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By D. Harker, E. Epremian

The constitution of the nickel-tungsten system has been studied by a number of investigators, the most recent of which are Ellinger and Sykes.1 On the basis of metallography, electrical resistivity and hardness measurements and some X ray diffraction work, they constructed a consitution diagram (Fig 1). Ellinger and Sykes report a0 for the alpha face-centered cubic phase (nickel saturated with tungsten) as 3.66?.‡ The gamma phase (tungsten saturated with nickel) is given as body-centered cubic, but no value of a. is recorded. At 43 pct tungsten by weight (approximately 20 at. pct) a beta phase is reported, but structure and lattice parameter are not known. Primarily on the basis of metallographic evidence, they conclude that beta is a new phase and rule out the possibility of formation of a superlattice since they- observe a new phase in the microstructure. Grube and Schlecht2 report an ordering reaction in a system similar to the Ni-W (Ni-Mo) and Harker3 has shown that NirMo forms a superlattice upon the pre-existing face-centered cubic lattice of the alpha phase. Elliniger arid Sykes observed a change in the diffraction pattern of a 4.3 pct W alloy upon aging and attributed it to the formation of a new phase. Thus, there appears to be some question as to the character of the beta phase reported by Ellinger and Sykes. The purpose of the present work is to determine precisely the structure and nature of the beta phase in the Ni-w system of X ray diffraction methods. Experimental Procedure One inch diameter ingots of 43.66 pct, 40.15 pct and 34.06 pct .tungsten by weight (19.8, 17.6 and 14.1 at. pct respectively) were melted and cast under vacuum from electrolytic nickel and pure wire filament grade tungsten. The ingots were soaked for 16 hr at 1300°C in a hydrogen atmosphere furnace, then swaged at this temperature and finally drawn to 0.020 in. diam wire. Some of the bar stock was retained in 1/2 in. diam rod for hardness and metallographic studies. Wire samples for diffraction work were sealed in evacuated quartz tubes and subjected to the various solution and aging heat treatments in a hydrogen furnace. X ray photograms were taken in a Debeye-Slierrer camera using copper K radiation filtered by nickel foil. Results X RAY DIFFRACTION The lattice parameters of the alpha and gamma phases at saturation were determined by an X ray photogram of the 19.8 at. pct W alloy after solution heat treatment at a temperature well within the alpha-gamma range above the peritectoid temperature (17 hr at 1150°C—oil quenched). The alpha phase was found to be face-centeted cubic with a. of 3.594 ± 0.001?, while the gamma phase was determined as body-centered cubic with a. of 3.158 ± 0.001?. Exactly the same phases and parameters were ohtained with the 17.6 at. pct W alloy for the same solution heat treatment. Thorough analysis was made of an X ray photogram of a 19.8 at. pct alloy sample in the quenched and aged condition (solution treated 1T hr at

Jan 1, 1950

By Forbes Rickard

Gilpin County, the cradle of mining in Colorado and the Cornwall of North America, is too well known to need much introduction; get, for the benefit of those not familiar with the district, it may be well to premise that it comprises a tract of country of about 122 square miles, lying between the counties of Jefferson, Boulder and Clear Creek, and hounded on the west by the main range of the Colorado Rockies. It is located centrally in the State, 40 miles west from the city of Denver. During the 38 years since the first gold-discovery, Gilpin county has contributed about eighty million dollars in gold and silver to the world's supply of these metals. Many mining districts have had their rise and decline in half this time; but, very far from being exhausted, this mining district is still in the ascendant; its output is increasing (it was $3,600,000 for the year just closed), and it was never more prosperous nor productive than to-day. Taken generally, there does not exist anywhere in the world so great a number of permanent veins within so small an area as in this district. Gilpin is practically a " poor man's camp." Its veins, with few exceptions, outcrop at the surface. In the oarlier---days of the camp these outcrops were worked in many instances by sluice-mining; particularly is this the case with regard to the veins of the Russell gulch. Discoveries are still made in the heart of this district, and the productive area is every year extending its limits. The districts of Yankee Hill, Hawkeye and Pine Creek, which used to be isolated, are now part and portion of the one gold-field of Gilpin county. Within the last year sensationally rich gold-discoveries have

Jan 1, 1899

By Richard McCaffery

WHEN we began the study of blast furnace slags we limited our work at first to a study of those slags containing only lime, alumina and silica. On our paper1 on some of the results of this first work, the solubility of sulfur in slags containing no magnesia was reported and the question of sulfur solubility and slag viscosity discussed. There has been, for a long time, a very great difference of opinion among metallurgists as to he effect of magnesia in blast furnace slags, and the literature is full if expressions of the most contrary opinions on the subject. As a result, our next publication' developed the constitution of slags considered as a four-component system, silica-alumina-lime-magnesia, and advanced an explanation of slag structure which accorded with the facts and with scientific theory. The present paper continues our study of the general subject of slags. As blast furnace slags are included in the silica-alumina-lime-magnesia system, which is a particular case of four-component solutions, we have determined that there are 22 components Table 1), which may enter into the silica-alumina-lime-magnesia system and that 10 or 12 of these components may be present in blast furnace slags which are within the ordinary ranges of composition. To cave a very definite conception of the behavior of these components in a slag, we have developed the theory of the cooling of a four-component solution from the liquid state to the solid and the conclusions that we obtained have been made use of in this paper. On account of the importance of the four oxides and 18 compounds which enter into the silica-alumina-lime-magnesia system, some method of calculating the percentages of the various compounds that are present in the slag when the percentages of the oxides are given, seemed very desirable and we develop L method later herein for doing this, and finally we give illustrations of the composition of a wide series of blast furnace slags and show some applications of these composition data.

Jan 1, 1927

By Walter Harvey Weed

CONTENTS. [ ] INTRODUCTION. THIS paper deals with certain ore-deposits whose structural features or mineral contents (or both) result, directly or indirectly, from igneous intrusions and their after-effects. It is largely a discussion of contact metamorphic ore-deposits based upon the physical changes in rocks due to contact action. It involves a classification of ore-deposits only so far as is abso-

Jan 1, 1913

By J. A. Goebel, S. Rosen

IN the NiAl phase diagram the NiAl (CsC1-type) phase field extends over a large composition range. At elevated temperatures the nickel-rich phase boundary extends to a composition of about 70 at. pct Ni, a value which is within 5 at. pct of the Ni3A1 (Cu 3 Au-type) phase boundary.' At room temperature, however, the maximum nickel content is only about 60 at. pct. Experiments have shown that alloys containing greater than 63 at. pct Ni when quenched from temperatures below 1000°C contain the equilibrium phases NiAl and Ni3A1. On the other hand, when these same alloys are quenched from temperatures above 1000°C and examined microscopically, a typically martensitic decomposition product appears in the microstructure as shown in the micrograph of Fig. 1. The structure of the martensitic phase has been determined by employing powder X-ray diffraction techniques to be an "ordered" AuCu type (Strukturbericht Llo, space group P/4 mmm - DL). The diffraction pattern of this phase differs from that of AuCu in the appearance of superlattice lines. The structure is shown in Fig. 2. The open circles represent nickel atoms and the half-shaded circles represent nickel and aluminum atoms which are randomly distributed. The sites represented by half-shaded circles would be occupied solely by nickel atoms at a stoichiometry of Ni3A1. The alloys used in this investigation were prepared from 99.99 wt pct Al and 99.99 wt pct Ni by arc melting charges of varying compositions in a water-cooled copper hearth using a tungsten electrode in a gettered argon atmosphere. In all cases chemical analysis agreed within $ at. pct with the nominal compositions of the alloys. Annealing treatments were carried out in a vertical resistance furnace through which a stream of argon gas was flowing. Specimens, which were wrapped in tantalum foil, were quenched by allowing the specimens to drop into a bucket containing iced brine. X-ray diffraction patterns were obtained from -325 mesh powder specimens by using a 114.8-mm

Jan 1, 1969

By W. Gundaker, F. C. Schwerer

Natural chromium-bearing spinels (chromites), which are used as refractory materials in basic steelmaking, are the only commercially important chromium ore and are also encountered as difficult-to-separate contaminants in ore deposits of potential economic value. Techniques for characterization and separation of ore materials frequently are dependent on the magnetic properties of the constituent minerals. An experimental program was initiated to explore the effects of temperature and of simple mechanical and thermal treatments on the static magnetic properties of several ore-grade natural chromites. Studies of the temperature dependence of the magnetic properties showed that the natural chromites, which are dilute in the magnetic ions Fe and Cr, order magnetically only at cryogenic temperatures. However, mechanical treatment in the form of crushing produces a magnetic component that is ordered at room temperature and that is of sufficient strength to alter magnetic-separation characteristics. The additional magnetic component apparently is associated with surface structures which develop during crushing and disappear after heating to above about 500°C. Preliminary studies indicate that this surface structure enhances the susceptibility of the chromite grain surfaces to gas reactions at moderate temperatures.

Jan 1, 1976

By M. J. Marcinkowski, D. B. Crittenden, A. S. Sastri

A study co.mbining stress-strain .measurements in conjunction with transmission electron microscoPy has been made with near equiatomic Fe-Cr alloys which were aged for various times at 500°C. Associated with this aging is a marked increase in deformation twinning. The outstanding feature of these twins is that they generate stress fields sufficiently great so as to give rise to spontaneous dislocation loop nucleation nearly normal to the propagating twin. This observation is in agreement with the theoretically predicted elongation of the stress field of a dislocation Perpendicular to its direction of motion as it moves near the speed of sound. Dislocation loop nucleation is more difficult in the longer aged alloys so that this energy absorption mechanism is not effective in hindering twin propagation. Since crack nucleation can readily occur near the tip of a twin, the aged alloys become extremely brittle when deformed in tension. Iron-chromium alloys in the vicinity of the equiatomic compositions become severely embrittled when aged at about 500°C. Fisher et 01.' have shown that this embrittlement is related to the decomposition of the original random Fe-Cr solid solution into a chromium-rich and an iron-rich phase. In addition, Mar-cinkowski et a1.' have shown that twinning becomes an increasingly more important mode of deformation as the aging time is increased. These results have been recently corroborated by the transmission electron microscopy study of Mima and amauchi . The Fe-Cr alloy thus seems ideal for verifying the predictions made in Parts I4 and 115 of this investigation where the behavior of large static or blocked twins and those of large dynamic or propagating twins, respectively, were investigated numerically. It was thus decided to measure the stress-strain curves generated by embrittled alloys that were aged for various times and to examine sections by transmission electron microscopy. EXPERIMENTAL PROCEDURE Electrolytic iron and electrolytic chromium were vacuum-melted and poured into ingot form. The composition of the resulting alloy was found to contain 46.0 wt pct Cr (47.8 at. pct), the remainder being iron. The resulting ingot was swaged above 850°C into 0.250-and 0.400-in.-diam rounds. Compression samples of 0.250 in. diam and 0.400 in. long were cut from the smaller-diameter rounds. These samples were then sealed in evacuated quartz tubes and annealed for 30 min at 1150°C to produce a uniform and equiaxed grain size of mean diameter equal to 1.73 mm. They in turn were rapidly quenched from 850°C so as to preserve the condition of random solid-solution characteristic of the elevated temperature. The samples were then aged for various times up to 300 hr at 500°C in a massive Pb-Bi alloy bath. The samples were next polished and tested in compression at room temperature as described in Ref. 6 using an Instron tensile testing machine. The strain rate used was 0.05 in. per in. per min. The remaining larger round was converted into compression specimens of 0.325 in. diam and 0.500 in. long. This larger diameter enabled wafers of sufficient size to be prepared for examination by trans-mission electron microscopy techniques after subjecting them to a suitable strain. Foil preparation is described in some detail in Ref. 6. All foils were examined in a type HU-11A Hitachi electron microscope operating at 100 kv. RESULTS AND DISCUSSION Fig. 1 shows the effect of aging at 500°C on the room-temperature stress-strain curves of the FeCr alloys. For greater clarity the origin of each curve has been displaced upward. The same origin has been used for both the 0 and the 0.1 curves. It is apparent that with increased aging times a sharp drop in load is observed at the yield stress which becomes more pronounced as aging proceeds. A loud sonic burst accompanies this drop and subsequent metallographic examination shows the sample to contain numerous twins. For intermediate aging times, a number of smaller twin bursts follow the initial large one. The total plastic strain associated with the twinning mode of deformation can be obtained by adding up the contributions AE~ from all i twin bursts, i.e., £,¦££,-, in the manner illustrated schematically in Fig. 2. The contraction of the specimen, as measured from the strip chart of the Instron, after suitably correcting for the elasticity of the machine, was converted into true strain using the assumption that there was no volume change and that the sample remained cylindrical. The dashed lines are all drawn parallel to the

Jan 1, 1970

By Howard Evans

Moderate but substantive gains were recorded in 1972 in the minerals processing industry. In the area of mill design, a number of large plants under construction during the past two to three years were tuned up and went into production. The application of operating controls has also made some significant strides. Progress here has been made in the areas of on-stream particle size analysis, on-stream x-ray analysis, slurry transportation, tripper control, flotation reagent control and digital control of grinding circuits. The major contributions to improved equipment are coming from smaller specialized equipment makers.

Jan 2, 1973

By R. S. Wagner, H. Brown

Criteria for nucleation with the aid of twin planes during crystal growth from the melt are discussed. It is shown experimentally that bismuth crystals can grow from a subercooled melt in a twinned bismdtic form. A mechanism of growth based on the presence of at least me twin plane is proposed. It is well known that faceted growth can be observed in crystals grown from the vapor phase, dilute solutions, or from the melt. Faceted growth, in which the crystal is bounded by its slowest growing faces, will occur if the growth rate is strongly orientation dependent. The addition of atom layers on a facet plane can only occur by two-dimensional surface nucleation or with the aid of an imperfection. Nucleation with the aid of dislocations was proposed by rank' and observed to be of particular importance in crystal growth from the vapor phase. Nucleation with the aid of two-dimensional imperfections, notably twin planes, was suggested by stranski2,3 and Frank.4 A twin plane, terminating at the growth interface, can form a reentrant step at which nucleation can occur at a much smaller super-saturation (or supercooling) than required for two-dimensional surface nucleation. Nucleation by a twin plane usually results in a fast growth rate along a crystallographic direction parallel to the twin plane. Such a nucleation mechanism, based on the presence of a twin plane, has been used by Dawson5 to explain the growth and morphology of sheet-like crystals of paraffin n-hectane. In recent years more evidence was found that nucleation by twin planes occurs frequently in crystal growth from the vapor phase and from dilute solutions, for example, in cadmium,' barium titanate,7 silver,8 silicon9 and gallium arsenide.10 In crystal growth from a supercooled melt, however, nucleation by twin planes has so far only been observed in materials with the diamond or zinc blende structure. Bennett and Longini11 were the first to recognize the important role a single twin plane plays in the growth of germanium dendrites. Subsequently, it was found that a prerequisite for continued propagation of germanium dendrites is the presence of two parallel twin planes which form a self-perpetuating system of nucleation sites.12 Sili- con and some III-V compounds such as InSb also grow dendritically by twin plane nucleation. It appears that the following criteria must be satisfied in order that nucleation with the aid of twin planes can occur: A) The growth form of the material must be faceted." B) The formation of twin boundaries, by a fault in layer sequence during growth, by plastic deformation, or by an accidental meeting of properly oriented crystals, must be possible. C) Twinning must form a reentrant step where the twin boundary terminates at the faceted growth interface. D) These three conditions are necessary, but in certain cases not sufficient for continued crystal growth with the aid of a twin plane. Depending on interface morphology, a combination of more twin planes is sometimes required to form a self-perpetuating system of nucleation sites. This investigation was carried out with the idea in mind that nucleation with the aid of twin planes is a more general phenomenon and should occur in those materials, grown from a supercooled melt, which satisfy the criteria outlined above. It has been found that crystals of high-purity bismuth grown from a supercooled melt can grow by the aid of a twin plane. In the first two sections the faceted growth form and the twinning elements of bismuth are discussed. In the last section prismatic crystals of bismuth, which appear to grow with the aid of a deformation twin are discussed.

Jan 1, 1962

By David A. Thomas, John F. Peck

Fibrous microstructures and their development have been studied by metallography and by hardness and quantitative metallographic measurements. Thin, curved grains were observed in transverse sections of commercial tungsten wire and were developed in laboratory-drawn iron wire at reductions greater than about 70 pct. The unusual grain shapes are attributed to the nonuniform mode of deformation of the grains associated with the characteristic [I101 preferred orientation that develops in bcc metals during drawing. Transverse sections of heavily swaged iron wire showed a ospiral nebulao structure that appears to result from the elliptical shape of the cross section of the swaging dies and their rotary motion. Hardness and quantitative metallographic results show unusual trends that parallel the changes in microstructure. Other phenomena are considwed in light of the results, including the strength of fine wires of bcc metals, ocylindricalo textures, and the ductility of fibrous tungsten. 1 HE microstructure of tungsten wire in a longitudinal section shows grains highly elongated in the working direction, giving the appearance of a bundle of parallel fibers, Fig. l(a). Wires of tungsten and other bcc metals show a pronounced preferred orientation in which a [I101 direction is parallel to the wire axis.l The microstructure and texture of tungsten develop during warm working (working above room temperature but below the recrystallization temperature) into wire by swaging and drawing. Fibrous tungsten so produced has limited but useful room-temperature ductility, whereas annealed tungsten is brittle at room temperature. During an investigation of the effect of recovery annealing on the substructure of commerical 0.030 in. diam tungsten wire, it was found that transverse sections of the as-received material showed thin, curved grains, Fig. 1(b), instead of the expected equiaxed grains. The fact that Figs. l(a) and (b) show different sections of the same material at the same magnification is at first disconcerting, because the long dimension of the curved grains in the transverse section is several times the average fiber width in the longitudinal section. However, a longitudinal section cuts most of the curved grains across their narrow dimension, giving the appearance of a multitude of narrow fibers. On the other hand, the plane of a longitudinal section occasionally includes a long dimension of a curved grain, resulting in a broad ofibero, such as A in Fig. l(a). EXPERIMENTS AND RESULTS To investigate the origin of fibrous microstructures and particularly the unusual transverse-section structure of tungsten, rods of iron (also bcc) were drawn and swaged in the laboratory. One rod of annealed Ferrovac E was drawn in six steps to a total reduction in area of 87 pct (0.10 to 0.036 in. diam), and a second rod was swaged to the same reduction, using approximately the same reduction steps. Longitudinal and transverse sections of the swaged and drawn iron wires are shown in Fig. 2, for reductions in area of 39, 73, and 87 pct. A fibrous microstructure in longitudinal section is first evident at 73 pct reduction, and it is further developed at 87 pct reduction. The grains in transverse section remain equiaxed until about 73 pct reduction, when they become somewhat elongated and curved. At 87 pct reduction, the drawn wire shows thin, curved grains in the transverse section, similar to those observed in tungsten. The transverse sections of the iron wires swaged 83 and 87 pct reduction in area show the striking ospiral nebulao structure in Fig. 2(d). This struc-

Jan 1, 1962

By D. J. Hawthorn

The widespread interest shown during the past year in the study of subsurface pressures warrants brief reference to its early development. Though it is impossible to set an exact date when constructive thinking on the subject first began, nevertheless, evidence is available that thought was given to the problem as far back as 16 or 1.7 years ago. There is record in one of the foreign journals of actual subsurface tests made by crude methods in one of the Rumanian fields in 1918 and 1919.' These tests were performed in conjunction with studies made on wells produced by bailing and, incidentally, the final outcome of the work led to the development of the so-called "duplex bailer" which is reputed to have trebled volumetric bailing efficiency. From this time on to 1927 a few scattered bottom-hole pressure determinations were made with makeshift instruments of one form or another, but probably not until 1927 was any great amount of concerted effort directed to the subject. At this fall meeting of the Petroleum Division four years ago was presented one of the first papers2 to appear in this country written for the express intent of advocating the value and importance of subsurface pressure determinations. It is thought to have been the first to present direct data on subsurface pressures obtained through the use of a specially designed recording instrument. As might be expected, the instrument had its limitations, but reasonably accurate results were obtained and, to say the least, it constituted a progressive step in the right direction. During the period from 1927 to 1931, many noteworthy improvements were made in the design and perfection of subsurface pressure instruments suitable to meet all conditions. Because of the magnitude of this task much credit is due the men who pioneered this work. They should feel a keen sense of satisfaction in the thought that their efforts have paved the way for the continuation of this most valuable study. At the present time more than a dozen companies are operating subsurface pressure instruments in the Mid-Continent field. Engineers in

Jan 1, 1933

By Stanley Herold

Considerable interest has been shown, during recent years, in the possibilities of developing oil fields in the South American Republics, now that the exhaustion of our present fields can be seen in the not very distant future. The demand for fuel oil and its products has been increasing far more rapidly than our increment of production during the last few years. Increase of consumption has been largely curtailed by the lack of sufficient supply. The main factors that have contributed to our previous neglect of the southern fields have been as follows:, (a) Lack of sufficient demand for the product. (b) Competition with producing fields, having large production, low cost, and better geographical position, such as Tampico, Mexico. (c) Greater interest in home fields with ready market at hand. (d) Our ignorance of southern economic and geologic conditions, clue to the distance between those areas and our financial centers. (e) Economic conditions in the southern countries, necessitating high costs of exploration and exploitation of the fields.

Jan 9, 1918

By Robert J. McKay, F. P. Huston, WILLIAM G. HUMPTON

THE manufacture of nickel-clad steel plate and the fabrication of articles from it has progressed far enough to permit a general description of the working methods used. The manufacture of sheets made up of layers of nickel and steel is not new as a sheet of this character was patented in Germany in 1893. Present development differs mainly in the size and finish of the product. The earlier light-gage highly finished products have been limited in their application due to their similarity, in certain respects, to electro-plated and highly finished alloy sheets. The new product is a relatively heavy plate 1/4 or 3/s in. thick and heavier, with one side coated with nickel, the weight of nickel being of the order of 10 per cent of the whole. The finish is that of hot-rolled steel plate.

Jan 1, 1931

By Walter O. Snelling

In the course of some experiments more than five years ago, made for a totally different purpose than the investigation of the oil used, I placed a small quantity of a transparent yellow lubricating oil in a bomb-like vessel and heated it to a relatively high temperature. At the end of the experiment I removed the oil from the vessel and was amazed to find that instead of bearing any resemblance to the oil which I had put in, it now had the appearance of ordinary crude oil. The green color by reflected light and the rich red-brown by transmitted light were so unmistakable as to at once lead to further investigation. I subjected the material to fractional distillation, and the surprise which I experienced at the appearance of the oil, changed to amazement when I found that it yielded, on distillation, 15 per cent. of gasoline and 30 per cent. of burning oil, and that its constitution resembled crude oil quite as much as did its appearance. Furthermore, the gasoline and kerosene distillates which it yielded were of a clear water-white color, entirely without treatment with acid or alkali, and were entirely free from the odor familiar in "cracked" petroleum distillates. The result of this experiment was quite too remarkable to be credited without further confirmation, and I at once filled the vessel with some of the same oil that I had used before, and again heated to about the same temperature that I had previously used, and for the same period of time. Upon opening the vessel and removing the contents I found, not the material resembling crude oil that I had obtained before, but apparently only the same oil that I had put in, somewhat darkened in color, but nevertheless far different in appearance from the material obtained in the previous experiment. Evidently some condition existed in the first experiment that had not existed in the second test, and here began a series of tests in which I sought by the change of one variable after another to arrive at the identical conditions which must have existed in the first experiment. Only the fact that the bottle of heavy oil used in the first test was still in its place,

Jan 1, 1915

By Luis Toron, Salvador Cortes-Obregon

John D. Price (Colorado Fuel and Iron Corp., Pueblo, Colo)—The paper on the coal fields of the Oaxaca district as prepared by engineers Toron and Cortes-Obregon of the staff of the Bank of Mexico bears witness to the thorough and careful way in which the men associated with this organization perform their work. There is little to be added to their paper in way of discussion other than to confirm and amplify some of their statements. Since the only extensive and well-developed field of coking coal lies in the northeastern section of the country adjacent to Sabinas in the state of Coahuila, it follows that blast furnace plants would be located in that same region. Two such plants are now operating at Monterrey and Monclova, using coke produced at the Sabinas district mines. But the nearer of these two plants is 600 miles from Mexico City and even farther from the center of population. Transportation of products from these mills to the market area is therefore expensive, both because of the distance and the difficulty of the terrain over which it must be carried. The development of an integrated steel industry closer to the center of population has therefore long been a goal toward which the Mexican technicians have been striving. While the presence of coal of some grade has been reported in many of the states, and many ideas have been advanced regarding its possible uses in iron and steel production, deposits of anthracite in Sonora and the various coals of the Oaxaca district as reported on in this paper are the only ones that have been explored in a serious manner. The coking coal from the Mix-tepec zone appears to offer promise of producing a coke which could be used in a standard blast furnace. Several problems are indicated, however: 1—The ash in the coal is high as mined, but indications are that it can be washed to an ash content of 15 pct with a recovery of 70 pct of washed coal. 2—Such washing would increase the volatile content from 17.4 pct to about 20 pct, and in a byproduct oven this should give a coke yield of close to 80 pct with an ash content of coke under 20 pct. 3—A free swelling index of 5 appears low for a good coking coal, and below that of the coals from the Sabinas district, which show between 6 and 9. But washing of the coal should result in an improvement in this regard; in the United States coals from Utah with an index even lower than 5 have made a usable coke. 4—A coal with volatile as low as 17.4 in raw coal and 20 in washed coal would come close to being classed as a low-volatile rather than medium-volatile coal, and low-volatile coals are notorious for their high expansion properties. Several plants in the United States are making coke from straight medium-volatile coal of 26 to 28 volatile content, and one at Rosita,, Mexico, from coal of 25 volatile. But no plants to my knowledge are using coal as low as 20 volatile. Since the Rosita coal appears to be a borderline coal from the angle of its expansion properties the coking of one of the straight lower volatile must be approached with caution. 5—There are few coals possessing any degree of coking properties which cannot be used in coke production by careful attention to its preparation and blending. The fact that coals of other types are available in this same region make improvement through blending very possible. 6—There are other workable methods of reducing iron ore other than the conventional coke-blast-furnace method. These will not be discussed here but it is known that their use has been considered. The technicians of not only Mexico but also of the other Latin American countries are keenly aware of their natural resources and their national needs. This paper emphasizes the fact that the Mexican technicians are working on their problem and attempting to speed the day of self-sufficiency for their country. Salvatore Cortes-Obregon (author's reply)—I wish to thank Mr. Price for his kind remarks. The Mixtepec coal as shown in Table II has 30 pct ash and a free swelling index of 5, but when the same coal is washed to 15 pct ash it has a free swelling index of 8 to 9 and the volatiles increased from 17.4 to 20.7 pct. A satisfactory coke has been produced from blends made in the Mexican laboratory using at least 40 pct of the Mixtepec coking coals with the other Oaxaca non-coking coals. Koppers in Germany report good coke obtained from the Oaxaca coal with a blend of 80 pct Mixtepec coal. Consideration is being given the possibility of using methods other than the conventional blast furnace for the reduction of iron ore near the Oaxaca area; electric furnaces appear promising. The non-coking coals could be used to produce cheap electric energy and the coking coals to make metallurgical coke.

Jan 1, 1955

By F. L. Bosqui

The history of the development of gold metallurgy in South Africa is divisible into two periods: That preceding the introduction of the cyanide process on a commercial scale in 1890; and the 24 years intervening between that important event and the present time. The period between the discovery of the banket reefs of the Witwaters-rand and the year 1890 was one of phenomenally rapid progress in mining development, but of no special interest to the metallurgist, There were no strikingly original or distinctly local advances in the treatment of gold ores. Californian practice in stamp milling and amalgamation prevailed, in mills ranging in equipment between 5 and 50 stamps, operating within a wide range of efficiency, and under the trying conditions usually encountered in a new and isolated field. The somewhat incomplete records of gold output of that period show that in December, 1887, there were 20 producing companies in the Witwatersrand district, of which 10 had mills, the largest being of 20 stamps. The only official record of returns for May, 1887, was that of the Wemmer mine, whose modest achievement with a 5-stamp mill was 100 tons crushed, producing 887 oz. 3 dwt. of gold. This is interesting in view of the present-day output of this field, which in 1913 reached 8,430,998 oz. The rapid increase of production during this first period (May, 1887, to January 1891) is shown by the following summary for the year 1890:1 Total tone crushed.................................. 702,828 Number of stamps in operation....................... 1,046 Average number of tons crushed per stamp per day..... 2.36 Yield of gold, ounces................................ 494,817 Yield per ton, pennyweights.......................... 13.36 The stamp duty ranged between 11/2 and 4 tons per day, according to weight of stamp, fineness of screen, and operating skill available. The prevailing weight of stamp was about 900 lb., and the screen, 900 meshes to the square inch.

Jan 1, 1916

President-Mrs John R C Mann, 90 Edgemont Road, Scarsdale, N Y First Vice-President-Mrs Earl H Bunce, Residence Park, Palmerton, Pa Second Vice-President-Mrs. W Clifford Bowden, Jr, 800 Midland Road, Oradell, N J Third Vice-President-Mrs F Edgar Kudlich, 521 Rutter Ave, Kingston, Pa

Jan 1, 1958

By James H. Boettcher

INTRODUCTION A complex interaction of worldwide economic and political forces is increasingly requiring 3 primary participants for the successful development of large natural resource projects in developing countries. They are the host government of the developing country (the "host government"), one or a consortium of international natural resource companies, (the "Resource Company") and one, or more likely, a syndicate of international lenders. The host government typically controls the rights to its country's natural resources and establishes the economic ground rules for their development. However, because of worldwide inflation and the depletion of easily accessible, high-grade resources, the nominal and real capital development and operating costs of projects have been spiraling. Moreover, the depletion of high-grade and mineralogically uncomplicated resources also raises the technical and operating risks associated with resource recovery. Thus, despite increasing political self-consciousness and economic nationalism in developing countries, international resource companies are still often necessary project sponsors since they can provide, among other things, the required technical and management expertise and equity capital. The presence of these factors, and often the addition of worldwide market access in a project, is often critical in determining whether or not the project will be considered creditworthy by international commercial lenders. The international commercial lender is often the critical third party in project development, due in a large part to the ever escalating-costs of project developments relative to the financial resources of many companies and even a growing number of countries. In addition, lenders have other reasons for taking more than a passive interest in all aspects of a project's development. These reasons include the following: 1. Projects are often financially structured such that the primary security for a loan, once completion and performance standards are met, is the cashflow of the project rather than recourse to its sponsors. 2. Lenders, in addition to the "project risk" just described, are frequently asked to assume various elements of "political" risk which nay put them in a sensitive economic position between the host government and international resource firms (This is discussed later). 3. International banks today have large loan portfolios of developing country debt with final maturities ranging from one to fifteen years. The various current projects undertaken are the building blocks of most developing country economies that will hopefully contribute to the long run economic development of a country as well as generate the foreign exchange necessary to repay foreign loans in the future. In this regard it is useful for lenders to realize whether a given project "makes sense" in terms of a country's natural resource endowments and competitive advantages over other countries. The type of framework discussed in this article would help lenders to better make such assessments. In order to facilitate the continued international flow of capital and technology to developing countries and of readily available supplies of raw materials from them, it is important for each of these three parties to increase its awareness of the goals and objectives of the other parties as well as the bargaining process that results in the legal, financial, credit and fiscal structures by which a joint venture project ultimately proceeds. Each of the parties faces increasingly complicated accept/reject decisions when they are faced with difficult choices among. a wide range of alternative structural combinations each of which has different implications for risk and reward to them. Therefore, by increasing the mutual, 3-way awareness of the decision processes of the other parties, it should be possible to: • provide better information and results in the formation of more rational expectations by all parties going into negotiations, • facilitate the project formulation process by allowing parties to focus more clearly on the areas of common interest and conflict, • result more frequently in final structures and agreements that better reflect the economic and political realities associated with a project and thus • result in more creative, innovative agreements that should reduce the need for changes to them and thus promote the kind of long run political stability conducive to attracting capital and further investment.

Jan 1, 1982

By B. R. Hollebone

The chemical action of molten anhydrous pyridinium chloride (pyridine hydrochloride) on oxy salts and ores of some Group IV and V metals are discussed-in particular zirconium, hafnium, niobium (columbium) , and tantalum. Laboratory-scale experiments are described whose results suggest that this reaction might provide a practicable means of converting ores of these metals to the anhydrous metal chlorides. Experimental results are given which provide some insight into the nature of the reactions and some of the compounds which could be present at intermediate stages. The treatment of ores of the more refractory metals is difficult and expensive and often demands the use of gaseous chlorine, hydrogen fluoride, or other reagents which are, if nothing else, expensive and dangerous to use. This situation is, of course, due to the strong metal-oxygen affinity resulting from the high charge and the small size of the metal ion which combine to produce such high lattice energy in the metal oxide as to defeat standard reduction methods. Thus, the characteristic of these metals which leads to one of their most important properties—corrosion resistance—is the main hurdle in obtaining the metal. Many common methods' for treating ores of zirconium and niobium (columbium), for example, proceed as directly as possible to the preparation of anhydrous halides. These halides are purified by now standard processes of solvent extraction, fractional distillation, and so on. This paper reports on preliminary stages in the development of a method of treating these ores—particularly of niobium—so as to prepare the anhydrous, volatile halides by the use of chemical reagents which are much more easily handled than those used at present. CHEMICAL PRINCIPLES The solvent action of aminium halides has been referred to periodically in the literature over several decades. The chemistry of pyridinium chloride has been discussed particularly by Audreith2 and Starke.3 However, since this is not familiar chemistry in its nonaqueous setting, it is perhaps well to point out some general metallurgical principles and applications. One can use, as point of departure, the fact that HC1 dissolved in pyridine is an acid very much the same as aqueous HC1. It thus gives essentially all the reactions of the HC1 with which we are familiar. However, when the ratio of HC1:pyridine reaches 1:l (a ratio far higher than is possible with H2O) the solution becomes solid C5F5NHC1, pyridinium chloride.* Inter- estingly, the acidic properties of HC1 persist in this medium, although they are manifest only in the molten state of the compound. Some typical reactions of divalent metal compounds which we have carried out in our laboratories are the following: 2PyHCl + Zn — (ZnCl2) + H2 + 2Py 2PyHCl + MnO — (MnCl2) + H2O + 2Py 2PyHCl + CuS — (CuCl2) + H2S + 2Py 2PyHCl + CaCO3 — (CaCl2) + H2O + CO2 + 2Py In these equations, the parentheses indicate a solvated compound which in water would be predominantly a hydra ted cation but which in molten PyHCl will more likely be a complex chloro-anion of the type MC14-. Some important physical properties of pyridinium chloride (PyHCl) are given in Table I. One sees from the data in Table I that at the temperature of molten pyridinium chloride both water and pyridine will boil away. Thus the system will be kept anhydrous. For this reason the reaction 2NbCl5 + 5H2O— Nb2O5 + 10HC1 has no counterpart in molten PyHCl. Instead, the chloride is made even more stable by the formation of a hexachloro complex: Nb2O5 + 12PyHC1 — 2PyHNbC16 + 5H2O + 10Py One interesting property of these complexes is their thermal instability which for the case of niobium can be illustrated as PyHNbCl6 — PyHCl + NbCl5 With a view to possible use of this chemistry in ore treatment, we have attempted to dissolve Pyrochlore (essentially FeO - Nb2O5) and recover the NbC15 from it.

Jan 1, 1968

By J. T. Norton, H. Blumenthal, S. J. Sindeband

The interstitial phases formed by the transition elements with carbon, nitrogen and boron constitute a unique class of substances which are of considerable technical interest because of their well developed metallic properties and their high hardness and melting points. They are also of interest from the point of view of structure. It was pointed out by Hagg1 some years ago that the principal factor determining these structures was the relative sizes of metal and metalloid atoms. He predicted that if the ratio of the radii of metalloid to metal atoms was less than 0.59, the metal atoms would be arranged in a close-packed fashion of relatively simple type. This prediction has been amply confirmed. It appears, however, that this specification applies most generally to those structures in which the metalloid atoms occupy isolated positions in the lattice and there is no tendency for strong binding between the metalloid atoms themselves. The series of borides of the type MeB2 formed from the transition elements of the fourth (Ti, Zr) and fifth (V, Cb, Ta) groups of the periodic table provide an opportunity to investigate this situation further. If one takes as a basis the radius of 0.87 A for the boron radius and the Goldschmidt values for the metal atoms in 12 coordination, then the radius ratio varies from 0.54 for zirconium to 0.64 for vanadium, which latter is considerably greater than Hagg's limit of 0.59. It was of interest, therefore, to see if these five elements would form borides of the MeB2 type and have simple isomorphous structures. When this investigation was initiated, relatively little information had been published on the structure of this group of borides. McKenna2 reported the preparation of ZrB2 by a carbon reduction process. Its structure was hexagonal and the approximate lattice constants were given as a = 3.15 A, c = 3.53 A. Ehrlich3 reported the structure of TiB2 as being of the C 32 type with a = 3.02, c = 3.21 and c/a = 1.06 A. Recently, Kiessling4 published the results on ZrB2, showing it to be one in which the metal atoms are arranged in a simple hexagonal lattice with the boron atoms in flat sheets, midway between the layers of metal atoms. The structure is C 32 type with a = 3.169, c = 3.530 and an axial ratio =1.11 A. He also states that CbB2 and TaB2 are isomorphous with ZrB2. Preparation of Borides The borides of titanium, zirconium, columbium and tantalum were made by the electrolysis of fused salt baths after the method described by Andrieux.5 The bath, totalling about 6500 g in each case had the following general composition: Metal Oxide + B2O3 + CaO + CaF2. The actual proportions of the ingredients were determined for each individual case. Although Andrieux reports the preparation of vanadium boride by the same electrolytic method, several attempts proved unsuccessful. However, it was possible to prepare VB2 by the carbon reduction method used by McKenna to produce ZrB2. The mixture consisted of V2O5 + 6B2O3 + 11C and the reduction was carried out in an induction heated graphite crucible. This method proved satisfactory for ZrB2 and TiB2 and undoubtedly the others could be made in the same way. The borides, which were all in the form of fine gray metallic crystals from the electrolytic bath or gray powders from the reduction process, were carefully separated from other constituents and analyzed chemically for metal and boron content. The densities of the boride powders were measured using a standard 10 cc pyenometer at 18°C and ethyl benzene proved to be the most satisfactory liquid for this purpose. X Ray Technique The boride crystals, as prepared, were too small for single crystal examination so that powder techniques were employed. Patterns of the finely ground borides were prepared, using the Norelco recording X ray spectrometer. The lines on these patterns were indexed with the aid of Hull-Davy charts and the approximate dimensions

Jan 1, 1950