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The curve of Fig. 3 for pyrite requires modification. There 11% a range of pH values from 6.2 to 7.8 for which no cyanide is required to prevent contact. From 7.8 to 11.3 a small amount of cyanide is required, with a sharp maximum of 20 mg. per liter at pH=9.6. The mistake arose from considering too few solution compositions (17 were considered) in constructing the curve. Subsequent work with other collectors indicates that the corrected curve is typical for such systems; it illustrates the further development of the dip in the pyrite curve of Fig. 5.

Jan 1, 1938

By T. F. Archbold, W. H. King

THE diffusivities of gold in polycrystalline copper have been determined in the temperature range from 700° to 1000°C by the utilization of the neutron-activation method. Martin, Johnson, and ~saro' used this method for their investigation of the diffusion of gold into copper at 375° and 550°C for 59 days in order to circumvent the experimental difficulties imposed by the 2.7-day half-life of Au-198. They employed the conventional technique of depositing Au-198 on copper specimens for short-time dif-

Jan 1, 1965

By Ahmad Saberian

Five salt samples 20 to 40 cm tall, sealed on all sides except one, were exposed to a series of dissolution tests in various brine solutions and at different temperatures. Solvents were in the 50 to 96% saturation range and the temperatures varied between 40°F and 150°F. The collected dissolution data sets for vertical salt surfaces were analyzed and three were selected to be used for developing a general relation. After various curve fitting efforts, an empirical relation for salt dissolution rate as a function of brine temperature and salinity was developed.

Jan 1, 1985

This month, Foote Mineral Co. will start to commercially recover tin in the area of Kings Mountain, North Carolina. For 50 years there have been intermittant efforts to recover it but it has finally become economic as a by-product in the mining and concentrating of the associated lithium ore. An unusual deposit of a nonmetallic mineral which is high in sericite, low in quartzite, and similar in physical characteristics to pinite, has been discovered by the Summit Mining Corp. in Adams County, Pa. Work is in progress to determine its suitability for ceramics, fillers, and extenders for insecticides.

Jan 10, 1951

By K. Y. Lo, R. S. C. Wai, R. K. Rowe, L. Tham

Laboratory tests for the determination of thermo-mechanical proper- ties of three rock types were performed at temperatures up to 400°C. Results showed that for the medium and coarse Granitic Gneisses, the coefficient of thermal expansion and Young's modulus are strongly temperature and temperature history dependent. A threshold temperature exists for each rock type above which material nonlinearity becomes important, and is associated with the progress of thermal cracking. Finite element computations were performed to illustrate the influence of material nonlinearity and boundary constraint on thermal stresses. Finally, a case history of thermal spalling was analyzed and it is shown that the results of analysis are consistent with field observations.

Jan 1, 1982

By F. Milton Lewis, James L. Coburn

In this paper the economics for a conventional comminution system, consisting of three stage crushing and one stage ball mill grinding, are compared to a semi-autogenous/ball mill comminution system. Capital and operating costs for a copper concentrator in Arizona at two levels of production, 20 and 40 thousand short tons of ore per day, are estimated. In order to minimize the investment and operating costs, large size equipment is selected for all four cases. These cost data are evaluated and conclusions are presented.

Jan 1, 1982

By Richard E. Ellwanger

Methods of utilizing flocculents as settling and filter aids for mineral processing slurries are reviewed. Broad chemical classifications and techniques for proper dilution, multiple addition, and combination treatments are discussed. A variety of custom built and commercially available systems for makeup and delivery of flocculents to the application points are in use throughout the mining industry. Those concepts which, in the author's opinion, are particularly important to the successful makeup and we of flocculants are presented in relationship to the available makeup and feed systems. Actual industrial applications are included in the presentation.

Jan 1, 1982

By Charles E. Mauk, H. William Prengle, Robert W. Legan

A process breakthrough was needed for the complete destruction of total cyanide influent as high as 100,000 mg per 1, or below 1 mg per 1, to produce an influent with total cyanide below the limit of detection. The process uses ozone for the total destruction of cyanide and metal cyanide complexes. It was found that while ozone alone reacted with the iron cyanide complexes too slowly for practical application, ozone at slightly elevated temperature became more effective, and ozone with ultraviolet light became effective enough to permit the design of a successful system.

Jan 1, 1977

By D. R. Skidmore, C. J. Konya

To quantify the effects of proper stemming on air-blast and flyrock reduction for a surface mining operation, a study was undertaken with funding from the Office of Surface Mining. Known weights of explosive charges were detonated in a simulated blasthole when confined with various types and size distributions of stemming. Results showed that proper selection of material type and size distribution can reduce necessary stemming length by 41 % and airblast levels by 23%. A relationship was obtained for minimum length of stemming for explosive confinement as a function of stemming size distribution and borehole diameter over a range of explosive pressures.

Jan 1, 1984

By D. P. Seraphim

Single crystals of bee Li-Mg solid solution were grown and their internal friction was measured as a function of temperature, A peak of the Zener type was found in the damping spectrum. The activation energy for the relaxation process is 21.5 ± 1 kcal per mole and the frequency factor is 1015.7 ± 0.7 sec-1. ZENER internal-friction peaks which are observed for a wide range of solid solutions are attributed to stress-induced changes in local order.' In the present work a Zener internal-friction peak, the first reported for a solid solution of an alkali metal, is

Jan 1, 1961

By Monica Mengoli Chaves, Byron S. Gottfried

For the past several years the U. S. Department of Energy has sponsored the development of a computer simulation program that will predict the performance of coal preparation plants under a variety of different operating conditions. Recently a study was undertaken to transfer the simulation logic from the large scale mainframe environment to a small inexpensive microcomputer operating in a highly interactive "user friendly" environment. This paper describes a program that was written for the APPLE II Plus microcomputer which accomplishes these objectives. The program prompts the user for information in such a manner that it can be used by persons other than computer specialists. This makes the program directly accessible to plant managers, designers and operating engineers.

Jan 1, 1983

By Richard Klimpel

In this paper various formulae are developed which can be used to estimate stream flow rates or weight ratios given information on the stream components. The type and level of experimental error present in the stream component analyses does have an important bearing on the numerical values (and reliability) of the weight ratios calculated by the various formulae. A simple but theoretically sound method is shown for selecting appropriate estimation formulae for any given engineering operation. The derived formulae are applied to sets of experimental classification data for illustration purposes.

Jan 1, 1980

1 Healthy and active Local Section organizations are vital factors in promoting the vigor and growth .of the Institute 2 Activity on the part of Local Sections should be recognized and stimulated by appropriation of funds, from the Institute's treasury, and these appropriations should be as large as is consistent with the relative needs for other activities 3 As between different Sections, the amount of such appropriations should be based primarily on the extent of activities as reflected in the number and character of meetings held and the attendance of the members at such meetings 4 In making a request for funds for any year, the officers of a Local Section should submit a report on the printed form approved by the Directors at their meeting on November 19, 1937

Jan 1, 1952

By Harold V. Pearce

The fire which occurred in the fall of 1906, at the works of the Boston & Colorado Smelting Co., Argo, Colo., destroyed entirely the gold- and silver-refinery of the plant, and in view of the development of modern practice in the refining of copper-mattes, etc., the management decided that it would be inadvisable to rebuild that part of the works for the continued use of the process which had been conducted therein for so many years as a metallurgical secret. This decision probably removes altogether from the sphere of practice the '(Pearce" method for the separation of gold. At all events, it removes the busi-

Jan 1, 1909

By Charles O. Thompson

IN 1867 the city of Worcester walled in the Mill Brook for its main sewer. This stream, one of the important affluents of the Blackstone River, flows through the city in a southwesterly course from Salisbury Pond, and along its valley a considerable part of the heavy manufactories of the city are placed. At two points, a mile apart, a sufficient fall occurs to be turned to account for motive power, and at many points it was the right and practice of the riparian proprietors, prior to 1867, to use the water for steam and other manufacturing purposes. But the

Jan 1, 1881

By M. Lastra, A. Cruz, J. Menacho

The technical feasibility of treating exotic copper ore with an acid cure using concentrated H2S04 is studied. Applications in a conventional percolation leaching circuit for unaltered ore and in a conventional agitation leaching circuit for altered ore are examined. The main effects of an acid cure are to inhibit silica dissolution and to increase the sedimentation rate of agitated pulps. An increase in the rate and degree of copper extraction is also observed. Based on these results and the minimal additional investment required, acid curing appears to provide an excellent approach for treating exotic copper ores.

Jan 1, 1980

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) The position of converter blower at a side-blow Bessemer steel casting plant is vacant. The State Legislature of Utah has provided for the establishment of a metallurgical research department at the State School of Mines, Salt Lake City. Applications will be received for, the position of head of this laboratory, and further details may be obtained by applying to Prof. Joseph F. Merrill, Director, University of Utah, Salt Lake City. An engineering company owning patents for improvements in steel manufacture which have been adopted at many works in America, desires. to secure the services of a technical iron and steel metallurgist as assistant to its chief metallurgical engineer.

Jan 6, 1913

By Raymond E. Zimmerman

The Swirl Cyclone developed in Japan, although based upon the same principles as the standard cyclones for heavy-media or water-only cyclones for cleaning coal, is novel in that it is invested with the apex on top, discharging rejects at the top, and clean coal at the bottom. It also uses a variable air vent tube for controlling the vortex. Tests conducted indicate that its efficiency is not only as sharp as standard cyclones but it also performs using a much coarser grain magnetite, promising higher magnetite recovery. The author describes the results of tests conducted in Japan on a very difficult coal.

Jan 1, 1979

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 P. Somasundaran, D. W. Fuerstenau

Adsorption isotherms for dodecyl sulfonate on alumina were determined at 45°C and 25°C and the data was used for calculating the partial molar heat and entropy of adsorbed ions under various concentrations. Changes in OH and AS observed at certain concentrations agree with the postulate of interaction of surfactant ions to form two-dimensional aggregates at the solid-liquid interface. Values of the total OH and AS for the aggregation process calculated using the Clausius-Clapeyron equation is used to interpret the interactions of surfactant ions with each other as well as with the solvent molecules.

Jan 1, 1973