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By R Domotor

Brisbane’s Airport Link is Australia’s largest road infrastructure project, worth a total value of A$4.8 billion. The project is using surface and underground blasting to excavate hard volcanic rock, Brisbane Tuff. This paper tells the story of the most challenging and difficult blast of the whole project: the removal of a remnant pillar of rock (approximately 2250 m3) next to a major arterial road and within 100 m of existing infrastructure including a number of heritage listed buildings, residences and privately owned sensitive receivers. The pillar consisted of a hard rock wall (Brisbane Tuff) between 2 m and 6 m thick, 15 m high and 35 m wide; with in situ precast concrete piles embedded within 1 m of the boundary of the pillar. Orica Australia Pty Limited was contracted by Thiess John Holland, to perform the work in this area, including design, modelling, drilling and loading of the explosives, as well as blast clearance and shotfiring. Access to the area was limited so all explosives and equipment, including the 20 t drill rig, had to be lifted in and out by crane. Due to the nature of the blast, with infrastructure 5 m directly in front of the 15 m high face, there was only ever going to be one chance to get this blast right. This was an extremely complex blast which required the use of a number of different types of packaged explosives, as well as special timing techniques only made possible by using electronic initiating systems. This type of blast is high risk, and is more typical of a building demolition in the urban environment. The blast was fired on the 25 September 2010, and was highly successful. The environmental results for vibration and overpressure were well under the imposed limits, and the embedded concrete piles remained undamaged.

Nov 8, 2011

By R M. Arellano, D M. W Harney, M Makhuvha

Mineral resource and ore reserve estimates are founded on two sources of data: tonnage and grade. The tonnage is a product of volume and density; both of which are estimates. Density impacts numerous operational factors, which include, but are not limited to, mine design, mine planning, equipment selection and operational performance. Hence, density is a significant parameter and its determination requires similar care as the measurement of grade. Selecting an appropriate method to determine density, and ensuring its rigorous application, thus reduces risk and can improve operational performance, which in turn increases profit margin.Different Anglo American sites use a variety of practices and protocols to determine density, which is highly dependent on the physical characteristics of the orebody, local conditions and historical practices. Also, individual sites sometimes execute the same method in a slightly different way, which may also affect the outcome of the measurements. In order to gain a better understanding of how density is determined at Anglo American projects and operations, a review of these techniques was undertaken. The objective of the study was to identify and share good practices across the company, as well as to look for improvement opportunities, where applicable. Ten different methods of measuring density, applied to nine different commodities, were identified and described. An additional technique was recently developed by Anglo American Technical Solutions. The core pycnometer is a large gas displacement pycnometer capable of measuring density at high accuracy on full pieces of intact core.This paper provides an overview of methods used to determine density within the Anglo American Group, including quality control and quality assurance aspects. It is not the purpose of this paper to identify a preferred method, but to highlight the importance of choosing the best suited practice for a project or mine site. In addition, a case study comparing two different density determination methods applied to the same rock samples from the Los Bronces Copper mine was undertaken and the results of that study are presented here.Selecting the most appropriate method to determine density and comparing results from two or more techniques against each other, together with other suitable quality control procedures, is considered to be of utmost importance for all mining operations and exploration projects.CITATION:Makhuvha, M, Arellano, R M and Harney, D M W, 2014. Determination of bulk density in Anglo American plc, methods and impacts, with a case study from Los Bronces Mine, in Proceedings Ninth International Mining Geology Conference 2014 , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By A Atkins

Six recent case studies were selected based on the eight main causes of mine disasters (Table 1; Quinlan, 2014) and where credible information sources, such as Royal Commission Reports, Coronial Investigations and textbooks, were available. The six case studies are listed below. Details are available via this link or the conference PowerPoint accompanying this paper. 1. Beaconsfield, Tasmania – 2006 Fall of Ground/Seismic Event (Chandler, 2009; Melick, 2007; Wright, 2012). 2. Bingham Canyon, USA – 2013 Manefay Slide (Ross, 2017). 3. Bronzewing, WA – 2000 Hydraulic Fill Inrush (Hope, 2002). 4. Brumadinho and Samarco, Brazil – 2015 and 2019 Tailings Storage Facility (TSF) failures (Bowker, 2019; Darlington et al, 2019; Demajorovic, Lopes and Santiago, 2019; Morgenstern, 2016). 5. Northparkes, NSW – 1999 Cave Air-blast (Bailey, 2003; Hebblewhite, 2003). 6. Pike River, NZ – 2010 Methane Gas Explosion (Macfie, 2013; Panckhurst, Bell and Henry, 2012.

May 5, 2022

By S Maritsa, E K. Chiwandika, S M. Masuka

The iron and steel industry is experiencing an increase in the use of iron and steel commodities within societies, decarbonisation pressures, depletion of high iron ore grades and high energy consumption. This necessitates scrap metal recycling, low-grade ore utilisation using the induction or electric arc furnace to achieve the global target of net zero CO2 emission. The available highquality scrap metal cannot sustain the steel industry but the world has unused hematite-goethite ores. It is the aim of this research that this resource be utilised using the induction furnace to sustain the steel industry in an environmentally friendly manner. Indurated pellets prepared from the hematite-goethite ore, 5 wt per cent limestone and 5 wt per cent coal addition were smelted in the induction furnace at 1350 ± 50°C with 25 mins holding time. The effects of basicity and carbon content were also investigated to optimise the smelting parameters. The results showed that the careful control of the basicity, and iron-to-carbon ratio maximised total metal recovery. The optimal basicity ratio was determined to be 1.3 and a carbon to iron ratio of 1.4 achieved a total metal recovery of 73 per cent. The metal recovery was closely related to the estimated slag melting temperature. The basicity ratio of 1.3 achieved the lowest slag melting temperature estimated to be around 1380°C based on the CaO-SiO2-Al2O3 phase diagram. The recovered metal had a comparable chemical composition and microstructure to that products from an ITmk3 furnace.

Jun 19, 2024

By A B. Jahed, Ö Aydan, T Ito

In this study, the authors compiled some case history data and present some typical examples of rock slope stability issues in Afghanistan with a special emphasis on Kandahar region and categorise rock slope failures according to the principles of modern rock slope engineering. The slopes considered involve rock-cut, natural rock slopes mainly. The effect of structural geology and discontinuous nature of rock mass on both slope-cuts and natural rock slopes is taken into account and some preliminary assessments on the stable and unstable rock slopes are presented. Furthermore, the seismic effect on their stability is also considered. It is also pointed out that similar issues could be observed in open pit mines, which may be exploited in years to come.

Nov 29, 2022

Risk management has become an essential tool for mining companies to ensure their projects are well-managed and profit expectations are achieved. Risk management has also become a mandatory corporate governance requirement in Australia for publicly listed companies and equally important to attract investors. This paper provides a brief overview of the essential tools needed to implement a practical risk management framework to comply with the internationally recognised ISO 31000:2009 risk management-principles and guidelines from the perspective of small or soon to be producing mining companies. To?successfully?deal with the unknown and to manage the opportunities and risks involved with a mining project requires a clear understanding of the basic risk management principles. These include how to develop a project risk register, how to develop a project risk treatment plan and how to manage and monitor project risks to take full advantage of the opportunities presented.The first step is to identify and fully appreciate the risks that face a mining project. There are many risk identification methods that can be used including checklists, brainstorming and hazard and operability (HAZOP) studies. These often lead to a telephone book full of risks which are near to impossible to manage. A risk library specifically designed?for mining?projects containing no more than 100 risks will cover the major showstoppers, is practical and can be readily implemented and successfully managed.A risk framework also needs to be established which is compatible with the companyÆs structure and objectives. Once each risk has been assessed in regard to consequence and likelihood and the risk control systems are in place they need to be assigned to the responsible manager. The extreme or high risks will require a risk treatment plan to be developed. Risks will change during the life cycle of a mining project. Hence, a reliable monitoring system is also required for compliance.CITATION:Jones, J A, 2012. Mine project risk management, in Proceedings Project Evaluation 2012 , pp 117-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By E Bouchard March, F Lavoie, B Legare, K Bourassa

Quebec Iron Ore (QIO), a subsidiary of Champion Iron Limited (Champion), completed the restart of the Bloom Lake iron ore mine located in the heart of the Labrador Trough region of Northern Quebec, Canada in February 2018. Prior to its restart, the concentrator flow sheet underwent major upgrades which brought the iron recovery to the highest of all Labrador Trough operations. After two profitable years of production, QIO, supported by Soutex, started to look at technologies to improve its current performance and integrate into its expansion project flow sheet. From the lessons learned while optimising Phase 1, the addition of a scavenger-cleaner processing stage was identified as an improvement opportunity to increase recovery, produce a higher-grade product, and further improve the stability of concentrate quality. In 2019, the NI-43101 feasibility study for the Phase 2 expansion, aiming to double the production of high-grade iron ore concentrate, was published. Based on the metallurgical test work, the hydraulic classifier was selected to perform the scavenger-cleaning duty for its well-established performance and known behaviour at the cleaning step in the Phase 1 plant. To validate laboratory results, a pilot scavenger-cleaning hydraulic classifier was installed in Phase 1. Although the hydraulic classifier was selected for the feasibility study, metallurgical test work performed with the REFLUX® classifier showed interesting potential. It was thus decided to also install a pilot RC300 Reflux classifier at the scavenger-cleaning stage in Phase 1. Despite their apparent great similarities, the metallurgical performance was significantly different, and many dozens of sampling campaigns highlighted the different performance of both pieces of equipment considering the feed material particle size. This article presents the pilot plant results in terms of recovery, selectivity and stability for both the Reflux classifier and the hydraulic classifier operated in a scavenger-cleaner stage at the Bloom Lake iron ore concentrator.

Nov 8, 2021

By T BoBo, D La Rosa, P Cameron

Efficient pre-concentration using natural and induced deportment starts with effective blast design. Leveraging these characteristics using Size-Based Grade Engineering® techniques requires detailed understanding and measurement of the particle size distribution (PSD) of the Run of Mine (ROM) ore. In turn, blasts must be designed to optimise fragmentation for the pre-concentration method. To be successful, fragmentation outcomes must be predicted and measured as part of the blast design process to account for the response ranking of the rock mass. The upgrade achieved using Size-Based Grade Engineering® methodologies will rely on the proportion of feed that reports to the screen undersize, so particle size distribution of the feed stock is of paramount importance if the potential benefits are to be achieved and maintained. Measuring actual fragmentation in the ROM ore and comparing with predictions allows the modification of subsequent blast designs to optimise fragmentation for pre-concentration scenarios. Automating this process can deliver significant increases in productivity and mine site profits. This paper discusses the importance fragmentation plays in Size-Based Grade Engineering® and explores technologies and methodologies used to measure it, consistently ensuring the best outcomes.

Nov 10, 2020

By D J. Thobaven

Project financing challenges caused by declining commodity prices have heightened the need to improve project metrics such as minimising capital payback and maximising net present value (NPV). Khnaiguiyah Mining Company (KMC) recognised the need to improve early cash flows at their Khnaiguiyah zinc-copper project after initial studies showed the project could not provide the desired financial outcomes necessary to compete for investment dollars in the current market.A significant improvement to the project cash flow in early years was realised through simultaneous optimisation of cut-off grade, mining sequence and strategic stockpiling. This improvement was achieved by accelerating mining in the pits, stockpiling lower value material and feeding higher value material directly to the plant. The schedule required higher mining and stockpile capacities than the sequential mine plan although minimal change occurred in the definition of ore and waste as measured by tonnes and grade. The practicality of the strategic schedule was demonstrated by implementation in the production plan with excellent conformance.CITATION:Thobaven, D J, 2014. An application of simultaneous optimisation – improving the payback period of a zinc-copper open cut project, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014 , pp 137–144 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By A Hughes, J Agius, T Ferguson, A Parbhakar-Fox, D Lester, L M. Jackson

Management of historic tailings is a major challenge facing the mining industry and its regulators. However, through improved mineralogical and chemical characterisation of such materials the opportunity to develop better rehabilitation strategies arises. Microanalytical techniques including microscopy, mineral liberation analysis and laser ablation inductively coupled plasma mass spectrometry (ICPMS) allow for improved tailings characterisation – but the challenge posed by these techniques is how to use them effectively. Additionally, data sets collected by such techniques must be properly integrated, only then can they assist in the identification of the most appropriate rehabilitation strategies. A study conducted at the Old Tailings Dam (OTD) located at the Savage River Mine, Tasmania allowed for the integrated use of several microanalytical techniques to help evaluate the benefits of a shallow water cover as a potential rehabilitation strategy. Samples (n = 144) from 14 trenches and 11 boring cores (2 m maximum depth) were collected across the OTD. These were subjected to routine acid-base accounting, with a subset subjected to detailed mineralogy using a modified sulfide alteration index (SAI), X-ray diffractometry and mineral liberation analysis (MLA). In addition, representative samples (n = 6) from across the OTD were subjected to laser-ablation ICPMS to characterise the pyrite chemistry. Our results showed that tailings in the northern area submerged under a natural water cover were relatively unoxidised from approximately 1 m depth, with SAI values of 1 to 2. Tailings from the subaerial southern portion were extensively oxidised to approximately 35 cm depth (SAI = maximum 5.8), with fresher materials observed underneath (SAI = 5 to 5.8). Pyrite from across the OTD is enriched in Co, Cu and Ni. Through the integrated application of microanalytical tools, we determined that establishing a water cover of at least 1.5 m depth across the OTD is a suitable rehabilitation option for this historic site. However, consideration for the reprocessing of these tailings to extract Co should be further investigated.CITATION:Jackson, L M, Parbhakar-Fox, A, Hughes, A, Agius, J, Ferguson, T and Lester, D, 2015. Microanalytical evaluations of the savage river old tailings dam, north-?west Tasmania, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 111–124 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By D La Rosa, D Bennett

"Exploration drill core provides for a number of standard measurements essential for determining the viability of a new mine or the extension of an existing one. Rock lithology and alteration can be visually determined and grade measured from the half core. Geotechnical parameters such as rock strength and structure can also be measured. Using suitable proxies, these metrics can then be used to estimate run-of-mine (ROM) particle size. In combination with comminution test results, these can subsequently be used to design comminution circuit configurations and estimate their performance.The Frieda River Project drill core for the large Horse-Ivaal-Trukai copper-gold porphyry deposit was unusual due to a late stage gypsum-anhydrite stockwork event that overprinted much of the deposit. Above the base of the oxidised zone, which closely matches the water table, gypsum and anhydrite has been leached out, effectively removing the glue holding the rock mass together. As a result, much of the rock above this gypsum-anhydrite surface is fragmented and gravel-like in texture, while the material below this horizon is typically uniform and competent.Large volumes of the orebody above the gypsum-anhydrite surface are expected to need minimal or no blasting for efficient excavation. In addition, the fragmented nature of much of the material was expected to reduce comminution specific energy as it already appears as though it has been crushed. While this was expected to have positive impacts to the operation, the lack of standard geological logging methods available to accurately define the degree of in situ fragmentation led to difficulty in gaining certainty over the ROM product and grinding circuit feed size distributions.Using the extensive library of core photos for the project, a novel method using image analysis techniques to take both the intact core and gravel into account to predict ROM fragmentation was developed. In addition, existing point load test data was used to infer the strength of the rock and its impact on the blasting, crushing and grinding processes. The novel approach allowed development of ROM size distribution data and improved certainty in the results of comminution circuit designs.This paper describes the methodology undertaken in detail, and discusses the results obtained.CITATION:Bennett, D and La Rosa, D, 2016. The Frieda River Project – a Novel Approach to Analysing Exploration Drill Core: How Broken is Broken?, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 65–76 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By V Yadi

Geostatistics has been widely used for more than four decades as a powerful tool in ore resource/reserve estimates and grade control. This method has gradually replaced the conventional method such as polygon and cross-section for grade estimation by more mathematical techniques such as kriging. The advances in geostatistical understanding and the availability of appropriate software packages have given much more contribution in speed and high accuracy during production. However, in many cases, these techniques are sometime applied without support with a good thorough understanding of the geological controls on metal distribution. To produce the result close to actual, the geological control in interpretation and appropriate geostatistical task is a must. Geological logging was described in the core must be consistent with the level plan produced by commercial modelling software used as a guide for grade control during production. Experience gained through evaluation of the Central I deposit resulted that the most effective systems continue to be based on geostatistical methods of resource estimation. Computer applications modelling software packages are necessarily as the core of an efficient in undertaking these assignments. They contribute to make a valued to data management and are becoming increasingly effective during processing. The latter role is particularly important to check the actual versus estimated values where will significantly to improve personnel to have a confident with their knowledge combined with experience and complete their jobs satisfy.

Aug 22, 2011

By D R. Anstey

The growing demand for iron ore from Western Australia has led to an increased focus on the development of magnetite and lower grade iron ore deposits. The need to process and beneficiate the ore from these projects can result in the generation of significant quantities of iron ore tailings over the life of a project. Over the coming decades, the management of iron ore tailings will become a significant aspect of the mining landscape in Western Australia.The tailings generated from iron ore projects differ signifi cantly from other mineral tailings currently produced in Western Australia. Iron ore tailings are generated on a scale not matched by any other mineral process and can often contain asbestiform or potentially acid forming components. New iron ore projects are coming under increased environmental scrutiny because of their large scale operations and the sensitive environments in which they occur. This combination of factors creates some unique challenges for the management of tailings generated by iron ore mining in Western Australia.This paper presents the fi ndings of two studies conducted in recent years to overcome the challenges posed by iron ore tailings. The paper discusses the role of laboratory testing in the development of management strategies for asbestiform minerals in tailings. It also presents a numerical modelling approach for evaluating the rates of rise in the storage of magnetite tailings. The paper concludes by outlining how the findings of these studies can be applied to reduce tailings management costs, lower risks and improve environmental outcomes for the management of tailings from iron ore mining.

Jul 11, 2011

By B Jones, M Chappell

Installing ground support correctly is not an easy task, whether lack of operator training, poor ground conditions or underperforming equipment. Confirming the quality of installation can help with planning and remedial works and help to maintain a safe working environment. A 2?m bolt with 700?mm of encapsulation will pass a 10?t pull test (assuming ground conditions permit); however, it will not provide any data of the unencapsulated length and thus the ability to withstand corrosion. Complimentary testing in the form of non-destructive testing (NDT) can provide factual data that leads to the assessment of the quality of the encapsulation. By improving the quality of the encapsulation, the risk of corrosion is reduced, the ground support durability is improved and hence the asset life is enhanced.This paper presents a case study of a trial using the NDT system RokTel™. Installations of varying quality were installed and tested. The characteristics tested were corrosion, load and free length. These characteristics can be tested and assessed for cable bolts, thread bar bolts and split sets. The aim of this paper is to present NDT testing as a viable method for assessing installation quality and ongoing performance of the ground support.CITATION:Jones, B and Chappell, M, 2014. A non-destructive testing method for measuring bolt condition, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 307–314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By M Barker, H Li

The total number of tailings accidents has reduced from over 50/decade in the 1960s-1980s to less than 30/decade in the 2000s to 2010s. However, the rate of significant tailings dam failures has not been reduced. The significant tailings dam failures the mining industry experienced in the recent history include: Merriespruit, South Africa, 1994; Los Frails, Spain, 1998; Kolontár, Hungry, 2010; Mount Polley, Canada, 2014; and Samarco, Brazil, 2015. The conventional Factor of Safety approach itself may not be enough to further reduce the rate of significant tailings failures due to its limitations such as uncertainty. For example, the same factor of safety could have a vast range of annual probability of failure for different tailings dams, and insufficient consideration of failure consequence. This paper presents a risk based approach for design with the objective being to minimise tailings dam failures, especially those significant tailings failures with high consequence and low probability. This approach includes risk based design and risk management using bowtie tools. In the risk based design, quantitative analysis will be used to estimate the annual probability of failure and the tolerable failure criteria is linked to the consequence category. Bowtie analyses will be used to understand hazards and risks and identify and select independent controls that are effective in preventing and mitigating catastrophic failures. In this paper, examples of risk based design and bowtie analyses are presented and discussed. CITATION:Li, H and Barker, M, 2018. Risk-based approach for minimising tailings dam failures, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 397–414 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Y Durkheim, P Saunier, L Ameglio

"In the last decade Afitex developed the Draintube™ geocomposite, which provides simultaneous drainage and waterproofing functions. This new type of drain tubes planar geocomposites (DTPG) differs from other geocomposites as the drainage core is composed of multiple corrugated and perforated pipes instead of biaxial or triaxial nets. It is furthermore associated with needle-punch stitched layers of non-woven geotextiles, which act either as capillary mediums or as filters.In this paper, the structure of the Draintube™ drainage composite is presented along with its key properties and the drainage mechanism associated with its particular structure.The relevance of this kind of structure is then reviewed based on past and current laboratory bench evaluations and field installations for mining applications such as the covering of acid rock drainage (ARD) tailings for the Central Manitoba Mine (Canada) site-rehabilitation; and as a pregnant solution collection layer in heap leach pads.Some of the demonstrated critical advantages of Draintube™ in the mining industry are as follows: reduction of the thickness, hence lower volume of granular drain layers improvement of fluid and gas collection and reduction of the hydraulic load reduction of secondary collector network mechanical protection of the sealing membrane fast and economical installation of interlifts stability under extreme conditions (compression, temperature, pH) increased stability of entire covering system and reinforcement of protection of dykes filtration of the covered material customised drainage positive connection of the geocomposite to collector pipes enable leaks detection (using a conductive textile layer) with an electrical test.CITATION:Saunier, P, Ameglio, L and Durkheim, Y, 2015. Tubular drainage and lining geocomposite for mine tailings and heap leach pads, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 297–304 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 27, 2015

By D Kepert

It is the role of the exploration geologist to create wealth through the discovery, delineation and characterisation of economic mineralisation. This requires a critical depth of geological understanding.Unfortunately, the resource industry is well known for its cyclic nature. Many of the current generation of workers have only ever experienced the boom of the ‘super-cycle’ and are only just discovering the negative side to the business. For the case of the geologist and especially the exploration geologist, the magnitude of peaks and troughs are usually amplified and may become destructive to all parties. During the uptime a healthy stream of exploration good news becomes the staple diet of company releases, in particular those of junior companies attempting to bolster the share price. The geological knowledge and experience gained thus forms a significant and integral part of the value and therefore, future of a company. On the downturn it is often viewed that geologists are a luxury, an optional extra and a burden on the bottom line with companies entering a period of memory loss and myopia.Retention of geological knowledge however remains critical as projects, companies and cycles mature. Beyond exploration per se, this knowledge becomes both fundamental in de-risking and commercialising an asset (through development or divestment) and in positioning the company for cyclic or counter-cyclic opportunities.The growth and retention of this knowledge base is difficult to quantify in terms of direct value but becomes one of a successful resource companies greatest assets. At worst, its loss can lead to millions of investors’ funds wasted on missed opportunities, drilling, or poorly designed plant and mine.But the rocks are around for the longer haul and pay little notice to the vagaries of the scurrying of Man.This paper reflects on some of the authors own observations through 25 years of iron ore exploration, in why it is critical to always rigorously question the prevailing geological (mis)understanding and the technical and commercial benefits which that may bring, and looks forward to the future.CITATION:Kepert, D, 2015. Geology – the affirmative case, in Proceedings Iron Ore 2015, pp 285–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By J Zhou, L Crompton, K P. Galvin, J L. Sutherland, C P. Lowes, C Bezuidenhout, J Bijzet

Platinum Group Metal (PGM) bearing ores from the Upper Group 2 (UG2) reef often contain significant concentrations of chromite which can potentially be upgraded to produce a saleable product. A common approach is to implement gravity separation on the PGM flotation circuit tailings. However, where the particle size range of interest is broad and the lower size limit ultra-fine, the challenge is how to maximise the recovery at a saleable product grade without compromising throughput. This study was concerned with the performance of a REFLUX™ Classifier for beneficiation of a PGM bearing chromite ore and the benefits of size classification. The sample had a nominal top size of 0.5 mm and was processed over the complete size range and in two discrete size classes following classification at 106 µm. The primary goal was to produce a concentrate exceeding 40 wt. per cent Cr2O3, ideally approaching 42 wt. per cent Cr2O3, with minimal PGM losses above 106 µm. A major challenge was to process at the required solids throughput in a single stage with the feed pulp density constrained to a nominal upper limit of 30 wt. per cent solids. It was found that varying the controller density set point of the REFLUX™ Classifier produced strong control of the product grade. Products as high as 41.1 wt. per cent Cr2O3 were produced at 78.6 per cent recovery for the +106 µm material, while in the −106 µm portion the product grade was as high as 41.4 wt. per cent Cr2O3 at 83.2 per cent recovery. Processing the feed in discrete size classes enabled the volumetric feed and fluidisation rates to be optimised for a given application; hence, superior performance was achieved at the finer sizes. This work has demonstrated the value in considering feed preparation as well as technology selection in developing a robust process solution.

Aug 24, 2022

By C Parihar, R Garg, A Bhandari, S Bhandari

Blasting can impact the efficiency of entire downstream mining operation. Individual technology solutions for blasting have been available in the industry for many years but all of them only cater for certain aspects of blasting. Many of them are based on individual research and/or experiences. Some of the available software solutions are not suitable to be used in the field as that they need advanced skills or tools. Also, most do not take technology advancements like mobility, advanced data analytics, web solutions and integration into consideration. Hence, no technology platform is currently present in the industry that addresses all potential needs a blaster may need in an integrated manner.This paper presents an integrated solution that takes care of all aspects of blasting – design blasts according to mine plan; collect data after drilling has been carried out (as there is often difference in designed and actual drilled hole locations in the field); predict blast results in terms of fragmentation, flyrock, ground and air vibrations, wave front reinforcement and flyrock distance; and after assessment, allows changes in charging, delay timing and sequence. The technology solution is a secure, cloud-hosted, web-based software-as-a-service solution that can be accessed from anywhere. Also it has a mobile app, which is available for both Android and iPhone/iPad. The mobile app is also integrated with the web-based solution using application programming interface calls to the central data repository.Case studies for two limestone mines are presented where this solution is being used in its initial format. This software platform enabled analysis of the outcome from a previous blast pattern and then subsequently allowed optimisation of blasting operations based on historical data. Uses of this platform have resulted in improved key performance indicators in these two limestone mines. The mobile app as part of this platform enables extensive field blast data capture and analysis and also various predictions before a blast. Data collected include blast parameters, individual hole charging, initiation pattern, videos, photographs and vibration records for analysis/reporting. The key features of the solution are a blast designer, a detailed blast data collection/analysis and a series of environmental predictors. These predictors give blast results in terms of fragmentation, flyrock, ground and air vibrations and wave front reinforcement and take remedial steps before blasting to optimise and control adverse environmental impact. Many features, such as fragmentation predictor and mobility solution, are completely unique features that are not available elsewhere in such a field personnel-friendly manner.CITATION:Bhandari, S, Parihar, C, Garg, R and Bhandari, A, 2015. An integrated technology solution for optimised and environmentally-controlled blasts, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 393–400 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By I C. Carrasco, V G. Mirada, J F. D Domingo, F S. Leite

This paper investigates ore loss and dilution produced by rock movement in bench blasting. A total of four blasts, in which electronic detonators have been used, were monitored in Cobre Las Cruces Open Pit Mine (FQM Ltd) in Gerena (Sevilla, Spain). Rock motion has been obtained in 137 points of the free face and 6 points inside the block. Multiple liner regression has been applied to predict rock motion and estimate ore dilution as a function of hole coordinates, rock contacts, powder factor/hole, amount of explosive per blasthole, burden, spacing, hole length, stemming length, explosive energy, hole row, subdrilling, blast sequence, stiffness ratio, blasthole distance to free face, rock density and Young’s modulus. The model is statistically significant with a determination coefficient over 0.8. Rock motion measurements in 31 more points have been used to validate the model and to show a reduction in ore dilution.CITATION:Domingo, J F D, Leite, F S, Mirada, V G and Carrasco, I C, 2015. Dilution, ore grade and blast movement calculation model, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 71–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015