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By Narong Thasnanipan

In Bangkok due to the prevailing condition of subsoil (existence of considerably weak stratum at top part) deep-seated large diameter bored piles of over 50 m depth with 0.8 -1.8m in diameter have been mainly used for heavy structures such as high rise buildings, elevated expressways, flyovers and more recently for underground subway stations of the first Bangkok MRTA system. As a part of pre-planned quality assurance regime and retrospective investigation, integrity of the piles are tested to obtain the information with regard to the potential deficiencies of the constructed piles which may have formed during pile construction process or may have been attributed by other activities after construction of the piles. An overview of three commonly used non-destructive tests such as sonic integrity, sonic logging and high strain dynamic load tests on deep-seated piles in Bangkok subsoil is presented in this paper. Advantages and limitations of each integrity test are discussed.

Jan 1, 2004

By P Wood

Loy Yang Power (LYP) owns and operates a 2160 MW brown coal fired, base load power station in the Latrobe Valley, Victoria, Australia (Loy Yang A). It also owns and operates a brown coal mine that supplies fuel to its own power station and a nearby 1000 MW power station owned by International Power (LoyYang B). The mine supplies 32 Mt of coal per annum from an open pit, which is currently about 4 km long by 2 km wide and 180 m deep. LYP has 500 employees and a substantial amount of work is also carried out by contractors and consultants. GHD Pty Ltd(GHD) has been contracted to provide mine planning and earth sciences expertise. GHD is an international professional services company that operates globally in many market sectors including mining, industry and the environment. The company has major offices in Melbourne and also within the Latrobe Valley. This paper sets out the experiences that GHD and LYP have gained in establishing a unique alliance arrangement for GHD to provide a range of mine planning, earth science, dam surveillance and environmental services to LYP. The underlying philosophy of the alliance is to closely align the objectives of the two companies such that GHDÆs recompense for service delivery is proportional to the benefit achieved by LYPÆs business. Quality of service, whole of life costs and risk management are important aspects and are reflected in key performance indicators against which GHDÆs performance is measured. Currently GHD provide 20 000 hours of labour to LYP per annum, which are delivered by up to 120 staff who possess the required diversity of skills. The paper explains how the contract was initially let as a conventional service agreement and explains why the contract was transformed into an alliance. It then illustrates the operation of the alliance with reference to the 2006 work program. The paper concludes with thoughts on how the arrangement can be further developed for the future to the benefit of both parties.

Jan 1, 2006

By George T. Faust

The petrographer engaged in examining the products resulting from the beneficiation of ores and rock minerals is constantly required to develop new means and methods of assaying microscopically the results of such operations. From time to time investigators have published descriptions of apparatus that have aided in solving problems in processes f physical separation. Thus, in 191.9, Coghill and Bonardi 31 published a paper covering the application of the binocular microscope and camera lucida to the microscopic analysis of pulverized ores. Similar work has been published by Schneiderhohn 4/, Schwartz 5/, and Head and his associates6/, 7/, 8/. The present paper goes further and considers application of the polarizing comparison-microscope to problems directly concerned with mineral dressing where it is desirable to compare analogous products, and in addition it suggests new uses in various related fields. This work was conducted under the cooperative agreements of the Southern Experiment Station of the Federal Bureau of Mines and. the University of Alabama.

Jan 1, 1940

By Erin N. Legault-Seguin

The Lac des Iles Mine (LDI) is located approximately 100 km northwest of Thunder Bay, ON. The mine has been in operation since 1993. The initial mine production was 2,300 mtpd and increased to 15,000 mtpd following a mine expansion project that was completed in 2001. Effective Oct. 29, 2008, LDI was shut-down under care and maintenance due to low metal prices. Prior to shutting down, LDI was the only primary PGM deposit in operation in Canada and of the few found globally. The complex geology and physical properties of the deposit causes several challenges for the concentrator. This paper will discuss the solutions to the main challenges of attaining nameplate tonnage and achieve satisfactory Pd recovery and concentrate grades.

May 1, 2009

By Ingvar Janelid

DURING the last ten years, in the effort to save manpower and costs, methods of drilling and blasting in Sweden have changed and developed in a revolutionary manner. These developments have been accompanied by extensive alterations in methods of tunneling and in mining technique. Since the end of the 1940's there has been a 100 pct change-over in Sweden to the use of tungsten carbide tipped drill steel. Both investigations and practical results have shown clearly that a tungsten carbide chisel bit fastened directly on the drill steel is the most economical for Swedish conditions. This applies to drill steel up to the longest size it is practical to handle. In terms of drilling footage, durability of the drill steel and the tungsten carbide bit is generally the same. In this respect, therefore, a detachable bit offers no advantage over integral steel. Transportation of integral steel to the grinding plant, instead of detachable bits only, involves heavier work, but this is counteracted by placing grinding plants closer together or by grinding at the working place itself. The drilling rate with integral steel is higher, the trouble of changing bits is avoided, and the difficulties which always arise with joints are eliminated. At present steel dimensions are usually 7/8 in. with a shank 41/4 in. long, whereas the international standard shank was formerly 31/4 in. The longer shank renders possible a better guide control of the steel and consequently longer life for the rotation chuck and the water-flushing pipe. After extensive experiments and investigations, agreement has been reached in Sweden on certain series of standards, shown in Table I. Other steel dimensions are, of course, available for special purposes. The standard drill-steel set begins with a 34-mm diam and has a length interval of 2 2/3 ft. On the other hand, for ordinary drifting it has been proved more economical to use greater length intervals on the steel, so only one steel change is required for a 61/2-ft round. Moreover, owing to the relatively close hole spacing necessary in a drift round, it has been possible to reduce the diameters of the tungsten carbide bits. This results in faster and cheaper drilling. As shown by the table, the lengths of drill steels for normal drifting are 33/4 ft and 71/2 ft, with 29 and 28-mm diam bits. During the last few years operators have begun to use 3/4-in. drill steel in place of the 7/8-in. drill steel chiefly employed earlier. This is a valuable development in drilling technique, particularly in view of

Jan 1, 1955

By E. L. Rawlins

Systematic leakage surveys of natural-gas transmission lines not only aid in the conservation of gas, but can be made to show direct financial returns of large magnitude. 1. Such surveys reveal the actual leakage from the lines, and indicate repairs to be made in order, to eliminate unnecessary waste. 2. Tests on lines, after repairs are made, show the actual saving that has been accomplished. 3. Tests on newly constructed lines reveal the presence of leakage that should be eliminated before the lines are put into service.

Jan 1, 1926

By Roy S. Nutter

The automation of coal mining must occur in a manner that is economically beneficial to the industry and that enhances the safety of the underground and surface workplaces. The work at WVU over the last five years in applying expert systems and neural network controlled autonomous robotics provides the mining industry with tools that when properly applied should clearly lead to mine-wide management and operational improvements and should also contribute to a higher awareness of safety issues by all work crews. This work includes the development of MMSS (Mine Management Support System) and the detailed development of autonomous robotics utilizing neural networks for mining systems.

Jan 1, 1993

By R. G. Turner, M. G. Hubbard, A. E. Dukler

Gas phase hydrocarbons produced from underground reservoirs will, in many instances, have liquid phase material associated with them, the presence of which can affect the flowing characteristics of the well. Liquids can come from condensation of hydrocarbon gas (condensate) or from interstitial water in the reservoir matrix. In either case, the higher density liquid phase, being essentially discontinuous, must be transported to the surface by the gas. In the event the gas phase does not provide sufficient transport energy to lift the liquids out of the well, the liquids will accumulate in the wellbore. The accumulation of the liquid will impose an additional back pressure on the formation that can significantly affect the production capacity of the well. In low pressure wells the liquid may completely kill the well; and in the higher pressure wells there can occur a variable degree of slugging or churning of the liquids, which can affect calculations used in routine well tests. Specifically, the calculated bottom-hole pressures used in multirate backpressure tests will be erroneous if the well is not removing liquids on a continuous basis, and gas:liquid ratios observed during such a test may not be correct. Several authors1,3,8,14 have suggested methods to determine if the flow rate of a well is sufficient to remove liquid phase material. Vitter14 and Duggan' proposed that wellhead velocities observed in the field would be adequate for keeping wells unloaded. Jones8 and Dukler3 presented analytical treatments resulting in equations for calculating, from physical properties, the minimum necessary flow rate. An analysis of these studies indicates the existence of two proposed physical models for the removal of gas well liquids: (1) liquid film movement along the walls of the pipe and (2) liquid droplets entrained in the high velocity gas core. Although there probably is a continuous exchange of liquid between the gas core and the film, they will be treated separately for the purposes of this study. The development and comparison of these separate models with experimental data will permit the determination of which, if either, is the controlling mechanism for the removal of liquids from gas wells. The Continuous Film Model Liquid phase accumulation on the walls of a conduit during two-phase gas/liquid flow is inevitable due to the impingement of entrained liquid drops and the condensation of vapors. The movement of the liquid on the wall is therefore of interest in the analysis of liquid removal from gas wells. If the annular liquid film must be moved upward along the walls in order to keep a gas well from loading up, then the minimum gas flow rate necessary to accomplish this is of primary interest. The analysis technique used follows Dukler2 and Hewitt5 and involves describing the profile of the velocity of a liquid film moving upward on the inside of a tube. The minimum rate of gas flow required to move the film upward is then calculated.

Jan 1, 1970

The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. Air samples were collected in glass syringes and analyzed by electron-capture gas chromatography. In these studies, the lower limit of detection was about I part per billion by volume (ppb) of SF6 per part of air. Experiments conducted in a Pennsylvania limestone mine showed this technique useful in evaluating the effectiveness of auxiliary fans, measuring low flow velocities, probing the air circulating near a working face region where ventilation appeared to be poor, and estimating volumetric flow rates in airways of large cross-sectional area and having low flow velocities. This technique was also used in a western vein-type metal mine to measure the amount of return air being recirculated into the intake air due to leakage through old stoped areas.

Jan 1, 1974

By R. W. Welker

A technique was developed for sampling and analyzing airborne dusts in diesel-operated, underground, metal, and nonmetal mines. Samples were taken using personal respirable samplers, operated as area samplers, and an 11-stage cascade impactor. Real-time particle size distribution and concentration measurements were made with a quartz crystal micro-balance cascade impactor and a portable electrical aerosol analyzer. The materials characterized were minerals (by XRD), elements (by XRF), particle size distribution and concentration (gravimetrically), and organic constituents (by HPLC). The method was used to characterize dusts generated at the chute pulling operations on the main haulage level of an underground tungsten mine. Analysis showed that respirable dust concentration ranged from 0.8 to 2.3 mg/m3. It consisted of silica (3-7%); organic constituents from diesel exhaust (0.11-0.31 mg/m3 equivalent airborne concentration); and mineral dust (39-100%). The remainder was diesel exhaust particles. It was concluded that size selective sampling may be used to estimate the ratio of diesel exhaust to nondiesel dusts in the respirable fraction.

Jan 1, 1982

By Mark A. Willian

The purpose of this short paper is to present soil profiles and basic soils information for the portion of the I-880 Replacement Project alignment where highway structures are to be built. The information presented here is derived primarily from foundation investigations conducted by the Caltrans Foundation Unit (currently the Structures Foundation Branch, Office of Structural Foundations) and by others under Caltrans direction. The foundation investigation for the I-880 Replacement Project began in May of 1991. The field work was completed in May of 1992 and consisted of 93 rotary sample borings, 11 consolidation sample borings, 6 TEXAM® pressure meter borings, six in-place vane shear borings and 57 electronic cone penetrometer soundings.

Jan 1, 1996

The status of remote sensing data availability in New Zealand is outlined and discussed. Currently, two multispectral remote sensing satellites are providing regular data over New Zealand; aircraft scanner services are available from Australia.; operational radar satellite services are yet to materialise. The advantages and disadvantages of the various data types are compared and contrasted. Some image processing considerations are outlined.

Jan 1, 1993

By Wilfred P. Schmoe

Introduction An integrated oil company has two options in approaching strategic planning. It has to decide whether it is in business for the long-term. I state this in all seriousness. Those who help manage public companies have the responsibility of good stewardship of other people's money. We must decide whether continued investment in our basic business will generate a reasonable rate of return. With a world surplus of petroleum production capacity, and continuing downward pressure on prices, this question should be addressed by all oil companies. And a positive answer is not necessarily a foregone conclusion in all cases. The decision should be made based on proven competence in finding and developing petroleum reserves on a cost-competitive basis with other producers, and on a frank analysis of future prospects. This should include a realistic assessment of the projected rate of return on specific investment projects. If a company did not pass these tests, its strategy could take one of four paths. Diversification First, it could diversify. But recent history suggests that oil companies are not good at managing other businesses. Second, it could seek a buyer for its business at the optimum return for its owners. Third, it could sell its assets on a piecemeal basis. And, fourth, it could adopt a longer-range plan of self-liquidation by living off current recoverable reserves. In other words, by not investing in exploration and development, it could maximize short-term profit and pass the money back to shareholders in the form of dividends. The Conoco component of DuPont has a below-average cost of finding petroleum, a good track record of efficient production, and a full plate of projects that pass the test of return-on-investment. In short, Conoco is in business for the long-term. That fact, in itself, determines at least one key element in strategy. This is to extend the life of the petroleum reserve base while at the same time maintaining maximum efficient rates of production to provide a strong cash flow. A company that is able to maintain a strong reserve base will ultimately see the value of those reserves escalate as world oil supplies tighten. Our planners expect this tightening to occur within the next decade as demand grows and production in non-OPEC areas of the world begins to decline. An exploration program tailored to meet the requirements of reserve replacement and current production should have two basic parts. The first is relatively low-risk exploration in proven oil provinces. This is augmented by

Jan 6, 1985

The Ross Goldfield is a unique gold resource. From its discovery in 1865 there was a growing understanding of the geology of the deposit as mining moved from the surface at Jones Flat in the south to underground extraction at Ross Flat further north. Multiple layers of gold-bearing gravels were penetrated in deep shafts and six rich gold-bearing bottoms were worked. The ultimate bottom on the Old Man Group gravel surface has never been reached either at Jones Flat or at Ross Flat. Mining at Ross Flat was ultimately halted by uncontrollable flooding, by escalating costs and by a shortage of labour during the First World War. Mining at Jones Flat recommenced in the late 1980s and attention has once again been drawn to the potential magnitude of the resource at Ross Flat. Research of historic literature shows that there is potential for a bulk gold grade of 400 mg/m3 in a volume of 82 million cubic metres of gravels which lie in a basin between Jones Flat and north Ross.

Jan 1, 1993

As part of a comprehensive risk analysis which was carried out into the effectiveness of the water barrier between South Deep and Randfontein Estate mines, the potential threat posed by large seismic events was assessed. The study covered several aspects. Firstly, an estimate of the maximum credible earthquake was obtained from a probabilistic analysis of the regional seismicity of the previous 25 years. Allowance was made for ?reservoir-induced? effects by increasing the estimate of the size of the maximum credible earthquake from ML= 5.1 to ML= 5.5. Based on available knowledge of the geological structure, the possibility of such an event occurring in the vicinity of the barrier pillar was estimated. The possibility of substantial damage to the barrier rock mass, resulting as a consequence of a large event, was assessed. The likely damage to the concrete control plugs installed in five tunnels that penetrated the barrier, which might result from a ?near-miss? by the largest possible seismic event or from a ?direct hit? by a smaller event, was also considered. It was concluded that there was a negligibly small possibility that the maximum credible earthquake could occur close enough to the barrier, and in such a manner, as to cause any damage to it or to the plugs in the tunnels passing through it. The possibility of serious plug damage occurring as a result of a ?direct hit? by as maller event was slightly greater, but still sufficiently remote as to be of no practical concern at all.

Jan 1, 2006

By Christopher J. Bise

INTRODUCTION The principal means for transporting men, supplies, and mined material in an underground or surface mine are rail systems, conveyor belt systems, or a combination of the two. Typically, large underground mines use rail haulage from the mining sections to the hoist, with conveyor belts being used within the sections. Small mines use conveyor belts in the mains and sub- mains as well as in the panels. The size and layout of surface mines also contribute to variations in the way these haulage systems are applied. The following sections address the typical problems confronting mining engineers in designing these haul- age systems. For rail, these include rail selection and turnout design, locomotive tractive-effort calculation, and motor sizing. Belt haulage calculations include belt width and speed specifications, tension and take- up requirements, idler spacings, and motor sizing. TRACK LAYOUTS Introduction The adequacy of mine track layouts is dependent upon such factors as rail weight (Table l), suitable ties, a well-drained roadbed, and properly designed curves, grades, and track alignment. As long as the installation conforms to the manufacturer's recommendations, good service can be expected from the rail system. Typically, mining-engineering calculations for rack layouts have dealt almost exclusively with the design of turnouts. As such, the following section provides the necessary information for computing the theoretically correct dimensions of turnouts. Turnout Design Fig. 1 shows a typical turnout with an identification of the component parts. Fig. 2 identifies the variables that are used to determine the turnout dimensions. The formulas that concern the mining engineer are those listed: [ ]

Jan 1, 1986

By Y. Nakata, K. Nagata

Plasma is partially ionized gas composed of ions, electrons and activated elements at high temperature. Some flying ash from incinerated municipal waste is melted to become glass by a transfer-type arc plasma furnace. As the glass is ionic silicate, when an electric current passes through anode to cathode, ions in molten slag electrochemically react with electron in plasma at the surface of molten slag. In case of molten Na2O-SiO2, sodium ions in the molten slag carry electric current and SiO2are reduced to evaporate as SiO gas by electron in plasma. The cases of Ag+in NaNO3-KNO3molten salt and Fe2+in FeO-SiO2slag were examined. The amount of cathodic reaction is larger than that of anodic reaction and not apparently according to the Faraday?s law on the electrochemical reactions.

Jan 1, 2004

By Guy Ervin, Delwin D. Blue, John E. Conley

"INTRODUCTION Extraction of alumina from various materials, such as low-grade bauxite and clay, by means of a lime-soda sinter has been the subject of a number ofinvestigations (1, 2, 3, 4, 5, 7, 9, 10, 11, 12, 13, 16, 17). 5/ in recent years, Although many of the details of these investigations are lacking, it is believed that there is one difficultly that frequently develops under certain conditions, namely, that of thickening or gelation of the slurry formed during extraction of the sinter. If gelation occurs even to a slight extent* Serious mechanical difficulties result, very low liquor recoveries are obtained, and the extraction step becomes virlually inoperable. Under 'favorable conditions, a solid gel is formed which can only be removed from the equipment with great difficulty. At the Eastern Experiment. Station of the Bureau of Mines in College Park, Md., a study of lime-soda processes was begun in November 1941. This work has included studies on low-grade bauxites, kaolin clay, and nodular diasporic clay. Gelation was most serous with kaolin clay and least with diasporic clay. As a part of the Bureau's investigation, a study was made of the effect of the pertinent variables on gelation. The results permit the selection of various sets of conditions at which gelation will not occur. These data are essential to the final selection of optimum conditions for the over-all process."

Aug 1, 1946

By H. Kose

In this research, a model quarry with an annual production capacity of 1 000 000 tonnes has been studied for both pit and hillside quarry cases with constant overall slope angle and variable bench slope angle, considering road grades of 8 per cent and 10 per cent. First, technical requirements have been determined and then the effect of production parameters, such as hole diameter, type of quarrying (pit or hillside) and road grade, on the cost has been investigated to determine bench height. Based on the results, it has been concluded that hole diameter has to be kept large in both pit and hillside quarrying to reduce drilling unit costs. In addition, in order to take advantage of gravity and reduce transportation cost, it has been suggested that bench height and road grade have to be kept high and low respectively in the case of hillside quarrying (downhill transportation) while, in the case of pit quarrying (uphill transportation), bench height and road grade have to be kept low and high respectively, in order to transport the blasted material to a lower height and distance, to save energy, thus decreasing the transport cost. Keywords: Quarry, pit, hillside, road grade, bench height

Jan 1, 2005

By Yumi Nakashima, Setsuo Maeda

Vibration magnitude and frequency of the z-axis vehicle seat are time-variant, which are influenced by not only vehicle vibration characteristics themselves but also road surfaces, speeds and the human body. There is little in the current reporting about evaluating and analyzing automobile seat vibration that focuses on the time-variant. Yaguchi et al.1 has proposed a method to evaluate automobile seat vibration that is based on judgments using a subjective mental state. Their method focuses on the time-variant magnitude of the peak frequency on a power spectrum density. However, their method has no consideration of all the frequency contents of the discomfort, nor comparison between different peak frequency vibrations. Suzuki2 has emphasized that the vehicle vibration should be judged by a series of vibration stimuli to evaluate, because the vehicle vibration is time-variant, which isn’t a matter of the relationship between a single vibration stimulus and a subjective response. He clarified that the human sensation to the vehicle vibration discomfort changes every moment showing the relationship between the frequency-weighted r.m.s. acceleration calculated every 5 seconds and the category judgment to vehicle vibration discomfort every 5 seconds. However, his study doesn’t show what parameter connects to the subjective final judgment to vehicle vibration. Therefore, we applied the method similar to ISO100563 considering the time-variant to the vehicle seat z-axis vibration evaluation. The new method for the vehicle seat vibration considering the time-variant was examined on the hypothesis that the final subjective evaluation must be conducted from the judgment summarizing a series of vibration stimuli. Methods The vibration bench system, which reproduces the movement of a vehicle floor, was used for the experiment with the single-axis (vertical direction) four-post road simulator system, which is usually used for a car, as shown in Fig.1. The experiment was done on the right side of the vibration bench using the floor vibration which was 5.5 minutes, 0.822 m/sec2 (Wk) over the range 0.5-20Hz with 4 male subjects (age ave21.5, SD0.5, weight ave75kg, SD7.91kg, height ave166.8cm, SD5.2cm) and 4 suspension seats. As Fig.2 shows, subjects evaluated the degree of discomfort every 5 seconds to each seat vibration measuring the seat z-axis vibration acceleration. [ ]

Jan 6, 2006