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By Frederic Benard

THE treatment of Balbach-Thum slimes at Copper Cliff by the Ontario Refining Co, is of interest because it differs considerably from methods usually employed for the recovery of fine gold from parting-plant slimes. Owing to the comparatively high percentages of palladium and platinum, wet methods are used to remove the greater proportion of these metals before electrolytic refining in the Wohlwill cells. THE PLANT The platinum-metals department, Wohlwill room, and gold-melting room extend along the north side of the silver refinery and are separated from the parting plant by a glass partition (Figs. 1 and 2). The platinum-metals department resembles a laboratory built on a large scale, with the various pieces of equipment laid out on terraces to facilitate handling. . Because of the corrosive nature of the solutions, chemical stoneware is used throughout. Elevation of acids is accomplished by means of Mariotte bottles. On the top level are three steam-jacketed stoneware kettles of 50-gal. capacity, also a packed tower. One kettle is used for digesting the slimes while the remaining kettles are used for precipitating the gold. The dissolver is equipped with a treated concrete hood, which is connected to the flue system. Gases are drawn off through the packed tower by means of a 6-in. stoneware exhaust fan. A 15 per cent solution of sodium carbonate is continually circulated through the tower. On the intermediate level are two suction filters, one for removing silver chloride and the other for the gold sand. The filter medium consists of an asbestos pad covered with a filter paper on which is a layer of twill. On the bottom level are two rectangular cementation tanks, 24 by 48 by 24 in. deep, and a suction filter used for removing the platinum-metal concentrates. The circulating pump for the packed tower is also here. Suction is provided by a vacuum pump having a capacity of 8 cu. ft. at 20-in. vacuum.

Jan 1, 1938

By T. D. Tiemann

The caustic extraction of silica from Wisconsin and Minnesota taconite was investigated by bomb digestion over the temperature range from 312 to 40S°F at caustic concentrations from 25 to 500 gpl. Residual concentrates containing as much as 65 pct iron were obtained. The high rate of silica extraction is related to a microcrystalline variety of quartz, since it is shown that the rate of extraction of silica from quartz is directly proportional to its surface area. Increasing dependence on foreign ore reserves makes the need for developing the technology necessary for treatment of our low grade ores even greater than it was at the time of World War 11, when much research was conducted on the extraction of alumina from clays. Representative of these were the studies carried on at the University of Illinois.' More recently, the U. S. Bureau of Mines investigated the production of alumina from anorthosite, and currently the aluminum industry is showing renewed research interest in this field. The studies reported here are part of a continuing research program based on the above concepts and aimed at the eventual development of processes for the treatment of low grade ores, particularly those of iron. The fact that large reserves 3 of low grade nonmagnetic taconite are contained in the iron formation of the Wisconsin Gogebic range have made this ore an important and attractive target for investigation. The idea of removing silica by caustic extraction is not new.495 The digestion in caustic solution of ground flint, diatomite, and other forms of chalcedonic silica is the basis for the production of soluble sodium silicates by the wet-process. Upgrading bauxites by the caustic extraction of silica has been investigated6 and is the subject of a German patent.7 Although mention is made by Roe' of the caustic extraction of silica from low grade Michigan and Wisconsin iron ores, and he lists a number of patents and references on the subject, recent work in the field does not appear to be extensive. As far as the author knows, there has been no work in this field on these particular ores. It is hoped that this paper will stimulate further investigation which will eventually lead to an econclmic means of processing these large low grade reserbes. TACONITES The taconites investigated in this study were from Minnesota and Wisconsin. That from Minnesota, a semi-taconite, Nas obtained from the Oliver Iron Mining Division, U. S. Steel Corporation, and represents a sample of an oxidized iron formation from their King Mine on the Mesabi range. The Wisconsin taconite came originally from the trench sampling of the U. S. Bureau of Mines, and represents a composite of the Norrie, Pabst, Yale, Plymouth, and Pence members of the Gogebic iron formation. Assays on these samples are given in Table I. A typical calcu1atr:d average analysis of the Wisconsin taconite is given in Table 11. Chemically, the Minnesota semi-taconite sample contains about 39 pct iron and 39 pct silica, while the Wisconsin taconite contains 30 pct iron and 53 pct silica, both on the dry basis.

Jan 1, 1962

By J. P. Kimball

INCIDENTAL to a description of the hytlrographical basin of the Quemahoning in Somerset county, Pa., as a coal-field, I have, without a personal survey of the whole county, taken the pains to collate a synopsis of' leading facts, so car as available, relating to its coal resources. This is here presented, in view of an interest in the subject, growing out of a nearly central traverse of the county, in common with the southern tier of counties of the State, west of Blue mountain, by a new trunk line of railway—the South Pennsylvania. The political east-and-west boundaries of Somerset county, Pa., following the bold topography of Allegheny mountain and Laurel hill, are in common with the east-and-west boundaries of the First Bituminous Coal-basin formed by these ridges respectively, except the southeastern townships which lie on the eastern slope of Allegheny mountain. The nearly parallel anticlinals of Negro mountain and the so-called Viaduct axis stratigraphically divide the basin into three sub-basins, which, in order from east to west, are known as follows, viz. : I. Berlin-Salisbury (Eustern) Sub-basin : Between Allegheny mountain and Negro mountain, embracing the Berlin section of Barren coal-measures, the Salisbury section of Upper Productive coal-measures, and the Meyersdale and Garrett sections of Lower Productive coal-measures. 11. Somerset (Middle) Sub-basin: Between Kegro mauntain and the Viaduct axis, so called from the viaduct on the Conemaugh river, which there crosses it; embracing the section of Lower Productive measures of Mineral Point and Casselman on Castlenlan river, and of Somerset. 111. Johnstown- Confluence (Western) Sub-basin: Between the Viaduct stratigraphical sub-axis (which is less strongly marked topograpically in Somerset county as a ridge than in Cambria county), and the Laurel Hill graud axis. The synclinal of this sub-basin is crossed by tile Conemaugh near Johnstown, and by the Castleman

Jan 1, 1884

By H. Shaw

In the author's previous paper an attempt was made to analyze in detail the gravitational effects arising from certain subterranean anomalies of simple form, and extending to infinity in three directions. As a result of this critical examination, certain features—which were considered to be characteristic of the anomalies under investigation—were disclosed, a close observance of which enables a complete interpretation to be reached. The most simple case was first considered; viz., that of a heavy horizontal plate, bounded above and below by horizontal planes, and extending to infinity on one side of a vertical plane containing the y axis, in the three directions + y, —y, and +x. After this, the investigation was extended to the case of a similar infinite horizontal block having an inclined face. In each case the form and behavior of the gradient curve and the curve of differential curvature were analyzed, and entirely distinct interpretations were put forward, based upon (1) the gradient, (2) the differential curvature and (3) a comparison of these two quantities. In continuation of the previous work, and as a preliminary to further analysis of more complex structures, certain factors will now be examined which characterize (1) the simple infinite vertical block and (2) an infinite block which is inclined to the vertical, formations which are of considerable practical interest, being typical of important. geological structures—intru-sive dikes, lodes, veins, etc.—and because, even though in nature these may be irregular, valuable guides to a more complete interpretation are obtained by assuming, as a first approximation, that they have the simple characteristics to be studied hereafter. In the previous paper certain preliminary assumptions were made in order to render the resulting deductions universally applicable and entirely independent of the particular scale employed. Consideration was limited to homogeneous deposits of unit positive effective density (and this condition is retained in the present investigation), so that in the case of

Jan 1, 1932

By Henry R. Joesting

DURING the past year and a half, the Territorial Department of Mines in Alaska has conducted a modest experimental program for the purpose of determining the extent to which magnetic and resistivity methods can be used in interior Alaska in connection with prospecting, mining and geological studies. Since little information is available concerning previous work,1,2 and since conditions differ considerably from those in most other regions, it was considered advisable to make a general study of the possibilities and limitations of the two methods, rather than a detailed study of any single problem. PROBLEMS One of the most serious handicaps to prospecting and geological study in interior Alaska, especially in the mature regions, is a cover of unconsolidated deposits ranging in thickness from a few feet to several hundred feet. These deposits, some of which are permanently frozen, consist of silt with varying proportions of vegetation and windblown material in the valleys and of residual deposits on the hills.3,4 The problems treated here are caused by the existence of this overburden: I. Location of buried placers. 2. Determination of depth and areal distribution of permanently frozen and of thawed unconsolidated deposits. 3. Location of water-bearing beds under unconsolidated deposits. INSTRUMENTS AND METHODS Magnetic and direct-current resistivity methods were used because they are relatively simple, rapid and inexpensive and because generally they are well suited to the study of the problems indicated. The instruments used were a vertical Schmidt-type magnetometer and a direct-current resistivity instrument similar to those used by the Geophysical Branch of the U. S. Geological Survey.5 For placer surveys with the magnetometer, a sensitivity of about 25 gammas per scale division was found suitable. For resistivity studies of frozen and thawed overburden and of underground water, the Lee partitioning method6 was found to be most generally suitable. In the Lee method a central potential electrode is placed midway between the two potential electrodes of the Wenner four-electrode configuration.7 Nonpolarizable electrodes were made from unglazed porcelain pots about 10 cm. high and 5 cm. in diameter. In order to retard evaporation of the electrolyte the sides of the pots were glazed, inside and out, with clear Duco lacquer. For resistivity work in cold weather, a nonfreezing electrolyte consisting of equal parts of ethylene glycol and a saturated water solution of copper sulphate proved satisfactory. Stainless steel rods of 3/4-in. diameter made excellent current electrodes because their bright finish enabled good ground contacts to be made.

Jan 1, 1941

By L. B. Slichter

It has been estimated that rock exposures in most mining districts aggregate less than 1 per cent. of the total surface area.1 Conclusions concerning the hidden 99 per cent. necessarily have been based on knowledge of only a small fraction of the surface, and from this limited information the geologist has been obliged to deduce the approximate and general nature of the underlying formations. In the search for ore it is necessary to supplement this general picture with greater detail. Fairly accurate knowledge of relatively small zones is required. This knowledge is carefully sought in many different ways—detailed interpretations of geological history, the tracing of float, the use of test pits, of trenching, of drilling, and of other methods. Practical ingenuity, scientific brilliance, great perseverance and patience, and the expenditure of large sums of money have all been a part of this search. The problem of exploring beneath cover with economy, and of obtaining essential information which this cover hides, is obviously a difficult one. It is also a very important one, for geologist's inform us that already the story of the 1 per cent. exposed outcrops has been largely read.V here remains the nearly virgin field comprised in the hidden 99 per cent.: and the importance of this zone is bound to increase continually. In recent years, the problems connected with the exploration of this "99 per cent. zone" have attracted a constantly enlarging group of investigators and at present greater efforts than ever before are being made to resolve them. This work, in it's various special aspects, has enlisted, beside geologists, the cooperative efforts of chemists, physicists, and mathematicians. The progress made in this development should be kept before those directing explorations in order that due advantage may be taken of a changing situation. My subject concerns certain aspects of one of the older physical methods of exploration, the magnetic method. This method is familiar in principle to most of us, arid because of its age., is especially suitable for

Jan 1, 1929

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By R. B. Tippin, J. S. Browning

Inasmuch as the higher grade potash deposits are rapidly being depleted, it is important that economic beneficiation techniques be developed for recovering potassium compounds from lower grade sylvite ores and deposits containing clay materials. The Federal Bureau of Mines has conducted research to develop processes for heavy liquid concentration of potash ores, This method of concentration is discussed, and results of tests made on potash ores from New Mexico are presented. The tests demonstrated the technical feasibility of producing near commercial-grade potash concentrates, with a high recovery of the contained sylvite. The concentration of minerals based on their differences in specific gravity dates back to the very beginning of mineral dressing, and the use of heavy liquids in the laboratory to achieve optimum mineral separations has been utilized for many years. With the advent of froth flotation and its success, the incentive to develop new processes has remained relatively dormant. However, flotation refinements in the nonmetallic ores have not progressed as rapidly as in metallic (sulfide) ores because of the complexity of the deposits and the chemical similarities of the minerals.

Jan 1, 1967

By A. T. Robinson, J. E. Dorn

The electrical resistivities of aluminum alloys containing CU, Ge, Zn, Ag, Cd, and Mg were found to increase linearly with the atomic percentage of the solute atoms. Application of Linde's rule to these data suggests that each aluminum atom contributes 2.5 electrons to the metallic bond. ALTHOUGH aluminum invariably exhibits a Jt\. valence of three in ionic solids, it does not follow necessarily that its valence in the metallic state is also three. As a matter of record, many properties suggest that the number of bonding electrons in metallic aluminum is less than three. For example, as shown in Fig. 1, the atomic radii1 of the metallic elements in the solid state decrease with increasing atomic number at the beginning of any one period. The atomic radius of aluminum, however, is greater than that which would result from a regular decrease in atomic radius with increasing atomic number, suggesting that the number of bonding electrons in aluminum is somewhat less than three. Correlated with the anomalously large atomic radius of aluminum is its abnormally low melting temperature. As the atomic numbers increase in any one period, the melting temperatures of the metallic elements increase.' As shown in Fig. 2, however, the melting temperature of aluminum (13) is only slightly greater than that of magnesium (12). Again the number of bonding electrons in metallic aluminum appears to be nearer two than the expected value of three. In addition Ageev and Ageeva3 alculated the electron density distribution in the aluminum lattice. A comparison of such electron density curves for various assumed valence states of aluminum with experimentally determined curves suggests that the actual number of bonding electrons in metallic aluminum is between two and three. Hume-Rothery and Raynor', " have suggested that the above-mentioned abnormalities are associated with the overlapping of the Brillouin zones of metallic aluminum when it is in the usual face-centered cubic structure. The importance of the number of bonding electrons in metals has been extended recently into the field of mechanical properties. While formerly it was thought that the plastic properties of alpha solid solutions were primarily dependent upon the lattice strain induced in the solvent by the solute, it is now known that the difference in the number of bonding electrons of the solute and solvent also has its influence on the plastic properties."1' In order to achieve a satisfactory correlation of the effect of alloying elements on the plastic properties of aluminum alloys,"'T however, it was necessary to assume that the number of bonding electrons contributed by aluminum was about two rather than the expected value of three. It appeared to be desirable, therefore, to seek other criteria for evaluating the number of bonding electrons contributed by aluminum to its alpha solid solutions, especially in view of the practical as well as the theoretical importance of the effect of valency on the plastic properties. Norbury' was perhaps the first to illustrate that the increase in resistance of alpha solid solutions is associated with the differences in valence of the solute and solvent metals. In a series of illuminating investigations Linden-'' has shown that the electrical

Jan 1, 1952

By Michael Tenebaum, C. C. Brown

In recent years, the importance of slag control in basic open-hearth operations has been universally recognized. To effect such control during the working period of the heat, methods have been developed to measure or estimate slag oxidation and slag basicity. While satisfactory rapid chemical methods have been developed to determine slag oxidation, no completely adequate method of evaluating basicity has yet been provided. The most generally accepted control methods of measuring slag basicity are based on visual cstimates. While considerable benefit may be derived from such estimates, the need for some measurable indication of slag basicity has become increasingly apparent. In a recent paper, Philbrook and Jolly suggested a promising technique for making the basicity determination. Their method consists of measuring the pH of a mixture of powdered open-hearth slag and distilled water. It was found that a relation could be established between the slag basicity and the alkalinity of the water mixture as measured by the hydrogen-ion concentration. The general procedure followed in making the measurements and the considerations involved in constructing the original curves are given in the paper of Philbrook and Jolly and need not be repeated. It is the purpose of this paper to discuss some of the factors considered in applying the pH measurements to actual slag control and to present some of the results of its apphcation. Factors Involved in Measuring pH of Water-slag Mixtures To facilitate the application of the pH control system, it was desirable that no alteration be made in the routine methods of sampling and crushing the furnace slag. Some of the factors considered before establishing a curve to relate slag basicity with the pH reading arc reviewed individually in the following paragraphs. Effect of Cooling Rate Under actual operating conditions there can be considerable variation in the temperature of the piece of slag crushed for the pH determination. To determine whether variations in crushing temperature or in cooling rate would affect the pH reading, a series of four samples was prepared from each of two separate slags. These samples represented conditions far more extreme than would actually be encountered. To obtain these samples, a thick pancake of slag was poured. One piece of this pancake was crushed immediately after it had solidified. Another piece was water-quenched and then crushed. A third piece was allowed to air-cool to room temperature before crushing. The fourth sample was prepared from a chilled slag. This sample was poured onto a heavy inclined steel plate at the

Jan 1, 1945

By L. C. Graton

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

Jan 1, 1931

By R. G. O’Meara, M. M. Fine

ONE of the principal activities of the Bureau of Mines connected with the recent war was to help to increase the supply of strategic and critical minerals. Fluorite was one of the most critical of the nonmetallic minerals because of the increased demand for it as a flux in basic open-hearth and electric steel furnaces and as a raw material for the production of artificial cryolite used in the aluminum industry. Wartime developments in the technology of hydrofluoric acid, such as the use of the anhydrous acid as a catalyst in production of high-octane gasoline and the use of organic fluorides as carriers for insecticides, also increased the demand for acid-grade fluorite.[t] In 1943 the consumption of acid-grade fluorite was advancing at a more rapid rate than production, and was only slightly less than production during the latter half of the year.1 The outlook for the postwar market for fluorite is encouraging. Steel production is expected to remain high until the domestic demand for commodities not manufactured during the war is satisfied. The uses for hydrofluoric acid are expected to increase under the impetus of war-initiated research. In consideration of these and other factors some authorities predict a postwar demand for fluorite equal to about 60 to 75 per cent of the wartime production.1,2 Others believe that the postwar fluorite industry will be permanently expanded over its prewar status.3 ACKNOWLEDGMENT This paper is one of many reporting on various aspects of the Bureau of Mines program directed toward the more effective utilization of our mineral resources. The program has been under the general supervision of R. S. Dean, Assistant Director, since July 1942. The scope of the paper falls in the province of the Metallurgical Branch, whose activities embrace the separation of difficultly beneficiated ores, the production of pure metals from domestic deposits, the exploitation of marginal ore reserves, the recovery of secondary metals, and the improvement of present industrial metallurgical practice. The investigation was initiated at the request of Mr. J. H. Steinmesch, vice-president and general manager, Minerva Oil Co., Eldorado, Ill. His hearty cooperation and helpful suggestions, and those of Mr. O. E. Anderson, mill superintendent,

Jan 1, 1946

By A. M. Talbot, John T. Norton

TheRe is still considerable controversy as to the exact nature of the mechanism of the age-hardening process, in spite of the many experiments already performed. For this reason, a considerable number of typical systems should be examined in detail and their results correlated. Furthermore, the methods of studying the changes that take place during the progress of this phenomenon should be carefully scrutinized and the different methods applied to the same samples, preferably at the same time. The experiments described in this paper are presented to supply information on one age-hardening system and to show how the various methods of investigation compare in their indication of what has happened. In brief, the progress of aging in magnesium alloys containing about 10 per cent by weight of aluminum at different temperatures was followed by measurements of hardness, electrical resistivity, dilation and lattice parameter, and by microscopic observation. Previous Work Meissnerl,$ Archer?, and Gann3 have investigated the changes in mechanical properties of magnesium-aluminum alloys during aging and have shown the optimum condition for the age-hardening treatment. Meissner's results are particularly interesting because when replotted so that they represent hardness as a function of aging time, the curves of 125" and 150" C. show two hardness peaks. This result was not confirmed in the present work. Schmid and Siebe14 have reported an investigation that is similar to the present one but it was not published until the present work had

Jan 1, 1936

By A. W. Hesse

Ventilation of all types of coal mines is fundamentally the same, in that sufficient air must be provided to properly dilute and remove dangerous and obnoxious gases and leave the oxygen content of the air not under 1 9 per cent in all places where men and animals must work. Perhaps animals should not be mentioned, as the speed of mechanical loading leaves livestock behind and outmoded. Since this paper has to do with the influence of mechanical loading equipment on ventilation, the problems will be confined to the splits and the coal-producing places of the mine. The removal of coal dust from the air, or its rapid transmission to the return air courses; the possible increase in the liberation of gases by the multiplication of cuts in the coal made during one shift or multiple shifts; and the additional electrical equipment at the faces, are the factors that cause the added importance to good ventilation in the permissible equipment area of gassy bituminous coal mines. Ventilation tor Mechanical Loading in Gassy Mines In gassy mines, the air currents must be maintained across the faces in such a way as to prevent short cuts to the returns and leaving pockets in which accumulation of gas might occur. To do this, two or more doors are required on almost every entry containing a track to the face, so located that in no event will a trip of cars block open the doors and permit the air to bypass some place or places on the air-approach side. This method frequently requires the use of unusual lengths of duplex cables to reach the mechanical equipment at the faces, particularly where the distances between parallel working places are 100 ft., as at the Nemacolin mine. Fig. I shows a pillar section being worked with mechanical loaders. This layout requires carrying the air in on the right and releasing it on the left, because the track clearance is on the right side and the line brattice is built on this side from the last crosscut to the face. Thus, the air travels to the face with greater velocity and gives more assurance of sweeping out the gas that might be exuding from the crevices of the coal. All working places, in driving through solid coal, are thus treated alike. They are all potentially gassy and must be swept clear of whatever may contaminate the air. Once the air starts into the working section, it is not released until it does a good job. Of course the volume of air must be large enough not only to dilute the gases but to carry away explosive fumes and fine coal dust quickly. Mechanical loading entails cutting and drilling of the coal during the same working period as the loading when two-shift and three-shift operations are employed, and all three processes create finely pulverized coal, which in itself is hazardous if not controlled by some means. If the ventilation is inadequate and gas accumulates, and a spark from defective electrical

Jan 1, 1942

By G. A. Alers, J. H. Bechtold, R. W. Armstrong

The plastic flow of .molybdenum was studied in compression at temperatures below the ductile-to-brittle transition in tension. It was found that molybdenum is ductile in compression at all temperatures down to —196°C. The yield strength continues to increase with decreased test temperature below the tensile ductile-to-brittle transition temperature range. Difficulty was encountered in correlating the experimental data obtained with existing theories of plastic flow. THE body-centered-cubic metals as a group show a rapid and very large increase in yield strength with decreasing test temperature.' It is of fundamental importance to the understanding of the mechanism of plastic flow that this general characteristic be examined carefully. Unfortunately, brittle fracture in low-temperature tensile tests prohibits the measurement of flow properties at very low temperatures. By using compression tests, fracture can be suppressed and the plastic flow of the bcc metals can be studied far below their tensile ductile-to-brittle transition temperatures. Molybdenum was chosen for this experiment and plastic-flow data were obtained down to —196°C.

Jan 1, 1959

By Carl G. Schwenk

Rocks of the Precambrian Shield of Rusk County, Wis., were recognized as a favorable host for volcanogenic base metal deposits by personnel of Bear Creek Mining Co. Most of the county is covered by a thick layer of glacial drift: consequently, geophysical techniques played a prominent role in the exploration program conceived and initiated there in 1966. The original work on three Precambrian exposures was followed by an airborne electromagnetic survey and subsequent ground follow-up. A geophysical evaluation of air-borne anomaly F-22 defined a target which was interpreted as a massive sulfide body. Numerous potential field and electrical tools were utilized to describe the geometry and physical properties of the target. Drilling confirmed the massive sulfide interpretation and eztentually outlined a 6 million-ton copper deposit.

Jan 1, 1977

By E. C. Wright

THE following article is based on observation of college graduates entering the steel industry in technical work made during the past 25 years, the first five of which were spent as a college instructor in two engineering schools, and the last 20 in the employ of a large steel company that has hired hundreds of engineering graduates for steel-mill operations. The college graduates encountered during this period have come from many, colleges representing schools in Eastern States, Midwestern Universities, many Southern colleges, and many smaller colleges and normal training schools mostly in western Pennsylvania and Ohio. The college training of these students for engineering work naturally has varied widely and the educational qualifications of the entrants have been in many ways different. It was found at an early date that graduates of standard engineering colleges were much more adaptable than graduates in science from nontechnical schools. The engineering students seemed to be more suited to actual work in steel' plants and in general were better able to grasp a knowledge of the operations they observed. However, although the graduates of engineering schools have had somewhat better training -in physics, mathematics, and engineering, it has been a general and continual observation that most of the students employed have had inadequate training in the fundamental sciences. Since this discussion relates entirely to metallurgical engineers, it should be emphasized that students taking metallurgical engineering courses in college seem to be poorly trained in organic chemistry, physics, physical chemistry, thermodynamics, and any higher form of mathematics than simple calculus. It has been noted frequently that young engineers faced with problems in a mill that involve some mathematics generally flounder badly, and that they have little conception of physical chemistry. Another common deficiency lies in the young graduate's lack of knowledge of where to look for the more detailed literature on any subject. He reverts instinctively to some college textbook whose coverage is usually very elementary. It is recommended that such textbooks contain a bibliography of the source literature, and that students be taught to use theoriginal data. Many of the students had had previous courses in college dealing with metallurgical work such as steel melting, metallography, etc., but it was found that their grasp of these subjects was extremely sketchy. It was soon realized that an ordinary engineering graduate could be taught more about steel melting and manufacturing processes in a, few weeks in a. plant than he could learn in a college course on such subjects. A similar statement may be made regarding the ability of students to conduct laboratory work. Their lack of technique and skill in handling equipment and setting up experiments was soon apparent. It became neces-

Jan 1, 1946

By P. B. Crawford, W. L. Huskey

A study has been made to determine the effects of random vertical fractures existing in a reservoir matrix on the effective matrix properties and producing characteristics of a well. The study indicated that short vertical fractures may distort the isopotentials by 1 percent in the vicinity of the fracture. A correlation was developed which showed the effect of fracture density on the producing capacity of a well. The correlation indicated that fracture shape had little effect on producing capacity, but that total fracture length was closely correlated with the producing capacity. Effective values of reservoir permeability were found to correlate closely with fracture density when measured parallel to the direction of flow. INTRODUCTION In reviewing the petroleum literature, it is found that in most analytical solutions of hydrocarbon reservoir behavior the assumption is made that the rock is uniform throughout although core analysis and well logging surveys indicate that substantially all reservoirs are heterogeneous and some are fractured. Only in recent years have investigators studied the effects of reservoir hetrogeneity. Russell1 discussed the effect of fractures in reservoirs. The literature indicates that fractures greatly affect the exploitation of man reservoirs. This is described by Elkins and Skov2 and Little-field et al. 3 Several types of reservoir heterogeneity have been studied by unsteady-state methods. In 1959, Landrum et al. 4 showed that transient phenomena in hydrocarbon reservoirs could be studied by thermal models. pickering5 studied the flow of heat in stratified linear reservoirs consisting of plates of different metals separated by sheets of rubber which were suddenly exposed to a low-temperature source at one end. Cotman6 studied both laterally and vertically heterogeneous thermal model reservoirs with special reference to cross flow. Another type of reservoir heterogeneity involves the presence of highly permeable, circular lenses around or near the wellbore which was studied by Miesch7 using a thermal and a steady-state model. Many studies have been made of the effects of induced hydraulic fractures on well performance. 8-10 Work regarding vertical fractures that exist initially in the reservoir was reported by Givens, et al.11 Since there appears to be little published work on the importance and influence on reservoir performance of fractures that exist out in the rock matrix, this study was conducted to determine the effects of vertical fractures on pressure distribution, producing capacity and the effective permeability of the reservoir rock. The analogy between the flow of electrical current through a conducting body and the flow of fluid in a porous medium provides a convenient method of studying various aspects of petroleum reservoirs. For electrical radial steady-state flow,12 For steady-state fluid flow, With the above analogy, it is only necessary to establish the ratio of the values of the electrical units in terms of the corresponding flow units to make the analogy quantitative. The ratios are shown below.

By Howard A. Meyerhoff

Nonmetallic rock and mineral products are so diversified that any generalizations regarding the industries based upon them are of doubtful value and can be misleading. They are geared to every phase of the national economy and respond sensitively and immediately to any economic change, but the responses vary with the individual products. They are also affected by political and competitive factors to a degree that is disconcerting and, at times, ruinous to operators, owners, and stockholders of mineral properties. It is not unusual to find these special factors functioning in reverse of general trends insofar as individual products are concerned. As this summary is being written in the final weeks of 1949 production statistics for the year are not complete, but it is obvious that few, if any, new production records will be set, and that 1949 level, will, in general, be lower than those of 1948. The decline in output is not alarming and reflects in large part the tendency of users, who have been finding sources of supply more dependable to rely on prompt deliveries rather than on inventories to meet immediate needs. Except for the government's program of stock piling which, insofar as it has worked at all, is of more direct interest and benefit to foreign than to domestic producers, industrial inventories have been further reduced, and the neater balance between production and consumption has freed capital for the manufacturer and has cut down the serious hazard of substantial inventory losses. There are no quantity products and only a few special products that cannot be supplied in quick response to current demands. Normal development of a few nonmetallic industries has been retarded by the government's unpredictable application and irrational interpretation of antitrust laws, and by extension of preferential tariffs to new countries and new products. Synthesis is likewise a potent threat. in certain fields, but otherwise it is difficult to make a review of 1949 read much differently from a review of 1948. Changes have been qualitative rather than quantitative, except for a few operations that have been pinched out by the relentless competition that characterizes many of the industrial mineral industries.

Jan 1, 1950

By A. J. Opinsky, J. L. Orehotsky, L. L. Seigle

TUNGSTEN incandescent lamp filaments possess a typical structure of elongated crystals generated upon heating the silica-alumina doped wire rapidly to 2200°C or above.&apos; It is known that these very long grains exhibit a preferred orientation, but there is disagreement in the literature about the direction. Rosi,2 and later Rieck; reported that the <135> direction of the large grains in doped wire tends to be parallel to the wire axis, but other investigators have reported that <110> is the preferred direction. Some further investigation of the orientations of large grains in tungsten wire is reported in the following. In the first series of experiments, 6-in. lengths of wire were heated rapidly in a bell jar. Current was passed through the wires and within 15 sec the wires had reached the grain coarsening temperature. 2 min was the annealing time. Wires were heated in hydrogen, nitrogen, and vacuum. Later, wires were heated in an evacuated tube furnace in which the tube was brought from 1000°C to the operating temperature within 25 sec and held 5 min at temperature. Temperatures were measured with an optical pyrometer. After heating, the wires were electro polished and etched, and the orientations of the large grains determined by the Laue back-reflection technique. Most of the experiments were carried out on a single spool of 5-mil silica-alumina doped wire, but a few tests were made with 5-mil thoriated tungsten wire and 10-mil undoped wire. 5-mil silica-alumina doped wires were reduced to smaller diameters by electropolishing for one series of experiments. Orientations of the large grains in silica-alumina doped wire heated in various atmospheres are presented in Figs. 1 and 2 as plots of the direction of the wire axis relative to the cube axes of the crystals. For most of the conditions studied, the preferred orientation cannot be described as a single direction, but the points might be said to group themselves about the arc passing through <110> and <113>. This arc is the trace of the (211) planes and contains the <135> and <124 as well as <011> directions previously observed by other investigators. The preferred orientation of large crystals in silica-alumina doped tungsten wire might be most generally described, therefore, by stating that a (211 ) tends to be parallel to the wire axis. This is true also for wires reduced in diameter by etching and furnace heated, Fig. 2, i.e., the recrystallization texture is apparently unchanged upon removal of the outer layers and substantially independent of the temperature gradient within the wire.

Jan 1, 1962