Search Documents

By J. Parke Channing

THE caving system of mining is that method of removing the ore from an underground body in which the top is first attacked and mined out and the capping, or roof, as the case may be, is allowed to fall in or "cave" and fill the space formerly occupied by the mined ore. It is applicable, generally, to large orebodies where the ore is relatively soft. We may say, within moderate limits, that when ore is removed the surrounding ground either caves in or remains open. For example, in mines like the Lake Superior amygda-loid copper mines, when the lode is removed there is left a void which remains open for many years; on the con-trary, mining a Lake Superior soft hematite ore, however carefully it may be done, always produces a caving of the surrounding rocks. We may say, with propriety, therefore, that the caving system is applicable to that type of ore deposit in which the surrounding rock readily caves. Another factor which governs the use of the caving system is the value of the ore itself. Admittedly, any form of caving will not extract 100 per cent. of the ore, and in the case of a very rich orebody it is often desirable to get out every pound of the ore with as little dilution as possible. Under these conditions, some other method of mining, such as that by square sets and filling, is indicated and should be followed. We may say, however, that, looking at it broadly, in the United States the caving system of mining is generally used for the removal of soft hematite and for the so-called "porphyry" coppers. In both cases this method is used where open-pit mining is not possible.

Jan 1, 1922

By D. L. Katz

A PHASE diagram showing boundary curve and quantity of liquid in the two-phase region was determined for a mixture of natural gas and natural gasoline in the region of its critical conditions. The tempera-tures and pressures of phase measurements were in the range of 85° to 212° F. and 1300 to 2600 lb, per sq. in., respectively, with the critical conditions at 169.5° F. and 2615 lb. per sq. in. abs, Color phenomena were observed in the region of the boundary curve from 102° to 192° F. Approximate densities of the single-phase and two-phase regions and analysis of the system are included. Boundary curves between the single-phase and the two-phase regions have been determined for several binary mixtures containing hydro-carbons. 2,3,4,6,7,10,11,12,14 These investigators did not report the relative amounts of liquid and vapor within the two-phase region. The equilib-rium values obtained from the dew-point and bubble-point data can be used to compute the lines showing percentage of liquid on the pressure-temperature phase diagrams but the positions of the lines near the critical temperature and pressure are uncertain. Relative amounts of vapor and liquid were obtained for a gasoline and a naphtha' within the two-phase area but not in, the region of the critical temperature and pressure. The bubble-point and dew-point lines, as well as the percentage liquid lines within the two-phase region, were determined by visual observations in glass apparatus.

Jan 1, 1939

By H. Van F. Furman

As the cyanide-method for the extraction of gold from ores is extensively used in the United States and elsewhere, and appears destined to prove a factor of increasing importance in the metallurgy of gold, a description of the latest laboratorymethods may prove of interest. The history of the development of the process in the United States has been analogous to that of all new processes. Many failures are to be recorded and a few successes. It is the opinion of the writer that, had the following simple tests been better understood, many of the failures would not have occurred, and we should probably have a larger number of successful plants in operation. While the process is not simple, but requires a high degree of chemical and engineering skill, the determination of the adaptability of an ore to the method is generally not difficult. While the laboratory-results will not always coincide with the actual results obtained in the mill, they will serve as a guide and control on the working of the mill, and mill generally suffice to determine if the ore can be

Jan 1, 1897

By Hans Haalk

PRACTICAL or applied geophysics-as we designate the border region between physics and geophysics on one hand and practical geology on the other-has as its object the application of physical or geophysical methods of investigation to problems of practical geology. Its field of operation comprises all methods of physical measurement that are used in the problem of determining, from the geophysical influences of the subsoil that can be measured at the surface of the earth, the special characteristics of the association of strata, faults, etc., to detect the presence of deposits and to investigate underground structures. It therefore repre-sents an aid, a physical method of research in practical geology, and is inseparably connected with geological studies; for this reason, it is also called geophysical prospecting. Formerly research methods of practical geology were based on observation exclusively: first, on the observation of the strata and formations at accessible parts of the surface of the earth, especially in shafts, borings and mines if such were available; then on the observation of the tectonic conditions in so far as these were already known at places directly visible; and finally, by estimation of the importance of formations of the terrane. Later, there were added in special cases, analytical chemical crystallo-graphical, petrographical and similar investigations of rock samples which were taken from the places under consideration. The knowledge thus obtained is of value and is expanded by hypotheses and constructions that are supported by geological theories of origin and by laws of the sequence of formations and rock systems, which are based on long experience.

Jan 1, 1928

By Arthur Young

UNEMPLOYMENT no longer finds its cure in pros-perity. Not only is there surplus labor in over-developed industries -like coal -mining, but more and more man, power is being released by technical im-provements in production. A new problem in industry has arisen: What is to be done with the labor dis-pensed with by better methods and more highly de-veloped equipment? Are luxury industries the logical outlet for our new unemployed? There has been a marked decline in employment in the manufacturing industries during 1927. Its extent is shown by the Bureau of Labor Statistics index, which receded from a high of 91.4 in March to 87.3 in October, with an estimated figure of approximately 85 in De-cember. This was a drop between the high and low points in the year of about 7 per cent, which means roughly that at the close of 1927 there were approxi-mately 600,000 fewer persons employed in manufac-turing industries than in March -of 1927, and upward of 400,000 less than in December, 1926. Does this de-cline reflect a swing toward industrial depression? Paradoxically it does not; the cause of unemployment at this time does not lie in a lack of prosperity, but rather is largely traceable to prosperity. Capital has been abundant and has gone back into production in the form of great increases in mechanization and new processing. Management is more than ever on the alert to improve methods, as well as to cut costs through reduction of personnel. Properly applied incentives and employee cooperation also have increased produc-tion per man. A new phenomenon in the industrial world-technological unemployment-is the result. Of course, there are added to those unemployed be-cause of the reasons just considered those affected by the coal strike, the period of shutdown at the Ford plants, and the reduction in expenditures by railroads and public utilities. This whole situation suggests that the problem of unemployment is not entirely solved by ironing out seasonal variations or by achieving business prosperity.

Jan 1, 1928

By J. L. Jones

1. Brinell tests at progressively increasing temperatures are given for a representative lead-base and a representative tin-base babbitt, showing that the former has superior resistance to deformation at the working temperatures of bearings. 2. Small squares of bearing bronze, tinned and then babbitted with a representative lead-base babbitt and a representative tin-base babbitt were subjected to compressive loading. The lead-base babbitt showed less average compression than the tin-base babbitt. Compression did not materially increase the Brinell hardness of the babbitts. 3. A process and a tool are described for giving smoother and more accurate surfaces to bearings than has heretofore been possible. The following experiments have recently been carried out in the chemical laboratory of the Westinghouse Electric and Manufacturing Co., Pittsburgh, Pa. While the work is incomplete, it is described at the present time because data on the comparative merits of lead-base and tin-base babbitts are of interest in connection with the present shortage of tin. BRinell Habdness of Babbitt at Increasing Temperatures Bearings fail because of wiping, or deformation. Hence tenacity is desirable in a bearing metal, especially tenacity at high temperatures. The Brinell test is commonly regarded as a measure of tenacity. In fact, it has recently been proposed to substitute for Brinell hardness number the expression " tenacity number."l It seemed, therefore, that the Brinell test was especially adapted for the tests described. Disks, 4 in. (101 mm.) in diameter and 1.5 in. (38 mm.) thick, were made of the babbitts to be studied, designated A, B, C. They were poured into metal molds, pyrometer leads being soldered in the center of each disk. The composition of the babbitts was as follows:

Jan 1, 1919

By M. H. Rana, W. D. Bullock

A basic requirement in any geomechanical investigation is the establishment of the state of stress in the rock mass. So far, qualitative determinations have been more readily obtained than quantitative ones. This is due to the fact that in order to define stress magnitudes in a rock mass it is necessary to make various basic assumptions about the physical properties and characteristics of the rock itself. The assumptions are generally that the rock is an isotropic, homogeneous solid which will behave elastically under various conditions of applied load. These assumptions are not valid. Due to the foregoing factors, the present investigation was confined to a consideration of stress directions only. Within recent years, two methods of determining stress orientations in geologic materials have been used and have received some publicity in the technical press. These are the techniques of photoelasticity and petrofabrics. The technique of using reflected polarized light for observing strains on the faces of rock samples has been described by Emery.1,2 With this technique it is possible to measure relative strains in relaxation. Absolute strain magnitudes are not attainable without the use of questionable assumptions. However, directions of strains (and thus, stresses) can be determined accurately on a point basis or on a statistical basis over the complete area of the strain gage being used. Petrofabrics, according to Friedman,3 an important geological discipline which can provide knowledge on the state of stress associated with naturally deformed rocks. Even though textural and structural features span at least 15 orders of magnitude, from crystal lattices

Jan 1, 1972

By F. F. Colcord

THE electrolytic separation of silver and gold has been practiced by the refineries in the United States for a good many years; and probably because of frequent visiting between officials of plants and the consequent exchange of views, operations in the various silver and gold refineries are very similar. We find, for instance, they practically all use electrolytes of approximately the same composition, which, no doubt, is more the result of experience than of studies of electrolytes. At the new electrolytic parting plant of the U. S. S. Lead Refinery, Inc., East Chicago, Ind., considerable attention has been given to the, composition of electrolytes, especially to their conductivity and their effect on the character of the silver deposit. We are not aware that anything has been recently published on this subject and are, therefore, presenting such data as we have with the idea that, although it will not be wholly new, it may stimulate interest in the subject. EFFECT OF COPPER CONTENT ON CONDUCTIVITY The first work, was to determine the specific conductivity of silver nitrate and copper nitrate solution. Concentrated solutions of silver nitrate and copper nitrate were prepared by dissolving analyzed chemically-pure salts in distilled water, and determining the silver and copper in each. Definite amounts of the concentrated solutions were taken, mixed and diluted to a definite volume. The silver and the copper were determined in each of these solutions and the conductivity was, then determined. The plotted results are shown in Fig. 1 and 2. The effect of increasing quantities of silver and, copper is readily seen. A comparison of the two sets of curves shows conclusively the benefit of holding the copper content of the electrolyte above 50 g. per liter, as its

Jan 2, 1926

By Nichols J. Grant, Bill C. Geissen

In low temperature phase diagrams, liquidus curves below about 1500°C are relatively easily established, e.g., by thermal analysis or separation of coexisting solid and liquid phases, followed by chemical analysis. Experimental difficulties increase considerably at higher temperatures and in systems involving more reactive metals. Although there are now thermocouples available for use from 1600" to 2400°c, as summarized by Caldwell,' the need for frequent calibration, aging, and contamination problems, and unavailability of suitable protection tubes has sharply limited their use at higher temperatures. Many of the high melt- ing metals are found to react with refractory oxides. TO avoid such problems, a frequently used procedure is the diffusion and saturation method, as described by Spedding et a1.' for the system La-C. This technique involves the annealing of one metal or a suitable alloy in a crucible of the other element at a temperature above the melting point, followed by chemical analysis of the center of the melt, after equilibrium is established. Further, if an alloy system is to be investigated employing the electron microbeam probe, and calibration charts have been established, it may be possible to measure the alloy concentration at the center of a cored as-cast structure, and to conclude from this points on the liquidus curve in a manner similar to the one to be described. It is known that in phases with a broad homogeneity range the rapidly cooled, cored, as-cast structure of an alloy presents concentrations having different lattice constants; this spread of lattice constant values contributes to the broadened lines of a powder pattern for the as-cast condition. The region of the crystal which is first to solidify will then correspond to the edge of the lines if the change of the lattice parameters with concentration is monotonous. In the course of the determination of the Ta-Tr phase diagram,3 it became evident that such behavior made it possible to construct the

Jan 1, 1963

By Ronald F. Ayers

The basic research for this study was conducted by Battelle's Columbus Laboratories in 1974. The high-sulfur content of coal threatens to erode its competitive position in the future. The impact of sulfur removal on final costs of eastern interior coal lies at the very heart of this market analysis. An extensive market survey was conducted that considered both traditional coal markets as well as anticipated future markets. Competition for coal from this province considers low-sulfur Western coal, nu- clear power, international oil and coal trade, as well as Appalachian coal producers. Based on projections of future energy consumption under several scenarios, a comprehensive market forecast for eastern interior coal was made to 2040. The study upon which this paper is based was completed by Battelle's Columbus Laboratories for the U.S. Army Corps of Engineers in 1974. It is but part of an overall effort by the Corps to evaluate the costs and benefits to the nation of waterway improvements. This study is primarily concerned with future coal markets for production from those counties near the Wabash River in the heart of the Eastern Interior Province. An objective here is to consider a most pessimistic energy (and hence, coal) demand for planning purposes.

Jan 1, 1978

By G. K. Burgess

§ 22. THe results published in Professor Howe's paper10 of our determinations on the Ac3 and Ar3 points for a series of commercial carbon steels " containing manganese in varying proportion, represent the average temperatures found by taking several (4 or 5) heating and cooling curves. The accompanying curves, Figs. 6 and 7, are, for each steel, the first heating and cooling curves as obtained by the inverse-rate method of Osmond, using a cylindrical chronograph sensitive to 0.1 sec. for recording time. Simultaneous observations were also taken by the differential method with a platinum neutral and plotted by Rosenhain's derived differential method and gave substantially the same results, the curves having sensibly the same contours in both cases.12 The observations were taken in vacuo on cylinders 5 by 1 in. in length bored to center with a 1/8-in. hole to receive porcelain insulated thermo-couple, and inclosed in an out- and in-glazed Berlin porcelain tube heated electrically by platinum foil wound on the tube. The vacuum was usually better than 0.1 mm. The heating and cooling of the furnace was automatically controlled by a salt-water rheostat with shaped electrodes, giving a uniform rate of heating and cooling.

Jan 1, 1914

By Joseph Hartshorne

For something over two years past a new development of the open-hearth process has been in operation at the works of the Prager Eisenindustrie-Gesellschuft at Eladno, in Bohemia. It was devised and perfected by Mr. Ernst Bertrand, general superintendent,, and Mr. Otto Thiel, steel-works superintendent. The results which the inventors wished to obtain were to increase the product per furnace, to reduce the amount of refractories and additions used, to enable a poorer and more varied quality of stock to be employed, to improve the quality of the material produced and to render the control of the operations and product more certain. In all of these objects they have been successful, and have thereby considerably reduced the cost of manufacture and increased the value of the finished material. The Plant. The plant at Kladno consists of one 12-ton and one 20-ton furnace. Through an incident of construction the smaller furnace stands some distance behind and to one side of the larger furnace, and at a height of about 10 feet above it. The furnaces are in the same building as the Bessemer converters, and the metal is handled in the same casting-house by means of a locomobile ladle-crane. The relative position of the furnaces suggested the experiments by which the process was developed, and also enabled it to be thoroughly tested. Much valuable and practical work has been done in this plant, although it is not as convenient and suitable as one especially designed for the process would be. Nevertheless, the pecuniary and technical results have warranted its continuous operation. The Process. The process, as at present carried out at Kladno, consists

Jan 1, 1897

By William Fink

THE investigation of aluminum alloy systems prior to 1923 was severely handicapped by the low purity of the best aluminum available. However, by that time, the electrolytic purification of aluminum had been developed by the Aluminum Company of America,(1)? and in May, 1923, there was initiated, under the direction of E. H. Dix, Jr.,(2) a program for the investigation of the aluminum-alloy systems using the purest electrolytically refined aluminum. Up to the present time 15 papers (a) have been published, most of which are on the binary aluminum systems. Work is now in progress on the ternary systems, and it seems probable that most of the future work will be on ternary systems. Therefore this survey of the binary aluminum systems investigated up to the present time (the sixteenth paper of the series) concludes the first phase of this program. Certain qualitative relations between corresponding portions of the various binary diagrams as well as between different parts of the same diagram were noted some time ago by R. S. Archer.(4) In the present . paper these relations and others are considered quantitatively by the application of well-known thermodynamic equations or by newly discovered empirical relations No attempt will be made here to present the history of the develop-ment of the thermodynamic equations defining equilibrium or their application to metallic systems, although a list of references is given at the end of this paper for those who are interested in this phase of the

Jan 1, 1934

By Hadyn W. J. Wren

The practical experience obtained from designing and commissioning of fully controlled coal preparation plants, using centralised mini computers is discussed. The importance of defining a workable operating philosophy is highlighted with particular reference to the problems associated with trying to achieve a total 'hands off' concept. These experiences with a centralised computer controlled system have led to a deeper understanding of the interaction between the operation and the control system and the role of local control and management information within the overall control philosophy of a highly automated process plant. The utilisation of an extensive fully distributed microprocessor control system with over 6500 digital and analogue signals split into six autonomous areas with a supervisory system to provide operator interface is described. The important aspects of project definition and design needs are outlined with particular regard for achieving maximum efficiency with minimum complexity. Views of future trends are offered, based on the experience of both centralised computer and distributed processor systems.

Jan 1, 1984

This study of engineering education arose out of the action of a joint committee on engineering education, representing the principal engineering societies. The committee had gathered so much material that it decided the work could best be carried out by some one trained in applied' science, who would devote his entire attention to the study.. The Carnegie Foundation therefore asked Prof. Charles R. Mann, of the University of Chicago, to undertake the work. After making a thorough study Prof. Mann has made a most comprehensive report. In it he says: The engineering schools of the United States began their work upon a definite teaching plan and one that had at least pedagogic consistency. But during the past half century the course of study has been overlaid with many special studies intended to enable the student to deal with the constantly growing applications of science to the industries. As a result, the load upon the student has become so heavy that there is a feeling that the students fail to gain a satisfactory grounding in the fundamental sciences and do not fulfil the expectations of engineers in d manufacturers in dealing with the practical problems with which they are confronted on leaving school. At present 60 per cent. of those who enter the schools fail to graduate, still many of them persist in engineering and make a success of it. It is evident, therefore, that the present systems of admission are not satisfactory. If a group of schools will take up the careful study of their entrance systems and experiment with objective tests and records of the students' youthful interests and achievements, the percentage of elimination can be reduced to at least a fourth of its present size, with an enormous saving of time, energy, and money for both student and school. The number of required credit hours per week should be less than eighteen, preferably sixteen. The few experiments that have been made indicate that college students do their best work when not more than five subjects are studied at a given time.

Jan 1, 1919

By D. G. Deveraux

A BRIEF SKETCH OF THE DAVE JOHNSTON MINE The Dave Johnston coal mine is located near the southwestern extremity of the Powder River Basin in central Wyoming. This mine is operated entirely for the purpose of furnishing fuel to the 750,000 Kw Dave Johnston power generation station located five miles east of Glenrock, Wyoming on the North Platte River about 24 miles east of Casper, Wyoming. Coal is delivered to the power plant by a company-owned railroad moving the coal 15 miles downgrade from the mine to the power plant. The mine first belonging to Pacific Power & Light Company has now been transferred to Northern Energy Resources Company (NERCO), a mining subsidiary of Pacific Power & Light Company. The coal beds which make up the field at the Dave Johnston Mine are locally referred to as the School and Badger seams and occur beneath gently rolling terrain in the Fort Union formation. The School seam is found approximately 180 feet beneath the Badger in the southern portion of the field and about 110 feet beneath the Badger towards the north. The coal beds dip down toward the northeast on about a four percent average inclination. The School seam has an average thickness of about 35 feet and the Badger seam about 16 feet. The climate at the Dave Johnston Mine is semi-arid, with annual precipitation varying between 10 and 12 inches with 70 percent occurring during the months of April to September, with the maximum occurring in May. A few storms occur in July and August which are usually torrential in character, often causing erosion damage to un- protected soils. Snowfall averages 50 inches a year at the mine with 12 to 15 inches of snow yielding one inch of moisture. However, snow seldom

Jan 1, 1983

By John Birkinbine

The estimated product of iron-ore in 1888 throughout the world was, in round numbers, 50,000,000 gross tons, of which the United States produced about one-fourth. Great Britain leads this country in production by about 15 per cent., but the output of the United States is practically equal to that of Spain, France, Russia, Austria and Hungary combined. We produced last year nearly twice as much iron-ore as Spain, with all her exports; and we mined 20 per cent. more than Germany and Luxemburg. In addition to the domestic iron-ores consumed in this country, 587,470 gross tons of foreign ore was imported, and the amount of mill-cinder used in blast-furnaces is estimated at 450,000 gross tons. The total quantity of iron-ore required in 1888 for blast-furnaces, rolling-mills and other purposes in the United States was approximately 12,700,000 gross tons. The purpose of this paper is to indicate the principal sources of this supply, and call attention to the extent of mining operations covering many years in certain localities, which, although some of them now produce but a small proportion' of the above total, have in the aggregate added very largely to the material

Jan 1, 1889

By O. G. Bell

Development and exploratory work continued vigorously during 1933 in Southwest Texas and, from a standpoint of new production discovered, the new discoveries probably equal or may even exceed any previous year in the history of this area. While exploratory work has been general over the area much of it has been confined to two localities; namely, northern Duval-southern McMullen counties and Starr County. A persistent effort has been made to open new productive areas in northern Duval County and the adjacent part of McMullen County, occasioned primarily by the fact that the Government Wells group of fields in northern Duval County have been by far the best fields so far developed in this part of the state, and the possibility of being able to find new fields in the same general area under similar geologic conditions. This has resulted in the discovery of three new fields, Northwest Government Wells, Moca and Eagle Hill. In addition encouraging shows have been found in North Kohler, Hoffman, Smith-Hunter and the Ignacio areas with the prospect that continued exploratory work will develop some of these prospects into fields. Wildcatting in Starr County was the continued result of an effort to find a trend of production through the county southwestward from the older Reynosa Escarpment fields in Webb, Jim Hogg and Zapata counties. This same impulse has caused most of the wildcatting in Zapata County. New Fields Cuevitas.—During the early part of the year the Sun Oil Co. began some core-drill work on a block of leases in northern Starr County, then in June drilled a test which found production in the McElroy member of the Jackson at 2200 ft. Drilling in this field has continued but the productive area has not as yet been clearly defined. Seven oil wells and three gas wells have been completed. There is as yet no pipe line outlet for this production, hence no productive history of the wells has been

Jan 1, 1934

By M. W. Strong

THE technique of handling drilling muds varies somewhat, partly because of personal factors but mainly because of differences in forma-tion, the type of problems met with, and the general drilling conditions in different localities. The much greater depths to which bore holes are now carried have made necessary closer attention to and great modifications of all aspects of drilling-mud technique. Increased depth means smaller hole, smaller drill pipe, smaller clearances, higher pumping pressures, higher differen-tial pressures between shows and the mud column, less accurate control of the weight of the mud column, delayed receipt of formation data, and poorer samples. It means longer delays and greater hazards in rectifying mistakes or dealing with accidental occurrences. Equipment on a larger scale is necessary and more pains must be taken with layout. Lastly, the budget costs of raw materials have risen to high figures and economy of time and of direct monetary expenditure have come to mean much more than formerly. A mud laboratory is now part of the essential establishment of a modern oil field and to it current problems can be submitted for the most thorough investigation. The detailed chemical properties of all mate-rials purchased or quarried have to be investigated. Detailed data on the physical properties have to be ascertained and research on improve-ment of material and its most efficient use has to be carried out. In this paper we propose to discuss the main mud problems with which we have to deal in Iran, some of which are peculiar to our local conditions while others are of the general type common to all workers in this subject.

Jan 1, 1938

By Takahide Wakamatsu, Shigeru Mukai

Fundamental investigations were made on the treatment of slime and the chrysocolla flotation, both of which are urgent problems to be solved in copper oxide mineral flotation. Unfavourable effects of slime on flotation are caused by the slime adsorption at the air/liquid Interface as well as the slime coating on the mineral surface. The adsorption of slime at the air/liquid interface was measured by using various kinds of slime particles. As a consequence, goethite, bentonite and talc tended to adsorb markedly at the interface. As a desliming method, slime flotation with a polymer flocculant such as polyethylene-oxide prior to the ordinary copper oxide flotation was found to be effective. The use of both a copper-avid organic reagent and an alkyl xanthate was examined for a selective collection of chrysocolla through xanthate adsorption tests, chrysocolla float- abllity tests and flotation tests for synthetic and natural ore. The copper-avid reagents used were salicylaldoxime, 8- hydroxyquinollne and benzoin-a-oxime. As a result, the ad- sorption of higher xanthate such as amyl xanthate on chrysocolla as well as the chrysocolla-to-air bubble attachment was increased by the presence of a copper-avid reagent under suitable reagent addition and pH of pulp. Flotation tests for synthetic and natural ores confirmed that chrysocolla could be floated sufficiently and selectively with a copper- avid reagent like 8-hydroxyquinoline or salicylaldoxime with its subsequent collection by amyl xanthate.

Jan 1, 1976