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By J. Nutting, J. W. Cahn

WITH the development of thin film techniques for the direct examination of metals in the electron microscope some new problems in quantitative metallography have become apparent. In order to obtain certain contrast effects in the electron optical image when examining thin films from alloys containing dispersed phases, it is essential to use films of a thickness at least two or three times greater than that of the mean particle diameter of the dispersed phase. From micrographs of such specimens it may be desired to obtain the volume fraction of the dispersed phase and the number of particles of the phase in a unit volume of the matrix. Under these conditions the particles sectioned by

Jan 1, 1960

By M. Muinonen, A. R. Barnes, R. Pandher, M. J. Lavigne

Over the past three years, Ring of Fire chromite ores have been tested extensively at both the bench scale and pilot scale at XPS Consulting and Testwork Services. Following bench scale testwork, two smelting campaigns were completed using a 300 kW DC arc furnace on different chromite deposits from the Ring of Fire. A ChemSheet model was developed to aid in the design and optimization of the recipes, and its predictions were confirmed with both the bench scale and pilot scale tests. A total of 7.5 tonnes of chromite ore was smelted at XPS. The results of the testwork demonstrate excellent reducibility for the ores tested with good reduction kinetics when compared with South African chromites.

Jan 1, 2014

By C. N. Kravig

STANDARD raises at Homestake are 150 ft long. Raises of more than 150 ft, driven with the use of a cage and hoist, are considered long raises- some have been driven more than 900 ft. Long raises have eliminated the need for access drifts on each level when transfer and ventilation raises are driven. These timbered cage raises, 7x9 ft in cross section, include a rock compartment and a combination cage, pipe, and manway compartment. To prevent excessive weight on the timbers, 10x10-in. bearing beams are cemented into hitches cut in the rock at 150-ft intervals. The beams also hold back timber movement caused by daily drawing of rock through the rock compartment.

Jan 6, 1957

By A. B. Morrow

Consulting engineers are well aware of large variations in plant operating cultures between countries, companies, and even within sites and operating crews. These operating cultures must be considered when designing Advanced Process Control (APC) applications in order to maximize utilization rates and return on investment. Designs must be driven by an understanding of the totality of unit operations. Economic factors, equipment constraints, management philosophy, maintenance department responsiveness, instrumentation reliability, operating crew skills and teamwork, and individual operator concerns are all important and must be considered during application design. A general approach to incorporating operating culture considerations into APC application design is described. A case study for an iron ore concentrator plant is presented.

Jan 1, 2014

By Fred N. Kissell, J. E. Matta, J. C. LaScola

The Bureau of Mines made laboratory absorption measurements on oil shale samples, which showed that the amount of methane absorbed is proportional to pressure and oil yield, and can be much larger than would be predicted based solely on porosity. Oil shale cores collected in the field were also measured for their gas content using the Bureau of Mines direct method, Cores taken from deep locations and far from outcrops yielded more gas than cores from shallower locations or at outcrops, when taking into account variations in oil yield, and all data indicate that oil shale mines that are both deep and far from an out- crop will emit low levels of methane gas.

Jan 1, 1977

By Byron Pickard

AT MIDNIGHT of Sunday, Aug. 27, 1922, a fire was discovered in the main shaft of the Argonaut mine, Jackson, Cal. With the excep-tion of a shift boss and two skip tenders who escaped, the entire night shift of 47 men was trapped in the mine and entombed for 22 days, when the bodies were recovered. The entombed miners made a valiant but fruitless effort to save their lives. Rescue crews toiled strenu-ously day and night for 21 days to save the entombed men, only to find they had arrived too late. From the experiences of the entombed miners and of the rescue crews, valuable lessons may be learned to prevent future catastrophes.

Jan 11, 1922

By W. Petruk

Imaging is a fundamental requirement when characterizing minerals, ores and related products. Images are used for presentation, texture analysis, characterization, image analysis, identification, etc. The image mode that is utilized is dependent on the application, mineral properties and available instruments. Different instruments produce images that display different features. In order of increasing complexity they are: hand specimens, a non-polarizing microscope, polarizing optical microscope, scanning electron microscope (SEM), low vacuum SEM, microprobe, secondary ion mass spectrometer, staining, cathodoluminescence, tomography and others. Image analysis uses images produced with either an optical microscope or a SEM, but the SEM images are superior in this application. Key words: Mineralogy, Imaging, Mineral characteristics, Scanning electron microscopy, Optical microscopy, Cathodoluminescence

Jan 1, 2003

Improve the safety of mine workers by developing a means of forecasting impending roof falls in underground mines. Approach The Bureau of Mines, through in-house and contract research, has developed the Roof Fall Warning Device. This battery-operated, portable electronic system forecasts roof falls by detecting and interpreting high-frequency rock noise, The technology has shown potential for detecting stress-related failures in a variety of underground environments. How It Works All geologic materials produce high-frequency acoustic emissions when they encounter an increase in stress. These ultrasonic frequency range events ( >20kHz) are well above the audible range of human hearing, very small in amplitude and duration, and can only be detected with sophisticated electronic equipment.

Jan 1, 1990

By S. Chander

The fundamentals of flotation are reviewed with an objective to understand the limitations in predicting the performance of a sulfide mineral flotation system and in its scale-up from laboratory studies to plant practice. The difficulties can often be traced back to complex interactions between chemical and physical parameters and nonequilibrium effects. The physical and chemical changes that occur during the long sojourn of sulfide minerals that begins with mining, continues through crushing and grinding, and ends when they emerge from the flotation cell as a concentrate, are reviewed. The benefits of new techniques that have become available in recent years to identify and estimate the amount of surface species are discussed.

Jan 1, 1999

By Alfred H. Bell, George V. Cohee

In 1939 Illinois produced 94,302,000 bbl. of oil—almost three times the amount of oil produced at the peak in 1908, when development in the southeastern Illinois field was at its height (Fig. I). It represents nearly a fourfold increase over the 24,075,000 bbl. produced in 1938 (Table 6). This rapid increase in oil production in Illinois is largely due to development in the Salem and Louden fields (Table I). During 1939 daily production for the state increased from 135,000 to 332,572 bbl. A notable increase in production for 1940 is expected as a result of the drilling of the Devonian limestone in the Salem and Centralia fields,

Jan 1, 1940

By Thomas Robins

About six years ago the writer had occasion to visit a large magnetic iron-ore concentrating-plant, and then saw for the first time rubber belts employed for conveying-purposes. These belts were from 20 inches to 30 inches in width, and some of them were as long as 500 feet between centers. When I spoke of the enormous amount of material they handled with a small expenditure of power, the superintendent assented, but at the same time complained that although he bought the best quality of belts, the abrasion of the ore wore them out very rapidly, causing continually very large bills for repairs and renewals. On close examination several interesting points were discovered :

Jan 1, 1897

By J. E. Gebhardt, S. Chander

Significant advances have occurred in the use of electrochemical techniques for sulfide mineral flotation research. The techniques have been used singly or jointly with other characterization methods. When used in combination with other methods, the electrochemical methods provide a means to control the state of oxidation of the surface. Various analytical methods are employed for characterization. The methods that have been used include wetting, x-ray photoelectron and fourier transform infrared spectroscopies. The electrochemical methods include voltammetry and transient electrochemical techniques of galvanostatic polarization and AC impedance spectroscopy. The challenge for the future lies in the utilization of this knowledge in plant operations so as to increase the overall efficiency of flotation separations.

Jan 1, 1989

By Alfred H. Bell, George V. Cohee

In 1939 Illinois produced 94,302,000 bbl. of oil—almost three times the amount of oil produced at the peak in 1908, when development in the southeastern Illinois field was at its height (Fig. I). It represents nearly a fourfold increase over the 24,075,000 bbl. produced in 1938 (Table 6). This rapid increase in oil production in Illinois is largely due to development in the Salem and Louden fields (Table I). During 1939 daily production for the state increased from 135,000 to 332,572 bbl. A notable increase in production for 1940 is expected as a result of the drilling of the Devonian limestone in the Salem and Centralia fields,

Jan 1, 1940

By T. R. Ellis

The vast majority of valuations produced for mineral properties using the net present value method provide an estimate of investment value or use value. Such an estimate can be a long way from the price that the property would actually sell for if placed on the market. Indicators from the market need to be used to validate or modify the net present value calculation if market value is being appraised. The comparable sales and replacement cost methods used in the appraisal of urban buildings generally fail when used in the appraisal of mineral properties. Other methods of sales analysis are introduced. Guidelines for what a minerals appraisal report should contain are presented.

Jan 1, 2002

Provide an effective method for "soft" soldering aluminum and aluminum alloys using conventional tin-lead solder alloys and flukes. The Problem In the past, it was virtually impossible to solder aluminum and aluminum alloys using standard tin-lead soldering systems (solder and flux) due to the presence of an aluminum oxide surface film which forms instantly on aluminum and aluminum alloys when these are exposed to air. The tenacious and stable oxide film enables aluminum-base materials to maintain their bright luster. But the film also prevents the required wetting and spreading of solder on the substrate, causing the loss of adhesion between the solder and the substrate. In addition, the heat produced during soldering increases

Jan 1, 1983

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation that New Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also (1) emphasise the discontinuous but inter-related nature of these processes of continental growth, (2) better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, (3) suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and (4) potentially lead to interpretations emphasising parautochthonous rather than far- travelled relationships between many New Zealand terranes.

Jan 1, 1995

By Giannini LM, Carras S

A fundamental problem in mine planning is that of determining the "optimum pit limit" of a mine. This optimum pit limit yields information which is considered essential in the evaluation of the economic potential of a mineral deposit, and in the formulation of long -, intermediate -, and short-range mine plans. Since the mid 1960's a number of mathematical techniques based on the "block model" have been proposed for solving this problem. When applied to large ore-bodies the implementation of these techniques, especially the more elaborate ones, poses considerable computational problems. In this paper we report on our work, done jointly with Systems Research Institute of Australia (SRIA), in devising strategies for overcoming these Problems.

Jan 1, 1986

By Charles Fulton

The study of the condensation of zinc from its vapor was undertaken to shed light on certain problems encountered in large-scale electric zinc-furnace work recently conducted. It is a matter of common knowledge that one of the disadvantages of the arc type, electric zinc furnace, is the production of a large amount of blue powder and proportionately little liquid spelter, for, as stated by Stansfield,1 "A notable defect in the electric smelting of zinc ores is the difficulty experienced in obtaining the distilled zinc in the liquid state; when zinc ores are smelted electrically, very little liquid metal is commonly obtained, nearly all of the zinc being in the state of powder."

Jan 8, 1918

By G. G. Waddell, T. J. Crocker, S. S. M. Chan

A successful engineering structural design often depends upon a thorough understanding of the material properties of the structure. It is no exception when designing a supporting system for stable underground openings. For this reason, studies were made in the deep mines of the Coeur d'Alene mining district to obtain engineering properties of rocks and rock masses immediately surrounding underground openings. In this paper, data concerning laboratory tested physical properties of rocks and in-situ deformation behavior of rock masses from the Galena, Lucky Friday, and Silver Summit mines of the district are presented. Interpretations of the data so obtained and suggestions for the use of the results of the investigations as design criteria are also outlined.

Jan 1, 1973

By M. R. Geer

THE increase in the number of coal-cleaning plants employing dense-medium processes occurring since 1946 is especially interesting when viewed historically. Both sand and magnetite were introduced as material for heavy mediums at about the same time, sand in the Chance process in 1921 and magnetite in the Conklin process in 1922, but from that point on their records diverge. The Chance process enjoyed a steady growth from its inception, whereas no additional magnetite plants were built in the United States for over 20 years. Then, following the close of the World War 11, magnetite was again introduced, this time with marked success. During the following years some 47 plants employing magnetite medium were built.

Jan 7, 1953