Search Documents

By R. J. Leary

This investigation was conducted to determine the effects of various rare-earth metal addition practices upon the macrostructure and the pattern of sulfur distribution in steel ingots. Heats of plain carbon steel were melted in a 1-ton, basic electric-arc furnace. Melts were treated with mixtures of rare-earth silicides, aluminum, and cryolite either in the furnace before tap or in the ladle after tap to determine the effects of this form of rare-earth treatment upon ingot macrostructure. Steels thus treated with rare earths in the furnace were characteristically free of the gross subsurface nonmetallics which typically result from conventional rare-earth treatments. Steel treated in the ladle showed only a few such nonmetallics, and practical techniques were developed for eliminating most of these. Results showed that furnace deoxidation was controlled by the concentration ratio of rare earths: aluminum. During casting, deoxidation was controlled by the concentration of rare earths. Oxygen contents equivalent to vacuum ladle degassing resulted from air-melt furnace treatments with the rare-earth mixtures described. Rare earths in steel inhibited the onset of equiaxed grain formation during ingot freezing, and also virtually prevented interdendritic segregation of sulfides.

Jan 1, 1968

By W. Scheetz

The Brewer Gold Mine is an open-pit, heap leach operation that processes about 122 kt/m (135,000 stpm). The mine is operated by Brewer Gold Inc., a subsidiary of Westmont Mining Inc., and is located near Jefferson, SC, about 80 km (50 miles) southeast of Charlotte, NC and 80 km (50 miles) northeast of Columbia, SC (Fig. 1). All of the ore to date has been produced from a breccia body of hydrothermal origin and a related smaller body of fault-controlled ore, known as the B-6. Reserves at the time the mine commenced production were 4.6 Mt (5.1 million st) grading 1.4 g/t (0.042 oz per st) gold. History Although some reports of a pre-Revolution War shaft at the Brewer are in the literature (Lieber, 1856, Nitze and Wilkens, 1897), gold was first produced in earnest from the Brewer Mine in 1828. Production occurred primarily from placer deposits south of the present mine workings. Lieber noted in 1856 that “every branch, gulch, ravine or even declivity of the main hill has been washed and rewashed.”

Jan 1, 1991

By Armin W. Stuedlein, Youssef Bougataya

Early stage design of driven piles primarily relies on static analysis based on one or a combination of total and effective stress approaches, the latter known as the method to estimate axial capacity. A database of 85 piles driven in the Puget Sound Lowland region and monitored at End of Driving (EOD) and Beginning of Restrike (BOR) was compiled along with capacities estimated using the CAPWAP procedure. Established soil profiles based on borings with standard penetration tests (SPT), cone penetration tests, and geologic maps were matched with their corresponding unit shaft resistance profiles from the CAPWAP procedure and resulted in more than 1,200 observations. In this study, eight new models were developed to predict the coefficients at EOD and BOR, based on the corresponding USCS categorization. Each coefficient model is formulated using a three-parameter exponential function, calibrated to capture the profile of coefficients with depth. These models could benefit the designer by providing them with a simple, empirical model that accounts for soil type and setup in a smooth, continuous function with depth. A parallel analysis was performed to assess the accuracy and variability of the formulated prediction models to facilitate implementation in load and resistance factor design (LRFD). INTRODUCTION The design of the axial capacity of driven piles during the planning stages of a project is typically based on a static analysis approach. The goals of this approach are to predict the components of capacity, consisting of the shaft and toe bearing resistances, and to assess project concept feasibility and preliminary lengths. In most cases, this analysis is based on empirically-developed methods, such as the total stress method, also known as the method (Tomlinson 1987) or the effective stress method known as the method (Esrig and Kirby 1979; Fellenius 1991). Many other methods, such as those based on in-situ test results exist and rely on correlations of blow counts from the standard penetration test (SPT), and cone tip and sleeve friction resistance from the cone penetration test (CPT), to shaft and toe pile resistances (Schmertmann 1978; Meyerhof 1976; Nottingham and Schmertmann 1975; Nordlund 1963; Eslami and Fellenius, 1997; De Ruiter and Beringen 1979). Although these methods were generally developed using data from specific geological regions, they are often recommended in national design manuals (e.g., FHWA, Hannigan et al. 2006).

Jan 1, 2018

By Gilles Rousset

This paper presents laboratory experiments conducted on hollow cylinders samples. The advantage of such a geometry is to approach in situ conditions around cylindrical openings (lined galleries, boreholes, ...). Many authors have been interested in this kind of problem, especially for borehole stability applications (for references see Guenot 1987). However, as long as we know, time-dependent behavior has not been well studied. For this purpose, we have set up two different types of tests on a deep clay : - Quick unloading test, to assess the influence of unloading rate on mechanical response and the failure modes. - Creep and relaxation test, to compute the time dependent overall deformation of the hole wall as well as to plot long term convergence-confinement pressure curve. The experimental results are then compared with those given by a theoretical model developed in our laboratory, well fitted with the tested material.

Jan 1, 1989

By A. M. Poston

Introduction of radioactive elements into ore samples and/or pregnant liquors and radiometric tracing thereof have greatly improved control of fusion and extraction studies on beryllium ores and products. Extractive metallurgical research on beryllium, normally guided by the usual laborious analytical methods, is both costly and slow. Recognition of this problem by the Bureau of Mines led to the development and application of radioisotope tracer techniques" as a substitute for chemical analysis at the Salt Lake City Metallurgy Research Center, The result was that much faster progress at significantly lower cost was achieved. This report discusses the problems encountered and resolved in using radioactive tracers and radiometric methods, defines the conditions and techniques for their effective use, and delineates the limitations and flexibility inherent in applying such methods in laboratory-scale beryllium research.

Jan 1, 1962

By Steve Stuart

Deep-sea mineral SMS deposits present some of the world’s most challenging conditions for drilling equipment. As robotic seabed drilling services mature so too the ways that clients engage with service providers to maximise their data requirements. This presentation reviews key considerations for planning and executing a successful seabeddrilling program in variable mineralised deposits. Some of the means of collaboration between robotic seabed drilling contractors and those hiring their services are explored; where improved efficiencies and recoveries over the period of a drilling programme could be achieved. Potentially new technology or methodology can be looked at to further improve these approaches.

Sep 1, 2014

By Mike Johnson, Greg Andrews, Niels Verbaan, David Dreisinger

"The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper INTRODUCTIONSearch Minerals Inc. (Search) is exploring and developing a number of deposits for rare earth element (REE) recovery in Labrador, Canada. The Port Hope Simpson District is in the southeast of Labrador and is highly prospective for heavy and light rare earth elements. The Foxtrot deposit sits within the Port Hope Simpson REE District (Figure 1), which is 70 km long by up to 10 km wide. The infrastructure available at Foxtrot is excellent; a deep-water port, air strip, and road and power infrastructure are pre-existing at St. Lewis. The three communities of Port Hope Simpson, St. Lewis and Mary’s Harbour are in close proximity to the site."

Jan 1, 2016

By Donelson A. Robertson

Literature was searched and cases of alleged water well damage were investigated. Occurrence of ground water in Appalachia is primarily in low yield, fractured, water table aquifers. Four test sites were chosen based on geographic and geologic diversity. Test wells were drilled at each site and base line data on water quality, static water level, and drawdown characteristics were obtained before surface mining commenced. Blast induced ground vibrations were measured at the surface by the wells at levels up to 5.44 inches per second maximum resultant particle velocity. Measurements made at the bottom of wells indicated that vibrations were considerably attenuated at depths of 140 to 160 feet. No direct evidence of change in water quality or well performance was produced by blast vibrations, but removal of downslope support by excavation does cause lateral stress relief which permits the water-bearing fractures to become more open. This additional storage capacity causes the static water level to drop and for well-bore permeability to improve. Static water level recovers if sufficient recharge is available and well performance is

Jan 1, 1980

By W. L. Cooley

The report provides a detailed analysis of 23 electrical accident countermeasures contemplated for use in the metal/non-metal mining industry. The costs and potential benefits of implementing groups of these countermeasures are estimated, and methods arc outlined by which the operator ran choose countermeasures in an effective manner. The analysis is based largely on an extensive electrical accident event tree which is developed in detail. For those countermeasures which are not currently technically feasible, several prototype devices were developed to help speed development. These included a trolley arc eliminator and a safer mine electricians multimeter.

Jan 1, 1982

Water and wind erosion of toxic zinc and lead smelter waste is one of the most urgent environmental problems to be solved in the Silesia region of Poland. Over 87 x 106 Mg of various mining wastes were disposed of in uncontrolled piles leading to soil, water, and air pollution in highly populated areas. Welz and Doerschel process Pb/Zn smelter wastes were stabilized in the summer of 1994 by application of heavy loads of CaCO3 (30 Mg/ha), CaO (1.5 -15 Mg/ha), and municipal biosolids (150 -300 Mg/ha), followed by seeding with a mixture of acid-and salt-tolerant grass species selected in a pot experiment. Vegetation was successfully established on 85% of the Welz material demonstration plot area (0.5 ha), even though it was initially high in water-soluble Zn, Pb, and Cd ranging from 0.4 to 1311,0.1 to 5.8, and 0.05 to 55 mg/kg, respectively. Standing biomass averaged 3.3 Mg/ha on the stabilized Welz waste zone by the end of the third growing season (1997). The revegetation of much of the Doerschel material area failed initially because of extremely high salinity (16 dS m-1), high content of water soluble metals (Cd in particular), and heavy compaction. The area was capped (15 cm) with waste lime and retreated with bio-solids (300 Mg/ha) in 1995, and standing biomass averaged 2.9 Mg/ha in the fall of 1997. The observed plant response to bio-solids and lime indicates this approach to be an environmentally beneficial technology as compared to the traditional methods utilizing topsoil covers.

Jan 1, 1999

By R. Y. Williams

In this report an attempt is made to discuss the first cost of each of several types of mine-ventilation stoppings, as well as the total annual expense of maintaining a stopping during its required period of service. Such data furnish a basis for comparison of the efficiency of the different types, and are of great importance to an engineer planning the development of a mine. The data given were obtained through an investigation conducted under a cooperative agreement between the Bureau of Mines, the Illinois State Geological Survey, and the department of mining engineering of the University of Illinois. The report itself is published by the Bureau of Mines as a contribution to the literature on safety and efficiency in coal mining.

Jan 1, 1915

By Yuhe Tang, Jun Zhang, Jianguo Liu

"The nature high carbon graphite with fine particle size has low commercial value because of its narrow application range. In order to improve its value, this paper has studied the methods for nature spherical graphite. The nature spherical graphite can be used as the battery material in the field of electronic product battery and new energy automobile battery, basis on the physicochemical characteristics and particle feature of graphite. In this research, the Fixed Carbon (FC) grade of the graphite sample is more than 95.0% and the particle size of the graphite sample is from +325 mesh to -100 mesh. There are many methods for nature spherical graphite, including the fluidized bed airflow mill, the hydro-spheroidization mill and micropowder mill. The testing results indicate that the method of ACM micropowder mill is the best because the spherical shaping ratio and production yield of spherical graphite are both the best.According to the testing results of the ACM micropowder mill, the best process includes two stages of coarse crushing, four stages of fine crushing and twelve stages of shaping. And two kinds of spherical graphite products can be got, which are the product of D50=22.85 µm and the product of D50=15.43µm, and the whole yield of them is up to 54.43%. So, it lays a foundation for the high value utilization of this kind of graphite resources.INTRODUCTION Graphite is isomer of the diamond. Graphite ore resources are mainly concentrated in China, Brazil, India, followed by Czech, Korea, Mexico, Canada and other countries. Graphite ore has lots of characteristics by itself crystal structure, such as good resistance to high temperature, electrical conductivity, thermal conductivity, thermal shock resistance, good lubricity, plasticity, chemical stability and so on. So, Graphite is widely used in metallurgy, machinery, electrical, chemical, petroleum, nuclear industry, defense industry and other areas. [1,2,3] Natural graphite ore has low geological Fixed Carbon (FC) grade. FC grade should be enriched to more than 94.0% by mineral processing. [1,2] The particle size composition of this high carbon graphite affects its application value. The part of +100 mesh particle size has high application value. The part of -100 mesh particle size has low value because of its limited application field. In order to improve the value of-100 mesh particle size, this part high carbon graphite can be made into spherical graphite. And the value of the spherical graphite is great, it is more than 8 times of the feed. This paper has lots of tests for spherical graphite preparing with the fine particle size natural high carbon graphite. And it lays a foundation for the high value of this kind of resource."

Jan 1, 2018

By A Rozendaal

Namakwa Sands, a heavy minerals beneficiation business situated along the west coast of South Africa, is a major producer of titanium slag, pig iron, ceramics quality zircon and rutile concentrate to the international export market. The bulk of the economic mineralisation, which includes zircon, rutile, ilmenite and leucoxene is hosted by a late Cainozoic aeolian succession overlying remnant palaeo-strandline sediments. Relatively younger duricrust layers that cement a significant part of the generally unconsolidated ore compounds the challenging processing character of the primary mineralogy. The complex nature and hardness of the duricrust ore influence their mineability negatively, and can potentially destabilise downstream ore preparation processes. Effectively, up to ten per cent of the entire mineral resource is sterilised as the present infrastructure is not geared to treat the hard-mineralised ore. The metallurgical performance of the primary processing stage, which entails wet density separation, is strongly a function of the quality of the heavy mineral assemblage, liberation state of the economic minerals and slimes content. Elevated concentrations of garnet, a gangue contaminant exhibiting similar physical characteristics as the economic minerals, subtract substantially from the recovery performance of the secondary concentration process, which comprises mainly wet magnetic separation. By contrast, the intrinsic mineral purity of the economic fraction governs its successful recovery to saleable products as stringent product quality specifications apply. Improved mine planning through geometallurgical enhancement of the existing mineral resource model is envisaged to benefit the entire Namakwa SandsÆ mineral beneficiation chain, ultimately aiming to optimise mineral resource utilisation.

Jan 1, 2008

By Paul D. Tomlingson

Editor's note: This is the first of two articles on maintenance. Part two, "Effective maintenance downsizing techniques," will appear in the October issue of MINING ENGINEERING. Most mine managers are aware that the cost of maintenance rarely goes down unless work is done less often and with fewer people. Fewer people translates into downsizing and seldom means making maintenance more efficient. Even so, mines that have struggled unsuccessfully to improve maintenance and are now pressed to reduce maintenance costs may opt for downsizing. On the other hand, mines with an immediate need to reduce costs may be forced to downsize because they cannot wait for needed improvements to take effect. This can be bad news for maintenance. In any case, the mine must downsize correctly to ensure effective maintenance is sustained.

Jan 1, 1994

By Lloyd A. Morley

Proposed advantages and disadvantages of low-voltage shielded trailing cables are formulated utilizing the literature and industry sources. A partial analysis of these proposed advantages and disadvantages is completed through a review of the literature. Cable costs are assembled from mine operators, cable and splice manufacturers, and actual cable purchases. To confirm each advantage and disadvantage, an underground test site is established, and testing is performed here and in the laboratory. All testing procedures are completely described. The results of this investigation are reported and used to formulate recommendations attendant to low-voltage shielded cables. Suggestions for installation, handling, and maintenance are presented.

Jan 1, 1977

By Maurício Gammertt Röhnelt

A pesquisa em questão trata-se do aproveitamento e aplicação da escória de aciaria elétrica, um subproduto residual do processo de refino do aço. A força propulsora para realização deste projeto está associada à utilização do resíduo: a quantidade gerada é maior que a quantidade aproveitada, uma vez que este subproduto tem como limitante de uso o fenômeno de expansão volumétrica que compromete obras de engenharia. No presente estudo, a escória foi micronizada, caracterizada e incorporada em uma matriz polimérica para obtenção de um novo produto com propriedades vedantes. Os artefatos produzidos foram submetidos a vários ensaios mecânicos, químicos e de caracterização conforme requisitado pela norma NBR 15750. Após a análise dos resultados, concluiuse que os compostos constituídos pelo resíduo apresentaram melhores propriedades vedantes que o grupo controle de referência. Além disso, verificaram-se melhores condições de processamento nos compostos com escória de aciaria micronizada. Obteve-se, portanto, um produto ecológico, mais viável economicamente, com propriedades que atendem a uma especificação. Dessa forma, difundiu-se a aplicação do resíduo para outros ramos industriais, agregando a este maior valor comercial, promovendo assim a sustentabilidade por meio da substituição de matérias-primas provenientes de recursos não renováveis pela escória de aciaria elétrica.

Aug 17, 2017

By R. H. Church

As part of the research effort of investigating the effects of microwave energy upon the chemical and physical properties of different minerals and ores, the Bureau of Mines has conducted basic research into identifying those properties of minerals that are affected by microwave energy, namely, the dielectric constant and loss tangent. These properties were determined utilizing the theory of microwave propagation in a coaxial waveguide filled with a dielectric material and measuring the input impedance with an RF impedance analyzer that operates from 1 MHz to 1 GHz. By knowing the microwave frequency and filling the waveguide with a powdered mineral, the dielectric properties of the mineral sample were determined. From these dielectric properties, theoretical microwave heating characteristics of each mineral could be calculated. These same mineral samples were then irradiated by a 915 MHz 30 kW variable power microwave oven and dielectric heating studies were performed. A comparison of the theoretical heating characteristics and the results from actual dielectric heating studies was conducted to evaluate the dielectric property measurements on each mineral. This report presents the results of the Bureau's research in identifying the dielectric properties of low-loss minerals according to the mineralogical classification scheme along with their irradiation studies. Though far from complete, this study represents some of the more frequently encountered low-loss minerals.

Jan 1, 1988

By S. R. Zimmerley, C. H. Schack

"INTRODUCTION The pilot-mill concentrator at Boulder City, which has a nominal capacity of 40 tons per day, was planned and built to investigate further the beneficiation of domestic manganese ores that have been concentrated successfully in the ore-dressing laboratory. As milling of manganese ores in general is a new field, it is necessary to prove the success of laboratory processes by means of large-scale operations employing standard milling equipment, and thus to obtain engineering and metallurgical data essential to designing and operation of full-scale concentrating mills.The first ore tested in the pilot plant was the Three Kids Annex manganese ore from the Las Vegas Wash area 15 miles southeast of Las Vegas, Nev. The deposit was worked for its high-grade ores during the First World War From 1930 to 1939, 4,500 feet of diamond drilling was completed by a private company. Diamond drilling started by the Bureau of Mines in November 1940 and completed in July 1941 aggregated 6,600 feet. Exploration by the private company and the Bureau outlined reserves of about 1,000,000 tons of ore assaying plus 28 percent manganese. A much larger tonnage of lower-grade ore also was outlined by the drilling.Because of its physical nature, the Three Kids Annex ore had long proved unamenable to concentration by ore-dressing methods. The ore is a mixture of manganese oxides (wad) filling the pores and to some extent replacing a silt composed of very fine grains of volcanic tuff, quartz, feldspars, other silicates, and clay. Some gypsum occurs as fillings along fracture planes. The ore is light and very porous. Upon wetting, it disintegrates into granular but friable particles and a large amount of slime. It is these characteristics that make the ore so difficult to concentrate."

Sep 1, 1947

By David C. Girard, Larry Williamson, Leonard R. Benson, Ronald E. Bizzarri

On the east side of Washington DC, the DC Water & Sewer Authority is developing a Facility Plan for the Anacostia River CSO Control Projects, including 8 to 12 miles of CSO storage/conveyance and flood relief tunnels and associated facilities. The project includes major technical and non-technical challenges, including: completion under a Federal Consent Decree schedule; large diameter (estimated 25 to 35 ft) soft ground tunnels and shafts up to 200 ft depth; operations without use of active flow control systems; and close coordination with several major public and private construction and development projects that are being advanced in the project area.

Jan 1, 2007

By Gary J. Massoth

Wherever hydrothermal fluids vent from the seafloor they will buoyantly rise (up to 100?s of meters) while mixing with seawater before attaining density equilibrium and dispersing laterally as neutrally buoyant plumes commonly 50 to several 100?s of meters in thickness and with order-of-magnitude or greater breadth. Although these plumes are typically >10,000-fold dilutions of vent fluids they can be reliably detected using sophisticated physical sensing and chemical techniques. Hence, hydrothermal plumes are spatially large targets compared to the actual sites of seafloor fluid discharge and resulting mineralization. For this reason plume prospecting techniques evolved over the past 20+ years have been widely used to systematically explore over 10% of the 60,000-km-long system of mid-ocean ridge (MOR) spreading centers for hydrothermal activity. While plume detection and gradient mapping can be used to home in on venting sites, plume chemical signatures provide additional insight regarding the nature of the fluids being discharged on the seafloor. We have applied the systematic plume prospecting techniques developed on MORs to the volcanic frontal arc setting as part of the NZAPLUME (New Zealand American PLUme Mapping Expedition) surveys. NZAPLUME I in March 1999 marked the first systematic reconnaissance of any intra-oceanic arc for submarine hydrothermal activity. Seven of thirteen previously mapped volcanoes that comprise a 260-km-long section of the southern Kermadec arc northeast of New Zealand were confirmed to be hydrothermally active. On average, one hydrothermally active volcano was found along each 35 km of arc front, a rate comparable to slow- and intermediate-rate spreading MORs. During NZAPLUME II in May 2002, thirteen previously unknown volcanoes and 8 satellite cones were first swath mapped for bathymetric detail and then surveyed using plume prospecting techniques. Three active venting sites were discovered along this 580 km-long arc section, bringing the total to 10, or 39% of 26 volcanoes surveyed overall, still an appreciable frequency rate for venting sites compared to MORs. While only chemical results for NZAPLUME I are available, the arc plumes characterized so far are chemically diverse and rich compared to MOR plumes. This diversity and enrichment was most evident as ultra-high concentrations of CO2, sulfur gases (St = SO2 + H2S), and Fe within plumes over several volcanoes. We suggest the fluids discharging from the seafloor at these sites are volcanic fluids, i.e., hybrid fluids comprised of MOR-like hydrothermal fluids evolved from seawater-rock reaction and fluids exsolved from magma as acid volatiles and liquid brines.

Jan 1, 2002