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By D A. Williams

The conventional method of transporting mine tailings from a process plant to a tailings storage facility (TSF) is in the form of a low to medium density1 slurry, which can be pumped using centrifugal pumps. Over the past several decades, therefore, mine operators have generally adopted this default approach. There are, however, some convincing arguments why consideration should be given to thickening the tailings slurry to a higher density paste consistency. In particular, the minimisation of environmental impacts, the reduction in water consumption and the cost savings relating to TSF closure make paste an attractive option for the life of mine tailings disposal. There are several environmental impacts that are associated with a conventional slurry TSF, such as land sterilisation, aesthetics, dust, seepage and acid mine drainage. Some of these impacts, such as dusting, may be difficult to mitigate while the TSF is in operation. Others can be influenced by adjustments made to the tailings slurry density at the plant. Unplanned fluctuations in slurry density and/or viscosity can have a significant influence on TSF performance and can exacerbate the environmental impacts relating to the facility. Relatively minor changes in the solids content of the slurry can affect tailings beaching behaviour, degree of segregation, position of the phreatic surface, amount of freeboard, consolidation behaviour, placed (settled) density (and hence TSF capacity) and in situ strength of the tailings. Paste is a non segregating slurry and many of these effects can be minimised at the TSF when the tailings slurry is thickened to a paste. These improvements are manifested by reduced seepage, flexibility in selecting an appropriate final landform, ability to rehabilitate progressively and reductions in plant water usage. It is possible to minimise environmental impacts of a TSF through the use of tailings paste. Ideally the paste production plant should be part of the initial design of the process plant. However, significant benefits can be gained by adding a paste production plant at some time later in the operational life of the mine to reduce environmental impacts and facilitate an environmentally acceptable TSF closure.

Jan 1, 2002

By P Voigt, B Lumsden, P Lines, I Gurnett

Plant tests of magnetic conditioning have shown increased flotation recovery of paramagnetic sulfide minerals (chalcopyrite, sphalerite and pentlandite) in the -38 ¦m size fraction within rougher and cleaner flotation circuits. A statistical plant test was undertaken in the Mount Isa zinc flotation circuit where magnetic conditioning was tested simultaneously in both the rougher circuit and the cleaner retreat circuit (cleaner scavenger). This test resulted in a normalised increase of 1.60 per cent in the rougher circuit zinc recovery and simultaneously a normalised increase of 4.60 per cent in the cleaner retreat circuit zinc recovery - to a very high level of statistical confidence. Interestingly, in a novel approach, it was possible to verify the plant test results in two ways. Firstly, detailed MLA analysis of the tails confirmed the statistical plant test results and showed that the greatest effect of magnetic conditioning was on the sphalerite in the C3 - C6 size fraction, where there was a reduction of around 15 per cent in zinc in tails. Moreover, there was a reduction of around 15 per cent in liberated sphalerite across all -38 ¦m size fractions, but only a seven per cent reduction in non-liberated sphalerite in the tails. Secondly, plant modelling showed that increasing the rougher zinc recovery would cause an increase in zinc feed grade to the cleaner retreat circuit. The increase in the zinc feed grade to the cleaner retreat circuit with magnetic conditioning was demonstrated to a very high level of statistical confidence.CITATION:Gurnett, I, Voigt, P, Lumsden, B and Lines, P, 2012. Magnetic conditioning of sphalerite at XstrataÆs Mount Isa Zinc Operations, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 233-240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Although the diesel engine is normally considered a tried and proven power source, many new and exciting diesel design concepts are being evaluated in engine development laboratories around the world. Three such programs currently underway at Cummins Engine Company are discussed. The turbocompound engine converts into power exhaust heat energy which is normally wasted. It does this by incorporating after the turbocharger a low pressure gas turbine which is gear driven to the crankshaft. The adiabatic engine has no conventional cooling system. It converts into useful power most of the heat energy normally rejected to the coolant. The series boost turbocharged engine uses seperate low and high pressure turbochargers to increase engine output and improve transient performance. These design concepts make possible increases in diesel engine thermal efficiency from the current 33 to 38 per cent range to the 50 percent range.

Jan 1, 1982

By G Diprose

Diamond exploration in Queensland is influenced by the South African approach modified by the discovery of diamonds in Lamproite in Western Australia. The current approach is to explore for Kimberlite and Lamproite bodies using indicator minerals dispersed by fluvial and colluvial processes. In the north-west, diamonds are derived from kimberlitic and lamproitic sources, whereas those in the coastal and subcoastal areas of eastern Queensland are associated with xenoliths included in rocks formed during Cainozoic volcanism. In these areas, sapphire is commonly associated with diamonds. In New South Wales diamonds in economic quantities occur in alkali basaltic intrusions and a subduction model has been proposed for these occurrences (Barrows et al, 1996). Exploration for diamonds in Australia increased following the discovery and exploitation of the Argyle mine. State geological surveys have produced digital information on the local occurrences of diamonds. As part of the Smart Mining Initiative (2006 - 2010), the Geological Survey of Queensland compiled a database and report on microdiamonds and diamond indicator minerals from open file company exploration data from 1968 to 2008 from the Department of Mines and EnergyÆs QDEX system. Most exploration in Queensland was conducted with exploration for other commodities. There is no commercial exploitation of diamonds in Queensland and, to date, only rare occurrences of microdiamonds. There is a regional difference in diamond occurrences with the kimberlitic and lamproitic models favoured for the north-western regions of the State and the subduction (S-type model) favoured for the eastern coastal zone linked to Cainozoic alkalic basaltic volcanism. Further diamond exploration is warranted in Cainozoic basalt provinces along the eastern coastal and near coastal regions and in the north-west of the state in conjunction with airborne geophysics flown as part of current Departmental Smart initiatives. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By D Smith, D Reid, D Bradshaw, C Brough

The Merensky Reef at Northam Platinum Mine in South Africa is characterised by a high degree of variability with respect to reef elevation (difficult to mine), as well as mineralogy and texture (difficult to process). Development along strike and down dip of multiple reef types has led to unpredictable run-of-mine characteristics that pose problems for the mineral processing circuit at Northam. Following mining terminology, Normal, Transitional (NP2) and Pothole (P2) Merensky reef types can be defined, and this geometallurgical study aims to characterise and understand the relationship between their mineralogical characteristics and laboratory scale batch flotation performance. The plagioclase-rich NP2 reef ore is the easiest ore to process in terms of capacity for high mill throughput as well as flotation performance. The lack of very fine-grained disseminated sulfide textures in the NP2 reef ore results in better liberation characteristics relative to the Normal and P2 reef types. Consequently, chalcopyrite, pentlandite and sulfide recoveries are highest for the NP2 reef ore. The lack of ferromagnesian minerals in the NP2 reef ore also results in the recovery of the least amount of floatable gangue during flotation tests. The Normal and P2 reef ores are similar to each other, with an orthopyroxene-rich mineralogy with associated alteration minerals. The P2 reef is also characterised by the highest sulfide content and degree of pentlandite liberation. Chalcopyrite, pentlandite and pyrrhotite liberation is only significantly increased by a change in grind for the Normal reef ore. The change in grind, however, only significantly affects pentlandite flotation performance and overall froth stability for the Normal reef ore. However, for all three ores, a small change in grind has a detrimental effect on pentlandite flotation performance.

Jan 1, 2008

By Graham JW, Cullen GV

edicted increase in, Aluminium production and the possibility of a diminishing supply of petroleum coke for anode electrodes in alumina reduction cells makes it desirable to find alternative electrode materials. Brown coal char, with a lower ash content and with an elemental purity similar to petroleum coke, has been produced by leaching in hydrochloric acid, washing with water and charring at 115000. The cost of processing is estimated to be competitive with petroleum coke. Without further processing the bulk density and real density were undesirably low, but. by briquetting the coal before charring and crushing, the bulk density was improved to 92 per cent of the petroleum coke value and the Particle density was improved to 92 per cent of the density of petroleum coke by water-displacement or 75 per cent by mercury displacement. Pre-baked electrodes were prepared from the char alone, mixtures of petroleum coke and char and from petroleum coke alone, all bonded with coal tar pitch. The electrodes were tested for the usual physical properties and were, evaluated for performance in a laboratory size alumina reduction cell. Electrodes based on brown coal char alone were found to be inferior in physical properties, and performance, but mixtures of the char and petroleum coke, despite poorer density, electrical resistivity and carbon consumption on a theoretical basis, in performance tests gave up to 17 per cent better carbon consumption per weight of aluminium produced and 21 percent better electrical current efficiency than the electrodes based on petroleum coke alone. It is suggested that larger scale tests are warranted.

Jan 1, 1970

By Wagland D. G, Guo H

The Mt Whaleback orebody is in a complex geological regime. A good understanding of geological structure is essential during the design and implementation stages. The amount of information on the rock-mass condition available at the design stage is considerably limited. It is essential to validate the rock-mass properties used in the design during implementation. It is important to achieve integrity of the final pit wall during development and to maintain the integrity until the end of its designed life for safe and economical extraction of ore. The original geological model is updated by way of on-going detailed geological face mapping. Original design is reassessed and is modified based on any significant variations to the previously evaluated geotechnical conditions. Information gathered during design implementation provide tools for effective management of the pit walls. Controlled blasting techniques are employed in the final limits blasting. Presplit blasting is used in most limits blasts. Presplit helps to maintain the integrity of the wall by venting excessive gases from the limits blast. This helps to reduce bedding dilation by gas penetration. Also, it helps to define the design batter for the operators for final batter trimming. Pyritic shale needs special attention during blasting due to its reacting nature. Cablebolting is applied in selective areas to secure small-scale potential instabilities. During the development phase, pit wall monitoring instruments are installed. These instruments are used to monitor the performance of the wall during and after excavation of the slope.

Jan 1, 1995

By Yeliseyev AK, Shestakov AM

Comminution is the most power-intensive process in the technology for ferrous quartzite concentration. That is why improving comminution efficiency leads to the most appreciable economic effect on the concentration process. The trend towards reducing the lump size of crushed ore before charging the mill is considered to be of major importance in improving comminution efficiency. A considerable number of investigations have been performed in this direction. At the same time, a strong interest is also maintained in the increase of comminution efficiency due to optimisation of process taking place in the mill. Recently, investigations of the power intensity of the breaking process inside the mill have been carried out at the Krivoy Rog Mining Institute. It was ascertained that the routine conditions of comminution at a low mill ball charge ratio resulted in an unnecessarily high power consumption due to the force of impact of falling and milling bodies far exceeding the power required for comminution. For example, the power value for falling balls of 60 - 125 mm in diameter reaches 0.3 kNm, and the force and stress due to ball contact with the lining reaches 60 kN and 250 MPa respectively. These values exceed the force required for comminution by a factor of ten. Analysis of the mechanism of ore particle size reduction during comminution in the ball mill indicates that the size reduction is due to impact load, attrition load, and static load. The efficiency of size reduction is very low. During comminution in the ball mill, impact loads prevail and amount to 85 - 90 per cent of the total load. In this situation, not more than 10 - 15 per cent of destruction is due to attrition.

Jan 1, 1993

An empirical kinetic model is discussed that enables the number of stages in a carbon-in-pulp plant and the amount of carbon in each stage to be calculated for any desired metallurgical performance. It is shown that a knowledge of the kinetics of gold extraction by activated carbon in each stage assists plant operators in the important' areas of process control and optimization. Factors such as mixing efficiency, concentration and distribution of carbon through the plant, bypassing of pulp through a stage, and carbon poisoning are examined. The resin-in-pulp process for the extraction of gold cyanide is also discussed, and the chemistry of absorption and elution on strong- and weak-base resins is examined. In addition, operating results from a small-scale resin-in-pulp pilot plant are presented, and various applications in which resin-in-pulp may be preferable to carbon-in-pulp are discussed.

Jan 1, 1982

Over the past 15 years, Artificial Intelligence (AI) techniques have shown promise of providing the ability to capture `human intelligence' into a computer program. The sub-fields of Expert Systems and Artificial Neural Networks are finding increased use in industry to perform tasks previously considered the domain of human thinking. But, are these methods just a new type of software much like that of the past or is real magic hidden within the lines of code? Will this field continue to enjoy high growth rates and if so, what developments will we see in the near future? Which algorithms and methodologies will continue to grow? This paper discusses a number of paradigms which can be used to create successful applications. There are certain barriers; some psychological - some linked with knowledge acquisition, that must be overcome or avoided to ensure system performance. Development time also requires careful consideration before embarking on an Al project. The paper focusses on constructing goal-driven systems that transfer high-technology solutions from the research laboratory to the plant floor. Respect for system users is of paramount importance - whether their involvement is to access contained information or to participate in program maintenance as new knowledge becomes available. Examples of successful and unsuccessful AI implementation in Canadian industry and academia provide evidence of the importance of this issue. The paper also examines some current constraints on applying AI in the real-world. Among these problems are automated knowledge acquisition, methods to acquire data during run-time, real-time systems (hardware versus software), explanation and justification features and adaptive/leaning systems.

Jan 1, 1995

Solid EnergyÆs project evaluation process utilises a standard staged gate approach, with five levels leading ultimately to project execution (level 6). For a project to progress through each level, specific financial criteria need to be satisfied. Solid Energy primarily use value based (discounted cash flow) metrics to support investment decisions. Within this approach Solid Energy utilise a number risk-based techniques to quantify project uncertainty. This includes the use of risk-based probabilistic analysis using Monte Carlo simulation and probability-based scenario analysis. Figure 1 shows the net present value (NPV) cumulative probability. Project risks are identified through comprehensive risk workshops. The output of these workshops (list of key risks, ranges of uncertainty and probability of occurrence), is quantified within the financial models. Incorporating this risk information on a probabilistic basis allows an investment decision to be made with a robust knowledge of the range of possible project outcomes along with the likelihood (probability) of those outcomes occurring, for example 80 per cent confidence that the project value will be greater than NZ$10 M, 50 per cent confident it will be greater than NZ$50 M and ten per cent confident it will be greater than NZ$70 M. Incorporating risk implicitly into the financial analysis allows the business to easily evaluate/measure projects with different risk profiles. The detailed risk analysis does away with the complexity of arbitrary risk-based hurdle (discount) rates, as projects can be evaluated based on their specific risk characteristics. Whether a project will progress to the next level of investment and ultimately into implementation depends firstly on the value assessment in comparison with the associated risk/uncertainty, and secondly matching this with the businesses appetite for risk. At Solid Energy standard criteria are used for specific project evaluations, but in addition projects are considered on a portfolio or strategic basis also. Solid Energy attempts to maintain a mix of low risk (low value) projects with some high risk (high value) opportunities. The mix of projects must remain in line with the shareholdersÆ risk appetite. One of the keys to a successful investment decision is ensuring that the appropriate information is available to decision-makers so that they may proceed with a comprehensive understanding of the risks and impacts associated with the decision.

Jan 1, 2007

Stringent environmental benchmarks imposed by governments and successful legal challenges in the country of origin have changed the risk profile for all mining companies over recent years. In developing countries, however, where high government standards may not always be in place, direct community action has often made worthless substantial investments in otherwise viable mining operations. Real limitations are therefore imposed from these risks on all areas of mining activity, wherever they may be. Thus, the bar has been raised for all companies developing or operating mines. This paper argues real financial and global industry reputation benefits accrue when all known environmental risks, where practical, are managed. In response, among major international mining companies, as the industry moves towards greater global consolidation, senior management teams have increasingly adopted corporate governance standards including æTriple Bottom LineÆ (shareholder/government/community) sustainability reporting. Sustainability reporting is encouraged by improved international stockholder and financial investor perceptions by contributing to lowered social, community and geopolitical risk which lowers the cost of access to funds as well as improving staff morale and productivity. New mines must not only be primarily financially viable but must operate throughout in a sustainable way. Case studies of some recent mining operations, who have not foreseen or proactively managed major environmental risks, demonstrate the dire financial and personal implications for managers, directors and shareholders from not identifying and managing these environmental risks. Merely having a corporate policy statement on environmental standards or high level Government approvals process for a mining activity does not preclude mining operations from the risk of direct action by local populations or future adverse legal implications from risks which were perhaps identified but not mitigated effectively. Methods and processes for the identification and active management of environmental risks in the global arena are discussed to add a practical element to sustainability, based on the authors recent strategy development processes with governments and major mining houses such as BHPBillition, Rio and Xstrata. Emphasis is placed on proactive, innovative yet practical solutions which, where possible, show positive contributions firstly to the financial bottom line but also the community at large.

Jan 1, 2003

An improved method of sample recovery for use with rotary percussion drilling has been developed. Cuttings can be recovered continuously from either dry or wet drilling, and the recovery under dry conditions is seldom below 99% of the cuttings brought to the surface by the rig. The system is designed for use with top drive drilling rigs using flush-jointed drill rods. The key feature of the system is a self-aligning mechanical seal around the drill rods. The sealing unit is removably fixed to a collar section of cas ing. the cuttings are recovered in a plastic bag attached to the bottom outlet of a cyclone. A valve at the bottom of the cyclone permits the cuttings representing various depths to I,e recovered separately for examination eind 0(iclysis. [u the Iron Monarch quarry, two percussion holes were drilled to depths if 30 metres and 28 metres using the unproved sample recovery system, and diamond drill holes bored 1 metre from each percussion hole. Samples from each hole were sectionalized over metre intervals and analysed for iron, silica, alumina and loss on

Jan 1, 1976

By P Commander

Western Australia is a major exporter of minerals, which places significant economic and environmental responsibility on Government and the stateÆs mining industry. Moving into the 21st century, mineral production in Western Australia is $14 billion accounting for 50 per cent of the stateÆs export income. There are over 60 large-scale mining operations distributed throughout the arid regions of the state (less than 300 mm/year rainfall). There are four key mineral provinces in arid Western Australia including the Pilbara (iron ore), Murchison (gold), Northern and Southern Goldfields (gold and nickel). These provinces have significant differences, particularly in respect to groundwater demand from mining and mineral processing, aquifer systems that are utilised, and approaches to groundwater management. The arid nature of the stateÆs interior and subsequent lack of surface water resources has required substantial groundwater resource development by the mining industry. A variety of aquifers have been explored and utilised ranging from shallow alluvium and calcrete, discrete fractured zones in bedrock, concealed palaeochannels and inland sedimentary basins. Groundwater usage by the mining industry is about 150 GL/year with most abstraction related to mine dewatering, mineral processing and dust suppression. Groundwater abstraction in Western Australia is regulated by the Water and Rivers Commission. In the Goldfields, the depletion of brackish (>2000 mg/L) and saline groundwater from storage is permissible, as mining is considered the beneficial use for groundwater which may be as much as 200 000 mg/L. In contrast, the low salinity groundwater of the Murchison and Pilbara is allocated on a sustainable basis. The role of monitoring and ongoing aquifer reassessment is crucial in water management, in evaluating the condition and performance of stressed aquifer systems. Mining operations face a variety of water resource issues ranging from insufficient availability for processing to excessive mine dewatering. These issues also change as a mine operation proceeds through its development, commonly starting with a deficiency and moving into surplus as deeper pits require more dewatering. Operating mines have to contend with three main issues: water supply, wastewater disposal and contamination of local water resources. In contrast, post closure issues are related to aquifer recovery or re-establishment of groundwater equilibrium, development of pit lakes in mine voids and isolation of waste products and associated seepage or run-off.

Jan 1, 2003

Fundamentally, the development of a minerals processing project is a very risky enterprise. Most mining companies do not have sufficient financial resources to undertake significant projects and hence have to undertake external financing. Indeed, most resource companies understand the high risks associated in developing their projects and therefore, wish others to share in the risks. Most merchant banks, on the other hand, are searching to find suitable resource development projects in which they can share their risk and also share a large proportion of the ærewardÆ. To resolve this issue a Feasibility Study is completed by the project developer and assessed by the merchant bank often with the assistance of an æIndependent EngineerÆ (IE) who assesses the validity of the development proposal. Generally speaking, unless the Feasibility Study has been prepared improperly, the technical aspects of most mineral projects are reasonable. Some of the more recent so-called æhigh techÆ projects are exceptions but these still do not present major technical mistakes or misconceptions. p> In most cases, the major criticism the IE presents after discussing the validity of the ore reserves focuses on production plans, capital costs and operating costs. Of these three parameters the production plan is one in which owners tend to be far too optimistic and financiers, until recent years, have not taken a position. The most critical part of the development plan is the ability of the project, as designed, to attain the required design performance and, even more critically, the ability of the owner to reach and sustain this level of production. In short, how long should the æramp-upÆ be planned to take? Financiers have become more circumspect and are now taking a more conservative view of new project performance by factoring into their project financial analysis longer periods of ramp-up, higher capital costs and higher operating costs. However, these financiers can also be part of the æproblemÆ if they become overly conservative. This paper attempts, by way of case studies available from the public arena, to identify the pitfalls the project owners can meet and possible means of avoiding the disastrous financial conundrum whereby the second or third æownerÆ is the company that reaps the rewards initially extrapolated. The paper briefly discusses this problem by referring to projects known to the author and including previous studies that looked at this very problem. It is emphasised that many of the opinions stated within the paper are strictly those of the author and could be subject of much debate.

Jan 1, 2003

By M P. Sandy, J B. Simpson

The empirical stope design techniques developed by Mathews et al (1981) and refined by Potvin (1988) and others, have gained rapid acceptance in Australia in the 1990s as a simple, æfirst-passÆ means of designing primary stopes. However, it is recognised that these æstability graphÆ methods can only provide broad design guidelines. Recently published stability graphs (Hutchinson and Diederichs, 1996) encompass a wide range of geological environments, which are not discussed, and the influence of time and blasting practices cannot be easily reviewed. The æscatterÆ in the graphs must reflect, to some degree, different operating practices as well as subtle but important differences in the pre-mining conditions that are not adequately accounted for in the æmodified stability numberÆ. Development of a ælocalÆ, site-specific stability graph may overcome some of these problems. At NormandyÆs Golden Grove Operations, Western Australia, detailed reviews of stope stability performance, including Cavity Monitoring System (CMS) surveys, are undertaken for every stope, with the objective of developing a series of local stability graphs, customised to site conditions and calibrated in terms of æAverage Falloff ThicknessÆ (AFT). Cablebolting of stope hangingwalls is used to develop reinforced æbeamsÆ on each sublevel, effectively dividing the full span into smaller, more stable æsubspansÆ. By analysing stope stability performance in terms of fall-off, cost-benefit studies can be undertaken of the effect of cablebolting and other options for modifying stope spans. The approach used to develop the local stability graphs, and their integration into routine stope design procedures at Golden Grove, is described. The experience gained during stope extraction in the Scuddles orebodies has been successfully applied to the Gossan Hill æC-PanelÆ orebody. This methodology should be applicable to other underground mining operations.

Jan 1, 2000

By Cocker A, Kavetsky A

A numerical model describing blast fragmentation and damage in three dimensions has been developed at the Julius Kruuschnitt Mineral Research Centre (JKMRC) and applied to numerous blasting operations in mines throughout Australia. The model combines the rock structure (summarised by block size distribution) with blast strain energy and uses comminution theory to calculate the resultant block size distribution. The model distinguishes between rock breakage and failure, the former being defined as size reduction and the latter as block dissassembly. The background and basis of the model are discussed in detail and three case studies presented describing the application of the model to explosive performance evaluation, explosive selection and drill selection in Australian mining operations.

Jan 1, 1990

The Telfer Gold Mine, owned and operated by Newcrest Mining and located in Western Australia, is currently being expanded. A new underground sublevel cave development is proposed along with an appreciable expansion of the open pit. The Telfer area is generally subject to low rainfall, however, during the wet season cyclonic events can result in sizable rain events, which have the potential to cause substantial inflow. In addition to this, during the first five years (nominal) of the mineÆs life, there is the potential for drainage paths between the pit and the underground mine via decommissioned underground workings which lie directly under the pit. After this initial five year period the pit floor will be mined out below the old workings and will therefore no longer connect to the underground, however cave breakthrough to the surface may start to occur thus providing another water path into the underground mine. To arrive at an optimum, safe solution for dewatering the mine that successfully addressed the above items, a rigorous risk analysis was included as an integral part of the design process. This involved the determination of the probability of events occurring and the consequences of these occurrences. This was compared against the cost of mitigation for the various events. This paper outlines the process by which a safe concept addressing all the issues relating to dewatering the proposed mine has been arrived at. This process included: Establishing the pit catchment areas. These were based on historical run-off data and took into account practical mitigation works. Establishing an Average Recurrence Interval (ARI) based on reference material and historical rainfall data. Utilising a standard approach based on Australian Rainfall and Run-off (ARR) to calculate pumping and storage requirements for the various catchments. Analysing the 20 years of recorded rainfall in the Telfer area to establish the duration, magnitude and sequence of events. This analysis assisted in determining the surface run-off coefficient. Establishing potential water storage areas and determining the risks associated with using particular storage options. Establishing the percolation rate through the cave zone. A degree of uncertainty regarding the percolation rate in the cave zone required that the consequences of using various percolation rates were considered to aid in establishing the rate which was adopted. Establishing preliminary concepts and determining the most economically viable concept. Conducting a risk assessment based on the principles outlined by Australian Rainfall and Run-off (ARR) to confirm that the appropriate Average Recurrence Interval (ARI) had been selected. A risk assessment was also conducted in accordance with client requirements. Establishing the optimum pump station sizes and storage capacities. Establishing the appropriate numbers of duty and standby equipment. By using the foregoing process, which included a number of stages of risk analyses, an optimum dewatering system concept was produced.

Jan 1, 2003

By Hoberg H, Schnieder FU

The disposal of residues from coal preparation and processing will to an increasing extent require investigation and consideration of the environmental problems resulting as a consequence of this. Different authors (Diingelhoff and Plankert, 1983; Hasenpatt, 1985; Szczepanska and Twardowska, 1987) have concentrated primarily on the content and the mobilisation of inorganic contaminants such as chlorides, metals and heavy metals from spoil tips, while no publications have yet been found on the question of a possible emission of organic contaminants (PCB, PAH, HC HC) from processing residues. Here the flotation residues in particular are able to bind larger quantities of organic contaminants by physi-sorptive means because of their large specific surface and, after disposal, to be re-emitt than into the environment. The flotation agents used in coal flotation are mixtures of technical distillation products with a correspondingly fluctuating composition. As Hey, 1986 showed, they may contain, in addition to the main components (n-alkanes, alcohols, surfactants), over 50 individual trace substances. In conjunction with the structural-chemical similarity of the individual components, this complicates the quantitative analysis of individual components considerably. For the analysis of hydrocarbon content of flotation products by means of extraction with organic solvents in accordance with DIN 38408, H18, the difficulty arises, besides the insufficient sensitivity at low concentrations, that geogeonic hydrocarbons are extracted from the coal as. well and the analysis results are thus falsified. These problems were overcome by the application of the 14C radiotracer method where certain components of the flotation agents are marked with radioactive carbon (14C). By measurement of the radioactivity of solid and liquid samples, the concentration of the marked substance can be measured very sensitively and precisely, whereby the accumulative measurement of similar organic substances is ruled out. Thus the reaction path of certain substances in complex reagent mixtures such as flotation agents can be traced excellently and the conceivable environment burden resulting from flotation tailings disposal can be estimated. In this paper, the adsorption behaviour of typical components of coal flotation agents are investigated for different coals and types of gangue material, the reagent content of flotation concentrates and tailings, as well as the mobility of the reagents adsorbed onto solids. The knowledge of adsorption and desorption mechanisms of unpolar hydrocarbons emulsified in water to solids are also of particular interest for the understanding of processes of organic soil contamination and for the further development of washing processes for oil-contaminated soils.

Jan 1, 1993

In 1953, Dr N Fisher of the Bureau of Mineral Resources, acting on behalf of the Society of Economic Geologists, which is considering the sponsoring of a uniform system of nomenclature for ore reserves, enquired from The Australasian Institute of Mining and Metallurgy whether it had ever considered this subject and particularly whether it had ever set up any standard definitions or specifications with regard to ore reserves.As this had not been done, but was thought to be desirable, the Council of The Institute appointed a Committee consisting of H H Dunkin, Associate Professor of Mining Engineering, University of Melbourne (Convenor); E A Rudd, Professor of Economic Geology, University of Adelaide; J D Campbell, Chief Geologist of Western Mining Corporation; and the writer, to consider the report on this subject.In December 1953, the Committee submitted its frrst report to the Council and this report (reproduced here as an Appendix) was widely circulated among member companies and engineers, with an invitation to comment on the proposals. A large number of replies was received and studied.After studying the replies the Committee issued a second report, in part as follows:From these replies we have learned that the suggestions made in the frrst report of the Committee are unacceptable to most of those interested, on one or all of the following grounds:a. number of categoriesb. defmition of categoriesc. nomenclature.It is also apparent that all alternatives suggested in the various replies would likewise be unacceptable to the majority of those replying.As a result, we have come to the conclusion that neither this Committee nor any other could at present and in the present state of opinion on the subject make recommendations regarding classification and nomenclature of ore reserves which would be acceptable to a sufficiently large proportion of members.It seems to us now that the objective of a widely applicable and acceptable system of classification and nomenclature, one that could be endorsed by The Institute and ultimately become standard practice in the industry, requires more than compromise between present conflicting views... it requires first a foundation of substantial agreement on the essential facts, implications and range of ore reserve estimation. This does not yet exist and it is evident that much additional analysis of present practice and opinion must be undertaken before any further systhesis is attempted.

Jan 1, 1994