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By AIME AIME

FOUR separate groups of conveyors are installed in the Morenci Reduction Works as follows: (1) Ore-handling conveyors from the primary crushing plant to the coarse ore bin, from the coarse-ore bin to the secondary crushing plant, and from the secondary crushing plant to the ore bin in the concentrator plant. (2) Conveyors in the mill section of the concentrator plant. (3) Conveyors handling concentrate from the filter plant to the bedding plant, and from this plant to the smelter. (4) Conveyors handling flux and custom ore in the smelter crushing plant and to the bin at the bedding plant.

Jan 1, 1942

By Dr. O’Neil Thomas J., Donald W. Gentry

Who steals our gold and silver, and copper, zinc and lead? Who takes the joy all out of life and strikes our high hopes dead? Who never wrote a schedule that to anyone else was clear? The sulphur-belching, miner-welching, smelter engineer. -Anonymous From "The Engineer," Engineering & Mining Journal, Apr. 13, 1918 INTRODUCTION A striking characteristic of publications devoted to the principles of engineering economy and investment analysis is that the revenue side of the equation is generally either ignored entirely or addressed only in a superficial manner. This is understandable to a degree in the general case because methods of revenue estimation are highly dependent upon the specific type of project under consideration and the nature of the market served. An important contributing factor, however, is that developing estimates of future sales prices for most products is a risky activity which is less amenable to credible quantitative modeling than other topics in investment analysis. The specific subset of capital intensive investments addressed in this book- mining projects-is particularly sensitive to projections of mineral prices, many of which are notoriously volatile. Furthermore, the unique nature of mineral markets, prices, and product specifications occupies a major role in mineral project evaluation. Even here, however, authors have tended to offer little assistance to the reader in estimating project revenues. For example, the most popular mining engineering textbook for four decades, Elements of Mining (Lewis and Clark, 1967), contains the following advice on estimating future mineral prices (pp. 359-360): "Since the life of the mine will extend over a number of years the future price of mineral products must be estimated in order to calculate the probable profit to be realized. Current prices may be used, but it is preferable to take the average price for the past 25 to 35 years as it covers definite business cycles. Some engineers believe that a mine should make a small profit if its highest-grade ore is marketed at the minimum price during the past 35 years. Business

Jan 1, 1984

By Elizabeth L. Robinson

INTRODUCTION The financial structure of the mining industry has changed strikingly over the last thirty years. The changes that have taken place in the last ten years include both the acceleration of adverse trends in familiar balance sheet numbers and ratios, and the subtle but extensive increase in the complexity and diversity of funding sources, both on and off the balance sheet. The objectives of this paper are: 1. to briefly trace the evolution of trends in the mining industry's financial structure; 2. to focus in more detail on changes in the last decade; and 3. to analyze those trends both within the framework of capital structure theory, and in the context of changes in business and economic conditions. This survey focuses primarily on the mining companies listed on the major U.S. stock exchanges, since financial data for these firms are readily available. The producers of minerals are a diverse lot, however, and the quantitative data on "the mineral industry" as characterized in this survey fails to encompass the financial arrangements for the bulk of production worldwide, whether owned by governments or private-sector enterprises. Even large portions of the U.S. minerals industry - subsidiaries of still larger firms, medium-sized privately-held companies, and the small miners - were not included in the quantitative part of the analysis. THE EVOLUTION OF THE INDUSTRY'S FINANCIAL STRUCTURE In the aftermath of the business failures of the Great Depression, most borrowers and lenders considered minimal debt on the balance sheet the soundest policy. By the 1950's, however, a body of literature was developing which demonstrated that the use of leverage could improve the value of the firm, given a corporate tax structure which allows interest, but not dividends, to be deducted from income. Optimal Capital Structure The objective of undertaking a new project is to improve the wealth of the current owners of the firm. If internally-generated funds are insufficient to allow growth at the desired rate, the company can raise funds either by issuing new equity, or by incurring debt. The most attractive source is the one which will provide the funds for the lowest cost. Both stockholders and lenders expect to receive compensation for use of their funds at a rate which reflects two things: (1) the return they could earn in alternative investments, and (2) the riskiness of the projected return. Factors which increase business risk include the variability of demand, sales prices and input prices, and "operating leverage", or the proportion of fixed to variable costs. In addition, from the investors' point of view, the use of financial leverage concentrates risk onto the shareholders, because lenders enjoy a prior claim in the event of bankruptcy. So although financial leverage can increase a project's expected rate of return, and therefore, presumably, earnings per share, too much debt will be perceived as uncomfortably risky by equity investors, and have a negative effect on stock prices. In theory, then, there should be an optimal level of debt which the firm's managers should seek to obtain in its financial structure. The desirable proportion of debt should in general be lower for a firm with a higher inherent business risk. In addition to their own judgement, financial managers are sensitive to the attitudes of lenders, rating agencies, and investment bankers in setting financial targets (Scott and Johnson). In practice, financial structure will also depend upon the company's growth rate and level of profitability, and conditions in the capital markets at a given time.

Jan 1, 1985

By W. D. France, H. l. Burghoff

FABRICATORS of copper and copper alloys have contended with the problems of reconversion during the past year in endeavoring to return to the full-scale production that is demanded of them. The problems have not been easy, for the industry, like so many others, has had to deal with strikes of long duration, and material shortages, particularly in the raw materials, copper, zinc, lead, and tin. Despite all these obstacles, it was possible to gear production to new peacetime records during the latter part of the year. This was made possible not only by the use of multiple shifts of personnel, but also by the improved production equipment, the development of which had been stimulated by wartime necessity. The work of installing new and better equipment is still continuing, and virtually every company is engaged in improving or planning to improve its processes.

Jan 1, 1947

By WILLIAM BOWIE

THE development of the isostatic idea during the last century would make an interesting paper in itself. But the various steps in the development have been covered in a number of papers and books which are readily available. Therefore this short paper should not give space to. the historical phases of the subject. Isostasy is really an old idea, but it is only in the last few decades that it has taken on any great prominence or importance in the study of earth phenomena. It is really remarkable how closely Dutton' sensed the isostatic principle 40 years or more ago. His general principles of isostasy as outlined by him have stood the test of time and fit in closely with the general ideas held today. It would seem, however, that some of his views with regard to the application of isostasy to geological processes must be modified or abandoned.

Jan 1, 1930

By A. B. Stickney

UPWARDS of 200,000 engineers in this country are sufficiently interested in engineering as a profession to have joined a society, but not over 10% of them belong to any one society. There is a widely-felt need of an over-all organization of all the societies to act as spokesman for all engineers on matters of common concern. On a local basis, over 100,000 engineers in 35 metropolitan areas have organized themselves into local councils, and are doing an effective job of intersocietal co-operation within their sphere of activity. In the last few years much has been said and written about a similar organization on a national scale. Everybody wants iteverybody is talking about it-it's in the air-it's coming-it's inevitable. Although it is no longer necessary to talk about why or whether there should be such an organization, there is no such unanimity about what it should be like. This paper outlines a proposed organization by answering four questions-who, how, what, and who will pay for it.

Jan 1, 1946

By Albert Sauveur

Jan 1, 1924

By Albert Sauveur

Jan 1, 1924

By Sidney A. Swensrud

This paper reviews the subject of gasoline margins, discusses some of the more current marketing problems, and gives some consideration to the main urges to marketing expansion, or overexpansion, in the oil industry. Margins In an earlier paper1, some comparisons were shown for the years 1929, 1930 and 1931, of the margin between the refinery cost of gasoline in Oklahoma, the market price in Oklahoma, and the average retail price in 50 representative cities of the United States. These figures indicated a small margin for the refiner in 1929 between his gasoline cost and the wholesale price, which, however, had turned into a loss by 1931. The margin between either refinery costs or wholesale prices and the retail price in the 50 cities showed a continuous decline during the three years. We have now worked out these figures on a similar basis for a longer period—from 1928 through 1936. The figures for refinery gasoline cost are slightly different from those in the earlier study, owing to the use of

Jan 1, 1937

By L. D. HUNTOON

MY first article on Canadian Gold, published in the Canadian Mining Magazine in 1911 expressed the view that the Hollinger mine would repay all the money invested and that other mines would be developed in this area. Many published forecasts have since been made. Quoting from the Northern Miner of Oct. 29, 1931: "It will be noted in studying the chart prepared by this engineer that his forecast for 1931 at $50,000,000 was too modest, as the output for this country this year will be closer to $54,000,000."

Jan 1, 1932

By Raymond Mancha

THE purpose of the Coal Division's Committee on Ventilation is to cover one principal aspect of mine ventilation thoroughly each year, instead of attempting to touch upon several different subjects. The Committee for 1943 consists of four members besides the Chairman. Members, selected because of both knowledge of the current topic of mine ventilation, and diversity of occupation, are: Carel Robinson, consulting engineer with an operating background; T. G. Fear, chief engineer for the Hanna Coal Co., an operator of varied experience in mine ventilation; E. H. Denny, chief of the coal mine inspection division of the U. S. Bureau of Mines, obviously well qualified; and C. M. Smith, editor of Mechanization with a background of mine ventilation study as a member of the mining department of the University of Illinois, at present retained as a ventilation consultant by the Climax. Molybdenum Co. of Climax, Colo.

Jan 1, 1944

By AIME AIME

A. A. Holland, Consulting Engineer, Toronto, Ont.-I noticed in this discussion of locations in which radium is found, no mention is made of the recent deposits discovered in Ontario. While radium is not a subject with which I am very familiar, I took an interest in this deposit on account of its novel occurrence. It is found in Haliburton County, near Wilberforce, Ontario, associated with a quartz free pegmatite, in a "break" that I understand can be traced for two miles. This "break" marks the contact between the limestone and syenite and contains numerous cavities or vugs. The gangue, on account of its deep purple, appears to :be amethyst.

Jan 1, 1930

By D. Weinstein

The high temperature mechanical properties of stainless steels after fast neutron irradiation are discussed in the light of effects caused by lattice dattmage and effects caused by helium generated from n,a transmutations. Embrittlement at high temperatures is due to helium accumulation at grain boundaries and to cavity formation and proPagation along grain boundaries. Following from the embrittlement mechanism, it is suggested that when deformation occurs by mechanisms associated with super plasticity, helium ac-curnulation at boundaries should be attenuated and cavities, if formed, should be nonpropagating. As the mean free Path between interphase boundaries of a two-phase Fe-Cr-Ni alloy was decreased, the degree of superplastic deforrnation at 870°C increased, as vneaszired by total elongation and by the expottent m = a log 'a/a log 'i. This alloy and type 304 stainless steel were cyclotron irradiated in an a-particle beam to a helium concentration of -1 x 10 atom He per atom. The stainless steel specimen was embrittled, but the ductility of irradiated two-phase Fe-Cr-Ni alloys correlated with the values of. m during 'defor-malion. The .finest grained, helium-injected specimens that deforrned with highest m values exhibited the largest elongations to ,fracture. These results could be correlated with metallographic observations of cavity behavior: the propensity for intergranular propagation was lessened as the m value increased. It is concluded that superplastic deformation is ef-fectizle in attenuating helium embrittlement at elevated temperatures. One of the principal problems associated with development of fast breeder reactors is application of alloys such that suitable fuel cladding results. Stainless steels and other Fe-Cr-Ni alloys, because of highly acceptable nuclear characteristics, represent the primary materials for this component, and an exhaustive research and development effort is being conducted. The main deficiency of these materials has been a severe loss of ductility at high temperatures after fast neutron irradiation. An extensive body of mechanical property data and microstructural observations has provided an adequate phenomenological description of embrittlement; in conjunction with transmission electron microscopy studies, a reasonably acceptable embrittlement mechanism has been obtained. Following from this mechanism, it is suggested in the present work that ductility would be enhanced if deformation could occur by mechanisms associated with the phenomenon of superplasticity. Experiments to test this hypothesis have been conducted, and the results are presented and discussed in this paper. IRRADIATION EMBRITTLEMENT AT HIGH TEMPERATURE Austenitic stainless steels have been irradiated to accumulated fast neutron fluences of 1020 to 1022 nvt at temperatures between 60" and 600°C. Specimens that have been exposed to these conditions and subsequently tensile tested at temperatures between 600" and about 900°C exhibit approximately 5 pct total elongation to fracture.'-3 For unirradiated specimens receiving a nearly identical thermal exposure, total elongation at these test temperatures is about 45 pct. Examination of irradiated specimens has shown that fracture propagation is entirely intergranular. These phenomenological aspects of irradiation embrittle-ment at elevated temperatures are well known and are not generally disputed. Although the explanation of this phenomenon has been controversial, a mechanism for ernbrittlement has emerged that accounts reasonably well for the observed mechanical behavior. The controversy resulted primarily from an indeterminate role of neutron-in-duced lattice damage, if any, and a presumed, but experimentally unverified, contribution to embrittle-ment from helium generated by n,a transmutations. Recently, Holmes and coworkers4 have conducted experiments that separate these effects, and the results are instructive in formulation of the ernbrittlement mechanism. Holmes el al.4 irradiated type 304 stainless steel in EBR-I1 to a fluence of 1.4 x 1022 nvt (E > 0.18 mev); the irradiation temperature was 538" * 48°C or, in terms of absolute melting point, 0.49 * 0.03 T,. After irradiation, tensile tests were conducted at temperatures of 21" to 870.C, the specimens first being annealed for 30 min at each test temperature. In addition, thin sections of irradiated specimens were annealed for 1 hr at identical temperatures, electro and examined by transmission electron microscopy. Thus, for a given temperature, it was possible to correlate mechanical properties with the defect structure. At room temperature, the yield stress of irradiated specimens was a factor of 2.5 higher than unirradi-ated specimens exposed to an equivalent thermal history. Electron microscopic examination of the irradiated specimen revealed a high density of lattice damage in the form of Frank sessile dislocation loops and polyhedral voids. Holmes et al.4 concluded that the presence of this defect substructure caused the increase in yield stress and that after irradiation in a fast neutron flux at 0.49 Tm, substantial lattice dam-age persists. Annealing at progressively higher tem-

Jan 1, 1970

By BLAllEY STEVENS

(Canal Zone Meeting, November, 1910.) I. INTRODUCTION. TEH object of this paper is to show how igneous intrusion is governed by definite mechanical laws. A distinction is made between dikes and fissures, and the various characteristics of intrusions are explained on an exact scientific basis. The modification of rock-stresses by intrusion is then considered and extensive isostress regions are recognized. Finally, a complete classification of intrusions is constructed covering all pos-sible cases. The generalizations of observed data, taken from Geikie's Textbook of Geology, conform to the laws of intrusion herein stated, and the deductions based upon these laws. No authority, however, is quoted for the type which I have named a corrugated intrusion. Its existence is a necessary deduction from the laws of intrusion, and even the entire absence of examples in technical publications cannot disprove its reality. In all probability, corrugated fissures would have remained undiscovered, but for the working of mineral veins. As intrusions of tabular form are seldom worked for commercial purposes, it has been left for theory to anticipate the discovery of corrugated dikes. In the light of these laws of intrusion and the corresponding laws of fissures,1 there seems to be a remarkable uniformity of stress-distribution in rocks at moderate depths. This renders .possible the mathematical calculation which should help us to approximate exact science in this and kindred branches of applied geology.

Jan 1, 1911

By Thomas T. Read

THE fact that certain types of ore-deposits have attained their present condition through the action of descending surface waters was, perhaps, first clearly pointed out by Posepny.1 The oxidizing effects of such waters were discussed by Penrose,2 and many papers dealing with this phase of the subject have subsequently appeared. That secondary enrichment of sulphide ores, however, might be produced by descending surface waters was not clearly understood until after the copper-bearing veins of the Butte district, Mont., had been carefully studied by the geologists of the U. S. Geological Survey, al¬though De Launay3 had suggested that sulphides might be transported from point to point and re-deposited in the zone above the level of ground-water. As a result of the study of the Butte district, two papers by geologists engaged in the work appeared within a short interval. The first by Weed,4 dealing with the enrichment of veins by later metallic sulphides: and the second by Ernmons,5 treating of the secondary enrichment of ore-deposits in general. In the latter paper it was pointed out that a typical vein of sulphide ores which has been subjected to the action of descending surface waters exhibits four zones,-an upper or surface zone, in which the changes have been mainly of removal, the products being typically oxides; a second zone of oxide enrichment, in which the less soluble metals brought from above have been precipitated as carbonates or oxides; a third zone of sulphide enrichment,

Mar 1, 1906

By M. G. Jones

AT the Edwards mine a 4 by 81/2-ft two-compartment shaft is used for men and supplies in the older workings down to the 900-ft level. All ore is hoisted through a 5 by 15-ft three-compartment vertical shaft which extends to the 1500-ft level. Ore pockets are on the 1300- and 1500-ft levels. The two-compartment countershaft used below the latter level is 6 by 12 ft inclined at 42°. Ore from the countershaft is hoisted to the 1350-ft level where it flows by gravity to the 1500-ft level ore pocket. One-ton skips are used in balance in the countershaft and two-ton skips, also in balance, from the 1500-It level to the surface. These skips are slung under the man cages. Each level has an ore pocket of 200 tons' capacity. Development at Edwards is similar to that at Balmat except that haulage drifts are only 7 by 7 ft. They are mucked with Eimco-Finlay No. 12 loaders. A drill carriage similar to that used at Balmat is being tried out on the new 2300-ft level, the present bottom of the mine. Drifts are driven below grade and later raised 6 in. and ballasted with waste leaving a ditch 6 by 12 in. at one side for drainage. All development is done on an incentive bonus system, the miner paying for his explosives.

Jan 1, 1947

By Donald B. Gillies

PROBABLY the most critical and difficult period in an engineer's career is that between the completion of his college work and his attainment of professional recognition and accepted status in the industrial world. Upon leaving school the young graduate breaks his immediate ties with his educational institution and in a sense finds himself adrift. At this time in his life a society like our Institute has both the responsibility and the privilege of meeting a vitally important need in his professional life. Some of these young men are Student Associates, in the year after graduation, and some are Junior Members, but all need advice and assistance. In some respects this situation will be accentuated by the war. Not only will thousands of young engineers be mustered out of military service but the process we describe generally as industrial reconversion will make necessary many readjustments in personnel. About two years ago the Institute recognized the opportunity of helping the younger member to help himself by appointing a new standing committee to be known as the Committee on Professional Development of Junior Engineers. Herbert Hoover is Honorary Chairman and it is my privilege to serve as Chairman. The name of the Committee is not entirely satisfactory but it expresses the general objective. The present article is in the nature of a progress report of the work of this Committee.

Jan 1, 1945

By Robert H. Richards

It has long been known to boiler makers and to the users of cylindrical pipes of many kinds that when a tube is exposed to internal fluid pressure the resolution of forces is such that the material of the walls of the tube is exposed to twice the stress in the direction tending to produce longitudinal rupture, as it is in the direction to produce circumferential fracture. By longitudinal fracture is meant the fracture by a rent parallel to the axis; by circumferential fracture is meant fracture by rents running round the cylinder. In consequence of this the makers of boilers always lay the fibre of their metal in direction round the boiler, and the same is true with the makers of gun-barrels. I have never seen any good and simple illustration of this law until I met with it in blowing glass. If a thin bubble of glass be blown out in a spherical form and then exploded it will be found that the particles tumble into totally irregular shapes, showing no special direction in the molecular structure of the material. If now a bubble of glass be blown out and so manipulated that it will take a cylindrical form (see accompanying illustration), and then be exploded, it will drop into ribbon-shaped pieces from end to end, and the only parts that will be found to differ from this form will be the two hemispherical ends which will remain whole, having a fringe of ribbons representing the line of their fracture from the cylinder. The main point of difference between this experiment and the

Jan 1, 1883

By FORTUNATO PEREIRA

(San Francisco Meeting, October, 1911.) I. GENERAL DESCRIPTION. The Department of Narino (formerly included in the Department of Cauca) is a narrow band about 170 km. (100 miles) wide in the southern part of the Republic of Colombia, FIG. 1.-SKETCH-MAP OF THE SOUTHWESTERN PART OF COLOMBIA. near the boundary of Ecuador, as shown in the sketch-map, Fig. 1. Its capital is Pasto, a small city of 25,000 inhabitants; the principal towns are Túquerres, Cumbal, Ypiales, Barbacoas, and Tumaco. The port on the Pacific ocean is Tumaco, and traffic in the interior is carried partly on the Patia river (steam navigation to the fluvial port of Barbacoas), and afterwards overland over poor roads by human bearers or on mule-back.

Aug 1, 1912

By F. S. Norcross

MANGANESE has long been considered one of the United States' most important strategic raw materials. Its indispensability in steel manufacture makes it vital to the nation's industrial life. Coupled with this indispensability is the fact that domestic producers have not been able as yet to supply more than a small part of the nation's manganese needs; consequently the United States has had to depend upon such distant foreign sources as the U.S.S.R., British India, the African Gold Coast and Brazil for the major portion of its ore. The great bulk of the mineral is consumed in the form of ferromanganese, an alloy that averages 8o per cent manganese and 20 per cent mainly iron and carbon. Manganese is used as a deoxidizer and desulphurizer in steel manufacture. By combination with the residual oxygen and sulphur of the bath, it helps to produce a clean, sound metal. Approximately 14 lb. of manganese, it is estimated, is used in making one ton of steel. For standard-grade ferromanganese, the ore should have a minimum of about 48 per cent Mn and preferably more. Beneficiation methods have not yet been developed for making the immense low-grade deposits in the United States salable at prevailing prices. Dependence upon foreign sources thrust the United States into serious difficulties during the World War. At the start of hostilities in 1914, the nation was obtaining about four-fifths of its ore from the Eastern Hemisphere. Domestic production had been negligible, amounting to only 3000 to 7000 tons a year. As the war continued, shipments from the East, endangered by sea attack and blockade, dwindled rapidly. Imports from Brazil mounted. In this grave emergency, the United States, starting almost from scratch and under the stimulus of high prices, succeeded by 1918 in producing a peak of 311,000 tons, about 3 5 per cent of its consumption that year. Since the war, the United States has depended upon foreign sources for more than nine-tenths of its high-grade ore. During 1936, 1937 and 1938, imports for consumption averaged 736,000 tons a year. During the same period, domestic shipments averaged 21,000 tons a year. Of the imports, the U.S.S.R. accounted for an annual average of 280,000 tons, the Gold Coast 208,000 tons, India 74,000 tons, and Brazil 72,500 tons. But India and Brazil, which in 1936 ranked third and fourth in the list of importers, were displaced in 1937 and 1938 by a new and much nearer source-Cuba. From less than 1 per cent of United States imports in 1931, the island republic increased its shipments to more than 27 per cent in 1938. Cuba's average for this three-year period was 97,000 tons, and its total for 1938 was 131,000 tons.

Jan 1, 1940