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By Thomas M. Barczak

The resultant load vector is the representation of the forces applied to a longwall roof support element by caving strata into a single, quantifiable measure of support resistance. The relatively complex kinematics of the shield support prohibit a determination of support resistance simply by summation of leg forces. A method is being investigated by the Bureau of Mines to determine the resultant load vector by instrumenting supports with pressure transducers and strain gages to measure leg, canopy capsule, and lemniscate link forces. This concept has been laboratory tested in the Bureau's Mine Roof Simulator. Functional relationships among variables have been assessed, and confidence intervals have been established for prediction of the resultant load vector parameters.

Jan 1, 1984

The Howe Memorial Lecture, in memory of Henry Marion Howe, Past President of the Institute, was authorized in April, 1923, as an annual address to be delivered by invitation under the auspices of the Institute by an individual of recognized and outstanding attainment in the science and practice of iron and steel metallurgy or metallography, chosen by the Board of Directors upon recommendation of the Iron and Steel Division. The following were the Howe lectures and lecturers for the years indicated 1924 What is Steel? By Albert Sauveur. 1925 Austenite and Austenitic Steels. By John A. Mathews. 1926 Twenty-five Years of Metallography. By William Campbell. 1927 Alloy Steels. By Bradley Stoughton. 1928 Significance of the Simple Steel Analysis. By Harry D. Hibbard. 1929 Studies of Hadfield's Manganese Steel with the High-power Microscope. By John Howe Hall. 1930 The Future of the American Iron and Steel Industry. By Zay Jeffries. 1931 On the Art of Metallography. By Francis F. Lucas.

Jan 1, 1923

By K. J. Anusavice, R. T. DeHoff, H. Oikawa, J. J. Pinajian

STUDIES of nickel self-diffusion and impurity diffusion in pure metals and alloys have, for the past two decades, employed predominantly the nickel radio-However, because of the low energy of the emitted particle, careful and time-consuming techniques must be used to obtain reproducible measurements. In our studies of nickel diffusion into copper, we have recently used Ni66 [Td1/2: 55 hr; : 0.20 Mev (100 pet)] which decays to it much more suitable as a tracer because of the presence of the high-energy y radiation from the cu66 daughter. Although the half-life of Ni66 is appreciably shorter than that of Ni63, the useful working lifetime of a small quantity, " 10 mc, is about 1 month. preparation bf Ni66. he Nis6 radioisotope was produced at Oak Ridge National Laboratory by means of a double (n,y) reaction:

Jan 1, 1969

By R. L. Tobie

Handling and storing ore at transfer points underground are encountered frequently. An ideal solution to these troubles is probably still to be found, but at the Mather mine "B" shaft a method incorporating scraping trenches has been developed giving better service, from the standpoint of safety and simplicity, than obtained from other schemes. When shaft pockets are used for storage, the size of the ground opening required to assure capacity is often prohibitive, and shaft depth below the last level can become excessive, particularly if a crushing station is used. Also, if the material being handled contains large amounts of wet fines, it is difficult, if not impossible, to hold the material with regular chute gates. In order to remedy these problems Cleveland-Cliffs' Mather "B" has utilized three types of trenches. Types I and I1 are now in service and the third is under construction.

Jan 4, 1955

By John D. Weibmer

A remarkably simple construction system that derives its internal stability from metal straps buried in backfill is finding diverse mine applications, ranging from rock crusher headwalls to massive slot coal storage facilities. Reinforced Earth (Re/Earth), the system trade name of Reinforced Earth Co., is proving itself 20-50% less expensive than alternative earth embankment structures, and in the case of cast-in-place concrete walls, six to seven times faster to erect. While the majority of applications are in the realm of civil engineering-projects such as retaining walls, bridge abutments, slide buttresses, and containment dikes-a growing proportion is mine related. Of the estimated 120 Reinforced Earth projects that will be completed this year, company president David P. McKittrick expects mining to account for about 20% of the business volume.

Jan 8, 1978

By Michael Richings

Although the role of slope stability has not changed, there have been changes in the mining industry which affect the geotechnician engaged in slope stability studies. The deposits currently being mined or evaluated are technically difficult , capital intensive, and economically marginal. In addition, many mining companies are now either controlled by oil companies or are financing projects through bank loans. The mining investor or decision maker is, therefore, often more sophisticated financially, but less sophisticated in mining terms. The impact of these changes will be to force the geo- technician and mining engineer to attempt to quantify risk and financial implications of a slope design. In conclusion, this paper outlines several questions which mining engineers should be asking those engaged in geotechnical studies and indicates the necessity for the mining engineer and geotechnician to work together and quantify the financial risk associated with a geotechnical design.

Jan 1, 1983

By H. E. Howe, A. A. Smith

E. Schumacher.*—Mr. Smith has shown us once again how variable lead alloys can be. I have studied lead alloys for a good many years and know from experience that their behavior cannot be predicted by analogy with other alloys. I have always been interested in observing how the creep resistance of lead may be improved by the addition of as little as 0.03 per cent Ca. Without the presence of calcium the grains of extruded lead pipe are fairly equiaxed and motion can take place easily at the boundaries. The calcium addition of 0.03 per cent causes the grain boundaries to become very irregular and jagged, and results in creep resistance many times greater than that of pure lead. Mr. Smith showed that in the one per cent antimony-lead alloy creep is occasionally excessive even where low stresses are involved. We have observed this phenomenon many

Jan 1, 1945

By B. G. D. Smart

An understanding of the nature of yield zones surrounding coal mine excavations is fundamental to the design of mine support systems. Various methods have been designed for investigation of underground rock masses and an extensometric technique, the Magnetic Rod Extensometer, has been developed to overcome inherent design limitations in existing equipment of this type. This paper refers to the prototype form of the extensometer and details changes designed to overcome a variety of drawbacks indicated by routine use of the equipment. The principal change has been one of manual to computerised data acquisition and presentation in the laboratory phase of the system. This has dramatically reduced the time taken to process underground measurements and produce numerical and graphical results. The revised Magnetic Rod Extensometer represents an integrated instrumentation system that combines speed and accuracy in all areas of data handling.

Jan 1, 1984

By Antonio Marrano, Eda F. Quadros, Diogo Correa [Fo], Paulo T. Cruz

For many years the water pressure test has been used as a normal procedure to investigate the hydraulic characteristics of rock masses and discontinuities. Although the test has given evidence of problematic areas, the nature of flow and the so called equivalent permeability are seldom seriously affected by the testing tecnique. In order to improve the information on these points the Instituto de Pesquisas Tecnológicas de São Paulo - IPT, has developed an extensive program at laboratory and field research on the hydraulics at rock fractures. This paper summarizes the main items related to this research. Is shows that with only small improvements on field tests and some support of laboratory conductivity tests on natural rock joints it is possible to obtain a better understanding of the nature of flow in fractures, improve flow predictions and estimate the opening and hydraulic conductivity, as well as the transmissivity of natural joints or rock discontinuities.

Jan 1, 1982

By R. S. Shrode, R. F. Bunting

Transportation is one of several important increments in the total market cost of most commodities. On a national average it has been reported that transportation accounts for about 25% of the total cost of a product at the market place. And industrial minerals are no exception. In fact, the proportionate cost frequently exceeds the 25% average. Further, it may actually determine the economic value of a deposit. Transportation possibly may be thought of as a specialized subject, of concern only to a traffic manager and of only nominal interest to the mining engineer, the geologist or other technically oriented member of a mineral producers' staff. However, in the industrial minerals field, interest is not commonly confined to exploration, development, production or marketing, but is in contrast an overlapping one. In a very real sense this broad area of interest in the total economics of the business is the specialty of the industrial minerals man. And transportation is a vital part of the total picture.

Jan 1, 1970

By R. W. Smith

A study has been made of the crushing and grinding circuits by the Portland Cement Association in nine cement plants. Five of the plants used the wet process and four, the dry method. Both raw and clinker grinding were studied in the four dry processing plants. The raw materials used varied considerably from plant to plant. Actual power consumption data were obtained for the majority of the grinding mills in these plants. Previously representative raw and clinker samples had been obtained from the nine plants, and Bond1 and Hardgrove2 grindability tests were run on these samples. All pertinent data concerning the grinding mills, such as mill size and speed, ball charge size and weight, size distribution of feed, and discharge materials were also obtained. Thus it became possible to calculate the actual horsepower used by the various mills, and to compare this figure to the theoretical horsepower as calculated by several different methods.

Jan 4, 1961

(Under this heading will be published notes sent to the Secretary of the Institute of members or other persons introduced by members) Young mining engineer, and geologist, member, technical, graduate with four years' varied mining experience in the West and Southwest as miner, surveyor and engineer. Past 18 months, work in mine geology, mapping and examinations. Would prefer assisting consulting engineer or work with exploration company in foreign service. Unmarried. Age, 28. No. 331. Member; aged 35, married, with 10 years' experience in the Southwest, thoroughly competent to take full charge of mining and milling operations. Particularly fitted to handle either gold or tungsten producers. At liberty February 1. Will go anywhere. No. 340. A member wants a roving commission to examine old mines of the Mother Lode in. California, especially those which can be bought for their taxes. Some of these mines are reported to contain large quantities of low-grade ores which can now be treated at a profit. No. 341.

Jan 2, 1917

By B. Wilshire, W. J. Evans

The high-temperature creep properties of nickel, zinc, and iron have been determined over a range of stresses. The creep strain, E, was found to vary with time, t, as: where e0 is the instantaneous strain on loading, ET the total transient creep strain, $ the steady creep rate, and m is a constant relating to the rate of exhaustion of transient creep. Deviations from this relationship occurred during the initial 10 to 15 pct of the transient stage. These deviations result in the initial creep rate, go, calculated as (m . ET + es), being considerably lower than those obtained by measurements on the creep curve. For all materials, the initial creep rate, the constant m, and the duration of transient creep are all related to the steady creep rate. These relationships suggest that transient and steady-state creep should not be regarded as distinct stages.

Jan 1, 1969

G. SHERBURNE ROGERS,* Washington, D. C. (written discussion ?).- Mr. Neal's paper on the petroleum hydrology of the Mid-Continent district is a welcome contribution on a subject concerning which none too much is known; it is, I think, the first published description of the chemical character of the oil-field waters of the great Mid-Continent area. When studying the oil-field waters of the California fields several years ago, the differences in chemical composition between waters occurring at various horizons seemed to be sufficient to enable the operators to use water analyses as a basis for determining the source of the water flooding a well; and it is gratifying to find that, Mr. Neal has arrived at a similar conclusion. As Mr. Neal points out, the Mid-Continent waters are very different in character from those of the California fields, and casual. inspection

Jan 3, 1919

Thirteen Directors, the Secretary, and seven guests were present. The formation of a Philadelphia. Section was discussed. The proposed rules for admission of additional societies to membership in Engineering Council were approved. An invitation was extended to the American Institute of Metals to become affiliated with the Institute upon the general terms proposed in the report of the Joint Conference Committee of the American Institute of Metals and the American Institute of Mining Engineers. The request of the Iron and. Steel Committee to hold a meeting in Milwaukee during the week of Oct. 7, 1918, was granted. The reports of the Treasurer and Finance Committee were accepted. A change in the By-laws was proposed. Thirty Members, two Associates, and four Junior Members were elected. The status of two Junior Members was changed to Member. The resignations of seven members were accepted. The clues of two members who are on active duty at the front were remitted. One member was reinstated to membership.

Jan 5, 1918

ON presenting the medalist, J.. V. W. Reynders said, in part: "Far the greatest progress in the art of steel-nuking has occurred in the production of lighter forms such as tool steels and steels entering into the moving parts of machinery generally, and particularly into the con-struction of automobiles and airplanes. In this highly specialized field in which the study of alloys and heat treatment has brought about such fundamental changes of design and practice, Dr. Mathews has achieved a ranking position. "As the technical head of the largest producer of special steels, his laboratory conclusions are frequently but a few steps removed from practical exploitation. The experimental determinations of yesterday must be sufficiently conclusive to form the basis for the specific plans of today, and to warrant commercial production tomorrow. His is not the complacent atmosphere of theoretical speculation, but one in which practice fol-lows close upon the heels of scientific research.

Jan 3, 1928

The University of Illinois, by Prof. H. H. Stock, professor of mining engineering, sent out to its mining students a long letter urging them to attend a Chicago meeting of the Institute. It stated that the University Council authorized the remission of the registration fee for sophomore, junior and senior mining engineers who would attend the meetings and present a written account of the sessions and excursions attended. Young engineers are rarely flushed at the beginning of their careers but if they ever expect to amount to anything at the end of 10-years-they are going to regret that they have not long been a member of the Insti-tute. So that the slogan "Do it now" is snore than particularly appli-cable in their cases and nothing will better indicate to them the scope of the Institute's work and the advantages which they are to get from mem-bership than attendance at one of the big meetings of the Institute and the preparation of a written report on the sessions and excursions attended to be returned to the University.

Jan 11, 1919

By M. A. Hunter

CHAIRMAN M. A. HUNTER. UP to this time our stress-corrosion sessions have been concerned with stress-corrosion cracking in brass. In the succeeding sessions a variety of other products which are susceptible to stress-corrosion cracking are to be considered and this afternoon's session is to be devoted to stress-corrosion cracking in light metals. The problems you have had to deal with up to now in brass have been very simple ones. From this time on the complexities become greater. You have already learned in the preceding sessions, that copper is not susceptible to stress-corrosion cracking and when you begin to alloy it with 3 per cent or larger proportions of zinc, then stress- corrosion cracking ensues. You apparently have few complications in the copper alloys you make. There is apparently no precipitation on the grain boundaries in the brass, and no precipitation within the metal itself. So, on the whole, the problem is a simple one. Yet it has been with the brass people for a very long time and it is apparently not yet settled from the fact

Jan 1, 1945

By Robert H. Richards

In the latter part of December a batch of amalgam was retorted and the tin in the retort uncovered while at a low red heat, and allowed to cool slowly to a temperature more suitable for ladling into moulds. It was then ladled and made what appeared to be nice, white, malleable block tin. On February 15th our attention is called to the fact that the tin is brittle, and on examination we find that the molecular condition of the pigs has changed to the extent of one-half its material. The change shows itself by an enlargement appearing on the surface something like crystallization, and comes in spots. The condition of the metal in these spots is very peculiar. It has changed from a malleable metal to a brittle one, with a structure somewhat resembling stibnite, and a color very considerably darker gray than tin. The analyses of the two parts of this tin pig showed the following results: Mercury. Tin. Specific Gravity. Crystalline part,.....2.62 97.24 6.175 Malleable part,.....2.38 97.50 7.387

Jan 1, 1883

By Cyril Stanley Smith

BETA brass (consisting of approximately equal atomic proportions of copper and zinc) exists as a random solid solution at high temperatures, but at low temperatures [ ] an ordered structure is stable, with the copper and zinc atoms occupying alternate sites on the body-centered-cubic lattice. On cooling, ordering commences at a temperature of 450° to 490°C., depending on the composition. The degree of ordering progressively increases at lower temperatures until it becomes virtually complete at about 100°C. The electrical resistivity of the alloy illustrates the changes clearly (Fig. I). This type of reaction has been a favored subject for study by physicists. An [ ] excellent summary of the theory is to be found in a paper by F. C. Nix and W. Shockley.1 All published data on electrical conductivity, specific heat and other properties agree in indicating that the ordering reaction in beta brass takes place so rapidly that it cannot be prevented or even retarded by quenching. With most ordered alloys, cold-working induces disorder and

Jan 1, 1942