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By D. Van Dooren

The final goal of the research project is to develop a 3D FEM model that is able to predict the kinetics and micro-structural evolution during the bainitic transformation. The input parameters consist of thermodynamic and atomic mobility data obtained from the ThermoCalc and mCTRA databases combined with structural mechanics data extracted from the stress-strain curves of the fcc and bee phases. In this paper the general principles of the model are outlined and some interesting preliminary results are shown and commented. The full implementation of the model has presently not been achieved yet. In the model the bainitic transformation is considered as a sequence of martensitic (re)nucleation and growth of a ferritic subunit followed by the carbon rejection into the surrounding austenite. The (re)nucleation of the subunits will be described through a non-classical martensitic nucleation criterion. Once a nucleus has been activated at a specific location in the material, a full-sized subunit is instantaneously formed through a displacive mechanism. The stress state in the system that arises due to the transformation strain can be calculated by a 3D FEM programming code. Immediately after the formation of the subunit, another 3D FEM programming code calculates the carbon diffusion from the supersaturated ferrite into the surrounding austenite. The resulting stress state and carbon profiles will be used to determine where and when a new subunit will nucleate based on a renucleation criterion. Keywords: Bainitic Transformation, Modeling, Eshelby, Carbon Diffusion

Jan 1, 2003

By H. Kenworthy

The purpose of the study described in this publication is to develop methods for recovering simple master alloys or single metal components from discarded and scrapped S-816 alloy, The Bureau of Mines started this investigation late in 1955 after the need became apparent for a method of reclaiming high-temperature alloys from an ever-increasing accumulation of rejected and wornout jet engine turbine buckets. Laboratory studies showed the following: (1) Pyrometallurgical separations are not selective enough, (2) several methods can be used for effective chemical dissolution of the major constituents of the alloy, (3) a master alloy or complex salts of cobalt and nickel can be separated, (4) chromium, contaminated by several other metals, may be segregated, and (5) more time and effort need to be expended in separating the minor constituents and improving the purity of the major metals removed. Difficult and incomplete chemical separations were attributed to the complexity of alloy composition, as were the long tedious chemical analyses o' products. For determination of several of the metallic components, standard methods of separation and routine analytical procedures had to be considerably modified to achieve satisfactory results. The overall technical problems involved in separating S-816 components do not appear to be insurmountable; however, refinement of several of the methods used in this investigation is desirable.

Jan 1, 1961

By D. L. Blakeman, Trimble. J. W., S. W. Banning

Noranda's Grey Eagle mine and mill, in the Siskiyou Mountains of northern California, began shakedown operations in the late fall and early winter of 1982. This paper describes some of the unique features in mineralogy, milling, and water treatment operation at Grey Eagle. In addition, major start-up problems in the mill and water treatment plant are discussed along with measures taken to correct these problems.

Jan 1, 1986

By Tony Mazzo

It has often been said by consulting engineers that foundation contractors are in the business of taking risks. One would agree that the mere fact a foundation project can be budgeted, planned, engineered and executed solely on the reliability of eight test borings made at a proposed site having an area of approximately 19,000 square feet, is a risky proposition, in and of itself. Now imagine that this site is actually one half of a city block located in an urban setting in an old, congested, historical neighborhood, surrounded by narrow city streets and historic landmark buildings. And suppose that the required depth of excavation for the construction of the new building on this site is approximately 35 feet and the natural groundwater table is at a depth below existing grade of only 25 feet. Given the difficult site conditions outlined above, one could certainly add the words "challenging" and "complicated" to the inherent word "risky" when describing the construction techniques involved to undertake a foundation project of this magnitude. This case study will discuss in detail how the excavation, sheeting, dewatering and underpinning work was accomplished as well as the problems overcome along the way.

Jan 1, 2003

By L. B. Phelps

Many coal mining companies have potential surface mine reserves which either are known or suspected to have had prior drift mining activity on them. In many cases, there is no documentation on these mines or at best, very fragmented records. These undocumented abandoned underground mines are creating engineering, financial, and environmental difficulties and concerns for both surface coal mine operators and regulatory personnel. This paper examines the use of resistivity techniques in detecting entries of abandoned drift coal mines. The detection of such a drift mine entry would confirm the presence and orientation of an abandoned underground coal mine.

Jan 1, 1985

By Francis Church Lincoln

I. SITUATION AND SURROUNDINGS. THE Promontorio mine is situated at the northern end of the Sierra San Francisco de Coneto, in the town of Promontorio, Partido of El Oro, State of Durango, Mexico. As shown in the sketch-map, Fig. 1, the nearest railroad station is Chinacates on the Mexican International Railroad, 82 miles north of the city of Durango. The mine is 16 miles north of the station by air-line. It is reached by means of a good wagon-road which first crosses the Guatimapé Plain, passing the ranches of San Antonio and San Julian, to Estacion-a distance of about 15.5 miles-and then entering the mountains crosses the Sierra to Promontorio-a further distance of 11.5 miles¬making in all a distance of 27 miles by road from railroad to mine. Promontorio is just beyond the summit of the range, at an elevation of about 8,000 ft. above sea-level, or 1,350 ft. above the Chinacates station. The Castillo de San Francisco, the highest peak in the Sierra, has an altitude of 10,000 ft., and the Promontorio road crosses the summit of the ridge at an elevation of 9,000 ft. by a pass just below this peak known as the Puerto del Almagre. The Promontorio mill is situated at Santa Ives, 2 miles by tram or 3 miles by wagon-road to the north of Promontorio and about 600 ft. lower. The Sierra San Francisco de Coneto decreases in height towards the north and west till it comes to an end at the Melchor Arroyo on the ranches of Melchor and Ramos. Beyond this arroyo another range, the Sierra de la Candela, begins. In the vicinity of the Promontorio mine the hills are very rugged and the surface is furrowed by ravines which contain running streams during the rainy season-July, August and

Jan 1, 1908

By R. Yang

This paper presents a kinematic approach for blast modeling with examples of blast models that were developed previously. A kinematic approach was applied successfully in developing blasting models that can simulate all blast design parameters for field applications. Several applied blasting models have been developed and applied widely in the world. A kinematic approach to blast modeling refers to using measurements of kinematic quantities such as the velocity, strain, or displacement and well-established assumptions to model blasting phenomena, rather than being restricted to use first principal of physics, such as, the stress- and material-constitutive relations. The kinematic quantities are easy to measure in the field. Due to the complexity and inhomogeneity of rock mass properties, using first principles of physics, many parameters of rock and explosive properties must be involved, which are hard or impossible to quantify. This creates a major impediment when trying to simulate the total process of blasting based upon first principles of physics. The 3D kinematic model for muckpile formation was developed and applied to open pit blasts. The multiple blasthole fragmentation model developed during recent years has been applied successfully to many mine sites around the globe. These models are typical examples of blast modeling using the kinematic approach, which enables the models to catch major trends of the blasting process and explicitly simulate full blast design parameters and complex geometries. Blast modeling using the kinematic approach results in easy model calibration and validation against field measurements and effective applications to practical problems. Using kinematic models of the muckpile formation and the multiple blasthole fragmentation model, this paper demonstrates the merits of the kinematic approach for blast modeling. New developments of the models were also presented in the paper, which illustrate the potential of the kinematic modelling approach.

Mar 2, 2022

By MattelmSki M

Outokumpu Harjavalta Metals Oy has been producing nickel since 1962, based on conventional flash smelting technology followed by electrowinning of nickel. In the 1980s, a research project was initiated to develop a converterless direct smelting process to produce matte for further refining in the then existing refinery. The process was tested on a pilot plant scale at Outokumpu's research centre in Pori and was found to be viable. The process was named the Direct Outokumpu Nickel Smelting Process or the DON Process. At the turn of the 1990s, Outokumpu studied various options to develop its nickel business and the Harjavalta operations. As a result of this work, the DON Process was further developed to produce two mattes: low iron matte in the flash furnace to be leached in the existing leaching circuit and high iron matte in the electric furnace to be leached in the new leaching circuit. In Harjavalta's case, it was essential and important that the process could use the existing flash furnace and electric furnace without converters.

Jan 1, 1996

By Francis Church Lincoln, Paul Zinner

"Attention of the Bureau of Mines was first directed to the Gray farm area by the results of several exploratory churn-drill holes completed by the New Jersey Zinc Co., and later by Roland J. Teske and by Judge H. L. Heer.When the Bureau of Mines initiated its investigation of the area, all drilling on the Gray farm had been discontinued, and no mining had resulted from the exploratory work. However, in the opinion of the Illinois Geological Survey, the Federal Geological Survey, and the Federal Bureau of Mines, this drilling,with the preliminary geological studies, was considered sufficient evidence to justify continued exploration to the southeast along a projection of the trend of mineralization developed in the mines to the northwest, or the so-called Black Jack Trough.This report describes the work done and presents the data obtained during the period of Bureau of Mines exploratory work.In its program of exploration of mineral deposits, the Bureau of Mines has as its Primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision or Dr. R. S. Dean, assistant director.Special acknowledgment is due Paul Herbert, geologist, Illinois Geological Survey, for his studies of cores, which greatly influenced the planning and progress of the exploratory work. Acknowledgment is also made to A. F. Agnew and A. V. Heyl, geologists, Federal Geological Survey, for their invaluable aid; to 0. W. Terry, F. C. Lincoln, M. H. Berliner, A. M. Cummings, project engineers; and to E. P. Barrett, district engineer, Minneapolis, and E. D. Gardner, regional engineer, Rolla, Mo., for supervising the program.The Gray ore body is on the Gray farm 5 miles south of Galena in Jo Daviess County, northwestern Illinois. The location with respect to adjoining properties is shown on figure 1. Galena is a city of 4,000 population on the banks of the Galena River, a stream that was formerly navigable by Mississippi River steamers but has now shrunk to the dimensions of a small creek. A gravel road leads from the city to the Gray farm and onward to the Bautsch and Boevers farms to the south of it."

Sep 1, 1946

By S. Stefanizzi

In the present paper, numerical simulations based on a finite/discrete element approach are used to study deformation and failure process during standard rock mechanics. FEM/DEM modeling has been used as available with the ELFEN code, which explicitly model the transition from continuum to discontinuum. The transition is simulated through a crack nucleation and propagation that obeys to the Griffith?s failure criterion. If the fracture criterion within the intact rock (represented by FEM) is met, a new crack (represented by DEM) is initiated. Remeshing allows the fracture process through the FEM mesh to be tracked and visualized, thus contact properties can be assigned to pre-existing fractures and newly generated fractures. In this study, compressive tests of rock samples are simulated. The applicability of ELFEN to properly and efficiently simulate typical laboratory rock mechanics tests, with reference to the rock fracture process, is described in detail. In addition, an indirect validation of the extensional strain criterion proposed by Stacey (1981) is given.

May 1, 2009

By R. C. Padfield

Experience over a 3-year period in Bethlehem Steel Corporation's plants has demonstrated the reliability of open-hearth roofs of bonded sprung-arch constructzon with burned basic brick. The design principles lor constructing these roofs include a minimum hot-strength requirement for the basic brick, expansion allowances that extend the full roof thickness, structural members to control arch contour, and a specified minimum roof rise. The greater stability of bonded roofs is explained in terms of the basic stress patterns of ring constrution and bonded construction. PRIOR to the development of successful sprung-arch roofs of basic brick, the majority of open-hearth furnaces in the United States were operated with sprung-arch roofs built of silica brick. Although many silica roofs used on open-hearth furnaces were ring-arch construction, Bethlehem Steel Corp. used bonded-arch construction because of its greater stability. In ring construction, each ring of brick is separately keyed and comprises an independent arch with the straight joints between rings traverse to the longitudinal axis of the furnace. In bonded construction, the bricks are laid in rows starting from the skewbacks so that the straight joints run parallel to the longitudinal axis of the furnace. Each brick in a given row is laid so that it spans the joint between two bricks in the row beneath it. Thus, the transverse joints across the arch are broken and the arch rings are thereby interlocked or bonded. When basic roofs were first being developed, the basic brick that were available had low hot strength. Such brick could not be safely used in sprung-arch construction without some means of suspending them. With the development of higher firing techniques by brick manufacturers and the recently introduced direct bonded bricks with high hot strength, the use of burned basic brick in sprung-arch roofs became feasible. The availability of high hot strength basic brick coupled with the potentially lower cost and proven stability of bonded construction prompted Bethlehem's Research Department to study the possibility of using basic brick in bonded roofs. With the full cooperation of plant ceramic engineers and open-hearth superintendents, particularly in 3 years of fur-nace trials, we developed the design criteria for bonded roofs and the corresponding property requirements for the basic brick that are discussed in this paper. DESIGN PRINCIPLES OF SPRUNG-ARCH BRICK ROOFS Stresses in Fixed Arches. A sprung-arch open-hearth furnace roof is generally built on rigidly held skewbacks. The constraint of the fixed support at each end adds a bending moment to the horizontal and vertical reactions at the ends of the arch. Fig. 11 shows the positive direction of forces acting on an arch fixed at both ends. Fixed arches can be analyzed when the members are continuous and have elastic properties. However, brick are inelastic, and arches built with individual brick segments cannot carry tensile stresses. Therefore, for practical solution of brick arches, empirical formulas have been derived from elastic theory that place design restrictions on arch dimensions to avoid development of tensile stresses. McDowell2 cites three main conditions for stability in sprung brick arches: 1) the thrust line of the arch should be maintained in the middle third of the thickness to avoid tensile stresses and resulting open joints in inner and outer curves of the arch; 2) the angle between the line of thrust at any joint and a line perpendicular to the joint must not exceed the angle of repose between brick; and 3) the maximum pressure at any point must not exceed the strength of the arch materials at furnace operating temperatures. The first and third conditions are particularly important in designing sprung-arch basic roofs because of the comparatively low hot strength of basic brick. According to McDowell's equation, if the thrust line is maintained within the middle third of the arch thickness, the unit pressure is obtained as follows: where p = unit pressure in psi, F, = resultant thrust normal to skewback in pounds per foot, t = arch thickness in inches, and z = distance in inches of thrust line from arch axis. When the resultant thrust normal to the skewback acts along the arch axis, z equals zero and unit pressure is simply the thrust divided by the cross-sectional area. If the thrust line moves to the limits of the middle third of the arch thickness, beyond which tensile forces would develop, z then equals one-sixth of the arch thickness and the unit pressure is double that when the thrust line is acting

Jan 1, 1968

By Sathit Tandanand

This report presents a Bureau of Mines study on the time-dependent behavior of coal measure rocks for future implementation in stability analysis and safety evaluation of in-mine rock structures. This initial study focused on moisture adsorption rate and strength degradation of shales in Pennsylvanian coal-bearing strata in the Illinois Basin. A reaction of clay minerals in Illinois shales with atmospheric water vapor was hypothesized as the adsorption and strength degradation mechanism. Part of energy exchange between shales and the environment was attributed to a free energy controlled by pore pressure of the rock and partial pressure in the environment. The relationships between adsorption versus time and strength degradation versus moisture content were derived and correlated with the experimental data. Partial saturation at various levels of relative humidity occurs within approximately 2 weeks at room temperature. The strength of shales tested decreases linearly with increasing moisture content. When the moisture exceeds 7 pct of the dry weight, these Illinois shales become unstable. To this end, the moisture content is a good predictor of rock strength for shales.

Jan 1, 1987

By C. C. Hustwit

The U.S. Bureau of Mines formulated a new mathematical model to characterize iron oxidation. The new model is intended to replace the currently used model, recommended by the Environmental Protection Agency (EPA), for most acid mine drainage (AMD) treatment applications. The new model was evaluated in a series of five synthetic AMD treatment tests. The initial ferrous iron concentrations ranged from 800 to 2,400 mg/L. In these tests, the Bureau model underpredicted the measured ferrous iron oxidation rates by a range of 3.24 to 8.03 pct. This was considered to be in close agreement after consideration of experimental error. The model proposed by the EPA was also evaluated using the same test data. The EPA model underpredicted the oxidation rates by a range of 77 to 100 pct in four tests and overpredicted by 19 pct in one test. The model formulated by the Bureau expresses that the rate of iron oxidation is a function of a treatment system's oxygen transfer efficiency and is independent of ferrous iron concentration when treated to near-neutral pH's. A new test method for evaluating oxygen transfer in flow-through reactors is also described.

Jan 1, 2010

By S. H. Lorain

This paper is one of a series on mining methods and costs being published by the U. S. Bureau of Mines. The operations of the Quartz Hill Mining Co., near Dewey, Mont., afford an interesting example of the cost of mining small bodies of direct shipping ore; they also illustrate the effect of the unavoidable periods of unusually high exploration and development costs in this type of mining upon the cost per ton of producing ore. The importance of skilled geological guidance and the necessity of avoiding unnecessary overhead and capital expense at small mines are shown. Operating conditions at Quartz Hill are typical of those in many other mining districts of southwestern Montana. It is believed that the costs presented here may be of value in the preliminary estimation of costs to be expected by conservative operators under similar conditions elsewhere. The information contained in this paper was obtained during a visit to the Quartz Hill mine in August 1936.

Jan 1, 1937

By R. G. Travis

1. Reserve estimates have been made for eight coal beds in Monongalia County, W. Va., but only the Pittsburgh, Sewickley, and Upper Freeport beds are important at this time. The Pittsburgh, Sewickley, Waynesburg, and Upper Freeport beds contain the largest recoverable reserves. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 3,526 million tons as of January 1, 1954. Of this total, 3,294 mil-lion tons is in beds 28 inches and more thick. Areas in each bed except the Pittsburgh were omitted from the estimate because available data relative to the bed characteristics are too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1956

By J. W. Merks

"Simulation is the process of designing a computerized model, of a system or procedure, for the purpose of understanding its behaviour and developing strategies to control its operation. Simulation models are rapidly becoming an effective tool for mineral processing plants. Powerful software and fast hardware are more readily available than a basic understanding of the theory of mathematical probability and applied statistics that process simulation models demand.Simple spreadsheet software can be used to develop simulation models that take into account any set of conditions at a mineral processing plant. In addition to an unbiased estimate for each variable in the set on which two-and three-product formulas are based, reliable variance estimates for all variables are required. How to estimate variances, effectively and at the lowest possible cost, and how to compute variances for simple functions such as the metal content of a quantity of ore or concentrate, or more complex functions such as the percentage recovery at a mineral processing plant, are the key to useful simulation models.IntroductionSimulation models for systems and procedures have become one of the most powerful and effective applications for computers( 2.6). Simulations are applied to a wide range of scientific and engineering disciplines. Generally, a model is designed to investigate the effects of changes in and interactions between a set of variables before a system is in operation or a procedure is implemented, by simulating weeks, months, and even years of operation, in a few minutes of computer time. Along with practical and useful applications always comeabuse and misuse. For a simulation process cannot be more reliable than the methodology that was applied to design the model, to estimate variables and variances, to check performance, and to verify validity. A mineral processing plant is a dynamic system that changes continuously as a function of time but within probabilistic constraints that can be estimated by applying statistical tools and techniques to the variables and variances that interact in the system.A model should be designed to simulate not only the set of variables but also the variance for each variable. Models in which constant variances are used to generate normally distributed random numbers, are less realistic than models in which the variances are simulated first, and then used to simulate the variables."

Jan 1, 1991

By Arno C. Fieldner

The objectives of the coal-research activities of the Bureau of Mines are very well expressed in the organic act of Congress establishing the Bureau. It reads as follows: That it shall be the province and duty of the Bureau of Mines, subject to the approval of the Secretary of the Interior, to conduct inquiries and scientific and technologic investigations concerning mining, and the preparation, treatment and utilization of mineral substances with a view to improving health conditions, and increasing safety, efficiency, economic development, and conserving resources, through the prevention of waste in the mining, quarrying, metallurgical and other mineral industries; to investigate explosives and peat; and on behalf of the Government to investigate the mineral fuels and unfinished mineral products belonging to, or for the use of, the United States, with a view to their more efficient mining, preparation, treatment, and use; and to disseminate information concerning these subjects in such a manner as will best carry out the purposes of this act.

Jan 1, 1946

By J. G. Groppo

In 1992, 48 million tons of fly ash (not including bottom ash, boiler slag and FGD material) was produced in the United States, according to the American Coal Ash Association. Of this amount, 27.2% was utilized; although the percentage of fly ash utilized increased from 20% in 1980, there is significant potential to increase utilization. One of the primary driving forces behind increased utilization is increased disposal costs due to more stringent environmental controls and regulation. Fly ash is classified as a natural pozzolan and finds significant use as a cement additive. It has been found to increase the plasticity of the cement mixture while lowering the amount of mix water needed. In addition to improving leveling and finishing properties, fly ash improves pumpability as well as decreases the heat of hydration of the concrete mix which is particularly important in massive concrete structures such as dams where the concrete needs to cool as quickly as possible. The Loss on Ignition (LOI) of fly ash is an important quality when considering utilization. The LOI is primarily due to the presence of unburned carbon and the standard specifications for the use of fly ash as a mineral admixture in Portland cement concrete are given in ASTM C618-89a. which sets an LOI limit of 6%. However, many states have set a more stringent limit of 3%. The primary reason for the lower LOI specification is that carbon adsorbs air entraining agents which limits freeze-thaw resistance. This is particularly important in climates such as the midwestern US where multiple cycles of freezing and thawing are typical in winter.

Jan 1, 1995

By R. E. Fanning

"IntroductionThe Aluminum industry is one of many materials industries which strive to make their material the preferred choice for large volume products. In some applications one material has a natural advantage over others, but more frequently several materials compete with one another, each providing one or more advantages and some trade-offs. Customers may design their product with several objectives such as minimum system cost, maximum customer appeal or maximum manufacturing flexibility, choosing materials which best combine cost and performance. In such markets it may become necessary for a material supplier to enhance the attractive features of the particular material to outweigh its disadvantages.It is difficult, if not impossible, to predict how various materials will evolve. Technological breakthrough, government regulations, material availability or sociological issues may redefine the balance between competing materials. In spite of some uncertainty regarding the competitive position of competing materials, there is little doubt that unrelenting pursuit of product quality improvement and cost reduction are essential to future viability of the aluminum industry. It is the intent of this paper to identify some areas where technological improvement would be beneficial. Thus this paper is a collection of briefly described problems that will hopefully stimulate the thoughts and research required for knowledge based solutions. Rolling ProcessA particular example is the beverage can industry where aluminum, steel, glass and plastics vie for a share of the m.arket. The high cost of aluminum relative to steel or glass requires minimizing the amount of metal per can. The high intrinsic value of aluminum has led to extensive recycling of cans although net metal cost is still higher than that of the competing materials. Intensive engineering of the beverage can led to improved design and better understanding of material requirements. These improvements permitted substantial reduction in sheet thickness over the past decade. The downward trend in metal thickness for beverage can sheet is shown in Figure 1."

Jan 1, 1988

By G. L. Mowrey

One critical element of the U.S. Bureau of Mines (Bureau) autonomous mining research program is the development of a reliable coal interface detection (CID) system. Several candidate CID concepts currently being investigated by the Bureau include vibration, passive infrared, radar, and natural gamma radiation (NGR). To establish which CID sensor technologies need to be developed for a given seam, coal and adjacent rock samples (i.e., immediate roof and floor) are being collected from selected major coal seams in the U.S. and are being analyzed in terms of NGR and other geophysical measurements. Results of the NGR measurements indicate that, in general, all shale and shale-like materials (e.g., drawslate, slate, and fireclay) have higher NGR readings than the coal seam. Consequently the NGR method appears to be a potentially useful CID tool, provided that the immediate roof and floor are both composed of a high percentage of shale-type material.

Jan 1, 1990