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By G. H. Jardine

In future years, decision makers in the coal industry will make more and more decisions based on information from computer-based models. Whilst the use of such techniques will provide many advantages for coal companies, particularly in terms of efficient utilisation of their human resources, it is equally important for the decision makers to have an awareness of the limitations inherent in each particular computer-based model being used to provide information for the decision making process. A recommended procedure for identifying such limitations - by analysing the 3 major elements of the model - is presented. The human aspects of increased use of computer-based techniques are emphasised throughout the paper.

Jan 1, 1983

By Robert H. Merrill

The art of rock mechanics has been applied in various forms since early man first used caves for housing and fashioned rocks into weapons, tools, and utensils. The development of the science of rock mechanics has occurred in a slow but steady fashion due to the complexity of the materials, geometries, and loading conditions involved. It encompasses a great diversity of topics ranging from techniques for rock destruction to those required for rock strengthening or support, and as such enters daily into the life of the mining engineer. Although today rock mechanics can be confidently used in competent geologic structures, the degree of confidence diminishes as the structures become more complex and the number of geologic defects become more numerous. Even so, the principles still give a better estimate of the structural behavior of underground openings than ever before, and the persons responsible for design and control draw freely and often on the subject. For the most part, the civil engineer will spend more time and money on pre-design than the mining engi-

Jan 1, 1982

By W. F. Miao

Nanocrystalline mixtures of Nd2Fe14B and a-Fe have been synthesized by mechanical milling and heat treatment. The samples exhibit isotropic behavior, with significant remanence enhancement associated with exchange coupling across the interfaces of hard and soft magnetic phases. Measurements of the effect of heat treatment on structure and magnetic behavior demonstrate the important influence of grain size on magnetic properties. The effect of alloy additions to increase the saturation magnetization of the soft phase and the magnetocrystalline anisotropy of the hard phase has also been investigated.

Jan 1, 1997

By Alan C. Noble

INTRODUCTION Forecasting of metal and mineral prices is a complex and hazardous undertaking. In order to accurately forecast prices, the complexities of both marketing and production must be modeled for each commodity. Even with the most detailed model, the economy may change unexpectedly, invalidating the forecast. Because of these factors, this chapter will not attempt to present specific methods for price estimation. It will, however, review the fundamentals of price forecasting as applied to planning and design of the final pit shell. Recognizing that no price estimate can be exact, sensitivity analysis will be reviewed as an approach to coping with these unknown variations.

Jan 1, 1979

By C. W. Merrill

The cyanide process in the United States, notwithstanding numerous failures made under the direction of the owners of the patent-rights, and others, has now passed its experimeiital stage, and can, undoubtedly, be made successful when intelligently applied to suitable material. Much, however, remains to be known as to the exact conditions under which this process is applicable to the treatment of gold-bearing ores. If the owners of the patent-rights in this country have ever scientifically investigated the matter, they have never published any valuable informatioil on the subject. Other parties who are now using the process (often independently of the patentees), have nothing to gain by publishing their experience; and, moreover, many of the chemical reactions described in the text-books refer to the use of solutions of potassium cyanide many times stronger than are used in the metallurgical process.

Jan 1, 1896

The various risk components to be addressed by explorers and project developers (and their investors) to minimise and/or manage the risk of Pacrim mineral investment are summarised to provide an overview of the issues involved and to set the scene. It then highlights the role of individual Mineral Industry Professionals (especially independent consultants) who are at the heart of any risk reduction or risk management strategy. The involvement of accredited qualified/experienced (competent) and reputable professionals is essential to produce realistic and reliable results that gain and maintain investor confidence. Today, high ethical standards as well as technical competence are sought by government legislation/licensing regimes and initiatives of professional bodies like AusIMM, MICA, Professions Australia, Council of Professions, etc. All attempt to regulate and guarantee reputable individual professional behaviour (particularly in the context of currently perceived high corruption levels in many Pacrim countries). Brief comment will discuss the usefulness of accreditation and ethics codes plus other specific codes (eg JORC/VALMIN and their international analogues in Canada, South Africa, etc) in reducing risks.

Jan 1, 2004

By R Vuolio, B A. Jonsson

In the center of Helsinki - capital of Finland - extensive blasting operations were carried out during the years 1982 - 84. At the corner of the streets Mannerheimintie and Simonkatu - in the Forum block - about 125,000 cu.m. of rock were blasted to give place for a new modern shopping centre (Fig. 1). Added to this amount of rock another 10,000 cu.m. were blasted for a transport tunnel to an adjacent underground bombshelter (Fig.2) which is to be used as a parking place in peace-time. The blasting work was demanding and difficult to carry out due to old buildings surrounding the work-site as well as computers and other sensitive equipment installed in some of them.

Jan 1, 1985

By N. L. Ananthanarayanan, J. F. Libsch

A LITERATURE survey1-' of sintering metal pow-A ders and powder compacts indicates that studies have so far been confined primarily to the latter stages of sintering in relatively coarse powders. Presumably this is due to the difficult techniques associated with studies of the early stages of sintering. Recent experimental and theoretical investigationsL-" on the preparation and the magnetic properties of ultrafine ferromagnetic powders suggest the possi- bility of following the sintering process from a very much earlier stage than has previously been considered. It is now well-known that ferromagnetic powder particles which are below a critical size behave as single domains and exhibit permanent magnet qualities characterized by a very high coercive force. When the same particles are fully sintered, the coercive force decreases to very low values corresponding to those of the solid metal. Thus the coercive force appears as a sensitive parameter which may be measured to study the early stages of sintering. To determine the feasibility of this technique, experi-

Jan 1, 1954

By Irvin Mayes, Maher E. Tadros

The effects of particle properties and dispersion on the filtration behavior of magnesiumhydroxide, silica, and polystyrene suspensions in aqueous media were examined. It was found that effective separation of particles can be achieved using filter media with larger pore diameters than the size of the particles. The addition of electrolytes, at concentrations lower than the critical coagulation concentration, to suspensions of polystyrene or silica resulted in an increase of the cake resistance. This result was interpreted in terms of a decrease in the effective particle size due to the increase in ionic strength. For magnesium hydroxide, an increase in the absolute value of the surface charge was associated with an increase in cake resistance and a decrease in cake compressibility. Low cake resistance values were obtained with suspensions of large particles with low surface charge and blocky morphology.

Jan 1, 1980

By R. R. Tatiya

The selection of a mining method for a particular deposit must be based on certain technical and economic criteria. This can be interpreted as maximizing extraction and productivity while maintaining safe working conditions and minimum costs. The methodology developed here examines some of these aspects. The proposed methodology was tested on copper deposits that could be mined by underground stoping methods such as sublevel stoping, cut-and-fill stoping and their variants. In general, it provides a practical approach to both method selection and optimum stope design for base-metal deposits.

Jan 1, 1998

By Robert Cooke

This paper shows how technology developed to analyse stabilised slurries can be applied to paste flows. The rheological characterisation of paste mixtures using the generalised yield pseudoplastic rheological model is described. It is noted that the slump test does not provide a complete rheological characterisation of a paste. Methods for calculating pipeline pressure gradients for laminar and turbulent flow are presented. The minimum pressure gradient is an important consideration to ensure that solids do not settle on the pipe invert. Important points to be considered for a pipe loop test programme are noted. The usefulness of the pseudo shear diagram for scaling pipe loop test measurements is demonstrated. Issues to be considered for the design of paste reticulation systems are discussed.

Jan 1, 2001

By Paul Levin

A coal preparation plant built with conventional materials only might be able to do an efficient job of preparing coal, but its maintenance costs would be high and emergency shutdowns frequent. To remedy this situation special materials are being used, either in original plant construction or for replacement of conventional materials. The special materials vary from high-strength and abrasion-resisting steels and stainless steel alloys to ceramics. They include hard surfacing welding rods, rubber refractories and some of the newer plastics, the merits of which are cited by the author. A coal preparation plant, limited strictly to the use of conventional materials-for example, mild steel, cast iron and ordinary rubber-could, no doubt, do an efficient job of preparing coal, but the high cost of maintenance and increasingly frequent emergency outages would soon force the operator to seek relief by introducing special materials such as alloyed steels, oil-resistant rubbers and hard-surfacing welding rods.

Jan 6, 1964

By G. F. Revey

All underground operations have limiting factors that influence overall profitability. Hoisting, hauling, available headings, labor, milling capacity and other factors limit how much material can be removed from an underground mine. Consequently, when mines use limited labor to handle the additional rock from overbreak and to perform extra ground support tasks, productive activity is replaced by nonproductive work. Mining economics are further penalized when overbreak causes dilution of ore grades. This paper reviews the organizational systems that mines have been using to create environments that foster the creation of successful overbreak-control programs. Actual case histories document the various quality-improvement techniques, worker incentives and practical project-management systems used by these mines. A brief review of controlled-blasting technology sources and overbreak-measurement tools is also included.

Jan 1, 1999

By L. J. Lorig, B. H. G. Brady

The Discrete Element Method is a numerical technique suitable for use in modeling the discontinuum behavior of jointed rock. The disadvantage of this method, in its application to analysis of underground excavations, is the necessity to discretize the complete problem domain. Since the far-field rock responds to the excavation as an elastic continuum, it may be appropriately represented by the Boundary Element Method. This exploits the inherent advantage of the Boundary Element Method in representing a quasi-infinite domain in terms of its internal surface geometry and associated boundary conditions. The procedures employed in developing a first-generation coupled Discrete Element-Boundary Element algorithm are described and the solution to a simple problem verifying the performance of the coupled code is presented. A procedure for numerical treatment of installed support systems is also presented.

Jan 1, 1982

This section is addressed to the computing needs of corporate (top) management which are less specialized than the computing needs of operating or divisional management described in the previous sections. It is essential that the computer be used as a tool to serve corporate management and that information and results are presented in a succinct form. A key responsibility of the manager of computer applications is to communicate well with corporate management. A common trap for computer management is to allow the development and implementation of sophisticated and academically interesting computer applications which do not enlighten corporate management in its decision-making task. Thus it is essential to devote sufficient time and effort to designing and specifying a computer system before developing and implementing the system.

Jan 1, 1979

By Hiroshi Himura, Shoichi Tsushima, Hiromi Goshima

This paper reports the construction of an environmentally-friendly tunnel in sedimentary soft rock near a residential area. The main tunnel, which will be used as the Onmawashi-Koen (Park) Regulating Reservoir, is a large-scale tunnel with a cross sectional area of 254.0 m2 and a lengthof 577.3 m, excavated using such support as shotcrete, rockbolts and steel H-sections. Since the large main tunnel is excavated in sedimentary soft rock, it is necessary to keep the stability of the tunnel face and the crown and to prevent surface settlement. A top heading with a length of 50 m is therefore driven as a pilot tunnel to observe the ground behavior during excavation, and to obtain information on the geological conditions based on which type of support structure is determined with consideration given to the results of field measurements and numerical analyses.

Jan 1, 2001

By Frank Firmstone

In the Kaernthner Zeitschrift, No. 2, 1881, p. 53, et seq., Prof. Ledebur details some experiments on the power of various silicates of lime and alumina, magnesia and alumina, and lime, magnesia and alumina, to remove sulphur from pig-iron, from which it appears (as has long been recognized in practice) that the more basic the silicate the greater the quantity of sulphur it will take up; but also that for the same grade of silicate, this quantity is greatest for the lime-alumina silicate and least for the magnesia-alumina silicate, the lime-magnesia-alumina silicate occupying an intermediate position, and he concluded therefrom (p. 59) that, for the production of pig-iron low in sulphur, pure limestones are to be preferred to those containing magnesia. Much the same opinion has been published elsewhere on high authority, and lately (not to multiply references) by Sir Lowthian

Jan 1, 1895

Meeting of June 4, 1915.-The President announced the appointment of the following Committee on National Reserve Corps of Engineers: Dr. Henry S. Drinker, Chairman; Arthur S. Dwight, and Warren A. Wilbur; also, the appointment of Arthur F. L. Bell as Chairman of the Committee on Petroleum and Gas, and of James F. hemp as Chairman of the Committee on Mining Geology. All of these appointments were approved. It was voted that the following minute be, placed on record and a copy sent, by order of the Board of Directors, to the family of John Birkinbine: "The Board of Directors of the American Institute of Mining Engineers hereby records its sense of sorrow and loss in the death of John Birkinbine, a former President, and for many years an active member of the Institute, and contributor to its Transactions. "Mr. Birkinbine's eminence as an engineer, author and editor, intimately connected with the industrial progress of the United States, brought him into contact With the leaders of science and the captains of industry, among whom his genial and estimable personal character won for him many friends; and his departure in the prime of Strength and usefulness is mourned by a wide circle."

Jan 7, 1915

Edward J. Stephenson. Extractive metallurgy. Recent advances. Park Ridge (New Jersey), Noyes Data Corporation. James L. McCall and P. M. French (eds.). Interpretive techniques for microstructural analysis. 1977. Institution of Mining and Metallurgy. Prospecting in areas of glaciated terrain. London, the Institution, 1977. £16 ($D.S. 30). NIM reports Report no. 1928 A liquid-nitrogen monitor for lithium-drifted germanium detectors. (21st Nov., 1977). Report no. 1931 The equilibrium between the slag and the metal in the production of low-carbon ferromanganese. (14th Nov., 1977). Report no. 1934 The spectrometric analysis of chromium-bearing materials with particular reference to ferrochromium slags and chromite ores. (30th Nov., 1977). Report no. 1935 The construction and testing of a small mixer-settler for use in the laboratory. (30th Nov., 1977). Report no. 1933 The determination of trace elements by thin-film X-rayfluorescence spectrometry, and its application to zirconium. (30th Nov. 1977). Report no. 1942 The accuracy of assays for platinum -group metals and gold. (30th Nov., 1977). Courses on geostatistics In view of the continuing demand, the University of Leeds will offer two further courses on geostatistics in 1978, each covering ten working days (3rd to 14th April, and 3rd to 14th July).

Jan 1, 1978

By Eva Surová, Molák. Bohumil, Márta Polgári

The Úrkút rhodochrosite deposit and Branisko Mn showings (rancieite, manganiferous calcite), located in Lower Jurassic marine sedimentary rocks with black shale, were studied by organicgeochemical methods. Both depositional localities were affected by the Lower Jurassic Toarcian anoxic event. UrkUt shales are rich in organic matter (av. 2.94 wtOJo total organic carbon), the composition of which indicates derivation mainly from marine sources, with some terrigenous component. The shales matured in a bacterially active environment under reducing conditions of diagenesis-catagenesis. Branisko shales (~0.2 wt % TOC) with lenses of Mn oxide ore were weakly metamorphosed and their organic matter thermally degraded. The model for Mn carbonate ore formation envisages reaction of Mn derived from sediments, with carbonate generated by a bacterially mediated process of decomposition of organic matter that also involved Mn reduction.

Jan 1, 1992