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By NRMR Bhargava

With the increasing use of lead-free solder alloys, low melting point alloy is often required due to the heat- sensitive parts or substrates in modern electronic devices. For such demand of low melting point, the nanostructure lead- free solder alloy, having excellent metallurgical characteristics and a melting point of <215oC, were developed by mechanical attrition of conventional lead free solder alloys (Sn-Ag-Cu, Sn-Ag and Sn-Cu). The decrease in melting point due to nanosize effect was calculated theoretically as function of particle size and the theoretical results were compared with experimental values measured by differential scanning calorimetry. The newly developed alloys have eutectic composition of Sn-3.5Ag-0.7Cu, Sn-3.5Ag and Sn-0.7Cu and the melting point depression found to be 5.10C, 4.10C and 6.20C when the bulk alloys reduced to 80 nm, 92nm and 96nm sizes respectively.

Jan 1, 2009

By A. P. Squelch

The high incidence of accidents and fatalities in the South African mining industry, in particular those associated with falls of ground, is often attributed to ineffective and/or inappropriate training methods and material. Recently introduced mine health and safety legislation in South Africa also requires that all mine workers receive appropriate and effective training to enable them to operate safely in their given mining environment. There can, therefore, be no doubt that methods to provide effective training, in particular safety related training, are urgently required in the South African mining industry. In the search for alternative and improved training approaches, attention has fallen on virtual reality (VR) technology as a possible solution. VR has found acceptance in a number of industries as an effective method of training for a variety of work place activities, including those of a safety related nature. VR has successfully been applied in a number of industries to improve the effectiveness of safety and hazard awareness training. The CSIR: Division of Mining Technology (CSIR Miningtek), in conjunction with the Safety in Mines Research Advisory Committee (SIMRAC), therefore evaluated the potential of VR to be used as a training medium in the South African gold and platinum mining industry. Aspects of the evaluation included an assessment of the technical capability of VR to represent a typical underground mining environment with sufficient realism and the relevance of the VR training concept for a largely illiterate workforce. For these purposes, a prototype PC-based VR hazard awareness training simulator has been developed by CSIR Miningtek, and a series of evaluation sessions conducted at a typical deep level gold mine. The conclusion from this evaluation work is that virtual reality technology has the potential to provide effective training systems that are relevant to the South African mining industry. Keywords: Virtual reality, mine training, safety training.

Jan 1, 2001

By A. J. MOORE

When the writer first saw the square-set timbering, he was at once impressed with the fact that the frames made by the sets, along the lode and across it, were composed of panels with rectangular openings, and it was puzzling to understand howsuch a collapsible construction could resist pressure that came unevenly on it. Later he learnt that the sets did not satisfactorily resist such pressure, but mullock filling had, to a great extent, to undertake this duty for them. So it appeared that the setswere practically an expensive scaffolding, enabling the miners to work in the face and carry the stope forward, till the filling was put in behind them to take the pressure of the roof and sides of the excavation. Of course some of the pressure is takenby the sets, but this is because &quot;the set timbers prevent the filling being done perfectly; if it were practicable to remove the sets before filling, the filling by itself would more effectively support the back and wall, than do the combined sets andmullock. On the whole, therefore, the sets can hardly be said to be of much benefit where pressure has to be resisted. Despite this, the system has been of immense service in mining wide lodes, but for all that, it can only be pronounced a makeshift.This is no reflection on Deidesheimer, the famous originator of the square set, for, as will be shown later on, this way of...

Jan 1, 1912

By Nelver Benavides

"Actualmente en la industria minera, las técnicas de control avanzado, la integración de procesos y tecnologías ya no son consideradas como conceptos exóticos y de dudoso impacto productivo, sino solo como un eslabón más en el proceso de mejora continua. En ese sentido, el presente texto señala la integración de estas tecnologías en la Concentradora Cuajone – Southern Perú, considerando las operaciones de chancado, molienda, sistemas de recuperación de agua y proyectando expectativas a mediano plazo para las operaciones de flotación, extracción y voladura. "

Sep 12, 2011

By N M. Vegter, C B. Kohler, E H. O Meyer

Zincor operates four Lurgi fluidised-bed roasters at its roast-leach-electrowin refinery in Springs, South Africa. In 2006, Zincor?s four roasters had reached ages ranging between 26 and 38 years, while the expected life of this type of roaster is generally 20 to 25 years. Based on its condition, Roaster 3 was the first to be rebuilt in 2006. Roaster 4 is being rebuilt in 2007 and the last two roasters will be rebuilt over the next few years as necessary. The main damage to Roaster 3 was caused by buckling of the roaster steel shell. This caused the freeboard and dome areas to shift, resulting in cracks in the dome brick lining and crumbling of the bricks lining the freeboard. The steel shell buckled due to the combined effects of too-high operating temperatures and corrosion caused by the following two main factors: ? Thicker external insulation was installed during a previous maintenance shut which resulted in and increased steel shell temperature and exacerbated the normal metal fatigue; ? SO2/SO3 containing gas that had permeated through the brick lining, passed through its dew point during frequent planned and unplanned shuts over the life of the roaster. This caused acid formation between the refractory brick lining and steel shell, resulting in corrosion of the shell. The initial plan was to replace only the damaged areas of Roaster 3, but upon dismantling more damage was found and the roaster was rebuilt from the tuyeres upwards. During the rebuild, the opportunity was taken to modify the design of some of the brickwork to extend its life and make future repairs easier. This paper discusses the mode of failure of Roaster 3 and the lessons learnt during its dismantling and rebuilding.

Jan 1, 2007

By M. Ahrens

The paper describes the main drive systems of an iron ore pelletizing plant and related important design aspects. It is shown how today?s drive systems provide the desired flexibility for the process and lead to high energy efficiency and system reliability. With respect to electric drives expansion projects have many technical issues in common with green-field installations. However, there are aspects where important, distinct differences occur. It is shown which considerations for selecting and sizing drive systems for such a plant as well as for integrating them into an overall plant control concept need to be taken into account. Besides the design of the drive systems a key aspect for such an expansion project is the network interaction. Harmonics levels at different points in the plant network need to be checked carefully with simulations during the design phase to avoid problems later-on during operation. The power factor compensation and the harmonic filtering of the new production line cannot be designed independently of the already existing plant. The paper highlights areas where problems could occur and which points need to be paid attention to when a plant is expanded.

Jan 1, 2008

By Theresa Y. Schulz

It is interesting to study the noise standards that have been promulgated in the US over the last decade or so. These regulations are likely to have long-lasting impact. The Occupational Safety and Health Administration (OSHA) Hearing Conservation Amendment (March 1983) continues to have influence not only in the workplace but in the debate over new regulations. Both the Mine Safety and Health Administration (MSHA) and Federal Railroad Administration (FRA) regulatory preamble documents state the desire to be consistent with OSHA. An examination of Table 1, which compares the major components of the three regulations and the 1998 NIOSH “best practices” criteria, depicts the extent to which that intent is met. There has been some regulatory activity in the last decade which may give some hope for evolution and updating based on the wealth of science that has occurred during the last quarter of a century since the OSHA regulation was enacted. However there has also been some “back-sliding” toward more lenient standards. The MSHA noise standard made regulatory progress in September 2000 by emphasizing engineering and administrative controls, followed by personal protective equipment, in the hierarchy of noise intervention. MSHA’s requirement for technician certification (today only available from CAOHC) strengthened the training requirements for audiometric testing in hearing conservation programs and MSHA also added the requirement of dual hearing protection at 105 dB TWA. There were many subtle differences between OSHA and MSHA based on comments and a desire to clarify some of the vague aspects of the OSHA noise standard, and meet the needs of the regulated mining industry. One example pertains to the ceiling for exposures. OSHA says, “no exposures >115 dBA,” which is interpreted to mean no unprotected exposures above that level, giving credit for the assumed effectiveness of hearing conservation programs, hearing protection devices and administrative and engineering controls. MSHA specified that a “P” code1 violation be issued for any protected or unprotected exposures >115 dBA. The Federal Railroad Administration (FRA) noise standard for railroad operating employees, which went The Modern Evolution of Hearing Conservation Regulationsinto effect February 26, 2007, was expressly based on the OSHA standard but also uses MSHA for comparison. The preamble states that the FRA defers to OSHA as the “primary regulator of noise in the workplace,” but also acknowledges the need for some departure from the OSHA regulation (FRA Preamble II.B). As an example, FRA requires testing at 8000 Hz “because it will allow employers to identify hearing loss sooner.” The FRA rejected MSHA’s hierarchy of noise controls in favor of requiring specific engineering interventions and focusing on appropriate hearing protection which would still allow communication and audibility, and identification of excessive noise through employee-filed “excessive noise reports.”2 Where OSHA has no specific mandate requiring employees to take advantage of the employer-paid audiogram, it has been traditionally a condition of employment and is generally accepted that OSHA-covered workers require an annual audiogram. MSHA addressed this issue in its preamble; however, they made no significant change. MSHA employers are required to offer annual audiograms but MSHA stopped short of requiring employees to comply with annual audiometric testing. The MSHA preamble does allow that mine operators can also make audiometric monitoring a condition of employment. FRA requires employees to

By Robert Jakiel

The following paper is being presented to provide an understanding of the Deep Soil-Cement Mixing (DMM) performed at Contract C09A7 at the Fort Point Channel Site (FPC), for the I-90/I-93 Interchange of the Central Artery/Tunnel Project (CA/T), Boston, MA. The paper is written as a summary of the DMM from the DMM Contractor&apos;s perspective. The summary provides technical information and practical observations that are currently considered to be state-of-the art knowledge within the soil mixing industry. The observations and information are being provided by Robert L. Jakiel, Chief Engineer of SMW Seiko, Inc., who was the DMM Project Manager and Project Engineer for the A7 Joint Venture at FPC. The DMM was started in April of 1996 and completed in December 1999. The various acronyms and terminology used to describe the soil mixing are found in a section at the end of the paper.

Jan 1, 2000

By S. G. Shabestari, S. Saeidinia, P. Mokarian

"The experiments were conducted to investigate the influence of various process parameters in rotary degassing of aluminum alloy AS5U3G. Degassing was carried out by use of argon inert gas. The flow rate of the gas was investigated in the range of 12 to 21 L/min., 350 to 500 rpm rotor speed, 6 to 12 minutes degassing time, and 755°C to 780°C melt temperature. Degassing efficiency was evaluated through measuring the density of RPT samples. By optimizing the process parameters, RPT sample density was increased up to 2.73 g/cm3, which guaranties the production of high-quality aluminum castings. Tensile strength and elongation were increased considerably by degassing process. Scanning electron microscopy (SEM) shows small size and well-distributed microporosity. IntroductionOne of the major problems associated with the casting of aluminum alloys is the formation of gas porosity. Aluminum and its alloys are very susceptible to hydrogen absorption. Because solubility is much lower in solid state than liquid state, hydrogen atoms leave their position during solidification and combine together to form hydrogen molecules. These micrometer- scale cavities, called microporosity, cause the reduction of mechanical properties, particularly strength, ductility, fracture toughness, fatigue resistance, pressure tightness, and corrosion resistance (Laslaz, 1991; Jorstad and Rasmussen, 1993; Sigworth and Wang, 1994; Korasani, 1996; Anson and Gruzleski, 1999; Zhang et al., 2000). To avoid these problems and produce good quality castings, it is necessary to remove hydrogen from the melt. Several methods are available for degassing aluminum melt. One of them is a rotary degassing system using inert gas, e.g. Ar or N2. Various thermodynamic and kinetic factors govern the removal of hydrogen from molten aluminum (Anderson, 1987; Sigworth, 1987; Pignault, 1993; King and Reynolds, 1995). These are some parameters that affect degassing efficiency. Some of them are discussed here and some are examined in this project."

Jan 1, 2004

By Mark A. Williams

"This paper was originally intended to be a presentation of a case study of two surface bituminouscoal mines in the southern Appalachian coal fields located within five miles of each other. These mines were nearly identical in every aspect from geologic setting to equipment application. Althoughrepresentatives from each mine desired to participate in the preparation of this paper through support in providing background information and in review and editing, it was later concluded that, due to the environmental sensitivity associated with each mine, it may not have been a good decision to present this case study in a public forum."

Jan 1, 1994

By T. H. Chan

As the University of Hong Kong and their advisors planned their new Centennial Campus it became clear that they would have to re-provide existing water reservoirs on an adjacent site with new salt water reservoirs located underground in two new caverns. The existing reservoirs are owned by the Water Supplies Department who provide salt water for sanitary flushing and a separate potable water supply for regular use. Although underground reservoirs had not previously been adopted locally, the planning has been completed to a tight schedule and the construction is well advanced. The need to preserve historic buildings imposed constraints, as did the requirement to minimise potential construction nuisance for the local community and environment. This paper presents the background to the project and the work carried out to develop an innovative, sustainable and environmental acceptable solution. Construction progress to date is also presented.

By Alexander J. Verstraeten

Work started on the building of the Amsterdam Concert Hall in 1880 by driving over 2000 wooden piles of 13 m on which foundation-beams out of wood and brickwork were made. During construction the design was changed. This was due to the latest German developments, requiring double walls instead of single, so that the space in between could be used for ventilation and heating. Therefore the pile load, originally designed at approximately 100 kN, increased even to 170 kN for some piles, causing settlements and unacceptable cracks in the brickwork. Settlements of up to 18 cm were measured. In 1985/1986 around 400 vibration-free Tubex-displacement-piles were installed under the Concert Hall, with a shaft of 0355 mm, a pile shoe of 0560 mm and a pile length of approximately 18 m. After these Tubex piles had been installed they took over the complete weight of the whole building, thus eliminating further settlements and damage. 95% of all the construction activities took place while the concerts went on. The chosen solution also made it possible to create a new basement under the Concert Hall as an extension for dressing-rooms etc.

Jan 1, 1987

By John J. Sammarco

The U.S. Bureau of Labor Statistics reports that the mining industry has the highest average annual fatality rate (31.9 per 100,000 workers) among all major American industry. To address this, a major research program to reduce hazard exposure of miners with computer-assisted mining equipment was initiated by the U.S. Bureau of Mines.1 One application involves the manual process of extracting and hauling coal where operators, in the tight confines of a mine, can be struck or caught by mobile machinery. The approach to remedy this problem uses a guidance system on the haulage equipment so that it follows the machine that extracts coal. This, in essence, involves sensor-based docking of the machines. Sensors that can survive the hostile mine environment of dust, methane gas, and water, play the key role. Computer analysis of the mining machine&apos;s movements and empirical machine characterizations were conducted to establish operating requirements and spatial limitations to ensure proper loading of coal into the haulage equipment. These data served in the selection of a sensing system. Various technologies such as scanning laser systems and ultrasonic sensors have frequently been used in other applications but were found unacceptable. However, a near infrared (IR) sensor employing active targets met the requirements. The sensor has a nominal 75° conical field-of-view and a range from 0.1 to 18.0 m. For the single target mode, nominal range accuracy was 4.3% at a distance of 3.56 m. Correction algorithms were generated reducing the error to 0.6%. Airborne dust testing showed less than 0.8% accuracy (worst case) degradation at levels exceeding (by a factor of 7.5) concentrations permitted by Federal law. The sensor can track multiple active targets providing five degrees-of-freedom (DOF) measurements. Using four targets, the nominal range accuracy was 0.4% without correction algorithms. A guidance system for the haulage system to follow the mining machine does not exist commer¬cially. Such a system can reduce fatalities and injuries by current haulage mining equipment, and is a viable alternative to current haulage control.

Characterisation of Manganese Ores

Sep 13, 2010

By John D. Bardill

A cooperative project between the Bureau of Mines, Department of the Interior, and the Montana School of Mines, investigating results of hydraulic systems for transporting sand slurries for emplacement, was begun in August 1955. In such circumstances, the Bureau provides funds for a fellowship leading to a Master of Science degree as well as available instruments, tools, supplies and equipment. The School provides the ore-beneficiating laboratory with its equipment for use as a pilot plant. The success of a hydraulic backfilling method employing mill tailings depends largely upon the physical characteristics of the tailings. One of these characteristics is size distribution, especially in the finer size ranges. When being emplaced underground, almost impervious layers of slimes separate from some types of mill tailings containing a high percentage of slimes and settle on the top of the sand fill. These coatings may be so dense that the water in the slurry cannot percolate through them for proper drainage. Successive layers of fill in a stope, each with an impervious coating on top, sometimes build up a hydrostatic head, creating pressure on the bulkheads. This may cause breaks in the lining material, inducing sand runs and flooding the level and sumps below. Deleterious slimes flocculated and disseminated throughout the sands should help prevent the formation of impervious slime layers, increasing percolation and settling rates.

Jan 1, 1960

By Stephen A. Gasiorowski, Frank J. Hrach, James D. Bittner

Separation Technologies, LLC (ST) has developed a processing system based on triboelectric charging and electrostatic separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. The environmentally friendly process can eliminate wet processing and required drying of the final material. The process requires little if any pre-treatment of the material other than grinding and operates at high capacity - up to 40 tonnes per hour by a compact machine. Energy consumption is low, approximately 1 kWh/tonne of material processed. Since the only potential emission of the process is dust, permitting is typically relatively easy. In contrast to the other available electrostatic separation processes that are typically limited to particles greater than 75 µm in size, the ST belt separator is ideally suited for separation of very fine (<1 µm) to moderately coarse (500 µm) materials with very high throughputs. The triboelectric particle charging is effective for a wide range of materials and only requires particle-particle contact. The small gap, high electric field, counter-current flow, vigorous particle-particle agitation and self-cleaning action of the belt on the electrodes are the critical features of the ST separator. The high efficiency multi-stage separation through charging / recharging and internal recycle results in far superior separations and is effective on fine materials that cannot be separated at all by the conventional electrostatic techniques. Since 1995, this triboelectric process has been extensively used for the beneficiation of coal fly ash with eighteen separators in place and over 100 machine-years of operation at locations in North America and Europe. The technology has been also successfully applied to the beneficiation of a variety of minerals including calcium carbonates, talc, and potash.

Jan 1, 2012

By Sangseom Jeong, Moonkyung Chung, Junyoung Ko

"Abstract The plugging effect of open-ended piles in sandy soil is analyzed by full-scale field test and plugging measurement. PLR (plug length ratio) measurement data from 144 field cases are analyzed with pile diameter. Based on the plugging measurements, PLR of open-ended piles which have above 1000mm diameter is predicted to be above 0.9. Through plugging measurements, a new empirical method is suggested for quantifying the plugging effect of open-ended piles. The proposed PLR equation is possible to predict the behavior of soil plug in the preliminary design stage. In addition, in order to investigate the behavior of the soil plug of open-ended pile, field load tests are performed on instrumented three piles driven into sand. It is obtained that the resistance components of open-ended pile are separated by double-walled pile system. It is found that inner shaft capacity is developed nearby pile tip. However, upper soil plug did not influence the inner shaft capacity. Also, it is found that all test piles are floating piles and unplugged condition because the sum of inner shaft capacity and outer shaft capacity is calculated about 58 to 76% of the ultimate bearing capacity.INTRODUCTIONIn Korea, a number of huge construction projects such as harbor terminals, offshore grand bridges, and lifeline systems are progress in urban and costal area. In these areas, steel pipe piles are frequently used to support high-rise buildings and heavy weight structures for ensuring structural safety rather than serviceability limit capacity. Also, steel pipe piles are frequently used in civil engineering structures because they have many advantages such as high-load bearing capacity, light weight and outstanding workability. The mega foundations of grand bridges and high-rise buildings are required in geotechnical engineering. Large diameter driven piles are frequently used in several projects.Many specifications such as API, FHWA and AASHTO have been reported as a design guideline of plugging effect, however , the current design method for plugging effect of steel pipe piles are mainly based on the our knowledge derived from observation of the model test or the small diameter pile load test. Therefore, these specifications have limitation to apply the large diameter steel pipe piles.Much work has been done to study the plugging effect by many researchers. Yamahara (1964) reported that soil plug has been modeled as a thin disk element as shown in Figure 1, since the increment of radial strain of the soil plug can be neglected due to high rigidity of the pile compared to that of the soil plug. Klos and Tejchman (1977) reported that the end bearing capacity of open-ended piles was almost equal to that of a closed-ended pile when penetration depth of pile was above 15times the pile diameters by model tests. Paikowsky and Whitman(1990) reported fundamental studies on mechanism of plugging effect in sand. Paik et al. (2003) reported that empirical relations for plug load capacity, annulus load capacity, and shaft load capacity of open-ended piles are proposed based on the model pile tests. As discussed above, much work has been done in the area of plugging effect. But little work has been done to study the plugging effect by full scale field tests."

Jan 1, 2014

By W. P. Arnott

This paper presents real time photoacoustic measurements of diesel-soot black-carbon (BC or EC) and Dusttrak nephelometer total carbon (TC) concentrations in a Nevada gold mine. Comparisons with time-integrated filter-based measurements of EC and TC accomplished using the NIOSH 5040 method were found to be 50% smaller than the integrated real time measurements. This work was initiated primarily as a demonstration project for the usefulness of photoacoustic instruments in measuring BC in the mine environment. Real time black carbon measurements are very useful for determining miner exposure, for providing feedback in mine ventilation systems, and for quantifying machine specific emission rates to understand the operating conditions for specific machines that produce greatest black carbon concentrations. This paper reports real time measurements of DPM from a loaded and empty hauler as it is operated in a drift with a 12% grade. The photoacoustic instruments were demonstrated to be satisfactory for BC measurements in the mine environment.

Jan 1, 2009

Quantitative seismology is an important tool for investigating mineinduced seismicity and the quantification of the seismic rock mass response. The spatio-temporal interpretation of seismic data within an ever-changing three-dimensional mining environment provides some challenges to the interpretation of the rock mass response. A grid-based approach for the interpretation of spatial variation of the rock mass response provides some benefits compared with approaches based on spatial filters. This paper discusses a grid-based interpretation of seismic data. The basic methods employed in the evaluation of the parameter values through space are discussed and examples of applications to different mine sites given.

Jan 1, 2014

By W. H. Bassett, C. H. Davis

In the commercial annealing of cartridge brass there are four points regarding which definite data are essential. They have to do with the correct interpretation of grain count in its relation to annealing temperature and, incidentally, to Brinell hardness. These points are: 1. The comparison of the grain sizes of two cartridge-brass mixtures: 69 copper, 31 zinc, 0.376-in. (9.5-mm.) gage; and 68 copper, 32 zinc, 0.130-in. (3.3-mm.) gage 2. The comparison of the grain sizes of annealed metal that had previously been reduced by rolling varying amounts; for instance, 20.0, 36.6, 50.9, and 59.1 per cent. 3. The determination of standards for grain sizes on annealed brass of the composition 68 per cent. copper, 32 per cent. zinc and 69 copper, 31 zinc. 4. The comparison of grain size with Brinell hardness on identical samples of annealed metal. In their comprehensive and thorough investigation of the recrystal-lization of cold-worked alpha brass on annealing,l Mathewson and Phillips have discussed the relations between temperature of anneal, degree of deformation, and structural alteration in alpha brass. They have also shown certain comparisons between the ordinary physical properties and the grain size of annealed brass. The purpose of the present investigation is mainly concerned with the grain size of cartridge brass, its relation to Brinell hardness, and the publication of sufficient data to enable those engaged in the inspection of such material to have a correct foundation upon which to work. The first alloy was taken from regular mill stock that had been rolled from 0.580 in. to 0.376 in. (14.7 mm. to 9.5 mm.) gage, a reduction of 35.1 per cent. This bar (No. 1) had the following composition: Copper, 69.20 per cent.; zinc, 30.76 per cent.; lead, 0.02 per cent.; iron, 0.02 per cent. The second alloy was also taken from mill stock of 0.325 in. (8.25 mm.) gage and was rolled as shown in Table 1, in order to get four bars reduced two, four, six, and eight B. & 5. numbers respectively. This second alloy

Jan 1, 1919