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By Vittal S. Bhandary, B. D. Cullity

Swaged iron wire has a cylindrical {001} <110> texture. The texture is also cylindrical after re-crystallization in the absence of a magnetic field, but <111> and <112> components are added to this texture when recrystallization occurs in a field. The mecizanical properties in tension and in torsion are not greatly altered by these changes in texture. AS shown in a previous paper,1 cold-worked wires of the two fcc metals copper and aluminum can be made relatively strong in torsion and weak in tension, or vice versa, by proper control of preferred orientation (texture). The deformation texture can be controlled by selection of the starting texture (texture before deformation), because certain initial orientations are stable during deformation. The present paper reports on similar work performed on bcc iron. In this case it was clear at the outset that there was no hope of controlling the deformation texture, which is one in which <110> directions are aligned parallel to the wire axis. (1t has usually been regarded as a fiber texture, but Leber2 has recently shown that it is a cylindrical texture of the type {001} <110>. In either case, <110> directions are parallel to the wire axis.) There is general agreement on this texture among a large number of investigators, which in itself suggests that the starting texture has no influence on the deformation texture. More direct evidence was produced by Barrett and Levenson,3 who reported that iron single crystals of widely varying initial orientations all had a single <110> texture when cold-worked into wire. Thus <110> is a truly stable end orientation for iron and probably for other bcc metals as well. Under these circumstances attention was directed to the possibility of controlling the recrystallization texture. This texture is normally <110> in iron,4 just like the deformation texture. However, it is conceivable that this texture could be modified by a proper choice of the time, the temperature, and what might loosely be called the "environment" of the recrystallization heat treatment. In the present work the environmental factor studied was a magnetic field. The effect of heating in a magnetic field ("magnetic annealing") on recrystallization texture has been investigated by Smoluchowski and Turner.5 They found that a magnetic field produced certain changes in the recrystallization texture of a cold-rolled Fe-Co alloy. The texture of this material is normally a mixture of three components, and the effect of the field was to increase the amount of one component at the expense of the other two. Smoluchowski and Turner concluded that the effect was due to magnetostriction. With the applied field parallel to the rolling direction, the observed effect was an increase in the amount of the texture component which had <110> parallel to the rolling direction. In the Fe-Co alloy they studied, the magnetostriction is low in the <110> direction and high in the <100> direction. Thus nuclei oriented with <110> parallel to the rolling direction will have less strain energy than those with <100> orientations and will therefore be more likely to grow. In a later paper on the same subject, Sawyer and Smoluchowski6 ascribed the effect to magneto-crystalline anisotropy and made no mention of magnetostriction. In the papers of Smoluchowski et al. the intensity of the magnetic field was not reported but it was presumably large, inasmuch as it was produced by an electromagnet. In the second paper6 it is specifically mentioned that the specimens were magnetically saturated. But if magnetostriction has a selective action on the genesis of stable nuclei during recrystallization, that selectivity must depend only on differences in magneto-strictive strains between different crystal orientations and not on the absolute values of those strains. Thus the saturated state does not necessarily produce the greatest selectivity, because the relative difference in magnetostrictive strains between different crystal directions may be larger for partially magnetized crystals than for fully saturated ones.7 In the present work the specimens were subjected to relatively weak fields (0 to 100 oe) produced by solenoids. MATERIALS AND METHODS Armco ingot iron rod (containing 0.02 pct C and 0.19 pct other impurities) was swaged from 0.25 in. in diam. to 0.05 in., a reduction in area of 96 pct. The mechanical properties in tension and torsion were measured as described previously.&apos; Textures were measured quantitatively with chromium or iron radiation and an X-ray diffractometer,8,1 and

Jan 1, 1962

By M Creech

During the 1990s, wider and more productive longwall panels were being introduced into the Newcastle Coalfield. The strata of the Newcastle Coalfield incorporate numerous massive sandstones and conglomerates, some of which formed the immediate roof of the coal seams being mined. The unexpected implications of introducing wider panels into this geological environment included more variable and increased subsidence, severe periodic weighting (with associated mid-face falls) as well as windblast.Subsidence prediction at the time was based on empirically derived data essentially relating subsidence to the width/depth ratio of the panel without accounting for actual widths, nor the impacts of variable geology. This approach required modification as locally derived data was gathered and reinterpreted.The interaction of massive strata located close to the roof of the mined seam resulted in dramatic implications for some of the operations. When associated with longwall goaf geomechanics severe periodic weighting events and crippling mid-face roof falls were the consequence. When associated with narrower panels and shortwall goaf geomechanics, mines in the region experienced aggressive windblast events. The relationships between the overlying massive strata, longwall panel geometry and the various risks encountered during this period is in the author’s opinion, the most concise still documented.As the extensive coalfields of Queensland turn to underground mining operations the relevance of these experiences cannot be underestimated. This paper will discuss recent developments as well as incorporating diverse subjects such as microseismic monitoring, low frequency radio emissions and ‘electrophonics’ as they relate also to the topic.Like Moriarty, massive strata can be disguised and can offend when you least expect. This paper documents a trail of crimes committed by conglomerate in the Newcastle Coalfield that were inflicted on the general public, miners and mining equipment. Although this paper concentrates on the criminal behaviour of conglomerate, this story is also relevant to other massive units such as coarse sandstones that may be more difficult to identify and apprehend. Currently Moriarty remains at large and able to reoffend at any time, once again taking advantage of the unwary.CITATION:Creech, M, 2014. Moriarty was a conglomerate – experiences and implications of coal mining under massive strata in the Newcastle Coalfield, in Proceedings Ninth International Mining Geology Conference 2014 , pp 47–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By James R. Wait

It is the purpose of this paper to review theoretical model concepts in through- the -earth transmission of electromagnetic waves. While the subject is very broad in its defined scope, we will be conscious of the specific applications to mine rescue and emergency telecommunications in coal mine environments. The plan of the paper is to outline previous theoretical efforts without attempting to attach names or organizations to the specific developments. However, we include a guide to the literature as an appendix. Without pretending to be entirely impartial we include a critique of the limitations of the available analytical models. As I see it the central problem is to calculate the steady state mutual impedance of a four-terminal network that is the black box characterizing the through-the-earth path. Problems of secondary importance include the determination of the input impedances of the two pairs of terminals and the associated transient responses. [ ]

Jan 1, 1973

W. C. MATTESON (communication to the Secretary*).-The criticism and question raised by Arthur Knapp regarding the standardization of nomenclature is most important. Faulty rock classification-is generally the result of carelessness or ignorance on the part of the driller. Two remedies might be suggested. In a field where several large companies are operating on an extensive scale, a geologist from each concern might be assigned to superintend the gathering of well-log data and the classification of samples. The geologists from the several operating companies might then combine their data, which would doubtless give valuable information to all interested parties. At present, coordination is not a big factor, unfortunately, but the time will come when conservation will demand such systematic coordination on the part of competing companies. The second remedy lies in instructing and educating the driller to a thorough understanding of the importance of an accurate log and correct classification of the various formations. The writer does not agree with the statement that "90 per cent. of the logs as taken today are absolutely worthless to any one but the one who has taken the log." While mistakes in nomenclature often occur, the driller is generally able to classify the important water-, oil-, and gas-bearing formations with a fair degree of accuracy. Such information is often sufficient to permit accurate correlation and also constitutes valuable data for projection purposes. It must be borne in mind that to attempt to use well-log data in a strict scientific sense of accuracy is impracticable and impossible. A broad interpretation and a comprehensive knowledge of the practical limits of such&apos; information are essential in applying it successfully. Even experienced geologists do not always agree on rock classification. The question as to what constitutes correct nomenclature should receive the earnest and immediate attention of geologists, operators, and producers. Although standard textbooks on geology give correct definitions and descriptions of the general rock species, such textbooks fail to develop the subject in sufficient detail for the work under consideration. A committee composed of appointed members from the American Institute of Mining Engineers, the Geological Society of America, and the

Jan 6, 1917

By Bernard E. Weichman

The oil shales of the Green River formation were deposited in an inland lake which contained abundant plant and animal life. A high percentage of sodium bicarbonate existed in the lower water layers. Digestion of the kerogen-rich mud accumulating on the lake floor lowered the pH of the interstitial waters and precipitated the sodium minerals dawsonite and nahcolite in the kerogen-rich mud. After about five million years of existence, uplift of land areas around the lake caused an influx of clastic sediments which filled up the lake. Continued tectionics gently folded the basin and caused fracturing of the kerogen-lean oil shale. Nahcolite existing in the fractured lean oil shale was dissolved by subsurface waters leaving a tremendous aquifer in a portion of the oil shale. The extent and porosity of the "Leached zone" aquifer is dependent upon the percent of kerogen and nahcolite originally deposited in the oil shale.

Jan 1, 1975

By P. K. Foster, C. M. Payne, A. McNabb

Some measurements of the rate of loss of hydrogen from cylinders of iron and steel are analyzed in terrns of a trapping theory. The apeement is encozcraging and gives rise to estimates for the density of traps in the metal. Furthermore, the results appear to be consistent with the assumption that the diffusion constant D for the steady flux of hydrogen through iron lies on the extrapolation of the linear curve (log D us 1/T) obtained at higher temperatures. IT has been shown in a previous paper1 that the literature relating to hydrogen diffusion in steels contains sufficient evidence to invalidate the application of Fick&apos;s laws to hydrogen diffusion in steel at low temperatures. To account for the deviations from simple diffusion behavior a trapping theory was developed, and the fundamental laws modified accordingly. In the present paper, new data on the evolution of hydrogen from long cylinders are presented, and together with some published data are examined in terms of the requirements of the theory.&apos; Properties of solutions of the basic equations derived previously1 and appropriate to the present experimental conditions are outlined in the first section as they determine the form in which the experimental data must be presented for a comparison of theory and experiment. Two new solutions not previously reported have been derived as described in the Appendix. The experiments and treatment of data are then given in Sections 2 and 3 and the results are discussed in Section 4. 1) THEORETICAL CONSIDERATIONS The hydrogen-diffusion theory1 applied in this paper postulated that lattice-dissolved hydrogen at a concentration C diffuses randomly in accordance with Fick&apos;s first law, but that the lattice contains a uniform density N of traps which can capture and delay hydrogen atoms. kC atoms are trapped per second in a region containing unit concentration of vacant traps while p are released per second in a region containing unit concentration of occupied traps. On this basis it was shown (Eq. [30] of Ref. 1) that, when local changes in the lattice-dissolved concentration C are slow enough for equilibrium to be established with the traps, the system is represented in dimensionless form by the equation:

Jan 1, 1965

By G. Merrington, B. J. Alloway

Tailings from three historical mining areas in the UK were leached in columns under a simulated weathering programme which was chosen to represent periods of 1 and 2 years at 3 different ambient temperatures. The total concentrations of Cd, Cu, Pb and Zn in the primary ore minerals present in the tailings showed only a limited correlation with metal concentrations in the leachate. The leachate from columns of tailings that were maintained at a temperature of 25 (+/-3) degrees C contained, on average, 50% more Pb and 75% more Cu than leachate from tailings that were maintained at a temperature of 10 (+/-3) degrees C. The pH values of leachates from all three types of tailings at 25 (+/-3) degrees C were 0.2 units lower than those from columns maintained at 10 (+/-3) degrees C. The concentration of Cd and Zn in the tailings leachates showed no marked difference at the different temperatures. The composition of the leachate was found to be dependent on the type of gangue mineral, the presence of other sulphide minerals and the formation of secondary iron minerals. A comparison of the concentrations of heavy metals in the leachates produced in the laboratory with those in leachates that were collected in the field over a similar period of time from two of the mine sites showed that concentrations were of a similar order.

Jan 8, 1993

By Florence Ntsiful, Eric Stemn

Exposure to whole-body vibration has been recognised as an occupational hazard in the mining industry, especially in the operations of earthmoving equipment. Managing whole-body vibration exposures requires periodic measurement of exposure levels to identify priority areas for implementing controls. However, due to different approaches to collecting exposure values, significant variabilities lie in the results. This systematic review is the first attempt to analyse whole-body assessment methods in the mining industry. The aim was to identify how whole-body vibration has been assessed, including the sources of variabilities to improve future research. The PRISMA methodology was adopted for the review and a total of 152 peer-reviewed journal articles were identified. However, only 24 were included in the review, following the application of some inclusion criteria. Descriptive and thematic analyses were performed on the 24 selected articles. Results indicate that whole-body vibration has been assessed as a function of either equipment characteristics, activity undertaken, operator characteristics, measurement approach or the assessment standards. Due to the multifactorial and dynamic nature of wholebody vibration exposures, the variabilities in results are due to the interrelationships between the risk factors of whole-body vibration and the differences in the sample sizes. To identify the sources of variabilities, a comprehensive assessment of all the risk factors, including equipment characteristics, road conditions, operator characteristics, and activity undertaken, is highly warranted. Finally, research gaps and directions for future research have also been discussed.

Dec 21, 2022

By Newell R

The situation in which a gas stream flows through a bed of solids is found in many extractive metallurgy operations. Examples include blast furnace smelting, sintering and pellet firing. In such cases the resistance of the bed to fluid flow and heat transfer is of major significance to the operation of the process. This depends on the structure of the bed, which in turn is influenced by the manner in which the materials are charged to the bed. In this work, packed beds of hematite pellets of two different sizes were prepared in which the pellets were charged as a uniform mixture and in layers. The porosity, flow resistance and heat front velocity were measured and compared for the different bed configurations. For layered beds, the overall porosity and heat front velocity increased while the flow resistance decreased when compared with the values obtained for the uniform mixture. The size of the layers also had an effect on flow Properties.

Jan 1, 1991

The U.S. Bureau of Mines, Department of Labor, and United States National Committee of the CIE hosted the TC4.10 Mine Lighting Committee Meeting and Second International CIE Mine Lighting conference at the MSHA Academy in Beckley, WV from October 12-16, 1981. This was the first time the meeting and conference had been held in the United States. The TC4.10 Mine Lighting Committee, chaired by Dr. Adam Peretiatkowicz of Poland, was attended by 15 committee members and six guests representing eight countries. Discussion during the meeting covered mine lighting instrumentation, open cast (surface mine) lighting, and lighting sources. The committee also reviewed a draft of proposed lighting terminology and suggested changes to make the definitions more acceptable to representatives of the nations present. The mine-lighting conference featured 20 papers presented by 18 speakers representing six countries. The papers covered all phases of mine lighting, including research, hardware development and application, personnel acceptance, and requirements for system maintenance. The conference attracted 126 attendees and also included displays by eight lighting hardware manufacturers and four mining machine manufacturers. Papers from the conference are being published by the Government Printing office, with copies presented to the conference attendees. Copies will be available to others interested through the NTIS. During the course of the TC4.10 meetings and conference, committee members toured three mining equipment assembly plants, and six of the foreign representatives visited a longwall installation in an underground mine. Planning and administrative services for the meeting and conference were handled by Bituminous Coal Research, Inc., under USBM Contract H0318038.

Jan 1, 1982

By Robert A. Rapp, Ronald L. Pastorek

Solid-state electrochemical measurements by three alternative experimental procedures were made with the cell FeO, Fe3O4 |Zro.85Cao.15O1.85 |Cu| Zr0.85CaO.15O1.85 | FeO, Fe304 to establish the solubility and diffusivity of oxygen in solid copper in the temperature range 800" to 1030°C. The solubility of oxygen in solid copper and the diflusivity of oxygen in solid copper Dgu = 1.7 X 10-2 exp(-16,000/RT) Cm2/sec were determined and confirmed in alternative experiments. The enthalpy of solution of oxygen in solid copper equals —10,000 cal per mole; the partial excess entropy of the oxygen atoms in the Cu-O dilute solution is approximately the same as that found for interstitial atoms in other metals. The diffusivity of oxygen in solid copper is consistent with that expected for an interstitial atom. RELIABLE values for the saturation solubility N(s) and diffusivity DO of oxygen in solid copper have not been unambiguously established in the literature. Following three early determinations by others,1"3 Rhines and Mathewson4 reported that the solubility of oxygen in solid copper increased from 0.007 at. pct 0 at 600°C to about 0.015 pct at 1050°C. Phillips and skinner,, using essentiially the same analytical procedure, reported that the solid solubility increases from 0.0018 at. pct 0 at 550°C to about 0.0075 pct at 1050OC. The only previous value for the diffusivity of oxygen in solid copper was reported by Ransley.6 Ransley deoxidized Cu-Cu2O alloys in an atmosphere of carbon monoxide gas to yield a solubility-diffusivity product. He used the solubility data of Rhines and Mathewson to calculate the diffusivity values. Another method for obtaining the solubility-diffusivity product (N(s) DO) is by measuring the widths of internal-oxidation zones in copper alloys as reported by Verfurth and Rapp.7 However, the calculated N(S)Do products depend upon the alloy content of the specimen, so that the internal oxidation of copper alloys does not follow ideal internal oxidation kinetics. As a result, unequivocal values for the N(s) DO product were not obtained by this procedure. A solid-state coulometric titration technique similar to that employed in this work was introduced by C. Wagner8 to study the dependence on silver activity of the Ag/S ratio in silver sulfide in the temperature range of 160" to 300°C. Similar experiments have been carried out by C. Wagner and co-workers9-11 to study the stoichiometry range of silver and copper tellurides, cuprous sulfide, and cuprous selenide. Numerous authors have carried out electrochemical measurements with a solid oxygen-ion-conducting electrolyte to determine the solubility and/or diffusivity of dissolved oxygen in several liquid metals.12-l6 Rickert and Steiner17,18 have used solid-state electrochemical measurements to determine the diffusivity of oxygen in solid silver from 760" to 900°C. Two different cell geometries were used. In the cell of linear geometry Fe, FeO | ZrO2 + (CaO) | Ag + [0 (dissolved)] [1] oxygen diffused from the interior of the silver electrode to the silver/electrolyte interface where the oxygen activity had been lowered from a fixed initial value to practically zero by the application of voltage to the cell. The diffusivity of oxygen in solid silver was determined from the solution of the diffusion equation and the time dependence of the cell current. However, this determination of the diffusion coefficient depended upon a knowledge of the solubility of oxygen in solid silver. A cylindrical geometry was used for the cell Pt, O2(Po2 = 0.21 atm) | ZrO2 + (CaO) | Ag + [0 (dissolved)] [II] which also allowed the diffusivity of oxygen in solid silver to be determined. These values were in agreement with other available data.l9 Recently, Raleigh20,21 used a method involving the measurement of diffusion-limited currents in a cell involving the AgBr solid electrolyte to determine the diffusion coefficient of silver in Ag-Au alloys at 400°C. Diffusivity values on the order of l0-14 sq cm per sec were measured in the alloy composition range 10 to 60 at. pct Ag in a single experiment. From numerous electrical conductivity and galvanic cell measurements,9&apos;22"26 the solid solution Zr0.85 Ca0.15 O1.85 has been established as an electrolyte with predominant oxygen ion conduction over a wide range of intermediate and high oxygen activities. For interrelating the thermodynamics and the kinetics of the dissolution of oxygen in solid copper in this investigation, a galvanic cell was constructed with FeO-Fe3O4 as the reversible reference electrode, the Zr0.85Ca0.15 O1.85 electrolyte, and a pure copper specimen under-saturated in oxygen as the other electrode. THEORETICAL ANALYSIS Three variations of a high-temperature electrochemical technique were used in this study to provide two determinations each of the solubility and diffusivity

Jan 1, 1970

By K. Lomberg

In this paper the process of sampling and assaying as it relates in particular to the platinum group elements (PGEs) is presented. A discussion of the geology of PGE deposits is included to provide an understanding of the mineralization that is considered necessary prior to sampling, as this has a direct bearing on the mineral resource estimate and also the selection of an appropriate mining cut. The discussion includes the selection of the sampling technique (drilling or face sampling), the size of the sample relating to the requirements of the laboratory, the potential mining cut, as well as a reference to sampling theory. The selection of an assay technique that is appropriate and will yield the optimal result based on sample turnaround, precision, accuracy, and cost is then considered. Examples are drawn from work undertaken on the Bushveld Complex (Merensky Reef, UG2 Chromitite Layer, Platreef) and Great Dyke (Main Sulphide Zone). A discussion of the appropriate QA/QC programme includes the chain of custody, CRM selection and the QA/QC process. Keywords sampling, assaying, QA/QC, platinum group elements.

Jan 1, 2014

By H. Dong, J. J. Valencia, L. Nastac

"A comprehensive computer model was developed to understand and optimize the centrifugal casting process for manufacturing TiC/Al-bronze friction drums. Performance of these components requires proper distribution of TiC particles, which is shown by dimensional analysis to be dominated by centrifugal buoyancy effects and solidification kinetics.The model addresses the following: (1) a rheology-viscosity model of the interference between moving particles, (2) engulfment (entrapment) or pushing of particles in the mushy region by the advancing solid/liquid interface, (3) nucleation and growth of equiaxed and eutectic phases, (4) effects of particle size, particle concentration, and cooling rate on the final grain size, and (5) the impingement effect of particles on the nucleation and growth kinetics of solidifying microstructure.Parametric studies were conducted using the computer model to investigate the effects of various process and material parameters on the distribution of TiC particles. The effects of the volume fraction, size, and morphology of the particles (including clusters and agglomerates) on the particle distribution were evaluated in detail. The complex interaction between the solidifying structure and insoluble ceramic particles in centrifugally-cast metal-matrix-composites was also investigated.The model predictions of particle distribution and microstructure were validated with experimental data for centrifugally-cast A356/SiC and TiC/Al-bronze alloys.This work was conducted by the National Center for Excellence in Metalworking Technology, operated by Concurrent Technologies Corporation under contract No. N00140-92- C-BC49 to the U.S. Navy as part of the U.S. Navy Manufacturing Technology Program."

Jan 1, 2000

By C. H. Li, S. H. Bendel, J. A. Sartell

Small additions of Mg to a 62 Cu-38 Ni alloy reduce the oxidation yates drastically between 500° and 850°C. Metallographic examination of the oxide scale disclosed a continuous network, identified by X-ray diffraction as (Ni, Mg)O solid solutions, located along the former alloy grain boundaries. This network acts as a barrier to diffusion. It is thought to result from the segregation of mg to the alloy grain boundaries. Oxidation occurs preferentially in these regions because of the presence of this more active element. To substantiate these ideas, homogenized alloys ulere oxidized. No oxide network was produced and oxidation rates were the same as for the parent 62 Cu-38 Ni alloy. An interesting aspect of the oxidation of the 62 Cu-38 Ni alloy previously described by the present authors, is the relationship between oxidation kinetics and changes in the microstructure of the oxide.&apos; The oxide scale on these alloys consists of two layers: a thin layer of CuO outside a much thicker layer of Cu20 in which particles of NiO are dispersed. In addition, immediately beneath the oxide-metal interface there is an internally oxidized zone in which NiO particles are dispersed in a copper-rich alloy matrix. Experimental observations on the growth of the individual layers under isothermal conditions have led to the conclusion that the rate-determining step in the oxidation of this alloy is the diffusion of anions through the Cu20 layer. It has been found that this diffusion rate is increased by the recrystallization of the outer CuO layer. Willardson and Gorton have reported that the addition of magnesium to the 62 Cu-38 Ni alloy causes a decrease in the oxidation rate.2 The present investigation was undertaken in order to determine the mechanism by which magnesium additions improve the oxidation resistance of the 62 Cu-38 Ni alloy. EXPERIMENTAL PROCEDURE Fifty-gram ingots of Cu-Ni alloys were prepared by vacuum melting materials of 99.999+ pct purity. These ingots were then remelted in a He atmos- phere and magnesium added in the form of a previously prepared and analyzed Cu-Mg master alloy. This procedure was necessitated by the high reactivity of pure magnesium at high temperatures. The proportion of the alloying elements was adjusted so as to obtain alloys with the desired magnesium content while maintaining a Cu-Ni ratio of 62 :38 by weight. (All alloy compositions will be given in weight percent.) Since it was considered desirable to study the oxidation of only single-phase, solid-solution alloys, it was necessary first to determine the approximate limit of solid solubility of magnesium in the 62 Cu-38 Ni alloy. A series of melts with various magnesium contents was made, homogenized by annealing for 48 hr at 975OC, then cooled in the furnace. Metallographic samples were prepared, etched in a potassium dichromate solution and examined at XI500 for the presence of a second phase. The alloys were then chemically analyzed and it was found that the approximate limit of solid solubility of magnesium in the 62 Cu-38 Ni alloy was 1 pct Mg. The ingots containing less than 1 pct Mg (0.19, 0.29, 0.58, and 0.87 pct Mg) were cold-rolled down to thicknesses suitable for oxidation experiments and specimens for gravimetric studies were cut to dimensions of 3.0 by 1.5 by 0.05 cm, specimens for inert marker studies, 0.6 by 0.6 by 0.17 cm. These were heat-treated in a protective atmosphere at a temperature (975" C) well above the oxidation temperatures and furnace-cooled to insure structural stability of the alloy during oxidation. Immediately prior to oxidation, the specimens were chemically cleaned by immersion for 1 min in a solution of 2 parts nitric acid, 1 part acetic

Jan 1, 1961

By J Foster

The Lanfranchi Nickel mine is located approximately 48 km south of Kambalda in Western Australia. Mining first commenced in the mid-1970s under the previous owner, Western Mining Corporation Ltd. After two years on care and maintenance, Panoramic Resources (previously known as Sally Malay Mining Ltd) purchased the operation in November 2004. The site currently produces approximately 10?000 tonnes of nickel metal annually from approximately 430?000 tonnes of ore. The Ore is mined from four main orebodies; Deacon, Helmut South, Lanfranchi and Schmitz. The Helmut South orebody is situated approximately 790 m below surface and extends to a resource depth of 940 m. Horizontal thickness of the orebody ranges from 10 m to 45 m in width, with the average being 30 m. Previous mining at the Lanfranchi operations specifically the Helmut orebody, had a history of seismic activity. When Panoramic Resources acquired the operation it was decided that seismicity was going to be an issue and therefore a mining method needed to be selected that could effectively manage this potential risk. The dip of the orebody is quite shallow at 45º, with a 30º plunge to the south . The hanging-wall comprises of very weak ultramafics. Due to these factors the orebody posed several mining challenges. To safely and effectively mine the Helmut South orebody in the Lanfranchi Nickel mine, underhand cut and fill mining was selected as the most appropriate mining method. Paste fill comprising of cemented gold tailings was the backfill of choice. This paper is intended to convey some of the key learnings from the use of a mining method that has not been commonly practiced in Australia.

Mar 21, 2011

By Morrison AL

The volume changes occurring during the reduction by hydrogen of single, high-grade hematite pellets under isothermal and non- isothermal conditions were investigated using a time-lapse photographic technique. The major cause of swelling during iso- thermal reduction at temperatures in the range 600-1000¦C, was the disruptive stresses set up during the transformation of hematite to mag- netite. The severity of the disruption was temperature dependent; the degree of swelling increased with increases in the reduction temp erature. Under non-isothermal reduction conditions, in which the pellet temperatures were increased at constant heating rates over the temperature range 500-1000¦C, minor swelling (6-8%) occurred in the initial stages of reduction followed by pellet contractions of up to 15% in the final reduction stages. The low initial swelling and high final pellet shrinkages were due to a com- bination of the temperature dependence of the swelling mechanism, and the sintering of fine pores in the reduced iron in the latter stages of reduction at higher temperatures.

Jan 1, 1980

By J. W. Paul

Mine foremen are employed in coal mines for two reasons: First, so that the underground work. may proceed in an orderly manner and that each employee gives attention to his duties; and second, by reason of the State law which re- quires the employment of such officials to see that the laws relating to safety are carried out. It may be seen that, with these two duties, the foreman has wide scope of authority and much responsibility. As foreman of operations he has to meet certain economic questions that contribute to the cost of producing the coal, and as the agent of the State he must also supervise and coordinate the work in such manner as to insure that the employees work under safe conditions. As the roof of coal mines is the source of the greatest hazard naturally the care of the roof must take much thought and planning on the part of the fore- man; and this circular is therefore presented to call attention to some things he may do to prevent injury to the workmen by falls of the roof material or coal. Mine foremen, in the principal coal-producing States, are certified by a State board which prescribes certain qualifications, experience, and character, attested by examination and personal endorsement. Certified foremen, therefore, are men who have had experience underground and know roof conditions and timber- ing methods. The suggestions herein are based upon observations made at many mines and collectively embrace practices that have been found to be in effect and pro- moted by experienced mine foremen:

Sep 1, 1930

By E. L. Rawlins

A previous report4 has explained that pipe lines for the transmission of natural gas should be buried to minimize temperature fluctuations because when excessive the latter decrease accuracy in measuring gas volume and increase leakage of gas due to expansion and contraction in the pipe joints. These effects are governed by the rapidity of the temperature fluctuations and by the total variation over a period of time. The temperature of gas flowing through a pipe line depends to a large extent, upon the temperature of the ground adjacent to the pipe; hence, fluctuation of the ground temperatures at various depths determines the economic depth at which pipe lines should be buried. Scope and Purpose of Report This report covers a record of the daily atmospheric temperature fluctuations at Bartlesville, Okla., for 12 months and a-similar concurrent record of the temperature variation 1, 2, 3, and 4 feet below the surface of the ground.

Jan 1, 1928

By Dennis Dolinar

In this National Institute for Occupational Safety and Health (NIOSH) investigation, numerical modeling is used to evaluate the degree the pillar strength is increased with a rectangular pillar over a square pillar. Three-dimensional models are developed with pillar sizes and geometries typical of underground limestone mines in the United States. Physical properties for the models are based on geotechnical surveys of nearly 30 underground limestone mines. To examine the effects of pillar length on pillar strength with the modeling, a parametric study was conducted where the pillar width was held constant while the length and height were varied resulting in width-to-height ratios ranging from 0.5 to 1.5 and width to length ratios ranging from 1 to 6. There are two aspects to pillar strength and failure. At relatively low stresses, pillars can fail as a result of geologic structure. At greater depths and sufficient extraction ratios, the pillars can also fail as a result of the vertical stresses exceeding the pillar strength. The effects of increasing pillar length regarding both strength aspects are presented in this study. Equations were developed for the increase in pillar strength with both height and length based on the model results. The results from these equations were compared to those from previously developed empirical equations for rectangular pillars. For the more slender limestone pillars with a width-to-height ratio below one, there is little increase in pillar strength for length-to-width ratios above 2 and almost no increase with length for a width-to-height ratio of 0.5. Only with the more squat pillars is there a significant improvement in strength with length. The gain in pillar strength with length for the pillars is explained by the change in the ratio of the area of the pillar affected by the ends to the area of the pillar. For the squattest pillar, the change in strength is also affected by an increase in pillar confinement along the central length of the pillar as the pillar transitions from a square to a long rectangular pillar. With geologic structure, added pillar length can significantly improve the pillar strength, depending on the strike of that structure with respect to the long pillar axis.

Jan 1, 2007

By Zhang Libo, Peng Jinhui, Zhang Zhengfu, Fu Mengbi, Han Yamei

In this paper, results of a novel synthesis method of carbon-coated LiNi113Mn113Co11302 cathode material for lithium-ion battery are reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The structure, morphology and electrochemical performance of the bare and carbon-coated LiNi113Mn113Co11302 were characterized by X-ray diffraction, scanning electron microscopy and charge-discharge tests respectively. The L8(27) orthogonal experiments were carried out to optimize LiNi113Co113Mn1130z/C technological conditions. The conditions of the orthogonal experiments were that the glucose content were 1.5 % and 4 %, the holding time were 15min and 30min, the heating temperature were 400 °C and 500 °C and the solvent were H20 and CH3CH20H. The main experiment target include specific capacity at 0.1C and 0.2C, Capacity retention rate, medium voltage attenuation rate and The fifth discharge medium voltage. The data were analyzed by Minitab 14 statistics software. The results of analysis of variance indicated that the most influential factor was the glucose content despite of discharge rate. Secondly, the effect of the solvent was equivalent to the holding time.

Jan 1, 2013