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By C. S. Chenga

Sustainable development is currently an extremely relevant concept worldwide, especially in developing countries like South Africa. Mining and metals companies are also directly affected by the sustainable development agenda. The Mining Charter?s requirements as well as new legislation (Mineral and Petroleum Resources Development Act) expect, among others, for mines to support infrastructure and poverty eradication projects in the communities surrounding the mines. The aim of this paper is to, against the background of a qualitative study of mining communities in the North-West Province of South Africa, put forward some critical factors for the sustainability of social development projects in the mining sector.

Jan 1, 2006

ALTHOUGH the development of the various flotation processes during the last 8 years has been so revolutionary, this development has been, until recently, entirely confined to the separation of the gangue from the mixed metalliferous sulphides.The desirability of finding some method of separating the independent sulphides from such a miXture, by means of flotation, has long been recognized. ThIS need was emphasized when the slimes resulting from the grinding of Broken Hill sulphide ores were for the first time successfully dealt with by the Mineral Separation Company's process on the Central mine. This process proved the practicability of separating the sulphides of lead and zinc as a mixed concentrate from the gangue present in slime. Although this was a very notable achievement, the process has not been generally used, owing to the mixed lead and zinc concentrates resulting from the treatment being acceptable neither to the zinc nor the lead smelters.Although the introduction of eucalyptus oil in minute quantities as an emulsifying agent has simplified the work of the subsequent tabling of mixed sulphide concentrates, rendering unnecessary the burning off or removal of the oil, there will always be a considerable quantity of slimy product too fine to settle on the moving surface of the concentrating machines, and therefore requiring other means for its division into lead and zinc concentrates.

Jan 1, 1912

By W. J. Kingwell

My comments and questions are addressed to Mr. Troughton. It seems to me that the tests were very well tailored to determine long term effects on performance of bearing piles as groundwater pressures rise in the London Basin. This rise is being simulated by means of a groundwater recharge system but it would be informative to have further details of the controls of conditions simulated. Ideally the porewater pressure in Standpipes 1, 2 and 3 should be the same throughout the test. Under test conditions are there not practical dif­ficulties? Recharge Well C2 is a lesser dis­tance from the pile than the other wells. Was the rate of recharge to C2 regulated to a lesser rate than the other three? In my experience the rate of acceptance usually varies from well to well. Under a common feed pressure were mea­sures taken to compensate for this? Since the problem does not only affect London, but also Liverpool, Nottingham, Birmingham and to a lesser extent, Manchester, I question whether an ideal procedure is being used. It is well known that rates of acceptance decrease with time and often recharge wells need to be flushed out at regular intervals. Other pro­cedures may need to be adopted to accurately simulate the effect of groundwater rise, if tests of longer duration are to be considered.

Jan 1, 1991

By M. Somerville, S. Sun

The liquidus temperature and viscosity of a range of melter slags produced in South Africa were determined. Drop-quench experiments were carried out on the supplied plant samples to determine the liquidus temperature and phase relations at sub-liquidus temperatures. The temperature measurement range covered 1300°C to 1630°C. Results from these experiments show liquidus temperatures for the melter slags to be in excess of 1500ºC with the chromium containing spinel as the primary crystalline phase. At lower temperatures, an olivine or pyroxene phase co-existed with the spinel phase. The viscosity of the slags was determined over a temperature range of 1350 to 1550°C, under a controlled atmosphere. Results show two orders of magnitude variation in the viscosity (0.2 to 20Pa s) with strong effects of slag chemistry and temperature. Slags with lower SiO2and Cr2O3concentrations were more fluid. Slags with the lowest FeOx and highest SiO2concentrations were the most viscous. These observations are in accord with general behaviour of silicate slags. While the presence of a spinel phase may have an effect on the viscosity of the melter slags, results obtained to date indicate a much stronger effect due to the presence of an olivine or pyroxene phase at lower temperatures. Keywords: phase equilibria, liquidus, viscosity, slags, olivine, spinel, pyroxene

Jan 1, 2004

Studies of the Main Seam in the Rapahoe Sector of Greymouth Coalfield have shown that the proportions of palynomorphs and palynomorph groups vary vertically within the seam, but remain laterally consistent. Subsequent examinations of other seams in the Rapahoe Sector have demonstrated that the changes in palynomorph proportions observed in the Main Seam are specific to that seam, effectively providing a seam 'fingerprint'. Such a characteristic signature may be used to identify the Main Seam where faulting or seam splitting confuses seam correlation between drillhole intersections. Palynomorph assemblages are derived from the original plants which formed the peat mire, and yield information on mire conditions such as climate, mineral matter input and chemistry. These depositional factors influence coal properties such as mineral content, volatile matter yields and coal breakability. Palynological data can therefore assist in development of depositional lTIodels for prediction of coal quality variations. Several other, thiner seams in the Rapahoe Sector have been demonstrated to also contain recognisable palynomorph assemblages, suggesting that other seams may also possess distinct palynomorph abundance profiles.

Jan 1, 1996

This Bureau of Mines publication consists of an overview of the mine waste management research currently being conducted by the Bureau. The following papers, given at a Technology Transfer Workshop, emphasize the increasing importance of research related to the safety and environmental considerations of mine waste disposal In recent years. Current work related to legislation passed in the last 10 years and their subsequent standards includes the development of adequate monitoring systems, development of stability and seepage prediction and control techniques, control of runoff water, and control of leaching solutions. Selected topics are included here that cover coal mine waste disposal, embankment slope stability monitoring, flow failures of mine tailings impoundments, and controlled burnout of abandoned coal mine fires. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By G. A. Harrison

The introduction of extra low profile (XLP) mechanized equipment within Anglo Platinum is aligned with the overall New Mining Technologies strategy to focus on continuing modernization of our mining operations` incorporating injury-free production and cost-effective mining technologies. The method allows for the introduction of a suite of ultra-low profile equipment in narrow reef (1.2 m) stoping operations. For the first time it is now possible to achieve total trackless mechanization at these widths and indications are that XLP mining has the potential to add more value when benchmarked with conventional mining and low profile (1.8 m) room and pillar methods. Various mine layouts were tested at different sites within Anglo Platinum and the XLP breast mining layout proved to be the most effective. This paper describes the results of the trials at Waterval Shaft and concludes with recommendations on our future strategy on implementation of XLP technology within Anglo Platinum.

Jan 1, 2006

By David Norval

Ni, Co, Cu and Pt, mattes are common materials that require granulating and milling of the resultant granules for further processing. This route is acceptable if the material is brittle (friable) which is a property associated with the higher sulphur mattes. For lower sulphur levels, where the matte is less amenable to milling, the costs of the milling increases. This paper will compare water granulation with certain dry granulation processes and the downstream processes required for Hydrometallurgy. It will further introduce and expand on atomisation which offers a further safety benefit in the control of the metal flow into the 'wet zone' with the use of a tundish flow control also reducing the conversion from the matte to powder in one fairly straightforward operation.

Jan 1, 2006

By Don Rose

INTRODUCTION A number of tunnels supported and permanently lined by steel-fiber-reinforced shotcrete (SFRS) have been built in North America in the 1980s. The material is more economical than, and technically equal or superior to, conventional shotcrete using wire mesh. The design and construction of SFRS-lined tunnels is straightforward, and only a few new design principles, laboratory tests or construction equipment modifications appear necessary in order to use this material. Modern tunnel Contractors may use cyclic drill-and-blast methods on some tunnels, with intermittent shotcreting as part of an orderly cycle. The Dry Mix method is most suitable for cyclic, intermittent, relatively small-scale shotcreting. However, modern Contractors excavating tunnels continuously using large long Tunnel Boring Machines (TBMs) or Roadheaders may prefer Wet Mix shotcreting on a mass production basis. In either case, the use of steel-fiber-rein¬forced shotcrete (SFRS) promotes the rapid and economical excavation of tunnels. The addition of microsilica will improve SFRS properties and reduce rebound, and is expected to become standard practice with SFRS in North America, as it now is in Scandinavia. HISTORICAL REVIEW Steel-fiber-reinforced shotcrete (SFRS) at the present time (1985) is essentially conventional shotcrete with straight or deformed steel fibers added, and in general SFRS for tunnel linings encounters the same problems that conventional shotcrete does. Shotcrete history is well known. The use of sprayed plaster on wire frames for mounting animal skins by Carl Akeley of the Smithsonian

Jan 1, 1985

By M. Jeffrey

This study investigated the elution of precious and toxic metals from activated carbon. Gold and mercury are of primary interest, due to their value and environmental impact respectively. A laboratory elution rig was commissioned to simulate industrial Zadra and AARL carbon elution conditions. Mercury was found to elute most effectively in strong caustic cyanide solutions; gold was found to elute most effectively in hot low ionic strength solutions. As cyanide decomposes on contact with activated carbon at high temperatures, optimum elution conditions for gold conflicts with those for mercury?no practical compromise in conditions was found. However, sequential elution allowed reasonable recovery of both metals. Ongoing work is looking at the deportment of other metals under elution conditions.

Jan 1, 2009

By B. J. Kloppers, J. V. Z. Visser, C. J. Horn

"The long-term plan (LTP) in a mineral resource company is defined by the quality of the mineral resource and represents the result of a series of trade-offs to fulfil internal organizational as well as external business and legislative requirements, ensuring ultimate delivery on the defined organizational strategy.The LTP should as a whole align to a coherent and well-defined organizational strategy, working towards a clearly defined objective while still allowing a tactical response to short-term requirements of the organization. The ability to respond tactically to changes in environment, like the unprecedented five-month strike in 2014 on the platinum belt following the 2012 Marikana incident, is a measure of the flexibility of the plan given the agreed strategy.This paper describes the Lonmin process of linking company strategy with long-term planning, tactical planning, and the execution of the plan through an annual planning cycle to maximize organizational flexibility. This flexibility enables mining companies to respond to the many internal and external forces that impact on both strategy formulation and delivery of results that meet shareholder expectations."

Jan 1, 2015

By Rixon K. L

Hargraves (1983) has reviewed the phenomenon of instantaneous outbursts of coal and gas with special attention to Australian occurrences. The purpose of this discussion is to highlight some problems and omissions in his review that reflect particularly on the authors' structural geological investigations of outburst-prone coal seams.It is surprising to find that much of the authors' reported work has either been glossed over or the results distorted by Hargraves (1983) and it is, therefore, important to clarify the contribution that structural analysis of coal seams can make.For many years it has been known that faults provided preferred loci for gas outbursts (for example, Briggs 1920-21) but the roie that faults played in outburstprone seams was unclear. The present authors reviewed the association of faults and outbursts drawing upon local investigations and the world-wide literature (Shepherd et aI., 1981), and discussed some wideranging aspects that result from the high coincidence of faults and outburst sites. Without repeating large segments of this article the authors will discuss four aspects of coal seam faulting and fracturing.

Jan 1, 1983

By Brigitte J. Dejou

The Red Dog sediment-hosted zinc-lead deposit is located in the Brooks Range thrust belt in northwest Alaska, approximately 1000 km northwest of Anchorage. The mine constitutes the primary deposit in a 400 square kilometre district, which hosts several other mineral occurrences. All the known mineralisation is hosted by the Mississippian Ikalukrok Member, deep basinal shale of the Kuna Formation, part of a Devonian to Cretaceous sedimentary sequence. The rocks underwent intense deformation during the Brookian Orogeny in Middle Cretaceous time. Several thrust faults juxtapose the stratigraphy. The Red Dog mine is composed of four deposits which together contain 105 Mt in resources and reserves for a total resource exceeding 18 Mt of Zn metal. The mine is an open pit with 25 foot high benches. The biggest challenge is not the Arctic conditions, but metal extraction, due to the fine grained nature of the mineralisation and the variability of the ore. The mine produces Zn and Pb-Ag concentrates that are shipped to smelters around the world from the Red Dog port facilities during the short summer period. Ore mineralogy is generally simple and consists of sphalerite, pyrite, galena and marcasite. The deposits are generally overlain by decametre thick exhalative barite horizons and exhibit strong silicification, which locally obliterates the original textures. Although described as a world class Sedex-type deposit, a large portion of the mineralisation exhibits sub-surface replacement textures. Moreover, unlike most other Sedex deposits, the reconstruction of the basin is made difficult by the structural complexity of the district. To assist exploration in the district, several assumptions are made regarding the deposit settings relative to metal source, growth faults or crustal extension.

May 1, 2006

The development of 3D multi-parametric models facilitate the provision of resource information well in advance of the mining face. Using the model, one can evaluate mining areas not only for grade and tonnage predictions but also for predictions of rock mass quality. Blast design and milling requirements can be derived from the rock mass quality predictions. This information can be used for overall mine planning and evaluation, costing, production optimization and slope design. This allows the full range of mining activities and costs to be interconnected, thereby lowering costs and improving efficiencies through the application of the multi-parametric model. Feasibility studies for new projects require an expected budget expenditure estimate to within 5% of actual costs. This level of accuracy is expected by mining companies and investors but cannot be achieved without a sound knowledge of the rock mass variability. By developing a 3D multi-parametric model as part of the feasibility study and using the same geological model exploration boreholes, a significantly better understanding of the rock mass conditions can be obtained. This rock mass information can be used for equipment selection, economic pit layouts, processing plant design, underground mining layouts and support requirements, to name but a few design parameters that depend on rock mass conditions. The initiative at Anglo Platinums, Potgietersrust Platinum Ltd.?s (PPRust) operation, has delivered significant results showing improvements across the mine to mill value chain. These include increased loading rates, reduced electricity and crushing consumables, as well as higher plant throughput. The ore reserve model has gained international acceptance as an invaluable tool for a mining operation. Certainly most financial organizations will not invest in a mining project that does not have an ore reserve model. There is the potential for multi-parametric models to be recognized as vital tools in the mining process, as is the case with ore reserve models.

Jan 1, 2007

By Art Carino

"The McClean Lake operation is located in the Eastern Shore of the Athabasca Basin in northern Saskatchewan some 700-air kilometers north of Saskatoon. It is operated by Cogema Resources Inc., the major share holder of the joint venture consisting of Cogema Resources Inc., Denison Mines Limited and OURD, a consortium of Japanese utilities.The JEB mill is the first uranium mill to be constructed and licensed in North America within the last 15 years. The mill uses conventional uranium unit process but employs innovative techniques unique to the JEB mill.This paper presents brief descriptions of the various unit processes, the innovations and the commissioning strategies developed to achieve the designed production capacity in the shortest possible time.INTRODUCTIONThe McClean Lake ore body was discovered in 1979, followed by the discovery of the JEB ore body in 1982. From 1985 to 1990, a cluster of deposits named Sue A, Sue B and Sue C were discovered. Environmental Impact Assessment (EIS) of the McClean Lake project began in 1990 under a joint federal-provincial process. Following the public hearings in 1993, the governments gave approval to proceed with the construction of the project, subject to fulfilling licensing requirements.The McClean Lake ores are located in the uranium-rich geological region of Saskatchewan known as the Athabasca Basin, 700 air kilometers north of Saskatoon. The JEB mill is located near the mined out JEB open pit that is now used as the tailing depository.The approved mill has a production capacity of 6,000,000 pounds of U3O8 annually and is capable and licensed to process JEB, Sue A, Sue B, Sue C, McClean Lake, and Midwest Lake deposits. Although the EIS has been approved, Mining of the Midwest Lake deposit has not been approved at this time."

Jan 1, 2001

By Tracy Brettmann

In recent years the Augered Cast-In-Place (ACIP) Pile industry has seen a substantial increase in the quality control options available to Contractors, Engineers, and Owners. Quality control methods range from the simple, manual techniques that have been used for years to new computerized installation monitoring equipment and nondestructive testing methods. Our ability to monitor and test ACIP piles has grown to such a degree that the industry is struggling to determine how much quality control is enough. This paper reviews the many options available and describes the pros and cons of each. The various nondestructive testing methods, in particular, have been difficult to apply reliably due to misapplications of methods and misinterpretation of the results. ACIP piles have unique properties that require the various nondestructive testing methods available be considered very carefully in determining the method most appropriate for a particular use. Some nondestructive testing methods, as well as automated monitoring equipment, potentially can be applied effectively to increase the level of quality control for ACIP piles. The experience gained on real projects using these new methods, in conjunction with the old procedures, provides valuable information for future applications.

Jan 1, 2000

By Paul J. Axtell

Self-hardening cement-bentontie (c-b) slurry walls were constructed as shear walls to stabilize the downstream slope of Tuttle Creek Dam near Manhattan, Kansas. The slope stabilization was required to protect the existing pressure relief well system located at the downstream toe of the dam. The wells require protection from slope deformation induced by liquefaction of the foundation sands during or immediately after the design seismic event. The shear walls are transverse to the axis of the dam, unreinforced, and relatively brittle members that may be exposed to relatively large shear strains, and possible cracking, during or immediately after shaking. An extensive laboratory investigation was conducted on recovered core samples to optimize the mix design and stabilization scheme. Furthermore, as is the topic of this paper, a portion of the laboratory investigation was to determine the large-strain, or post-peak, shear strength of the c-b material for use in limit-equilibrium slope stability analyses and numerical deformation modeling to assess the magnitude of permanent deformation caused by the design earthquake. These data may be beneficial to other projects that are considering the use of unreinforced c-b slurry walls for seismic retrofit purposes.

Jan 1, 2010

Minerals are fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels?mining, processing and manufacturing finished products. The estimated growth rate for the real GDP of the United States was 2.1 percent and the nominal GDP was about $13.8 trillion in 2007 (Table 1). The prime interest rate decreased to 7.25 percent in December from 8.25 percent at the beginning of 2007, reflecting actions taken by the Federal Reserve Board to counter financial difficulties surrounding subprime mort-gages. Delinquencies on subprime mortgages increased throughout the year, affecting not only the delinquent home owners but also financial instruments invested in mortgage-backed securities. The average contract mortgage rate for the purchase of previously occupied homes in the United States was 6.35 percent in November; a slight decrease from 6.37 percent in January but still greater than 5.34 percent reported in July 2003, the lowest rate in the past five years. With the tightening of credit, the seasonally adjusted annualized rate for new privately owned housing starts declined 27 percent from December 2006 to November 2007. The loss in the residential market was balanced by a 9-percent increase in nonresidential construction between January and August 2007, during which slight increases occurred in nearly all

Jan 1, 2008

By Larry G. Stolarczyk

Jan 1, 1980

By H. T. Chiwaye

Risk analysis is an important step in the design of rock slopes in open pit mining. Risk is defined as the product of the probability of slope failure and the consequences of the failure, and is generally evaluated in terms of safety and economic risk. Most of the risk analysis done at present is based on the use of limit equilibrium (LE) techniques in evaluating the probability of failure (POF) of the slopes. The approach typically makes use of full Monte Carlo simulations of the limit equilibrium models, with all uncertain variables randomly varied. The number of required simulations is generally over a thousand, at times as high as 20 000, in order to produce statistically valid results of the POF. Such an approach is clearly not practical when using numerical modelling programs dueto the high computational effort required. This paper explores the impact of using numerical modelling instead of the traditional LE techniques in evaluating the probability of slope failure. The difference in the overall assessed risk, in terms of economic impact, for the mining operation is then evaluated. With numerical models, approximate methods are used in the calculation of the probability of failure instead of full Monte Carlo simulations. This paper will use a method called the response surface methodology (RSM) for estimating the POF from numerical analyses. Simple slope models were used to verify the accuracy of the RSM method by comparing the results with those obtained from full Monte Carlo simulations. It is shown that there is good agreement between the POF values computed using full Monte Carlo simulation and those obtained using the RSM method. Finally, the use of numerical modelling in the assessment of risk is shown to bring a significant difference in the result compared with that from LE methods. One of the reasons for the difference is that LE models tend to underestimate the failure volumes and hence the consequences of slope failure.

Jan 1, 2010