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By Whittaker B. N, Reddish D. J

The rockbolting method of support is employed widely in several countries in different of mines. Hard rock mines use this method extensively. Soft rock mines, such as coal mines, have employed standing supports (steel sets) as the main method, although some countries such as the U.S.A. and Australia have preferred rockbolting. There is increasing interest in extending the rockbolting method in coal mines. The application of rockbolting techniques in an industry which traditionally has not applied such techniques, has required the development of a systematic design approach. This design approach uses extensive monitoring, to asses the viability of the support system in differing conditions. Currently at a number of new and existing mine developments in the U.K., rockbolting is being successfully applied. Although, inevitably some localised geotechnical problems have been encountered and have needed to be taken into account. The effect of faulting on roadway conditions is discussed in this paper and a design approach has been applied using a numerical analysis method, namely the Finite Element Method. The results presented in the paper serve as a useful guide to roadway support designers, and in particular the role played by different bolts in a range of conditions.

Jan 1, 1992

By C. Montoya

This paper shows, through a case study, the impact of multivariate grade modelling upon mine design and mine planning. A deposit explored by drill holes is considered, in which the grades of five elements (copper, silver, molybdenum, arsenic, and antimony) are of interest. Forty alternative models of the deposit are constructed by fitting the joint correlation structure of the grade variables and using conditional cosimulation. In addition, a reference model, obtained by averaging the alternative models, is also considered. The study shows that the resulting mine design (final pit characteristics and production schedules) is sensitive to the grade model under consideration, and that the design based on the reference model may not be optimal when compared to the alternative models based on cosimulation. However, when assuming a given long-term plan and extraction sequence, the grades and net present value (NPV) calculated on the reference model are unbiased with respect to those calculated on the alternative models with the same extraction sequence. The latter allow assessing the possible dispersion of the actual grades and NPV around their expected values, and are useful for the planner in order to determine the probability of meeting given production targets and of exceeding or falling short of given threshold grades. Additionally, unlike cosimulation, the separate simulation of each grade variable leads to unrealistic resource models and to biased results in mine design and mine planning. This approach should therefore be avoided, unless the grade variables are spatially uncorrelated.

Jan 1, 2012

By K. Kim

INTRODUCTION A thorough evaluation of the geologic material being considered must be conducted to determine the feasibility of constructing a large-scale underground facility in a deep geologic formation. The design and construction of a nuclear waste repository in basalt, due to the unprecedented nature of the project, adds significantly to the need for thoroughness of this evaluation and mandates that geoengineering data and analysis be of the highest quality. The investigations required to collect the data encompass in situ measurements and observations, as well as laboratory and field tests. Mathematical (numerical) models, which are required to predict the long-term performance of the repository structure, must be developed to evaluate rock mass behavior at canister, room, and repository scale and eventual 1 y must be validated through in situ tests and monitoring. The information generated from these geo- mechanics investigations is essential for assessing site suitability and will be utilized in the development of the repository design, the engineered barrier design, and the evaluation of repository performance. The Hanford Site near Richland, Washington is one of nine sites throughout the nation being investigated by the U .S. Department of Energy as a possible location for the first high-level nuclear waste repository in deep geologic formations. The process of site characterization is currently in progress. If the site is nominated by the U.S. Department of Energy, an extensive program will be undertaken, the culmination of which will be a decision on the suitability of the site for waste disposal. There are a mu1titude of elements to the proposed site characterization

Jan 1, 1984

By T. A. Rickard

INTRODUCTORY. THE presentation to the Institute, eight years ago, of the paper of Pošepny on " The Genesis of Ore-Deposits " has borne fruit in much fresh: investigation, as is evidenced, for example, by the group of very valuable papers, by distinguished members" of the United States Geological Survey, read at the Washington meeting-discussions of general principles particularly suggestive to those who are engaged in mining. Pošepny, in the discussion of his famous treatise, said that the present writer seemed to look at every new conception in ore-deposition" from the sole standpoint of its immediate usefulness in mining."* Protesting mildly against " sole " and "immediate," I accept the impeachment. It calls for no defence. THE DEVELOPMENT OF RECENT THEORIES. Given the idea of an underground water-circulation as the chief factor in the deposition of ore, the next step in the inquiry as to the genesis of such deposits is, the endeavor to determine which particular part of the general water-circulation is responsible for the results. Around this question have centered the controversies of a generation, and to these controversies we owe the gradual clarification of our ideas upon the processes of ore-formation. It is unnecessary to sketch here their progress from Werner to Le Conte, who combated in 1883 the extreme views of the lateral-seeretionists, and in 1893 opposed the narrow interpretation of the ascensionist-theory. The generally accepted opinions of to-day are a well-deserved tribute to his philosophic discrimination. Thanks to Prof. Van Hise and Mr. Slichter, whose work he utilizes, we have now arrived at a comprehensive conception

Jan 1, 1902

By Christopher Mark, Anthony T. Iannacchione

Falls of ground continue to be one of the most serious causes of injury to U.S. miners. Of the 256 fatal injuries that occurred in mining between 1996 and 1998, 52 (20%) were caused by falls of ground (Table I). Falls of ground affect some sectors of the mining industry more severely than others. For instance, nearly 40% of the 98 coal mine fatalities between 1996 and 1998 were caused by falls of ground. Underground miners are at much greater risk than surface miners. Nearly half (45 out of 101) of underground mine fatalities were attributed to roof, rib and face falls, while less than 5% of the 155 surface fatalities were caused by falls of highwalls or slopes. Sources of Data All of the injury data examined in this study were derived from MSHA’s Fatal Investigation Reports (www.msha.gov)and the MSHA accident database. Because falls of ground often result in serious injury, MSHA Fatal Alert Bulletins and Fatal Investigation Reports provide a useful snapshot of ground control issues in the mining industry. MSHA requires that mines file a report on every reportable accident that occurs, containing information on the accident’s location, severity, classification, activity, and nature of injury, etc. A short narrative is generally included as well. Accident reports can be searched by many of the above fields. From 1996 to 1998, miners suffered a total of 55,096 injuries, which ranged in severity from death (degree 1) to injuries with no days away from work nor restricted duty (degree 6). Six percent of the total injuries were from falls of ground, including machine accidents where caving rock was coded as the source. As the data in Table II indicate, 98% of all non-fatal fall of ground injuries occurred in underground mines, with underground coal mines accounting for 83% of the total. Table II also shows the distribution non-fatal fall of ground injuries by severity and commodity. The injuries are classified into Lost Time Injuries that resulted in permanent disability (degree 2) or days off work (degrees 3-4), and Injuries Without Lost Time that resulted in no more than restricted duty (degree 5-6). Overall, groundfall injuries appear to be more serious than other types of mining injuries. 65% of all ground fall injuries resulted in lost time compared to 54% of all types of mining injuries.

By W. Keilich

A methodology of subsidence prediction using the Distinct Element code UDEC has been developed as an alternative for subsidence modelling in the Southern Coalfield, New South Wales, Australia. The models have been validated by comparison with empirical results and observed caving behaviour. At this stage, modelling capability is limited to flat lying terrain. It is planned to apply the methodology to areas of high topographical relief to investigate the mechanics of valley closure.

Jan 1, 2006

By P. Barnes

(Read at the Philadelphia Meeting, February, 1878.) IT may be of interest, and perhaps of importance, to the members of the Institute that specific mention should be made in detail of the great value of this method of copying or photographing all kinds of tracings.* Several samples are laid upon the table which may serve as illustrations of the results obtained. Some of these show slight imperfections, depending upon the character of the tracing, and upon the length of the exposure to the light, but it may be clearly seen that even a faint copy would be quite available for actual use. The process is believed to be of French origin, and has been used for many years. Special attention seems to have been directed to it recently, and its great value to engineers appears likely to be fully recognized. The manipulations required are of the simplest possible kind, and are entirely within the skill and comprehension of any office boy who can be trusted to copy a letter in an ordinary press. These particulars may be summarized somewhat thus 1. Provide a flat board as. large as the tracing which is to be copied. 2. Lay on this board two or three thicknesses of common blanket, or its equivalent, to give a slightly yielding backing for the paper. 3. Lay on the blanket the prepared paper with the sensitive side uppermost. 4. Lay on this paper the tracing, smoothing it out as perfectly as possible so as to insure a perfect contact with the paper. 5. Lay on the tracing a plate of clear glass, which should be heavy enough to press the tracing close down upon the paper. Ordinary plate-glass of ill thickness is quite sufficient. 6. Expose the whole to a clear sunlight, by pushing it out on a shelf from an ordinary window, or in any other convenient way, for six to ten minutes. If a clear skylight only can be had, the exposure must be continued for thirty or forty-five minutes, and under a cloudy sky, sixty to ninety minutes may be needed. * The introduction of this process into the United States is due principally to Mr. A. L. Holley, who first drew the attention of American engineers to its simplicity and convenience. Mention was also made of the process at the meeting of the Institute in New York, in February, 1877, by Mr. Ogden Haight.

Jan 1, 1878

By Junius D. Edwards

WHEN Charles Martin Hall invented the electrolytic process for the production of aluminum, one basic requirement was a supply of pure alumina. Now, more than 50 years later, the same requirement still holds, and there are no technical straws in the wind to indicate that this situation is likely to change. Long ago, Aluminum Company of America took a number of steps to see that this country should not face shortages of alumina and aluminum in time of emergency. As one step to this end, the Company developed and used a supply of bauxite in South America in order to conserve dwindling Arkansas reserves. Another, and more a program than a step, was to investigate every type of process that might bear the possibility of utilizing the low-grade ores of aluminum that are more plentiful than bauxite. It is a long story, but the investigation included electric-furnace processes, acid extraction processes and alkaline extraction processes, with or without preliminary furnace and sinter treatments. Some of the processes developed were operated in commercial production. This work has been continuous since the first World War. The turn of the wheel came sooner than was expected when, in 1942, bauxite shipments through the Caribbean became uncertain and hazardous through the operation of submarines. The tremendous requirements of aluminum for the war effort were consuming high-grade bauxite at an alarming rate and a national search for substitutes began. High-grade bauxites, for technical and economic reasons, have been defined as those containing about 7 per cent or less of silica. While bauxite of this grade was limited in amount in the United States, there was in sight a substantially greater volume of low-grade, high-silica bauxite not amenable to economic treatment by the Bayer process, but richer in alumina than the clays or other available low-grade ores. It was at this point, and after several years of intensive research on this particular phase of the problem, that Aluminum Research Laboratories brought to completion the invention of one of its research staff, which made practical the utilization of large reserves of low-grade bauxite in America. BAYER PROCESS The Bayer process has been almost universally used for the 'production of alumina from bauxite. This process, in outline, comprises the digestion of finely ground bauxite in a solution of caustic soda (NaOH) under pressure and at an elevated temperature. Alumina in the bauxite goes into solution as sodium aluminate and the impurities-oxides of iron, titanium and silicon-remain undissolved. The undissolved residue, known as "red mud," from its color, is separated and run to waste. Aluminum hydrate (A1202.3H20) is precipitated from the solution of sodium aluminate, and the liquor containing the caustic soda and some alumina is returned to the process for digesting more bauxite. The aluminum hydrate, after washing, is calcined at a high temperature to produce

Jan 1, 1945

By B. M. Das, F. Claridge, V. K. Garga

Coal, as well as a large part of other minerals in Canada, is produced by surface mining methods. This has resulted in short and long-term accumulation of waste rock in dumps. Two main problems arise from the flow of water through these dumps: stability of dumps and the impact on stream flows. In recent years, a number of mines have started placing waste rock in valleys for general disposal or far constructing mine access road ways. All these have created challenges in the following areas: effective design of dumps and flow-through dams; stability monitoring of the structures; environmental impacts downstream by way of increased amount of fines in suspension, sedimentation, and toxic substances; and long-term status of flow and flood. Similar situations also exist in many civil engineering structures. This paper discusses the status of rock drains and the immediate and future research needs.

Jan 1, 1990

By S. A. Braley

DRAINAGE of acid mine water into surface streams of coal mining areas is one of the most serious problems of stream pollution, since there is no known method that completely prevents its forming and no economically feasible treatment after it has formed. The mine acid problem differs from other pollution hazards because acid production does not end with cessation of mining but actually becomes more evident when pumping is stopped. The acid problem in the Pennsylvania, Ohio, West Virginia, and Kentucky bituminous coal areas of the U. S. began with the first operation in 1761, and the volume of acid discharge today is largely the cumulative result of years of mining. Provided they lie above the drainage area, the oldest mines, now long abandoned, are almost without exception producing acid in the same manner as those now operating or recently abandoned. It is well to consider some of the many procedures that have been used to determine the composition

Jan 1, 1957

By D. T. Peters, C. R. Cupp

Aging of commercial 18 pct Ni maraging steel and of related binary, ternary, and quaternary alloys has been studied by electrical resistivity, X-ray diffrac-tion, and hardness measurements. The aging process is in three stages: 1) recovery of martensite; 2) two precipitation reactions; 3) formation of nickel- rich austenite. The main objective of this work was to discover the nature of the Co-Mu interaction. Addition of cobalt to the Fe-18 pct Ni-5pct Mo alloy results in acceleration of the pvecipitation reaction by increasing the super-sat~lration 0f molybdenum. The cobalt-containing al- loys show no incubation period for the precipitation reaction, but the alloy without cobalt shows an initial slow reaction. These results are interpreted in terms of precipitation on dislocations. At low aging temperatures, the presence of cobalt leads to the appearance of a second type of precipitate which is a particularly effective hardener. Cobalt was found to retard the formation of austenite. Overaging is a combination of classical overaging and the formation of austenite in the structure. he- activation energy for the precipitation reaction determined from resistivity ,measurements is 42.8 kcal per mole and the growth of the precipitate is found to obey at law at high tenzperatures and a tU3 law at low temperatures. HE mechanism of strengthening of the 18 pct Ni maraging steels has been studied extensively since 1962.'-? The strengthening is due to precipitation hardening of the martensitic matrix. The main precipitate is an inter metallic compound involving molybdenum, but there is disagreement about its identity.

Jan 1, 1967

By Robert S. Schecter, Mark P. Walsh, Michael J. Humenick

In recent years in situ leach mining has emerged as a viable technology for the recovery of uranium from strata in South Texas which contain relatively low concentrations of uranium ore. Because the ore bodies lie within ground-water aquifers, a significant determinant in the economics is the requirement that such aquifers be protected from contamination. Since ammonia is one of the constituents of the leach solutions now being field tested, one environmental problem to be resolved is the removal of ammonia at the end of mining. A second related question is the fate of the ammonia which is not removed by the restoration procedure. This paper considers the displacement and migration of ammonium in a flowing electrolyte with concomitant ion exchange. The ion exchange is an important feature since, during the solution mining phase, ammonium saturates the mineral exchange sites and must be removed from these sites. A mathematical model is used to simulate this process and the model is tested against the results of laborator.y experiments. It is found that the simulations are adequate if an appropriate selection of parameters is made. The model is then used to investigate the effect of cation composition and concentration of the restoration medium as well as dispersion on the overall effectiveness of the process. It is concluded that increasing the concentration of monovalent ions in a solution containing a mixture of both monovalent and divalent ions decreases the adsorption selectivity of the divalent ions with respect to all monovalent ions including ammonium. Thus increasing the ionic concentration of a restoration fluid by increasing the concentration of a nonselectively adsorbed (with respect to ammonium) ion may have a very limited benefit.

Jan 1, 1979

By Eamonn F. Maher

Superconductivity is one of the most remarkable scientific phenomena ever investigated. It is the phenomenon whereby some materials exhibit zero resistance to the passage of an electric current when cooled to low temperatures, and requires a quantum mechanical explanation. Four Nobel prizes in physics have been awarded specifically on the subject of superconductivity, with many more enabled by superconducting technology. For example, particle beams are generated in accelerators and manipulated in ?particle beam lines? in the ?Big Physics? projects around the world eg. at CERN, Geneva, leading to major discoveries in fundamental particle physics. Similarly, at the JET Propulsion laboratory near Oxford, U.K, controlled nuclear fusion has been demonstrated, and magnetic containment of plasmas is key. In the chemical and biological sciences high field NMR spectroscopy has become indispensable for examining organic matter, revealing the mysteries of the workings of cells, genetics, and in the development of new polymers and pharmaceuticals. With all these very advanced uses for superconducting magnets, it is easy to forget that superconductivity is big business, not just a scientific curiosity. MRI (Magnetic Resonance Imaging) superconducting magnets, the key component of high resolution body scanners, use approximately half of the world?s superconducting wire ? the other half being mostly used in accelerator magnets. The MRI market is about 3 billion dollars per annum, and one MRI magnet uses 200km of wire. New applications for superconducting magnets are now appearing including ?Catheter steering?, enabling much shorter timescales for life-saving brain tumour removals and ?Functional MRI?, a whole new area in patient diagnostics. Whilst the use of low temperature superconductors (LTS) is now well established commercially in superconducting magnets and niche electronic applications, the application of LTS in electric power distribution and transport has been very limited to date. It is now more than fifteen years since the so-called High Temperature Superconductor (HTS) materials were discovered: these can be operated at liquid nitrogen temperatures rather than liquid helium temperatures. However, materials processing and scale-up issues have prevented their widespread use, and in particular the required price/performance criteria are only beginning to be reached except in certain niche markets. BSCCO (Bismuth Strontium Calcium Copper Oxide) tapes up to one km long are now readily available, and have been demonstrated in high current cables for power distribution networks, but the general consensus is that 1) it is difficult to reduce the price much further because of the silver matrix required and 2) in applications where coils are required eg. motors, generators, transformers etc the properties of BSCCO are rather poor because of the critical current dependence on magnetic field. Magnetic fields are always associated with coils and windings, and such fields are of course fundamental to the operation of all electrical machines. YBCO (Yttrium Barium Copper Oxide) however, has good characteristics in field and for the last few years there has been intensive research and development costing several tens of millions of dollars worldwide into the scale-up of production of so-called ?coated conductor?. This ?second generation? tape can be produced by any of many different film deposition techniques, with more or less success for short lengths, but as yet it is unavailable in lengths more than a few tens of metres.

Oct 1, 2003

By J. T. Winkelmann

The Mineral Park Mine is an open pit copper-molybdenum mine located in northwestern Arizona, approximately twenty miles northwest of Kingman, Arizona. The concentrating facility has been regarded, with the expansion in 2011, as a plant capable of treating fifty thousand short tons of feed per day for the mixture of supergene and hypogene ores available. The grinding circuit consists of two 32? x 14? SAG mills and four 20? x 28? ball mills. As ores became harder with greater depth in the adjacent pit areas, however, the SAG mills became severely throughput limited. The traditional treatment for similar properties is the installation of a recycle pebble crushing circuit. Because the cost of such an installation is quite elevated, and preliminary testing and research was inconclusive regarding the predicted throughput increases, management and technical personnel set out to find another solution to the problem. The result entailed a redesign of SAG lifters/liners and a nearly unique circuit change which was, at best, a difficult step that defied current grinding logic. This paper describes these changes, events leading up to them, and the results.

Feb 23, 2014

By D. G. Krige

The scope and salient features of a general risk-analysis model for the main types of new mining ventures are covered in brief outline. The following special features and their effects on the investment criteria are discussed: - various criteria for viability, - the maximum shortfall of funds, - correlations between the grades of up to five ore constituents and between the corresponding product prices. differential inflation and escalation rates for costs and prices, - the estimation, if relevant, of a pay limit based either on the major product only, or on the two major products jointly, - the likely recovery grades of all the products to be obtained when the ore-body is mined to any such pay limit. - an option to take account of the effect on the pay limit of any negative taxation on marginal ore, - investment analyses in current and real terms for individual groups of investors subscribing for equity and any loan capital on differential terms.

Jan 1, 1979

By A F. Cooper

The northeast-southwest trending ~25 km2 area incorporating Bald Hill is located 18 km northeast of Haast, and 5 - 7 km west of the Alpine Fault in South Westland, New Zealand. The geology consists of Greenland Group greywacke overlain by a Cretaceous-Tertiary sedimentary sequence and fluvio-glacial/marine terrace deposits of Quaternary age. Alluvial gold in Cole Creek, draining west from the summit of Bald Hill, may be derived either from vein mineralisation in basement rocks or from fluvial or marine terraces.   This paper focuses on the potential for in situ gold and base-metal mineralisation in sporadic, siderite-rich quartz veins that cut basement greenschist facies metasediments that have been overprinted by contact metamorphism.   Throughout the area, vein compositions are dominated by quartz and commonly feature zoned plagioclase. Alteration adjacent to veining within the contact aureole is dominated by 1 - 2 mm, coarse grained biotite, with small amounts of sulphide, and is pervaded by abundant siderite veinlets. Outside the aureole, wall rock alteration to veins consists of fine grained chlorite. Trace element XRF analysis has been used to ascertain base metal concentrations within samples of vein and alteration zones collected from throughout the area. Vein and alteration zone mineral assemblages containing <5 per cent sulphide, with low concentrations of As, Cu, Pb and Zn indicate low potential for gold and base-metal mineralisation in the Bald Hill region. Contact metamorphism of Greenland Group basement in the northeast of the region, is likely due to emplacement of a poorly exposed Cr- and Ni- enriched gabbro. The presence of biotite and andalusite in hornfelses indicate contact metamorphism occurred at temperatures >350¦C and at depths <10 km. Widespread vein distribution does not appear to be related to contact metamorphism or gabbro emplacement. Further research is required in order to establish the fluid source from which the veins were precipitated.

Jan 1, 2007

By Hamid Maleki

A novel ground control program has been developed at Plateau Mining Company through five years of geotechnical investigations. The study was initiated to determine the causes for roof stability problems and to develop alternative support and monitoring systems for increased safety and productivity. From systematic roof fall observations, extensive geologic mapping, roof drilling and monitoring ground movements along gate entries of four longwall panels, a sand- stone channel system was detected and shown to impact roof stability. In particular, underlying mudstones up to seven feet thick experienced instability due to differential compaction and load transfer from the gob. Roof bolter operators were trained to report roof lithology for mapping channel positions into the roof and for selective use of longer bolts. This boosted operator morale, and improved ground conditions. Monitoring rates of roof movement is used in these areas for detection of instability and for application of secondary support: This has significantly increased safety and productivity.

Jan 1, 1987

The A J Parker Cooperative Research Centre for Hydrometallurgy has recently been established by a major grant from the Australian Commonwealth Government. The participating institutions in this centre are the CSIRO Division of Mineral Products, Curtin University of Technology, Murdoch University and the Chemistry Centre (WA). The Australian Mineral Industries Research Association is also a partner. Information is presented about the research activities of the Parker Centre, which are focussed on the solid/solution interface. Three research programs have been established in the areas of leaching, precipitation and surface processes (adsorption). The initial projects within these three programs are described. Details are also given of the Centre's education program which include honours degree training, masters and doctoral degrees by research, a masters degree by course work and workshops. The importance of collaboration with industry to the successful operation of the centre is stressed.

Jan 1, 1992

By Vogwill R. I J

The Boddington Gold Mine, operated by Worsley Alumina Pty Ltd, is located about 100 km south of Perth and is one of the largest-producing gold mines in Australia.Multiple open pits are planned and several extend below the water table, through the deeply weathered lateritic profile and into the underlying Archean bedrock. Groundwater related mining problems, such as poor trafficability, wet floor conditions and slope instability began to occur early in 1990.The mine is located within Archean greenstones which are steeply dipping and faulted. Rock types include mafic to felsic volcanics, pyroclastics and sediments. These rocks have been regionally deformed and metamorphosed and are intruded by quartz micro-diorites and post-mineralisation dolerite dykes. Deep weathering has produced a typical oxide profile consisting of laterite, clay and saprolite zones underlain by weathered to fresh bedrock.

Jan 1, 1993

By Markku Virtanen, Pertti Koivistoinen

From the perspective of a large mining company the comminution circuit design is worth keeping within the boundaries of the organisation. The correct circuit design begins from the understanding of the role of grinding. Grinding is a link only in the long "comminution chain," starting from solid rock and ending at the concentrating stage. The final target in comminution is to take a part in the maximization of Net Smelter Return, which goal provides the simultaneous considering of capital costs, operating costs and the economic effect of process results. As a general rule there will be a single crushing stage only, ahead of the grinding process. Grinding does not use any metallic grinding media at all, and there will be fine crushing for critical material in the grinding circuit. Grinding has a minimum two stages, besides, at many concentrators middling products and quite often also tailings are reground.

Jan 1, 1997