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By R. E. Zimmerman, Michael Sokaski, E. R. Palowitch, M. R. Geer, H. F. Yancey, W. Deurbrouck, S. C. Sun

PART 1: DENSE MEDIUM SEPARATION by M. SOKASKI, M. R. GEER and H. F. YANCEY INTRODUCTION In the early days of coarse-coal treatment by the dense-medium process in Europe, loess was one of the materials used for medium solids. Newly developed cyclones were used to reclaim and thicken :he loess suspension. On occasion, when the cyclone thickener at the Maurits mine in the Netherlands plugged, the overflow was found to be filled with clean coal free of impurity. From this observation stemmed the concept of the cyclone as a cleaning device. Development took place during World War 11 in the laboratory of the Dutch State Mines under the direction of M. G. Driessen. A 15-ton-per-hour pilot plant was in operation in the laboratory by 1945, when, in September, Driessen made the first public disclosure of the process in a paper presented to the Institute of Fuel in London. In April 1945,2 operation of this pilot plant was observed by one of the authors, who was so impressed with the potential of the cyclone process that, on his return to the United States, a research program on the cyclone was started by the Bureau of Mines immediately. This work led to an AIME paper in 1946 in which the first details of cyclone operation on American coals was made available. Commercial adoption of the cyclone proceeded in Europe, initially in the Netherlands, Germany, and France. In the United States, where coal is less costly and most of the coals are so easy to clean they respond well to simpler cleaning systems, the first cyclone plant was not built until 1961.3 As of the spring of 1967, a total of 31 commercial cy- clone plants had been installed or were under construction in the United States; this does not include eight Dynawhirlpool plants. The capacity of the cyclone plants ranges from 50 to 1300 tons per hour and totals 6600. THEORY Before discussing the theory of a dense medium cyclone, a brief description may be helpful to some readers who are not familiar with its basic operation. In a typical dense-medium cyclone, illustrated in figure 10-1, the mixture of medium and raw coal enters tangentially near the top of the cylindrical section, thus forming a strong vertical flow. The refuse moves along the wall of the cyclone and is discharged through the under- flow orifice. The washed coal moves toward the longitudinal axis of the cyclone and passes through the vortex finder to the overflow chamber.

Jan 1, 1968

The mining fraternity of North America was grieved and shocked to learn of the death of Dr. Willet G. Miller on Feb. 10, 1925. Doctor Miller was for many years the Provincial Geologist of Ontario and the one who more than any other had contributed by his personal work and the reports of his subordinates to the recent extraordinary mineral development of the Province. Doctor Miller was fifty-eight at the time of his decease. A man of unusually stalwart physique, he seemed destined to many years of useful service. His friends in both the American and Canadian Mining Institutes can with difficulty reconcile themselves to his loss. Doctor Miller was born in 1867 in Port Rowan, Ont., on the shores of Lake Erie. After preparation in the high school of his native town, he entered the University of Toronto and took his bachelor's degree in 1890. He pursued graduate studies in geology at Chicago, Harvard, and Heidelberg Universities. In 1893, he was first appointed lecturer and soon thereafter Professor of Geology in Queens University, Kingston, Ont., a chair which he held until 1902. He was then appointed Provincial Geologist of Ontario and was placed at the head of the Survey which was attached to the Department of Mines. Within the next year, 1903, he performed the service that made him famous. In the summer of 1903, in connection with the building of the Ontario Government Railway toward an objective on James Bay, veins had been noticed by construction parties just north of what is Cobalt Lake today, and in the rocky pass that is now traversed by the main line of the Canadian National Railway en route to Vancouver. The pink stain of cobalt bloom on the vein, known later as La Rose, caught the eye of a workman; in November, Doctor Miller recognized the silver in it, and brought the possibilities of the district to general attention. In December, he published an article in the Engineering and Mining Journal, stating that the veins could be worked at a handsome profit. During the winter and spring, the mining interest awoke, which resulted in the astonishingly productive silver district of Cobalt; but in which, Doctor Miller, because a government official, scrupulously refrained from having any financial interest whatever. Seldom has so high a sense of honor been manifested; and as the result, Doctor Miller commanded confidence and respect to an extraordinary degree. Hard on the discoveries at Cobalt came, in the next few years, those at the other famous camps in Northern Ontario; and step by step with them, reports issued from

Jan 1, 1925

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By W. A. Ver Wiebe

The year 1939 in Kansas, with a production of 57,944,300 bbl. from 19,669 wells, shows a slight recession from the peak of oil production reached the previous year, when slightly over 59,000,000 bbl. of oil was marketed. The previous peak had been reached in 1917 with 45,451,000 bbl. marketed. Another still earlier peak had been reached in 1904, when slightly less than 5,000,000 bbl. was produced and sold. The production of gas probably reached a new peak during 1939 with a total of over 69 billion cubic feet. Between the peak of the year 1908, when over 80 billion cu. ft. was produced, and that of 1939 the production dropped to 16 billion cu. ft., in the year 1921. During the year 1458 wells were drilled. This figure is somewhat lower than that given in several trade journals, because it does not include wells that were deepened or recompleted in a different geological horizon. Nearly 75 per cent (1029) of the total number of wells were completed as commercial oil wells (824 in western and 205 in eastern Kansas). The commercial gas wells completed number 71, of which 24 are in eastern Kansas and 47 in western Kansas. The remaining completions include 154 dry holes in eastern and 204 dry holes in western Kansas. Based on daily potential capacity the new discoveries of the year accounted for a cumulative initial production of 264,000 bbl. in eastern and 1,158,827 bbl. in western Kansas. It is interesting in this connection to note that the number of wells completed in the state rose gradually to a first peak in 1904, when 2782 were drilled. The number dropped off rapidly to 368 three years later, but rose to the second and highest peak in 1918, when 4671 wells were completed. In the period between 1904 and 1912 more gas wells than oil wells were completed. Between the high peak of 1918 and the somewhat lower peak of 1937, the low point was reached during 1931 with the completion of only 470 wells. In the matter of new pools discovered, Kansas again ranks high. The exact number depends somewhat upon the interpretation of a "new" area—whether it should be called a new pool or a long extension of an older pool. In some places this determination cannot be made until more wells are drilled within the area. Therefore, the figures given

Jan 1, 1940

By T. Matsui

Many existing bridge abutments on the soft ground laterally move and their many damage examples have been reported. An essential cause for the troubles of the lateral movements may be the lack of examinations for the lateral earth pressure acting on its foundation piles. In the present paper, actual movement condition of existing bridge abutments is first summarized, and then the author establishes a practical and systematical design method for bridge abutment foundation piles, including the examination for the passive pile.

Jan 1, 2010

By Tian Li

Simple compartmental models of a laboratory batch gibbsite precipitator were used to investigate the influence of the number of compartments, the local shear rate and solids distribution on the crystal size distribution (CSD) under the conditions where aggregation is the dominant mechanism. In the current work, a power law relationship was assumed between the local agglomeration and shear rate. The simulation results showed that both the local shear rate and solids distribution have significant effect on the CSD responses, and the interchanging flows has a lesser impact with its influence strongly depending on the former two factors. Overall, the results reveal that in an aggregation controlled precipitation system, the influence of each of the factors on the CSD depends on the local hydrodynamic conditions in the precipitator, as well as their interactions.

Jan 1, 2003

At the Second Pan-American Scientific Congress, meeting in Washington, D. C., from Dec. 27, 1915 to Jan. 8, 1916, the following special topics will be discussed in each of the four sub-sections of Section VII, of which Hennen Jennings is Chairman: A. Mining.-The mining law of each country and the changes that may be made to aid the development of mineral resources. History of the mining industry in each country with reference to the beginnings of that industry. The development of the Patio process. Bibliography of mining. B. Metallurgy.-Present methods of concentrating ores and the development of concentration methods. International relations in the exchange of ores and metals. Bibliography of metallurgy. A. and B. Mining and Metallurgy.-Development of hydro-electric power for mining and metallurgy, the amount probably available, and specific benefits from its utilization.

Jan 1, 1916

By O. Akinkugbe

The safe, productive exploitation of coal in multiple-seam situations requires specific design technology. At present, there are two general design approaches that the mining engineer can use to analyze the multiple-seam problem in question, either simple empirical relationships or complex numerical models. Often, the empirical approaches are too general for the specific problem and the numerical models require too much time and expertise for the practicing engineer. In this paper, a new program designed for quickly and easily calculating the stresses, strains, and safety factors associated with basic multiple-seam mining situations is presented. The program implements a simplified, two-dimensional boundary-element method in order to model the complex multiple-seam stress and displacement interactions. The program incorporates automatic coal and gob property generation to simplify the input, and inherently calculates pillar safety factors to enhance the output.

Jan 1, 2004

By M. R. Tek, R. L. Nielsen

The scaling laws as formulated by Rapoport relate dynamically similar flow systems in porous media each involving two immiscible, incompressible fluids. A two-dimensional numerical technique for solving the differential equations describing systems of this type has been employed to assess the practical value of the scaling laws in light of the virtually unscalable nature of relative permeability and capillary pressure curves and boundary conditions. Two hypothetical systems — a gas reservoir subject to water drive and the laboratory scaled model of that reservoir — were investigated with emphasis placed on water coning near a production well. Comparison of the computed behavior of these par ticular systems shows that water coning in the reservoir would be more severe than one would expect from an experimental study of a laboratory model scaled within practical limits to the reservoir system. This paper also presents modifications of the scaling laws which are available for systems that can be described adequately in two-dimensional Cartesian coordinates. INTRODUCTION Present day digital computing equipment and methods of numerical analysis allow realistic and quantitative studies to be carried out for many two-phase flow systems in porous media. Before these tools became available the anticipated behavior of systems of this type could be inferred only from analytical solutions of simplified mathematical models or from experimental studies performed on laboratory models. To reproduce the behavior of a reservoir system on the laboratory scale, certain relationships must be satisfied between physical and geometric properties of the reservoir and laboratory systems. Where the reservoir fluids may be considered as two immiscible and incompressible phases, the necessary relationships have been formulated by Rapoportl and others.2-5 Rapoport's scaling laws follow from inspectional analysis of the differential equation describing phase saturation distribution in such systems. It will be recalled that these scaling laws presuppose three conditions: (1) the relative permeability curves must be identical for the model and prototype; (2) the capillary pressure curve (function of phase saturation) for the model must be linearly related to that of the prototype; and (3) boundary conditions imposed on the model must duplicate those existing at the boundaries of the prototype. These three requirements seldom if ever can be satisfied in scaling an actual reservoir to the laboratory system because: (1) The laboratory medium normally will be unconsolidated (glass beads or sand) while the reservoir usually is consolidated. Relative permeability and capillary pressure curves are usually quite different for consolidated and unconsolidated porous media. (2) The reservoir usually will be surrounded by a large aquifer which could be simulated in the laboratory only to a limited extent. (3) Wells present in the reservoir would scale to microscopic dimensions in the laboratory if geometric similarity is to be maintained. In view of these considerations, rigorous scaling of even a totally defined reservoir probably would never be possible. The purpose of this paper is to assess the practical value of the scaling laws in the light of the unscalable variables. This has been done by carrying out numerical solutions in two dimensions to the differential equations describing the flow of two immiscible, incompressible fluids in porous media for a field scale reservoir and a laboratory model of that reservoir. While both the reservoir and the laboratory model were purely fictional, each has been made as realistic and representative as possible. The field problem selected as the basis for the investigation was an inhomogeneous, layered gas reservoir initially at capillary gravitational equilibrium and subsequently produced in the presence of water drive. The laboratory model of this reservoir was designed to utilize oil and water in a glass bead pack. The numerical treatment employed was similar to that of Douglas, Peaceman and Rachford6 and it included both capillary and gravitational forces as

By W. Stahl, K. Keller

In addition to classifying bulk material, vibration screens are commonly used in dewatering. However, the lack of a comprehensive physical theory of dewatering often leads to difficulties in the design and operation of the vibration screens. First, in this report, the dewatering of bulk material are shown based on a physical model. Because of tile oscillatory motion of the liquid in the bulk, the inertial force of the accelerated liquid and the dripping of water out of the bulk or screen must be taken into special consideration. The physical model put forward shows the effect of the various operations parameters of dewatering screens. A comparison between dewatering theory and practice are shown by measurements using coal, limestone, etc. Dewatering measurements conducted on a vibration screen demonstrated that different vibration frequencies and rates of acceleration lead to different residual moistures. Finally, the possibility of improving vibration dewatering is described.

Jan 1, 1998

By Richard McCaffery

WHEN we began the study of blast furnace slags we limited our work at first to a study of those slags containing only lime, alumina and silica. On our paper1 on some of the results of this first work, the solubility of sulfur in slags containing no magnesia was reported and the question of sulfur solubility and slag viscosity discussed. There has been, for a long time, a very great difference of opinion among metallurgists as to he effect of magnesia in blast furnace slags, and the literature is full if expressions of the most contrary opinions on the subject. As a result, our next publication' developed the constitution of slags considered as a four-component system, silica-alumina-lime-magnesia, and advanced an explanation of slag structure which accorded with the facts and with scientific theory. The present paper continues our study of the general subject of slags. As blast furnace slags are included in the silica-alumina-lime-magnesia system, which is a particular case of four-component solutions, we have determined that there are 22 components Table 1), which may enter into the silica-alumina-lime-magnesia system and that 10 or 12 of these components may be present in blast furnace slags which are within the ordinary ranges of composition. To cave a very definite conception of the behavior of these components in a slag, we have developed the theory of the cooling of a four-component solution from the liquid state to the solid and the conclusions that we obtained have been made use of in this paper. On account of the importance of the four oxides and 18 compounds which enter into the silica-alumina-lime-magnesia system, some method of calculating the percentages of the various compounds that are present in the slag when the percentages of the oxides are given, seemed very desirable and we develop L method later herein for doing this, and finally we give illustrations of the composition of a wide series of blast furnace slags and show some applications of these composition data.

Jan 1, 1927

By Javier Baladron, Mijail Villar, Brandt Henriksson

"In this presentation an overview will be given of what has been observed by the authors in the copper concentration industry, with a large diversity of tailing thickeners operating under different conditions, although many of them are located in the same neighborhood. A closer look will be taken at the reported performance from different sites and from different thickener designs, either conventional or high rate, including those that were retrofitted, regardless of the thickener brand. An analysis is also made of the generic correlation of the size of the thickener and the performance in terms of solids loading (or unit area) and % solids. The paper envisions a technology development route, makes a brief analysis of the economic impact of the suggested route and points out the need for development in technologies around tailings thickeners, such as automation, yield stress measurement, slurry pumping and construction methods."

Jan 1, 2014

By James J. Scott

I am indeed honored to be the 1991 recipient of the Daniel C. Jackling Award. To be voted this honor by my peers in the Society for Mining, Metallurgy, and Exploration and AIME means more to me than I can truly express. Daniel Jackling's position and prominence in the mining industry first came to my attention in the fall of 1949 when I transferred from Wisconsin Institute of Technology, then a three-year school, to the Missouri School of Mines to complete my last year for a bachelor's degree in mining engineering. I played basketball in the Jackling gym and ran track on the Jackling field. I didn't know a lot about Jackling then, except he was an honored graduate of the school and, obviously, supported the school financially. Over the years, Jackling's name kept coming up. He was a man with a reputation for being a doer, a mining leader who was always a step ahead, a mining engineer who knew how to motivate men in the working place, to organize mining systems, to finance and organize corporations. to open up new, low-grade ore bodies for exploitation. If Jackling were alive today, I would expect he would bean excellent candidate to apply practical rock mechanics to his projects. Looking over the list of Jackling Award recipients, I have known many, have met many personally and had a few who were dear friends that affected my own professional life. Ab Shoemaker, '58, and I consulted at the White Pine Copper Co. on mining problems in the 1960s. We arranged for our visits to the mine to coincide so that we could collaborate on our ideas. I would rent an auto and drive for Ab. He said he was the only mining engineer in the country that had a PhD for a chauffeur. James Boyd, '67, was my mentor as regards the White Pine Rock Mechanics Program that we organized in 1963. Only through Boyd's forsight. leadership, dedication and willingness to spend money on research and development did the Practical Rock Mechnics Program at White Pine succeed. He never wavered in his support to that program or to me personally. Tom Howard, '75, was my predecessor in 1970 as Director of Mining Research for the US Bureau of Mines. When I joined the Bureau in August 1970, he had the research centers up and running. Any successes I may have had with the Bureau of Mines were due in great part to Tom's leadership and organization throughout the 1960s. Gene Cameron, '68, was my teacher at the University of Wisconsin and I remember him fondly. He was the one professor who lectured in a manner that made me welcome going to his classes each day, a truly remarkable educator. If you have come today to listen to me talk about instrumentation, rock properties, stress-strain relationships, rock mechanics theory, etc., you will be disappointed. Large volumes of data have been collected by well qualified theoreticians to define stress-strain conditions in mines. Unfortunately, very little of this data has been used by industry due to the lack of initiative and understanding by the researchers to the true problems of implementation in the industry. I hope my remarks will assist future investigators to work through the maze of operational problems so they will experience the satisfaction of seeing their research used. I fully realize that the Jackling Award is given by the Society for Mining, Metallurgy, and Exploration and is primarily offered for accomplishments in hardrock mining. I have found it impossible to separate hardrock and coal mining when I talk about "Applied Rock Mechanics." There is too much overlap and the same mechanics principles are applied to both. For example, coal mine designs have been applied to salt, trona and potash. Also, the original layout and design of White Pine Copper Mine was based on coal mine designs. Any developments to apply rock mechanics ideas must

Jan 1, 1992

By S. Mathur

Future Florida phosphate reserves contain higher MgO than presently mined deposits. The high MgO content is contributed by dolomite and Mg-rich clay, palygorskite. Selective flocculation was attempted to reduce the MgO content of apatite in synthetic mixtures of apatite with dolomite and palygorskie. Mixed mineral selectivity was predicted in the apatite-dolomite and apatite- palygorskite systems with Poly(ethy1ene oxide) (PEO) flocculant. Loss of selectivity in the mixed mineral systems was primarily attributed to heteroflocculation, which was minimized by addition of a Site Blocking Agent (SBA), a lower molecular weight fraction of PEO, prior to addition of the flocculant. A 80:20 mixture of apatite-dolomite (or palygorskite) was upgraded as 95% apatite at more than 80% recovery level in the product fraction.

Jan 1, 1995

By A. Gatti

Studies were made on the system iron plus alumina. Various methods of dispersing and various amounts of alumina were used. Powder metallurgy techniques were used to produce the final product. Microstructures and some mechanical properties are presented. Alloys containing up to 16 pct alumina by weight are ductile at all temperatures tested. The ivon-alumina materials have a higher yield stress and improved creep resistance over that of pure iron. SINCE the development of SAP' an A1- Al2O3 powder metallurgy product, great interest has been shown in the development of a SAP-like structure in metals and alloys other than aluminum. The outstanding properties of this class of materials are: 1) Good creep resistance at high temperature. 2) High yield strengths and high hardness at high temperatures. 3) High recrystallization temperature. However, the lack of ductility and formability has thus far limited the applications of SAP-like materials. The following report deals with methods of dispersing A12O3 in Fe, processing of powders into rod, structures produced after processing, and mechanical properties of the iron-alumina material produced. Methods of dispersing the alumina and also the volume fraction of alumina added were varied. MATERIAL Powder Processing— Four methods of obtaining dispersions of alumina in iron were studied. 1) Oxidation-reduction of a Fe + 8 pct Al alloy. .2) Coprecipitation of Fe(OH)3 + Al(OH)3 from aqueous solution. 3) Colloidal mixing of Fe,O3 and Al2O3. 4) Colloidal mixing of Fe powder and A1,O3. Fig. 1 is a processing flowsheet which outlines the processing steps taken to produce a final extruded bar 1/4 in. in diameter and about 30 in. long. The - 100 mesh iron-aluminum alloy was oxidized by placing a thin layer of powder on an alumina plaque. The reduction step was modified to include 1/2 hr at 1000°C since the powders tended to become pyro-phoric unless sintered slightly after low-temperature reduction. Compacting was done in a 1-1/8-in.-diam pressing die. The slugs produced averaged 1 in. in length. The billets were encased in low-carbon steel cans shown schematically in Fig. 2. The blank is included for structure and property comparison purposes. TESTING PROCEDURE All tests were made on as-extruded material.

Jan 1, 1960

By LeJuge G. E, McKenzie C. K

Innovative mining and blasting techniques were demanded at the Richmont Mines, Francoeur Mine in Quebec, Canada, by a narrow, shallowly dipping high grade gold ore body. The ore body being mined occurs as a thin tabular deposit varying in thickness between 1.5 and 3.7 metres, and dipping at 36¦. The mine proposed experimenting with open stoping techniques using small diameter drill-holes. The hangingwall required progressive, full face rockbolting after each production blast, utilising a specially manufactured machine which provided access to the hangingwall for both scaling and bolting. Blasted material is mucked from the stope by scraper and hoisted directly to surface without benefit of primary crushing.

Jan 1, 1992

Reduce longwall shearer operators' dust exposures by more effectively suppressing the dust generated by the upwind cutting drum. Approach Direct more of the shearer water supply to the upwind drum, thus reducing the shearer operator's exposure to respirable dust while making more efficient use of water. How Proportioning Permits More Efficient Use of Water On most longwall mining operations, the cutting action of the shearer drums is the primary source of dust. Al-though the amount of dust generated is directly related to the amount of coal and rock cut by the drum, the exposure or the shearer operators to dust depends more on their work position relative to the upwind drum. When cutting with the airflow, the upwind drum, cutting bottom coal and floor rock, is the primary generator of dust reaching the operators. The lead drum is downwind of both shearer operators and is thus of less concern. (See diagram). When cutting against the airflow, the lead drum is upwind-taking a full cut, including roof rock-and both shearer operators may be exposed to very high levels of respirable dust. Currently, water sprays mounted on the cutting drum provide the most effective method of controlling dust from longwall shearer drums, and all longwall mining operations use some type of bit flushing or cavity filling water spray system on the cutting drums. Bureau surveys of longwall operations, conducted as part of its research program to reduce respirable dust, have indicated that six longwalls with better than average compliance records use higher than normal water flowrates to the cutting drums. The average water flow to the shearers at these six operations was approximately 60 gpm-about 50 percent more water than is normally supplied to double-drum longwall shearers.

Jan 1, 1982

By A. J. Metz, Roberto Nevarez

One popular method to stabilize slopes is the use of deep foundation elements to support lateral loads from an unstable soil or rock mass. Drilled deep foundation elements are often selected due to local availability of equipment, access concerns, cost considerations and post-construction aesthetics. Often, one or more rows of deep foundation elements are installed running parallel to the slope. The elements in each row may or may not be connected through a cap beam. They work primarily in bending, and resist slope movement by transferring the earth pressures down below the potential slip surface. Design of these systems considers the effect of arching

Nov 1, 2023

By G. F. Willis

Gold mineralization in the Mesquite district is hosted by a series of Jurassic amphibolite grade metamorphic rocks which have been intruded by a Cretaceous leucogranite pegmatite. A series of northwest trending, high angle, normal faults have apparently acted as a structural locus for mineralized epithermal fluids and thus economic concentrations of gold in the Big Chief orebody. Late Tertiary fault reactivation has bounded the fault and fracture controlled mineralization. Popular theories of ore genesis call on, (1) Tertiary detachment faulting, (2) the Cretaceous intrusive, or (3) the opening of a dilational jog between regional dextral strike-slip faults as a source powering the gold bearing hydrothermal fluids.

Jan 1, 1988

By Xiao Huang, Dongmei Wang, Prakash Patnaik

Further increase in gas turbine engine temperature necessitates continuous development and advancement to thermal barrier coatings. While tremendous effort has been devoted to developing new thermal barrier coating materials and processing methods in order to decrease the thermal conductivity, limited attention has been paid to radiative thermal transport through coatings. It is the purpose of this study to develop a new layered coating structure that can be used to effectively reduce the both radiative thermal transport as well as thermal conductivity, and to demonstrate the mechanism and effectiveness of the proposed multilayered structure. Mathematical modeling based on the multilayer quarterwave stack and simulation results are presented.

Jan 1, 2004