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By E. L. Affleck, W. G. Stevenson

In both Canada and the United States, a company making a public offering of securities must comply with regulations which have been passed by Federal, State and/or Provincial Legislatures. These regulations usually require the distribution of an acceptable prospectus which provides essential background information about the issuer, the project and the share offering. when the public offering has been accepted, the unlisted company may then seek a listing of its shares for trading on a Stock Exchange. Once listed, the company will be subject to rules of the Stock Exchange. This paper will deal with the specific information required for inclusion into a prospectus being submitted for a resource company and particularly those parts of concern to mining engineers and geologists.

Jan 1, 1985

By Frederick G. Coqueron, Joseph E. Pogue

The purpose of this study is to present the results of a detailed survey of the financial and operating aspects of 30 oil companies comprising a major sample of the American petroleum industry. This review supplements a previous paper entitled "Capital Flow and Capital Formation in the Petroleum Industry, 1934-1941,"a and deals not only with a longer period but also gives new and more revealing analyses of the capital movements and characteristics. The data are gathered from published financial statements of the companies, especially the annual reports to stockholders and Form 10-K to the Securities and Exchange Commission, supplemented by confidential information. The 30 oil companies covered by this study are listed on the leading stock exchanges and for the purpose of analysis are grouped as follows: 9 companiesb engaged principally in crude production, 4 companiesc with production averaging in excess of refinery requirements, and 17 companiesd with refinery throughput in excess of crude production. These samples are sufficiently broad and representative to constitute norms against which individual company performances may be profitably compared. The 30 companies in 1942 produced 54 per cent of the Nation's total output of crude oil and refined 79 per cent of the country's crude run to stills. The financial data apply predominantly to the domestic oil business, although 15 of the companies have investments and operate facilities in foreign countries. The net value of these foreign holdings amounted to 724 million dollars, or 12 per cent, of the combined net assets of the 30 oil companies at December 31, 1942.

Jan 1, 1944

By K. D. Jacob, H. L. Marshall, D. S. Reynolds

All types of commercial phosphate rock produced throughout the world contain fluorine in quantities ranging from approximately 0.4 to 1.3 per cent in the Curacao and Christmas Island phosphates to 3.1 to 4.2 per cent in the phosphates of the United States and North Africa1. For a given type of rock, the fluorine content is usually roughly proportional to the phosphorus content. Significance of Fluorine in Phosphate Rock On the basis of chemical and X-ray diffraction studies, Hendricks and co-workers2 concluded that fluorapatite, Cal10F2(PO4)6, is the essential phosphatic constituent of the commercial types of domestic phosphate rock. On the other hand, Bredig and co-workers3 have recently advanced the opinion, also based on X-ray diffraction studies, that the mineral phosphates usually contain carbon dioxide in the apatite lattice, and that the phosphate rocks of the United States are really fluorcarbonate apatites. However, the domestic types of phosphate rock do not seem to differ greatly from coarsely crystalline fluorapatite in their behavior toward chemical reagents in general, and for the purpose of this paper it will suffice to consider fluorapatite as being the essential phosphatic constituent of these types of rock. The available data1 indicate that the different commercial types of domestic phosphate rock usually contain about 12 to 52 per cent more fluorine than theoretically is required to form fluorapatite with all the phosphorus. Calcium fluoride (fluorite) has been definitely identified in only a very few of the samples that have been examined1,2. Bredig and co-workers4 state that fluorapatite can take into its crystal lattice excess calcium fluoride to the extent of approximately 70 per cent of that theoretically required by the formula Ca10F²(PO4)6 without causing more

Jan 1, 1938

By D. S. Reynolds, K. D. Jacob, H. L. Marshall

All types of commercial phosphate rock produced throughout the world contain fluorine in quantities ranging from approximately 0.4 to 1.3 per cent in the Curacao and Christmas Island phosphates to 3.1 to 4.2 per cent in the phosphates of the United States and North Africa1. For a given type of rock, the fluorine content is usually roughly proportional to the phosphorus content. Significance of Fluorine in Phosphate Rock On the basis of chemical and X-ray diffraction studies, Hendricks and co-workers2 concluded that fluorapatite, Cal10F2(PO4)6, is the essential phosphatic constituent of the commercial types of domestic phosphate rock. On the other hand, Bredig and co-workers3 have recently advanced the opinion, also based on X-ray diffraction studies, that the mineral phosphates usually contain carbon dioxide in the apatite lattice, and that the phosphate rocks of the United States are really fluorcarbonate apatites. However, the domestic types of phosphate rock do not seem to differ greatly from coarsely crystalline fluorapatite in their behavior toward chemical reagents in general, and for the purpose of this paper it will suffice to consider fluorapatite as being the essential phosphatic constituent of these types of rock. The available data1 indicate that the different commercial types of domestic phosphate rock usually contain about 12 to 52 per cent more fluorine than theoretically is required to form fluorapatite with all the phosphorus. Calcium fluoride (fluorite) has been definitely identified in only a very few of the samples that have been examined1,2. Bredig and co-workers4 state that fluorapatite can take into its crystal lattice excess calcium fluoride to the extent of approximately 70 per cent of that theoretically required by the formula Ca10F²(PO4)6 without causing more

Jan 1, 1938

By John D. Meahin

THE use of digital methods for generating crystallo-graphic data is well-established and many programs are now available. Transmission electron microscopy usually requires a knowledge of the electron diffraction pattern which is obtained by plotting a planar section through reciprocal space. With cubic symmetry these sections are very easily produced, but with hexagonal and lower symmetry systems considerably more labor is involved. Johari and Buchanan1 have written a Fortran program for generating standard projections and along similar lines we have produced a short but completely general program for generating any section through reciprocal space. The required inputs are the lattice parameters and angles for the real crystal. The Miller indices of the direction [U, V, W] parallel to the electron beam are then specified and the program will generate the Miller indices of the plane normals perpendicular to [U, V,, W] up to some specified integer. A subroutine can be inserted to test for forbidden reflections if desired. We have used such routines for fct and hcp crystals. As each permitted index is generated it is printed or punched out and no storage arrays are utilized in the computer. The normal diffraction pattern corresponds to the zero-order Laue zone, but with thin crystals or crystals of large lattice parameters the higher-order Laue zones may contribute to the diffraction pattern. Accordingly the program will generate successive Laue zones and project them onto the zero-order zone. The output of the program first lists the zone axis [C, V, W] and the Laue zone, and then gives a list of permitted reflections and the corresponding XP and YP coordinates of the reciprocal lattice point in angstroms-'. In addition, ZP, the perpendicular distance of the reciprocal lattice point from the (U, V, Ur) plane in reciprocal space is given, as is the reciprocal interplanar spacing. In the case of the zero-order Laue zone ZP is zero. A diffraction spot from the higher-order Laue zones will be very slightly displaced from the computed coordinates as its position in an actual pattern is given by projection along the diffracted beam2 and not along [u, V, w]. For any given electron wavelength this correction could be readily incorporated into the program, but as it only amounts to -1 pct it was decided to leave the program in its most general form, i.e ., a computation of points

Jan 1, 1970

By Frank C. Kelton

It is perhaps not widely realized that extraction and saturation processes carried out on oil well core samples alter the properties of these samples to varying degrees. On the other hand it is felt by some that quick-freezing of core samples increases their permeability and porosity significantly. Accordingly, laboratory tests were carried out on 49 pairs of horizontally adjacent samples in order to differentiate between the effect of quick-freezing per se on permeability and porosity of the samples, as distinguished from the effect of the identical saturation treatment on permeability and porosity of the companion samples. Also, additional field data were obtained on comparison of frozen vs unfrozen companion samples. LABORATORY INVESTIGATION OF FREEZING us SATURATION EFFECTS Procedure The samples used in these tests were two-cm cubes cut in horizontally adjacent pairs from cores from eight Gulf Coast and Mid-Continent wells, which cores had not previously been frozen. These samples were extracted with carbon tetrachloride, dried, and air permeabilities run in the conventional manner. They were then evacuated and saturated with brine of 25,000 ppm sodium chloride content, and porosities determined by gain in weight. The samples were partially desaturated by evaporation down to an average brine saturation of 68 per cent. One sample from each pair was quick-frozen by covering with dry ice after wrapping in a single layer of paper, and allowed to remain frozen for about two hours; the companion sample from each pair was not frozen. After thawing the frozen sample, all samples were immersed in tap water overnight in order to leach out most of the brine. Air permeabilities were re-run, and the samples were again saturated with brine to determine a second porosity value. For purposes of averaging of data, the samples were grouped according to four permeability ranges, from 0 to 10, 10 to 100, 100 to 1,000, and 1,000 to 3,840 md. Average permeability and porosity changes for the frozen vs the unfrozen adjacent samples are shown in Table 1. Discussion As may be seen from Table 1, the averages of the per cent permeability increases for the quick-frozen samples ranged from 3.8 to 12.9 per cent among the four permeability groups. The average changes among the four groups of unfrozen companion samples ranged from a decrease of 0.2 per cent to an increase of 9.3 per cent. There was no particular correlation of these changes with magnitude of permeability; however, the increase for each group of frozen samples paralleled the increase for the corresponding unfrozen samples. The differences between the two sets of values are believed to be a valid indication of the effect of the quick-freezing in itself, since the treatment of the two samples in each pair was identical except for freezing. The permeability changes which are strictly the result of the quick-freezing are shown in the sixth column of Table 1. These range from a decrease of 0.9 per cent to an increase of 4.0 per cent; the overall weighted average is 1.2 per cent, as compared to an average increase of 6.8 per cent caused by the saturation treatment of the samples not frozen. The average porosity changes are in general smaller than the changes in permeability, and range from a decrease of 2.3 per cent to an increase of 3.3 per cent. The overall weighted average change ascribed to the quick-freezing is 1.0 per cent of porosity. Many factors can contribute to the changes in permeability and porosity observed when subjecting cores to the simple processes used in these tests. Such are: hydration and swelling of clay, adsorption of ions, changes in surface structure and wettability, expansion and compression effects due to ice formation, shrinking and cracking, leaching of salts and colloids, displacement of particles resulting in either blocking or enlarging of pore openings. Whatever particular mechanisms are involved. however, it is apparent not only from this study but also from other investigations in the literature' not directly concerned with quick-freezing, that the effects produced by commonly used extraction, saturation and drying techniques may be of considerable magnitude The results of this study indicate that for the particular samples and techniques used, such effects are of the order of five to six times the effect of quick-freezing. insofar as changes in permeability are concerned. It may be argued that these samples might not include extremely shaly material where the effect of freezing upon permeability may be much greater. However, had such material been available for these tests, it would undoubtedly have been very susceptible also to alteration by the extraction and saturation treatment used. To investigate this point further, the individual sample data were re-grouped according to the magnitude of the average per cent permeability increases for the pairs of samples, irrespective of permeability. The results

Jan 1, 1953

By Y. C. Liu, W. R. Hibbard

An aluminum single crystal cold-rolled from (110) [1121 essentially retains its initial orientation after 99.6 pct reduction in thickness. The orientation of the recrys-tallized grains of this material can be described in terms of crystallographic rotations about principal poles of deformation texture. DURING the study of the recrystallization of a copper single crystal cold-rolled from a (110) [112] initial orientation, the orientation of the re-crystallized grains could be derived by a 30" rotation of the orientation of the cold-rolled matrix about its <111> poles.&apos; The present investigation was undertaken to extend the work done on copper&apos; to an aluminum crystal also cold-rolled from a (110) [112] initial orientation. Experimental Procedure The procedure of this experiment was similar to that reported for copper.&apos; An aluminum (99.998 pct) single crystal rod* 1 % in. in diameter was grown in back-reflection technique.&apos; The specimen (1.20x 1.004x0.6787 in. thick) was then rolled along the [112] direction. The final thickness was 0.0028 in., giving a reduction in thickness of about 99.6 pet. Specimens were cut from the rolled strip with scissors, and approximately in. of disturbed metal was removed with Tucker&apos;s reagent. The rolling edge remained intact. The specimens were sandwiched between two graphite plates and annealed in a lead or lead alloy bath which was electrically heated. Pole figures were constructed using the techniques previously described.&apos; Specimens were electrolytically polished4 and etched with 47 pct HNO8, 50 pct HC1, and 3 pct of 48 pct HF. The electrolytic polishing method and etching reagent employed for aluminum specimens were not entirely satisfactory and the microstruc-tures could not be studied in any detail. Results and Discussion The octahedral pole figure of cold-rolled aluminum strip is plotted in Fig. 1. The <111> poles spread in the transverse direction approximately 8" for the highest intensity areas. The spread in the transverse direction can be related to a rotation about two <110> directions lying in a plane containing the rolling direction and rolling plane normal. The two <110> directions and a scale of rotation for the <111> poles are shown in Fig. 2. The amount of rotation is consistent for three of the four <111> poles, about 35" to 40". The discrepancy for the fourth pole is believed to be due to limitations of the film technique. Alternate inter-

Jan 1, 1956

OF the many categories into which scientific knowledge has been arbitrarily &apos;divided, the one that has proved most. applicable in our attempts to gain an insight into the details of steelmaking processes is physical chemistry. To the young metallurgist who has only recently survived a college course in this subject, the application of its principles to reactions in liquid steel should not be difficult. The many excellent textbooks of physical chemistry provide ample material on the principles of this subject for the student of steelmaking processes. It is the purpose of this chapter to provide a concise review of the principles of physical chemistry that have proved useful in studies of steelmaking and at the same time to present some of the data that are essential to the application of physical chemistry to reactions at high temperatures. Certain parts of physical chemistry require rather formidable mathematics for their complete development, but in the main those applications in which we are here interested can be expressed in fairly simple terms. Many of the equations are logarithmic, and we shall use the symbols In X and log X to represent, respectively the natural and the common logarithm of X. The two are related-by In X = 2.303 log X. Logarithms may, be read from a good slide rule with sufficient accuracy for our purposes. In a few spots a knowledge of the calculus will be helpful. MATTER Innumerable forms of matter may, be recognized, and these may be converted by chemical processes into others, as ore, coke, and air are converted into iron, slag, and gas.. Whenever such a change occurs there is a corresponding change in the amount of energy associated with the matter. The process may require an input of energy, as in the electrolytic production of aluminum, or it may result in an output of energy, as in the combustion of fuel. The basic laws of the conservation of matter and of energy tell us that we cannot change the total amount of matter or the total amour t of energy.. When the fuel pile is used up, we realize that it has simply been converted into other forms of matter; .i.e., ash

Jan 1, 1964

By Dever Ashmead

ANTHRACITE was first mined in the Wyoming Valley and sold as an article of commerce in 1808. As some preparation has always been necessary to make it ready to burn, the preparation of anthracite must date back over a hundred years. Two vital factors have determined to a large extent the degree and method of anthracite preparation. These are, first, the character of the beds worked and the methods by which they were mined and, second, the equipment used and practices followed in the burning of the coal. It is not the intention here to go deeply into these phases of preparation as a paper of no mean length could be prepared on the history of either. Rather, the intention here is to point out the main considerations and to show the influence they have exerted on the preparation of anthracite. MINING METHODS AND THEIR RELATION TO PREPARATION In the beginning f the nineteenth century, the coal beds were virgin with the possible exception of some outcroppings that had been worked, to a slight extent, by the Indians. It is known that the American aborigines had a knowledge of the use of this fuel, because when the Wyoming Valley was purchased from them, in 1754, they mentioned the fact that, by selling the land, they would lose their coal.

Jan 9, 1921

By D. C. Seidel, M. C. Fuerstenau, R. J. Roman

The role of surface charge in soluble salt flotation, which was developed in Part I, is extended to relate the theory to the specific phenomena of KCI-NaC1 separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed. The initial paper in this series developed and presented the hypothesis that one of the mechanisms of soluble salt flotation may involve electrical attraction between the collector and mineral surface. This hypothesis was developed from a combination of experimental data and free energy calculations, and details of the logic are presented in this first paper.* The studies have indicated that KC1 has a positive surface charge and NaCl a negative charge. KC1 can therefore be floated with sulfonate ion (RSO;) or with an aqueous polar species such as the aqueous amine chloride, RNH3C1(,,). The chloride end of the RNH3C1(,,) molecular dipole is probably negative and will be attracted to the positive surface of the KC1 particles and absorb (actually probably fit into a vacant chloride site) on the mineral surface. The amine end of the collector molecule would extend into the solution phase and provide the air avid surface required for flotation. NaCl particles are floated by such collectors as aqueous molecules of fatty acid salt, RCOONa(,,), in which the positive inorganic end of the dipole is attracted to the negatively charged surface of the NaCl and, in this case, adsorb and probably fit into a vacant sodium site on the surface. The aminium cation, RNH~, should also be a collector for NaC1. For certain collectors, actual precipitates of the collector must be formed before a sufficient amount of the polar aqueous molecule is present to effect flotation. In a system of this type there is a three-way equilibrium between: Aqeous Molecular Solid Precipitate - A of the Collector (Not Dissociated) . Ionic Species (Dissociated). The controlling equilibrium is probably between the precipitated form of the reagent and the aqueous

Jan 1, 1969

By J. E. JR. Johnson

AT the Cleveland meeting of the Institute in October, 1912, I had the honor to present a paper outlining the conditions surrounding the charcoal iron industry, and giving some of the results of an investigation started about three years ago for the purpose of determining the reason for the poor reputation of the Lake Superior charcoal irons as compared with the Southern and Eastern irons. In that paper I explained the effect of high carbon on quality, and tried to make clear that that paper was a preliminary one, as we felt convinced that we should eventually discover other factors affecting quality. The progress of the investigation has brought out facts that seem to us of the utmost importance practically and theoretically, and the purpose of the present paper is to present these facts with the proofs which seem to us to establish them. The closing year of the nineteenth century saw the publication of the first definite and connected statement of the relationship between the cast irons and the steels.&apos; The metallurgical world was ready to accept the fundamental unity of these two series, acceptance being greatly hastened by Professor Howe&apos;s classic paper, The Constitution of Cast Iron, presented at the Richmond meeting of the Institute, February, 1901.

Jan 1, 1914

By T. Reed Scollon

With some uncertainty as to the type, rate and scope of adoption of air pollution control regulations, and with limited information on the availability of low-sulfur fuels, it is possible at best to make only a rough assessment of the impact of such regulations on coal. It is apparent from the following discussion that regulations of the type already effective or being considered, if adopted and enforced on a widespread basis over a short-term period and if substitute fuels were available, both quantitatively and economically, could result in a loss of more than one-half of coal&apos;s markets. Depending on the areal sequence of adoption of such regulations, some areas would be able to obtain limited amounts of low-sulfur coals. Others would not. Because of the usually greater distances from the large industrial coal consuming areas to new sources of coal supply, and because of the higher mine prices for low-sulfur coals, the delivered prices of such coals as might be available would be much higher than those for high-sulfur coals. A large and sudden demand for low-sulfur coals would exert further upward pressure on prices.

Jan 1, 1970

By G. Sachs, E. J. Ripling, J. J. Lynch

INTRODUCTION General IT is general practice to evaluate the strength properties of a particular metal from its stress-strain [(S1 - E1]) curve obtained by means of a conventional tension test. Such a stress-strain curve, Fig I, illustrates two important properties of a metal, its ability to strain harden, and its ability to withstand a certain limiting stress, the "fracture stress,"[ (s&apos;r)], and a certain limiting strain, the "ductility" [(e1)], before it fails by separation. These two fracturing characteristics are the coordinates of the point of fracture in Fig I. In the case of a metal which necks in a tension test, both the fracture stress and the ductility (measured in a tension test) are dependent upon (a) the shape of the neck and (b) average values of the stresses and strains over the cross section at the moment of fracture. However, for the purpose of this investigation, these average quantities, rather than the actual values, may be considered for reasons of simplicity. It appears that the conclusions also hold true if the analysis were carried out for actual values of fracture stress and ductility at the locus of failure. In this paper, the effects of straining (at room temperature) by various methods on [ ] the above metal characteristics, which were determined by subsequent tension tests will be discussed. According to our present knowledge, any such prestraining results in a stress-strain curve (in subsequent testing by tension), Fig 2, the general shape, or flow characteristics, of which can be derived from the original stress-strain curve of the unstrained metal minus a certain portion exhausted by the initial straining. This phenomenon is called strain hardening, and may be measured by the magnitude of the cut-off, or the "effective strain," from which the new curve must start in order to coincide in its plastic branch with the original stress-strain curve.

Jan 1, 1948

By George S. Rice

The extremely valuable papers and discussions on coal-cluat explosions by Bache,&apos; Eavenson, Shurick, Mannakee,* and Raymond are of unusual interest to me, since it has been my duty to carry on investigations on this and allied subjects for the Technologic Branch of the United States Geological Survey during the past year, and to make a series of coal-dust tests in the explosion-gallery at Pittsburg during a short periocl when its use could be diverted from the pressing work of testing explosives. In several of the discussions mentioned, it has been assumecl that the Technologic Branch of the Survey mas not paying attention to certain phases of the general problem, or to the specific question of temperature and humidity of mine-air in its effect upon the explosibility of coal-dust. This assumption is not correct, since from the time of the establishment of the " Mine-Accident Division," with its subdivisions of explosives, rescue-work, and mine-investigation, the mining engineer.; of the last-named section have made the subject one of chief consideration. Their general duties, including mine-sampling for governmeilt purposes, emergency-calls for rescue-work, and esplosion investigations, have prevented undivided attention, but all of them have been supplied with instruments for such determinations, and special report-forms have been in use and a great many observations made in mining-districts to which the mining engineers have gone. With the idea of obtaining a uniform system of reporting these data, and in the hope that the work may be of service to mining engineers in the field, the collecting blanks in use are shown in Forrns 1 and 2.

Jan 1, 1911

By W. M. Weigel

The general term "sand" applies to a multitude of similar materials consisting of fine granular mineral. As usually understood, it means the ordinary natural product used for structural purposes and made up largely of grains of quartz. Quartz sand constitutes by far the greater bulk of the production, but there are other grades used for industrial purposes, such as molding sand, glass sand and many others, that may be grouped under the general name of special sands. Under this general group would fall filter sand, sand-blast sand, engine sand, potter&apos;s sand, abrasive sands of all kinds, sand for pulverizing, roofing sand, flooring sand, fire or furnace sand, standard sand, burnishing sand, sand for magnesium oxychloride cement-plasters and sand for chemical and metallurgical purposes. Sources of Supply Sand is a widely distributed natural product and even the better grades are low-priced commodities. For these reasons development has occurred near points of consumption where sand meeting the requirements is available. Some special grades, however, cannot be prepared from any sand bed and shipments are often made over considerable distances when the only developed deposit is remote from the consuming center. This is true of filter sand, sand-blast sand, sand for pulverizing and some of the others when chemical purity or grain size, coupled with the need of a properly equipped plant for preparation, are required. New Jersey is a large producer of filter, engine, sand-blast, fire, and pulverizing sand. Pennsylvania, and West Virginia produce special sands for pulverizing, fire sand, abrasive sand, engine sand and sand for chemical and metallurgical use. Ohio produces much sand-blast, fire and abrasive sand, and some filter sand. Illinois and Minnesota produce

Jan 1, 1926

By Strathmore R. B. Cooke, Paul B. Queneau

The kinetics of the dissolution of scheelite in basic solutions of carbonate and fluoride were investigated. Work was also done with solutions of alkali metal chloride, hydroxide, phosphate, and mixtures of phosphate and fluoride. The study was conducted at 90 psig and at temperatures ranging from 100" to 155"C, and both natural and synthetic scheelite single crystals were used. The interaction of scheelite with carbonate solutions generally followed a parabolic rate law, and resulted in the formation of calcite crystals on the attached surface. The transport of the CO3 through the calcite to the scheelite surface was probably rate -controlling between 115" and 135°C. Positive deviations from Parabolic behavior were observed at 100" and 155?C, presumably due to the calcite grain growth, and to the formation of a noncoherent calcite layer, respectively. The leaching of scheelite with alkaline fluoride solution produced a calcium fluoride reaction-product which covered the surface as a sheet-like layer. Below 110°C the dissolution rate was parabolic; at 115" and 135°C it was linear. In the linear region, the periphery of the calcium fluoride layer lifted from the sample. Only the lower layers, braced by the scheelite substratum, remained unbroken. This bound layer, approximately constant in thickness, limited the rate at which the fluoride could attack the scheelite. The phosphate and phosphate-fluoride leaches dissolved scheelite at a linear rate; solid reaction products were respectively hydroxyapatite and fluorapatite. Sodium hydroxide and chloride were not effective leachants, and did not produce observable solid reaction products. THE feasibility of pressure leaching of scheelite pulps with basic solutions containing either carbonate or fluoride ions, as indicated by the following equations, has been established by previous investigators:1-3 200°C CaWO4s + CO37q - CaCO3s+WO4aq [1] 200°C CaWO4s + 2Faq ^ CaF2s+WO4aq [2] It is to be noted that a commercial process employing reaction [I] is in use at Union Carbide&apos;s operation near Bishop, Calif. In the earlier work referred to, it was apparent that the precipitation of the solid reaction-product on the scheelite particles sharply reduced contact of the leachant with the scheelite. We have extended this work by studying the kinetics of dissolution employing single crystals of scheelite of known exposed surface area. In addition, the effectiveness of solutions of phosphate, of phosphate with fluoride, and of chloride and hydroxide as leachants for scheelite have been investigated. EXPERIMENTAL Apparatus. The low-pressure autoclave used in this wo (100 psig maximum) is essentially that of J. Halpern4 as modified by F. A. Forward.5 Constructed entirely of 316 stainless steel, its maximum capacity is 4000 ml. The temperature in the autoclave was regulated to *0.5?C by a Wheelco thermocouple controller. A 4-in. diam, three-bladed impeller, circulated solution upward against the sample, and a strobo-scope permitted holding the stirring rate to *15 rpm. A check valve and a "pop" type safety valve were installed, a sample holder was fixed to an externally adjustable rod, and a water-cooled condenser was placed in series with the sampling valve. The stainless steel sample holder, Fig. 1, held the epoxy-mounted sample (f) five mm above the impeller. Tightening the tapered sleeve (d) positioned the epoxy-resin specimen-mount by forcing it back against the spacer (c). The mount (e) was 1 in. diam. Sample Description and Preparation. Both synthetic and natural scheelite crystals were leached. The former were single crystals of 99.95 pct purity which were leached approximately perpendicular to the "c" axis; they were supplied by the Gallard-Schlesinger Chemical Manufacturing Corp. The natural crystals, supplied by Minerals Unlimited, were transparent, analyzed 99.8 pct CaWO4, and in ultraviolet illumination exhibited the characteristic blue glow of substantially molybdenum-free scheelite. To permit exposure of an essentially constant surface area of scheelite to the leachant, the samples were mounted in Scotchcast Brand Resin No. 250 (Minnesota Mining and Manufacturing Co.). The mount-

Jan 1, 1970

By William Schriever

The flow of a gas-free liquid through a spherical-grain sand has been investigated by S1ichter.l By theoretical considerations involving a rather large number of approximations he arrives at the following flow-formula: V = CPd2At NLB{1 - m) where V is the volume of liquid delivered in time t through a cylindrical column of sand of length L and cross-sectional area A by a pressure-drop P when the sand grains of diameter d are packed to a porosity m and the coefficient of viscosity of the liquid is n. C and B are constants which were determined from geometrical relations; B was in reality a function of . Values of B(l — m) for various values of m were given in a table. In the same Annual Report of the U. S. Geological Survey, King reported the results of his experiments on the flow of water through porous media. He found that there was a departure of about 86 per cent. from a linear relationship between rate of flow and pressure, for a specimen of Dunnville sandstone for pressure drops not exceeding 60 cm. of mercury. The specimen was approximately 4 cm. in diameter and 5.1 cm. in length. Over the same range of pressure he found a departure of 45 per cent. for a specimen of Madison sandstone. For unconsolidated sands he found departures as great as 49 per cent. for pressure drops of 70 cm. of mercury; for pressure drops not exceeding a few inches of water he obtained a close approximation to a linear relation. He also investi-

Jan 1, 1930

By Stanley L. Lopata, Eric B. Kula

The problem of preferred orientation has been considered in quantitative phase analysis by X-ray diffraction techniques. The average intensity of a diffraction peak can be obtained by integration over the whole pole figure, or by random rotation of the specimen in the X-ray beam, or by a combination of both. For rod or wire, where the pole figure shows rotational symmetry, the intensity is measured along a radius of the pole figure. Where no symmetry is present, rotational symmetry is imparted by rapid rotation of the sheet around its surface normal during measurement. These methods are applied to the determination of aus-tenite in an Fe-31 pct Ni rod and Fe-28 pct Ni sheet. X-RAY diffraction techniques are frequently used for quantitatively determining the relative amounts of two or more phases present in a structure.1,2 Briefly, the method requires a measurement of the intensity of a Bragg reflection for each phase. The method is based on the principle that the intensity of a Bragg reflection, IA, is directly proportional to the volume fraction of the given phase present, CA: T KRACA/2µ [1] where K is a constant independent of the diffracting phase, RA can be calculated and depends on the Bragg angle ? and the particular reflection measured, and µ is the linear absorption coefficient of the mixture.&apos; For a mixture of two phases A and B, IA = RAcA [2] IA/IB=RAcA/Rbcb and CA+ CB = 1 [3] This allows the volume fraction of a phase to be calculated directly from the measured integrated intensities of the two phases present. This method is frequently used for quantitatively determining retained austenite in steels, but can be used for the quantitative determination of in titanium alloys, as well as phases in other alloy systems. The intensities are generally measured by diffracting only from planes whose normals are perpendicular to the specimen surface, with the implicit assumption being made that this intensity is typical of reflections from planes whose normals lie at other angles to the surface. If the specimen contains a texture or preferred orientation of the crys- tallographic planes by virtue of previous mechanical working, however, this measured intensity is correct only if the intensity level fortuitously is one times random. Examination of pole figures for actual rolled sheet shows that the intensity level at the center of the figure is seldom at the random level, and can very easily differ by a factor of five or more, leading to a commensurate error in the calculated amount of the phases. Textures have been commonly found in materials which are cold-rolled or recrystallized after cold rolling. This problem is becoming of greater importance since structural materials in use today, such as the high-strength stainless steels, frequently are further strengthened by cold rolling, and hence contain textures. Although high-strength carbon-containing alloy steels generally do not contain textures, some of the newer thermomechani-cal treatments will impart a texture even in these cases. In the case of hexagonal metals, such as titanium, probably every wrought sample will show some anisotropy. Since the standard X-ray techniques are inapplicable in all these cases, there is a clear need for some method of taking this anisotropy into account. The specific problem is to obtain the integrated intensity of a Bragg reflection for each phase, averaged over all orientations of the sample with respect to the X-ray beam. This can be done either by purely mechanical means or by a mathematical averaging. Mechanically, a small spherical speci-

Jan 1, 1965

By F. W. Aul, R. C. Glenn

EXTRACTION techniques are of particular importance in determining size, shape an: crystal structure of particles smaller than l000Å in steels and other alloys. However, artifacts that can arise during the preparation of extraction replicas may lead to erroneous conclusions. The purpose of this note is to illustrate some of these artifacts and the misinformation that can result from their presence. An alloy of iron with 0.8 pct Cu was investigated in the following conditions: 1) Solution treated 3 days at 925°C in dry hydrogen and quenched in water. Aged in steps to precipitate copper, as follows: heated to 700°C, held 1 day; then furnace cooled to 50O°C, held 3 days; then furnace cooled to room temperature. 2) Solution treated 3 days at 925OC in dry hydrogen and furnace cooled to room temperature. 3) Solution treated 3 days at 925OC or 17 hr at 1100°C in dry hydrogen to dissolve all copper, then quenched in water. A normal parlodion dry-extraction technique was employed after etching the specimens with super picralP or with 2 pct nital. A wet-extraction method

Jan 1, 1962

By John V. Beall

As Mother Nature arranged it, the hottest potential mineral target in the country today, the Stillwater complex had to occur in a spectacular natural setting-the north margin of the Bear Tooth Mountains of Montana. What more appropriate backdrop for the August 17-18 field hearings of Senator Frank E. Moss (D-Utah). His subcommittee, on Minerals. Materials and Fuels, heard 37 witnesses ponder the value of minerals vs esthetics or other uses of federal lands. On August 17, four Army Hueys swept the senatorial party, the press, Forest Service Officers and such distinguished witnesses as Montana Governor Forrest H. Anderson over the Custer-Gallatin National Forests, besting the thin air of 10,000 ft p1us, they set down on Iron Plateau.

Jan 1, 1971