Search Documents

By P. Marinos, G. Tsiambaos, H. Saroglou

Anisotropy is a characteristic of intact foliated metamorphic rocks (slates, gneisses, phyllites, schists). ?esting was used to establish the anisotropic behaviour of selected gneissic rocks. The effect of anisotropy on various mechanical properties (strength, deformation) and dynamic properties (wave velocity) was examined. The rock samples were also tested at successively higher confining pressures in order to evaluate the effect of anisotropic behaviour at high overburden pressures. L’ anisotropie characterise les roches foliées (schistes, gneiss, phyllades). Dans ce travail des essais en laboratoire ont été exécutés afin de déterminer le comportement anisotropique des roches gneissiques. L’ effet de l’anisotropie a été examiné par rapport aux propriétés méchaniques (résistance, deformation) et propriétés dynamiques (vélocité ultrasonique). En outre des essais des roches ont été exécutés a des compressions latérales successivement plus grandes afin de déterminer le comportement des roches sous grands charges. Anisotropie ist eine Eigenschaft der geschieferten Gesteine (TonSchiefer, Gneis, Phyllit, Marmor). Versuche wurden durchgeführt, um anisotrope Verhalten von gneis Gesteinen zu ermitteln. Der Einfluss von Anisotropie auf mechanische (Festigkeit, Dehnung) und dynamische Eigenschaften (Wellegeschwindigkeit) wurde bestimmt. Die Dreiaxialversuche wurden unter grossem allseitigen Drücken entnommen, um das anisotrope Verhalten auf grösse herrschende Spannung zu bestimmen.

Jan 1, 2003

By Norman A. Jull

"Factors which affect the separation achieved in a hydrocyclone are discussed and illustrated with graphs of some mathematical relationships.Definitions of separation and sharpness include comment on use of elutriation devices.A plea is made for better evaluation of field data prior to their reporting or use in calculations. Methods of evaluation are suggested, with samples of the relevant calculations.An example of the effect of percent solids errors is given, with computer printout and plotted corrected recoveries.INTRODUCTIONThe range of interest in cyclones runs from a simple demand for classification results to a detailed study of published equations defining cyclone characteristics. Probably this group covers as broad a range and, in an attempt to offer something for everyone, I will begin with general operating comments, then move on to more analytical topics. Ideally, an author would compose his paper after the discussion period, when he would have a better idea of the areas of special interest to his audience.Sor'1e of you may share our incurable fascination with classification, especially as performed in cyclones. It is amazing that such a simple device could be in use for more than 20 years and retain as much mystery as it does. Substantial parts of the mystery have been solved but some remains, to keep up our curiosity. There is at least one valid reason: the unusual compactness of this device, which makes internal observation very difficult. What other unit can you think of which performs such a complex separation between particle sizes, shapes and specific gravities at such high capacity? Retention time in a cyclone is typically 3 seconds!Mutual Agreement - In a cyclone, every parameter of geometry and of operation interacts with every other. In an orderly discussion of individual parameters it would be necessary to repeat, in every section, 11 if all other factors are equal"". Could we agree now, for our mutual convenience, that that phrase is clearly understood between us during the remainder of this paper?"

Jan 1, 1972

By D. R. Wilburn

The worldwide budget for nonferrous, nonfuel mineral exploration was expected to increase by 58 percent in 2004 from the 2003 budget, according to Metals Economics Group (MEG) of Halifax, Nova Scotia. The increase comes two years after a five-year period of declining spending for mineral exploration (1998 to2002). Figures suggest a subsequent 27 percent increase in budgeted expenditures from 2002 to 2003. For the second consecutive year, all regional exploration budget estimates were anticipated to increase. The worldwide budget for gold exploration achieved about 50 percent of the total amount budgeted in 2004.This was 68 percent, or US$715 million, higher than the reported 2003 budget. The 2004 worldwide exploration budget estimates for copper increased by 70 percent, orUS$237 million, to US$577 million from the 2003 budget. The budget for nickel exploration increased 52 percent, or US$89 million more than in 2003. The 2004 exploration budget for other mineral targets (primarily cobalt, heavy minerals, industrial minerals and silver) increased114 percent, or US$118 million.

Jan 1, 2005

Due to the ongoing restructuring of the mining industry in central Europe with a continuous decline of the number of large underground mines and collieries, and a simultaneous decline of staff numbers in the remaining mines, the established mine rescue schemes are endangered to collapse. With the end of the mine rehabilitation at Wismut Uranium in 2014, the last remaining major mine rescue teams in Saxony, providing basic mine rescue services for all other mines in the region, will disappear. This will leave a large number of small mines and other underground operations without capable mine rescue support. Since none of these companies is able to set up a complete mines rescue unit on its own, new ways have to be found. Among others, a central mine rescue team for central Germany as well as the assistance by special trained professional fire fighters or mine rescue teams from abroad are discussed. Problems like location of the central rescue team, financing, communication and transport have to be solved. This paper provides an overview over the complexity of the problem as an example for other mining regions worldwide and will discuss national and cross-national strategies.

Feb 23, 2014

By F. J. McMulkin

This paper, the 1965 Airey Memorial Lecture, reviews the world-wide technical advances in iron and steelmaking, and offers an appraisal of the new techniques which will be applied in the future. After a review of blast furnace operations, the continuous steelmaking process is described, and the resulting techniques of degassing and continuous casting are discussed at length. Pressure pouring, hot rolling, cold rolling and coating practices are also outlined, and considerable space is devoted to the direct reduction process. Finally, the application of the computer to steelmaking operations is discussed in some detail.

Jan 1, 1966

By J. J. Beresford

The primary function of a support slurry is to provide stability during excavation. Today foundation structures can be designed around the additional friction afforded by the absence of the filter cake attributable to the use of polymeric fluids as support slurries. These fluids use pseudoplastic fluid viscosity to advantage over the fragile thixotropic gel structures of bentonite. Many of today's polymeric fluids are environmentally acceptable for disposal directly to municipal sewers.

Jan 1, 1989

By David Mitchell, Daan Delport, Frik Marx, Mike Shapiro

The use of copper cooling elements to enhance refractory lining life in pyrometallurgical vessels is common in modern furnace design. Copper elements typically incorporate a base panel with cast in cooling passages and an integral extended surface (formed of pins, fins or similar) onto which suitable refractory material is cast. The metallic, conducting parts are located towards the cold face of the lining, with the refractory material interposing between the coolers and the process. The coolers are designed to arrest wear of the refractory material by freezing a layer of slag or partially reacted material onto the hot face, thereby rendering the lining inert to further attack [1]. These coolers have achieved success in new furnaces and relining of existing vessels. The freeze layer is prone to mechanical damage during operational and process instability. The coolers must be capable of extracting the additional heat flux under upset conditions to facilitate rapid self-repair of the freeze layer and prevent further refractory wear in the intermittently exposed areas. However, operational experience has shown that the high heat flux capabilities of the copper coolers have some disadvantages, especially in processes producing vapours which form corrosive compounds when condensing onto the cold surfaces of the coolers. When corrosive conditions develop, the entire composite will fail due to loss of structural integrity, and as a result of leaks from the cooling water passages. This paper describes recent developments in the approach to the design and manufacture of copper cooler panels customized to achieve specified heat fluxes and temperature profiles, thereby reducing the formation of corrosion mechanisms in applications with corrosive gaseous environments and enhancing refractory lining life. Condensation formation prevention is achieved by adjusting the geometry of the cooler and selection of suitable materials of construction.

Jan 1, 2007

By Steve Dubnewych

The Joint Water Pollution Control Plant, operated by the Sanitation Districts of Los Angeles County, treats wastewater generated by over three million people. A new tunnel and ocean outfall is being considered to meet future hydraulic demands and provide long-term redundancy for the Districts? existing tunnels, portions of which were constructed as early as the 1930s. The detailed process used to evaluate the feasibility of various tunnel and out-fall locations is described. Challenges include a geologic profile with mixed face and squeezing ground conditions; high water pressures; active fault crossings; gassy and contaminated ground conditions; and liquefaction, slope stability, and lateral spreading concerns in the area of the riser and diffusers.

By Stephen C. Tadolini, Thomas M. Barczak, Paul McKelvey

A new generation of hydraulic mine support prestressing devices has been developed. These thin-walled steel shells are machine-welded and can be inflated with water or any liquid to provide prestressing for a wide variety of roof support products ranging from Can supports to props and cable bolts. With an expansion capability of several inches, depending on the geometry and size of the unit, they can also establish roof contact eliminating the need for wooden wedges or crib blocks that are commonly employed with several standing roof support products. Capable of withstanding pressures from 1,000 to 6,000 psi, these cells are able to transfer roof loading into the support structure without rupturing. A recent development has been the addition of an inexpensive yield valve that provides control of the maximum pressure and load development on the support. This paper examines the performance capabilities of these inflatable prestressing units and the impact they have on the performance of various support systems, including an evaluation of the overall stiffness of the support system and the load control during yielding of the prestressing unit. Recommendations are made regarding the design requirements of the prestressing unit to optimize the support performance. A summary of mine applications using this technology is provided with general comments regarding their impact on ground control.

By H. C. van Zyl

Mine water in the Upper Olifants River Catchment in Mpumalanga(upstream of Loskop Dam) is at times discharged into local streams, resulting in local acidification and regional salination of surface water resources. Pollution of surface water can be prevented by collecting and treating mine water to a quality where it could be re-used without restriction (Cleanwater 2020 Initiative). Mine water in the Olifants River Catchment currently amounts to only 4,6% of the total water usage, but contributes 78,4% of the sulphate load. Limestone and lime treatment is the most cost-effective technology for neutralization and partial sulphate removal of acidic/sulphate-rich water to sulphate levels of less than 1500 mg/l due to precipitation of magnesium and removal of the associated sulphate fraction (through gypsum crystallization). Neutralized mine water of this quality may be suitable for irrigation. A number of alternative desalination treatment technologies were investigated (subsequent to gypsum crystallization pre-treatment) where treated mine water must meet more stringent quality requirements (e.g. less than 200 mg/lSO4). The capital cost of these processes varied between R4 million/(Ml/d) and R10million/(Ml/d) and the running cost between R2/m3and R5/m3. Water usage in the Upper Olifants River Catchment currently amounts to 947 Ml/d (including the power stations), and will increase to an estimated 1385 Ml/d by 2020. The additional water demand by2020 (438 Ml/d) will have to be supplied by importation from neighbouring catchments, and more efficient utilization of the local water resources, including excess mine water. Various levels of treatment are required to make mine water suitable for the following potential applications (acceptable treated water sulphate concentration shown in brackets): irrigation (2000 mg/l), coal processing plant (1000 mg/l), general industrial use (500 mg/l), discharge to public streams (500 mg/l), potable use (200 mg/l) and cooling water in power stations (20 to 40 mg/l). The following two options, or a combination thereof, can be considered for management of excess mine water in the Upper Olifants River Catchment: ?Collection and treatment of excess mine water to a quality suitable for selected urban and industrial applications (Option A) ?Collection and treatment of mine water to a quality suitable for irrigation (Option B). The estimated capital and running cost for Option A amounts to R528.5 million and R55.7 million/year, respectively, compared with R68,2 million and R11,9 million/year for Option B. It is recommended that Option B be investigated for implementation in the short to medium-term. Option B was selected due to cost benefits and the initial favourable results obtained by a joint Water Research Commission and Coal Industry initiative where mine water is used for irrigation. Option A may become feasible in the long-term to ensure maximum environ-mental protection and reduced treatment cost as a result of anticipated technological improvements over the next 5 to 10 years.

Jan 1, 2001

By R. G. Shen

The relation curve of strain and acceleration is presented in this paper. The steel pipe pile of 609.6 mm in external diameter driven by IDH-45 diesel motor hammer on the esturial shoal of Yangtze River. The ultimate bearing capacity of pile is analyzed by one dimensional wave equation and the effect of computational parameters of the equation is discussed.

Jan 1, 2010

By Ahmad Ghahremaninezhad, Denver H. Cowan

Much of today’s gold is locked within sulphide minerals. These sulphide minerals, including pyrite, need to be subjected to oxidative pre-treatment in order to leach the refractory-gold using traditional methods. Typically autoclaves employing high temperatures between 180?225 ºC, and extremely high pressures between 1,500?3,200 kPa, are used for the oxidative pre-treatment. However, the autoclaves themselves are very expensive, costly to operate and maintain, and produce excess sulphuric acid. This paper studies the atmospheric oxidation of pyrite in ferric sulphate solutions. In general, pyrite oxidation under atmospheric pressure can result in high elemental sulphur production, i.e. less acid generation. Activated carbon has displayed an ability to catalyze the process, achieving reasonable kinetics. The reaction kinetics were investigated by altering acidity of the leaching solution, temperature, catalyst ratio, sparged oxygen and agitation. A combination of X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray fluorescence, inductively coupled plasma mass spectrometry (ICP-MS), and atomic absorption spectroscopy (AAS) were used to monitor the kinetics of the process and elemental sulphur yield. The purpose of this investigation was to determine optimal operating conditions that maximized kinetics of the atmospheric oxidation while maximizing elemental sulphur yield.

Jan 1, 2015

By Georgy Cherkashov, Svetlana Babaeva, Tamara Stepanova, Firstova. Anna

Seafloor massive sulfides (SMS) study in the Russian Exploration Area at the northern equatorial Mid Atlantic Ridge began after signing the contract with International Seabed Authority in 2012. In order to evaluate the SMS resources in the course of exploration the major and rare metals with economic value should be determined. The evaluation is based on geochemistry and mineralogy and particularly on the type of rare metals occurrence in the SMS. As a case study research of the Semyenov cluster of SMS deposits have been conducted.

Sep 1, 2014

By Baruch Grinbaum, Edwin Bwalya, Robert Minango, Deogratias Bukunkwe

Solvent extraction of Cu from acidic leach, using an oxime extractant, e.g. LIX 984 or Acorga is a well known and established process. As the process advances, Cu is extracted to the solvent and is replaced by H+ in the aqueous phase. At high acidity the distribution coefficient of Cu between the solvent and the aqueous phase decreases, and eventually relatively high concentration of Cu remains in the raffinate, regardless of the number of equilibrium stages. In many processes this phenomenon is immaterial, as the raffinate returns to the leaching and no copper is lost. But when the copper raffinate is used for processing of additional metals, minimal concentration of Cu in the raffinate is essential for an effective process. The recommended process includes three steps: 1. SX-1: Standard extraction of Cu with oxime. The resulting raffinate contains about 6-8 g/L Cu and 50 g/L H2SO4. 2. SX-N: Extraction of most of the acid into an amine-based solvent, and stripping it with a base, e.g. aqueous ammonia, caustic, Na2CO3 etc. The extraction removes no metals, but decreases the concentration of acid from 50 to 10 g/L. 3. SX-2: Extraction of the neutralized solution once more with oxime, to remove the residual copper. Such a process enables one to get down to 100-150 ppm Cu in the final raffinate. This process was developed and tested in the R&D facility in Chambishi Metals plc, by a joint team of Chambishi & Bateman, using Cognis LIX 984N and real solutions from the plant. In the laboratory scale, the equilibrium isotherms for SX-1, SX-2 and the neutralization were developed. Computer simulation of the results showed that the optimal configuration is two stages for both extraction and stripping for SX-1. For SX-2 2-3 stages of extraction and two stages of stripping are needed. The stripping stages may be common to both SX-1 and SX-2. The neutralization of SX1 raffinate was tested both by conventional precipitation with lime and by extraction with Alamine based solvent extraction and stripping with a solution of 10% NaOH. For the SX-N only one stage was needed for both the extraction and stripping. The bench scale pilot plant was run for both SX-1 & SX-2. The results were very similar to the simulated ones, and the configuration of 2E2S for SX-1 and 3E=2S for SX-2 delivered the required raffinate with less than 150 ppm Cu.

Jan 1, 2005

Jan 1, 1961

By Andrew Allan

[The Thompson Creek Coal and Coke Corporation, a. mall company engaged in producing coal in the Rocky Mountains of Colorado, is currently engaged in a struggle of destiny to increase their production from inclined seam operation to compete with highly mechanized horizontal bed mines. This paper introduces some of the problems encountered it pitch seam mining as they apply to the convention, room and pillar system employed at the present time. Further described is the test work now being conducted to overcome these obstacles with an. attendant increase in productivity. Included in this test work is a mining machine designed especially for pitching seams, an automated longwall, and hydraulic mining of the latter compared with those of conventional work presently employed.]

Jan 1, 1965

By Michael S. Zhdanov

One of the major problems of mineral exploration is the ability to reliably distinguish between uneconomic mineral deposits and economic mineralization. While the mining industry uses many geophysical methods to locate the mineral deposits, until recently, there was no reliable technology for mineral resources identification and characterization. The main goal of this project is to develop a new geophysical technique for subsurface material characterization, mineral exploration and mineral discrimination, based on electromagnetic methods. The proposed new technique is based on examining the spectral induced polarization effects in electromagnetic data using the modern distributed acquisition systems and advanced methods of 3-D modeling and inversion. The recovered parameters of the relaxation model will be used for the discrimination of different rocks, and in this way will provide an ability to distinguish between uneconomic mineral deposits and zones of economic mineralization using geophysical remote sensing technology (Zonge, 1976). The proposed research and development is undertaken using multi-partner collaboration between the University of Utah, four major mining companies, Kennecott Exploration, BHP Billiton World Exploration Inc., Placer Dome Inc., Phelps Dodge Exploration, and Zonge Engineering Inc., which is equipment manufacturer and service provider to the mining industry. The multi-partner collaboration between the academic institution, the University of Utah, and mining industry helps to identify the appropriate mining target and conduct the field experiment for practical demonstration of the developed new technology, which is an important part of the this project.

Jan 1, 2005

By Z. G. Lin

In Xian, China, compaction by means of soil (or lime-soil) piles is one of the effective methods widely used for densifying loess and eliminating its collapsibility. However, as a result of groundwater table rising, it is no longer applicable in many areas. This paper is the summary of the first-time use in Xian of sand-gravel compaction piles aimed at densifying the miscellaneous fill (already partially under water) and saturated loess at a certain project site. In-situ tests, conducted before and after the treatment and including several kinds of penetration tests backed up and confirmed by a set of plate loading tests, yielded very satisfactory results, strongly testifying to the viability of the method.

Jan 1, 2010

By Harvey W. Parker

The underground industry is challenged by many complex technical and non-technical issues and risks. The most obvious of these are the traditional technical issues that we usually try to address with risk management techniques. However, there are many other non-technical risks that our projects face on a daily basis which we often fail to fully recognize or appreciate. This paper addresses some of the less-technical broad-based risks in order to put them into perspective with the technical risks we face day to day in underground planning, design and construction. The good news is that Risk Management techniques are not always about bad things. For obvious reasons Risk Management is always thought of in terms of the ?downside? of risk (i.e., the identification and mitigation of things that can go wrong). On the contrary, there is an ?upside? of things that might go better than expected. Fortunately, if a deliberate effort is made, the same principles and techniques that our industry uses in Risk Management can be applied toward identifying and quantifying the Opportunities and Benefits that might occur. In this way, the process of conducting risk management programs can not only identify the downside risk but can be used to identify and direct projects to take advantage of the upside of uncertainty (i.e., Opportunities as they arise). This beneficial aspect of risk management programs will be highlighted in this paper together with the importance of the non-technical issues.

Jan 1, 2008

Collaboration between education providers is the key to long-term sustainability and improved quality in mining education. The mining industry is now, more than ever, an industry doing business on a global basis. Staff are recruited by global mining companies in many different countries and can find themselves deployed anywhere in the world. The mining engineer of tomorrow must be willing to take on this international challenge, and must be educated to a level where he or she has a comprehensive grounding in technical aspects of mining engineering, but also a well-founded appreciation of management, social, environmental and cultural issues that may be encountered around the world. In order to deliver such an education, academic providers must collaborate at both a national and international level. This paper provides an overview of progress that has been made in Australia through the national joint venture ? Min¬ing Education Australia (MEA). Supported by the mining industry in Australia, through the Minerals Council of Australia (MCA), MEA has been operational since 2007 and is seeing the development of a range of innovative courses and delivery methods, together with a high level of staff cooperation across the country. MEA has also commenced some international teaching initiatives that are seen as a catalyst for a far greater degree of international collaboration in the future. Such activity is not only to the benefit of the students who are taught by experts from around the world, but it also ensures that individual univer¬sity programs remain viable in terms of staffing numbers and financial performance. The paper also presents some statistics on recent upward trends in mining engineering student numbers from around the world, in response to the global shortage of mining engineers.

Jan 2, 2010