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By O&apos, M. W. Neill

Mini-piles have been found to be a practical, technically correct remedial underpinning method. They can be constructed in limited access areas with very little disruption. Experience indicated that mini-piles installed using a down-the-hole soil displacement hammer would be particularly effective in the "bottomless" Beaumont Clay formations in the Houston, Texas, U.S.A. area. The University of Houston Foundation Testing Facility was ideally suited to perform tests on mini-piles. The availability of extensive geotechnical data and previous pile test results was invaluable in evaluating the mini-pile test data. As expected, the mini-pile test results were consistant with test results from large sized driven piles in the same soil formation.

Jan 1, 1989

By M Armstrong, S J. Coward, A Galli

Mine management is often expected to make rapid evaluation decisions at different stages of projects based on limited and uncertain data. The challenge is exacerbated by having to distil technical complexity into a financial model that is usually designed to produce only one or two key indicators, eg net present value (NPV), internal rate of return (IRR). Mining is a complex environment with many sources of uncertainty ranging from sampling to economics. In order to optimise investment decision-making, an appropriately structured evaluation framework must be utilised. An evaluation framework should be designed to encapsulate and integrate the complexity across the evaluation cycle, ie sampling, resource estimation, mine planning and treatment, and financial and economic modelling. This complexity is diverse and ranges from sampling support, scale effects to understanding the impact of variability, uncertainty and flexibility on operational efficiency and economic viability. These complexities, combined with time and capital constraints, usually do not allow all facets of evaluation to be integrated into the model. The model must strike a balance between simplified estimation techniques and sufficient incorporation of aspects of the project that will make a material difference to the investment decision. This paper demonstrates the impact of the scale of measurement on the valuation of a mineral project. Comparisons are made between global estimation averages using a top-down approach and local estimates using a bottom-up approach. Three sampling campaigns were conducted on a virtual orebody to compare the relative NPV accuracies. Stochastic forward models were run on foreign exchange rates and are compared with the results from a fixed foreign exchange rate model.

Jan 1, 2006

By B S. Utting, W J. Cowie

The alluvial gold industry of New Zealand is based on the placer deposits in Otago and on the West Coast. Production from these since discovery in the 1850s has been an estimated 480 t (15 Moz) of gold. Annual output has expanded continuously since 1980 and is expected to be over 2 t of gold for 1989. Following a historical review, the characteristics of typical operations, which use hydraulic excavators and mobile trommel units are discussed. Descriptions are then given of alluvial activities in Otago and on the West Coast.

Jan 1, 1990

This report describes the development of training materials for the operators of underground mining equipment in the underground metal and nonmetal mining industry. The objective was to determine the effectiveness and acceptability of these training materials and to provide the validated training materials to the industry. Ten modules were developed, based on industry need according to accident frequency, accident severity and exposure to the equipment. The final modules were an average of 20 minutes in length and used slides with synchronized narration on cassette tapes. Testing materials are included for use by the mines.

Jan 1, 1984

By David Norval

The increased tendency to use hydrometallurgy as an extraction step towards final refining following a pyrometallurgical smelting process requires melts which have to be cast and or comminuted which can then be taken up into solution or leached. To generate surface area for optimal leaching, a common process is to granulate and in many cases mill, which is a general practice with friable material with properties associated with higher sulphur, carbon and silicon levels. However, in the case of metallic melts milling can be unfeasible due to the ductility of the granulated particles. Water solidification is capable of producing either fine particles by means of granulation or atomisation. Atomisation however, can produce particles as fine as 40 microns without a milling circuit.

Jan 1, 2005

By J. Kempken, R. Degel, J. Kunze, R. König

The FeNi technology is currently dominated by high-power submerged arc furnaces, often designed as smelter as "two-inline-solution". To achieve the intended high efficiency, state-of-the-art design in good correlation with ores and reductants and an integrated layout of the whole plant is of great importance. An introduction will be given to general aspects in the production FeNi, plus a detailed overview of design principles for large FeNi smelters and finally some examples of innovations and research projects concerning Fe-Ni.

Jan 1, 2007

By Isobel Yeo, Luca Cocchi, Sven Petersen, Nico Augustin, Sean Plunkett, Ingo Klaucke

Exploration for seafloor massive sulfides is currently mainly focused on investigation for active hydrothermal vent fields. However, most of the resource potential is thought to be related to inactive, large deposits that had enough time to accumulate sufficient tonnage. At the same time, ageing of these deposits will ultimately result also in burial acted by either sediments and/or volcanic deposits. We currently lack the technologies to explore for these deposits in a time- and cost-efficient manner. In the fall of 2012 we used a number of AUV-based technologies to explore and image a sulfide occurrence at the Palinuro Volcanic Complex in the Tyrrhenian Sea (Mediterranean Sea; Fig. 1) where sampling and drilling have documented a buried polymetallic barite-pyrite dominated site (Petersen et al., 2014). Sulfide mineralization is here covered by volcaniclastic and pelagic sediments and only red sediment staining and the presence of few tubeworm bushes indicated recent hydrothermal activity - black smoker venting is absent. We used AUVbased high-resolution bathymetry, sidescan sonar imaging, subbottom profiling, as well as magnetics to describe, in a quantitative way, the previously known sulfide-bearing areas as well as to successfully explore for new hydrothermal sites including large chimney structures (Figs. 2). Additionally chemical sensors (CTD, Eh, turbidity) investigated the water column for signs of hydrothermal activity in areas not previously investigated, but at the end, only weak anomalies were found in the southern part of the summit.

Sep 1, 2014

By C MacDonald

There are many technologies available today in terms of fire and life safety in road tunnels. So many in fact that it is becoming more and more difficult for clients and contractors alike to determine what they want and what they need. From a clientÆs perspective, fire and life safety is about protection to its infrastructure and to the public at large. Conversely, the contractor is looking to meet its æfit for purposeÆ or ædeem to complyÆ requirements in the most economic and practicable way. Practices regarding fire and life safety in road tunnels have undergone a degree of transformation during the last decade or more throughout the world. This transformation has largely been driven by a series of catastrophic accidents such as the major fires in Europe including the Mont Blanc Tunnel, Tauern Tunnel, Saint-Gothard Tunnel, and now most recently in the CityLink Tunnels in Melbourne. International guidelines produced by organisations such as the Permanent International Association of Road Congresses (PIARC), the European Union, the International Tunnelling Association (ITA) and the US National Fire Protection Authority (NFPA) now provide clients, owners and designers with the tools required to define and specify the required fire and life safety systems in road tunnels. The majority of these tools are based on risk assessment and risk management. Recent road tunnel projects within Australia, however, have not referred solely to such guidelines. Clients have opted to prescribe different or additional fire and life safety requirements within the projectÆs technical specification documentation (project requirements), leaving designers and contractors with little room to implement alternatives or substitutions. Further, these project requirements are largely dictated by practice established on previous road tunnel projects within Australia. This paper looks at the current international guidelines and practices and undertakes a comparison with the EastLink tunnels in Melbourne and other road tunnels within Australia and makes assessment on whether Australian methods are the most appropriate for clients and contractors alike. Focus is directed to the key elements of fire and life safety such as:traffic envelope, barrier arrangements and emergency walkway provisions;deluge systems;drainage systems;fire rating requirements;tunnel ventilation systems;cross passage provisions;fire safety assessment;critical intelligence systems including help phones, CCTV, incident detection, tunnel signage, etc; andexternal tunnel control systems.

Jan 1, 2008

By D. Fleury

"This paper describes the challenges of mining a sill pillar under various types of paste backfill quality. From 1994 to 2002, Louvicourt mine produced approximately 12,600,000 t grading 3.5% Cu, 1.5% Zn, 27 g/mt Ag, and 0.85 g/mt Au. The mining method is transverse blasthole stoping, mining primary and secondary stopes. The production of this 4,300 t/d operation was accomplished using two mining horizons; from the 655 m level to the 415 m level and from the 860 m level to the 680 m level. The main sill pillar is between the 680 m level and the 655 m level. The second sill pillar is between the 885 m level and the 860 m level representing a quarter of the main sill pillar in size. Since 2002, production has gradually decreased and mining activities are expected to end in mid-2005. The sill pillar production will represent almost 25% of the total mine production. The overall recovery of the sill pillars stopes will be discussed in this paper. To recover the sill pillars, more than 1,500 m of development was planned in or under paste backfill. The first sill pillar stopes under paste backfill were mined out in 2002 with excellent results."

Jan 1, 2005

Under contract from U. S. Bureau of Mines, Harza Engineering Company in cooperation with Eastern Associated Coal Corporation, conducted a ground control study of two mechanized longwall panels at the Federal Number 2 Mine. The mine is located in Northern West Virginia, and the coal is mined from the Pittsburgh Coal Seam. The prime objective of the study was to collect data which will aid in the proper selection of the longwall supports system and to control the entry caving problem. Instruments installed in the mine were borehole pressure cells, convergence recorders, roof sag recorders, horizontal roof strain indicators, differential floor movement systems, and lateral roof and floor movement systems. Instruments installed on the surface, above the instrumented longwall panels, consisted of slope indicator system, vertical bed settlement probe system and shear displacement detecting system. A comprehensive surface subsidence study was conducted in conjunction with the instrumentation. In addition to the instrumentation and monitoring, special tests were conducted to determine the bearing capacity of the roof and floor rocks, in situ modulus of coal, roof and floor rocks, and response of borehole pressure cells to ground stress. Cores of coal measure rocks were collected for the physical property tests. Face observations were made to detect various roof behavior parameters under the different jack setting pressures. This report essentially describes the instrumentation work, special tests and presents the data collected.

Jan 1, 1976

By Reno M. Pappas, Christopher Mark

This report presents results of a U.S. Bureau of Mines study of longwall gob material. The objective of this work was to determine material stiffness properties of the gob for use in numerical models of rock mass response to longwall mining. Photographs of actual mine gob were digitized to obtain approximate particle size gradations of gob material. The gradation curve was shifted down to a lab- oratory scale, and 20 uniaxial compression tests were conducted. Varying the maximum particle size was not found to affect the stress-strain behavior, but changing the gradation appeared to influence the stress-strain behavior. The stress-strain relationship of the simulated gob material was nonlinear, the stress-secant-modulus relationship, was approximately linear, and the stress-tangent-modulus relationship was approximately a second-order polynomial function. Equations were generated from these curves, providing numerical modelers with a means to estimate gob moduli based on the stress level. In addition, the experimental data were statistically evaluated using multiple regression analyses, producing a series of equations to predict the secant and tangent moduli from the given stress level, bulking factor, rock strength, and thickness-to-width shape ratio of the particles.

Jan 1, 1993

Mineral ownership determination is not always straight forward as in many cases the relevant details are not recorded on the latest Land Transfer title held in the local Land Registry Office. To determine mineral ownership can be difficult, time consuming and expensive especially in a confused sector. Non statute minerals can be owned by the Crown, Land Owner or other persons. Statute minerals (Gold, Silver, Petroleum, Uranium) are always owned by the Crown and thus present no problems. In simple terms the only accurate and reliable method of determining the mineral ownership under subject land is to historically search back to the first registration when the land and minerals were definitely intact. Then carefully ascertain from the evidence gathered along the way to the present day whether any legislation or private agreement altered or affected the status quo.

Jan 1, 1998

By M. S. Ellis, D. J. Nichols

In 1999, 1,100 million short tons of coal were produced in the United States, 38 percent from the Northern Rocky Mountains and Great Plains region. This coal has low ash content, and has sulfur content in compliance with Clean Air Act standards (U.S. Statutes at Large, 1990). The National Coal Resource Assessment for this region includes geologic, stratigraphic, palynologic, and geochemical studies and resource calculations for 18 major coal zones in the Powder River, Williston, Green River, Hanna, and Carbon Basins. Calculated resources are 660,000 million short tons. Results of the study are available in U.S. Geological Survey Professional Paper 1625-A (Fort Union Coal Assessment Team, 1999) and Open-File Report 99-376 (Flores and others, 1999) in CD-ROM format.

Jan 1, 2001

By Renaud Adams, Vladimir Salatic

"The El Mochito Mine located in Honduras, Central America, has produced lead, zinc and silver in concentrates since the 1950s. The paper discusses changes made in both lead and zinc circuits to reduce costs while maintaining production during the recent period of low metal prices.The intent of this paper is to show that sometimes thinking “outside the box” is beneficial for progress. Also, in striving for better metallurgical results we should not forget the basics of flotation. Sometimes the latest trends may not be applicable to the ore we are treating and may not meet the operating cost constraints.A major beneficial impact on El Mochito metallurgy was achieved when the overall grind was coarsened, eliminating the significant percentage of slimes. Switching from two parallel twostage grinding circuits to one circuit with three-stage series grinding has resulted in a significant reduction in power and steel consumption. With minor layout/reagent modifications, both lead and zinc circuits gained not only in retention time but as well in producing better grade products.Of course, the challenges are still there; they exist and only with the full support of operational data collection and metallurgical laboratory investigation success can come. That is why, we as professionals, can never stop in trying to make the most of what we have.INTRODUCTIONThe El Mochito Mine is owned by American Pacific Honduras S.A. de C.V. (AMPAC) a subsidiary of Breakwater Resources Ltd. Of Toronto, Canada. The mine is located in western Honduras, approximately 220 kilometers northwest of the capital city, Tegucigalpa and 90 kilometers south of the country’s second largest city, San Pedro Sula. The mine began operating in 1948 and to date has produced more than 19 million tonnes grading 240 g/t Ag, 3.5% Pb and 7.4% Zn. Production in 2005 was 700,190 tonnes grading 87 g/t Ag, 1.85% Pb and 6.61% Zn.Decreasing metal content in the ore followed by the lowest zinc price on the market in the last 15 years (see Figure 1) has reduced the cash flow and endangered to stop the operation."

Jan 1, 2007

By King E. J

Department of Pathology, British Post-graduate Medical School, London:The experiments here recorded were devised and carried -out during the last two years in an attempt to corroborate the important work of Denny, Robson and Irwin (1939) in which they found that experimental silicosis could be prevented by means of metallic aluminum. By causing rabbits to inhale powdered quartz for several months they induced experimental silicosis. These animals then served as controls for comparison with another group which were dusted with a mixture of quartz and aluminum. In the second group silicosis failed to develop.Our experimental procedure was somewhat different. We resorted to intratracheal insufflation instead of simple inhalation, and we used rats instead of rabbits: otherwise the essential features of the original experiments were carefully duplicated.EXPERIMENTAL PROCEDURES.A single dose of dust was delivered into the lungs of each animal. The dust was suspended in a fluid medium and injected by means of a syringe directly into the trachea in known quantity (technique of Kettle and Hilton, 1932). The suspensions were autoclaved before use and were injected with aseptic precautions. Having had a long experience of this technique we employed it with confidence and usually secured a fairly uniform dispersal of dust throughout both lungs. To carry out injections successfully one requires, above all, an even suspension of dust which will flow smoothly and quickly from the syringe. This is not difficult in the case of quartz, for, though it tends to settle out rather quickly, this can be avoided by constantly agitating the suspension. The syringe containing the inoculum may be shaken gently right up to the moment of injection and then emptied quickly to prevent sedimentation. Powdered aluminum is more difficult to handle, for the particles tend to flocculate and are not readily made to disperse evenly in saline, even by violent shaking. For this reason an emulsifying agent may be used to advantage, provided it does not complicate the experiment, a point to be mentioned again presently.THE EXPERIMENTSExperiments with quartz alone: Extensive silicotic lesions were produced in 23 out of 26 rats by the administration of pure quartz dust in doses of from 50 to 200 mg. per rat. The dust was so finely pulverised that the particles averaged about 1-p. in size: none was larger than 5 p. and 99 per cent. were under 2.5 p.Eight of these animals survived for seven months and were then killed...

Jan 1, 1945

By Augustine O. Orumwense, Micheline Boisclair

"The use of stirred mill to complement tumbling mills in grinding fine grained minerals is increasingly becoming an attractive processing option. Parameters such as agitation speed, grinding media type and size, feed pulp density, and grinding time were studied in order to elucidate their impact on stirred milling. Test results showed that the parameters have a profound effect on stirred mill efficiency and operating cost. A comparative test with a tumbling ball mill was also made and the specific energies of both mills in fine grinding were analyzed. A difference of over 40% in energy savings particularly when the product size is smaller than 20 µm was obtained with the stirred mill.INTRODUCTIONIn industrial processes where very fine and ultrafine particles are required such as in chemical, ink, food, paint and lacquer, pulp and paper, plastics, pharmaceutical, metallurgical and ceramic industries, the use of stirred mills for grinding is well established. Mineral processing plants are gradually shifting focus to the use of stirred mills for fine grinding and /or regrinding purposes as the target liberation size gets very small. A number of plants processing finely/sparsely disseminated ores are known to have adopted stirred milling technology for their fine grinding needs (Enderle et al., 1997; Harbort et al., 1999; Gao et al., 2000; Davey, 2003 & 2006; Pease et al., 2006).There are different kinds/designs of stirred mills available on the market but, all can be divided into two sub groups namely fluidized and non-fluidized types. The non-fluidized stirred mills consist of Tower mill, Vertimill, Sala agitated mill (SAM), and ANI-Metprotech (SVM). These mills are characterized by their low-speed and the use of fairly coarse grinding media size, 3 – 20 mm. Hence, they are mostly suitable for relatively coarse grinding application. The fluidized type includes the Isamill, Netzsch mill and Stirred mill detritor (SMD). These mills have a characteristic high agitator speed, use fine grinding media size of 0.5 – 5 mm, and are employed in very fine grinding operations. The superior fine grinding capability of stirred mills is attributable to two main process parameters, which are the use of fine grinding media and a high mill speed."

Jan 1, 2008

The ore, as sent to the sulphide mill, is a mixture, in varying proportions, of oxidized ore from above the 450-ft. level and sulphide ore from above and below (to date mainly from above) that level. The oxidized ore consists essentially of quartz, with varying amounts of kaolin and clayey material which passes into the slime and, in excess, creates a serious problem in settling. Pyrite may be present in small amounts. The gold is free and extremely fine.The ore, classed as sulphide, consists of pyritic material in a quartz gangue. The sulphides have been exposed to weathering, leaching by descending solutions and attack by ascending gases and actual burning. The alteration products occur in widely varying proportions and this variation adds to the difficulties in settling and control of grinding and flotation.Copper Minerals.-Chalcopyrite is the principal copperbearing mineral with smaller and varying amounts of covellite, which is sometimes associated with chalcocite, both these minerals being apparently of secondary origin.Examination of tailing by Dr. Stillwell has revealed all stages between clean chalcopyrite, chalcopyrite tinged with covellite, covellite with residual cores of chalcopyrite and clean covellite.The chalcopyrite is free floating, very few particles of clean chalcopyrite being observed in the tailing from granular flotation. The chief tailing loss is probably as chalcopyrite occurring as small inclusions in pyrite...

Jan 1, 1939

By Stephen R. Iverson, Bill M. Stewart, Michael J. Beus

The U.S. Mine Safety and Health Administration (MSHA) has identified ore pass hazards as a significant safety problem in underground metal mines in the United States injury and fatality data show that many injuries are related to pulling or freeing ore pass chutes and structural failures of control gates and ore pass walls. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are investigating these hazards and developing methods to improve safety during transport of ore and waste. Particle flow analysis methods were used to simulate chute and control gate response to various material loading scenarios. Results from computer models indicate that dynamic impacts from ore and waste rock might be considerably greater than theory predicts. Static and dynamic loads were measured in a laboratory setting using scaled ore (sass mock-ups. Field tests were initiated in an active ore pass to determine actual static and dynamic loads. Field data were compared to computer results and indicated that impact and total static loads were substantially less than the computer model results suggested. Damping factors, normal and shear stiffness, and mass frictional characteristics have a significant effect on particle flow and resulting impact loads.

By A. K. Dikshit, H. R. Murty, S. K. Gupta

This paper deals with the development of environment performance indicators (EPIs) for the steel industry. Environmental performance has become one of the key measures of business success. Emergence of continuing pressure from customers, employees, government and NGOs for environmental performance evaluation (EPE) of industries has led to evolve a framework for the development of sector specific environmental performance indicators. EPIs can be used by steel industry for assessing the continual improvement in environmental perfromance, selecting various eco-friendly options, benchmarking, environmental reporting, technology assessment and dissemination, evaluating environmental impacts and building EPIs based environmental management systems. The objective of this paper is to develop EPIs for steel industry and provide framework for development of environmental performance indicators based environmental management system and its integration with the overall management system. An indepth discussion has been presented concerning identification of EPIs, eavaluation of significance of EPIs, their prioritization and its integration with Environmental Management Systems. A new methodology has been proposed for implementing EPIs based environmental management systems . The material presented is derived in part from PhD studies of Rajesh Kumar Singh.

Jan 1, 2005

By B. G. Tarasov

This paper proposes the further development of a recently identified shear rupture mechanism (fan mechanism) that elucidates a paradoxical feature of hard rocks ? the possibility of shear rupture propagation through a highly confined intact rock mass at shear stresses that can be significantly less than frictional strength. In the fan mechanism, failure is associated with consecutive creation of small slabs (known as ?domino blocks?) from the intact rock in the rupture tip, driven by a fan-shaped domino structure representing the rupture head. The fan head combines such unique features as extremely low shear resistance, self-sustaining stress intensification, and self-unbalancing conditions. Consequently, the failure process caused by the mechanism is inevitably spontaneous and violent. Physical and mathematical models explain unique and paradoxical features of the mechanism, which can be generated in primary ruptures and segmented faults. The fan mechanism provides a novel point of view for understanding the nature of spontaneous failure processes, including shear rupture rockbursts. The process explains, in particular, features of shear rupture rockbursts such as activation at great depths, generation of new shear ruptures in intact rock mass, nucleation of hypocentres at significant distances from the excavation, shear rupture development at low shear stresses, and abnormal rupture violence.

Jan 1, 2014