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By P Tzeferis

An exploratory laboratory work was carried out on microbial leaching of poor non-sulphide nickel ores, not amenable to conventional mineral processing operations. The results have shown that domestic low-grade lateritic ores of limonitic or haematitic type are amenable to bioleaching by fungal strains of Aspergillus sp and Penicillium sp. Maximum nickel and cobalt recoveries achieved were 60 per cent and 50 per cent respectively. Losses of soluble nickel in the fungal biomass were found in the range 3 - 11 per cent. Chemical analysis of the leach liquors showed the presence of significant amounts of citric, oxalic and other organic acids, indicating the role which certain metabolic products of fungal activity may play in the process. Possibilities for future investigations are discussed.

Jan 1, 1997

By F. E. Heuze

This article deals with the effects of high-explosive and nuclear explosions in rock masses. We first highlight the strong influence of geological discontinuities, such as joints and faults, on ground motion characteristics. Then, we briefly introduce the Discrete Element Method, as a new technique for numerical simulations. II is shown to be far superior to continuum-based approaches, when dealing with the dynamics of discontinuous media such as jointed rocks. Finally, we simulate the ground effects from a generic contained nuclear explosion, which bears some similarity to the SHOAL event in granite. This calculation is intended to emphasize the influence of the near-source geology on the distribution of energy, and on the motion at various azimuths in the medium.

Jan 1, 1991

To improve communication among Government, industry, and academic researchers in the field of thermodynamics, the Federal Bureau of Mines sponsored a Workshop on Techniques for Measurement of Thermodynamic Properties in August 1979. Participants at the workshop presented 33 papers on the subjects of temperature measurement and control, general calorimetric techniques, low-temperature calorimetry, high-temperature calorimetry, galvanic cells, ionic solutions, and heterogeneous phase equilibria. A special invited lecture was presented by E. F. Westrum, Jr., on the resolution of lattice heat capacity. This Information Circular comprises the proceedings of the workshop and includes the texts of papers presented and discussion by attendees.

Jan 1, 1981

By Robert G. Bottge

The Bureau of Mines investigated the availability of the land in south-central Alaska for exploration and mineral development of locatable minerals under State or Federal laws. The land ownership for an area of nearly 72.5 million acres in south-central Alaska was divided into 3 availability categories and 15 subcategories. In July 1985, 31.0 million acres of the study area were available for mineral exploration and development, 6.2 million acres were available with restrictions, and 35.3 million acres were unavailable. About 23.6 million acres in the study area are underlain by mineral terranes. About 9.9 million of the 23.6 million acres are available for mineral entry, 2.4 million acres are available with restrictions, and 11.3 million acres are unavailable. While much of the land currently classified as unavailable will be reclassified once it is conveyed to the State or to Native corporations, about 22% of the unavailable lands underlain by mineral terranes are now Federal parks, preserves, wildlife refuges, wild and scenic rivers, and military lands, all of which are considered permanently unavailable for mineral exploration and development.

Jan 1, 1986

By Frederic P. Dewey

The Bureau of the Mint of the United States Treasury maintains 13 ofEces for the purchase of gold-bullion, and this paper describes an investigation to establish the reasonable differences in the assay-results at the various institutions which may be commercially allowable in the settlements between them. Beginning with the comparative assay of proof-gold at the Philadelphia mint and the Utrecht mint, which shows 0.00002 as the closest agreement now possible, nine tables of comparative results, taken from the regular work of the service, are given..These tables begin with very fine gold, produced in an electrolytic refinery, showing close agreement in the assay-results, and follow through decreasing gold fineness and increasing amounts and complexity of base metals to very impure and complex bars produced at cyanide-mills, some of which give widely-varying results. Next is given a series of results on samples, prepared and sent out to various laboratories in the service, to test the influence of different metals and various combinations upon the agreement of the assay-results ; 11 samples were sent out and each one was assayed from 44 to 71 times, making a total of 623 assays. To these ire added 107 assays of identical samples of coin-gold. On a previous occasion,' I have endeavored to show the degree of accuracy that may be expected in the ordinary everyday analysis of various materials, and on another occasion,2

Jan 1, 1910

By Donald H. McLaughlin

PRICES paid for goods and services in paper currencies are undoubtedly determined by many interrelated factors, but among them none is more specific in pushing prices toward higher and higher levels than the vast increase in debts and monetary obligations of our own and practically all major governments. There is nothing unorthodox in the situation in which the gold miners find themselves today. With wages and the prices of all materials required in the production of gold at the high levels characteristic of a period of prosperity, phony or otherwise, and with shortages of both men and machinery to contend with as well, the spread between the returns in paper dollars that must be accepted for gold in the United States and the cost of producing it is rather painfully small for most producers. Technical

Jan 1, 1948

By A T. Spathis

The 11th International Symposium on Rock Fragmentation by Blasting (FRAGBLAST 11) was held in Sydney, Australia, between 24-26 August, 2015. The 93 papers, including six keynote presentations, covered exciting and practical topics in 20 sessions within 12 themes. Just fewer than 300 delegates from 27 countries attended. Four workshops were conducted on the weekend prior to the symposium, with three field visits after the symposium to Sydney region quarries, the Hunter Valley coal mining region, and the Kalgoorlie gold mining region. Delegates had the opportunity to visit the exhibition areas that showcased the latest products, software, hardware and systems in blasting technology. The keynote addresses were held in plenary sessions and set the tone for the parallel sessions that followed. They spanned the dynamics of the mining industry, the detonics of explosives, the interaction of stress waves and fracture mechanics in fragmentation, wall control blasting, and the importance of education and engineering for full process optimisation.

Jan 1, 2015

By J. R. Campbell

THE need for standardizing methods of arriving at definite conclusions regarding the cleanability of a given coal, and for measuring the performance of coal-cleaning equipment, is constantly increasing. Earlier notes by the author on this subject are amplified in this paper, because he believes that better preparation of bituminous coal is a partial solution of the coal operators' troubles. WASHABILITY STUDIES The term "washability" of coal was coined when washing was the universal method of separating coal from its impurities by utilizing their difference in specific gravity. This and analogous terms are still used in their broad sense although pneumatic or air separation is now used to clean coal. These terms are so used in this paper. Too much time or money, can hardly be spent on "feed surveys" to get a "picture" of the coal that is to be cleaned. There have been too many "rule of thumb" methods used. Screen analyses and "sink-and-float" tests on the raw coal enable the coal operator and washery man to predict within reasonable limits the results that may be expected from any efficient cleaning apparatus.

Jan 1, 1928

Mineragraphy is a coined term to signify the field of microscopic investigation of ore minerals. The term is not euphonius and is sometimes regarded as superfluous because the subject is no more than an enlargement of the scope of petrology. In the past the practical field of petrology has been largely limited by the instruments which were designed for the study of rocks and' the microscopical properties of the transparent minerals. The addition of mineragraphy has been brought about by the use of the reflecting microscope and a totally different technique.The use of the petrological microscope, as it has been employed in the training oi geologists and mining engineers for nearly half a century, has been justified many times, not only in its application to general geological problems, but also in the more restricted field of the exploration and examination of ore deposits. It provides information of the gangue minerals and rocks associated with an ore body which is of great value in some mining fields. In cases where ore deposits occur selectively in certain favourable types of rock, the recognition and delineation of these rock types is a useful guide in prospecting. The Boulder Belt at Kalgoorlie forms one of the most striking examples in Australia where important significance is attached to different rock types, and the petrological microscope is essential to their elucidation.

Jan 1, 1932

By P González, J Videla, E Córdova, I Gottreux

Currently, underground mining of deeper massive deposits with lower grades, harder rock conditions in high strength environments, entails difficulties in caving, fragmentation and seismicity of the orebody.So far, the use of preconditioning (PC) with hydraulic fracturing (HF) has shown positive results in terms of seismic response and caving performance, while PC combined with explosives aims to weaken the rock mass, causing an additional effect on fragmentation.In particular, mines commonly referred to as ‘supercaves’, operated by caving methods, have the need to integrate mine to plant processes, where rock fragmentation appears as a key tool. In fact, it implies making mining and comminution processes more efficient to the plant and for mines, it justifies the search of innovative solutions in drilling and blasting techniques to precondition the rock mass. The following paper aims to show the feasibility of numerical blast modelling to weaken the rock mass using explosives, mainly through sensitivity analysis applied to designs to minimise bias and uncertainty in the results. It is shown how the presence of structures, their geometry and in situ stresses influence or interfere with the PC method being used.From the work, it is concluded that better knowledge on the application of explosives weakening allows specialists to strengthen numerical models associated with every design and therefore previously validate their applicability, helping to understand complex phenomena such as the propagation of mechanical waves in non-elastic heterogeneous media. In this sense, it is understood that while there are studies (Sanchidrián, Segarra and López, 2006) showing that the transfer of energy in the rock mass could be even greater in a confined environment, the more competent rock mass and higher in situ stresses interfere mostly on the effectiveness of a technique using explosives.CITATION:Gottreux, I, Córdova, E, González, P and Videla, J, 2016. Preconditioning modelling and explosives effectiveness in block caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 683–688 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By John E. Rourke, O&apos

This report documents the process of site selection, instrument installation, data acquisition, and preliminary data analysis followed to characterize the physical response of overlying strata to longwall mining. A system of surface, subsurface and mine level instrumentation was installed at the Allen Mine in Weston, Colorado where the overburden varied in thickness from 600 to 900 feet. Survey monuments, automatic-recording strain-meters, multi-point rod extensometers, inclinometer-extensometers, stressmeters and tape extensometer convergence stations were installed to monitor displacements and stress changes. A preliminary analysis of the data acquired up until project termination has shown the system to be operative and strata response to be similar to that reported for other subsidence monitoring case histories. Recommendations for continued monitoring of the instrumentation systems are presented.

Jan 1, 1982

By A. E. Ketler

This report describes a variety of coal mine lighting projects which were funded by the Bureau of Mines in order to obtain underground lighting experience in support of new lighting requirements for underground coal mines. Low coal and high coal, narrow and wide entries, conventional and continuous mining, ac and dc power, bituminous and anthracite, and machine mounting and area lighting were some of the variables covered in this program. Also evaluated was the OCENCO fluorescent caplamp.

Jan 1, 1979

By C. Richard Tinsley

INTRODUCTION The economic analysis (Chapter 3), the engineering studies (Chapter 10), the credit structure (and the consequential funding sources) - Chapter 11, and the overall feasibility structure for any venture are all directed to determining one major decision element: How much and how certain is the reward for taking these risks? Risk assessment is a surprisingly weak area of analysis and is usually addressed in a checklist fashion. It is much preferable to deal within a risk system so that the inevitable tradeoffs among risks are correctly made. DEFINITION The first step toward risk definition must be to ascertain all of the risks to which a project or a company is exposed; otherwise one will remain ignorant of the possibility of a financially crippling loss until it occurs. (Carter and Crockford, 1974). However, simply stating what "risk" is can lead to debate. For example, risk could be (adapted from Vaughan, 1982): -the chance of a loss - uncertainty of loss -possibility of loss - uncertainty -dispersion of actual from expected results - probability of an outcome different from the one expected - possibility of an occurrence of an undesirable contingency -a condition in which a possibility of a loss exists. For the minerals industry financier, the last definition is probably the most appropriate. However, from a mineral company's point of view the definition might well include the possibility of not achieving the expected financial return. RISK CLASSIFICATION Risk identification will be readily agreed as the all-important first step. There are five major "branches" of risk classification. These are: -Statistical -Modellers -Checklist -Project Financing -Insurance The Statistical set discovered probability theory and any risk discussion soon deteriorates into a mathematical jungle (Megill, 1977; Hartman, 1976; Reutlinger, 1970; and Pouliquen, 1970).Their use of terminology tells its own story: coin toss (binomial distribution), gamblers' ruin, delphi (oracle) techniques, monte-carlo simulations, random walks, etcetera. These techniques inadequately represent the judgements necessary in an increasingly complicated and interrelated world. The risk Modellers have turned to the computer to handle these inter-relationships but soon find barriers because of "simultaneity". Certainly the computer has its uses to conduct various analyses (marketed as "sensitivity" analyses) but very often one finds that this involves changing one or two variables at a time, all other things being equal. Unfortunately, in a modern and complex world all other things do not remain equal. The statisticians will, no doubt, jump to their own defence by citing this

Jan 1, 1985

By G. P. Halliwell, C. R. Austin

The investigation described in this paper deals with the development of high-temperature alloys of the Konel series over a considerable period of time at t,he Research Laboratories of the Westinghouse Electric and Manufacturing Co. The word ''Konel" has been coined to designate a class of alloys which are essentially nickel-cobalt-iron with other elements added, usually in small quantities. Most of these alloys contain titanium, usually about 2.5 per cent. The main consideration related to strength at high temperatures but the thermionic characteristics of the alloys was also of considerable importance. It is, however, with the mechanical properties at elevated temperatures that we are herein concerned. Much attention has also been devoted to their age-hardening characteristics. There is little need to stress the utilitarian aspect of this subject, as it has been discussed frequently. Alloys exhibiting superior properties at normal or elevated temperatures rapidly find many suitable applications. There may be some question, however, as to what constitutes a "superior alloy," or an alloy that may have good service possibilities at high temperatures. The problem is complex and various means have been employed to predict the useful life that may be expected of a material. In recent years the "creep limitJ' has been used as the best means of evaluation. Such tests necessarily are prolonged and hence collection of data is very slow. In a general survey of many alloys therefore the creep test is not desirable and recourse must be had to much shorter time tests in order more rapidly to select alloys which appear to show promise. For this reason the present survey has been made using the high-temperature tensile test and a bend test developed by Howard Scott.' In the tensile test the conditions have been standardized for all tests, so that values obtained are at least comparable, one alloy with another, although the absolute values recorded merely indicate the mechanical properties at the given temperature under a definite rate of loading.

Jan 1, 1932

By Henry Kreisinger

Some of the investigations conducted by the Bureau of Mines have for their object the collecting and disseminating of information regarding methods by which the fuels of the country may be most efficiently used. As the analysis of flue gases tends to develop better methods of firing, which in turn reduces waste of fuel, the Bureau of Mines in this bulletin presents for the benefit of those in charge of boiler plants and all other persons interested detailed information on methods of sampling and analyzing flue gases, and on the utilization of the analyses in promoting boiler-room economy. This bulletin is intended to be a companion to Technical Paper 80,a and is written in plain and nontechnical language, as far as possible, so that it may be readily understood by persons who have not had the advantage of a technical education. Whenever possible, illustrations of apparatus and methods of handling have been used rather than elaborate descriptions.

Jan 1, 1915

By Robert F. Shurtz

This paper suggests that pre-occupation with the random process model notised by geostatisticians may result in neglect of more promising techniques, especially since the random process model does not appear to be essential to current geostatistical procedures. This point of view is emphasized pictorially. To emphasize the potential of new techniques a simple application of the conventional Brownian function is described. The probabilities estimated in this truly random way are different from those estimated by Kriging

Jan 1, 1980

By C. H. Larsen

The results of a comprehensive investigation of conveyance arrestment devices (safety catches) in United States coal mines are presented. Availability and use, performance, inspection, maintenance, testing, procedures, and regulatory requirements were investigated. Information was obtained from equipment manufacturers, mine operators, and regulatory-agency personnel, as well as from studies of domestic and foreign mining safety regulations. Traditional mine hoists and commercial elevators for mine use were investigated. Results of this and an earlier study of wire-rope practice in United States coal mines show a continued need for conveyance arrestment devices. A wide variety of these devices are in use. Only two types have been proved reliable for stopping a conveyance without injuring passengers or equipment. These are elevator overspeed-actuated wedge-clamp (Type B) safeties and broken-rope-actuated devices for wooden guides using a single-tooth-dog design developed in Ontario as a braking element. Elevators are widely used in U. S. coal mines. When maintained according to American National Standards Institute (ANSI) Specifications A17. I and A17. 2, they appear to present no major arrestment problems. Of 42 coal-mine hoists used for man transport that were inspected, 30 are in vertical and 12 in inclined shafts. Twenty-four vertical shafts use wood guides; 6 use steel. The 12 inclined-shaft systems use flanged-wheel T-rail guidance. Two wood-guided vertical-shaft systems use the single-tooth Ontario-type dog; the other 22 use multi-toothed wedges, cams, or dogs that have been proved highly unreliable. The arrestment devices in the six steel-guided vertical-shaft systems and in six of the inclined-shaft systems cannot be evaluated because performance data are lacking. The remaining six inclined-shaft systems have no arrestment devices at all. Of the 36 hoists with arrestment devices, the devices of 16 are never tested, the devices of 10 are actuated periodically with the conveyance at rest, and the devices of the other 10 are actuated periodically with a slow-moving conveyance. Although high speed is as probable as low speed in an emergency and would provide the best test of arrestment capability, no tests are performed in the United States which demonstrate the ability of an arrestment device to stop a loaded conveyance from high speed. Mine operators indicate little confidence in their conveyance arrestment devices, and manufacturers recognize a need to improve their products. Neither state nor Federal regulations provide a guide to this improvement. Mine operators, manufacturers, and state and Federal regulatory agency personnel would welcome specific guidance. In view of this, a set of application, design, actuation, stopping-performance, and testing and inspection criteria is presented as a guide to eliminating the inadequacies of these devices. Recommendations are included for improving hoist controls and machinery directly affecting conveyance safety.

Jan 1, 1972

By H Haas

H. HAAS, San Francisco, Cal. (communication to the Secretary?). -Fig. 1 plainly shows that the comparison of the steam-turbine and Diesel-engine plants was made on a basis of 6,000 kw. continuous operating load. The tabulation of costs for an 8,000-kw. load is merely done to show the relation of increased output on' the unit power costs. Both plants would sacrifice their reserve capacity, which is to insure continuous operation, if operated to generate 8,000 kw. continuously; unless Mr. Hawkins advocates the operation of one of the turbines at 33.33 per cent. overload, retaining the other as a standby, which, besides overtaxing the turbine, results in a great loss of efficiency. It would he well for Mr. Hawkins to qualify certain of his statements. Thus, under the caption "Diesel Engines, Selection of Units," he says that "two of the largest Diesel-engine builders take the position that, in the present state of the art, they would not attempt to put out units over 1,000 kw.;" he should qualify it by saving that "two of the largest American Diesel-engine builders take the position that, in the present state of the art in the United States, they would not attempt to put out units over 1,000 kw." The reason that American manufacturers restrict themselves at present to units of that size is to be found not so much in a lack of experience in building large units as in a lack of a sufficient, demand for them in the United States to justify the heavy capital outlay connected with the development of such engines. There are relatively few localities in the United States where fuel prices are as high as they are in the Southwest, and regions of high fuel prices are sparsely settled and have a very limited demand for power. Where low fuel prices obtain, steam turbines are active competitors of Diesel engines for large power plants, particularly when the station load factor is low. As most of the American manufacturers of Diesel engines work under license agreements with European manufacturers, which limit their market to the United States and its possessions and Canada, a further limitation is imposed upon them, leaving to European firms practically the entire world as a market.

Jan 5, 1917

By J. E. Cleveland

The major health concern for uranium miners is the release of radon gas and the resultant ingrowth of the short lived daughters in the mine atmosphere. Present methods of control are the utilization of mine ventilation systems for dilution and control of ingrowth time to maintain working levels below those set by regulations. This study examined pressure cycling efforts on the radon emanation. The mechanical ventilation systems were altered to allow pressure changes throughout the mine to increase radon influx during the off shifts and thus deplete the sources of radon gas. Continuous radon working level and environmental monitors, developed by the Bureau of Mines, were employed to monitor radiation and physical parameters in the mine workings. The mine ventilation system was then varied to induce radon flows during off shifts, thus, depleting the radon sources during normal production shifts. Electro-static precipitators were also tested to determine radon daughter collection efficiencies. Both radon and radon daughter concentrations were monitored and evaluated. Major problems were found in the simple mechanical operation of cleaning these units.

Jan 1, 1982

By V. B. Achanti, A. W. Khair

Laboratory studies were carried out at West Virginia University to investigate the rock fragmentation mechanism by continuous miners using an automated rotary cutting simulator. The primary factors influencing the fragmentation process were found to be: bit spacing, bit geometry, depth of cut and cutting drum rotational speed. This paper presents the influence of these parameters in achieving optimum energy consumption and minimizing dust generation during rock fragmentation process. Tree bits were used simultaneously on Indiana limestone while the bit tip angle was varied from 60° to 900. Bit spacing was varied from 2.54 cm (1 in.) to 5.08 cm (2 in.) while the cutting process was assessed for varying cutting depths. Restorable dust generated during the course of the experiments was analyzed utilizing cascade impactors. Assessment of these parameters has led to a better understanding of the cutting mechanism by continuous miners in terms of energy consumption and dust generation.

Feb 24, 1997