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At moderate depths this question is of relatively small importance, but at depths over 2,000 feet it becomes a matter of some consequence. The rate of increase of temperature with the depth varies in different localities, but as a rough average we may take it to be about 1° Fahr. for every 50 feet of depth. The variation of temperature of the earth's surface from summer to winter penetrates to a comparatively shallow depth. At 50 feet the variation becomes practically insensible, and the temperature of the strata will be about the mean temperature at the given locality, from 60° to 75° F. in this country or the comfort of men working in the mines it is desirable to maintain a temperature of about 70° F. in the workings, or approximately the temperature of the strata near the surface.In order to obtain some idea of the magnitude of the undertaking involved in cooling a mine, I have examined the effect of placing in a long drive an apparatus by means of which we can abstract heat at a uniform rate from the drive, keeping, thetemperature nearly the same at all points of the drive at any given time.The lowering of temperature 70 F. at any distance feet from the centre of the drive (treated as a cylinder of the same sectional area as the actual drive), after an interval of time days from the commencement of the operation is given by the formula...

Jan 1, 1907

Mine Transitman.-Engineer, about 30 years of age, experienced in coal mine underground surveys. Must be good draftsman and possess sufficient personality to get results from the men. Location, Illinois. No. R 419. Coal Mining Engineer: Coal mining engineer of proved ability for position of manager f high-grade bituminous coal property. Location, Canada. No. R 427. Chemist or Metallurgical Engineer.-Chemist or metallurgical engineer for special library work. Man with scientific training with the ability and education -of a young instructor in a university. Duties would consist of working out a new method of indexing scientific information, more particularly in obtaining information for use of a Committee on the Heat Treatment f Steel. Location, Washington, D. C. No. R 470. Topographical Draftsman.-Civil engineering training and topographical and surveying experience. Unmarried man, under 40 years of age. Knowledge of Spanish not necessary. Discharged army or navy man preferred. Location, oil fields, Mexico. Salary, $5 per day, living and traveling expenses. No. R 483. Mechanical Draftsman.-Engineering training, familiarity with drawings of pumps, piping, etc., need not necessarily be a designer. Unmarried man, under 40 years of age. Discharged army or navy man preferred. Location, Mexico. Salary $5 per day with living and traveling expenses. No. R 484. Engineer Translator.-Engineer of Portuguese nationality who has received his technical training abroad, and has been filling engineering positions in this country, to translate material for catalogs of an engineering character. No. R 486.

Jan 5, 1919

By Francis M. Walters, Irvin R. Kramer

THE substitution of cobalt for part of the nickel in Invar was found by P. H. Brace1 to lower the coefficient of expansion. Scott1 extended the use of cobalt to alloys of higher inflection temperatures. Such alloys have a larger temperature range of low expansion than those without cobalt, and [ ] their use up to 400° or 500°C. offers decided advantages in certain applications. However, it has been found that the iron-nickel-cobalt alloys are not stable in this temperature range. EXPERIMENTAL METHODS Two methods were used in studying the stability of the low-expansion iron-nickel-cobalt alloys. Dilatometer specimens were held at 480°C, for 9 months and the change in expansion characteristics was determined. Filings were held for about 2 months at various temperatures and the change in structure was determined by X-ray diffraction. As shown by Table I, the alloys studied covered a wide range in nickel plus cobalt content (which determines the inflection [ ] temperature) as well as some variation in the ratio of nickel to iron (which controls the temperature of the gamma to alpha transformation). Included also are alloys containing carbon and vanadium, carbon and titanium and three with various amounts of copper. The alloys were melted in a high-frequency induction furnace with a magnesia crucible, using ingot iron, electrolytic nickel and commercial cobalt. Fifteen-pound heats were cast into iron molds after deoxidizing with silicon, or

Jan 1, 1941

By Kerry Spickelmier

A traveler driving across desolate central Nevada to the Round Mountain property can easily identify with turn- of-the-century prospectors seeking a fortune, or at least an existence, from the high desert. But now a shadow passing overhead is as likely a sophisticated fighter aircraft from Stillwater Naval Air Station as a circling bird, and the famous trails west show only as historical markers along the highway. Even the approximately 400- km (250-mile) trip southeast from Reno or northwest from Las Vegas takes hours now, not days. And the camps of Round Mountain’s early prospectors have been replaced by one of the world’s largest gold heap-leaching operations. While Round Mountain’s uniqueness begins with its scale, it doesn’t end there. Consider the mine’s low cutoff grade of 0.2 g/t (0.006 oz/st) gold, made possible by a new dedicated (not reusable) leach pad. Also, the operation’s degree of automation means that ore dropped in the south crusher system is not manually handled until it is stripped from the pads. There is the bonus of a geothermal field that is tapped to heat the leach solutions in the winter. And, of course, there was that “unexpected” hitch expected in all mining operations. For Round Mountain, it meant buying a gravity plant to process the gold nuggets discovered last summer in a fault gouge.

Jan 1, 1993

By R. C. Adams

This report describes the feasibility of mining the oil shale deposits of the Piceance Creek basin in Colorado by an integrated open pit system. The study is based upon a comprehensive analysis of pertinent environmental, economic, and engineering factors. Ten mining cases are investigated, and the mine design and cost estimates for each case are presented in this report. Nine of the cases represent three cutoff grades, defining oil shale ore as equal to and above 15 gallons per ton (gpt), 20 gpt, and 25 gpt at three ore production levels of 500,000 tons per day (TPD), 1,250,000 TPD, and 2,500,000 TPD. The tenth case is an alternate design of the 500,000 TPD production rate at the above 15 gpt cutoff grade. The report consists of Volume I, a technical and cost comparison of the ten cases; Volume II-Part I, a detailed explanation of the estimating methods used; and Volume II-Part 2, a more detailed discussion of the technical and cost features of the ten cases than is presented in Volume I.

Jan 1, 1976

By Laurance L. Oden, Jack C. White, Alan D. Hartman

The U.S. Bureau of Mines, under a Memorandum of Agreement with the American Society of Mechanical Engineers (ASME), established design criteria for a facility to field residues from municipal waste combustion. This facility, which is available to potential users on a cost-sharing basis, is also applicable to a variety of inorganic waste materials from smelting or melting operations. The design consists of a mechanical feed handling system, electric arc melting furnace, fume-off gas handling system, and thermal oxidizer for final off gas treatment. Screw conveyors and a bucket elevator deliver up to 2,000 Ib/h of minus I-in material to a three-phase electric arc melting furnace. This unique 800-kVe A furnace has a water-cooled shell and roof to minimize interaction of the melt with the refractory lining. The volume of the hearth below the slag taphole is approximately 1.2 st of steel. The furnace is sealed, allowing atmosphere control within the furnace and fume duct by nitrogen or inert gas injection. A jet-pulsed baghouse removes particulate from the off gas and serves as an acid gas scrubber. The clean off gas is heated to 1,800' F for 1 s in a propane-fired thermal oxidizer before being vented to the atmosphere.

Jan 1, 1993

It was a pleasure listening to this paper. Gary Works' problems were a lot more extensive than the trunnion bearing problems encountered at the Weirton Steel Division. In our two-vessel shop bearing failures are critical in that with a bearing failure on an operating vessel and the second vessel under rebuild, we are down until the vessel rebuild is completed or the bearing is repaired. The first bearing problem at Weirton occurred after we had been operating three years. The failure occurred during the 8th heat following "bum-in" of the vessel. Immediate steps were taken to change the damaged float bearing without an extensive search for the reason the bearing failed. Once the campaign was run out the bearings were inspected and found to be damaged. Field checks revealed that the bearing pedestals were not properly located and as a result the freedom of the float bearing was restricted. The trunnion pin end to end dimension had decreased due to distortion and deflection in the trunnion ring. These dimensions were within tolerances. The damage to our bearing was similar to that in the exhibits from U.S. Steel-Gary Works. Steps taken to correct what was found in the field checks were as follows: 1. The pedestals were relocated to center the bearings. 2. 4" diameter pins were installed to locate the housing in the pedestals. 3. The bearing pedestals were opened up to allow the bearing housing to move slightly in the pedestal. 4. Lubrication fittings for greasing between the bearing housing and the pedestal were installed.

Jan 1, 1972

By Brad Wahlquist

An ex-situ biological treatment system was implemented at a gold mine site in South Dakota. The system removes selenium and nitrate from a mixture of groundwater and surface water runoff at ambient water temperatures. The Applied Biosciences? system replaced a denitrification system that did not perform consistently, did not treat for selenium and required heating of the influent water. Installation was completed in phases starting with the selenium circuit being brought into operation in February, 2002 and the nitrate circuit in March, 2002. System design can accommodate average flows of 380 L/min (100 gallons/minute) and a maximum flow of 1,136 L/min (300 gallons/min). Four cells were designed to remove nitrate from approximately 30 mg/L to below 10 mg/L and two cells were designed to remove selenium from 0.01 mg/L and higher, to below 0.005 mg/L. No pretreatment is required to operate the system at ambient temperatures, which can fall as low as -12C in the winter, and treat water at temperatures ranging between 8C to 16C. Nutrient requirements are met using a sugar based nutrient mixture that includes a balanced C:N:P:S ratio, trace elements and vitamins. Since start up, the system has consistently been in compliance for nitrate and selenium, treating water to below detection limits for both contaminants. This paper discusses laboratory biotreatability testing of a system designed to remove selenium, arsenic, and nitrate and full-scale implementation and optimization of a system to remove nitrate and selenium.

Jan 1, 2003

By Anders Lagerkvist, Agne Rustan, Tommy Edeskar

Landfills containing house hold waste produces methane gas during its decomposition. This gas can be recovered and used for heating purposes or as fuel for vehicles. Gas drainage pipes are installed in the landfill and connected to a central suction point. Methane gas is produced over several years until the slots in the drainage pipes are clogged by black mud. And the bottom of the vertical drainage pipe are filled with mud and water. The hypothesis tested in this paper is if blasting in the drainage pipes could activate the production and flow of methane. In the first part of the paper we have studied what maximum linear charge concentration could be used in different size of PE-pipes place vertical on surface and surrounded by air. The results show that the maximum linear charge concentration for single blasts varied between 5-10 g/m, depending on the diameter of the pipe (90, 100 and 160 mm). Maximum charge concentration for the repeated blast varied between 2-5 g/m. In the second part of the paper we study what maximum linear charge concentration could be used in situ for full scale blasting tests in a special prepared test area which later on was dug out after the blastings. Up to 40 g/m could be used without damaging the top of the 160 mm diameter pipes. The increase in methane flow was so low so it could not be measured c4.5 m3/h. The conclusion therefore is that the stimulation of methane flow by explosives is not enough.

Jan 1, 2000

By David Forrest

In 1981, K. E. Drexler proposed using massively parallel nanomechanical systems to manufacture large atomically exact structures. As in macroscopic mechanical systems, they would contain components that serve traditional functions such as trusses for support, gears to transmit power, bearings for low-friction support of rotating surfaces, motors to supply torque, pipes and conveyor belts for material transport, and channels for coolant. Many of these components would only contain a few thousand atoms. Specific designs for these devices became available in the early 1990s, and a few working devices appeared in laboratories by the early 2000s. As advances continue, a thorough understanding of the operative transport phenomena will guide the intelligent design and construction of nanomechanical structures, devices, and systems. The familiar equations of continuum mechanics are generally inadequate to describe the flow of heat and mass in the proposed nanosystems. Boundary conditions often need to be described in terms of potential surfaces. Surfaces are not geometrically smooth, but periodic according to the locations of atomic nuclei. Friction occurs not due to the plastic deformation of asperities on mating surfaces, but to phenomena such as thermoelastic damping and phonon viscosity when atoms slide past each other. Electrostatic forces dominate over gravitational forces by orders of magnitude; there is no role here for natural convection. Structural components, no matter how stiff and strong, are in constant motion due to the thermal noise in the system. The fluids are described in terms of individual molecules in constant motion.

Jan 1, 2006

By L. W. Helle

In this investigation, which was conducted at the Metallurgical Research Plant, Lulea, Sweden, a series of experiments were carried out using a water-model to simulate the gas rinsing of a ladle containing liquid metal. The factors examined include the effect of gas flowrate, the position of a porous plug or lance, the immersion depth of the lance, and the geometry of the bath at the time of complete mixing. Mixing times were recorded by conductivity measurements. The results showed that there is a threshold level for mixing above which no advantage is to be gained from an increase in the gas flowrate. It is suggested that the results can be applied to rinsing ladles in working situations, the levels being approximately 270 dm3/min for 40 t ladles and 780 dm3/min for 150 t heats. The optimum siting of the lance or porous plug is a position that is three-quarters of the internal radius from the centre of the ladle with the lance penetrating as deeply as possible into the ladle. The best design of liquid bath is that having a diameter-to-height ratio of I. An equation was developed for the calculation, by dimensional analysis, of the time required for mixing during gas rinsing, and a comparison of the calculated mixing times with the results from production trials shows a satisfactory agreement (with a correlation factor of 0,91). Thus, an equation is available for the calculation of the stirring time needed to completely mix the bath in production situations.

Jan 1, 1981

By Edward A. Vitunac

The emerging importance of pneumatic conveying systems for bulk materials is largely due to the economic advantages such systems frequently exhibit when compared to alternate methods. Included in these advantages are relative simplicity, ease of installation, flexibility, ease of maintenance, cleanliness, safety and ease of automation to the degree desired. In general, installed costs favor a pneumatic system when compared to competing mechanical systems if the transporting distances are long or to and from many points. In addition, supplemental use such as cooling, heating, or drying may supply the incremental value required to justify its selection.1 The main disadvantages of a pneumatic system are the greater horsepower required per unit weight of material conveyed, material limits in abrasiveness, and density. In addition, material breakage tends to increase at changes of direction and at any obstruction such as that caused by the imperfect butting of two pipe sections in the conveying line. Classification of the material at the discharge may also cause problems in dusting and segregation. Materials weighing less than 4 lb per cu ft tend to cause feeding and collecting problems although they can be conveyed easily. Material between 4 lb and 20 lb per cu ft can be handled with fewer problems, but flow rate is hard to predict. The 20-60 lb per cu ft range offers best results, whereas materials of over 60 Ib per cu ft tend to drop out of the air stream and settle in the pipeline unless careful pro- visions are made to prevent this.2

Jan 5, 1968

By F. Kongoli

A computerized thermophysicochemical database is being developed for various processes involved in nickel smelting and converting. This database includes optimized models for slag, matte, liquid and solid alloys in the multicomponent system(s) as applied to batch and continuous nickel smelting and converting processes. This database can be used to quantify the multicomponent and multiphase slag/matte/alloy/gas equilibria, liquidus and solidus surface, tie-lines, solubility and/or losses of nickel and other components in the slag, distribution coefficients, components activities, heat and mass balance, etc. The database also includes optimized models for the viscosity of the slags associated with any of the above processes. Both databases are coupled and this constitutes a very effective method to quantify the effect of each component on several parameters of the smelting and converting processes and to diffuse the confusion that exists in the literature. Several application examples have been given to demonstrate the usefulness of this database for quantitative prediction of the thermophysicochemical properties of the phases involved in actual or developing processes, even in the areas where experiments are difficult or impossible. The considerable cost reduction that results ftom the use of this database as compared to other methods in the improvement of existing technologies or in the development of new ones is discussed along with continuing new developments of this database.

Jan 1, 2002

By D. D. Pollock

The resistivity, temperature coefficient of resistance, and absolute thermoelectric properties of some binary terminal solid solutions of silver were determined. Equations are given which permit the calculation of these properties. CONSIDERABLE work has been done on the constitution and electrical conductivity of binary alloys of silver.1-l2 Some of these alloy studies are apparently complicated by doubtful chemical analyses. In some cases the limits of solid solubility are questionable. Those references which present electrical properties of binary silver alloys usually give just one particular set of characteristics such as conductivity (or resistivity). As a means of checking and extending this earlier work, an investigation was undertaken to describe and calculate the resistivity, temperature coefficient of resistance, and thermoelectric power of binary terminal solid solutions of silver. PREPARATION OF ALLOYS All of the alloys were made with silver containing less than 0.014 pet (by weight) of impurities. These materials were carefully weighed out into 225-g heats and melted in a high-frequency induction furnace. The indium, tin, and antimony systems were melted in Al2O3 crucibles, under a boric anhydride cover, and poured into split graphite finger molds. The aluminum, germanium, arsenic, lead, and bismuth alloys were melted in machined graphite crucibles, and they were also covered with boric anhydride and poured into split graphite finger molds. The alloys containing magnesium and manganese

Jan 1, 1964

By E. M. Wise

MANY of the platinum metal alloys are hot-forged in the early stages of reduction from ingot and substantial quantities of platinum alloys are commercially employed at very high temperatures in ammonia oxidation units, orifices for forming glass rods and fibers and as cathodes in long-life thermionic amplifiers. They are used also for electrical heating resistors, safety blowout disks, thermocouples and crucibles. The tensile prop-erties at elevated temperatures are important in many of these situations but data on the subject are limited. Creep data also are important, but will not be covered at this time. SCOPE AND CONCLUSIONS Tensile tests were carried out at room temperature and elevated temperatures up to 1100° C. on previously well annealed samples of platinum, palladium and several of their important alloys with composi-tions shown in Table 1. The results are presented graphically in Figs. 1 to 4. The tensile strengths of platinum and the platinum-base alloys (with the exception of the 10 per cent rhodium-platinum alloy) at 1100° C. are from 16.6 to 18.8 per cent of the strengths of the same alloys (well annealed) at room temperature. The strength ratio of the 10 per cent rhodium-platinum alloy is 22.3 per cent, which is appreciably higher than that of the other materials tested.

Jan 1, 1938

By J. J. Egan

ADVANCES in the production of quality steel have emphasized the need for greater knowledge of the amount and distribution of oxygen in the steel. Control of inclusion content and quality is largely dependent on such knowledge. While many analytical methods have been de-vised for the accomplishment of this end, few are without serious limita-tions in accuracy, convenience, or skill required in application. Usually at least two methods are necessary to determine total oxygen and constituent oxides. Because of the great importance of this problem and the specific interest in the application of such methods of analysis, the various procedures were carefully reviewed at the Union Carbide and Carbon Research Laboratories, with the view of developing a method free from the limitations mentioned above. Intensive experimentation finally led to an improved iodine extraction analysis described by Cunningham and Price. I After this had been thoroughly checked from the standpoint of the analytical chemist, it was rechecked from that of the metallurgist. This involved preparation of a number of small heats of varying composition with determination of total oxygen in the molten metal by the alumina method2 and an analysis of the solidified material without the aluminum addition by means of iodine extraction; the oxides of iron, manganese, silicon and aluminum also being determined by the iodine analysis. The report of this work constitutes the subject of this paper.

Jan 1, 1933

By John A. Shuster

INTRODUCTION Controlled ground freezing for mining and construction applications has been in use for over a century. Despite the great technological evolution which has occurred during this period, ground freezing is still used on projects today with much the same basic technology as that used originally over 100 years ago. Major developments have occurred in the separate fields of frozen soil mechanics, refrigeration, and heat transfer analysis. However, except for a few projects in Europe and Asia, these developments have not been combined to upgrade ground freezing techniques to their potential level. In view of this situation, it is believed desirable to examine the art of ground freezing in light of recent technical developments, together with highlights on some of the apparent advantages, disadvantages and economics of the various alternative approaches. The purpose of this paper is to attempt such an examination, with particular emphasis on the practical application of presently available technology. GENERAL ADVANTAGES AND DISADVANTAGES Ground freezing may be used in any soil or rock formation, regardless of structure, grain size or permeability; however, it is best suited to soft ground rather than rock conditions. Freezing may be used for any size, shape or depth of excavation and the same physical plant can be used from job to job despite wide variation in these factors.

Jan 1, 1997

By Henry Howe

(New York Meeting, October, 1913.) The Equilibrium. Position of A 1.-Some of the most important data on this subject are collected in Table I. Definition of Ae 1-Just as we call A 1 of rising temperature Ac 1, and that of falling temperature Ar 1, so we may give the symbol Ae 1 to the equilibrium position of A 1. Preliminary Assumptions.-In deciding what weight to assign the various data, and indeed what data are to count, three assumptions should be made. These are: 1. The corollary from the phase rule, that the temperature of Ae 1 is constant and independent of the carbon content, though, of course, it may be changed by the presence of other elements. 2. That because neither in heating nor in cooling can the transformation begin before the temperature reaches Ae 1, though it may be delayed by lag till after the temperature has passed beyond Ae 1, therefore Ae 1 should be at or below the observed beginning of Ac 1 and at or above the observed beginning of Ar 1, and, a fortiori, it should be at or below the observed maximum of Ac 1, and at or above the observed maximum of Ar 1. It may be necessary to take these maxima into consideration in view of the experimental difficulty of detecting these beginnings.

Jan 6, 1913

By W. V. Kotlensky, H. E. Martens

In an earlier communication, Ref. 1, the authors presented the tensile properties and the changes in crystal structure and microstructure for pyrolytic graphite tested at 2750°C. It was suggested that changes in the structure may have an effect on the tensile properties of this material. Accordingly, tensile tests were run on a series of specimens, from one block of pyrolytic graphite, some of which were hot-worked by being strained at 2750°C, others of which were tested in the as-deposited condition. According to the manufacturer, General Electric Co., the polycrystalline material was deposited at 2100°C on a substrate of synthetic graphite by decomposition of a dilute natural gas mixture. The as-deposited material had a density of approximately 2.19 g per cc, and as shown in Fig. 1 had a structure of medium size growth cones which were regenera-tively nucleated. All specimens had a gage section 0.75 in. long by 0.06 in. wide by 0.1 in. thick with the thickness direction perpendicular to the basal planes. The testing method and equipment used have been previously described, Ref. 2 and 3. For both the hot-working and the testing the load was applied parallel to the basal planes; a cross-head speed of 1.5 x l04 in, per sec was used. All heating was done in an atmosphere of bottled helium.

Jan 1, 1962

By M. S. Basich, J. S. Scope1, J. H. Raeder

During 1983, The Youghiogheny and Ohio Coal Company's lost-time-incidence rate was 8.1, equal to the average for underground bituminous operators. How- ever, one half of all lost-time injuries were low back, back and neck related. In reviewing these results, we determined that substantial improvement could be made. We investigated existing back schools and the possibility of opening an in-house clinic. In September 1984, we began The Youghiogheny and Ohio Coal Company's Back Care Program. The objectives of the program are to reduce the number of back injuries incurred at the work site, hasten recovery time, decrease medical and workers' compensation costs and provide the employee with a thorough understanding of his problem. A state-of-the-art clinic capable of treating injuries to the spine and extremities has been established at the work site. The clinic is staffed by a licensed physical therapist and is offered to all employees on a voluntary basis under physician referral. The approach to treatment is multi-phasic. For the typical patient, the initial goal is to reduce pain and correct dysfunction. Treatment modalities such as auto-traction, extension exercises, ultra sound and moist heat are frequently used. During this period the patient is given extensive education regarding his problem. As soon as more vigorous activity can be tolerated, a work-hardening pro- gram consisting of job simulation activities designed to improve flexibility, strength and functional capability is begun.

Jan 1, 1986