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By R. B. Taylor

The Esmeralda mine is located about three miles west of the town of Parral, in the State of Chihuahua, Northern Mexico, and about 400 miles south of El Paso, Texas. The area is serviced by the Interamerican Highway and a branch line of the National Railways of Mexico. The Parral district is quite typical of the semidesert of Northern Mexico, lying near the western margin of the Chihuahua basin and range province known in Mexico as the ?Mesa Central? In the immediate mine area, low rounded hills and rolling plans slope toward the Parral River. Surface elevation at the mine is 5,800 feet. The Esmeralda vein outcrops strongly, but was too low grade to be of interest to the Spaniards, The first claims were staked in 1897 and limited exploration work to a depth of 550 feet was carried out prior to 1912, at which time work was suspended. The Eagle-Picher Company acquired the property in 1944 and by surface diamond drilling outlined an orebody to a depth of 800 feet, Minas de Iguala, S. A, de C.V., one of Eagle-Picher?s totally owned subsidiary companies in Mexico, then unwatered the old workings, developed the mine, installed a modern differential flotation plant and started production lage in 1948. To the present, more than two and ahalf million tons of ore have been mined and milled producing lead and zinc concentrates.

Jan 1, 1958

By Walter E. Lewis

The Cuyuna iron range in Crow Wing County, Minn., is the principal producer of manganiferous iron ore in the United States. The ore is mined from a manganiferous iron formation in the bedrock of the Cuyuna district. This iron formation is divided into two general lithologic types-thin-bedded and thick-bedded. The unoxidized, thin-bedded iron formation is composed of iron silicate with associated fine-grained carbonates of iron and manganese. The thick-bedded iron formation carries iron and manganese oxides with intimately associated silica. Oxidation and leaching of the original iron formation have been the most influential factors in producing manganiferous iron-ore concentrations in quantities large enough to exploit on a commercial basis. The unoxidized and the partly oxidized and enriched iron-formation materials are suitable as a source of ferrograde manganese ore. These materials have been classified according to their amenability to mineral dressing and degree of oxidation and leaching.

Jan 1, 1958

By A. Brown

THIS P APER has been pre-pared as a progress report on Mines Branch investigations into problems of ground stress in certain co al mines of Western Canada. As such, it should be considered as a companion report to the one ( 1) presented to the Mining Society of Nova Scotia in 1956 and which dealt with similar investigations in the coal mines of Eastern Canada. For the past 50 years, dynamic incidents in the form of 'bumps' and 'outbursts' have been occurring in the coal mines of the Inner Foot-hills belt of tl1e Canadian Cordillera. As these phenomena generally become more frequent with in-creased thickness of overburden, a limiting depth of mining of 2,500 feet has been set (2) for estimating recoverable reserves of coal. If such a view were accepted, from a long-term viewpoint very large resources of coking-grade ?coal -in a part of the continent deficient in such coals -would not be available to the nation. The terrain in which these in-6dents take place may be described in geological terms as being dominated by pronounced structure in strata ?consisting of a large proportion of highly indurated rocks. The Geological Survey of Canada has co-operated by carrying out structural studies (3) at the mines, supplemented lithological by stratigraphic observations.

Jan 1, 1958

By H. R. Skewes

IN the course of small seale experiments on the electrodeposition, of copper, extremely brittle deposits were obtained from electrolytes prepared by leaching calcined chalcopyrite with aqueous sulfuric acid. It was not possible to strip the metal without fracture after it had been deposited from such electrolytes onto smooth oiled copper sheets, the usual plant procedure for the production of so-called starting sheets. The embrittlement did not occur with electrolytes made either by leaching the calcine with water or by treating an acid leachate to remove iron as hydrous ferric oxide. The electrolytes which produced brittle deposits were found to contain molybdenum in concentrations of 10 to 25 mg per 1, whereas those which produced ductile deposits contained <0.5 mg per 1. Synthetic electrolytes having the composition: Cu", 40 gpl; Fe", 0.5 to 1.0 gpl; Fe3+, 0.5 to 1.0 gpl; and H,SO,, 10 to 50 gpl, were prepared from reagent-grade salts; by adding ammonium molybdate, the embrittling effect of the higher concentrations of molybdenum (VI) was strikingly confirmed. The brittle deposits contained up to 0.03 pct Mo. The importance of oxidation state of the molybdenum was demonstrated when the electrolyte containing it was circulated continuously through a bed of fine copper metal during deposi- tion. Under these reducing conditions, the cathode deposit was ductile and molybdenum could not be detected. Molybdenum has not been recognized as one of the metals causing embrittlement of copper nor is it listed among the usual impurities. In most elec-trowinning plants there is a purification step which removes iron from the leachate before electrolysis. In these cases molybdenum would be coprecipitated with hydrous ferric oxide. In the case of the large leaching plant at Chuquicamata, Chile, where the leachate is reported to contain considerable molybdenum, it would be reduced to a lower oxidation state during removal of chlorine by means of cement copper. This may explain why the embrittling effect of molybdenum has not been reported previously. Moreover, in copper refining plants where soluble anodes have been prepared by a high temperature smelting process, it is most unlikely that any molybdenum would remain with the copper, whereas the calcines in this work were prepared in a fluidized bed reactor at a temperature not exceeding 720°C. Acknowledgment This work is part of an investigation on the roasting and extraction of copper from sulfide ores sponsored jointly by Mt. Morgan Ltd., Queensland, and the Mt. Lyell Mining and Railway Co. Ltd., Tasmania.

Jan 1, 1958

By R. V. Higgins

This report presents the results of a study of water injection in the HX sub-pool fault block V-B, in the Upper Terminal zone, Wilmington field, California, and is based on data obtained to May 1957. An earlier report3/ describes the results of gas injection in part of the field. The principal purpose of the pilot flood was to determine whether a sand having a permeability of 1,200 millidarcys and containing oil having a viscosity of 17 centipoises could be waterflooded effectively. The results of a preliminary study by engineers of the Long Beach Harbor Department of oil recoveries from areas where encroaching edgewater was active and the results of an independent study by a consultant retained by the Long Beach Harbor Department were favorable to a trial waterflood. After these preliminary studies, a detailed petroleum-engineering exam-ination was made of the technical details. As a result, a peripheral flood was started in June 1953. The peripheral flood was deemed desirable because the producing wells are bottomed a short distance from the edgewater. The HX subpool was selected for the pilot test because it is an isolated section of the Upper Terminal zone and is separated from the adjoining pools by faults on the east and west and by edgewater on the north, south, and west. Several petroleum-engineering methods were applied to evaluate the performance of the waterflood, and all showed that injecting water stimulated oil production.

Jan 1, 1958

By Charles Banks Belt

In 1925, Niggli (1925, pp, 1-69), formulated a physico-chemical, explanation for the origin of hydrothermal ore deposits, from a concept that had appeared earlier in the literature in the writings of Von Groddeck, Stelzner, Beck, de Launay, Kemp, and Lindgren. Niggli proposed that pressure at depth could force volatiles from deep-seated magmas. The volatiles would In turn form pegmatites and then ore deposits as the fluids cooled. This is one view of a general theory of ore genesis that gained secondancy for years among such prominent geologists as Fenner (1926, p, 697) and Emmons (1936, pp. 29-70). It was, proposed that ore deposits were precipitated from solutions or fluids that had escaped or been separated from a deep-seated magma by means of liquid immiscibility or crystallization or gas transfer. This theory is based on the presence of igneous rocks close in space and age to hydrothermal ore deposits in many mining districts of the world. As is well known, there are many ore deposits apparently of hydrothermal origin that are neither spatially nor chronologically related to igneous rocks, In still other localities where there are no hydrothermal ore deposits, igneous rocks occur that are similar in composition to those in mining districts. In view of such facts, the applicability of the Niggli theory to all hydrothermal ore deposits may well be questioned. The chief purpose of this paper is to test the Niggli theory by studying the primary petrology, hydrothermal alteration, and distribution of copper and zinc in silicic igneous plutons supposedly genetically related (in the Niggli sense) to nearby hydrothermal ore deposits, Silicic Tertiary plutons in three New Mexico mining districts were chosen, the Hanover-Fierro intrusive at Hanover and Fierro, the Granite Mountain pluton at Magdalena, and the four outliers of the Lordsburg stock at Lordsburg. First, it had to be established whether the observed plutons were or were not the source of the adjacent ore deposits. This was done by studying the relation between the copper or zinc distribution-and the primary or secondary features in the plutons studied, and the time relations between instrusion and ore deposition. Primary igneous features of a pluton are defined as the minerals, texture, shape, and character of the pluton which were formed prior to the complete solidification of the rock, secondary features include all changes that took place in a pluton after solidification. They are identified by their cross cutting nature or as replacing primary minerals, Under the Niggli concept, it is proved that the ore ions did not originate from the parts of the pluton now visible as immediately adjacent to the ore deposits; it must then be established, if possible&apos;, that the ore ions were separated from deeper parts of the intrusive, Some idea as to whether the copper or zinc ions originated from a related magma at depth may be gained by a comparison between the primary (that is, pre-alteration) zinc and copper abundances found in ore localizing intrusive studied and the average abundances for copper and zinc in silicic igneous rocks most recently given in the literature. Finally, the relation between ore deposition and hydrothermal alteration was studied on a regional as well as on a local scale.

Jan 1, 1958

By Frank J. Markewicz

The expanding: demand for ilmenite for use in the manufacture of titanium pigments, the knowledge that much of this raw material comes from distant points and therefore has to include a heavy freight charge in the price of the delivered product, and the further knowledge that ilmenite occurs both in the crystalline rocks of northern New Jersey and also in some of the Triassic igneous rocks, were considerations which led to a search for ilmenite-bearing sands in southern New Jersey. That this search was successful is now history, and it is the senior author&apos;s privilege to state here that most of the credit belongs to his associates who did all of the heavy work of hand-augering for samples, and who made all of the heavy-mineral separations. We all are grateful to members of the Department of Geology at Rutgers and Princeton Universities for the use of equipment which enabled us to evaluate certain samples from our ilmenite exploration program. In addition, we wish to express our appreciation to many companies for their cooperation and for their permission to publish mineral and chemical analyses. We also acknowledge with much appreciation our debt to the geologists and engineers with whom we have had many lively and rewarding discussions relative to the ilmenite deposits.

Jan 1, 1958

By Harold Bloom

Dimethylglyoxime reacts with nickel in a buffered ammonical-citrate solution containing the detergent ?Aquet? and hyroxylamine-hydrochloride. The resulting nickelous dimethylglyoxime is extracted with xylene. Visual comparison with standards permits the estimation of from 50 to 10,000 ppm of nickel. Soil, rock, or sediment may be decomposed by digestion with (1-3) nitric acid, allowing about 70 determinations per man-day to be carried out. With minor modifications to the above procedure, sediment and soil may be semi-quantitatively analyzed for nickel at the sample site. The chemical equipment is easily portable and the analysis extremely rapid because the buffer, dime thylglyoxime and xylene are added simultaneously to the sample and no heating is required. The sensitivity varies with the "availability" of the nickel ions; under favorable conditions, one may obtain a positive test for as little as 10 micrograms in soils and sediments. This procedure is similar to one, for the field determination of heavy metals described elsewhere by the author.

Jan 1, 1958

By D. S. Kingery

The practice of using doors to control main ventilating currents in bituminous-coal mines is common throughout the industry. When doors are erected in pairs to form air locks, they are usually accepted as satisfactory by both State and Federal coal-mine-inspection agencies. A review of the contributing factors in recent methane ignitions showed that interrupted ventilation (often caused by doors latched open, destroyed, or damaged) was the principal cause of methane accumulations that subsequently were ignited.

Jan 1, 1958

By C. R. Nailler

Two recently published papers describing the use of psychological tests for selection and placement of coal mine personnel have created considerable interest within the Coal Industry, one paper, published in the April 1957 "Mining Congress Journal," entitled "Personnel Evaluation and Training," discusses the use of tests by the Christopher Coal Company, The second paper, published in the "West -Virginia Coal Mining Institute&apos;s 1957 Report" and in the September 1957 "Coal Age," entitled "Testing to Select Better Personnel for Coal Mining Today," outlines Hanna Coal Company&apos;s test and selection procedures. Since these rather detailed sources are readily available, and to avoid repetition of the material in them, we will confine this paper to a very brief review of the essential steps already taken by these companies and a more extensive look at newer material. Briefly, the Personnel Managers, Mr. Harold L, Durrett and Mr. Albert M,. Rowe, of the Hanna Coal Company and Christopher Coal Company, in conjunction with Dr. Quin F, Curtis, Head of the Psychology Department of West Virginia University, developed two different groups oftests for coal mine personnel, The first group oftests was designed to assist in the selection of supervisors. These tests of the supervisory group were "The California Short Form Test of Mental Maturity - Advanced Series," which gave an I.Q. rating, and the second test is known as "The Minnesota Multiphasic Personality Inventory," which measures several personality characteristics, These tests must be given, grade, and interpreted by a person trained in psychological testing. As a result of testing all of Christopher&apos;s supervisory employees (seventy in number) by this method, and then comparing the individual results with the individual ratings of the foremen on the job, a so-called foremen&apos;s scale was developed. If this resulting foremen&apos;s scale had been used to select the foremen who were rated as, the best men in on-the-job performance, it would have correctly identified seventy-four percent of that group.

Jan 1, 1958

By J. A. Chamberlain

DURING a recent trip across Canada and parts of the northern United States, the. writer examined some forty mine models. Construction -details and the uses to which the models were being put were outlined in a report to Eldorado Mining and Refining, Limited, and a specific model was proposed on the basis of the Company&apos;s particular needs at their Beaverlodge operation. It was felt, however, that portions of the report would be of some value to anyone contemplating building a mine model. For this reason, a synopsis of some of the more important aspects of the problem is presented here, together with a suggested model type that appears to have wide application. Thanks are due not only to Eldorado for permission to publish the following material, but also to the many mine personnel across Canada who allowed the writer to examine their models and gave freely of their time in discussion.

Jan 1, 1958

By E. M. Baroody

MUCH information on intermetallic diffusion has been obtained in experiments in which two volumes, initially at different uniform concentrations, are maintained in contact at an interface which is plane, or nearly so. Concentration-distance curves are obtained after suitable times, and analyzed on the basis of a one-dimensional form of Fick&apos;s law In early work the linear equation to which Eq. 1 reduces when D is independent of concentration was used. However, when the initial concentrations c, and c, are appreciably different this simplification is often unjustified, and the suggestion by Matanol in 1933 of a way of avoiding it was welcomed. Matano&apos;s paper was based on work done as early as 1882 by Boltzmann.2,3 In 1938 Rhines and Meh14 reported an extensive investigation of systems in which the diffusion coefficient depends strongly on concentration, and included a detailed description of the Matano-Boltz-mann method. To a large degree, this description represents the formal method as it is understood and applied today, most later discussions having emphasized thermodynamic and mechanistic aspects of diffusion. Exceptions are the comments of R. V. Churchill, contained in a paper by Ham, Parke and Herzig,5 and the papers by Hall8 and by Kirkaldy.7 More discussion appears necessary since some aspects of the problem remain obscure. Better computational procedures are also needed. The common method, involving graphical determination of slopes and areas, is inconvenient and makes the estimation of errors difficult. Background of the Matano-Boltzmann Method Eq. 1 is to be considered along with initial and boundary conditions. Take the origin of x at the

Jan 1, 1958

By F. E. Jaumot, A. Sawatzky

IT as long been recognized that there is a need for accurate systematic data on diffusion in solids. Originally, such data were needed to check existing theories but, more recently, it would appear that it could be used most advantageously as a guide to, or a check for, much needed extensions of the theory of diffusion. The awareness of the conditions which are important to experimental accuracy, the availability of the materials for accurate experiments, and the techniques have improved to the extent that it would now seem to an experimentalist that, unless extensions of the theory are made which take into account the fundamental parameters of the atoms, the electrons, and the lattice in some detail, the field of diffusion will rapidly become an empirical or semi-empirical field. The present series of experiments was designed to provide accurate data on the diffusion of the elements of the IB and IIB subgroups in silver; that is, to provide data on the diffusion in silver of three face-centered-cubic elements with roughly similar chemical properties, but with different atomic or ionic sizes and, similarly, for three noncubic elements. The elements of these two subgroups have different valences, so that the data will not give any significant information on differences due to the crystal structure of the solute. The present paper reports data on the diffusion of copper and mercury in single crystals of silver; the data for the other elements of the IB and IIB subgroups were reported previously by the authors1&apos;2 and by Tomizuka and Slifkin.8 Experiment The general technique used was identical to that previously described1,2 and will not be repeated here. In all cases, the sectioning technique and high specific activity isotopes" were used. The short half-life of Cu64 made decay corrections more important than for the other isotopes, and necessitated around the clock shifts while data were being taken. Each section was counted at least twice (as was true for all longer half-life isotopes) and a monitor was counted along with each sample. Data for the diffusion of mercury in silver are presented at a greater number of temperatures than for the other solutes. This is a result of two circumstances. First, six (of 30) samples had to be discarded because of pitting or recrystallization which occurred during the diffusion runs, even though the samples had sustained high temperature prediffusion anneals. Either of these was a very rare phenomenon in the other experiments, and their occurrence in this case is considered in more detail below. Second, the curves of the logarithm of the activity of the sections vs the square of the penetration deptht were, in general, quite good, but frequently seemed to show one point to have high activity and the next point to have slightly low activity in terms of the best straight line. When this occurred, there was remarkable regularity of the high-low sequence. In any event, the results, as far as diffusion coefficients are concerned, were not affected by this amalgam effect. In fact, the mercury data had the highest internal consistency of any of the data. Results Diffusion of Copper in Silver—-Diffusion runs were made at eight temperatures In the temperature range from 700° to 950°C, for times ranging from 5 to 45 hr. A linear curve of the logarithm or the activity vs the square of the penetration depth was obtained for all samples. Table I summarizes the results for individual samples and Fig. 1 gives a plot 02 the logarithm of the diffusion coefficients as

Jan 1, 1958

By P. E. Baker

The commercial neutron-gamma log measures the intensity of gamma-rays produced by the interaction of neutrons with nuclei in the formation and in the bore hole. This measurement gives information concerning the distribution of neutrons around the neutron source, and in particular gives information on porosity or fluid content. Another type of information is contained in the frequency or energy spectrum of the neutron capture gamma-rays. The capture gamma-rays of each element, in fact of each isotope, have only those energies characteristic of that isotope.&apos;" The neutron capture gamma-ray spectrum, if obtainable, would permit the identification of the elements producing the spectrum. Such information would have considerable value in oilfield exploration work if it could be applied practically in well logging. Experiments have been carried out at the La Habra Laboratory of California Research Cop. to determine the feasibility of a method of well logging in which neutron capture gamma-ray spectra are measured down hole. In these experiments, spectra were obtained for artificial formations under simulated borehole conditions, using actual borehole geometry. This paper will describe the experimental apparatus and methods and will present the spectrum curves for several formations. THEORY Basic Formulas The neutron capture cross section of an element is a measure of its tendency to capture neutrons. The macroscopic cross section, or cross section per cubic centimeter, of a material composed of several elements is the sum of the cross sections of the nuclei making up 1 cc of the material. This is expressed in the equation SB = Sn1s2, ..........(1) where SB is the macroscopic cross section, s, is the cross section of a nucleus of type i, and ni is the number of nuclei of type i/cu cm. If N is the number of neutrons absorbed per second by the composite material, then the number captured by element j is Ni = N nisi/SB = N nisi/Si ni si ......(2) When the nucleus captures a neutron, a new nucleus is formed, which is usually in an excited state and falls to its ground or unexcited state by emitting one or more gamma-ray quanta.* The emission spectrum has been measured for many elements (see Table 1). The intensity of gamma-rays produced by an element is proportional to the number of neutrons captured per unit time by the element, which in turn depends on the capture cross section of that element and the capture cross sections of the other elements present which are competing with the first element for thermal neutrons. In a small sample of material the number of neutrons, N, captured per second is N = ?SB, ..........(3) where $ is the thermal neutron flux and SB is the macro-scopic cross section defined above. The number of neutrons captured by element j is N1 = ?ni si = N ni si/SB . ......(4) The number of gamma-ray quanta of energy, E, pro-duced per unit time by element, j, is I(E)=Nni si/SB P(E) .......(5) where P(E) is the emission probability of element, j, for this gamma-ray energy. Borehole Effects The capture gamma-ray spectra of many elements have been measured accurately in academic and government laboratories. These measurements are made on small samples, and from these measurements the emission spectra of the elements are obtained.

Jan 1, 1958

This study of the tin-tungsten ore of the Shepherd and Murphy Mine, in central northern Tasmania, was originally undertaken at the request of the Moina Tungsten-Tin Mining Co., N.L., as part of the research programme of the Mineragraphic Investigations Section of the C.S.I.R.O. It is based on the examination of a suite of specimens supplied by the management, supplemented by a more extensive collection and observations made by the author during a short visit to the mine in October, 1956.The Shepherd and Murphy Mine is at Moina, 36 miles S.W. of Devonport and 22 miles from Sheffield, the nearest railway station. It was worked almost&#183; continuously from 1893 to 1919, when a fire destroyed the mill; to that date it had produced concentrates to the value of &#163;141,000. After a long period of idleness, the mine was re-opened by the present company, but it has been announced recently that unfavourable market conditions have again forced closure.GENERAL GEOLOGYThe mine is on a deeply dissected plateau, about 2,500 ft. above sea level; it lies between the Iris and the Forth Rivers, whose valleys are deep gorges cut to about 400 to 600 ft. above sea level. From Moina westwards to the Iris River, a limestone regarded as part of the Gordon River Group, of Ordovician age, conformably overlies a sandstone containing tubicolar casts which are circular in cross section, half an inch in diameter and up to two feet long, and which resemble marine worm burrows (Elliston, 1953).

Jan 1, 1958

By P. J. Colbassani

Samples of mine atmospheres collected by Federal coal-mine inspectors during their inspections and investigations of coal mines, in accordance with provisions of the Federal Coal Mine Safety Act (66 Stat. 692; 30 U. S. C., sees. 451-483) are analyzed routinely by chemical methods at Bureau of Mines laboratories. When samples collected in open workings of nongassy coal mines at points not less than 12 inches from the roof, face, or rib contain 0.25 percent or more methane, the act requires the operator, during operation of such mine, to comply with the provisions of sec. 209, Title II, of the act, which pertain to gassy mines. The methane con-tents of such samples are determined by a physical method based on infrared absorption spectrometry to provide an independent check on analytical results obtained by chemical methods. This information circular describes the equipment and procedures used by the Bureau for determining low concentrations of methane in coal mine atmospheres by infrared absorption spectrometry. ACKNOWLEDGMENTS The authors are indebted to Dr. R. A. Friedel, Chief of Spectrometric Section, Branch of Coal-to-Oil Research, Bureau of Mines, for suggesting the analytical method and for furnishing valuable advice and assistance, and to J. A. Queiser of his staff for making exploratory measurements by this method; to Dr. M. G. Zabetakis of the Division of Explosives Technology for his assistance during the conduct of preliminary experimentation; and to L. B. Berger, Chief, Branch of Health Research, under whose guidance the equipment was procured and the work conducted.

Jan 1, 1958

By John C. Shyne, Eric R. Morgan

BORON as a hardenability agent of commercial importance has been the subject of extensive study in recent years. It has been suggested in the past that boron increases hardenability by combining with nitrogen, thus rendering it innocuous.&apos; More recently it has been proposed that boron increases hardenability by reducing the free energy of sites of ferrite and pearlite nucleation.&apos; The segregation of boron to grain boundaries, the primary site of nucleation, would account for the large hardenability effect of minute additions of boron in steel. This grain boundary theory has found general acceptance while the concept of boron as a nitrogen scavenger has been disregarded. However, the interaction of boron and nitrogen in steel is considered to be important to hardenability because boron may be made ineffective by combination with nitrogen.". * The present work was undertaken to examine some of the effects of boron and nitrogen arid their interaction in steel. A base composition of moderate hardenability was chosen. This was a 0.35 pct C steel containing 2.50 pct Ni and 0.30 Mo. This composition was used because it contained no strong carbide, nitride, or Table I. Composition of Steels by Analysis, Wt Pct Steel C Ni Mo 0&apos; B N* Base 0.35 2.50 0.30 0.0012 nil <0.0001 Boron 0.35 2.50 0.32 0.0012 0.0022 <0.0001 Nitrogen 0.33 2.60 0.35 0.0015 nll 0.0052 Boron plus nitrogen 0.35 2.48 0.30 0.0006 0.0020 0.0040 * Obtained by vacuum fusion technique. boride-forming elements. The other alloys examined were modifications of the base composition and contained nitrogen, boron, or nitrogen plus boron. The compositions of the four alloys used are listed in Table I. The alloys were vacuum melted from electrolytic iron, electrolytic nickel, ferromolybdenum, and fer-roboron. When required, nitrogen was added by admitting a partial pressure of nitrogen over the melt after vacuum melting. The alloys were cast into 21h-in. diam ingots and hot rolled to %-in. sq bars. No ingot pattern was discernible on the polished and etched cross sections of the hot-rolled bars. The alloys were normalized at 1650°F, then machined into standard %-in. diam end-quench hardenability test bars. Four different austenitizing treatments were used: 60 rnin at 1550°F, 45 rnin at 1800°F, 30 rnin at 2000°F, and 20 rnin at 2000°F followed immediately by 30 rnin at 1550°F. The 1550" and 2000°F treatments were carried out in duplicate for each of the four steels. In order to prevent surface oxidation the bars were austenitized while buried under charcoal in an atmosphere of argon. After quenching the bars in a conventional end-quench fixture, the hardness surveys were made in the usual fashion on parallel flats ground along opposite sides of each bar. These were ground 0.050 in. deep rather than the conventional 0.015 in., to avoid decarburized or deboronized regions.5 The austenite grain sizes which resulted from each heat treatment were observed metallographically using Vilella&apos;s etch for martensite. The criterion used as a measure of hardenability was the distance from the quenched ends of the bars at which a hardness of RC 35 was observed. This hardness represented the inflection point on the hardness vs distance plot. Fig. 1 shows the hardenability of each steel after the several heat treatments. The duplicate tests demonstrated excellent reproducibility; the distance to Rc 35 was reproduced within 1/16 in. for duplicate test bars. All four alloys had the same grain-coarsening characteristics. Neither boron nor nitrogen had any observable effect on grain size. The grain sizes resulting from the various austenitizing treatments were ASTM 7 at 1550°F, ASTM 4 at 1800°F, and ASTM 2 at 2000°F. The small amount of boron in the boron steel greatly enhanced hardenability when the samples were austenitized at 1550°F. The low hardenability of the boron plus nitrogen steel showed that nitrogen eliminated the boron contribution to hardenability. Both steels containing nitrogen, with and without boron, exhibited lower hardenability than the base composition when quenched from 1550°F.

Jan 1, 1958

By M. I. Sherman, J. D. H. Strickland

USE of a hydrometallurgical approach to the oxidation of sulfide ores and extraction of metals therefrom may have advantages over the more common smelting techniques when a low grade deposit is difficult to concentrate or the subsequent separation of metals, coexisting in the ore, is laborious by any known smelting operation. For economic reasons, the most promising oxidants are either atmospheric oxygen or electric power. The use of oxygen, or air under pressure, has recently been revised. Pyrrhotite has been converted to iron oxide and elementary sulfur&apos; and a variety of sulfides have been treated by Forward and co-workers.2-4 Generally sulfate is the end form of the sulfur but with galena in an acid medium, elementary sulfur can be formed." For economic reasons chlorine and ferric iron salts are about the only possible alternatives to the atmosphere as oxidizing agents for base metal sulfides. If aqueous solutions of chlorine or ferric iron are employed, the reduction products can be oxidized electrolytically in situ and used again, thus acting as catalysts for electric power as oxidant. The use of ferric salts for this purpose is established hydrometallurgical practicea but, although chlorine gas has been employed in the dry state at an elevated temperature, its use in aqueous solution at or near room temperature has not found favor. The reaction of chlorine water with the soluble sulfide ion has been studied by several workers,7-9 and both sulfate and elemental sulfur are found as end products, the latter being favored by the presence of a low concentration of oxidant relative to that of sulfide in solutions of about pH 9 to 10. Of direct bearing on the work in hand are an early American patent" and a recent Austrian patent." The former advocates stirring powdered ore with an aqueous solution of ferric chloride chlorine oxides and chlorine. In the latter it is claimed that both metal and sulfur can be obtained by electrolysis, in a diaphragm cell, of a metal ore slurry in brine. Details in these patents are scant and no data or explanation is given for the mechanism of the reaction which, in the Austrian work, is attributed to the (unlikely) action of nascent chlorine at the anode surface. No mention is made of possible differences in behaviour between various ores. Apparatus A complication encountered when working with chlorine water is that a serious loss of chlorine occurs by gas partitioning unless an enclosed system is used and any air space in the apparatus is kept very small and constant. Arrangements were made, therefore, to take out samples for analysis without letting air into the system to replace the liquid removed. For convenience in studying a heterogeneous reaction the apparatus was so designed that a reproducible controlled stirring rate could be maintained and the ratio of surface area of ore to volume of solution was approximately constant throughout any experiment. The apparatus used is shown in Fig. 1. The ground ore was placed in the horizontal cylindrical vessel, A, of about 1 liter capacity, heated by a constant temperature circulating bath pumping water through the concentric jacket, B. By adding chro-mate to this water, an ultraviolet radiation filter effectively surrounded the reaction vessel, greatly reducing any possible photochemical decomposition of chlorine solutions. Stirring was effected by glass paddles, C, attached by an axle to a magnet which was rotated by another powerful Alnico magnet, D, outside the glass end, this magnet being itself rotated by an electric motor electronically controlled to constant speed. Speed could be varied from about 150 to 900 rpm and was measured and held to within 1 pct of a given value. The end of the reaction vessel remote from the stirring magnet was closed by another one-ended glass cylinder, E, connected by thin polyethylene bellows, F, clamped by screw clamps and watertight rubber gaskets to the main vessel. Through E, a glass electrode and calomel electrode projected into the solution and a hypodermic syringe pierced a small bung and allowed acid or alkaline to be added to maintain a constant pH. By pushing the fully extended bellows until the two cylinders touched, from 50 to 100 ml of solution could be forced out through a sintered disk into the three-way tap system, G, either to waste (for flushing purposes) or up into a 10 ml burette where the solution could subsequently be measured out for analysis. The ore samples were introduced at H, the tube being stoppered by a thermometer of —1 to +52ºC range, graduated to 0.1°C intervals. To prevent ore from being ground in the end bearings of the stirrer these bearings were pro-

Jan 1, 1958

By A. R. Troiano, W. J. Barnett

IN recent years the demands of space limitations and increased loads, particularly in the aircraft industry, have accelerated the trend toward utilization of ultra-high strength steels. The increased application of such steels has focused attention on the phenomenon of delayed failure or static fatigue. Parts subjected to a static load, after successfully sustaining the load for an extended period of time, may fail in a brittle manner. Subsequent examination of such failed parts by conventional laboratory tests in many cases reveals no apparent signs of embrittle-ment. That is, the material exhibits good ductility and impact resistance. Furthermore, consideration of the service conditions (environment and temperature) under which this brittle failure occurred eliminates its classification as a stress-corrosion or creep type of failure. Recently this unique time dependent fracture process has been the subject of numerous investigations. The most significant result of these studies was the recognition of hydrogen as the source of embrittlement. While the effect of numerous variables on the occurrence of static fatigue failure has been defined, an adequate explanation of these behaviors is lacking. The occurrence of this phenomenon in steels generally has been limited to strength levels in excess of 180,000 lb per sq in. Although steels at high hardness levels have exhibited delayed failure in the absence of hydrogen introduction after heat treat-ment,&apos;.&apos; this behavior was most prevalent when the material in processing had been subjected to an environment conducive to the absorption of hydrogen. Delayed failures have been produced in high strength steels by the introduction of hydrogen

Jan 1, 1958

By J. L. Huitt, IM. L. Slusser, E. E. Glenn, M. L. Slusser

This paper is concerned with: (1) an analysis and interpretation of the filtration characteristics of drilling muds on filter paper, and (2) an interpretation of early stage "filtration" on consolidated synthetic porous media, herein referred to as the "surge loss" period. It is shown that water-loss data can be plotted so as to disclose the existence of a surge period, a non-uni-form cake thickness period, and a constant pressure filtration period. The same periods occur during exposure of consolidated porous media to muds. The data on consolidated porous media indicate that: (1) mud particles bridge pores inside porous media during the surge period, and (2) "filter cake" build-up inside porous media occurs during subsequent filtration. The data also show that the surge loss increases with sample permeability and with pressure differential. INTRODUCTION The phenomenon of mud filtrate invasion into porous sands of a drilling well has been recognized for many years.1,2,3,4 Part of API Code 29 is concerned with the filtration testing of a drilling mud to yield data on this subject. In a number of investigations "plastering properties" of muds were studied,5,6,7,8 "plastering" apparently meaning cake forming properties. In such studies the characteristics (thickness, permeability, and toughness) of the cake and the rate at which the liquid phase of the mud was separated from the solids (filtration rate through the cake, commonly referred to as water loss) were measured or at least considered. From the standpoint of its effect on well productivity, filtrate invasion into "clean" water-wet pay sands (i.e., those containing no clay minerals) may not necessarily be a serious problem. An increase in water saturation in the zone immediately around the wellbore would cause loss of oil permeability. However, in such a system, much of this water may be removed by oil production. If filtration occurs into "dirty" sands (i.e., those containing appreciable clay minerals), clay swelling or other mechanisms may cause losses in oil permeability which cannot be overcome by oil production.&apos;.&apos; The phenomenon of mud particle invasion into the pay sand of a drilling well was considered to be a possible serious factor in the early days of rotary drilling. Opinions varied as to whether drilling fluids "mudded up" and "sealed" oil sands. In 1932 Rubel,9 Gill,10 and Parsons," in separate papers, presented differences of opinion together with some laboratory and field data concerning loss of oil production caused by drilling fluid invasion into pay zones. These papers, and the discussions, furnish a large background on this subject and indicate the very clear thinking of many men at a time when petroleum production technology was in its infancy. Jones and Babson,6 and Silent,&apos; experimentally found that the depth to which mud particles invaded water-saturated sand packs was small (no greater than 1/16 in). Arn-quist12 in 1937 observed loss of water permeability due to invasion of mud particles into water-saturated, consolidated, sandstone samples. Williams and Cannon5 studied the filtra-tion properties of drilling muds and mentioned "sludge" which penetrated a short distance into the water-saturated filtering medium (sand pack). Byck5 concluded that formation permeability had no effect on the plas-

Jan 1, 1958