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By J-M Rendu

Substantial progress has been made over the last ten years in the development of uniform national and international standards covering the definition, estimation and public reporting of mineral resources and mineral reserves. Agreement between the major participating countries has been reached, which includes the requirement that a Competent Person prepare and approve publication of mineral resources and reserves. Most national regulatory organisations have accepted the new standards and have included them in the rules that must be followed by mining companies operating under their jurisdiction. These developments are the result of a concerted effort on the part of professional societies, national regulatory agencies, international organisations, and many dedicated individuals. The historical development of these standards is summarised in this paper. Accepted definitions of mineral resources and mineral reserves are discussed, as well as the definition and role of the Competent Person. Additional effort is needed before the international standards are fully understood, accepted and followed by mining companies, regulatory agencies, the investment community and the general public. Steps being taken toward development of an International Code are outlined.

Jan 1, 2002

By N. C. Joughin

Potential for the mechanization of stoping in gold mines by N. C. JOUGHIN B.Sc. Eng., Ph.D. (Rand) (Member) The basic requirements for stoping machines are identified first by examination of the mining rates and productivities attained in conventional stoping, and then by examination of a series of problem areas associated with the shape of the reefs, rockbreaking, rockhandling, and the support and design of the machines. Some of the more important machines being developed are described briefly, and their principal features are compared with the basic requirements identified in the first part of the paper. An estimate of the potential demand for the different types of machines is given.

Jan 1, 1976

By R Witt, M Lowing

Tanking of tunnels is now often specified when inflows exceed as little as 1 L/s/km with a unit distance of 100 m. To demonstrate inflows over a 100 m segment of a tunnel are less than 0.1 L/s with a standard error of 0.01 L/s by timed, gravity filled, volume measurement up and downstream of the segment, the measuring cylinder volume (L) must exceed 10 Q, where Q is the flow in L/s, and the number measurements taken and averaged must exceed 20 . If a standard error of 0.02 L/s is acceptable then 5Q2 measurements must be taken and averaged. If gravity filling is not possible then the number, n, of repeat pumped container measurement required is given by: where: is the 100 m section leakage is the volume filling time is the standard error of volume measurementZ is the standard normal variateK is a coefficient dependent on physical measurement conditions Based on analysis of field data an indicative coefficient of variation of volume measurement is ~0.05.

Jan 1, 2008

By C. G. Dunn, J. L. Walter

The c/laracterzstics of cube-oriented nuclei ard other matrix grains that are associated with secondary, recrystallization to the cube texture in high-purity silicon iron were investigated by me-tallographic and X-ray methods. The results show that the structure consists of relatively perfect grains of average diameter between one and two times the sheet thickness ad that the texture has a moderately strong (110) [001] component and a weak (100) [001] component. The results also indicate that matrix stability results from the two-dimensional nuture of the graitzs and that cube-orzented nuclei are neither more Perfect nor larger grains than other matrix grains but have a preferred [001] direction in the rolling direction and have a more effective driving force for growth than other grains because of a low (100) surface energy. THE structures and textures of fine-grained rnatrices determine to a large extent the kinds of secondary recrystallization textures that form on annealing. The understanding of secondary recrystallization processes therefore depends on adequate information about the initial matrices. Matrices usually have three characteristics: 1) they consist of fine-grained primary recrystallization structures, 2) the fine-grained structures are stable toward normal grain growth, and 3) they contain secondary recrystallization nuclei. Stability toward normal grain growth may be due to either a strong single orientation texture (texture inhibition)' or a dispersed second phase (dispersed phase inhibition).2"4 If normal grain growth is not inhibited by either of these two factors, it nevertheless stops when the average grain size is between one and two times the sheet thick- ness.5 This thickness effect satisfies one of the characteristics of a matrix for secondary recrystallization. Its importance in the development of the cube texture in high-purity silicon iron by secondary recrystallization was pointed out by the authors in a recent paper on tertiary recrystallization7 and will be discussed further in the present paper. Assmus, Detert, and he8 have provided some information on a matrix for secondary recrystallization to the cube texture in silicon iron. They found a (110)[001] or Goss texture with enough spread about the rolling direction to include a small amount of the (100)[00l] orientation. The distribution of the [00l] directions was strongest parallel to the rolling direction for both (100) primaries and cube secondaries. These authors found no correlation between size of a matrix grain and orientation and concluded that some property other than size must be the distinguishing characteristic of the cube-oriented nucleus. No consideration was given, it

Jan 1, 1961

By P. Ruz

A melt transfer ladle was 3D modeled by means of a mathematical fluid dynamics and heat transfer program. Internal temperature profiles were calculated as a time function for a normal ladle and for a pre-heated refractory lined ladle. It was shown that in a normal ladle the molten metal cools down quickly forming accretions. By using an inner lining there are practically no accretions build up within a typical time of operation. Therefore, by applying a refractory lining to a melt transfer ladle and keeping it at a moderate to high temperature it is possible to reduce cold dope circulation in the smelter.

Jan 1, 1999

By Schebek, J. Warsen

"Data and information from sustainable development (SD) reports can be seen as a promising and easily accessible source for an Life Cycle Assessment (LCA), i.e. for generic Life Cycle Inventory (LCI) data in particular. The reliability and comparability of LCA results crucially depends on the quality of LCI data, that is defined by specific normative requirements. In parallel the GRI (Global Reporting Initiative) provides a set of guidance documents for enhancing the quality, rigor, and utility of SD reporting with specific reporting principles that address similar issues on a company level comparable to LCI data quality requirements on the process level. In order to assess the general suitability of the fundamental reporting principles for LCI data quality purposes selected reports from mining and minerals (M&M) sector are assessed within a detailed analysis."

Jan 1, 2005

Several federal and state agencies have promulgated regulations that require the installation of operator protective structures on mobile equipment used in mining, construction, agriculture and logging industries. These regulations cover many different types of vehicles, from small farm tractors to large rubber-tired front-end loaders, and require structures that help protect the operator from death or injury from vehicle overturns, from falling tree tops and logs, from falling rocks, and from tree limbs in clearing operations. Two general types of vehicle operator protective structures have evolved over the past twenty years. The first of these is the "Roll-Over Protective Structure'' or "ROPS" that is essentially a "roll bar" or "roll cage" that provides a relatively safe area for the vehicle operator if the vehicle should tip over and roll. The second protective structure is the "Falling Object Protective Structure" or "FOPS" that provides overhead protection against falling material. The terms "ROPS" and "FOPS" are often used interchangeably (sometimes inaccurately) with "cabs", “canopies” , "roll bars" , protective structures" and other such descriptive names. In this report, "ROPS" describes the function of the structure; "FOPS" also describes a particular function. Thus a ROPS/FOPS could describe a cab or a canopy that provides both roll-over protection and falling object protection. “MESA” is used as an abbreviation for the Mining Enforcement and Safety Administration; "USBM" is used to abbreviate the U, S. Bureau of Mines.

By Yi Luo

This paper presents some of the results of a research on long-term subsidence over and near the chain pillar systems -the area available to long-term subsidence in longwall operations. Although the long-term subsidence in most longwall operation is insignificant, it does exist in some cases. For the cases where long-term subsidence is significant, it has been found that the development process can be expressed by an exponential decaying function. The stability factor of the chain pillar system and the potential for long-term subsidence are the two important factors that control the magnitude and development characteristics of the long-term subsidence process.

Jan 1, 1999

By James D. Noll, Jon A. Hummer, Shawn E. Vanderslice, Aleksandar D. Bugarski, George H. Jr. Schnakenberg, Steven E. Mischler, Larry D. Patts

The National Institute for Occupational Safety and Health designed and conducted a study in an underground metal mine to assess the effects of selected diesel emissions control technologies on the concentrations of diesel particulate matter and gases in underground mine air. The control technologies studied included diesel particulate filter (DPF) systems, filtration system with disposable filter elements, diesel oxidation catalytic converter, and biodiesel blends. Each technology was tested on a mining vehicle operated in an isolated area of an underground mine supplied with fresh air. These isolated zone tests allowed for the operation of vehicles under conditions and over duty cycles that closely mimic actual duty cycles of production equipment. The DPF systems reduced the elemental carbon (EC) concentrations in mine air between 88% and 99%. The same systems reduced total particulate matter (TPM) concentrations in mine air by approximately 75%. The biodiesel blends B20 and B50 caused a reduction in the EC concentrations of 26% and 48%, respectively. Those blends also reduced TPM concentrations by 9% and 24%, respectively. The use of #1 diesel fuel reduced EC concentration by 13% compared to #2 diesel fuel. An increase in nitrogen dioxide concentration of up to two times was seen when platinum-catalyzed DPF systems were tested.

Jan 5, 2006

By Vadym Drozd, Yongzhou Sun, Shah Najiba, Jiuhua Chen, Andriy Durygin

"Phase transitions of the potential hydrogen storage compound, ammonia borane (NH3.BH3), was investigated using Raman spectroscopy and a diamond anvil cell at high pressures up to 9.5 GPa and low temperatures down to 90K. At room temperature, ammonia borane has three phase transitions in this pressure range. Upon cooling, four new phases were discovered through changes in characteristic Raman spectra. This result provides information about the stability of new bonding characteristics of this potential hydrogen storage material at low temperature and high pressure region.IntroductionDevelopment of hydrogen technology requires the safe, efficient and environmental friendly materials for hydrogen storage and hydrides have attracted much attention as hydrogen storage media. Among chemical hydrides, ammonia borane (BH3NH3) stands out due to its high gravimetric and volumetric hydrogen density ' "". Despite high hydrogen content, this compound is very stable. It releases hydrogen in several steps by thermal decomposition in the temperature range of 100°C to 500°C. Direct thermal decomposition also causes toxic borazine emission. Recent research interests on ammonia borane include destabilizing this compound to lower the dehydrogenation temperature with an enhanced hydrogen release rate using different techniques, e.g. the nanoscaffolds'', ionic liquids"" and acid'"" or transition metal catalysts' ""'. As a molecule of ammonia borane consists of protonic (NH) and hydritic (BH) hydrogens bonded by the polarized dative bond, thermal or catalyzed decomposition requires breaking of N-H and B-H bonding. Still now, the detailed information about the bonding characteristics of ammonia borane is not sufficient to understand details about its phases and structures. The development of methods to enhance hydrogen discharge rate from ammonia borane requires a detailed study about the structural and dynamical properties that control the stability and the intermolecular interactions of this material. This study is motivated to investigate the stability of the existing phases and also to explore the existence of any new phases at different temperatures and pressures which may have enhanced hydrogen release and uptake properties."

Jan 1, 2012

By Richard C. Harris

Substantial economic benefits exist today for fine coal preparation and improved technologies coupled with more stringent air quality standards should increase those benefits in the future. The costs of cleaning can be determined with reasonable certainty with proper consideration given to mining methods, plant feed characteristics, refuse disposal and marketing impact. The benefits cannot be as accurately determined but include impact on generating capacity, plant maintenance, emission standards, slagging, fouling, transportation, and handling. Site specific cleaning offers particular benefits in some situations to tailor the preparation plant facility to boiler characteristics. Improved communications and methodologies need to develop to allow the coal producer and the coal user to clean coal to the degree that results in the lowest overall cost for electrical generation.

Jan 1, 1988

By W. W. Weller

Heat-capacity measurements of sodium dimolybdate (Na2Mo207) and sodium ditungstate (Na2W207) were conducted over the temperature range from 51° to 298° K. The entropies of the two compounds at 298.15° K were calculated from the heat-capacity values and were used, in conjunction with other entropy data, to evaluate the entropies of formation of the compounds from their constituent elements and oxides.

Jan 1, 1963

By Mario Andres Albuja Ribadeneira

El presente trabajo pretende encontrar la ruta para incrementar la productividad y reducir el costo de transformación en una acería eléctrica, mediante el uso de la tecnología disponible en el mercado. El método para alcanzar los resultados se enfocan en una drástica reducción de los tiempos de transformador conectado (power-on), los tiempos de transformador apagado (power-off) asi como la reducción en los consumos de las materias primas e insumos para la fabricación de acero por la ruta del horno eléctrico. La experiencia de Adelca arroja resultados que sobrepasan el 100% de productividad y 30% de reducción en el costo de transformación de la palanquilla. Los resultados obtenidos sin duda alguna servirán de una guía probada para quienes buscan un mejor desempeño en el negocio del acero.

Aug 16, 2017

By G. D. Hobson, I. Mrosovsky

Material balance relationships for expansion-type reservoirs above the bubble point have been discussed in recent years by H. N. Hall and M. F. Hawkins, Jr. The former drew attention to the effects of rock compressibility, and the latter to the effects of the compressibility of any interstitial water. Hawkins derived a general relationship which took note of oil, water and rock compressibilities, and then by assuming first, the absence of interstitial water and secondly, no effects due to interstitial water or rock compressibility, obtained relationships symbolically of the same form as those previously derived directly by Hall. Hawkins defined his terms clearly, and noted an approximation, due to the omission of a term involving the product of two compressibilities, made in reaching his final equation. There is, however, possible ambiguity with regard to Hall's written definition of the oil production term. One interpretation would mean that the produced oil and initial oil-in-place, if both required as stock tank barrels, would be obtained by using different formation volume factors in the conversion in order to satisfy the conditions implicit in Hall's formulae. The other would involve an approximation which, if used, was not stated. In both Hall's and Hawkins' studies the effect of the approximation or inconsistency is very slight. Nevertheless, it may be justifiable to give a somewhat more consistent derivation, since the complexity of the final relationships is not thereby greatly increased. Let the initial pore volume be Vi and the volume after a pressure drop of Ap, V. Then V = V, (1 - ?p . cr), where c, is the rock compressibility expressed as change in pore volume/unit pore volume/unit pressure change, and is defined with the initial pressure as base. Suppose that the interstitial water saturation under the initial conditions is Sw. The total volume of interstitial water under those conditions will be ViSw. If the volume of the water after dropping the pressure by ?p is V., this will be given by Vw = ViSw (1 + ?p.c,w), the compressibility of the water being c, which is ex- pressed using the volume at the initial pressure as base. If Boi is the reservoir volume factor of the crude oil for the initial reservoir conditions, and B. the equivalent factor when the pressure has dropped by ?p, with N the initial amount of oil expressed as stock tank barrels. N.Boi = Vi - V,Sw If n is the amount of oil produced (in terms of stock tank barrels) as a result of the pressure drop ?p, the remaining subsurface volume of oil at the lower pressure will be Bw, and Bc can be related to the compressibi:ity of oil and the pressure drop, and if c, is the compressibility factor based on the initial conditions, The relationship derived by Hawkins was case to a standard at the lower pressure, while a term (Ap) had been dropped, because of its smallness arising from its dependence on the products of two compressibility factors. When there is no interstitial water and rock compressibility can be ignored, Eq. 1 reduces to:

Jan 1, 1957

[ ] DISCUSSION F A LORIA*-The method of testing gun steel for resistance to surface cracking described in this paper was restricted to the examination of small, rod-shaped specimens The writer would like to point out the importance of other factors in producing defects in forged and bored gun tubes which would not be apparent in this investigation because of the nature of )he test Actual section size would accentuate the possibility of internal wall (bore) defects arising from unequal expansion between the internal and external wall surfaces on firing, resulting in internal tearing Checks and tears on the inside walls arise from internal tensions and nonuniformity on cooling, but the internal tearing can be reduced by using alloys of low expansion and of good thermal conductivity so as to reduce the difference between the outer and inner wall surfaces Also, the possibility of the location of inclusion segregates within a machined gun tube becomes more likely than in a small test specimen The effect of these nonmetallics on gun life and performance is evident when one realizes that the inclusions are soft yet brittle They reduce the amount of plastic deformation which can take place before cohesive failure occurs Once localized fracture has occurred at the position of a chain of these inclusions, a sharp notch (crack) is formed which produces stress conditions more favorable to cohesive failure than to plastic deformation These cracks aid erosion by providing channelways for the explosive gases, eventually leading to the tearing out or spalling of blocks of metal Oxidation of the surface may be partly responsible for the change in the surface of gun steel during firing observed by the author The appearance of burn on the surface is an indication that high temperatures were reached on firing, resulting in a slight oxidation of the surface Since the color of the oxidized film depends on both temperature and time, a higher temperature is required for a given color to form when it is caused by explosive heat, which acts for only an extremely short time at a given spot, than when it is caused by ordinary tempering The cross section of the gun steel specimen, Fig 16, illustrates that the repeated firing temperatures were high enough to cause

Jan 1, 1948

[Council for 1994/95 President J.A. Cruise President Elect D.A.J. Ross-Watt Vice Presidents Senior P.D.K. Robinson Junior Dr N.A. Barcza Immediate Past President Dr H. Scott-Russell Honorary Treasurer D.A.J. Ross-Watt Members of Council J.P.W. Bennie Dr L.A. Cramer Prof. R.J. Dippenaar J.R. Dixon A.A.B. Douglas F.M.G. Egerton Prof. R.H. Eric B.R. Fleetwood Dr M.A. Ford Dr R.V.R. Handfield-Jones P.J. Knottenbelt R.P. Mohring K.C. Owen M.H. Rogers K.A. van Gessel P.M.T. White]

Jan 1, 1995

By Lloyd A. Morley, Alan M. Christman

Mine One General. The first summer field trip for the purpose of collecting data on open-pit metal mine grounding systems was marred by the fact that the group's ground test instrument was damaged in transit and proved to be inoperative. Fortunately, the mine personnel had a similar instrument which was then used for all tests. System Description. Power is purchased from the utility at either 69 or 100 kV. This is transformed to 4160 V at the pit substations and distributed around the periphery of the pit via a "ring bus." The three phase wires and the safety-ground conductor are carried on a conventional wooden pole and cross-arm support structure. At key loca¬tions, overhead feeders carry power from the ring bus down over the benches and into the pit. Each overhead feeder is terminated at a switchhouse, from which an SHD-GC trailing cable supplies power to the electric loading shovels. Each pit substation has a main or system-ground mat, installed by the utility, and a separate safety-ground mat, which is constructed by mine personnel. Three of the safety-ground mats are quite old, and personnel at the mine could not recall what type of construction was used. However, records are available on the fourth mat and construc¬tion details are shown in Figure 64. Protective circuitry includes a donut or window-type current transformer through which the three phase wires are run. Additional

Jan 1, 1976

By James F. McConnell, Charles W. Statler

Pennsylvania's existing large coal-fired units are limited to 2.0, 1.8, or 0.6 lb of sulfur per million Btu fired, depending on site location. Multi-stream coal preparation can be employed on system basis to extract the highest quality fraction of coal for use in units requiring the lowest sulfur. The middling fraction can be directed to units permitted higher sulfur. General Public Utilities Corp. has concluded that it is feasible to advance the state-of-the-art of heavy media coal preparation to produce an intensively cleaned primary product of 1.3 sp gr of less than 0.6 lb of sulfur per million Btu for the new unit and a middling product of 2.0 lb of sulfur per million Btu for existing units.

Jan 1, 1977

By D. J. Carney, E. Richard Randolph, E. Van Meter, J. J. Oravec, Stanley H. Ward, Gerald J. Anderson, Rolland L. 203-000-000-005 Blake

DURING the last 30 years the inductive electromagnetic method has been used chiefly in the search for massive sulphide mineralization. This application has met with varying degrees of success and in recent years has resulted in discovery of several large orebodies. Little has been written concerning its use in exploration for soft iron ores, but one of the present authors has reported on experiments with massive magnetic deposits.' To augment the exploration tools available to geologists in delineating iron orebodies, Cleveland-Cliffs Iron Co. and McPhar Geophysics Ltd. undertook in 1953 to apply the inductive electromagnetic method to Cleveland-Cliffs properties in the Lake Superior region. As a result of this project, equipment has been developed that enables simultaneous transmission of two audio frequency waves, and the field technique and interpretative procedure involved have furthered exploration in the district significantly. Thus far, inductive electromagnetic application in the Lake Superior region has been only a development tool, that is, it is used to locate obscured contacts and faults as a part of property expansion and development. However, its application to primary reconnaissance of unexplored areas may be feasible in the future. The method has assisted in placing drillholes efficiently, and the elimination of excess drilling foot-ages and/or actual elimination of unnecessary holes has amply justified the expense of the geophysical survey. Cost of the field work involved is comparable on a per station basis to the cost of a magnetometer or superdip survey. Since observations require no reduction, i.e., are directly interpretable, overall expenditure is low, and the scope and detail of the survey can be adjusted in the field as geological- geophysical correlation becomes evident. To a great extent, this eliminates the second-guessing so commonly arising after office calculations are completed on data obtained with other types of geophysical surveys. This unique feature of field interpretation and its associated intimate feel of the project area, is, perhaps, one of the most valuable aspects of the inductive electromagnetic method as applied to iron ore exploration. Basis of Method Fundamentally, the method involves transmission of an alternating electromagnetic wave, of a chosen audio frequency, which permeates the ground materials in the vicinity of a transmitting, or primary, coil, see Fig. 1. This wave, or field, induces an electric current in any conductor on which it is incident. The flow of an alternating current in a conductor sets up its own, or secondary, radiating electromagnetic field. These two fields form a resultant whose configuration depends on the following characteristics of the subsurface conductors: 1) size, 2) shape, 3) electrical conductivity, 4) magnetic permeability, and 5) frequency of the transmitted wave. To a lesser extent the resultant is also dependent on material adjacent to the conductor, topography, and surface conductivity. For illustrative purposes, the primary, secondary, and resultant fields may be represented by vectors. In operation, the direction of the resultant vector is measured by a small receiving coil tuned to the frequency of the transmitted wave. Generally speaking, the method can be compared to the transmission and reception of the familiar radio broadcast, with special variations permitting measurement of the effect on reception of intervening materials. Field Technique Mechanics of field operation are simple. The mast is set up in a vertical position and is then guyed in place. The transmitting loop then is raised by means of a sheave at the top of the mast and the coil connected to the motor-generator. A special plane table is clamped into position on the mast and the loop is plumbed. The plane table is oriented according to a grid system established over the project area. By means of this plane table it is possible

Jan 1, 1956

By Elizabeth A. Johnson

Minor-element behavior and interaction in the copper matte-iron silicate slag system have been studied by the Bureau of Mines. In the present work, the possibility of interactions among the minor elements As, Sb, Bi, Se, and Te was investigated. Equilibrations of matte, slag, and one of each of the five minor elements were performed at 1,250° C under typical matte smelting atmospheres of CO, CO2, and S02 for mattes containing 40, 50, and 60 pct Cu. Results are compared with those of a previous Bureau of Mines study in which all five minor elements were present simultaneously.

Jan 1, 1984