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By N J. Goodman

The HIsmelt technology was developed and proven in Western Australia (WA) after more than 30 years and several billion dollars of research and development. The HIsmelt technology was transferred to China and is now successfully operating at the Molong plant in Shandong Province, China using WA iron ore fines as the major feedstock. Several more plants are under construction in China, and the technology has been approved by the Chinese Government as an environmentally acceptable alternative to the blast furnace. The unique flexibility of the HIsmelt process offers multiple pathways to decarbonise the production of steel in the near future. These pathways include:  Use of sustainably grown biomass converted to Biochar to replace coal as the reductant.  Pre-reduction of iron ore fines using hydrogen or biomass to direct reduced iron (DRI) powder.  Capture of carbon dioxide from the HIsmelt off gas and geo-sequestration underground. These pathways are highly suitable for the Australian iron ore industry as they utilise:  The large areas of land and long growing season available in Australia for the production of large tonnages of sustainably grown biomass.  Coarse iron ore fines directly without the need for fine grinding and pelletising.  Existing oil, gas and other underground gas reservoirs to store carbon dioxide. The HIsmelt technology will allow Australia to transition from ‘Asia’s quarry’ to Asia’s supplier of low cost, low carbon and high quality metallics that are required to produce ‘green’ steel with net zero carbon dioxide emissions. In addition, HIsmelt pig iron can be converted locally into steel via electricarc or basic-oxygen steelmaking furnaces to supply all of Australia’s demand for green steel.

Nov 8, 2021

By E J. Hill, F Huang, A Otto

Geochemical data from drill core samples is used in mineral exploration to enable geologists to understand subsurface geology. However, it is challenging to analyse these data sets rigorously and consistently. Manual data interpretation relies on the knowledge and experience of logging geologists. When multiple geologists are involved, it is possible to introduce inconsistencies in logged lithology type and scale of logging (‘splitters’ versus ‘lumpers’). Machine learning (ML) is a powerful tool for analysing high dimensional data (ie data with many variables) and large data sets (ie data with many samples). However, ML methods applied to drill hole samples do not incorporate spatial information and this can result in high misclassification rates and small-scale ‘noisy’ results. We demonstrate the use of multiscale spatial analysis (wavelet tessellation) as a pre-ML step to analyse spatial information. This step helps reduce misclassification and filter out unwanted small-scale variation in the data. In an experiment, we used wavelet tessellation and supervised ML to predict litho-geochemical rock types from geochemistry data. The data set is from the Valhalla uranium deposit near Mount Isa, northern Queensland. First, geochemical knowledge and statistical analysis was used to select appropriate geochemical elements for litho-geochemical classification. Second, the elements were processed using multiscale spatial analysis. Third, we trained a Random Forest model with the data set and found that the model performs worse in predicting rare rock samples than common ones. We applied over-sampling and down-sampling methods in aim to overcome this issue. As a conclusion, the combination of multiscale spatial analysis (to define rock unit boundaries) and Random Forests (to classify rock units) is a good method for rapid and accurate analysis of drill hole geochemistry.

Mar 22, 2022

WaihiÆs Cornish Pumphouse is located on the edge of town in a dynamic and changeable area where history affects the future. As in any successful project, ingenuity and team work have been significant factors in the planning and implementation of the buildingÆs relocation.   Work around the Pumphouse site commenced circa 1900 with preparation to sink the No 5 shaft. Construction of the pumphouse and the steam driven C pump was completed by 1904 with hints of what was to come evident in 1905 as the No5 Shaft collar had sunk 350mm in four years. By 1907 surface cracking developed over the Milking Cow cave area and in 1913 200 mm was cut off the main pumping rod as the ground was sinking at a rate of 25 mm per year.   In 1913 ground around No 6 shaft had subsided 600 mm.It was also the end of an era as steam gave way to hydroelectricity and electric pumps replaced the C Pump. C Pump was maintained as a backup from 1913 to 1929 and then finally scrapped. 25 years of underground caving operations removed approximately 400 000 cubic metres of ore leaving a 7 ha collapse crater that eventually became known as the mine lake.   On the edge of town a tension zone over the Royal Lode began to develop 50 m diameter chimney collapses as large scale blocks relaxed into unfilled stopes in the old Martha underground mine. After the 1999 collapse part of the main street was closed and after the 2001 collapse Hazard Zones were declared, more streets closed and areas evacuated and retired from residential use.   By 1984 the Pumphouse has approximately one degree of tilt and in 2002 tilt on the Pumphouse accelerated briefly and then settled down. Tilt accelerated again late in 2004 and a scoping study was initiated to define protection options for the pumphouse. The Martha Mining Licence requires Newmont to 'Take whatever precautions are necessary to protect the old Cornish Pumphouse adjacent to No5 shaft' and viable solutions needed to found.   Any work on the Pumphouse comes standard with a wide range of stakeholders, governing agencies and legal framework to consider. Land Information New Zealand (LINZ) is owner and administrator of the pumphouse.

Jan 1, 2006

By H Kurth

"The focus of this paper is on measuring the composition to improve mill feed quality to minimise the processing of waste, optimise process performance, reduce processing costs and minimise the generation of tailings.Technologies used since the 1990s in the cement and coal industries for measuring conveyed materials have been operationally proven and effectively derisked. Despite this the acceptance by the minerals industry has been very slow except in iron ore. Real-time penetrative full stream measurement using prompt gamma neutron activation analysis (PGNAA) for multielemental analysis and microwave transmission for real-time moisture analysis provide representative, tonnage weighted dry weight per cent results on a minute by minute basis. Analysis is unaffected by particle size, dust, layering/segregation, mineralogy and belt speed. The technologies are explained and performance examples given. The benefits derived from real-time compositional analysis are predicated upon a good understanding of deposit geology, mineralogical associations, waste to ore interfaces, amenability to mining, metallurgical processes and downstream customer requirements. Processing may include basic preparation in the case of direct shipping ores, minor beneficiation using simple upgrading methods, or concentration using more complex processing systems such as flotation, leaching or many others. The value of real-time data from primary crushed conveyed flows, using analysis of increments smaller than a single haul truck’s load, is very beneficial in process plants aiming to reduce waste processing, increasing feed grades and increasing metal recoveries. Grade variability can be utilised to divert conveyed increments of waste, direct shipping ore (DSO) quality material bypassing beneficiation, and subeconomic material amenable to upgrading diverted for further preconcentration by particle separation (sorting, heavy medium etc). Paybacks of a few months have been commonly achieved where the real-time technologies have been applied in the minerals sector. The paper outlines proven applications and case studies and proposes some innovative applications.Citation:Kurth, H, 2016. Measuring and Utilising Ore Quality Variability Using Real-time On-belt Elemental Analysis to Improve Mill Feed Quality, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 239–244 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

EIA is a test of a development proposalÆs legitimacy and asks two questions: not only æis the proposal competent?Æ but also ædoes the proposal have moral authority?Æ For reasons of miningÆs historic importance and of a scientific and technological industry culture, traditional EIA has focussed on the first on these, an increasingly misplaced priority in a changing world.This paper explains why competence alone is not enough and examines the second of the two questions: what is meant by a projectÆs moral authority, why does it matter, why has it taken so long to become an issue and what, in practical terms, can project proponents do about it.

Jan 1, 2004

By P F. Hodkiewicz

"Our understanding of mineral resources relies on three basic steps: data capture data interpretation model construction. Until recently, all three of these steps required significant time and manual effort to produce a single resource model for mine planning, typically taking more than a year to progress from drilling to the final block model. Over the past several years, BHP Billiton has been developing innovative workflows in rapid resource modelling projects to significantly reduce these time constraints and make the process more productive by replacing manual activities with automated ones. Rapid resource modelling is the process of combining recently developed off-the-shelf technology with internal technology developments to fundamentally change the way we collect, interpret, model and evaluate geoscience data. Initiatives include automated systems and standardised workflows to make it safer, faster and cheaper to continuously update multidiscipline resource models. Specifically, rapid resource modelling workflows combine: real-time analysis of drill holes and drill samples with downhole tools and hyperspectral scanning systemsautomated interpretation of drill hole intervals based on pattern-recognition algorithmscontinuous modelling workflows using implicit modelling software. This paper outlines technology developments and workflows that provide a more thorough understanding of mineral resources to support faster and more informed strategic, planning and production decisions.CITATION:Hodkiewicz, P F, 2014. Rapid resource modelling – a vision for faster and better mining decisions, in Proceedings Ninth International Mining Geology Conference 2014 , pp 183–188 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By J Boshoff

The management and operation of tailings storage facilities (TSFs) are often neglected until the process plant has to shut down as a result of this negligence or as a result of a catastrophic failure as was the case during the recent TSF failure in North America.TSFs are often regarded as non-assets and do not receive the attention they deserve in terms of technical expertise and financial provision. A TSF is not a simple structure but a complex and dynamic structure that changes throughout its operational life. The operational life of a TSF is the period in which there is the greatest opportunity for risks to occur. The failure of a TSF is normally not as a result of a single event but as a result of a consequence of events. These events are often not recognised in time due to a number of factors.Process plants and slurry pumping systems are operated at suboptimal conditions in order to maintain throughput. At the same time, the tailings properties are compromised in terms of slurry density and particle size distribution amongst other things. Tailings deposition cycles and drying cycles are not well understood and the tailings management strategy is not well tuned in terms of maximising consolidation and improving in situ densities. Pond control is also neglected. These are aspects that form the keystone to the effective utilisation of available deposition area as well as the frequency and cost of future embankment raises.Apart from operational issues, forward planning in terms of budget requirements, increases in tailings throughput, embankment raises, pipe replacements, etc are normally put on the back burner. Available deposition space at the time seems to render this planning obsolete.The bottom line is that responsible tailings management and proper forward planning can limit liability and reduce the bottom line in terms of cents per ton if correctly implemented by suitably qualified tailings managers and engineers.The aspects that need to be considered as part of responsible tailings management are highlighted in this paper.CITATION:Boshoff, J, 2015. Responsible tailings management, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 317–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By D Carroll

Mining of the zinc, lead and silver deposit at the Broken Hill Southern Operations site has been occurring for over 100 years. As a result of this, a significant amount of high-grade ore is now taken from narrow remnant pillars left between old stopes and zones of previously mined ground. Stopes have been filled with either hydraulic fill (also known as ‘sandfill’), cemented hydraulic fill (cemented sandfill), waste rock backfill or a mixture of these fill types.In the last ten years, there has been considerable success mining through narrow pillars where sandfill is exposed in the development face and/or walls using a ‘shell’ support regime, wherein a layer of bolted mesh is sandwiched between two layers of sprayed fibrecrete (25 mm fibrecrete, then mesh and bolt, followed by a final 50 mm layer of fibrecrete). Shell support is also used in very poor, broken, relaxed ground conditions and in areas filled with cemented fill (sandfill with a minimum four per cent cement content).The next stage of innovation has been to develop a technique for mining through old stope voids filled with uncemented sandfill, known locally as ‘contours’ (old cut-and-fill working), an activity where unconsolidated sandfill can run at the face and from the backs. The challenge is to prevent exposed sandfill in the face and the backs from failing before it can be supported.To achieve this, the Southern Operations mine has implemented a technique in which 6 m long spiling bars are used to strengthen and stabilise the sandfill in front of the face. The hollow steel bars are driven in around the heading perimeter in a closely spaced pattern then pumped full of grout. The bars and the grout stabilise the sandfill in front of the face, preventing it from failing into the drive during excavation and prior to further support being installed.A final support system consisting of shotcrete, mesh, bolts and steel girders is installed as excavation progresses. Both the initial and final support systems are essentially passive support systems designed for a low-stress environment (as the stress originates mostly from the mass of unconsolidated sandfill).This process is slow and labour intensive. Fifteen separate cycles of people/machinery are needed to progress one equivalent heading cut (compared to six for a standard fibrecrete- and bolt pattern-supported rock face heading). This slow pace introduces scheduling challenges, but the process opens up parts of the orebody that were previously uneconomical to mine.CITATION:Carroll, D, 2014. Mining through sandfill using spiling bars, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 95–100 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By S F. Rogers, P W. Booth

Digital photogrammetry is revolutionising the task of geotechnical mapping of jointed rock masses and has greatly increased in popularity and sophistication in recent years. Modern commercially available digital photogrammetry software systems can provide geotechnical practitioners with a user friendly tool for rapid data acquisition. The data can be acquired remotely from large exposure areas, some of which may be otherwise out of reach due to restrictions on time, access or safety.Photogrammetry is a complimentary technology to discrete fracture network (DFN) modelling because it can provide the large, statistically significant, spatially located geotechnical data sets required to produce the most robust results. It also provides the flexibility to selectively map structures at a range of scales, depending on the focus of the DFN modelling.Integration of the interpreted rock structure data derived from photogrammetry with modern DFN modelling methods really advances the rock engineering process. The ability to generate 3D fracture models driven by the statistical structural data and conditioned to the features observed by the photogrammetry yields a synthetic rock mass on which improved design methods can be applied. The generation of multiple equi-probable conditioned DFN models allows the use of probabilistic methods for assessing kinematic stability, rock block size distribution as well as a range of other applications.CITATION:Rogers, S F and Booth, P W, 2014. Integrated photogrammetry and discrete fracture network modelling for improved rock mass characterisation and engineering design, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 203–208 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

Quay Magnesium Limited (QMG) listed on the Australian Stock Exchange in late September 2004 having raised approximately A$30 million with the object of designing, constructing, commissioning and operating a 15 000 tpa magnesium alloy production facility in Nanjing, China. Site construction commenced in February 2005, with installation of all major components completed by the end of October 2005. Hot commissioning was simultaneously commenced with the final stages of installation, leading to the first stage of continuous ingot casting by mid November 2005. Since that time, ramp-up to the name plate capacity has been undertaken. This presentation highlights some of the more significant technical and logistical hurdles that have had to be overcome in order to meet the high quality product specifications required by a range of QMG customers.

Jan 1, 2006

Tailings management trade-off studies are done for all mining projects. There is wide variability in these studies as their approach, details and outcomes are determined by the experience and focus of the project team. While some of these approaches may consider the whole life cycle of the project others may focus only on capital and operating costs and direct environmental impacts. A complete life cycle approach is not standard practice. This paper describes an approach to implementation of formalised life cycle assessment (LCA) following ISO 14044 to tailings management trade-off studies. The paper describes the implementation of the methodological framework for the LCA, ie goal and scope definition, life cycle inventory analysis, life cycle impact assessment and life cycle interpretation. This standardised approach to implementing tailings management trade-off studies following the LCA approach will contribute to the state-of-the-practice in sustainable mine development.

Jan 1, 2009

This paper reports the advances made during the development of underground mine fill technology from circa 1960 to the present and, in particular, indicates where increased input from process plant metallurgists û mainly milling, but also smelting û can contribute to further advances. Fill types pertinent to the discussion are partially deslimed, partially dewatered mill tailings fill (uncemented, cemented) and paste fill. Pertinent process plant includes hydrocyclones, thickeners, filters, elutriation tanks, holding tanks, mixing mills, pumps and pipes. Control instrumentation is a critical component of each of the process plant units. The impact of smelter practice on filling is not considered in this paper, except to note that some smelter slags are, or have the potential to be, active pozzolans and when ground to the specific surface area of Portland cement can act as partial Portland cement replacements, a factor of economic and operating significance when Portland cement supply lines are considerable and/or tenuous. The important role of process plant metallurgists has long been recognised, with Thomas, Nantel and Notley (1979) including them as one of the many categories of professionals with contributions to make. With the ever increasing sophistication of mine fill practice and its ever increasing acceptance as an essential component of the mining/ milling/waste disposal process, the scope for contributions by the modern breed of highly educated, specifically trained process plant metallurgists is becoming ever increasingly obvious.

Jan 1, 2006

The new law on Environmental Protection and Management (Republic of Indonesia Law 32 of 2009) was passed by the Indonesian parliament in September 2009. This law aims to protect Indonesia's rapidly degrading environment by providing tougher provisions for both polluters and law enforcers. In doing so, the law introduces a number of new constraints and potential business risks that will affect all companies in Indonesia, particularly mining companies. Some of the newly introduced concepts follow.   Mining companies will now require an environmental license, issued by the Minister of Environment or local counterparts. This license is a prerequisite for all other business and operational permits. The Minister can revoke the environmental license at any time in case of an environmental incident or dispute. Mining companies may be exposed to additional environmental taxes and bonds besides already existing reclamation and mine closure bonds.   There is an increased risk of environmental lawsuits, due to more stringent controls on one side and greater protection for NGOs on the other side who make claims, false or true, against the company. Company executives and managers can be sued and they will be held accountable if environmental degradation has indeed occurred due to the company's activities.   Companies may face increased liabilities due to a change in the definition of contamination. The new definition is more stringent (and on occasion may prove too stringent to be practical); it also provides little room for flexibility in its application.   As implementing regulations are prepared over the coming two to three years, mining companies will need to adjust to the new law. A proactive approach is needed to minimise risk. Recommended actions include: upgrading existing environmental impact assessments to a higher standard; conducting baseline studies and thoroughly documenting environmental conditions on a regular basis; closely tracking regulatory changes, especially the forthcoming implementing regulations on the new environmental law; and regularly engaging key government and community stakeholders on environmental issues.

Jun 1, 2010

By J Berg, M Hahn, R Winkel

Imaging sensor systems designed for the mining and minerals industry incorporate different physical measurement technologies that can be used to detect the machine environment, such as laser, ultrasonic/sonar, video and RF-sensors. The underlying physical measurement principles cannot be employed in most applications near the face without regular maintenance due to the harsh environmental conditions like dust, dirt or moisture. However, that is the area, where imaging sensors are most valuable to the machine operator. In the domain of 2D radar sensors these have been either restricted by the angular coverage area or by limited adaptability of signal processing algorithms. The unique full digital solid state design will establish a generation step in mining applications.In order to fill this gap of terrain imaging sensors, the Institute for Mining and Metallurgy Machinery (IMR) of the RWTH Aachen University, in cooperation with the radar company indurad, developed an imaging sensor based on radar technology employing the digital beam forming (DBF) concept. Through multiple transmitting and receiving antennas the sensor delivers high accuracy range and angular information. Using adaptive digital signal processing with multiple imaging algorithms and target detection routines, data of the surrounding environment can be used to enable automation functions in mining.A comprehensive range of radar scans in different environments have been evaluated and benchmarked by using laser scanners. Accuracy measurements in range and angular direction have shown minimal differences. Experimental measurements have been performed at slopes, on conveyor belts and hot cement clinker silos. The experimental system uses a frequency modulated continuous wave (FMCW) front-end combined with a processing unit for signal analysis and target detection.

Sep 26, 2011

By B Beale

Bow-tie analysis is a commonly used tool to identify and display risks that have the potential for an undesired hazardous event. The output of the analysis are bow-tie diagrams, which are an effective and versatile communication format that can be applied to any type of risk. Contrary to their simplicity, a proper bow-tie diagram that maintains its usefulness and clear communication is difficult to build. Over two decades assisting Major Hazard Facilities with bow-tie analysis for Safety Cases, several common mistakes have been identified. This paper aims to highlight those issues with examples and provide improvement strategies. A sample of the most common mistakes are: - overly complicated risk analysis - poorly scoped and defined terms - poor descriptions and justifications - identifying too many dependent controls. Overly complicated risk analysis leads to wasted time in obtaining data for little gain. The bow-tie diagram is only a model. Effort should be redirected into identifying and managing controls that will make a tangible difference to site risk. Broad scopes lead to enormous and confusing bow-tie diagrams for both the user and the workshop team. Defining the scope of the study, the consequence severity of interest and critical control characteristics creates focused workshops and targeted analysis. With more definitive scope, there may be more bow-tie diagrams, however, they are succinct and specific. Well described causes are imperative for clear communication to users, regulators and future bowtie review workshop groups. It is best to use common wording structures and explain the event stepby- step. Also, clearly document any likelihood calculations and use data references where applicable. Identifying all possible controls creates a false sense of security that there are many layers of protection. In reality, most controls are dependent on a single system or person and could all be compromised from a single failure. A definition of a ‘bow-tie’ control is required whereby it must be independent from other controls. Improving the bow-tie analysis process will assist operators in developing meaningful and ‘operational’ bow-tie diagrams to support risk management systems and practices.

Apr 16, 2024

By M Jones

Legacy tailings storage facilities exist within operating mine sites across Australia. These tailings storage facilities are often viewed as rehabilitation liabilities but with considered assessment may prove to be a resource. Extraction of such a resource might add value to operations by providing cash flow during the development of new mines; providing supplementary mill feed for existing mines undergoing step changes in operations; and supporting mine closure activities. Hellyer Gold Mines is successfully extracting and reprocessing sub-aqueous material from legacy tailings storage facilities at their Hellyer operation in north-west Tasmania. The Hellyer tailings storage facilities contain poly-metallic material from the Hellyer and Fossey underground deposits dating back to the 1980s as well as material from tailings reprocessing activities by other operators of the Hellyer site. Hellyer Gold Mines is reclaiming sub-aqueous material using cutter-suction dredgers and reprocessing on-site. Hellyer is the only operation of its type in Australia and few such operations exist worldwide. Key learnings around the estimation of a resource for legacy tailings storage facilities have been acquired at Hellyer that can be applied to the assessment of other tailings storage facilities. The application of dredging as a mining method at Hellyer is delivered through collaboration with experts from outside the mining industry under the direction of a mining engineer. Key elements required for the planning and delivery of safe and efficient dredging inside tailings storage facilities have been identified at Hellyer and are presented to provide a road map to the development of other dredging operations.

Sep 1, 2024

By M Barkh, F X. Spachtholz

The mining industry faces significant environmental challenges in managing tailing ponds and wastewater treatment, including the risk of contaminated water, breaches of tailing dams, and energy-intensive treatment processes. Traditional methods involve pumping water to secondary treatment facilities for neutralisation, which is costly and poses operational and environmental risks. In response to these challenges, the Professional Mine Water Action Plan (PMAP) introduces a revolutionary approach that combines cutting-edge AI technology and environmentally friendly reagents for in situ neutralisation of acidic wastewater. PMAP leverages magnesium-based slowrelease reagents and AI-driven intelligent dispensing systems to optimise treatment processes within the tailing pond itself. The unmanned smart dispensing vessel (USDV) conducts bathymetry to gather data on water quality and hydrography, allowing the system to determine the appropriate reagent quantity and injection strategy. This approach transforms the tailing pond into virtual reaction columns, enabling individual and simultaneous water treatment while optimising efficiency. PMAP’s novel reagent demonstrates exceptional efficacy in removing critical metals like cobalt, nickel, and copper, as well as reducing harmful metals such as mercury and manganese to undetectable concentrations. Unlike traditional lime-based treatments, PMAP’s reagent prevents gypsum formation and reduces waste volume significantly, improving reagent utilisation and solid waste handling. Furthermore, PMAP technology offers benefits beyond environmental stewardship. By reducing water treatment costs and improving resource management, it enhances operational efficiency and aligns with broader corporate sustainability goals. Additionally, PMAP expedites permitting processes by eliminating the need for traditional water treatment infrastructure and mitigating risks associated with hazardous reagent transportation. Integrating PMAP as a pre-treatment for existing lime facilities provides further benefits, including optimisation of treatment operations, reduced reagent consumption, and the recovery of valuable metals from generated sludges. Overall, PMAP represents a groundbreaking advancement in mining wastewater management, showcasing the transformative potential of AI and environmentally friendly solutions to foster sustainable and responsible mining practices globally. Its inaugural project in the Yukon Territory aims to demonstrate its capability to remove contaminants from mine water, paving the way for widespread adoption in the industry.

Sep 1, 2024

By P Odins

Traditionally, stratigraphic deposits have been represented by a large number of gridded surface and product analytical models, related to each other by naming convention. This approach, though suitable for structurally simple stratigraphic deposits, does not lend itself well to addressing the complex style of stratigraphic deposits which are becoming more prevalent. In addition, the sheer number of individual gridded models involved makes it very difficult to keep a consistent audit trail of the overall deposit model. Recently, a new enhanced block model structure known as Horizon Adaptive Rectangular Prism (HARP) models was introduced to address these issues. An HARP model is specifically designed to allow stratigraphic units to be represented with virtually no loss of structural integrity, by allowing the tops and bases of the individual HARP blocks to ‘bend’ in concert with the input surfaces. By bringing together the best of grid modelling, triangulation modelling, block modelling and grade estimation, the HARP model opens up many exciting new opportunities for the stratigraphic geologist or engineer to take their model further than was previously possible. Examples of improvements in modelling methodology using a HARP model include: the ability to represent complex normal, reverse and thrust faulting; the ability to store thousands of additional analytical, geotechnical or calculated variables in each individual block; advanced visualisation, manipulation and plotting capabilities; and the ability to calculate volumes and resources against complex, three-dimensional (3D) solid pit designs. Finally, several ‘real world’ scenarios, illustrating how this advancement in modelling technology can benefit a wide range of mining professionals are detailed. These examples demonstrate how productivity gains can be made in both long-term resource modelling and short-term ‘week by week’ geological modelling as an adjunct to mine planning.

Aug 22, 2011

By T Vizcarra, G Sandoval, C L. Evans

One of the challenges in the development of mineral processing simulators is modelling the liberation characteristics of particles produced by comminution circuits. Understanding the mineral characteristics of these particles is one of the keys to predicting their behaviour in separation circuits. While more fundamental research seeks to model the non-random breakage of ores this work examines whether we can move forward now by using observed characteristics of ores to model the composition of particles generated in comminution processes. Several researchers have noted the similarity of the liberation characteristics for a selected size fraction of particulate material, whether the fraction comes from a coarse material, such as the product from a jaw crusher, or a more finely ground material, such as the product from a ball mill. In most cases these observations were reported as an aside and were not the main focus of the published work. This observed behaviour has the potential to be a useful tool for modelling the particle characteristics in mineral comminution and separation circuits, particularly as we move towards the development of multi-component models. However, before the behaviour can be used widely we need to understand which ore types follow the observed pattern and which do not. The current work examines a range of ores and identifies which exhibit the pattern of similarity of composition for particles in a given size class that has been produced as the result of a variety of breakage conditions. The impact of mineralogy and texture on the evolution of liberation characteristics for both valuable and gangue minerals is discussed.

Jan 1, 2008

By J D. Bryant

The Ernest Henry Copper-Gold mine, the third largest copper deposit in Australia, is located 35 km NE of Cloncurry in the Mt Isa-Cloncurry mineral district of NW Queensland. Ernest Henry Mining Pty Ltd (EHM), a wholly owned subsidiary of Xstrata Copper Australia, operates the mine. Approximately 10.2 Mt of ore grading 1.12 per cent Cu and 0.56 g/t Au were processed during the 2001 - 2002 financial year. The Ernest Henry plant produces copper-gold concentrate, which is trucked to Mt Isa for smelting. The Ernest Henry deposit is a member of the diverse Fe-oxide-(Cu-Au) class of deposits. The orebody is hosted within a sequence of moderately SSE-dipping, intensely altered Paleoproterozoic intermediate metavolcanic and metasedimentary rocks. Copper (chalcopyrite)-gold mineralisation occurs mainly within the magnetite-biotite-calcite ¦ pyrite matrix of a 250 m + 300 m pipe-like breccia body. The breccia pipe comprises two anastomosing lenses separated by a lower grade, clast-supported breccia zone. Several anastomosing brittle faults affect the macro-geometry of the orebody. Copper grade is proportional to the degree of matrix support in the breccia. The July 2002 Ore Reserve was 88.7 Mt @ 1.0 per cent Cu and 0.5 g/t Au. Resource estimation at Ernest Henry is based on a large database of predominantly diamond drill hole information. Drill spacing is typically 50 m + 50 m. Ordinary kriging is used to estimate Cu, Au, SG and IST (oxidation indicator) into model parent cells of dimension 20 m E + 20 m N + 16 m RL. The block model is comprised of five geological-geochemical domains represented by 3D wireframe surfaces. Zonal control, where samples and blocks are assigned the same domain number, is used to control grade estimation. The geometry of the domains defines hard grade boundaries across strike and soft boundaries along strike A Deep Drilling Project was initiated in August 2002 with the initial aim of testing the down-plunge extension of the orebody to a vertical depth of over 1 km. The encouraging intersections to date have resulted in a significant increase in the mineÆs open pit Mineral Resource together with the identification of an underground Mineral Resource. Added benefits of the project included an expanded and updated geological legend and an improved understanding of the host geological sequence.

Jan 1, 2003