Search Documents

By Koichi Kobayashi

Performance-based approach to design of structures including foundations was adopted after enforcement of the revised Building Standard Law in Japan in 2000. The use of piled-raft foundation is favorable for medium-rise buildings in soft ground because of its good performance. In the design of the piled-raft foundation (Architectural Institute of JAPAN2002), vertical load is usually carried by the raft foundation, while the pile is primarily meant to control settlement of the structure. Shaft friction is expected to be larger in a nodular pile(Karkee, et.al., 1998) since it has larger surface area than a straight pile, and such piles are frequently used in piled-raft foundations. Since few structures with piled-raft foundation exist currently, the settlement characteristics of piled-raft foundation have not been fully clarified. To design piled-raft foundations with better confidence, the mechanism of vertical bearing capacity and the spatial distribution of settlement should be clarified, for which the actual behavior of the building-foundation system needs to be evaluated. This paper presents observations of settlement of a building with a piled-raft foundation at a soft ground site. The building is a steel structure covering an area an 766 m2, and consists of two-storey office block and one-storey warehouse block. The filled ground of about 5-m thickness at the ground surface is underlain by approximately 4-m thick alluvial sand layer below which lies about a 17-m thick alluvial clay layer with SPT N-value less than 2. The piles used in the piled-raft foundation are 12-m long nodular piles with nodal diameter of 500 mm (pile shaft diameter is 400 mm). The bored pre-cast piling method (Karkee, et.al., 1998) was used to install the piles. To evaluate the foundation settlement, the method of analysis of three-dimensional frame system, utilized widely in Japan, was adopted in combination with the foundation system. Basic assumptions were: (i) total ground settlement is evaluated as the sum of immediate settlement and consolidation settlement, (ii) immediate settlement is evaluated from the Mindlin?s solution in which strain dependency of shear modulus of soil is considered, (iii) settlement in clayey layers is evaluated by the one-dimensional consolidation theory, and (iv) shear spring between soil and pile shaft is represented by a hyperbolic function. The applicability of the method of analysis was verified by comparison with results of field monitoring of building settlement.

Jan 1, 2006

By C. Sensogut

The phenomenon of spontaneous combustion is one of the major hazards encountered in underground coal mines both from the safety aspects and on economic grounds. Every occurrence, however small, if not tackled effectively in the early stages can develop into open fire, or explosion of gas or coal dust. In terms of economy, even dealing with small incidents may be costly in terms of labour and materials, and in case of a sealing off of a district being necessitated, the loss of face equipment and sterilization of reserves is potentially great. Therefore, expense and effort in prevention and detection of such heating, together with a high state of readiness for dealing with likely event, is completely justified and may be considered as a sound investment. In order to achieve this investment, it may be worth to pinpoint the centre of the fire occurring due to autogenously heating which is supposed to be great assistance to inert it at a least cost and time. Therefore, it is the aim of this work to model the spontaneous combustion in the goaf.

Jan 1, 2002

By S. K. Kawatra, S. J. Ripke, T. C. Eisele

It was determined by the authors that the water that remains in the filter cake after filtration in iron ore concentrators can contain several hundred times greater concentrations of calcium ions and other cations, due to surface chemical effects carrying the ions along with the water. Filter cake from two plants was analyzed. The water retained in samples of magnetite concentrate filter cake in Plant 1 contained 5088 ppm calcium and 5995 ppm magnesium, while the Plant 2 filter cake contained 231 ppm calcium and 119 ppm magnesium. These levels were dramatically elevated compared to the water that was removed from the concentrate by filtration for recycle to the plants (9 ppm calcium/15 ppm magnesium for Plant 1, and 11.9 ppm calcium/9.3 ppm magnesium in Plant 2). In addition to possible effects on agglomeration performance, the presence of these cations also affected the efficiency of filtration. In order to reduce the effects of these cations on filtration in Plant 2, carbon dioxide was injected into the slurry before it entered the filter press. This was found to increase filtration rates by up to 23.7%. Comparison of the results from the two plants shows that the concentrations of cations present in the filter cake will vary greatly from plant to plant, with correspondingly large variations in their effects on plant operations.

Jan 1, 2004

Mine planners must select a single pit for design with the knowledge that the grades on which this selection is made are uncertain. This uncertainty is often ignored through the use of deterministic models of grade. This makes the mine planner?s job simpler but does not necessarily lead to the ?correct? or ?best? selection. Grade uncertainty is typically modelled with conditional simulation which generates multiple possible realisations of grade that are equally probable (or improbable) to occur. Methods for incorporating grade uncertainty into mine planning to date have either been perceived as being too complicated, not accessible or too time consuming. This paper proposes a simple and efficient modelling approach to incorporating conditional simulation into pit optimisation, which would be able to be applied in currently commercially software. An example for Resolute Mining Ltd?s Syama Gold Project in Mali shows the range of ore, grade and value outcomes associated with generating pits through a variety of methods.

Feb 27, 2013

This report describes the new Bureau of Mines Core Repository System (CORES) and presents the methods for selecting, processing, and storing physical samples and descriptive data for future reference by earth scientists. The system preserves splits of chip samples and longitudinally sliced segments of core. A records retrieval system provides for storage of data on microfilm and magnetic tapes and uses the keysort parameters of location and commodity for the identification of data.

Jan 1, 1978

By Dan Brown

A method is outlined for computing the contribution of a micropile group to global stability of a sliding mass. The forces in the micropile are computed in a way which accounts for the effect of soil mass movement on the mobilization of axial and shear forces and which maintains compatibility between shear and axial force as a function of displacement. The method provides a rigorous model to incorporate the pile forces into the stability calculations, including the effect of pile forces on the resultant shear and normal forces at the sliding surface. This paper demonstrates the proposed solution using a simple example slope.

Jan 1, 2007

By P. Bermingham

A new approach to load testing of high capacity piles is presented. The method is mobile, inexpensive, repeatable and non-destructive allowing for multiple pile testing at a single site. A reaction mass is placed over a pressure chamber situated atop the pile to be tested. The test method is significant in that it can produce linearly increasing forces of high magnitude (over 5.0 MN) with durations of up to 80 milliseconds. This represents pulse durations an order of magnitude longer than achieved using a drop hammer. The accelerations the pile undergoes are less than one g, (conventional dynamic methods = 50 to 100 g). These effects combine to produce pile behaviour no longer dominated by the action of stress wave, instead the pile is under high levels of stress through its length during the force input. This is representative of the situation when static loads are applied, thus the method may be considered quasi-static. Further advances introduced with this method are that pile deflection and transmitted force are measured directly by means of a laser beam and load cell. This allows accurate correlation of event load displacement histories without the error associated with zero shift (acceleration integration) or non-homogeneous materials (strain measurement). The load displacement histories emulate those obtained for static load testing.

Jan 1, 1989

By Mark William Withey

"Blasting safety in surface mining is a necessary industrial goal. Proper techniques and disciplinesexercised during the blasting process enhance the probability of achieving that goal.The blasting process is generally a series of repetitive steps performed by all blasting technicians.Because habits formed during this process influence safety, production and cost, proper habitsbecome compulsory."

Jan 1, 1995

The paper deals with the importance of design and of codes of practice in ensuring safe working conditions in mines. The design principles involved in the design process are dealt with, and the importance of a logical design process is emphasized. The links between the requirements for developing a code of practice, embodied in the existing guidelines for the preparation of such a code, and the design principles and process are considered in some detail. Finally, suggestions are included, which may provide improvements to the code and hence, ultimately, lead to further improvement in safe working conditions.

Jan 1, 2004

The paper presents the development of an integrated computer aided design and planning of open cast mining, with the use of object-oriented modelling and geoinformation technologies, on the example of interaction of the subsystems on planning optimisation and freight traffics.

Dec 6, 2010

By M. Kinne

Catalyst preparation/ characterization Slightly modified DP (~Schumacher et al. Catal. Lett. 89, 109, 2003) CeO2 HAS 15 from Rhodia calcined in air for~ 2h BET: ~188m2/g, particles size: 5.7nm (TEM, XRD) + HAuCl4 at pH of 6.5-7, (>95% of the Au was deposited) ? Au/CeO2 (2.6wt% Au, ICP-AES) A new conditioning procedure was applied, including heating at low temperature in N2 and H2/N2 mixtures) Patent DE 10205873A1. Very small Au particles <2nm, for CO oxidation catalyst as Au/TiO2, Au/Fe2O3, and Au/Co2O3 Here Au particles size <3.5nm (XRD) Summary ? CO is nearly exclusively adsorbed on the Au particles ? Positive reaction orders of 0.5 are found for CO and H2O ? Ea= 40kJ/mol ? The catalyst is very active and stable ? During WGS reaction huge amounts of formates are formed and cover the surface ? The activity of the catalyst seems to be correlated with the formate species.

Oct 1, 2003

The prime objective of geometallurgy is to improve the profitability of mines through the use of spatial models of rock properties that have a significant impact on value. Although a key property is the grade of the component of interest, because it directly influences the revenue from saleable material, increasingly attention is being focused on other attributes. These &apos;non-grade&apos; variables may have a less direct, but equally profound impact on value, either by reducing potential revenue (eg lowering recovery, deleterious elements, etc) or increasing mining or treatment costs (eg comminution, grindability, throughput, reagent use, etc). Collectively, these variables have been described as &apos;geometallurgical&apos;. There are three main areas of activity required to realise the value of geometallurgy: 1. acquisition of appropriate data through sampling and measurement, 2. building spatial models of geometallurgical variables, and 3. using these models to optimise value. Each of these is built on the foundation of the preceding step. In building reliable spatial models, it is critical that the amount of error introduced to data by the sampling and measurement processes is understood and quantified, in order that the inherent variability of the component of interest can also be properly understood. Management of the quality of grade variables is now applied (with different levels of diligence and success) across nearly all sectors of the mining industry, not least because of the necessity to adhere to Codes of practice (eg JORC, 2004). The necessity for quality management and at least the broad framework of what to do in practice is reasonably understood by many relevant professionals. There are also a number of tools, including software products, statistical analyses and presentation formats, available for those managing grade data. It is also abundantly clear, that in many cases people have little understanding of why they are doing particular quality control activities, or how to sensibly interpret the results. The same is not true for many geometallurgical variables. In almost all instances the authors have seen, the magnitude of sampling and analytical/measurement error variance embedded in geometallurgical test data is untested and unknown. This is partly because until relatively recently, metallurgical data has mainly been collected for the purpose of process and mill design, with few, expensive tests carried out on &apos;average&apos; samples of the orebody. Increasingly however, there is a move towards collection of much larger data sets from spatially distributed sampling, and thus a growing necessity to understand the errors inherent in both sampling and analysis of these types of variables, and how to manage them. In order to understand how the quality management practices applied to grade variables can be extended to geometallurgical variables, it is essential to understand the theoretical foundation that supports these practices. This requires an analysis of the concepts that underpin the &apos;principles of additivity&apos; (Matheron, 1963), the &apos;theory of sampling&apos; (Gy, 1982, Pitard, 1993), and &apos;statistical process control&apos; (Shewhart, 1930). Relevant concepts are then integrated to form a foundation to develop methods to improve the quality management of geometallurgical variables. Application of this framework will significantly increase the integrity of geometallurgical data, the reliability of geometallurgical models and ultimately the value derived from implementing geometallurgy. This is an ABSTRACT ONLY no paper was prepared for this presentation.

Mar 1, 2010

By R. G. Gürtunca

Over the past century coal miner safety and health has seen tremendous improvements, the fatality and injury rates continue to decrease while productivity continues to increase. Many of the hazards that plagued miners in the past, such as coal bumps, methane and coal dust explosions, ground fall accidents and health issues have been significantly reduced. The contribution of NIOSH research includes products for prevention and survival of mine fires, methane control measures, design procedure for underground coal mines, methods for excavation surface controls, methods and procedures for blasting, laser usage in underground mines and prevention of electrocution from overhead power lines that have reduced accidents and injuries in underground coal mines. Health research has produced products such as the personal dust monitor, noise abating technologies and ergonomic solutions for equipment operators. Research priorities at NIOSH are set by considering surveillance statistics, stakeholder inputs and loss control principles. Future research in coal mining is directed towards respiratory diseases, noise induced hearing loss, repetitive musculoskeletal injuries, traumatic injuries, falls of ground and mine disasters. The recent spate of accidents in coal mines resulted in the Miner Act of 2006 which includes a specific role for NIOSH in future mine safety research and development. The mine safety achievements in the USA reflect the commitment of industry, labour, government and research organizations to improving the safety of the mine worker.

By Wenbing Guo

Strip pillar mining method is one of the most important techniques for mining subsidence control in China. Mining depth is one of the most important factors that affect subsidence in strip pillar mining method. Six numerical simulation models were set up in this paper to simulate surface subsidence of strip pillar mining at different mining depths. The mining depth in these models ranged from 300 to 800 m. The simulated results were compared and analyzed. The results showed that the subsidence factor of strip pillar mining is related to mining depth. While other things being equal, the subsidence factor of strip pillar mining increases logarithmically with increase in mining depth. Their quantitative relationship was established based on the simulated results.

Jan 1, 2007

By R. G. Burdick, W. R. Peters

Shallow underground voids resulting from early coal mining and other resource recovery activities over the past several decades are now being recognized as a significant cause of ground subsidence problems. Uncertain knowledge of abondoned coal mines also imposes potential hazards in current underground mining operations, since water inundation or the release of methane gas is a serious hazard when mine excavation operations break into an abandoned mine. Requirements for detecting and mapping subversive manmade tunnels in previous work has led to the development of a surface-operated automatic earth resistivity survey system and associated computer data reduction process for military applications. Field demonstration tests of this system have resulted in successful detection of tunnels at depth-to-diameter ratios greater than 10 to one. Under the sponsorship of the Bureau of Mines, a similar high-resolution earth resistivity system was designed and constructed for use as a potential means of detecting abandoned coal mine workings. The hardware and software aspects of third new system are described together with applications of the method for surveying and mapping abandoned coal mine workings. Field tests are presented to illustrate the detection of both air-filled and water-filled mine workings.

Jan 1, 1984

By Michelle Mouton, Johanna van Deventer, Jussi Vaarno

Mintek has been involved in numerous projects to remove Fe and Mn from dilute Co sulphate solutions by means of oxidative precipitation using air/SO2. Test work was done using a gas induction system, designed and supplied by Outotec. Various aspects, such as SO2 concentration, SO2 flowrate, impeller rotation speed and pH were investigated on a 2 m3 scale. Batch tests were performed using a residence time of 5 hours. Mintek has been involved in numerous projects to remove Fe and Mn from dilute Co sulphate solutions by means of oxidative precipitation using air/SO2. Test work was done using a gas induction system, designed and supplied by Outotec. Various aspects, such as SO2 concentration, SO2 flowrate, impeller rotation speed and pH were investigated on a 2 m3 scale. Batch tests were performed using a residence time of 5 hours. Impeller rotation speeds of 0-220 rpm were tested, and it seemed that speeds of between 80 and 220 rpm gave similar Fe and Mn removal rates. Co and Cu losses were generally below 1% and 5% respectively at pH 3.

Jan 1, 2007

The underwater test method for the determination of energy content of explosives is a very useful method. It’s also the only one which can separate shock and gas heave energies from each other. The total energy can be determined as a sum of these partial energies. Because of this special feature, the test method can be used to develop the energy content of explosives for different purposes; the military high explosives should contain more shock energy whereas the gas heave energy is a very important feature for the blasting explosives. The goal of this study was to find out the effects of aluminium and sodium perchlorate increments to the shock, gas heave and total energy values of an emulsion explosive and detect the particle size effects of two different aluminium powders to the total and partial energies as well. Both partial energies as well as the total energy were observed to increase linearly as a function of aluminium (A-80) concentration. The fine aluminium powder (A-100) (6%) also seemed to increase the shock energy of the explosive slightly whereas the gas heave energy was observed to remain unchanged to compared to the normally aluminazed (A-80) (6%) emulsion explosive. Therefore the fine aluminium powder also increased the total energy, but only very silightly. The fine aluminium powder can probably take apart to the chemical reactions more easily during the detonation. (3%) of sodium perchlorate (NaClO4) mixed with (6%) of (A-80) aluminium powdered emulsion explosive was observed to effect to the gas heave energy content of the explosive, but only very slightly. The shock energy was observed to remain unchanged.

Jan 1, 2005

By G. H. Lind

This paper discusses the traditional costing approach currently used in the underground coal mining industry. Activity Based Costing (ABC) is identified as being a potentially more effective manner in which to cost underground coal mining systems. With the use of a costing framework developed by the author incorporating new thinking to eliminate the shortcomings identified in the traditional costing approach, a comparison of two types of underground coal mining systems, viz. continuous miner and longwall, is conducted. It is found that under certain criteria, in all cases, irrespective of the way in which the systems are costed, the continuous miner system is currently the better investment. It is also observed that when a system is costed using ABC that better investment decisions result when compared to costing the same system using traditional costing techniques. It is further seen that traditional costing techniques tend to overestimate the total costs of a mining system. This paper shows one application of ABC that can be incorporated as a management tool.

Jan 1, 2001

Mineral liberation data are routinely obtained for a wide variety of applications, including ore characterization and characterization of various metallurgical test products obtained in bench-scale laboratory testwork. Newmont Mining Corporation owns several properties in the Carlin Trend containing refractory gold ores. These ores are generally difficult to treat and have to undergo several processing stages for gold recovery. At Carlin?s Mill 5 operation, flotation is used to pre-concentrate some of these difficult ores to produce a sulfide concentrate to feed the roaster. It is of interest from a flotation perspective to be able to study the floatability of pyrite, arsenopyrite and arsenian pyrite, since these minerals all have different quantities of gold associated with them, and have to be recovered to ensure a successful separation has been achieved. In this paper, a detailed MLA study on several Carlin ores was undertaken on samples from flotation tests, using air or nitrogen as flotation gas, specifically to study the differences in floatability characteristics, which ultimately impacts overall gold recovery. I

Jan 1, 2009

By Stephen J. Roberts

Gold catalysts were prepared on co-precipitated, calcined copper oxide - zinc oxide support by an inverse deposition-precipitation method. These catalysts were characterised by X-ray diffraction (XRD) and temperature-programmed reduction (TPR) and studied for CO oxidation activity at various catalyst calcination temperatures. TPR studies of the support material exhibited a double peak and shift to lower temperatures for the reduction of Cux+ to metallic copper, as opposed to the single reduction peak for pure CuO. This phenomenon is possibly caused by an interaction with the zinc oxide. The addition of gold to the support CuOZnO led to a further shift in copper reducibility to lower temperatures. Gold present in the initial uncalcined catalyst as Au3+ was auto-reduced to Au0 under various calcination temperatures. The Au3+ reduction peak was observed to shift to lower temperatures with increasing calcination temperature. The catalytic activity was found to pass through a minimum value with respect to calcination temperature. Catalysts with both gold in entirely the 3+ or metallic oxidation state were found to exhibit high activity. Furthermore, the catalysts were found to decrease in activity with decreasing Au3+ content up to an intermediate calcination temperature, afterwhich the activity increased sharply. Possibly at higher temperatures, a stronger Au-support interaction is formed, leading to a new active site.

Oct 1, 2003