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By M. J. Little

Potgietersrust Platinums Ltd (PPRust) is Anglo Platinum?s only open pit operation. The major slope stability concern at PPRust is rapid, small-scale brittle failure on the west wall of Sandsloot open pit. In order to improve safety and mine more economically, a comprehensive slope monitoring strategy has been implemented. In the last 3 years four new state-of-the-art monitoring systems have been installed namely an ISSI microseismic monitoring system, a GeoMoS automated prism monitoring system, prismless Riegl laser scanners and a GroundProbe slope stability radar (SSR). Groundwater monitoring and visual monitoring have also been improved over the same time period. To complement the visual inspections, SiroVision digital photogrammetry is now used for predicting where future failures may occur. All these monitoring tools provide primary monitoring which is used to identify high risk areas. The SSR is then set up in that area to provide early warning of failure so evacuation can be successfully done. Fault tree analysis has proved that with this comprehensive slope monitoring strategy the geotechnical risk at PPRust is greatly reduced, allowing mining to continue safely and economically in challenging conditions.

Jan 1, 2006

By Christoph Miller

About 80 years ago the mining industry saw an advertisement of a machine manufacturer: ?One man ? one machine?, meaning the productivity gain by using a pneumatic rock drill instead of manual tools. Mechanization in mining had started. In the 1950's and 1960's when mechanization progressed the word could be transformed into the meaning of ?one man ? one drill rig?. During the 80's automatic functions were added to the machines. Automation started. In the 90's, the first autonomous machines were seen, transforming the advertisement from the 1920's into ?one man ? multiple machines? operated from a remote control room. Soon, the productivity gain achieved by pure automation will also be flating out meaning that the margin cost of further productivity gain will be inefficiently high. What next? In mining operations there is still a high potential of unused productivity lost by ?trivial? things like organization, logistics and operational management. Changing the focus from mechanization and automation towards optimizing the overall mining process will unleash another big potential for cost cuttings and for enhancing efficiency of production. Optimizing an overall process is a task of much higher total complexity compared to an isolated machine automation focus. And a successful process integration requires the collaboration of machine vendors, infrastructure suppliers, IT services and the mine itself. It requires a number of of important preconditions to be fulfilled: ? Integrated IT systems with seamless interfaces between all components and peripherals involved ? Real time information access in all locations ? Real time overview of all operational aspects A crucial aspect for all of these issues is a seamless communication both above and also under ground and IT interfaces which are easy and price efficient to implement. This paper highlights ways to achieve productivity gains by process optimization. It also discusses needs for industry wide activities in order to enable cost efficient performance of mine process optimization projects.

Oct 1, 2009

By F. Kavicka

An original application of ANSYS simulated the forming of the temperature field of a massive casting from ductile cast-iron during the application various methods of its cooling using chills. The numerical model managed to optimize more than one method of cooling but, in addition to that, provided serious results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity and the local solidification time in any point of the casting. The determined relations therefore enable the prediction of the face density of the spheroids of graphite in dependence on the local solidification time. The calculated temperature field of 500x500x1000 mm casting of ductile cast-iron with various methods of cooling has successfully been compared with temperatures obtained experimentally. Acknowledgments. This analysis was conducted using a program devised within the framework of the GA CR projects (No.106/04/1334, No. 106/04/1006 and No. 106/04/094), of the COSTAPOMAT-OC526.10, MPO/FI-IM/021, EUREKA No.2716 COOP and KONTAKT 14/ 2005/06.

Jan 1, 2006

By Russell J. Gartrell

This report describes the engineering feasibility and economic advantages of using a steep angle conveyance (SAC) system in conjunction with medium and large draglines to transport spoil in a typical Western Coal Mine. The SAC system, including a receiving hopper, a steep angle conveyor and a sticker/spreader, is capable of processing overburden material at the rate of 7,000 tons/hr. The unique feature of this system is the steep angle conveyor which transports the overburden material from the pit bottom to the top of the spoil at angles to 45 degrees. Compared to other means of cross-pit conveyance considered during this study, the SAC system offers the advantage of easier operation, lower conveyance cost and greater mobility. The results of this study have shown that integration of the SAC system into both established and planned new mines would improve the overall mining operation, expand the operating capability of existing equipment and reduce mining end reclamation cost.

Jan 1, 1977

By Larry A. Haas

Carbonyl sulfide (COS) was decomposed to sulfur and CO in a silent electrical discharge. A threshold of about 4 kv at 60 Hz was required to dissociate the gas in a laboratory ozonizer at 790 torr with electrode gaps between 1 and 5.5 mm. Above the threshold value, the reaction rate increased with increasing voltage with helium or nitrogen diluent. With the latter diluent, higher voltages had to be applied to obtain the same yield in the 4-to 12-kv range. The COS decomposition rate increased with COS concentration, but a saturation value was reached at about 10 pct COS. The reaction rate decreased at low linear gas velocities as obtained at lower gas flows, larger electrode gaps, or larger reactor volumes. Increasing gas temperature also decreased the decomposition rate. The presence of solid adsorbents such as quartz wool, bauxite, or charcoal had no significant effect on the reaction rate. The addition of S02 did not affect the COS decomposition rate, but small amounts of water decreased the reaction rate. Over 50 pct of the COS was decomposed at room temperature and atmospheric pressure in a l7-kv ozonizer using a gas containing 0.9 pct COS in helium flowing at a rate of 0.3 liter/min. The average current was less than 5 ma. This method has possible application in eliminating the toxic air pollutant, COS, which is generated in petroleum refineries and in processes involving reactions between sulfurous and carbonaceous materials. Carbon monoxide that is formed can be further oxidized to CO2 after the collection of elemental sulfur.

Jan 1, 1972

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the quantitative procedures that have been developed for the mine-specific analyses of accident/injury experience data are presented and their applications are demonstrated in a summary form through case study examples. The quantitative procedures will aid mine safety management personnel to develop focused accident prevention strategies including training, as well as to justify the investment in such proactive programs through cost-benefit analyses.

Jan 1, 1993

By T. M. Tharp

Attempts to analyze the stability of slopes, foundations and underground openings in discontinuously jointed rock have generally assumed full joint continuity or ignored the role of stress concentration at the tips of discontinuous joints. The most common approach in rock slopes is to consider a failure plane consisting of coplanar, but discontinuous joints separated by intact rock. The intact rock is assumed to fail in shear as a MohrCoulomb material and to contribute a strength component proportional to the fraction of the failure plane that is intact rock (Jennings, 1970). An alternative approach by Stimpson (1978) applies Lajtai's (1969) theory for shear strength of discontinuously jointed rock masses to slopes. Lajtai allows tensile failure in the intact rock of a composite surface. This theory yields lower shear strength than that of Jennings (1970) except in the presence of high normal compression, however it also fails to account for the stress concentration at the tip of a discontinuous joint. For a given slope geometry, stresses increase with slope height, but in both of these models rock mass strength is independent of size. A fracture mechanics analysis shows that particularly for small slopes, rock mass strength decreases with size.A continuous stepped failure surface produced by propagation of preexisting joints may develop at lower shear stress than pre¬dicted by the Jennings (1970) or Lajtai (1969) models. This fracture mechanics model applied to slopes in competent rock is more realistic in its assumed failure mechanism, and for large slopes more conservative than the Jennings (1970) or Lajtai models (1969).

Jan 1, 1984

By Aníbal Castañaga Coll

El presente trabajo refiere los resultados de las pruebas sobre el empleo de las membranas filtrantes en la colección y análisis de muestras de polvo. De los resulados, se encontró que las muestras de polvo colectadas con membranas filtrantes para el estudio de su potencialidad silicógena, deben ser disueltas en acetona u otro solvente orgánico, para evitar los errores por defecto a que da lugar la transparencia del cuarzo y otros minerales con índices de refracción próximos al 1. 5 cuando se emplea el método directo. Asimismo, el método de la disolución en acetona se corresponde con los resultados del método Impinger, eliminando el problema creado por la excesiva acumulación de las partículas de polvo en las membranas filtrantes,considerándose como el más adecuado para espacios polvorientos.

Jul 20, 1961

By R. J. Durrheim

The seismicity of the Witwatersrand Basin and Bushveld Complex has been analysed, revealing significant differences in source and damage mechanisms. A comparison of mining taking place at similar depths and extraction ratios indicates that the seismic energy release rate is considerably lower in the Bushveld Complex. Technologies introduced in the past decade to manage the risk of rockbursting are reviewed and assessed. These include geophysical methods to detect hazardous structures ahead of mining, new mining layouts and support systems, and the mechanization of in-stope processes. Despite important differences in geology, in situ stress, mining layouts and methods, there are many opportunities for the reciprocal transfer of knowledge, experience and technology between the gold and platinum mining sectors to improve the management of the rockburst risk.

Jan 1, 2005

By Sadettin Bagdatli, Ali Kahriman, Umit Ozer, Alper Celtikci, Yucel Karakus

Due to population growth and rapid urbanization in Turkey, the need for the construction of residential units, transportation and infrastructure facilities has become increasingly more pressing. Since rock units encountered in the surface and underground in the construction of the subway, infrastructure and housing facilities, it is a necessity to use blast excavation methods. In recent years, large housing construction projects have been carried out especially in Turkish metropolitan areas, involving foundation excavations giving rise to great amounts of earthmoving. Since rock units encountered during foundation excavations are usually hard and solid, excavation with conventional machinery proves to be inadequate and unproductive, hence the necessity for the application of blasting technology.

Jan 1, 2014

By Llewellyn A. Rubin

Under Bureau of Mines Contract H0122007, Telcom, Inc., with the assistance of Fenix & Scisson, Inc., conducted a 17-month research and development project aimed at provid¬ing a field-test model of a guidance system for use with the Bureau of Mines Probe Drill. The Probe Drill is a part of the Bureau's Mine Rescue System developed under Contract H0101262. Volume I of this report is subdivided into seven sections. Volume II consists of a number of supporting appendices. In addition, there were delivered under the Contract, a number of other documents which are referenced in the text. Section 1 deals with essential contract information, Program Background, and a general system description. Section 2 covers the project chronology in brief. Section 3 is a digest of design considerations and implementation related to the requirements of the Contract. Section 4 is a description of the System, including illustrations of the hardware, and software. Section 5 is devoted to Operation and Maintenance. Para. 5.1 describes step-by-step field assembly and disassembly of the downhole unit. Para. 5.2 covers Operation. Para. 5.3 covers various aspects of maintenance from the lowest field echelon possible. Higher level maintenance must be accomplished in the laboratory, for the present field-test model. Para. 5.4 covers system calibration. Para. 5.5 covers detailed step-by-step operational sequences. Section 6 covers the results of the field testing, post-test evaluation, and recommendations. Essentially, we conclude that the present hardware (field-test model) has proven every aspect of system performance, but failed to provide reliable assurance of an operationally ready system. Telcom, therefore, recommends a three-phase continuing effort devised to provide the operationally-ready model of the system.

Jan 1, 1973

By E. De Souza

Two comprehensive surveys, which focus upon backfill practices and the economics of backfilling in underground mines in Canada, have been conducted. The two surveys were designed to assess operational practices and costs associated with the wide scope of filling operations that must be met by individual mines, ranging from raw material feed to the preparation plant, through underground backfill transportation, to in-stope product placement. This paper presents the current state of backfill usage in Canada, identifies trends in minefill practices and provides mine operators with an updated database of information upon which they might compare their own practices and costs with present trends throughout the industry.

May 1, 2003

A preliminary study was conducted by the Bureau of Mines to determine the effect of humidity on salt mine airborne dust levels. Results showed less dust where the humidity was elevated. Dust reductions appeared to be dependent on the equilibrium between humidity and salt.

Jan 1, 1980

By Michael G. Zabetakis

The spillage of liquid diethyl ether in rooms at floor level and 3 feet above the floor resulted in flammable vapor-air mixtures in the immediate vicinity of the exposed liquido The liquid temperature was found to decrease by as much as 35° C., with a resultant decrease in vaporization rate. A search of the literature yielded numerous references to unstable peroxide (residue) formed by the autoxidation of ether. Such residues appear to constitute an explosion hazard in the condensed state.

Jan 1, 1962

By M. Nyoka

Consideration of the economic, environmental, and social impacts associated with the life-cycle of a technology is of increasing importance for decision-making in industry. It has been suggested that economic assessment of technology deployment projects requires the translation of associated environmental effects into monetary values. This paper introduces an approach for identifying and evaluating environmental damage in monetary terms. The approach groups the environmental impacts associated with a technology life-cycle system into four main criteria: air, water, land, and mined abiotic resources. The valuation of the impacts on the resources consists of an economic cost benefit analysis (CBA) procedure that comprises four steps: the compiling of an impact inventory, a monetary valuation of the inventory, discounting, and a risk/uncertainty analysis. The monetary valuation step for impacts on air resources is primarily based on published externality costs for Europe and the United States, which are adopted and converted to reflect the South African context. Local opportunity costs are utilized for the other resource criteria. The damage costs are transformed into South African Rand at 2005 prices. The paper demonstrates how the approach may be applied in the assessment of projects in the metallurgical industry. Shortcomings in the approach are identified. For example, not all of the aspects that are considered necessary to assess environmental performances comprehensively can be valued in monetary terms. Also, certain values, specifically those pertaining to opportunity costs, need to be determined on a case-by-case basis. Furthermore, the uncertainties associated with the indicators obtained may strongly influence the usability of the results of an environmental performance assessment, e.g. future damage costs will change with fluctuations in the markets. It is concluded that although such an approach has merit in increasing the understanding of the potential financial implications of a technology?s environmental performance, further research is required to improve the approach described if it is to be used further in the South African metallurgical industry. Damage cost estimates that are specific to South Africa need to be developed to reduce uncertainty, and the combination of both quantitative and qualitative approaches is recommended for comprehensive sustain-ability decision-making.

Jan 1, 2007

By Ned Baker

Details are given of a Hydride Fuel System to provide 5 kg of HZ to fuel a Caterpillar 3304 engine previously modified to operate on hydrogen fuel and intended to power an underground mining vehicle. The Fuel System was installed onto the engine and the Engine/Fuel System tested under cold start conditions and a full range of engine loads and speeds. Refueling tests were also performed. The fuel system tested will support full engine power and allow delivery of at least 3/4-power on a continuous basis, from cold start conditions.

Jan 1, 1983

By Holger Witthaus

There is more than a century of experience in multiple seam mining in Germany. In several mines up to 20 seams had been excavated within the last decades. Due to the nature of the deposit and the history of technical development the older panels cause a complex stress distribution for the lower seams and the current longwalls in descending order of mining. The depth of the longwalls reaches up to 4000 ft. This causes a maximum vertical stress that reaches between 30 and appr. 60 MPa. To handle these conditions several support systems are applied for roadway heading. A central knowledge management system for ground control is used for design and dimensioning of support within the DSK. This paper gives an overview to the nature of German multiple seam mining and the solutions in matters of panel layout and support design. It describes the full lifecycle for roadways in the seam starting with the geological and geotechnical evaluation, the basics of roadway deformation in great depth, the development of planning tools and standards for German coal mines, the range of alternative of support systems and roadheading techniques, as well as the reinforcement measures and the processing of support at the T-junction of the face entry. This paper uses exemplary descriptions that are consolidated in a specialized reference book ?Gebirgsbeherrschung von Flözstrecken? ? ?Ground Control in Roadways? which summarizes the standards of ground control based on the development of the past 25 years in German coal mines.

Jan 1, 2007

By Susan M. Moore

Many challenges are faced by workers in lower-seam (42 inches or less) mines. The lower-seam heights confine mine workers to their knees as they perform their daily tasks such as installing roof bolts, delivering supplies, repairing belt, or cutting coal. Miners working in these lower seams often consider kneepads to be their only line of defense against knee injuries. However, healthy knees do not start and stop with kneepads. Other interventions such as changing postures, proper hygiene, and work station design may also be used to reduce mine workers? risks for developing knee injuries. Incorporating these and many other interventions into a mine worker?s ?way of life? is an important step to ensuring a long, healthy career and retirement. Keeping knees healthy is also a key aspect to reducing costs in low-seam mines as the industry battles rising health care costs, and training/recruitment of replacement workers is time-consuming and costly. Educating the workforce about the possible interventions to reduce knee injury risk is a primary objective for the National Institute for Occupational Safety and Health?s (NIOSH) Pittsburgh Research Laboratory (PRL). Therefore, NIOSH researchers, along with industry and academia, developed a training package to educate the mining community about some possible interventions beyond kneepads that may be used to help decrease knee injury rates. Increased awareness and simple changes are the first steps to reducing knee injuries.

May 1, 2008

By J. K. Richmond

This is a progress report summarizing more than 5 years of a long-range Bureau of Mines research program. The purpose of this program has been to investigate the fire and explosion properties of Green River oil shale in the Bureau's Experimental Mine, in laboratories, and in the field. The lean limits of explosibility of oil shale dust, by small-and large-scale tests, are reported as a function of grade, ignition source, and particle size. A limited number of laboratory tests on the autoignition of oil shale dust layers and the spontaneous combustion tendencies of oil shale are described. Moderate-scale rubble fire tests were conducted to determine flame spread rates as a function of ventilation flow. With the aid of a system to continuously monitor methane emissions in a deep oil shale mine, the characteristics of the methane flow are reported as a function of ventilation and blasting procedures, and are compared with gas yields from core samples. Tentative predictions as to the emission of the methane to be expected in deep oil shale mines, far from the outcrop, are offered. Brief reference is made to a parallel investigation into the fire and explosion hazards of oil shale mining and processing by a Bureau contractor; detailed results of the latter investigation are to be found in the contractor's reports.

Jan 1, 1982

By Gordon R. Sima

This contract is concerned with the construction of a Time Resolved Audio Dosimeter System consisting of one readout unit and several dosimeter units. The Time Resolved Audio Dosimeter System was designed and developed by the Bureau of Mines with the purpose of this contract aimed at obtaining additional units for further field testing and evaluation. All construction was in accordance with the Bureau of Mines design and/or Bureau approved drawings produced during the course of this contract. This report contains a summary of the construction efforts, problems encountered, recommendations and all drawings produced under this contract.

Jan 1, 1977