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By S. Stewart

The topic of sustainability in the mining and minerals industries focusing on economic development, ecological integrity and responsible stewardship of the environment together with community well being are vital issues for our industries at a crucial time in our history. Many of the priorities of the Greek Presidency of the European Community ? Sharing the Future in a Community of Values ? encourage our industry to continue to innovate and develop many of the environmental and social initiatives already underway. Sustainable development is here to stay and has been placed strategically at the heart of all European public policy. The future of the minerals industry here in Europe as well as elsewhere depends on how well professional mining people, both as individuals and through their associations and others, have to present their case for a sustainable mining and minerals industry to a critical world. And, Greece with its strong and expanding mining, minerals and metals base has more to win or lose from this endeavor than many others.

Jan 1, 2003

By Betty L. Gibbs

Mine planning and scheduling done with computer programs is possible only after extensive work has been completed to define the geologic extent of an ore body and an overall mine design. Mine planning methodology on computer can vary from computerized engineering tasks through systems which completely optimize a plan with little input from an engineer during the actual scheduling process. However, a strong emphasis is placed on producing practical mining sequences which may be "best" rather than "optimum". This section offers several viewpoints on the planning process using computers. Interactive planning and scheduling systems are attractive for many companies because they are easy for engineers to understand, and the results are acceptable. The engineer develops an open pit mine sequence by trial and error using interactive graphics. The results of this approach can usually be improved. A computer program can help an engineer make many trials in a short time period and provide a higher level of confidence that a "best" plan has been generated.

Jan 1, 1989

By Julian Brown, Steve Hicks, Zach Agioutantis, Zachary Wedding

Analysis of Coal Pillar Stability (ACPS) software, released in 2018, integrates numerous empirical pillar design techniques. The ACPS program incorporates methodologies originally available as design tools from the National Institute for Occupational Safety & Health (NIOSH), including Analysis of Longwall Pillar Stability (ALPS), Analysis of Retreat Mining Pillar Stability (ARMPS), Analysis of Multiple Seam Stability (AMSS), and concepts including Coal Mine Roof Rating (CMRR), the Mark-Bieniawski pillar formula, and pressure arch loading. The design methodologies that are the basis of ACPS were developed via analysis of significant amounts of real-world data and have been standards of the United States coal industry for decades. While there are empirical factors built into ACPS, making it ideal for use in U.S. coalfields, the concepts in the program have proven to be applicable in variable mine settings, and the software was developed to allow for user-based, site-specific modifications of key design inputs. Application of ACPS to cases outside the regions for which it was developed must be approached carefully, and continuous development of site-specific data is mandatory. A case study is presented involving the application of ACPS to assess pillar stability and assist future design for an underground lignite mine in Eastern Europe. Assessment of in-mine observations, review of the geology of the lignite mine, and evaluation of specific conditions associated with a failure event resulted in “calibration” of key input factors to ACPS. Scenarios evaluated with ACPS suggest that pillar strength and overburden depth are key factors for the determination of pillar stability and design in future areas.

Jun 25, 2024

By Steve Kral

It is agreed in mining and regulatory circles that a safe and healthy working environment for underground miners is the major challenge for mine operators. Underground mine ventilation is complex. And it is becoming even more difficult as mines become larger, deeper and more complicated. At the Seventh US Mine Ventilaton Symposium, a group of mine ventilation experts from industry, government and academia attempted to solve some of the problems in ventilating underground mines. The meeting, sponsored by the Underground Ventilation Committee of SME and the University of Kentucky, was held in Lexington, KY June 5-7, 1995. Andrzej M. Wala, symposium chairman, commented that previous mine ventilation symposiums have focused mainly on work in North America. The 1995 symposium, however, broadened its borders to include several international papers. Of the 77 papers presented and bound into the Proceedings volume, 25 are from operations and research centers outside of the United States and Canada.

Jan 1, 1995

By A. G. Sciulli, G. P. Ballock, G. Hearnshaw, K. K. Wu

Waste disposal underground is the most effective method when viewed from an environmental aspect. As costs of other methods of disposal continue to escalate, the cost effectiveness of underground disposal during the mining cycle becomes increasingly attractive. The use of concrete for sealing abandoned mines has proved to be suspect when associated with a relatively incompetent adjacent strata due to its shrinkage characteristics. Complete failure of the plug has been known to occur in some instances. A more effective, cost competitive seal can be obtained using pneumatically stowed material and incorporating a polyurethane grout, which has greater adhesion characteristics than concrete. Injection of the surrounding strata and of the stowed material helps to ensure an impervious barrier and prevent the plug from moving when subject to high pressure heads. When properly placed, impervious seals cause the old workings to flood, raise the mine pool level, and thus eventually eliminate the potential for oxidation, which is the primary cause of acidity in the water

Jan 1, 1987

By H. J. Handewith, W. D. Coski

This paper describes the development and testing of the RAMEX excavation system. Incorporating a synergy of low velocity, high energy impact and kerf cutting, this machine offers a competitive alternative to drilling and blasting in hard rock. It is a boom mining machine that incorporates the features of a lightweight roadheader and it can mine nearly any shape opening in hard rock. The RAMEX Tunneler has been developed to satisfy industry demands for a non-explosive, flexible, continuous and rapid underground rock excavation system. It will produce minimum ground vibration in the urban environment and allow the flexibility necessary for thin seam mining conditions. It will also reduce initial ground support costs and has a minimum impact on rock integrity. Developed by RAMEX Systems with cooperative research provided by the U.S. Bureau of Mines, this system, could produce the next step in the continuing evolution of mechanical mining systems.

Jan 1, 1989

By M. Kavvadas

Geotechnical design using Factors of Safety recommended by Codes of Practice is based on largely unknown ?margins of safety?, usually without consideration for the importance of the project (i.e., potential consequences of failure) directly or explicitly. On the contrary, probabilistic modelling can be a useful tool in risk management as it provides the means to measure the risk to be managed. This is achieved by calculating the probability of failure associated with a specific design, i.e., by relating the classical factors of safety with the corresponding probability of failure and by using a cost optimization procedure to achieve ?optimal? designs, accounting for the expected costs in case of catastrophic failure. This paper describes the methods used to calculate the probability of failure and its correlation with the classical Factor of Safety using sampling techniques and a simplified method based on the moments of the factor of safety considered as a random variable. These procedures are illustrated in an example which investigates the stability of a slope.

Jan 1, 2005

At present, increasing focus of public perception is placed on the environmental and social benefits, risks and impacts of metals and metal-bearing products. To address these issues, the concept of product stewardship has recently been introduced into the political debate. In this paper, results from a survey of existing environmental and social reporting practice in the copper mining, smelting, refining and fabricating industry are presented. In this context, particular emphasis is placed on the reporting practice regarding products and product performance over the life cycle. In a few companies there has recently been a shift towards adopting product stewardship principles and putting them into action. As part of an ongoing exercise within the Non-Ferrous Consultative Forum on Sustainable Development sponsored by the International Copper Study Group (ICSG) key issues of interest to the non-ferrous metals sector are being addressed. The Forum, for example, has developed a series of principles, criteria and indicators that could form the basis for a voluntary, industry-lead product stewardship scheme. Current achievements and way forward of this product stewardship initiative will be presented.

Jan 1, 2003

By Elias Apostolidis

Since 500 B.C. Mt. Penteli has been famous as white marble production site, which provided the birthstones for the construction of Athens Acropolis and Parthenon. The Aloula quarry belongs to ?Dionyssomarble S.A.?, a commercial and industrial marble company, which retreated after 1940. Disturbance in the site was minimal since then. In July of 1994 the reclamation started by a group of quarry workers from Paros, already familiar with traditional marble quarrying techniques, unchanged from antiquity to 1940. The project was complete in 1997. Our main objectives have been to show respect to the area and the art of people, to let nature guide our choices, to use only local stone as a construction means, to imitate the old construction rules and to turn the land use into amenity and civilization. Aloula quarry will become a site restored for amenity and civilisation, including ancient quarrying techniques. The restored quarry is already open to the public, though to a small number of visitors, and soon will become an amenity park and an open space museum of the ancient quarrying art.

Jan 1, 2002

By Tracy E. Barnes

The process of computerized reserve estimation consists of assuming a model of the spatial continuity of a deposit and then, working within the assumed model, estimating the grade and tonnage of the deposit. The basis for geostatistical analysis is a statistical definition of this continuity or the variogram. The true variogram is essentially impossible to define. So an experimental variogram is defined from the sample data and kriging proceeds assuming that this experimental variogram is a good approximation of the true variogram. Therefore the closer the experimental variogram is to the true variogram the better the estimate will be. Realizing that the variogram is nothing more than the definition of the spatial continuity of the deposit, taking the known geologic continuity of the deposit into account will give a superior variogram. The use of known geology is a widely recognized necessity for good structural analysis of a deposit, but is rarely fully incorporated into the structural analysis.

Jan 1, 1982

By Y. K. Yen, J. D. Miller, C. L. Lin

Particle size segregation is a common phenomenon in many particulate processes and has many undesirable effects. The size segregation which occurs on a belt conveyor causes a serious problem for on-line particle size measurement using image-based techniques. Whether particle size distributions measured from the top layer of the belt are representative of the total particle population is largely dependent on the degree of size segregation. Therefore, it is important to understand the nature of such size segregation in order to make appropriate corrections for on-line particle size analysis. Monte Carlo simulation has been used to provide segregation information on particles with simple geometry and the results can help to determine important factors in experiments with irregularly shaped particles. It is expected that the relationship between the particle size distribution of the top layer and that of the entire particle population on a belt conveyor can be formulated as a model based function.

Jan 1, 1997

By R. Flattery, Z. Agioutantis

Coal and rock pillar design is critical not only for mineral extraction but also for the safety of the mine operators. Pillar strength can be estimated through numerous empirical formulas that are available in the literature, which are typically based on a statistical analysis of case study data. The limitation of most of these equations is that they only considered the width to height ratio and in situ rock or coal strength for pillars in horizontal seams. The adoption of such equations to estimate pillar strength in inclined seams may overestimate the pillar strength and ultimately lead to a poor pillar design. This paper will discuss different techniques that can be used to estimate pillar strength in inclined seams as well as present preliminary modeling results for stress redistribution around inclined pillars. Factors in the parametric analysis include pillar shapes, geometry, and seam inclination.

Mar 2, 2022

By Joe Scheuering, Don Poulter, John Trirnble

Closure of the Grey Eagle Mine tailings impoundment is an example of closing a "wet" tailings impoundment at the cessation of milling operations. This paper presents a summary of tailings cover design and construction, tailings deposition sequences to facilitate closure, construction schedules, costs, and post-closure monitoring. Permit requirements which influenced the design and construction of the tailings are summarized. The performance of the cover and post-closure monitoring issues are also discussed.

Jan 1, 1995

By Robert P. Mahoney, William J. Roe

Polymers of a wide variety of composition are used in coal and mineral beneficiation. Applications include flocculation and coagulation in thickeners, filtration enhancement, mill scale control, dust control, ore leaching improvement, and pond management. The proper chemistry of the polymer is determined by many factors, including the nature of the process, mineral type, and respective performance requirements. This paper provides an overview of the various current applications of polymers in mineral processing, and a description of the applicable polymer chemistries which find utility in these applications. Examples of structure/performance relationships are discussed.

Jan 1, 1994

By R. Sivamohan, F. Huang

A mineral processing strategy developed for the finely and complexly interlayered calcite rich wollastonite, microcline, and iron-garnet ore of Jokkmokk, northern Sweden, gives an overall calcite recovery of 89.4% at a grade of 90.7% CaCO3. The wollastonite product assays 53.0% Ca- SiO3 at a recovery of 92.2%. The significant elements of the developed strategy are stepwise grinding, wet high intensity magnetic separation (WHIMS), reverse flotation and starvation flotation. Stepwise grinding avoids the overgrinding of soft calcite. WHIMS removes the colored iron-garnet impurity and thereby increases the whiteness of the product. Reverse flotation enables a simple flotation circuit and starvation `flotation helps to optimize the physicochemical conditions in cleaner flotation by giving rougher products of narrow particle size distributions. Moreover, with the reagent scheme developed in this work only one cleaner stage is necessary for the various rougher flotation products to be upgraded to give the foregoing results. In this paper, the strategy is presented in detail along with appropriate results.

Jan 1, 1990

By R. F. Holub, P. J. Dallimore

Basic to solving the problem of the role of radon transport on radon concentrations in mines is to establish whether it occurs primarily as diffusion and forced flow through porous rock or through fissures in the rock. The laboratory experiments performed involved measurements of diffusion and emanation coefficients, porosity and permeability of representative rock samples. Significant differences have been found when comparing the results of the laboratory permeability determinations to those of the mine determinations. Considerations of underlying principles, however, suggest that the diffusion and emanation coefficients are the same in laboratory and mine. It was also found that moisture content plays a dominant role in radon transport through rock. Using these concepts and findings, some conclusions about the radon concentrations in mines have been drawn.

Jan 1, 1981

By D. W. Horsfall

The washability of South African coals is described and the problems encountered in washing at low densities, to make premium products, are enumerated. The measures taken to overcome those problems, when low density separations became a commercial necessity, are described in detail. The descriptions of processes are with specific reference to the three sizes commonly treated separately in coal preparation namely coarse coal, small coal, and fine coal. Some information is given on the performance characteristics of the plants erected to meet market requirements.

Jan 1, 1995

By P. C. Schutte, A. J. Kielblock

INTRODUCTION Certain activities, such as emergency work and rescue operations, often have to be undertaken in environments where heat loads often exceed limits prescribed for routine work. This is particularly relevant to the South African mining industry where heat stress-induced fatalities are not uncommon during rescue operations. In this regard an excessively hot environment is defined as one where either the dry-bulb temperature exceeds 37,0°C or the wet-bulb temperature exceeds 32,5"C, and it is therefore not surprising that heat stroke mortality escalates rapidly when these limits are exceeded. A review of both local and international standards indicated that the available information on safe exposure times under abnormal heat stress conditions is very limited. Where available, such standards are aimed at the general population, including both sexes, irrespective of age and also the least heat tolerant worker, and not at a medically-screened, all-male population free of grossly heat intolerant individuals, as is the case in the South African mining industry. It is suggested that available norms and limits are too conservative for local application and, therefore, unrealistic. In view of the definite need to protect workers when exposed to abnormally high environmental temperatures, the present study was undertaken to establish a scientifically derived data base. applicable to local conditions, to determine safe exposure times: Any exposure limit, especially in an emergency situation, should be easy to administer, valid and reliable. These aspects, there- fore, form an integral part of this paper. FORMULATION OF HEAT STRESS LIMITS The formulation of heat stress limits was based on the criterion that a heat exposed individual should experience a negligible risk of developing dangerously elevated body temperatures. In order to provide a database for risk assessment, certain physiological responses of heat tolerant men were determined at various combinations of thermal conditions and work rate in a climatic chamber. These physiological responses were analysed statistically in order to predict safe survival and tolerance times as a function of thermal conditions and work rate. EXPERIMENTAL DESIGN A total of 202 randomly selected, medically fit mine workers volunteered for the study on the basis of informed consent. These men were considered to be inherently heat tolerant in as far as they had successfully completed a heat tolerance test (Anon., 1991) or the standard climatic room acclimatisation procedure used on many South African gold mines (Anon., 1989). The subjects were allocated randomly to 14 experimental groups and each group was exposed in a climatic room to one of

Jan 1, 1997

By Leonhard Schmid

INTRODUCTION In the region of Zurich several of the Swiss Interstate Highways meet and have to be linked to form a continuous network. The subalpine glacial topography with hills, ridges and lakes requires the construction of many tunnels (Figure 1). The Milchbuck Tunnel forms part of the inner arterial highway system of the city of Zurich. It passes underneath the ridge separating the Limmat and Glatt valleys. In its final configuration the tunnel will consist of two parallel three-lane tunnels (Figure 2). For the time being only one tunnel is constructed. This tunnel will be operated with two outbound (climbing) lanes and a single inbound (descending) lane (Figure 3). The owner, the Canton of Zurich, awarded the contract for the construction to a joint venture with the following three contractors: Locher & Cie AG (leader), Prader AG, A. Brunner's Erben, all located in Zurich. The actual freezing was performed by subcontractor Philipp Holzmann AG, Mannheim, West Germany. Electrowatt Engineering Services Ltd, Zurich, was design engineer and performed the construction supervision.

Jan 1, 1981

By Xia Guangxiang, R. Y. Wan, Yang Hanlin, M. C. Fuerstenau

The mechanism and kinetics of pretreatment on pyritic gold concentrate with the catalytic oxidation acid leach (COAL) process were studied in the temperature range of 80-100°C and oxygen pressure range of 230-1013 kPa, with sodium lignosulfonate (SL) and mixed medium of sulfuric acid (11 g/[ ]) and nitric acid (5.5 g/ [ ]). The results show that nitric acid acts as a catalyst, the surfactant changes the hydro-phobicity of resulting elemental sulfur to favor the oxidation of pyrite, and the oxidation-determining step would be the chemical reaction between nitric acid and pyrite. When about 80% of pyrite contained in the concentrate is oxidized, the gold cyanidation extraction exceeds 95 % . The nitric acid in solution can be recycled and used again.

Jan 1, 1993