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By E. M. Bloomfield, C. A. Jermy

Geotechnical tests were carried out within an area of the coastal sand dune cordon of northern KwaZulu-Natal which is currently being exploited through mining of heavy mineral sands. In situ and laboratory tests were carried out to assess the density, strength and stability of the dune sand material before and after mining. The most stable combination of sand (>63µm) and fines(<63µm) material was determined as well as the effects of compaction on the strength and permeability of the sand dune samples. In situ DCP and density tests showed that the sand dunes fall in density immediately after mining has taken place. However, settlement of the dunes occurs with time and the density increases within the top 2 metres, and particularly once the dunes become re-vegetated. Laboratory tests carried out showed that the dune sand with between 20% and 30% added fines had the highest shear strength and dry density, but the permeability was shown to decrease steadily with increasing fines up to 40% fines added. The addition of fines would result in steadily increasing water flow problems. Compaction of the dune sands was shown to significantly increase the density and the shear strength, but with a corresponding dramatic decrease in the permeability of the material. Slope stability analysis carried out on models of the dunes with increasing fines showed that the addition of fines increases the stability of the dune sands up to a peak of about 30% fines added, and compaction further increases the stability of the dune sands. Despite the benefits of compaction on the stability of the tailings dunes, the loss of permeability is thought to outweigh the benefits as well as the high costs involved. The stability of the tailings dunes greatly increases after re-vegetation. Compaction and densification of the tailings dunes may be necessary within the top 2 m interval if large-scale construction takes place on the sand dunes. Petrographic analysis was performed to understand the granular interactions of the sand and fines fractions, and the effect of the in situ weathering of the dune sands on the stability of the sand dunes. As the fines contents increase the gaps between the sand grains are filled, until a point where the percentage of fines begins to push the sand grains apart.

Jan 1, 2003

By Jana Dobrovska

Solidification and cooling of a continuously cast slab and simultaneous heating of a mould is a very complicated problem of transient heat and mass transfer. Nowadays, the solving of such a problem is impossible without numerical models of the temperature field not only of the slab itself, while it is being processed through the whole concasting machine (Caster), but of the mould as well. Two original numerical models have been developed and used in the investigation of a continuously cast steel slab. The first (one of two) 3D model of the temperature field of a concasting is capable of simulating the temperature field of a caster. Experimental research and data acquisition have to be conducted simultaneously with the numerical computation-not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. After computation, it is possible to obtain the temperatures al each node of the network, and at each time of the process. The utilization of the numerical model of solidification and cooling of a concasting plays an indispensable role in practice. The potential change of technology-on the basis of computation-is constantly guided by the effort to optimize, i.e. to maximize the quality of the process. The user can therefore choose any appropriate longitudinal or cross-section of a slab and display or print the temperature field in a 3D or 20 graph whenever necessary. The second numerical model of dendritic segregation of elements assesses critical points of slabs from the viewpoint of their increased susceptibility to crack and fissure. In order to apply this model, it is necessary to analyze the heterogeneity of samples of the constituent elements (Mn, Si and others) and impurities (P, S and others) in characteristic places of the solidifying slab. The numerical model, based on measurement results obtained by an electron micro-probe, generates distribution curves showing the dendritic segregation of the analyzed element, together with the distribution coefficients of the elements between the liquid and solid states. The combination of both models enables the prediction of cracks and fissures in critical points of the continuously cast carbon-steel slab. Both models had been applied in the industrial investigation of a cast low-carbon-steel slab.

Jan 1, 2003

By E. Kozeschnik

A new model is presented for the simulation of the evolution of precipitates in a multi-component multi-particle multi-phase environment The mathematical formulation as well as the physical background of the model are briefly introduced and its capabilities are discussed on the example of a precipitation sequence in a complex steel. Keywords: Modeling, precipitation kinetics, nucleation, growth, coarsening

Jan 1, 2003

By Martin Herenknecht, Michael Knabe, Ulrich Rehm

In Switzerland at present, the longest railway tunnels in the world, the Gotthard(57 km) and the Loetschberg base tunnel (34km) are under construction. For thischallenge six high-tech HERRENKNECHT Hard Rock Tunnel Boring Machines (TBM)are applied, which have to excavate approx. 80 km at the Gotthard and 20 km at the Loetschberg Tunnels. The machines being used are of a single Gripper-TBM type, which are equipped with the latest rock support techniques, in order to optimize the quality of the working conditions for the personnel which have direct impact on the quality of the tunnels. The different requirements of the projects based on different speci?cations within the tender documents led to completely different TBM concepts which will be reviewed in detail in this paper.

Jan 1, 2003

By Leon Lorenzen, Charlene Gokhale

"In excess of 24 x 106 tons (Eskom, 1997) of coal-derived fly ash is produced annually in South Africa for the production of electric power. A large quantity of this ash is disposed of as a solid waste in landfills, thus posing a serious environmental problem. Due to the shortage of landfill sites, new ways of utilising fly ash are needed. Recently several authors have shown that various combustion fly ashes can be converted into zeolites to obtain industrial products with applicability in environmental management. Geopolymerisation has emerged during the last few years as a possible solution to some waste stabilisation and solidification problems. henolic compounds have been shown to be toxic to soil microorganisms at the parts-per-million level. Indeed several of the organic compounds classified by the U.S. Environmental Protection Agency as priority pollutants, are phenols. Immobilisation of phenols by adsorption on zeolites and encapsulation in a geopolymer appears to be a promising solution to this problem.This paper reports a technique for the production of a low-silica sodium zeolitic material from fly ash (zeolite NaP1), and its application for the stabilisation of phenols by adsorption and subsequent encapsulation in a geopolymer matrix. A commercial zeolite, clinoptilolite was also utilised as an adsorbent. Due to their uniform pore sizes and large surface areas, zeolitic materials are suitable for ion exchange and adsorption of certain organic substances. Adsorption data show that the commercial zeolite, clinoptilolite was an effective adsorbent for organics. Adsorption data showed that between 51.2 ppm and 74.3 ppm of chlorophenol or between 15.4 ppm and 32.5 ppm of phenol could be adsorbed. Physical encapsulation of the coated zeolite loaded with organic within a geopolymeric matrix increased the compressive strength of the matrix from 28.80 kN to 40.79 kN. Leaching data for the various geopolymer matrices with encapsulated and loaded zeolites show no organics being leached from the system at a detection level of 2ppm. According to the SABS these would have been acceptable organic concentrations within a waste water stream."

Jan 1, 2003

By M. J. Blattman

Upon completion of an underground mine design, the planning engineer is faced with a surprisingly complex problem, “What development and mining sequence should be implemented so as to maximize the return on investment?” The problem relates to the scheduling of development headings to access stope production areas in such a way that the most money is made as quickly as possible for as long as possible. The total dollar value of the stopes, the average grade, the total tonnage, nor even the profit margin do not accurately give an indication of the “proper” mining sequence on their own. This paper will outline a method being developed by the author that can create a sequence of events that maximizes the net present value (NPV) of a given development and production design using information already being generated during the design process.

Jan 1, 2003

By P. Wittke-Gatterman

ABSTRACT: A three dimensional constitutive law for swelling rock is presented. It can be applied to the osmotic swelling of mudstone as well as to the swelling of rocks containing anhydrite. It describes the development of time-dependent strains and stresses due to swelling considering elastic and viskoplastic behaviour. Furthermore an anisotropic swelling behaviour can be considered. This constitutive model was implemented within a numerical computation program according to the finite element method and calibrated on the basis of the results of measurements in the investigation drift of the Freudenstein tunnel which is completely located in the unleached Gypsum Keuper. A parameter combination could be found which results in a good agreement between numerical solutions and results of measurements. Therewith an analysis procedure which enables the design of tunnels in swelling rock is available. ZUSAMMENFASSUNG: Im vorliegenden Beitrag wird ein dreidimensionales Quellgesetz vorgestellt, das nach derzeitigem Kenntnisstand sowohl auf das osmotische Quellen von Tonsteinen als auch auf das Quellen anhydrithaltiger Ton- beziehungsweise Schluffsteine anwendbar ist. Das Stoffgesetz wurde in ein Finite-Elemente-Programm implementiert und anhand von Meßergebnissen des im unausgelaugten Gipskeuper liegenden Untersuchungsstollens des Freudensteintunnels kalibriert. Es ist gelungen, eine Kennwertkombination zu finden, mit der alle Meßergebnisse gut beschrieben werden können. Damit steht ein Bemessungsverfahren für Tunnel in quellfähigem Gebirge zur Verfügung. RÉSUMÉ: Dans l&apos;article présent un loi de gonflement à trois dimensions est présenté, qui peut être appliqué aussi bien au gonflement osmotique de l&apos;argile compactée q&apos;au gonflement de l&apos;argile compactée ou du limon compacté contenant de l&apos;anhydrite. Le loi de comportement était implémenté dans un programme numérique d&apos;éléments finis et calibré avec des résultats de mesures de la galerie de recherche du tunnel de Freudenstein, situé dans le Keuper de gypse non lessivé. On est réussi à trouver une combinaison de paramètres avec laquelle tous les résultats de mesures peuvent être bien décrits. Par ce moyen, une méthode de dimensionnement existe pour des tunnels dans de la roche capable de gonfler.

Jan 1, 2003

By Stacy Loizeaux

The Beirut Hilton Hotel, which was built in 1975, but never occupied, was imploded on Sunday, July 14, 2002 by Controlled Demolition, Inc. (CDI) of Phoenix, Maryland and their client, Optimal Engineering Consulting & Contracting, SARL, (OECC) of Antelias, Lebanon to make room for a new hotel. Twenty-seven years ago, just days before the grand opening, the Hilton Hotel became the site of fighting in Lebanon’s Civil War. Christian and Muslim militiamen fought room to room for control of the building and other nearby hotels. The Hilton, two other major hotels and other high-rise buildings were ravaged by the fighting. The building was one of the three major hotels badly damaged, but not rebuilt, in Lebanon. Located in the City Center, the Hilton stood out in a major redevelopment area which, in recent years, had erased the scars of the 15 year long Civil Wa r.

Jan 1, 2003

By H. Deveci

Bioleaching/biooxidation is essentially a dissolution process with the involvement of acidophilic bacteria acting as the "catalyst" to accelerate the dissolution of metals from sulfide minerals. The contribution of bacteria to the metal dissolution is closely controlled by the growth of bacteria, which is itself affected by the physico-chemical conditions within the bioleaching environment. There are a number of operating parameters controlling bioleaching processes, which are required to be maintained within a certain range in the leaching environment whereby the activity of bacteria with the resultant oxidation of sulfide minerals can be optimized. In this regard temperature, acidity, oxidizing conditions, availability of nutrients, oxygen and carbon dioxide, surface area and presence of toxic ions are of prime importance for control and optimization of bioleaching of sulfide ores/concentrates. Bioleaching processes are temperature and pH dependent with optimum metal dissolution occurring in a particular range where the bacterial strain is most active e.g. mesophiles at 35-40°C and pH 1.6-2.0. Provision of nutrient salts is required to maintain the optimnm growth and hence metal dissolution with the quantity of nutrients apparently being dependent on the availability of substrate i.e. head grade/pulp density of an ore/concentrate. Oxygen transfer is one of the most critical factors since the oxygen levels below 1-2 mgll may adversely affect the oxidizing activity of bacteria. Bioleaching rate tends to improve with increasing the surface area at low pulp densities but, in practice. the pulp density is limited to -20010 w/v. Increasing concentrations of ions such as cr may also adversely affect the oxidative activity of bacteria. Keywords: Bioleaching, Biooxidation, Acidophilic bacteria

Jan 1, 2003

By A. R. Zambrano

Equations for power draft, capacity and work input for predicting the performance of industrial grinding mills are derived based on torque measurements using a laboratory instrumented mill. These derivations are based on mechanical principles and on the first-order kinetics of the grinding process. Rittinger&apos;s, Kick&apos;s and Bond&apos;s laws express work input as work index (Wi) times a particle size function. It is proposed that these laws are only particular cases of more general expressions having the particle size function raised to an exponent, i.e., the work exponent (We). Case studies illustrate the excellent prediction of the Wi - We models compared to the three mentioned laws, and, from the data, the corresponding general mill-sizing equation is derived. Key words: Grinding mills, Comminution, Work index, Mill sizing

Jan 1, 2003

By Victor A. Sowa

"Abstract - In 1938, a body of goethite and hematite was discovered beneath Steep Rock Lake near Atikokan, northwestern Ontario. This was at the time the largest and richest undeveloped iron ore body in North America. Mining began in 1944, fast-tracked by the needs of World War II, and through 1979 produced 79 Mt of 56.5% Fe. Production required the diversion of the Seine River, draining of Steep Rock Lake, building of a railroad, and a 25-fold increase of the local population. The mining project, at the time, was the largest project of its type undertaken in Canada. The current concepts of sustainable mine development and mine closures have advanced considerably since the period of operation and closure of the Steep Rock mines, and those operations would probably not have met current expectations of sustainability. However, some of the post-closure aspects of the mines provide illustrations of components of sustainability, which could form part of a basis for a post-mining sustainable land use plan. It is concluded that some of these components were successful in meeting current expectations of sustainable use, and although some aspects are unique to the circumstances at the Steep Rock mines, others could be applicable at other mine sites."

Jan 1, 2003

By Arthur E. Morris

Fifty years ago when Professor Yazawa began his career, the field of process simulation and modeling was in its infancy. Since then, tremendous progress has been made in our ability to model metal production flowsheets from mine to refined metal. This progress has come about by parallel developments in basic understanding of process chemistry and in computational techniques. This paper will review the progress made in process understanding and modeling in lead, zinc, and copper metallurgy from its inception to the present, and the role of Professor Yazawa&apos;s work in furthering this progress. Specific examples wi1\ be given for the sintering of lead concentrates, slag fuming, zinc concentrate roasting, flash smelting of copper, and pyro-extraction of zinc. Factors limiting further progress will be described.

Jan 1, 2003

By N Elith

Coal is a valuable energy source in New Zealand and has been mined from the West Coast for over 100 years. Stockton Mine is New Zealand&apos;s largest opencast coal producer supplying around 1.5 Mt of hard coking and thermal coal to international markets annually. The Stockton Plateau forms an extensive, gently inclined dip slope on erosion resistant Lower Eocene Brunner Coal Measures unconformably overlying basement rocks. The dip slope rises 600 - 1000 masl, locally dissected by fault scarps and present-day fluvial systems, some of which are deeply incised. Within the Mt Augustus Mining Block overburden comprises of a 30 - 40 m thick sequence of fluviatile, coarse to granular coal measure sandstones. High quality coking coal is preserved as a gently dipping, 10 - 12 m thick seam. High and sometimes very steep cliffs of jointed overburden shape the skyline escarpment, above steep forested slopes and gullies. As mining has progressed at Mt Augustus individual coal blocks are progressively becoming more technically challenging. This paper outlines the scientific approach taken by Solid Energy International and mining contractors to carefully unlock many thousands of tons of coal whilst protecting nearby flora and fauna from the impacts of dislodged rock and other blasting side-effects. The strategy involved: an expert-driven onsite risk assessment,formulation of a management plan to manage impacts,conducting an in situ vibration research program, andanalysis of results and operational designs to eliminate potential environmental problems.

Jan 1, 2003

By Chu Yong Cheng

The solvent extraction (SX) processes of the three pressure acid leach (PAL) nickel plants in Western Australia have been reviewed. The use of intermediate precipitation, solids/liquid separation and re-leach in the three W A nickel plants make these processes complicated and costly in capital and ?operation. The research work carried out by the SX group at the AJ Parker Cooperative Research Centre for Hydrometallurgy I CSIRO Minerals has led to the development of direct solvent extraction (DSX) processes to recover and purify nickel and cobalt from leach solutions. The simplicity of the process flowsheets and the expected savings in capital and operating costs are the major advantages of the new DSX processes over the reviewed processes. By using a new synergistic organic system in semi-continuous tests with a pilot plant leach solution (after iron precipitation) from BHP-BiIliton Stainless Steel Materials, the metal values (Ni and Co) together with zinc and copper were separated from the major impurities (Mn, Mg and Ca, together with Cl) in the first SX circuit. The co-extracted manganese, magnesium and&apos; calcium were easily scrubbed out. After stripping, the metal values (Ni and Co) together with zinc and copper were concentrated, resulting in a much smaller second SX circuit and equipment in the down stream processes. The extraction and stripping kinetics of the metals with the new synergistic organic solution were very fast. The extraction and stripping almost reached steady state within 0.5 minutes. Semi-continuous test work with a synthetic leach solution, a cobalt pilot plant leach solution from Peko Rehabilitation Project Pty Ltd and a synthetic solution to simulate a concentrated laterite leach solution from BHP-Billiton Stainless Steel Materials showed that manganese, calcium, copper and zinc can be effectively and efficiently separated from nickel, cobalt and magnesium by extraction, scrubbing and stripping. This led to the development of another DSX process using D2EHPA to recover nickel and cobalt from leach solutions.

Jan 1, 2003

By K Gordon, A Black

Two remediation strategies have been considered to reduce the levels of acidity and dissolved metals in acid mine drainage discharging from Sullivan Mine, West Coast, New Zealand. The oxidising strategy involves adding alkalinity and dissolved oxygen (DO) resulting in the precipitation of metallic oxides and decreased acidity. The reducing strategy involves removing DO, resulting in the precipitation of metallic sulfides, followed by addition of alkalinity to decrease acidity. Field remediation trials indicate a reducing system may be more effective for this site than an oxidising system. A residence time of only&nbsp;two hours in the limestone layer of a successive alkalinity producing system (SAPS) is sufficient to reduce acidity by 100 per cent, iron by 71 per cent, aluminium by 59 per cent, nickel by 38&nbsp;per cent&nbsp;and manganese by 26 per cent. The proposed remediation plan will likely include a series of SAPS, followed by an anoxic limestone drain, and settling ponds to capture any remaining precipitates.

Jan 1, 2003

By G. van Hout, D. Rahal

Caving is a mass mining method that is normally applied to large, low grade orebodies because of its low production cost and high capacity. However, equipment breakdown and poor draw management can cause mining costs to exceed that of all other mining methods. One way to minimize the effect of disruptions in the mining cycle is to use Mixed Integer Linear Programming (MILP) for long-term scheduling. This paper describes a MILP goal program which has the dual objectives of minimizing deviation from the ideal draw profile while achieving a production target. Schedule optimization is performed using a life of mine approach in which all production periods are optimized simultaneously. The underlying assumption being that material mixing in the short-term (between monthly optimization cycles) has a minimal effect on the long-term state of the panel. Schedule optimization is carried out using six general constraint types to model and control production. The constraint types define: deviation from ideal practice, panel state, material flow conservation, production quality, material flow capacity and production control. These constraints define production targets and drive production toward the ideal profile while maintaining correct mining practice. Application of the model using production scheduling data for a De Beers kimberlite mine. It is shown how different production control constraints regulate production from individual drawpoints as well as recovery of the ideal panel profile by implementing an optimised draw schedule.

Jan 1, 2003

By J. Autio, H. Malmlund

The excavation damage zone (EDZ) caused by drill and blast excavation consists of intense damage adjacent to the remaining half barrel of the blast hole, new fracturing induced by the blast and reactivation of pre-existing fractures. The properties of intense microfracturing adjacent to the half barrels of remaining blast holes are based on study of rock samples from ZEDEX-tunnel and it’s extension at Äspö and the Research tunnel at Olkiluoto in Finland. The new and reactivated fracturing is based on results of mapping of slots cut in the rock in ZEDEX-project. The zone of increased porosity adjacent to half barrels, which penetrates to a depth of some centimeters was studied by using novel 14C-PMMA method. The penetration of the radial fractures, which is an order of magnitude deeper, was studied by mapping using color penetrant. Results of EDZ studies carried out at Äspö HRL in Sweden and in Research Tunnel at Olkiluoto show that the properties of EDZ can be affected significantly by engineering design. The result imply that the additional pore volume caused by distinct fracturing around the blast holes caused by state-of-the-art smooth blasting technique could be of the same order as that of the damaged zone adjacent to the surface of the half barrels. Durch Bohr- und Sprengarbeiten entstandene Eigenschaften der Auflockerungszone: Die durch Bohr- und Sprengarbeiten entstandene Auflockerungszone besteht aus einem großen, an das Resthalbrohr des Bohrloches angrenzenden Schaden, neuer Rissbildung und einer Reaktivierung der bereits existierenden Risse. Die Eigenschaften einer immensen, an die Halbrohre der Restbohrlöcher angrenzenden Mikrorissbildung beruhen auf einer Studie über die aus dem ZEDEX-Tunnel gewonnenen Gesteinsproben und deren Fortsetzung im Untertage-Labor Äspö (Hard Rock Laboratory, HRL) in Schweden und im Forschungstunnel bei Olkiluoto in Finnland. Die neue und reaktivierte Rissbildung basiert auf den Auswertungsergebnissen der Schlitze, die bei dem ZEDEX-Projekt ins Gestein geschnitten wurden. Die Zone der vermehrten, an die Halbrohre angrenzenden Porösität, die in ein paar Zentimeter Tiefe eindringt, wurde anhand der neuen 14C-PMMA-Methode untersucht. Das Eindringen der etwas tiefer gelegenen radialen Risse wurde anhand eines farbigen Eindringungsmittels untersucht. Die in Äspö und Olkiluoto durchgeführten EDZ-Studien zeigen, dass die EDZ-Eigenschaften wesentlich durch Engineering Design beeinflusst werden können. Das durch Bohrarbeiten verursachte Hohlraumvolumen der Rissbildung um den Tunnel herum ist ähnlich wie das Hohlraumvolumen der Bruchzone um die Bohrlöcher herum. Caractéristiques d’une zone endommagée par le creusement résultant d’un creusement par forage et dynamitage: La zone endommagée par le creusement résultant d’un creusement par forage et dynamitage présente un endommagement intense adjacent au demi-cylindre restant du trou de mine, une nouvelle fracturation et la réactivation des fractures préexistantes. Les caractéristiques de la microfracturation intense adjacente aux demi-cylindres des trous de mine restants reposent sur l’étude des échantillons de roche en provenance du tunnel ZEDEX et de son extension au laboratoire souterrain d’Äspö (« Hard Rock Laboratory » ou HRL) en Suède et du tunnel de recherche d’Olkiluoto en Finlande. La fracturation nouvelle et réactivée repose sur les résultats du placement des rainures sur la roche dans le projet ZEDEX. La zone de porosité accrue adjacente aux demi-cylindres et pénétrant à une profondeur de quelques centimètres à fait l’objet d’études recourant à la nouvelle méthode 14C-PMMA. La pénétration des fractures radiales, considérablement plus profondes, a été étudiée par placement en utilisant un agent pénétrant coloré. Les résultats des études EDZ effectuées à Äspö et à Olkiluoto montrent que les caractéristiques de l’EDZ sont susceptibles d’être affectées de manière significative par la conception technique. Le volume vide de fracturation résultant du dynamitage autour du tunnel est du même ordre que celui de la zone concassée autour des trous de mine.service.

Jan 1, 2003

By A Black, A de Jo, J Cavanagh, J Harding

Acidic and metal-rich waters have been discharging from Sullivan Mine, West Coast, New Zealand since the closure of the mine during the early- 1990s. This has resulted in a decrease in pH from a background of 4.5 to 2.8 and an increase in metallic elements in nearby Rapid Stream. In addition to the chemical effects on Rapid Stream, a study of freshwater macro-invertebrates revealed the absence of most biota downstream from the discharge. An attempt is being made to use the Sullivan Mine as a case study of problem and remediation analysis.

Jan 1, 2003

By Harri J. Lehto, Marja I. Oja

"The purpose of grinding circuits is to produce a particle size distribution that has as much as possible the wanted particle size class. In practise, however, the production of the wanted size class is not at all as simple as it sounds. In the case of industrial minerals for example the end user may give very tight specifications for the particle size distribution and for the chemical composition of the product. This leads in many cases to a very demanding grinding process, if we want to reach and maintain these specifications. In other words, the required size distribution is not necessary the best possible for the chemical composition.Screen models aim to predict the size distribution and flow of the products when a feed size distribution, feed tonnage, and grade efficiency curve are known. The approach used in this study was to select the most suitable empirical model for classification. Suitability of the existing models has been evaluated and accuracy compared. The tests showed that best grade efficiency model was the Rosin-Rammler model.The performance of a screen was evaluated in order to minimize the amount of fine material in the screen overflow. The experiments were carried out using Derrick single-deck screen, first alone with recycling and then in the closed circuit with a rod mill using two different scales. The separate screen tests showed the expected behaviour of the grade efficiency curves. In the pilot tests the Leonard screen efficiencies stayed almost constant. This suggests that the screen works better in a milling circuit. However the loading of the screen turned the product of the mill coarser that helped screening. The grade efficiencies obtained from the pilot tests had the same general shape. The regression analysis of the pilot test runs did not give an acceptable correlation for the parameters. This suggests that pilot tests cannot be directly used to scale or to optimise industrial milling circuits. However they can be used to predict the trends of behaviour of an industrial circuit."

Jan 1, 2003

By M. Machina

Anew approach to the use of projectiles for rock fragmentation uses recently-developed technology to optimize projectile shape and composition to achieve the desired type of breakage. Projectiles can also be made of various materials, as determined by the requirements of downstream processes. This paper describes laboratory tests with an 21-mm (8-guage) gun, and field tests with a 60-mm cannon.

Jan 1, 2003