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By P. Huang, D. W. Fuerstenau

Various factors that control the natural flotability of talc, including differences due to crystal face and edge effects, were delineated. For study of talc depression phenomena, dextrin was used as a model depressant. For the enhancement of talc flotation, dodecylammonium acetate (DDAA) was used as the collector. The interaction of DDAA with talc was assessed by flotation experiments and electrokinetic (zeta potential) measurements, from which the role of hydrophobic bonding can be demonstrated. The results presented in this paper provide useful information on how the crystal chemistry and surface chemistry control the electrical double layer, adsorption phenomena, wettability, and flotation behavior of talc in aqueous media.

Jan 1, 2003

By Sebastian Schmuck, Petrico von Schweinichen, Dieter Senk, Mohammad Peymandar

"At Department of Ferrous Metallurgy of the RWTH Aachen University in Germany steels in the system Fe-Mn-C(-Al) are investigated and produced in the framework of the SFB 761 ""steel-ab initio"". A new world of steel grades leads to special challenges regarding the production and recycling at the end-of-life cycle of product. In order to recycle high manganese steel alloys the EAF has to be chosen preferentially. A good slag practice is necessary avoiding loss of manganese content during melting in the EAF. This paper investigates on the reaction kinetics at the interface of slag and steel containing Mn (17-22 wt.-%) and up to 3 wt.-% Al. The effect of changes in the composition of slag and steel on the interfacial reaction kinetics is studied. The thermodynamic software FactSage™ is utilized to calculate the composition of slag and steel at equilibrium.IntroductionTRIP and TWIP steels are highly alloyed steels which show superior strength and ductility when compared to standard carbon steel and stainless steel alloys. These TRIP- and TWIPsteel grades contain typically 15-30 wt.-% manganese, 0-4 wt.-% silicon and aluminum, and up to 1 wt.-% carbon. Steels containing 18-28 wt.-% manganese and 0.7-1.2 wt.-% carbon together with aluminum addition from 3 to 12 wt. -% and without silicon refer to TRIPLEX high manganese steel alloys. These alloys combine high strength at even large ductility [ 1-4]. At the Department of Ferrous Metallurgy (IEHK) of the RWTH Aachen University in Germany, steels in the system Fe-Mn-C(-Al) is under investigation at the collaborative research center, SFB 761 ""Steel-ab initio"". In this project, high manganese alloyed TRIP and TWIP steels are in the focus.The mechanical properties such as high strength and high ductility make this kind of steels perfect candidates for impact absorption applications in auto body such as vehicle doors and bumpers [2, 5]. With increasing the use of TRIP-, TWIP- and TRIPLEX-steels more high manganese steel scraps will be available at the end of life cycle of products, which need to develop the technologies and metallurgical processes to recovery of high manganese steel. A new steel grade brings new challenges in recycling. In order to recycle high manganese steel scraps the electric arc furnaces (EAF) have to be chosen preferentially [1]. Nevertheless it's not easy to prevent the manganese loss during the process in EAF. During the oxygen refining of high manganese molten steel in EAF the manganese content decreases strongly by oxidation and vaporization, which is affected by slag composition, slag properties such as basicity and viscosity, slag weight as well as melt temperature [6-8]."

Jan 1, 2014

By M. X. Huang, Y. Z. Li

The titanium diboride (TiB2)-reinforced steel composite, designed for automotive applications, exhibits a combination of high isotropic Young’s modulus and low density as compared to existing advanced high strength steels (AHSS). The steel-based composite is produced by in situ precipitation of TiB2 particles during eutectic solidification followed by hot rolling, and its microstructure displays a homogeneous distribution of both large primary TiB2 and small eutectic TiB2 particles in the ferrite matrix. Instead of interfacial debonding, particle cracking is the primary mode of damage, revealing very high interfacial strength. To investigate the intrinsic interfacial strength, a hybrid method combining both nanoindentation and finite element analysis (FEA) was used. A micron-sized sample containing a single crystal TiB2 attached to the ferrite matrix was fabricated by focused iron beam (FIB), and was compressed using nanoindentation with a flat indentation tip. By combining the compression and FEA results, the interfacial strength was therefore determined.

Mar 1, 2017

By John Carson

Belt feeders are commonly used to meter the flow of bulk solids from bins and hoppers. If the interface between the hopper outlet and belt feeder is not designed correctly, flow from the bin may be severely compromised, resulting in problems of no-flow, segregation, flooding, etc. By knowing the flow characteristics of the bulk solid being handled and applying proven design techniques, such problems can be avoided. Relevant bulk solids flow characteristics are identified, along with measurement techniques. Design procedures for correcting problems with existing feeders as well as proper design of new feeders are presented, along with case histories of successful application of these procedures.

Jan 1, 2008

By Gordon M. Elliott

Health risk underlies all of today's environmental regulations. Mine Manager's are no strangers to risk, but risk in the context of mine management is not the same as risk in the context of environmental regulation. One of the risks facing the mine manager is whether the mining operations meet environmental compliance standards. These standards are defined in terms of the frequency of occurrence of adverse health effects in an exposed population (i.e., health risk). Demonstration of compliance necessarily involves mathematical modelling and selection of values for input variables. What is not immediately apparent is that the method of estimating the human health risk has a significant influence on remedy selection and the amount of money spent at suspected contaminated sites. Using a hypothetical, mining-related example, this paper illustrates the disassociation between the current deterministic approach to health risk assessment and cost-effective decision making. This paper also illustrates how the probabilistic approach to health risk assessment provides a more realistic characterization of health risk and enables mine managers to identify cost-effective remedial strategies for the site.

Jan 1, 1992

By C. M. Loeb, A. M. Gaudin, J. H. Brown

THE object of most size reduction operations in the mineral industry is to liberate the grains of valuable minerals in the ore from those of the gangue. This is usually accomplished by crushing and grinding the entire mass of ore until there is only a small probability that any single particle contains more than one mineral. During this size reduction only limited control exists over size or composition of the particles exposed to the breaking action, and there is no control over the paths followed by cracks generated during the operation. This lack of control usually results in overgrinding and in production of large quantities of very fine material. The first detriment, overgrinding, is costly in itself, but when combined with the second factor it is doubly so. Not only is the fracture of a free particle unnecessary-the fracture of these particles may also make subsequent separation operations difficult, inefficient, and wasteful. It has been pointed out' that if the object of size reduction is to liberate the valuable mineral component of the ore then, ideally, fracture should follow intergranular paths to the exclusion of trans- granular ones. This would result in liberation of the valuable minerals with as little size reduction as possible. This ideal comminution operation is referred to as intergranular comminution, and it was the object of the investigation to determine the extent to which it could be developed by heat treatments.

Jan 4, 1958

By Jerrold J. Marcus

United states reserves of oil and gas have been steadily declining while consumption of petroleum products has continued to increase. The nut result has been an ever increasing shortfall between supply and demand. This imbalance has been made up by imports of both oil and gas causing a strain on the United States Balance of Payments. To complicate the situation further, exporting nations have recently formed a cartel and dramatically increased the selling price of petroleum products. To meet U.S. energy demand, increased attention has been drawn to the production of synthetic oil and gas from coal. To date, considerable research has been conducted and is continuing on various processes for liquefaction and gasification of coal. Some of these processes are now in the pilot plant stage and at least one demonstration plant has been proposed. The coal conversion complexes envisioned will be very large, requiring substantial capital investments and abundant reserves of coal. Coal production to feed these proposed complexes has been estimated on the order of 75,000 tons per day. With the viability of these projects becoming economically attractive, the Office of Coal Research initiated a contract with Fluor Utah to determine and define the problems of surface mining coal at very high mining rates, under varied physical, geographic, and climatic conditions. The flow of recent events in the Middle East has created a greater sense of urgency for this study.

Jan 1, 1975

By Alden B. Carpenter

Oil-field brines have been collected and analyzed from Jurassic and Cretaceous rocks in the Mississippi Salt Dome Basin, from Jurassic and Lower Cretaceous rocks, southwestern Arkansas, and from Ordovician and Silurian rocks, southern Michigan. All of these brines are genetically related to evaporites and appear to be brines expelled from halite-bearing rocks, presumably during compaction. The brines in rocks closest to the halite-bearing rocks are uniformly low in lead and zinc suggesting that the metals in metal-rich brines are not acquired within evaporite sequences. The metals in metal- rich brines in Mississippi and in Russia appear to be derived from red beds and may have been originally associated with ferric iron oxyhydroxides. Reduction of these compounds by migrating hydrocarbons appears to release lead and zinc to the associated brines accompanied by the fomation of authigenic ankerite.

Jan 1, 1979

By Natalie Zeleznik, Brian Hawkins, David Bradley, Rachel Gooding, Patrick Wilson, Brian Somes, Kevin Wegman

"To perform a probabilistic risk assessment (PRA), a method of quantifying the risks associated withinfrequent high consequence events, consequence models that generate representative estimates of human health consequences for a wide variety of representative scenarios are commonly used. Criteria that suitable models must possess include: (1) input requirements necessary to generate large volumes ofprobabilistic simulations; (2) the capability to output injuries with the necessary details and resolution;(3) the ability to capture the variety of different scenarios inherent in an assessment; (4) acceptable cost and computational requirements; and (5) sufficient stakeholder buy-in for community acceptance."

Jan 1, 2017

By Richard P. Killmeyer

In 1985 the Pittsburgh Energy Technology Center (PETC) of the U.S. Department of Energy (DOE) conducted a study to evaluate the emerging selective agglomeration processes (Killmeyer, 1985). This paper covers a recent similar study evaluating an associated technology, the emerging advanced froth flotation processes. This study has goals similar to those of the 1985 study: to evaluate the emerging froth flotation technologies collectively and determine how far they have progressed in their ability to clean ultrafine coal, and to assess the differences among the participants. The major concern again in this study was not the level of development, nor the economics of each individual process but only the current technical performance.

Jan 1, 1989

If it had not been for the almost unbelievable adventures that came before and after, the last ten months of 19 15 would have been exciting enough for anyone. As it was they were a cheerful interlude. I spent most of the time on our Warren operations catching up on a lot of underground work and visiting Ajo every few weeks to see if my Chuquicamata visit might help solve the New Cornelia problem. While the difficulties were finally solved, at times they seemed almost hopeless. About all I could do to help was to make sure that the ore sent to the pilot plants represented the average ore that must be treated in the final 5000 tpd mill. Dr. Ricketts and John Greenway worked tirelessly with the best consulting advice they could obtain. Credit for the final success was due chiefly to their efforts. Since our old group had given up its "Merry Widow" home in Warren, a few of us got rooms in the company-built Cole Building over the Warren grocery store. This included Jim Lewis, Roy Mitchell, Steve Landon, Paul Stevens, and Hubert d'Autremont who came from Duluth to join our legal staff. Later we rented a small house two blocks from the Calumet and Arizona office. With the now flourishing country club only a 10-min walk away, and an electric car running to it every half hour or so, we were able to give parties in return for the hospitality of our friends. One of the most pleasant episodes came by luck a few days after I got back from Chile. Chester Congdon, a leading director in Calumet and Arizona, with his wife and their daughters, Elizabeth and Helen, spent a couple of days at the Greenway house before making an auto- mobile trip across the desert from Tucson to Ajo. At the same time I arranged to examine the small but rich Bush and Baxter copper mine a few miles from Tucson. At a party in Warren we found we would all be staying at the Santa Rita Hotel in Tucson, and I took my South

Jan 1, 1976

By Henry Hanson

A STUDY of the ore to be treated should be the first step in deciding on a machine for crushing or grinding. Coarse crushing is practically confined to the jaw and the gyratory crushers, the large-size jaw type being often employed in large installations as a primary crusher, followed by the gyratory type for secondary reduction. In small plants where mine-run ore is reduced in a single step, either of these machines will do the work. In intermediate and fine grinding, various machines are used. The relative merit of the different types will be governed in no small measure by the size of the installation, the character of the ore to be reduced and the final product desired for subsequent treatment. It should be possible, nevertheless, with the data available, if properly classified, to arrive at an approximation of the relative efficiency of these intermediate and fine grinders. It should be possible, also, to determine the economic grinding range of the different machines. With this in mind, it will be the object of this article to indicate, in rough outline, how the data available may be classified, rather than to attempt to discuss any particular practice and compare the results with other practices. Conclusions or generalizations can not be drawn without an exhaustive classification of data; in fact, many vital points will have to be determined by additional experiments which can be carried on most advantageously in the laboratory. The expense en-tailed in such experiments would be worth while if the data obtained should lead to definite conclusions that would aid in standardizing and simplifying grinding practice.

Jan 2, 1923

By R. Kok, N. B. Strydom, P. L. Jooste, W. H. Van Der Walt

Intermittent exposures to heat, and the retention of heat acclimatization by N. B. STRYDOM, M.Sc., Ph.D. (Illinois) (Fellow), R. KOK, M.Sc. (Potch.) (Visitor), P. L. jOOSTE, M.Sc. (Stell.) (Visitor), and W. H. VAN DER WALT, B.Sc. (Potch.) (Visitor) Twenty-one heat acclimatized subjects were assessed for the degree of acclimatization attained with respect to heart rate, rectal temperature, and sweat rate during a standard four-hour heat-stress test. Thereafter, they were put on light duties in cool environm ents for four weeks, except for four hours of exposure to heat every seventh day. Their state of heat acclimatization was again assessed two days after the final week's exposure. Although heart rates and body temperatures showed significant increases over the initial values, no differences were observed in sweat rates and, in general, the subjects were rated as still adequately acclimatized to heat.

Jan 7, 1975

By Oscar A. Glaeser

MINE VENTILATION is an important factor in mine maintenance as well as having direct bearing on labor efficiency. Effective ventilation systems are costly, especially those for the deeper mines, but with intelligent direction the worth of a system is usually greater than its cost. In most mines using mechanical ventilation, and practically all deep mines, it has been found beneficial to equipment, timber, and the ground, to run the fan or fans continuously even though production has been curtailed or entirely suspended. Therefore, economies in ventilation may be overlooked when general cost reductions are necessary. The operating costs of a well-designed ventilation system should be capable of reduction during periods of curtailed or suspended operations. A mine that is ventilated by splits, or that can be sectionized, can reduce its fan-power costs considerably, and provisional divisions can sometimes be made in other mines, in which the air is ordinarily coursed through all the workings, without harmful effects.

Jan 1, 1932

By Frank Martonhegyi

"The objective of this paper is to review the coal basins in the Canadian part of the Western Cordillera to aid their understanding, and to aid in finding and proving places of economic coal mining potential. Coal occurs in eugeosynclinal basins in the Western Cordillera which evolved through three stages: -from systems of volcanic arcs in the Late Jurassic to mid-Cretaceous; -through an intermediate stage with deposition in increasingly restricted successor basins in Jurassic to Early Tertiary; -to a continental stage by the Eocene. Minor coal seams occur usually in late volcanic arc stage sediments bur they can be locally thick as they are on Queen Charlotte Islands. Successor basins usually show a marine-paralic-limnic evolurion. Signijicanr coal deposits occur in the tarter two sequences in the Whirehorse (Tantalus) and Bowser (SkeenaSusrur) basins. Currenr activities are intensive in the more accessible Bowser Basin, for example at Telkwa, Susrut River and on the Groundhog coal field. On Vancouver Island major coal seams occur in cyclic sediments, but the more accessible deposits are mined our. Exploration renewed recently in the less accessible northern part of the Island, for example Quinsam, for surface mineable coal. The Western Cordillera is a mosaic of allochtonous tectonic blocks. They originated from the south and were displaced northward by several hundred kilometres. Many Tertiary coal basins are related to strikeslip transcurrent faults along which the later part of displacement took place, for example the Dawson coal area in the Tintina Trench. Tensional and dipslip normal faulting also created or enhanced sites for thick peat accumulation. For example at Hat Creek 280 m of coal occur in a 550 m section. Secondary structures are often better exploration targets than the main fault zones. Pluvial and alluvial fan environments away from the main drainage are usually the favourable sites for thicker and cleaner coal deposition."

Jan 1, 1985

By P. J. Suardini, T. E. Seppanen, M. J. Hanninen

In order to reduce the heat loading in the Tilden Mine kilns caused by burning coal, which in turn resulted in rapid and significant build-upon the kiln lining, internal carbon was added to the green ball prior to balling. Intensive laboratory testing led to three short-term full-scale plant tests that were successfully conducted. Appropriate environmental permits were obtained to allow Tilden to use internal carbon on a continuous basis. Findings concerning carbon addition rates, reductions in coal use, build-up reductions, fired pellet quality, and environmental issues will be discussed.

Jan 1, 2003

By F. A. McLean

The past decade has witnessed a rapid increase in the number and variety of uses found for internal combustion engines in mining operations. Gasoline engines are now widely used for operating core drills, pumps, compressors, small hoists, switching locomotives, tractors, boats, and other equipment. The heavy-oil engine is employed for operating compressors, generators, shovels, ore-milling machinery, and- in the iron, copper, and coal districts- in connection with that' latest newcomer in modern railroading, the oil-electric locomotive. Each of these applications could well form a subject for a lengthy treatise in itself. This paper, however, will be confined to a discussion of some of the features of internal combustion engines as applied to mine compressing plants and mill drive. Perhaps at no time in the history of mining in Canada has the search for new mines been more vigorously carried on, more old properties rejuvenated, or more remote districts exploited than during the past three years. The mine operator of today has a far wider range of equipment and facilities at his disposal than had the pioneers of Rossland, Cobalt, or Porcupine. Each year now witnesses the hinterland driven farther and farther back as improved forms of transportation, machinery, and methods make possible the exploration of properties once considered too inaccessible to warrant serious attention. Howey, Sherritt-Gordon, Callinan-Flin Flon, Jackson-Manion, Picard Gold Mines, and a number of properties in British Columbia, afford excellent examples of work carried out on an extensive scale miles from a railway, or in comparatively inaccessible mountain regions.

Jan 1, 1928

By Lin Li, Wen Shi, Hua Wang

"Specimens of the ultra-low carbon bake hardening steel were soaked for 1 min to 5 min, and then cooled by water quenching. The internal friction experiments were carried out to detect the spectra of the specimens. Results show that Snoek peaks are present in all the specimens, however, an obvious Snoek-Koster peak is found only in the 5 min-annealed specimen. Besides, tensile results indicate that the bake hardening values increase with the annealing time prolonging from 1 min to 3 min, but decrease as the annealing time prolongs further to 5 min. The solute distributions in the specimens were characterized by three dimensional atom probe. Some segregated C and V are found in the 1 min-annealed specimen, and the C and V contents decrease as annealing time prolongs to 5 min.1. IntroductionAs an excellent member of automotive body panel materials, various types of bake hardening (BH) steels have been developed since 1980s. Bake hardening property, as one of the most important mechanical properties, has been studied by many researchers [ 1-5]. As is known, BH phenomenon is generally controlled by the interaction between solute C and dislocations. The Snoek peak of internal friction (IF) is very popular in the investigation of solute C [6-9]. However, result of internal friction cannot suggest the distribution pattern of solute C as well as its influence on BH phenomenon.Three dimensional atom probe (3DAP) can diagnose solute element atoms as well as nano-sized precipitates, and it is the only instrument that currently can identify the identities of individual atoms in a material and measure their spatial coordinates with the resolution close to 0.3 nm [10]. There have been a number of studies about using 3DAP to detect solute elements as well as nanometer sized precipitates [11-19]. For example, Hono et al. [16] used 3DAP to determine the solute elements in an age-hardened Mg-Ca-Zn alloy, and they also obtained the distribution patterns of the observed elements."

Jan 1, 2011

By Clarence Zener

THE internal friction of nonferrous metals vibrating at low stress amplitudes has so far always been successfully interpreted in terms of inhomogeneities of one sort or another. Examples are the fluctuation of stress across a specimen vibrating transversely,1,2,3 the stress inhomogeneities due to the elastic anisotropy and partial random orientation of the individual crystallites,4,5 localized weak regions introduced by cold-working,6,7 grain boundaries and possibly twinning planes.8.9 Perfect single crystals are, by definition, homogeneous. Actual single crystals usually, perhaps always, contains some imperfections. The present investigation was undertaken to determine whether the internal friction of single crystals may likewise be attributed to inhomogeneities. This study was made possible through the gift of a large single crystal of 70-30 alpha brass by H. L. Burghoff, of the Chase Brass and Copper Co. The specimen, 3-s in. in diameter and 10 in. long, was similar to samples previously described by Mr. Burghoff.10 EXPERIMENTAL METHOD The experimental method used has previously been described in Institute papers.5,6.9 The measure of internal friction adopted here, I/Q, is (p) X the logarithmic decrement, a measure used by some writers, and is also (I/2p) X the specific damping capacity, a measure used by other writers. In all measurements the stress level was kept so low that the measurements were independent of stress level. In all measurements in which the temperature was varied, observations were made as the specimen slowly cooled from its highest temperature. The specimen was vibrated transversely. Observations were made at the fundamental frequency and at the first overtone, of about 620 and 1710 cycles per second, respectively. No attempt was made to avoid acoustical losses. EXPERIMENTAL RESULTS The specimen was annealed for several hours at 450°C. The temperature dependence of the internal friction was then determined from room temperature to 400°°C. As shown in Fig. i, the internal friction increased by only a factor of 2 from room temperature to 300°°C., then by a factor of 100 during the next :too' interval. These measurements are consistent with the view that the observed internal friction is the superposition of two distinct parts. One, dominant at room temperature, is nearly independent of temperature. This part may be accounted for by acoustical losses and by transverse thermal currents. It was not further investigated. The second part, when plotted in the manner of Fig. I, lies upon a straight line. Therefore it has a heat of activation H; i.e., it varies with temperature as Internal friction ~ e-HI/RT [I]

Jan 1, 1942

By Clarence Zener

THE internal friction of nonferrous metals vibrating at low stress amplitudes has so far always been successfully interpreted in terms of inhomogeneities of one sort or another. Examples are the fluctuation of stress across a specimen vibrating transversely,1,2,3 the stress inhomogeneities due to the elastic anisotropy and partial random orientation of the individual crystallites,4,5 localized weak regions introduced by cold-working,6,7 grain boundaries and possibly twinning planes.8,9 Perfect single crystals are, by definition, homogeneous. Actual single crystals usually, perhaps always, contains some imperfections. The present investigation. was undertaken to determine whether the internal friction of single crystals may likewise be attributed to inhomogeneities. This study was made possible through the gift of a large single crystal of 70-30 alpha brass by H. L. Burghoff, of the Chase Brass and Copper Co. The specimen, ½ in. in diameter and 10 in. long, was similar to samples previously described by Mr. Burghoff.10 EXPERIMENTAL METHOD The experimental method used has previously been described in Institute papers.5,6,9 The measure of internal friction adopted here, 1/Q, is (1/p) X the logarithmic decrement, a measure used by some writers, and is also (1/2p) X the specific damping capacity, a measure used by other writers. In all measurements the stress level was kept so low that the measurements were independent of stress level. In all measurements in which the temperature was varied, observations were made as the specimen slowly cooled from its highest temperature. The specimen was vibrated transversely. Observations were made at the funda¬mental frequency and at the first overtone, of about 620 and 1710 cycles per second, respectively. No attempt was made to avoid acoustical losses. EXPERIMENTAL RESULTS The specimen was annealed for several hours at 450°C. The temperature dependence of the internal friction was then determined from room temperature to 400°C. As shown in Fig. 1, the internal friction increased by only a factor of 2 from room temperature to 300°C., then by a factor of l00 during the next 100° interval. These measurements are consistent with the view that the observed internal friction is the superposition of two distinct parts. One, dominant at room temperature, is nearly independent of temperature. This part may be accounted for by acoustical losses and by transverse thermal currents. It was not further investigated. The second part, when plotted in the manner of Fig. I, lies upon a straight line. Therefore it has a heat of activation H; i.e., it varies with temperature as Internal friction e~H/RT [I]

Jan 1, 1942