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By G Noonan, S Thomas, M Limbert

Stuck drill rods (often referred to as bogged rods) in production ‘upholes’ are a common problem in the underground mining industry. Bogged and broken off drill rods have the potential to fall out of the hole without warning, posing a serious hazard to personnel and equipment below.Current industry practice to alleviate this hazard can be to either grout the hole in order to lock the drill rods in place, or to ‘plate over’ the hole with a rock bolt. Each of these operations seriously delays mine production as both require demobilisation of the production drill and mobilisation of alternative personnel and equipment to address the hazard. Both methods have been assessed for safety and efficiency and were found to be expensive, time consuming and in the case of plating over, ineffective.To address the safety and efficiency short-comings of the traditional practices, the long hole plug (LHP) has been developed to safely secure the lost rods in the hole. The LHP when struck by falling drill rods behaves similar to an expansion shell anchor transferring the axial forces from the falling drill rods horizontally into the rock mass. It is installed using standard production drills allowing work to safely continue with little interruption.Extensive testing has been carried out on the LHP in the laboratory and underground at the Rosebery mine on the west coast of Tasmania, Australia. Testing has included static pull testing, full scale drop testing and underground trials.The outcome of this work has proven the LHPs ability to add safety, volume and cost benefits to the Rosebery underground operation and it is currently in use at that site. It enables proven elimination of a common workplace hazard immediately, thus eliminating delay on the mine’s production cycle.CITATION:Thomas, S, Noonan, G and Limbert, M, 2017. Long hole plug – addressing the hazard of bogged rods in ‘upholes’, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 305–310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By E Nettleton, A Melkumyan

A probabilistic system for autonomous tracking of excavated ore in mining would be highly valuable. Currently, mine sites can have a vast array of sensors; examples include excavator load cells, bucket volume estimators and haul truck strut pressures which can be used to gather information about the excavated ore at different locations. These sensors can be utilised efficiently to increase the accuracy of mine estimates by introducing a real-time ore tracking system. This requires the introduction of a probabilistic ore tracking framework to consistently fuse information from any sensor input. Current modelling practices are manually intensive, deterministic (no recognition of the quality of data) and generally not a complete end-to-end system. This paper will provide a novel method for tracking extensive ore properties (mass, volume) and intensive ore properties such as chemical composition (eg Fe per cent, SiO2 per cent, Al2O3 per cent). This method is proved to ensure that correct correlations between states are conserved as material is transferred, combined and/or separated at different locations with any configuration of sensor inputs. This ensures that consistency of estimates is maintained and other benefits such as real-time probabilistic reconciliation can be implemented. A method for combining material of different mass and chemical compositions is also developed to enable accurate and efficient operation of the system. Representative experiments on a small-scale and a larger field trial which mimic the mining processes of excavation, haul and unload to ROM Stockpile will be used to verify the approach.

Sep 26, 2011

By A Trench, S Ulrich, S Hagemann

A synthesis of reported All-In Sustaining Costs (AISC) for 57 Australian gold mines in the period 2014–2016 reveals for the first time the clear influence of grade upon cost performance, most evident in gold-only underground mines. Past syntheses of costs on a single quarter basis have viewed grade as potentially subordinate to other factors such as production scale, mine geometry, mineralisation style and a combination of other mining-related costs. Better understanding of the grade to cost relationship on both an individual mine and whole-of-portfolio portfolio basis is needed. Insight into the roles and trade-offs between other cost-determining factors will aid the future sustainability of the gold mining sector in Australia and assist in targeting prospects for future resource growth and development. While the overall trend is toward higher-grade mines displaying lower costs and vice versa, the grade to cost functions appear radically different between mines based on time-series data. The median cost of Australian gold production in the final quarter of 2016 was A$1081/oz. The threshold for lowest cost quartile production was A$965/oz. Underground production now dominates Australian gold output – with 71 per cent of ounces originating from operations that are either entirely underground or hybrid pit/underground mines. Scale economies are evident, with smaller mines predominately among the higher cost producers. For mines of equal grade, open pit mines are lower cost than underground operations. Reserves are modest, with a median mine life for underground operations of 4.7 years based on current production rates. Reserve additions at mines are likely constrained not only by the finite nature of mineralisation at each mine but also by the geometrical difficulty of accessing suitable drilling locations to test for reserve extensions.CITATION:Ulrich, S, Trench, A and Hagemann, S, 2017. Towards an understanding of production costs at Australia’s underground gold mines, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 241–250 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By D Drinkwater

In 2009, Peter Munro and Peter Tilyard examined the “human capital” in the mineral processing sector in a paper entitled Back to the Future (Munro and Tilyard, 2009). One of their major concerns was a general decline in technical skills and process knowledge, exacerbated by lack of appreciation of the impact this can have on process plant performance and, ultimately, profitability or sustainability of the industry. There are many reasons for this decline, not least of which are the work schedules of today’s metallurgists which have a very different balance between technical and non-technical responsibility than those in the past. However, a shift towards a more technical focus has potential to deliver a range of benefits for industry at large and for the individuals in it This paper discusses some options for development of core metallurgical and process engineering skills that can be used by graduates, employers and training providers.Key skills are identified and mapped against available opportunities for development, such as existing graduate programs, on-the job training and external courses. The authors also review a number of past and present high-quality graduate development programs, including the graduate development program in place at Mount Isa Mines in the 1980s and the Anglo Platinum Graduate Development Program (AGDP) currently operating in South Africa.

Aug 8, 2011

By A K. Ghosh

"Inrush of water is always an issue, especially for mines located in heavy rainfall areas. Nowadays, mining companies and research institutes have developed many advanced technologies for study and analysis of hydrological processes. In this paper, an advanced method is introduced, which uses the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) data in the Geographical Information System (GIS) platform to simulate the stream distributions around two specific mines: Super Pit and Griffin coalmine in Western Australia. The impact of this approach is important because it reduces the time and economic cost by creating a high spatial resolution hydrological map in the specific areas. The study identifies the flow path of the run-off water, which helps in adopting a suitable water management plan surrounding the case study mines. The results match with the ground reality. Based on the results, the stream structure around Griffin coalmine is more complicated than that of Super Pit. The bifurcation ratio and drainage density are computed to estimate the subsoil permeability characteristics of the two mines. Recommendations have been put forward to prevent and reduce the potential risks of water accumulation around the open pit mines.Citation:Ghosh, A K, 2016. Application of Shuttle Radar Topography Mission Data in Hydrological Analyses of Super Pit and Griffin Coal Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 162–169 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By L Rachmad

Freeport IndonesiaÆs Deep Ore Zone (DOZ) mine is the new underground block caving mine within the East Ertsberg Skarn System (EESS) deposit which started production in mid-2000. The DOZ will produce 25 000 tpd using mechanised block cave mining method and will be the fourth underground mine opened within the EESS deposit. Evaluations were made on former block caving mines at PT Freeport Indonesia (IOZ, GBT Area I and II) in order to design a more appropriate support system. As a permanent support, the thread bar bolt support system is widely used in the DOZ mine. The advantages of this system are ease of operation, quality control and high bond strength. The main problem of this system is the curing time of about 28 days to achieve maximum strength, necessitating the installation of a temporary support for its implementation. In this instance, the system was inefficient in operation and studies were required to find an alternative grouting system. This paper examines the evaluation of thread bar bolt support system and compares the performance of two types of grouting (resin cartridge and cement cartridge) with cement grouting performance. The evaluation is conducted with a pull out test. The advantages and disadvantages for each grouting method, comparison of cost estimation and grouting application in mine scale are presented in this paper.

Jan 1, 2002

By C Augustin, M Hahn, K Nienhaus

Operators of mining machinery like haul trucks or excavators have very limited information about the exact distance to other equipment as well as to the natural boundaries like berms, walls and structures such as crushers. The industry is seeking solutions to provide safety and positioning. The authors have developed a solution approach which is being used in several installations. This solution consists of three parts: first robust and compact two-dimensional (2D) radar scanners that provide range and angular information of the environment especially under difficult conditions like dust, rain, snow and fog; second an intelligent data processing framework flexible enough to adopt to different machines and operation modes like speed, inclination, visibility, tire friction, GPS position, orientation and acceleration; and third a high quality and easy to use interface giving highly condensed data to the operator, not blinding the operator at night and being sunlight readable. The truth of present proximity detection sensors is that they not only have a high false alarm rate but furthermore cover only a fraction of the possible scenarios. This makes them unsuitable for stand-alone collision avoidance systems. On the other side, mine dispatch systems only deliver database and GPS information, but no information regarding the real environment. The indurad company and its Australian partner CTS (http://www.cts.com.au) addressed these aspects by developing smart productivity enhancement driver assistance tools like lane and crusher dumping assistance.An innovative driver assistance tool developed in cooperation with the coal shearer manufacturer Eickhoff and the RWTH Aachen University has been awarded with the annual research award of its customer RAG, being the largest German hard coal producer, as well as with the bauma Innovation Award in 2010.

Sep 26, 2011

By V Chamberlain, M Appeah Owusu, M Aniawu-Asumakah, A Anyimadu, R Peattie

This is an integrated geology and plant improvement study arising from the heterogeneity seen in mineralogy and gold association at the Obuasi goldmine in Ghana. This heterogeneity comes from the two ore types mined, the one being a sulphide ore, mainly composed of gold-bearing arsenopyrites. This gold is refractory and exhibits a strong relationship between gold and As. The other is quartz veins, that are high grade and free milling. The installed circuit consists of comminution – Gravity -Flotation – BIOX – Leaching and Adsorption processes. The opportunity tested involved improved mass pull - related flotation recovery of Au in the Sulphide stream; while balancing the need for a minimum Sulphide grade for the Bio-oxidation process, occasioned by the removal of 25 to 30 % of the (quartz) stream through preconcentration by Ore sorting. The current circuit is then utilized for the sulphide route, while a smaller grind-gravity circuit is utilised for the quartz stream in a relatively inexpensive way, followed by a common leaching and adsorption circuit. Added advantages of the strategy includes faster recovery of gold from the quartz stream, with less consumption of reagents from saving on flotation and BIOX reagents for this stream. Screening and Ore sorting was successfully tested with laser technology, achieving over 98% separation of quarts (containing up to 40% of the gold). The plant schedule of Ore, the suggested circuit design for the Ore sorting, the results obtained from the different flotation regimes, as well as consequent financial modelling have been presented and discussed in this paper. This illustrates the opportunity that arises out of a detailed analysis of material versus installed circuits, even if the gains in pre-concentration do not necessarily involve rejection of gangue material. An added opportunity for future investigation, briefly discussed but not tested in this paper, would be to maintain current mass pulls but with increase in throughput (by the space created by the sorted material). This will of course require the mining ability. It could also add LOM value by altering the cut-off grade.

Nov 10, 2020

By R Halatchev

Production scheduling optimisation in open pit gold mining is a complex problem as it is driven by economic criteria reflecting particular economic interests of the concerned parties in the mining business. The contemporary organisational forms of mining, such as owner-operator and contract mining, are a good example of this relationship. These forms are complex and contradictory by nature as the contractor aims to get more waste at the beginning of mine exploitation in order to make more profit with favourable discounting effect over time, while the owner-operator aims to mine less waste at the beginning, which is a precondition for implementation of the mine planning principle of waste deferment and maximising the net present value (NPV) by accounting for the time value of money. Both forms are vital for the successful performance of the Australian mining industry as their competition is a powerful driving force of the market-oriented national economy.The present paper offers a new vision about the economic effectiveness of contract and owner-operator forms in surface gold mining through the prism of a novel production scheduling approach with a multistage stabilisation of the mining rate that implements the mine-to-market concept of modelling. The comparison of the forms is demonstrated with a case study that reveals the specific features of the new scheduling approach and the benefits of its implementation in the exploitation of Australian gold resources.CITATION:Halatchev, R, 2013. Owner-operator versus contractor production scheduling - a vision for the effective exploitation of Australian gold resources by surface mining, in Proceedings World Gold 2013 , pp 255-266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By A Purton, C Taylor, E Conroy

The spatial modelling of geometallurgical domains is an important step in the characterisation of an ore deposit allowing for the quantification of various rock types, their differing rock properties and the overall value of a project. The traditional approach to modelling such features is through the use of deterministic models, where a single estimate of the extents and structure of the ore deposit is mapped out by geologists based on available data and their interpretation of the geological processes. Any uncertainty in the layout of different domains is not accounted for and heterogeneities of chemical and physical properties of the orebody are likely underestimated. Spatial machine learning techniques can be used to derive geometallurgical categories, or classes, from multiscale, multiresolution and high dimensional measured rock properties. Subsequently, geostatistical simulations of these classes can be applied to obtain multiple equiprobable realisations that define the layout of the geometallurgical classes at unknown locations between boreholes, or domains. In-turn these realisations can be used quantify the uncertainties in the location of boundaries between different domains. The development of a workflow for defining geometallurgical domains and later geostatistically simulating them across the Orebody H; a complex stratabound Bedded Iron Ore deposit located in Western Australia’s Pilbara region is demonstrated. This could be used to identify zones of high uncertainty where collection of additional data might help mitigate or minimise risks and in turn improve forecast production performances.

Mar 22, 2022

Process mineralogy is an inter-discipline in the fields of mineralogy and mineral processing. As a predicting and trouble-shooting tool, process mineralogy helps address all mineralogical issues and problems related to mineral processing. It provides useful information on process design and optimisation, flow sheet development and cost reduction. As more and more complex and refractory ores are being discovered and processed, it is believed that process mineralogy will gain more attention and play a more important role in process design and optimisation. This paper will first discuss the scope of process mineralogy and mineralogical factors that may affect mineral processing of various ores, and then focuses on the application of process mineralogy in process design and optimisation through case studies.

Jan 1, 2008

By C Rizos

Many of the ‘new paradigms in mining’ and notions of ‘sustainable mining’ have at their core the requirement for reliable, continuous centimetre-level positioning accuracy to enable increased automation of mining operations. The deployment of precision systems for navigating, controlling and monitoring machinery such as drills, dozers, draglines and shovels with real time position information increase their operational efficiency, and reduce the need for humans to be exposed to hazardous conditions. The Global Positioning System (GPS) is the best known, and only currently fully operational, Global Navigation Satellite System (GNSS) providing positioning capability anywhere in the globe, on a continuous 24/7 basis, with accuracies ranging from the dekametre-level to the sub-centimetre-level depending on hardware and operational configuration. Despite this versatility, GNSS cannot satisfy the high accuracy positioning requirements for many applications in mine surveying, and mine machine guidance and control. The reason is that increasingly open cut mines are getting deeper, resulting in a reduction of the ‘sky-view’ necessary for GNSS systems to operate satisfactorily. Yet, to date there have been no viable alternatives to GNSS that can be deployed in mine environments that can meet the challenging requirements in open cut mines.Locata Corporation, a Canberra-based company, has invented a terrestrial high accuracy positioning system known as ‘Locata’ that can augment GNSS with extra terrestrial signals to permit cm-level positioning accuracy even when there are insufficient GNSS satellite signals for reliable positioning and navigation. Locata relies on a network of synchronised ground-based transceivers that transmit positioning signals that can be tracked by suitably equipped user receivers. Hence Locata can be considered a new type of ‘local constellation’, able to provide high accuracy positioning coverage where GNSS fails. This paper introduces some of the technical aspects of this Australian technology and describes tests conducted by Leica Geosystems over the last few years at Newmont Boddington Gold in Western Australia. A recent news announcement by Leica Geosystems (12 January 2011) has confirmed that their new mine management system will have combined GNSS + Locata positioning capability – the first commercial product that integrates GNSS and Locata capabilities into a single high accuracy and high availability navigation device for open cut mine machine automation applications.

Nov 22, 2011

By S J. Loach

F-Series reconciliations are formal comparisons of estimates and measurements of ore quantity and quality made at pre-determined points along the mining value chain. F1 is the ratio of ‘Depleted Grade Control Ore/Depleted Long-term Model Ore’ and validates the models upon which Resource and Reserve statements are based. F2 is the ratio of ‘Produced Tonnes and Grade/Depleted Grade Control Ore (-) Changes in Pre-Crusher Stockpiles’ and validates that the ore tonnes and grade delineated in the pit are being accurately extracted and correctly delivered to the processing plant. These factors provide important corporate assurance for a mining company by providing quantitative feedback on model-predicted tonnes and block grade estimates. Since 2009, BHPs Western Australian Iron Ore F-Series reconciliations have been calculated in a single, centralised sequel-server database. This software routinely collates data regarding mineral resource block model depletions, grade control model depletions, pre-crusher stockpile inventories and production tonnes and grade measurements and then calculates F-Series factors for both tonnes and product quality. This paper will present case studies where reconciliation factors were used to identify improvement opportunities leading to projects that improved our models and subsequent forecasts of production tonnes and quality. In addition, it will show how reconciliation factors are tools that monitor control during periods of rapid change and provide feedback on the effectiveness of improvement projects.

Sep 18, 2023

By Pinczewski WV, Nowak LP, Tanzil WBU, Jenkins DR, McCarthy MJ

An experimental and theoretical study has been made of the drainage behaviour of two-dimensional packed beds drained from an outlet in the sidewall of the bed in order to identify the fundamental me- chanisms involved. Under these conditions a grad- ient develops in the air-liquid interface in the direction of flow with the interface tilting towards the outlet. This results in a significant volume of liquid being retained in the packing on completion of draining when the interface first reaches the bed outlet. Residual liquid volume and the shape of the air-liquid interface as a function of time were det- ermined experimentally in a two-dimensional packed bed where the packing consisted of glass spheres ranging in size from 0.6 to 10 mm dia. and the bed was drained at superficial liquid velocities rang- ing from 0.007 to 0.32cm/s. The test liquids used were water, glycerine/water solutions and kerosene resulting in a viscosity range of 1 to 10 mPa.s and a surface tension range of 0.0243 to 0.072 N/m. Assuming laminar flow within the bed, a compu- tational model was developed to predict both the liquid residual ratio and the temporal evolution of the drainage profile within the bed. The computed results were in good agreement with the experimental data over the entire range of conditions invest- igated. the computational model was used to estimate the relative importance of the effects of changes in hearth conditions on residual slag volume for typ- ical blast furnace operating conditions. On the basis of the computed results it is concluded that coke quality is a major parameter affecting hearth drainage performance.

Jan 1, 1981

By F Ramos

Conventional techniques for resource estimation generally involve the laborious analysis of variograms and the specification of parameters for covariance functions. In large deposits, construction of resource models and their update require significant amount of manual work, expert knowledge and time. In this paper we take a machine learning view to the problem of resource estimation. This is a non-parametric Bayesian method, leading to automatic parameter estimation (learning). Through Bayesian learning, the parameters of the model can be obtained by optimising a quantity known as the marginal likelihood. The main advantage of this approach over conventional maximum likelihood estimators is that the objective function incorporates the OccamÆs razor principle. This allows the comparison of different statistical models û for example, models designed with different covariance functions û and naturally penalises complexity, thus avoiding overfitting. Our technique presents significant flexibility for the definition of mean and covariance functions and permits the usage of more sophisticated models.The second contribution of this work is the formulation of a data fusion mechanism that continuously updates the resource model. As mining progresses, more information becomes available. For example, the hardness of the rocks can be measured while drilling blast holes, grades of ore and contaminants are obtained from cone logging. This information is in general available at a finer spatial resolution but can be more uncertain. The data fusion mechanism can seamlessly estimate the uncertainties of the different types of information and fuse them as new measurements are acquired. This procedure can significantly improve the quality of the resource model, defining new grounds for stochastic mine planning. We demonstrate the effectiveness of our approach in estimating iron ore deposits by integrating information about different grades.

Sep 26, 2011

By B L. Sainsbury, M F. Lee, A Penney

For most practical rock engineering purposes, stress versus strength conditions around underground openings for which rock masses fail and their various modes of failure, are reasonably well-understood and predictable. Some rock masses and particular rock types fail slowly and relatively quietly. However, others can fail rapidly, violently and maybe with the ejection of significant broken rock. In some countries and in some mines, the latter style of violent fracturing and failure of the rock mass is referred to as ‘strain bursting’. It can be alarming and extremely hazardous to nearby miners and machines. For such situations, the design and installation of appropriate ground support, to provide a safe work place, can be challenging. At any particular mine site, it’s often generally understood which local rock masses (rock types) are prone to strain bursting. Competent and strong siliceous rocks and some massive sulphides are often the main offenders. While some neighbouring, equally-competent and strong rocks might also fail, they do so more quietly and without ejection. To understand this contrast, a better understanding of the fracturing process is required other than simple and standard strength versus stress considerations. Suites of standard intact rock properties from numerous Australian mines have been used to define and help understand different high-stress failure styles for component intact rock; especially those prone to violent fracturing (strain bursting). Simple considerations of micro-fracturing (defects in the intact material), plus the available energy at failure versus the energy consumed during fracturing, distinguishes between over-stressed and competent rock types that fracture violently and those that don’t. CITATION:Lee, M F, Penney, A and Sainsbury, B L, 2018. Proneness of competent over-stressed intact rock to violent fracturing, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 170–184 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By M Andrew, H Reynolds, R Mills

As the global mining industry continues to grapple with ‘black swans’ (high consequence / low frequency events) for health, safety and environmental losses, the focus is shifting from risk assessment of these events to risk management using selected purposeful controls that reduce the risk.Fundamental to critical control management (CCM) is a soundly based rationale for selecting the right controls for each and every risk. The approach should be based on a thorough understanding of the dynamics of the event: What causes it? How frequently will it occur? How likely is the consequence to be realised? This is typically done through a bowtie and methodical numerical risk analysis. Core to this step, then, is the structure and content of the bowtie; specifically, the analytic architecture that is used to construct the bowtie. Different architectures yield different constructions, and bowties are no different.Although bowties for operational health and safety (OHS) hazards appear to have a common architecture, they are not generic. It is important to stress that they contain site specific information, are prepared by site based operational teams, and vary from site to site to reflect each site’s operational conditions. They are often a product of the knowledge and understanding of the operational teams involved, may be prone to human error, and potentially miss latent hazards that may have been embedded early in the planning, design or construction phase of a mine or facility, or within the mining equipment. Overcoming these deficiencies through constant re-evaluation of the risks, and challenging the content on the bowtie will help to minimise the chance that something will be missed.This paper will cover key themes in bowtie architecture, introduce the concept of barrier models for high consequence event (HCE) bowties and present a relevant case study to illustrate the issues that determine quality in bowtie construction and critical control (barrier) selection and management.CITATION:Mills, R, Andrew, M and Reynolds, H, 2016. Can we stop a black swan breeding? Advances in bowties and critical control management, in Proceedings International Mine Management Conference, pp 105-114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

Rather like the mythical "Economic Man" "an employer" in this context must necessarily be an abstraction, and the views possessed by such an abstraction, a composite of many views known to have been expressed. Not even the complex Conciliation and Arbitration legislation in this country provides any helpful specifications, except in one peculiar particular. The Australian Conciliation and Arbitration Act provides an almost totally tautological definition, except in that one oddity referred to above. It is this : "An employer means any employer in any industry, and includes any person who is usually an employer in an industry, and also includes a Club." No doubt there is some perfectly justifiable reason for such specific and unique particularity in an otherwise meaning- less definition. That need not trouble us in this exercise.

Jan 1, 1982

By Connell JE

The Worthing Mine near Hallett Cove. 20 km southwest of the cite of Adelaide, belongs to Aus- tralia's first mining era, which took place in South Australia between 1841 and 1851 (Figure 1). Oper- ations began in 1849 only six years after the com- mencement of metal mining in Australia at Glen Osmond. Although not as historically significant as Glen Osmond (1841), or the much larger copper mines of Kapunda (1844) or Burra (1845) its importance lies with its Cornish enginehouse and chimney. The Worthing enginehouse, built in 1851-1852 is the oldest remaining in Australia and certainly the most significant relic of Australia's first mining era. Six other stone enginehouses were built during that period: at Kapunda in 1848 and 1850: at Burra in 1849, 1850 and 1851; and at Tungkillo in 1849. All of these houses have long since dis- appeared although the foundations of one (Kapunda, 1850) still remain. The significance of the Worthing site is enhanced by its magnificant environmental setting in the bare, steep valley of Field River. Currently (1986) the Worthing Mine is the only site within the City of Marion which is on the Register of State Heritage Items. The site is also included in the Classified List of the National Trust of South Australia and on the Register of the National Estate.

Jan 1, 1987

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

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

Oct 29, 2012