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By P Nichols, C te Kloot, A Harrison

Ernest Henry mine (EHM) is a sub-level caving operation located in north-west Queensland, Australia. Located below a previously mined open pit, the underground operation ramped up production to 6.8Mt/a in 2017. The EHM ore body dips at 45 degrees to the South and therefore requires each level to “step out” from the level above as seen in Figure 1. Within this step out zone it is important to both maximise recovery and allow for efficient operation of the underground workings production to bring the level up to full production as quickly as possible. Throughout the step out design process, a combination of further defining the ore boundary, using lessons learnt from production performance on upper levels and the introduction of design improvements, has reduced the production ramp-up time, decreased costs and increased recovery for a single level at EHM. CITATION: Nichols, P, te Kloot, C and Harrison, A, 2018. Case study – Ernest Henry Mine: designing step out zones in an inclined sub-level cave, in Proceedings Complex Orebodies Conference 2018, pp 53–54 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By E Holloway

The optimisation of an open pit mine can be broadly split into two stages, the first being the ultimate pit optimisation (and subsequent stage designs), and the second being schedule optimisation. Macroeconomic uncertainty clearly impacts on both however interrelationships do also exist. Generally, the opportunity exists for the ultimate pit to be revised during each planning cycle, however when this reprieve is removed the uncertainty for the underlying business increases. As one example, the introduction of an in-pit waste dump can be seen to significantly limit the option to revise the ultimate pit. When in this situation there are two potential risks that present: (i) the long-term price used for the ultimate pit selection is optimistic, and too large of a pit is selected resulting in waste being mined which uncovers material not of a significant value to deliver a profit; (ii) the long-term price used for the ultimate pit selection is pessimistic, too small of an ultimate pit is selected, and ore of realisable economic value left behind. Both of these outcomes are risks and as such can be assessed and quantified. CITATION: Holloway, E, 2018. Incorporating economic variability into a strategic planning framework, in Proceedings Complex Orebodies Conference 2018, pp 88–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By K Biegaj, S C. Dominy

A high-nugget effect and presence of coarse gold characterises many styles of gold mineralisation. The effective sampling of these deposits is often difficult because of the relatively low concentrations involved and erratic nature of the gold or other minerals. Geometric and/or metallurgical complexities often compound this effect. Underground development, in-fill drilling and bulk sampling/trial mining are generally required to delineate Ore Reserves. Similarly expensive definition strategies often apply to surface mining in complex orebodies of gold and other minerals, including precious stones. Development, particularly winzing is a historical technique that was used to gather geological, grade and metallurgical data during underground and near-surface exploration. It permits access to the mineralised structure below the surface datum to determine viability. Winzing has always been considered an arduous and dangerous task. Modern winzing technology has led to the development of the Mobile Supersucker – essentially a giant vacuum cleaner with underground and surface capabilities. By the elimination of shovel-loaded blasted winze material into a kibble and hoisting, this system permits safe and highly efficient winzing activities, and allows the collection of bulk samples for grade and metallurgical evaluation, as well as access to the mineralisation for geological and geotechnical mapping. Bulk samples from horizontal development have long been collected to help define mineable grade via pilot processing. However, when defining blocks below current development, there has been over-reliance on ineffective ‘small sample’ drill data. The Mobile Supersucker permits the development of winzes and off-winze sub-levels. These provide critical information to a mine technical team when trying to justify capital to go deeper or commence or deepen an existing open pit. CITATION: Biegaj, K and Dominy, S C, 2018. Lowering risk in complex mineralisation: application of mobile supersucker development, in Proceedings Complex Orebodies Conference 2018, pp 113–115 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By S Roberston, G Batt, R Shanahan, B Shah, A Trench, H Bromfield

The geographic imperative of ore systems leaves mining, more so than virtually any other aspect of modern industry, heavily dependent on obtaining and maintaining social licence to operate. A prospective miner cannot arbitrarily walk away from a deposit in search of more favourable community perceptions – concentrations of mineral endowment represent highly specific and fixed elements of the landscape, and their development and extraction thus requires the acceptance and trust of a specific network of landholders and stakeholders, sometimes with diverse and even competing interests in the development and use of the local environment. Weakness or absence of such social licence can bring added costs and complexity to developing and operating a mine – and in extreme cases even result in project failure. Because it must be maintained throughout the life of a project, such social risk becomes a substantial part of overall project risk profile, particularly during routine operations once initial technical and development risks have been largely resolved.CITATION: Bromfield, H, Roberston, S, Shah, B, Shanahan, R, Trench, A and Batt, G, 2018. On equitable distribution of mining wealth and the social licence to operate imperative – an African case study, in Proceedings Complex Orebodies Conference 2018, pp 6–7 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By K Tungpalan, E Wightman, M Edraki, E Manlapig, L Keeney

The depletion of easily mined high-grade ore bodies resulted in the industry having to exploit lower grade, complex resources (Albanese and McGagh, 2011; Darling, 2011; Randolph, 2011). The trend is now towards mining and processing of low-grade and complex ores (Darling, 2011; Yingling, 1990). Variable geological and mineralogical characteristics, and complex mineralogy and texture can result in large variations in metallurgical response and also cause challenges in processing. (Carson, 1995; Lorenzen and Barnard, 2011; Yingling, 1990). Variability and the complex nature of ores are fundamental sources of risk that often cause the greatest economic impact (Dusci et al., 2007; Williams and Richardson, 2004). Hence it is important to effectively characterise these types of ore bodies and assess their processing performance (ie recovery, grade). To enable this, there is a need for the following: (i) characterisation of geological, mineralogical and metallurgical variability in the ore body; (ii) effective selection of drill core with characteristics that represent the range of ores in the entire ore body. CITATION: Tungpalan, K, Manlapig, E, Keeney, L, Wightman, E and Edraki, M, 2018. A systematic approach of sample selection to predict processing performance of an ore body, in Proceedings Complex Orebodies Conference 2018, pp 67–70 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By M Angus, S Konopa, A Virisheff, S Crispin

A positive mill reconciliation at a mine is a double-edged-sword. Much back slapping happens. The bank and the board can’t get enough until the downside becomes apparent. Over a prolonged period, there becomes an issue with market perception and the potential for shareholders to be misinformed regarding the potential value of the project. In addition, there are impacts on mine scheduling, waste allocation (or lack thereof), government expectations, and the potential for misguided external assumptions regarding the ‘unexpected’ results. The PT Agincourt Resources Martabe Gold Mine has shown a significant under-call, in the order of 20% total gold metal, between the Mineral Resource (MR) estimates and Grade Control (GC) estimates since production commenced in 2012. Recently, the under-call has been reduced by incorporating the use of grade control drilling in the MR grade estimates. Despite recent improvements in reconciliation, drilling in 2017 at both Purnama and Barani open pits shows that infill reverse circulation (RC) drill holes often produce significantly higher grades than those predicted in the MR block model. CITATION: Angus, M, Virisheff, A, Konopa, S and Crispin, S, 2018. Martabe Gold Mine, Indonesia: a positive solution for positive reconciliation, in Proceedings Complex Orebodies Conference 2018, pp 76–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By R Valenta, J Owen, D Kemp, E Lebre, G Corder, J Thomas

Numerous recent analyses have shown that future demand for a broad range of critical commodities is unlikely to be met by new discoveries and recycling alone. The only practical alternative source to address this shortfall comes from orebodies which are currently either uneconomic or inaccessible. A common assumption is that a simple rise in commodity price will render these deposits economic. The mining industry has a long history of innovation allowing economic production from increasingly low grade and technically challenging orebodies. Industry “roadmaps” have been produced on a regular basis, with the aim of identifying future innovations which will allow this progression to continue. At the same time, there have been relatively few systematic analyses of the actual range of challenges facing undeveloped orebodies. The aim of this study is to analyse the mix of challenges faced by a group of undeveloped orebodies in order to better understand the relative importance and necessity of innovations applicable to the deposits, with the ultimate aim of determining the relative value and impact of possible innovations to the economic viability of those deposits. CITATION: Valenta, R, Lebre, E, Kemp, D, Owen, J, Corder, G and Thomas, J, 2018. Can a simple price-rise unlock complex copper orebodies?, in Proceedings Complex Orebodies Conference 2018, pp 71–72 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By L MacDonald, D Molver, D Pepper

Increasing contamination/impurity levels (including arsenic, antimony, mercury etc.) of concentrates is an issue of global commercial and health / environmental significance. With increasing environmental pressures at smelters, penalties for contaminants in concentrates continue to rise, accompanied by lower reject limits. There is a strong incentive for miners to investigate alternative means to remove contaminants in order to increase the value of complex ores and concentrates. This paper discusses the global problem of contamination in complex ores and concentrates, how the Toowong Process technology is a potential solution to this problem, and the opportunities this technology brings to the business of dealing with deleterious elements. CITATION: MacDonald, L, Molver, D and Pepper, D, 2018. The Toowong process for treatment of complex ores, in Proceedings Complex Orebodies Conference 2018, pp 119–121 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By R Valenta, A Littleboy

Geological heterogeneity is one dimension of complexity in mining. Significant effort is put into developing an understanding of this complexity so it can be used in resource estimation, mine planning and economic modelling. However, over the decadal lifespan of a mining venture, many other dimensions add to the complexity of a mining operation. These include: technological evolution, market fluctuations; investor confidence; social norms; local expectations; and ecosystem functionality. As with geology, these factors are all heterogeneous, uncertain, time varying and represented through sparse and incomplete datasets. Recent work (Valenta et al) is beginning to show us how these risks correlate in different global settings. By analysing data relating to known, but as yet undeveloped copper deposits, this work (the complex ore body database) is demonstrating that it is the combination of issues (both price sensitive and non price-sensitive) that determine the viability of a deposit for extraction in the 21st century.CITATION: Littleboy, A, Plint, N and Valenta, R, 2018. Mining as a complex system: do we need a new model?, in Proceedings Complex Orebodies Conference 2018, pp 41–43 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By D Kentwell

This extended abstract and associated presentation provide a series of real examples of the complex interactions between the numerous input parameters, both geological and mathematical, that are required for resource estimation. Many of these parameters can contain a large degree of uncertainty at the initial resource stage. The resource tonnages and grades at economic cut offs of some types of deposits are relatively robust to these initial uncertainties while others exhibit significant sensitivity. In some cases, changes in parameters can result in counter-intuitive outcomes. Grades and confidence levels are inseparable; as the parameters change the confidence changes and so does the grade estimate. The extended abstract and associated presentation also discuss the question of whether or not a single solution is still an acceptable outcome for an estimate or if even a set of simulations based on a single fixed set of parameters is acceptable.CITATION: Kentwell, D, 2018. Sensitive dependence on initial conditions in resource estimation, in Proceedings Complex Orebodies Conference 2018, pp 28–30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By M Barden, G Lane, B Quilliam

NQ Minerals PLC, through Hellyer Gold Mines Pty Ltd, plans to reprocess the contents of the Hellyer tailings dam to produce lead/silver concentrate, zinc concentrate and pyrite concentrate (containing Au and Ag). This paper discusses the project development, mineralogy, metallurgy and chemistry of processing Hellyer tailings and the associated environmental benefits. The Hellyer and Fossey orebodies were volcanic hosted polymetallic massive sulphide deposits located within the Mount Read volcanic arc of western Tasmania. Mineralisation was hosted in massive sulphide (pyrite) and comprised predominantly of sphalerite, with lesser galena, chalcopyrite and arsenopyrite. The Hellyer orebody was mineralogically complex (fine grained) and was treated through differential flotation with initially modest recoveries. Fossey ore processing characteristics were similar to those of Que River ore and simpler than Hellyer but treatment still resulted in significant grades in flotation tailings. CITATION: Lane, G, Barden, M and Quilliam, B, 2018. Hellyer tailings – complex mineralogy but higher grade than many ore bodies, in Proceedings Complex Orebodies Conference 2018, pp 35–38 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By T Craske, J Sykes, T C. McCuaig, M Jessell, A Trench

The prevalent strategic approach in the mining industry is one of planning. However, it is widely recognised that planning does not work in complex and uncertain situations (Mintzberg, 1994), such as those associated with ‘above ground’ non-technical orebody complexity (Trench, Packey and Sykes, 2014). Mintzberg, Ahlstrand and Lampel (2009) suggest the focus instead should be on strategic ‘thinking and doing’ and using the many ways to think about strategy to make sense of complex, uncertain, and unique situations. They therefore place great value in cognitive flexibility. Scenarios development utilizes several different thinking styles and thus assists with this type of flexible strategic thinking (Figure 1). The ‘Centre for Exploration Targeting (CET) Scenarios’ were developed with the ‘Oxford Scenario Planning Approach’ (OSPA) (Ramírez and Wilkinson, 2016). The OSPA aims more to improve the thinking skills of decision makers, rather than forecasting per se (Wack, 1985a, 1985b). As such, this paper focuses less on the content of the scenarios and instead on the practical value of scenarios in strategizing. CITATION: Sykes, J, Trench, A, McCuaig, T C, Jessell, M and Craske, T, 2018. Strategic thinking about long-term ‘above ground’ orebody complexity using scenarios, in Proceedings Complex Orebodies Conference 2018, pp 60–64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By R Valenta

Most developing projects face a range of technical and non-technical challenges, and examination of development histories can potentially provide insights into improved approaches to project development. The Kestanelik project in the Canakkale region of Western Turkey was acquired by Chesser Resources Ltd in 2008. Turkey is a significant and growing source of gold production, with sector participation by both domestic and international companies. While the broad ranges of challenges faced by developing projects is well known, there are relatively few case studies in which the range of technical, environmental, social and governance challenges are presented in a single contribution. Recent studies of undeveloped complex orebodies have particularly shown the extent to which environment, social and governance (ESG) complexities contribute to project delays and failures. The Kestanelik project faced a full range of technical and ESG complexities, and provides an illustrative example of the associated challenges. CITATION: Valenta, R, 2018. A case study of technical, social and environmental challenges for a gold project development in Western Turkey, in Proceedings Complex Orebodies Conference 2018, pp 73–74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By P Stewart, S Cowie, A Offer, J Carpenter, E Jones

The Ban Houayxai Gold-Silver Operation is a producing asset for Australian-based copper and gold producer, PanAust Limited. The Operation lies within PanAust’s 2600 square-kilometre Phu Bia Contract Area in northern Laos. Commencing production in 2012, Ban Houayxai is operated by PanAust’s Lao-registered company, Phu Bia Mining. PanAust owns a 90 per cent interest in Phu Bia Mining. The Government of Laos owns the remaining 10 per cent. The Operation mines an intermediate sulphidation epithermal gold-silver deposit and comprises an open-pit feeding ore to a conventional carbon-in-leach process plant. Metallurgical recoveries for gold and silver are approximately 75-85 per cent and 55 per cent respectively. To year-end 2017, the Operation had poured 0.65 million ounces (oz) of gold and 4.7 million oz of silver. The Ban Houayxai Ore Reserve supports a mine life of approximately four years from the end of 2017. The Ban Houayxai deposit is in an early Permian volcano-sedimentary unit which is part of a late Carboniferous to early Permian (310–270 million years ago) volcanic-plutonic sequence of the Truong Son Fold Belt. The deposit formed when hot saline (240–415°C, 2.7–13.0 weight per cent NaCl equivalent) fluids ascended from a geologically fertile island arc porphyry into overlying volcanics along a fault or faults in the early Permian (290–256 million years ago) (Manaka et al, 2014). CITATION: Carpenter, J, Cowie, S, Stewart, P, Jones E, and Offer, A, 2018. Machine learning at a gold-silver mine: a case study from the Ban Houayxai Gold-Silver Operation, in Proceedings Complex Orebodies Conference 2018, pp 82–85 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By D Connelly

The initial results for the cyanide leach gold recoveries were very poor on a high-grade primary sulphide ore of 6.2 g/t Au with no silver. Subsequent mineralogy showed the ore to be a characteristic pyrite, carbonaceous refractory gold ore (double refractory). This was a very disappointing finding. A small scale gravity and flotation test programme was developed to produce a concentrate with the majority of the gold. This also failed with most of the gold remaining in the tailings. An ICP scan also showed variable levels of antimony. A Desktop Study was undertaken with minimal laboratory test work looking at Pressure Oxidation (POX), roasting, ultra-fine grinding, graphite passivation and consideration of any new technologies that might be applicable to this type of ore. The subsequent Study highlighted how difficult these double refractory gold ores are to process and highlighted some recent technology developments may be applicable. CITATION: Connelly, D, 2018. Technology options for processing complex and double refractory gold ore, in Proceedings Complex Orebodies Conference 2018, p 94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By N Madani, Y Abildin, E Topal

Mine planning is a crucial part of all mining industry projects, and nowadays, geometallurgical mapping through advanced computer technologies provides an opportunity to involve metallurgical responses of a deposit into 3D block model in order to optimise mine planning activities, especially for production forecasting. Including these metallurgical parameters apart from traditional geology and grade-based attributes into resource modelling leads to an extensive approximation for the economic maximisation of mine production due to better forecasting, planning and increasing certainty and the reliability of the resource model (Macfarlane and Williams, 2014). Commonly, geostatistical techniques and algorithms are used to produce models with the high resolution (Brissette et al. 2014; Deutsch et al. 2014; Tolosana-Delgado et al. 2015). The accuracy of the modelling procedure deeply depends on a reliable block model, produced by spatial analysis of corresponding variables that define the geological, metallurgical, mineralogical and chemical behaviour of the deposit. However, there are special cases, where the application of enhanced geostatistical methods is required, to solve the occurred difficulties between variables with multivariate complexities. For example, in oxide copper deposits, the soluble copper grade is a percentage of total copper grade and recoverable by heap leaching processes (Emery, 2012; Hosseini and Asghari, 2015). Hence, the joint spatial modelling of these variables has two difficulties.CITATION:Abildin, Y, Madani, N and Topal, E, 2018. Forecast the mineral processing destinations based on spatial interpolation of geometallurgical variables, in Proceedings Complex Orebodies Conference 2018, pp 2–5 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By R Valenta, I Fahey, M Klawitter, N Spanswick

Zinc-Lead-Silver (Zn-Pb-Ag) mineralisation at the George Fisher Mine occurs in multiple structurally-disrupted stratiform orebodies hosted within a mid-Proterozoic sequence of calcareous siltstones and variably pyritic shales (e.g. Valenta, 1994; Chapman, 2004). The geological model for the mine has been constructed based on a large number of stratigraphic domains which have been defined using recognised patterns of the constituent rocktypes, aided by recognition and mapping of K-rich tuff marker beds (TMBs). The continuity of these domains has been affected by the presence of several sets of faults which are extensional in the plane of stratigraphy, leading to the common occurrence of fault-related stratigraphic gaps in drillholes. Recent improvements to the detail of the geological model have led to significant improvements in the head grade of ore at George Fisher, with relatively small loss of metal. Recognition and accurate logging of these domains requires a high level of knowledge and expertise amongst mine geologists. In order to aid this process, the George Fisher mine installed a Minalyzer CS (core scanner) on site, with the aim of using high resolution X-ray fluorescence (XRF) geochemical data and core photography to increase the speed, accuracy and consistency of the site geological logging system. This contribution describes some preliminary results from a research project aimed at using the Minalyzer CS XRF data to perform high-resolution rocktype identification and domain boundary mapping in drillcore at George Fisher. CITATION: Spanswick, N, Klawitter, M, Valenta, R and Fahey, I, 2018. Rocktype classification and domaining of complex stratiform Zn-Pb-Ag mineralisation at the George Fisher Mine using high resolution XRF Core scanning, in Proceedings Complex Orebodies Conference 2018, pp 58–59 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By M J. Davies, R S. Davies

Despite increased expenditure, the global discovery rate of world-class ore deposits has been in decline for over a decade (Schodde, 2017). Mineral exploration has traditionally followed an empirical approach, searching for evidence of mineralisation upon the surface of the planet, then drilling to define the extent of an ore body beneath the surface. As outcropping deposits in well-defined areas are depleted, there is a need for exploration to extend to less well-explored search spaces. One popular new frontier is exploration at greater depths beneath the Earth's surface. However, exploring for deep deposits with limited surficial evidence requires the implementation of predictive targeting methodologies (Hronsky, 2011; McCuaig & Hronsky, 2014). The Mineral Systems Concept (Hronsky & Groves, 2008; McCuaig et al., 2010) provides a framework for predictive exploration targeting. Ore deposit formation is recognised to be a focused mineralising event. These events represent self-organising critical systems and are underpinned by the interaction of complex, non-linear processes. Through the collection and analysis of datasets that map mineralising processes, it may be possible to predict the size and location of resultant ore bodies. CITATION: Davies, M J and Davies, R S, 2018. Beyond below-ground geological complexity: Developing adaptive expertise in exploration decision-making, in Proceedings Complex Orebodies Conference 2018, pp 95–98 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By B Bonfils, P Lois Morales, C Evans

One of the main challenges for current and future mining and processing methodologies is to understand the characteristics of the rock so that its behaviour in one or more parts of the mining process chain can be predicted. Features such as rock texture, mineralogy or border complexity between minerals control how the rock behaves from the processing plant through to the final products, including tailings disposal and thus can affect the feasibility of the project from technical, economic and environmental impact perspectives. Understanding how the mineralogy and texture of rock affect its behaviour in mineral processing is a demanding area of research and is essential knowledge in predicting the processability of complex ores in different stages. This study aims to demonstrate that different types of relevant information can be extracted from a range of currently available analytical methods. However, this information can be used in a complementary way for building a more comprehensive rock characterisation at the microscale and better-predicting ore processing characteristics from the intact rock through to tailing disposal. CITATION: Lois Morales, P, Evans, C and Bonfils, B, 2018. Multisource rock characterisation at microscale for a better understanding of processing characteristics, in Proceedings Complex Orebodies Conference 2018, pp 44–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By M Nehring, M Kizil, P Knights

Mining and beneficiation can be described as sequential processes of separation of valuable minerals from waste. There is a great deal of interest in how the industry can be more effective – and efficient – with these processes. In particular, many mining companies are looking towards digital technologies to improve precision mining practices; that is, the targeted identification and separation of valuable ore from waste during the mining process. Greater precision will help unlock the value in many complex orebodies that are currently considered Tier 2 or 3 deposits. CITATION: Knights, P, Kizil, M and Nehring, M, 2018. Selection of precision surface mining methods for complex metalliferous orebodies, in Proceedings Complex Orebodies Conference 2018, pp 31–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018