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By Ernest L. Corp

Seepage forces computed by a finite-element flow program are combined with gravity forces in an elastic-plastic stress-analysis program to determine the stability of mine-waste slopes. Computer output provides a cross-sectional plot of the dam or embankment showing the safety factors for each element. The combined finite-element program called SEEP-SLOPE was used to analyze several trial embankments and the 1972 Buffalo Creek Dam failure Safety factors computed by the finite-element method (FEM) were compared with those computed by Bishop limiting-equilibrium method. For individual slip circles, there was little correlation between the factors of safety computed by the two methods. Both predict failure, but FEM shows a different mode of failure plus development of potential failure zones not indicated by conventional methods. Besides having a better theoretical basis than the Bishop method, FEM requires no assumptions regarding the location or geometry of the failure surface. As a result, the program will show progressive development of a failure zone, and areas can be pinpointed where remedial measures should be taken. In addition, nonhomogeneous cross sections can be analyzed, and zones of potential piping can be defined.

Jan 1, 1975

By R. A. Guereca

The Bureau of Mines conducted an analysis to determine criteria for steady-state, laminar flow boundary conditions for a coiled-tube gas viscosimeter by comparing experimental data from a thick-walled, stainless steel capillary in a horizontal, straight-tube condition, with similar data taken after the same capillary was formed into a helix. Overlapping volumetric f10wrates and pressure drops are covered for both configurations at pressure levels of 28, 225, and 1,000 psia at 3000 K. Friction factor, Reynolds number, and Dean number correlation plots show conditions where the coi1ed-tube flow deviates from straight-tube flow. The coiled-tube data indicate departure from Poiseui11e steady-state laminar flow at a Reynolds number close to 390 and a Dean number of about 15. Below these conditions and consistent with the data reported, Dean's circulation appears negligible. For the particular coil used, a conservative upper limit of 10 is chosen for the Dean number corresponding to an upper limit of about 250 for the Reynolds number.

Jan 1, 1967

By Izabela Vieira Teixeira Neves

Os aços inoxidáveis ferríticos estabilizados com nióbio apresentam grãos mais refinados e uma recristalização mais homogênea quando comparados aos não estabilizados. Contudo, em seu processamento industrial, mais especificamente na laminação a quente, utiliza-se um recozimento antes da etapa de laminação a frio e do recozimento final, visando a homogeneização da microestrutura de entrada. Objetivando a melhoria das propriedades de estampagem e soldagem em aços com adição de Nb, bem como uma possível redução de custos com a eliminação do recozimento após a laminação a quente, foram realizados testes com o aço inoxidável 430 estabilizado com Nb de forma a acompanhar a evolução de sua microestrutura e textura após ser submetido à laminação a frio com 80% de redução e recozimento a tempo constante (900 s) e diferentes temperaturas, 400°C a 1.000°C, partindo-se de ambas condições iniciais. A quantificação da recristalização foi feita através da fração amaciada em função da temperatura, obtida pela curva de microdureza Vickers. A interpretação da textura foi obtida por exames por microscopia eletrônica de varredura e difração de elétrons retroespalhados (EBSD). Para o encharque de 900 s, a recristalização se inicia a 700°C. A 750°C o aço se encontra completamente recristalizado, alcançando um tamanho de grão da ordem de 8,0 µm. Os resultados mostram que o aço não recozido após a laminação a quente apresentou grãos mais refinados e ligeiramente menores. Além disso, notou-se o aumento da fibra gama e redução da fibra alfa em ambas as condições de processamento à medida que a recristalização progredia.

Aug 8, 2018

By Kyle Apple

The following is a case study of how LuckStone Corporation improved their blast monitoring and documentation program. A number of resources already at their disposal have been utilized to improve the body of data collected from each blast. The tools being used include GPS, aerial photos, and a user-friendly push button format excel spreadsheet. The data collected include product by product records of materials used, distances to all concerned neighbors, seismograph data, etc: The spreadsheet has been designed to perform an ongoing analysis of blasting trends. The program has been carried out at a corporate level and is in use by blasters at each location. This paper addresses the advantages and drawbacks of this program. It also addresses the ways in which the various tools were integrated, Discussed as well is the need for simplicity when bringing “new” technology to the field and the steps taken in familiarizing the end user to changes.

Jan 1, 2001

By Arnold O. Tanner

The domestic mining industry gained more strength in 1988 as the healthy comeback that became evident in 1987 continued and grew for many commodities. The increasing and more stable commodity prices, still predominantly in the metals sector, reinforced both the new ways of conducting business and the use of technological advancements in successfully lowering operating costs during the last 4 to 6 years. Some commodities and companies still struggled to survive, but increases in productivity and profits were becoming more common.

Jan 1, 1990

By Kenneth W. Luke

In the development of the ultimate pit limits for a narrow ore body, pa¬rameters necessary in the design of a functional, or working, pit become highly sensitive factors in the determination of ore reserve levels and their associated waste to ore stripping ratios. Through the use of geologic cross sections, ore reserves can be roughly calculated by utilizing a straight line approximation for pit wall slopes. The optimum position of the pit floor can be substantially altered from such a preliminary design though with the introduction of functional mining parameters, such as a ramping network, and working bench heights, berm widths, and bench to bench wall angles. Originally a computer program was developed to quickly evaluate changes in cross-section pit design with minimal alteration of input data. After developing a satisfactory technique of cross-section evaluation which incorporates working mine parameters, an optimization algorithm, or procedure, was developed and included in the program to eliminate much of the tedious manual decision-making required in determining the optimum location of the pit floor on each cross section. Optimization in this case implies the maximum profit pit. When pit and processing costs are defined or hypothesized, this computer program can be used to design the maximum profit pit, constrained by the recognized functional mining parameters. A second way of stating the optimization is that the program can be used to develop a pit design which minimizes waste stripping at any desired ore reserve level. The basic method of cross-section evaluation parallels present manual methods. Program input is a combination of data obtained directly from cross sections developed for, geological interpretation and pit design parameters selected by the mine planner. As a result it is easy for the mine planner to comprehend what the program is accomplishing, and thus participate in the development of the computer assisted design.

Jan 1, 1971

By Ronald M. Hays

During the twentieth century the Mesabi Range in northeastern Minnesota has been the major source of iron ore for American steel mills. The Mesabi Range extends along an iron bearing outcrop known as the Biwabik formation. This outcrop is some 120 miles long and up to three miles wide. The formation is from 200 to 650 feet thick and dips 5 to 10 degrees to the southeast. The iron content of the original Biwabik formation was quite uniform, but much of this formation has been subjected to alteration. Thus major variations in iron content and mineral composition exist both laterally and vertically in the present Biwabik formation. The remaining unaltered iron formation includes the magnetic taconites which are commercially processed by Reserve Mining, Erie Mining, Eveleth Taconite, National Steel, Butler Taconite, and U.S. Steel. These six operations have a capacity of 32 million tons. per year of iron pellets and have produced approximately 170 million tons of pellets since 1956. Capacity for another 30 million tons per year of pellets is being considered by the industry for the next ten years. This increase will be obtained by construction of new plants and expansion of present operations. Thus by 1977, it is estimated that approximately 60 million tons per year of iron pellets will be produced from magnetic taconite on the Mesabi Range. The portions of the Biwabik formation subjected to intense alteration resulted in the direct shipping, wash and heavy media ores. Since 1892, 1.8 billion tons of direct shipping ore have been shipped from the Mesabi Range. This ore has been the major source of iron for American steel mills. In 1966, 12 million tons of direct shipping ore and 18 million tons of wash, jig, heavy media and other gravity concentrates were shipped from the Mesabi Range. These products generally have poorer physical and chemical properties than the iron pellets produced from magnetic taconite. It is predicted that the shipment of these materials will decrease from about 30 million tons in 1966 to 6 to 8 million tons in 1975. This decrease will be due to depletion of reserves and poor quality product.

Jan 1, 1968

Variety among deserts is nearly as great as among other climatic environments. Common to most deserts, and to areas downwind from them, is the dominance of aeolian transport of surface material, at least during some seasons of the year. The result is dilution of local surface materials with varying proportions of chemically uniform fine sand and silt, often imported by the wind from remote areas. Fortunately, desert pavement,.even though separated from bedrock by a meter or more of nearly pure loess, is simply a diluted reflection of nearby bedrock. Infiltration of loess through the surface debris and the rudimentary soil-forming processes in the desert usually preserve the integrity of the pavement. This pavement, or its "downstream" derivatives, provides a suitable sample for exploration geochemistry if proper care is taken to circumvent the aeolian dilution. The simplest and most commonly used method of circumventing the dilution is to use a coarse fraction of soils or stream sediments, discarding or retaining the finer fraction depending upon the magnitude of the dilution. Where the coarse surface debris is composed of rock chips representative of the bedrock sources, the method is successful. Under most circumstances the coarse fraction of the surface material will give a fair representation of gross lithology and will occasionally give an indication of mineral- ization. The major drawback to this approach is that selective weathering and erosion in the vicinity of mineral deposits often lead to the loss of ore minerals into the finer fraction, leaving a coarse residue enriched in feldspar and particularly in quartz; thus, the geochemical signature from a mineral deposit is effectively reduced or completely masked. The second most commonly used method to overcome aeolian dilution, and probably the most effective at present, is to use a heavy- mineral concentrate. This approach presupposes that the chemical signature sought resides in a heavy mineral. Fortunately, the arid weathering cycle is conducive to the formation of a wide variety of secondary ore

Jan 1, 1988

By José E. Rondoña

El presente trabajo desarrolla un estudio comparativo de la producción de dos tipos de hornos usados en la fundición de cátodos de zinc en la planta de La Oroya, para asi determinar cúal es el equipo más idóneo para futuras expansiones del proyecto. De los puntos comparativos se encontró que el horno SICE desarrolla más productividad de personal en operaciones, así como en el rendimiento de la energía eléctrica. Mientras que respecto de las consecuencias de las filtraciones del metal, se encontró que el horno Ajax es el más adecuado, dado que la producción de barras se afecta solo en la producción que el horno afectado representa en la instalación total. Por ende, es conveniente el uso de dos hornos SICE tamaño mediano dada la capacidad y productividad de esta.

Nov 20, 1967

By Charles B. Manula

Judging from the rapid pace of increased demands for mineral products, technological forecasting will become an increasingly necessary tool in mining. Even though the mining industry in 1966 produced more are than ever before, current extraction rates are only a fraction of what is expected in the later years of the twentieth century. If metal and mineral commodities continue to hold their respective and present share of markets, the prospect of coping with demands from a population that will double in the next thirty years can become an impossible task when viewed outside the limits of technological advance and change. Those mining companies that are doing little to develop new and expanding horizons for their operations cannot expect to survive. Nearly 90% of all metals and mineral products consumed last year was recovered by open-pit mining. This has placed great pressure on this segment of the industry which, consequently, has resulted in some spectacular developments. Already production rates at many places are dwarfing those of the Panama Canal and other well-known earth moving projects which are frequently identified as massive undertakings. With projects of this scale, the need for increased sophistication of engineering, planning, management and administration of modern mining installations has never become more apparent. The design of complete systems for the mine and plant that fit the mould of today's business and social environments is undergoing an evolutionary process.

Jan 1, 1968

By H. Karabulut, S. Gündüz, K. Karacif, M. A. Erden

The corrosion properties of iron-based composite materials containing graphite and silicon carbide (SiC) reinforcement were investigated. The effects of silicon carbide reinforcement were investigated by adding 0.5% graphite and 1%, 2%, and 4% SiC. A powder metallurgy method was used to produce the composite samples. Iron, graphite, and silicon carbide powders were blended for one hour with a threeaxis mixer and then unidirectionally pressed under a pressure of 750 MPa. After pressing, the composite materials were sintered at 1100°C for one hour. The corrosion properties and microstructure, density, and hardness properties of the composite materials that can affect the corrosion properties were also investigated. It was determined that the pore ratio and hardness of the composite material increased, and corrosion resistance decreased, with increasing silicon carbide content.

Jun 2, 2022

By Henry Rumfelt

Strip mining in the domestic coal industry is contributing a greater proportion of overall production than at any time in the past. U. S. Bureau of Mimes statistics show that the percentage of total production mined in 1958 by stripping methods in- creased to more than 30 pct, up from 22 pct in 1951. The tendency to favor strip and open pit mining exists in other mining activities, but such trends are not as clearly outlined as in the coal industry. Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating over- burden and dumping it in the spoil position where it remains indefinitely). Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically, Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating overburden and dumping it in the spoil position where it remains indefinitely).

Jan 1, 1960

By Jetson Lemos Ferreira

A necessidade de redução de espessura de componentes automotivos para atender a demanda por veículos mais leves, aliada ao aumento da complexidade geométrica das peças, tem exigido a utilização de aços de maior resistência e com boa conformabilidade. No entanto, a baixa capacidade de flangeamento dos aços de alta resistência limita a aplicação destes materiais em peças de geometrias mais complexas. O método de corte dos blanks tem influência decisiva na capacidade de flangeamento desses aços, que é avaliada em laboratório por ensaios de expansão de furo. Foi avaliado o efeito da folga de corte por cisalhamento e da qualidade da superfície de bordas puncionadas na capacidade de expansão de furo de aços Interstitial Free, High Strength Low Alloy e Dual Phase. Os resultados indicaram que para o aço IF, folgas entre 10% e 20% da espessura e que propiciaram bordas de corte dos tipos 2 e 3, segundo a classificação do ASM Handbook, foram as que geraram maior expansão de furo. A maximização da flangeabilidade foi conseguida para as folgas de corte de aproximadamente 15% (bordas de corte tipos 3 e 4) para os aços DP e em torno de 20% (bordas tipos 2 e 3) para os aços HSLA.

Jul 30, 2018

By Aditi Sharma, Sumanta Haldar

Scouring of soil is the major concern forthe various hydraulic structures built in the flowing rivers since scouring impacts the bearing capacity of foundations. Hence, consideration of scouring in the design of foundations for hydraulic structures is crucial. Pile groups in bridges are subjected to combined vertical and horizontal loading due to self-weight, live loads, vehicular impacts, wind load, earth pressure, and current. Hence, an assessment of the combined bearing capacity of pile groups subjected to scour is essential for the safety of the structure. This paper aims to analyze the bearing capacity of pile group supporting the bridge under combined loading i.e., Vertical (V) and Horizontal (H) loading subjected to local scour. Three-dimensional finite element model (3D-FEM) of a 3 x 3 pile group embedded in homogeneous sandy soil is established in Abaqus (2018). Mohr-Coulomb plasticity model is used for the soil domain. The pile group is modelled as linear elastic. Finally, V-H yield envelopes are obtained with and without scour. The potential impact of different parameters, such as angle of attack, flow velocity, depth of flow, and different pile length-to-diameter ratios (L/D) and spacing-to-diameter ratios (S/D) of pile group on V-H yield envelopes is studied.

Sep 1, 2022

By M. Kitazume, H. Imai

The deep mixing method was developed in Japan and put into practice in the middle of 1970s. Since then, the wet and dry type methods have been applied for various improvement purposes in Japan. One stork of mixing tool produces a column shape of stabilized soil in a ground. By the series of productions, arbitrary shape of improved ground can be constructed by overlapping each columns. It is specified to complete the overlapping within 24 hours in order to ensure the tight connection of the columns. However, it can not be completed within the specific time in some cases due to bad weather or machine trouble, which causes a cold joint in the improved ground. In this study, the influence of the cold joint to the behavior of the block type improved ground is examined by a series of centrifuging model tests and FEM analyses. It is found that the ground behavior is influenced by the position of the cold joint, where the cold joint at the sea side shows a little influence to the behavior but one at the port side causes large decrease in the stability of the improved ground.

Sep 8, 2021

By J. G. Pearson, F. H. MacDougall, A. G. Galley

The difference in age, host rock lithology, alteration and style of mineralization indicates a fundamental difference in the format ion of gold deposits in the Flin Flon and Amisk Lake areas. The Flin Flon area contains early quartz-sulfide-gold veins fo rmed within intermittently active fractures and later plutonic hosted deposits thought to be generated in a porphyry system. In the Amisk Lake area two types of gold occurrences are recognized: I) gold-quartzcarbonate- sulfide veins within or flanking fault zones and 2) structurally and stratigraphical ly controlled zones of dissem inated and vein type sulfide-gold mineralization within extrusive and intrusive rhyolite and dacite porphyries. Both types of deposits are set within supracrustal rocks. are accompanied by intense alteration haloes and were formed prior to the major deformation event suggesting an early, epigenetic hydrothermal origin.

Jan 1, 1986

By R. D. Irwin, W. M. Mullins, E. A. Medina

"Various stability criteria are introduced and thermo-kinetic models for metallurgical processes are used as concrete examples for evaluation. Kinetic criteria for the process of dynamic recrystallization are proposed. These criteria are compared to the non-equilibrium thermodynamic approaches discussed in the literature. The application of macroscopic stability criteria to materials processing is then discussed.IntroductionThe mechanical behavior of metals at elevated temperature is very well predicted by any of several empirical constitutive relations. Typical is the power-law (or Swift's) form,Equationwhere r-is the stress, y is the strain and m, n , t0, y0 and Q are material constants. This form has been used with some success in the metals processing area [1]. In general, though, all of the empirical constitutive equations are static, failing to account for any dynamical properties of the system they seek to describe.The physics of warm deformation is qualitatively well understood. An example is power-law creep, where the dominant mechanism is assumed to be lattice diffusion limited climb of dislocations, which allows the strain-rate to be determined by the applied stress through"

Jan 1, 1997

By M. S. Safarzadeh, V. Agarwal

"The solvent extraction of cerium(III) and samarium(III) from mixed solutions of all rare earth elements (REEs) except promethium using PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), an acidic extractant, was investigated. The effects of aqueous equilibrium pH, various acids (sulfuric acid (H2 SO4 ), hydrochloric acid (HCl) and nitric acid (HNO3 )), initial metal ion concentration and extractant concentration on the solvent extraction of Ce(III) and Sm(III) were systematically studied. From the experimental results, HNO3 and HCl were found to be the preferred aqueous media for the solvent extraction of both Sm(III) and Ce(III). The most promising experimental conditions of pH, PC88A concentration and metal ion concentration were identified for the extraction of Ce(III) and Sm(III). Separation results showed that H2 SO4 at pH 2 provided the best separation between Sm(III) and Ce(III). IntroductionIn recent years, demand for rare earth elements (REEs) has increased significantly because of their many commercial applications. REEs have especially important high-tech applications owing to their unique physical and chemical properties, and they are used in a wide range of areas such as catalysts, ceramics, magnets, lasers, glass, neutron absorption and alloys. As REEs have very similar physicochemical properties, their separation and purification from each other is challenging and gaining significant interest. Samarium (Sm) and cerium (Ce) are found in different REE minerals, including bastnäsite ((Ce,La,Nd(CO3)F), xenotime (YPO4) and monazite ((Ce,La,Nd,Th)PO4) at major production sites in the United States and China, as listed in Table 1 (Bleiwas and Gambogi, 2013). The most common acidic organophosphorous extractants used for REEs extraction and separation are DEHPA (di-(2-ethylhexyl)phosphoric acid), PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) and Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) (Sarangi, Reddy and Das, 1999; Surampally et al., 2012; Tian, Jia and Liao, 2013). Out of these extractants, PC88A is known for providing higher separation factors (Acharya, Mishra and Misra, 2015). El-Hefny et al. (2010) investigated the kinetics of the solvent extraction of Sm from chloride media using sodium salt of Cyanex 272 and reported the extracted species to be Sm(OH)A2•2HA. Lee et al. (2005) investigated the solvent extraction of Sm(III) with PC88A and saponified PC88A from chloride solutions and found the stoichiometry of the extraction reactions to be 1.5 with PC88A and 3 with saponified PC88A."

Jan 1, 2017

By T. C. -M. Cheng

Iron removal and disposal in zinc plants has imposed a major environmental challenge to the industry. Among the existing options of precipitating iron as jarosite, goethite, and hematite, the Hematite Process seems to be the best candidate for the future development of a waste-free technology, because of its potential of producing saleable iron oxide residues for feed in iron-steel making industry. Unfortunately, under the current practice of the Hematite Process, it is not possible to produce iron residues clean enough to meet the specifications of the said industry. In this paper, the practice of industrial hematite precipitation and the relevant technical literature are reviewed with the objective to identify the critical processing parameters which are responsible for the contamination of hematite, particularly with sulfur and zinc. The analysis is conducted from a crystallization theory standpoint with emphasis given to the role of supersaturation with respect to the cleanliness of hematite precipitates.

Jan 1, 1997

By X. Shi, K. S. Kaspnak

"The generation of free radicals from reactions of nickel (Il)-thiol complexes with molecular oxygen and model lipid hydroperoxides was investigated by electron spin resonance (ESR) utilizing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap. Incubation of nickel (II) [Ni(II)) with cysteine in an aerobic environment generated hydroxyl (·OH) radical, which then reacted with cysteine to generate a carbon-centered alkyl ( · R) radical. Radical generation was inhibited under a nitrogen atmosphere. Model lipid hydroperoxides, cumene hydroperoxide, and I-butyl hydroperoxide enhanced the yield of these radicals and also generated an alkoxyl (·OR) radical. Radical yield decreased by approximately half under a nitrogen atmosphere. Although histidine did not cause radical formation in the reaction between Ni(II) and cumene hydroperoxide under aerobic conditions, the addition of histidine to a mixture containing Ni(ll), cysteine, and cumene hydroperoxide under the same experimental conditions increased the yield of · R radical but lowered the yield of ·OR and ·OH radical adducts. It thus appears that histidine caused the ·OH attack to be more site-specific. Similar results were obtained utilizing 1-butyl hydroperoxide. Penicillamine or N-acetylcysteine yielded similar results except that under aerobic conditions, reaction between Ni(ll) and N-acetylcysteine without hydroperoxide did not generate a significant concentration of free radicals. Under the same experimental conditions, cystine did not generate any detectable free radicals, suggesting an important role of the -SH group in Ni(II)-mediated free radical generation. The results indicate that free radical generation from the reaction of Ni(Il)-thiol complexes and molecular oxygen, and/or lipid hydroperoxides, may play an important role in the mechanism(s) of Ni(II) toxicity and carcinogenesis. INTRODUCTIONWhile nickel is a well-recognized carcinogen [l, 2]. the underlying biochemical mechanisms remain unclear (3, 4). Recent studies suggest that these mechanisms may involve oxidative DNA damage through free radicals, especially the hydroxyl (•OH) radical [5-13]. The mechanisms of nickel carcinogenicity and toxicity may also involve lipid peroxidation [14-21]. Unlike ferrous ion [Fe(II)], the Ni(II) cation itself does not directly react with 02, H2O2, or lipid hydroperoxides to generate free radicals [12, 21]. However, it has been reported that Ni(II) complexes with certain synthetic oligopeptides, e.g., tetraglycine or glycylglycylhistidine, make Ni(II) reactive with 02. This reaction results in transitory formation of Ni(III) and degradation of the organic ligand via free radical reactions [22]. Such Ni(II)-peptide complexes are also capable of reacting with H2O2 to produce oxygen free radicals [11, 12]. Although the cellular environ¬ment may not contain these particular peptide ligands that are known to render Ni(II) redox active in vitro, it does contain a variety of oligopeptides that are capable of forming Ni(II) complexes at physiological pH, and thus may facilitate Ni(II) redox activity in vivo. These oligopeptides include glutathione (y-L glutamylycysteinylglycine), carnosine (homocarnosine (y aminobutyryl-L-histidine), and anserine ( B-alany1-3-methyl-L-histidine)."

Nov 1, 1995