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By G Johnson, S Michalek, N Redman

As the modification of the 2009 Mill OperatorsÆ Conference theme from æmilling through the boomÆ to æthe boom û experience gained and lessons learnedÆ exemplifies, comminution practitioners are facing a series of challenges in the dramatically changing mining environment. One of the main problems plant managers have been facing during the boom times has been the severe metallurgy skills shortage and high staff turnover, both factors that can cause difficulties in mill liner management. Many of todayÆs mill managers are now also more than ever faced with the need for cost-cutting in order to continue operating viably. Amongst other potential target outcomes such as maximised throughput, MillMapperÖ, a tool for mill condition monitoring and mill performance optimisation, can be utilised to address these issues. This paper demonstrates how MillMapperÆs quantifying decision making tools can serve to be in control of managing mill liner and production issues, and how it can form the basis for mill cost savings without the risks normally associated with conventional methods or the lack of using any condition monitoring methods. MillMapperÖ is currently being referred to at a rate of approximately 150 surveys and associated reports per annum at processing plants in Australasia, South America and Africa. Examples throughout the paper provide insight into how the presented sample set of users have extracted benefits that could have otherwise not been safely or at all achieved.

Jan 1, 2009

By S Z. Petho

The South Deep surface shaft system is being sunk to a final depth of 2750 m below surface and on completion will be the deepest single drop shaft in the world. The shafts will intersect the target reef horizon at 2650 m below surface. In order to negate the requirement for a shaft pillar, which would be extremely large at this depth, the reef horizon in the vicinity of the intersection is currently being mined. A high quality crushed waste/classified tailings backfill is being placed in the longwall stoping panels around the shaft intersection area. This will limit closure and ride which following shaft reef intersection could have a detrimental effect on the long term shaft stability. This paper discusses underground instrumentation results and numerical modelling exercises carried out to confirm that the shaft system will be stable throughout the life of the mine. Instrumentation projects include closure and ride measured between backfill paddocks and haulage leveling exercises carried out to determine the far field rockmass response to mining with stiff backfill. Results from the numerical modelling exercises show good correlation with measured data. This indicates that a high degree of confidence can be placed in the model input parameters and consequently in the design of the shafts to ensure their long-term stability.

Jan 1, 1998

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

SPOT imagery acquired in May 1986 of the areas that include the Dugald River lead-zinc lode, northwest Queensland, Australia and the Ngwenalekau copper deposit, Botswana has been evaluated and compared with LANDSAT MSS imagery of the same areas. The data have been processed using band combinations, band ratioing, principal components analysis and classificatory techniques and the outputs compared with those of geobotanical, geochemical and biogeochemical data as well as geological information. For both study areas the image processing techniques cited have successfully distinguished discrete vegetation associations related to discrete surficial and bedrock geological units; and, notwithstanding the sharp contrasts between the nature of the geobotanical anomalies that in both areas occur over mineralised bedrock in Proterozoic sedimentary sequences, they have successfully identified the areas of anomalous vegetation over the mineral deposits. Greater vegetational and geological detail is revealed than on outputs generated from LANDSAT MSS data [see Cole, 1977, 1982(a) and (b)]. The additional information yielded by SPOT imagery compared with LANDSAT MSS imagery results from its greater spatial resolution - 20 metres as against 79 metres - and from ti fact that the three SPOT MSS spectral bands - 0.50 0.59um, 0.615-0.68um and 0.79-0.89um - respectivelc cover those sections of the electro-magnetic spectrum in which leaf pigments, notably chlorophyll, absorption for photosynthesis and leaf cell structure strongly influence reflectance. This accords opportunities for the detection of reflectance aberrations caused by stress due to drought and/or metal toxicity as well as for the identification of anomalous vegetation communities of moderate sizr These cannot be accurately discriminated on LANDSA I MSS imagery on which only very large geobotanical anomalies like that over the Lady Annie phosphate deposit in northwest Queensland [Cole, 1977, 1984; Cole and Owen-Jones, 19771 can be detected.

Jan 1, 1988

By A Coulson, J Hussey

Noranda Inc is a Canadian mining and metallurgical company with its activities managed through businesses in copper and recycling, zinc, aluminum, magnesium and various metals through its interest in Falconbridge Ltd. Noranda operates three base metal mines, three copper smelters, one copper refinery, one zinc refinery, one lead smelter and refinery, three copper recycling and sampling facilities seven aluminum producing facilities and one magnesium production facility in the construction stage. The mining side of Noranda has a strong history of open stope, cut and fill and shrinkage mining. The 1999 Noranda Annual Report lists a 206 million tonne resource located at Porphyry Mountain in GaspT, QuTbec. Mont Porphyre is a large tonnage, low-grade porphyry style Cu-Mo deposit that was discovered in 1994. It is located at a depth between 1.0 and 1.7 km below surface and characterised by a very competent rock mass. The Mont Porphyre resource is located adjacent to the town of Murdochville, close to NorandaÆs Mines GaspT operations. Mines GaspT closed its open pit and underground operations in 1999 after approximately 45 years of mining, but still operates a copper smelter near Murdochville. The low-grade and great depth of the Mont Porphyre resource suggested that mine design could not be based on the conventional Noranda open stoping mining practice. This paper will review NorandaÆs approach to evaluating the Mont Porphyre deposit. The approach included two definition diamond drilling campaigns, a review of current caving practice, an in-house scope study, a geotechnical logging program for diamond drill core and participation in an international study on cave mining. One interesting component of NorandaÆs approach was the scope study that involved a team of multi-disciplinary personnel drawn together for a short period of time. The objective of the scope study was to determine what conditions would be necessary to mine the deposit and to assess the merits of continuing with further exploration work. A review of current worldwide underground bulk mining practices, and in particular an evaluation of the applicability of caving mining methods, were key components of the scope study. The scope study team concluded that derivatives of caving could be applied to the mining of Mont Porphyre, but additional diamond drilling was recommended to further define the deposit and improve the level of geotechnical information. Following the recommendations of the scope study team, a diamond drilling campaign was completed during the summer and fall of 1997. The 1997 drilling campaign had two secondary objectives, in addition to the primary objective of defining the limits of the orebody. The first objective was to improve the level of geotechnical information available for the characterisation of primary block cave fragmentation. The second objective was to improve the delineation of a lower grade intrusive core. A geomechanical investigation was conducted and included particular emphasis on geotechnical data collection and analysis. A review of the actual data collection process, including several trials of different core orientation techniques, will be included in the discussion.

Jan 1, 2000

By Lewis W. H, Leigh M. C, Mayercheck W. D

The U. S. Department of Interior's Bureau of Mines, in conjunction with a cooperator in the U. S. A., are developing a new highwall mining system (HMS) for coal extraction in unreclaimed and active contour strip mines. This prototype system is comprised of a computer-based remote control (CBRC) system to monitor and remotely control a thin-seam continuous miner (TSCM) and a 76*m long multiple-unit continuous haulage (MUCH) conveying system, plus other manually- operated support equipment located on the highwall bench. The TSCM and MUCH coal haulage system are both controlled remotely by a single operator in a protective enclosure at an ergonomically- designed workstation located on the highwall bench. Two other personnel work on the bench to operate other support equipment. Full-scale mock-up fabrications were employed in the design of the unique remote control operator workstation. The HMS should allow the safe and economical exploitation of increased coal reserves where they outcrop in hilly regions of the United States. It should also be competitive with conventional auger mining and other coal extraction techniques, with a productivity goal at a highwall site of 20 tonne/man-h. Extensive simulated surface tests of the miner and haulage system should be completed in early 1988 at Bureau test facilities at Pittsburgh, Pennsylvania. These will be followed by actual coal production trials of the entire system in 1988 at a highwall site in West Virginia/USA.

Jan 1, 1988

By Xizhen J

Point load testing for irregular rock specimens was studied to determine the relationship between tensile and compressive strengths, drill penetration rate and other rotary drilling parameters. The DH-l type point load tester was developed and more than 2 000 irregular specimens of over 60 kinds of rock from 16 mines and quarries were tested. The effects of size, shape and number of samples on the point load strength index were investigated, using regression analysis. Experiments were carried out to investigate the relationship between point load strength index and uniaxial compressive strength on 29 kinds of rock. The relationship between these values and the drill penetration rate for rotary and percussion drills is discussed.

Jan 1, 1986

By Gao K, Wu C, Langley J. M, Waugh B, Farrell K

The dissolution of carbon from carbonaceous materials into molten iron is a key step in various ironmaking operations. For example, in new direct smelting processes, carbon in the form of coal is injected into the molten iron bath, which leads to the dissolution of carbon. In foundry operations, typical recarburizer materials can range from high purity graphite to chars. The dissolution performance of these" materials is critical to the operation and could dictate the efficiency and economics of the process.Dissolution kinetics has been studied by various investigators to explain the influence of melt conditions and carbon type (Sahajwalla et al, 1994; Shigeno, Tokuda, and Ohtani, 1985; Orsten and Oeters; 1988; Ganguly and Reid, 1992; Wright and Taylor, 1993). The influence of melt sulphur content on the dissolution kinetics has been characterised (Sahajwalla et al, 1994), with sulphur retarding the rate of carbon dissolution. The carbon dissolution from different sources is seen to vary significantly even under similar melt conditions. This observation has been explained by investigators on the basis of the varying ash content present in the carbonaceous materials. However, ash content alone cannot account for the variability in dissolution kinetics reported in other studies. One such study is presented below.In a recent study (Sahajwalla et al, 1994), pulverised carbonaceous materials were injected into the molten iron bath and the" dissolution kinetics was established. The dissolution of graphite and glassy carbon, which contain almost 100 per cent carbon, was seen to be significantly different when the molten iron contained sulphur. The influence of melt sulphur content was explained on the basis of different wetting behaviour observed.Importantly, the study showed that even pure carbon sources dissolved at significantly different rates. Hence, their performance could not be explained on the basis of ash content.The key difference between graphite and glassy carbon is in their atomic structure. Graphite is highly ordered whereas glassy carbon has relatively poor ordering in its atomic structure. This study showed that the atomic structure in carbonaceous materials can have a significant effect on their dissolution performance.The focus of the present investigation which stems from the past study described above (Sahajwalla et al, 1994), is to investigate the influence of atomic structure of carbonaceous materials on their dissolution into Fe-C-S melts.The specific objective of this study is to determine the relationship between dissolution kinetics and crystallographic character of carbon sources. In order to accomplish this goal, a range of different materials representing a spectrum of carbon sources have been chosen for the investigation. These materials include brown coal char, two types of Auscarb (A and B), and commercial graphite. Auscarb is prepared by calcining Auscoal at 1000°C. Auscoal is made from chemically cleaned Australian coals (Bowling, Chandler and Waugh, 1990). Part 1 of this paper details the dissolution performance of the materials studied, while Part 11 describes the X-ray diffraction study. The relationship between the atomic structural dimension and dissolution rate constant is discussed in light of the results obtained.

Jan 1, 1996

By Cresswell G. M

The international coal industry is becoming increasingly aware of the economic impact of coal dewatering in terms of plant yield limitations, attainment of product specifications and freight costs. This paper examines the current position of dewatering within coal process plant design and reviews equipment developments over the past decade.

Jan 1, 1993

By S D. Golding, K Baublys, V Nanjappa, C J. Moran

Water reuse is becoming an integral component of the water management strategy on mine sites. This practise is being driven by corporate sustainability goals, community and societal pressures to demonstrate improved water stewardship, as well as climate and regulatory pressures. However, water reuse often results in water quality compromise which can then result in decreased recovery through problems in processing circuits, product quality, and an increased likelihood of discharge of water that cannot meet environmental regulatory requirements. On most mine sites, there is usually a disjuncture between water quantity management and water quality management with the latter being managed solely as an environmental problem. It is becoming increasingly clear that water quality and quantity must be managed as an integrated system. In order to integrate water quality and quantity management to achieve multiple objectives the dynamics of water and constituents must be understood. Using examples from a study being conducted at a coal mine in the Bowen Basin, this paper will outline the dynamics of water and salts on the site.

Jan 1, 2009

By M H. Randell, J B. Haines

The Honeymoon Uranium Project comprises the Honeymoon Deposit,Goulds Dam Deposit and Yarramba Prospect in the Southern Lake Fromeregion, South Australia. Both the Yarramba Prospect and HoneymoonDeposit (which includes Honeymoon and East Kalkaroo orebodies) arelocated in the Yarramba Palaeovalley. The Goulds Dam Deposit is about75 km north west of Honeymoon, in the Billeroo Palaeovalley. Exploration for sediment-hosted uranium began in the area in the late1960s, culminating in the discovery of Honeymoon and Goulds Dam inthe early 1970s. In 1982, a 25 L/s demonstration plant was built atHoneymoon to confirm suitability for in situ leaching. The project was put on hold in 1983 due to changes in government policy. Southern Cross Resources Australia Pty Ltd acquired the project in mid 1997. Roll-front deposits form from a migrating geochemical cell, anadvancing reduction-oxidation interface between oxygenateduranium-bearing groundwater and its reduced aquifer host. The source of metal is uranium-anomalous granites, which were eroded fromsurrounding ranges. The weathered granites and resultant sediments are stripped of uranium by oxidised groundwaters, to form solutions carrying uranyl carbonate complexes. The solutions percolate down-slope through permeable sand zones until contacting a reduced environment where uranium precipitates. Uranium mineralisation occurs interstitially between and as thin coatings on sand grains, usually in the form of uraninite or coffinite. The palaeovalleys (previously termed palaeochannels) are incised intounderlying Cambrian/Precambrian basement rocks and filled withsemi-consolidated, largely un-cemented, Tertiary sediments of the Eyre Formation. The late Palaeocene to middle Eocene Eyre Formation is the basal unit of the Tertiary succession in the Callabonna Sub-basin of the Lake Eyre Basin. Further to the north, the Lake Eyre Basin overlies the Jurassic-Cretaceous Eromanga Basin, which comprises much of the Great Australian Basin. Eyre Formation sediments are in turn overlain by the late Tertiary Namba Formation and terrestrial Quaternary units. At Honeymoon, the Eyre Formation includes immature, pyritic,carbonaceous sands and gravels interbedded with lignite andkaolinite-illite-montmorillonite clays. It was deposited by braidedstreams during epeirogenic uplift of the Olary Ranges, accompanied bysubsidence of the Lake Eyre Basin. The Eyre Formation comprises aconsistent stratigraphy of interbedded sand and clay units that arecontinuous over the Honeymoon Deposit but with local variationindicating some hydrological connection between aquifers.In the Honeymoon orebody, uranium occurs within coarse-grained,pyritic sands where the basal sand pinches out between overlyingcarbonaceous clay and the southern palaeovalley slope. Its characteristics are typical of the well-developed, planar limb of a roll-front uranium deposit. Zonal changes related to the reduction-oxidation interfaces across the deposit are readily observable. The orebody extends for nearly 1000 m along the valley margin, is 400 m wide at its maximum and averages about 6 m in thickness. The East Kalkaroo orebody also lies near the southern margin of theYarramba Palaeovalley. It extends discontinuously for approximately 3.5 km and averages 200 m width, with significant uranium present in the Middle as well as the Basal Member. The Billeroo Palaeovalley extends northward for 40 km sub-parallel tothe western side of the Benagerie Ridge, is up to 5 km wide and hasgently dipping banks. Eyre Formation within the palaeovalley isconcealed beneath 90 m of Quaternary and Namba cover, isapproximately 40 m thick, and is sub-divided into three upward-finingunits, which are remarkably similar to the Yarramba Palaeovalleysequence.

Jan 1, 2001

The complexities of mining in current economic conditions, where ore extraction schedules are varied on a weekly basis so as to ensure constant supply to the process plant, can result in a number of scenarios that pose geotechnical challenges. This paper presents a case study where alterations in the mining schedule of a particular mine resulted in the necessity to mine under a large uncompacted embankment, ie integrated tailings and mine waste land form. To effectively ensure that ore recovery was maximised, a well-designed slope monitoring system to evaluate design performance and to provide timely warning of impending failures was imperative. In order for an appropriate slope monitoring strategy to be developed, a thorough understanding of the potential slope failure mechanisms, capabilities and limitations of available monitoring techniques is required. Communication of the monitoring results and response strategy to alarms generated by monitoring systems must also be carefully considered to maximise effectiveness. The results of preliminary stability modelling can be used to guide the design of a monitoring system, which in turn can then generate data which can be used to iteratively refine the geotechnical model. This paper illustrates the development and implementation of a slope monitoring system and associated communication system, using the Daydream embankment at Fortescue Metals Group's (FMG's) Cloudbreak Operations as a case study.

May 1, 2010

The mining industry is facing tremendous economic challenges. Fluctuating and depressed commodity prices, the ever-increasing pressure from environmental legislation and the competing global opportunities for capital investment are placing enormous strains on every aspect of the mining business. At the same time, mines are generally becoming older and deeper with all the logistical and rock mechanics difficulties that this entails. In the face of these new challenges the industry looks to technological advances to make operations more efficient and profitable. One approach is to develop and implement highly automated and computerised equipment as part of a trend towards major reductions in the underground workforce. This approach requires more capital investment rather than less and requires a more sophisticated and well-educated workforce with skills which are generally in high demand in society as a whole. It is difficult to see how the benefit that can be gained from such technology can justify the expenditures necessary to make it operate reliably underground on a daily basis. Nor is it easy to foresee how the mining industry, based as it is often in very remote areas, will be able to hire and retain sufficient numbers of people to maintain such fleets of equipment. Another approach, and the one which I favour, is the implementation of much greater control over the whole of the mining process. Mining is essentially a very simple process - we break rock and move it. The most cost-effective means of moving and processing the mining product depends entirely on the way it is broken - it depends on primary fragmentation by blasting. I propose that the way forward for the industry in the face of our present difficulties, is not new technology but is to utilise the level of technology which currently exists in ways which have traditionally been regarded as too difficult or too inflexible - improved fragmentation and the use of conveyors. The technical success of this approach depends on the complete re-design of the ore handling system from the face or stope drawpoint to surface. The fundamental issue which determines the success of this approach is designed fragmentation.

Jan 1, 1995

Copper was first produced in Australia in 1844, at the Kapunda Mine in South Australia, and, by 18i>0, production exceeded 2,000 tons of copper a year. Output increased ,steadily, reaching a peak of 14,00Qo tons a year in 1867 and 1868, when the Burra Burra and Kapunda Mines in South Australia and the Peak Downs Moine at Clermont, Queensland, were at the height of their production. At this period, Australian copper formed a considerable percentage of the world's supply, its output equalling, for a short time, that of the United States. Production declined to between 3,000 and 4,000 tons a year after the closing of' these three mines between 18717 and 1879, and, at this stage, the Australian output came chiefly from the Wallatoo and Moonta mines in South Australia. About 19000, it began to rise again, with the extension of the railway to the copper fields of Chillagoe and Cloncurry, and, between 1905 and 1912, was at its greatest, with a maximum of 47,774 tons of copper in 1912. During this period, Australia contributed 4,7 per cent. of the world's annual production, and ranked among the six major copper-producing countries of the world (Table 1).

Jan 1, 1943

This opportunity to present a few thoughts on the question of professional education and training comes at a most appropriate time. In Britain, a great deal of energy is being expended in this, so-called, post-Finniston era, to create a new look for the status of engineers and engineering by the Engineering Council. Naturally, the tune and the tempo are being called by the big institutions which essentially serve the manufacturing industries. However, the Engineering Council in Great Britain also includes the mining and processing institutions such as the Institution of Mining and Metallurgy (IMM) and so there is a chance - if it is taken - for us to contribute to the debate and the determinations that emanate from it. The IMM, of course, caters for the professional status of those engaged in the mining and minerals industries and includes many who do not see themselves as engineers. Nevertheless, the debate is important to these other groups whose livelihood is inextricably bound up with those who are engineers and there are many facets of the engineering policies being shaped that will, I am sure, eventually be enshrined in the requirements for professional status across all the various disciplines in our industry.

Jan 1, 1986

By F Mavroudis, M Gaastra

Due to the increasing demand for resources worldwide, efficient utilisation of raw material deposits and recycling technologies become more and more important. Growing industrial nations and increased living standards require a large raw material supply. Hereby responsible handling of existent primary and secondary raw materials is indispensable. By utilising state-of-the-art technologies resources are extracted, recovered and recycled more efficiently which increases sustainability. Hereby sensor technologies combined with intelligent data processing systems in particular provide a considerable research area. Innovative sensor technologies are already implemented during recognition of material-specific characteristics, during elemental recognition as well as during machine control. They are applied to attain increased automation levels of mining machineries, higher recoveries during mining and processing as well as higher recoveries. To be able to face the increased demand for sensor technologies and the integration into raw material industries, an interdisciplinary association of three RWTH Aachen University Institutes has been founded. The association has expertise on increasing productivity and capacity utilisations by automating mining and recovering processes by sensor technologies. Due to the utilisation of sensor systems, materials and structures can now be detected and elementary analysed on a real-time scale. The developed and enhanced techniques are the key for any ambition of autonomous plants and machineries. This paper gives an overview on the regarded sensor technologies for material recognition, machine automation and mineral processing. The authors present concepts based on extensive laboratory and field studies of successful implementation and application the technologies considering special mining conditions. Overall three applications are described to demonstrate the potential of sensor technologies for autonomous and sustainable mining: real-time analysis: recognition of elementary compounds during extraction processes; multi-sensor system EiControlPlus: designed for automation of longwall shearers by complete detection of the machineÆs environment; and sensor-based sorting: applied in recycling and mineralÆs industries.

Sep 26, 2011

By M I. Pownceby, A Torpy, C Johnson, N C. Wilson

To extract uranium from low-grade, calcrete-hosted uranium (CHU) ore is challenging owing to the presence of carbonate and swelling clay gangue minerals that require an alkaline lixiviant to be used. Western Australia possesses ~75 000 U3O8 t in CHU resources. Improvements to alkaline leach extraction practices would improve the economic potential of these deposits.A column leach study of CHU ore was run for 105 days using an alkaline carbonate-bicarbonate lixiviant. The uranium content of the liquor plateaued after 75 days at ~275 mg U/L; the calculated maximum solution capacity was 800 mg U/L. Spiked peaks and troughs were seen in the data set beyond the 60th day, where concentrations ranged from 220 - 290 mg U/L, indicating possible cyclic uptake and loss of uranium from the solution.Pristine and leached ore samples were geochemically analysed and mineralogically characterised at high resolution using a field emission gun-electron probe micro-analyser (FEG-EPMA). Results showed that leached ore samples from the top of the column contained less carnotite than pristine ore. In contrast, leached ore samples from the column base contained regions with more carnotite than pristine ore, indicating precipitation. Three carnotite grain micro-structures were identified in the leached ore; fan-spherulite, granular and core-shell cubes, with evidence for multiple growth phases.Evidence of carnotite precipitation was seen at the edge of and in pore spaces within montmorillonite and dolomite grains. The point of zero charge of both minerals is lower than the pH of the lixiviant (pH 10.8), thus the mineral surfaces are negatively charged and would not attract UO2(CO3)34- ions out of solution. Similarly, the decrease in the uranium content of the lixiviant is not attributed to super-saturation, as this was unlikely to have been achieved. Work is ongoing to understand the reason for carnotite precipitation and the fluctuations in the lixiviant uranium concentration that are seen.CITATION:Johnson, C, Pownceby, M I, Wilson, N C and Torpy, A, 2013. Microscale characterisation of pristine and processed ore - implications for leaching calcrete-hosted uranium ore, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 303-316 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By A J. MacDonald, M P. Raffield

The South Deep massive orebody consists of 20 to 30 m of payable conglomerates ranging in dip from 11¦ to 20¦ and at depths of between 2400 m and 3400 m. The mine design process selected a mining method with a proven record of application that could be adapted to overcome the inherent difficulties associated with the depth, thickness and structural influences of the South Deep orebody. A modified cut and fill mining method provides a concentrated and highly flexible method of extraction. An integrated destressing cut will enable the modification of the stress environment such that it is suitable for massive mining operations. The choice of backfill type and stoping width in the destressing cut ultimately determines the characteristics of the stress modification and, as such, is critical to the success of the cut and fill operation. This paper discusses the decision process undertaken to determine the optimum backfill type and stoping width combination in terms of, conditions in the destressing cut faces and in the massive mining environment. Numerical modelling has been extensively used to analyse various scenarios to aid in the decision process.

Jan 1, 1998

A generalised mathematical model for hydrocyclone classifiers was developed by the author (Nageswararao, 1978) using dimensionless groups which include phenomenological characteristics as independent variables. This model is incorporated in JKSimMet, the steady state mineral processing simulator developed by JKTech.Recently, when this model was rewritten (Lynch and Morrell, 1992), in terms of variables other than those used by the author, a few errors have crept in. For example, while the exponent of (Du/Dc) in the equation for d50e should be negative (-0.47), it was recorded as positive (0.47). Also, the exponent of (DoIDe) in the equation for pressure drop should be 0.67 and not 0.60. In the same equation, the exponent of Dc would turn out to be -0.10 and not 0.15. These are clearly attributable to typographic and rounding off errors, while transforming the original equations.More recently, Cilliers (pers comm) has done a comprehensive evaluation of the major semi-empirical models for hydrocyclones.He observed that the major difference between the cyclone model developed by the author and other models lies in the method of quantifying the effect of spigot diameter on d50e. He noted that while all other models predict an increase in d50e with a decrease in the spigot diameter, the model as cited by Lynch and Morrell (1992) predicts just the opposite. However, he conjectured correctly that the discrepancy could be due to a typographic error. As the model is still unpublished, it is felt that the original model equations should be recorded with the correct exponents, so that errors in predictions other than those due to the limitations of the model itself could be avoided. They are given hereunder.

Jan 1, 1995

By T G. Measham, D A. Fleming

When attempting to understand potential regional or community socio-economic changes that resource-extraction industries may produce, it is important to analyse the channels that promote these changes. In this study, we propose a conceptual framework to better understand how socio-economic effects are likely to emerge in regions impacted by mining. The framework considers three levels of hierarchical effects (Measham, Fleming and Schandl, 2016).In the first level, the resource-extraction industry causes four direct initial impacts on nearby communities: labour demand shock (mining employment generation), income generation (compensation to landowners and higher wages), environmental consequences and land tenure/Aboriginal issues and an increase in local tax revenues.The second level is shaped by the subsequent population increase (given by immigration of permanent or temporary residents) produced by the new levels of employment and income that resource windfalls can generate in resource-extraction regions. These increases in employment, income and population become the source for a rise in the demand for local (and non-local) goods and services.Finally, the third level is given by boomtown-like and other socio-economic effects generated from the initial effects.CITATION:Measham, T G and Fleming, D A, 2016. A conceptual framework to understand the local community/social impacts of mining, in Proceedings Life-of-Mine 2016 Conference , pp 188–190 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016