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The placer mining industry of the West Coast region of the South Island is based largely around the production of alluvial gold, although other valuable minerals are also present. Since the first major discoveries in 1864-65, reported gold production has totalled around 264 t (8.5 Moz). During the past 10 years, annual production has totalled around 1460 kg (47,000 oz). It is anticipated that gold production over the next three years will continue at a level of 1400-1800 kg.   Annual gold production peaked during 1866 at approximately 17,170 kg (550,000 oz) and has not exceeded 100,000 oz since 1885. This reflects the ease with which gold was won from shallow, rich deposits that were present at many localities. Subsequently, there has been a general decline in the availability of this type of deposit, a trend that will continue in the future. This paper outlines the present state of placer mining in the West Coast region, gives some historical background to the industry and briefly predicts future trends.

Jan 1, 1997

By D G. Rantucci

Organic carbon is a major ore contaminant at MMG’s Century mine. This carbonaceous matter is associated with shale hosted sphalerite mineralisation. It occurs as elongated lamellae and as inclusions in porous sphalerite aggregates which are fine grained and difficult to liberate from sphalerite. The carbon prefloat circuit was designed to remove the liberated organic carbon in order to mitigate excessive reagent consumption, contamination of the lead and zinc concentrates and poor flotation performance in the primary zinc circuit. The consequence of organic carbon removal is that sphalerite and galena minerals are lost to the prefloat concentrate. A Jameson Cell was installed in late 2005 as a prefloat cleaner cell. Operational experience showed that the cell became capacity limited during periods of high amounts of organic carbon in the feed and was subsequently bypassed.Reactive style operating strategies were implemented to manage the effects of insufficient organic carbon removal by the prefloat circuit but due to the relatively large circuit residence time, upstream changes meant hours before the downstream circuits were stabilised following a disturbance from excess carbon.This paper describes the modifications and testwork undertaken to enable the Jameson Cell to be operated during periods of high organic carbon in the float feed and the implementation of process control initiatives to proactively remove the required prefloat mass from the float feed to eliminate the reactive style operating strategy.The process control modifications centred on dynamically targeting a prefloat mass recovery determined by an equation relating the carbon to zinc ratio to the carbon prefloat mass as a percentage of the float feed. The equation was developed by analysing historical data. These improvements served to optimise the prefloat circuit and consequently stabilise the downstream lead and zinc circuits.

Aug 8, 2011

By R Salmon, C Jones

This paper examines the recent trend towards sustainability reporting and the application of the Global Reporting Initiative (GRI) æSustainability Reporting GuidelinesÆ. It also reviews reporting in the context of the Australian Minerals Industry Code for Environmental Management, as well as the status of public sustainability reporting globally in the minerals industry. The public reporting of environmental, health and safety, social/community and economic performance has evolved over the past two decades. Initially, separate and to some degree disparate documents were produced to report performance in each distinct area. In the early to mid 1980Æs some organisations had begun to report their environmental performance through some minor commentary in their annual financial reports or through ætokenisticÆ leaflets, often used as public relations exercises. Due to more media coverage and an elevated level of public scrutiny, organisations are no longer merely reporting their good performance, but also their bad and indifferent performance. In recent years these once separate environment, health and safety and community public reports have further evolved to become more integrated, reflecting organisations embarking on the reporting of their progress towards sustainable development. The primary factor in driving the evolution of sustainability reporting has been the increasing influence of stakeholders. Two groups of external stakeholders that have had a significant influence over public sustainability reporting in recent years have been non government organisations (NGOs) and socially responsible investment funds. Significant expenditure is involved in the preparation and publication of a sustainability report however many organisations do not appear to have examined in detail what they are really trying to achieve from their public reporting process. It is important to establish objectives for the public reporting process to achieve maximum benefits. Without a framework of public reporting objectives, the benefits of the reporting process to the organisation will not be recognised and the considerable expenditure involved will be increasingly difficult to justify. We believe that by focussing on the process rather than the document, significant benefits to the organisation can be gained. Indeed, with a proper framework of objectives and targets, the reporting process can be used as a vehicle to drive organisational change, implement management systems and improve performance. An idealised framework for a public sustainability reporting process sees the organisationÆs sustainability policies drive the entire process and determine the sustainability objectives. Specific targets are then set to realise those objectives. The targets will govern performance indicators that should be used to measure the success of target achievement and which will also define what data need to be collected. Evaluation is a key component of the reporting process to measure the success of target achievement and progress in realising objectives, as well as review the need for new targets to be set. The actual production of a public document is only one, albeit important, component of the overall reporting process. The challenges that lie ahead for sustainability reporting primarily relate to the integration of environmental, social and economic performance reporting as organisations integrate their approach to these areas. This will only happen as the culture of an organisation changes to not only accept the principles of sustainable development but to implement those principles in daily operations. The reporting process has the potential to drive that cultural change by communicating the organisationÆs sustainability objectives and setting challenging targets for their realisation. Public sustainability reporting will only achieve its maximum value when it forms an integral part of an organisationÆs sustainability management system and culture.

Jan 1, 2002

By A Jewbali, L Allen

At Newmont Corporation drill hole spacing studies are done to support the business in understanding the cost of collecting additional information (with a specific focus on drill hole sampling density) versus the value of additional drilling in terms of resource risk reduction. For the last 20 years drill hole spacing studies have been executed in an effort to answer the following question: What spacing should the deposit be drilled at to achieve a certain level of resource confidence so that when mining occurs the resource model delivers as predicted ie what is the optimal sampling density? The optimal sampling density supports a resource model that provides a sound foundation for mine planning purposes and resource/reserve reporting. At Newmont Corporation drill hole spacing studies are now a requisite for understanding drill data density needs for new deposits and near mine expansions. This paper details the evolution of drill hole spacing studies at Newmont Corporation in terms of methodology and usage.

May 24, 2023

By F F. Pitard

Observation from attending many conferences around the world reveals that many people are constantly shifting from the word ‘error’ to the word ‘uncertainty’ without a clear vision of what the subtle difference is. The same applies to a large swath of the scientific literature, in which these two concepts are unfortunately often used synonymously, which is a scientific flaw of the first order. In practice, as demonstrated in the Theory of Sampling (TOS), there are both sampling errors and sampling uncertainties. Sampling errors can easily be preventively minimised, while sampling uncertainty for a preselected sampling protocol is inevitable. P M Gy’s work, supported by G Matheron’s critical reviews, demonstrates beyond any possible doubt that sampling uncertainty cannot be achieved if sampling errors are not preventively minimised by applying very stringent rules that are too often ignored by sampling practitioners. A clarification, in line with the TOS, is presented to mitigate the confusion created by circles favouring the use of uncertainty versus the use of the word error. Both words are very different in nature and scope and they are both necessary in their due place and time.CITATION:Pitard, F F, 2017. From errors to uncertainty – a clarification for proper use by the Theory of Sampling, in Proceedings Eighth World Conference on Sampling and Blending , pp 355–358 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Phillips J. T, Hutton W. A

This paper discusses why Argyle Diamonds adopted thickened tailings disposal in 1985 and how the system was developed over the next seven years. A wide ranging review of the thickened tailings disposal system and the tailings deposit it was producing was carried out during 1992 and 1993. The results of that review led to the abandonment of thickened tailings disposal at Argyle because of serious concerns about the stability of the resultant tailings deposit. The exposure to the risk of liquefaction and an assessment of the consequences if this happened to the thickened tailings deposit are shown. The criteria for selecting the new tailings disposal strategy are then described. The final section of the paper discusses the management strategies that have been put in place. These are designed to: ò reduce the risk posed by the thickened tailings deposit to an acceptable level; ò safely store tailings to the end of mine life; ò produce a land form that can be decommissioned to the satisfaction of Government regulatory bodies.

Jan 1, 1996

Correlation of Air Recovery with Thin Film and Froth Stability in Flotation

Sep 13, 2010

By J Pan

This case study assesses the application of Mine-to-Mill optimisation combined with Whittle Consulting’s Prober<sup>®</sup> economic optimisation for the purpose of economic value uplift in open cut base and precious metal operations. The study extends the application of these optimisation methods to incorporate the recent practice of Ultra High Intensity Blasting (UHIB) developed by Orica Mining Services. The case study deposit known as “Marvin” is a copper/gold porphyry resource that is commonly used in optimisation software training and industry case studies. It has many similarities to Newcrest’s Cadia Hill open pit mine in NSW. Prior desktop research and industrial trials employed static assessments of Mine-to-Mill effects. No prior work other than a Whittle Consulting client study, has sought to assess the impact of variable fragmentation on enterprise economic value. This study examines the use of variable blasting intensity as a driver of economic value maximisation over the mine’s life.CITATION: Howe, S and Pan, J, 2018. Application of enterprise optimisation considering ultra high intensity blasting, in Proceedings Complex Orebodies Conference 2018, pp 14–20 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By D Connelly

Silver and gold bearing ore from the Troy Resources NL Casposo Gold-Silver Project, located within the San Juan Province of Argentina contains a complex mix of gold, silver, electrum and silver sulphides in the ore. Casposo is a typical low sulphidation epithermal style gold–silver deposit where mineralisation is hosted within rhyolite – andesite flows and breccias. Veins are typically banded quartz–chalcedony colloform - crustiform banded with quartz - carbonate infill. Mineralisation is associated with an assemblage consisting of quartz, chalcedony, adularia, calcite, illite, sericite and trace sulphides. Gold and silver occur as electrum, native silver, sulfosalts and silver sulphides. This paper presents a case study that describes the process selection, development and engineering of a tailored process plant for the recovery of gold and silver from this ore.The original feasibility study, modelling, metallurgical testwork and engineering studies are outlined. The final flowsheet was based on minimising capital cost, operability, recovery and minimising technical risk.The process flowsheet uses the traditional Merrill Crowe route because of the high silver to gold ratio in the feed and achieves maximum gold and silver recovery while providing a common facility for future ore body treatment.

Aug 8, 2011

By W Malone, J Garrett

FLSmidth (FLS) has spent the last 15 years, working with customers and engineering houses to deliver innovative improvements in crusher safety, coupled with the latest, maintenance friendly, crusher design. The key focus being to prevent service personnel from working underneath the crusher during maintenance and obviate the need for personnel to be exposed to suspended loads when performing tasks such as, main shaft installation, for example. Improvements include: full top-service capability to ensure the safest and fastest way to disassemble the crusher for maintenance purposes, which also removes the requirement for a service cart; a selfaligning main shaft which ensures remote assembly is now possible, keeping service personnel well out of harm’s way; And rotable shells, or the ability to perform relines off-station, allows for quick shell ‘swap-over’ without the downtime associated with removing, refitting and curing time associated with epoxy backing. The high flow spider improves large material entry into the crusher, reducing blockages and downtime and therefore maintains crusher capacity. Each size of crusher in the range comes with an option to increase the standard feed opening to a larger one if desired to compensate for ‘blocky’ or ‘elongated’ feed material, a common problem for Pilbara hematite iron ores. Power capability has also been increased with a maximum of 1500 kW, to match the higher throughput capacities being achieved. This due to uprated eccentric speeds and larger discharge annulus. Increased eccentric throws and mantle diameters are also now a reality, when compared to more traditional designed gyratory crushers. To keep up with the improved design features of the Mk V, digitalisation has also been upgraded to maximise performance capabilities to ensure that the most efficient reduction and throughput capacities are achieved, whilst utilising the higher powers now available as standard. Condition monitoring ensures that the crusher is at its optimum operating capability by monitoring and adjusting the crusher settings via feedback from additional sensors, ie main shaft spin, temperature and vibration. Camera monitoring capabilities are available as is an advanced oil contamination monitoring system. As a result of the above design improvements, it will be shown that the Mk V range offers benefits such as: enhanced safety features, increased availability, faster maintenance turnarounds, higher power utilisation, equivalent product size at higher throughput capacities and with Remote operation capabilities. All of which result in a gyratory crusher with higher levels of safety and a lower per tonne operating cost.

Sep 18, 2023

By R Nicholson, N D. Cox, N W. A Lambert

"This paper reports on the long-term operation of a particle density meter (PDM) at the Bloomfield coal handling and preparation plant (CHPP). This unit has been operating continuously for over three years, providing real-time data to the operators to allow the monitoring of flotation circuit performance. PDM outputs include slurry density, solids concentration on both mass and volumetric basis, and particle density. Knowing the average particle density of a stream allows for the optimisation of the process in real-time.The calibration of the solids concentration measurement device proved very difficult as the factory calibration techniques and existing laboratory analysis did not give accurate or reliable results. The solids concentration device had to be re-engineered and a new calibration method developed that gave accurate and repeatable results. Independent verification of samples taken from the PDM was undertaken as part of the trial process.The operational reliability of the PDM was a major point of investigation. The initial installation of the unit revealed issues with large, misplaced material of up to 20 mm periodically entering the unit, leading to feed blockages. The presence of these misplaced, oversized particles in the flotation circuit was resolved by installing innovative automatic back flush systems on the PDM.From a plant perspective the PDM has been an invaluable instrument that has enabled irregularities in the flotation circuit performance to be identified, which sampling had not and could not readily identify. This was achieved by close monitoring of real-time tailings composition on a minute by minute basis over short and extended periods. Variations in the tailings stream with respect to particle density and solids concentration were traced back to other issues in the plant. In addition, the PDM has allowed cell optimisation with respect to reagent dose rate to be improved. The PDM with real-time feedback can negate the need for large sampling campaigns and analysis during plant optimisation programs.Citation:Lambert, N, Cox, N and Nicholson, R, 2016. Particle Density Meter, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 245–250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By D Tucker, K Harney

Hatch forecasts that an increasing share of seaborne traded iron ore will be ultrafine, being either concentrate or pellet feed. This provides several challenges for the iron and steel industries, but the principal concern is: how much ultrafine iron ore can be consumed on sinter strands and with a minimal effect on productivity?This paper will identify new supply by project through 2020. Demand will be estimated for sinter production and practical steps will be identified to increase ultrafine consumption in sinter strands. The long-term iron ore price will be forecast to balance supply and demand. The paper will conclude by assessing how the pricing of ultrafine ore will develop relative to the Chinese iron ore indices.CITATION:Tucker, D and Harney, K, 2015. Iron ore ultrafines challenges and opportunities, in Proceedings Iron Ore 2015, pp 501–504 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By C V. Deutsch

"Geometallurgical variables often cause problems to conventional geostatistical workflows. There are many variables; some are compositional and some are non-additive. They often show: complex multivariate relationships undersampling relative to conventional grade variables unequal sampling; that is, all variables are not available at all data locations.A variety of approaches have been developed over the years, but geostatisticians remain mostly focused on modelling rock types and a few grade variables with an abundance of data. The problems are reviewed and a chained workflow is presented where appropriate techniques are employed in sequence to permit reliable spatial prediction of geometallurgical variables. The spatial models may be used to assess the value of additional data, for prediction of process performance, for improved mine planning and other optimisation tasks. The chained workflow will include data transformations such as ratios and normal scores that make the variables amenable to geostatistical modelling. Data imputation techniques to account for missing values are considered with special consideration to spatial correlation with the available data. Decorrelation techniques such as the principal components, min/max autocorrelation factors and projection pursuit multivariate transformation are employed to manage massively multivariate modelling. Full distribution modelling must be considered to avoid biases in the prediction of non-additive variables. The post-processing of geometallurgical models must be streamlined for robustness and efficiency. The precise workflow varies according to the specific purpose of the study. Guidelines and thoughts on best practice are presented.CITATION:Deutsch, C V, 2013. Geostatistical modelling of geometallurgical variables - problems and solutions, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013, pp 7-16 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 29, 2013

Effect of Anionic Surfactant on Silica Particle Attachment at the Oil-Water Interface Controlling particle attachment is crucial where powdered solids come into contact with oil and water. Particles are trapped in a deep energy well at the oil-water interface, stabilising emulsions. Here it is shown that adding anionic surfactant causes dramatic changes to the bulk and interfacial structure of silica particle-stabilised oil-in-water emulsions. Exposing particle-stabilised drops to surfactant concentrations above the critical micelle concentration enhances the rate and extent of creaming and flocculation. Mixing particle-stabilised emulsions with surfactant solutions causes drop fragmentation. As the surfactant concentration increases, the average drop size decreases and particles are displaced from the interface during the mixing process.

Sep 13, 2010

The theme of my address to your Institute, indeed its name, is "The Mineral Industry - What Next?" Knowing that I was required to make four appearances, and not wanting to be too repetitious, I wrote a rather long speech of which I will deliver various sections at different places, with a common introduction. Specific areas I have addressed are "Exploration", "New sources of minerals and energy", and "Mining and metallurgy of the future".

Jan 1, 1984

By X Dahe

SLon vertical ring and pulsating high gradient magnetic separators possess excellent mineral processing ability and have been widely applied to process oxidised iron ores. SLon centrifugal separators are applied to clean the SLon magnetic concentrate and remove quartz and other gangue minerals associated with a small portion of magnetite.This paper introduces the application of this technology in Hai Nan, Da Hong Shan and An Shan for processing oxidised iron ores.

Jul 11, 2011

Distribution of Settling Velocity of Irregular Particles and its Effect on Jig Separation Efficiency

Sep 13, 2010

This research is about human development and socio-economic progress of the main mining areas of Chile in the period 1990 - 2007, and especially about the positive effects that mining activity has on poverty reduction and indicators related to the Millennium Development Goals of the United Nations. The analysis is doubly interesting, if one considers that the economic and social developments in Chile, recognised and prominent among the Latin American economies and developing nations, are more evident in mining areas as Tarapacß and Antofagasta (northern Chile), which concentrated than more 70 per cent of investments and mining assets in the country. Additionally, the study concludes with methodological reflections for the evaluation of socio-economic impact in the mining industry in developing countries.

Jan 1, 2009

The selection and implementation of the right technology for a project is critical to the future development of the resource industry. It is essential for companies to ensure ongoing competitive viability that where practical new or alternative technology be adopted. Analysis of historical data relating to development of resource-based process plants provides an enlightening insight into the key factors which influence their success or failure. The adoption of new technology does not guarantee the success of a project. The outcomes of this analysis have been used to develop some general guidelines and principles the author believes are useful in the selection and implementation of new or alternative technology in resource projects. This paper is available as a PowerPoint presentation only.

Jan 1, 2006

By A Whaanga, W Vigor-Brown

IGO Ltd’s (IGO’s) Nova-Bollinger Deposit (Nova-Bollinger) is a magmatic nickel-copper-cobalt (NiCu-Co) sulfide deposit found 160 km east-north-east of the town of Norseman in Western Australia (WA). The deposit is hosted by the Mesoproterozoic rocks of the Fraser Zone, which is part of the Albany Fraser Orogen (AFO). Since mining commenced in 2016, IGO’s Nova Operation (Nova) has mined and processed to 31 December 2020, 5.63 Mt of ore grading 2.04 per cent Ni, 0.86 per cent Cu and 0.07 per cent Co. Nova’s mine geology team (MGT) has used commercially available implicit modelling (IM) and general-purpose resource modelling (RM) industry software systems, to prepare the 31 December 2020 (CY20) update of Nova-Bollinger’s JORC Code reportable Mineral Resource estimate (MRE). This CY20 MRE update was predominantly based on ~386 km of diamond core drilling, with the drill holes having a nominal grid spacing of 12.5 by 12.5 m throughout the mineralised zones of the deposit. Using IM tools, Nova’s MGT interpreted and modelled 22 separate domains from the drill hole logging, assaying results, and the MGT’s underground mapping. These IM closed volumes were then used to control the estimation of MRE variables into conventional industry digital block models using RM and other ancillary software systems. During 2021, a commercial machine learning (ML) software was trialled by Nova’s MGT for preparing block models of Nova-Bollinger’s MRE domains. The motivation for the trial was that the ML process could expedite modelling through the direct creation of a domain coded block model from the drill hole logging. Compared to the industry standard approaches of wireframing or IM, where the modeller usually makes many subjective choices to produce the domain model, ML offers a more objective ‘hands-off’ process for determining the connectivity of domains defined in drill holes. Additionally, the ML process provides a quantitative confidence metric associated with its output that may have utility in mine production and resource classification. In this paper, the results of the Nova-Bollinger ML modelling trial are compared to the MGT’s current workflow for MRE work. The MGT’s conclusions as to the advantages and disadvantages of the IM and ML methods for preparation of MRE domains are discussed. The ML software was also tested as a method of rapidly interpreting geology outside the principal zones of MRE interest. These testing results are also presented in this paper.

Mar 22, 2022