Search Documents

By William Bergeson

"BACKGROUND As of December 2015, there are roughly 475 road tunnels within the United States according to the most recent national tunnel inventory data compiled by the Federal Highway Administration (FHWA); whereas, there are more than 615,000 highway bridges on public roads. The FHWA estimates that tunnels represent nearly 100 miles of Interstates, State routes, and local routes. Tunnels are part of the national transportation infrastructure and represent a significant financial investment for the owner and, hence, the tax payers. Tunnels, that are not properly maintained, usually require more extensive repairs and consume more resources. Tunnels must provide safe, reliable, and effective transportation even as these structures age and deteriorate. Furthermore, tunnels generally remain in service for extended periods of time due to their very high construction costs. For example, many tunnels were constructed decades ago during two historic periods of highway system expansion; the first period correlated with the era of public works programs linked to the Great Depression of the 1930-40s; and the second period of expansion occurred with the building of the interstate highway system in the 1950-60s. As such, these tunnels are fast approaching 60 to 80 years old. Congress enacted the Moving Ahead for Progress in the 21st Century Act (MAP-21), which was signed by the President on July 6, 2012. This legislation followed a fatal tunnel incident on July 10, 2006 and a National Transportation Safety Board (NTSB) report1 that noted the importance of conducting regular tunnel inspections. MAP-21 authorized the Federal Highway Administration (FHWA) to develop a mandatory inspection program for all tunnels on all public roadways (Bergeson and Ernst 2015): To help safeguard tunnel users and to ensure reliable levels of service, the FHWA developed the National Tunnel Inspection Program (NTIP), which is comprised of the National Tunnel Inspection Standards (NTIS), the Tunnel Operations Maintenance Inspection and Evaluation (TOMIE) Manual, the Specifications for National Tunnel Inventory (SNTI), and the Manual for Bridge Evaluation (MBE). The data collected from the program will be stored in a National Tunnel Inventory (NTI) database. A comprehensive and refresher training program was also developed to help qualify and certify key tunnel inspection personnel to include the program manager and team leader."

Jan 1, 2016

By Mishark Nnabuchi

A heterojunction of PbS - CuS thin film has been grown on glass slides by SGT. The films were annealed for 1hr at temperature of 373K and 423K respectively. The optical properties were characterized using a UNICO UV - 2102 PC Spectrophotometer at normal incidence of light in the wavelength range of 200 - 1000nm. The minimum percentage transmittance was observed to be 34% for sample A and 25% for sample B within the same optical region. The band gap energy was determined from the spectra to be 2.05eV for sample A and 1.85eV for sample B which gave a band shift of 0.20eV. It can thus be concluded that the optical properties of the films within the VIS - UV - NIR can find application in solar thermal technology, particularly as antireflection coating, window materials and as good materials for selective solar cell fabrication.

Jan 1, 2010

By R. R. Lowery

The Bureau of Mines developed hypereutectic aluminum-silicon alloys which 11.7.d better mechanical properties than the unmodified hypereutectic alloy. A commercial aluminum-20 weight-percent silicon LIr alloy was selected as a ary base for improvement. The primary silicon. grains were reduced from ASTM 4-5 to ASTM 8.5 by the use of phosphorus and phosphorus compounds. The remaining eutectic matrix was refined by sodium metal additions of 0.2 weight-percent. Solid solution strengthening of the alpha aluminum was obtained by adding 2 percent copper and 0.5 percent magnesium. Also, 1 percent nickel was added to harden the alloy. Optimum thermal treatment consisted of a solution treatment for 10 hour:, at 480° C with hot water quench, followed by aging for 6 hours at 175° C. The final alloy exhibited a Rockwell B hardness of 75 ±2 in the heat-treated condition. The ultimate tensile strength was 39,5O0 psi with no recordable elongation. The coefficient of linear thermal expansion was 20.4 x 10-6 per °C in the temperature range 20° to 300° C. No wear resistance data were collected.

Jan 1, 1966

The phosphorus content of the banded iron formation (BIF) and of the associated iron ore deposits in the north west of Western Australia is known to vary widely, a fact which has considerable econ~mic significance. Trendall and Blockley (1970) have described the variety of textural appearances of apatite in the Hamersley Group BlF, and suggest that apatite may account for the entire phosphorus content of the unaltered BIF.A preliminary investigation using an M.A.C. electron microprobe analyser has shown that, at least in some iron ores and in partially enriched BIF and associated shales, the phosphorus occurrence is more complicated than this. A suite of samples was examined from one location which covered the entire Dales Gorge Member and some adjoining macrobands in the Mt. McRae shale, together with samples selected for their high phosphorus content, degree of ore enrichment, and position relative to the enrichment zone. Calcium apatite was not observed in any sample of ore from this sequence, despite its ubiquitous occurrence in the BIF. Silicate mineralogy in the enriched regions also differs from that in the BIF, but this change has not yet been studied in detail.The phosphorus content of goethite in one orebody is often high and appears to be in solid solution in the goethite structure. It shows little or no variability on a micro-scale within a grain, except where theremay be a zoned enrichment near boundaries and solution channels. There is also a limited solubility of phosphorus in hematite (the maximum observed by the author is 0·1 per cent P); but where the hematite is martitic (after magnetite) its phosphorus content is always low or zero. In some bands, martitic hematite has been hydrated to goethite, and this also has a very low phosphorus content. Phosphorus was not found in the silica or silicates in the ore, and even when iron enrichment is just beginning, a limited suite of samples from the BIF suggests that the phosphorus content of the chert microbands is almost entirely in the microscopic goethite nuclei (after riebeckite) scattered throughout the chert. The ability of goethite and hematite to accept phosphorus...

Jan 1, 1973

By Donald H. McLaughlin

ALTHOUGH Cerro de Pasco was well known since the early sixteen hundreds as one of the major silver districts of the Andes, its development on a modern scale did not occur until the first decade of the present century when a syndicate organized by James B. Haggin initiated the enterprise that eventually grew into the complex and widespread operations of the Cerro de Pasco Copper Corporation. Options on a few claims in Cerro de Pasco that had been brought to New York in 1900 came to the attention of A. W. McCune, a mining man from Salt Lake City, who took them to Haggin and soon succeeded in interesting that creative mining financier in the possibilities of the district. James MacFarlane, an engineer well known to both Haggin and McCune, was sent to Peru early in 1901 to make the initial examinations which promptly led to acquisition of a substantial group of claims in the heart of the mineralized area. A syndicate to which Haggin turned over his rights was organized on Feb. 26, 1902 to provide the necessary funds. The original members were J. B. Haggin, who retained a 34 per cent interest, Edward H. Clark (for Mrs. Phoebe Hearst, the widow of Haggin's old associate, George Hearst), H. McK. Twombly, H. C. Frick, D. O. Mills, and J.P. Morgan.

Jan 1, 1945

By David Heyl

"El presente texto señala la evolución de los modelos genéticos de geología económica del yacimiento minero Tres Cruces. Dicho yacimiento se encuentra localizado en el noreste del Perú, adyacente al distrito minero de Quiruvilca. A partir del año 1995 se le reconoció como el mayor productor de oro a través de un programa de exploración en la Formación volcánica Calipuy. Posteriormente, el yacimiento fue visitado por variosgeólogos que postularon diferentes modelos genéticos del yacimiento para así estimar su potencial económico -en tanto se incrementaron los datos geológicos del yacimiento. Por ello, el texto presenta el modelo genético de Tres Cruces, como el más adecuado, aunque la evaluación de su potencial econornica está aún en progreso."

Apr 26, 1999

By G. J. Heferen, A. Pranowo, N. J. Aslin, P. O. Eriksson

Glencore Technology (GT) has over four decades experience supplying stainless steel cathode plates (“cathode plates”) to the electro-refining and electro-winning industry. Cathode plates are typically the single biggest capital investment in a refinery. Refineries may view cathode plates as fixed asset or consumables depending on their operational characteristics. This paper examines the issue of cathode plate life and the strategies and philosophies used by different plants in the management of their cathode plate asset. Some plants operate with their original plates after more than 20 years. Others accept high turnover and regular maintenance as normal operating practice. Reference data are provided on plate life for various operating plants including benchmark plants achieving best-practice plate life and operating cost. The role of the electrode handling equipment on cathode plate longevity is also examined, including latest developments in Cathode Stripping Machine, robotic copper stripping, and full-automation production cranes. The ability to identify and manage the population of plates in service is also critical for maximising plate life and minimising its overall operating cost. This paper discusses a novel and unique RFID system for tracking and managing cathode plate inventory. INTRODUCTION Permanent cathode plates The adoption of permanent stainless steel cathode electrodes in the electro-refining of copper was the most significant process development since the first commercial electro-refineries were built in the late 19th century. It provided significant improvement over the labour intensive and complicated starter sheet system. Copper grows over the permanent cathode blade for a number of days before being stripped, and the permanent cathode can be returned straight back to cells for the next cathode cycle. Glencore Technology (formerly Mount Isa Mines (MIM), then Xstrata Technology) has been manufacturing permanent stainless steel cathode plates from the late 1970s with the birth of ISA PROCESS™, and the Kidd process that came one decade later. Invented and commercialised by Mount Isa Mines, the ISA PROCESS™ was first implemented into Copper Refineries Limited (CRL), Townsville, in 1978. The KIDD PROCESS by Falconbridge evolved in the 1980s and was first implemented into the Kidd Creek Tankhouse, both operations converting from traditional copper starter sheets.

Jan 1, 2019

By M. M. Poulton

Universities are not immune from the large number of retirements facing the mining industry. Department heads anticipate that we will need to replace all of the senior mining engineering faculty in the U.S. by 2020. Long term studies of Ph.D. completion times and success rates indicate that in Engineering disciplines in the U.S., the ten year completion rate is 65% at best and the four year completion rate is less than 8%. We do not have accurate data on completion rates and times for mining or metallurgical engineering Ph.D. students in the U.S. but students self-report their expected completion times are around 4 years. National data on doctoral students indicate that younger, full time students with sufficient financial support have a higher probability of success in completing their degrees in a timely manner. Students in Eastern U.S. mining engineering programs are on average 32 years old, 85% are full time, and the gap between support and cost of attendance is $5,000 per year. Students in Western U.S. programs are on average 38 years old, 78% are full time, and the financial gap is $8,483. Further, it appears that domestic graduate students are not very geographically mobile. The current demand for new faculty is higher in Western programs but the longer term retirements are higher in Eastern programs. While all Ph.D. students who responded to the 2010 survey indicated an interest in a faculty position at some point in their careers, very few were applying for the open positions. Over the past 35 years for which data could be obtained, the maximum number of Ph.D. students enrolled in mining engineering in the U.S. is 115 with a maximum of 27 degrees granted in one year. On average 89 students are enrolled in doctoral programs in mining engineering in the U.S. with average degree production of 15 Ph.D.s per year.

Jan 1, 2012

By Peter Cain

In response to the appearance of excessive convergence of bolted gateroads in the front abutment zone of retreating coal faces at Phalen Colliery, staff from the CANMET Cape Breton Coal Research Laboratory in Sydney, N.S. initiated a programme of roof profile measurements in the front abutment zone of longwall headgates. The results of these measurements allowed a characteristic deformation curve to be determined for each headgate, and the early identification of areas showing an unstable deformation trend. These areas were then reinforced with supplementary support. The monitoring programme was adopted and enlarged by the rock mechanics staff of the Cape Breton Development Corporation, and has been continuing for a period of approximately two years. A sufficient quantity of data now exists to be able to make an assessment of the effects of a number of mining parameters on the performance of the gateroad in the front abutment zone. The following paper describes the method of measurement, illustrated by typical results, and goes on to relate variations in rate and patterns of movement to geology, interaction, method of support and pre-mining stresses.

Jan 1, 1996

By Martin Herrenknecht, Karin Bäppler

The last five years have seen a remarkable increase in tunnelling projects in both soft ground and hard rock applications. Part of the increase is a result of recent Research & Development efforts to improve Tunnel Boring Machine (TBM) adaptability, capability and reliability. This paper will review the latest innovations in the TBM industry and explain in detail the results of these innovations followed by a forecast where the technology will take the tunnelling industry in the future.

Jan 1, 2005

These may be of interest to members examining the collection of ores, etc., from Mount Lyell, which is a feature of the Victorian Gold Jubilee Exhibition, and may have some value as geological records. No. 7 and No 8 are analyses of samples of footwall rock from the Lyell Tharsis mine. No. 7 is hard, crystalline, fine-grained, and of homogenous structure. It has a dark-red colour, due to ferric oxide (Fig 1); and was taken from a place eight feet east of the ore body and about half way between the 50 feet and 100 feet levels. No. 8 is from the same excavation and from four feet east of the ore body it is softer than No. 7, being easily scratched with a knife-blade, of a deeper dark-red colour, and has a slaty cleavage.

Jan 1, 1902

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 Larissa Koroznikova, Steve Durkin, Patrick Bouwmeester, Michael Tuck

In currently used mining methods, blasting techniques often causes dilution of valuable ore and results in costly processing requirements. In the context of narrow vein mining of thin and highly concentrated orebodies there is a need of a mining method that can reduce dilution in order to remain economically viable. This research project explored the viability of a new mining technology, thermal fragmentation, in narrow vein mining. Thermal fragmentation technology uses a flame jet to produce extreme heat that spalls the surrounding rock to a strategically located drill hole, as an alternative to traditional blasting. This paper creates a net present value (NPV) model of a mining method using thermal fragmentation, as well as for an existing method used for narrow vein mining; comparisons and evaluations were made regarding the feasibility of the new technology. It was found that while overall costs for thermal fragmentation were relatively high, reductions in wages, haulage and processing costs, as well as increased productivity and ore recovery, meant that the new method would improve the financial performance of any operation. These results identify that there is an opportunity to introduce the thermal fragmentation technology to narrow vein mines within Australia, in order to lower costs and increase profit.

By Marcelo Moreira Furst Gonçalves

A qualidade superficial dos produtos lingotados continuamente está ligada diretamente aos estágios iniciais de solidificação do aço no molde. Nessa etapa do processo, os parâmetros e estratégias de oscilação são decisivos para a obtenção de produtos com qualidade superficial adequada. Assim, foi desenvolvido na Usiminas um sistema computadorizado para monitoramento dos parâmetros de oscilação do molde, de modo a fornecer subsídios para um melhor entendimento do processo. Este sistema monitora, em tempo real, o eixo vertical e as oscilações nos eixos horizontal e transversal, mesmo com baixas amplitudes. O sistema desenvolvido possibilita a obtenção dos dados com alta precisão, de forma totalmente automática e a realização de pós-tratamento de forma a se obterem valores relativos ao processo de lingotamento e funcionamento do molde.

Jul 30, 2018

By Congling Shi, Marek Borowski, Yue Wang, Jianwei Cheng, Xixi Zhang, Xuan Xu

As the first barrier to prevent accidents caused by explosions in underground coal mines, the integrity and stability of mine seals have great effects on mine workers’ lives and underground production safety. In this paper, the mechanical responding performance of typical mine seals under the impact load are studied by using numerical simulation method. By such simulation studies, the safety of different seals subjected to the explosion load is evaluated. Seals’stability are also investigated under effects caused by various influence factors including thickness of mine seal, cutting depth into surrounding rocks, rock type, and the roof-tofloor convergence under given the explosion load. The research results can provide theoretical basis and reasonable improvements for mine seal’s construction practices for improving its anti-explosion performance.

By Congling Shi, Marek Borowski, Yue Wang, Jianwei Cheng, Xixi Zhang, Xuan Xu

As the first barrier to prevent accidents caused by explosions in underground coal mines, the integrity and stability of mine seals have great effects on mine workers’ lives and underground production safety. In this paper, the mechanical responding performance of typical mine seals under the impact load are studied by using numerical simulation method. By such simulation studies, the safety of different seals subjected to the explosion load is evaluated. Seals’stability are also investigated under effects caused by various influence factors including thickness of mine seal, cutting depth into surrounding rocks, rock type, and the roof-tofloor convergence under given the explosion load. The research results can provide theoretical basis and reasonable improvements for mine seal’s construction practices for improving its anti-explosion performance.

By William F. Daly, William H. Hansmire

Installation of initial tunnel support is often the most uncertain element of work in the design of, and a contractor bidding on, construction of a rock tunnel. The risks the construction contractor and owner assume are delineated to a great extent in the technical specifications portion of the contract documents. It is intended that this paper identify current practices for specifying initial tunnel support and the impacts each case has on the assignment of risks associated with providing the initial tunnel support. Examples of recently completed tunnel designs are given.

Jan 1, 1985

A quantitative chemical model of the rocks of the Broken Hill lode environment is presented to illustrate a stratiform orebody in a meaningful form to scientists interested in environmental control on the chemicalcomposition of sediments.Even though this study was restricted by the narrow range of rock analyses available it is obvious that significant chemical differences exist between the various rock units and also that some association of metallic sulphides with Ca, Mn, Fe, and P is indicated.Correlation of this evidence with that from other mining fields may point out more definite chemical relationships and elucidate the puzzle of the mode of formation of many stratiform orebodies.

Jan 1, 1968

By Eduardo de Oliveira Cabral

O trabalho apresenta uma comparação entre os principais tipos de processo de aglomeração mecânica de pós e lamas, com foco nas tecnologias de tambor e prato rotativo, misturador horizontal e misturador intensivo vertical, destacando as vantagens e desvantagens de cada processo de acordo com o objetivo final.

Oct 30, 2017

By T. J. Rohrbacher

This report presents a U.S. Bureau of Mines methodology developed to incorporate factors of coal production (mining and cleaning methods, recoveries, economics, etc.) into the definition of recover-ability of a coal resource. Project procedures and computer models that were developed to include mine and preparation plant production rates, recoveries, and costs are explained. The results of these procedures and models are reviewed and compared to the Energy Information Administration estimate of U.S. coal resources-the "demonstrated reserve base." The Matewan 7-1/2-minute quadrangle in eastern Kentucky was selected to demonstrate the methodology.

Jan 1, 1993