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By Peter N. Calder, G. H. Blackwell

The development of an open pit slope monitoring system, from equipment selection and justification to complete computer data storage and analysts, Is described. Methods of overcoming the Limitations of the electronic transit/distance measuring device and survey system selected are discussed. Results of the monitoring program showed that blasting was a major cause of Instability, and, after much experimentation, suitable blast patterns for mine production and pit wall integrity were designed. The experiences gained with double benching 'and wall cleanup procedures are discussed . The monitoring program also indicated that water was a contributor to instability, and methods of dealing with water In a rock with a low storage coefficient and transmissibility are described. Because of the danger of falling rock, photogrammetric methods are used for joint mapping and analysis, this work being contracted out. Joint strengths are measured on-site using a portable shear tester. Finally, a discussion of a complex failure is given.

Jan 1, 1983

By P. R. Bradley

This paper gives a brief history of the mining and milling operations in the Juneau gold belt, and a general description of the geology of the district, followed by a suggestive discussion of the general problem of sampling gold ores and a detailed description of the mining methods used in the Alaska Juneau mine. The paper indicates that variations in assaying ore similar to that from the gold belt are unavoidable on account of the erratic distribution of the gold. A caving system that accepts dilution was adopted for the Alaska Juneau mine; the ore is sorted and the final mill feed has nearly twice the assay value of the ore trammed. THE property of the Alaska Juneau Gold Mining Co., covering the Juneau gold belt for over a mile in length, consists of 136 claims and 24 mill sites; these are near Juneau, Alaska, in what is known as the Harris mining district.

Jan 3, 1924

By O. K. Miniato, L. Massé, K. Nobe, J. S. Aronofsky, W. F. 213-000-000-016 Seyer

MUCH work has been done dealing with the effect of mechanical stress on electrode potential in an electrochemical system. The contradictory nature of the experimental results indicates the complexity of the problem although thermodynamic considerations show that a simple relationshir, should exist. In those systems where a gas was the electromotive active substance satisfactory agreement between theory and practice has been found. Des Coudres' found this to be so even when the active substance of the electrode, in this case mercury, was in the liquid state. In contrast, attempts to correlate theory and experiment for the solid state have met with a very limited success. The early workers in this field, Andrews,2 Walker and Dill3 used iron, certainly one of the most reactive of metals. Others have made use of less active metals such as copper and nickel. Recently Fryxell and Nachtrieb4 investigated the electrochemical behavior of gold and silver under both tensile and compressive stresses and concluded that it was doubtful whether true stress potentials could ever be measured. Much of the lack of success to measure the thermodynamic stress potential can be ascribed to the presence or formation of a complex film on the metal surface in contact with the electrolyte. Further, the theoretical stress potential is very small and therefore difficult to measure directly. Thus the calculated emf between a 24 B & S gage cold-drawn copper wire stressed with a weight of 1 kg and an unstressed portion of the same wire is only 2.60 X 10"7 volts. This is very small compared to that which can be produced by chemical reactions at the metal electrolyte interface which in turn can be so large as to mask completely the stress potential. Hence in this type of measurement all chemical side effects must be eliminated or reduced as much as possible. It was for this reason that the system copper-sodium chloride solution was selected for study. INSTRUMENTATION In the many preliminary experiments conducted, two major difficulties were encountered. The first was to measure the small electro-potentials to be expected and the second to obtain a suitable electrode surface. The conventional potentiometric method was found to be unsatisfactory for measuring the small emf expected. However, by using an L & N No. 2290 galvanometer having a resistance of 915 ohms consistent measurements were possible. The reference electrode was always the unstressed one made from the same sample of wire. The steady current flow was approximately 10-8 amp. Lewis and Randell5 have stated that for currents of the order of 10-8, if there is no sensible polarization, the measured emf may be taken as a reversible one. To check the galvanomenter readings an alternative method was devised to measure the potential difference between the wires. This involved a Liston-Falb d-c breaker amplifier model 10, an L & N k-2 potentiometer and a moving-coil galvanometer having a sensitivity greater than 0.1 µv (microvolt) per mm. To increase further the output voltage of the amplifier a d-c amplifier, model B. L.-932 was introduced into the circuit. This amplifier was in turn connected to a Brush recorder which had been calibrated previously by the test signals from the Liston-Falb instrument. These test voltages employed took into account the impedance of the input current. Unfortunately, this method had too low a sensitivity for measurement below 10 µv. Above this value the voltage agreed reasonably well with those obtained directly by the simple galvanometer method. The main advantage of the amplifier setup was that one did not have to wait until no deflection occurred on the galvanometer in the circuit when first exposing the wires to the solu-

Jan 1, 1959

By Thomas N. Walthier

ROSPECTING for uranium in the East is hampered by the lack of bedrock exposure due to extensive overburden and residual soil. But, despite the problems of this physiographic province, it has not been ignored in the search for radioactive materials. Since 1951 both the U.S. Geological Survey and the Atomic Energy Commission have had field parties in the eastern U.S. Tempo of private prospecting is increasing, and many discoveries have resulted. AEC work so far has been concentrated in the areas of most numerous discoveries-Pennsylvania, New Jersey, and New York. Accounts of uranium mineralization in the eastern U.S. are found in the old literature and one site in the Mauch Chunk area of Pennsylvania has been known since 1874. In 1949 McKeown examined the original occurrence there and found another southeast of the town. The deposit appeared to have commercial possibilities and a short period of production began in July 1954

Jun 1, 1955

By Frank C. Appleyard

Southwest of the town of Saltville in western Virginia is Plasterco, a small village that has been a source of gypsum production since 1815. Boasting the deepest underground gypsum mine in the world, Plasterco has been the site of mining operations by United States Gypsum Co. for more than half a century. And although its own ore supply is dwindling, Plasterco's position as a source of gypsum and gypsum products has been ensured by the recent opening of the nearby Locust Cove mine, one of U.S. Gypsum's newest projects. In the early days, production of gypsum at Plasterco was very small, the primary use of the mineral limited to that of "land plaster"-ground gypsum spread on the land to sweeten the soil. Initial mining was confined to surface outcrops containing gypsum, but the construction of a local plaster-producing calcining plant in the late 1800's coupled with al- most total depletion of the surface rock spurred the start-up of underground operations.

Jan 3, 1965

By A. J. Sedriks

ALTHOUGH the occurrence of a readily visible tarnish on the stress-corrosion fracture surfaces of titanium alloys tested in oxygenated nitrogen tetrox-ide solutions has been reported,' the possibility that the formation of this tarnish is a requirement for cracking to proceed does not appear to have been considered. It has been proposed that failure occurs in this system as a result of some electrochemical-mechanical process.2 However, recent studies3-6 of the stress-corrosion cracking of a brass in certain ammoniacal solutions, which also cause visible tarnishing, have led to the view that failure occurs by the repeated formation and fracture of a brittle surface film of cuprous oxide. The purpose of this note is to point out the similarities which exist between the tarnish which forms on a brass and that found on titanium alloys failed in nitrogen tetroxide, and to suggest, by analogy, that a similar tarnish-rupture mechanism may be operative in the latter case. The titanium alloy selected for the present study contained 5.2 pct Al, 2.5 pct Sn, 0.025 pct C, 0.16 pct Fe, 0.014 pct N, 0.012 pct H, 0.07 pct 0, and 0.002 pct Mn by weight. Vacuum-annealed alloy strips measuring 4 by 0.25 by 0.04 in. were used to prepare self-stressed test specimens. Each specimen was made from two strips by bending the end portions and spot welding them together to produce curved sections of uniform bending stress. (The exact details of preparing such specimens have been described by Lisagor el al.7) The curvature in the strips determines the ma-magnitude of the outer fiber stress, which in the present specimens was 100,000 psi (yield stress = 120,000 psi). The specimen surface in the spot-welded end regions was shot-peened to induce compressive stresses and thereby eliminate the possibility of stress-corrosion cracking in these regions. The test environment was nitrogen tetroxide, initially containing 99.5 pct N2O4, 0.1 pct H2O, and 0.08 pct C1, through which oxygen had been bubbled for 30 min. During testing the tetroxide was subject to an oxygen pressure of 250 psi. The duration of the test was 96 hr, and during this time stress-corrosion cracks propagated through some 50 pct of the thickness of the specimens. After testing, the tarnish was liberated from the fracture surface by immersion in a methanol-5 pct bromine solution, and then examined by electron dif- fraction and transmission electron microscopy using a JEM-7 electron microscope. The possibility that the bromine solution had affected the structure of the tarnish was investigated by an "in silu" examination of the stress-corrosion fracture surface using a reflection electron diffraction attachment designed for handling bulk specimens. Typical areas of the tarnish liberated by the me-thanol-bromine solution are shown in Fig. 1. Fig. l(a) reveals that the tarnish consists of individual platelets, and from Fig. l(b) it can be seen that the platelets are joined together to form a semicontinuous film, the boundaries of the titanium substrate grains being retained in the tarnish. Electron-diffraction patterns taken from these areas exhibited diffraction spots typical of a monocrystal. The diffraction pattern shown in Fig. 2 was taken from the central area in Fig. l(n). Monocrystal patterns obtained from areas containing numerous individual platelets can only be explained by assuming that their growth is governed by the titanium substrate (i.e., their growth is epitaxial). In other areas, the tarnish had folded over or became mechanically damaged, and these areas gave diffraction patterns consisting of "spotted" rings, enabling interplanar spacings of the tarnish lattice to be determined. These spacings, measured using a

Jan 1, 1968

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Jan 1, 1938

By H. LeChatelier, B. Bogitch

Page Introduction........................... 134 Methods of Investigation....................... 135 The Tridymite Network...................... 137 Independent Variables....................... 146 Manufacturing Operations..................... 153 Introduction Silica brick are indispensable in the manufacture of steel because they alone are able to withstand the high temperature of regenerative furnaces. All attempts to replace silica brick by other refractory materials for this purpose have failed, but the reason for this failure has remained obscure; we shall give an explanation later in this paper. Before the war, silica brick employed in France came principally from abroad, for which reason, since the beginning of hostilities, certain French steel works have been seriously handicapped. Our attention was first directed to the question by M. Bied, Engineer of the Teil Works. With him, we began certain investigations, at first using our laboratory and the furnaces of neighboring steel works. The larger part of our experiments, however, have been made in the laboratory of the Faculty of Sciences at the Sorbonne. For the heating of our samples, we are deeply obliged to MM. Charpy, Yeatmann and Guerineau. In undertaking these studies, our first aim has been to render assistance to French industry, by indicating, as precisely as possible, the necessary conditions for the manufacture of high-grade brick; but at the same time me have

Jan 1, 1919

By H. Hubert

The first attempts at direct utilization of blast-furnace gas in engines were made in 1895. For a considerable time the gas had been burnt in Cowper stoves for heating the blast for the furnace, and under the boilers which supplied steam to the blowing-engines, and others serving the furnaces. It was natural, therefore, that the idea of directly employing it in gas-engines should have occurred simultaneously to several engineers, notably to Lurmann and to Lencauchez, who had pointed out the blast-furnace as a powerful gas-producer. Nevertheless, nowhere had any attempt been made to apply it to this purpose up to the end of 1894, when Thwaite proposed it to Mr. James Riley, of the Glasgom Iron & Steel Company. About the same time investigations were being made in Belgium and in Germany, independently of Thwaite's experiments, which were not generally known on the Continent. The industrial world, which up to that time had hardly favored the idea, had thus been gradually prepared to receive it. The gas-engine, long restricted to small sizes and dependent upon the use of an expensive fuel obtainable only in large centers, now began to make headway. At the Paris Exhibition of 1889 two engines of 100 h.p. were shown and excited much interest among engineers. One had four cylinders, and was made at the celebrated works of the Deutz Company, and the other was a single-cylinder engine, exhibited by two French designers, Messrs. Delamare-Deboutteville and Malandin. In the meanwhile the design of gas-producers had made important progress, completely freeing the new engine from its

Jan 1, 1907

By J. E. Johnson

At the Cleveland meeting of the Institute in October, 1912, I had the honor to present a paper outlining the conditions surrounding the charcoal iron industry…

Jan 1, 1915

Jan 1, 1919

Jan 1, 1954

Jan 1, 1936

By Charles P. Williams

THE successful production of zinc white or oxide on a commercial scale in this country dates from the issue of the patent of Samuel Wetherill, for the preparation of the material (November, 1855), and

Jan 1, 1877

Jan 1, 1915

By Francis Lucas

EACH year we gather in this auditorium to honor the memory of a . distinguished American metallurgist and educator. I cannot bring to you reminiscences of Prof. Henry Marion Howe as other lecturers have done. It was not my good fortune to enjoy the privilege of studying and ,working under his direction. As I have reflected on the published works of Professor Howe, it has seemed to me that his mind was trained on the nature of metals and on the mechanism which produced known but unexplained effects. He was interested in controlling and regulating the causes so as to produce specific effects, useful in serving mankind. I recall an afternoon in May, 1925, when, at the invitation of Mrs. Howe, I visited his former home, Green Peace at Bedford Hills, N. Y. The purpose of my visit was to receive at the hands of the widow -an engraving of Professor Howe, a reproduction of a painting from life. Mrs. Howe showed me his study. The walls of this large attractive room, brilliantly illuminated by the spring sunshine, were literally covered with the scrolls of honors and of decorations which had been conferred on Professor Howe by governments, academies, universities, societies and. institutions the world over. As we walked about the room, she pointed out the significance of each honor and recited a few details of each occasion. I sensed the pride with which Mrs. Howe, then in the late autumn of her life, told me of her husbands' achievements, of his struggles, of his disappointments and of his successes. There was a surprisingly familiar note in the recital to which I was listening. I have found the same theme running as a disconnected thread through the written accounts of the lives of most men of science. We then went to the drawing room to chat for a few minutes before I said my farewells. As we seated ourselves, Mrs. Howe turned to me and asked: "Mr. Lucas, what of this great microscope of yours? Cannot it be applied to the study of disease? What a great blessing it would be if it could be directed to relieve the suffering of mankind."

Jan 1, 1931

Jan 1, 1888

New Products Equipment

Jan 6, 1953

By William J. Robinson

What is the cummulative rate of recovery of copper from a sulfide leach dump? The technical answers to this frequently asked question may vary from "I don't know" to "quite good" from people of the same company. Management also poses this question because it plays a vital role in planning future production. The answer is difficult because of the many variables between different operations such as physical construction of the dump, topography of the original site, characteristics of dump material, mineralization and water application. Each of these factors and others have a bearing on the rate of recovery. Anaconda's method of water distribution at Butte is unique in that each dump is drilled to allow physical injection of water into the dump. The injection holes are drilled vertically on 25 ft centers from the surface of the dump. Normally, the holes are drilled 40 ft deep and cased with 4-in. PVC perforated pipe. The pipe is perforated at one-foot intervals with four 1/2 in. diam holes at 90" spacing on the pipe circumference.

Jan 9, 1972

By Paul L. Hunter

Nearly 2000 people are employed at Kennecott's Chino Mines Division, which recently completed its 50th year as a leading copper producer. Chino operates an open pit mine at Santa Rita, N.M., and a reduction plant, including mill, power plant, and smelter, at Hurley, N.M. The property mines 66,000 tons of copper ore and materials per day. There have been safety and industrial health programs at Chino for a number of years, but in 1955 these procedures were reorganized on a more active basis. The following discussion evaluates the progress made during the 1955-1958 period.

Jan 6, 1960