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By C. J. Edmonds, R. Bland, W. C. Ferguson, R. Whitehead

"In 1969, the Environmental Science Division of James F. MacLaren Limited received authorization from The International Nickel Company of Canada, Limited to carry out a water quality monitoring program in the Lake Shebandowan region of Ontario, where a new base metal mining and milling complex was expected to go into operation in 1972. The objective of the program is to establish base-line water quality characteristics. Fully realizing their corporate responsibility to minimize the effects of the proposed activities on the environment, Inco decided that it would be desirable to establish a program by which any change in the quality of environmental waters will be detected before detrimental conditions ensue, permitting prompt corrective measures to be taken. The program has been in progress for over two years. The waters are sampled and analyzed four to six times per year. Sampling stations are located in Lake Shebandowan and on the adjacent Gold Creek - Matawin River system. On-site analyses and measurements are made of flow, dissolved oxygen, temperature and pH. Samples also are collected for later analysis in the laboratory. These samples are analyzed for a wide range of chemical and biological characteristics. The paper discusses the extent of the sampling program, the techniques utilized and the value of such programs in maintaining the quality of the environment."

Jan 1, 1973

By L. C. IlsLey, E. J. Gleim, F. CRAVEN

Electrical apparatus and circuits began to be used in mines about 50 years ago. A search of the literature on mining reveals that in 1882, umping was being done by electricity in some aines of England. One account tells of a small electric locomotive being used in 1882 "to drive eight corves loaded with coal" in a mine near Dresden. In an account of his visit to some English mines, en American in 1892 mentions that he saw underground electric signals, lights, pumps, hoists, and one revolving- cutter-bar 19wall mining machine,. Among the carl electrical installa- tions in the United States was an electric locomotive in the Lykens Valley Coal Co. mine at Lykens Valley, Pa., in 1887. In 1889 the Sperry electric coal digger was being tried out. Tarce mining machines were placed in the Prospect mine, East Palestine, Ohio, in 1890. An electrical pumping plant was put in oneration during 1892 in the Woodward mine of the Delaware, Lacka- rahma & Western Railroad Co. Thus we Almost coincident with the proposed use of this new servant in under- ground workings, came the thought of making it safe in gassy mines. find an account of a design for a protected stationary electric mine lamp proposed by Edison in 1831. Enclosed-type motors rere developed in the United States and shiped to English collieries about 1903. From those early beginnings there has been continuous progress until to-day one finds hundreds of pieces of specially designed electrical apparatus distributed in American coal mines and in mines of nearly all important coal-producing countries. Along with introduction of this equipment grew the idea of the necessi- ty of government aid, in standardization. In most coal-mining countries to- day the governments either directly or indirectly have a considerable in- fluence in guiding the design of electrical equipment intended for use in Pasay mine

Jan 1, 1933

By Ralph W. Smith

DEVELOPMENT of the lime industry- in Ste. Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there are today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. GEOLOGY The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft. of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaC03; 0.35 Si02; 0.3 R203; 0.35 MgCO3; 0.3 S03. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 ½ º. Thus the outcrops of the various sedimentaries run approximately north and south. A line running west from Ste. Genevieve crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 ½ º the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile

Jan 1, 1938

By Donald D. Smythe

This paper describes briefly the topography and geology of the region where the mica-bearing pegmatites are found and discusses prospecting, the quality of the mica, its preparation, and evaluation of the deposits. Muscovite mica occurs in a number of widely separated localities in Brazil, but production has come largely from deposits in the southeastern and eastern part of the State of Minas Gerais (Fig. I). There the deposits form a discontinuous zone, which starts at a point go km. north of the city of Rio de Janeiro and extends north for some 500 km., roughly parallel to the coast. A maximum width of 180 km. is reached along the Rio Doce. To the west in Minas Gerais, and extending east into the states of Espirito Santo and Rio de Janeiro, the mica zone proper is fringed by areas in which there are scattered occurrences of mica-bearing pegmatites. A few of these outlying deposits have produced commercial mica, but most of them are unimportant. To the southwest, in the State of Sao Paulo, there are a number of mines, which at one time produced a very considerable amount of sheet mica, largely as a byproduct of kaolin mining. These deposits, and a few others lying between them and the main productive areas to the northeast, appear to be the southwestern continuation of the strong Minas Gerais mica zone. In the vicinity of Conquista, just north of the Minas Gerais boundary in the State of Bahia, and still farther north, near Jacobina, there are several known mica deposits. Their location indicates that they may be the northern continuation of the main mica zone. The major part of Brazilian mica production has come from four areas within the mica zone proper; from north to south, Governador Valadares, Raul Soares, Espera Feliz, and Muriaé.. The first is go km. from north to south and reaches a maximum width of 180 km. The Raul Soares area extends 135 km. from northeast to southwest, and in places is 80 km. wide. The Espera Feliz area is 100 km. from north to south, and reaches a width of 35 km. The Muriai. area extends 150 km. from northeast to southwest and its width reaches 40 kilometers. Between the known productive areas, and in the areas directly to the southwest and to the north of them, little mica has been produced. These gaps, as well as certain irregularities in the outline of the mica zone itself, are to be ascribed either to lack of prospecting or to conditions preventing the discovery of mica, rather than to its nonexistence. Elsewhere in Brazil mica has been reported from eastern Goiaz, Ceará, Pernambuco, Rio Grande do Sul, Matto Grosso, and Amazonas. Production from these sources is negligible at present. Because of the inferior quality of the mica from the more accessible of these localities, and the operational difficulties occasioned by the remoteness of others, it is improbable that they will become important producers for some time to come.

Jan 1, 1948

By Donald D. Smythe

This paper describes briefly the topography and geology of the region where the mica-bearing pegmatites are found and discusses prospecting, the quality of the mica, its preparation, and evaluation of the deposits. Muscovite mica occurs in a number of widely separated localities in Brazil, but production has come largely from deposits in the southeastern and eastern part of the State of Minas Gerais (Fig. I). There the deposits form a discontinuous zone, which starts at a point go km. north of the city of Rio de Janeiro and extends north for some 500 km., roughly parallel to the coast. A maximum width of 180 km. is reached along the Rio Doce. To the west in Minas Gerais, and extending east into the states of Espirito Santo and Rio de Janeiro, the mica zone proper is fringed by areas in which there are scattered occurrences of mica-bearing pegmatites. A few of these outlying deposits have produced commercial mica, but most of them are unimportant. To the southwest, in the State of Sao Paulo, there are a number of mines, which at one time produced a very considerable amount of sheet mica, largely as a byproduct of kaolin mining. These deposits, and a few others lying between them and the main productive areas to the northeast, appear to be the southwestern continuation of the strong Minas Gerais mica zone. In the vicinity of Conquista, just north of the Minas Gerais boundary in the State of Bahia, and still farther north, near Jacobina, there are several known mica deposits. Their location indicates that they may be the northern continuation of the main mica zone. The major part of Brazilian mica production has come from four areas within the mica zone proper; from north to south, Governador Valadares, Raul Soares, Espera Feliz, and Muriaé.. The first is go km. from north to south and reaches a maximum width of 180 km. The Raul Soares area extends 135 km. from northeast to southwest, and in places is 80 km. wide. The Espera Feliz area is 100 km. from north to south, and reaches a width of 35 km. The Muriai. area extends 150 km. from northeast to southwest and its width reaches 40 kilometers. Between the known productive areas, and in the areas directly to the southwest and to the north of them, little mica has been produced. These gaps, as well as certain irregularities in the outline of the mica zone itself, are to be ascribed either to lack of prospecting or to conditions preventing the discovery of mica, rather than to its nonexistence. Elsewhere in Brazil mica has been reported from eastern Goiaz, Ceará, Pernambuco, Rio Grande do Sul, Matto Grosso, and Amazonas. Production from these sources is negligible at present. Because of the inferior quality of the mica from the more accessible of these localities, and the operational difficulties occasioned by the remoteness of others, it is improbable that they will become important producers for some time to come.

Jan 1, 1948

By Richard E. Gray

Virtually all structures show some signs of distress due to deterioration of the building components, to changed loads, or to changed support conditions. Changed support conditions result from ground movements. In mining regions many cases of structural distress are attributed to mining without considering alternative causes. This is particularly true of coal mining since it occurs under extensive areas. Coal mining is estimated to have already undermined more than eight million acres and may eventually undermine 40 million acres in the United States (HRB Singer, Inc., 1977). Other nonmetal and metal underground mines impact much smaller areas. Although it is sometimes difficult, even with careful study, to identify the actual cause of damage, persons responsible for underground coal mining should at least be aware of possible causes of building stress other than mine subsidence. This paper presents information on distress to structures and briefly reviews a number of causes of ground movements other than subsidence: Mass movements, dissolution, erosion, frost action, shrinking and swelling, yield into excavations and compressibility

Jan 1, 1986

By Bartosiewicz H

A method for the determination of the gas content of coal seams is presented which improves upon existing methods. The method makes use of a gravitational technique for measurement of the gas desorbed. The amount of lost gas is estimated by determining an empirical relationship relating the desorption of gas with time for each sample separately. This is to replace the assumption that desorp- tion follows a square root law with time. Laboratory investigations have been conducted which indicate that the square root desorption law does not hold good for carbon dioxide. Results of investigations on various factors influencing the technique are presented. It is shown that co-efficients of the empirical equation are dependent upon the elapsed time and the period of observation. Data about gas pressure measurements is presented and it is concluded that gas pressure can be approxi- mated to 0.6 times the pressure below a column of water equal to the depth of cover. This estimate is good enough for adsorption tests to evaluate desorption co-efficients. The technique for repressurisation of the sample,

Jan 1, 1982

By Paul Hughes

Purpose of Research ? What are the loading mechanics of paste against barricades? ? What is the capacity of the composite paste fill fences? ? Based on the loading mechanics of the paste, do the fill fences pose a risk of failure? Outline ? Glossary of Terms ? General Introduction ? Research Methodology ? Site Description ? Instrumentation Program ? Results ? Analysis ? Conclusions ? Recommendation for Future Work

May 1, 2008

By Robert Archer

IT is now well known that the structure of aluminum-silicon alloys can be refined in a rather remarkable manner, with consequent improvement of physical properties, by certain treatments applied to the molten metal shortly before casting. The differences between the treated and the untreated alloys are so marked that special terms are used to distinguish them, the untreated alloys being referred to as "normal" and the treated alloys as "modified." The first practical method of accomplishing this result was that of A. Pacz,1 which consists in treating the molten metal with a, salt flux of which the, active ingredient is sodium fluoride. The result can also be brought about, and in a more economical manner, by the addition of small quantities of metallic sodium (or potassium) to the molten alloy shortly before casting.2 The action of the Pacz flux evidently consists essentially in the production of free sodium by the reaction of sodium fluoride with aluminum. The changing of a normal alloy to a modified alloy is referred to as "modification' and any process for accomplishing this result is a "modifying" process. Modified aluminum-silicon alloys were introduced several years ago, and it has been demonstrated both in the laboratory and in commercial practice that it is no simple matter to produce castings having the maximum or nearly the maximum properties which under favorable circumstances can be obtained. The alloys are rather sensitive to small changes in chemical composition, and the modifying process must be carried out in a very particular manner to obtain the best results. Extensive experimental work has been carried out in the laboratories of the Aluminum Company of America with the object of determining the conditions that must be observed to make these alloys of the greatest possible

Jan 2, 1926

By David Wilshaw

Continuous Surface Wave (CSW) testing has been the “next big thing” in ground characterization for the last 25 years. The technique uses surface geophones to measure the speed at which Rayleigh waves (generated by a vibratory source) travel through the ground over a range of frequencies. The velocity at which surface waves travel through the ground is directly related to ground stiffness; the velocity of shorter wavelengths is influenced by the stiffness of shallower soil layers, while the velocity of longer wavelengths is influenced by the stiffness of deeper layers. Measuring the surface wave velocity over a range of frequencies, therefore, allows a stiffness / depth profile to be produced. Using the small-strain stiffness data measured by the CSW technique greatly improves the accuracy of simple limit state analyses; the data are also of sufficient quality for use in Finite Element modelling. Nonetheless, the technique has suffered from a perception of high cost, low productivity, and poor repeatability. An improved Advanced Continuous Surface Wave (ACSW) testing system has been developed by Ground Stiffness Surveys in the United Kingdom, has been deployed there commercially for several years, and is now available in the United States. ACSW uses an automated electronic control system that generates vibrations (from a purpose designed and manufactured portable seismic “shaker”) at different frequencies, measured across a 3m (10-foot) array of geophones, linked to a robust data acquisition and analysis software package. The range of applications in geologic and geotechnical site characterization includes rapid preliminary non-intrusive site assessments (utilizing published soil correlations); stiffness profiling to detect discrete layers (such as a variation in rockhead); average stiffness profiling for earthwork or ground improvement control testing, Working Platform stability assessments, foundation settlement analysis, rock quality and rippability assessments, and void detection.

Oct 1, 2022

By George Burrell

INTRODUCTION THE senior author of this paper, while in Colorado on other official business, made a trip to the Cripple Creek gold-mining district to get more data than are at present available regarding the composition of the gas that issues from the rock into the mines of the district. This was done at the suggestion of George S. Rice, Chief Mining Engineer of the Bureau of Mines. There are many questions of interest and importance in connection with the ventilation of the mines in the Cripple Creek district, such as the menace to life and mining of a suffocating gas entering the mines from the rock, the danger due to powder smoke (from blasting operations), and danger of continued inhalation of rock dust by the miners. This report confines itself to the first problem, the gas from the rock, and principally to one phase of this question, the composition of the gas and its effects on men and lights. A more thorough study of this and other ventilation problems is planned. That the, rock gas is a real menace is shown by the fact that miners (variously estimated from 25 to 50 by different persons interviewed) have been killed by it in the 25 years that mining has been vigorously carried on at Cripple Creek. Many men have had narrow escapes from death, some of them having been incapacitated for days. In addition, much loss of time results because at certain periods of the year or on certain days it is impossible to enter some workings. At a few mines fans force air into the workings, thus supplementing the natural ventila-

Jan 5, 1916

By D. O. Hobson, J. O. Stiegler, C. J. McHargue

The effects of alloy composition, deformation temperature, heal treatment, ad inlerstilial contamination on the occurrence of deformation twins were studied. The twinning transition temperature varied with composition and was a maximuni of 140°C for the 40 pcl V composition. Tire remperature range of the transition was very narrow. Alloys of 20 to 70 pet V could he cold-rolled and exhibited profuse twinning. The alloys which did not twin at room temperature (10, 80, and 90 pel V) could plot be cold-rolled. Oxygen additions systematically lowered the transition temperatures for all vanadium contents. The transition temperature for a 30 pet V alloy increased with annealing temperature, apparently due to changes in dislocation density and configuration. Twinning did not nucleate fracture in any specimen in the 20 to 60 pet V composition range. THERE is great current interest in the refractory metals and alloys as structural materials. An important factor in considering the ductile-brittle behavior of such materials is the role of mechanical twinning as a deformation mechanism. Mechanical twins have been observed after deformation at low temperatures or at high loading rates in the pure metals iron,1 vanadium,2,3 columbium,4,5 tantalum,6 Chromium,7 molybdenum,8 and tungsten.9 Binary alloys in which mechanical twins have been observed include: iron with silicon,10 phosphorous," or aluminum;12 and chromium, molybdenum, or tungsten with rhenium.13-17 The increase in low-temperature ductility obtained by alloying the Group VI-A elements with rhenium is very important with regard to fabricability, and there has been considerable effort to understand the so-called '(rhenium effect". Factors suggested to explain this effect include:'' 1) increase in solubility of interstitial impurities with alloying (electronic effect): 2) changes in the nature of grain boundary phases; 3) changes in interfacial energies of grain boundaries and stacking faults: and 4) promotion of twinning. Although an outstanding characteristic of these alloys is the profuse twinning that accompanies low-temperature deformation, most studies of the rhenium effect have been concerned with the other factors. During recent studies of refractory-metal alloys, it was noted that solid solutions of columbium and vanadium exhibited high hardness and strength at room temperature and elevated temperature and, surprisingly, also showed considerable ductility at room temperature and below. These alloys deformed by twinning at room temperature when subjected to slow loading rates. It appeared that the low-temperature ductility resulted at least in part from the relaxation of stresses by twinning in a system where slip is difficult. The reason for enhanced twinning behavior in some bee solid-solution alloys is unknown. There have been suggestions18,19 that, as in fee alloys, the

Jan 1, 1965

By Gregg W. Morrison

"The Craigmont copper-iron skarn deposit is adjacent to the southern margin of the late Triassic Guichon Creek batholith in south-central British Columbia. Host to the ore are sedimentary and volcanic rocks of the western calc-alkaline belt of the Upper TriassicNicola Group. In the mine area, the Nicola Group rocks are a stratigraphically complex sequence, at least 1800 feet thick, which have been subdivided into Basalt, Rhyolite, Carbonate and Clastic Sediment units. All the units strike and dip parallel to the margin of the Guichon Creek batholith and are within the batholith contact aureole. However, only the Clastic Sediment unit is in contact with the batholith.Most of the skarn and ore is within the Carbonate unit and more specifically within an Interbedded facies that consists of lime sandstone, lime siltstone, quartzo-feldspathic siltstone and argillite. The Interbedded facies and the adjacent barren Massive Limestonefacies are interpreted aspart ofa carbonate reef complex. The distribution of skarn and ore within the Interbedded facies suggests that the facies boundary was a physical and chemical barrier that resulted in concentration of metals adjacent to the Massive Limestone facies.Two stages of skarn formation have been recognized at Craigmont. In Stage I, ore-bearing magnetite-rich and actinolite-epidote-magnetite skarns developed both in basaltic rocks and in Fe-bearing siltstone and argillite of the Interbedded facies, while barren grossular garnet-epidote-calcite-pyrite skarns developed in Fe-poor rhyolitic bands within the Interbedded and Massive Limestone facies . In Stage ll, massive, barren grandite garnet skarn replaced mineralized Stage I skarns in the vicinity of diorite plugs. and specularite ore formed in brecciated Stage I skarn and clastic rocks away from the plugs. Theformation of Stage I skarns required no addition of material, only redistribution and concentration of elements already present within the Interbedded facies. However, the concentration of Cu in Stage lore requires a mechanism for more efficient leaching of Cu from the host rocks, an anomalous concentration of Cu at the site of the Stage I orebody or an additional input of Cu from an external source. The formation of Stage II skarn and ore requires only remobilization and recrystallization of Stage I skarn and ore.Copper and iron are the only elements in economic concentrations in the ore and chalcopyrite is the only significant copper-bearing mineral. Chalcopyrite is disseminated and interstitial to magnetite in Stage I mineralized skarns and is interstitial to specularite in the matrix of Stage II breccia ores. Chalcopyrite also occurs with pyrite as stringer ore in bleached • sediments and rhyolite tuffs in the stratigraphic footwall of the main orebodies.The Craigmont deposit has more features in common with Cu-Fe deposits hosted in metavolcanic and metasedimentary rocks than it has with typical skarn deposits associated with porphyry copper deposits. The orebody is more likely a product of concentration of metal contained within the Nicola Group rocks than of the mineralizing event that produced the . Highland Valley Cu-Mo porphyry deposits in the central part of the Guichon Creek batholith ."

Jan 1, 1980

The rheological behavior of high concentrated coal -water slurry (cws), a new liquid fuel, is an important factor in the preparation, transportation and combustion. The conventional viscosimeters designed for Use with true fluids are not suitable to the measurement of the rheological behavior of cws. So that a special viscosimeter of tube type for cws was designed and set up in .laboratory. Experiments using two kinds of cws from two provinces from P. R. Olfna were conducted. It is found from test results that the experimental cws possess the rheological character of Bingham fluid and there is the existence of the wall effects which causes the measurement errors. In our former paper published the wall effects were discussed III the light of methods of Odroyd and Jastrzerbsiki to make the correction of the experimental results. But a number of tests are necessary to meet the need of determining the slip coefficient. In this paper the models of the wall slip velocity and the thickness of the slip layer of Bingham fluid were proposed III in theoretical approach which were satisfactorily used in the correction of the measured results of the rheological character of cws.

Jan 1, 1994

By J. J. Jonas, G. Gagnon

SHG zinc was extruded in the temperature range 110" to 350°C and the strain rate range 0.05 to 5 sec-1 The strain rate/flow stress/temperature results were analyzed using a power sinh stress relationship. When temperature changes due to the heat of deformation and to heat losses are neglected, the exponent of the sinh function of the stress is 5.6, and the apparent activation energy of deformation is 28 kcal per mole. When these changes are taken into account, the exponent decreases to 4.7 and the activation energy to 23 + 2 kcal per mole. The corrected stress exponent and activation energy are in very good agreement with published values obtained from creep experiments, and suggest that the hot extrusion of zinc is controlled by a mechanism involving self-diffusion. When the extrusion and creep data are compared using a Zener-Hollomon parameter and either a sinh or an exponential stress term, an appreciable offset is observed, which may be due to the difference in impurity content. For a given set of extrusion conditions the ram speed, maximum pressure, and initial temperature can also be correlated using a Zener-Hollomon parameter and a sinh pressure term. THE deformation of metals at temperatures over about one-half the absolute melting temperature has been extensively studied at creep strain rates. By contrast, relatively little work has been carried out on the behavior of metals at hot working strain rates. Most of the latter investigations have been performed using simulative methods, such as hot torsion and hot compression, in which the friction conditions and temperature rise during deformation may differ appreciably from those existing under industrial conditions. Recently, however, Wong and Jonas1 used a scaled-down industrial process to determine the stress and temperature dependence of the strain rate during the extrusion of aluminum. In such tests, the effects of friction and adiabatic heating are closer to those produced in industrial operations. Also, with regard to the testing of materials of limited ductility such as zinc, hot compression and hot torsion do not permit the attainment of true strains as large as the deformations usually applied commercially. The present study was undertaken to investigate the extrusion behavior of Special High Grade (SHG) zinc. The detailed objectives were: 1) to establish the stress and temperature dependence of the strain rate with and without a consideration of adiabatic heating, 2) to study the pressure and temperature dependence of the ram speed, and 3) to investigate the microstruc- tural changes occurring during the deformation. The last aspect of the investigation will be covered in a separate paper. The treatment described below differs from that of Wong and Jonas in that the adiabatic temperature rise during deformation is taken into account, and the calculation of the mean equivalent strain rate is based on the redundant as well as on the homogeneous work. EXPERIMENTAL PROCEDURE Rods from two shipments of continuously cast SHG zinc* were used in the investigation. The composition *Supplied by courtesy of Cominco Ltd. range of the impurities present, as given by the supplier, was: Pb: 0.0013 to 0.0023 pct, Fe: 0.001 pct max Cd: 0.0001 to 0.0006 pct, Cu: 0.0002 to 0.0005 pct, Ti: 0.0001 pct max; thus, by balance, zinc valued from 99.9963 to 99.9966 pct. The as-received rods were machined into billets having a nominal diameter of 1.56 in. and a nominal length of 1½ in.; longer billets up to 4 in. in length, were also used to investigate special aspects. The as-machined rods were annealed at 400°C for 24 hr and slowly cooled. This treatment produced a columnar grain structure, with a grain size of about $ by 2½ cm which was appreciably larger than the as-cast one. A 150-ton, direct extrusion, vertical press was used. Ram displacement and force were recorded continuously against time. A constant flow control valve permitted the maintenance of a range of preselected ram speeds up to in. per sec. The selected speed was held constant, irrespective of the required force, as long as the load developed was below the maximum available. Strain gages were used to determine the force; the gages were calibrated before and after each testing period with a 200,000-lb capacity load cell. Further details of the experimental equipment can be found in Ref. 2. The billets were preheated for 90 min in the extrusion container, which was well insulated so as to minimize temperature gradients. This period was sufficient for the billet to reach a uniform temperature at all temperatures between 110" and 350°C. A square-shoulder die having a 0.290-in. diam central hole was used. The extrusion ratio was 30 to 1. This is equivalent to a reduction in area of 96.7 pct, an elongation of 2900 pct, and a true strain of 3.4. The ram speed was varied over two orders of magnitude from 0.0027 to 0.26 in. per sec. The ram was water-cooled during most of the tests, although some experiments were conducted with a preheated, uncooled ram. All extrusions were run without lubricant, which resulted in conditions of sticking friction. EXPERIMENTAL RESULTS Stress Dependence of the Strain Rate Neglecting Adiabatic Heating. The maximum force required to extrude is given in Table 1 for each of the five initial

Jan 1, 1970

One of the most important parameters in rock/resin/bolt load transfer mechanism is the surface property of the bolt. Although there are various bolt surface configurations available in the market, very little work is reported on the bolt/resin interface failure mechanism. This paper examines the behaviour of bolt surface roughness under constant normal stiffness conditions which is considered as being a realistic way of evaluating bolt surface roughness. A series of shear tests have been conducted on the flattened bolt surface to study the shear behaviour of bolt/resin interface. Based on the experimental results, a mathematical model has been developed to predict the shear resistance of the bolt/resin interface at various normal stress levels for the bolt types used in the study.

Jan 1, 1999

By A. J. Kraemer

[The Bureau of Minas for a number of years has been studying the properties of crude petroleum from producing fields in the United States and Western Hemisphere and has published a series of reports on these fields, including oil fields of Texas.5]

Jan 1, 1927

By John L. Lamont, Walter Crafts

SECONDARY hardening in tempering has long been recognized as a typical characteristic of steels containing large amounts of carbide-forming alloys. These steels, when quenched and tempered, tend to soften somewhat after tempering at low temperatures, and to reharden at intermediate tempering temperatures before finally softening to low hardness. This behavior in tempering has been studied by many investigators, chiefly with respect to the secondary hardening of high-speed steels. The initial softening has usually been ascribed to decomposition of martensite and growth of iron carbide particles. The secondary hardening has been explained by formation of fresh martensite from residual austenite, formation of very fine alloy carbide particles and by precipitation hardening of metallic compounds in the ferritic matrix. However, factors derived for the calculation of tempered hardness in low-alloy steels1 indicated only a tendency toward retarded softening rather than a discontinuous rehardening. A study was, therefore, made to determine whether fresh martensite from residual austenite and precipitation hardening are essential to rehardening and the degree to which tempered martensite could be rehardened by precipitation of alloy carbides. The mechanism of carbide rehardening was also investigated to determine the nature of the process. The causes of secondary hardening in high-speed steel have received serious consideration for about thirty years. Among the earlier workers Bain and Jeffries2 in 1923 recognized residual austenite as a significant factor, but in addition, emphasized the effect of the formation of alloy carbide particles of "critical" size. They conceived that freshly quenched martensite forms low-alloy iron carbide at low tempering temperatures; with further tempering the iron carbide is then modified by alloying elements that can diffuse most readily at intermediate temperatures (850°F); and that the iron carbides grow in size by coalescence so that the steel tends to lose hardness. At higher tempering temperatures carbide stability rather than alloy availability becomes the controlling influence and in high-speed steel "iron-tungsten carbide is the most stable one and forms to the elimination of the earlier formed carbides. . . . The iron-tungsten carbide particles reach approximately the size for critical dispersion after a short reheat at 1100°F." This concept, the formation of alloy carbide nuclei, redissolving of the iron carbide, and diffusion of carbon to the alloy carbide, was restated for vanadium steel in 1932 by Houdremont, Bennek, and Schrader.3 Subsequent studies have confirmed that iron carbide changes to alloy carbide at 1000 to 1100°F, but the mechanism of the process has received little consideration .

Jan 1, 1948

The man in the street (and no doubt most members of the Institute) thinks of wire, if he gives it any thought at all, as a most commonplace commodity. It is an accepted necessity, and like most necessities is taken for granted, unless a shortage in one or other of its multitudinous forms or products causes inconvenience.For many years Australia has ·been a large consumer of wire, particularly for fencing. With the rapid development of secondary industry the demand has increased in both size and character until at the present time much of the wire produced in this country is used as raw material for subsequent manufacturing processes. The call has been of so varied a nature that the Newcastle Wire Mills now turn out a greater variety of wire types than any other single plant in the world.In this paper, the aim is to provide a picture of the manufacturing, properties, and uses of wire. No attempt is made to cover the subject in any detail, as the field is much too broad for anything other than general treatment. Many phases, particularly in regard to manufacturing processes, are, therefore, dealt with cursorily, but it is hoped that the paper will, without delving too deeply into the technical aspects of Wire production, give a general appreciation of:- (a) How steel wire is made. (b) The remarkable physical characteristics obtained by judicious combination of chemical composition, heat treatment, and subsequent cold work. (c) The uses of steel wire.HISTORY.Best known of the early references to wire is that appearing in Exodus, where mention is made of gold wire being used for the sacerdotal robes of Aaron. However, the period in question, about B.O. 1491, is comparatively modern history as far as wire is concerned, for specimens believed to have been made about B.O. 4600 have been found. It is fairly certain that the Egyptians produced iron wire in B.O. 4000. Of particular interest is the

Jan 1, 1947

By W. M. Weigel

Economic deposits of barite occur in Missouri in two main districts. The most important, the Southeastern or Washington County district, is in the southeastern part of the state, mostly in Washington County with a small extension into the northeastern part of St. Francois County. Roughly, it embraces nine townships or about 200,000 acres and accounts for from 80 to 90 per cent. of the state production. The Central district, is in the central part of the state, includes most of Morgan and Miller counties, and parts of Camden; Benton, Moniteau and Cole counties. The area embraced is much larger than the Washington County district, but the deposits are more infrequent. The location and general area covered by the two districts is shown in Fig. 1. There is another small area in southern Franklin County but so far its production has been of small consequence. It might be considered as a northward extension of the Washington County field. An, area in the central part of Hickory County has also produced a small amount. The outline of the districts as shown indicates the general area in which deposits have been found. The total area covered by deposits of barite is only a small part of this, as, in the Central district especially, there may be miles of supposedly barren areas between ore-bearing areas of an acre or two in extent. The date when barite was first mined in Missouri cannot be definit stated, but the industry probably dates back to about 1860. The occurrence of barite was known long before this, as it was encountered in the lead mines in Washington County and mentioned by several earlier writers." Missouri is reported as producing 8000 tons in 1882 so it is evident the industry was well under way in the seventies in order to have arrived at this substantial production. By 1893 Missouri production had increased so that it ranked with that of Virginia, then the largest producer it increased until in 1914 Missouri accounted for about 65 per cent. of the total United States output.

Jan 1, 1929