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By D Lozada, A Salazar

Geometallurgy is a tool that, for more than a century, has been present in the implicit operations of mineral beneficiation. There’s a need to understand the characteristics of the material to be processed. This has led metallurgists to ask geologists what type of rock and mineralogy is entering the Beneficiation Plant and vice versa. The geologist needs to understand the beneficiation process in order to be able to carry out the production programming. The paradigm is whether geometallurgy can be applied to small-scale mining or if it is only aimed at large companies that invest millions of dollars to conduct studies. With this work, we provide an example of how geometallurgy can help improve the processes of a small mining company located in Ecuador (South America). We performed characterizations of geological and mineralogical and metallurgical tests in universities and the National Research Institute of Geological Metallurgical Mining. The origin of the theme is based on the fact that gold has been detected in the final tailings. The flotation concentrates meet the standards in terms of the content of economically profitable metals, but this isn’t the case with regards to the percentage of arsenic, which has hindered sales. The hypothesis is: conducting technical and scientific research will optimize the metallurgical process for the recovery of gold and concentrates. The referential framework is the mining geology of the Bella Rica District, current status of the Beneficiation Plant. In the theoretical framework there are parameters of the veins, comminution operations, gravimetric concentration, flotation, and cyanidation. The methodological framework contemplates the characterization of the gold ore, the chemical, mineralogical, textural, metallurgical analysis and the interpretation of the results. Thus, the design of a geometallurgy model of the deposit, with its main characteristics, is a conclusion that serves as a basis for the proposal of the optimization of the metallurgical process.CITATION:Lozada, D and Salazar, A, 2018. Geometallurgy applied to small-scale mining: a case study, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 153–162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By O Arafat, R E. McIvor, K M. Bartholomew

It is well known in the industry that good classification system performance is vital to efficient ball mill circuit performance. But what is meant by good classification system performance, and how is it achieved? Unfortunately, the perceived complexity of classification systems, and the day-to-day time demands placed on the practicing metallurgist, all too often put the low-hanging fruit of classification system optimisation in the ‘I’ll do it later’ basket. Additionally, lingering confusion about basics such as the relationship between circulating load ratio and ball mill circuit performance makes the optimisation objective seem nebulous to both plant metallurgist and designer.Some of this confusion can be eliminated by taking a step back from the overwhelming detail of sharpness of separation curves, circulating load ratios, cyclone feed pressures, vortex and apex sizes etc, and focusing on the purpose or function of the classification system – to apply mill power to particles that need further size reduction! The classification system efficiency (CSE) metric captures how well the classification system is performing its function with two quick and easy size distribution analyses.Once CSE is understood and implemented as the optimisation criteria, well-tested methods for improving CSE can be implemented and quickly measured at plant scale to give confidence that the right change was made.This paper will describe CSE and how it is measured in practice. Next, a guide for improving CSE through manipulation of design and operating variables in the classification system will be provided. Examples and case studies will illustrate the gains in ball mill circuit efficiency that can be achieved by maximising CSE.CITATION:Bartholomew, K M, McIvor, R E and Arafat, O, 2018. A guide to maximising ball mill circuit classification system efficiency (CSE), for operators and equipment designers, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 553–558 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By M D. Taylor, G Duclaux, K Atkinson, L A. Fisher, A R. Latham, M F. Gazley, S J. de Beer, C M. Tutt

Geological logging by mine and exploration geologists involves the application of a logging code that requires a geologist to make a subjective decision to classify a particular rock unit. This will most likely result in inconsistencies in logging that will be difficult to monitor or assess over time. A potential solution to this problem is to have an objective method to determine the true nature of a given rock unit. This can be achieved using portable X-ray fluorescence technology (pXRF), as large geochemical data sets can be collected rapidly and at low cost. Plutonic Gold Mine (Plutonic), Western Australia, has a growing data set of more than 150 000 pXRF multi-element analyses from core and underground face samples, reconciled to Au fire-assay concentration, and logging codes. This study investigates and statistically validates the consistency with which the logging codes have been applied at Plutonic for the last four years, with respect to both Au distribution and other elements. In doing so, we have developed a schema that allows objective logging to occur once core has been sent for assay and analysed by pXRF. While far from replacing the geologist in the field, this is a complementary method that adds significant value to a data set.CITATION:Gazley, M F, Tutt, C M, Latham, A R, Duclaux, G, Fisher, L A, Taylor, M D, de Beer, S J and Atkinson, K, 2013. Objective geological logging using geochemical multi-element data - Plutonic Gold Mine, Western Australia, in Proceedings World Gold 2013 , pp 455-462 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By M K. Kapo, S C. Nzama

The success of a mining operation depends on the quality of data used in decision-making processes and the people involved in making operational decisions. At Olympic Dam, mine geologists form an integral part of the teams that make decisions at various key points in the mine operational value chain. Mine geologists are directly and indirectly involved in all stages of the mining process, namely, orebody definition and categorisation, mine design and planning, metallurgical processing, and reconciliation.Due to the sheer size and complexity of the Olympic Dam deposit, each mining stage has been divided into smaller units within which decisions are made in line with the overall mine operational plan. In each of these units, the decisions and inputs made by mine geologists has ensured that consideration of geological factors is made in the mining process. Over time, the mine geology team has demonstrated a systematic approach in the development and improvement of their processes in line with the mine’s operational needs, such as understanding the in-stope ore variability and maintaining a consistent ore feed to the plant. An understanding and interpretation of the mineralisation distribution, based on acquired data, has proven to be important in the definition of resource modelling parameters. These parameters in turn affect the quality of grade estimates and their downstream use in planning, production and subsequent reconciliation processes. The continual study of the geology of the deposit, and unravelling its complexity through research has been crucial to the metals extraction process. The involvement of mine geologists through each of the mine value processes places Olympic Dam in a favourable position to benefit from future opportunities that will take advantage of the increasing operational demands and production pressures, and the ever changing economic conditions.This paper reviews the role mine geologists play in the realisation of the Olympic Dam deposit, from ore to product, through their interaction and collaboration with other departments and stakeholders. This paper also highlights mining practices employed at the Olympic Dam mine.CITATION:Nzama, S C and Kapo, M K, 2014. Managing the giant – a mine geologist’s perspective to the mining of the Olympic Dam deposit, in Proceedings Ninth International Mining Geology Conference 2014 , pp 451–460 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By R Moreby, J Kok, L van den Berg

The high production rates achieved from mass mining methods such as block caving, sublevel caving and longwall mining require large conveyor belts, trucking loops (diesel/electrical) and rail systems for ore handling. However, the ore handling systems used in mass mines introduce a significant amount of heat into the overall ventilation system, which may be problematic at depth or in mines located in hot climates.In particular, the heat load from a conveyor system is not always well understood and consists of various components, including frictional heat from idlers, heat from electrical motors, heat from the drive train and heat from broken rock transported on the conveyor system. This paper presents results from a study that investigated the heat introduced to the ventilation air from a large conveyor system. The conveyor system transports ore with a maximum virgin rock temperature of 41°C from a depth of over 1 km. Air, belt and rock temperatures were measured in the conveyor system to evaluate the distribution of heat loads.CITATION:van den Berg, L, Moreby, R and Kok, J, 2015. Heat load estimation from conveyor systems in mass mines, in Proceedings The Australian Mine Ventilation Conference, pp 63–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By R Minnitt

Two methods of calibrating the parameters K and Alpha for use in Gy’s formula for the fundamental sampling error were investigated. Approximately 480 kg of broken ore from Harmony’s Target gold mine in South Africa was used to compile the replicate samples for two experiments. The duplicate series analysis (DSA) and segregation free analysis (SFA) methods differ in terms of their approach to recovering the sized materials required for the calibration procedure. In this experiment the DSA method split off six more-or-less equal masses of material from a 75 kg lot that was successively crushed to finer and finer fragment sizes. The sublots so formed were split into 32 samples and fire assayed for gold. The SFA method used approximately 250 kg of broken ore crushed to 95 per cent passing 2.50 cm, which was then passed through successively finer screens until a sublot of less than 0.0075 cm was obtained. Each of the 15 sublots obtained in this way were split using a riffle splitter into 32 samples that were fire assayed. A total of 672 fire assays were used in these experiments. The sampling parameters K and Alpha were used for the compilation of a nomogram and to calculate the gold liberation size of the ores. While there are no definitive results in terms of the actual gold grain sizes against which the calculated sizes can be compared, it appears that the DSA method produces more acceptable results.CITATION:Minnitt, R, 2014. A comparison of two methods for calculating the constants K and alpha in a broken ore, in Proceedings Sampling 2014 , pp 165–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By N Clarke, A Barros

Preconcentration of run-of-mine subgrade and marginal ore by screening has the potential to substantially improve the economics of mining, particularly for large, low-grade orebodies, and to reduce environmental impacts. It has recently been the subject of a major research effort by a joint public-private research body, CRCORE. Yet despite this, there appears to have been only one fully commercial installation, at Bougainville Copper Limited in the late 1980s. Two reasons for the limited application are that not all ores have suitable properties and the economics of all pre-concentration processes on low-grade materials are highly sensitive to the precise balance of mass and value recovery and to the pre-concentration process cost, including materials handling. These factors make it imperative to have good test data on the process response of feedstock across the orebody. Collecting that data presents major challenges, which differ for green and brownfields operations. This paper first discusses the approach to preliminary evaluation developed by CRCORE, which relies on testing of coarse rejects or drill chips available from exploration drilling programs. This method is an efficient first step in evaluating an orebody which is deemed geologically to be potentially amenable to screen upgrading, but it does have limitations and must be followed by larger scale work. A suite of methods have been developed by the authors as a result of test work since the 1990s on several projects, supplemented by published data, which aim to provide statistically robust data at lower cost than large scale bulk sampling tests. For greenfields projects, the upgrade response measured on material crushed to -53 mm has been found to correlate closely with ROM ore, with no scale-up required for material with upgrade responses in the range of commercial interest. Large diameter whole drill core, such as PQ, is expected to be suitable for this method. As drilling such core is costly, the aim should be to establish relationships between upgrade performance and proxy measurements such as multi-element chemical or hyperspectral analyses. This approach was successful at the Gramalote gold project in Colombia. The method is not applicable for ores with thick vein material comparable with the crush size, but such material is not suitable for upgrading by screening and would be eliminated by the preliminary testing. For brownfields projects where blasted material can be sampled, the upgrade response can be accurately measured by sampling only the finer fraction of the ore, selecting a top size which represents 30–50 per cent or more of the ROM size distribution. This is likely to be between 50 and 100 mm. The much finer size compared with the full ROM ore greatly reduces the sample mass required to achieve a given intrinsic sampling error and enables sample preparation to be undertaken with large-scale laboratory equipment rather than mobile crushing plant. The accuracy of the method can be improved by measuring the approximate mass of oversize rejected during sampling. Some ores do show a systematic deviation from the assumed model fit which results in this method slightly underestimating the upgrade response, and it would therefore still be recommended to take one or two full bulk samples to confirm results before a final investment decision.

Aug 24, 2022

By C Staak, H Mischo, A Fichtner, F Reuter

In mining and remote areas of resource industry, there has been a development towards lacking emergency medical first aid response, that creates a potential disadvantage for patients after work accidents and other medical emergencies compared to standard population. This raises the question how a professional emergency medical coverage can be provided underground, taking into account lacking medical professionals in small resource companies combined with long rescue times. Aiming on the closure of this gap, a team of the mine rescue brigade from the Research and Training Mine Reiche Zeche (Forschungs-und Lehrbergwerk (FLB) Reiche Zeche) of the TUBAF Technische Universität Bergakademie Freiberg in Freiberg/Germany and its cooperating emergency departments of the Freiberg District Hospital and the Zeisigwaldkliniken Bethanien Chemnitz developed a totally new rescue concept using elements from tactical medicine and advanced emergency medicine combined with a specifically designed compact equipment and a highly standardised teaching curriculum. A fully new standardised and condensed tactical medical approach was developed including specifically adjusted equipment, and was taught in a didactically optimised way within 16 lessons in two days. Objective Structured Practical Examinations (OSPE) using manikins and simulated patients were conducted and compared to the identical exam of the reference group, which consisted of advanced paramedics. The standardised tactical medical scheme includes vital functions and body checks, advanced life support, nasal and intraosseous drug application, supraglottic airway management, artificial ventilation, thoracocentesis, bleeding control including tourniquet, fracture repositioning and splinting, transport bedding and thermal preservation. The developed Tactical Medical Mining Rescue (TMR) concept was subsequently included in the German guidelines for mine rescue services in 2022 and is already implemented in many companies in Germany and several international projects.

Sep 1, 2024

By A S. Fogliata, L Bengochea, G Mas, J E. Lazarte

The Culampajß auriferous district is located in the northern sector of the eastern edge of the homonymous hill, Catamarca Province, Argentina. Tajo Largo mine is situated in the southern flank of Las Minas gulch at an approximate height of 3.600 m above sea level. In the studied area main outcrops are orthogneiss rocks of Chango Real Formation. The ore mineral is native gold with a lesser amount of pyrite, chalcopyrite, haematite, limonite, malachite, azurite and covellite. These ore mineral assemblages are disseminated in quartz veins filling tension fractures in the host orthogneiss.Several types of inclusions have been recognised, including three phase H2O-CO2liq-CO2vap inclusions, polyphase inclusions with H2O-CO2 and one or more solid phases, and two phase aqueous inclusions. In the three phase H2O-CO2liq-CO2vap inclusions the Tmclath is about 1¦C and the CO2 liquid-vapour homogenisation occurs at 26 - 28¦C, to liquid phase. The homogenisation temperature of H2O-CO2 occurs at 365 - 380¦C in the aqueous phase. This set of data defined a solution with a salinity of 14, 4 wt per cent NaCl equivalent and a density of 0.84 g/cm3. In the two phase aqueous inclusions the melting temperature (Tm) of -5.4¦C and the eutectic point (Te) in -38¦C indicates a salinity of about 7.5 wt per cent NaCl equivalent, with the probable presence of Ca2+. Density of fluid is about 0.83 g/cm3. Homogenisation temperature ranges between 260¦ and 280¦C. The pressure, temperature and salinity of fluids in the polyphase inclusions suggest an early fluid of high density and high salinity. The three-phase fluid inclusions may be the result of an unmixing-phase separation of post magmatic hydrothermal fluid due to pressure decrease along fractures. It is suggested that the deposit was formed during the late magmatic hydrothermal stage genetically linked to granitic rocks and can be comparable with the intrusion-related gold system of Baker (2003).

Jan 1, 2008

The subject of my paper is one which, I am certain, has exercised the mind of every man on whom depends the safe and economical conduct of mining operations; particularly in this district where the enormous size of the ore body has necessitated the mine workings assuming a scale that was hitherto unknown in the history of Australian mining. I, therefore, approach the subject with the feeling that I am displaying considerable t.emerity, knowing as I do that the subject has engaged the earnest attention and thought of everybody immediately concerned in the extraction of the ore of this district, and particularly of the Broken Hill lode.I think I shall not be contradicted in asserting that a very large proportion of eur accidents are distinctly traiceable to inexperience on the part of the miner, and records at the mines and verdicts of coroners' juries in many instances uphold this assertion by showing that the accident under notice was the direct result of lack of knowledge of the conditions of the work, or, at any rate, of an error of judgment hardly conceivable in the experienced miner. That this assertion is correct may also be proved by visiting any of the mines of the district.To the experienced eye it will be evident at once that a very large number are not in way skilful in the use of their tools and, therefore, lack the experience which of necessity must be coincident with the acquirement of skill. Now in making this' assertion, I do not intend to be too sweeping...

Jan 1, 1903

Tunnels are being built around the world using TBMs and prefabricated segments or in situ concrete as linings. Clients demand high quality of these linings to guarantee a long-term stability and density of the tunnels. This paper describes the development and the use of segmental lining systems, including joints, important design criteria, installation procedures, possible mistakes and consequences, repair works and final results for different sites in Europe and around the world. The experience on these sites shows that damages may occur, if some essential aspects are not considered. These aspects include:parameters of the TBMs and back-up equipment such as fixation of jacking rams, movement of the back-up on the lining or ring reformer;parameters of the segments such as quality of moulds, quantity of reinforcement or structure of the joints; andparameters of the tunnel drive such as advance rate, ring-gap grouting or experience of the tunnel crew.All these aspects have to be considered very carefully in detail to get a good lining accepted in total.

Jan 1, 1999

By M I. Pownceby, S P. Suthers, V Nunna, G J. Sparrow

Global demand for iron and steel has increased substantially over the past 20 years and there has been a greater focus on developing suitable processing options to treat low-grade hematite-goethite ores containing higher levels of silica and alumina impurities. The processing applicable to reduce the impurity levels in these lower-grade iron ores depends on their mineralogy and a thorough understanding of the process dynamics associated with the separation technology. Different separation technologies used to remove silica and alumina from low-grade iron ores were reviewed. The major concentration methods that may be applied to upgrade lower-grade lump iron ores include magnetic separation, wet and dry heavy media separation, and air-pulsed jigging. The technologies applicable to beneficiating iron ore fines include wet and dry gravity and magnetic separation, flotation, and roasting followed by magnetic separation. It is necessary to investigate the application of separation technologies on a case-by-case basis to select economically viable beneficiation strategies suitable for the particular low-grade iron ore. A commercial flow sheet is expected to involve the implementation of several separation technologies.

Nov 8, 2021

By S Khadhraoui, T Yusuf, C Kirmse, E Hecker, R Degel, A Akouch, N Borowski, M Reuter

For an optimal design and control of metallurgical processes, a deep understanding of the thermodynamics of the governing reactions is required. Modelling the thermochemical behaviour of those reactions is complex, as it involves multi-component and multi-phase systems. For this purpose, thermodynamic computing systems such as FactSage™ (Bale et al, 2016), which combine Gibbs energy minimisation routines with large databases of optimised thermodynamic data of solutions and compounds, have been used within the SMS group GmbH. Recently, the successful integration of those thermodynamic computing systems into the digital platforms of SMS has been achieved through ChemApp, which made running complex thermochemical calculations in Python-integrated development environments possible. ChemApp is a programmer’s package for thermochemistry and incorporates the Gibbs energy minimiser of FactSage™ as reported by Petersen and Hack (2007) as well as by Zietsman and Petersen (2018). The digital platforms link the fundamental and the industrial aspects together and can be applied as a process advisor, or for the evaluation of the environmental footprint and the economic implications of different process routes, as discussed by Reuter (2023). Two examples illustrating the progress of the developments in this regard will be introduced: 1. The Tilting Refining Furnace (TRF) for copper scrap recycling and refining to anode copper (the BlueControlApp). 2. Dephosphorisation control for the oxygen steelmaking process (Basic Oxygen Furnace (BOF)).

Jun 19, 2024

By K W. Mills, N R. P Baczynski, J Mylvaganam, D A. Prado, M F. Lee, I A. de Bruyn

"This paper presents the second part of a study of the assessment of rock stress inputs on the performance of various new mining designs at the Ok Tedi large open pit mine in Papua New Guinea. Over the years, four programs of rock stress measurement have been completed at Ok Tedi, each providing different interpretations of the in situ field stresses. Details of three of these programs and interpretations are provided in the precursor to this paper, entitled ‘Rock Stresses at Ok Tedi, Papua New Guinea’ (Lee et al, 2014).This paper explains how the various stress interpretations were utilised in the modelling of the proposed new open pit and underground mining excavations, comparing where possible their expected effects on stability. The modelled performance of three specific mine components have been discussed here as case studies, including: the below-pit drainage tunnel, as the floor of the open pit workings is mined down from 350?m above, to within just 75?m above the crown of the tunnel the stability of the 1000?m high slope of the proposed West Wall cutback the proposed sublevel open stoping extraction sequence in the Gold Coast orebody beneath the East Wall, for which only the likely ‘worst-case’ stress regime was used to assess sequencing and stability issues.The benefits of scheduling the collection of detailed rock stress measurements and other input data from a range of different sources at various stages of the projects are discussed.Alternative in situ stress models have less stability impact on open pit slopes than on underground mine excavations.CITATION:de Bruyn, I A, Baczynski, N R P, Lee, M F, Mills, K W, Mylvaganam, J, and Prado, D A, 2014. The application of rock stress inputs to stability assessments at Ok Tedi Mine, Papua New Guinea, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 43–54 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By S Fityus, K Koosmen, J Simmons

The purpose of this paper is to therefore investigate the hydrogeological characteristics of tailings, coarse and mixed rejects from coal processing to enable better understanding of the potential for undrained behaviours in coal mine spoil piles. This is achieved by analysing the results from permeability and oedometer testing of tailings, coarse rejects and mixtures thereof. Focus is given to the effect that tailings content has on the behaviour of mixed rejects, the transition point between drained and undrained material behaviours, and the evolution of properties with increasing stress that would occur with increased depth of burial in a mine spoil pile. The implications of the findings are discussed with respect to spoil pile stability.

Jul 1, 2021

By S H. Algie, E J. Knoblauch, I A. Lovatt, S G. Doig

Mill operating teams are expected to engage in a perpetual quest for process improvement – pushing the boundaries of practical process limits and testing new technology to achieve the next step-change in plant performance. Often the barrier to improvement lies in gaining management approval for process changes.Getting approval for investment in novel technology carries an added degree of difficulty, particularly in risk-averse operations, when it challenges conventional wisdom. A case in point is a new technology for controlling variability in slurry distribution. There is a widely held view that less-than-specified classification efficiency and spraying and roping of individual units in a hydrocyclone cluster, must be accepted as unavoidable. That these are wholly correctable deficiencies resulting from unequal loading of the individual units seems a bold claim. Wouldn’t the high turbulence of pumped slurries overcome all potential for segregation of solids? This paper discusses how the task of developing confidence in a new technology can be approached by a combination of physical modelling at small scale, and full-scale operating experience. Proving efficacy then leads to the next task: demonstrating value. Again, the particular technology serves as an example that could be of value to others developing relatively low-cost technologies. A high-pay-off as an investment may be achieved with improvements in metallurgical performance that are small in relation to normal process variations. This has led to an exploration of how process simulation modelling could be used, in conjunction with production data, to provide a benchmark for the expected change, which could be expressed in monetary terms.The next goal, which is currently being achieved in operating plants, is to realise the greater value now available through the optimisation of cyclone configuration, which becomes practical when the confounding effects of cluster instability are removed through equal loading.CITATION:Doig, S G, Algie, S H, Lovatt, I A and Knoblauch, E J, 2018. Investing in new process improvement technology: reducing the risk of implementation – a way forward, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 571–584 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By F Cesnik

The past few years has seen a concerted effort to improve the recovery of gold along with its co-product copper from the æhigh-gradeÆ Ridgeway concentrator at Newcrest Mining LtdÆs Cadia Valley Operations. A number of initiatives were identified and implemented, culminating in a sustained improvement in recovery of approximately three to four per cent for both metals. The key projects that contributed to this improvement included the installation of a 355 kW Metso stirred media detritor (SMD) to create a regrind circuit, installation of froth crowders on the scavenger circuit, installation of a Falcon SB2500SE gravity concentrator as part of the regrind circuit to improve gold recovered to bullion on-site and the optimisation of the grinding circuit to reduce the 80 per cent passing size (P80) of the primary grind from 160 to 121 ¦m for the same throughput via process control, cyclone and ball charge optimisation. This paper will focus on the supporting test work, where applicable, that was used as the design basis for the project, but more importantly the plant data before and after the changes to clearly identify the improvements to plant recovery.

Jan 1, 2007

In practice a sampling solution is a compromise of many requirements: the sample should be representative; the sampling system should also be reliable, less than 95 per cent availability restricts the use of the assayed sample for process control purposes; no sample is the worst sample, and investment costs and installation space/layout are frequently a restriction. For instance, online X-ray analysers for process control introduce a delimitation error by the nature of X-ray physics. Thus only in special cases a relative accuracy better than three per cent relative, as one standard deviation, is achieved. A sampling system for process control needs not to be, as representative, for so many sample properties, as one for composite laboratory analysis samples. Sampling system maintenance is also an important issue. There are many sampling systems in the industry which have been difficult to maintain and are in disuse for lack of resources or incentives to keep them running. Pierre Gy developed the most generally accepted sampling theory. One of the main principles is that all particles in a one-dimensional process stream should have equal chances of being included into the sample. A correctly designed and operated transversing cutter comes close to this goal but has limitations in temporal representativity. For slurries an acceptable solution in many cases is to use a fixed vertical cutter(s) in a position where the slurry is well-mixed by turbulence and other means. For online analysis, reliability problems are mostly related to faulty design or installation of the piping system to the analyser. Properties of material processed, process flow sheet and piping details before and after the sampler have to be taken into account when deciding on which sampling arrangement is appropriate. Guidelines and some solutions to these issues are presented in this paper.

Mar 1, 2010

By Y Zhang, Z Zhao

The green production of the steelmaking process has urgent requirements for fluorine-free fluxes. In this article, a new solid waste-based slagging flux was applied in the external dephosphorisation test of low silicon hot metal to replace the traditional fluorite-lime dephosphorisation slag. The results showed that under laboratory conditions, the new flux was utilised for smelting low-silicon molten iron with a phosphorus content of 0.10~0.13 wt per cent, the temperature of the molten iron was 1350°C and the slag amount was controlled at 2 per cent. Within ten minutes of smelting, the dephosphorisation rate of the molten iron reached more than 50 per cent. When making slag with new flux, the slag melting time was about 40 seconds and the P2O5 content in the final slag was higher than 8 wt per cent. In the industrial test of a 150 t molten iron ladle, under the same molten iron conditions, an out-of-furnace dephosphorisation test was conducted in the Kambara Reactor (KR) process. The flux material consumption per ton of steel was 8~10 kg. Within 15 minutes of smelting, the dephosphorisation rate of the molten iron was about 30 per cent. During flux slag making, the slag melting time was about three minutes and the P2O5 content in the final slag was higher than 6 wt per cent. This new solid waste-based flux has significant cost advantages and outof- furnace dephosphorisation effects and is expected to become the benchmark for a new generation of fluorine-free steelmaking fluxes.

Aug 21, 2024

By A M. Lechner, S Arnold, M J. Gillespie, P D. Erskine, D R. Mulligan, A T. Fletcher, A Gordon

Mine ecological monitoring schemes are often conducted only to address compliance and in some cases do not have the sufficient statistical power or understanding of ecological systems to assess, quantitatively, the meeting of rehabilitation targets or mine impacts. Monitoring schemes for rehabilitation commonly rely on analogue sites or premining baselines (reference sites) to assess whether rehabilitation sites are ecologically similar and thus successfully rehabilitated. In the case of monitoring for mine impacts, if the impacted sites diverge from reference data, the site is considered to be impacted. Fundamental to any monitoring scheme is testing the sampling design to ensure that it can detect these differences if they are present through adequate sample sizes (ie statistical power). However, a good understanding of the ecological system is required to ensure that differences detected are ecologically significant. Modelling ecosystem properties can provide a quantitative understanding of how ecosystems change over time and space, in response to natural environmental variations and thus aid in determining significant ecological differences. Furthermore, modelling methods can be used to predict future ecosystem states. Within the ecological literature, guidelines for robust statistical monitoring designs and modelling methods exist but are not routinely being used in the mining industry. This paper uses simple examples to discuss: problems with current compliance monitoring methods; importance of robust statistical techniques; and how modelling can assist rehabilitation assessment and guide monitoring schemes. The aim of this paper is to describe general monitoring and modelling methods that could be potentially used for mine site monitoring and closure assessment. These methods are often considered by mining companies as an extra expense that provide little practical benefit, and the domain of academia; however, engaging these methods may be more cost-effective in the long-run than conducting untargeted monitoring schemes that give no confidence to regulators on whether rehabilitation criteria have been met. Furthermore, monitoring programs in mining contexts provide a good opportunity to better understand long-term ecological patterns and test the application of more rigorous modelling approaches as the life of many mines tends to be greater than ten years.CITATION:Lechner, A M, Arnold, S, Fletcher, A T, Gordon, A, Erskine, P D, Gillespie, M J and Mulligan, D R, 2012. Embracing modern ecological methods - Monitoring and modelling for mine closure, not compliance, in Proceedings Life-of-Mine 2012 , pp 25-32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012