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By Alwyn Birchmore Cox, Ian William Wark

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939

By Ian William Wark, Alwyn Birchmore Cox

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939

By Sanford Belden

My topic, Recent Developments in the Design of Electric Mine Locomotives and Mining Machinery, does not require me to go into a general review of electricity as applied to the mining industry. Interesting as that subject always is, what I might say in regard to it, by way of introduction, would be unnecessary use of your time, since such facts are familiar to all. First, we will consider the recent development of the electric mine locomotive. We may well pause for a moment to reflect upon its importance to the coal-mining industry of to-day. With the dawn of the electrical age its advent was inevitable. Our practical interest is aroused not so much by the first crude effort as by the great efficiency attained during the 30 or more years since the electric locomotive made its first appearance. To judge accurately what it means to coal mining, and through coal mining to the industrial field at large, we would have to know how many of these locomotives are in use throughout the country and their aggregate daily performance, and then compare the results with what could be expected with other forms of power. Such data are lacking, but it requires no statistician to make it evident that the electric mining machine is a tremendous factor in modern progress, and that without it the work of the world could never have reached its present magnitude. Not only has the electric mine locomotive served its own special branch of usefulness, but incidentally it has solved in the main the whole problem of electric transportation. It is but a step from the triumph of a 25-ton locomotive leading a long train of loaded coal cars from a mine to the electrification of common carriers. We may or may not be near any great change in this respect. Economical reasons may hold it back for an indefinite period. But the fact remains that in the development of our mine locomotives we have met this larger emergency, in mechanical type and efficiency, whenever it may come.

Jan 6, 1914

By Thomas Read

PERSONNEL work is a term recently introduced to cover the great variety of activities in industrial work that deal with the human factor. Much attention has been focussed upon individual phases of personnel work, such as accident prevention, sanitation, "welfare" work, reducing labor' turnover, and so on. In most cases these activities have been carried on as though they were distinct and separate fields; as a matter of fact, they are only different phases of the single problem of human engineering, and each has important and fundamental relations with the others. Thus, for example, high labor turnover is one of the most .important causes of a high accident rate, and unsatisfactory housing conditions are an important cause of labor turnover. In the early stages of the study of these problems, it was necessary to take them up separately; the time has now arrived at which it is desirable to consider them as a whole in order to bring them into the right relation to each other. When thus considered as phases of an interrelated whole, they may be grouped as personnel work. A discussion of the importance of personnel work as a means of in creasing dividends in industry may be objected to by some as a too materialistic way of looking upon work that is humanitarian. Nothing could he more mistaken than such an opinion. Humanitarianism, per se, has no place in industry, and nothing is gained and much is lost in pre tending that it has. The only reason why a corporation engages in business is to make profits, and any activity of the corporation that does not tend either directly or indirectly toward that end is poor business. It is equally poor business to overlook any activities that do tend indirectly to the making of profits. On this basis, personnel work can be justified as a corporate activity; there is no justification whatever for abstract humanitarianism from the business standpoint. One characteristic of the American workman is a general high level of intelligence, and it is an insult to intelligence to ask a man to believe that anything so impersonal as a corporation is really desirous of benefiting

Jan 10, 1917

By E. T. Turkdogan, M. T. Hepworth, R. P. Smith

The permeability of oxygen in 0 iron in the tempera-ture range 700" to 900 C and in 6 iron at 1450°C was determined by the rate of internal oxidation of iron, containing -0.1 pct Al. The solubility of oxygen in zone-refined iron was determined by equilibration with hydrogen-water vapor gas mixtures at 1450" and 1510°C; oxygen solubilities , for iron in equi1ibriu.rn with molten oxide, are found to be 66 and 83 ppm for these two temperatures, respectively. The diffusivity of oxygen in iron at 14500C3 as calculated from the permeability and solubility data, is (4.1 * 0.6) x 10 "B sq cm per sec. OXYGEN is one of the most common impurities present in iron or steel, mainly in the form of oxide inclusions. In the study of many metallurgical problems concerning solid iron, it is often desirable to know with a reasonable accuracy the solubility and diffusivity of oxygen over a wide temperature range. The solubility of oxygen in solid iron has been the subject of numerous studies yielding highly discordant results as seen for example from the literature surveys made by Meijering &apos; and Schenck et a1.&apos; As shown by Kitchener et aL3 and by Sifferlen, the high oxygen solubilities reported by many investigators are the result of oxidizable impurities which are often present in iron. In addition, there have been experimental problems associated with icaccuracy of oxygen analysis of iron containing less than 100 ppm 0. A number of studies have been made on the permeability of oxygen in a and y iron using Fe-Si, Fe-Mn, and Fe-A1 alloys in the internal-oxidation experiments.1&apos;2&apos;5&apos;6 However, no direct measurements have been made of the diffusivity of oxygen in iron. In the present work two sets of experimental measurements were made: permeability and solubility studies at 1450" and 1510°C and permeability studies only in the range 700 to 900°C. In both sets of permeability measurements slab-shaped specimens containing small predetermined amounts of aluminum in solution were exposed at constant temperature to gas mixtures of hydrogen, water vapor, and argon for varying times. These specimens were quenched, sectioned, and examined for oxygen penetration by metallographic observation of aluminum oxide particles which formed. From these data, it is possible to calculate the ratio of the diffusivity of oxygen in iron, D, to the equilibrium constant K for the reaction Hz(g) * O (dissolved in iron) = H,O(g). EXPERIMENTAL Permeability Measurements at 1450°C. An ingot of vacuum-carbon deoxidized iron containing 0.086 pct A1 was prepared, using commercial "Type lO4A Plas-tiron"; after hot rolling, specimens were machined into slabs a by 2 by 2 in. The impurity contents were: S, P < 0.002 pct; C, Mn < 0.01 pct; each of all other Usual impurities < 0.004 pet. The amount of oxide inclusions in this material, determined by a bromine-methyl acetate extraction, corresponded to about 20 ppm 0 in the iron which agreed well with the results of vacuum-fusion analysis. Each specimen was annealed at 1450°C for 1 hr in purified hydrogen, polished to a smooth surface, and then introduced into a controlled oxidizing atmosphere in a recrystallized alumina tube at 1450°C. The constant temperature zone (*3"C) was about 3 in. in length. The gas composition was controlled by mixing argon with hydrogen (using calibrated constant-head flow meters) and passing the mixture through a column of a mixture of oxalic acid dihydrate and 10 pct anhydrous oxalic acid, to establish a required water-vapor content in the gas mixture. The temperature of the oxalic acid dihydrate column was controlled by a thermostat. The total gas flow was in the range 800 to 1000 cu cm per min. The exit gas from the reaction tube was passed through a weighing bottle containing a desiccant, to cross-check the degree of water-vapor saturation, which for all experiments was about 97 pct of those derived from the data of Baxter and Lansing.1 For a typical experiment, a specimen was introduced into the furnace in a stream of dry argon and hydrogen. The specimen was then rapidly raised by a Pt-Rh alloy wire into the hot zone and allowed to reach the reaction temperature, at which time the oxidizing gas mixture was introduced. The oxygen potentials employed were sufficient to oxidize aluminum but not to cause liquid iron oxide to form. After a specified time, the experiment was ended by dropping the specimen onto a water-cooled copper block at the bottom of the reaction tube. The depth of the internally oxidized zone, hereafter called the "case", was determined by sectioning the specimen at right angles to the long direction. The section was then examined under a microscope equipped with a micrometer stage. In general, the oxide particles were fairly uniform in size and distribution, forming a reasonably well-defined interface between the oxidized and unoxidized region. A typical cross section as observed at X30 is shown in Fig. 1. A thermal macroetch was used in one selected specimen to delineate the case. A cross section of a previously oxidized slab was polished and reheated at 1450°C in a hydrogen atmosphere for about 10 min. Upon quenching, the surface relief shown in Fig. 2 was produced; causes of this effect are unknown. Permeability Measurements Below 900°C. A slightly

Jan 1, 1967

By J. Q. Ehrgott

INTRODUCTION The U. S. Army Engineer Waterways Experiment Station (WES), under sponsorship of the Defense Atomic Support Agency, has recently developed a unique dynamic high-pressure triaxial testing device (DHT). The device permits acquisition of both axial and lateral deformation data while undisturbed soil and/or rock specimens are subjected to various states of controlled impulsive-type stresses produced by varying both the axial stress and the radial stress rapidly with time. The device is used to develop controlled dynamic pressure pulses within the triaxial chamber fluid on soil or rock test specimens to 3 inches in diameter. Controlled dynamic axial pulse loads are delivered to the specimen by a piston driven by an existing pneumatic ram loader (SECO). The DHT consists of a triaxial cell and a pressure supply and decay system which permits the chamber pressure to be varied with time. Together the DHT and SECO operate in a testing program so as to provide time varying confining pressures and axial loads to test specimens at independently controlled but synchronized programmed rise, hold, and decay times. Rise time is defined as the time from zero load or pressure to peak load or pressure; hold time is the time of constant peak load or pressure; and the decay time is the time from peak load or pressure to zero load or pressure. The maximum dynamic confining pressure attainable is approximately 15,000 psi and the fastest rise and decay times are 3 millisecond (msec) and 20 msec, respectively. This paper presents a description of the DHT, the necessary support equipment, and details of the measurement system. Performance evaluation tests conducted on clay siltstone and a Cretaceous sandstone are presented since the results demonstrate some of the capabilities of the device and show some of its characteristics.

Jan 1, 1971

By C. H. Chou, Albert Sauveur

The following experiments were conducted in order to study the influence of the rate of cooling through and below solidification on the dendritic structure (macrostructure) and microstructure of some hypo-eutectoid steel. The steel selected was of commercial grade and had the following composition: C, 0.40 per cent.; Mn, 0.85; Si, 0.70; P, 0.099; S, 0.043. After melting in vacuum in an Arsem furnace, the various samples were allowed to solidify and to cool to room temperature as indicated in Fig. I. Samples were thus obtained representing all possible combinations of slow and fast cooling through the various ranges of temperatures indicated, namely: (I) zone of solidification or primary crystallization, (2) zone of granulation, and (3) zone of secondary crystallization. The location of the different temperature zones in the iron-carbon equilibrium diagram is shown in Fig. 2. The authors adopted Belaiew&apos;s notations. The designations of the various samples readily indicate their treatment, as will be apparent from Table 1. Sample SSS.—This sample was slowly solidified and cooled to room temperature in the crucible in which it was melted. The dendritic (macro) structure is shown in Fig. 3. The dendrites an: sharp and dis-

Jan 1, 1930

By Van Dyne Howbert, Fred E. Gray

The Presidio mine of The American Metal Co. of Texas is situated 45 miles south of Marfa, Texas, a town on the Southern Pacific R. R., and lies approximately 20 miles north of the Mexican border. Communication with the railroad is maintained over a state highway. All supplies for mine and mill are hauled in by truck from Marfa and precipitates and concentrates are freighted to the railroad by the same means and shipped to Selby and El Paso, respectively. The mill is at the town of Shafter, 1 mile from the mine and at approximately 350 ft. lower elevation. The ore is conveyed to it by an aerial tramway which requires practically no power on account of the difference in elevation. The mill is a countercurrent decantation cyanide and gravity concentrating plant of 200 tons daily capacity. Coarse and fine crushing are done at the mill. Two neal-by shallow wells in the bed of Cibolo Creek furnish an abundance of water. Power is generated for the mill and town by a Diesel engine plant. Ore Treated The ore is oxidized and siliceous. The greater part contains approximately 16 oz. of silver per ton, but mixed with this are many particles of ore of much higher grade, assaying in many instances 100 oz. or more. In the 16-oz. material there is an almost constant amount of silver which is difficult to recover by cyanidation. The high-grade material contains a much greater proportion of silver which is easily amenable to cyanide treatment. Thus, as the grade of ore becomes higher, the percentage of recovery of silver increases rapidly, under equal milling conditions. The silver minerals contained in the ore are principally argentite and cerargyrite, the former predominating The lead minerals, all of which are argentiferous, are chiefly cerussite and galena, with occasionally a little anglesite. The gold is free; most of the ore contains merely a trace

Jan 1, 1935

By W. B. Daly, A. S. Richardson

The application of artificial refrigeration, or air-conditioning, to the ventilation of deep, hot mines has long been a subject of interest to the operators of such properties. Artificial cooling of the air in theaters, railroad coaches, and various industrial plants has been so successful within recent years that it has been natural to assume that the adoption of similar methods would afford a ready solution to the difficult problem of mine ventilation. It should however, be obvious, that although there may be nothing technically impossible in the application of this process to mine ventilation there is a great economic distinction between the maintenance of a high standard of comfort for a large number of people in a relatively small space such as a theater and the cooling of air to improve working conditions for miners scattered throughout the extensive workings of a large mine. Many methods of air-conditioning have been considered by the management of the Anaconda Copper Mining Co. at various times, but until the development of the process to be described in this paper none has seemed economically practicable. The Ventilating Problem at Butte The main obstacle to satisfactory ventilation in the Butte mines is the normally high temperature of the granite country rock. In the present operating zone, rock temperatures as high as 120&apos; F. have been noted, and in some parts of the district the rate of increase of temperature with depth has ranged as high as 3.5" F. per 100 ft. Other factors, such as the decay of mine timber and the oxidation of sulfide minerals in the ore bodies, contribute to raise the temperature of the air in the working places but, particularly in the development of the mines to greater depth, the naturally high temperature of the rock is of predominant importance. In few other places, probably, are the ordinary ventilating measures more hindered than at Butte. At an operating depth now exceeding 3000 ft., all of the air required for ventilation must pass through timbered shafts which, because of heavy ground, are of small size and offer great resistance to the flow of air. Shaft compartments are rarely more than 4.5 X 5 ft., and the shaft area open to the flow of air usually does not exceed 65 sq. ft.; in only two shafts is the area as great as 85 sq. feet.

Jan 1, 1934

By N. Brown

From the theories of flow and fracture it is shown that the difference in reciprocals of the transition temperatures (OK) is a quantitative measure of temper ernbrittlement. Experimental data are given which support this conclusion. STUDIES of temper embrittlement have been made with various viewpoints; some involved a study of the kinetics of the reaction,&apos;,2&apos;" others were concerned with changes in the mechanical properties," . and still others investigated the structural differences between the embrittled and unembrittled states by means of the microscope," -ray ,&apos; measurements of electrode potential," and electrical resistivity." In all these studies, the difference in impact properties was the criterion for distinguishing between the embrittled and unembrittled states. By common agreement the difference in transition temperatures is now taken as a measure of the degree of embrittlement, and this measure is used as the quantitative measure upon which studies of the phenomenon are based. Vidal and Jolivet"&apos; suggested that the degree of embrittlement was the same whether measured by impact or by a slow bend test. Their conclusion was based on tests at constant temperature. Jaffe and Buffum" using the impact and slow bend test showed that, for a given degree of embrittlement, the difference in transition temperatures varied with the method of testing. Hultgren and Chang" showed that the difference in transition temperature produced by the V-notched Charpy impact test was not the same as the value produced by the keyhole-notched impact test. This is a very fundamental point because there can be no true measure of temper embrittlement unless it is invariant with respect to the test method. Theory The purpose of this analysis is to show how the transition temperature depends on the stress distribution and the state of the material. The criterion for fracture may be stated as follws: where iF is some function of the principle stresses and F is a critical condition depending on the state of the metal. Similarly yielding occurs when Where is another function of the prin-ciple stresses and Y is a critical value depending on the state of the material. There is some controversy as to the exact form of the function f,.(u,, u,, us) but most experimental data give the following criterion:= where 8, and 6, = 21 or 0. Combinations of 6, and 8, give the various criteria such as the normal stress, the hydrostatic tension, and the maximum shear stress laws. Agreement is general that the octahedral shear stress law adequately describes the yield condition. where the bracketed factor will be called the design factor and depends on the stress distribution. Whether the metal decides to yield or fracture is given by the condition that The effect of temperature and strain rate upon Y has been studied by various investigators, It has been shown by MacGregor and Fisher" that

Jan 1, 1955

By V. H. Wilhelm

The trend initiated in January 1936, of stabilized gasoline prices, increased demand and extraordinary drilling activity, continued in California during the year 1937. Crude prices were maintained during the year at the highest level since September 1930. Wildcat activity with resultant new discoveries and development of proven acreage were greater than in any year since 1928. Many fields in California in former years have been produced at full capacity, with consequent loss of reservoir energy, but at the present time continued activity is maintained to develop adequate reserves, so that production in these fields can be taken at a rate to correspond with good operating practice. Naturally, this good operating practice will be influenced to some degree by gas outlets and, in certain instances perhaps, by oil outlets. In any event, these last two controlling features will result in favorable rather than detrimental operation. In fields producing from great depths, ultimate production will be practically limited to the flowing and compressor life of the well, since there is as yet no economical method for pumping wells below depths of approximately 7000 ft. Experience has shown, however, that such pumping difficulties will be overcome and that production secured by pumping will add some to reserves established on the flowing life of the wells. California continued to operate under voluntary curtailment, but with unlimited transfers of allowable between various fields. Even though there was at all times considerable production above the Umpire&apos;s established quota, a constantly increasing demand reduced storage during the year. This increasing demand was due mainly to the rapid rise in Pacific foreign shipments from May to September. It is questionable, however, whether this favorable condition will be maintained over a prolonged period. (See Fig. 1.) Field Discoveries The great drilling activity during the year resulted in the discovery of three new fields in the San Joaquin Valley, as well as many extensions

Jan 1, 1938

By G. W. Tracy, R. D. Carter

Numerical calculations were made to determine the behavior of reservoirs with high-pressure drawdown and wide well spacing where the initial productivity is low and the wells are completed by hydraulic fracturing. The two-phase flow equations were solved for the flow into a single well. This well was assumed to be producing from a reservoir with hydraulically created horizontal fractures (four different systems with fractures were studied). For comparison purposes, additional two-phase flow calculations were made assuming a reservoir with uniform rock properties. The two-phase flow results were also compared with the conventional calculation methods, which do not include the effect of saturation gradients resulting from a simultaneous flow of oil and gas which are normal to this type reservoir. It was found that the conventional methods predict (1) a high and too optimistic value of ultimate recovery, (2) a high producing rate and a high reservoir pressure at a given oil recovery and (3) a low trend of gas-oil ratio with oil recovery. Included in the two-phase flow calculations were provisions to control the oil production rate by an allowable rate and, also, by a gas-oil ratio penalty rule. For the systems with hydraulic fractures, the producing rate was controlled by the gas-oil ratio penalty rule for most of the life. This is in contrast to the system with uniform rock properties which went "on decline" almost immediately. An unexpected characteristic of the systems which included fractures was the early rise in producing gas-oil ratio from 730 cu ft/bbl to approximately 1,200 cu ft/bbl, followed by a "leveling off" before the normally expected gas-oil ratio rise began. Additional features which are a result of hydraulic fracturing are (I) greater ultimate recovery, (2) higher average producing rates and (3) a lower average reservoir pressure at a given oil recovery. INTRODUCTION Some oil fields discovered during the past few years are producing from certain volumetric ally controlled reservoirs (often referred to as solution or internal gas- drive reservoirs) which are characterized by high-pressure drawdown at the wells. Since the available pressure drawdown at a well is limited by the static reservoir pressure and the producing rate is controlled by the available drawdown, wells completed in this type of reservoir usually produce at a rate less than the allowable from the time of completion. Because of this, this type of reservoir is referred to as a low productivity reservoir. Economic considerations require the use of wide well spacing and well stimulation by hydraulic fracturing to make commercial wells in this type of reservoir. Performance predictions for volumetrically controlled reservoirs have been made using a combination of two standard equations. 1. The "Schilthuis" or "Muskat" type material balance equation is used to relate the average reservoir pressure and the cumulative oil recovery. 2. The results from the material balance equation and the productivity factor as described by Pirson&apos; are used to relate the cumulative recovery with producing rate and time. The material balance equation assumed uniform pressure and liquid saturation conditions throughout a reservoir. The steady-state radial flow formula allows for a pressure gradient toward a well but assumes uniform liquid saturation. These calculation methods are adequate for application to reservoirs wherein the drawdown at the well to realize satisfactory producing rates is small compared to the total pressure. In low productivity, volumetrically controlled reservoirs, the pressure drawdown at the well is large cornpared to the total pressure. Although a precise number cannot be given for the magnitude of a large pressure drawdown, values in excess of 1,000 psi would definitely be included. For practical considerations, this usually occurs when the formation flow capacity is less than about 100 md-ft. However, this limit of formation flow capacity will vary with the well producing rate. The low pressure in the neighborhood of the well which results from a high drawdown causes evolution of large volumes of gas. This causes the gas saturation to be higher near the well than at a greater distance—-hence, a non-uniform gas saturation. Also, the relationship between the relative permeability to oil (K/K) and gas saturation is nonlinear but decreases approximately in an exponential way with increases in gas saturation. Because of this, the following chain reaction is established.

By A. L. Galpin

INTRODUCTION For many tailings ponds, particularly those having substantial watershed areas, the control of pond water levels will be a major factor influencing the operation of the pond and the design and construction of the dam retaining the pond. This paper summarizes the basic factors affecting the control of water in tailings ponds, methods of water control, and methods of estimating the variables involved. The influences that pond water levels can have on the design, construction, and stability of tailings dams are explained in order to emphasize the importance of water control in the overall planning of mine tailings disposal systems. Two examples of pond water control planning conclude the paper. BASIC FACTORS The principal factors influencing the control of water in tailings ponds are illustrated on Fig. 1. Fig. 1 (a) shows the general disposition of the tailings solids and water in the pond; the solids settle from the slurry to form "slimes", deposits sloping down into the pond from the points of discharge; these slimes hold volumes of water in the voids between solid particles; water in excess of this "retained" water forms a pool of "free" water laying over the slimes deposits. In some cases, tailings solids (and water) go to the tailings dam for its construction. Fig. 1 (b) indicates those ways additional to tailings disposal in which the pond gains or loses water. These include surface and sub-surface runoff from the pond watershed, water reclaimed from the pond for ore processing, evaporation, and seepage. Seepage losses sometimes include water draining from tailings sand placed in the dam, but a portion of the total seepage flow is often collected and returned to the pond in order to avoid downstream pollution and to recover water for re-use. PRINCIPAL REQUIREMENTS In relation to the control of water in a tailings pond, the first requirement is usually to maintain a pool sufficiently large to ensure adequate clarification of the free water prior to its reclaim for use in the mill, or its discharge from the pond.

Jan 1, 1972

By H. L. Luo, P. Duwez, C. C. Chao

BY rapidly cooling alloys from the liquid state, it is possible to obtain solid solutions beyond the equilibrium concentrations, provided that the components are miscible in the liquid state. Typical such cases include CU-Ag,1 Pt-Ag,2 CU-Rh,3 nickel-base alloys with silicon, germanium, and tin,4 and cobalt-base alloys with silicon, germanium, tin, aluminum, and gallium.5 In the present note it is shown that terminal solid solutions can be appreciably extended in A1-Mg alloys. The alloys whose compositions are given in Table I were prepared by induction melting in tantalum crucibles under an argon atmosphere. Both aluminum and magnesium were 99.99 pct pure. Weight losses after melting were less than 0.2 pct for the aluminum-rich alloys and less than 0.4 pct for the magnesium-rich alloys. From these weight losses it was estimated that the compositions of the ingots after melting were accurate within 0.3 at. pct for aluminum-rich alloys and within 0.5 at. pct for magnesium-rich alloys. As indicated in Table I, the compound AuCd10 in which there is an ionic contribution to the bonding. The authors thank Dr. J. H. Westbrook of the Research Laboratory, General Electric Co., for arranging the supply of materials and for his interest. This investigation was supported by the U.S. Atomic Energy Commission under Contract AT(30-1)-1002, Scope I. some of the alloys were also chemically analyzed and the results confirmed the limits of uncertainty based on weight losses. Rapid quenching from the liquid state was achieved by techniques previously described.8,7 The principle of these techniques consists of propelling a small globule of liquid alloy (about 20 mg) onto a copper substrate. The thin foils easily detached from the copper substrate were analyzed by X-ray diffraction using a Debye-Scherrer camera 114.6 mm in diameter and either nickel-filtered copper Ka or iron-filtered cobalt Ka radiation. Since the back-reflection doublets were resolved, the wavelengths used in the computatioas were CuKal = 1.54050A and CoKa1= 1.78892A. Lattice parameters were obtained by extrapolation of the Nelson-Riley function, and the tables compiled

Jan 1, 1964

By H. L. Bridgman

The correct sampling of ores is a subject of far greater importance than is usually conceded to it. Of the little which has been published on this subject, the recent paper by Mr. Glenn, with the accompanying discussion by Dr. Raymond (Trans., xx., 155), is the latest and best, and well worthy the careful perusal of all interested in accurate sampling, whether by hand or by machine. It is doubtless true that thorough hand-sampling gives as good average results as can be obtained; but all hand-sampling is subject to the possible incompetency, carelessness, or dishonesty of the workmen employed. It is, moreover, tedious and expensive, requires large space, and usually entails considerable delay, both in unloading and in sampling. For these and other reasons, machine-sampling is now regarded with more favor than ever before. So-called machine-sampling may be accomplished in two radically different ways: 1. Part of the stream of material is taken for the whole time. 2. The whole stream of material is taken for part of the time. Under the first case the stream, as it issrles from the deliveryspout of the crusher, is cut continuously in any given proportion, such as one-tenth, one-fourth, or one-half, by some fixed apparatus, which, as it contains no moving parts, is strictly speaking not a machine at all, but may be termed an appliance. The principle under which these appliances operate is now pretty generally conceded to be wrong, becanse of the practical impossibility of&apos; cutting such a

Jan 1, 1892

By George W. Neumann

The mines and concentrator of Brunswick Mining and Smelting Corporation are located in the northern part of the province of New Brunswick, approximately 20 miles distant from the City of Bathurst. Discovery of the No. 6 orebody by diamond drilling in 1952 was followed by the finding in March 1953, of the larger and higher- grade No. 12 orebody, approximately six miles to the north of the No. 6 deposit. Original development was financed by St. Joseph Lead Co., and included a small open-pit operation with a 10C ton per day pilot mill at No. 6 orebody, shaft sinking and underground development at No. 1; orebody, and an extensive program of laboratory and pilot plant metallurgical research on No. 12 ore. These operations were suspended in May 1958, and remained in standby condition until June 1961, when the equity of St. Joseph Lead Co. was purchased by a group headed by M. J. Boylen, K. C. Irving, Maritime Mining Corporation, and the Patino Corporation. Construction of a mine plant and concentrator at the No. 12 mine commenced in October 1962 and the concentrator was placed in operation in March, 1961b. Preparation of the open pit mine for production, construction of the No. 6 Concentrator to produce bulk Pb-Zn-Cu-Ag concentrate from No. 6 ore, and construction of an Imperial Smelting Process smelter at Belledune were started in 1964 and placed in operation in September 1966.

Jan 1, 1970

By G. E. Anderson

The Asientos-Tepezala district is in the north of the State of Aguasca-lientes, about 30 miles north of the city of Aguascalientes, the capital. The district is reached by a standard-gage railway on the west side through the junction, Rincon de Romos, which is on the main line of the National Railways of Mexico from El Paso to Aguscalientes. The terminal is Tepezala. On the east side a narrow gage connects Asientos with the junction, San Gil, on the main line, Asientos to San Luis Potosi. Tepezala on the west side of the Asientos hills is about 2 miles from Asientos on the east side. The area between the two mining centers is separated by a low subdued divide which forms the central part of the hills. The district is in a group of isolated hills surrounded by characteristic bolsón plains. The hills rise above the surrounding plains about 6500 to 10,000 ft.; the highest peak is Alta Mira. The two mining districts lie somewhat upon the flanks of the hills at about the same elevation, 7200 ft. The district is an old one and has been known since early in the 17th Century when the mines were worked by the Franciscan Monks. Their mining operations, which were limited to the oxidized ore above the water level, consisted chiefly in extracting silver from the Santa Francisca vein. To judge from the old workings and the remains of surface plant, the operations were on a large scale. By modern mining operations since about 1900, the various mines of the district have been one of the principal sourees of ore for the smelter located at Aguascalientes. Topography The topographic features of the Asientos hills are largely controlled by the character of the underlying rocks. During the Tertiary period, the entire group of hills was probably covered by extrusive volcanic material in the form of cones and lava flows. The central part of these have since been carried away by erosion, so that remnants have been left along the borders of the hills. These remnants form rather conspicuous peaks,

Jan 1, 1927

By V. R. Garfias

Although the work on which this paper is based was carried on by the writer as Special Commissioner of the Petroleum Department of the Mexican Government, the opinions expressed are only his personal views for which the Mexican Government can in no way be held responsible. Notwithstanding that the appointment covers all phases of the so-called petroleum question, as the one question of immediate importance was that relating to taxation, it was decided to devote all the time to this phase of the work. The present report has been divided into two closely related parts, the first dealing with the production and marine transportation of Mcxican petroleum, and the second, with the Mexican taxation on petroleum and its products. The writer wishes to acknowledge the loyal cooperation rendered by Mr. M. C. Ehlen, who had charge of the statistical work, and by Miss S. Stern and Messrs. E. P. Heiles and J. E. Morrissey. The aim throughout the work has been to pave the way for a thorough understanding between the Mexican Government and the oil operators and to present a true and clear statement of facts relating to the questions at issue. Mexican Oil Fields Development The salient features in the development of the Mexican oil fields may be summarized as follows: 1901. First commercially productive well in Ebano field. 1902. Tehuantepee field came in; Diaz Government granted concession to Pearson & Son on practically all Federal lands along the Gulf of Mexico. 1907. First producing well in the Furbero field. 1908. Dos Bocas well caught fire, advertising tremendous productivity of Southern oil fields of Mexico.

Jan 1, 1921

By Tell Ertl, Ernest E. Burgh

INTRODUCTION THE Bureau of Mines is operating an oil-shale mine 10 miles west of Rifle, Colo., as part of its Synthetic Liquid Fuels program. The purpose of operating this mine is twofold: First, to supply oil shale to an experimental processing plant; and second, to develop practices and select methods for mining oil shale on a commercial scale at the lowest practicable cost. The second purpose-that of finding out how to mine oil shale most cheaply-entails considerable mining research. Since the drilling of oil shale probably will be one of the major items of the mining cost, factors that influence drilling speeds were investigated. One phase of the drilling program was the development of a successful hard-surfaced rock-drill bit1 that can be used for drilling long holes in oil shale without changing bits. During that phase, drilling speeds were measured and drill cuttings were collected for assay and for screen sizing. When the cuttings from the individual tests were compared, a definite relationship was shown to exist between the drilling speed and the coarseness of the drill cuttings. PROCEDURE Measurement of Drilling Speeds All drilling in the tests was done with a Model UMB-D-99W Gardner-Denver wagon drill. Round-lugged drill steel, 1 ¼ in. in diameter was used in 6, 12, and 18 ft lengths with 2 1/8 -in. Timken H-type bits hard-faced with acetylene tube borium. The tests were made in the lower adit of the Bureau of Mines oil-shale mine; the grade of the oil shale drilled ranged from 18.6 to 42.7 gal per ton. During the experiments air pressure varied between 75 and 90 psi while water pressure remained fairly constant at 75 psi. All holes were drilled almost horizontally. Each drill hole was thoroughly cleaned of cuttings after being collared. The advance of the drill along the carriage was measured and recorded as the drilling speed in inches per minute. Method of Collecting Cuttings To facilitate the collection of cuttings, each drill hole was collared in a smooth, vertical portion of the oil-shale breast (Fig 1). A galvanized-steel sheet was fastened to the breast below the area in which the hole was to be drilled. The cuttings washed out of the drill hole by the drilling water were guided by the steel sheet into a wooden box. The cuttings that remained in the drill hole after the drill was withdrawn were scraped out and placed in the same box as the cuttings washed out of the hole. After the cuttings from a 1-min. drilling interval were collected, they were placed in flat metal pans. The fines were allowed to settle and the clear water was decanted. The cuttings then were dried in the sun.

Jan 1, 1947

By W. R. Bendy

GRINDING is a large and costly part of Portland cement manufacture. Prior to clinkering in the rotary kiln, raw materials are ground to a fineness of 80 to 90 pct passing 200 mesh. Then, after burning and cooling, the resulting clinker is ground to about 92 pct passing 325 mesh. In the cement industry the most favored method of grinding has always been by impact and attrition of a ball charge in a rotating mill. Other types of mills, in which materials are ground between die rings and rollers, or between die rings and large balls, are sometimes used for single-stage grinding and often for preliminary grinding followed by grinding in ball-type mills. Their efficiency is usually high, but maintenance and repair costs are high also, and the ball-type mill continues to be the most widely used. Together with 4 pct gypsum to retard setting time, the kiln run clinker—consisting of hard, semi-fused lumps that may have been crushed to — 1/2 in.—is ground to a Blaine surface area of 3000 sq cm per gram and about 92 pct passing 325 mesh. Approximately 32 kw-hr per ton, or 6 kw-hr per 376-1b barrel, are consumed in the grinding mills alone, not counting auxiliaries. Open Circuit Clinker Grinding: Many early clinker grinding plants employed two-stage, open circuit grinding. Comparatively short mills of large diameter, loaded with balls 4 in. and smaller, first reduced the clinker to 95 pct passing 14 mesh. Tube mills of smaller diameter and greater length, loaded with balls 11/4 in. and smaller, carried out the fine grinding operation. An early development was to assemble two or more stages of grinding in a single mill having two, three, or four compartments separated by division heads. There were difficulties in balancing the compartments, but compartment mills were popular in the 1920&apos;s because the layout was simple and there were no elevators and conveyors. Oversize Particles: Open circuit mills, whether separate ball and tube mills or compartment mills, always encountered the problem of tramp oversize in the product. A small percentage of clinker survived passage through the first grinding stage as particles—perhaps 1/16 in. diam—that were too large for the smaller balls in the following stages to reduce to —200 mesh. When the feed rate was lowered to reduce tramp oversize, there were serious losses in grinding efficiency. Many ingenious designs were perfected to incorporate perforated screen plates or wire mesh screens in the ball mills or in the first compartments of compartment mills. Their purpose was to prevent mate: rial passing out of the first stage until it was small

Jan 1, 1958