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An Environmental Impact Statement (EIS) for a major mining development typically has to address various aspects of surface water management, including some which generally tend to be the more contentious: the diversion of rivers and creeks from areas disturbed by mining, and their rehabilitation; the effective management of disturbed area run-off via the collection, containment and treatment of contaminated water on site in sedimentation dams; the collection, containment and treatment of mine pit water; the decommissioning of surface water storages; final void water quality; and water discharge criteria. Environmental Impact Assessment processes for proposed mining developments in Australia at the state and commonwealth level usually involve a form of Initial Advice Statement (or Notice of Intent), Terms of Reference, an EIS, and a Supplementary Report (or similar) which responds to agency and public comment on the EIS. The EIS is used by approval agencies to decide the acceptability of the Project, and to set the conditions of approval. The conditions are often in the form of a state-issued æOperational LicenceÆ or similar. With mining, the initial approval at the EIS stage is often just a pre-cursor to various other planning related approvals, including obtaining a mining lease. Afterwards, mine plans and plans of operations must be submitted to government at various stages of the mineÆs life, ostensibly to provide the detailed mine planning over periods of one û five years. Despite all this additional planning and documentation beyond the submission of the EIS, government approval agencies are increasingly not satisfied with conceptual water management designs and commitments to an outcome (such as meeting a specified water quality standard) in the EIS. Agencies are also requiring sufficient water management design information to be convinced that the outcomes are achievable. To assist proponents of major mining developments, the Queensland Government has published Technical Guidelines for water management, and Environment Australia has published a æBest Practice Environmental Management in MiningÆ booklet on water management. In addition, the Australian and New Zealand Environment and Conservation Council (ANZECC. 2000) has published Water Quality Guidelines which provide an approach to water management, and provide receiving water investigation trigger criteria. So, what are the water management issues that are likely to be the subject of comment, debate and negotiation prior to the EIS being approved? and what commitments may a mining proponent have to make in order to convince the approval agencies that sufficient investigation and design has been provided? This paper provides some answers to this question, by reference to recent major mining proposals which the author has managed through state and commonwealth Environmental Impact Assessment processes.

Jan 1, 2003

In 1989 Henry Fairlie wrote a cover story for The New York Republic, 'Fear of Living'. He noted, `The first Apollo space craft caught fire during a test on the launch pad. Three astronauts were killed, the nation was shocked and horrified, all the more because the screams and scrambles of the astronauts could be clearly heard'. After a brief delay in manned flights, the Apollo program resumed with strong public support; within 18 months, Apollo 11 landed on the moon. Fairlie contrasts the Apollo tragedy to the 1986 Challenger disaster. `The prevailing mood in America so panicked NASA that it took almost three years to send up another shuttle', he observed. `In 19 years between these tragedies, the idea that our individual lives and the nation's life can and should be risk-free has grown to be an obsession threatening to create an unbuoyant and uninventive society.' Taking risks is a normal part of our daily routine. The act of living involves minute-by-minute decision-making focused on survival through the practical management of risks. The act of breathing exposes each individual to the risk of infection while the act of crossing the road could almost be considered suicidal. We deal with these constant threats by observing simple rules of hygiene, safety or what may be labelled as common sense. The rules of community, designed to minimise risk in society, can at times lose focus and result in the imposition of schemes that have a far greater cost than the issues from which they protect. Effective management of risk, whether in the community or a business is about awareness and balance and the elimination of unacceptable risk. Risk cannot be eliminated from our lives or our working environment. However it can be managed if it is properly understood, monitored and controlled. The purpose of my presentation today is not to provide a comprehensive technical risk inventory but to capture the essence of risk and the application of management strategies designed to deal with it in a positive fashion. The basis of our differential financial reward system is risk. The key to successful management is to deal with the downside risks in such a fashion that the benefits of enterprise are not eliminated. The key question any investor must consider is `can the major risks assQciated with a venture be managed or eliminated while retaining a greater proportion of upside potential'. The answer to this question is the ultimate value an investor would assign to any project. In reviewing the relevance of risk to our industry the range of papers to be presented today provide examples of how management deals with specific components of risk. In each case the value of the business has been enhanced by the practical application of balanced risk management. The ultimate success of the industry depends very much on this concept as it also provides a public showcase upon which we are judged. Therefore, from all perspectives the effective management of risk is a cornerstone from which to build a stable and progressive mining industry.

Jan 1, 1994

By Benson R. P

Building a new tunnel to accommodate CN North America's needs or double stacked container traffic for the next 100 years represents new and unprecedented challenges. Innovative approaches to contracting, especially the Negotiated Compressed Process (NCP), TBM design, project management, and the regulatory and approval process, were all required to deliver a new tunnel to meet the needs of CN North America within the approved completion schedule of 33 months compared to a traditional approach of 45 to 48 months. The NCP resulted in trimming a full 12 months from the project schedule with an anticipated saving of direct and indirect costs.

Jan 1, 1993

By Oliver R

The Hamersley Iron ore resources are geologically complex with fluctuations in mineral chemistry. From this resource Hamersley Iron must produce consistently high quality direct shipping products and have the ability to evaluate the effects of changes in demand. In order to achieve these objectives an incremental long term planning technique has been developed. This method reduces the total geological resource statement into a simple, logical sequence of events. A logical sequence of mining increments is defined within individual areas based on a final pit and access system. Increment characteristics are derived manually and from a computer based orebody model. The end product of the technique, an optimum mining schedule, is readily developed from the incremental information. Among its many benefits, this simple technique rapidly provides management with information for policy formulation.

Jan 1, 1979

By Paton T. P

In the technical sense, as well as in the professional sense, the word 'model' can have many meanings. More than 23 000 references were uncovered by a simple literature search on keywords ' MO D EL#. and. (META LLURG#. or. M I NERAL#)' . For the purpose of this paper, 'models' will be considered to be mathematical formulations which attempt to represent or approximate a process. The model may be purely, or a combination of: ò fundamental models, based on the laws of physics, chemistry and thermodynamics; ò semi-empirical or phenomenological models, where an intuitive concept of the process is formulated and found by testwork to fit observed behaviour; and ò empirical or 'black-box' models (including neural networks), where a mathematically convenient form is proposed and fitted. Even under this more restricted definition, which eliminates heuristic and statistical 'models', it is clear that the efforts expended in devising and using models have exploded during the years since the first APCOM Conference in 1961, benefiting from the dramatic decrease in the cost of computer power. This paper reviews the areas of usage of computer modelling in the metallurgical and mineral processing industries, from plant design, through off-line support, to on-line modelling and automatic control. In each area, frontiers of new development of the technology are mentioned. It is noted that, while modelling is now standard practice in design, it is not yet the norm in operating and controlling plants. The reasons for this partial acceptance are, it is argued, less related to the limitations of the technology than to the human and organisational factors involved in transferring technology to implementation.

Jan 1, 1995

The authors have succeeded in providing additional rigour and clarity to the formulation and execution of the dynamic programming algorithm for optimum open pit limit determination. The inclusion of the blocks on the J + 1 column in the search for Pmax, and constraining this search with blocks assigned a value of negative infinity, ensures an optimal solution within the defmed blocks. The effect of the negative infmity blocks is to preclude mining along the diagonal blocks from the first row that they occur in. Figure 1 graphically illustrates the effects of this on the calculation of P. A practical application for constraining mining with negative infmity blocks is the case where the pit outline is defined by lease boundaries and not by the value of blocks to be removed. Any legal, social or physical constraint could be accounted for in the same way.The danger in applying this technique is that the negative infinity blocks will override any other more profitable solutions that may exist. This is in fact what has happened in the example that the authors use. If a further column is added to the left hand side (column -1) and the calculation is carried out again, a more optimal x-section can be found. (If the negative infinity values are removed the same result is obtained.) This gives a pit value of 112 as against the 108 of the authors' optimal pit. This calculation is shown in Figure 2. Lerchs-Grossman optimization is reliable only if there are sufficient columns available to allow "mining" to optimum depth of the ore body and still allow the pit to break out at the surface within the confines of the columns.This author's approach is to create enough columns each side of the lateral limits of the ore to allow the pit to intersect the surface while still within the confines of the block model. Implementing the methods discussed by the authors helps to reduce the number of columns required to achieve this.

Jan 1, 1987

By G W. Wilson

Rehabilitation of tailings impoundments is one of the most challenging aspects in mine closure, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modelling for this hydrologic system becomes difficult, as numerical models capable of analysing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings. This paper describes the development of a flux boundary model that enabled accurate modelling of the unsaturated zone in the tailings impoundment at Kidston Gold Mine, Queensland, Australia. The technique made it possible to accurately predict the spatial variation of infiltration to the tailings as a result of the presence of the phreatic table. The conceptual model defines the boundaries for the Kidston tailings dam, based on a generalised cross-section through the dam. Firstly the shape of the top boundary is described as a function of the particle size of the tailings associated with particle segregation that occurs due to the hydraulic placement of tailings. This function was rigorously tested using in situ infiltration tests and laboratory materials testing. Defining the bottom boundary of the section, ie the phreatic level was done by physically monitoring the phreatic level with 42 piezometers strategically located on the tailings dam. Analysis of this data led to the fixing of this bottom boundary through the introduction of a function that mimicked the shape of the phreatic level. The material properties of the surface layer, specifically the saturated permeability that would govern the infiltration/exfiltration rates of moisture through the top boundary layer were defined on the basis of extensive field and laboratory material testing. A function for the saturated permeability was developed on the principles of particle segregation. Finally a procedure is described for the application of the new conceptual model for the evaluation of the spatial infiltration to a tailings surface using the rigorous one dimensional surface flux boundary code SoilCover. The solution of the calculation described above was then used as the top boundary condition in conventional three dimensional saturated/ unsaturated flow codes, and verified against measured seepage rates from the tailings impoundment under drains. It was concluded that the developed spatial flux function was in deed a most rigorous representation of reality. Although the methodology presented here was applied to the Kidston tailings impoundment only, the authors believe that the principles are directly transferable to any tailings impoundment that has a varying phreatic zone thickness due to the presence of a pond. The mathematical equations describing the typical cross-section would be site specific, but the approach and ultimate solution methodology would be directly transferable.

Jan 1, 2003

The decrepitation technique is a rapid means of measuring abundances, temperatures and to some extent the fluid compositions, of fluid inclusions in transparent and opaque minerals. The method has been used to investigate the hydrothermal fluid systems associated with gold mineralisation in the Tennant Creek, Pine Creek and Halls Creek Goldfields. At the Enterprise Mine, Pine Creek, several different stages of quartz veining are distinguished and within these, gradational changes in fluid temperatures and compositions help to define the centre and nature of the thermal system responsible for the mineralisation. In the surrounding Pine Creek region and at Tennant Creek and Halls Creek, the results were applied on a regional scale to characterize outcrops and aid in the discrimination between potentially mineral- ized and barren outcrops. The decrepitation method involves the heating of a small (lgm) sample of crushed and sized grains up to as high as 800 degrees celsius. During the heating the fluid inclu- sions within the grains develop sufficient internal pressure to physically burst, the temperature of such bursting being dependent on the type of fluid and the prevailing tem- perature at the time the inclusion was originally trapped. The resulting tabulation of the number of inclusion bursts per 10 degree temperature interval is plotted as a histogram of decrepitations versus tempera- ture and called a decrepigram. The decrepi- grams frequently show several distinct peaks at different temperatures which are caused by different populations of inclusions in the sample. The areas of the peaks indicate the abundances of inclusions in each population while the shape and mean temperature of the peak provides a guide to the type of fluids involved. Of particular importance in this study is the presence of decrepitation peaks at fairly low temperatures (around 2000 C. These are characteristic of C02 rich fluids which build up internal pressure very quickly when heated. The Enterprise Gold Mine at Pine Creek comprises a number of overlapping quartz vein systems hosted by Burrell Creek Formation sediments. The geology of this mine has been described at this conference by Dann and Delaney, who have defined several distinct stages of quartz veining based on structural, mineralogical and physical features of the veins. For this decrepitation study, 19 quartz samples from the mine and environs, including some from each stage of veining were collected. These results suggest that there are 4 major vein types, within 3 of which additional small variations can be discerned which are due to gradational changes in the temperatures and fluid compositions in the mine area.

Jan 1, 1984

Epicentres of recent shallow earthquakes in the region (3-12¦S, 126-150`E) were plotted to identify the various plate boundaries in the region, in particular the southernmost one marking the northern edge of the Australian plate. New and published fault plane solutions were examined to determine the style of faulting and state of stress along the Australian plate boundary. From east to west the boundary is first a subduction zone along the Solomon Islands, then a spreading centre across the Solomon Sea, a zone of compression and left lateral strike slip along the Papua Peninsula, almost pure thrusting across the centre of New Guinea and lastly left lateral strike silo through Irian Taya to the outer Banda Arc. The principal stress is very consistent, trending NW to NNW in a near horizontal plane, from the triple junction of the Pacific, Solomon Sea and Australian plates in the east to the Banda Sea in the west. Only along southern Solomon Sea plate margin which is a divergent boundary, is the stress different in type and direction.

Jan 1, 1987

By J L. Merritt

Effective minesite water management requires that this issue be treated as a risk management exercise. The management process is generally far from simple and by necessity must involve a range of personnel covering a siteÆs commercial, operational and environmental interests and responsibilities. The challenge to be collectively faced by these stakeholders is to strike the correct balance between risk and cost. On the other hand, the challenge to be faced by technical services support personnel is to provide stakeholders with information in a format that they can use with confidence. This paper presents the application of continuous operational simulation (OPSIM) modelling techniques to establish appropriate risk profiles for minesite operations. It is necessary that the format of these risk profiles be generic and equally applicable for defining the risk of occurrence for a relatively comprehensive range of activities û eg from of a non-compliant discharge, to the risk of failure to meet production targets. What is more, the profiles need to be quantitatively based and capable of reflecting change in system response to varied operational or management strategies. The techniques presented in this paper are based around a key assumption that long-term records of the climate contain within them sets of sequences that are representative of what can be expected in the future û that is, the droughts, floods, cyclones, good years and bad, long or short, and everything in between. Therefore, if these historical records are run through an OPSIM model for a particular site, then the simulated operational characteristics can be taken as being representative of what can be expected in the future, in the long-term. This lends itself to statistical analysis and translation into the required risk based format. Water Solutions Pty Ltd have been working with Capricorn Coal Management to develop a relatively comprehensive OPSIM model of their operations at German Creek Mine, Central Queensland. Outcomes from the modelling have been used in recent times to provide mine management with risk-based guidelines for both securing and containing mine water inventories. One of the more interesting tasks has been to establish risk based inventory levels that, if reached, would trigger the immediate implementation of a contract for the desalination and re-use of mine water, at predefined rates. Also, lead-time warning of the occurrence of a possible trigger is of importance to operational and commercial planning. To service this requirement the OPSIM model is regularly used to produce lead-time estimates to defined levels of confidence. Case studies of these, and other, applications of the OPSIM model at German Creek Mine are presented in this paper and serve to demonstrate an effective methodology for practical risked based water management.

Jan 1, 2003

By Mozley R

Contaminated sediments are a multinational problem. A crucial factor in solving an environmental problem is knowledge of, not only the amounts of polluted soil, the contaminants involved and their concentration, but also the historical background of the problem. Processing polluted soil is a tailor made activity based on rational decisions resulting from a detailed treatability study. Lack of information about characteristic properties of a specific sludge/pollution combination is the main obstacle in the route from first ascertaining that a particular harbour subsoil is polluted, to final identification of the full scale treatment plant. In the first instance, information must be generated regarding the distribution of pollutants in relation to the distribution of the original geophysical components. Based on this information rational decisions can be made on separation at a particular cutpoint and what sequential techniques should be involved for a certain fraction. For this purpose a `fingerprint method' is presented especially developed for investigation of polluted soil and sediments. The heart of the fingerprint method is a series of sequential hydrocyclone separations, by which a series of products is generated. The objective of the fingerprint method is to select an optimised treatment procedure in which the pollutants are concentrated in as small a volume of material as possible, leaving the bulk of the material clean. The pollutants can then readily be destroyed or isolated from the environment. The philosophy and advantages of the fingerprint method are demonstrated for a harbour sludge containing heavy metals as main pollutants. Hydrocyclone separation combined with flotation of both the coarse and fine fraction resulted in reusable and dischargeable products. Flotation of the fraction of fines was carried out by means of an experimental flotation cyclone enabling the selective recovery of mineral particles with diameters less than 10 microns. The overall conclusion is that design and engineering of treatment flow schemes for polluted dredged materials is a tailor made activity based on rational decisions resulting from the fingerprint information.

Jan 1, 1993

The basic model for the evaluation of any coal-bearing property is the cash flow projection, the major components of which are operating costs, capital charges, taxation and revenue. A range of cash flow projections can be produced by varying the assumptions which underlie the operating costs, by assuming various forms of capital funding, by making assumptions as to future taxation and by speculating upon the present and future market value of the product. As for any model, the informational inputs and assumptions are vital because, no matter how sophisticated the processing, the informational inputs and assumptions cannot be improved by it. That is to say, the validity of the output (the total evaluation itself) cannot be of greater certainty or significance than that of the inputs. The total evaluation can of course be expressed in a number of ways such as the Discounted Cash Flow (D.C.F.) Rate of Return, the Net Present Value or, the Payback Period. The foregoing statement may seem trite. However, it is necessary to be clear about it so as to avoid unnecessary complication and a preoccupation with techniques as opposed to the informational inputs and assumptions. So far as techniques are concerned, much has been written and said about them during the last decade. Most of us have heard, if not always understood, something about probabilistic models, Monte Carlo simulation, sensitivity and risk analysis to say nothing of inflationary costing and the relative merits of developing cash flows in terms of current or constant money. Those techniques have their value, particularly if they can serve to illuminate conclusions which could not be reached on a simple and even perhaps on an intuitive basis. I am, however, reminded of one major coal mining project in which 20 or more major variables were identified, many cash flow projections were run on the computer and a detailed sensitivity analysis was carried out. The major conclusion reached was that the D.C.F. Rate of Return was predominantly sensitive to variations in selling price and operating cost. Of course, the funding and fiscal elements of a cash flow projection have to be dealt with as rigorously as possible. However, in the development of any coal property, capital requirements and taxation are, in part at any rate, dependent upon the assumed operational parameters. If the latter are misjudged, the whole evaluation process is deeply affected. The same is true of revenue, in the sense that, the positive cash flow is a function of output as well as selling price and again, misjudgements about achievable and maintainable levels of production also deeply affect the final evaluation. I shall try to underline the fundamental influence of the technological factors upon lead times, capital costs, operating costs, taxation, funding and the achievable and maintainable levels of production. In turn, these affect the whole question of coal property evaluation and indeed, the likely success or failure of any coal mining venture. I make no apology therefore that this paper does not set out to discuss the more esoteric aspects of the evaluation process but rather, directs attention towards some of the informational inputs and assumptions which merit clarification and discussion.

Jan 1, 1975

By Bogar D. V

Often dewatering of coal tailings is inhibited by the presence of clays, making it difficult to obtain a high concentration, handleable coal tailings. The net result can be a low concentration, chocolate mousse-like tailings which poses significant sedimentation problems in a tailings dam and represents a significant environmental problem. This paper examines the coal tailings from a Hunter Valley colliery where the tailings properties are influenced significantly by the presence of montmorillonite clay. The influence of the calcium ion on the rheology and sedimentation/compression behaviour of coal tailings . containing montmorillonite already dispersed in water was investigated and revealed that very little improvement in the properties is achieved through the coagulation. The preliminary investigations also indicated that the properties of the tailings were dominated by the presence of the montmorillonite clay. Thus investigations were carried out on the clay alone in water. Investigations into the effect of dispersing samples of the clay alone in water and then coagulating with calcium compared with dispersing the clay directly into calcium ion solutions at the same calcium concentration showed huge improvements in the rheology, compressibility, sedimentation rates and sediment solids concentrations for the second dispersion method, which can be called controlled dispersion. The sediment volume fraction solids improved by more than a factor of two by controlling the dispersion of the clay. The reason for the improved properties lies in the suppression of the initial swelling of the clay, which is initially in the sodium form, thus maintaining the parallel orientation of the platelets that is present before wetting. While swelling is being suppressed, ion exchange occurs with the calcium which results in permanent swelling suppression. In the uncontrolled dispersion case where swelling is uninhibited, the clay is allowed to break up and despite the powerful coagulating nature of the calcium ion, the random orientation of the high aspect ratio clay platelets inhibits effective coagulation. Results indicate that the initial electrolyte concentration of the washwater in a coal washery is the critical factor controlling the dewaterability of clay tailings and the handleability of the dewatered product rather than the actual act of coagulating with the calcium ion. The results presented are of clear practical significance and indicate how coal tailings problems where clay dominates the rheology can be improved considerably by knowledge of the surface chemistry.

Jan 1, 1995

By N Murphy and, S Santomartino, M Cramer

Acid rock drainage (ARD) can have detrimental effects on mining infrastructure, water reuse options and environmental discharge. As a result, some form of short- or long-term treatment is required at many mine sites. Successful treatment depends on a number of factors including the selection of an appropriate treatment technology and its correct implementation. A variety of passive and active technologies are available for dealing with ARD. Passive treatment solutions do not require continuous chemical inputs but take advantage of naturally occurring chemical and biological processes. They are often low cost, site specific approaches and are predominantly used in post-closure situations. Passive systems are well suited to drainage with low acid loads and low soluble aluminium concentrations, and are more effective with highly reduced (ie low oxygen) water. While they are often regarded as permanent fixes, most require some form of ongoing maintenance and all have an engineered life expectancy (ie finite carbonate and organic matter budgets). Passive treatments include, oxic limestone drains, anoxic limestone drains, limestone diversion wells, various reducing and alkalinity producing systems, pyrolusite limestone beds, aerobic and anaerobic wetlands, permeable reactive barriers (organic ¦ carbonate and zero valent iron), slag leach beds, and gas redox and displacement systems (GaRDS). Active treatment solutions require a continuous or semi-continuous activity (eg reagent dosing) to correct water quality issues. They can be engineered to treat virtually any type of drainage or site specific ARD issue, and have no set acid load or redox limitations. Tasks handled by active treatment systems are almost invariably larger and more costly than for passive systems. Active treatment approaches include; pH control, adsorption/absorption, ion-exchange, electrochemical concentration, biological mediation/redox control, flocculation/filtration and crystallisation. A range of generally available and proprietary technologies has been developed around these approaches. Active treatment involving pH correction with alkaline amendments is the most common and cost-effective form of ARD treatment. A variety of fixed plant and portable treatment systems are available. Calcium-based reagents, including quicklime (CaO), hydrated lime (Ca(OH)2) and limestone (CaCO3) remain the reagents of choice for the majority of active ARD treatment worldwide. This is principally due to their widespread availability, non-proprietary nature, and variety of proven dispensing technologies and cost-effectiveness. Limestone, in particular, is a very low cost reagent. However, due to æefficiency of useÆ problems with limestone in passive treatment systems, combined with its very low cost, there has been a recent emphasis on developing active treatment systems that use limestone efficiently. As the requirement for treatment increases, there is a growing emphasis on treatment sludge management and sludge stability. The final choice of a suitable treatment technology is dependent upon water chemistry (eg pH, type of metal contamination, acidity), flow rates, acid load, local natural resources (neutralising materials, topography), climate, site logistics, environmental risk and economics. The benefits and limitations of both passive and active treatment technologies are summarised.

Jan 1, 2003

By Denby B, Miles N. J

The underlying theory behind the construction of an on-line size analysis system is described together with an introduction to the Artificial Intelligent techniques that it is founded on. Previous systems based on more traditional technology such as edge detection and dilation algorithms have been restricted by the significant processing power they require, this has resulted in the production of systems with either reduced functionality or severe hardware requirements. A neural network approach offered a new perspective to the problem of size analysis; the ability of a network to learn and recognise subtle patterns in training data before on-line processing is initiated opened up the possibility for the production of a fully functioning practical system. The format of the training data had to be carefully analysed prior to its implementation in a neural network as the capability of a neural network solution depends as much upon a suitable data preparation as it does on the system architecture. To facilitate experimentation with various profile quantification techniques such as fourier and fractal analysis an Image Profile Analysis System was constructed (IPAS) in software on a personal computer. The IPAS system was produced with the aim of pre-processing image data to create data sets for experimenting with external neural network packages. The system allows the analysis of both real images obtained by image capture and simulated images created by an in-built in simulator. A measurement comparison scheme is also included together with a case study concerned with the frequency analysis of simulated images. The power of neural networks combined with the data compression provided by profiling removes the need for direct measurement of individual particles. This has obvious implications on the level of hardware necessary, and ultimately the expense of a stand alone system. The extrusive nature of data collection via an image analysis system will also permit simple installation of a shipped system; eliminating any requirement for interference with existing machinery.

Jan 1, 1995

By Georgi H, Farquhar J. W, Lorrigan A. N

The potential for major new lenses of Volcanic Hosted Massive Sulphide (VHMS) beneath the existing Rosebery Deposit is extremely high. Recent deep drill hole intersections of massive sulphides, including 22 in true thickness at 24 per cent Zn, may significantly extend the life of the Rosebery Mine. The Rosebery Ore Deposit is located within Australia's most prospective VHMS mining district, the Mount Read Volcanic (MRV) arc of western Tasmania (Figure 1). The MRVs are a 10 - 15 krn wide arcuate belt of lavas, related intrusives and volcaniclastics. Rosebery is a major Cambrian volcanic hosted Zn-Pb-Cu-Ag-Au rich deposit which has been over-printed by Devonian deformation and granitoid alteration resulting in local rcmobilisation of the ore. The Rosebery Mine Sequence is composed of an east dipping and east facing, predominately felsic sequence of rhyo-dacitic volcaniclastics, epiclastics, sediments and shale lenses more than 500 in thick. This sequence is bounded by two, low angle (35 - 40¦), east dipping thrust faults, the Rosebery Fault to the west and the Mount Black Fault to the cast. The Rosebery Mine lithologies are summarised in the following table: Hangingwall (HW) Polymictic, quartz, feldspar-phyric epiclastics. Black Slates Graphitic, pyritic mudstones. Host Rocks Turbiditic mudstones and sandstones. Footwall (FW) Feldspar-phyric, pumiceous, mass-flow breccias. Cambrian, quartz-feldspar, porphyritic sills intrude this sequence at all levels. Thin, Jurassic, dolerite dykes also occur throughout the mine. Widespread quartz, sericite and chlorite alteration occurs in the FW. This alteration is manifested as quartz-augen schists beneath the orebody. The Host Rocks are pervasively altered with silica, sericite, chlorite and pyrite. Intense carbonate alteration occurs within the orebody, whereas chlorite and pyrite alteration is commonly concentrated directly beneath it. Cambrian volcanogenic alteration is over-printed by three major Devonian, granite-derived, assemblages. These are massive to quartz veined tourmaline, pyrrhotite-pyrite and magnetite-chalcopyrite. Though the Devonian granite has not been intersected in deep drill holes or in mine workings, there is good evidence that it exists within a kilometre of the deposit. The Rosebery orebody is structurally complex when compared to many other VHMS deposits. Evidence for Cambrian growth faulting has been found at the North End of the mine (B lens) where displacement of ore lenses occurs without corresponding displacement of the overlying Black Slates. A well defined cleavage exists throughout the mine, dipping at 28 to 50¦E. East dipping shear zones are also obvious in all parts of the mine workings and reverse movement is evident on many of these.

Jan 1, 1993

By G Solly, P J. Leevers

Day-to-day operating practices at existing operations need provide high quality data for decisions that will impact directly on the potential value of the available resource, in addition to meeting standards of quality expected of data used in feasibility studies that will be completed to obtain additional capital required to finance operational improvements. Drill hole location, down hole survey and assay data standards of accuracy and precision have received considerable attention in recent years. The authors propose that geological descriptions of both cored and non-cored drilling warrant at least equal attention, considering their fundamental role in establishing the framework used for geological modeling and resource estimation. The iron ore deposits of the Middleback Ranges have been a major source of iron ore for almost a century. High-grade hematite-dominant ore is currently mined by OneSteel from three open pit operations supplying ore to the companyÆs integrated steelworks at Whyalla. A review of OneSteelÆs future iron ore resources, commenced in 2002, highlighted the need for more flexible and comprehensive management of all forms of geological data used in resource evaluation. Driving this program was the information needs of feasibility studies of the Iron Magnet deposit, located beneath the existing Iron Duke and Iron Duchess mines. Prior to the beginning of 2003, resource evaluation drilling data collected by OneSteel was managed using an in-house system based on industry standard relational database software. The system was demonstrably effective in ensuring the fundamental integrity of basic drilling data, but lacked necessary capabilities for the acquisition and management of geological descriptions, geotechnical and geophysical data obtained by down-hole logging. OneSteelÆs existing system for the management and interpretation of geological descriptions was restricted to storage of a single three digit code for each lithological description interval. The original logs for a large number of older drill holes could not be located, having been either poorly archived or culled from the database in the belief that they did not contribute to the understanding of the resources currently being mined. The three digit codes represented a combination of lithological and stratigraphic descriptions, including many subtle variations in iron ore colour and texture believed to be associated with variations in geochemistry, but subsequently demonstrated to be either incorrect or inconsistently applied. This resulted in the establishment of a plethora of codes for a relatively small number of distinct lithologies. Improvements implemented by OneSteel geologists addressed these shortcomings by ensuring the new data management system: facilitated the objective description of lithological characteristics; distinguished between obsevations and interpretations (eg lithology versus stratigraphy); promoted consistency between descriptions provided by different geologists; and helped to ensure data integrity by developing an audit trail for alterations made to data subsequent to its acquisition. The data used to develop interpretations of mineralisation distribution and characteristics are fundamental to the effective utilisation of a mineral resource: any mineÆs most important asset. Resource related risk is widely recognised as the principal source of technical risks affecting resource development projects, whether they are new mines or expansions of existing operations. A key lesson from this work is that most commercial or æin-houseÆ developed geological data management systems are able to handle basic data validation tasks effectively. Geologists, however, need to ensure that the data management system is appropriately structured to help promote the acquisition of objective and consistent data for interpretation.

Jan 1, 2003

By Mance G

Today there are many different techniques of soil remediation used in Australia and throughout the world. This paper considers the thermal desorption remediation technique and, in particular, the application of high temperature filtration to the process. The thermal desorption technique involves the treatment of hydrocarbon (oil, petrol, etc) contaminated soil. The process involves heating the soil in a retort or kiln to drive off the volatile organic contaminants. The exit gas stream from the retort is subsequently passed through an after burner to thermally oxidise the hydrocarbons. This technique produces soil and combustion gas streams which are free of hydrocarbons. Due to the heating and agitation of the soil within the retort, soil particles become entrained in the hot gas stream. To avoid the blockage and fouling of the system's interim ductwork and the afterburner, high temperature filtration technology has been applied to remove these soil particulates without cooling the gas Stream.

Jan 1, 1995

The Comstock Lode, a world-class precious metal vein district near Virginia City in western Nevada, U.S.A. (Fig. 1), produced 8.3 million ounces (0.28 X 106 kg) of gold and 193 million ounces (6.56 X 106 kg) of silver during the period 1859 to present (Bonham and Papke, 1969). More than 95% of production was from the Comstock fault, while the adjacent Silver City, Occidental and Flowery vein systems produced about $10 million (U.S.). Within the Comstock fault high-grade ore bodies, or bonanzas, were distributed over 2.3 miles (3.8 km) along strike and persisted to >3000 feet (>900 m) below the surface (Fig. 2). Bonanzas consisted of as much as 1.4 million tons (1.3 million tonnes) of ore grading up to 1.9 oz./ton (65 gm/ton) Au and 30 oz./ton (1020 gm/ton) Ag (Table 1). Some bonanzas occurred in the main Comstock fault plane while others, including the highest grade bonanzas, formed in hangingwall frac- tures. After 1880 most ore consisted of lower-grade vein material surrounding mined- out bonanzas and large volumes of mineralized vein and wall rock in the Comstock hanging- wall that were mined from open cuts. Deep mining was hindered by large quantities of hot water and bad ground which ultimately defined the limits of underground production. The widths and richness of Comstock bonanzas strongly influenced U.S. mining law, milling and underground mining methods, and securi- ties regulations that are in practice today. Within the district Mesozoic metasedimentary rocks, metavolcanic rocks, and granitic in- trusions are overlain by Miocene volcanic rocks (Thompson and White, 1964). Veins cut all lithologies. Miocene volcanic rocks and their K-Ar ages (Vikre, McKee and Silberman, 1987) include Santiago Canyon rhyolite (22

Jan 1, 1987

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