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By A. W. Diedericks

Rosh Pinah Zinc Corporation (RPZC) identified implementing a Mineral Resource Management (MRM) programme at the mine as a strategic incentive. The purpose of the programme is to optimize the economic value of the RPZC mineral resource, over the total value chain of the mine, taking expected macro economic conditions into consideration as well. With Mineral Resource Management still being a relatively young drive in the mining industry, information on the concept is relatively scarce. RPZC had several successes and problems with implementing such a concept and also still has a way to go before a complete Minerals Resource Management approach is implemented at the mine and entrenched as a working culture. The purpose of this paper is to: ?define a systems approach to implementing a Mineral Resource Management programme at a base metal mine ?indicate the specific MRM approaches taken at RPZC ?indicate the expected advantages of implementing a MRM approach ?measure the actions already taken against the systematic MRM approach, and indicate the advantages already captured ?indicate the way forward taking lessons learned into consideration ?indicate proposals to implement the MRM approach in the macro mining environment in South Africa.

Jan 1, 2003

By Elizabeth M. Ho

Oxidants are added in uranium leaching in acid media to convert iron(II) in solution to iron(III). Iron(III) has an important role in the leaching of uranium by acting as an electron transfer agent for the oxidation of uranium(IV) to uranium(VI). The oxidation of iron(II) to iron(III) in sulfate solutions using sulfur dioxide/oxygen (SO2/O2) was carried out under typical uranium leaching conditions (pH 1-2, 20-50°C) to confirm literature trends and this work was then extended to the use of SO2/O2 in the leaching of uranium ore. The oxidation rate was found to be dependent on the initial SO2/O2 volumetric ratio and the oxygen mass transfer rate, but was independent of the initial iron(III) concentration above about 200 ppm at pH 2. The presence of 55 ppm organic extractant (Alamine 336) decreased the reaction rate. The oxygen mass transfer coefficient (kLa) for the mixing tank system was measured and was found to decrease with increasing solids density in a 1 g L-1 MgSO4.7H2O solution.

Jan 1, 2003

By G. Belardi, N. Shehu, L. Passeri

"This paper illustrates the possibilities of applying what is essentially a physical soil-washing technique for treatment of soil contaminated by semi-volatile hydrocarbons in order to reduce the level of pollution to that permitted by Italian regulations.The ground around a factory producing lubricating-oil additives consists of silty-sandy soils which have long been contaminated by heavy hydrocarbons, especially branched alkyl benzenes and naphthalene derivatives. Pollution is particularly marked in some zones (hot-spots) where Total Petroleum Hydrocarbon (TPH) values are as high as 7000 ppm. The hydrogeological characterization showed the presence of a gravely soil in a sandy/silty matrix, with big stones making preferential paths to the water circulation. The permeability is 10-5 m/s and the water-table occurs at about 3 m below ground level.After laboratory and pilot-scale studies on representative samples of in-situ soils with TPH between 2700 and 7000 ppm a flow-sheet is proposed for reducing TPH values below the acceptable limits in Italy, namely 700 ppm for hydrocarbons with more than 12 carbon atoms and less than 250 ppm for those with fewer.On the basis of indications provided by laboratory tests a mainly physical treatment process of soil washing has been developed. This is used to clean-up soil from a site polluted by non-volatile hydrocarbons with a high TPH value. The process involves a high-density attrition stage followed by wet screening at 0.5 mm and then wet-gravity separation of the minus 0.5 mm fraction in the centrifugal field.The gravity separation products consist of a light fraction with particle size finer than 15 micron which contains most of the pollutants, and a heavy coarse fraction with TPH values conforming to the limits set by Italian regulations (less than 700 ppm hydrocarbons whose structure contains more than 12 C atoms, and less than 250 ppm of hydrocarbons with less than 12 C atoms)."

Jan 1, 2003

By Kazimierz Trybalski

"Simulation methods have a big potential in the studies and analyses of complex technological processes and schemes. The simulation method used jointly with flow diagrams and related transmittance models allows describing and analysing dynamic characteristics.The paper presents results of simulation analysis of dynamic characteristics of ore dressing system, called closed circuit mill-classifier-mill. Such systems are widely used in ore processing plants. The system was analysed as a typical system with material feedback, to establish its dynamic characteristics.Flow diagram conforming to the technological scheme is presented in a figure. Transmittances shown in the scheme are defined as follows:GMP - transmittance of rod mill,GP, KZ, GW, KZ - transmittances of overflow and underflow streams of spiral classifier, respectively,GMK - transmittance of ball mill,GT - transmittance of underflow stream from classifier to ball mill,GU, MP, GU, MK - fraction transmittance of outflow streams of rod and ball mill, respectively, summed up at classifier input.Taking into account, in base of carried out analysis the transmittance forms of individual system elements. The calculations are based on numeral forms of transmittances of individual blocks, defined through industrial experimentation.Step input function to rod mill was assumed to be a step of mass ore flow rate to the mill. Responses are defined as product densities.This figure demonstrates the way of input signal transmission by consecutive elements of the system and shape of these elements' responses. It can be noticed that step signal undergoes gradual change from the stream of the first order to those of higher and higher orders as a distance from process leading edge increases. Simultaneously, the impulse signal is subject to systematic smoothing and decay. From the technological point of view, the most important is response stream in point 5 (on the above figure) that characterises classifier overflow, which is a final product of this system."

Jan 1, 2003

By George S. Dulikravich

An advanced semi-stochastic algorithm for constrained multi-objective optimization has been adapted and combined with experimental testing and verification to determine optimum concentrations of aJ10ying elements in heat-resistant and corrosion-resistant H-Series austenitic stainless steel alloys. The objective was to simultaneously maximize a number of alloy's mechanical properties. This research will result in a rigorous tool for the design of high-strength H-Series steels and other types of alloys unattainable by any means existing at the present time. Such a material-by-design tool will also be able to reduce or minimize the need for the addition of expensive elements such as Cr, Ni, Co, Nb, Ti, V, etc. and still obtain the optimum properties of an aJ1oy.

Jan 1, 2003

By Charlene Gokhale

Geopolymerisation has emerged during the last few years as an industrial and ecological approach to construction and waste management. By utilizing waste materials and their reactive properties, it is now possible to create geopolymers systems that not only mechanically durable enough to be used as construction materials but are also potential stable immobilisation systems for toxic waste. Previous studies by Van Jaarsveld et al. (1997) and Van Jaarsveld et al. (1998) have reported on the numerous applications of geopolymers in the immobilisation of toxic metals. Research into the possible utilisation of geopolymers as an encapsulation media for organic waste has however been rare. This paper therefore provides an insight into the possible utilisation of geopolymers as a binder for hazardous organic materials.

Jan 1, 2003

By E. V. Manlapig, M. C. Harris

"The complexity of the flotation process has made the identification of an appropriate model structure for the predictive simulation of flotation circuits far from obvious. Work performed under the auspices of the AMIRA P9 flotation program has indicated that the metallurgical performance achieved from a flotation cell arises from the interaction of two essentially independent property classes, namely the cell operating conditions and the properties of the cell feed stream. These observations have led to the development of a model structure that associates a constant set of flotation parameters to the streams of the circuit, which are transformed into a flotation response depending on the operating conditions within the flotation cell.A variety of alternative model structures exist within the literature which do not make this distinction between cell and stream flotation properties, and many of these models are in widespread use for flotation optimisation and design studies, both in industry and academia.In this paper, circuit survey and laboratory batch flotation data collected from an industrial flotation circuit are analysed. The data demonstrate that streams in an industrial flotation circuit exhibit varying particle floatability – concentrate streams typically float faster than tailing streams (Figure 1(a)). This floatability, however, is generally conserved around the various units within the flotation process (i.e. the effective floatability of the combined feed and product streams of a unit is equivalent (Figure 1(b)))."

Jan 1, 2003

By A. D. Shuloyakov, G. A. Finkelstein, V. I. Kurets, A. K. Vedin

"In disintegrating solid ores with mineral values disseminated in them, one of the principal tasks is to selectively separate valuable mineral particles from the matrix in which they reside, striving at the same time to keep their natural shape and size as intact as possible.The conventional mechanical disintegration methods do not meet this most important requirement in full. The other major objective here is to reduce electric power consumption during the fragmentation stage, since up to 65 per cent of the total power consumption at concentrators processing ores of non-ferrous, ferrous, rare, and precious metals is spent on disintegration steps.Numerous experiments conducted on dozens of ore types (tin, tungsten, and many others, as well as on rock containing diamonds, rubies, emeralds, etc.) have invariably demonstrated by far superior integrity of mineral values as compared with that obtained by mechanical as well as other types of disintegration.However, the process remains as power-intensive as ever which is due to the imperfect nature of the electro-technical devices that convert the network electric current into high-voltage electric impulses responsible for the disintegration process.The maximum capacity attained in disintegrating the hardest materials from 40 mm to 2 mm size in a single operating chamber with four high-voltage electrodes does not exceed 1.0-1.5 t/h. Attempts at increasing the number of electrodes and the capacity of the operating chamber have failed so far because of high overall dimensions and mass of the electrical part of the installation supplying the chamber with pulsating current, as well as of the commutation requirements. At the same time, a number of overseas operations have reported a significant breakthrough in their attempts to reduce dozens of times the overall dimensions and mass of the discharge impulse generating installation (EIS), which enables us to contemplate to increase the capacity of the EIS at least ten times in the nearest future. Yet, even with the currently achieved capacity of the EIS, these installations have found wide use in geological surveying, precious and semi-precious stones production, in grinding super hard materials, etc., since they provide spectacular selectivity of disintegration and thus the integrity of valuable mineral crystals."

Jan 1, 2003

By J. J. Kellar, W. M. Cross, H. Du, C. D. Struckman, D. A. Boyles

Silane coupling agents have been used in the filler industry for years. One particularly unique feature is the ability of the coupling agents to enhance the adhesion between filler and polymer matrices. This paper will review the use of coupling agents for polymer matrix composite applications and discuss a new approach to coupling agent chemistry, namely, direct formation of a silicon-carbon non-hydrolyzable linkage between glass and coupling agent. The grafted silane monolayers were evaluated by infrared spectroscopy to ascertain their surface coverage and relative stability. Finally, composite specimens were fabricated and their mechanical properties were compared with traditional silane coupling agent treatment.

Jan 1, 2003

By F Battaglia-Brunet, D. H. Morin, Foucher S. ’

In the mineral-processing field, bioleaching of metal sulphide concentrates is currently operated in very large mechanically agitated tanks. Such bioreactors have considerable requirements in terms of power consumption for mixing, aeration and heat transfer. The use of slurry bubble column, where the particles are suspended by gas motion as well as by liquid upward flow, could be an alternative to achieve bioleaching in more economical conditions. In order to compare these two techniques, a unit of stirred reactors in cascade and a bubble column were comparatively operated at laboratory scale in the bioleaching of a pyrite concentrate. For both pieces of equipment, experiments were performed not only in batch mode but also in continuous conditions.

Jan 1, 2003

By M Pratt

For up to 75 years large scale coal mining has been carried out within the Latrobe Valley region of Victoria. Withdrawal of groundwater from Tertiary aged sediments within the Latrobe Valley is essential to allow coal mining to proceed to depth. Water within the overburden layers, coal seams and interseams must be drained to avoid flooding during the mining process. The pressure in deeper aquifers must also be lowered to avoid floor heave, batter instability, and to maintain safe operating conditions as the mines develop in size and depth. The cost-effective management of the groundwater systems at and adjacent to the mining operations in the Latrobe Valley is essential to enable the efficient utilisation of the coal resource whilst minimising the environmental impact of this major industry in rural Victoria. Large-scale depressurisation and dewatering programs within the Latrobe Valley mines are managed through the use of detailed groundwater management plans. These incorporate:an extensive monitoring network which extends up to 60 kilometres from the mines; detailed mine scale and regional groundwater and hydrogeological models; and established operational procedures aimed at minimising capital and operational costs associated with the mine groundwater systems. Groundwater extraction system optimisation programs have been introduced into two of the mines with the aim of reducing extraction rates, improved risk management, and reducing operational costs by approximately whilst not compromising mine safety. This paper reviews the aquifer depressurisation and mine dewatering operations of the Latrobe Valley mines and illustrates the techniques utilised to ensure that high artesian pressures do not adversely impact on the mining operations.

Jan 1, 2003

By R. Hamilton

"Louvicourt mine began operation in 1994. It is located in northwestern Quebec, 20 km east of Val d’Or. The mine is owned by Aur Resources (30%), which operates the mine, Teck/Cominco (25%) and Novicourt (45%). By the end of 2002 there were approximately 280 employees working on the site, including contractors. Production averages 4300 tons per day, working a massive sulphide body located between 415 m and 920 m underground.Maintenance expenses represent 27% to 29% of the operating costs, and the maintenance personnel represents 34% of the total workforce (including electrical, mechanical and concentrator maintenance staff). Considering these figures, in addition to capital costs and indirect costs, such as energy (electricity, fuel, gas, etc.), it is worthwhile to pay attention to how things are done in order to protect such investment. Every task performed to help understand the impact of Louvicourt’s practices must to be seen as an investment in the reliability of its operation."

Jan 1, 2003

By Stephen Slot Odgaard, Simon D. Taylor

Phase One of Copenhagen Metro opened on October 19th, 2002 and is already a great success. 11 stations are open and Phase Two with 6 additional stations will open during 2003. Phases One and Two include 21 km dual track, whereof 10 km is in tunnel. 17 stations (six deep, three shallow, and eight above ground) will service passengers with trains running at 90 seconds intervals. This paper will discuss the various aspects of the Metro, where construction methods include TBM bored, NATM, Cut & Cover, Secant Piles and Diaphragm Walls.

Jan 1, 2003

By A. Haque

The shear behaviour of infilled joints produced from ordinary gypsum plaster (gyprock) and bentonite was investigated in the laboratory under Constant Normal Stiffness (CNS) conditions. Shear tests were performed on saw-tooth profiles having Joint Roughness Coefficients (JRC) of 4.75 and 9.25 under an initial normal stress (sno) of 0.30 to 1.10 MPa, and at a normal stiffness (kn) of 8.5 kN/mm. Test data under the same sno and infill thickness to asperity height ratio (t/a) were analysed for two different sets of JRC. The peak shear stress plotted against the t/a ratio under constant sno revealed an increase in peak shear stress with the increase in JRC, up to a t/a ratio of about unity. The effect of roughness on the peak shear stress was observed to be minimal when the t/a ratio exceeded 1.40. A mathematical model for the prediction of peak shear stress due to the increased infill thickness has been developed based on a hyperbolic stress-strain relationship and energy balance principles. The model predictions are in good agreement with the laboratory observations. Le comportement de cisaillement des joints remplis produits à partir de plâtre ordinaire et de bentonite a été étudié dans le laboratoire sous des conditions de rigidité normales constantes. Des essais de cisaillement ont été réalisés sur des profils en dents de scie ayant des coefficients de rugosité des joints (CRJ) variant de 4,75 à 9,25 sous un effort normal initial (sno) de 0,30 à 1,10 MPa, et une rigidité normale (kn) de 8,5 kN/mm. Le résultat des essais conduits sous la même contrainte et épaisseur de remplissage au rapport aspérité/hauteur (t/a) ont été analysés pour deux ensembles différents de CRJ. La variation de l'effort de cisaillement maximal contre le rapport t/a sous une contrainte normale constante a indiqué une augmentation de l'effort de cisaillement maximal avec l'augmentation du CRJ, jusqu'à un rapport de t/a proche de l'unité. L'effet de la rugosité sur l'effort de cisaillement maximal a été minimal quand le rapport t/a a excédé 1,40. Un modèle mathématique pour la prévision de l'effort de cisaillement maximal dû à l'épaisseur accrue du remplissage des joints a été développé sur la base de la variation entre contraintes hyperboliques et déformation et sur des principes de bilan énergétique. Les prévisions du modèle sont en bon accord avec les observations de laboratoire. Das Scherverhalten in mit gewöhnlichem Gips und Bentonit gefüllten Klüften wurde im Labor unter Bedingungen konstanter Normalsteifheit (CNS) untersucht. Scherversuche wurden durchgefürt für Sägezahnprofile mit Werten des Fugenrauhigkeitskoeffizienten (JRC) von 4.75 und 9.25 unter Normalspannungs-werten (sno) von 0.30 bis 1.10 MPa, und bei Normalsteifheit (kn) von 8.5 kN/mm. Testresultate für gleiche Werte von sno und Verhältnis Fülldicke zu Rauhigkeit (t/a) wurden untersucht für zwei verschiedene Werte von JRC. Die Beziehung zwischen maximaler Schubspannung und und t/a Verhältnis unter konstantem sno zeigte einen Anstieg der maximalen Schubspannung mit zunehmendem JRC, bis zu einem t/a Verhältnis von etwa 1.0. Der Einfluss der Rauhigkeit auf den Maximalwert der Schubspannung war minimal solange das t/a Verhältnis den Wert von 1.40 überstieg. Ein mathematisches Modell wurde entwickelt für die Vorhersage der Schubspannung die von zusätzlicher Fülldicke erwartet werden kann, ausgehend von einer hyperbolischen Spannungs-Dehnung Beziehung und dem Energiegleichgewichts-prinzip. Die Modellvorhersagen zeigten gute Uebereinstimmung mit den Laborbeobachtungen.

Jan 1, 2003

Despite mineral sand occurrences having been noted since the 1970s, the Wemen North Mine is the first operation to commence commercial mining within the inland Murray Basin. The deposit was discovered in the 1990s and, following lengthy resource development, mining commenced in 2001. This initial mine was established as a pilot operation to test the commercial viability of mining in the Murray Basin, with subsequent expansions planned if the mine proves successful. The deposit lies beneath arable farmland close to the Murray River and is hosted by Pliocene marine sands, with a geometry resembling a classical beach strand placer. The operation utilises traditional dry mining overburden removal techniques, with ore mining carried out using a floating dredge and concentrator. This paper looks at the geology of the Wemen North deposit, the mining techniques and challenges as well as grade control practices employed to mine this palaeo-beach placer deposit.

Jan 1, 2003

By J. E. Dutrizac

The behaviour of the lanthanide elements during the precipitation of sodium and potassium jarosites at 98oC from sulphate media was systematically investigated. The lower atomic weight lanthanide elements (La to Gd) are characterized by the limited solubility of their alkali-lanthanide sulphates, such as NaNd(SO4)2?H2O, which commonly contaminate the jarosite precipitates. Hence, single phase jarosite-type compounds were precipitated only from solutions containing <0.4 g/L of the La to Sm lanthanides. The sulphates of the heavier atomic weight lanthanide elements (Tb to Lu) have significantly higher solubilities such that solutions containing up to 10 g/L of the individual lanthanides could be investigated without the precipitation of alkali-lanthanide sulphate species. Even at the highest lanthanide concentrations, however, none of the jarosite precipitates incorporated more than 0.3 wt% of any of the lanthanide elements. Comparable levels of lanthanide incorporation were noted in both Na-jarosite and K-jarosite. Although the mass of the jarosite precipitate increased with increasing ferric sulphate concentration or with increasing pH, the extent of lanthanide incorporation was not significantly affected. Clearly, the trivalent lanthanide elements do not substitute extensively for trivalent iron in the jarosite structure. This behaviour likely reflects the significantly lower hydrolyzability and larger size of the trivalent lanthanide ions relative to ferric ions.

Jan 1, 2003

By Guy Xueyi

The environmental impact assessment of the Imperial Smelting Process for metallic zinc and lead production in Shaoguan Smelter, China, was carried out by the life cycle assessment method. The detailed inventory analysis of the Input/Output in the process during 1998-2000 was conducted and the allocation was done among the main products of zinc, lead and sulfuric acid, according to the system expansion and substitution principle, The environmental impacts were assessed by using the following five Eco-indicators: Gross Energy Requirement (GER), Global Warming Potential (GWP), Acidification Potential (AP), Heavy Metal Toxicity&apos; (HMT) and Solid Waste Burden (SWB). The results from this study are useful to address the environmental situation of the technology practice in this smelter, and provide a scientific basis for the further improvement.

Jan 1, 2003

By John Waggoner, Steve Klein, John Townsend, Jay Arabshahi

The Riverside Badlands Tunnel is a 13 km (8 mile) long segment of the Inland Feeder Project. This 3.65 m (12 ft) finished diameter water tunnel presented many challenges that had to be overcome to take the project from concept to reality, not the least of which were the diverse ground conditions. Construction of the tunnel was carried out by a single tunnel boring machine (TBM) in one tunnel drive. The project is considered a success due to the accurate baseline established for the ground conditions; the approaches used to mitigate adverse conditions; and the appropriate use of TBM excavation methods, which achieved rapid advance rates despite the challenging ground conditions.

Jan 1, 2003

To simplify programming, image analyzers commonly measure either linear intercepts or the areas of particles and grains to determine liberation based on polished section mounts. However, the concentration of minerals by flotation is based on reagents that interact with the exposed surfaces of the minerals. Thus, it is often perceived that image analyzers should measure the perimeter of the mineral of interest in the ore particles. A comparative liberation study of thirteen samples collected from a flotation plant processing a complex base metal sulfide ore showed that the liberation of the ore minerals determined by area measurements is very similar to the liberation determined by the exposed perimeters. The liberation determined by exposed perimeters is more appropriate only for those cases where the mineral texture is so complex that it is retained in the small particles generated in conventional grinding operations. Key words: Mineral liberation, Flotation, Image analyzers

Jan 1, 2003

By M Logsdon, T R. Clark, T I. Mudder

Oxidation of pyrite and other metal sulfides is accelerated by the activity of acidophilic iron- and sulfur-oxidising microorganisms. The ideal biocide for controlling biocatalysed acid rock drainage (ARD) would be inexpensive, inhibitory toward sulfide-oxidising bacteria at low concentrations, relatively non-toxic toward non-target organisms, degradable in the environment outside the zone of application, stable and long-lived in the impacted environment, sufficiently mobile to penetrate into piles of waste rock or tailings, and effective regardless of the metal sulfides present. A potent agent for combating ARD that fits these criteria is the thiocyanate anion (SCN-). The objective of this study was to determine the effectiveness of thiocyanate in controlling or preventing ARD within several types of sulfidic waste rock and tailings. Results were evaluated within a context encompassing process water and solids management strategies employed at different precious and base metal mines. Sulfidic rock was treated with solutions of potassium thiocyanate and subjected to accelerated weathering tests in lab-scale humidity cells, trays, and columns. Certain tests also utilised solid phase copper thiocyanate (CuSCN) to evaluate a ærelease on demandÆ strategy. Leach solutions were analysed for parameters indicative of ARD including pH, redox potential, conductivity, acidity, sulfate, iron, and certain heavy metals. Two larger scale field tests were also initiated by personnel at separate mines using, in the first case, ore containing a pyritic component in large columns and, in the second case, waste rock containing base metal sulfides in lined pits. Humidity cell tests showed low concentrations of thiocyanate solution applied to pyritic waste rock could reduce ARD formation by 90 per cent or more compared to untreated controls, with the residual release of ARD components (eg sulfate, Fe, acidity) probably reflective of strictly chemical oxidation of the sulfides by molecular oxygen. Thiocyanate applied at a concentration of 22 mg/kg to waste rock from a base metal mining operation in large laboratory scale columns reduced acidity and sulfate release by 75 per cent to 80 per cent compared to untreated controls. This extent of reduction in ARD may not meet discharge water quality criteria, but has the potential to significantly reduce lime consumption and sludge production in a conventional neutralisation facility. The use of a solid-phase metal thiocyanate compound (CuSCN) at a dosage of 194 mg/kg pyritic ore resulted in the following per cent reductions in leach solution parameters in comparison to controls: sulfate (78 per cent), acidity (93 per cent), dissolved Fe (99.4 per cent), and dissolved arsenic (99.9 per cent). This compound has the further advantage of being relatively stable until needed, dissolving only in the presence of an acidic and oxidising ARD solution. If this line of investigation progresses favorably, it offers the possibility of an ARD prevention technique that may be applicable in some settings. Mine-site pilot scale tests with pyritic ore resulted in reductions in sulfate (56 per cent) and Fe, As (66 - 68 per cent). In sum, thiocyanate at relatively low concentrations dramatically reduced ARD from sulfidic rock in a simulated heap. The pilot test using waste rock containing base metal sulfides has begun only recently. A preliminary process design and cost estimate was made for fullscale application of thiocyanate to waste rock at a hypothetical gold mining operation producing 5000 tpd of ore and 10 000 tpd of sulfide containing waste rock. The combined capital and operating costs for the full-scale thiocyanate application facility were about $US 0.25/tonne of waste rock and $US 0.50/tonne of ore. Although thiocyanate is readily available commercially, it also occurs in process solutions associated with certain types of mining processes. Such solutions after selective treatment might be recycled to sulfidic waste rock or tailings, rather than being treated for thiocyanate degradation.

Jan 1, 2003