Search Documents

By M. F. Ameur, M. Habak, H. Aouici, M. Kenane

Present study interest by aluminium alloy (Al 7175-T5173) drilled without cooling fluid. The influence of the machining parameters (spindle speed and feed rate) on the holes quality was analyzed. Drilling tools are made of carbide (WC); high speed steel (HSS) and TiN coated carbide (WC-Ti).The Experiment design was reinforced by the application of statistical analysis of variance (ANOVA).The results show that the thrust force is influenced principally by the spindle speed and feed rate. Though, both feed rate and tool materials have statistical significance on the surface roughness. In addition, the objective of correlations between spindle speed and feed rate with the evolution of the machining parameters was established. These correlations were obtained by quadratic regression using the response surface methodology. Finally, useful to select optimum values of drilling parameters, that would minimize thrust force, torque, cutting temperature and surface roughness.

Jan 1, 2015

By Daniel W. Su

This paper presents the results of a detailed geotechnical study on the potential multiple seam interaction between the No. 2 Gas (upper) and the Powellton seams, which are separated by an average interburden of 45 ft. The interburden consists of 4 ft of clay shale below the No. 2 Gas seam, 38 ft of massive sandstone, and 3 ft of shale above the Powellton seam. The No. 2 Gas seam was mined about 60 years ago, and many water-pooled areas were projected to be present. The deepest overburden over the No. 2 Gas seam is about 750 ft. To evaluate the potential interaction between the two mine works and to determine the pillar safety factor, Analysis of Multiple Seam Stability (AMSS) software was initially used to determine pillar dimensions to obtain a minimum safety factor of 2.0 for areas under pooled water, as well as a minimum safety factor of 1.5 for areas not under pooled water. Furthermore, to assess the quality of the interburden rock strata, two surface core holes were drilled, and rock cores were tested in the laboratory for their strength and elastic moduli. Using the experimentally determined strengths and moduli as part of the input parameters, the RocScience Phase2 finite element program was employed to model the stress field scenarios and estimate the safety factors of the interburden rock strata before and after Powellton seam mining. The pillar safety factors derived from the Phase2 analysis were in excellent agreement with those obtained from the AMSS analysis. Phase2 results also predicted that the effect of the Powellton seam mining, first mining only, would reach a maximum of 19 ft above the Powellton seam, which led to the proposal of drilling 25-ft deep test holes to detect water, instead of the 45-ft deep test holes mandated by MSHA. The proposed test-hole height was accepted by both Mine Safety and Health Administration (MSHA) District 4 and the state of West Virginia. Mining of the Powellton coal seam commenced in February 2011 and continued for eight months. To date, no 25-ft deep hole has encountered water under the water-pooled zone, which validates the RocScience Phase2 finite element analysis. Also, inmine observation of excellent pillar stability and roof condition confirms the validity of the AMSS analysis.

Jan 1, 2012

By L. Y. Sadler

The Bureau of Mines conducted a study Lo determine the loss in weight of silica (Si02) volatilization from low-alumina (A1203) refractories used as hot face liner materials in such process equipment as coal gasifiers, synthesis gas transfer lines, and ammonia plant secondary re-formers. Small specimens of 80-and 40-pct-A1203 brick and 95-pct-SiO2 brick were exposed to steam in high-pressure furnaces at pressures of up to 1,000 psig and temperatures up to 1,400° C for periods ranging up to 120 h. Weight losses from the 40-pct-A1203 brick after 40 h of exposure were highest, 2.75 pet at 1,400° C and 1,000 psig. The rate of weight loss had dropped to near zero after 80 h of exposure at all temperatures. No relationship between total silica content of the specimen and weight loss could be established nor did scanning electron microscopic examination of the specimens before and after exposure identify specific regions (e.g., surface) suffering a disproportionate share of the silica loss. It was concluded that minor silica volatilization is likely to occur, if at all, at temperatures of less than 1,000° C and pressures below 1,000 psig, and that low-alumina refractories should be used as dry-ash coal gasifier hot face linings.

Jan 1, 1986

By Richard F. Flanagan, Robert H. Marshall

The Republic of Singapore’s Public Utilities Board is implementing the Deep Tunnel Sewerage System Project. The project’s deep tunnel component, 48 km of deep, large diameter sewer tunnels has been successfully completed (the works are in the defects liability period). Six International Design/Build tunnel contracts utilized eight Earth Pressure Balance TBMs ranging up to 7.23 m in diameter to deal with varied ground types ranging from deep soft clays to fresh granite. Numerous access/workshafts were constructed and using various support systems. This paper provides an assessment/overview of the tunnel contracts, tunnel excavation methods and equipment, and the shaft systems. Suggested enhancements to similar future projects are provided.

Jan 1, 2007

By Nav Dhadli

Tailings from Oil Sands MiningWhat are they? Challenges Solutions Regulatory Environment Definition of the AFD Tailings Treatment Process 2010 AFD Pilot/Demonstration ProgramTechnical challenges Performance and Results Next steps Oil Sands Industry Collaboration on Tailings Technology TAILINGS ?WHAT ARE THEY? Mixture of remaining water and solids following bitumen extraction process Composed of water, sand, silt, clay, small amounts of hydrocarbon (bitumen, solvent, and asphaltenes) A necessary part of production in excavation of oil sands and removal of bitumen

May 1, 2011

By Joe Wickline, Mark A. Van Dyke, Wen H. Su

"Geological factors and mine design contribute to mining-induced seismic activity, and this is especially true in longwall mining. Massive rock units are a key cause of seismic activity due to catastrophic failures that release large amounts of energy. Other factors, such as overburden depth, panel design, pillar design, rock strength, and proximity of the massive rock unit to the coal seam, all have a role in the potential and size of a seismic event. A recent seismic event was recorded by a deep longwall mine in Virginia at 3.7ML on the local magnitude scale and 3.4 MMS by the United States Geological Survey (USGS) in July 2016, which had no impact on the mining operations. Further investigations by NIOSH and Coronado Coal researchers have shown that this event was associated with geological features that have also been associated with other, similar seismic events in Virginia. Detailed mapping and geological exploration in the mining area has made it possible to forecast possible locations for future seismic activity. In order to use the geology as a forecaster of mining-induced seismic events and the energy potential, two primary components are needed. The first component is a long history of recorded seismic events with accurately plotted locations. The second component is a high density of geologic data within the mining area. In this case, 181 events of 1.0ML or greater were recorded by the mine’s seismic network between January, 2009, and October, 2016. Within the mining area, 897 geophysical logs were analyzed from gas wells, 224 core holes were drilled and logged, and 1,031 fiberscope holes were examined by mine geologists. From this information, it was found that overburden thickness, sandstone thickness, and sandstone quality contributed greatly to seismic locations. After analyzing the data, a pattern became apparent indicating that the majority of seismic events occurred under specific conditions. Three maps were created using MineScape geological mapping software. MineScape deploys an interpolator known as FEM (finite element method) and is based on a series of gridded triangles to forecast the probability and magnitude of an event if a particular panel were to be mined. The forecast maps have shown accuracy of within 74%–89% when compared to the recorded 181 events that were 1.0 ML or greater when considering three major geological criteria of overburden thickness of 1900 feet or greater, 20 to 40 feet of sandstone within 50 feet of the Pocahontas number 3 seam, and a longwall caving height of 15 feet or less."

Jan 1, 2017

By Lawrence Devon Smith

"What is Due Diligence?Within the mining industry the term “due diligence” is used to describe a detailed data review, generally in connection with the purchase or sale of a mineral property, the approval of a large capital expenditure, or the borrowing of a large sum of money.The term originates in the requirement of the board of directors of a corporation to “act honestly and in good faith ... and exercise the care, diligence, and skill that a reasonably prudent person would exercise in comparable circumstances” (OBCA, 1994). Furthermore, the law assumes that a corporation (or its board) will have exercised due diligence in the acquisition of an asset and, therefore, knowingly (in the absence of fraud or deceit) will have taken on the liabilities and obligations associated with the asset (Nelson, 1994). This is the familiar “Buyer Beware”.Directors are liable for their decisions except “if the director relies in good faith upon financial statements of the corporation represented … by an officer of the corporation or in a written report of the auditor, or a report of a lawyer, accountant, engineer, appraiser, or other person whose profession lends credibility to a statement made by any such person.” (OBCA, 1994).Hence the importance of reports prepared by professionals. They provide confirmation that the directors have exercised due diligence in the performance of their duties. For this reason these reports are referred to as due diligence studies"

Jan 1, 1997

By W B. Edgar, S C. Dominy

High-nugget effect vein-gold systems are generally considered to be one of the most challenging of deposit types to evaluate and exploit. To potential investors and mining companies, they are viewed as high risk because of the associated uncertainties in the grade estimate and general paucity of Ore Reserves at production start-up. However, despite the well-known risks, these deposits often have a grade upside that makes them potentially attractive. The reporting of resource grade is of importance and perhaps even more so is the reporting of the associated uncertainty attached to the grade estimate. The use of the grade estimate supported by a grade range is recommended to achieve more complete and useful disclosure. The definition of the grade range can be somewhat subjective, ranging from opinion based estimates through to data-based estimates and geostatistical conditional simulation. Whichever method used, the over-riding issue must be the provision of enough data of appropriate quality and full disclosure to the public of relevant uncertainties.CITATION:Dominy, S C and Edgar, W B, 2012. Approaches to reporting grade uncertainty in high-nugget gold vein projects, in Proceedings Project Evaluation 2012 , pp 95-108 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By S. Gaillard, E. Cauda

"Diesel particulate matter (DPM) is an occupational health hazard in underground mines. It generally occurs in the submicrometer size range and is often present in the mine atmosphere with significant concentrations of dust particles that tend to occur in the supramicrometer size range. As dust can interfere with analytical methods to measure DPM, it is often removed from a sample stream using an impactor-type size selector such as the DPM impactor (DPMI). Because the DPMI physically removes oversized particles from the stream, its performance may be gradually reduced with aging. Sharp-cut cyclones (SCCs) are an alternative size selector for DPM sampling applications, with a major advantage that, by design, they should not be susceptible to rapid aging. This paper presents the results of a field study designed to compare the performance of aged versus new/clean DPMIs and SCCs in an underground mine. DPMI aging resulted in clogging of the device and, eventually, a reduction of its effective particle cut size, but when sample flow rate was maintained, DPM sample mass collection was not affected until significant aging had occurred. Under the conditions of this study, the effects of SCC aging were observed to be minimal at the end of the study period. IntroductionSubmicrometer-sized particles are increasingly recognized as significant respiratory health hazards (Cantrell and Watts, 1997; Kenny, Gussman and Meyer, 2000; Ristovski et al., 2012). Diesel particulate matter (DPM) represents a major source of submicrometer particles in both public and occupational environments (Kittelson, 1998; Abdul-Khalek et al., 1998). Relative to other occupational groups, underground miners can have some of the highest DPM exposures due to their work in confined spaces where large diesel equipment is used (U.S. Environmental Protection Agency, 2002; Grau et al., 2004). DPM largely consists of solid elemental carbon (EC), commonly known as soot, and organic carbon (OC) that may be sorbed to EC particles (Kittleson, 1998; Abdul-Khalek et al., 1998). EC and OC can be measured by thermal-optical methods such as the U.S. National Institute for Occupational Safety and Health (NIOSH) 5040 standard method (Birch, 2016), and their sum is referred to as total carbon (TC). While the complex nature of DPM does not allow for its direct measurement, both TC and EC have been accepted as suitable surrogates for monitoring occupational exposures to DPM (Noll et al., 2007; Birch, 2016)."

Jan 8, 2018

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 Clifford R. Porter

A 200 pound per hour Magnex Pilot Plant was designed and constructed. A non-compliance Eastern Coal which would generate more than 2.0 lb of SOZ per million Btu upon burning was brought into compliance (less than 1.2 lb of S02 per million Btu) during continuous operation of the pilot plant. Approximately 85 percent of the pyritic sulfur was removed while recovering 86 percent of the Btu of the feed coal. Pilot plant operation is summarized and preliminary economics presented. Present status of the Magnex Program is reviewed.

Jan 1, 1977

By J. F. Archibald

This paper reviews the formation of the Canadian Mining Education Council (CMEC) and its terms of reference. CMEC considers that Canada?s mining schools represent a distinct competitive advantage to the Canadian Mining Industry. The core objective of CMEC is to reinforce the links between the constituent schools and their individual Industry Advisory Committees. The latter traditionally provide the schools with a great deal of guidance on a range of planning issues, including recruitment, curriculum, research and infrastructure. Beyond those bounds CMEC intends to improve its ability to network with the industry and government. It is concerned overall with the objective to raise the quality and level of its educational and research contributions to meet the needs of industry and society.

May 1, 2002

By Elizabeth G. Baglin

Research was conducted by the Bureau of Mines to determine the feasibility of using electrokinetic densification to dewater Bayer process red mud, magnetic black mud prepared by pressure digestion of red mud in the presence of ferrous sulfate, and magnetic black mud formed by simu-lated Bayer digestion of Jamaican bauxite with added ferrous sulfate. Tests showed that the solids content of presettled muds could be increased from 25 pct to approximately 40 to 48 pct by gravity draining followed by electrodewatering for approximately 48 h. Electrodewatering may not be practical because of increased reagent and processing costs and because the muds must be thoroughly washed prior to electrodewatering to remove dissolved ions and decrease mud conductivities.

Jan 1, 1988

By Robert S. Becker

The results of a laboratory investigation of coal cutting mechanics and noise is presented. These experiments were performed using a linear cutting apparatus that operates over a broad cutting speed range. The influence of several coal cutting parameters on the noise, force, productivity, and specific energy associated with linear cuts is ascertained. Some basic theoretical aspects of coal cutting mechanics and noise generation are discussed, and the results of the laboratory experiments are used to Formulate analytical models of the coal cutting forces and noise. The analytical model For coal cutting noise is then generalized to account for the more important effects of rotary cutting. Based on the generalized model, an estimate of the sound pressure level at an operator's position is made for a typical continuous mining machine. It is concluded that by employing linear rather than rotary cuts, using deeper depths of cut, slower cutting speeds, and more efficient cutting tools, it is possible to reduce the level of coal cutting noise, as well as Provide benefits to other important areas of underground health and safety.

Jan 1, 1980

By Frederick K. Allgaier

This report presents the final data from a 5-yr Bureau of Mines study designed to determine the surface subsidence characteristics resulting from longwall coal mining in a geologic environment common to the Western United States, It includes a description of the geologic setting of the study site, the mine plan, measurement techniques, and results of the monitoring program. Measured subsidence values were obtained over four adjacent longwall panels- Major subsidence characteristics such as longitudinal and transverse profiles, angles of draw, time-related subsidence development, and critical width are discussed. The maxima subsidence value of 5.8 ft was 68 pct of the mining thickness. The average angle of draw was 30°, Subsidence at the center of the first panel continued for 46 months following undermining. The lengths of the longwall panels precluded a definitive determination of the critical width and maximum possible subsidence.

Jan 1, 1988

By G. W. LAAiIBOURNE

FEW mines possess a history of more fascinating interest than the Ontario at Park City, Utah. The famous Bonanza's production record of over $50,000,000; the great extent of its workings; the remarkable character of its mineralization; the fact that recent discoveries have shattered preconceived theories of the geology of the camp practically assuring the half-century old property a future as active and as prosperous as the past make the Ontario one of the unique mines of the world. A mere accounting of the wealth created by this historic property not only exemplifies the great profits

Jan 1, 1925

By R. Vernon Helm

Four tables listing values for the various physical properties of those sulfur compounds most likely to occur in petroleum and petroleum products are given herein. The data necessary to bring the first compilation2/ in this subject up to date are given in table I -Revised and Additional Data, which includes boiling points, refractive indices, densities, and freezing points. Tables 11-, III, and IV are published for the first time and include refractive indices for the F, C, and G' lines of hydrogen and the helium D:3 line; surface tensions and viscosities, and refractivity intercepts, specific dispersions, specific refractions, and parachors. The need for information concerning the sulfur compounds in petroleum is becoming-more urgent because of the necessity of refining larger quantities of high-sulfur crude oil to meet the rising demand for petroleum products. For a number of years the Bureau of Mines has been engaged in research to make available more information concerning the properties of the sulfur compounds in petroleum. The petroleum industry has recognized the value of such studies, and as a result the American Petroleum Institute has established Research Project 48A to study sulfur compounds. The investigations under this Project are to be done in Bureau of Mines laboratories as a cooperative project in connection with the work already started.

Jan 1, 1949

By J. E. Hamak

This publication contains analyses and related source data for 920 natural gas samples from 26 States and 2 foreign countries. All samples were obtained and analyzed as part of U.S. Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by mass spectrometer and chromatograph.

Jan 1, 1991

By Akihiro Higashide, Roy H. Patten

The DOT Tunneling method combines two conventional earth pressure balance shield machines in an overlapping cylindrical arrangement. The method allows two tunnels to be driven simultaneously with mini¬mum cross sectional area. Two full size trials, one configured horizontally and one vertically stacked, were successfully completed employing the DOT method. The method was then utilized for the new transportation system. The goggle-shaped DOT machine, 9.36 m high by 15.86 m wide, is the largest earth pressure balance shield machine in the world. This paper includes a general description of the DOT tunneling method as well as a history of its development.

Jan 1, 1995

By X Hill

Throughout the 2016/2017 financial year, the NSW Resources Regulator conducted an assessment of each underground metalliferous operation across the state to assess how each operation managed the principal mining hazard of ground and strata control. The assessment considered all aspects of the mining process, including all aspects of managing geotechnical risk within drawpoints. This assessment is ongoing and, therefore, this paper is limited to the first six mines assessed in the program.In 2015 there were three fatalities in and around underground drawpoints in Australian metalliferous mines. Whilst many of the systems of work around underground development are consistent across the industry, there are large discrepancies around how each underground mining operation manage the risks associated with drawpoints.For drawpoints to be effectively managed, their management needs to be considered at the earliest stages of the mine planning process. By using downholes and adopting remote systems of work – systems that are continuing to improve with technology – the risks drawpoints posed can be greatly reduced.The assessment by the NSW Resources Regulator revealed a number of common failings across the state in the management of the risks that drawpoints pose. The assessment also observed a number of innovative practices that particular operations have adopted in the wake of serious incidents occurring within drawpoints at their operation; however, these practices have not been communicated to other operations.It is hoped the learnings from the assessment can be considered by industry and reduce the risks drawpoints pose in underground metalliferous mines.CITATION:Hill, X, 2017. Learnings from review of drawpoint management across New South Wales mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 143–150 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017