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By Francis Lucas

A microscope objective of given numerical aperture, whew used with light of given wave length, has some fixed limit of resolution. This may be expressed as potential resolving ability-the ability to resolve is inherent in the lens but whether this limit is achieved in practice is quite another matter. Nearly 50 years ago Abbe evolved theoretical considerations which indicated that the ability of a lens to resolve detail is directly proportional to twice the numerical aperture of the objective and inversely proportional to the wave length of the light used. It is true, unquestionably, that as the numerical aperture of the objective is increased the potential resolving ability of the lens is increased and likewise whew the wave length of the light used is decreased, the degree of resolution is increased. Whether Abbe's formula expresses the exact relationship is not a matter of great concern. It suffices to know that to improve resolution, other things being equal, two avenues of approach are available. Either the numerical aperture of the objective may be increased or the wave length of the light decreased. With the apochromatic system it is possible to employ successfully wave lengths from 400 to 500, µµ and still secure reasonably short exposures. The present limit for numerical aperture is 1.40 N. A. although objectives of 1.65 N. A. are wow an experimental possibility for metallurgical work. Thus certain well defined limits are set for those who work within the range of the visible spectrum. In order to take advantage of the increase in resolving power which accompanies a decrease in the wave length of light employed, Dr. A. Köhler and Dr. M. Vow Rohr of the Zeiss Scientific Staff developed the "monochromats." These are quartz objectives corrected for the single wave length 275 µµ which lies in the ultra-violet region of the spectrum. They also developed a series of quartz oculars and a complete photo-micrographic equipment with which to use the quartz optics. Quartz must be used for the optical parts because glass absorbs ultra-violet light almost completely. Thus there was made available about 20 years

Jan 6, 1926

By A. P. Herring, M. Hoover, D. W. Fuerstenau

The dissolution of nickel, copper, and cobalt from five different samples of well-characterized deep sea manganese nodules was measured as a function of temperature, pH, leaching time, and particle size. Nickel, copper, and cobalt extraction each respond to these variables in a different manner. The results of this investigation indicate that copper and nickel can be selectively dissolved from iron and manganese at moderately low pH, provided the reaction is given sufficient time. A high dissolution of cobalt with dilute sulfuric acid can only be achieved from nodules that have a low iron content (<5%). The most probable rate-controlling step for copper and cobalt dissolution is diffusion through the pores of the nodules, and for nickel dissolution chemical reaction appears to be rate-controlling.

Jan 1, 1974

On the following pages are abstracts of papers published by the Institute during the year 1934 as TECHNICAL PWLICATIONB, CONTRIBUTIONS, m bound volumes and in MINING AND METALLURGY. For abstracts of papers that appear In bound volumes in 1934 but that were published as TECHNICAL PWLICATIONS m 1932 or 1933, see the TRANSACTIONS for 1932 and the YEAR BOOK dated January, 1934. Many of the TECHNICAL PWLICATIONS have been reprinted In bound volumes Information regarding this disposition, and number of pages in each paper, may be found m the list beginning on page 92 Volume numbers are given as listed at the beginning of the index, page 99 The abstracts are grouped as follows:

Jan 1, 1935

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Jan 1, 1946

By Charles S. Barrett, Frederick N. Rhines, Robert F. Mehl

The solid solutions which aluminum forms with copper, and with magnesium and silicon, are not extensive, and accordingly could not be expected to form Widmanstatten figures profusely nor with great ease. A study of the Widmanstatten figures in these systems seemed desirable, however, because of the interest which these alloys bear towards age-hardening theories resulting from the necessary relationship between the age-hardening phenomena and the atomic processes leading to the formation of Widmanstatten figures.&apos; Alloys of Aluminum with Copper The most accurate determination of the solid solubi1it.y of copper in aluminum seems to be that by Dix and Richardsoq2 whose results are represented in Fig. 1. According to this work, aluminum dissolves 5.6 weight per cent of copper at 548", and less than one per cent at room temperature. Judging from the constitutional diagram, this solid solu-lion on cooling tends to precipitate the compound CuA12, and this conclusion has been confirmed experimentally by Schmid and Wassermann.

Jan 1, 1932

By W. C. Snow

The plant of the Electrolytic Zinc Company of Australasia Limited, situated at Risdon on the estuary of the River Derwent, near Hobart, was designed and erected primarily to produce high-grade zinc from zinc concentrates produced by the mines of Broken Hill, N. S. W. Consequently the metallurgy of the process has been influenced in its development by the peculiar characteristics of the Broken Hill concentrate, which on treatment gives into solution relatively large amounts of cobalt, manganese and silica. The Risdon works (Fig. 1) produces high-grade electrolytic zinc, leaded electrolytic zinc, zinc dust, cadmium, sulphuric acid and superphosphate. This paper, however, is concerned only with the zinc plant and process. Roasting The roasting of raw concentrate is not a major feature of Risdon&apos;s process, and in this respect practice is unlike that of most zinc plants. The roasting is mostly done on the Australian mainland at centers where the sulphuric acid made from the roaster gases can be used for superphosphate manufacture. A small amount, approximately 40 tons per day, is roasted at Risdon, acid being manufactured from the gases. The amount that can be roasted there is limited by the acid requirements of the zinc plant and of the superphosphate plant. Roasting is not carried to completion at the mainland plants, and the product, known as preroast calcine, largely constitutes the raw material for the Risdon zinc plant. It contains about 6 per cent of sulphur as sulphide. Roasting is completed at Risdon for reasons that are set out later in this paper. The zinc plant proper is divided into four main divisions: (1) final roasting division, (2) leaching and purification division, (3) electrolytic division, (4) melting and casting division. There are two subsidiary divisions—the cadmium division and the preroast, acid and superphosphate division.

Jan 1, 1937

Jan 1, 1914

By Philip Bucky

THE general conception of a mine model is that of a three-dimensional object representing the mine workings, the orebody and the country rock of a particular property. Its chief uses have been to make it easier to understand the mine and to serve as a basis for the arguing of legal questions. Fayol endeavored to use mine models in a different way and to all students of subsidence "Fayol&apos;s dome theory" is of decided interest. We have more recently the suggestion of Young and Stoek of the University of Illinois, who1 suggest the use of models as a means of studying the problem. Prof. Henry Briggs, of the University of Edinburgh and Herriott Watt College, also makes use of models to determine the effects of bending at the edges of extensive workings.2 It is interesting to note that civil engineers are taking a decided interest in the application of models and the principles of dynamic similarity to the solution of their problems. The Proceedings of the American Society of Civil Engineers for 1930 contain an elaborate article by Benjamin F. Groat,3 who says, in his opening remarks: "Every engineer should know and understand that a model constructed in accordance with Newton&apos;s theory of similarity is not only the means for reproducing the complexities of flow, or other mechanical action, on a small scale, but that models may be made the best means of designing works of great magnitude. In the present state of knowledge, a properly constructed and properly tested model will answer the difficult questions of hydrodynamics much more quickly and accurately than the most profound mathematical analyses." A study of P. W. Bridgman&apos;s book on Dimensional Analyses leads one to arrive at the same conclusion.

Jan 1, 1931

By Desmond De Villiers Oxford, Peter H. Williams

Nchanga Consolidated Copper Mines, Ltd., is one of the four mines operated by the Anglo American Corp. in Northern Rhodesia, now the independent nation of Zambia. Today Nchanga is the second largest single producer of copper in the world, accounting for more than 200,000 long tons of copper annually at a monthly milling rate of 430,000 tons of ore. The average mill-head grade is about 5.20% total copper, of which approximately 60% is copper sulfide. The remainder, referred to as "acid soluble," is copper oxide. Nchanga mines three separate orebodies varying in grade and sulfide-to-oxide ratio. Ore is processed in two separate grinding circuits feeding into three separate flotation circuits. A fourth flotation circuit treats leach plant residue for additional recovery of sulfides.

Jan 1, 1965

By Louis P. Gignac

INTRODUCTION The selection of trackless equipment for underground mining can be a complex engineering problem due to the wide range of equipment sizes and operating modes. Computer simulation is particularly useful in estimating the performance of different systems for specific rock- handling problems. A hybrid simulator, incorporating some of the features of deterministic and stochastic simulation, was developed in order to handle not only queuing delays at loading and dumping points, but a1 so traffic interferences. Any number of vehicles can operate in any one of four basic modes (LHD, LAF, FEL, HFC) in parallel or in series. If the units use common roadways, loading and dumping points, certain operating delays will occur and be registered by the simulator and thus give a better evaluation of the marginal productivity of each additional unit. Based on a typical layout of drawpoints and ore passes for the sub-level stoping method, productivity and operating costs of different rock-handling systems will be examined. 1 . COMPUTER SIMULATION Numerous applications of computer simulations are reported in the 1iterature for various mining problems. Depending on the complexity of the system to be studied, simulation models were conceived with different degrees of sophistication. Three different types of simulators are generally recognized: stochastic, deterministic, and hybrid. Stochastic or Monte Carl o simulation randomly generates items, transactions, or events from some population defined by a frequency distribution and produces some expected future situations. Because this type of simulation is governed by the input of probability distributions, it requires a detailed knowledge of the system to be simulated; it implies expensive and time-consuming studies and reports to gene- rate this input information. A major short- coming of stochastic techniques is in new equipment evaluation, where the lack of data is unavoidable, and in new system design where the conditions are outside the range of the known historical behavior of the equipment. However, probabilistic simulation is almost essential for the study of cyclic queues and traffic problems. Deterministic simulation studies a system by generating performances on the basis of the mechanical capabilities of the vehicles and the physical limitations of the mining scheme. It is based on the engineering principle that the engine converts its energy into a rimpull at the wheels, which is in turn opposed by the rolling resistance and the grade of the ground; the machine is accelerated or decelerated until the tractive and resistive forces are in equilibrium, at which point it moves at constant speed. The information required by this technique, such as rimpull charts and equipment weight, is readily available from equipment suppliers. However, equipment performance at the mining site is also dictated by human and environmental conditions and changes with time and usage. For this reason, deterministic simulation generally overestimates the system capabilities; these must then be adjusted by efficiency factors based on observation and experience. Recently, hybrid simulation models, using both stochastic and deterministic techniques, have been built with some of the events generated stochasticly and others being deterministic. This compromising approach originated at the Pennsylvania State University. O&apos;Nei1 (1966) designed a simulator for truck-and- shovel operations that allows for transportation from multiple faces to mu1tiple destinations. Each truck performs according to its mechanical capabilities while its loading and dumping time and its load fluctuate according to specific probability distributions. A major advance in the simulation of mining systems is due to Sanford&apos;s model (1969) of underground coal mining operations. The originality of the model is in the use of an Executive System Control which sets up the initial system, de- fines the operation conditions , and instructs continuously four sub-assemblies representing shuttle cars, trains, continuous miners , and conveyors, which in turn generate a feed-back of their movement to the Executive Control System for further instructions. The model has enough flexibility to simulate simultaneous and sequential jobs that characterize any dynamic system. Sanford&apos;s early work evolved slowly to what is known today as the Under- ground Materials Handling Simulator for coal mining (Manula, 1974).

Jan 1, 1981

By Randy M. Cole, Peter J. Phillips

A methodology is presented which quantifies six coal utilization cost components, each proportional to a coal&apos;s mineral content. These are: Ash disposal costs, coal transportation costs, plant maintenance costs, reduction in plant peaking capacity, reduction in plant rated capacity, and reduction in plant availability. Numerical examples illustrate that coal containing between. 12.5% and 25.0% ash-plus-sulfur can cause incremental utilization costs ranging from less than $1.00 to more than $8.00 per ton of coal, when combusted in a pulverized coal fired power plant. Estimated costs are then compared to historical data and the conclusion drawn that steam coal beneficiation may have broader economic justification than sometimes realized. It is noted that TVA, which first proposed the methodology and parameters used here, is continuing research on this aspect of coal utilization.

Jan 1, 1981

By Dale I. Hayes

Combined loader and transport, the Gismo is now built for sale in one size, 5 to 6 tons. It will operate in a minimum opening of 7x7 ft and can be built to operate at lower heights. Where space limitations are not a factor it could be designed with much greater carrying capacity-12, 18, or 25 tons-to be powered with a standard heavier tractor. The Gismo is mounted on crawler tracks of the same design as the tracks of the small Allis- Chalmers HD-6B tractor used to power it. With the HD-6B tractor it will negotiate upgrades of 12 pct and downgrades of 20 pct. The next tractor size would make the device feasible for steeper grades or for a machine of larger capacity at moderate grades.

Dec 1, 1956

By LEWIS F. THOMAS

MINING geologists and mining engineer, rarely give due thought to the geography of mining deposits. They realize, it is true that what may be ore in one place would be only worthless rock in another because f the in accessibility of a smelter r a market; and they may consider the lack of a supply of labor, or water, or power to carry on operations. But they do not think (of these things in terms of geography. Geography may be defined as the science of relationships between earth and man, so geographers are vitally interested in the how and why of mining as it is carried on at different place, having entirely different environment-. Such environments are geographic complexes or composites of natural and cultural elements, which are listed and briefly discussed in the following paragraphs.

Jan 1, 1941

By Eugene A. Stephenson

In November, 1932, Dr. Lacey, of the California Institute of Technology, presented before the American Petroleum Institute some of the results of his research under Project 371. The investigations described dealt particularly with changes in the physical properties of petroleum that result from the solution of natural gas therein. The solubility of Santa Fe Springs dry gas, containing 87 per cent methane, 8 per cent ethane and 5 per cent propane, had been determined in various crudes at 100&apos; F., and 2000 lb. pressure per square inch as shown in Table 1 and Fig. 1 herewith. Originally the computations were made in terms of cubic feet per barrel, but&apos; for a more uniform basis of comparison the results are also shown as cubic feet of gas2 per cubic foot of oil.

Jan 1, 1935

By J. L. Gillson

The big mass of anorthosite in the Lake Sanford district and the bodies of titaniferous magnetite that occur in a small area near the south margin of the mass have been described repeatedly, and the puzzling problems of the genesis of the rocks and ores have stimulated the deductive reasoning of geologists for a hundred years. Some of these men have taken a leading part in describing the anorthosite rock and forming hypotheses concerning its origin; some have contributed most to the study of the ore deposits; and some have made classical Studies introducing a basic approach to the problems of the anorthosite rock and genesis of the titaniferous magnetites. Much of the writing on the problems of rock and ore genesis has been based on physical-chemical reasoning rather than on field and microscope observations of the rocks and ores. Most of these geologists conclude that the anorthosite was formed by true magmatic crystallization, involving previous settling or squeezing out of ferromagnesian minerals from the parent magma. The associated gabbro is a separate segregation or later intrusion, and the lighter colored and finer grained facies of the anorthosite is either a chilled border zone of the anorthosite or the result of granulation by crushing of the coarse, dark blue rock of the main mass. This blue rock, called the Marcy type, is named after the highest peak in the range. The finer grained and lighter colored rock is called the Whiteface, after another mountain appropriately named for a cliff colored by this facies of the anorthosite.

Mar 1, 1956

Jan 1, 1907

By Cyril Stanley Smith

Although alloys of copper and silicon were examined several years ago,&apos; and their excellent mechanical properties were shown, it was not until C. B. Jacobs 2 introduced manganese in small quantities to the alloys that they became of commercial importance. A few years ago The American Brass Company took over the patents and commenced to manufacture the alloy under the name "Everdur." The present study of the constitution of the ternary system was undertaken in order to reach a fuller understanding of the behavior of the alloy. Review of Previous WORK on the BinaRy Systems There have been no papers published dealing with the constitution of the ternary system, although some tests of the mechanical properties have been described," which indicate that there is a change in solubility with temperature. Copper-silicon System The copper-silicon system has been studied in detail by the author and is described in two papers published in 1928.V he portion of the diagram up to 8 per cent. silicon, as determined by this research, is reproduced in Fig. 1. The author&apos;s previous papers include a complete review of the work of other investigators and it is not necessary to deal further with this system here. Copper-manganese System The copper-manganese system has been investigated by several workers, notably Lewis,5 Wologdine,6 Sahmen7 and Schemtschuschny,

Jan 1, 1930

By Willard Ide Pierce

The Department (formerly called State) of Tolima, which is beginning to attract considerable attention in this country on account of its mineral wealth, comprises an area of 18,415 square miles, lying between latitude 1" 34&apos; 25" and 5" 44&apos; 12/" N. and between longitude 74" 25&apos; 45" and 76" 34, 25" W. from Greenwich. It is bounded on the north by the Department of Antioquia, on the east by the Departments of Cundinnmarca and Cauca, and on the south and west by the Department of Cauca. It is the most recently created of the States of Colombia, having been established by decree of April 12th, 1861, and being composed of the old provinces of Mariquita and Neiva, and of the districts Melgar, Carmen, Cunday and Santa Rosa, of Tequendama.

Jan 1, 1888

By Donald Barton

THE theory of gravitation is based on Newton&apos;s law that any two bodies exert a mutual attraction which is proportional to the product of their masses and inversely proportional to the square of the distance between them; i. e., A = K MM/R2 (1) where K is a constant, M and m are the respective masses of the two bodies, and R the distance between them. In the earth&apos;s gravitational system, the earth is one of the bodies; the other may be any body within or without the earth. In theoretical discussions and calculations in regard to gravity, that other body usually is taken as a unit of mass: in the C. G. S. system, a body of one gram in mass. GRAVITY AND LEVEL SURFACES Gravity is defined in geophysics as the force of attraction exerted by the earth, towards itself, on a body of unit mass. The intensity of gravity is usually expressed in dynes of force or in centimeters of acceleration. In geophysical work in America; most commonly it is expressed in dynes (per gram) with the "per gram" understood and not directly expressed. In geophysical work in Europe, most commonly it is expressed in centimeters per second per second (cm./sec.2) and less commonly merely as centimeter-gram-second units (C. G. S.). At sea level, the intensity of gravity amounts very nearly to 980 dynes. The vertical is the direction along which the attraction of gravity is exerted at any point. In most cases, it is very nearly, but not quite, perpendicular to the earth&apos;s surface. The path that would be taken by a body falling freely through space toward the earth is vertical at each point and may be spoken of also as "the vertical," or as the line of the vertical, or as a line of force of gravity. At the earth&apos;s surface it commonly is very nearly, but not quite, a straight line.

Jan 1, 1928

By C. G. Fink

A PART of the material incorporated in this paper was derived from the studies of ancient metal objects examined by the authors from time to time for museums and art collectors, in order to verify the age of the metal. The data thus accumulated during several years was systemati-cally surveyed and supplemented by new material obtained in examina-tion of a set of specimens that had been generously donated by museums for this study. Altogether over 50 pieces were investigated, of which 39 are described in this paper. Every specimen is at least 1500 years old; the majority are considerably older. Exact conditions to which these bronze and copper objects were exposed in the ground are unknown, unfortunately. It is safe to say that exposure conditions did not remain constant during the long period of burial. Although the collection of specimens studied represents a wide variation in location and age of the objects, as well as in the nature and composition of the metals, it was found that fundamental changes in the metal structure were limited to a few typical cases which, therefore, may be considered as more or less general. The authors&apos; chief aim was to study the effect of extremely long periods of corrosion on the structure of bronze and copper.

Jan 1, 1936