A molybdenum resistance furnace was built for this purpose in which samples could be heat treated in a purified atmosphere and quenched from any desired temperature.' Experimental Work Solubility of Carbon: Arc-cast molybdenum supplied by the Climax Molybdenum Co. and 18-gage molybdenum wire samples produced by powder metallurgy at the Fansteel Metallurgical Co. were used in determining the a-solubility line for the MO-C system. The cast molybdenum contained 0.032 pct C initially. Two lots of 18-gage wire were used, one containing 0.011 pct C and the other 0.005 pct C initially. All material contained a carbide phase as received. Fig. 1 illustrates the carbides found in the untreated material. Heat treatment in a purified hydrogen atmosphere was found to reduce the carbon content in the as-cast molybdenum. Purified argonT also decarburized molybdenum samples at temperatures above 3500°F; however, the carbon content remained constant during heat treatment in purified argon at lower tem- peratures. The argon was purified by passing it over titanium at 750 °C and then through a magnesium perchlorate drying tower. The hydrogen was purified by passing it through a commercial hydrogen deoxidizer, followed by a drying tower. Specimens having different initial carbon contents were heat treated in argon at 3500°F for periods ranging from 5 min to 5 hr and were analyzed for carbon. Samples of the same final carbon content had the same microstructures regardless of time at temperature. Furthermore, a gradient between center and surface in the amount of undissolved carbide particles present was never observed. It was concluded that at these low carbon levels, and at the high temperatures involved, diffusion proceeds so rapidly that the specimen is always substantially homogeneous in carbon content, in spite of the gradual loss in carbon. Based on the above findings, the following procedure was used to determine the carbon-solubility limit at 3000°, 3500°, and 4000°F. At each of these temperatures, a number of samples were heat treated, as shown in Table I, and rapidly cooled to room temperature. Since the samples lost carbon in proportion to the length of time heated, a series of samples were obtained of varying carbon contents. By use of a rapid cooling rate, the phases present at the high temperature were retained at room temperature. All samples were examined microscopically. Those found to contain either no excess carbide phase or only a very small amount were then analyzed for carbon. The samples actually analyzed for carbon

Jan 1, 1953

By J. B. Cheatham

Applications of the mathematical theory of plasticity promises to lead to the solution of many drilling and rock mechanics problems. ,Because of mathematical considerations, the inelastic behavior of rock has frequently been represented by a perfectly plastic model in conjunction with a yield criteria of the Coulomb or Mohr type. The totality of all stress states for which a solid ceases to behave elastically can be represented as a limit surface in stress space. ,Probing of such limit surfaces indicates details of strain hardening which are not provided by the standard triaxial testing procedure. Probing tests of the limit surfaces have been performed on Cardova Cream limestone to provide data for extending plasticity theory to cover situations in which consolidation and strain hardening are present. Test results indicate that this highly porous limestone undergoes a permanent volume decrease when it is subjected to hydrostatic pressures in excess of 3,500 psi. A virgin sample tested under a confining pressure of 1,500 psi has a yield strength of 1,700 psi; however, if the sample is subjected to a consolidation pressure of 5,000 psi, before testing at 1,500 psi, the yield strength is raised to 2,300 psi. Thus, both consolidation and strain hardening are important considerations in describing the mechanical behavior of this limestone. Tests conducted with the axis of the core having different orientations indicate that this rock is also anisotropic. Portions of the initial and subsequent limit surfaces are determined for samples loaded either perpendicular or parallel to the bedding planes. INTRODUCTION Previous experimental work in rock mechanics indicates that no mathematically tractable constitutive theory is inclusive enough to describe the mechanical behavior exhibited by all types of rocks under all conditions of stress and temperature. Indeed, the type of deformation encountered in a single type of rock is known to depend upon the stress and temperature conditions in the rock during deformation.l-5 Certain rocks and minerals, notably those minerals composed of ionic salts, have been shown to exhibit plastic deformation when tested under conditions of high confining pressure.2 Since the mathematical theory of plasticity provides simplifications over the theory of elasticity in certain types of problems, such as those in which limit analysis can be applied, it is of interest to know under what conditions plasticity theory may be applied to rock mechanics problems. The following factors determine the nature of the deformation a particular specimen will undergo: (1) the microscopic structure of the rock, i.e., the structure visible under an optical microscope, including number of phases, porosity, distribution of phases, (2) the mineralogical structure of the solid phases, (3) the conditions of stress and the rate of change of stress and (4) the temperature. Extensive experiments on Yule marble, Carthage marble, Solenhofen limestone and other calcerous rocks indicate that these relatively nonporous rocks deform plastically under certain conditions of loading, and creep under other conditions of loading.l-3 This study is concerned with the behavior of Cordova Cream limestone (Austin chalk) which is also composed almost entirely of calcite and thus has the same mineralogical composition but, because of a rather large porosity, it possesses a different microscopic structure. This investigation was undertaken to learn if Cordova Cream limestone deforms plastically despite the embrittling effect of the pore spaces, and to provide data which can be used to determine whether the mathematical theory of plasticity can describe the mechanical behavior of Cordova Cream limestone. A brief discussion is given of some of the underlying principles of plasticity theory concerning stress space and limit surfaces. Strain hardening is defined and a discussion is given of how the mechanical behavior of a material can depend on the previous history of the loading. This is followed by a description of the experimental procedures

By B. F. Decker, J. H. Keeler, W. R. Hibbard

Textures of hot-rolled, of cold-rolled, and of cold-rolled and annealed zirconium sheets were determined by use of an X-ray spectrogoniometer. All textures showed a tilt of the basal planes 240" from the rolling plane about the rolling direction. Deformation textures showed the [1010] direction to be approximately in the rolling direction. After recrystalliza-tion, the 111201 direction was approximately in the rolling direction. This texture was sharpened by annealing above the allotropic transformation. Textures of sheet produced by alternately cold rolling and then annealing were less strongly oriented than sheets that underwent severe deformation without intermediate anneals. THIS study of the deformation and annealing textures of high purity zirconium was carried out to supplement an investigation of zirconium and zirconium-base alloys. The spectrogoniometer method of pole figure determination was used and yielded more detailed and precise information than the photographic techniques used by previous investigators. Earlier investigations of the rolling textures of hexagonal metals titanium,1,2 beryllium," and zirconiumL having a c/a ratio slightly less than 1.6 disclosed a rotation of the basal planes from the rolling plane about the rolling direction so that the basal poles were inclined toward the transverse direction, and with one exception,& the [1010] direction was found parallel to the rolling direction. Similarly, hot rolling produced a spread of the basal poles in the transverse direction,2,3,5 With the [1010] direction parallel to the rolling direction. The textures of these metals after recrystallization differ somewhat from each other although still exhibiting the transverse rotation of the basal poles about the rolling direction. Zirconium" was found to have the [1120] direction in the rolling direction, beryllium" continued to have the [1010] direction in the rolling direction, and titanium' was shown to have the [1010] direction in the rolling direction (the cold-rolling texture) when annealed at 1000°F, changing to the [1120] direction in the rolling direction when annealed at 1500°F. It was suggested2 that the titanium retains the deformation texture after re-crystallization, and preferred grain growth at higher temperatures produces the second texture. Annealing above the allotropic transformation temperature did not appreciably change the high temperature recrystallization texture for titanium.' Coarsegrained zirconium showed more spread" in the transformation texture than in the recrystallization texture. The material used in this investigation was crystal-bar zirconium prepared by the iodide process. The major impurity was hafnium which was less than 0.3 pct. The composition obtained by spectro-graphic analysis is given in Table I. The hot-rolled specimen was prepared from a 50-g button of zirconium arc-melted in a water-cooled crucible under an argon atmosphere. This button was enclosed in a welded sheath of soft iron and the ensemble was rolled at 825°C. After each pass the sheath was put back into the furnace to allow it to return to the desired temperature. The zirconium ingot was reduced in this manner to a thickness of about 0.035 in., a reduction of approximately 90 pct. The sheet after removal from the sheath was alternately polished and etched to a thickness of 0.001 in. Cold-rolled specimens were prepared from crystal bar by a series of reductions of approximately 0.010 in. until the sheet reached a thickness of 0.010 in. after which it was cold-rolled to 0.001 in. thickness between sheets of alloy steel. The total cold reduction amounted to about 99.8 pct. Specimens were annealed in an evacuated Vycor or quartz tube. The transmission pole figures were obtained by the quantitative method of Decker, Asp, and Harker6 modified by Geisler7 using an X-ray spectrogoniometer with Cu Ka radiation. Unless otherwise specified all four quadrants were examined with 5" increments along the radius of the pole figure. Absorption corrections were made for changes in length of the X-ray path through the sample as inclination of the

Jan 1, 1954

By Bhudeo N. Sinha, Paul Dean Proctor

Heavy metal contents in stream waters, sediments, and selected aquatic algae were determined for the upper Meramec River basin, Missouri, of 3905 km2 (1508 sq mi) area and site of the proposed and controversial Meramec dam and reservoir. Six distinct drainage areas within the basin are: (1) a lightly industrialized and farm area, (2) a primitive forested- ranch area, (3) an area which includes the Northern New Lead Belt, (4) the westward drainage of an old and extensive barite mining area, (5) the main trunk of the Meramec River, and (6) short north-divide tributaries of the Meramec River. Lower Paleozoic sediments rest nonconformably upon eroded and hilly Precambrian igneous basement. This locally rises as major inliers and also makes up the St. Francois Mountains to the east. Major lead, and lesser zinc, copper, cobalt, and nickel mineralization occurs in the buried Cambrian Bonneterre dolomite. Residual barite is present along the eastern fringe of the basin and is derived from the Potosi formation. Some 62 water samples, active stream sediments (AS), bank samples (BS), and 11 selected aquatic algae samples were collected in the various drainage areas and analyzed for copper, lead, zinc, cadmium, nickel, arsenic, and mercury contents. Heavy metals in water have a maximum range of 1-120 ppb (parts per billion), and this for zinc. The AS and BS sediments have orders of magnitude greater acid leachable metal contents in the -80 mesh fraction, with lead hawing the greatest range of 11-1028 ppm. Heavy metal content of stream-algae approaches that of the sediments in which they grow. Most anomalous heavy metal accumulations occur near mining and milling activities and in the streams draining such areas. Significant distortions of the primary dispersion pattern militate against geochemical exploration for hidden ore zones, but do demonstrate the mining, milling, and smelting activities of man, and sporadic mineral occurrences in younger horizons.

Jan 1, 1980

By A. Daouadji, P. Cazes, S. Grange, L. Briançon, R. Milane

Construction in congested urban areas is often accompanied by geotechnical problems due to high loads and the impact caused by nearby buildings. For this reason, it is important to understand the behavior of the soil and the structure without forgetting the essential role of the interaction between them. Experiments, instrumentation and numerical modeling are the main methods used to study this behavior. To this end, pressure cell, strain gages, vibrating wire extensometers and optical fiber sensors are installed on the reinforcement steel of pile and raft foundations to monitor stresses and induced deformation in these elements during and after construction. A fiberglass rod extensometer is placed in the soil to help measuring the displacement due to excess loading, knowing that the pile foundations are embedded in the Rhône’s alluviums and reach the molasse, a particular and challenging soil with properties that are not yet well understood. The objective of this paper is to present the geotechnical instrumentation program carried out for the tower Silex2 in Lyon, France, and to describe the types of sensors used and their installation on site. INTRODUCTION The complexity of geotechnical structures like dams, bridges or high-rise buildings requires a sound understanding of the behavior of the soil, the structure itself and the interface. Therefore, a geotechnical instrumentation program can be essential in many ways. During the site investigation stage, it can help determine the initial conditions experienced by the soil in the field by measuring parameters such as the compressibility index or the permeability. During the construction stage, real time measurements can protect the structure from premature failure, help validate and optimize the design if needed. In addition, sensors measuring pore-water pressure, loads, deformations and settlements allow for monitoring the performance of the structure. This is called the observational method. Finally, during the operating phase, instrumentation aims to study the long-term behavior of the structure (Nicholson et al., 1999).

Jan 1, 2019

By H. R. Hose

The total crude fluorspar reserves in Western Europe, including the USSR and the Soviet sphere, Thetotalare estimated to exceed 17 million metric tons. The total fluorspar production in 1951 in Western Europe, excluding the USSR and Soviet sphere, amounted to 371,109 metric tons. The chief fluorspar-producing countries in Europe, excluding Russia and the Soviet sphere, are France, Western Germany, Italy, Spain, and the United Kingdom. TOTAL crude fluorspar reserves in western Europe, containing more than 35 pct CaF2, are estimated at 12 million metric tons, while reserves in the USSR and Soviet sphere may exceed 5 million metric tons. The bulk of these reserves are concentrated in the USSR, Spain, United Kingdom, Western Germany, and Italy. Since published estimates of the tonnages of individual mines and explored deposits are not available for most countries in Europe, the estimates given in Table I for individual countries are necessarily approximate, as they have been compiled from various sources and modified and combined according to the author's judgment. The majority of fluorspar deposits in Europe belong to the late Paleozoic metallogenetic epochs and have been found within or along the borders of the Hercynian massifs. Deposits in the Central and Esterel massifs of France, those of Western and Eastern Germany, Sardinia, the Catalonian coastal range and the Sierra de los Santos in Spain, and those of Devonshire and Cornwall belong to the Hercynian metallogenetic epochs. The deposits in southern Norway and Sweden belong to the middle Paleozoic or later, those of northern England to the late Paleozoic or later, those of northern Spain and Greece to the late Mesozoic, and those of northern and probably central Italy and Switzerland to the early Tertiary. Fluorspar occurs typically in veins, lenses, and stringers, but also in bedded replacement deposits and pockets, and may be colorless to white, yellow, green, pink, brown, blue, or purple to almost black. Except for the colorless variety, the only kind which can be used for the optical industry, the color of the fluorspar does not affect its ultimate use. Crystalline cubic or octahedral fluorite of CaF2 composition, with 48.9 pct fluorine and 51.1 pct calcium, has a specific gravity of 3.18. The ore in place, however, usually averages 3.0 metric tons per cubic meter owing to the quantity of other minerals asso- ciated with the fluorspar in the veins and the physical state of the fluorspar, which may vary from sugary to massive crystalline or microscopic inter-growths with barite or quartz. Barite of 4.5 sp gr, quartz of 2.66 sp gr, and chert and calcite are commonly associated with fluorspar. Other minerals usually present in lesser amounts are celestite, wad, silver, lead, zinc, copper, iron, and uranium minerals. In some cavity fillings the rhythmic deposition of the fluorspar, barite, and quartz into successive crusts may make it possible to handpick the crude ore on belts or to separate the fluorspar from other minerals while the actual mining is carried on. Where metallurgical grade lump spar is required for foundries, separation of quartz and barite may be made also by jigs and heavy media, and in some mines the lead and zinc sulphides may be separated and recovered by vibrating tables. However, except in the case of unusually high grade deposits, acid grade fluorspar is obtained by flotation. By this process fluorspar deposits grading down to 35 pct CaF2 in the crude ore can be worked at a profit when fluorspar, lead, zinc, and silver prices are high, as the sulphides of these ores can be separated from the fluorspar by flotation and concentrated.

Jan 1, 1956

By Hengst B

The first production stage in any mining operation is the breaking of whole rock into fragments small enough for loading and subseq- uent handling. This primary fragmentation is most frequently accomplished with blasting. The maximum fragment size and the fragment size distribution have an influence on the subsequent loading, handling and crushing costs. It is assumed that total rock fragmen- tation in practice is a result of an interact- ing array of radial cracks from various blastholes. The representation for the basic pattern of radial cracks emitted from a particular blasthole is first described. A model is then developed simulating the interaction between blastholes at various burdens and spacings, and in simultaneous and delayed modes. The resultant picture is analysed and a fragment size distribution calculated. Methods of incorporating the existing faults in the rock are also discussed. Finally application of this model to various facets of mining are considered.

Jan 1, 1977

By M. L. Hammond, G. M. Bowers

Silicon dioxide films have been prepared on silicon wafers by the oxidation of SiH, near 400°C. Results previously reported by Goldsmith and Kern7 have been qualitatively corrobovated using a system of different geometry, and significantly greater deposition rates have been achieved. The deposition rate is independent of thickness and nearly independent of the O2/SiH, ratio over a wide range; however, the rate is strongly temperature-dependent. The structure of the deposit depends upon the cleanliness of the substrate, and the electrical field strength of the deposited oxide depends upon the nature of the electrodes. MULTILEVEL interconnects in integrated circuits using aluminum metallization require an insulator that can be deposited at low temperature. Because the A1-Si eutectic is only 577°C, the maximum deposition temperature must be below about 500°C to prevent reaction of the aluminum with the silicon and with other materials in the integrated circuit. Many methods of depositing insulating films of SiO, and other dielectrics have been reported'-6 but the technique described by Goldsmith and Kern7 offers the simplest method of preparing SiO, films. The technique involves the reaction of SiH, and 0, to form SiO, films in the 300" to 500°C temperature range. Previous work using this gas system has been reported8 and the initial development work at Philco Microelectronics was done at the East Coast R&D Laboratories. 9 This paper corroborates some of the results of Goldsmith and Kern,7 shows that much higher deposition rates can be obtained than previously reported, and presents some observations on the structure of deposited SiO, films. EXPERIMENTAL CONDITIONS Fig. 1 is a schematic drawing of the apparatus used in this study. It differs from that of Goldsmith and Kern in that 1) the gases are mixed before they enter the reaction chamber, 2) there is no fritted glass diffuser, and 3) the wafers are stationary during deposition. The control thermocouple was in a well located 0.06-in. from the substrate, and three gas supplies were used: 1 pct SiH4 in N 2, O 2, and N 2. Water vapor must be excluded from the plumbing to prevent the formation of colloidal SiO, and the SiH4 must be diluted with an inert gas because SiH4-0, mixtures are extremely flammable above about 4 pct SiH The wafer temperature was determined by attaching a thermocouple to a test wafer and the temperature was maintained to +5 C. The conditions used in this investigation are listed in Table I. The temperature range was chosen for compatibility with the A1-Si system. The volume ratio of 0, to SiH4 is the actual volume of 0, delivered to that of SiH4, taking into account the initial dilution of the SiH4. This ratio, which was used by Goldsmith and Kern,7 is a useful indicator of the experimental conditions. The active/inactive ratio is the ratio of the volume of active gases, SiH4 and O2, delivered to the volume of dilution gas. The active/inactive ratio is an important parameter to specify for deposition rate determinations since it determines the amounts of reactants that arrive at the sample per unit time. Fairly high dilution ratios were necessary to achieve uniform deposits of SiO,. Most of the process characterizations were performed on the polished (111) face of 3 to 5 ohm-cm, n-type silicon wafers which were 0.009 in. thick; but the data approximately apply to deposition of SiO, on thin films of aluminum. It is difficult to obtain accurate deposition rate data over aluminum films because of coarsening the aluminum surface during exposure to 300" to 400°C. The deposited SiO, film fol-

Jan 1, 1969

By K. Madhusudan Reddy

"Pile response under combined uplift and lateral load is very important and it is imperative to evaluate the effect of combined loading and only few studies were reported on pile behavior under combined uplift and lateral loads. Model pile made-up of aluminum having an outer and inner diameter of 25.4 mm and 19.4 mm respectively is used. Dimensions of the model steel tank are fixed as 1.0 m x1.0 m x 1.2 m (depth) to avoid the boundary effects under combined lateral and uplift loads. Experiments were carried out on single piles at isolated uplift, isolated lateral loading and combined lateral and uplift loading, embedded in sandy soil. Results indicate that load–deflection behavior is nonlinear for isolated uplift and lateral load tests as well as in case of combined loadings. It is also observed that the behavior of piles under isolated loadings is substantially different when compared to combined loading.INTRODUCTIONPile foundations are generally used to support compressive loads from superstructures. Some structures, like transmission towers, mooring systems for ocean surface or submerged platforms, tall chimneys, jetty structures, etc. are constructed on pile foundations, which have to resist large lateral and uplift loads and moments. The various loads (compressive, lateral and uplift) and moments act on the piles simultaneously rather than isolated manner. There are well-established theoretical methods present to evaluate the pile behaviour under different isolated loadings namely, verticalcompressive, vertical-uplift and lateral (Poulos and Davis, 1980), but there are very limited studies focused on pile behaviour under combined loadings. Though there is good number of studies reported on pile behaviour under combined compressive-lateral and compressive-uplift loadings (Ramasamy, 1974; Jain et al. 1987; Zhang and Small, 1999; Dash and Pise, 2003; Karthigeyan et al. 2006 & 2007; , there are only very few studies reported on pile behaviour under combined uplift and lateral loads. Darr et al. (1990) described an approach to a rational solution of the interaction of pile to combined uplift and lateral loads based on analytical and experimental studies. Influence of cyclic loading was also considered. Narasimha Rao and Prasad (1993) investigated the uplift behaviour of pile anchors subjected to lateral cyclic loading. There were many onshore and offshore situations where lateral cyclic loading may affect both the pullout and lateral loading capacity of pile anchors. Jetty and wharf structures are usually subjected to lateral forces from wave and wind action. If these cyclic lateral loads are acting on the supporting piles, the resulting movement of the upper part of the embedded length of pile may reduce the skin friction. This progressive deterioration in pullout resistance may not be reflected by a pullout test made soon after the installation. Hence, Tomlinson and Woodward (2008) pointed out that a generous safety factor on the ultimate pullout load should be adopted for piles in such situations. Mroueh and Shahrour (2007, 2008) presented a threedimensional finite element analysis of the response of battered piles to the combined lateral and vertical pullout loads. Nevertheless, the model is not validated well due to lack of good experimental data based on rigorous experiments. Thus there is a scope for investigating the effect of lateral load on pile behaviour under uplift load and vice versa based on carefully designed experiments, which is main focus of the present investigation."

Jan 1, 2017

By A. F. Jolly

In an effort to better predict the useful service life of friction rock stabilizer mine roof bolts in coal mine environments, the Bureau of Mines has evaluated the corrosion resistance of stabilizer steels in air-saturated and deaerated waters from seven Eastern and Midwestern underground coal mines. Accelerated electrochemical corrosion tests were used to estimate corrosion rates for the two high-strength, low-alloy (HSLA) steels used to fabricate Split Set stabilizers and for galvanized steel. Long-term static-immersion weight-loss tests were also conducted with the HSLA steels. Corrosion rates developed from the weight-loss tests (steady-state air dissolution) were roughly comparable to rates determined from electro-chemical testing in aerated waters. Although the highest rates occurred in waters with the highest chloride contents, rates in the other waters were low (<2.0 mpy) and exhibited little correlation to the widely varied chloride contents of the waters. The generally low corrosion rates are attributed in part to the tendency to deposit a protective CaC03 film, reflecting susceptibility to carbonate precipitation as indicated by positive Langelier (saturation) index values for the waters. With one exception, corrosion rates for the galvanized steel were (2.0 mpy. Rates with aerated waters were higher than those with deaerated waters. Pitting tendencies of the steels were also estimated.

Jan 1, 1987

By D. de Fontaine

A convolution procedure is described for obtaining an analytical expression for the composition profiles of solute concentration:; in binary solid solutions. The free energy of solutions containing such compositional inhomogeneities can then be evaluated and the stability of spherically symmetric clusters (G.P. zones, for short) us a function of their radii and central compositions can be studied accordingly. Two characteristic zone radii are defined: the minimum radius (RM) corresponding to the smallest zone for which growth is energetically favored over dissolution, and the critical radius RK) corresponding to zones associated with the minimum work of formation. The values of RM and RK coincide at the two classical limits of nucleation and growth and spinodal decomposition. As the spinodal is approached, however, RM and RK diverge increasingly and it is proposed that the initial] decomposition morphology is governed more closely by the minimum, rather than by the critical radius since the former possesses no singularity within the m eta stable phase boundary. Reversion is briefly discussed in the light of the foregoing and it is shown that a set of reversion temperatures located between the coherent miscibility gap and the coherent spinodal must correspond to a given distribution of low temperature zones. SINCE the early works of Guinier1 and preston,2 the kinetics and morphology of GP zones have been studied extensively, see Ref. 3, for example, for a recent review. Nevertheless, a completely satisfying theoretical treatment of the decomposition of meta-stable or unstable binary solid solutions is still lacking due to the almost unsurmountable mathematical difficulties that one encounters in attempting to solve the pertinent diffusion equation which, in principle, describes the whole process. This equation, first derived by Cahn for the initial stages of spinodal decomposition,4 is a nonlinear partial differential equation of the fourth order in anisotropic space, a general analytical solution of which is completely out of the question. From this equation, some prediction can be made, however, concerning the later stages of spinodal decomposition5 and a recent numerical solution6 of the equation in the case of one- and two-dimensional composition modulations of a solid solution inside the spinodal has led to the following considerations: the sinusoidal morphology7 is to be expected only for solutions of average composition c, located near the center of the coherent miscibility gap.8 For solutions with co closer to the spinodal decomposition, depleted shell zones9 should constitute the first recognizable decomposition product, later evolving to iso- lated, enriched preprecipitates in a uniformly depleted matrix as this must, in all cases, constitute the final metastable morphology, barring, of course, loss of coherency and change in crystal structure. In agreement with the qualitative description of Bonfiglioli and Guinier,l0 it thus appears that the various models discussed by previous authors are, in fact, idealized successive stages of the general decomposition process. Unfortunately, corresponding calculations for a solid solution outside the spinodal are not yet available because of two additional difficulties: it is essential that the diffusion equation be solved in three-dimensional space, and furthermore, one must include in the equation an appropriate "source term" describing the statistics of the creation of composition fluctuations required to trigger the nucleation events. At present, a general treatment of this problem does not appear to be tractable. Nevertheless, by using a modelistic approach, i.e., by selecting a priori certain composition variation profiles and by evaluating their associated free energies, one can draw certain conclusions relative to the stability of these isolated composition modulations or "zones", both outside and inside the spinodal. This is the object of the present investigation. THEORY We shall now describe a standard four-parameter spherically symmetric GP zone, evaluate its free energy according to the Cahn and Hilliard11 formula (Eq. [5], below), and plot the corresponding energy surfaces as a function of zone amplitude and radius as

Jan 1, 1970

By A. Rosen, P. Wynblatt, J. E. Dorn

The temperature, strain rate, and structure dependence of the flow stress in a poly crystalline Fe-2 pct Mn alloy was investigated between 77" and 370°K. It was possible to identify the low-temperature data from 77° to 160°K with Dorn and Rajnak&apos;s theory of the Peierls mechanism of plastic deformation. Above 160°K one or more thermally activated mechanisms must he operative; however, these were not identified in this investigation. The mechanistic basis for the rapid decrease in the flow stress of bcc metals with an increase in temperature over the low-temperature range is yet being debated. Various dislocation mechanisms have been suggested in the past but the agreement between the various proposed theories and the experimental results have not been definitive. In the present paper, the authors will demonstrate that the plastic behavior of polycrystalline iron containing 2 wt pct Mn plus interstitials agrees excellently with predictions based on the Peierls mechanism from 77" to 160°K whereas from 160" to about 370°K other as yet unidentified thermally activated mechanisms take over. Undoubtedly, the overlap of these mechanisms with the Peierls mechanism contributed to the difficulties of rationalizing the low-temperature behavior of iron and its alloys. I) EXPERIMENTAL TECHNIQUES AND RESULTS Although extensive data are now available on the effect of temperature and strain rate on the flow stress of various bcc metals and alloys, it was, nevertheless, deemed necessary for the objectives of the present study to obtain highly accurate data of the type most pertinent for checking the theories on a series of well-documented work-hardened states. Iron containing 2 wt pct Mn was used in this investigation in order to obtain a lower ductile to brittle transition temperature than that for iron.&apos; The additional elements present were 0.004 pct C, 0.05 pct 0, 0.004 pct S, 0.003 pct P, 0.006 pct N, and 0.001 pct Si. The as-received 3/8 by 3/4 in. bars were cold-rolled to 0.100-in. thickness, recrystallized under argon for 30 min at 1073"~, further cold-rolled to 0.063-in. thickness, and finally recrystallized under argon for 30 min at 1000°K. This treatment gave a stable reproducible equiaxed grain structure having an average grain diameter of about 90 p. Prior to the final recrystallization treatment, the sheet was machined into tensile specimens 1/4 in. wide having a 1.625-in.-long gage section. All specimens were tested in controlled-temperature baths on an Instron Testing Machine. For convenience in the theoretical analyses the data will be given in terms of the shear stress for flow, 7, the shear strain rate, f, and the shear strain, y. A series of three standard strain-hardened states were obtained by prestraining specimens at 300°K and at a shear strain rate of 7.68 x lo-&apos; per sec to three stress levels of 6.89 X l08, 10.3 X lo8, and 14.5 x 10&apos; dynes per sq cm, respectively. Immediately following this prestrain the temperature bath was changed and each specimen was pulled in tension at either f = 7.68 X lo-&apos; or f = 3.06 X 10"3 per sec. In terms of the accuracy that was achieved, the values obtained did not deviate more than *0.1 X 10&apos; dynes per sq cm and * 1°K from the reported values of stress and temperature and not more than *5 pct in the reported values of the strain rate. The tensile stresses were converted to shear stresses using a factor of 1/2. The shear stress for the initiation of flow at the test temperature was determined by taking a y = 6.16 x 10&apos;3 offset. from the modulus line at which point good accuracy could be achieved in determining y and the associated flow stress 7, with only a negligible increase in the pre-

Jan 1, 1965

By J. S. Fox

It is generally recognized that the interpretation of bedrock geochemical data in volcanic terrains can be improved by adjusting for rock-type. Various chemical attributes of volcanic rocks have been put forward in the literature as rapid indicators of rock-type, but there is some question as to which of these is the most reliable . Only one such attribute, total iron, seems to have seen systematic use in geochemical mapping in the Flin Flon region. Discriminant analysis of 500 basalts, andesites, dacites and rhyolites suggests that SiO2 is the most important rock-discriminating variable and that MgO, CaO, TiD2, AI2O3 and FeOtot, are successively poorer discriminators. Lithological normalization in the subalkaline volcanic environment should therefore be made over ranges of this variable. Trace-metal data from drill core through the sulphide orebody at Hanson Lake, Saskatchewan are used to demonstrate various approaches to lithological correction, including silica normalization, factor analysis and trend analysis. All of these extract economically important information from the core that is not apparent in the raw data logs. However, silica normalization does not seem to be subject to as many serious limitations as factor and trend analysis in this case, and therefore seems to provide the most reliable basis for the interpretation of subsurface exploration geochemical data.

Jan 1, 1978

By J. D. Bennett

The degree of injury and days lost from work due to an injury are examined for selected electrical sources, occurring in conjunction with falls of the injured miner or with selected machinery, that could have been eliminated by use of diesel equipment. Although the number of electrical source injuries that could have been prevented is small relative to the total number of injuries during the period examined, many lost-time injuries could have been precluded and thousands of days lost from work could have been avoided.

Jan 1, 1984

By R. W. Raymond

(Cleveland Meeting, October, 1912.) UNDER the names of Conservation, Social Justice, the New Nationalism, and Progressive Democracy, many earnest reformers are calling for a new system of Federal government to replace the one which they ascribe to our fathers, and declare to have been outgrown. They are proposing the lease by the United States of certain natural resources on the public domain, for the profit of the U. S. Treasury, instead of the sale of such resources to private citizens or associations of citizens. In the present paper, I shall try to show that this notion is neither new nor good. It is clear that the United States is owner, as well as sovereign, of public lands acquired through conquest or purchase from other nations, as it was owner of the public lands expressly ceded to it by the original thirteen States. Its policy with regard to such lands involves, therefore, two entirely distinct questions: What shall it do as owner ? and, What shall it do as sovereign ? The latter question, it must be confessed, has played but a small part in our history. All the prerogatives of sovereignty which were not explicitly conferred upon the Federal government by the original States were retained by them. The ownership or control of precious or other metals or minerals in the earth, for instance, was thus reserved to the several sovereign States. New York, South Carolina, and other States have passed laws on this subject, without regard to Federal authority. As new States have been successively admitted to the Union, the tacitly accepted theory has been,. that they thereby acquired all the reserved rights of the original States. These newer States largely outnumber the first. thirteen; and it is inconceivable that they would submit to any deprivation of sovereignty based on historical grounds. One of them-Texas-came into the Union by its own voluntary

Oct 1, 1912