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By E. S. Machlin, A. A. Hendrickson

Use was made of a recently developed surface-accumulation diffusion technique to measure the self-diffusivity of edge-type dislocation singular lines (Burgers vector along <110>) in a bent and polygonized single crystal of silver. Two factors are involved in obtaining a number for the diffusivity. One factor, the dislocation-line density, was measured by a microscopic technique recently developed, and the value of the other parameter, the effective "diameter" of a dislocation pipe, was estimated. With these parameters equal to 7.3 X 106 dislocations per sq cm and 10-7 cm, respectively, it was found that the self-diffusivity along edge-type dislocation lines was a factor of about two times the average grain-boundary self-diffusivity. The dislocation-pipe diffusivity is about 7x10-7 sq cm per sec at 450°C. THE possibility of short-circuit diffusion through imperfections in crystals has been recognized for some time. It was only recently, however, that concerted effort has been expended to obtain values of diffusivity for grain-boundary short circuits. The work, for example, of Hoffman and Turnbull1 on silver, Fisher&apos;s&apos; analysis of the grain-boundary dif-

Jan 1, 1955

By Glenn Allen

SAN FRANCISCO Mines of Mexico, Ltd. owns and operates an extensive group of claims in the San Francisco del Oro-Santa Barbara district, about 15 miles southwest of Parral, Chihuahua. The property comprises the mines, aerial tramways, flotation mill, power plant, shops, offices, assay and testing laboratories, modern hospital, water and sanitary system, quarters for miners, mechanics and operators, a well housed colony for Mexican staff employees and residences for foreigners. Each colony has a club house and mess and tennis courts. The employees have constructed a nine-hole golf course. In other words, the property is self-contained and completely integrated for production of lead and zinc concentrates from complex sulfide ores.

Jan 1, 1930

By A. M. Gaudin, D. W. Fuerstenau, M. M. Turkanis

SOLUBLE silver salts are effective activators for flotation of sphalerite with potassium ethyl xanthate as collector.&apos; Since sphalerite takes up large quantities of silver ions rapidly," investigation of this system appeared fruitful for studying the mechanism of sphalerite activation and deactivation. Experimental data presented here comprise studies of the mechanism and rates of activation and deactivation of sphalerite with silver and cyanide ions. A 20-lb sample of sphalerite from Ottawa County, Oklahoma, was handpicked, crushed, screened, hydrosized to produce a 65/100-mesh fraction, and purified by electrostatic separation. The sphalerite was then leached with benzene and absolute ethyl alcohol to remove possible organic contaminants and with 0.1 M NaCN to remove any copper that might have been picked up during screening. The benzene had been specially purified by grinding with fine sphalerite for 12 hr to remove trace impurities that might have had a specific affinity for sphalerite. Finally, the mineral was washed, dried in flowing nitrogen, and stored in large ground-glass stoppered weighing bottles under a small nitrogen pressure.

Jan 1, 1957

By J. E. Russell, Y. J. Wang

In this paper, we report the results of a study of the characteristics of Texas lignite based on a proximate analysis data base previously published by the Bureau of Economic Geology, University of Texas at Austin and the U.S. Bureau of Mines. The original impetus for this study was the desire to perform a parameter study in connection with the siting of potential underground gasification tests in Texas. A numerical model of the gasification process was available and required proximate analysis data, among other parameters, as input. If proximate data were available for a particular site, a prediction of the product gas quality could be made. However, in preliminary siting studies, it would be advantageous to know what the desirable characteristics of the lignite are, in order to target general areas for drilling. Consequently, a parameter study was in order. This paper presents the methodology required to systematically vary proximate analysis parameters and estimate the corresponding energy content for various group(or formation)-facies classifications of Texas lignite.

Jan 1, 1983

By William McCullouch

The method of determining moisture percentages in coal has been defined as purely empirical. The procedure, as defined, has been published in the U.S. Bureau of Lanes technical papers and approved by the American Society of Testing Materials but deviations from this established procedure are common in most commercial and private laboratories. It is not within the scope of this paper to discuss the deviations in common practice but rather to give a detailed account of the method in use in the laboratories of the United Electric Coal Companies. In general, moisture values are presented as surface moisture and, for lack of a better term, inherent moisture. The formula for adding them together to give total moisture is common knowledge. In practice, on high-moisture bituminous coal, it has been found that the line of demarcation between surface and inherent moisture is very indefinite, the inherent moisture being so loosely held that it is released far beyond its natural limits when the prescribed method of the A.S.T.M. for determination of surface moisture is followed. This is shown in Table 1 for two typical washed coals from Illinois.

Jan 1, 1938

By Auguste J. Rossi

As is well known, practically all the phosphorus of the ironores smelted in the blast-furnace passes into the pig-metal, increasing its fluidity, but diminishing its strength to such an extent that, if phosphorus exceeds a certain amount, the metal is only fit for fine castings, not required to resist strains, and it cannot be used for the ordinary purposes of good foundry-iron. No phosphorus being eliminated in the acid Bessemer process, the quantity admissible in pig-metal destined for that process must be very small, and hence the ores smelted must be strictly Bessemer ores, of which, in many districts, the supply is taxed to the utmost. On the other hand, very highly phosphoric pig, a metal of little or no value by itself, when refined by the Thomas-Gilchrist process in the basic converter, furnishes an excellent steel; but such pig-iron must be made from ores particularly high in phosphorus; and these ores are not everywhere abundant, and are much sought after for this special purpose. But there are many iron-ores containing a moderate, though still important, amount of phosphorus, which yield a pig-metal

Jan 1, 1897

By Philip L. Collyer

A technique for evaluating the similarity of ore deposits is presented. A Q-mode cluster analysis is performed using information on tungsten mines in North America. This is a method of grouping several samples according to their similarity based on a simple matching coefficient. Tungsten mines are grouped or clustered on the basis of geologic variables. It is possible to interpret and evaluate different ore environments according to age, mineralogy, and other variables. It is well known that variable geologic conditions influence the occurrence of certain types of minerals. If one variable is responsible and identified, that variable can be searched for in exploration. If several interrelated variables are responsible for forming a favorable environment, then recognition and identification may be more difficult or completely masked. Therefore it is helpful in exporation to isolate and identify multiple interrelated variables which control the localization of mineral deposits. Cluster analysis is useful in mineral exploration where considerable amounts of data are available for analysis. Subtle relationships that might be overlooked because the data are voluminous can be isolated using this technique. Cluster analysis can be used to establish exploration prioriy in unknown areas on the basis of similarities to known metallogenetic provinces.

Jan 1, 1976

By P. K. Guerrero, Nathaniel Arbiter

The correlation of power consumed by a tumbling mill with the dimensions, speed, and load has been attempted by three principal methods. One of these, the torque formula, has been reviewed critically elsewhere. This approach, while analytical, disregards the individual motion and speed of the tumbling bodies and assumes that the gross geometry of the entire load is sufficient to establish the power requirement. A more general approach, using dimensional analysis, has been applied in this laboratory by the present authors, and more recently by Rose. This disregards the internal conditions within the mill entirely and in effect is an empirical procedure for correlating data. Finally, the complete analysis of tumbling mill dynamics as first made by Davis attempts to develop the power requirement from individual ball and rod paths and velocities. Although Davis&apos; result is applicable only at a single speed for a given size and load it could be useful, since his optimum speed is at the upper limits of conventional tumbling mill practice. Where power values predicted by the Davis equation were compared with actual mill requirements, they were found too low for small mills and much too high for the largest mills. This suggested that the agreement with actual intermediate range requirements might be fortuitous, and the development of the equation was examined critically.

Jan 5, 1960

JUST as I have told you that it is impossible to give an exact rule for the bell scale, so I say the same concerning the clappers. Yet, if one wishes the bell to sound well, it is necessary that it have a proportioned blow; for if it is struck with a clapper that is lighter than it should be, it will not give out all the sound that it contains, and if it is struck with a heavier one than it can support, it is forced and the sound is made crude and harsh, in addition to the danger of breaking the bell. Therefore-the clappers must be made so that they bear a certain proportion to the bell, and in order not to proceed by chance, I have diligently tried to find the method as well as possible. I have found that experienced masters [99] have given to bells weighing ten pounds a clapper of one and a half pounds [and, to larger ones, clappers as tabulated on the next page].* Larger numbers than these I have not found because, in truth, few of the extraordinarily large ones are made in our regions. In my opinion, the masters should not be limited to these rules for the differences in clappers but should proceed according to the kind of bell, using a certain discretion for it is not possible to give a definite rule.

Jan 1, 1942

By D. O. Ehrenburg

DURING the earlier period of electrical prospecting, the search for orebodies was by far the most important application of this method of geophysical prospecting. In the past few years, however, increasing attention has been paid to the possibilities of this method in the investigation of subsurface structures. Not only have fault zones been located, but attempts have been made to determine the depth to certain strata and thus contouring on some bed which proves to be a good "electrical marker." Many workers have published the results of field tests showing how their particular interpretations have agreed with the actual field conditions, but very few have stated their method of interpretation. Weaver, Hummel and Stefanesco and Schlumberger1 have given a more theoretical discussion of the resistivity methods. Hummel and Stefanesco and Schlumberger have published mathematical solutions for the flow of electricity in a medium involving four layers. In this paper the authors present a solution for the flow of electricity in a medium of any number of horizontal strata. By means of this solution, curves showing the relationship between the apparent resistivity and the electrode spacing can be computed for ideal cases.

Jan 1, 1931

By Fred P. Dewey

The iron ores of Canada have attracted more or less attention in this country for a number of years ; and having had an opportunity this past summer to examine some of them, especially the magnetic ores, I have thought it might be of sufficient interest to the members of the Institute to put on record some of my observations. The region examined contains, for the most part, only the rocks of the Laurentian system. Much of it was originally covered with a dense growth of pine, which interfered with successful prospecting for ores. However, after the best of the timber had been cut off, fire generally got into the bush and cleared it up pretty well. This, besides making travelling about easier, exposed large surfaces of rock, and rendered the work of the prospector far more liable to be rewarded with success, while removing many of its hardships. The general appearance and productiveness of the land have, however, been far from improved by this process. It would be difficult to find a more desolate-appearing country than some of these pine woods after fire has been through them. The country examined may be, for convenience, divided into two

Jan 1, 1884

By Thomas B. Dellinger

Since 1950, rotary-drilled, large-diameter holes, "big holes", with depths to over 300 ft and diameters of over 30 in., have become numerous and widespread. 50 such holes have been drilled for access shafts to LPG mined caverns. Over 70 holes have been drilled for various other commercial activities. Over 150 holes have been drilled by the AEC for atomic testing purposes. These holes have ranged up to 300-in. diam with 1600-ft depths, 120- in. diam with 570-ft depths, and 72-in. diam with 4800-ft depths. Equipment is now available to drill a wide range of big holes for varied requirements. At least a dozen drilling contractors are participating or have participated in the drilling of big holes. The accompanying tables show pertinent historical, technical and economic data on over 250 holes. The purpose of this paper is to present a review of the big hole drilling equipment available, a compilation of the available data on large-diameter holes, to show the experience obtained to date and to show that big hole drilling is feasible and available to the industry.

Jan 12, 1965

By Harry E. LeGrand

Most mine operations are hampered to varying degrees by excessive inflow of water into mines or scarcity of water for processing the materials. These internal problems are compounded in many cases by such external hydrological problems as lowering of ground-water levels in areas outside the mine properties, subsidence of ground surface, adverse geochemical changes, and pollution. The development of a mine below the water table disturbs the natural ground-water system, causing a convergence in the flow of water from a surrounding area. The mine becomes the apex of a depressed cone in the water table. The fact that mines are commonly located in complex and somewhat anomalous geologic environments prevents an idealized treatment of the mine as a well that would be similar to a water well in a homogeneous aquifer having isotropic conditions. Yet, adherence to some principles of ground-water behavior is helpful when combined with an understanding of the local geology. A program calling for an appraisal of all pertinent hydrological conditions prior to mining and during various stages of development should supply adequate information for mine officials to anticipate difficulties and to allow for corrective measures. Before and during mining operations there should be a mine hydrology framework and plan, in which there is continual upgrading of such considerations as anticipated actions, consequences of actions, remedial plans, and contingencies.

Jan 1, 1973

CHARLES F: WILLIS,* Bisbee, Ariz. (written discussion?).-An employment department operated only with the object of relieving the foremen from hiring and for the purpose of centralizing record keeping is not likely to be entirely successful, and is doing but a small part of the good that practice has shown is possible; although it was .probably a desire to save time and to conduct the business more conveniently that led many mining companies to centralize their employment department. The ultimate object, however, is the reduction of labor turnover, by obtaining men better qualified to fill the positions to which they are assigned, by following up their work and providing for transfer to other departments or for promotion, if advisable, by reducing the number of quits for inconsequential reasons, and by supervising such laying-off as is necessary in such a way that the permanent force is not upset. It provides a stability &apos;of employment, free from favoritism and paternalism, probably the best form of employment insurance that we can have. The value of the employment department is in direct proportion to the breadth of its supervisor, his ability to estimate and place men, his sympathy in dealing with their petty troubles, and his analysis of quits and the reasons therefor. There is probably no better index of the soundness of the industrial relationship between the employee and the employer than the reasons why men quit; an intelligent, unbiased analysis of these reasons tells where corrective measures are necessary. In nine cases out of ten the reasons are small grievances, easily corrected, and are things usually overlooked by mine officials.

Jan 6, 1919

By C. Y. Wen, H. O. Hofman

In casting a thermal balance of the heat generated and absorbed in a blast-furnace treating lead-, copper- and similar non-ferrous ores, assumptions have always to be made for the values of the heat of formation of slag. Considering that the larger part of the charge introduced into the furnace comes out in the form of slag, the significance becomes apparent of a lack of heat-values for the singulo-silicate, which is the type of slag commonly made. The aim of the present investigation is to supply these heat-values as far as possible with the apparatus and the time available. The heats of formation of the ferrous and manganous bi-silicates have been determined by Le Chatelier;1 those of some silicates other than iron and manganese by Tschernobaeff;&apos; finally Richards3 gives a figure for a copper blast-furnace slag of known composition. The existing data and those resulting from the present investigation are assembled in Table VI. 11. Materials Used. The materials used in the experiments mere silica, ferrous oxide, and calcium carbonate. Silica.—The silica sold in the market as chemically pure usually contains small amounts of magnesia, lime, and alumina, and is therefore not suited for the work. The pure material was obtained from clear quartz crystals from Arkansas, broken in a diamond mortar and ground in an agate mortar to pass

Jan 1, 1911

In his paper, Sastry proposes the use of flotation methods other than the "conventional flotation!&apos; process as possible economical methods of removing mineral fines, The practice of Liquid/Solid separation employing microbubbles to assist or induce the flotation of suspended solids is common to both municipal and industrial waste- water treatment; and is also used as a separation step in some processing industries. The pretreatment (if any) of the stream prior to flotation, the source of the microbubbles, and the design of the separation vessel depend on the application. For example: a metal finishing plant would use an elaborate chemical conditioning scheme to precipitate metal hydroxides for removal by a dissolved air flotation unit operating in the effluent recycle mode, while some oily waste can be separated using a dispersed air flotation cell with no chemical conditioning. At the present time, the "conventional flotation" process employed by the mineral processing industry makes use of mechanical agitation and aeration to generate certain sizes and quantities of bubbles and to mix these bubbles with the pulp. Specific types of chemical conditioning are used to obtain the desired results. For the separation of mineral fines, the type of chemical conditioning, bubble generation and separation device needed to obtain optimum results will have to be determined through research. The point to be made is that while the principles of flotation separation can be applied to a wide variety of applications, the specifics of the flotation process may vary with each application. Sastry&apos;s paper has dealt with the many areas of research required to fully understand and utilize the flotation process for the beneficiation of mineral fines.

Jan 1, 1979

By A. U. Seybolt, R. L. Fullman

THE Hume-Rothery rule relating the relative sizes of the solvent and solute atoms in a substitutional solid solution for moderate to extensive solubility is, of course, well known and much used in the design of alloys. No such rule has been obtained for interstitial solid solutions, although a qualitatively similar relationship would be expected. Among the most common interstitial elements, oxygen, carbon, and nitrogen which can dissolve in important amounts in the transition metals, only in the case of oxygen is there enough solubility data available for an examination of the possibilities of a simple relationship between the extent of solubility and the properties of the metal solvents. Three properties were examined: 1—size of the octahedral space V into which oxygen atoms fit, 2— the elastic modulus E, and 3—the free energy ?F of formation of a low oxide, such as is known to be, or would be expected to be, in equilibrium with the terminal solid solution. The size factor or octahedral volume is so closely associated with the well known Hume-Rothery con- cept of size factor that additional development of this subject is hardly necessary. The octahedral volume used was not corrected to an elevated temperature, as this correction would have made no significant difference. The second factor, Young&apos;s modulus E, must be considered, since it is a measure of the strain energy required to force neighboring atoms apart so that an oxygen atom may enter the octahedral volume. The temperature dependence of the elastic modulus of many metals has been reported by Köster,1 but for a rather limited temperature range. Since the

Jan 1, 1955

By Grover J. Holt

Open-pit mining on the iron range has been in a stage of transition for several years from the standpoint of mechanization. The most radical change in open-pit mining methods was started in open-pit haulage in 1937 with the departure from the then standard system of locomotive and car transportation and the advent of the heavy duty truck as a replacement. The initial use of trucks was followed shortly by the first installation of a conveyor belt for open-pit ore haulage. The growth of the combination of trucks for gathering units delivering to a conveyor system for transportation out of the pit, has been rapid and this transition appears to have reached a peak in 1949 with locomotives and cars now being used in only a few of the largest open pits. One point which must be considered, if we assume that the maximum equipment change- over point has been reached, is that the largest pits have probably passed their peak of production. Future ore replacement must come from smaller pits wherein the truck conveyor system has done an outstanding job.

Jan 1, 1950

By William G. Pariseau

A plasticity theory for anisotropic geologic media has been applied to the problem of quasi-static wedge penetration of rock under confining pressure. Numerical evaluation of the governing system of stress equations in the transversely isotropic and orthotropic cases using representative material properties shows that the consequences of initial anisotropy for the penetration process are by no means trivial. In the transversely isotropic case, a threefold increase in the vertical force required for penetration to a unit depth occurs as the inclination of the axes of anisotropy are rotated through 90° with respect to the penetration path. The horizontal force required varies from zero to a maximum at approximately 60° then back to zero as the axes of anisotropy are rotated. The maximum is of the order of magnitude of the force required in the isotropic case. Similar results are observed in the orthotropic case. Practical aspects of the post-elastic phenomena associated with anisotropic rock indentation within the context of drilling problems include: bit yaw, hole deviation and bending stresses in the drill rod, all of which vary with strata dip but which can be quantitatively evaluated given the bit geometry, interface friction and rock properties. In a broader context, the analysis reveals the necessity for well conceived experimental work and sound theoretical research concerning post-elastic behavior of geologic media as a function of confining pressure, the effects of induced anisotropy, and the variation of strength parameters with loading path changes in the post-elastic range.

Jan 1, 1971

By J. E. Flinn, E. R. Gilbert

Recently, Green reported some high-temperature, 0.60 to 0.89 T3, creep results on unalloyed tantalum. From his study he determined an activation energy of 114 kcal per mole for steady-state creep using the T, differential-temperature method25 for testing. He accounted for the difference between this value and 110 kcal per mole for self-diffusion by the temperature dependence of the elastic modulus, 4 kcal per mole. This reported activation energy is in apparent disagreement with that which can be determined from Green&apos;s isothermal data, which we have plotted as log creep rate vs 1/T in Fig. 15. From this figure, it appears that there are two activation energies of -185 kcal per mole at the higher temperatures and -75 kcal per mole at the lower temperatures. It is not obvious that the data can be fitted to a straight line corresponding to an activation energy of 114 kcal per mole. One is led to two possible conclusions regarding Green&apos;s study: there are two discrete processes controlling the creep rate from 0.60 to 0.89 Tm or the apparent activation energy is not discrete but continuously increases with increasing temperature. The former speculation would be in closer agreement with the high-temperature creep behavior of tungsten.28 The apparent disagreement between the activation energies determined by the AT and isothermal methods certainly suggests that further study on the high-temperature creep of tantalum is needed.

Jan 1, 1967