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By A. Singh

The control of flotation plants is by no means trivial. Flotation is one of the most interactive minerals? processing operations. The interactive nature of flotation circuits results in oscillations of levels and hence of grades and recoveries. Also, poor level setpoint tracking and disturbances have negative influences on grades and recoveries. The result is an unstable plant with limited scope for optimization. An advanced controller, FloatStarTM, has been developed to provide tight control and to reduce the amount of disturbances in flotation levels. It has been shown on a number of plants that the system results in faster and better setpoint tracking, better regulatory control and faster settling times after start-ups and disturbances. The successful stabilization provided by FloatStar has made it easier to investigate the area of optimization on flotation circuits. Mintek has identified the need for a more meaningful set of setpoints or aeration rates to use as a basis for control than levels and have advocated flow control by looking after residence times. When the feed conditions change, the ideal solution would be an algorithm or strategy that finds the new optimum conditions rather than just having an unguided hunt from the previous point. A multivariable flow-optimizing algorithm, a new module in FloatStar, has been developed to calculate optimum level setpoints and/or aeration rates that will aim to optimize the residence times, mass pulls and circulating loads within a flotation circuit. Keywords: flotation, regulatory, FloatStar, start-up, disturbance, residence times, circulating loads

Jan 1, 2003

By John Ellenberger

The nature of competition in the coal market tends to deplete the most favorable coal reserves first, and forces subsequent development of mines in more extreme ground conditions such as those associated with multiple-seam mining. In fact, 70% of the United States coal reserves are in multiple-seam situations. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop mine design algorithms that will result in safer multiple seam mines. This paper presents an overview of multiple seam issues in the central Appalachian coalfields. To date, more than 50 case histories have been analyzed from 20 operating mines in Eastern KY, Western VA, and Southern WV. Each case history is classified according to the degree of multiple-seam interaction, ranging from no apparent interaction to severe interaction with direct impacts on mine safety and resource recovery. The case histories are also examined with regard to amount and geologic characteristics of interburden and overburden, and design stability factors. The sequence of mining has also been found to be critical when the lower seam is fully-extracted. This paper compares current case histories to traditional rules of thumb. In addition two situations were modeled using LaModel software. LaModel has been upgraded to import pillar grids and topographic data from AutoCAD files. The cases presented demonstrate vertical stress capabilities of LaModel.

Jan 1, 2003

By Ken Schei, Martin Reed, Samuel Bowser, John Wright

From October 18 through October 21, 2001, United States Antarctic Program blasters opened ten access holes for research divers in 11-ft. thick sea ice at Explorers Cove, McMurdo Sound, Antarctica. During this project, a blasting seismograph with a hydrophone accessory was used to monitor the underwater shock waves associated with the blasting technique. Shock wave values averaged 42.3 psi for initial (cratering) shots and 5.9 for subsequent clearing shots, indicating that the ice absorbs most of the shock wave. The results also provide data for refining safety protocols for divers and for the protection of marine biota.

Jan 1, 2003

By A. M. Raichur, S. P. Vijayalakshmi

Fine coal dewatering is a major problem in the coal industry because the fines hold significant amounts of water and account for two-thirds of the product surface moisture. Present methods include flocculation using polymeric flocculants followed by filtration. But the kinetics of filtration are not favorable with such flocculants. In this study, a novel method involving flocculation with microorganisms for improving the settling rates and dewatering kinetics has been investigated. Two Gram-positive microorganisms, Mycobacterium phlei and Bacillus subtilis were used as bioflocculants. The effect of time, pH and ionic strength of the electrolyte used on adhesion and flocculation were studied. Adhesion tests showed that maximum adsorption occurred in 20 minutes in the pH range of 2-7 and the total amount of bacteria adsorbed was almost the same with both the flocculants. Nearly 98% of the coal flocculated with both the microorganisms in about 5 minutes. The filtration rate of fine coal almost doubled with addition of bacteria and electrolyte and maximum filtration occurred near the point-of-zero-charge of the bacteria.

Jan 1, 2003

By R. Abela

Heavy mineral sands are usually beneficiated in a spiral concentrator circuit prior to separation of heavy minerals into streams of zircon, rutile and ilmenite. The performance of the spiral concentrators is heavily affected by the presence of slimes in the rougher feed. The paper quantifies the effect of slimes content and discusses the beneficial effect of spiral feed de-sliming. The net effect of inefficient slimes removal can cause significant recovery losses of the heavy minerals present in the feed.

Jan 1, 2003

By Jussi Liipo, Pertti Lamberg

Image analysis of process samples gives precise data on particles and their composition. The results presented as liberation tables and maximum grade-recovery curves are informative and good for comparing different feed materials, but basing on them it is impossible to predict the results of the mineral separation process (flotation, magnetic separation, gravity separation) in details. The exact and extensive particle data has remained large unused, because there has not been a model nor a modeling program to include particle information in mineral separation processes. This study introduces a method, which incorporates the particle data in the kinetic model of flotation. Similar approach can be used in modeling other separation processes, too.

Jan 1, 2003

By L. Jurca, C. Gligor

After 1990, a great process of re-organisation and economic reform has occurred in the Romanian mining sector and especially in the pitcoal mining in the Jiu Valley. This process has included both legislation and the main aspects for getting an economic efficiency in the environment issues and for dealing the problems with social impact. Accordingly, starting with the year 1993 a new mining method has been introduced to turn efficient the pitcoal mining, and we speak about mining with caved in bed. This method has two variants: - with transverse strips and caved in bed; - with long face and caved in bed. Each of the above-mentioned variants has in turn several subdivisions, depending on how the longwall is prepared and on other characteristics. By using this method, the output has increased compared to other mining methods. The main safety aspects concerning caved in mining refer to: - great emissions of methane; - technical aspects (a mining method system, supports, discharging process); - pressure driving (analysed for the case of mining with long face, with transverse strips as well for the case of transverse strips when mining a subsequent sublevel).

Jan 1, 2003

By lonkion M. Font

Due to the known disadvantages of the use of iron silicate slag in the nickel converting stage, i.e., high metal losses, high magnetite content, and low fixation of impurities in the slag, the development of the new proposed "ferrous calcium silicate slag" for smelting and converting processes of nickel is very promising. Hence, considering the successful experimental results of using CaO base slag for the nickel smelting process, a study based on a detailed comparison for the phase equilibrium, and the minor elements distribution between the NilS2-FeS matte with either FeOx-CaO or FeOx-Si02 base slag was investigated. The main results are summarized as: no difference in the nickel losses between both slags was found at high nickel content in the matte, and the fractional distribution analysis for arsenic and antimony pointed out their preferential fixation in the calcium ferrite slag rather than in the iron silicate slag. Considering the energy and pollution issues, the technical feasibility of using calcium ferrite slag in a converting process of the Bessemer matte will have a prominent future for the nickel industry.

Jan 1, 2003

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 E Kozan

The paper presents new developments of the methodology of open pit coal production scheduling optimisation. They deal with the specific features of the exploitation of single coal seam and utilisation of truck-shovel and dragline systems. A production scheduling optimisation model is developed as a linear programming problem. The objective function maximises the net present value of the mining project under the technological constraints for meeting the demand function of the coal processing plant and effective utilisation of the available production equipment. Both principles of mine planning, coal quality optimisation and waste deferment are incorporated in the model. Results of a case study are provided to illustrate the applicability of the optimisation model.

Jan 1, 2003

It is self evident that in many cases mining disrupts communities, however, community reaction to mining varies enormously. This is due to a whole host of factors, some physical, some financial, some political and some a direct result of the projected mining company attitude towards the community at large. Physical and political factors are increasingly being dealt with realistically and financial aspects are to a significant extent determined by profit margins. If the acceptable profit margin canÆt accommodate all necessary costs (which now includes a variety of community considerations unheard of even a decade ago), then the project is just not viable. Despite major commitments now made by many mining companies to their affected communities, corporate attitudes, and their projection, remain as the most outstanding factor in mining project development where real gains can still be made in effectively reducing social risk. This paper addresses both international and domestic experience gained in managing this aspect of mining development risk, including initiatives implemented by multilateral institutions.

Jan 1, 2003

By C. Milne, T. M. Dyhr, T. E. Wilson

As time progresses, new concerns regarding long-term post-mining effects are identified, increasing mine closure costs. Regulators responding to public interest must take a “worst case” view and require post-closure monitoring or remediation processes. Although closure costs depend on the size and type of operation, general cost categories are defined, and median values (per acre, or per unit of production) are identified. Closure cost categories, as well as amounts, have increased with time. Except for increased efficiency in earth-moving and water management (surface or subsurface), there are no apparent offsets to a steady rise in closure costs. When the historical trend of closure costs is considered, it is probable that additional cost categories will come into being. For mine operators, the challenge will be to anticipate them and devise cost-effective remedies.

Jan 1, 2003

By t. Knezicek

Tuzla Coal Basin in Bosnia and Herzegovina is the largest coal area in the State. Regional mining industry sensed the need for mining machinery database development in order to achieve easier planning purposes and equipment selection for open cast mines in Tuzla Coal Basin. Several databases for mining machinery used on the bituminous deposits, i.e. on brown coal and lignite mines, were developed at the Faculty of Mining, Geology and Civil Engineering, Tuzla. System Development Method was used as the approach to the database development, generating relational structure of database. First database was established for trucks and was presented as simple table, drawn and filled on the paper sheet. In the next phase, data were stored in spreadsheet type software (Quattro Pro and Excel). Lately developed database is Bucket Wheel Excavator database designed in MS Access. Two concepts, spreadsheet and Access, were integrated into one large database, enabling manipulation of hundreds of data at one place. Required adaptations of existing database in MS Access, enables Access to be used as an integration resource. Database is designed to reserve free memory for input data for mining equipment not considered so far, such as spreaders, crushers, belt conveyors, tripper cars, etc. New, integrated database, at this stage, can be imported to any type of commercial or individual software where needed. Mining machinery integrated database for open cast mine operations is under going testing in a State company, Coal Mines Tuzla. Keywords: Tuzla Coal Basin, machinery database, SDM, relational database

Jan 1, 2003

By P. Somasundaran, T. Chen, Diptabhas Sarkar

We have developed a layer-by-layer deposition technique for preparation of nanocomposite particles. Using this process, it was possible to make nanocomposites of various oxides with desired local composition and microstructure. The attachment of the shell particles to core particles was achieved using controlled polymer adsorption. Removal of excess polymer was accomplished without detaching the pre-adsorbed polymers by a specific stepwise washing scheme. The inherent chemistry of the process makes it easy to incorporate functional fillers over core particles. The nanosized filler materials will replace the shell particles in the present process and the polymer bridge would be chosen by taking into consideration the respective surface chemistries of various shell and core particles.

Jan 1, 2003

By C. S. Compton, D. R. Dolinar, D. C. Oyler

More than 80% of U.S. roof bolts are fully-grouted, but about 1500 roof falls are reported each year. Anchorage failure of a fully grouted bolt can occur when the roof is active near the top of the hole. This paper reports on an extensive series of short-encapsulation pull tests (in which the bolts are installed with only 1 ft of resin) that were conducted in the National Institute for Occupational Safety and Health(NIOSH) Mine Safety Research Laboratory and operating mines in WV and PA. The tests confirmed that poor anchorage can been countered under some weak rock conditions. Suggestions for improving anchorage are included.

Jan 1, 2003

By D A. Aitzhanova, E Zh Omirzakova

The Republic of Kazakhstan has well developed mining and metallurgical complex. In modern conditions, when deposits of useful minerals are running thin, it is very important to find additional sources for obtaining necessary products. As our investigations showed different kinds of waste may be used for producing of different kinds of products, which are successfully applied in different branches of KazakhstanÆs economy. Analysis of ways for increasing of complex use of mineral raw materials of different deposits, widening raw mineral materials base and decreasing negative effects on the environment, are presented in this paper.

Jan 1, 2003

By N. Gatelier, T. You, J. C. Kandel

ABSTRACT: Underground hydrocarbons storage is a very specific domain for the designer. He is usually free to adjust the section, shape and layout to cope with the geological and geotechnical conditions. This paper presents a panorama of the geotechnical design of mined underground storage caverns, then lists a number of uncommon features encountered in a storage excavated in Sydney, Australia, the Elgas LPG project that had to face major non-isotropic conditions with numerous local variations, impacting on the achievement of the design profiles. Changes in geotechnical design methodology and practice are examined through this project, now in operation, which will have lasted altogether almost ten years. KEY WORDS: underground storage, geotechnical engineering, stability, methodology, design. ZUSAMMENFASSUNG: Die untertaegige Speicherung von Kohlenwasserstoffen unterliegt in der Planung sehr spezifischen Bedingungen. Der planende Ingenieur hat bei der Dimensionierung und Formgebung der Speicherhohlraeume gewisse Freiheiten, muss jedoch vorgefundene geologische und geotechnische Bedingungen beruecksichtigen. Der vorliegende Beitrag gibt zunaechst einen allgemeinen Ueberblick ueber die geotechnische Planung von bergmaennisch aufgefahrenen Speicherhhohlraeumen. Darueber hinaus werden Besonderheiten betrachtet, mit denen das Elgas LPG-Speicherprojekt in einer bergmaennisch aufgefahrenen Kaverne in Sydney, Australien konfrontiert war. Hierbei ging es um die Beruecksichtigung anisotroper Bedingungen mit zusaetzlichen Heterogenitaeten im Gestein und den daraus erwachsenden Schwierigkeiten, die geplante Hohlraumform zu verwirklichen. Ueber einen Zeitraum von fast 10 Jahren, in denen das jetzt in Betrieb befindliche Projekt unterschiedliche Betriebsphasen durchlaufen hat, wurden verschiedene geotechnische Entwurfsverfahren auf ihre Anwendbarkeit geprueft. SCHLUESSELWOERTER: Untergrundspeicherung, Geotechnik, Stabilitaet, Entwurfsverfahren, Planung. RESUME : Le stockage souterrain d’hydrocarbures est un domaine très spécifique pour le concepteur, car celui-ci dispose d'une large liberté pour adapter les sections, les formes et les implantations aux conditions géologiques et géotechniques de l’environnement choisi. Après un panorama de la conception géotechnique des stockages souterrains d’hydrocarbures par la méthode dite des cavités minées, l’accent sera mis sur un certain nombre de particularités rencontrées lors du projet de stockage de GPL de Elgas à Sydney en Australie, creusé dans de très fortes conditions d’anisotropie du massif rocheux, avec de nombreuses variations locales et toutes les implications que cela peut avoir sur le maintien des formes. L’évolution des approches méthodologiques géotechniques durant la dizaine d'années de développement de ce projet depuis les premières études jusqu'à l'exploitation actuelle est également présentée. MOTS-CLEFS : stockage souterrain, géotechnique, stabilité, méthode, conception.

Jan 1, 2003

By M. Berger

The ‘Metallurgical Operations’ Department of Grinaker-LTA Process Engineering (GLTA) currently undertakes then primary mining as well as the re-deposition of tailings forTicor South Africa (Ticor) at their Hillendale mine near Empangeni, KwaZulu-Natal, South Africa. The mining plant, which was designed by GLTA on a Build, Own, Operate and Transfer (BOOT) basis, is capable of mining 780 000 tons per month of ROM material which is then pumped to the Primary Wet Plant for treatment by Ticor. Hydraulic mining via high pressure water cannons and subsequent transfer of the heavy mineral slurry at an RD of between 1.35 and 1.48, has never before been undertaken successfully at this level of production on an in situ reserve. The presentation will take the form of a case study in which the unique site operating conditions will be detailed and discussed, as will the innovative process and engineering solutions employed by GLTA to overcome the engineering and production challenges encountered. In order to protect the intellectual property involved in this operation, this paper is fairly general in nature, and attempts merely to provide the reader with a broad perspective understanding of the operation, and some of the difficulties encountered during the early stages of production.

Jan 1, 2003

By W. P. Johnstone

The computer assisted generation of geological models to represent the geometry of, and grade distribution within, orebodies is a rapidly growing area of the geological profession. Such models are increasingly used as a necessary starting point in determining the mineability of mineral deposits in terms of practical mine design and economic considerations. The transition from traditional techniques such as field or underground mapping and the manual calculation of grade and tonnage estimates, as well as related activities such as the interpolation of cross-sections, the use of stereographic projections, core logging and hand contouring, to computerized applications, is by no means complete. In fact, many geological professionals deliberately avoid the use of computer simulations based on the perception that the resulting models are simplistic and that their construction is not founded on sound geological principles. The purpose of this paper is to assess current thinking on this topic by considering; (a) an overview of advances in the drafting of geological maps, (b) the theoretical basis for multi-dimensional geological modelling, (c) the case for combining traditional and modern techniques, and (d) the benefits to the mining value chain.

Jan 1, 2003

By P. F. Ziemkiewicz

This project evaluated the performance of nine passive treatment methods by studying 137 treatment units in eight eastern states. Performance was normalized according to construction cost, projected service life and tons of acid load treated. Results were dimensioned as $/tons of acid load treated/year. These costs were then compared to those of chemical treatment. Sites that achieved acid load reductions at costs below those of chemical treatment were considered successful. In addition to evaluating the performance of the treatment methods, this paper describes the various passive treatment systems, their applications and performance data for individual treatment units.

Jan 1, 2003