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By K Ehrig

Two irrefutable facts in geology and metallurgy are: ore deposits are comprised of variable mixtures of minerals which are systematically distributed throughout the deposit, and mineralogy exerts the primary control on metallurgical performance. If the distribution of process critical minerals can be quantified and mapped, then a logical assumption is that metallurgical performance can be predicted across the deposit.Olympic Dam is a +9 billion tonne Fe-oxide Cu-U-Au-Ag deposit which is hosted entirely within a magmatic-hydrothermal breccia complex consisting of over seventy ore and gangue minerals. Each has a unique set of metallurgical performance properties. Fortunately, 15 of the 70 minerals accounts for >98 per cent of the total rock mass.The mineral mapping journey commenced in the early drilling days shortly after the discovery of Olympic Dam in 1975. Geologists quickly recognised that the copper-iron sulphides had a predictable zoned distribution. However, geological models reflected the presence or relative abundances, not quantitative concentrations, of the minerals. This type of mineral mapping remained relatively unchanged for ~20 years and was of limited use outside of geology.Several things changed during the mid-1990s: assaying costs decreased significantly, instruments capable of automatically measuring mineralogy became readily available, the recognition of two quantifiable relationships at OD (ie mineralogy is a function of chemical composition (ie assays), and metallurgical performance is a function of assays, mineralogy, texture and process conditions. The linkage of metallurgical performance to mineralogy and mineralogy back to assays allows for every assayed sample in the resource model to be assigned mineral concentrations and metallurgical performance predictors. At Olympic Dam, block models (ie 3D maps) are routinely produced for 27 elements, density, 15 process critical minerals and greater than 50 metallurgical performance variables. These geometallurgy-enabled resource models are used for mine planning, process plant design and process optimisation studies. *This is an abstract only. No paper was prepared for this abstract.*

Sep 5, 2011

By D E. Tennant

In the fields of geotechnical engineering and slope management, various software packages are used to assess the behaviour or propensity for a slope to fail. Traditional kinematic analysis calculates the probability of failure of design sectors with respect to dominant structural set orientations. A novel methodology is provided here to view potential hazardous slope behaviour in 3D, allowing engineers to make informed decisions regarding various pit slope geometries. Apparent dips are calculated for every point in space with respect to every slope orientation of the entire pit surface/design, specifically in reference to bench and inter-ramp planar failure mechanisms. Implementing a proactive approach to slope design will not only lead to early mitigation of risk but can also add direct value by enhancing or improving upon slope angles for earlier access to ore. From a safety perspective, identification of unfavourably oriented slope geometries can be dealt with before failure occurs. This methodology relies on a strong understanding of the existing rock mass anisotropy, particularly behind the face, thereby removing some of the uncertainty surrounding pit design as well as presenting engineers with an additional means to manage risk.

Nov 29, 2022

By Macaulay J

The recovery of gold from cyanide liquors is frequently effected by using activated carbon. Process economics however require non destructive methods of gold extraction from the carbon so that it may be recycled.Stripping at atmospheric pressure usingthe method of Zadra et al(l) suffers from the disadvantage of unfavourable kinetics with strip times of the order of 48-72 hours. Subsequent research has led to development of processes which strip the gold more rapidly namely: A.A.R.L. process, (2,3) organic solvent (4,5,6) and pressure stripping (7,8)This paper reports on a development of the pressure stripping technique in which stripping and electrowinning are carried out at elevated temperature and pressure.

Jan 1, 1984

By Reid JG, Cutfield S

Considerable quantities of dissolved nickel are lost in the waste liquors from the QNPL nickel treatment plant. Cementation, precipitation and ion exchange techniques were investigated to reduce this loss. Ion exchange was the most successful of the procedures studied and a process for recovering nickel from stripped ammoniacal process liquors was developed in the laboratory and scaled up to plant flow volumes. The system developed uses a carboxylic ion exchange resin operated in a completely ammoniacal cycle. The regenerant is itself regenerable using existing plant, thus the only loss is the stoichiometric value of NH4+ required to displace the exchanged cations from the resin. Existing plant sand/anthracite filter beds have been adapted for use as resin columns containing 3 cubic metres of resin capable of treating effluent at a flow rate of 6000 litres/min.

Jan 1, 1978

By A He, J Li, J Pan, J Clout

The removal of sulfur from SO2 containing flue gas is improved by adsorbing SO2 into solution with manganese ions as catalyser, however, burnt lime slurry has to be added to modify solution pH and the CaSO3 by-product is of low economic value. In this paper a novel one step process for simultaneous manganese leaching-desulfurisation of flue gas is presented. An investigation of the effect of process parameters included flow rate and SO2 concentration in flue gas, adsorbing time, solution to solid mass ratio, leaching time, and their impact on the oxidation and removal of SO2 from flue gas. The catalysing mechanism of manganese ions on the oxidation and SO2 removal was demonstrated by calculation of the species originating from manganese ions and SO2 in the solution according to solution chemistry. SO2 removal in the adsorbing solution took place at pH 5 - 6, where manganese ions dominantly occurred as Mn2+, and the chain reactions for oxidation of SO2 starting from HSO3- were improved by the presence of Mn2+. SO2 bearing flue gas was effectively desulfurised by leaching rhodochrosite (MnCO3), with desulfurisation of the flue gas and modifying the solution pH being achieved simultaneously, and MnSO4 of high economic value recovered from the leachate. 85 per cent manganese leaching and over 70 per cent desulfurisation of the SO2-bearing flue gas were achieved with only one adsorption stage under optimum conditions.

Jan 1, 2004

By G Guy, J Summerville

Over the past five years in coalmine slope evaluation the application of 3D modelling has increased significantly as software has become more user friendly but also areas requiring evaluation have become increasingly complex. Often simplistic 2D Limit Equilibrium modelling and analysis has been poorly used to solve slope stability issues by back analysis and subsequent forward predictive analysis. A plane strain condition with slope movement perpendicular to the slope strike is assumed where in reality the problem is more complex. This often leads to a misinterpretation of the failure mechanism because the failure mechanism being modelled in 2D does not generally represent the actual failure mechanism observed in the pit, with 2D modelling often oversimplifying a slope. This paper presents a case study where the initial slope assessment and remedial design evaluation was undertaken as a 2D Limit Equilibrium model which led to an overly conservative and costly remedial solution being implemented. Subsequent modelling of the slope using both 3D Limit Equilibrium and Finite Element methods were able to provide a better understanding of the structural complexities associated and correlate well with slope monitoring data to create a more realistic outcome.

Nov 29, 2022

By G Chitombo, G Lewis

The knowledge of the expected run of mine (ROM) fragmentation during the feasibility study of a green field site is essential for the design of downstream crushing and milling processes. However,the prediction of blast fragmentation can be a challenging process due to the uncertainty related to the blast design and rock mass parameters. In general,a number of possible blast designs are considered in a feasibility study,with factors such as bench height and blasthole diameter influencing the design. Rock mass parameters are normally derived from a limited number of geotechnical diamond drill cores. Although diamond drill core can provide detailed information concerning intact rock strength (unconfined compressive strength and point load),it provides limited structural information to predict the in situ block size distribution of the rock mass. The in situ block size is an essential input to the prediction of the fragmentation distribution, in particular the coarse end. This paper outlines the methodology of blast fragmentation modeling undertaken for a green field feasibility study at the Riska gold deposit in Indonesia. The favoured milling process for the feasibility study was dump leaching,with no crushing of the ore material extracted from the pit. For this reason,blast fragmentation was a critical issue to be addressed by the study. A range of blast designs were considered with bench heights and blasthole diameters ranging from 4 m to 7 m and 76 mm to 102 mm respectively. Rock mass data was obtained from 19 diamond drill cores across the deposit (total drill length approximately 2200 m). Intact rock strength was estimated from qualitative strength descriptors,while the in situ block size distribution of the rock mass was estimated from the Rock Quality Designation (RQD) of the core. The methodology of fragmentation prediction involved a number of steps including the estimation of rock mass parameters from diamond drillhole data including the estimation of the in situ block size, delineation of blast domains within the deposit,and the assessment of the impact of various blast design parameters and rock mass variation on the predicted fragmentation distribution. The modelling process for the Riska green field site highlighted the need for additional rock mass data to be collected post feasibility stage and once the development of the mine commenced.

Jan 1, 2004

Mid-ocean ridges host approximately 65 per cent of about 100 known sites of high-temperature venting and polymetallic sulfide deposits; most of them are located at the East Pacific Rise (EPR), while more diverse mineralisation styles occur at the Mid-Atlantic Rise (MAR). Seafloor hydrothermal activity at the EPR are related to MORB while different substrates, including MORB and ultramafic intrusive rocks, are associated with æblack smokersÆ at the MAR. Depth of hydrothermal activity ranges from 0.7 to 4.3 km. High-temperature vents precipitating Cu-Fe sulfides (chalcopyrite and isocubanite, rare bornite), pyrrhotite, pyrite (¦ marcasite), and sphalerite, and low-temperature edifices precipitating marcasite (with pyrite), sphalerite, barite, andsubordinate chalcopyrite (pyrrhotite and isocubanite are absent) occur in both environments. There are considerable differences in Fe, Zn, Cu, Ag, Au and trace element contents in ores and in theFeS contents in Zn-sulfides in these deposits. Acomparison with anhydrite and sulfide minerals precipitating from modern black smoker fluids sulfide reveals many similarities but also some important differences. Fluids with salinity values above and below that of seawater at 400¦C down to 130 - 170¦C deposited sulfide minerals. Mantle-derived He prevails in fluids trapped by sulfides in EPR 9¦N and 21¦N hydrothermal systems. Hydrothermal fluids in MAR and back-arc systems are richer in radiogenic 4He. The sulfur isotope composition varies in the different hydrothermal fields and within zones of a chimney. EPR sulfides display narrower range of d34S values, while MAR and back-arc sulfides can bedepleted and enriched in the heavier d34S isotope. The most important finding is that fluid temperature, salinity, R/Ra ratios and d34S values ranged more significantly in the polymetallic sulfide deposits than when measured directly on venting fluids. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By P Audet, D R. Mulligan, D Doley

This analysis attempts to reconcile existing ecological theories, rehabilitation planning goals and implementation constraints in the form of a rehabilitation paradigm that considers potential and pragmatic ecosystem transformation pathways. The framework prioritises multiple developmental scenarios for post-disturbed landscapes within a continuum of ecological outcomes. A feature of the framework is that ænovelÆ ecosystems and agro-ecosystems, having a range of commercial and societal values, are valid outcomes spanning the conceptual divide between the ecological functions of under-rehabilitated versus re-instated ænaturalÆ landscapes, especially in a changing environment. Landscape suitability analyses are considered to be fundamental to the incorporation of regional landscape and climate in the implementation of land rehabilitation and management strategies. Altogether, the paradigm could facilitate the identification of widely pertinent rehabilitation goals having direct implications at the regional scale of restoration ecology and acceptance of the need for ongoing commitment to the management of disturbed environments.CITATION:Audet, P, Doley, D and Mulligan, D R, 2012. Can ænovelÆ ecosystems offer suitable rehabilitation alternatives for post-mined landscapes?, in Proceedings Life-of-Mine 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By D M R Stone

Failings di,posal presents many challenges at metal mines in Peru where the extreme relief yields very little useable land area. These challenges are amplified by other hazards such as the high seismic environment, high rainfall, and frequent debris torrents down the steep hillsides. As a result many mining operations have resorted to in-river disposal of mill tailings. This paper presents a case history of one underground metal mine located in the high Andes mountains of Peru where in-river disposal of tailings has been used for some 30 years. The paper outlines a comprehensive engineering study that was aimed at increasing the utilisation of tailings disposal underground. The scope of this study included modifications to the grinding and flotation circuits to produce a high sulphide and low sulphide tailings for underground and surface disposal respectively: mapping and cataloguing of abandoned stopes for hackfilling: modifications to the existing backfill system to improve icliahility and throughput, and a preliminary evaluation of alternatives Such as silicated and paste fills.

Jan 1, 1998

By M McCarthy

Attraction, recruitment and retention of quality mining engineers is becoming increasingly difficult for many mining companies. Part of the problem is attracting young professionals, especially given the decline in graduating engineer numbers, and the other is balancing the new engineerÆs development with business needs. The evolution of the graduate program at Olympic Dam over the last five years has resulted in substantial benefits for both the engineer and the company. The program has developed to provide structured exposure to key areas of the mine enabling new engineers to step into vacated roles as the need arises. The pool of quality engineers generated by the graduate program is a buffer against high industry turnover and helps reduce future recruitment expenditure. Olympic DamÆs program goes beyond conventional recruitment of graduate engineers. Innovations designed to improve intake include the employment of graduate engineers as well as final year students, retraining of existing personnel from other backgrounds and fast track recruitment for previous vacation students. By employing a cross-section of professionals to complement the generic university graduate, the company takes full advantage of the relevant lifestyle experience belonging to the individual, which is a substantial factor in turnover. Study assistance and a salary paid for final year students and mature age students often creates a loyalty that lasts beyond graduation. Careful selection of vacation students increases the ease of recruitment at a later stage and ensures that full advantage is taken of the relationship developed previously between the company and young professional. The evolution of recruitment at Olympic Dam has seen a decline in the turnover statistics of young mining professionals.

Jan 1, 2005

By J St George

Much of AucklandÆs transport infrastructure has been developed on surface with little or no consideration of underground options. Current and planned transportation routes are now facing high costs due to land values and increasing environmental resistance to surface development. The option of utilising underground space becomes a feasible investment decision for these links as well as being the only option to develop the rail network within the inner city area. Transportation tunnels offer a quieter, more energy efficient means of getting around with minimal impacts on the surface environment. One of the major impediments to tunnelling is the high construction cost, which is partly related to the risks of encountering unexpected ground conditions and/or the possibility of causing surface ground deformations which could damage structures. The geology of Auckland has had substantial investigation through various studies and projects. The sediments of the East Coast Bays Formation (ECBF) underlie most of the Auckland urban area. It is classified as a soft rock and is a suitable material to tunnel through using either a tunnel boring machine or a roadheader. This paper reviews the limited amount of tunnelling completed in the urban Auckland area, together with the international advancements that have been made in the tunnelling industry. From the known features of the local geology and the problems encountered historically, the likely risks of tunnelling in Auckland are presented and ways in which those risks could be reduced and managed, are discussed. In addition, contractual arrangements between client and contractor are assessed with respect to complicated projects (such as tunnelling), so that the risks can be managed to create efficient infrastructure routes with reduced costs.

Jan 1, 2008

By Kam KM, Tran B

Statistical techniques of Box and Jenkins (1976) have been used to assess the existing control schemes and determine the dynamics of flash smelting furnace at the Kalgoorlie Nickel Smelter. Pertinent process variables, such as, oxygen flow, flux flow, matte grade and iron to silica ratio in slag, were considered in the analysis using routine operating data collected over two periods of operation. Results indicate inadequate control of some of the important variables. Dynamic characteristic parameters (dead time and response time) between a set of input and output variables were identified to improve optimisation of the existing thermodynamic model used for flash furnace control.

Jan 1, 1996

By B M. Moudgil

Atomic force microscopy (AFM) has become an important tool for understanding the nano- to molecular scale mechanisms predominant in multiphase systems. In flotation research, the use of AFM holds promise for unlocking and establishing fundamental mechanisms, ultimately leading to significant advances in process performance. From measuring and characterising surface forces, the structure of molecules at interfaces, and nanoscale features on flotation media, AFM is a powerful tool that has only begun to impact flotation research. Highlights of advances made in the utilisation of AFM for flotation research at the University of Florida are given with an emphasis on interpreting the mechanisms behind calcium activation in phosphate flotation and the impact of nanoscale asperities on collector-born surface hydrophobicity.

Jan 1, 2005

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

By A Karrech, E Hamdi

The uncertainty of geomaterials properties is commonly encountered in resource engineering applications, especially in mining engineering where the rock mass texture, joints, fractures and damage zones can impose the mining method and operation cycles. In the present research work, we focus on the elastic properties of rock masses. We use stochastic numerical simulation of fractured rock masses to estimate their Young moduli. The procedure starts with field mapping campaigns which are conducted to evaluate the locations, dip angles, strike and trace lengths of pre-existing fractures. We develop statistical law parameters of the natural fracture network to represent the weakness patterns. In addition, we use HLA-Dissim, a recently developed and validated Matlab program, to simulate the propagation of monochromatic longitudinal waves and derive the equivalent elastic modulus of fractured rock masses. Such procedure applies within a simulation domain, which is greater than an Elementary Representative Volume.At a second stage, we conduct finite element simulations to validate the previous approach. The matrix and the actual fractures zones are reproduced in the model to mimic the natural set-up. The block is excited on particular positions and its response is evaluated on predefined spots. Real field rock fracture mapping data and monitored single-hole blast induced vibrations are used to validate the theoretical and numerical approaches discussed herein. Comparison between the simulated and measured vibration records shows a great agreement which confirms that the proposed methodology has a full potential to predict and optimise multihole/multidelay blast-induced vibrations.CITATION:Hamdi, E and Karrech, A, 2015. A methodology for rock mass characterisation to control blast-induced vibrations, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 89–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By R Simonato

It is now recognised that rotary sample division is by far the best laboratory tool for extracting subsamples from a lot of material. In terms of sampling theory, rotary division, by virtue of the fact that it can extract many increments from the lot during the division process, radically reduces the variance due to distributional heterogeneity in the sample being divided. There are a number of occasions in sample preparation when it is necessary to extract a subsample of a target mass. To do this with rotary dividers taking a fixed fraction of the starting mass is a tedious task. In response to this problem, a variable split sample divider has been designed and built for the mineral industry. This paper discusses the utility of the device and presents test data showing that the machine is capable of making accurate mass split while overcoming segregation in the material being divided.

Jan 1, 2008

By H S. Shin, H Jin, B H. Ryu, J Lee

Prospecting ice on the Moon necessitates drilling systems to obtain subsurface samples and measure the composition of ice deposits. Landers and rovers equipped with drilling equipment are essential for analysing ice and subsurface resources located at the Moon’s poles. These devices must be small, lightweight, low-power, highly efficient, and high-performance units to function properly in the extreme conditions of the lunar environment. Researchers have developed a prototype drilling apparatus capable of operating in atmospheric and cold environments. A newly developed drilling system in Korea, capable of performing not only sampling but also subsurface investigation, is introduced.

Sep 1, 2024

By K Sommerville

BHP Billiton’s Area C iron ore operation has been in production since 2003. During 2010, below water table mining in the Marra Mamba formation commenced and dewatered ore has been successfully processed through the plant.The ability to mine below water table material increases reserves. Pits can be dewatered using a combination of ex-pit and in-pit bores. Critically it is important to allow suffi cient lead time to dewater. For Area C, in-pit bores yield the most water which presents challenges in every day operations when mining around bores. Operationally there are steep learning curves in obtaining equipment, training personnel and setting up infrastructure. Core risks include lifting, refuelling and maintaining gensets. The pipework, extraction and re-establishment work can be very manual.The challenges include blasting, mining, stockpiling, processing, water balance and disposal. Maximising up time on bores whilst minimising impacts to blast practices have evolved. Blast practices now align bores to the edge of patterns. Protecting bores have evolved from stemming bores with rock and re-drilling to using gas bags which require no drills. Based on moisture and material properties, mining of dewatered material can be categorised into three groups:1. normal,2. sheeting, and3. sheeting and top loading.Ore can go straight to the plant ore to drying pads where it takes between one and three months to drain.Stock management of these piles is important to ensure efficiency of the plant. Rules have been established for blending wet material to maintain feed capacity and some modifications to plants have been made. Dewatering of pits poses a challenge for water use. Initially turkey’s nests were established to capture water and use for dust suppression. As water abstraction has increased methods of management include using exhausted pits for storage and evaporators. Managed Aquifer recharge and use in potable water are being considered. An over arching coordination of the capacity and use are required.Important elements in dewatering include:• capacity models,• capital,• long to short planning,• day to day coordination, and • water level monitoring and balances. Success in dewatering requires a cross function team working towards a common goal. *This is an abstract only. No paper was provided for this abstract.*

Jul 11, 2011

Recent well-publicised problems with the start-up of new mining projects have continued to feed the perception that the mining business in general and Ore Reserves in particular are a poor risk. New mines commonly experience difficulties when the true variability of ore characteristics becomes apparent during commissioning. At this critical stage, the impact of lower metal recovery, reduced throughput or increased consumption of reagents and energy can have a catastrophic effect on economic returns, as illustrated by the premature closure of some operations. There appear to be several common reasons contributing to the poor performance of mining projects, of which three are examined here: lack of early risk assessment before feasibility studies are started, inadequate sampling for metallurgical test work and variability of the run-of-mine (ROM) ore. An underlying feature of these issues is the lack of effective interaction between geologists, mining engineers and metallurgists/ process engineers. Geologists need to be more aware of ore processing issues and the range of characteristics that need to be considered as part of the resource estimate. Metallurgists need a greater understanding of the variability of the run of mine ore in terms of all the characteristics that influence the design and operation of the plant. Mining engineers need to determine the short-term variability of the ore in the mine schedule, so that there is confidence that the quality of the run-of-mine ore will be within the design specifications of the plant. A substantial overlap between these disciplines and sharing of areas of responsibility is necessary if these and other technical problems are to be better understood, production estimates are to be improved and commercial risks are to be reduced. Although the JORC Code (1999) provides guidelines for reporting all the issues that are material to an Ore Reserve estimate, some issues are rarely fully addressed in Ore Reserve reports. In particular there is no formal requirement for a metallurgist to assure his or herself of the appropriateness of the Ore Reserve classification. Consequently the level of uncertainty related to recovered grade and ore processing characteristics may be understated. It is suggested that to meet the concerns of bodies funding new mineral developments a stronger multi-disciplinary approach to the analysis of mineral deposits and reporting of Ore Reserves is required. The culmination of this approach would be the formal requirement for a geologist, mining engineer and a metallurgist to co-sign Ore Reserve reports.

Jan 1, 2002