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By H. A. Wilhelm, P. Chiotti, G. A. Tracy

A summary of analytical, X-ray, thermal, and metallographic data obtained in the study of the Mg-U system is presented. No intermetallic compounds are formed by these two elements, and their mutual solubility is limited at temperatures up to 1255°C. The compositions of the liquids which coexist at 1135°C under a pressure of 3 atm are 0.14*0.05 wt pet U in magnesium, and 0.004 wt pet Mg in uranium. The solubility of uranium in magnesium decreases to 0.0510.03 wt pet at 675OC, and to about 0.0005 wt pet at 650°C. Due to the reactivity of both uranium and magnesium toward crucible materials, the choice of a suitable crucible presented a problem. Crucibles made from high purity magnesia to which 10 wt pet MgF2 was added to reduce porosity proved to be satisfactory. Some observations made with the use of other crucibles are given. THIS investigation was made to establish the phase diagram for the Mg-U system. Ahmann,' formerly of the Ames Laboratory, did some work on the system. He used several methods in an attempt to prepare Mg-U alloys. One of the methods involved the reduction of UF, with a large excess of magnesium. In these experiments, the magnesium wet the surface of the uranium, but there was no evidence for compound formation. The maximum solubility of magnesium in uranium was indicated to be 0.01 wt pet. In another set of experiments, uranium chips as well as uranium powder were heated in contact with molten magnesium in a graphite crucible for periods of time up to 48 hr. A reaction layer was found at the Mg-U interface in several instances. X-ray analysis of the layer material showed the presence of UC and some additional unidentified lines which were interpreted as indicating the possibility of an intermetallic compound of uranium and magnesium. These studies indicated the maximum content of magnesium in uranium to be 0.043 wt pet. One sample of magnesium which had been heated at 1025°C in contact with excess uranium was found by chemical analysis to contain 0.275 wt pet U. Rules, based on empirical or semi theoretical considerations, which attempt to predict the alloying behavior of metals have been presented in the literature. Although these rules are not infallible, they nevertheless serve as useful guides. Using them, several generalizations can be made concerning the Mg-U system. According to Hume-Rothery's' atomic

Jan 1, 1957

By N. A. McKinnon, J. H. Auld, A. M. Marshall, R. A. Coyle

IN making a study of the slip deformation and strain hardening of single crystals of aluminum, it has been found that considerable information additional to that provided by the usual metal-lographic techniques can be obtained by the use of the microfocus X-ray method described by Schulz.1 This technique has been applied to crystals both in the state as-grown by the strain-anneal method and after they have been subjected to increasing amounts of plastic strain. Kelly and Wei" have recently reported the use of this method for a study of lineage structure in aluminum single crystals grown from the melt. The crystals, prepared from aluminum of 99.99 pct purity supplied by British Aluminium Co. Ltd., were grown in the form of flat tensile specimens with a gage section of 0.3 by 0.1 in. and a gage length of 2.3 in. The microfocus X-ray tube used provided a focus of approximately 50 half width. Examination of a large number of as-grown crystals showed no sign of any macroscopic defects in the majority of cases. However, occasionally crystals grown by the strain-anneal method did show defects similar in nature to those shown by Kelly and Wei to occur in crystals grown from the melt. In some other cases a more regular appearance of black and white lines, corresponding to valleys and ridges, respectively, in the lattice, was obtained, Fig. 1. This particular crystal was slightly deformed as the lines when present in the image of an as-grown crystal are only barely visible. The angle of tilt of the blocks is of the order of 3. It seems likely that these tilt boundaries arise during the growth of the crystal due to the specimen not being perfectly flat on the hearth of the furnace and straightening under its own weight at the elevated temperatures. For the deformation studies the crystals were strained in a Polanyi-type tensile machine. A typical photograph taken after 1.2 pct elongation of a single crystal oriented with its axis fairly close to the center of the stereographic triangle is given in Fig. 2. The reflection, which is from the (111) planes, is traversed by two systems of parallel lines. These have been identified as traces of the primary (111) slip plane and the (110) plane perpendicular to the primary slip direction. The latter lines correspond to kink bands which could not be detected by the ordinary techniques of

Jan 1, 1958

By Eugene Grace

IN THE careers of the men to whom I have referred we find typified the development of the chief prob-lems of engineering. The first is to shape and direct the forces of nature and thus to bring the world's resources to add to the comfort and welfare of man-kind. That, in a word, is the problem of production. Engineers have made a supreme contribution to the solution of that problem. But I feel that we have two somewhat newer branches of engineering which must command more and more of our attention. Those are what might be termed commercial and human engineering. Of what value is all our efficiency in pro-duction if we do not distribute efficiently, economically and effectively? And of what value is any of it unless we can add to the happiness and deeper satisfaction of those engaged in industry, as well as those who enjoy its -products? I predict that the outstanding advances in business over the next ten years will be in improved merchan-dising and distributing methods. Herein lies a wide field of opportunity for the engineer. We have briefly reviewed certain qualities of engi-neers who have become successful business executives. Is it possible for us to say that the material success of all these men was due to any one characteristic com-mon to each one of them? Indeed, I venture to assert that there is one quality which, in the last analysis, is determining as to whether any roan shall realize material success in this world of ours. That quality-so notable in the character of each one of the men I have named-is sound judgment. Moments arise in every life when it is necessary to say "yes" or to say "no" to a particular proposition or to a proposed line of action. It is the man who says "yes" at the proper time and "no" at the proper time who, in the final analysis, realizes business success. The ability to do this wisely is the mark of sound judg-ment, which is necessary in a business executive. I have known many business men seemingly slow in their mental processes, possessed apparently, of little imagination and of none of the flair which gives fasci-nation to so many characters, and yet who, when crises come-be they big or be they little-are able so to steer their business courses that they move in the right direction instead of into shallow waters or upon the rocks of trouble.

Jan 4, 1928

By Raymond C. Johnson

GASIFICATION is important to the anthracite industry, as it is to the entire solid-fuel industry and to the nation. However, to the anthracite industry it may have particular significance in that it would increase the market value of many millions of tons of a by-product fuel, which the industry now has in storage and is currently producing, in addition to increasing the potential market for all its products. The by-product fuel is of usable quality but the ash content is higher than it can be in other products and therefore it must be converted or used at the point of production. Gasification is one method by which the product may be given increased value. The inherent characteristics of anthracite make it well suited for producing a fuel or synthesis gas. It is the most concentrated form of natural commercial carbon, noncaking and noncoking; it does not produce smoke, tar, or soot and has a low sulphur content; and the volatile matter, which ranges between 2 and 8 pct, is 80 to 85 pct hydrogen with small amounts of methane, carbon dioxide, carbon monoxide, and nitrogen. The ash fuses at high temperatures, which allows it to be burned at high rates without slagging. However, with the addition of small amounts of dolomite, the ash will form a slag, or glass, which is very fluid. Anthracite has long been used in the manufacture of city gas and it is extensively used in various parts of the country to make water gas to be converted to hydrogen. Buckwheat and rice anthracite are used in Galusha producers to make producer gas. Excellent synthesis gas has been made in a Galusha producer with rice and barley anthracite with oxygen in tests at the Consolidated Mining and Smelting Co., Trail, British Columbia. In these tests, anthracite was shown to have advantages over competitive fuels, in that the gas had a higher hydrogen content and could be cleaned with less difficulty. The anthracite seams are steeply pitching and in mining the parting strata and some of the roof and bottom materials are taken with the coal. In preparation, these materials are separated by gravity from the commercial product and stored in refuse banks. This refuse contains a mixture of rock, slate, or shale, and high-ash anthracite with bone coal, which is low-ash coal that is interspersed with thin bands of shale. The bone coal contains between 25 and 50 pct ash with an average ash content of approximately 30 pct, with a

Jan 1, 1953

Frontino operates three underground lode mines at Segovia in the area of northwest Antioquia, Colombia, which has been an important gold producing district since the late 1800s. Auriferous pyrite, the pre-dominent sulfide, carries very finely disseminated gold. Other minor sulfides are galena, pyrrhotite, and sphalerite in quartz gangue with the host rock being granodiorite. Silver is associated with the galena and also occurs as a sulfo-salt. In 1.973 and 1974, at an annual milling rate of 145,000 mt (160,000 st), average mill heads were 7.80 g per mt (0.23 oz per st) Au; 20.0 g per mt (0.58 oz per st) Ag; and 0.37% Pb; with a production of 1,150 kg (35,700 oz) Au and 4,500 kg (141,000 oz) Ag. Over 300 mt (330 st) of Pb concentrate were shipped. The ore is crushed to minus 16 mm (5 18 in. ) and fed to a rod mill with the discharge passing over a 1.07 m by 1.07 m (42 in. by 42 in. ) jig operating in closed circuit with the underflow from a cyclone in closed circuit with two ball mills. Cyclone overflow is bulk-floated for sulfide recovery from which the tailings are sent to the river as waste with the flotation concentrate joining the jig concentrate for cyanidation. The combined gold bearing concentrates, after cyclone classification, are reground to a very fine mesh in closed circuit with cyclone classification, with the overflow going to the primary thickener. Regrinding, classification, and thickening is done in cyanide solution, and the primary thickener produces a pregnant solution for Merrill -Crowe precipitation. The thickener underflow is the feed to the agitators, thickener, and filter from which the overflow and filtrate are sent to precipitation. The washed filter cake is repulped and floated for the recovery of a galena concentrate for shipment. About 40% of the recovered silver is in this concentrate. In the refinery the precipitate is melted into a dore bullion. This 600 mt (660 st) capacity mill employs several interesting techniques. Gold recovery of 85% to 90% from a complex sulfide denotes good practice. While total power at 42 kwh per mt (46 kwh per st) is high, it would be recognized that the grinding units are small in size and the flowsheet is complicated due to the gold occurring in the sulfide minerals. The extremely low-cost electric power is generated by

Jan 1, 1981

By John Randall

It is a fair assumption that the main purpose of any diagram is to present facts to the eye in more convenient form than they could be tabulated in figures, and this implies that a screen diagram should set forth in a convenient and familiar form certain facts as to the character of the material screened regardless of the screen standards used, and it seems particularly desirable on account of the well-known differences in the size of openings of different laboratory screens having the same nominal mesh. In making screen-sizing tests it has been customary first to consider the largest size, going progressively to the smallest, and this seems to have led to the practice of placing the smallest size .at the right-hand side of the diagram and measuring toward the left. This is not altogether convenient and might be changed to advantage, but for illustration I have preserved that feature and present the method just as I have used it for over 2 years. Direct plotting in which the intervals on the diagram are proportional to the sizes of the openings, or to the arithmetical difference between them, seems at first sight more natural and is extremely useful for certain purposes, but it makes the diagram very crowded in the smaller screen sizes while the larger ones occupy unnecessary space, making it less convenient for most purposes, and for that reason the method here discussed is the well-known one based on the ratio between openings, and is plotted in logarithms instead of the direct values of the screen opening. Metric coordinate paper is convenient, although not necessary; it is recommended, as the use of the metric scale gives a diagram of convenient size, but any scale of equal parts may be used. In order to make any screen diagram translatable in terms of any standard screen size, it is necessary to have noted on the size scale of the diagram all points corresponding to the openings of the various screens in question, instead of a single series of points as with a single screen. In drawing the diagram assume 0.001 in. (corresponding approximately to 0.025 mm.) to be the smallest size to be considered and fix this as the zero point at the lower right-hand corner of the diagram. This value is selected because the values are to be plotted in logarithms, and the logarithm of 1 is zero. Then lay off to the left for the position of each screen

Jan 1, 1918

THERE are, as I have heard, varying opinions among men experienced in minerals as to whether silver has its own mineral [i.e., occurs native] or not. Mineralogical reasons and the authority of the majority persuade me that it has, not only because I have seen the natural material separate but also because I know that in mines of gold, copper, lead, and other metals pieces of pure metal are found without admixture, and I have heard that pieces of silver, gold, and copper have been found that had been reduced to their ultimate purity by natural causes. This is also confirmed by a German, Georgius Agricola, who says* that in a mine in Saxony a piece of metallic silver was found so large that the Duke who was prince and patron of the place had a whole dining table of square German style made from it without its being enlarged or worked on by any human artifice except for the tripod legs, and he often boasted that in this he surpassed the greatness of the Emperor. In truth I have never seen any metal except copper that was brought out from the mine pure and without any mineral, but I think that such a thing is indeed possible, since I believe in the greatness and power of Nature, who strives toward no other goal than perfection and purity. Indeed most of the minerals that I have seen have not been without admixture, not only of their earth but also of other metals, and this is more true of that which I have heard called silver than of any of the others. I except the silver that is mined in Schio in the region of Vicenza. These doubts, therefore, are not born without some shadow of apparent reason. As I told you above I believe that silver may have and does have its own mineral, for every substance that is converted into metal can exist pure by itself in its own species, as it also exists separately even though it be mixed with others, since it is seen that in each ore its metal is generated in a single body. Therefore it happens many times that whoever speaks of the ore of silver in one breath, without distinction, speaks of that of all the other metals, because there are few ores that are not mixed. But because the most noble things always have the prerogative of including in their name that of the others, where there is gold or silver the ores are not called

Jan 1, 1942

By E. D. Gardner

When the National Forests were created, all lands embraced in their boundaries were exempted from all forms of entry, except mineral claims. Later, by Act of June 11, 1906, and as amended by Act of Aug. 10, 1912, provision was made allowing homesteads on areas chiefly valuable for agriculture and not necessary for the public use. Patents to mining claims in the Forests are granted the same as on land not in the Forests, irrespective of timber or other values. It is the policy to encourage the highest use of the Forests. As a business proposition, it is a good policy to have mines developed in the Forests. Their development in remote or inaccessible regions causes the country to be opened up and, in addition to the local market which the mines create, means of transportation are afforded to outside markets. No examination of mining claims is made until patent has been applied for, unless they are actively interfering with the administration of the Forest. In this case, an examination is made, and if there is evidence that the claims are being held in good faith they are in no way interfered with. Timber is never sold from a mining claim except with the consent of the claimant, or unless it is clearly shown, after an examination, that the claim is abandoned. In the case of fire-killed timber, which rapidly deteriorates by standing, a contract bond arrangement can be made for the sale of the timber which protects the interests of both the mining claimant and the government. The promiscuous locating of mining claims has in the past caused considerable trouble. It has been, and still is, the custom in some parts of the West to locate a mining claim when the surface rights of any particular area are desired, irrespective of the mineral character of the ground. This has been done to hold power sites, town sites, summer residences, springs, etc. When the ground is desired for any of these purposes, what is known as a Special Use Permit will be issued at a nominal sum, to legalize the occupancy. In most instances, it is far cheaper to take out one of these permits than to do the annual assessment work on a mining claim, but, of course, patent to the ground cannot be obtained in this manner. If mineral were discovered on the land covered by a Special Use Permit, it would ordinarily be the policy to cancel the permit if it were clearly

Jan 1, 1915

Dr. Robert Bell died on June 18, 1917, at Rathwell, Manitoba, in the seventy-seventh year of his age. He was born in Toronto on June 3, 1841, and was a son of the Reverend Andrew Bell of the Free Church of Scotland. He was educated at the Grammar School of the County of Prescott, Ontario, and subsequently at McGill University and the University of Edinburgh. While still a boy of 15 years of age, he joined the Geological Survey of Canada, under Sir William Logan, in the capacity of Junior Assistant, and was rapidly promoted in the service, where lie remained-with but one short interval-for over fifty years, retiring as Chief Geologist and Acting Director in the year 1908. He married Agnes, daughter of the late Alexander Smith, of Westbourne, Glasgow, and Auchentroig, Stirlingshire, and is survived by one son and three daughters. Practically nothing was known of the geology of Canada, and very little with reference to its geography, when Mr. William E. (afterward Sir William) Logan was called upon to undertake the organization of the Geological Survey of Canada, and as its first Director to carry out the mapping of this vast area and the examination of its mineral resources. Dr. Bell's work as a member of Sir William Logan's staff in these early years consisted, therefore, exclusively of geological reconnaisance and geographical exploration. Even in later years, and until his administrative work confined him to his office, Dr. Bell's work remained essentially of this character. The exploratory traverses and track surveys which lie carried out were, chiefly within the area of the great Laurentian protaxis or Canadian Shield, which forms such a striking feature and which has played and will continue to play so important a role in shaping Canadian history and in influencing the character of the Canadian people. Dr. Bell's lines of exploration crossed and re-crossed this area from the Atlantic Coast to the Great Lakes on its western border, and from Lake Huron and Lake Superior on the south to the Arctic Sea, following the water ways of this great land. He also worked along the coast line when acting as geologist and naturalist to the "Neptune" Expedition in 1884, and to the "Alert" Expedition in 1885, both of which carried out explorations in Hudson's Bay and Hudson's Straits; also on the "Diana" Expedition in 1897, when he surveyed the coast of Baffin Land, and was one of the first white men who penetrated to the great 'lakes in the interior of that immense

Jan 11, 1917

By C. D. Tedmon, D. P. Ferriss

THE yield stress, o of low-carbon steel has been shown to vary with the average grain diameter, d, according to the relation1-3 where o is taken to be the lower yield-point stress Of is the friction stress on an unlocked dislocation, and ky is a constant. The interpretation2,4 of ky in terms of dislocation theory relates this constant to the stress to unlock a source across a grain boundary. cottrel14 predicted that ky would increase with decreasing temperature. This was observed to be the case by Adams and coworkers5 in their investigation of niobium (columbium). However, petch6 and Backofen: both working with low-carbon steel, found ky insensitive to temperature. In his work with high-purity niobium, Johnson' found ky equal to zero. Evansg showed that k, was essentially zero for niobium containing nitrogen in an appreciable concentration range. The present experiments were designed to check this apparent anomaly in the value of ky in another Group V metal. Yield points were determined as a function of grain size at several temperatures for tantalum and a tantalum-tungsten alloy. The material used was double are-melted tantalum and a double are-melted alloy of 90 pct Ta and 10 pct tungsten (by weight), both obtained as unannealed, swaged rod. The impurity content of the materials is given in Table I. The tantalum was annealed at 1325"C. in a vacuum resistance furnace using a tantalum boat. The alloy was similarly annealed at 1660°C. Annealing times varied from 15 min to 2 hr, depending on the desired grain size. Nominal pressure in the furnace was 3 X 10~4 mm of Kg. Metallographic examination showed that the annealing treatment produced grain sizes ranging frorn 0.021 to 0.200 mm in the tantalum, and 0.060 to 0.160 mm in the alloy. Tensile bars were made by centerless grinding the annealed specimen;, and then electropolishing to remove all grinding marks. The specimens were than pulled :it 2 1/2 pct per rnin in an Instron testing machine. The tantalum specimens were tested at 77", 195", and 300°K. The alloy was tested at 300°K only. All specimens exhibited a yield-point phenomenon at all temperatures. Typical load-elongation curves at the three test temperatures are shown in Fig. 1. The lower yield stress is plotted as a function of (grain size) in Figs. 2 and 3 for tantalum and the 90 pct Ta-10 pct W alloy, respectfully. The position and slope of the curves was determined by least-

Jan 1, 1962

By John Randall

IT is a fair assumption that the main purpose of any diagram is to present facts to the eye in more convenient form than they could be tabulated in figures, and this implies that a screen diagram should set forth in a convenient and familiar form certain facts as to the character of the material screened regardless. of the screen standards used, and it seems particularly desirable on account of the well-known differences in the size of openings of different laboratory screens having the same nominal mesh. In making screen-sizing tests it has been customary to first consider the largest size, going progressively to the smallest, and this seems to have led to the practice of placing the smallest size at the right-hand side of the diagram and .measuring toward the left. This is not altogether convenient and might he changed to advantage, but for illustration I have preserved that feature and present the method just as I have used it for over 2 years. Direct plotting in which the intervals on the diagram are proportional to the sizes of the openings, or to the arithmetical difference between them, seems at first sight more natural and is extremely useful for certain purposes, but it makes the diagram very crowded in the smaller screen sizes while the larger ones occupy unnecessary space, snaking it less convenient for most purposes, and for that reason the method here discussed is the well-known one based oil the ratio between openings, and is plotted in logarithms instead of the direct values of the screen opening. Metric coordinate paper is convenient, although .not necessary; it is recommended, as the use of the metric scale gives a diagram of convenient size, but any scale of equal. parts may be used. In order to make any screen diagram translatable in terms of any standard screen size, it is necessary to have rioted on the size scale of the diagram all points corresponding to the openings of the various screens in question, instead of a single series 'of points as with a single screen. In drawing the diagram assume 0.001 in. (corresponding approximately to 0.025 mm.) to be the smallest size to be considered and fix this as the zero point at the lower right-hand corner of the diagram. This value is selected because the values are to be plotted in logarithms, and the logarithm of 1 is zero. Then lay off to the left for the position of each screen

Jan 9, 1917

Further discussion of the paper of JAMES JOHNSTON, presented at the New York meeting, February,. 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133. See also Bulletin No. 91, July, 1914, pp. 1473 to 1496. THOMAS CROWE,* Victor, Colo.-The interest manifested of late in the treatment of low-grade ores, together with Mr. Clevenger's discussion of the Mill and Metallurgical Practice of the Nipissing Mining Co., prompts me to acid a few remarks relative to concentration in connection with cyanide treatment of low-grade ores. Mr. Clevenger in this discussion does not condemn concentration in this connection, but, nevertheless, the tone of his remarks would lead one to believe that his conclusions are like those of many others: that concentration is often turned to as a last resort in an attempt to improve or obtain an extraction upon an ore by the recovery and sale of the refractory portion of the ore. This, I will attempt to point out, is not always the case. Concentration in connection with cyanidation often performs an entirely different function, i.e., one of saving fine grinding. Economy being the keynote of successful treatment of low-grade ores, the problem often becomes more commercial than metallurgical, and, as there is generally a definite ratio existing between cost of operation, degree of comminution, and percentage of extraction, the grade of ore under treatment usually imposes a limit upon these factors. With many ores grinding is the most expensive single item in their treatment; therefore, the degree of comminution is very apt to be governed by the allowable cost of operation. With most ores the degree of comminution controls to a great extent the percentage of extraction. So in the treatment of low-grade ore it often becomes necessary to sacrifice extraction, through coarse grinding for the benefit of cost, in order that the greatest ultimate profit may be obtained, and it is under these conditions that it is, possible for concentration to play an important part in overcoming to some extent the effect of mesh. The precious metals occurring in an ore are usually closely associated with the metallic portion of the ore, and as this metallic portion is generally fairly well liberated from the gangue at comparatively coarse meshes, further grinding of the ore is necessary only in order that the metallic portion may be reduced sufficiently fine that the precious metal part of it may be dissolved by cyanide solutions in a reasonable length of time.

Jan 11, 1914

By L. G. Truby

DISCUSSION By Rhrt G. Nisle, Phillips Petroleum Co., Barthesville, Okla. The subject paper presents the results of a reservoir behavior analyzer study of the pressure-production performance of five Ellenburger pools in West Texas. These five pools are Wheeler, TXL, Andector, Embar, and Martin. This laboratory has also made reservoir behavior analyzer studies in this area and arrived at substantially the same conclusions. Although the principal results of the studies made in this laboratory are confirmed by the results in the subject paper, there are certain points of difference. The points of difference are (1) the subject paper includes the Martin pool in the common aquifer, whereas our studies indicate that it is not, and (2) the subject paper concludes that the effective aquifer is considerably smaller than that derived from studies made in this laboratory. In terms of reservoir analyzer data, our rejection of Martin is based on the inability to obtain a satisfactory match of the pressure curve when Martin is considered as lying within the common aquifer. A satisfactory match was possible, however, when Martin was run as an isolated pool. This indicates that the pressure disturbance resulting from production at Martin had not reached Embar, Andector, TXL, or Wheeler at the time of our study. A similar situation exists relative to Dollarhide. In tern of geological data, our rejection of Martin is based on the presence of a faulted zone between Martin and Embar. This condition is indicated in Fig. 4 and again in Fig. 10 of the subject report. If a permeable connection between Martin and the other fields does exist, it is probably by way of a detour around this fault. The second point of difference between the two studies is illustrated by a comparison of Fig. 4 of the subject paper with Eg. A. Fig. A is obtained from an internal report on one of the studies made by this laboratory. It will be noted that the area indicated in Fig. 4 is roughly that marked "Pool Unit" in Fig. A. The additional portion of the aquifer shown in Fig. A was simulated on the reservoir analyzer by means of the water drive network. A satisfactory pressure match could not be obtained without this additional network. The differences involved here stem from a more fundamental consideration concerning reservoir analyzer operating techniques. The true source of these differences in reported results cannot at this time be determined because of the incompleteness of the subject paper. It is not stated, for instance, whether the pressure match was induced by altering the field resistance or the field capacitance, or both. Changing analyzer

Jan 1, 1953

By R. Bakish, W. D. Robertson

IN the course of a study of stress corrosion cracking of AuCu,, it was necessary to develop new electropolishing and metallographic etching methods. The techniques are generally useful for Cu-Au alloys, including the AuCu composition in which transformation markings are well delineated. For electropolishing, the only satisfactory electrolyte and procedure that has been found1 has the composition given in Table I. The solution must be vigorously stirred while polishing and the temperature maintained in the range of 55" to 62°C. The electrolyte is very unstable and can be used only for 10 to 15 min after which its color changes and a dark-brown precipitate forms. The polishing time is between 1 and 4 min depending on the initial surface preparation. The use of a hood is recommended to avoid the danger of cyanide gas which may form at one of the electrodes even though the solution is alkaline. The optimum current and voltage conditions for vertical anode and platinum cathode are on the plateau shown in Fig. 1, in which voltage is measured across the cell terminals. At voltages below the plateau, etching of grain boundaries occurs and under some conditions, which have not been clearly defined, octahedral etch figures are observed. For general purpose grain-size determination in polycrystalline alloys, a 3 pct solution of iodine in methyl alcohol is used with excellent results. However, when it is necessary to reveal small orientation differences or concentration gradients in an alloy, the iodine etch is not satisfactory. For this purpose, a highly satisfactory etching procedure was developed during this investigation. It involves the use of the vapor given off by freshly prepared aqua regia. The solution employed is 3HC1 to lHNO, which decomposes in accordance with the reaction HNO, + 3HC1 = NOCl + 2H,O + Cl,. The polished specimen surface is held about 1 to 2 cm above an aqua regia solution for 2 to 10 sec depending on the intensity of the contrast required and the surface is not subsequently washed. The results obtained with a coarse grained cast structure are shown in Fig. 2. Subgrain boundaries in a single crystal and concentration gradients within the boundaries are developed by the same treatment with the results shown in Fig. 3. Obviously, any conclusions regarding structure-dependent properties will be modified by the pronounced heterogeneity, which is not clearly evident when more conventional methods are used. Interesting structural details are also revealed by treatment for 4 hr at 850°C in unpurified tank argon. Fig. 4 shows a pattern characteristic of orientation-dependent oxidation.

Jan 1, 1956

By John Blandy

EVERY new mining district has had its own peculiar experiences in inventing and experimenting upon new methods for the various operations of mining, and more particularly in the processes of crushing and dressing ores. As a matter of course, during this period many old things have been reinvented, patented, and cast aside, there to remain until at a future day other geniuses shall bring them forth again as new. In this respect the Copper Region of Michigan has not been behind other mining centres, and probably in no other part of the country has more money been expended in devising new machines and improvements upon old ones for the crushing of the rock. The appliances for washing the sand have not been so varied, simply for the reason that, having but one mineral, or rather metal, of high specific gravity to separate from rock material which varies but little in its character in any one mine, it requires much less care than is necessary in most mining centres of the world. At the beginning of operations in that district most of the work was in the control of Cornish miners, who introduced the simplest of Cornish mills, namely, wooden stem pestles, with wooden shafts and cams. These were well suited to the small mines, and particularly to the limited means of transporting more expensive machinery. As these facilities improved, they were enabled to change to iron, and to vary their patterns of rods, shafts, cams, and mortars. The most approved pattern, finally obtained, is the square or round stem, with collar adjustable by means of keys. In its present form it is a bar of cold rolled shafting, an eye in the top, an adjustable collar with key-plate and keys, the head and a shoe of chilled iron. The stem is fitted into the head by a slight taper. The battery has heretofore been of wood, lined with chilled cast plates, and bed-plate of the same, but within the past year the California pattern has been introduced. The screens are of sheet-steel, drilled with 16 holes to the inch. During this period of trial and gradual improvement in the pestle stamps, in the years 1855-6, the Ball steam-stamps were intro¬duced, and after years of labor and expense, have been made the most efficient and powerful machines ever yet used for the purpose. It is ostensibly the Nasmyth steam-hammer, and yet the

Jan 1, 1874

By David V. Ragone, Richard E. Balzhiser

The liquidus uranium concentration in the U-Bi system is given by the following expression for the temperature range 400° to 800°C: No break was observed in the curve over this temperature range. The partial molar enthalpy change for uranium in the liquidus reaction, UBi2— U + 2Bi, was found to equal 12,300 cal per g mole. Copper produced a continuous decrease in the liguihs uranium concentration at 600°C. The presence of copper in the solvent was observed to affect the uranium activity coefficient according to the following expression: duced no change in the liquidus combosition below 0.6 at. pct Pd. Higher palladium concentrations sharply depressed the uranium concentration. SOLUTE behavior in molten alloys has been shown to be strongly influenced by the presence of additional species. Much attention has been given to such phenomena in iron-base systems where a number of alloying elements and/or impurities are likely to be present in small but significant quantities. Frequently, the interaction of these solutes has altered their thermodynamic behavior to the extent that reaction equilibra are appreciably influenced. Consequently, much of the information available for binary behavior must be reevaluated when additional components are likely to be present. Similar interactions can be expected to occur in bismuth-base solvents. Interest in the use of bismuth solutions of uranium as reactor fuels has stimulated investigators to explore the effect of various elements on the liquidus uranium concentration. Criticality requirements necessitate close control of the uranium concentration which, at the anticipated operating temperature of 500°C, approaches saturation. Consequently, elements which suppress the liquidus concentration could produce serious reactivity problems. Since the fuel solution is cer- tain to contain additives, such as magnesium and zirconium, for corrosion inhibition as well as small concentrations of fission products and corrosion products, a better understanding of the possible interaction phenomena is mandatory. This need stimulated experimental programs at the Brookhaven National Laboratory and elsewhere to determine precisely the liquidus uranium concentration in the bismuth-rich portion of several ternary systems. Early experimental efforts were directed toward an accurate dcmtermination of the U-Bi liquidus over the temperature range from 300' to 800°c. As shown in Fig. 1, the results to date exhibit considerable scatter. The investigations of Bareis,' Teitel,2 Greenwood,3 and Cotterill and hon4 agreed well below 700°c. Greenwood and Teitel extended their studies to higher temperatures but failed to concur in their results. A more recent study by Schweitzer and weekss at Brookhaven National Laboratory between 300' and 725°c, produced values 15 pct lower

Jan 1, 1962

By A. E. Back, K. E. Tame, W. F. Wyman, S. F. Ravitz

IN 1940, when it appeared that the United States soon might be cut off from foreign sources of high-grade manganese ore, the Bureau of Mines began an extensive series of investigations on the production of ferrgrade products from low-grade domestic ores by ore-dressing, pyrometallurgical, and hydrometallurgical methods. Among the hydrometallurgical processes for oxide ores investigated was a sulphur dioxide process in which the manganese was recovered from solution by precipitation with lime;1 this process is essentially as follows: The ground ore is suspended in water and leached with SO2 gas to extract the manganese as manganese sulphate. Calcium chloride is then added to the slurry to precipitate calcium sulphate and form manganous chloride solution, and the resultant slurry is filtered to remove the calcium sulphate together with the in- soluble portion of the ore. Calcium hydroxide is added to the filtrate and the mixture is agitated with air to precipitate hydrated oxides of manganese and regenerate calcium chloride. The precipitate is calcined, and the calcium chloride is recycled. To determine manganese extraction, reagent consumption, grade of product, and similar data for this process, a laboratory investigation was started. Two minor modifications in the process were soon made: (I) the ore was suspended in calcium chloride solution instead of in water in order to extract the manganese and precipitate the calcium sulphate in one step, and (2) the agitation with air after the addition of slaked lime to the filtrate was omitted because manganese hydroxide is readily precipitated without air agitation and can be nodulized or sintered to a satisfactory product. When the process was carried through a series of cyclic tests, it was noted that the concentration of dithionate ion (which is one of the products of oxidation of SO2 by MnOz) in the cycled solution gradually increased; at the same time the chloride content of the solution gradually decreased, owing to soluble losses in the leach residue and in the precipitate. After a number of cycles, the calcium chloride became virtually completely replaced by calcium dithionate, the quantity of dithionate ion formed during the leach being more than enough to make up for the losses of dithionate in filtering. The calcium chloride process thus developed into a calcium dithionate process. Since the latter eliminated the need for make-up calcium chloride, and the dithionate solutions appeared much less corrosive than the chloride solutions, work on the calcium chloride process was dropped in favor of the calcium dithionate process. ACKNOWLEDGMENTS The dithionate process was developed by the Bureau of Mines as part of a

Jan 1, 1946

By Harold M. Feder, Irving Johnson

Tkermodynamic functions for dilute solutions of uranium in liquid cadmium were obtained from galvanic cell measurements. Deviations from Henvy's law were observed at concentvations down to 2 x 10-3 atom fraction. Unusually large negative values of the pavtial molal relative enthalpy and excess entvopy of uranium, suggestive of the occu,vvenctwe of partial ovdering of cadmium around uranium in these solutions, were found. The negative relative partial molal enthalpy of uranium at the liquidus accounts for the observed retrogvade solubility of metallic uranium between 473" and about 630°C. The standard free enevgy of formation of UCd,, from a-uranium and liquid cadmium is given by F,° THE constitutional diagram of the U-Cd system,' Fig. 1, is unusual in several respects. The near equality of the Goldschmidt atomic radii2 (Cd, 1.52A U, 1.56A) might be expected to give rise to extensive mutual solubility of the elements except for the restrictions imposed by differences in valence and electronegativity.3 The latter factors must be strongly influential because mutual solubilities in the terminal solid phases are probably negligible, and the solubility of uranium in liquid cadmium in the readily accessible range is only about 1 at. pct. Interestingly, the solubility of uranium in liquid cadmium actually decveases slightly with increasing temperature from 473" to about 630°C. Such a retrograde solubility in a liquid phase is a rare phenomenon in metallic systems; no other authenticated examples were found among the nearly 700 binary phase diagrams compiled by Hansen and Anderko.2 These observations suggested the existence of some unusual interaction between uranium and cadmium. Greater insight into the nature of this interaction was sought by measurement of the thermodynamic properties of the system. EXPERIMENTAL PROCEDURE The emf of cells denoted by the scheme was measured. Each cell consisted of two uranium and two alloy electrodes immersed in a molten lithium chloride-potassium chloride eutectic mixture containing uranium trichloride. The physical arrangement is shown in Fig. 2. The potential between any pair of electrodes could be measured with a Leeds and Northrup Type K-3 potentiometer. The measurements were made at points marked in Fig. 1. It should be noted that points on the phase boundaries represent the concentrations of uranium in the saturated liquid phases of heterogeneous alloys. Uranium Electrodes. Uranium, which is not a particularly soft metal, is capable of retaining residual stresses, and its potential may depend upon its physical condition. Electrodes were prepared from 3-mm diam rods of hot-rolled high-purity4

Jan 1, 1962

By T. Sterry Hunt

BUT little was known of the coals of Southeastern Ohio until the present survey of the State under Dr. Newberry began its work. The results of the geological investigations of Prof. E. B. Andrews in this region, and of the chemical investigations of Prof. T. G. Wormley, both of which appear in the reports of the survey for 1869 and 1874, and more recent special reports by the former, together with some data for which I am indebted to the kindness of Dr. Newberry, and my own limited observations, have served me for the preparation of the following notice of the coals lying on the western border of the great Appalachian coal-basin in the region drained by the Hocking River and its tributaries, and belonging to the Lower Coal-Measures. Some uncertainty exists as to the place in the succession of the lower coals to be assigned to the seams known and mined in the Hocking Valley. It is the opinion of Prof. Andrews that the inequalities of the original surface were such that we cannot identify in that region the lowest coals known in Northwestern Pennsylvania and the contiguous parts of Ohio, but that we must rather count from above downwards. These conclusions Dr. Newberry is not prepared to accept, and further researches will be necessary before certainty can be attained in this matter. Meanwhile it seems, from a study of its relations to the Pomeroy or Pittsburgh seam, that what is known as the great vein of the Hocking Valley, occupies the horizon of the Upper Freeport coal, E of the Pennsylvania survey, or No. 6 in Dr. Newberry's enumeration, counting from the base. This seam, in the region in question. assumes certain characteristics which, taken in connection with its geographical position, give it a great importance among the coals of the State. The area to be noticed includes the whole or parts of several townships in Perry, Hocking, Vinton, and Athens Counties, lying near the margin of the basin over which the vein in question assumes the character of a dry-burning or splint coal, and has a thickness varying from six to ten and even twelve feet. Its precise limit southward cannot at present be clearly defined, but it has been found as far south as the line of the Marietta and Cincinnati Railroad, with a thickness of six feet, and is mined at various points along the valley of the Hocking River, near Nelsonville, where it attains six or seven feet. To the northward, along the tributaries of this river, Sunday and Monday

Jan 1, 1874

By T. Sterry Hunt

But little was known of the coals of Southeastern Ohio until the present survey of the State under Dr. Newberry began its work. The results of the geological investigations of Prof. E. B. Andrews in this region, and of the chemical investigations of Prof. T. G. Wormley, both of which appear in the reports of the survey for 1869 and 1874, and more recent special reports by the former, together with some data for which I am indebted to the kindness of Dr. Newberry, and my own limited observations, have served me for the preparation of the following notice of the coals lying on the western border of the great Appalachian coal-basin in the region drained by the Hocking River and its tributaries, and belonging to the Lower Coal-Measures. Some uncertainty exists as to the place in the suc- ' cession of the lower coals to be assigned to the seams known and mined in the Hocking Valley. It is the opinion of Prof. Andrews that the inequalities of the original surface were such that we cannot identify in that region the lowest coals known in Northwestern Pennsylvania and the contiguous parts of Ohio, but that we must rather count from above downwards. These conclusions Dr. Newberry is not prepared to accept, and further researches will be necessary before certainty can be attained in this matter. Meanwhile it seems, from a study of its relations to the Pomeroy or Pittsburgh seam, that what is known as the great vein of the Hocking Valley, occupies the horizon of the Upper Freeport coal, E of the Pennsylvania survey, or No. 6 in Dr. Newberry's enumeration, counting from the base. This seam, in the region in question. assumes certain characteristics which, taken in connection with its geographical position, give it a great importance among the coals of the State. The area to be noticed includes the whole or parts of several townships in Perry, Hocking, Vinton, and Athens Counties, lying near the margin of the basin over which the vein in question assumes the character of a dry-burning or splint coal, and has a thickness varying from six to ten and even twelve feet. Its precise limit southward cannot at present be clearly defined, but it has been found as far south as the line of the Marietta and Cincinnati Railroad, with a thickness of six feet, and is mined at various points along the valley of the Hocking River, near Nelsonville, where it attains six or seven feet. To the northward, along the tributaries of this river, Sunday and Monday