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By C. E. Melbye

A serious problem confronted the city of Gunnison early in 1958 in that, for a few months during each spring runoff, the water supply derived from the Gunnison River became polluted to an unsafe point. The city management had the choice of building a new filter plant to replace the old unworkable one or drilling wells to develop a ground water supply. The cost of a new filter plant was estimated at $180,000 compared to $50,000 for 6 wells, pumps, and additional water lines, hence their decision to attempt the development of sufficient ground water. Six wells at 300 gpm per well were estimated as necessary to handle the peak usage of 1800 gpm, compared to only 600 gpm winter usage. Although the water table is only about 7 feet below the surface, existing private wells drilled at random locations were producing much less than 300 gpm. The problem was to find sufficient quantities from about 6 wells. Since the presence of an ancient bedrock channel was suspected, which would be expected to localize greater quantities of water, the city of Gunnison authorized a resistivity survey to investigate bedrock topography below unconsolidated gravels. Survey results were highly satisfactory and led to the preparation of a fairly detailed bedrock contour map, Fig. 1. This map was used in selection of all well sites. The city of Gunnison is situated in a flat, broad, Quaternary gravel-filled valley (terrain dips south at 20 feet per mile) at the junction of the Gunnison River and Tomichi Creek. The valley, about 2-4 miles wide, is bordered by hills of Tertiary volcanics to the northwest, Cretaceous and Jurassic sediments to the north and northeast, and pre-Cambrian granite and gneiss to the south. One previous deep test well at the west end of the city hit pre-Cambrian granite at 496 feet, which, allowing for 40 feet of surface gravels, makes the older sedimentary section 456 feet thick. This section is probably all Jurassic Morrison formation, consisting of the Saltwash sandstone overlain by the much thicker section of Brushy Basin shales and mudstones. According to the driller's logs, each well was bottomed in what is believed to be Brushy Basin shale. FIELD PROCEDURE A standard Gish-Rooney type of resistivity apparatus was employed, which used 45-volt dry batteries as a direct-current power source. Applied voltages could be selected from 45 volts to a 270-volt maximum. Copper-coated steel stakes were employed as current electrodes and porous porcelain pots as potential electrodes to avoid possible polarization effects with direct current. The expanding Wenner electrode configuration was utilized for this investigation and measurements were made at 20 40, 60, 80, and 100-foot spacings,

Jan 1, 1961

Unrelieved residual strains can influence the states of stress in rock masses. If cheap, stable structures are to be constructed in Tock in which large pressures are exterted by unrelieved residual strains, the pressures must be either utilized or neutralized. A photoelastic technique has been used to show that the release of residual strains in rocks is influenced by the mechanical properties of anisotropic rock fabrics. The relationships between directions of residual strain release and the attitudes of minor geological structures have been determined. For engineering design purposes it is possible to estimate the principal stress directions in rock containing unrelieved residual strains if the attitudes of such minor geological structures as foliation planes, lineations, and joints are known.INTRODUCTIONQuarry workers have long been aware that near-surface rocks may be highly stressed. In many cases the stresses are too large to be the result of gravitational loads. Dale (1923, pp. 34-35) gives many instances of deformation produced by the violent release of residual strains in quarry rocks. Coates (1963) has described powerful rock bursts and cases of rock deformation underground implying the existence of much larger stresses than are likely to result from present-day gravitational loads. The only explanation is that pressures of up to several thousands of pounds per square inch may be caused by unrelieved residual strains in rock.Instruments have been developed for measuring states of stress in rock masses. Most stress determinations in rock have been made on the assumption that rock behaves as a simple elastic material. It is now known that rock is a...

Jan 1, 1964

By Robert Stefanko

This report, rather than attempting to replace previous annual reports, supplements, and more importantly, coordinates and summarizes the entire effort. Even with such restrictions, the report is voluminous and, therefore, a decision has been made to divide it into two parts. The first volume is basically narrative and includes tabular results and analyses. The second volume is in appendix form giving detailed information. Together, they permit a logical discussion of all aspects of the project (Volume I) without cumbersome distractions but, at the same time, provide all the details to permit others to evaluate and explain the results or develop similar research programs (Volume II). The aim of the original proposal was basically to develop instruments and techniques and then make measurements of suitable power parameters, ground fault currents and ground resistance beds. With such information available, it was possible to develop a meaningful simulator which would permit investigating electrical systems and components on paper without costly trial and error procedures in the third year, a cable splice testing program was added to the project. While there were the usual delays attendant in such original research, these objectives were achieved.

Jan 1, 1973

By G. Andrews

This case study details the process that was used for project planning and permitting for the Greens Creek Mine, located near Juneau Alaska, as seen through the eyes of one of the primary environmental consultants. This case shows how a Company could involve the public and the agencies in the early 1980's and develop a project sensitive to concerns expressed with a high level of environmental protection. Comparisons are made to the current environmental permitting situation. Initial baseline studies performed during the exploration phase provided helpful information for more detailed environmental work in 1980-1981 as planning and permitting formally got underway. Since the mine was in a National Monument and abuts up to a designated wilderness, the Monument Manager administered the project for the lead agency, the USDA Forest Service. Planning and permitting progressed smoothly to a Final Environmental Impact Statement (FEIS) in 1983. Metal prices were depressed when the FEIS was completed and the project permitting proceeded slowly. Ownership changed several times in the mid-1980's. New owners re-evaluated the project and suggested five changes that required a supplemental EA prior to development. The project was fully permitted and started construction in 1988. Operation began in 1989. Today the environmental process in southeast Alaska is now much more complex, detailed, expensive, and time consuming than in the early 1980's. Significant issues discussed that may impede development and operation include overlapping agency jurisdictions, personal agendas of agency staff, conflicts between agencies that impede project progress, changing regulations, and a well organized environmental opposition.

Jan 1, 1993

Flat jack stress determinations in selected colliery roadways have revealed a range of measured stress from 330 lb/sq. in. tension to 3,750 lb/sq. in. compression. Photoelastic examination of loaded plastic and actual rock model mine openings has shown that the primary horizontal stress required to attain these measured stresses would be from one to three times the superincumbent vertical load.Examination of roof movement with a borehole extensometer and a series of anchors at various horizons to 30 feet in a vertical roof borehole showed that when a standing face was advanced the roof movement was practically confined to the lower two feet. The majority of this movement occurred during the 36 hours after mining at this face commenced.The use of a radioactive isotope and a scintillation counter in a pair of parallel boreholes is a sensitive and accurate method of roof bedding plane crack detection.INTRODUCTIONA knowledge of strata stresses is required to understand the deformation of an underground opening and, in particular, the roof behaviour. It is the aim of investigations currently being conducted by Australian Coal Association (Research) Ltd. to determine the stress existing around mine openings and the location and magnitude of roof movement.STRATA PRESSURE MEASUREMENTMost measurements of strata stress are performed at the surface of underground openings and the majority measure the change of strain resulting from stress relief. The accuracy of the measured value of stress depends upon knowledge of the rock modulus of elasticity. The flat jack method has the advantage that strain relief is restored by a measured stress applied directly by the jack. The rock modulus of elasticity can also be determined.

Jan 1, 1963

By E. L. McHugh, J. M. Girard

This paper discusses the results of two recent case studies in which high-tech prototype instruments were used. The first case study describes the results of a ground-based hyperspectral imaging tool used to map the geology of an open-pit mine highwall. The second case study outlines the use of interferometric synthetic aperture radar and how this type of radar can be used in a variety of geotechnical situations. These case studies are part of an on-going research project at the National Institute for Occupational Safety and Health’s (NIOSH) Spokane Research Laboratory. The project objective is to implement engineering controls and design methods in order to reduce the number of injuries and fatalities associated with slope failures at mining operations. Project personnel are hopeful that these new developments in technology will lead to better geotechnical monitoring and design in slope stability and other important areas of rock mechanics.

The Reefton Goldfield on the West Coast of the South Island of New Zealand was a significant gold producing area between 1860 and 1951. During this period it produced approximately 2.1 million ounces (67 tonnes) of gold. The largest single producer on the goldfield and the deepest mine in New Zealand, was the Blackwater Mine at Waiuta which produced 21 tonnes of gold. The Prolubition Shaft reached a depth of 878 metres (317 metres below sea level). The mine closed suddenly in 1951 with about 66 000 tonnes of are remaining in the stapes. Since closure there has been no attempt to determine the ore potential of the mine at depth. This paper summarises the geology, history and resource potential of the mine and sets out two options for evaluating the remaining resource. The options are either deep drilling from surface or recovery of the Prohibition Shaft and underground development and drilling. A schedule for each option is presented and discussed.

Jan 1, 1992

By Adriano Santos

O presente trabalho busca apresentar o desenvolvimento, as diferenças e os resultados dos testes de flotação em bancada em circuito fechado (locked cycle test - LCT), desenvolvidos para avaliar o circuito industrial do projeto Morro do Pilar da Manabi que foi projetado para processar um itabirito com 30% de teor de ferro. Para buscar a máxima eficiência na recuperação de ferro a rota de processo desenvolvida prevê a flotação em duas estreitas faixas de tamanho: a faixa -0,15+0,044mm será processada em células mecânicas e a fração -0,044mm em colunas de flotação. Por se tratar de um minério de baixo teor, houve a necessidade de desenvolver um teste de bancada, preciso e robusto, para avaliar o desempenho do itabirito no circuito industrial projetado, composto por etapas de flotação rougher, cleaner, recleaner e scavenger. O teste em circuito fechado desenvolvido apresentou excelentes resultados, coerentes com o desempenho de testes piloto contínuos feitos com o mesmo itabirito pobre.

Aug 2, 2018

By M. Lonoff

G. Campbell The paper by M. Lonoff looks at the importance of byproduct prices on copper production. The paper develops several interesting points on this topic, but there are some points in the theoretical discussion that could use further development. A couple of these theoretical topics will be considered here using the paper's framework of assumptions without concern about how realistic the assumptions are for the copper industry. Lonoff's theoretical model is based on a static, homogenous world where all copper/byproduct deposits are identical, and these deposits are the main source of these metals. Due to the importance of the byproducts to the production decision, the term coproducts will be substituted for the term byproducts to reflect more accurately this condition. The conclusion is drawn that a rise in coproduct prices necessitates a decrease in copper prices because copper production is increased as a consequence of increased coproduct production. The observation that real world behavior does not always follow this pattern is dismissed as "speculation." However, it can be easily shown that within this simple framework market forces might create the observed behavior. The key question to be answered is what causes coproduct prices to rise. Three possible cases will be used as illustrations. The first case is the one implicity assumed by Lonoff. Here, the demand for coproducts increases at all prices (an outward parallel shift of the demand curve) with the demand for copper remaining constant. As reported in the paper, the results are higher coproduct prices, an increase in coproduct production, and lower copper prices due to the resulting increase in copper production. The second case is when the supply of coproducts are constrained-leading to higher market prices. Copper production, as required by the simple model, is also reduced which Reply by M. Lonoff Campbell's comments give me an opportunity to clarify a few points in "Copper and Its Byproducts." That paper examined the affect of byproducts on the copper market and considered the relative riskiness of multi-metal deposits from an investment standpoint. That brief note made no attempt to be exhaustive. Nevertheless, Campbell's comments miss the point of the paper and necessitate a response. My "theoretical model" was static and I freely conceded after introducing the assumption of identical deposits that "none of the assumptions hold." These simplifying assumptions allowed me to bound the possible effects of higher byproduct prices on the copper price by assuming identical deposits and computing average price effects. I took great pains to subsequently explain that since deposits are not identical the identity of the marginal deposit might change due to byproduct price changes. In this case, average price affects will overstate the affect of byproducts on copper prices. According to Campbell, I dismiss as speculation any "real world behavior that does not always follow this pattern" (of metals prices moving in opposite directions). In the byproducts paper I noted that gold, copper, and silver price movements often parallel each other on an intra-day or day-to-day basis. Such movements are largely due to market anticipation of or reaction to changes in interest rates that affect carrying costs of metals stocks. Other movements may be due to anticipated changes in available supply or physical requirements. I loosely grouped these effects as speculative. To distinguish this statement from the main thrust of the paper, I contined "In the long run if gold and silver prices remain high the equilibrium copper price will be lower." The paper set out long run equilibrium conditions rather than attempting to explain price movements on a daily basis or on a year-to-year basis.

Jan 11, 1983

By R. Heath Forbes

The route of a new, 4-mile long, electrical transmission line passed through residential neighborhoods and commercial areas of a small town in the South Carolina Coastal Plain. The new line consisted of 54 new poles and a one-mile underground section. Most of the new poles were constructed within 50 ft of existing structures, and in some cases, within 8 ft to 20 ft. A widely-space subsurface exploration consisting of 20 cone penetration test soundings indicated the subsurface conditions along the alignment generally consisted of saturated, loose to medium dense, fine slightly silty to silty sand. The pole foundations consisted of 20 to 30 ft long, prefabricated ?caissons? (essentially an open-end pipe pile with a prefabricated connection system at the top) with diameters of 28 to 56 inches. The steel caissons were installed with vibratory pile hammers. To help prevent damage and defend against possible allegations from nearby property owners, vibration and settlement monitoring was performed during all foundation installation activities. Limited structural condition assessments were also performed before and after foundation installation. For 53 of the 54 foundations, the ground vibrations recorded at distances coincident with the nearest structure locations ranged from 0.05 inches per second to 1.46 inches per second. With consideration of the dominant frequency, the majority of these values were below the commonly used USBM vibration limits. For a foundation installation that was only 8 ft from the nearest structure, a peak particle velocity of 3.06 inches per second was recorded, which exceeded the USBM limits. For all cases, the measured ground surface settlement was negligible (i.e., less than ¾ inch). Several spurious claims alleging vibration-induced damage were made, but the monitoring program provided an adequate defense. One claim involving artwork that fell to the floor during foundation installation at a distance of 8 ft from the house was deemed legitimate.

Jan 1, 2011

By Henry Kreisinger, John Blizard, B. J. CROSS, C. E. Augustine

This report gives the results of 26 tests of a four-pass Edgemoor boiler fired with powdered coal at the Lakeside station of the Milwaukee Electric Railway & Light Co. The tests were made by the fuel section of the Bureau of Mines in cooperation with the research department of the Combustion Engineering Corporation and the operating department of the Milwaukee Electric Railway & Light Co. The object of the tests was to determine the thermal efficiencies and capacities obtainable by burning powdered coal under large central-station boilers, and the possibility of operating such boilers continuously at high efficiency and capacity without destructive effect on the furnaces and without difficulties in refuse removal. In any system for burning pulverized coal the furnace is the most important part because, to justify the cost of pulverizing, the powdered coal must be burned with higher efficiency than coal fired with mechanical stokers. In other words, it is the furnace that by giving higher thermal efficiency must pay for the installation, maintenance, and operation of the pulverizing equipment. No matter how simple the apparatus for the preparation of pulverized coal may be, or how simple the pulverizing process, unless the furnace is so designed that it can be operated continuously with high thermal efficiency, the whole system is a failure. For high thermal efficiency the coal must be burned almost completely with low excess air. But low excess air and complete combustion give high furnace temperature, which in turn causes erosion of the furnace lining and fusion of the ash; and removal of the fused ash is difficult. The necessity of complete combustion with low excess air thus brings with it these two important problems in the design of a furnace for burning powdered coal: 1, Prevention of erosion of the furnace lining; 2, easy removal of refuse from the furnace. For the purpose of solving these problems, the boiler tested was equipped with a furnace having hollow walls, through which about 60 per cent of the air needed for combustion passed before it entered the furnace. By passing through the hollow walls, the air cooled the furnace lining and prevented excessive erosion. A water screen was placed in the furnace about 3 feet above the bottom to keep the refuse deposited at the bottom from fusing and to make its removal easy. The design of the furnace, water screen, and burners was based on the experience gained in the previous cooperative tests1 with a smaller furnace, experimental water screen, and burners at the Oneida Street station of the Milwaukee Electric Railway & Light Co. The boiler tested had 13,057 square feet of heating surface. It was one of eight boilers fired with powdered coal, and was designated as boiler No. 8. The Lakeside station is the largest central station in the world that burns powdered coal exclusively. The coal used in the first five tests came from Illinois. The fuel in the other tests -:vas a mixture of Illinois and Pittsburgh coals.

Jan 1, 1925

By A. Uiga

The U.S. Bureau of Mines funded a project which addressed objectives concerning irrigation of native plants and inoculation of native plants with vesicular-arbuscular mycorrhizal (VAM) fungi. The specific irrigation objectives were 1) to demonstrate the performance capabilities of solid-set irrigation for reclaimed mineland conditions, and 2) to demonstrate and evaluate three irrigation concepts under two separate water supply conditions. The VAM inoculations were to assess irrigation benefits in establishing VAM relationships for transplanted native species. Following the seasonal demonstration (May to September 1983) at 3 separate mine sites, conclusions were made that apply to the 6 state Western mining industry. The demonstration sites were located in Montana, Wyoming, and New Mexico. Positive conclusions were reached for 1) the use of soil moisture sampling with or without irrigation, and 2) the selection of solid-set sprinklers as the irrigation method. The conclusions about the irrigation concepts and strategy were mixed, due to the short-term (1 season) nature of the project. No conclusions could be reached for the VAM inoculations because the study time was too short.

Jan 1, 1984

By H. J. McQueen

Friction stir welding (FSW) generates complex microstructures in the nugget and thermomechamically affected zones (TMAZ) that have led to diverse explanations. However, consideration as an extension of microstructure development in piercing/extrusion can lead to a better understanding of flow patterns and microstructures during FSW. Furthermore, the intense strains in the nugget/TMAZ can be interpreted by comparison with ultra-high strains in torsion that exhibit dynamic recovery as extending into regions with high angle boundaries strongly serrated with spacing near the subgrain size defined by the high temperature. The subgrain diameter and extrusion pressure have been shown to be dependent on the Zener-Hollomon parameter Z (=t exp(Q/RT), Q activation energy, R gas constant) combining temperature T and strain rate E in the same mariner as for torsion and compression. Moreover, such tests exhibited steady state stress os above a certain strain Es (rising as Z increases) in which T, , subgrain diameter and dislocation spacing remain constant. Due to the subgrain boundaries (SGB, low angle <5°, i.e.,LAB), continually rearranging by migration, decomposition and reformation, the subgrains remain equiaxed in elongating grains, whose boundaries (GB) become serrated as they migrate to absorb SGB. As confirmed by straining in torsion at constant T and Z. , more subgrains bordering the greater GB area have several high-angle facets (HAB) ; these small cellular regions with a mixture of HAB and LAB facets are designated HAB-subgrains. As serrations in neighboring grain boundaries impinge, the grains pinch off becoming shorter; this occurs at higher strains as subgrain size decreases with rising Z. The pinching-off makes the neighbors thicker so the grains never become thinner than about two subgrain diameters. In conjunction with such geometric dynamic recrystallization (gDRX), GB&apos;s undergo a net migration into grains with denser substructure, enlarging those with larger subgrains. Consequently a better name has been proposed: grain dimensioning dynamic recovery (gDRV).

Jan 1, 2007

By G. S. Harper

Noise in general and drilling noise in particular have received increasing attention within the South African mining industry during the last 10?15 years. The Mine Health and Safety Committee1, during their 2003 annual summit, established two significant milestones to be met by December 2008 and December 2013. The 2008 milestone target is that of no more than ten per cent deterioration in hearing among occupationally exposed individuals, whereas the 2013 milestone target is that of less than 110 dB sound pressure levels at any place in the workplace. While these targets relate to general noise within the mining industry, it is widely believed that the most significant source of noise contributing to noise induced hearing loss (NIHL) among the underground workforce, is that of pneumatic rock drills. Data pertaining to the noise emission level of any machine is generally reported as either a sound pressure level or a sound power level of a single machine measured under free field conditions as defined in Appendix 3 of SABS-ISO 37442. However, rock drills are seldom used in isolation and underground conditions cannot be considered as free field. A methodology for the selection of rock drills on the basis of total operating cost has been developed. However, this paper focuses on the noise elements of the generic methodology and provides a model for the prediction of the composite sound pressure level and the equivalent noise exposure levels of groups of individuals from machines, used singly and in combination in an underground environment based on the sound pressure level determined according to SABS-ISO 3744 under free field conditions. The methodology includes provision for the consideration of the effect of hearing protection devices and the use of multiple machines in combination and provides an indication of the potential costs of hearing compensation.

Jan 1, 2006

By Kehsin Kuo

DIE steel with 1.47 pct C, 0.42 pct Mn, and 8.22 pct W contains Fe,C and WC in the annealed state and WC embedded in a martensitic matrix in the hardened state (quenched from 800°C). The presence of a large amount of undissolved angular WC carbide particles makes this steel extremely wear-resistant. However, the WC carbide begins to dissolve in the austenite when the heating temperature is raised above 1000°C, but this solution process is still not complete at 1250°C although partial melting has already taken place at the austenite grain boundaries. At 1325 C, this steel contains austenite and liquid metal but no WC carbide, Fig. 1. On quenching into brine, the liquid metal solidifies into a constituent which etches differently from the austenite-martensite matrix. This constituent appears lighter than the matrix at the 1250°C stage when etched with 2 pct nital but darker in Fig. 1 when etched with Murakami&apos;s reagent. Such a constituent has also been found in burnt tungsten high speed steels. This constituent has been isolated from the matrix by anodic dissolution in a 5 pct HC1 electrolyte and was found by the X-ray powder method to be iso-morphous with &manganese, Table I. The agreement in line intensity between these two phases indicates that there is no ordering in this new phase. The calculated cube edge of this phase is 6.395A, somewhat larger than that of ß-manganese (6.30A). Besides this phase, the anodic residue also contains free carbon from the matrix and amorphous WO,, although the X-ray powder pattern of the residue shows the presence of only this phase. This makes it impossible to determine directly the composition of this phase from the residue. Attempts to prepare an alloy containing only this phase have hitherto been fruitless. The following experiments serve to show that this phase can only be obtained by drastic quenching from the liquid state and that its tungsten and carbon contents must be lower than those in the Fe,W,C carbide. On air cooling from 1325oC, the liquid metal solidifies into a eutectic consisting of austenite and the Fe3W3C carbide. The nature of this dark-etching Fe3W3C has also been ascertained by X-rays. This eutectic becomes coarser on furnace cooling. The solidification of a specimen cooled for 5 min from 1325" to 1200°C and water quenched is still not complete and the fine eutectic is formed during the quenching. Since this new phase can be replaced by a eutectic of austenite and the Fe,W,C carbide, its composition must lie somewhere between the latter two phases. The special features of this phase are: 1—it can only form directly from the liquid state by drastic quenching and 2—it is a ternary phase of iron, tungsten, and carbon. The ß-manganese structure of this phase is also interesting. In the Periodic Table, iron and tungsten lie on opposite sides of manganese; a certain combination of these two elements, in the presence of carbon, may have average properties similar to those of manganese. It has already been established that the x phase, a ternary one of iron, chromium, and molybdenum, has the a-manganese structure."&apos; A similar phase has also been found in the ternary system Fe-Cr-W and in the following binary systems: Re-Cb, Re-Ta, Re-Mo, and Re-W.6 References 1 G. D. Preston: Philosovhical Magazine 11928) 5. 7th Series, p. 1207. - K. W. Andres: Nature (1949) 164, p. 1015. 35. G. McMullin, S. F. Reiter, and D. G. Eberling: Trans. ASM 11954) 46, p. 799. &apos; J. S. Kasuer: Acta Metallurgica (19541 2, p. 456. • H. J. Goldschmidt: Trans. ASM (19541 46, p. 807. P. Greenfield and P. A. Beck: Private communication.

Jan 1, 1957

By Laurance A. Beck

Safety is the most important aspect of haul road design. Although other aspects of road installation enter decisions on design, the safety of persons using the road has to be foremost for the duration of haul road usage. Other aspects of mad design focus on minimizing truck cycle time and fitting haul roads to the long-term configuration of the mine/quarry or construction project. Roads are often installed at high gradients for a short-term goal, but the long-term benefits are easily shown with lower gradient haul roads which provide better cycle times and lower operating costs.

Jan 1, 1995

By M. Gangal

CANMET-MMSL, in cooperation with Dry Systems Technologies and Quinsam Mine, conducted a study to determine the effects of B50 biodiesel on the emissions of a flameproof diesel power package in comparison with mining diesel fuel for application in underground coal mines. The emissions testing for coal mine application requires that the intake air mixture to the engine should be at 1.25 percent methane by volume in air. The tested power package system included a naturally aspirated, mechanically-controlled diesel engine with a diesel oxidation catalyst (DOC), a heat exchanger, flame arresters, and a low temperature disposable diesel particulate filter. The engine dynamometer tests were conducted at the CANMET-MMSL Diesel Emissions Research Laboratory in Ottawa using the ISO 8178-C1 test protocol. The separate and combined effects of a B50 biodiesel blended fuel, and with and without 1.25% methane enriched intake air were measured on a diesel power package. Fuelling the baseline engine (without methane), with B50 biodiesel blend reduced carbon monoxide (CO) by 44%, and increased nitrogen dioxide (NO2) by 19%, and particulate matter by 31% relative to the mining diesel fuel. Similarly, injection of 1.25% methane to the intake air for baseline engine with mining diesel fuel increased engine power by 15%, CO by 124%, and NO by 15%, and decreased NO2 by 13%. The effect of B50 biodiesel relative to the mining diesel for coal mines application (with methane for both fuels) was to reduce CO by 27%, and NO by 6%, and increase NO2 by 23%, with no change in engine power. The overall results indicate that the minimum ventilation rate for the equipment application in coal mines with B50 biodiesel was 4.11 m3/s (8,700 cfm), slightly higher than the ventilation rate of 4.01 m3/s (8,500 cfm) with the mining diesel fuel. This slight increase in ventilation rate for B50 biodiesel fuel was due to an increase in NO2 at one of the operating test points, and the ventilation rate for this equipment was governed by NO2 in the exhaust gas.

Jan 1, 2009

By Tiago Silva Costa

O processo que envolve soluções aquosas para remoção do metal de valor de uma grande massa de ganga, com um beneficiamento mínimo, é denominado Lixiviação. A especificidade do agente lixiviante empregado define a capacidade de tratar soluções com baixos teores do metal de interesse e o sucesso do processo. A lama da aciaria, recolhida no sistema de limpeza dos gases oriundos do convertedor LD, e a lama da eletrogalvanização, gerada após a neutralização da solução de zinco contaminada com ferro, são resíduos sólidos gerados nas usinas siderúrgicas com potencial de serem reutilizados ou reciclados. A fim de se remover o óxido de zinco presente nas lamas, amostras foram coletadas e preparadas para sofrerem o processo de lixiviação em escala laboratorial usando soluções de hidróxido de sódio (NaOH) e ácido sulfúrico (H2SO4). Os resultados obtidos nas análises mostraram que é possível remover óxido de zinco através da lixiviação das lamas.

Aug 16, 2017

By Luis Enrique Vargas

En las operaciones a tajo abierto, la generación y control de vibraciones juegan un papel importante en la estabilidad de taludes a lo largo del tiempo. Para mantener un diseño de minado óptimo y seguro en Toquepala, el autor ha contemplado 7 factores (caracterización geotécnica, diseño de malla, diseño de carga, análisis de secuencia de tiempos entre taladros y filas, análisis de vibración tanto en piso como en cara de banco, calidad del precorte y evaluación geotécnica de voladura mediante celdas) al desarrollar esta metodología denominada Evaluación geotécnica integral de voladura. El trabajo incluye conclusiones y recomendaciones precisas.

Sep 20, 2019

Comparative Studies on Balls Versus Spheroidal Tetrahedrons Working Media to Ore Grinding in an Industrial Drum Mill

Sep 13, 2010