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By T Baumgartl, J Burgess, B Emmerton, P D. Erskine

Large-scale open cut mining in the Bowen Basin has been undertaken for over 40 years. During this period, improved mechanical capability and economics have allowed extraction to greater depths, resulting in post-mining landforms of increasing height. Rehabilitation practitioners face significant challenges in stabilising these landforms and require a comprehensive understanding of the Bowen Basin Coal Measures strata likely to be disposed of during mining. Knowledge regarding the potential behaviour of differing spoil materials (following disturbance) provides a rationale to maximise short- to medium-term surface stability of constructed landforms by identification, salvage and advantageous reuse of cladding resources as a means to minimise erosional risks.CITATION:Emmerton, B, Burgess, J, Baumgartl, T and Erskine, P, 2016. Bowen Basin coalmine spoil classification for improved mine rehabilitation outcomes, in Proceedings Life-of-Mine 2016 Conference , pp 142–147 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By M P. Sandy, R M. Stephenson

Portals to access underground mines are important infrastructure and their design requires careful consideration. Portals are generally expected to last for the life of the mine. Typically, the exposure of personnel and equipment is high, with many hundreds of movements through the portal per day. Consequently, the risk associated with geotechnical instability must be extremely low. Portals are often established from a boxcut. In areas where the weathering profile is well developed, the design and execution of the boxcut can involve significant effort, with the objective of minimizing the volume of the boxcut, whilst ensuring that conditions at the design depth are suitable for establishing a stable portal. Properly designed site investigations are a critical part of this process. Currently available portal design guidelines have not been updated for decades, however the equipment and ground support systems have changed significantly in recent years. Many mine portals have since been constructed in a relatively short time frame with success, often in challenging ground conditions using some of the more modern approaches to ground support. This is beneficial because delays in establishing a portal will generally delay other critical path activities, and lead to cost overruns.

Mar 15, 2021

By F Clark, J T. Carswell

Ore definition for final stope planning is often a challenging prospect in underground (UG) gold mines which exhibit high geological and grade variability. Unlike the grade control (GC) scenario in an open pit (OP), the ability for the mining geologist to plan a sampling campaign which effectively characterises the underlying mineralisation is fraught with difficulty. UG sampling patterns are strongly clustered and typically not dense enough to characterise the spatial and statistical properties. Very commonly, sample volumes are not large enough to provide a reliable grade estimate of the surrounding rock. These factors critically affect our ability to accurately map out ore positions and estimate metal quantities.At Sunrise Dam, traditional UG sampling and modelling techniques have proven to be an unreliable strategy for successful stope planning and extraction. The problem was first observed during the final cut-back in the open pit for which the mineral resource model was constructed from UG diamond drilling. Open Pit grade control reconciliations were strongly positive for both tonnage and grade compared to the resource model. Underground workings missed significant quantities of ore which was laterally defined by open pit reverse circulation (RC) GC drilling. Upon examination it was realised that the cause of the problem was one of inadequate sample density and sample support, the implications of which potentially affected the entire UG mine.As part of a broader study into underground grade control procedures, detailed reconciliation of initial stope production from the GQ domain also pointed to inadequate sampling as a major constraint to effective grade control and reserve conversion.To overcome this deficiency, dense 115 mm wet RC grade control drilling and conditional simulation modelling has been successfully implemented with the intent to replicate the grade control process in the open pit. The increase in sample density and sample volume has proven to be a very effective tool for mapping out highly complex mineralisation. A marked improvement in stope definition, reserve conversion and Mine to Mill reconciliations has been demonstrated on the back of an innovative approach to UG grade control.CITATION:Clark, F and Carswell, J T, 2014. Using reverse circulation drilling to improve sampling in a complex underground gold operation – an innovative approach to underground grade control at the Sunrise Dam Mine, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 143–152 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By L P. Trout, D G. Reid

PanAust Limited (PanAust) has successfully constructed and commissioned two mining operations in Lao PDR over the past decade and undertaken major studies for three new mine developments. The management of potentially acid generating mine waste and tailings in close proximity of local communities sensitive to water discharge quality have been recurring themes that have confronted PanAust’s project study, development and operational teams. Further compounding challenges, such as the effects of intense annual tropical monsoonal conditions, staging of embankment raises and regular lifting of spillway structures, integrating mine waste and tailings management into production plans and ensuring the long term stability of structures, have been addressed by implementing leading practice management solutions.A recognition of the criticality of managing the substantial business risks associated with these crucial activities led to the early establishment of a governance structure to ensure that the highest standards are embraced for planning and execution. Importantly, these are guided and monitored by a panel of highly experienced and qualified international specialists reporting directly to PanAust’s Managing Director – the Tailings Independent Review Panel. The stewardship process has been effective in identifying potential shortcomings in management systems and has led to enhanced executive commitment to risk informed designs, assurance and overall process rigour.CITATION:Trout, L P and Reid, D G, 2018. PanAust Limited’s approach to mine waste and tailings stewardship, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 135–155 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J Joy, A Bye, G V. Kizil

This paper demonstrates an application of a recently developed Risk-Cost-Benefit (RCB) Framework to environmental risk management in the mining industry. The environmental application of the RCB Framework as part of an ACARP project (Kizil, Bye and Joy, 2012) involved a thorough selection process with site visits and in-depth discussions with the case study siteÆs environmental management team. Under their guidance, the highest risk of environmental impact at the case study site was identified as æroad subsidenceÆ at the time when the project work was undertaken. This paper presents the unique application of the RCB Framework to examine the risk of mining-induced subsidence and its impact on one of AustraliaÆs busiest highways, with a traffic volume of 38 000 vehicles per day (NSW RTA AADT, 2008). The RCB Framework was employed to assess the optimum group of controls for road subsidence risk management to ensure highway availability while mining occurs. Whilst this paper focuses on road subsidence, the methodology employed can be directly applied to other environmental concerns including preparation for mine closure, rehabilitation planning and waste management. The RCB Framework incorporates mathematical modules which were developed to enable complex yet tightly integrated RCB calculations. The process integrates the risk-control effectiveness assessment to determine that the selected safety initiative is financially beneficial to the mine site and company. This concept has been applied to a number of high-risk mining areas targeting safety, productivity and environmental issues. This paper introduces the five-staged RCB Framework, incorporating the RCB tools RCBGEN (Risk-Cost-Benefit Generator) and RCEMETHOD (Risk-Control-Effectiveness Method), and demonstrates its practical application to the risk management of a road subsidence case study. The case study looks at potential pavement damages, in particular, the occurrence of pavement stepping on the surface of the highway as a result of vertical subsidence. This type of road damage was previously experienced at another major inter-city route while underground mining occurred in the region where the case study site is located. The RCB Framework has been successfully applied to the analysis of the road subsidence case study and determined the risk reduction and financial benefits of implementing a range of risk-controls. User-friendly RCB Charts to provide an aid for decision-making were produced. The value of using the RCB charts to achieve balance between risk, cost and productivity in the decision-making process for risk management has been explained. The case study determined that pavement slots and fibre-optic cable monitoring were relatively low-cost and effective controls applied in the mining industry for the first time at a global level.This paper supports the industryÆs ongoing efforts to manage risk to ALARP (as low as reasonably practicable) and achieve æzero harmÆ by providing a new Framework to more effectively establish the adequacy of controls.CITATION:Kizil, G V, Bye, A and Joy, J, 2012. Application of risk-cost-benefit analysis to highway subsidence due to mining, in Proceedings Life-of-Mine 2012 , pp 197-206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By M Colwell

The Coal Mine Roof Rating (CMRR) is a rock (roof) mass classification (RMC) system/index that was originally developed by the United States Bureau of Mines (USBM) for aspects of underground coalmine geotechnical design and was first introduced to Australia as a part of the original Analysis of Longwall Tailgate Serviceability (ALTS) project conducted in 1997/1998. In subsequent years further refinement to its calculation was undertaken, such that the CMRR is now an industry standard for quantifying the structural competence of the primary bolted roadway roof interval and has been routinely/widely used by Australian collieries over the last 25 years with great success for roof support/chain pillar design. There have been many publications discussing the use and calculation of RMC systems and this paper also provides an important update and recommendations in how best to calculate the CMRR. However, it is rare to find an explanation as to why and how a RMC system/index satisfactorily takes account of the mechanics and rock mass behavioural issues associated with ground reinforcement. This paper provides such an explanation and insight with respect to the CMRR so it is: 1) better understood, 2) to allay any concerns, and therefore 3) will continue to be confidently used by and for the collieries’ benefit.

Nov 29, 2022

By R Wynn, N Stoitis, R A. Lauten, H Liang

At the Century mine in North West Queensland, MMG produces lead and zinc concentrates. The current production rate is close to 500 000 t of zinc per annum. Graphite is the main gangue in the orebody and a substantial quantity of chemicals are used to achieve an acceptable depression of graphite and other gangue materials in the current operation. In the future, it is anticipated that the content of graphite in the orebody will increase while the zinc grade will gradually drop. This scenario illustrates the importance of an optimised suite of flotation chemicals to maximise concentrate grade and recovery. As an alternative to the current reagent suite where dextrin is used to depress graphite, laboratory test work and subsequent plant trials were conducted with alternative depressants. These depressants facilitated both graphite depression and elevated zinc grades in the rougher concentrate. As an added benefit, it was also observed that the silica content in the zinc concentrate was reduced in the presence of the biopolymer selected for the plant trials. Results from both laboratory tests and plant trials will be discussed to illustrate how this change of reagent suite improved flotation yield at the MMG Century Mine.CITATION:Wynn, R, Lauten, R A, Liang, H and Stoitis, N, 2014. A change in graphite depressant to improve the recovery of zinc at MMG Century mine, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 179–186 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By H Hoogvliet

The Goondicum Crater industrial minerals deposit is located about 30 km east of Monto, Central Queensland, Australia. Early exploration programs in the 1990s found alluvial ilmenite along the banks of the Burnett River. This mineralisation was traced upstream to the Goondicum Crater. The Goondicum Crater is a topographic feature centred on a roughly circular 6 km diameter layered gabbro complex. Significant ilmenite, apatite, titano-magnetite and feldspar mineralisation are present in a weathered horizon up to 25 m thick. After several drilling campaigns in the Crater and subsequent feasibility studies, the project was developed by Monto Minerals Ltd, an ASX listed company, in 2007. However, the project never achieved production performance expectations and ran out of commissioning funds. The company subsequently went into voluntary administration in August 2008.In 2009, the RMM Capital group, of Brisbane, took control of Monto Resources Pty Ltd, and renamed the company Belridge Enterprises Pty Ltd (Belridge). Belridge commissioned a redevelopment study aimed at recommencing mining and processing operations. As part of the redevelopment study the authors planned a drilling campaign, managed a quality control program and developed a block model. This paper describes the drilling program, analytical procedures, quality control procedures and the preparation of the block model.The block model for the resource estimate was created using 1 m high blocks, wireframes defining the main material types, and 2.5 m thick horizontal search ellipsoids with a radial pattern. The deposit was ‘flattened’ prior to modelling. To assist with the economic evaluation of the project, each block in the model was assigned a net dollar value based on economic parameters provided by Belridge, including anticipated revenues and costs. This modelling technique allowed for efficient investigation of various scenarios and was used extensively in the development and optimisation of the project’s financial model. At a zero net value per block, comparable to a break-even cut-off grade of four per cent ilmenite equivalent, the Indicated plus Measured resource is estimated at 51 Mt, averaging 4.1 per cent ilmenite, 1.9 per cent apatite and 2.5 per cent titano-magnetite.

Oct 5, 2011

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

Jan 1, 1903

By P Crittenden

Thiess Pty LtdÆs Australian Mining business unit used 7.6 PJ of energy in the 2007/2008 financial year. This represented more than 85 per cent of Thiess Pty LtdÆs total energy use and therefore meant that the Australian Mining business unit is required to conduct energy efficiency assessments and report publicly on the outcomes by December 2008 under the Federal GovernmentÆs Energy Efficiency Opportunities (EEO) Act. Thiess Pty Ltd has a policy commitment to sustainable development throughout its operations. This includes minimisation of its carbon footprint and the Australian Mining business unit has a strong focus on efficiency in all of its operations. It approached the energy efficiency assessment as an opportunity to further improve and build on its energy efficiency and greenhouse gas reduction focus in the business. As a mine contractor, Thiess faced a number of challenges in designing an assessment process that would be both effective and efficient to deliver. For example, unlike most other companies involved in the Energy Efficiency Opportunities program, the energy use associated with the Australian Mining business unit is not fixed to any single geographic location in Australia. Mining vehicles are moved from site to site according to the specific requirements of mine owners and the timing associated with the commencement and completion of contracts. Thiess departed from a traditional æsite by siteÆ based assessment and designed a ærepresentative assessmentÆ approach that involved detailed investigation of data across all sites and a focused assessment on a single site.Data and analysis was an essential part of the assessment and indicators at company, mine and site level were essential in identifying opportunities and tracking progress. Forty-six potential energy saving opportunities were identified and four of these are currently being implemented. The projects being implemented are: payload management, automating mobile lighting equipment, plant idle time management, and turbo idle downtime. The potential savings from the four major projects that have been identified are approximately 150 800 GJ/annum, equivalent to 10 600 tonnes of CO2-e/annum with a simple payback period of less than two years. Beyond the fuel savings however, there are a number of other benefits from the assessment, including operational efficiency, reduced maintenance costs and even a potential reduction in the number of vehicles required to complete the work. The EEO assessment has significantly increased the importance and urgency of energy efficiency and facilitated the sharing of good practice across all Thiess operations. Not only have four projects been adopted for immediate implementation but a further pipeline of projects is available for future possible implementation. This case study describes: how Thiess conducted its assessment including the use of energy data and indicators, the opportunities identified that are currently being implemented, and the lessons learnt and how other organisations can use these to improve their approach to energy efficiency assessments. This case study is a more comprehensive version of a case study developed for the Commonwealth Department of Resources, Energy and Tourism. The assessment results reported in this case study are drawn from the Thiess Energy Efficiency Opportunities Report 2008.

Jan 1, 2009

By T Blenkinsop, A Jenkins, H Moore, L Fisher, N Oliver, J Cleverley, M Nugus, J McLellan, J Hill, N Brunacci

The 2 Moz Vogue mineral resource is a recent discovery at the Sunrise Dam gold mine (SDGM), lying approximately 600 m vertically below the Sunrise Dam open pit. Unlike most other lodes, which are dominated either by steep vein sets or shallow high-strain (shear) zones, it lies broadly in the hinge of a folded felsic porphyry body, where it cuts intermediate volcanic lavas and volcaniclastic rocks and is not specifically concentrated at a lithofacies contact. The mineralisation is controlled by a complex interplay of moderate to shallow, west-dipping high-strain zones that are transected by irregular and discontinuous high-grade, north-west-, north–south- and east–west-trending breccia sheets that initially caused problems with attempts to model broad domains. However, by combining the structural controls and styles with the distribution of gold, arsenic, sulfur and antimony, we have improved opportunities for scheduling, extracting and processing the most appropriate material considering the current mining and processing constraints.The early delineation process for the Vogue lode revealed a significant mineral resource for the SDGM, coupled with the recognition of some potentially difficult downstream implications for mining and processing. The ultimate success of mining at Vogue will be a consequence of combining standardised data collection and geological modelling techniques with the results of the novel innovative techniques applied at an early stage of the project.Innovation (in the truest sense) drives change and application to deliver efficient and effective outcomes. Initial data generation and interpretation in lodes above Vogue provided a sound geological model based on strong structural foundations, leading to ideas that could be tested and validated by stress inversion analysis and modelling simulations. Geomechanical modelling simulations, based on the structural analysis, then provided an insight into both the structural and fluid evolution of the system and highlighted target areas. This promoted support for deeper drilling and sampling, which lead to the discovery of Vogue.With additional data, the structural model for Vogue was re-engineered through combination with geochemical and hyperspectral analysis and detailed geological and geostatistical domaining. Initial poor results from metallurgical tests from a small batch sample refocused efforts to undertake mineral and chemical characterisation and profiling (geometallurgy) and combine this data with the composite geological-structural-geochemical model. The result is a conditional probability model for differentiating mineralised or waste domains, with direct outcomes for planning, drilling and mining.CITATION:Nugus, M, Oliver, N, Blenkinsop, T, Hill, J, McLellan, J, Cleverley, J, Fisher, L, Brunacci, N, Moore, H and Jenkins, A, 2014. Exploration and innovation – the discovery and evolution of the 2 Moz Vogue Gold Resource, Sunrise Dam Gold Mine, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 323–340 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By L Nienaber

Mines, after becoming operational, often retain the same support and reinforcement designs developed in the feasibility study. These designs are conceived from limited drilling data and regional experience, thus having an empirical flavour. Empirical designs are perceived to be conservative, catering for a variety of failure mechanisms, which are not always present in mine development drives.This begs the question: If you were to invest in the necessary resources to obtain sufficient data and complete the required analyses for the different development drives in the mine, to engineer a support and reinforcement scheme with the capacity to match the demand of the rock mass, what is the difference in cost when comparing an empirical design to an engineered design?To answer this question, mine tunnels with different geometries and orientations, where detailed structural data was available, were selected for a comparative design exercise. Material cost, development cost, cycle time and professional fees for engineered and empirical designs were estimated. The outcome is summarised in the following paper that discusses the process followed and the results of the design comparison.

Mar 8, 2011

By G du Toit, P L. Gillot, M Swanepoel

Randgold Resources’ Loulo-Gounkoto Complex is one of the largest gold mining operations in Mali, West Africa. The mine, which is situated on the western border with Senegal, treats more than 4 Mt/a of ore through a conventional three-stage crushing and ball milling circuit followed by a carbon-in-leach plant. Ore supply is achieved by a combination of open pit and underground mining, with the majority of the ore supply sourced from the Gara and Yalea underground mines situated approximately 2 km and 6 km respectively from the gold plant.In 2011, Randgold Resources commissioned Golder Associates to perform an evaluation study for providing structural backfill to both the Gara and Yalea underground mines using the current gold plant tailings. The test work performed as part of the evaluation study concluded the need for a tailings cycloning and dewatering facility capable of producing slurry at a solids concentration of 65 per cent with a particle size distribution that had minimum 25 per cent passing 20 µm and less than 5 per cent of -5 µm material. Tailings desliming was required to ensure a consistent feed quality to the paste preparation plants and to ensure that the system would be capable of handling variation in the feed composition from the gold plant.WorleyParsons, previously TWP Projects, was contracted by Randgold Resources to complete the engineering design for the slurry preparation plant, whilst Golder Associates was retained to complete the engineering design of the two paste preparation plants.This paper discusses the test work, design considerations and engineering design of the slurry preparation plant, termed the ‘intermediate plant’, as well as all ancillary facilities required for the delivery of the deslimed slurry to the paste preparation plants located at the two underground mines.CITATION:Swanepoel, M, du Toit, G and Gillot, P L, 2014. Case study – engineering design for a slurry preparation plant for a paste application in West Africa, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 477–486 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By E C. Holloway

"The financial valuation of mining assets has a number of fundamental differences to the valuation of many other asset groupings. One such difference is that typically, the greater proportion of both the cost and revenue sides of the cash flow are inherently governed by systemic market forces.As a result, the range of outcomes for the valuation of each mining asset is more unpredictable, with higher levels of risk and uncertainty. In contrast, the management function of many other non-mining businesses or industry groups can control at least a portion of the cash flow by maintaining the margin or controlling the sales price. The management teams of mining businesses and operations typically have limited options, and are thus price-takers for both costs and revenues. As mining is an inherently cyclical industry, large, long-life operations can exist through several price cycles, making valuation both subjective and challenging.The outcomes of both static- and stochastic-based valuations, as well as the internal probabilities of the associated cash flow statements, are significantly impacted when the correlations between the appropriate parameters are quantified, modelled and incorporated into the valuation framework. The appropriate parameters for correlation modelling primarily include those that are governed by systemic market forces. Applying this process results in a different risk profile for the asset by allowing the risks resulting from systemic market movements to be more accurately quantified and then objectively minimised. This process also reduces the level of residual uncertainty in the valuation outcome.This paper presents a valuation methodology to pragmatically incorporate this level of valuation sophistication and statistically quantify the associated increase in the level of confidence of the valuation outcomes reported.CITATION:Holloway, E C, 2016. Correlated valuation methodology, in Proceedings Project Evaluation 2016, pp 181–200 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By M Binks

The Fosterville Gold mine is located approximately 20km to the East of Bendigo in central Victoria. The gold at Fosterville occurs as solid solution within disseminated arsenopyrite and pyrite. The Fosterville ore bodies contain various amounts of native carbon in the form of bituminous coal. This carbon (Non-Carbonate Carbon or NCC) has been the predominant mechanism for gold loss from the processing facility through”preg-robbing”.Processing of the Fosterville ore is achieved initially through crushing, grinding and flotation to extract the sulphides. The sulphide concentrate is oxidized using Bacterial Oxidation, before being leached in a conventional CIL circuit. A high portion of the native carbon (NCC) in the mine ore is naturally hydrophobic in nature, and subsequently reports to the flotation concentrate stream, and ultimately onto the CIL circuit. This NCC has a notable preg-robbing ability. Treatment of Black Shale ores, which have elevated NCC levels, has historically resulted in CIL recoveries as low as 35%, with around 60-80% of the gold loss from the leach circuit attributed to preg-robbing.Standard technologies for dealing with a carbonaceous leach feed have been trialed with limited success. The discovery of the significance of heat on leach recoveries, triggered extensive testwork on a range of leach feed and tails samples. Pilot plant testing demonstrated that “Heated Leaching” of the CIL tails was the best process with an average recovery increase of 7.5% being achieved. Following a successful pilot study, an engineering feasibility study was completed by Minerva Engineering, and the project economics determined. With strong recovery gains evident and a predicted project payback of 1-1.5 years, approval for the installation of the full scale plant was granted. Detailed design commenced in September 2008 with installation commencing in January 2009. The circuit was successfully commissioned in April 2009.Following commissioning, the Heated Leach circuit has achieved recovery gains of 4-14%, and has proven itself to be a significant contributor to the overall plant performance.

Aug 8, 2011

By J Channell, G Phillips

"The Chesney deposit, located 4 km south-east of Cobar consists of three copper-gold rich shoots that lie within a larger, copper dominant lode. A fourth gold rich shoot is located adjacent to the main deposit. The deposit exhibits a strong structural control on mineralisation, as brittle deformation during subvertical extension provided the requisite structural traps to precipitate sulfides from solution. It is postulated that the Great Chesney Fault acted as a fluid conduit, conveying fluids to the site of orebody formation. The continual supply of fluids resulted in cyclic brittle deformation when the fluid pressure exceeded the lithostatic pressure and the tensile strength of the Great Cobar Slate.Evidence supports the hypothesis that ore deposit formation was controlled by: a supply of mineralised fluids transported along the Great Chesney Faulta suitable location for the mineralised fluids to accumulate, accommodated by vertical extension and dilation in certain locationsthe creation of suitable structural traps to capture the sulfides. These traps formed as a result of fault-valve behaviour. Understanding the controls on mineralisation enables prediction of the location of other deposits with similar emplacement history, or extensions of current deposits.CITATION:Channell, J and Phillips, G, 2014. Understanding mineralisation controls – a case study of the Chesney deposit, in Proceedings Ninth International Mining Geology Conference 2014 , pp 301–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By C McCamley

"The requisite for maintaining optimal carbon concentration levels in a carbon-in-leach (CIL) circuit is of paramount importance in the prevention of gold losses. The process’s ability to recover gold from the aqueous phase is primarily dependent on the carbon loading profile of the CIL train.Newmont Boddington Gold (NBG) have over 2015 tested the Mintek online carbon concentration wmeter (C2 Meter) suitability for effective carbon concentration measurements in their CIL circuit compared to the standard method where the readings are taken twice a shift by the operations staff. The C2 meter works by passing a 1MHz ultrasonic signal through a slurry containing carbon where there is a relationship between the carbon concentration and the attenuation of that signal.It also highlighted another area where the C2 meter could be implemented at NBG whereby the instrument can be as a cautionary device for carbon losses in place of carbon safety screens.Citation:McCamley, C, 2016. Continuous Carbon Concentration Measurement at Newmont Boddington Gold, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 207–212 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By G Burton, S Fityus, J Li, S Vaughan, D Payne

Daunia and Caval Ridge coal mines, owned and operated by BHP, have been co-disposing rejects and dewatered tailings within spoil dumps from the beginning of their operations in 2013 and 2014, with the purpose of minimising environmental impact and geotechnical risk. Following the recent large failures of tailings dams around the world, BHP Coal, through its Coal Tailings Program, plans to transition other coal mines to deliver “dry” tailings and produce mixed plant rejects (MPR) for inpit co-disposal. This will materially reduce future tailings dam risk exposure. Previous laboratory shear strength testing was conducted on rejects with a maximum particles size of 20 mm, and some concerns were raised that this might not represent the mechanical properties of the actual full particle size distribution (PSD) rejects. BHP was also aware that using different technologies to dewater the tailings, such as belt press filters (BPF) and solid bowl centrifuge (SBC), could produce thickened tailings which could significantly modify the physical behaviours of the MPRs, particularly the bonding between particles. Therefore, laboratory testing on both coarse rejects and mixtures of the coarse rejects and dewatered tailings (MPRs), with full PSDs, was carried out. Testing was performed using the large direct shear machine developed by the Australian Coal Association Research Program (ACARP) project C20019 in 2017, as well as a 300 mm diameter triaxial apparatus at the University of Newcastle (UoN). This paper presents details of the laboratory testing program and results for the rejects from the first studied mine of the BHP Coal Tailings Program. It compares the shear strengths measured at full scale with those tested on modified (scalped or crushed) specimens in the past; and discusses the tailings dewatering technique selection from geotechnical aspects based on the testing results, and finally presents some dump and tip head stability analysis results using the testing results.

Jul 1, 2021

By G Kirk

Definition and delineation of in-pit ore and waste material are the most significant tasks for an open pit production geologist; adding or destroying value in the mining value chain. Anglo American’s Mogalakwena Platinum mine, an open pit operation in South Africa moving 100 Mt/a, has recognised the value of improved material definition and is in the process of changing from blasthole to reverse circulation (RC) sampling for in-pit grade control. This is aimed at obtaining more representative samples, which are required to maximise ore recovery, minimise waste dilution and to increase the accuracy and confidence of production forecasts. Early in the project, it was realised that the key risks for implementing RC grade control were related to change management processes, rather than failure of technology. Recognising the importance of this issue, Mogalakwena chose an integrated implementation approach that incorporates all stakeholders of the mining cycle in order to develop a process that delivers maximum value and is sustainable within an active mining environment. The following core goals were addressed over five phases of project implementation: extensive definition and design of integrated project implementation, comprising: project buy-in and ownership from all key stakeholders, including survey, geology, mine planning, drill and blast, load and haul, maintenance, supply chain and finance; and detailed analysis of all potential issues and possible solutions, allocated to stakeholders as part of the scoping process; optimising hole patterns and drilling procedures, focusing on delivering maximum value for minimum cost using multiple scenario analysis from borehole data and operational sequencing requirements; and evaluation of lessons learnt during project implementation in order to optimise the technical solution and operational efficiencies. Although this project is not yet finalised, Mogalakwena Platinum Mine is already providing a blueprint for the effective development, implementation and optimisation of sustainable in-pit grade control RC drilling for other open pit mines within Anglo American plc.

Aug 22, 2011

By P J. Hawke, M F. Flis

The Hamersley Basin of Western Australia holds significant tonnages of detrital iron deposits. Formed by a cyclic weathering and eroding sequence of nominally barren banded iron formation, they may form rich proximal accumulations of iron cemented gravels distal from any obvious hard-rock iron mineralisation. While generally small, they nonetheless represent excellent economic targets as they are near surface and easy to mine. The relatively high density of iron detritals, when compared with their sedimentary hosts, makes the gravity method the primary method of exploring for these blind deposits. Identification of possible trap sites is used as a precursor to gravity surveying, with magnetics used as an ancillary method prior to drilling. Application of the gravity method in this terrain is not straightforward. Detrital trap sites are best developed next to the spectacular cliffs that form the range fronts to the Hamersley Ranges. Precise terrain corrections and use of first vertical derivatives are routinely applied to gravity data in an effort to map every possible gravity high that may reflect the presence of a detrital accumulation. Extensions to Hamersley Iron Pty LimitedÆs BS2D deposit were discovered by the routine application of gravity. This methodology has been used to create a model by which exploration for detrital deposits continue to the present day.

Jan 1, 2002