Search Documents

By V. Caps

Gold has been often used as an alloying component in order to increase or modify the catalytic properties of an active metal. For example, in the hydroconversion of methylcyclopentane, Riahi et al [1] shown that the addition of gold to palladium or platinum enhances the activity which becomes greater than that of the pure metals whereas the selectivity towards products resulting from ring expansion increases. Molenbroek et al [2] presented a detailed study on Ni-Au catalysts which exhibit activity for steam reforming and have been proved to be more resistant toward carbon formation than the pure Ni catalysts. Blocking of highly reactive Ni edge and kink sites by Au atoms is assumed to be the reason for the increased robustness of the Ni-Au catalyst. Nevertheless, the own catalytic properties of pure gold have been almost ignored up to the pioneering work of Haruta et al [3] which demonstrates the high activity of gold for CO oxidation at low temperatures. Other reactions such as WGS reaction, propylene epoxidation or benzene total oxidation have then been shown to be catalyzed by gold [4]. This discovery induced the publication of papers devoted to analyze the different factors controlling the activity of gold catalysts. Among them the most relevant appears to be the gold particle size, the nature of the support [5] and the preparation methods [6]. Clearly distinguish between support and size effect is not straightforward. Indeed, the calcination step often needed to synthesize supported catalysts on different supports, leads to different particle sizes showing that particle size and support are interdependent. To circumvent this difficulty, Au-based supported catalysts have been synthesized by using laser vaporization and low energy cluster beam deposition. The as prepared catalysts have then been characterized and tested in CO oxidation reaction.

Oct 1, 2003

By David M. Spatz

The way people interact, collaborate, learn and improve can have a profound impact on a company’s efficiency, performance, productivity and return on investment. This is the motive behind corporate efforts today to replace the traditional hierarchical structure with team-oriented organization. The increased importance of communication and collaboration during the past 20 years has been propelled by rapid advances in technology and increased availability of information. Companies must take advantage of the information that is required for competitive performance and for the continued production of quality products. So it is essential that outstanding communication, cooperation and collaboration take place among multidisciplinary specialists assigned to work together to solve common problems and achieve common goals. Companies are searching for ways to increase knowledge transfer and learning, particularly among people who work on related topics. This will improve efficiency and quality and reduce redundancy and costs.

Jan 1, 2000

By Tapani Järvinen

Non-ferrous metals and metals in general are considered as being non-renewable natural resources. Metals are needed because of their excellent and irreplaceable properties. The consumption of metals, with the exception of carbon steel, is steadily growing by 1-3 % annually, and that of stainless steel as much as 3-6 %. This is a general trend, which is periodically disturbed by cyclical variations. In recent years so-called "New Economy" has become prominent in the public media and the market value of the traditional industry has been well below its real value and importance. Nevertheless, the modem society requires metals today and also in the future, and the companies using the most modem technology in a responsible way and innovative solutions not only in technology, but also in everything they do will survive. This paper describes the role of Europe as a producer of primary base metals and as a supplier of technologies in the base metals industry. It concentrates on the development and commercialization of technologies and project implementation in the metallurgical industry. As one example of a European approach to these matters the paper presents Outokumpu' s response to the future challenges in the base metals industry. Outokumpu Oyj is one of the leading metals and technology companies in the world of stainless steel, copper, zinc, and sales of technology in metals and minerals businesses. Outokumpu applies its knowledge of metals and processing to generate value for its customers and shareholder. Everything we do, we do in an economically, environmentally and socially responsible way.

Jan 1, 2003

By D. B. Jenkins, D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity that exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into a worldwide business with a capacity of about 500 kt/a. This paper will present data on the chemistry, mining, manufacturing, and applications for acid-activated clays.

Jan 1, 1988

By C. D. Anderson

A variety of processing technologies exist for recovery from both primary and secondary sources of rhenium. Currently, there are no known primary rhenium deposits, thus, the method in which primary rhenium is produced is dependent on the commodity of which it is a byproduct, e.g., copper, molybdenum, uranium, etc. In addition, focus on the recovery of rhenium from secondary sources, such as alloy scraps and catalysts, is continually growing. This paper presents a review of both primary and secondary processing technologies for the recovery of rhenium. Key Words: Rhenium, Ammonium Perrhenate, Extractive Metallurgy

Feb 27, 2013

Most of the gold reef mined today in South Africa is approximately 1 m in width with slopes about 30 m long. To prevent production interruptions it is essential that the stopes should not be blasted in sections. The shortage of experienced labour and arduous working conditions at the face dictate the need for simple blasting techniques.Hence, a pyrotechnic blasting system of sequential firing is in use at present, although research work to improve this technique is in progress.

Jan 1, 1985

By Tanner A. C, Harraway D. H

Various circuits were tried at Mount Isa Mines during the period 1959 to 19G3 with the objective of improving the differential flotation of galena and sphalerite. Many benefits and disadvantages of the various circuits were revealed. An analysis' of ore characteristics and their effect on flotation was made -and resullted in the design of a proposed circuit which is currently in the process of installation.INTRODUCTIONSince 1936 when lead-zinc sulphide flotation commenced at Mount Isa, at least three types of ore have been encountered.Each ore has presented problems to flotation metallurgists.The three types of ore are,1. partially oxidized upper level sulphide ore,2. Black Star ore from the lower levels with its carbonaceous fraction, and3. Black Rock ore which is similar to 2, but more free milling.In retrospect a number of the metallurgical successes of the past were short lived. Often flowsheets or 0perating practices were designed to solve a single metallurgical problem associated with the current ore being treated. As the ore changed the problem would vanish and the method originally taken to counter the problem could become unnecessary or deleterious to the treatment of the new ore. The general lesson learnt from-the past-is-that thetreatment of Mount Isa lead-zinc ore involves a number of equally major problems...

Jan 1, 1963

By Donald Carlisle

"IntroductionTHE OPINION is held by many persons outside the mining industry, and by some within it, that mine •operators customarily find it advantageous to mine •only the richer parts of orebodies and to leave behind, perhaps permanently, leaner material which could be mined only at a lesser profit. This opinion and the inference which might be drawn from it that 'gutting' of mineral resources is a common feruture• of the mining industry are prejudicial to the intertsts of the industry and deserve careful scrutiny. Oddly enough, a theory of mine economics which gives much support for the opinion was advanced first by members of the mining profession itself, has been repeated •several times in mining literature, and to my knowledge has never been adequately refoted.According to the theory, selective mining of the rich ore first on a large scale will yield substantial gains and these gains do not merely reflect the desire of 'money minded investors' for a quick return but derive from the logical application of compound interest rates and the concept of ;present value. W. O. Hotchkiss and R. D. Parks (1) illustrate the reasoning with a hypothetical example in which an orebody of 4,000,000 tons may be mined either in its entirety in forty years at $1.00 per ton profit or selectively with the recovery of only the richest half in twenty years at $1.50 per ton profit. They show that, with Hoskold rates of 4 and 8 per cent, the present value of profits from mining only the richer 2,000,000 tons exceeds the present value of profits :from mining the whole orebody by about 20 per cent."

Jan 1, 1953

By Mohamad Hussein

Low strain dynamic tests are performed to evaluate the structural integrity of driven or cast-in-place concrete piles. This type of testing requires minimal pile preparation, and is simply performed by attaching an accelerometer to the pile head and striking the pile head with a hand held hammer. The measured data is processed by a dedicated system, inspected for wave reflections, and interpreted based on one dimensional wave propagation theory. Piles are normally tested shortly after installation so that problems can be identified early and corrective measures taken before construction of the superstructure. However, evaluation of existing foundations is occasionally required. Often, pile installation records are not available rendering impossible any rational foundation reanalysis. This paper discusses three case histories where low strain dynamic measurements allowed determination of pile lengths and structural integrity under existing structures where pile heads were not accessible.

Jan 1, 1992

By Frederick G. Coqueron, Joseph E. Pogue

The purpose of this study is to present the results of a detailed survey of the financial and operating aspects of 30 oil companies comprising a major sample of the American petroleum industry. This review supplements a previous paper entitled "Capital Flow and Capital Formation in the Petroleum Industry, 1934-1941,"a and deals not only with a longer period but also gives new and more revealing analyses of the capital movements and characteristics. The data are gathered from published financial statements of the companies, especially the annual reports to stockholders and Form 10-K to the Securities and Exchange Commission, supplemented by confidential information. The 30 oil companies covered by this study are listed on the leading stock exchanges and for the purpose of analysis are grouped as follows: 9 companiesb engaged principally in crude production, 4 companiesc with production averaging in excess of refinery requirements, and 17 companiesd with refinery throughput in excess of crude production. These samples are sufficiently broad and representative to constitute norms against which individual company performances may be profitably compared. The 30 companies in 1942 produced 54 per cent of the Nation's total output of crude oil and refined 79 per cent of the country's crude run to stills. The financial data apply predominantly to the domestic oil business, although 15 of the companies have investments and operate facilities in foreign countries. The net value of these foreign holdings amounted to 724 million dollars, or 12 per cent, of the combined net assets of the 30 oil companies at December 31, 1942.

Jan 1, 1944

By A. L. Mula

Pasaremos revista brevemente a 10s fundamentos de 10s ciclones, considerando un ciclón típico. Los datos gráficos disponibles en la literatura han sido convertidos en ecuaciones matemáticas por conveniencia. Se suministran los procedirnientos preliminares para seleccionar y diseñar tanto los ciclones como las bombas, y se facilita con algún detalle un ejernplo de cálculo para un hipotético circuito de molienda. En general, debe consultarse a 1os proveedores de ciclones y bombas para determinar un disefio definitivo. Algunos suministradores de ciclones emplean normalmente computadores digitales para el diseño definitivo con objeto de asegurar una gran precision.

Jan 1, 1982

By J. L. Walter

Tungsten ingots with and without small amounts of aluminum, silicon, and potassium were prepared by conventional powder-metallurgy techniques and hot-rolled to 0.001-in.-thick sheet. The ingots were rolled three different ways: I) initially cross-rolled, then straight-rolled; 2) straight-rolled, and 3) straig-ht-rolled, then cross-rolled. Total reductions were 99.8 pct. Samples of the sheet were annealed, in vacuo, at temperatures from 1200" to 2200°C. Substructures and textures were determined by transmission electron microscopy and X-ray diffraction. The doping agents were found to form particles of mullite (Al,Si,O,,) which, on rolling., appear to form strings of particles aligned parallel to the rolling direction. These strings of purticles are associated with an increase in the recrystal-lizution temperature from 1400°C for undoped sheet ThE addition of small amounts of aluminum, silicon, and potassium to tungsten has a profound effect on the grain structure of drawn and recrystallized wire.'" The grains generally do not occupy the entire cross section of the wire and have lengths many times the wire diameter. The grain boundaries are, in general, nearly parallel to the wire axis and have long ''fingers" projecting one into the other as may be seen in Fig. 1, a longitudinal section of recrystallized doped wire. When unsuitable additions or no additions are made or the wire is not sufficiently reduced during draw- to 2000°C for doped sheet. The particles also limit lateral grain growth while allowing growth parallel to the rolling direction. This results in the formation by primary re crystallization of large highly elongated grains of specific preferred orientation. The undoped sheet recrystallized to small equiaxed gains. The preferred orientations of the large grains were determined from axis density plots to be (113) (691). (0i3) (362), (116) (304) types for the initially cross-rolled then straight rolled material. These orientations are similar to the orientations of the large elongated grains in doped and heavily drawn tungsten wire. The nucleation of the large grains appears to occur by recovery of certain of the polygonized regions of specific orientation, followed by strain-induced boundary migration.

Jan 1, 1968

By Paolo Bevilacqua, Paolo Antonini, Lorenzo De Lorenzi

"Ceramic production requires large quantities of K-feldspar, which is commonly sourced from granites, alkali-granites, and feldspathic sands. These rocks contain other minerals, such as quartz and plagioclase, which are undesirable for ceramic production. Due to the coarse mineral grains that constitute these rocks, a reasonable liberation is achieved at a relatively coarse particle size.The feasibility of feldspar-quartz separation using a dynamic dense medium separation system has been investigated as an alternative to flotation techniques. The use of a two stages cylindrical vessel (Tri-Flo) was preferred to a conical vessel, due to the improved separation efficiency.In a full-scale processing plant, a dense medium separation process can be used as a K-feldspar preconcentration step. This reduces the amount of material to be treated in the more expensive processes, such as finer comminution, flotation or magnetic separation.A comparison between commercial raw materials for the ceramic industry and the “rich in feldspar” products of the Tri-Flo process is reported, and the validity of the process is demonstrated."

Jan 1, 2003

By P. Wells, P. Quinn

"A moveable flotation miniplant was designed and constructed at the research laboratory of Inco Technical Services Ltd. to address the need for flowsheet development with a limited amount of ore (such as drill cores). It consists of one rod mill, two regrind ball mills, one vibratory screen, 24 flotation cells of various sizes and two Venturi aerated flotation columns. The setup has continuous monitoring capability for pH, dissolved oxygen, oxidation-reduction potential, conductivity and temperature in conditioning tanks and flotation cells. Various options regarding flotation reagents, circuit configurations, and fineness of primary grind and regrind can be readily evaluated. The throughput of the miniplant is 20 – 30 kg/hour ore.Unit operations such as flash flotation, magnetic separation and gravity concentration can also be evaluated as an integral part of an entire flowsheet development.This communication describes the basic design features of the miniplant and some examples of applications are given.INTRODUCTIONInco operates numerous mines in Sudbury and Thompson and will shortly bring the Voisey’s Bay mine into production. It has long been recognized that the ores from different mines or from different depths of the same mine can give different responses in flotation. There is a growing need to properly evaluate the ores before feeding the mill to maximize the return of the mine/mill operation. Inco Technical Services Limited at Sheridan Park, Mississauga, Ontario has developed a batch laboratory procedure to address this issue. The results are considered in the overall economical assessment of new mine operations.For ores that cannot be processed by the existing mill operations or that will be processed by a new mill, it is necessary to develop a flowsheet that can maximize the economical return of the mine/mill operation. While recognizing the importance and contribution of the laboratory batch flotation procedure, it does not generate reliable data for flowsheet simulation and design. A full-scale pilot plant campaign is normally required to obtain the design data but often this is not possible due to a limited amount of ore obtainable from the drill core. A small-scale pilot plant (mini pilot plant or miniplant) capable of processing 20-30 kg/h ore can provide this data prior to a full-scale pilot plant campaign. A miniplant can also be used to optimize the circuit configurations, reagent additions and recycle options of process water before pilot plant work and can be used to test a different flowsheet configuration for an existing mill before re-piping a plant circuit."

Jan 1, 2003

By Nekitel S, Arumba J, Kopi G, Findlay RH

The Kainantu area lies within the composite Scrapland terrane which is composed of Mesozoic metamorphic and intrusive units, overlain by Cenozoic marine sediments, volcanic and intrus-ive units and Quaternary fluvial sedi-ments.Four deformations (Dl, D2, D3, D4) are recognised within the Mesozoic sequences, which consist of greenschist to amphibolite facies schist derived from felsic to intermediate pyroclastic rocks and pelitic sediments. The second, third and fourth fold events are present in the Cenozoic sequence, and these rocks are broken by thrusts related to northwest trending D3 folds. South-dipping, possibly lystric, normal faults are recognised and may be related to uplift and exposure of the metamorphic rocks as core complexes.Known mineralisation in the area consists of gold and copper skarn deposits, porphyry copper deposits, shear-hosted gold deposits, epithermal vein deposits and gold placer deposits. Over 35 hard rock and 18 gold placer deposits are known within the area. Of significance are the Kathnell shear-hosted auriferous quartz veins; such structurally controlled veins may be more widespread than proposed prev-iously and offer a new exploration target.

Jan 1, 1994

By Brian H. Kaye

Efficient design of grinding circuits for efficient production of ultrafine material requires rapid feedback of information concerning the fineness of material leaving the grinding device Generating this information requires efficient sampling and adequate rapid characterization of the material leaving the grinding machinery Recent developments in electrooptic inspection of dry and wet material leaving a grinding device are critically reviewed New methods for characterizing ultrafines are discussed A rapid operating automated cybernetic (intelligent) permeability device for automatic control of grinding circuits using Blaine Index and other fineness indices is described

Jan 1, 1983

By M. Reza Saberi, T. Ted Miyake

Driven piles are a common tool in any engineer’s toolbox for supporting large structures over very soft ground, especially in high seismic risk zones. Challenges include achieving sufficient vertical and lateral load capacities within the constraints of pile spacing and geologic conditions. This was the case for a project in Orange County, California with a state-of-the-art, $180 million plant for biosolids processing, biogas management and energy recovery located in marshland next to an existing waste water treatment plant. The new construction for the Irvine Ranch Water District included a 70-foot (21 m) tall building and three closely spaced, 90-foot (27 m) high, 65-foot (20 m) diameter, egg-shaped steel digester tanks. The lower 35-feet (11 m) of the tanks were constructed below ground level. The site was underlain by up to 45 feet (14 m) of highly compressible peat and organic clays with standard penetration test (SPT) blows as low as 2 blows/ft (30 cm). Some of the peat layers had measured in-situ dry densities of less than 30 pcf (480 kg/m3) with moisture contents of over 250 percent. The soft clays and peat were underlain by a dense layer of sand and gravel at depth. Groundwater was very shallow. While nearby sites were designated by others as seismic site class “D”, this site was clearly class “F” (SF) which required site specific seismic hazard and time history analyses. Six recorded time histories were selected from the 1994 Northridge, 1989 Loma Prieta (California) and 1999 Chi Chi (Taiwan) earthquakes for the ground motion analysis considering the magnitude of the earthquake, distance to the source, characteristics of the earthquake source (i.e. type of fault displacement), peak ground acceleration, local site geology, station type (i.e. free-field or small structure stations), and spectral content that was similar to the period range of interest. Following ASCE’s Guideline Document 7-05, a site-specific horizontal acceleration response spectra (ARS) was developed for the maximum credible earthquake (MCE) associated with the site.

Jan 1, 2018

By H. W. Hitzrot

THE new 4800-ton fine-grinding plant at the Hollinger Consolidated Gold Mines property at Timmins, in the Porcupine district of northern Ontario, went into operation in November 1937, and represents the culmination of an experimental program. The plant is a moderately low rectangular building of hollow tile on a steel frame, large enough to house four 7 by 15-ft. ball mills, with a 12 by 27-ft. classifier beside each mill. At one end is space for the addi-tion of another mill and classifier or a mill and classifier for the regrinding of table concentrates. This regrinding is now done in the old grinding department of the main mill building. Also within the new building are the four 6-in. sand pumps for lifting the product from the low-dis-charge ball mills up to the classifier feed launders and the containers and appurtenances of a complete dust-collecting system. Together with the usual overhead crane, these constitute the major units of equipment within the new plant. The location is at the lower end of the main mill buildings toward the old tailings pond, now so neatly leveled off and sodded to rival the very best of our own W.P.A. projects. Close by the new grinding plant is a large dome-shaped structure-the new fine-ore bin designed and built by Mr. Longmore and the Hollinger milling and engineering staffs. There are four separate automatically loaded inclined belt conveyors leading up from the bottom of the bin to the grinding plant. Each belt is equipped with a recording weightometer, in the grinding building. The whole structure and the machinery within it give the impression of permanence and a carefully integrated design with close attention to details, giving the operators every advantage for consistently good work.

Jan 1, 1939

By Ananda M. Wijesinghe

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies at the time of the Symposium.

Jan 1, 1986

By James M. Tennant

In the mid 1970's, American Electric Power significantly expanded its internal coal production. This involved opening several large mines in seams that had never been mined on a large commercial scale before. One of the mines opened was the Martinka No. 1 Mine which is located approximately five miles southeast of Fairmont. The mine was originally designed for room and pillar mining with continuous miners but was later modified to permit the utilization of longwalls and continuous miners for entry development. The coal seam to be mined was the Lower Kittanning which averages fifty-six inches. In order to successfully mine this seam, it required that the mine design recognize the effect caused by the dip of the seam which averages four percent to the Northwest with a maximum of sixteen percent for short distances and a relatively low cover. In fact, seventy-four percent of the reserves have cover of less than four hundred feet. Also, the core hole data indicated that the immediate roof varied from zero to eighteen feet of shale with two to forty-five feet of sandstone overlying the shale.

Jan 1, 1982