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By George Holderer

THE relation between man-hours of labor and production may be correlated for any industry, and already it has been widely used in piece-work studies. It is not in general use as yet for recording labor efficiency of an enterprise or an industry. An exception to this is the Cement Institute, which tabulates the man-hours used in each operation and FIG. 1.-LABOR PRODUCTIVITY IN COPPER MINING. thus gets the total man-hours per barrel of cement. The writer knows of one steel company that keeps a complete record of man-hours for every operation from mining the ore to finishing the product. No doubt many others find the information useful, and such a study could be of value to the mineral industries.

Jan 1, 1935

By A. F. Crawley

THIS communication reports measurements of the densities of dilute liquid alloys of 0.1 and 0.5 pct Ag in Sn over temperature ranges of 170" and 210°C, respectively, above the melting point of pure tin (232°C). The work was earried out to provide accurate density data for some liquid diffusion studies performed by Davis.1 Densities were measured using a pycnometric technique established in this laboratory. Earlier papers2, 4 attest to the accuracy of ±0.05 pct and the reliability of the method. Tin, 99.999 pct pure, and silver 99.99 pct pure, were melted in a graphite crucible in a vacuum furnace and held at temperature for 10 hr to ensure homogenization. Ingots suitable for machining

Jan 1, 1970

By A. F. Peterson

MUCH has been said and written about the engineer shortage. The mining branch in engineering has lagged during the past several decades. I can think of two institutions, formerly prominent in that field, that have discontinued this department and another that has branched from a purely mining school into various forms of engineering. Conversely, I do not recall any institutions that have added mining to their curricula. I believe that this action is in direct response to the demands of incoming students. But I also believe that while there is a specific demand for civil, mechanical, and electrical engineers in the highly complicated mining operations of today, our need for mining engineers capable of assuming top responsibility for mining operations is unchanged.

Jan 3, 1957

By M. S. Klima, P. T. Luckie

An evaluation of the operating performance of a recently designed pneumatic centrifugal classifier is presented. This classifier has been modified from a separate air and feed input design to an entrained solids in air feed input. The evaluation first required determining the size distributions for the three streams (feed, fine, and coarse). Using size distribution data and mass flow rates, a size selectivity curve was calculated for each operating condition tested. This curve, in turn, was characterized by appropriate selectivity parameters (i.e., the equiprobable or cut size, the sharpness index, and the apparent bypass values). The variation of these parameters with classifier operating conditions was examined. From these evaluations, the "best" operating conditions for the classifier were then determined.

Jan 1, 1985

By Christopher Haycocks, J. Richard Lucas

The growth of computer and ground control technology in recent years, combined with an urgent demand for low-cost fossil fuels and mineral resources, has set the stage for full-scale utilization of computers in mine planning. Steeply rising production costs and the need to preserve the environment are placing great demands on engineers to improve their mining efficiencies, which can best be accomplished by applying the full capabilities of the computer. Pressure to develop and perfect programs with an immediate potential for improving mine design, reducing mining costs and extending the viable coal reserves of the country has already come to bear in the form of exploding energy requirements, environmental considerations and the visible limitations of other energy sources.

Jan 4, 1973

By Kenneth E. Kulp, Theodore Botinelly, George J. Neuerburg

Distribution of hypogene iron oxides may be useful in prospecting the Montezuma district, central Colorado, for certain metals, some of which have not been mined or sought in the district. The depletion of accessory magnetite in fresh rocks of the Montezuma stock identifies sources of ore minerals for the pneumatolytic metals, locates probable areas of possible contact-pneumatolytic deposits, and, in the altered rocks of the stock, identifies rock through which hydrothermal ore fluids have passed. Specularite veins are located in structures through which pneumatolytic ore fluids have passed and thus indicate optimal areas for prospecting. The presence of unusual amounts of vicarious metals such as bismuth, mercury, tin, and tungsten serves to identify magnetite and specularite that were involved in the pnematolytic ore process.

Jan 1, 1972

By K. V. S. Sastry, S. C. Panigraphy, D. W. Fuerstenau

The batch balling behavior of hematite, magnetite and limestone was found to depend markedly on the grinding method used for feed preparation. Wet ground materials require higher moisture for balling than do dry ground materials. Further, as the fineness of the wet-ground material is increased, the overall rate of agglomeration decreases, whereas the opposite is true for dry-ground materials. In contrast, the resulting pellet size distributions are not affected by the nature of the feed material preparation. These differences and similarities in the agglomeration behavior between wet and dry ground materials may result from the hydrophilic/hydrophobic nature of the surfaces, the formation of pre-agglomerates during dry comminution, and possible variations in the packing density of particles in the agglomerates.

Jan 1, 1978

By A. M. Gaudin, J. G. Morrow

FLOTATION requires the existence of a definite contact angle. This contact angle, the surface tension of the solution, and adsorption at the solid- fluid interface are quantitatively related. Adsorption of dodecylammonium acetate on hematite was measured for a wide range of concentrations of reagent in solution. Similar measurements for quartz have already been made.1 Contact angle measurements were then made on polished surfaces of hematite and of quartz immersed in aqueous dodecylammonium acetate solutions, and a functional relationship was sought between adsorption density at the mineral-solution interface and the contact angle. Finally, the surface tension of the aqueous amine acetate solutions was measured. These data were combined to give an evaluation of the work of adhesion for the three-phase system.

Jan 12, 1954

By John W. Tieman

Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased.

Jan 8, 1972

By S. G. Malghan

Steel consumption forms a significant part of the operating cost of a minerals processing plant. An estimated 250 kt (276, 000 tons) of steel in the US and over 500 kt (551, 000 tons) worldwide are consumed each year in wet grinding alone. The depletion of ore grades and the need for finer grinding of abrasive ores are expected to increase steel consumption even more. Through continued research and development by the mining industry and the suppliers of steel products, several methods to reduce steel consumption have evolved. This paper critically reviews the mechanisms involved in steel wear and the currently available methods, materials. and operating conditions for reducing steel consumption. Particular attention is given to liner design modifications and substitution of rubber liners for steel liners.

Jan 1, 1983

By E. W. Greig

This paper is an account of exploration for bauxite in the Amazon Basin, Brazil, and particularly of the discovery, exploration and development of the Trombetas deposits by Alcan. A general report of the Trombetas Project has already been published in E/MJ(Anon. 1975) to which the reader is referred for details on ownership, infrastructure and construction as well as the proposal for mining and treating the bauxite. A regional account of bauxite in and around the Guyana Shield and the northern part of the Brazilian Shield is included to help explain the geology of the Trombetas deposits and their relation to other bauxites in northern South America. It is suggested that all these deposits formed during Tertiary time under similar geologic conditions.

Jan 1, 1979

By R. S. Archibald

THE Blueberry mine is about 10 miles west of Ishpeming, Marquette County, Michigan. The property consists of about 2000 acres in sets. 3, 4 and 5, T. 47, N.R. 28W. and sets. 32, 33 and 34, T. 48, N.R. 28W., and, excepting one intervening 80-acre tract, contains the iron formation for a length of about 2 1/4 miles. The property is traversed by State Highway M-28 and is served by three railways, the Chicago & Northwestern, the Duluth, South Shore & Atlantic, and the Lake Superior & Ishpeming. The Northwestern transports the ore to a dock at Escanaba; the other railways, to Mar¬quette. Ore for Chicago goes via Escanaba and that for Lower Lake ports, as Detroit, Cleveland, and Buffalo, via Marquette.

Jan 1, 1935

By A. J. Lynch, W. J. Whiten

Extensive research, ,development and plant application work has been done on automatic control systems for wet grinding and sulphide flotation circuits during the past twenty years. The result is that there is a good understanding of the process mechanisms, the effects which changes in different variables have on these processes, the procedure for design of control systems to satisfy particular objectives and the problems in the implementation of control systems. There is also an appreciation of the problems which are still to be solved. These are reviewed briefly in this paper. Other processes used for the beneficiation of fine particles have been studied in lesser detail. The control of dry grinding, coal flotation and gravity separation are mentioned briefly in this paper.

Jan 1, 1980

By Theodore H. Eyde

The Superior Oil Co. drilled two holes, 4720 and 5940 ft, respectively, using conventional oilfield rotary drilling equipment. The results indicated that large rotary drills can be adapted to mineral exploration purposes with few modifications. The principal advantages are: a large hole diameter, excellent samples of cuttings, a geolograph which is a constant drilling record, rapid penetration even in hard rocks, and the ability to use electric logs for measuring the properties of the rock being penetrated. The disadvantages are the high cost of mobilization, drilling, and oilfield service at remote locations. Though the oilfield sampling techniques are adequate for identifying lithology, improvements are necessary to obtain representative samples for analytical purposes. As deeper targets are explored, mineral exploration organizations will have to resort to rotary drilling.

Jan 1, 1975

ECONOMICS In the preceding pages you will find an attempt to judge the direction of one phase of the mining industry in Drift, and following that a quick round up of what happened to production in 1958 in Trends. Next, Charles Merrill presents a comprehensive price history for the mineral products of greatest importance, complete with figures for the past 50 years. On the following pages Nathaniel Arbiter and Charles Will Wright take a look at price trend prospects and the cold war in mining, respectively. MINERALS BENEFICIATION Fifty years progress is reviewed as a springboard for a look ahead. In the past decade the art has moved forward, but the author fears that the science is not progressing as promisingly.

Jan 2, 1959

By J. B. Mitchell

The intelligent selection of comminution systems for industrial minerals requires a broad background of comminution experience. At the same time a thorough knowledge of the specific mineral occurrence, the applicable process and the product end use is required. To illustrate the different ways to process potash ores three flow sheets have been selected for presentation.

Jan 1, 1970

REPORT OF PRESIDENT C. F. RAND FOR THE YEAR 1917 The noteworthy occurrences during 1917 were the creation of Engineering Council; the completion of the addition to the Engineering Societies Building. and the occupation by the American Society of Civil engineers of the space thus provided for it; the addition of 67,000 vol-

Jan 3, 1918

By J. F. Myers, F. M. Lewis

This second progress report of grinding presents comments regarding ball consumption and data pertaining to the hydroscillator, which is closed circuited with the tricone mill. A study and postulate of how balls function is presented. The paper summarizes cost reduction obtained by the method of "grinding for the tail race" rather than for "mesh tons."

Jan 11, 1950

By M. J. Miller

In modern mill design, a stockpile storage system for raw and/or semiprocessed ore has become almost indispensable. This paper discusses the benefits of such stockpile storage as well as the available types of belt conveyor stockpiling units. Alternative reclaiming arrangements for stockpiles are reviewed, and the advantages and disadvantages of each arrangement are discussed.

Jan 1, 1982

The ten-year "supply-demand relationship" tables in this chapter for various mineral and metal commodities have been adapted from Minerals in the U.S. Economy, compiled by the Bureau of Mines, U.S. Department of the Interior, published in 1975. Acknowledgment is made to the Bureau of Mines for compilation of the tables. [ ]

Jan 1, 1976