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By A. J. Lyon

The stability and permanence of any structural material used in aircraft are of paramount importance. The spontaneous hardening, or age-hardening, which takes place in some of the aluminum alloys under ordinary conditions of temperature and atmosphere, is accompanied by an increase in tensile strength and proportional limit and a decrease in elongation or ductility. Within the last few years the introduction of a number of strong and ductile casting alloys led to a study by the Materiel Division, Air Corps, of the permanence of the physical properties in several of these alloys. It has been found that even though some alloys have good properties directly after casting or heat treatment, they are not satisfactory for stressed parts that require a combination of strength and ductility. It has also led to the conclusion that all alloys that can be hardened by artificial aging—heating in a temperature range below 170" C. (340" F.)—will harden spontaneously if allowed to stand for a sufficient length of time. It follows that, in aircraft work where the factors of safety are limited on account of the necessity of keeping the weight of the structures as low as possible consistent with their safe operation, the properties of the alloys in the stable or final condition should be used as a basis for design rather than the properties obtained on the material directly after casting. The work of Wilm in Germany, Hanson and Gayler at the National Physical Laboratory in England, and Merica, Jeffries, and others in the United States, has shown that the spontaneous hardening is characteristic to a greater or less extent in all aluminum-base alloys in which the solubility in the solid state of the alloying constituents decreases with the temperature. It has been shown that, by heating to a temperature as near as possible to the melting point of the material and soaking at that temperature for a sufficient length of time and then quenching or cooling rapidly, a maximum amount of the soluble constituents can be retained in solution and the condition of maximum hardening effect upon aging can be obtained. Also, in ordinary sand and chill castings, without heat treatment, a sufficient amount of the alloying constituents is held in solution to cause important changes in the final physical properties.

Jan 1, 1929

By A. J. Lyon

The stability and permanence of any structural material used in aircraft are of paramount importance. The spontaneous hardening, or age-hardening, which takes place in some of the aluminum alloys under ordinary conditions of temperature and atmosphere, is accompanied by an increase in tensile strength and proportional limit and a decrease in elongation or ductility. Within the last few years the introduction of a number of strong and ductile casting alloys led to a study by the Materiel Division, Air Corps, of the permanence of the physical properties in several of these alloys. It has been found that even though some alloys have good properties directly after casting or heat treatment, they are not satisfactory for stressed parts that require a combination of strength and ductility. It has also led to the conclusion that all alloys that can be hardened by artificial aging—heating in a temperature range below 170" C. (340" F.)—will harden spontaneously if allowed to stand for a sufficient length of time. It follows that, in aircraft work where the factors of safety are limited on account of the necessity of keeping the weight of the structures as low as possible consistent with their safe operation, the properties of the alloys in the stable or final condition should be used as a basis for design rather than the properties obtained on the material directly after casting. The work of Wilm in Germany, Hanson and Gayler at the National Physical Laboratory in England, and Merica, Jeffries, and others in the United States, has shown that the spontaneous hardening is characteristic to a greater or less extent in all aluminum-base alloys in which the solubility in the solid state of the alloying constituents decreases with the temperature. It has been shown that, by heating to a temperature as near as possible to the melting point of the material and soaking at that temperature for a sufficient length of time and then quenching or cooling rapidly, a maximum amount of the soluble constituents can be retained in solution and the condition of maximum hardening effect upon aging can be obtained. Also, in ordinary sand and chill castings, without heat treatment, a sufficient amount of the alloying constituents is held in solution to cause important changes in the final physical properties.

Jan 1, 1929

By M. I. Brasileiro

The use of experimental design to the study of mixtures has found a wide range of applications, even in laboratory scale or in industrial development works. The aim of this work was to maximize granite sawing waste content in ceramic tiles using experimental design. Based on the raw materials, specific formulations were developed using the experimental design. The raw materials were mixed and sample bodies were produced using uniaxial pressing. The sample bodies were fired and characterized in terms of water absorption, mechanical strength and X-ray diffraction. Regression models were adjusted relating the water absorption and mechanical strength with the amount of raw materials. The results showed that the methodology of experimental design maximize the content of wastes incorporated in ceramic tiles formulations. Formulations containing up to 40% of waste can be used for the production of ceramic tiles.

Jan 1, 2009

By Gerd L. Klinkenborg

Throughout the history of the development of mechanical conveyor systems, it has always been an established condition that loads are received at one end of a single-belt conveyor and discharged at the other end, in a point-to-point, manner. In systems designed for the continuous transport of granular materials, vertical or horizontal changes in; direction have always necessitated two or mope single-belt conveyor units, with a corresponding number of motors, assemblies and attendant mechanical and human or electronic controls. Besides these high-cost factors, every change in the system's direction also calls for a transfer point that involves a drop-back of the material from one level to another with some loss of the material and, in many cases, unwanted additional granulation. Where changes in the location of the discharge point are wanted, the conventional single-belt conveyor must either be replaced by a shorter or longer unit or additional units purchased and installed, or existing units rearranged. This can take days or weeks, and involve special expenditures as well as loss of valuable production time.

Jan 1, 1962

Howard N. Eavenson, Gary, W. Va. (communication to the Secretary*):—For some time before the publication of Mr. Scholz's paper, I had been collecting data bearing upon its subject, and I now take pleasure in presenting to the Institute my results in the form of a discussion. It has long been a matter of common opinion among mining-men that mine-explosions are more frequent during the colder, or winter months, than during the warmer ones, and it is a matter of common knowledge among them that the air-ways and road-ways in most mines are much drier and are more inclined to be dusty during the winter than during the summer. In many mines, places which are wet and sloppy in the summer are dry and sometimes dusty during the winter. These changes, of course, can only be due to atmospheric conditions, and are caused by differences in temperature and humidity. Until recently, however, very little attention has been paid to the part that atmospheric conditions may play in mine-explosions, or, rather, to the effect they may have in rendering mine-conditions peculiarly dangerous, and in spreading and rendering more disastrous the effects of what otherwise probably would have been small explosions. To show the difference in mine-conditions during summer and winter months, I have tabulated in Table I. the results of 24 observations of hygrometric conditions in several different mines at different times of the year. Mines Nos. 1, 2, and 6 are located in the Pocahontas coal-region, in McDowell county,w.Va., the first one being a shaft-mine and the others drift. Mines 1A and 2A are drift-mines located in Logan county, W. Va. All of these are mines of fair size, but none of them has been in operation more than six years,

Jan 1, 1910

By Kathleen M. Kowalski-Trako?er

National Institute for Occupational Safety and Health re­searchers conducted a study to investigate the human response issues related to wearing a self-contained self-rescuer (SCSR). The goal was to develop training to educate miners on what they could expect from their units during an escape. Subjects included miners who had experience wearing SCSRs, manu­facturers, and researchers. Results identified nine key areas of concern: (1) starting the unit, (2) unit heat, (3) induction of coughing, (4) unit taste, (5) difficulty in breathing while wearing the unit, (6) quality of the air supplied, (7) nose clips, (8) goggles, and (9) the behavior of the breathing bag. In addition, researchers reviewed the literature on human response under duress. This article describes the expectations training program, which comprises the findings of the SCSR study and what is known about the normal human response in an emergency. The authors present background on SCSRs and the SCSR switchover procedure mandated in the recent federal Mine Improvement and New Emergency Response Act of 2006, which provided the impetus for the expectations training. Keywords disaster, escape, mining, self-contained self-rescuer, training

Jan 1, 2008

By Jennifer Riefenberg

A family of personal computer programs that calculate the Coal Mine Roof Rating (CMRR) has been developed by the U.S. Bureau of Mines. The CMRR rock mass classification system provides a link between the qualitative geologists' description of coal mine roof and the quantitive mine engineers' needs for mine design roof support selection, and hazard detection. The program CMRR is a user-friendly, interactive program into which raw field data are input. A CMRR is calculated and output along with two graphic displays. The first graphic display is a plan view trap with the CMRR's displayed on a color-coded scale. The second display shows a stratigraphic section of the bolted roof interval and its resultant CMRR. In addition, a Lotus 1-2-3 worksheet, computer file BOM-CMRR.WK3, has been developed for easy storage of field data. The worksheet includes four macros that automatically calculate CMRR's, store field test data in a database format, and print a two-page report of the field data and CMRR parameters. Production of summary port; for analysis of site-specific information are readily generated using Lotus 1-2-3 software. These programs help to facilitate the engineer in utilizing the CMRR in ground control studies.

Jan 1, 1994

By E. G. Davis

A research program to evaluate the use of ceramic die inserts for ferrous diecasting was initiated by the Bureau of Mines at its Tuscaloosa Research Center. Data were compiled from the literature to characterize selected ceramic materials with respect to thermal properties, thermal-shock resistance factors, chemical reactions with molten metals, and processes required to form die components. With this information and a computer model developed for predicting temperature and stress patterns induced in ceramic materials during simulated ferrous diecasting operations, 27 candidate materials were evaluated. After evaluation, only 15 were considered for testing in an apparatus constructed to immerse the ceramic specimens in molten cast iron. Of these, 13 were tested in a modified testing unit in which cast iron was poured onto the specimens. These tests resulted in the selection of three materials for further testing: boron carbonitride (50 pct B4C:5O pct BN), boron nitride-grade M (BN-M, 40 pct BN, 60 pct Si02), and pyrolytic boron nitride (PBN). Tests in a gravity-flow die unit showed that PBN was thermal-shock resistant and could be used in diecasting of ferrous metals.

Jan 1, 1981

By Donald F. Reed

Deposits of gray hematite occur in two districts in Talladega County, Ala., the Emauhee-Tallasechatch and Weewoka, both in the; vicinity of Wintorboro, 50 miles east of Birmingham. The deposits were investigated by the Bureau of Mines in 1945 and 1944. Approximately 15,000 feet of diamond drilling was done and 6,000 linear feet of trenches excavated and sampled.

Jan 1, 1949

By Russell W. Mumford

LITHIA compounds have a place in pharmaceutical and other chemical industries and lithium minerals in glassmaking and ceramics. The metal, although rare, is used to a minor extent in alloys. During the nearly 50 years of production of lithium minerals in the United States, the silicate mineral spodumene has continued as the chief source of raw material for the manufacture of lithium salts. Although twice as much lepidolite, a lithium mica, has been mined, most of it has been used in the making of certain types of glass. Amblygonite has been an additional but minor source of lithium compounds. Triphylite, petalite, and zinnwaldite have also been utilized in the past. All of these commercial lithium minerals contain low percentages of lithium (Table 1). In 1938, a new raw material for manufacture of lithium compounds made its appearance. This product was crude dilithium sodium phosphate (Li2NaPO4), obtained as a by-product of manufacture of potash and soda chemicals from the brine of Searles Lake, California. Searles Lake, which is now dry, lies in the extreme northwest corner of San Bernardino County, California, and consists of a large mass of salts. It was estimated by the United States Geological Survey that the crystal body contained about 25 pct voids, which are filled with a saturated brine. The brine consists mainly of the sulphates, chlorides, carbonates, and borates of sodium and potassium. Several other acid radicals, including phosphates, are present. Lithium is present in the brine in an amount corresponding to 0.01 15 pct Li2O. In the course of evaporation of water from the brine, during the process of manufacture of sodium and potassium chemicals, dilithium sodium phosphate crystallizes out and is recovered by a flotation operation. The lithium concentrate is filtered and dried and is then ready for shipment. It analyzes from 19 to 21 pct Li2O and now constitutes the highest known grade of crude lithium material. It is and will continue to be a major source of lithium for manufacture of lithium products. The variation in lithia content of the commercial minerals as mined is due to replacement of the lithia by soda and potash, to partial alter-

Jan 1, 1949

By Alicia Esther Ares

This study was conducted to investigate the directional solidification of Zn-20%A1 and Zn20% A1-1O%Si-3o/oCu alloys under different conditions of heat transfer at the metal/mould interface. The type of structure obtained in both cases was analyzed and related to the solidification thermal parameters such as cooling rate, growth rate, thermal gradient and recalescence which were determined from the temperature versus time curves. These parameters were correlated with the structure-like length of columnar grains and size of equiaxed grains. The metallographic analyses were done performing quantitative metallography and composition analysis of the different alloying elements along the cast samples by SEM (Scanning Electron Microscopy) and EDXA (Energy Dispersive X-Ray Analysis). Correlations between properties, structures and thermal parameters were found.

Jan 1, 2008

By M. B. Cooke

In the course of investigation now in progress by the Bureau of Mines into the nature of " gum forming" constituents of gasoline , several gasolines and other petroleum products were heated in a small bomb , and pressures of considerable magnitude were developed . As the Bureau has received many inquiries for data showing the pressure that may be developed in a still when gasoline or other oil is subjected to elevated temperatures , it was thought advisable to record the pressures observed at various temperatures in the course of this work . data were merely a by- product of the main investigation . These Gasoline and similar products are very complex mixtures , and it is difficult to determine accurately the true vapor pressures , hence the vapor pressures of the oils used in these tests have not been studied in detail , but the data obtained may be taken as representative of the pressure- temperature relations of the various oils in commercial work.

Jun 1, 1922

By Satu Jyrkönen

A single-particle laminar-flow technique was used to study reactions of sulfidic nickel particles. The studied materials were three natural nickel concentrates and four synthesised nickel mattes. The variables of the experiments were the gas preheating temperature (500 - 1300°C), the composition of the reaction gas (N2 + 0 - 75 vol-% 02) and the ,particle size of the feed. Chemical analysis of the particles was used to determine the oxidation degree of the materials, and optical and scanning electron microscopy were used to detect alteration in their morphology, internal composition and structure. General reactivity of the materials was monitored by the extent of sulfur removal. The reaction mechanism of the studied materials was found to depend primarily on the materials composition as well as oxygen content of the reaction gas.

Jan 1, 1998

By D. M. Conner

An innovative patented process has been developed to convert high volume wastes--fly ash from coal-fired power plants, municipal solid waste (MSW) ash from incineration, solids from waste water treatment and paper mill sludge into a high value and environmentally benign product in the form of a lightweight aggregate. Lightweight Aggregate is widely used in the building construction industry in the United States, Europe and some Asian countries. This paper will present the development of the process, the process itself and details on the first commercial scale plant. The commercial plant is owned and operated by Wisconsin Electric Power (WEPCO).

Jan 1, 1997

By R. T. Jones

Keywords: Pyrometallurgy, DC arc furnace, myths, history, hollow electrode, radiation, resistance, flicker, AC DC arc furnaces are widely used for steel scrap melting as well as for reductive smelting of ore fines. Industrial smelting applications include the smelting of chromite to produce ferrochromium, the smelting of ilmenite to produce titania slag and pig iron, and the recovery of cobalt from non-ferrous smelter slags. A number of myths and misconceptions are widely held, especially regarding: the age of the technology, the use of a hollow electrode, arc stability and shape, arc and bath radiation, interaction between the arc and molten slag, electrical behaviour of arcs and slags, a comparison between AC and DC furnaces, DC reactors, the lifespan of bottom electrodes, and the applicability of DC arc furnaces to various metallurgical systems.

Jan 1, 2011

By Martin A. Moyers

THE nation's effort to win the war speedily is reflected in current trends in coal utilization, as in all other fields of our lives. In all industries, wherever coal is used for the production of heat and power the emphasis is on getting the most useful result with the least expenditure of matt.ria1. In addition to carrying its own share of the load, increased as it is by the demands of war industry, coal has had to fill in for the other fuels, mainly petroleum products, whose distribution from their more distant sources has been crippled by lack of shipping. Thus, the outstanding note in the utilization of coal this year is not the development of new methods of burning or handling coal but the extraordinary job that the industry has done in producing enough coal to serve all needs.

Jan 1, 1943

By ERIK C. WESTMAN, JESSICA M. WEMPEN, DALLAN J. COONS, WILLIAM G. PARISEAU, MICHAEL K. MCCARTER

Safe, efficient underground mining is dependent upon proper pillar sizing. Pillar sizing is typically based on a combination of observation of prior behavior, point measurements, theory and numerical modeling. The actual stress redistribution within a pillar, while assumed for many years, has rarely been imaged. Such imaging can help confirm whether or not theoretical and numerical modeling methods agree with actual conditions within a pillar. This research presents a case study from a longwall mine in the western United States. A two-entry, gate-road yield pillar in the headgate of the mine was instrumented with seismometers and convergence monitoring stations, and was monitored over a period of about six months as the longwall face approached the pillar. In this paper, the stress distribution imaged using seismic tomography is compared to the stress distribution expected from theoretical models, geotechnical measurements and numerical models. The tomography results generally agree with those proposed by theory, convergence measurements and numerical modeling results. The agreement of the methods provides validation for the theorized stress redistribution, and this study provides further evidence that tomography can indicate the redistribution of induced stress within a mined rockmass and is another tool available to ensure that mining is conducted safely and efficiently.

Aug 1, 2022

By F. C. Clapp

Although many oil fields have been, and still are being, discovered in Oklahoma, the geology and structure of most of them have not become familiar to the general public because of the delay in securing government geological surveys and the reluctance of oil companies and other intercsted parties to give out their "inside information " Therefore, until official surveys are available, it behooves us to publish geological results as soon as possible. Fortunately the writer has been authorized by the Cement Field Oil Co. to publish his data on the Cement field, Caddo County, at this time. Locality and Description The Cement field is situated in the part of Oklahoma known generally until recently, as "Healdton fields," and lies 60 mi. (96 km.) northwest of the Healdton field proper. Like the Healdton field, it forms an approximate ellipse, trending northwest and southeast through the village of Cement on the St. LouisSan Francisco Railroad, on which it is reached in 21/2 hours from Oklahoma City. In its geological structure, the field constitutes an anticline over 13 mi. (21 km.) long and from 1 to 3 mi. wide; the point of greatest width being not far from its intersection by the above-named railroad. The major axis trends north 75' west from the village of Cement; but eastward appears deflected (if field interpretations are correct) to about south 45" east. About 5 mi. south lies an approximately parall el syncline, which may be conveniently called the Cyril syncline, the south and west boundaries of which may be distant many miles, but forming a closed basin south of the Cement anticfine. The positjon of the offsetting synclinal axis, which is believed to lie north and east of-Cement, has not been discovered. TOPOGKAFHY In the southwest part of the state, nearly all maps of Oklahoma show two mountain areas—Arbuckle and Wichita—which are conspicuous geological and topographic landmarks. In addition, some maps show a third, and smaller, range, named the Keechi Hills, in the vicinity of Cement. These hills also form a conspicuous feature in the landscape; but for some reason they have been neglected by geologists, and the

Jan 1, 1921

By Raymond O. Ladoo

FUSED quartz is a glass made by the fusion of nearly pure silica. Some confusion in terminology exists but in the trade today "fused quartz" generally refers to the perfectly transparent colorless product made from rock crystal whereas "fused silica" is a white, translucent product made from silica sand. Vitrified silica is the term preferred by purists for all quartz glass, but it lacks the definiteness of -the trade terms. Since the raw materials, methods of production, and properties of the finished products arc different for the two types, the trade terms are preferred. As fused quartz is amorphous, it-physical properties differ greatly from those of quartz crystal. Lacking crystallographic directions and having no piezo-electric properties, fused quartz. of course, has no value for the making of radio oscillator plates; but it does have other valuable and unique properties. Perhaps the 'best known and most useful properties are its extremely low coefficient of expansion and its ability to transmit short-wave ultraviolet radiant energy. Crystal quartz not only has an aver-

Jan 1, 1947

The selection of the best comminution circuit for the preparation of concentration feed is a compromise based on economics, energy efficiency, labour costs, steel consumption, availability and other factors specific to each case. It is postulated that the selection must be a choice of one of the eight basic comminution circuits which can be divided into two basic groups, (1) autogenous or semi-autogenous primary mills with or without a secondary grinding stage and (2) fine crushing usually in cone crushers followed by a rod mill-ball mill circuit or a single stage ball mill circuit. The accuracy of selection may be improved by pilot plant and laboratory tests which are described in this paper. For (1) above, testing includes media competency tests with standard impact crushing, grindability and abrasion tests followed by pilot plant tests. For (2) above, bench scale crushability, grindability and abrasion testing is available. It is suggested that, through these tests, it should be possible to eliminate all but one in each group of basic comminution circuits. Then engineering and economic studies should lead to the best comminution circuit for the specific requirement.

Jan 1, 1984