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By X Li, R Chu, X Deng

The hot-dip galvanising industry is the largest consumer of zinc, with over 40 per cent of the world’s total annual production of zinc used for galvanised steel. The dross generated in the hot-dip galvanising coating process is a valuable co-product, since it contains high quantities of recyclable metal. A new method to recover the metal from the industrial galvanising dross was proposed using supergravity separation. During the hot-dip galvanising process, the presence of zinc dross has a serious impact on the surface quality of the hot-dip galvanised sheet, forming zinc dross defects. To reduce the impact of zinc dross, the zinc dross on the surface of the zinc pool needs to be manually or mechanically removed at regular intervals. However, during the dross removal process, a large amount of metal zinc is inevitably carried out, resulting in low zinc utilisation rate and high zinc loss rate. This article proposes an efficient and low-cost technology for the recycling and utilisation of hotdip galvanised dross, which uses super-gravity technology to recover hot-dip galvanised dross online. The metal in the hot-dip galvanised dross returns to the zinc pot in situ, while a small part of the dross remains in the super-gravity equipment, which can reduce the amount of zinc dross by more than 60 per cent and achieve a reduction in zinc loss from 17 per cent to less than 7 per cent.

Jun 19, 2024

By J. Zinck

The management of mine wastes generated by both active and inactive mining is an ever more challenging issue. The cost to manage and treat mine wastes, including tailings, waste rock, treatment sludge and slag, is estimated at over $50B in Canada and the United States alone. Cost-effective technologies are required to meet both short and long term challenges and increasing environmental standards. This paper will provide an overview of novel and conventional technologies to manage mine waste particularly in the areas of waste stabilization, treatment and disposal technologies.

Jan 1, 2004

By Devraj Sharma

This paper presents technical issues in the design and management of a retorted oil shale disposal site. Major physical and geochemical mechanisms which affect the disposal are: heat transport, moisture migration, chemical species transport, auto-ignition, and mechanical behavior alterations of the retorted oil shale pile. The interaction of these mechanisms and their relative magnitude will affect the environmental behavior of the pile. The paper discusses the coupling between the mechanisms, presents a framework to quantify the processes by laboratory and field measurements, and in addition discusses the use of mathematical models to provide quantitative predictions.

Jan 1, 1981

By R. W. Pugh, S. L. Ma

"High carbon rods are typically used as the grinding media in rod mills. Usually an AISI I 090 grade of steel is used which provides the high hardness needed for abrasion resistance and sufficient toughness to prevent rod breakage.Work to improve performance in the past has mainly concentrated on increasing the hardness for improved abrasion resistance. This has been accomplished by adding alloys to the steel which uniformly increase the hardness across the rod section.However uniformly increasing the hardness of the rod produces a more brittle product and at high hardness l1evels can lead to rod breakage problems. Heat treatment processes can be used to selectively increase the surface hardness to high levels while maintaining the core at lower hardness levels to give a product that wears slower without breakage. AltaSteel has developed and mill tested a higher hardness heat treated grinding rodThis paper describes the development of a simple model to predict performance improvement with different hardness profiles and the AltaSteel heat-treated grinding rod process. Mill characteristics of the Endako operation are summarized and predicted performance improvements based on hardmess are compared to the approximate 25% achieved in trials running since July, 1991 at this mill. Early results of other mill trials are also presented.INTRODUCTIONAltaSteel, in Edmonton is a major supplier of grinding media. We have a strong desire to continually increase the quality and performance of our products and thereby improve the efficiency of our customers' processes. In the area of grinding rods, we wanted to produce a product with a significant improvement in wear rate. Second to energy, rod consumption usually represents the next highest cost in processing. This paper presents our development of a heattreated grinding rod that has reduced consumption by about 25% in trials to date."

Jan 1, 1993

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

By A. Bouajila

To stay competitive in an open market, mineral industries have to optimise their processes, lower their production costs and improve the commercial value of their products. Up to a recent past, they were impaired in this attempt by a lack of adequate devices allowing reliable on-line and real-time process monitoring (detection or measurement). Process monitoring for process control and the product characterisation for quality control are quite different tasks. Planners and researchers should be fully aware of this when evaluating or developing monitoring equipment for on-line process control. This paper will comment on some aspects of sensor specifications, during the design and the evaluation steps, related to sampling, measurement (accuracy, sensitivity, delay and correlation to the process) and suitability to the exploitation environment. Examples of R&D projects promoted by COREM for various industrial applications will be presented.

May 1, 2001

By B. A. Eaton, R. H. Jacoby

This paper presents the depletion-performance correlations developed using data from PVT studies and well-completion tests of 27 rich gas-condensate and volatile-oil reservoir fluids. The PVT behavior for each fluid war determined experimentally in the laboratory, and the depletion performance of each fluid was then calculated. Well-completion test data consisting of reservoir pressure and temperature, initial total gas-oil ratio, and stock-tank oil gravity were used with the depletion-performance data to develop general performance correlations. Three correlations are presented. The first equation shows the empirical relation of gas in place per barrel of hydrocarbon pore space with reservoir pressure and temperature, and initial total gas-oil ratio. The second equation is the correlation of stock-tank oil in place per barrel of hydrocarbon pore space. The third equation relates stock-tank oil production (to 500-psia depletion pressure) with pressure, temperature and oil gravity. All three correlations are also presented in convenient graphical form. Gas production to 500-psia depletion pressure is approximately 92.6 per cent of the gas in place for each fluid, so no correlation was developed for gas production. INTRODUCTION The rate of discovery of shallow, low-pressure and low-temperature oil reservoirs in the United States has been declining in recent years. For this reason, the search for oil has gone to greater depths where high pressures and temperatures are encountered. A high-pressure and high-temperature reservoir is the environment in which many rich gas condensates and highly volatile oils are found. Because of this trend, the performance prediction of such reservoirs has become an important task of the reservoir engineer. The need and usefulness of a performance correlation based on field data that are available from the usual well-completion tests have previously been established. These earlier attempts have shown that the phase behavior of rich gas-condensate systems and volatile-oil systems can be correlated with fluid properties, pressure and temperature. However, very little information on gas-condensate depletion performance5 was available at the time of these earlier attempts. The availability of more recent data has made possible the development of an improved correlation. The data, as listed in Tables I and 2, are for 25 gas-condensate and two volatile-oil systems that were studied. The problem was to correlate the data for in-place fluids and the production data with the initial total gas-oil ratio, initial reservoir pressure and temperature, and stock-tank oil gravity. These correlations were obtained by multiple regression analysis, whereby the data were fitted to an equation by the method of least squared error. BASIS OF THE CORRELATIONS 1. The data used in the development of these correlations were obtained from depletion-performance calculations6 and well-test or production measurements. 2. All of the independent variables used in the correlations are available from the usual well-test completion data. 3. The reservoir volume considered is 1 bbl of hydrocarbon pore space (HCPS). 4. The gas-oil ratio used is the total standard cubic feet of gas (at 14.7 psia, 60F) coming off the entire separator train per barrel of stock-tank oil. This minimizes the effect of separator conditions which might vary from system to system. 5. The correlated pressures are the actual reservoir pressures which might or might not be the saturation pressure of the reservoir fluid.

Jan 1, 1966

A practical approach has been developed for the design of both grates and pulp lifters. It is based on: an appreciation of the process interaction between grates and pulp lifters, an interpretation of mill charge structure as it relates to discharge through grates, and an analysis of pulp and solids flow in pulp lifter channels. This approach can be used to improve the overall discharge effectiveness of AG and SAG mills.

Jan 1, 2000

By M. Fiset, D. Belley

"To better understand the wear process of various materials that may be used as blades on snow removal equipment, the first step is to evaluate the influence of the load applied and the moving speed on road wear rates of one type of steel and three types of polymers. While the behavior of steel conforms to Archard's law, wear rates of polymers increase to a power of ex of the load applied according to a model implying that the wear of these materials is due to fatigue. The wear rate of some of the polymers varies considerably in terms of speed, unlike the steel. The wear resistance of some of these polymers outclasses the steel tested as long as the speed is not too great. They, therefore, present interesting alternatives for snow removal on more fragile surfaces such as sidewalks and zone made of inter-block slabs.IntroductionSince the dawn of the Industrial Revolution, the massive use of machines has brought with it a number of different problems regarding wear. Snowplowing roads, parking lots and sidewalks is an activity that generates enormous expense in a country such as Canada. To better understand these wear processes and in the hope of stimulating new approaches designed to reduce the costs related to this sector of activity, this paper presents the behaviour of several materials (steel, polymer and rubber) as they wear on an asphalt-fines matrix surface lubricated with water. Also discussed is the effect of various parameters such as the load applied and speed."

Jan 1, 1990

By R. D. Leitch

"REASONS FOR AND PURPOSE OF WORKIn 1924 the United States Public Health Service was requested to undertake a special study of stream pollution. At that time the proposal that the United States Bureau of Mines take up the study was made by the Public Health Service because in point of training and experience the personnel of the latter was considered not to be as well, suited to this type of investigation as was that of the Bureau of Mines. H. Foster Bain, then Director of this bureau, promised to undertake the work, and, accordingly, field investigations were begun in the spring of 1925. The problems of mine-drainage wastes and of gas-house and coke-oven waste were investigated in the laboratory, and a method of treatment by sodium hydrate and benzol was found to be promising. The idea was obtained by A. C. Fieldner, chief engineer of the Bureau of Mines experiment stations, while in Germany in 1924, where he was shown a practical application of the process, but no information was obtained as to definite chemical or mechanical processes. Because of the then pending American patent application by the German firm, we made no attempt to develop our findings further. Shortly after, a similar method of treatment was developed in the United States, and since that time we have devoted our attention entirely to mine drainage. This paper is a presentation of some general facts and information gathered during the past five years on coal-mine drainage.SCOPE OF WORKAt the time our work was begun there was such a diversity of opinion on the whole subject and apparently so little was accurately known, that it was decided to undertake a basic study from which (1) certain definite information might be evident, and (2) what might be considered side issues of the original investigation would be suggested for subsequent study.A stream in a district thought to be representative of those in low to average sulphur bituminous coal fields and another in a high sulpbur district were selected for study, A fair (weber of factors entered into the tentative selection of these streams, the chief ones being their accessibility and freedom from other industrial or domestic pollution, besides, of course, the presence of mine drainage in these streams."

Apr 1, 1931

By H. Soto, J. Jara, F. Nava

"A combination of oxidation and precipitation was used to eliminate cyanide from gold milling effluents. Preliminary laboratory work developed with both synthetic cyanide solutions and with industrial effluents indicated that ozone can easily destroy free cyanide and weakly complexed cyanide (i.e. copper and zinc cyanide). In this case the reaction is quite fast and seems to be controlled by the mass transfer of ozone to the solution. Experimental results indicate that free cyanide and weak-acid dissociable cyanide in mill effluents can be reduced to less than 1 ppm. However, the iron-cyanide complexes proved to be quite resilient to destruction with ozone and they remained in the solution even after most of the free and weakly complexed cyanide was destroyed with ozone. These results were confirmed in a pilot trial developed at the Sphinx plant in northern Quebec.To deal with the problem presented by the presence of the iron complexes two different approaches were studied: use of a combination ozone-ultraviolet light oxidation, and the precipitation of iron-ferrocyanide complexes in the residual solution after ozonation. This last method proved quite promising since reduced the total cyanide levels of industrial solutions assaying as much as 250 ppm to less than 1 ppm of total cyanide. Control of the · pH of the solution was the key to obtain the precipitation of the iron complexes. The use of iron to precipitate cyanide complexes has the advantage of being less expensive and less toxic than copper (used by the Inco process)."

Jan 1, 1992

By Sakshi Hazuria Anderson, Angela Binder, Oscar Jaime Restrepo Baena, Simit Raval, Sandra Nowosad

As the mining industry faces times of change, new challenges arise to ensure raw material supply for the younger and future generations. Different scenarios are currently shaping the way we mine and teach mining engineering. Led by an increasing demand for raw materials, net zero requirements for improving long-term operation performance, technological advancements such as automation and digitalization, safety improvements, environmental considerations and a need for social acceptance, mining is pursuing to change and adapt to these requirements at a faster pace. Such changing times raise new concerns, one of the most relevant is the lower number of students interested or enrolling in mining engineering and related fields leaving mining engineering as one of the less preferred career options between the younger generations. Nonetheless, it is essential to continue addressing and supplying the skill sets that are suited to the contemporary and future mining industry. To this end, globally, academia is currently undergoing several initiatives such as curricula updates and adaptation, up skilling, improving teaching practices and techniques, including e-learning techniques, enhancing industry-academia and inter-university collaboration, and much more. In countries like Australia, where mining plays a crucial role in the economy, the need for curriculum updates is more pressing than ever. As the mining industry evolves with new technologies and sustainable practices, there is a growing demand for a workforce skilled in these modern approaches. Recognizing this necessity, universities such as the University of New South Wales and Curtin University have taken significant steps to revamp their educational programs. By updating their academic offerings, both universities aim to equip graduates with the necessary skills to drive innovation and sustainability in mining, supporting Australia’s development as a leader in this critical sector. Moreover, the selection of topics that drive curricula update and the focus of the research institutions in mining engineering must extend beyond mere technological and technical aspects to include social and ethical dimensions. In this context, the Universidad Nacional de Colombia, in association with the Colorado School of Mines, has introduced the topic of Humanitarian Engineering (HE) in 2020. HE is a socio-technical approach that focuses on developing engineering solutions that promote the sustainable development of communities addressing their basic needs and aiming to improve their quality of life (10, 18). By focusing on sustainable development, community engagement, and equitable resource distribution, HE helps the industry build positive relationships with stakeholders, reduce conflicts, and foster social license to operate. As the mining industry seeks sustainable and socially responsible practices, future engineers require training in this area to understand the broader impacts of their work, fostering a mindset that prioritizes community well-being and environmental stewardship alongside technical proficiency.

Feb 1, 2025

By C. G. Dunn

The measurement of interfacial teusions or grain boundary energies in metals is an important metallurgical problem, especially since it bears on growth and nucleation processes. Statistical methods of measuring equilibrium grain boundary angles, which relate interfacial tensions, have been used by some investigators1'2 but more direct methods would be preferred. A direct way, based on a simple extension of a successful method of growing single crystals of silicon ferrite to predetermined orientations in flat specimens,3 is to produce three-grain specimens in such a way that the equilibrium common grain boundary will be perpendicular to the surface of the specimen. The angles to be measured then appear as the grain boundary angles in the surface of the specimen. The method of producing a single crystal specimen with a predetermined orientation is basically the same as that employed by Yoshida and Fuji-wara4 in their work on aluminum wires. The specimen, prior to any single crystal transformation, must have a matrix which will support the growth of a crystal of the desired orientation. Growth may occur through exaggerated grain growth or, if the matrix is strained a critical amount. by normal recrystallization. In either case the matrix must have stability at the temperature used to effect the transformation, this stability appearing as a long induction period for exaggerated grain growth or for the formation of recrystallization nuclei. Additional control is gained by using a high temperature gradient through which the specimen is moved at a suitable rate. To obtain the desired orientation, the specimen is fed a short way into the furnace producing one or more crystals in the hot end. After the specimen is removed from the furnace, the orientation of a crystal is determined, so that this crystal may be reoriented by properly deforming a narrow piece of the matrix between the end crystal and the rest of the specimen. This part of the specimen in the case of silicon ferrite is preferably held at red heat during the reorienting process. Fig 1 shows a specimen which is ready to be transformed into a single crystal through growth of a reoriented "seed" crystal. When the method just described is applied to the production of a three-grain specimen two crystals are grown first side by side in one end, the specimen is then reversed and the third grain grown from the opposite end. A suitable group of grains each of different orientation is one where all three grains have the same crystallo-graphic plane in the plane of the specimen. Fig 2 shows a photograph of a three-grain group prepared as described. The notches are introduced in the open ends of the grain boundaries to anchor them during the final annealing operations which ultimately should bring the grain boundaries to the lowest energy configuration. Two-grain groups with different crystallographic planes in the plane of the specimen can be similarly prepared and treated. If the two grains have different surface (gas to metal) energies per unit area, the equilibrium condition leads to a curved grain boundary.* * This feature of the problem was pointed out by J. c. Fisher. References 1. Cyril Stanley Smith: Grains. Phases and Interfaces: An Interpretation of Microstructure. Trans. AIME 175, 15. Met. Tech. TP 2387, June 1948. 2. D. Harker and E. Parker: Grain Shape and Grain Growth. Trans. A.S.M. (194,5) 34, 156-195. 3. C. G. Dunn, A. Seddon, and R. Wylie: Unpublished Work, 1946-1947. 4. Takeo Fujiwara: A Method of Producing A Long Single-Crystal Wire of Aluminum with any Desired Crystallographic Axis. Jnl. of Sci. Horoshima Univ. A, (1939) 9, No. 3, 227.

Jan 1, 1950

By L. G. Austin

Using an instrumented laboratory high-pressure grinding rolls mill, the grinding force, gap dimension, mass flow rate and net mill power were measured for six coals and a crystalline quartz. A technique was developed to estimate the compressive stress-strain curves for compression of the materials in the mill plus the effects of elastic decompression. To reconcile the mill power and grinding pressure results, it was necessary to allow for the energy recovery on decompression. No clear correlation was obtained between the form of the stress-strain curves or the variation of specific mill power factor with the Hardgrove grindability index (HGI), although coals with the lowest and highest HGIs (i.e., 44 and 106) gave results significantly different from the other coals. Feeds below 140 mesh (105 µm) flowed more rapidly than coarser feeds and would not build up high grinding pressures. This indicated shearing and fluidlike properties rather than compression as a locked bed.

Jan 1, 1998

By L. Xinghua

Limonite is a general term for a group of amorphous iron oxide and iron hydroxide materials. It is considered as one of the very refractory iron ore types due to its wide variation in chemical composition, iron content, moisture content and easily sliming in the course of comminution. Iron grade of test sample is 25.48%, the iron minerals are mainly limonite; and the gangue minerals consist of quartz and feldspar in majority, secondarily silicate minerals. In this test work, high intensity magnetic separation (HIMS)-cationic reverse flotation and magnetic roasting-low intensity magnetic separation (LIMS) tests were conducted on limonite ore. The test results show that the concentrate with iron grade of 50.97% and recovery of 68.50% can be obtained by HIMS-cationic reverse flotation technique; while using magnetic roasting-LIMS technique, the better concentrate indexes of iron grade of 60.36% and recovery of 89.71% are achieved, and the iron grade of tailing is only 4.42%. Therefore, the magnetic roasting-LIMS technique is a better suitable method for beneficiation of low-grade limonite ore. Keywords: Low-grade limonite; Mineralogy; HIMS; Cationic reverse flotation; Magnetic roasting; LIMS

Feb 27, 2013

By Andrzej Warczok

Liquid slags produced in smelting of copper concentrates contain copper in a dissolved form as well as mechanically entrained inclusions of copper matte. Coalescence and sedimentation of inclusions during slag cleaning plays a key role in copper recovery. Liquid matte inclusion in a molten slag presents a system of metallic conductor in an ionic solution. Constant electric field induces migration of the matte droplet along the current lines. Additional phenomena occur in a system under crossed electric and magnetic fields. Electromagnetic buoyancy force acting on the inclusion affects its settling rate. Electromagnetic buoyancy force of insulating and metal spheres has been measured in a liquid synthetic slag. It was found that depolarisation of the metal sphere, related to the electrode reactions occurring in the surface, plays an important role in the determination of the direction and magnitude of the electromagnetic force. On the basis of the existing theories and results of measurements a mathematical model describing the behaviour of metallic inclusions in the liquid slag under the influence of crossed electric and magnetic fields was developed. Simulation of behaviour of copper matte inclusions under crossed fields showed trajectory of motion in a liquid slag as a function of the slag properties and the inclusion size.

Jan 1, 2003

Extensive testing in the past ten years has shown that where a uniform natural gamma background is present in the strata bordering the seam, the thickness of the boundary coal left in place after mining can be determined by measuring the attenuation of that radiation (Nelson and Bessinger, 1989). Measurements made by the authors in underground mines in Pennsylvania, West Virginia, Ohio, Illinois, and Kentucky, and by others in Wyoming and New Mexico, have shown the presence of such a gamma background (Nelson, 1989). Natural gamma coal thickness sensors of several configurations have been tested in mines owned and operated by the Consolidation Coal Company in Pennsylvania and west Virginia (Nelson and Bessinger, 1988).

Jan 1, 1990

By J. E. Lema

America's bulk commodity transportation systems have taken on a new look in the 1970's and 1980's. Railroad systems, barge lines providing inland and intra- coastal waterway transportation, and Great Lakes carriers have undergone substantial changes through mergers and acquisitions, consolidations of ownership and control, and construction of modern intermodal transportation facilities linking railroads and water carriers. The new look has generated some concerns and opportunities with regard to producers and shippers of bulk commodities which are characterized by the necessity of moving large quantities of heavy materials long distances. Clearly such transportation requirements call for efficient railroad and water carrier services. Shippers of commodities like coal, grain, .chemicals, minerals, ores, forest products, petroleum products, and heavy manufactured goods find reductions in transportation competition lead to concerns that rates charged by carriers will not be sufficiently constrained by market forces. At the same time, new policies on contracting for railroad services can lead to greater efficiencies, a rewarding opportunity for carriers which should be shared with shippers and consumers of bulk commodities. Then, of course, there's a related problem that in the absence of effective competition, the benefits of increased carrier efficiency will not be passed on, in part, to shippers and consumers, causing losses in markets for producers.

Jan 1, 1986

By D. J. Jr. McAdam

This paper presents stress-cycle graphs for five samples of monel metal and three high-strength aluminum alloys. These graphs are evidently curves with horizontal asymptote. The position of the horizontal asymptote can be determined with sufficient accuracy by extending the experiments to not more than 50,000,000 cycles. For some of the graphs, there is a slight downward slope between 50,000,000 and 100,000,000 cycles. The slope is so slight, however, that, extrapolation from 50,000,000 to 100,000,000 cycles gives the endurance limit with sufficient accuracy. Monel metal and duralumin are not exceptional among non-ferrous metals in endurance properties. IN Part I of this paper' a comparison was given of the results obtained in investigation of the endurance properties of non-ferrous metals in .three laboratories: the Engineering Experiment Station of the University of Illinois, the U. S. Air Service at McCook Field, Dayton, Ohio, and the U. S. Naval Engineering Experiment Station, Annapolis, Md. Part I was devoted to a discussion of the forms of the stress-cycle graphs obtained at the three laboratories. For comparison, typical graphs obtained at the three laboratories were plotted on the same semi-logarithmic scale. The typical rotating-cantilever graph for ferrous and non-ferrous metals obtained at the Naval Experiment Station was described as a curve descending with gradually decreasing slope to a horizontal line. In the reply to the discussion of Part I, however, this graph was described as a curve with horizontal asymptote. It. was also said that the ordinate of the asymptote (the endurance limit) could be determined by endurance tests of not more than 50,000,000 cycles. This description was intended to apply only within the range of ordinates used in plotting an ordinary endurance graph. It was recognized that if .extended upward beyond the usual field, the curvature of the graph would decrease until -the graph would either approach a straight a line or possibly reverse its curvature.

Jan 2, 1926