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By M Jahani, M Taji

For suitable production planning in an open pit mine, and also to carry out the optimisation process during the mining production cycle, prediction of fragment size distribution is required prior to carrying out the blasting operation. For this purpose, many prediction models, such as empirical models, were presented. The proficiency of these models differs in various conditions and mines. Therefore, in this paper the most important models, including SveDeFo, Kuz-Ram, CZM, Modified Kuz-Ram in 2005, Kuznestsov-Cunningham-Ouchterlony (KCO) and also Gheibie et al, were examined by the information of 20 blasts in Gol-Gohar iron ore mine. Fourteen images were taken on average for each blast. For image processing analysis Split-Desktop software was used. After examination, it was understood that none of the available empirical fragmentation models had presented acceptable performance, except the Kuz-Ram model for magnetite ore, which had somewhat acceptable results. However, this model for blasting patterns in hematite presented unsuitable results. Examination and comparison of two important distribution functions, Rosin-Rammler and Swebrec, were carried out and it was observed that the performance of Swebrec for fines was far better than Rosin-Rammler. This result for the upper part of fragment size distribution curve, coarse, is the reverse.CITATION:Jahani, M and Taji, M, 2015. Comparison of empirical fragmentation models at the Gol-Gohar iron ore mine, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 707–714 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By G Hall

BHP BillitonÆs (BHPB) Yandi ore deposit is a channel iron deposit (CID) in the Pilbara district of WA. The ore is predominantly a goethite-hematite pisolite and overlays a clay at the base of the deposit. Knowledge of the location of the contact prior to mining is critical to maximise ore extraction and minimise contamination from and mining of the underlying clays which contain high levels of alumina. The contact between the iron ore and the clay is highly irregular. Traditionally the contact has been delineated by closely spaced drilling û this can be expensive and since each drill hole only provides a point sample measurement, irregularities in the contact surface can be missed. In September 2001, three high resolution geophysical techniques were trialled to see if they could be used to improve the efficiency and accuracy of ore delineation. The three techniques were resistivity imaging, ground penetrating radar and electromagnetic conductivity imaging. The resistivity data showed a favourable correlation with the available ground truth data from drilling. Using this ground truth data as a calibration, an interpretation of the depth to the base of the channel iron deposit (CID) ore was constructed for the areas surveyed. A significant attribute of the method is that the position of the base of the ore is imaged continuously along the lines that are surveyed rather than at discrete points. No continuous well defined ground penetrating radar (GPR) reflections were observed from the base of the CID ore. There did appear to be some correlation between the range of echo times that reflections were observed and the drill data, however the precision to which the range of echo times could be estimated was of the order of several metres and therefore not adequate to replace current procedures. The electromagnetic data showed good correlations with the existence of shallow clays but did not discriminate between variations in CID ore depth. This technique is therefore not suitable for mapping the base of the CID ore but may still be useful as a rapid tool for mapping the position of clay bands.

Jan 1, 2002

By Parfitt RL

A quarter of the North Island, New Zealand is covered by weathered volcanic tephras of mainly andesitic and rhyolitic compositions. Rapid weathering of basic volcanic glass and slower weathering of acidic glass have produced short-range order alumino-silicate clays such as allophane. Although amorphous to x-rays they have a high degree of local structure. Allophane comprises hollo spheres of approximately 40 diameter and 7 X wall thickness. This small particle size and morphology gives a very high surface area (up to 800 m2/g). Ferrihydrite is another short-range order clay of similar small size and high surface area; it has ò formed from the rapid oxidation of water containing ferrous iron derived from volcanic rocks. The quantity of allophane present in tephra depends upon the climate, the nature of the volcanic glass and the time it has weathered. In New Zealand highest amounts (-50%) occur in beds of andesitic ash deposited on old ignimbrite surfaces with mean annual rainfalls >1600 mm. Both allophane and ferrihydrite will react with oxyanions, such as phosphate, arsenate or borate, and remove them from solution. Other anions such as fluoride also react with aluminium sites on the mineral surface. At NZ Soil Bureau, Department of Scientific and Industrial Research (DSIR), New Zealand, techniques have been developed for granulating allophane to enable it to be used to remove pollutants from solution without dispersion into the liquid phase. This granulated allophane can be used to remove phosphate from sewage effluent or fluoride from tap water without having a sedimentation stage to remove the clay.

Jan 1, 1987

By T J. Laing, A B. Richards, A J. Moore

Blastholes fired in a pattern with a constant initiation delay create a frequency in the ground vibration similar to that from a percussion instrument, such as a drum, in the air. A constant firing delay generates a prime or forcing frequency into the ground motion. The forcing frequency may then be modified by ground transmission characteristics into subharmonics of the forcing frequency. The moving vibration source between blastholes also creates a frequency shift because of a Doppler effect. Other wave interactions may form beats. The effects are exacerbated by the accurate firing times of electronic detonators. This paper demonstrates how observations of wavetraces and frequency spectral analysis were used to recognise:Doppler effect and frequency ellipsoidssubharmonics (and sub-subharmonics) of the forcing frequencybeat formation that may double or triple peak particle velocity (PPV) levels.Recognition of beats permitted techniques to be used to control ground vibration from coal overburden blasting to limits deemed to cause no further instability in a slip failure. An understanding of the science involved has practical application elsewhere that has been successfully applied to initiation timings to reduce PPV and adverse human and structure response from other blasting operations.CITATION:Moore, A J, Richards, A B and Laing, T J, 2015. Blasting harmonics and controlling peak particle velocity, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 527–532 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

This paper describes the programing and specification requirements which affected the choice of excavation methods on the Melbourne Underground Rail Loop (M.U.R.L.). The various methods that were chosen are briefly described, and the three most used are compared in more detail. Excavation rates, cycle times and other statistics are compared for full face tunnel boring, full face drill and blast, and heading and bench using a road header excava- ting machine. The length of tunnel excavated is sufficient to enable meaningful statistics to be presented and the significant specifi- cation and geological factors are described to weight the statistics where necessary for purposes of comparison. Average tender prices are given for excavation and primary support to indicate the reimbursement sought by contractors to carry out this type of tunnelling.

Jan 1, 1981

The paper describes the preparation of new rail guides, removing existing rails, and replacing with new rails in a vertical winding shaft.INTRODUCTIONThe general practice in coal winding shafts is the use of two cages, with one or more decks in which men and materials are raised or lowered. Winding speeds vary according to depth, the type of winding gear, and whether winding is done in downcast or upcast shafts. Each cage occupies a position between the centre and side of the shaft, with a clearance depending on the type of guides used. The function of the guides is to keep the cage in position throughout the entire depth of the shaft. There are three types of guides, two of which are in general use.1. Selected wood of about 6 in. square section, fixed to the side of buntons.2. Solid strand steel made up similarly to that of an ordinary wire rope, suspended from the head frame with weights attached to the lower end.3. Standard T-rail sections fixed to end or side buntons. Of the three types, 2 and 3 are in general use. The type used in the particular case, the subject of this paper, is T-rails of the standard section used in railway work.GENERAL DESCRIPTION OF SHAFTDetails of the shaft are as follow: Diameter of shaft: 22 ft. inside lining.Depth of shaft: 900 ft., including sump.Concrete lined throughout.VENTILATIONThe ventilation shaft is used for the upcast, through which all vitiated air passes to the main ventilation fan. Quantity of air passing up the shaft is 400,000 cu. ft. per minute. The air is highly saturated during the summer weather and slightly less...

Jan 1, 1947

By J F. H Thompson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Mineral exploration and mining are challenging businesses. Remote and at times harsh conditions have always made it difficult for exploration, but modern explorers also have to deal with cover, numerous technologies, an explosion of data and critical early community engagement. Mining deals with the reality of moving and breaking thousands of tonnes of rock each day to extract what can be a very minor component of economic value, and, furthermore, society expects that this will be done in a clean and sustainable manner. The exploration and mining challenges appear disparate, but they are intimately related.Although not widely appreciated, both exploration and mining have a long tradition of innovation. Over the last 50 years, major step changes in exploration have resulted from radical advances in our understanding of ore forming processes, new geophysical, geochemical and remote sensing technologies, and new ways to integrate and interrogate data. Over a more extended period, close to 100 years, mining has developed bulk surface and underground methods, selective extraction through flotation and leaching and global positioning system–geographic information system control systems that collectively facilitate mining at a massive scale. And yet, in spite of these successes and the boom that we have enjoyed in the last ten years, the industry is under pressure and the need for innovation and change is paramount.The major drivers for innovation are the need for increased quality in discoveries and mines and the need to interact effectively with communities and jurisdictions such that the benefits of quality mines are recognised and enjoyed widely.We are still making new discoveries around the Pacific Rim and elsewhere, but many argue that the quality – grade and accessibility – of these discoveries is decreasing. The net result is that explorers are delivering resources and reserves for development at lower grades and with higher capital and operating costs than current operations. For mining, the increasing age of many existing operations contributes to increasing costs, which, when combined with decreasing cut-offs and lower grades, also results in declining quality. The combined picture does not look good.Just as the pressure to improve performance and margins in the face of declining inputs increases, we are simultaneously faced with increasing societal demands for improved environmental performance and sustainable practices. This is most apparent at the local, community level, where opposition ultimately leads to delays or even cancellation of new projects. Quality is again the issue – quality of the initial and ongoing engagement and quality of the proposed mine in terms of environmental and economic performance.CITATION:Thompson, J F H, 2015. Exploration and mining – the need for innovation , in Proceedings PACRIM 2015 Congress, pp 45–48 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Bisshop J. P W

Maximum recovery of sulphide minerals by flotation is achieved over a limited size range. Valuable particles above and below this range have a smaller probability of being recovered. In the normal grinding-flotation operation, not all valuables are reduced to the optimum size range, and therefore sub- stantial losses occur. A significant improve- ment in the size distribution is not usually possible within the conventional circuit, and a more complex arrangement may be necessary to obtain optimum recovery of the valuable mineral. This problem is considered with refer- ence to the Mt. LyeZl concentrator. The performance of the existing circuit is dis- cussed, and it is shown that losses in recovery occur in both coarse and fine sizes. Laboratory tests indicate that regrinding the coarse particles results in an increase in recovery of up to 4%. Redistribution of plant grinding capacity to reduce initial grinding power by 6% and use this capacity to regrind coarse particles was considered. It is con- cluded that overall plant efficiency would be increased by 2% provided that overloading of the regrind mill could be avoided.

Jan 1, 1977

The selection and implementation of the right technology for a project is critical to the future development of the resource industry. It is essential for companies to ensure ongoing competitive viability that where practical new or alternative technology be adopted. Analysis of historical data relating to development of resource-based process plants provides an enlightening insight into the key factors which influence their success or failure. The adoption of new technology does not guarantee the success of a project. The outcomes of this analysis have been used to develop some general guidelines and principles the author believes are useful in the selection and implementation of new or alternative technology in resource projects. This paper is available as a PowerPoint presentation only.

Jan 1, 2006

By Z Li, D Chalmers, J M. Tenney

This paper presents the findings and analysis of the investigation of effectiveness of thin spray-on liners (TSLs) as a gas management tool in underground coalmines. The project involves spraying TSL on the area surrounding gas drainage holes whereby the TSL acts as a thin membrane decreasing the permeability of the coal. This restricts air migrating through the coal seam and diluting gas from the drainage holes. There are a number of potential benefits from this technique but key points are that gas drainage holes produce gas with higher concentrations of methane. The design and execution of a field trial to investigate the effectiveness of a TSL on purity of in situ methane from gas drainage holes is presented in this report. For eight drainage holes, the results show an average increase in methane purity by 9.14 per cent and a reduction in air contamination by an average 7.93 per cent. Overall methane flow rate decreased by 27.6 L/s; however, flow rates were unreliable due to poor measuring equipment. For most holes, methane purity was not changed significantly; however, certain boreholes were responsible for most of the variation in methane purity. The boreholes showing a dramatic improvement in methane purity were likely those with intersecting cleats covered by the TSL. If the TSL was sprayed over more area, specifically in areas where the cleats are intersecting with holes, it is likely that purity of methane in the drainage holes will increase.CITATION:Tenney, J M, Chalmers, D and Li, Z, 2015. Thin spray-on liners potential in reducing dilution of in situ gas in underground coalmines, in Proceedings The Australian Mine Ventilation Conference, pp 323–328 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By A D. Campbell, G R. Power

The increasing availability of marker data in sublevel caving operations is changing the way draw can be managed to achieve positive recovery outcomes in these mines. This paper describes how marker data has been incorporated into flow simulations to help calibrate full mine ore recovery simulations for the forecasting and optimisation of recovery.Some flow modelling techniques do not use marker data, relying instead on the outcomes of physical and numerical experiments to guide assumptions about an idealised recovery flow shape. Other mines have access to marker trial data, but find it difficult to specifically link this marker trial information to their recovery models. This can make it difficult to create a link between the marker trial information and recovery forecasting and limits the potential value of the marker trials at the mine.In the simulations shown here, the marker rings are fully incorporated into the flow model, and can be tracked in the model. The model is compared against the real underground marker recovery information to give the user an indication of how accurately the flow settings in the model are reflecting the conditions in the experimental marker rings. An example of use of this system at an operational mine is included.CITATION:Power, G R and Campbell, A D, 2016. Modelling of real-time marker data to improve operational recovery in sublevel caving mines, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 105–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By S W. Richards, J Buys

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Magmatic arcs are prime targets for porphyry- and epithermal-style mineral deposits, although settings within continental arcs and/or tectonically-thickened crust generally tend to be more prospective than intra-oceanic arcs in extensional settings. In this paper, we report new geochemical and geochronological data on igneous rocks of the Western Belt of the Vanuatu intra-oceanic arc. Dating of igneous hornblende (Ar-Ar) and zircon (U-Pb) from the igneous rocks place their formation in the late Eocene to Miocene. In most respects, these are typical arc igneous rocks. However, they contain inherited zircon grains with significant age populations at ca 2.8–2.5 Ga, 2.0–1.8 Ga, 1.75–1.5 Ga, 850–700 Ma, 530–430 Ma and 330–220 Ma. This inheritance signature is unlike anything recognised from the oceanic realm of the south-west Pacific, but, in general, does match the age of the major crustal blocks of the Australian continent. An exception is the significant proportion (~20 per cent) of zircons of Rodinia breakup age (~800 Ma), which previously has not been found in eastern Australia or the south-west Pacific.We propose that part of the Vanuatu arc basement comprises a ribbon of continental material rifted from northern Australia prior to, or during, the Cretaceous. The presence of ancient continental material within the Vanuatu island arc may help reconcile the relatively large thickness and low density of the crust of Vanuatu, and may enhance the prospects for significant porphyry and epithermal ore deposits in the region.CITATION:Spandler, C, Buys, J, Holm, R J and Richards, S W, 2015. Remnants of ancient Australia in Vanuatu – implications for south-west Pacific tectonics and mineralisation potential, in Proceedings PACRIM 2015 Congress, pp 183–188 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By L MacDonald, D Molver, D Pepper

Increasing contamination/impurity levels (including arsenic, antimony, mercury etc.) of concentrates is an issue of global commercial and health / environmental significance. With increasing environmental pressures at smelters, penalties for contaminants in concentrates continue to rise, accompanied by lower reject limits. There is a strong incentive for miners to investigate alternative means to remove contaminants in order to increase the value of complex ores and concentrates. This paper discusses the global problem of contamination in complex ores and concentrates, how the Toowong Process technology is a potential solution to this problem, and the opportunities this technology brings to the business of dealing with deleterious elements. CITATION: MacDonald, L, Molver, D and Pepper, D, 2018. The Toowong process for treatment of complex ores, in Proceedings Complex Orebodies Conference 2018, pp 119–121 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By B Murphy, N Strong, J Albrecht

Rio Tinto’s Argyle Diamond Mine has a history of underperformance with delivery of ore from the underground operation to the surface for processing with no real clarity in sources of loss and value. In order to increase underground production performance, the basic concepts of the Theory of Constraints model were applied to the Argyle underground production system. This prompted a revised view on bottlenecks and contributors to value loss and ultimately leading to record breaking mine performance. System loss reporting to demonstrate the best opportunity to drive value, departmental detail to develop tools to identify improvement opportunities and clarity across the team to ensure alignment and clear lines of communication were critical to the project success.

Mar 15, 2021

By B Chapman, B Gaida, L Drowley

The 372 MW Ulu Jelai Hydroelectric Project is a peaking power scheme located in the Cameron Highlands, Malaysia. The main features of the project include an 84 m high roller compacted concrete dam; two weirs which divert flows from adjacent catchments via transfer tunnels into the main reservoir; an underground power waterway; and an underground power station complex comprising three large caverns with connecting tunnels approximately 240 m below surface level. The project includes approximately 25 km of tunnels excavated in fresh granite rock mass with some distinct shear zones of weaker material. The majority of the tunnels are being excavated using drill and blast, with the two transfer tunnels being excavated with a tunnel boring machine (TBM).This paper focuses on the design and construction of the Telanok underground power station complex and also some aspects of the design for the headrace tunnel. Topics covered include geological site investigations including in situ measurements of rock stresses; development of a geological model and parameters for rock support design; three-dimensional modelling to assess interactions between the caverns to optimise rock support; design of a rock anchored crane beam; construction of the caverns and design of the unlined headrace tunnel taking into account hydraulic jacking and operational pressure fluctuations.CITATION:Drowley, L, Gaida, B and Chapman, B, 2014. Design and construction of large caverns in granite – Ulu Jelai Hydroelectric Project, Malaysia, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 361–368 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By E R. Ramanaidou

Two unknown iron ore samples were found by a geologist from Ok Tedi Mining Limited copper, gold and silver mine at an old wharf site dedicated to a 1970s drilling program in Lake Murray in Papua New Guinea (PNG). These iron ore samples could not come from a PNG mine and it was decided that a study should be undertaken to understand their origin. Lake Murray is the largest lake in PNG with a total surface area of 647 km2. It has a high-water 2038 km long convoluted shoreline with seasonal water level changes (Osborne, Kyle and Abramski, 1987) and it is located around 200 km south of the Ok Tedi mine (5°13’25”S, 141°09’37”E). The petrology, mineralogy and chemistry of two Fe samples (Ok Tedi 1 and Ok Tedi 2) included optical microscopy, X-ray fluorescence (XRF) analysis and a comparison with worldwide iron ore deposits. The two rock samples were cut to produce two subsamples: (1) a polished thin section; and (2) a pulp that was used for XRF analysis including major, minor and trace elements. Ok Tedi 1 and Ok Tedi 2 were petrologically and chemically compared to a range of known iron ore samples from Australia, Brazil and South Africa. The petrological study of Ok Tedi 1 indicates that it is composed of granoblastic recrystallised hematite and the overall texture is uniform without any obvious original ‘sedimentary’ texture. Ok Tedi 2 is a ‘specular’ or platy hematite with recrystallised and fused grains. Using both petrological and chemical clues, the two Ok Tedi samples likely originated from the Iron Quadrangle in Brazil.

Sep 18, 2023

By B W. Atkinson

Full-stream mechanised sampling apparatus, that collect a full cross-sectional increment from the complete screen discharge, will always be the preferred option for sampling screen overflows. However, the reality is that provisions for automated sampling are rarely, if ever, provided at the discharges of individual screens within beneficiation plants.Sampling from the discharge of high capacity vibrating screens, especially multi-slope screens, is subject to sampling bias, due to the stratification of the ore that occurs on the vibrating screen deck. The stratification in the vibrating bed translates to a stratified falling stream at the discharge end of the screen, typically with smaller particles at the back of the falling stream and large particles at the front of the falling stream (Figure 1).The chemical and physical characteristics of heterogeneous ore (mineral or coal) particles vary significantly with particle size. If samples do not correctly reflect the source material size distribution, they will be biased and the resulting analytical/assay data will not reflect the actual physical nor chemical characteristics of the source material.Prior published data for coal preparation research (Australian Coal Association Research Program) has demonstrated that a bias appears to exist for samples collected from high capacity multi-slope screens.A new form of sampling scoop has been developed with the aim of overcoming this issue.Bias was evaluated at a coal preparation plant by comparing the desliming screen overflow size distribution to that for æreferenceÆ coal preparation plant feed samples collected using the recognised stopped-belt technique. The study procured 20 sets of comparison samples in order to ensure statistical relevance.Two forms of sampling device were employed for the multislope screen discharge.A conventional square aperture scoop was demonstrated to exhibit a significant coarse bias, in that the resulting samples exhibited a significantly coarser size distribution compared to the reference samples. In other words it was evident that the conventional scoop æfavouredÆ material from the front of the falling stream.A new æcollapsibleÆ sample scoop was evaluated in parallel, and its samples were found to exhibit no relevant bias.CITATION:Atkinson, B W and Swanson, A R, 2012. A new method for sampling from high capacity screens, in Proceedings Sampling 2012 , pp 89-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By S Bhandari

A model for predicting dust plume dispersion from blasting operations using the Eulerian mathematical algorithm has been developed. This model considers atmospheric stability, and wind velocity and direction for computing dust concentrations at different distances from the blast. Software has been developed which simulates the movement of a dust plume at a given horizontal distance from the blast location and time elapsed after the blast. The concentration of dust is also given in vertical planes. It takes into account ground profile and atmospheric conditions such as temperature, pressure, humidity, wind velocity, wind direction and shear. Experiments were carried out in two limestone mines to calibrate the accuracy of the predictions made by such model. High volume dust samplers were used to collect dust samples. Difficulties encountered in satisfactory dust sampling and quantification of results have been described.

Nov 8, 2011

By R Pax

Feed ore variability, the major disturbance into a mineral processing plant receives considerable attention operationally, and at research and strategic levels to ensure that the throughput of the ore are maintained at all times whilst encouraging a sustainable approach to recovering the valuable minerals from ore bodies. Effort and insights from mineralogical and processing characterisation (eg. ore hardness) of sub-ore body domains allows sequencing for processing to ensure consistency and throughput for the size sensitive grinding unit processes. Optimising the blast fragmentation has benefit as does pre-concentration using ore sorting. Blending of ore domains with different characteristics is common for operations. In recent years a number of technologies have become available for on-line and more rapid assessment of ore and have been discussed in a recent paper by Cameron et.al. (2016) as an opportunity for further utilisation of mine-to-mill (and mine to product) strategies. Current concepts have focused on extensive characterisation of ores so that current control practices can be realised and made more effective with relatively slow measurements and actuation. CITATION: Pax, R, 2018. Dynamic concepts for mine to mill operation and optimisation, in Proceedings Complex Orebodies Conference 2018, pp 124–125 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

Employing gravity recovery for coarsely liberated gold and sulfide ores has potential to lead to a signifi cant reduction in the energy required for comminution and ultimately can have a significant impact on gold processing. Most of the recognised metallurgical tools at our disposal currently have been designed around recovery of relatively finely ground minerals. In order to change the paradigm of fine grind for liberation, a new set of tools need to be recognised that are capable of separations in the coarser size fractions. Some of these tools already exist and some need to be developed but the key is the way in which the fl ow sheets are arranged. A very strong understanding is required in the existing tools and their capabilities before these new flow sheets can be optimised. Only when we understand the existing gaps in technology can we start to fill these positions with new candidates. Many ores when crushed liberate their gold bearing minerals at coarser sizes than current practice would suggest (Figure 1). In order to characterise this response in ores it is necessary to utilise some new techniques in the lab such as gravity separation and ore sorting at the sizes greater than 15 mm followed by gravity recovery on fractions from 15 mm down to 150 ¦m. The most difficult range has been the mid-sized fraction from 4.0 mm down to around 150 ¦m. This is the size range in which many ores show economic liberation starting to occur and coincidentally this is the range in which many commonly used metallurgical processes reach their operational limits due to physical constraints. Examples of these processes are flotation, hydrocyclones and whole ore leach in agitated tanks which are currently the mainstays of the processing fraternity. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010