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W: 0. HOTCHKISS, Madison, Wis. (written discussion*).-Mr. George's paper on. "The Wisconsin Zinc District" is a very complete and clear description, which it is a pleasure to read. His discussion of the origin of the ores is the least satisfactory part, and Mr. George correctly states present knowledge when he begins his paragraph on a origin with the words "the general supposition is, etc." There is still much to be learned regarding the details of the processes by which the ores have reached their present situation. In this the Wisconsin district differs not at all from other mining districts. It is my hope that Mr. George and others, equally clear-thinking, who are in close touch with these operations will be able at an early date to give us more information on this subject.

Jan 3, 1918

Stuart Manwaring Buck, a member of the Institute from the first year of its existence, and one of its Managers from 1883 to 1885, died at his home in Bramwell, West Va., on July 16, 1921, at the age of 79 years. He was the son of David and Matilda S. Ruck of Boston, and was educated at Williams College, at the Massachusetts Institute of Technology and at the School of Mines at Freiberg, Germany. Mr. Buck was one of the pioneers in the development of the coal fields of West Virginia. From 1872 to 1877 he was connected with the Kana-wha and Ohio Coal Co. as engineer and as lessor; from 1877 to 1888 he was general manager of the East Bank Coal and Coke Co.; from 1888

Jan 1, 1922

By Christine Alexander

Twenty years ago, the northern Oquirrh Mountains overlooking Salt Lake City were bare. Heavy logging and overgrazing combined with erosion and uncontrolled forest fires had severely denuded the mountains by the turn of the century. As a final coup de grace, a copper smelter was built there in 1906, and for the next 50 years its sulfurous fumes killed off what little vegetation remained. In 1956, Paul Rokich, a biology student at the Univer¬sity of Utah, started to surreptitiously restore the mountains. For the next 17 years, Rokich devoted his spare time and money to replanting the Oquirrhs, with the result that several thousand acres of the mountains are green again, and animals have returned: deer, elk, and rabbits thrive among olive, maple, and fruit trees, wheat grass, and sunflowers.

Jan 10, 1975

By R. E. Frounfelker, W. M. Hirthe

INVESTIGATORS in the areas of plasticity, crystal growth, and stress analysis have a need for crys-tallographic data such as the interplanar angles. This information is utilized in the form of a stereo-graphic projection from which orientation determinations can be made. Calculations of mechanical properties, such as the critical resolved shear stress, require values for the angles between directions as well as the interplanar angles. Only a limited amount of this data is available for tetragonal crystals. The equations for these angles are relatively simple but because of the large numbers of angles involved and the infinite number of structures that could be investigated, it was decided to program these calculations on a high speed digital computer. The angle, 8, between two crystal planes (h1 k1 l1)

Jan 1, 1962

A. A. Almstrom is mill superintendent for Barrue Mines, Barraute, Quebec. Frank A. Ayer, vice president of Copper Range Co., who has been in charge of the development and bringing into production of White Pine orebody in northern Michigan, has resigned. E. G. Bailey and H. S. Mudd were made honorary members of the American Society of Civil Engineers. Lee Bilheimer, graduate of Missouri School of Mines, has been employed as assistant mine captain at the Edwards, N. Y., div. of the St. Joseph Lead Co. Douglas C. Blackwell, recently graduated from the South Dakota School of Mines, is now with the Oliver Iron Mining Co. of Duluth, Minn. Joseph F. Brown has joined the Grand Junction Exploration Branch of the United States Atomic Energy Commission as a geologist.

Jan 1, 1952

By C. R. Hocott

THE viscosity of the oil in the reservoir is one of the properties that influence its movement through the sand to producing wells. Measurements of viscosity, therefore, are pertinent to problems associated with well behavior and with the estimation of recoveries, and afford an indirect means for partial evaluation of various methods of controlling reservoir behavior. The effect of dissolved gases on the viscosity of crude oil has been determined,1,2 but no data have been published on the viscosity of repre-sentative samples of reservoir oils. This paper describes a simple instrument that has been used to determine the viscosities of a number of subsurface oil samples at the temperatures and pressures existing in the reservoirs, and presents the results of the determinations for typical fields.

Jan 1, 1940

By F. Weston Starratt

The opening of a new large-scale beneficiation plant is always news, but the start-up of Cleveland-Cliffs Iron Co.'s Eagle Mills near Ishpeming in Michigan's Upper Peninsula early in October is of particular interest because of the completely different type of operation being carried on at this plant. The ore boat which left Marquette, Mich. on the 3rd of October bound for the plant of Wisconsin Steel Division of International Harvester, not only carried the first output of this new mill, but also carried the first agglomerate made from the Upper Peninsula's jasper ore, the first commercial output from an updraft traveling-grate furnace, and the first large-scale commercial application of the balling disk, also called the flying saucer, to the agglomeration of an iron flotation concentrate.

Nov 1, 1956

By Zden[e]k P. Bažant

Due to their heterogeneity, most rocks fracture with a zone of distributed cracking ahead of the fracture front. This makes linear elastic fracture mechanics inapplicable. The present study describes a mathematical model in which the progressive microcracking is taken into account by strain-softening stress-strain relation. In a simpler version of the model, the triaxial strain-softening stress- strain relation is obtained by direct adjustment of the elements of the compliance matrix. This formulation is rigorous only if the principal stress directions do not rotate during fracture formation within the fracture process zone. As a more sophisticated and generally applicable model, the so-called microplane model which is an analogue of the slip theory of plasticity is outlined. Comparison with fracture data for various rocks are given.

Jan 1, 1984

By Nathaniel Arbiter

THE separation of minerals by flotation can be regarded as a rate process, with the extraction of any one mineral determined by its flotation rate, and the grade of concentrate by the relative rates for all the minerals. So regarded, the significant variables for the process are those that control the rates. These variables are of two types, the first describing the ore and its physical and chemical treatment prior to flotation and the second characterizing the separation process in the cells. This paper will examine the variation in rates for a group of separations, will show that a simple rate law appears to govern, and will consider the relation of the control variables to the rates. The use of rate constants for evaluation of performance and efficiency will be discussed.

Jan 9, 1951

By Corale L. Brierley

An unidentified, high-temperature microbe, which oxidizes reduced sulfur and iron in an acid medium between 45° and 75°C, is studied to determine its ability to leach copper sulfide minerals and molybdenite. Copper is leached from low-grade ore as well as a chalcopyrite concentrate, and preliminary data indicate a tolerance of 1.0 gpl copper by the microbe. A molybdenite concentrate is also biogenically leached, and the microbe is able to continue growth when the soluble molybdenum concentration is 750 ppm. Molybdenum can not be biogenically extracted from waste material using the present technique. Direct observation using SEM illustrates colonial growth and developmental characteristics of the microbe on molybdenite fines. The organism responds to hexavalent molybdenum by reducing this metal to the pentavalent state in aerobic and nitrogen gas atmospheres.

Jan 1, 1974

By C. E. Lesher

Two processes for agglomerating fine sized ores with low temperature coke are described. One process (Orcarb) agglomerates ores with limited amounts of carbon; the other (ore-carbon pellets) pelletizes fine sized ores, using low temperature cokes as the binder. Data are presented on the products obtained when taconite, magnetite, and hematite concentrates and several titanium oxide ores were used. Reduction of finely divided oxide ores has long been a major metallurgical problem. Various methods of agglomerating, notably briquetting, sintering, nodulizing, and pelletizing, have been developed and are in industrial use. Carbon is the usual reducing agent for oxide ores and attempts have been made to agglomerate fine ores with coking coal in order to get the metallurgical advantages of intimate contact and increased particle sizes suitable for subsequent smelting or reduction.

Oct 1, 1955

By Austin Park

More metal at a lower profit continued to be demanded from the mining industry during 1969. Correspondence with U.S. and Canadian mining districts and a study of the mining literature indicate that, a large majority of the mines are keeping pace and rising to the challenge. Continued research and better understanding of pneumatically applied concrete for roof and wall support was of top interest. Many mines are changing mining methods for the adaptation of load-haul-dump units. The most recent adaptation being the use of these units in cut- and-fill stoping and in various types of development headings. Boring methods and use of two- or three- boom drilling jumbos mounted on rubber tires for versatility continues to be the favorite approach to the demand for rapid excavation.

Jan 1, 1970

By D. Jeulin

For iron ore sinters to be good blast furnace burden, they need to possess certain basic properties such as cold mechanical strength, reducibility, etc. Relations between such basic parameters and sintering parameters (composition of the mix, fuel consumption, operating conditions of the sintering plant, etc.) are not always well understood. For example, one cannot explain the differences in quality noticed for sinters having the same chemical composition. In this paper a new approach is proposed for the characterization of iron ore sinters by a quantitative description of their morphology. The Texture Analyzer LEITZ T.A.S. is used for this purpose and such morphological parameters as sizes of microstructures and the size distribution of phases are measured on samples of sinters. The results indicate that these measurements can be correlated with the sinter quality.

Jan 1, 1977

By Ross W. Smith, M. E. Wadsworth, T. James Smolik, A. S. Peck

Ross W. Smith (Acting Instructor, Department of Mineral Engineering, Stanford University, Stanford, Calif.) and T. James Smolik (Kennecott Copper Corp., Salt Lake City, Utah) - Professors Peck and Wads-worth have made an interesting contribution to the study of fluoride activation of beryl. We have a few comments to make regarding the paper and a question to ask of the authors. We note that glass containers were used in the study. Hydrofluoric acid should react with glass to produce SiFg2 in quantity which could adsorb onto the beryl surface (onto either beryllium or aluminum sites). The authors propose that individual F- ions actually go into the mineral surface lattice rather than onto the surface by adsorption of siFi2 ions. Based on infrared reverse bands with an untreated

Jan 1, 1969

By H. Jehn

The high-temperature oxidation of Pt metals results' in the formation of volatile oxides. The evaporation of which considerably increases the metal losses in oxygen-containing atmospheres when compared with high-vacuum or inert-atomosphere conditions. The paper describes gravimetric investigations carried out to determine the metal losses of polycrystalline samples of Ru, together with earlier studies on Ir and Pt at oxygen pressures of 10-3 to 1000 mbar and temperatures > 1000 °C. A strong pressure and temperature dependence is noted. Preliminary results of the oxidation of Pd are reported, too (665 mbar 02, 1100-1300 °C). The oxidation mechanism is discussed and the oxidation rates of Ru, Pd, Ir and Pt are compared with those of the other Pt metals Rh and 0s and of refractory metals.

Jan 1, 1984

By David A. Summers, Steven McGroarty

The last ten years has witnessed the change in water jet cutting studies, on rock, from laboratory testing to prototype use of field equipment. Unfortunately, while equipment and technological developments have occurred, the understanding of the exact mechanisms of water jet erosion have been less well developed. Commonly, theoretical evaluations have used the uniaxial compressive strength of the target rock as the major parameter of rock erosion resistance . It is considered that the structural properties of the rock, and most particularly, the flaw density and heterogeneity of the rock are much more important parameters. This is demonstrated and discussed. Locating the jet and target under water and pressurizing the containing vessel makes it is possible to induce cavitation in and around the water jet and create a much slower erosion process.

Jan 1, 1982

By Dale I. Hayes

Combined loader and transport, the Gismo is now built for sale in one size, 5 to 6 tons. It will operate in a minimum opening of 7x7 ft and can be built to operate at lower heights. Where space limitations are not a factor it could be designed with much greater carrying capacity-12, 18, or 25 tons-to be powered with a standard heavier tractor. The Gismo is mounted on crawler tracks of the same design as the tracks of the small Allis- Chalmers HD-6B tractor used to power it. With the HD-6B tractor it will negotiate upgrades of 12 pct and downgrades of 20 pct. The next tractor size would make the device feasible for steeper grades or for a machine of larger capacity at moderate grades.

Dec 1, 1956

By T. S. Maio, J. G. Mansanti

In 1978, Ozark Lead Co. made the decision to expand the capacity of its mine/mill complex by 33%. The objectives of the expansion were to increase mine production capacity by 1.8 kt/d (2000 stpd), increase lead metal production by 21.8 kt/a (24,000 stpy), and to construct new facilities and modify existing equipment to accommodate increased production. This paper gives a brief explanation of the equipment installed and the overall production and metallurgical benefits realized from this expansion. The expansion was completed in the second half of 1980 with all equipment debugging and fine tuning completed by the first quarter of 1981. Concentrator modifications and improvements were basically restricted to four areas: materials handling, automation of the mill grinding circuit, increased flotation capacity, and concentrate dewatering.

Jan 1, 1985

By C. Le Neve Foster

The object of this paper is to offer a few suggestions for improving the mining and mineral statistics presented by the governments of various nations on both sides of the Atlantic. At the present time one may fairly complain of' two evils—lack of uniformity in some cases and want of completeness in others. The consequence is that the statistics are either less plain than they might be, or are useless for comparisons, or fail to present a faithful picture of the state of the mining industries of a country. The principal subjects upon which information is desirable are: the amount and value of the mineral products raised and the number of the mining population. With these data it is possible to form an estimate of the importance of the mining industries of any given

Jan 1, 1894

By Roy J. Greenfield, Charles H. Stoyer

A geophysical survey was made in Kylertown, Pa., in an area where the ground water is polluted with acid mine drainage. Since acid mine water is a good electrical conductor, both direct-current electrical and electromagnetic loop methods were examined for their ability to determine the subsurface electrical conductivity structure and from this to imply the location of the acid water. Consistent results were obtained with the two methods and the interpreted subsurface resistivities were consistent with the electrical resistivity measured for water samples. It was demonstrated that fracture traces which act as conduits for ground water flow can be located with electromagnetic surveying methods. Thus geophysical methods for measuring subsurface electtrical resistivity can be used to advantage for monitoring the environmental impact on the ground-water system of acid mine water.

Jan 1, 1977