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By G. A. Wancheck

Shear tests were performed on several prepared samples of granular and powdery bulk materials to investigate the following parameters: Particle size and distribution, particle movement, moisture content, consolidation of material, bulk density, void ratio, porosity, volume change, and strain rate. A series of shear tests was performed with weight-percent-ratios of minus 0.185-inch tertiary sand and 1-1/2-by l/2-inch tertiary gravel mixtures, and weight-percent-ratios of minus 200-mesh limestone (rock dust) and minus 200-mesh bituminous float coal dust. A comparison was made for shear test results obtained with rectangular and circular shear cells utilizing the large and small direct shear testers. Specifically, the shear results obtained include the angle of internal friction or shear strength of the tested material under known consolidating pressures, and the kinematic angle of friction or coefficient of friction between the interface of a bulk material and a sample wall material. The experimental procedure, tests, and results are given for each parameter investigated.

Jan 1, 1973

By Donald E. Ralston

The Huntsville study area in northeastern Alabama consists of Jackson, Limestone, Madison, and Marshall Counties. Major emphasis was placed on the Huntsville urban area in Madison County to analyze the relationship of urban growth and the minerals industry. Huntsville was delineated into its component urban, suburban, and rural parts for 1964, and the primary area of growth was predicted for 1990. Population estimates were made for the four-county area as a unit and Madison County separately, and projected to 1990. Demand estimates for crushed stone and sand and gravel were made for the same area units and projected to 1990. Analysis of quarry sites in the Huntsville area was made for the present and for the future. The mineral operations of the study area are all located in rural areas; in the case of Huntsville, the mineral sites are located in areas defined as "rural" in the component urban-suburban-rural system. The operations outside Madison County can expect to have minor problems with urban encroachment, while those operations in Madison County can expect major problems associated with urban growth and development. Some of the problems associated with limes tone production can be reduced if producers invest in capital equipment that will reduce the nuisances inherent in this activity. Although urban expansion endangers some quarry operations in Huntsville, topographic and political restrictions which prevent urban expansion can effectively shield quarry operations for some time.

Jan 1, 1970

By W. L. Acherman

The Bureau of Mines found the chemical and galvanic corrosion behavior of the TZM and molybdenum-30 tungsten alloys to be generally equal or superior to that of unalloyed molybdenum in many aqueous solutions of acids, bases, and salts. Notable exceptions occurred in 1 [N] nitric acid, where both alloys corroded appreciably faster than molybdenum. In mercuric chloride solutions, the TZM alloy was susceptible to a type of crevice corrosion which was not due to differential aeration. The alloys were usually not adversely affected by con-tact with dissimilar metals in galvanic couple experiments, but the dissimilar metals sometimes corroded galvanically. Both alloys were resistant to substitute ocean water spray at 60° C.

Jan 1, 1968

By A. G. Starliper

The Bureau of Mines made laboratory investigations to determine the feasibility of utilizing fine tungsten wires to reinforce a number of nonferrous metals and alloys and a superalloy, S-8l6. The composites of tungsten filament and metals were chosen to attain elevated temperature strength and corrosion resistance. Oriented clean or precoated tungsten wires were incorporated with the other metals by extrusion, swaging, and infiltration casting. Although widely varying characteristics were found in the composites, none were considered satisfactory for high-temperature use, chiefly because of reactions between the matrix metal-tungsten surface. Diffusion, solution, and chemical reactions between matrix and tungsten wires were sufficiently slow for some combinations, such as 15 v/o 8-816, to exhibit increased high-temperature strength for a limited time. A few metals failed to wet or bond to the tungsten surfaces, while a few responded after precoating with a third metal.

Jan 1, 1968

By K. N. Karparov

The classical limit equilibrium methods are suspected to be ineffective in predicting the potential for highwall failure in many instances in coal mines around the world. Slope engineers have for many years recognized a block thrust failure mechanism for slope failures, but little work had been done before 2000 to explain the actual mechanisms which must be responsible for the failure. The main reason for this is that limit equilibrium methods implicitly assume rigid blocks, and the resulting force equations must be satisfied everywhere simultaneously for them to have any meaning. This paper will show that the material involved in the slope failure is not rigid; indeed it undergoes considerable permanent deformation during failure. This observation allows the authors to treat the block boundaries independently, because they need not maintain a constant spatial relationship with one another, as is assumed in other methods. To enable analysis of this type the authors assume that the weight of the blocks is evenly distributed. This is reasonable, because the slope material is not strong enough to be self-supporting without some sort of constraint, or strong enough to be able to apply point loads to the surrounding material. The purpose of this paper is to extend the practical application of the analytical method developed from mechanism studies to provide an objective assessment of the risk of slope failure, and therefore guidelines for more stable slope designs. This work is based on studies carried out on two failures in an open pit coal mine in South Africa, and provides a methodology to assess the potential for failure more objectively than is possible with currently accepted methods, while at the same time remaining sufficiently simple to allow a ?back of the cigarette box? assessment by geotechnical engineers on site.

Jan 1, 2009

By Melford H. Salsbury

The maximum net return from the sale of ores and concentrates of gold, silver, copper, lead, and zinc accrues to the producer when these mine products are marketed to the best advantage. Data are presented that the producer, especially the small mine operator, can use to survey available markets and make a preliminary estimate of the net return to be expected from an ore, on the basis of typical mill, smelter, and freight schedules. A review of the industry is presented by States in which recent production statistics are given, marketing facilities are discussed, and locations of principal mining districts, custom mills, and smelters are shown. Explanations of treatment processes, ore types, treatment charges, payments for metals, and deductions are given. Published rail and truck freight rates for mine products, based on marketing patterns developed over many years, are listed and explained.

Jan 1, 1964

By L. C. IlsLey

Many accidents rightly classifiable as electrically caused are not so classified for the reason that in numerous accidents the part that electricity played in causing the fatality is only suspected. For instance, a workman might receive a shock that would cause him to lose his balance and fall beneath a trip of cars; if no one saw the first part of the accident, the cause undoubtedly would be charged to "haulage." This paper covers a brief study of fatal and nonfatal electrical accidents. The first usually result from direct contact with the electrical circuit or electrical apparatus; the second more often are the result of arcing or flashing due to handling defective apparatus or making repairs on "live" equipment or circuits. It is hoped that helpful suggestions may be offered for minimizing accidents of these two classes.

Jan 1, 1938

By Philip Bonanno

The first major project in Boston's new access to Logan Airport was an Immersed Tube Tunnel which extended 3,600 ft. from South Boston to East Boston across Boston Harbor. Twelve tube sections, 300 ft. long x 80 ft. wide x 40 ft. high, were lowered into an excavated trench which was then backfilled. The depth of the trench at mid-channel was approximately 100 ft. below mean high tide. At the East Boston end the tube terminated close to the present shoreline. At the South Boston end the tube terminated approximately 600 ft. inland from the shore line where a ventilation building was required. The depth to subgrade from existing ground at the ventilation structure was approximately 85 ft. The soil profile at this location consisted of 50 ft. of miscellaneous rubble fill, 25 ft. of Boston blue clay, and 10 ft. of glacial till. A small amount of weathered argellite existed at the north end of the structure. Part of the Morrison Knudsen, Interbeton, J.F. White, Joint Venture contract to construct the Immersed Tube Tunnel (ITT) was the construction of a cofferdam at the tube/ventilation building interface. The ventilation building was to be built as part of another contract. The construction of the cofferdam and the excavation to the building subgrade was the responsibility of J.F. White Contracting Company.

Jan 1, 1994

By A. V. Roschin, N. V. Malkov, V. N. Karnoukhov, V. E. Roschin

Reduction interactions in solid phases are widespread and occur in most complex metallurgical processes. Among these processes, reactions between oxides and carbon have a special importance. The authors conducted experiments for comparison of reduction by different reducing agents of impregnated chromite ores, in which grains of the reducible chromite spinel are isolated from direct contact with the reducing agent by layers of non-ore material. The results of the experiments have revealed that the beginning of reduction is preceded by thermal and impurity order-disorder transformation of the oxide lattice whilst the transformation of the oxide lattice into the metal lattice takes place as a result of removal of oxygen anions from the zone of metal germ nucleation. Since anions are charge carriers, increase of their mobility can be monitored by changes in electrical conductivity of oxides. Respective measurements of electrical resistance of ores of different metals and a number of pure refractory oxides under heating have indicated that the beginning of reduction coincides with the time of drastic (tens of thousands times) increase of conductivity of the oxides. Besides, the temperature of the beginning of carbon-thermal reduction is in line with the Tammann temperature, i.e. the temperature of transition from the predominantly surface diffusion to volume diffusion. Segregation of metals from the oxide lattice occurs as a result of merging of anion vacancies with defect electrons on defects of the oxide lattice. The transformation of the oxide lattice into the metal lattice requires a certain concentration of anion vacancies and inflow of electrons from the reducing agent to the site of metal segregation. Such inflow has no difficulties due to the mixed anion-electron nature of high-temperature conductivity of oxides. Thus, the reduction is not determined by oxygen diffusion, it is determined by oxygen vacancies diffusion whose speed exceeds the speed of oxygen diffusion by orders of magnitude. This determines that the kinetics of reduction considerably exceeds the kinetics of oxidation at similar temperatures since oxidation proceeds by means of mass transfer of oxygen through the layer of the generated oxide.

Jan 1, 2004

A BRIEF DESCRIPTION OF TELPHER HANDLING AND BLAST FURNACE EQUIPMENT.The various sections will be described in the following order:(a) Telpher Handling and Storage Bins.(b) Blast Furnaces.(c) Slag Disposal.(d) Bullion Handling to Drossing Kettles.(e) Copper Drossing.(f) Copper Matte Furnace.(g) Bullion Delivery to Refinery.(h) Fume Handling.(a) TELPHER HANDLING.The telpher installation is an all-steel structure designed to carry out the work of assembly and delivery of charge materials to the blast furnaces.To simplify description, the primary telpher installation will be divided into three (3) sections:-No. 1 Section. 395 ft. long, running north and south, parallel to the water front, and so located that coke, which...

Jan 1, 1937

By G. L. Oldright, J. D. Sullivan, W. E. Keck

"An apparatus and procedure developed in the laboratory of the South-west Experiment Station of the Bureau of Mines are capable not only of determining the rate and volume of penetration of solutions into porous materials but also of determining the total volume of voids within particles of porous material, and the density. The method is applicable to ores, bricks, concretes, tiles, filter bottoms, or other porous materials of this nature. As will be made clear in the descriptive matter to follow, the method measures (a) the volume of voids within the porous materials and is not concerned with the interstitial space between the particles.Porous materials usually contain some large voids and also pores that are capillary in nature. To measure the total volume of voids in a sample it is necessary to replace the gas or gases within the voids with some liquid of known density. The large cavities can be filled quite readily, but under ordinary conditions a long time may be required to fill capillary pores. As many porous materials are of a decomposable nature it is necessary to evacuate the porous materials and then submerge them in a liquid of known density to bring about saturation in a short time. Then by the use of a hydrostatic balance the volume of porous material (solid itself) can be determined. To determine the volume of porous material plus voids it is necessary to coat the sample with some material, such s paraffin, which will prevent solution from entering the voids; then, by means of a hydrostatic balance, the volume of porous material plus voids is determined and by subtracting that of the porous material from this the volume of voids is ascertained. The rate of penetration of solutions can be determined either (a) by measuring the change in weight as the sample becomes saturated when immersed ni a liquid of know density, or (b) by measuring the volume of liquid penetrating with a dilatometer. In either instance, due to the fact that some penetration takes place as soon as the sample comes in contact with solution and before a reading can be taken, the sample must be paraffined to determine the total volume of penetration. Since many porous materials partly decompose and disintegrate in liquids the rate and volume of penetration can better be measured by dilatometer than by the change in weight, as saturation takes place when immersed in a liquid. The details of procedure for determining (a) total volume of voids, and (b) rate and volume of penetration are given in this paper."

Oct 1, 1930

By Elbridge W. Gresseth

Rock deformational structures in a deep mine were analyzed by petrofabric techniques to learn (1) the relative magnitude and direction of the principal stresses involved in tectonic deformations prior to mining, (2) the preferred orientation of rock planar discontinuities which define rock anistropy prior to mining, and (3) the relationship of mining-induced rock failure to inherent rock stresses and inherent rock anisotropy. Rock fabric elements used for petrofabric analysis consisted of bedding planes, faults, joints, fractures, foliation, sericite plane (001), quartz axis [0001], quartz deformation lamellae, and microfractures. Structures and structural symmetries from different areas within the mine and from different scales of observation were compared to learn the nature of rock anisotropy and the orientation of the principal stresses defined by rock deformations. Analysis of such fabric as regional and macroscopic faults, b-c joints, quartz [0001], sericite (001), and microfractures, indicate that during the epochs of tectonic deformation, the maximum and minimum principal stresses were horizontally oriented and acted along northwest and northeast axes, respectively. This condition of regional stress appears to have continued during folding and the associated period of faulting. The most recent tectonic deformation represents a rotation of the minimum principal stresses into a vertical position, as shown by the development of a tensile joint system, quartz deformation lamellae, and microfractures. Good interscale correlation and statistical homogeneity of tectonic fabric indicate a stress field homogeneity in this area during tectonic deformation. Rock physical anisotropy is genetically associated with tectonic fabric and consists of preferentially oriented planar discontinuities intersecting along a nearly vertical axis. The mining-induced deformations were correlated with the inherent rock anisotropy which either directly controls or greatly affects their development. This phase of rock deformation shows a greater degree of stress field heterogeneity than was the case with tectonic deformations This is explained as a result of nonconfinement afforded by underground openings and the increase in ground stresses due to mining activity"

Jan 1, 1968

By A. McLean, M. Iwase, K. Wakimoto, K. Katogi, Y. Kikuchi

One of the greatest obstacles to the application of physical chemistry principles to the elucidation of slag-metal reactions is a lack of knowledge of activities of the reacting species. To a large extent, oxygen potential of the slag phase governs iron and steelmaking practice. Without oxygen control by means of appropriate sensors, the behaviour of the other elements cannot be managed. In this paper, measurements of the FeO activity with various types of electrochemical FeO sensors will be described together with examples of their applications for improved strategies toward better practice for ladle metallurgy and sulphur and manganese distributions between slag and metal phases during steelmaking. Measurements of FeO activity have also been made in order to improve dephosphorization reactions. This type of work has led to significant reduction in volume of slag generated within the steelmaking vessel, which in turn has important implications for refractory wear, metal yield, alloy recovery and improved productivity. Finally, an on-line sensor is described that permits the oxygen potential to be determined for both the metal phase and the slag phase during steelmaking in the BOF.

Jan 1, 2004

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By F. B. Samani, B. Stabel

The 1,000 MW Hydro Power Station Masjed-e-Soleiman (formerly called Godar-e-Landar) in Iran is under construction since 1992. The rock engineering aspects of the major underground structure, i.e. the powerhouse cavern shall be reported on in detail. The geotechnical investigations are described and results given. The results of several geotechnical analyses are presented. The designed and executed rock support is given. A description of the monitoring systems and typical measurement results obtained during and after excavation are presented. The lessons learnt during construction of the Stage-I powerhouse cavern were applied on the extension of the powerhouse cavern, which is to house an additional 1000 MW. Details regarding the unexpected behaviour of the Mudstones are given. Die 1000 MW Wasserkraftanlage Masjed-e-Soleiman (vormals Godar-e-Landar genannt) befindet sich seit 1992 in Bau. Dieser Artikel berichtet im Detail über die felsbaulichen Aspekte der Untertagebauwerke, insb. der Maschinenkaverne. Die geotechnischen Untersuchungen werden beschrieben und deren Ergebnisse wie die Ergebnisse verschiedener Berechnungen werden präsentiert. Die geplante und die ausgeführte Felssicherung wird angegeben. Die eingebauten Überwachungseinrichtungen werden beschrieben und typische Ergebnisse während des Aushubs und danach werden dargestellt. Die Erfahrungen beim Aushub der Kaverne der Stufe I wurden beim Entwurf der Kaverne der Erweiterungsstufe II, die weitere 1000 MW beherbergen wird, berücksichtigt. Details zum unerwarteten Verhalten des Schluff-/Tonsteins werden angegeben. La centrale hydroélectrique de Masjed-e-Soleiman (dénommée anciennement Godar-e-Landar), d’une puissance de 1.000 MW, est en construction depuis 1992. Un rapport détaillé sera présenté sur les aspects relatifs à la construction en enrochements de l’aménagement souterrain principal, à savoir la caverne abritant la salle des machines. Une description des investigations géotechniques réalisées y est fournie ainsi que les résultats correspondants. En outre sont présentés les résultats de plusieurs analyses géotechniques. L’ancrage dans la roche tel que projeté et réalisé est présenté. Une description des systèmes de contrôle ainsi que les résultats de mesures typiques obtenus au cours des travaux d’excavation sont donnés. Les leçons tirées lors de la construction de la Phase 1 de la caverne de la salle des machines furent appliquées à l’extension de la caverne de la salle des machines, qui doit abriter une unité supplémentaire d’une puissance de 1.000 MW. Par ailleurs, des détails sont donnés sur le comportement inattendu des argilites.

Jan 1, 2003

By Jeff Jackson, Paul Axtell, David Graham

The Montana Department of Transportation recently awarded a contract to construct a replacement bridge across the Clark Fork River in Heron, MT. Both abutments and both intermediate bridge bents were to be founded on 6-ft and 8-ft diameter, permanently cased drilled shafts with rock sockets, respectively. Two drilled shafts per substructure location were designed for a total of eight drilled shafts. The original design included 6-ft diameter drilled shafts at the abutments but the Contractor elected to submit a Value Engineering proposal that increased them to 8-ft diameter. On the basis of the subsurface exploration program, extremely challenging subsurface conditions were known to exist, including the potential presence of large boulders within the predominantly sand and gravel soil matrix. The successful bidder elected to use an oscillator to install the permanent casing to the top of bedrock, while simultaneously removing the spoils from inside the casing with a clam-grab. On seven of the eight shafts, this approach worked well. Unfortunately, on one of the shafts, the casing met refusal on one or more boulders encountered in the predominantly sand and gravel soil overburden. Following several attempts, and despite several variations of approaches, it was determined that the casing could not be advanced beyond the obstruction without unacceptable risks to the pile-supported temporary work trestle (i.e., loss of soil and reduction in pile capacity for the foundations supporting the work trestle). To mitigate the problematic drilled shaft, a unique solution was designed and successfully constructed. The solution involved the construction of seven 16-in diameter micropiles constructed within the confines of the obstructed casing. The micropiles were drilled to bedrock through the sand, gravel, and boulders and include rock sockets to satisfy axial design requirements. The micropile casing thickness, grade and grout strength were designed to provide adequate flexural strength as well as to satisfy other design requirements. Upon completion of the micropile installation, the upper portion of the drilled shaft above the boulders and within the permanent casing was constructed as usual. This paper discusses the difficult subsurface conditions at the site, the drilled shaft construction difficulties, and the design and construction of the micropile solution.

Jan 1, 2018

By Vedala Sastry

Longwall mining for coal extraction in deeper deposits is gaining momentum in India, due to the increasing stripping ratios and depletion of shallow deposits amenable for surface mining. In longwall mining, presence of multiple seams with varying interburden thickness is a major problem especially while planning for over-mining. An investigation program was taken up to analyze the effect of the presence of goaf and virgin coal blocks in already developed and extracted lower seam by bord and pillar mining, on the stress distribution in the longwall panel in upper seam. Studies revealed marginal increase in horizontal and shear stress as longwall face passes above goaf to the virgin area present in lower seam. Stress distribution over chock shields was considerably affected when the face in upper seam reached 15-25m zone above the galleries in the lower seam. A clear influence of the presence of solid coal, galleries and goaf in lower seam was found in the loading of longwall panel in upper seam.

Jan 1, 2007

By A. J. Van Der Merwe, J. F. Erasmus

One of the valuation approaches applied to Advanced Exploration Areas and Pre-Development Projects is the so-called ?in situ Mineralization Method? or the ?Yardstick Method?. This method is based on the concept of a known undeveloped Mineral Resource being worth a certain fraction (the ?Yardstick?) of the contained commodity value (?metal in ground?), using commodity prices ruling at the date of valuation. The Yardstick value is derived usually from an average market-based figure obtained from an analysis of recent transactions and is expressed as a monetary value per ounce or per tonne. It maybe modified to accommodate the quality (e.g. grade) and category (e.g. confidence level) of the Mineral Resource/Reserve involved and the time, effort and expenditure expected to be involved in bringing the project to fruition. Some eighteen recent and relevant transactions were analysed, allowing the following general conclusions to be reached: ? a Yardstick with which to value undeveloped PGE mineral resources is likely to range between 0.5% and 2.5% of the in-ground contained metal value ? the expected method of mining (especially with regard to mining costs) and the grade of the mineralization both have a strong influence on the Yardstick ? the status (classification) of the Mineral Resource has some influence on the Yardstick and ? the ruling price of platinum and the regional location of the deposit appear to have insignificant influences on the Yardstick.

Jan 1, 2006

Between February and August of 1986, Dr Alfred Petrick visited New Zealand sponsored under a Fulbright grant administered by the New Zealand-United States Educational Foundation. The grant supported a research project completed by Dr Petrick having as an objective, the preparation of a preliminary economic evaluation of the mining of six Otago lignite deposits as a source of energy for steam power generation or in liquid fuels. The research is limited to consideration of preliminary geological and engineering data on the six deposits and to the time constraints of the Fulbright visit. This paper is a summary of the final Fulbright report. The complete report including the listings of the computer programs is available from the Otago School of Mines.

Jan 1, 1986

By Evelynn Stirling

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Aug 1, 2013