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By B, R E. Browner, H R. Watling

A number of hydrometallurgical treatment methods are being developed to extract copper from chalcopyrite flotation concentrate including microbial leaching and ferric sulfate leaching. However, chalcopyrite is difficult to process efficiently by hydrometallurgical methods as it exhibits slow reaction kinetics. Comparative leaching tests do not always satisfactorily explain or predict observed copper recovery, acid consumption, or differential leaching of minerals. This is especially true when reactive gangue constituents are present. The aim of this study was to determine how the leaching regime (microbial versus ferric sulfate) affects both the extraction of copper and residue mineralogy. Chalcopyrite flotation concentrate was leached at 30¦C and 65¦C using a pure culture of Acidithiobacillus ferrooxidans and a mixed consortium of thermophiles, respectively. In addition, the concentrate was leached at the same temperatures using 0.1 M ferric sulfate. Microbial leaching of chalcopyrite extracted more copper than ferric sulfate oxidation of chalcopyrite at 30¦C, demonstrating that the microbes promoted the solubilisation of copper at this temperature. This result was confirmed by leach solution analyses and residue analysis using quantitative X-ray diffraction (QXRD). More chalcopyrite was oxidized with ferric sulfate at 65¦C than at 30¦C (as expected). QXRD confirmed that pyrite reacted during ferric sulfate leaching at 65¦C but was relatively unreactive during lower temperature leaching. The high ferric ion concentration in the ferric sulfate leach at 65¦C led to significant precipitation of jarosite. This phase was only detected in small amounts at 30¦C in both the microbial and ferric leached residues. Sulfur also precipitated in the ferric leaching at 65¦C whereas no sulfur was detected in the microbial leached residue. Quartz was a relatively unreactive mineral phase regardless of the leaching medium and temperature. QXRD analysis indicated the residue mineralogy differed with different leaching regime.

Jan 1, 2004

By P Joyce, A S. Ray, P S. Thomas, J Haggman

Climate change and global warming present a significant challenge as unsustainable levels of greenhouse gas emissions arising from human activities continue to be emitted. The cement industry is responsible for between five and ten per cent of annual world carbon dioxide emissions; most arising from the manufacture of Portland cement (PC). An effective way of reducing emissions is by incorporating supplementary cementitious materials (SCMs) as partial PC replacements. SCMs are silicate or aluminosilicate based pozzolanic materials which, in finely divided form, combine with water and calcium hydroxide (lime), liberated by cement hydration, to form compounds exhibiting cementitious properties. Pitchstone is such an aluminosilicate and has the potential to act as an effective pozzolan for partial replacement of PC. In North Queensland, Australia, a vast deposit of pitchstone is mined and processed for expandable perlite aggregate. During the classification stage of the excavated natural material, waste pitchstone fines (PF) less than 0.5 mm in size are generated. This study evaluates the waste PF as a viable, eco-friendly pozzolan for the partial replacement of PC. The reactivity of the PF is compared to fly ash (FA), using the pozzolanic compressive strength activity index (SAI) after seven, 28, and 91 days ageing at 20 per cent and 40 per cent PC substitutions. PF was found to be comparable to FA as a pozzolan at 20 per cent PC substitution at all ages tested. However, for the 40 per cent substitution blends significant strength was only achieved at 91 days ageing for the FA blend. The pozzolanic reactivity was also investigated using thermogravimetric analysis to determine the degree of free lime present after 91 days. In all cases where an SCM was added, the free lime was observed to be consumed with increasing age.

Jan 1, 2008

By H Aral, L Malishev

The carbothermic chlorination of titaniferous materials such as rutile, synthetic rutile (SR), upgraded slag and ilmenite in a fluidised bed is an established commercial process. In this work, ilmenite sourced from the Murray Basin area of South Eastern Australia was chlorinated and an assessment of the chlorination characteristics of the ilmenite, in terms of pre-treatment, type of reductant and reaction time was made. Selective chlorination of Murray Basin ilmenite to remove Fe and Mn was achieved in this work. A synthetic rutile sample containing around 93 per cent TiO2, one per cent Fe2O3 and 0.5 per cent MgO was produced at a chlorination temperature of 1000¦C with around 25 per cent loss of Ti as TiCl4. Raising the reductant to ilmenite ratio in the chlorination reactions increased the amount of Ti chlorinated. However, complete chlorination of Murray Basin ilmenite to produce FeCl3 and TiCl4, was not achieved under the conditions used in this work. Pre-oxidation of Murray Basin ilmenite before chlorination had little affect on its reactivity, compared with æas receivedÆ ilmenite. In contrast weathered West Coast ilmenite chlorinated appreciably better than West Coast primary ilmenite, in terms of bed residues remaining and amounts of elements removed. The presence of large amounts of Mg and chrome spinel grains in the Murray Basin ilmenite used in this study are likely to make it difficult to chlorinate directly in a commercial chlorinator. However, this is not to say these ilmenites will be unsuitable for chlorination applications. Further work is needed in the separation of Mg and chrome spinel grains from Murray Basin ilmenites and the products resulting from these tests could then be assessed in terms of chlorination performance, so that further processing options can be explored.

Jan 1, 2000

THE slag from the blast furnaces having been granulated, a representative sample is taken to the sample mill. It is then dried, crushed through a 100-mesh screen, intimately mixed, and packeted for assay purposes.METHOD OF ANALYSISINSOLUBLEWeigh 1 grm. of the finely-pulverized slag into a 3t-in. casserole, moisten with a little water to prevent sticking, cover with a clock glass, and add 20 cc. of hot acid (1 HNOs, 3 HCI, 4 H2 0). Evaporate slowly to dryness on a hot plate and bake (without overheating) until all the gelatinous silica is dehydrated. Cool, add 20 cc. HCI (1-1), and boil gently for several minutes; filter into a 300-cc. beaker, cleaning out the casserole thoroughly with a rubber-tipped glass rod. Wash residue with hot distilled water and transfer it to a No. 1 porcelain crucible. Dry, ignite, cool in a desiccator and weigh as total insoluble matter. Dilute filtrate to 200 cc. and neutralize some of the excess HCI with NHa.OH. Warm, and pass H2S for 15 min. Filter and wash withhot water. Boil off H2 S, oxidize with 5 cc. HNOll , reduce bulk of the solution by evaporation. to about 100 cc., and transfer to a 250 cc. flask.SILICAFuse insoluble residue over a blast lamp in a platinum crucible with three or four times its weight of anhydrous carbonate of soda, for 10 to 15 minutes, or until decomposition is complete. Cool, and extract fusion in an 8-in. evaporating dish with HCI (1-1); rinse crucible and cover with distilled water, and evaporate to dryness over a water bath. Take up dry mass with 10 cc. strong HCI, and then.

Jan 1, 1922

Dilution in underground coal operations can be underestimated by up to five times during feasibility studies, with disastrous economic consequences. Every one per cent of stone waste introduced can reduce an in situ specific energy of 25 MJ/kg by some 0.25 MJ/kg and increases the abrasiveness of the run-of-mine coal. Where a wash plant is not in place, penalties imposed for not meeting contractual specifications alone can amount to some $A 1 million per year. This paper presents a method for monitoring, reporting and ultimately controlling dilution in an underground coal mining operation and presents the dilution trends from a continuous miner/longwall mine over an eight year period. The overall dilution level for the mine can be back-calculated by comparing the run-of-mine coal quality to the predicted in situ, undiluted quality. However, this will not identify the actual contaminant types, areas of the mine responsible for the dilution and the reasons for the dilution. This additional information is essential for controlling dilution to acceptable levels. Quality and horizon control using existing sampling information is generally only adequate for longer-term control purposes, and is not suitable for monitoring mining-induced dilution. The cost of close-spaced surface drilling to collect the information necessary for short-term control is prohibitive, particularly for deeper mines. However, much of this data can be collected through underground channel sampling and horizon control measurements taken during continuous miner development and longwall extraction. The mine runs the risk of not meeting contractual quality specifications and of increased equipment wear if this additional information is not available and the sources of dilution cannot be controlled. The information can also be used to plan longwall extraction heights on a short-term scale with resulting improvements in productivity.

Jan 1, 2003

QEMSCAN« technology is a widely accepted automated e-beam technique providing quantitative and statistically robust mineralogical data to the mining industry. It uses X-ray mapping combined with backscattered electron (BSE) brightness to identify minerals in almost any type of geological material (Gottlieb et al, 2000). Besides the modal mineralogy also the liberation, associations, average grain size and other textural information can be obtained. The aim of this study is to test reproducibility of this technique by setting up and running standard tests on different QEMSCAN« systems. Multiple sample blocks were prepared by our standard operating procedure as epoxy-mounted, carbon-coated, polished blocks. The replicates were measured under the same conditions and measurement parameter settings on different QEMSCAN« instruments. The relative standard deviation (RSD) for the set of measurements was calculated. Generally the reproducibility of the systems themselves was found to be excellent, ranging between 0.4 and 1.5 per cent RSD. The more significant change in the reproducibility was found to be caused potentially by the sample preparation and variation in the mineralogy of the replicates. The measurement parameter settings together with these variations can account for almost 15 per cent RSD for minerals of low abundance. For analysed samples good results for the main phases present in quantities higher than 2 - 5 wt per cent of the total mass of the sample were confirmed with RSD generally below six per cent. Following the experiments, the parameters having the biggest influence on the performance of the QEMSCAN« and its precision are discussed in detail. The importance of sample preparation procedures and measurement parameter settings is emphasised. It is shown that experience and excellence is necessary for getting the most from the automatic mineralogical methods like QEMSCAN«.

Jan 1, 2008

By B G. Lottermoser

The placement of sulfidic waste below the groundwater table ensures limited interaction with the hydrosphere and suppression of sulfide oxidation. However, if sulfidic waste is placed above the groundwater table and remains uncovered, the backfill becomes part of the unsaturated zone and is exposed to atmospheric oxygen and leaching. This study aims to establish the leaching behaviour of sulfidic waste placed above the groundwater table and the impact of such leachate on the local aquifer at the Thalanga base metal mine. Mining of the Thalanga copper-lead-zinc deposit resulted in a large final mining void (600 m + 150 m + 70 m) and extensive underground workings. The underground workings were partly filled with tailings and the open pit was partly backfilled with acid producing sulfidic waste rock. In addition, the pit serves as a sink for acidic run-off from adjacent waste rock piles and mine workings. To date, the backfill of sulfidic waste rock placed into the pit has not been capped with benign materials and for most of the dry season, the surface of the backfill is covered by melanterite-type efflorescences. Results of kinetic column leach experiments conducted on the sulfidic waste indicate that Cd, Cu, Zn and SO4 rich waters migrate from the backfilled sulfidic waste into the local unconfined aquifer. However, the seepage of alkaline (pH 7.3 - 8.0), high conductivity (>10 000 ¦S/cm) tailings waters into the remaining pit void clearly shows that the acid leachate originating from the sulfidic waste rock does not impact beyond the waste repository and its immediate environment. Geochemical modelling implies that minimal or no mixing occurs between the acid waste rock leachate and the alkaline tailings waters.

Jan 1, 2003

By G I. Lumley

‘Every mine is a pilot’ is an attitude which encourages the mining paradox of optimistic mine plans and equipment under performance; propped up by an environment lacking accountability. The premise that ‘every mine is a pilot’, appears to underlie the development and operating approach to most mines. It is the hypothesis of this paper that many mining companies, development teams and their managers largely ignore what is done elsewhere. Anecdotally, most planners don’t know whether the selected rates are high or low (rates based on theoretical models tend to be high – certainly higher than what most companies can achieve). Mines then consistently operate the equipment at rates well below targets; often more than 20 per cent below. Further to this paradox, mine performance data demonstrates the average mine is currently operating their equipment at levels of output not much more than half the output of those in the top ten per cent. On the whole mines don’t know the potential of their equipment and therefore don’t put appropriate plans in place to do better. After all, when ‘every mine is a pilot’ there is little reason to look to one’s peers for an indication of potential. This paper will outline why every mine is not a pilot and how mines do value some knowledge, but not as much as they should. This paper proposes a two-pronged approach to address this issue in the area of equipment performance. This approach is to:1. engage in better forecasting of equipment rates and better subsequent performance through benchmarking against industry standards2. provide conditions for more accountability.These parameters are linked and proper implementation of them will address the losses which many shareholders and financiers have incurred when investing in companies with unrealistic mining plans.CITATION:Lumley, G I, 2016. Is every mine a pilot? In Proceedings International Mine Management Conference, pp 75-88 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

This brief introduction tries to introduce delegates to this conference to the almost unbelievable attributes possessed by many microbes which might be relevant to geomicrobiology, and how most of these remain unexploited by us. It introduces some of the terminology which will be used and tries to suggest that there are rewarding times for those who set out to discover the natural biodiversity of bacteria in nature. Although we have exploited microbes, usually unwittingly, and suffered at their hands for millennia, it is only recently that we have begun to become aware of how they dominate our planet (most of the earthÆs biomass is bacterial) and are responsible consequently for most of what happens here. A few can cause us harm and occasionally kill us, but most bacteria are beneficial, impacting positively for example on how we grow our food and in cleaning up the pollution we create. They are simply indispensable to how we live. They have been responsible for many of the geochemical changes which have taken place on this planet and play major roles in the transformation of elements so essential to our existence (Newman and Banfield, 2002). No one should dismiss them as minor players in our game of life.

Jan 1, 2004

By R C. Morris

Supergene lateritic iron ores are uncommon when compared with the vast tonnages of BIF-hosted microplaty haematite ores of the world or with the dominant supergene mimetic martite-goethite ores of the Hamersleys. In Australia and to a lesser extent in India and South America, mimetic replacement of gangue minerals by iron hydroxyoxides is a major factor in forming supergene iron ore from banded iron-formation (BIF) and results in the superb preservation of all of the original BIF features. This includes primary banding down to the finest inclusions, as a result of pseudomorphing of the BIF gangue at depth by goethite. The enrichment as a whole is an absolute accumulation of Fe at depth, dissolved from the surface BIF, and a removal of the gangue elements without loss of the original BIF mineral textures. Thus the ores grow upward to meet the downward destruction of the surface BIF by erosion. By contrast the supergene lateritic ores including the 'blue dust ores' are residual ores resulting from the relative accumulation of Fe. In the supergene lateritic ores derived from BIF, removal of the gangue is accompanied by repetitive solution and reprecipitation by secondary haematite and goethite. The final product of lateritisation of BIF and BIF-derived ores is typically complex, due to successive overprinting of earlier stages of alteration during the process, and because of the different precursors. This progressive lateritic modification tends to produce a varied surface complex including massive, vermiform, and botryoidal, or nodular aluminous/siliceous goethite and haematite, variously known as ferricrete, duricrust, canga, or 'hydrated zone hardcap'. The significant difference in these ores to the supergene mimetic martite-goethite ores is that they grow downward, with the total destruction of any of the parent BIF or BIF-ore textures.

Jan 1, 2009

By H J. J Boshoff

Mine closure planning integrated into life-of-mine (LOM) planning during the operational phase consists of many subcategories. One of these subcategories that needs to be fully integrated into the LOM planning is that of water management planning. Issues arise when mine water management infrastructure, which is required post-mine closure, is only considered closer to the end of LOM. Once the mine is closed monitoring is focused on water quality as an indicator of closure performance, hence inadequate upfront post-mining water management planning or integration into operations will result in environmental harm. The lack of considering post-mining water management is not uncommon in LOM planning. Poor mine site water management and planning are a wide reaching problem for the mining industry. Numerous active mines have been issued with environmental notices and penalties for contaminated water discharge; including issues with abandoned mines now being cared for by governments all over the world.Mitigating sources of water contamination caused by existing and closed mine sites that are leaching pollutants might be impractical, due to inaccessibility to the contaminants or final landform topography. The opportunity to consider and introduce post-closure required mine water management infrastructure is lost once the waste facilities are constructed. Mitigating contamination is made more problematic with mines located in remote areas, serviced by dedicated roads, water supply, electrical supply, etc. It is expected that these services will be decommissioned or drastically reduced, once closure is reached making remedial work much harder. Inadequate planning, to ensure access and easily maintainable water management infrastructure, could lead to erosion and contamination going unnoticed. There are numerous examples of poor mine water management practices in Africa, Asia, Australia, South and North America. In the United States more than 23 000 km of streams are affected by pollution sourced from some 50 000 abandoned or mature mine sites (DeGraff, 2007).CITATION:Boshoff, H J J, ?2014. Inadequate water management planning resulting in long-term closure liabilities, in Proceedings Life-of-Mine 2014 , pp 233–246 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By J A. Rowland

When executing a ventilation change the mine ventilation circuit is in a state of flux throughout the entire change period with discrete mine areas both under ventilated and/or over ventilated during the change process. Whilst routine risk reduction strategies such as removing electrical power and people from the mine are commonly deployed it is wise to complete the change in the shortest practical time frame. This not only minimises the chance of unacceptable concentrations of contaminants accumulating around the mine but reduces the impedance on production activities which are routinely suspended during these change periods. This paper firstly highlights the importance of the maintenance of an accurate ventilation model and discusses issues which should be considered to assist to maintain in it a suitable state of health. Further it provides some tips on how to monitor that your model is in an acceptable state of tune so that it can be confidently deployed in the change process. Finally, it details the sequential process how a finely tuned and accurate ventilation model can be utilised to carry out major ventilation changes according to appliance pressure adjustments only and without the need to constantly measure and check resultant branch flows throughout the whole change process. Also discussed are some simple practical tips which will help ensure that the ventilation change process will go according to the devised plan on the day and in the most appropriate order including checking the efficiency and accuracy of the change, after it is completed.

Oct 12, 2022

By A F. von Wielligh, M Scott, L Keeney

Operational Grade Engineering (GE) is the early (pre-processing) discard of low-grade mineralised and/or barren rock to improve the ore grade and/or reduce deleterious elements within the run of mine ore to be processed. GE activities generally have an impact on primary and ancillary mining activities, equipment utilization and overall equipment productivity. By discarding material which would have reported as ore (in a non-GE mine plan) means that GE must increases the total ore and total rock mining rate requirements to sustain mill feed targets. One challenge of GE and the planning of GE activities is that there are several indirect parameters which impact operational productivity. Modelling these potential impacts and determining if they can be overcome with alternate mine sequences, equipment application or possibly a different equipment fleet altogether is a key question requiring investigation. Overcoming these potential productivity obstacles associated with a more complex operation by introducing new operational parameters and destinations for ore and possibly sub-grade blocks, requires a GE mine plan that is coupled with detailed equipment productivity metrics and a sound operational plan incorporating all GE infrastructure requirements. Several GE mine plans and equipment productivity models indicate that mining rates generally need to increase by approximately 5% to 15% to sustain mill targets and often negatively impact equipment unit productivity metrices through increased cycle times, additional queuing and destination changes. These changes to productivity metrics are however offset by step change increases in asset value. This paper details a methodology to develop GE mine plans that incorporate equipment modelling, flexible mine sequencing and equipment-based production scheduling. In addition, the paper will outline impacts of GE planning on equipment unit productivities through worked examples and models.

Nov 10, 2020

By N Boughen

This paper synthesises the findings of five studies undertaken by the CSIRO Wealth from Oceans Flagship in 2009-10. This research explores the concerns, expectations, and information needs of a range of stakeholders, (ie government, seafloor exploration and mining industry, other marine industries, environmental non-government organisations (NGOs), community members) in relation to the possible exploration and mining of minerals and aggregates from the seafloor, as well as the conditions for meaningful engagement with communities regarding seafloor exploration and mining (SEM) activities. The SEM industry has been described as the ‘next minerals frontier’, as incentives to explore and mine seafloor resources increase because of diminishing reserves of easily accessible onshore mineral and aggregate deposits. However, the conditions (if any) under which SEM would be acceptable to stakeholders (notably the public and regulators) have not been established. This work seeks to address this gap and ascertain the levels at which potential environmental and social impacts become unacceptable to those stakeholders. The research follows an earlier phase of studies undertaken in 2006 - 2008 that: identified the opportunities and barriers to the development of SEM in Australia, took the first step towards understanding the public and political contexts surrounding the industry, and mapped the positions of key stakeholders and captured their major issues and concerns. Together, these two phases of research confirm that environmental concerns dominate stakeholders’ responses to the idea of an expanded industry. However, the most recent phase of research has also found that, similar to current onshore scenarios, reservations due to environmental concerns do not completely outweigh social and economic objectives. This is provided stakeholders feel confident that there are systems in place (regulatory frameworks, watchdogs, independent research, and stakeholder consultation) to ensure that all interests are protected. When making decisions about the social acceptability of potential seafloor mining, stakeholders favour a precautionary approach, supported by rigorous scientific analysis of the potential environmental impacts, transparent and socially responsive management processes, and meaningful stakeholder engagement. This paper outlines the details of these findings, which may also be relevant to understanding the social acceptability or ‘social licence to operate’ for other future mining scenarios featuring a new approach or technology.

Nov 22, 2011

By J Vann

Geometallurgy is inherently multidisciplinary and it gains its power to deliver improved outcomes for the minerals industry by bridging silos between disciplines. This cross-disciplinary approach unlocks value, identifies (and avoids) value destruction and provides a pathway to better implementation of an energy efficient and sustainable minerals industry. Despite this promise, we argue that the cross disciplinary approach also represents the greatest threat to the success of geometallurgy. Some key cross disciplinary issues identified are:Geometallurgy has so far evolved in the technical sphere, mainly by collaborations of geologists and metallurgists. Consequently, in many cases the business dimensions and value have not been incorporated. Financial and risk evaluation viewpoints need to be assimilated into the geometallurgical paradigm. In fact, until such measures are integrated into practices, the value cannot be fully demonstrated.The historical and current efforts on geometallurgy have been highly focused on improved sampling and measurement of geometallurgical properties or appropriate proxies. This work has been driven by professional and academic geologists and metallurgical engineers. It is notable that mining engineers (who are critical in the value delivery of geometallurgy through changed planning approaches) have so far been at the margins, or absent. The construction of valid three dimensional (3D) geometallurgical models raises some important organisational, mathematical and geostatistical considerations. The enhancement of resource models to account for geometallurgical aspects must be managed carefully if the full value of geometallurgical thinking is to be realised.The use of 3D geometallurgical models to change business decision making and practices is the real nub of the problem. We believe sophisticated scenario based evaluation methods are required if the potential impacts of spatial rock properties on processes further down the mining value chain are to be realistically evaluated. Such changed practices require ‘whole of value chain thinking’ to embed this change into the business in an ongoing way.Because profitable geometallurgy demands changed approaches to business decision-making and also organisation of the firm (radically changed in some cases), the senior executive viewpoint must be incorporated into the language and thinking of geometallurgy. This is unavoidable if the establishment of a geometallurgical approach to project evaluation, development and operation is to be successful and sustained.A powerful analogy for the problem faced by geometallurgy is the transformation of safety culture in the mining industry in the past 20 years. We argue that, as in the safety revolution, explicit models, cultural change and management of the ‘soft’ dimensions of the problem are pivotal to success of geometallurgy. In light of this, we propose a model (‘the Geomet Curve’) that gives a framework and pathway for geometallurgy in seven steps. The implications of this model for technical and organisational steps required at different stages are discussed.

Sep 5, 2011

By Neville Rockhouse

This paper examines the interrelationship of conducting full risk assessments in the context of the coal mining industry and under the framework of the Health's Safety in Employment Act 1992. In the context of Occupational Health's Safety, Risk Management is a holistic management process that can be used by individuals working in all organisations and from all industries. The Australian New Zealand Standard 4360: 2004 defines a Risk as being; The chance of something happening that will have an impact on objectives. This definition is followed by several notes that include: a risk is often specified in terms of an event or circumstance and the consequences that may flow from it, risk is measured in terms of a combination of the consequences of an event and their likelihood, and risk may have a positive or negative impact. For the purposes of this paper, the above definition will be adopted. This paper examines the newly expanded approach of the fully documented risk management process in the New Zealand coal mining industry. This is done in the context of the coal mining regulations but more importantly by using the framework of the Health & Safety in Employment Act 1992. This legislation under Section 6 requires all employers to, Take all Practicable Steps to prevent harm coming to employees while at work and to others who might be at or in the vicinity of a workplace. When the term 'all practicable steps' is studied, one can clearly see that such steps should be the same steps taken that a prudent and reasonable person would have taken given the same type of circumstance. Due to the fact that in New Zealand parliament made statutes is administered by a Government Department, means that their breaches will be heard before a judge in the District Court. Under the Westminster System of Justice, a basic dictum of that court in matters relating the occupational health and safety is that a breach needs to be satisfied to a specific standard. That standard is, 'Beyond a reasonable Doubt'. One of the primary benefits of adopting a proactive approach to risk management is that if the industry were to adopt similar approaches, then this mythology could be seen as an industry standard. As such, the approach carries the same status in a court of law, as that of an Approved Code of Practice.

Jan 1, 2007

By M Manefield, G Bournival, S Ata

Asteroids contain an abundance of valuable resources such as: nickel, cobalt, gold, platinum and rhodium. Whilst the consumption of mineral resources on Earth continues to deplete, meteoroids have the potential to become a significant source of minerals. Even though the minerals content of asteroids may be relatively high, the valuable minerals are more likely to be only a small portion of the total ore present in the main body. The ores must, therefore, be processed to extract the metals of interest from the waste. Existing terrestrial technologies rely on manipulating the physical and chemical properties of minerals. The application of these techniques to asteroids processing, however, is not straightforward due to the presence of different conditions such as zero gravity and lack of water in space. This paper discusses potential separation and extraction techniques that can be used for processing of asteroids.CITATION:Ata, S, Bournival, G and Manefield, M, 2015. Resource recovery in space, in Proceedings Third International Future Mining Conference, pp 275–280 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By Y V. Haarlem, P Coghill, N G. Cutmore, M Millen, I Carter

Due to the low concentration of gold, ore sorting for gold has always required measuring indirect properties, such as density or colour, to allow separation on a rock by rock basis. This only works on an ad hoc, by deposit basis and is likely to be least reliable where it is most required in low grade ores. One candidate technique, Gamma Activation Analysis (GAA) has been demonstrated to directly measure gold extremely accurately in powder samples of around 500gm and is used in the Chrysos PhotonAssay assay system. This method uses a linear accelerator (linac) to generate the X-ray radiation that activates the ore at low levels to emit a characteristic gold gamma ray that is then measured by a radiation detector. CSIRO is adapting this measurement technique to application on a belt at up to 800tph to measure pods of ore. The principal differences between measuring samples and an on-line measurement of pods are the requirement to measure coarse ore (<50mm), to measure a larger volume of ore as uniformly as possible, and to have an open-ended geometry with adequate shielding of the linac radiation source. These issues have all been addressed with measurements of coarse ore reported down to around 1ppm in sub-optimal test conditions. They have been demonstrated for <75mm particles with detectors capable of measuring a large volume geometry continuously. These are projected to allow measurements down to 0.3ppm in more optimum conditions for a 10 second measurement time period where the U/Th content of the ore is less than ~10ppm. Extensive Monte Carlo modelling has demonstrated that adequate shielding can be provided in relatively simple geometries with only 1 right angle transfer in the material handling. Steady progress is being made to reach the technical position required to trial an ore sorting system.

Nov 10, 2020

By B P. Wrench, N R. Steward, C Wu

A gold mine in southern China has transitioned from an open pit operation to a fully underground mine. An overhand mining method is used which requires the mined stopes to be filled with backfill having an unconfined compressive strength of at least 0.35MPa. Tailings from the process plant is deposited into separate flotation and Carbon in Leach (CIL) tailings storage facilities. The tailings has a high fines content and the thickener on site could only produce a dilute flotation tailings at a solids content of about 30 wt%. This resulted in two undesirable outcomes: the density of flotation tailings in the Tailings Storage Facility (TSF) was significantly lower than planned so that the TSF could not store the life of mine tailings and that the backfill product had to include a high percentage of manufactured aggregate and increased cement content to achieve the required strength. This paper presents results of a tailings study which identified that the flotation TSF would be capable of storing the remaining life of mine tailings if an amended backfill product made up of 100% of flotation tailings could be introduced. A 100% tailings backfill with the addition of 8% cement was developed by classifying the tailings and using the coarser fraction in the backfill. This backfill allowed 60% of the flotation tailings to be placed underground and only the remaining 40% in the flotation TSF. A new thickener was designed and installed to thicken the tailings and rheological testing of the tailings, using a closed loop pilot plant, provided parameters to upgrade the underground reticulation system to deliver cemented backfill to stopes throughout the mine and to deliver thickened tailings to the TSF. The revised design was implemented and has resulted in considerable cost savings. CITATION:Steward, N R, Wrench, B P and Wu, C, 2018. Optimisation of surface tailings storage and tailings backfill – a case study, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 454–464 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

The carbonatite-hosted apatite deposit at the Cajati open pit mine in the Jacupiranga igneous-carbonatite complex is located in south-eastern Brazil. The major styles of apatite mineralisation include veins or veinlets, small pods or patches, disseminated apatite and locally massive aggregates. The metallurgical concentration of the apatite is accomplished by grinding the carbonatite, removal of magnetite with a magnetic drum, size classification with cyclones and flotation to suppress carbonates and collect apatite. To examine the character of the apatite grains and to apply those observations to apatite beneficiation, specimens of carbonatite were collected from recent exposures in the mine and from selected drill holes. This study utilised a variety of microscopy methods, including transmitted and reflected light, cathodoluminescence (CL) and scanning electron microscopy with wavelength-dispersive spectrometers for mineral compositions. It was found that LREE, Na and Sr are the main elements replacing Ca in the apatite, with relatively low oxide contents (&lt;0.5 per cent, but up to about one per cent for Sr). LREE and Sr contents consistently increase in the latest intrusions (C4, C5 and SP24). Chemical and morphological modifications of apatite were recognised to be related to detrimental effects on flotation recovery. Three examples illustrate this relationship: 1.&nbsp; Apatite with reddish CL is fractured. Locally that apatite exhibits no CL due to CL quenching caused by iron entering the apatite structure.2.&nbsp; Apatite from the xenolith-rich area exhibits abundant fine, platy silicates that appear to interfere with flotation and lower apatite recovery.3.&nbsp; So called æhardÆ apatite, which is more difficult to grind, occurs in an area in the mine that was affected by hydrothermal activity. That activity is evidenced by the development of a bright, white CL rim in the apatite, and by the presence of late veins of carbonates and sulfides that fill fractures and appear to contribute to higher cohesiveness of those apatite grains.

Jan 1, 2008