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By A McEwan, J Masters, C A. Jackson, A Catanzano, V Sharp, M Millen, S Rainey, S J. Spencer, G Roberts

A passive acoustic emission (AE) monitoring system has been developed and trialled on two M10000 IsaMillsTM. The analyser detects AE stress waves generated by grinding media impacts with the mill liner during mill operation. Locally propagating stress waves can be detected on the exterior liner surface using strategically mounted broadband accelerometers.The analyser has been developed into a robust commercial prototype system, and has been designed, installed and commissioned with Xstrata Technology at two mineral processing plants.A six-month field trial showed large-scale variation in AE power signature with process conditions. Analysis of the enveloped AE power output demonstrated a strong correlation with mill process conditions – more specifically grinding media relative loading, feed pulp density, feed volumetric flow rate and feed type.Placement of accelerometers along the length of the mill body provided key information on the grinding media relative deportment. The enveloped AE power detected by the mill body, discharge pipe and bearing housing sensors all captured information strongly correlated with mill operating parameters and process state.The prototype analyser demonstrates suitability as a long-term online tool for stirred mill performance monitoring, and potentially for optimisation and control, in beneficiation plants.CITATION:Jackson, C A, Spencer, S J, Masters, J, Sharp, V, McEwan, A, Rainey, S, Catanzano, A, Roberts, G and Millen, M, 2014. Monitoring of M10000 IsaMill™ process performance by passive acoustic emissions, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 241–254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Z Fu, E Topal, O Erten

"Mine waste rock management involving waste rock movement and placement, is a critical aspect in the planning of open pit mining operations, as the waste rock haulage cost can be the largest portion of the mine operating cost. The concept of sustainable development in the mining industry also encourages environmentally friendly waste dumps that have zero hazards to people and the surrounding environment. Therefore, a detailed waste management schedule must satisfy economic and environmental considerations. However, the available tools in the market cannot provide optimal waste dumping schedules to meet all these constraints. This paper introduces a user-friendly and automatic tool to optimise the waste dumping schedule, which minimises the haulage cost, and covers the encapsulation of reactive materials to minimise acid mine drainage problems. This tool has been developed by using a new mixed integer programming (MIP) mathematical model that considers both single-lift and multilift dumping scenarios. The application of the proposed tool on a data set collected from a gold mine shows that the multilift dumping scenario has provided a more flexible and economical waste dumping schedule than the single-lift scenario, and both scenarios satisfy environmental requirements.Citation:Fu, Z, Topal, E and Erten, O, 2016. A Modified Software Tool for Mine Waste Rock Dump Planning, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 229–242 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By J S. J van Deventer, D C. Shallcross

New developments are taking place in the recovery of gold from leached pulps that are based upon the adsorption of the metal cyanide species onto ion exchange resins. Despite the success of several resin-in-pulp pilot plant operations in the Western World and large-scale plants in the former Soviet Union, the process is yet to gain recognition as a viable alternative to the carbon-in-pulp process. An experimental research program has investigated the use of a variety of different types of resins for the recovery of gold, but to-date no resin studied has the desired properties of high selective loading capacity for gold cyanide and a simple inexpensive elution procedure. In addition very little is known concerning the physical strength of resins and their ability to resist shattering due to osmotic shock during cycles of adsorption and elution. The ability of ion exchange resins to enhance the leaching of refractory and re-adsorbing ores has not been investigated. This paper highlights the necessary factors that need to be addressed before commercialisation of ion exchange technology for gold extraction is feasible.

Jan 1, 1998

By G Hancock, J Lowry, T Coulthard, W Erskine, M Saynor

An important part of planning for the rehabilitation of uranium mine sites is the ability to assess the geomorphic stability of the final landform, over time frames ranging from decades to millenia. Depending on the environmental conditions, erosion features such as gullies may incise into containment structures, potentially leading to the exposure and transport of encapsulated radioactive material. Further, erosion may lead to increased sediment loads and the transport of other mine-related contaminants off-site and into downstream waterways. While erosion may be monitored and assessed over the short term (years to decades), the longer-term behaviour (centuries to millennia) of such landscapes is not within any meaningful human management time frame. Landscape evolution models (LEMs) can provide information on soil erosion rates at decadal or centennial scales over large spatial scales, and evaluate the sensitivity of these processes to environmental changes. However, an important issue associated with the use of models is the ability to assess the reliability and accuracy of the model. In this paper, the CAESAR-Lisflood LEM is tested for its ability to predict soil erosion from a series of 30 m × 30 m experimental plots specifically constructed for this purpose on a trial rehabilitated landform at the Ranger Uranium Mine in the Northern Territory, Australia. Model predictions of bedload and suspended sediment loads from the erosion plots were compared with field measured observations collected over four wet seasons from the trial landform. Once calibrated for the specific site hydrological conditions, the predicted sediment yield – specifically, bedload – demonstrated an excellent correspondence with the field data. However, longer-term simulations of ten years identified an exhaustion effect in sediment yield from the landform. These latter results indicate that a weathering function needs to be incorporated into CAESAR-Lisflood to ensure confidence that the CAESAR-Lisflood LEM will be able to correctly predict the long-term evolution of a rehabilitated landform once it has been?constructed.CITATION:Lowry, J,?Saynor, M,?Erskine, W, Coulthard, T and Hancock, G, 2014. A multi-year assessment of landform evolution model predictions for a trial rehabilitated landform, in Proceedings Life-of-Mine 2014 , pp 67–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

The purpose of this paper is to look at the costs of tailings disposal, and in particular the comparative costs of different disposal methods in different situations. Costs are often the hidden design parameter. We know that they are important but sometimes feel that it is not very respectable to talk about them in public. It is better from a public relations point of view for it to appear that the decision-making process is driven by environmental factors or best practice rather than looking for the cheapest option. But this presumes that the two are mutually exclusive and this need not be so. These issues are discussed later in the paper. It is also commonplace for the scale of the mining operation to change with time, typically involving increased throughput rates and total tonnage. New ideas in tailings disposal make their appearance. The regulatory attitude can change. Having made a decision about the disposal method at the time of original feasibility study and design it is easy to suppose that the mine is æstuck with itÆ. But that also need not necessarily be so. Careful costing of options may reveal that a switch in method could be cheaper in the long run. The designer will often tend to think in terms of initial earthworks and site development costs. Aspects of power consumption, labour, and periodic campaigns to move tailings pipelines and carry out embankment raises are either overlooked or not given the same emphasis. This can distort the evaluation process. It is productive to think in terms of dollars or cents per tonne as a basis of comparison, not just the total sums. Tailings disposal can cost from as little as 10 - 20 ó/t to over $1.00/t which is a big range. There may be good and unavoidable reasons for the high figure but there would need to be to justify being so far over the industry average. At the same time, mining and processing costs, at least for gold, are around $15 - 20/t. Viewed from this perspective tailings disposal will always be a relatively small component of the annual budget.

Jan 1, 2000

By D K. Weatherley, A N. Mainza, I Govender, L M. Tavares, M S. Powell

It is understood that rocks do not instantaneously transport along a grinding mill and are consequently not perfectly mixed, but this is conveniently overlooked in mill modelling. A lack of understanding of the transport phenomenon and the difficulty of modelling realistic transport in a complex tumbling system, contribute to this. Visual observation of segregation in AG and SAG mills and measured lag time of mill response to changes in feed provide evidence of the influence of axial transport within mills. Incorporating this lag in dynamic models should underpin dynamic simulation of milling circuits for design and for model-based control. Limitations and errors in predicting the influence of increased power via mill length versus diameter, inability to predict pebble production, and a lack of the differential in residence time across rock sizes and competences, all contribute to inadequate design prediction that can be especially acute for large Autogenous mills. Examples of dramatically under – and overloaded pebble regrind circuits and the inability to predict pebble load in AG milling discouraging the application of this energy-efficient option, point to the need for predictive modelling of breakage by competence linked to transport through and out of mills. Incorporating progress in granular flow and mixing, coupled to computational advances enable models to be based on complex breakage and transport models at high spatial resolution. This allows mechanistic models to simulate thousands of times faster than real time, opening the door to more accurate mill design, including dynamics in process simulation and to live simulation for process control – all with advanced mechanistic models. The value of grasping this opportunity is not easily refuted.

Aug 24, 2022

By P B. Hills

This paper discusses the computerisation of the drill hole database, some historical records and the creation of a three-dimensional model of the gold bearing structures for resource estimation and mine design at the Beaconsfield Gold Mine in northern Tasmania. The phase of the work reported here commenced in November 1997 and was completed in March 1998. The historical mining on the Tasmania Reef had reached a depth of 450 m below surface when work ceased in 1914. Production up to this time was 854 000 ounces gold. Recent activity has concentrated on testing depth extensions of the previously mined ore structure, to a depth of 1000 m below surface, and the establishment of an underground mining operation to exploit this resource. The lode structure at Beaconsfield is a typical mesothermal vein style deposit. Gold is contained within narrow quartz, carbonate and minor sulphide reefs or veins. Reef width is variable from a few centimetres to several metres with æsplitsÆ or bifurcations being common. The reef averages 2.7 m true width in the economic zones. The key feature of this style of mineralisation is that reef continuity can be confirmed by drilling to a high level of confidence, but the gold grades are somewhat more erratic in nature. The resource estimates were based entirely on drill data. The drill intercepts on the reef were coded for each split directly into a database and these allocations validated graphically. The distribution of grades and widths show an increasing gold grade with reef width for both the drill hole and historical data. The same histogram patterns, mixed populations and overall arithmetic average grade for the historical mine (at 21.52 g/t > 3 g/t Au) and new drill data (at 21.55 g/t > 3 g/t Au) would indicate that there has been no major change in the overall style or grade of the ore from the historically mined areas to the new resource. The reef, host geology, area of historical workings and resource zones at the Beaconsfield Mine were defined as a series of closed wireframes. The Tasmania Reef was modelled as five mutually exclusive wireframes, one each for the Main Reef, Footwall split, Second footwall split, Third footwall split and Hangingwall split. The data for this exercise was extracted directly from the drill hole database, stored in Microsoft Access format. The formation of the solids was largely automated with manual validation and refinements allowing for multiple runs using different interpolation methods and combinations of drill holes. A rotated 3D-block model in the plane of the Tasmania Reef was created to contain the grade model and allow for tonnage, grade and reef width estimates. An inverse distance squared (ID2) interpolation method was used with ranges of 25 m along strike and 125 m down plunge with blank areas infilled with 50 m by 250 m. Each reef split was filled separately using only drill intercepts from that split. The method was independently validated used MIK methods. Longitudinal sections have been prepared showing gold grade, reef width and width +grade. Estimates were also made for arsenic, sulphur and other minor elements. The long sections show three distinct mining zones. A method is presented for the conversion of the resources to reserves by the addition of mining parameters for minimum mining width, minimum pillar, cut-off grade and internal and external dilution. The selection is done on columns within the block model, and allows for all splits to be considered at once. Multiple runs can be made for varying combinations of parameters to test different mining methods and their impact on reserves, mine life and NPV.

Jan 1, 1999

By R R. Lovel

In this paper, life cycle assessment methodology has been used to assess the variations in water use associated with different metal production and processing routes and provide insights into the value derived from water usage in the minerals sector. Using water consumption data derived from the literature it has been shown that the æcradle-to-gateÆ water consumption (or embodied water) for production of the various metals considered in the study ranged from 2.9 m3/t for steel up to 252 087 m3/t for gold. The results largely reflect the grade of the initial ore used to produce each metal, and can be approximated by the following equation:W = 167.7 G - 0.9039 where: W = embodied water (m3/t refined metal) G = grade of ore used to produce metal (per cent metal) The study showed that indirect water consumption in the metal production life cycle, in particular that due to electricity generation, can make a significant contribution to the embodied water value, eg aluminium production. When expressed in terms of m3/t ore, the results for all metals considered indicated that the embodied water is roughly, on average, three times the water consumption of the mining and concentration stage. It was also shown that the economic value per m3 of water consumed for the minerals industry exceeds that for the agricultural and industrial sectors, supporting the view that allocating water resources to the minerals industry has a strong underlying economic basis. Water reforms currently taking place in Australia aim to address issues such as competition for water access, reduced security of supply and increase in cost. Consequently the minerals industry, along with others, can be expected to come under increasing pressure to reduce fresh or raw water use and to integrate water use across sectors. While water recycling is an obvious candidate to help reduce water consumption in the minerals industry, issues such as water quality, among others, will influence the extent to which this can be achieved. In addition, wastewater volumes can be minimised using techniques such as pinch analysis to establish and use the minimum water requirement for the process. The use of dry or near-dry processing technologies, for which the demand for water is small or zero, may be a more radical solution to the water consumption problem; however, it is possible that the introduction of dry processing would bring with it a new set of problems, including dust.

Jan 1, 2006

Sample preparation for gold samples, where the distribution and size of gold particles is often irregular, usually demands that a relatively large sample weight is taken to produce a representative sample for analysis. Traditional sample preparation of gold samples incorporated multiple stages of coarse particle size reduction followed by subdivision of the sample prior to final fine pulverising. This technique developed because of the limited equipment options available to laboratories. As a result significant errors are introduced and the final sample size being pulverised is a small fraction of the original sample weight. Three significant developments have occurred in the last 25 years to significantly improve sample preparation of gold samples: 1.  large capacity fine pulverising,2.  fine jaw crushing, and3.  whole sample coarse pulverising. In the mid-1980s an Australian manufacturer developed large capacity pulverising bowls which had the ability to reduce samples with a mass of 1.5 - 3.5 kg to a nominal 0.075 mm product in approximately three to five minutes. Laboratories were able to produce a large homogeneous pulverised sample which significantly reduced the error in sampling. However, exploration and mine samples are usually 7 to 10 kg and the sample requires a subdivision stage following crushing to produce the 3.5 kg for the pulverising step, thus introducing potential for significant error. The development of fine jaw crushing allowed particle size reduction to -2 mm which reduced the subdivision error of the bulk sample prior to fine pulverising. Subdivision of the crushed sample at -2 mm still results in potential sampling errors, where the gold particles are not sufficiently liberated to be representatively sampled. Clearly the best option would be to reduce the particle size small enough to ensure a representative sample prior to final pulverising. Continuous mills offer a partial solution but are relatively slow and subject the sample to differential pulverising prior to subdivision. Clearly this does not provide the best solution for routine laboratory applications where high volumes of samples are to be processed. The recent development of a large capacity coarse pulverising system allows samples of up to 10 kg to be reduced to -0.25 mm prior to subdivision, and fine pulverised to -0.075 mm. Laboratories now have the necessary equipment to perform reliable large capacity sample preparation of gold samples. The exact choice of a sample preparation scheme may still depend on particular ore types but the need for multiple crushing and subdivision stages is redundant.

Jan 1, 2008

By M A. Jardine, J A. Miller, M Becker, M Harris

"Although the role of texture has been increasingly recognised as a geometallurgical indicator of ore characteristics and their variability, the ability to appropriately quantify and correlate it with metallurgical performance remains an ongoing challenge. In this study, we propose the 3D characterisation and quantification of ore textures from drill core using X-ray computed tomography (XCT) with an appropriate image analysis methodology (grey level co-occurrence matrices, GLCM). This methodology has been specially customised for application of 3D XCT grey-scale volumes. This approach has potential as an online mine site analysis tool providing detailed 3D information on both quantitative texture and simple mineralogy.The approach is illustrated in this paper using drill core samples that were manually extracted from various rock types and textures representing the Nkomati Main Mineralized Zone (MMZ) sulfide nickel ore deposit. A preliminary classification of the samples was performed based on their particle size distribution after laboratory scale rod milling. Accompanying QEMSCAN analyses were also used to guide the interpretation of the grey-scale mineralogy and texture in the 3D XCT volumes. The resultant GLCM produced from quantitative 3D image analysis of the XCT volumes indicated sensitivity to ore variability and was able to capture a simple mineralogy and grain size distribution. The approach holds many possibilities for geometallurgy, of which the potential for automation is promising.CITATION:Becker, M, Jardine, M A, Miller, J A and Harris, M, 2016. X-ray Computed Tomography – a Geometallurgical Tool for 3D Textural Analysis of Drill Core?, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 231–240 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By A Grace, C Sennersten, A Davie, R Lyu, C A. Lindley, O Goldstein, T Thomas, L De Macedo Camargo

Block modelling is a well-established method for modelling ore reserves as a basis for strategic mine planning and mine development. Off-Earth mining, particularly of asteroids, can benefit from block models; however, the significantly different characteristics of asteroids and their methods of mining require reconsideration of the geometry and annotations of block models. Terrestrial block models consist of rectangular prisms within Euclidean coordinate systems. Their labels and parameters typically include location within a mine-specific coordinate system, x, y and z dimensions, specific gravity, hardness, grades of metals of interest and so on.These data provide an input to mine design and strategic mine planning. Mining asteroids may require different coordinate systems (eg spherical, elliptical or cylindrical, rather that Euclidean) and attributes that vary from Earth-based block models. These include: variable gravitational vectors throughout the block modelrotational moment or accelerationrotation rates. Materials within asteroids may show different isotopic compositions. Asteroid mining has the unique characteristic of a mine being identical with an asteroid. The position of the asteroid/mine in space and its full orbital elements provide critical inputs to mission design and costing. Hence, the block model concept needs to be extended with this metadata. The orbital position and behaviour of the Earth must be included for active mine planning, and increasing automation of mine planning and operations needs to consider terrestrial weather and telecommunications infrastructure. Financial planning requires analysis of the net present value of extraterrestrial mining compared with terrestrial alternatives, so a fully automated mining enterprise should integrate terrestrial and extraterrestrial block models at different scales and resolutions. Blocks can be indexed via octrees, allowing for hierarchical scales that support analytics for deriving new knowledge and correlating features across different scales.CITATION:Lindley, C A, Sennersten, C, Davie, A, Goldstein, O, Lyu, R, Grace, A, Evans, B, Pentecost, D, Thomas, T, De Macedo Camargo, L, Craig, J, Salomao, G N, Hellicar, A, Biggins, D, Timms, G, Coombe, M, Shahriar, M S, Smith, G and Rahman, A, 2015. A multilayer 3D index tool for recursive block models supporting terrestrial and extraterrestrial mine planning, in Proceedings Third International Future Mining Conference, pp 289–296 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By D Hunter

A production information management system (PIMS) was recently implemented at Queensland NickelÆs Yabulu Refinery. Although a strong business case was developed to justify the significant investment in PIMS some potential beneficiaries remained sceptical of the anticipated benefits. The decision to install PIMS was justified as the on-line availability of continuous production data enabled the optimisation of some crucial operations resulting in significant cost savings, improved throughput and final product quality. Furthermore the rapid access to extended historical data has allowed the cause of repeated failure of equipment to be determined. The investment is expected to pay for itself within two years and has already contributed towards significant savings. This paper focuses on some of the diverse production improvements gained and compares the anticipated benefits in the business case to those achieved. A brief outline of the phased implementation of the OSIsoft PI data historian and complementary client software at Yabulu is included, along with details of the lessons learned.

Jan 1, 2003

By D J. Bradshaw, E M. Wightman, B Newcombe

Flash flotation plays an integral role in many of the gold and sulfide mineral concentrators around the world, and yet despite this widespread use, very little information on this unit process is available in the published literature. For operations to maximise the performance of their flash flotation circuits, understanding how these cells operate, the nature of the particles they target and how to predict whether a flash flotation cell should be used on a specific ore type is of vital importance. This paper provides a summary of the key findings of a large flash flotation research project based in the operating environment of a refractory gold concentrator. The influence of key flotation performance criteria including gas dispersion, residence time and particle segregation within the cell will be discussed and recommendations for process improvements will be made throughout. The nature of the particles within the flash cell will be examined, as will the impact on the type of particles that are passed to downstream processes when the flash flotation cell is taken off-line. The development of a laboratory method to determine whether an ore is suitable to undergo the flash flotation process is also presented for its potential to aid in flow sheet development and optimisation for new ores.CITATION:Newcombe, B, Bradshaw, D J and Wightman, E M, 2012. Into the belly of the flash à Insights into the mechanisms at work within a flash flotation cell, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 163-170 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Australia is presently the world's principal producer of rutile and zircon, and also provides a major share of the world's ilmenite. Since 1980, Australia's share of the world's output of these minerals has fallen. Exhaustion of known resources, together with the changing composition of new deposits, is expected to result in Australia's share of the rutile and zircon output continuing to decline. Its role as a major supplier of upgraded ilmenite, that is synthetic rutile, is expected to increase. In 1994, the Bureau of Resource Sciences assessed Australia's demonstrated resources of mineral sands as follows: rutile 14.4 Mt, ilmenite 132.5 Mt, and zircon 21.0 Mt. These resources are located along the coast of Queensland and New South Wales, in the Murray Basin of New South Wales and Victoria, in the southwest corner of Western Australia, and in the Eneabba region, north of Perth. However, some 45 per cent of rutile and zircon resources along the coast of Queensland and New South Wales are not available for mining because of environmental concerns. World demonstrated resources are estimated at 40 Mt (contained TiO2) for rutile, 50 Mt for zircon and approximately 312 Mt (contained T1O2) for ilmenite. Outside of Australia, the most important resources of rutile, ilmenite and zircon are in South Africa (rutile, zircon , and ilmenite in the form of titania slag), Sierra Leone (rutile), India (ilmenite, zircon and rutile), and Canada (hard rock ilmenite). Significant resources of ilmenite occur in Madagascar and Mozambique.

Jan 1, 1996

By A J. Minns

This paper addresses the question: how can the minerals industry remain viable; viable in the sense that we are able to access land for exploration and discovery, we are able to develop and operate mines (and processing plants) safely and profitably and we are able to close operations in a responsible manner, so that modified landscapes are restored to acceptable community standards?Many of the answers to this question can be addressed through the theme of this conference û that of eco-efficiency. The eco-efficiency concept is very useful, since it does help to translate principles of sustainability into business value at the operational level. To provide some context to how this can be achieved, the paper discusses what is happening at the international level, outlines some key industry initiatives within Australia and then discusses what work is being done within companies.

Jan 1, 2004

By C J. Moran

All mines face water management challenges. Adopting leading practice water management strategies can help reduce both operational and strategic risks. While many of the water issues faced by underground mines are the same as other operations, underground mining presents some unique water management challenges. In this paper we review trends in underground mining, water use and associated water issues. We then compile a structured set of strategic and operational risks that are pertinent to underground operations. The causes, threats, opportunities and measures for controlling or mitigating the risks are summarised. The risk compilation could provide an addendum for underground operations to the Australian governments leading practice water management handbook.

Mar 21, 2011

With commodities suffering dramatically low real prices, mining business margins are under intense scrutiny. Unfortunately, management systems developed early this century for manufacturing are driving counterproductive behaviours that choke productivity. The paper and presentation will explain this and present a proven methodology for increasing productivity. This will be supported by operational examples from Australian and American mining management to demonstrate the importance of modern business performance measurement and analysis systems. It will explain the importance of management systems in driving organisational change to sustain superior productivity and margins. The paper will explain why many executives and managers confuse production (a measure of volume) with productivity (which measures efficiency and effectiveness). It will explain how this and other counterproductive managerial and operator behaviours and attitudes are driven by traditional business management systems exacerbated by managerial and consulting fads. The paper will begin with the simple principle that to improve results one needs to first improve the process producing the result û and will show how this is often violated. Improving productivity then boils down to:accurately identifying opportunities using sound, modern measurement, analysis and reporting systems; methodically improving operating and commercial processes, and changing peopleÆs behaviours and attitudes to sustain changes in practices. The paper will include fundamentals of applying sound measurement and analysis to:processes directly, eg cycle time charts and their impact in cyclical (non-continuous) operations commonly used in rock breakage; drivers of productivity; and process results themselves since correct analysis identifies opportunities accurately. The paper will cover the importance of practical leadership and the need to follow a simple, solid plan for changing systems that drive behaviour. Overall, it will highlight use of modern performance Measurement, Analysis and Reporting systems to drive behaviours and improve margins - without capital investment û and make executive and managerial work easier and more effective.

Jan 1, 1999

By B M. Patterson, A J. McKinley, M E. Grassi

Large-scale column experiments were undertaken to determine the effect of a step decrease in groundwater pH on metal remediation by bioprecipitation. Metal contaminated groundwater at pH 5.5 was amended with ~1 g/L of ethanol in one column using a polymer mat ethanol delivery system to promote bioprecipitation, while another column was left unamended and used as a control. Sulfate reduction and zinc removal were observed after eight weeks. Zinc removal was observed in the zone of sulfate reduction, indicating precipitation as ZnS, while, copper was removed in the denitrification zone. Once steady state bioprecipitation of zinc had been established, the pH of the metal contaminated influent groundwater was decreased stepwise from 5.5 to 4.25. As a result of the change in pH, a significant increase in copper concentration was observed in both columns. In the ethanol column, the zones of denitrification and copper removal migrated up the column, while both sulfate reduction and zinc removal ceased. Bioprecipitation of metal contaminated groundwater via sulfate reduction was shown to be an effective remediation strategy for zinc removal. However, this in situ biological remediation process was sensitive to changes in groundwater pH.

Jan 1, 2004

By P Breuer, D J. Robinson, A McFarlane, L L. Kuhar

Increasing global demand for commodity metals and capital and the greater operating costs of mining and metal production present significant challenges for the metals mining industry. Current conventional technologies may not be feasible for processing deposits of declining grade, challenging mineralogy or those that occur at increasingly greater depths. To overcome these issues, the development of a step-change technology such as in situ recovery (ISR), which reduces mining and avoids milling costs, may be vital in ensuring future economic metal production. ISR has been used extensively to treat porous soft rock deposits such as the water-soluble salts, sylvite and halite. Although ISR has typically been used for mining conventionally uneconomic uranium ores, it has also been used less frequently for the treatment of other restricted permeability hard rock deposits, such as those containing copper and gold. The reason for the limited uptake of the technology for hard rock mineralisations is primarily due to low natural rock porosity and permeability and hence poor response to available lixiviant. However, additional challenges include solution containment, management of groundwater and regulatory, ecological and societal requirements and expectations. CSIRO has focused on understanding the challenges of hard rock ISR and identifying global capabilities that can contribute to developing the essential enabling technical areas required to realise ISR. Specific focus areas include geochemistry and advanced resource characterisation; drilling and controlled rock-breaking technologies; solution chemistry and environmentally benign lixiviant systems; lixiviant delivery systems and ‘subsurface mixing’; subsurface hydrology and reactive transport mechanisms and models; downstream processing options; legal, social and environmental aspects; and techno-economic modelling. This paper will discuss ISR challenges including industry feedback focused on addressing this issue, gaps preventing ISR from being applied in practice, capabilities to overcome these gaps and the development of a collaborative approach to making hard rock ISR a reality.CITATION:Kuhar, L L, Breuer, P, Robinson, D J and McFarlane, A, 2015. Making hard rock in situ recovery a reality, in Proceedings Third International Future Mining Conference, pp 189–196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By R Higashi, D Maruoka, T Murakami, Y Iwami

The ironmaking industry consumes a large amount of fossil fuel derived carbon as heat source, reducing agent of iron ores and carburising agent of reduced iron. Although the demand for drastic decrease of carbon dioxide emission, carbon is an essential element for smelting process of molten iron. The carbon recycling ironmaking process by circulating CO has been already proposed to achieve carbon neutrality. However, the production of molten hot metal is not considered in this process because sufficient amount of carbon does not dissolve in reduced iron by CO. Therefore, our group has suggested a new carbon recycling ironmaking process which can produce hot metal. In this process, free carbon and iron carbides produced by carbon deposition reaction using metallic iron as a catalyst are used. It is known that only Fe3C is obtained as iron carbide by using CO gas, however, Fe5C2 is also produced by adding H2 gas. The composite agglomerated with these carbonaceous materials and fine iron ore (Deposited Carbon-Iron oxide Composite: DCIC) is reduced and melted in a furnace. It is reported that Fe3C in DCIC accelerates the reduction reaction and melting of the composite. In this study, the effects of iron carbides and free carbon on the melting behaviour of DCIC are investigated. Fe3C, Fe5C2 and free carbon were produced by vapour deposition using porous iron whiskers and CO-CO2-H2 gas. These were agglomerated with hematite reagent at a certain ratio to prepare DCIC samples with and without Fe5C2. The samples were heated up to 1300°C in inert atmosphere. The DCIC containing Fe5C2 completely melted and iron nuggets were obtained after the experiment. This behaviour was not observed in the composite without Fe5C2. This indicates that using Fe5C2 is more preferable than Fe3C for molten iron production using DCIC.

Jun 19, 2024