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By G Fahey, S Rose

"Mining geology as a defined profession is only about 100 years old. The successful modern mine geologist needs to be a multidisciplinarian, but also needs to maintain a focus on the key outputs of the role. The technical skills needed in the role have increased as mining methods move to increasingly mechanised techniques. As well as being the guardian of the orebody and ensuring minimal dilution to expected ore grades, the mine geologist should be competent in the 12-point mine geology process. The mine geology process should include:a statement of purpose (a ‘mission statement’)geological mapping/logging system that supports consistent and regular geological data collection, storage, and interpretationsampling system that can produce representative samples and fits in with the mining scheduleassay database with relevant controls to ensure only ‘clean’ data is loadedsimple quality assurance / quality control (QA/QC) system for samples and assays, with a response process to react to out of specification resultsconsistent method of exporting, visualising, processing and interpreting assay data to create mining blocksdevelopment sign-off system so that all development and stoping is controlledproduction tracking system to monitoring and reporting what ore and waste volumes have been moved from the face, to any intermediate stockpiles, the run-of-mine (ROM) pad and into the crusherreporting system for daily, weekly and monthly reporting of tonnes and gradesdocumentation so that the grade control system has simple, but effective descriptions of how it works, who has responsibilities, and authorities, and be easily maintainedreconciliation system to compare resource and reserve to grade control and to mined and milledtraining system so that the geology team can quickly become competent.In this paper, the authors discuss the requirements of each point, and comment on common shortfalls observed by them over several years’ experience on producing mines worldwide.CITATION:Rose, S and Fahey, G, 2014. Modern mining geology, in Proceedings Ninth International Mining Geology Conference 2014 , pp 461–466 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 18, 2014

By K Grohs, A Satriawan, S R. Pearce

Martabe gold and silver mine is operated by PT Agincourt Resources (PTAR) and is situated in northern Sumatra and comprises several deposits in steep terrain, and in a tropical climate, that are required to be developed in the optimal sequence for the best possible Net Present Value (NPV) return on the project. In addition, the waste rock from excavations and tailings from processing is a by-product to be scheduled and used for a number of purposes identified as part of life-of-mine planning. These uses include construction of the current integrated tailings storage facility (TSF) as well as future engineering construction and waste disposal projects which includes plans for a program of in-pit backfilling. These plans need to be aligned to ensure the waste rock and tailings can be contained relative to the production rate. Given that the site will have multiple open pit voids upon cessation of mining activities opportunities for integration of in-pit disposal of mine waste have now been assessed with technical studies to review the practicality of the approach with respect to operational challenges and conformance with closure planning requirements. This includes assessment of disposal of waste rock, tailings (including consideration of filtered tailings) and co-disposal of waste rock and filtered tailings.

Aug 2, 2023

By D McCoy

Titanium feedstocks are the building blocks of the titanium value chain. They can be mined directly, as is the case for ilmenite, leucoxene and rutile, or manufactured from ilmenite by extracting various quantities of non-TiO2 components from the ore by chemical and/or thermal processes.While feedstocks can be grouped into categories of materials with similar characteristics, they are essentially unique products from very different mining locations around the world. In fact, no two feedstocks are exactly the same. As such, the variations between the available feedstocks, in combination with the permutations in processing technologies to turn the feedstocks into titanium pigment or metal, mean that choices between feedstocks are specific to the location in which they are utilised.In this paper, the authors examine the key requirements of titanium feedstocks to the TiO2 pigment and metal sectors. Apart from the well known differences between feedstock choices for the sulfate and chloride process, the more opaque considerations in feedstock sourcing are examined.

Oct 5, 2011

By A N. Parry, G van Wyk

"Sensor based automatic ore sorting technologies are used in the minerals industries to efficiently remove waste and submarginal grade material from crushed and screened run-of-mine (ROM) ore, producing a coarse (typically >10 mm) upgraded preconcentrate at an early stage in the mineral processing circuit. This avoids additional energy intensive downstream processing of this rejected component of the ROM feed, leading to lower unit operating costs and reduced tailings disposal volumes.Test work on bulk low-grade gold ore stockpile samples from Central Norseman Gold Proprietary Limited has been conducted, indicating high gold recoveries as well as high material rejection rates. A financial model, based on these results, evaluates grade sensitivity and identifies a minimum stockpile grade for adequate financial returns. The base case modelling estimates that the ex-stockpile grade (including the fines bypassed fraction) can be more than doubled through ore sorting and that the project will be highly viable with strong cash flow generation at stockpile grades as low as 0.7 g/t gold. The modelling will enable the company to benchmark ore sorting options against stockpile reclaim and screening operations currently employed. Citation:Parry, A N and van Wyk, G, 2016. Upgrading Low-grade Gold Ore Stockpiles by Preconcentration Using Ore Sorting - an Assessment of the Economic Impact and Viability, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 179–190 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By L MacDonald, D Molver, D Pepper

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

Nov 21, 2018

By A M. Ebbels, D Pratt

The current commodities super-cycle has seen an explosion in the number of mining projects demanding human resources throughout the world. The demand for key personnel currently far outweighs the international talent pool and will take several years to subside. A highly effective project team can be the difference between a successful project and a bad public relations exercise. Building an effective team and retaining the team members has become one of the major influencing factors for successful project development in the mining industry in the last decade.Increasingly, international teams are being established combining skill sets, subject matter experts, unique previous experiences and diverse cultures to deliver mining projects all around the world.This paper explores the characteristics of a highly effective team, the communication and geographic challenges and some potential pitfalls which influence the ability to form effective teams within the mining industry.CITATION:Ebbels, A M and Pratt, D, 2012. A great project team - Bringing together location and culture, in Proceedings Project Evaluation 2012 , pp 197-202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

By C G. Sweeney

The underground mining industry is seeing unprecedented shortages in skilled labour. Migration to Australia being at an all-time low is a leading concern, with pandemic-induced border closures and lockdowns only exacerbating the skills shortage, not causing it. The skills shortage is forecast to peak in 2023 and remain high beyond 2025. With this skills shortage in mind, mining companies throughout Australia are trying to deal with stricter protocols around Health and Safety (H&S) legislation, as well as more stringent controls on quality assurance, particularly as underground mines are reaching greater depths and extending into ‘unchartered territory’. The cumulation of this is proving to be a major hurdle in ‘effective’ operational geotechnical management. The drive for automation in mining is bringing another level of complexity. However, ‘once automation is up and running, it presents the opportunity to access talent pools that may not normally be available. There is also a change in skillset that will be required to drive automation. ‘The top two emerging roles that will be critical for the future of the mining industry are artificial intelligence and machine learning (AI/ML) specialists, and process-automation specialists’ (Writer, 2021). If anything positive has come from the pandemic, it has shown that remote working can be effective and that the drive for automation and critical evaluation of skills required on-site should be given greater priority. UQ acknowledges that the industry is changing, and that digital technology is required to be offered in mining related disciplines. Industry and academia need to do more to promote geotechnical engineering in mining and balance the curriculum to suit the future of mining and make it more enticing. The average cost of a geotechnical failure is about $5 million in coalmines and can be into the hundreds of millions of dollars if production is affected (Cartledge Mining and Geotechnics, 2020). The cost of a good geotechnical design far outweighs the potential losses if a failure were to occur. This alludes to the growing importance of experienced geotechnical consultancies playing a pivotal role in managing mine site geotechnical hazards, while the industry is developing the next generation of geotechnical engineers.

Nov 29, 2022

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

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

Nov 21, 2018

By M L. Muller, A R. O’Donnell

The Mount Isa Mines (MIM) Copper Concentrator has an extensive history of reagent trials, with different reagents coming in and out of favour over the years. The research and use of carbon depressants is particularly prevalent, as carbonaceous pyrite is a major source of concentrate dilution. Years of research led to the use of naphthalene sulphonate due to its excellent carbon depression properties. However, due to rising reagent costs carbon depression ceased in the late 1990s. This led to the loss of knowledge about the use and value of naphthalene sulphonate. Cyanide is used at the Copper Concentrator for the sole purpose of pyrite depression and over the years multiple projects have been devoted to finding alternatives to it. In 2012 the neighbouring MIM Lead-Zinc Concentrator replaced cyanide with naphthalene sulphonate which resulted in cost savings and the elimination of a hazardous reagent. In 2013, plant trials were conducted at the Copper Concentrator in hopes to replicate the outcomes obtained at the Lead-Zinc Concentrator. The results of the trials conducted at the Copper Concentrator showed that naphthalene sulphonate could not replace cyanide and this work was set aside to pursue more promising projects. Further research conducted in 2014 found that mineralogy and a better understanding of the depressing mechanism of naphthalene sulphonate held the key to improved pyrite depression at the Copper Concentrator. The findings showed that Mount Isa copper ore contains two forms of pyrite; euhedral pyrite (cubic pyrite) and framboidal pyrite (carbon rimmed spheres of pyrite), both of which require different reagents to sufficiently depress them. Naphthalene sulphonate was found to be an excellent carbon depressant, suitable for depressing graphite and framboidal pyrite, whilst cyanide specifically targets euhedral pyrite.In 2015 laboratory test work was conducted to examine the use of naphthalene sulphonate in conjunction with cyanide to selectively target both forms of pyrite. This work led to a full plant trial, the results of which showed a significant increase in plant performance, with higher copper concentrate grades and recoveries being achieved. This paper aims to focus on the benefits and importance of understanding past work and linking a detailed knowledge of feed mineralogy to reagent selection for improved plant outcomes.CITATION:O’Donnell, A R and Muller, M L, 2018. Selectively targeting hydrophobic gangue minerals at the Mount Isa Mines Copper Concentrator, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 413–421 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By A Llewellyn, M Varvari

The ventilation circuit at the FrogÆs Leg Mine was originally designed to permit mining to progress down to 440 m below surface at a maximum production rate of 500 kt/a, as per the feasibility study. The FrogÆs Leg resource has now been defined down to 640 m below surface at a maximum production rate of 750 kt/a. In order to allow for this increase in production depth and tonnage, it was necessary to upgrade the ventilation circuit.This paper outlines the upgrades to the ventilation circuit that were undertaken and the underlying rationale behind them.CITATION:Llewellyn, A and Varvari, M, 2013. Ventilation upgrade at the FrogÆs Leg Mine - Case study, in Proceedings The Australian Mine Ventilation Conference , pp 95-102 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By K Banerjee, C Dube

Veolia Water Technologies was contracted by a global coal mining company to design a retrofit acid mine drainage treatment facility using DenseSludge™ technology on a former coal refuse disposal site. The project constraint was to reuse current facilities in order to reduce additional capital work cost and avoid additional footprint requirements while improving treatment performance and reducing sludge production and chemical consumption. The initial installation of 454 m3/h served as a pilot plant to demonstrate the benefits of the process and ultimately provided design criteria for the new facility. The pilot demonstrated the benefit of the technology by reducing sludge volume by 90 per cent compared to conventional processes currently in use. The sludge that is reinjected into the mine contains less water, which reduces the volume of water that returns to the mine pool for treatment and mine water balance. Furthermore, the pilot plant reduced lime usage compared to conventional processes by operating at a lower pH set point, demonstrating steady pH control and stoichiometric lime utilisation.CITATION:Dube, C and Banerjee, K, 2015. Sludge conditioning technology to reduce sludge and the cost of acid mine drainage treatment, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 105–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Nikaido M, Kanda Y

A rotary type separator has been developed which separates particles on the basis of their shape. This separator was applied to a particle size range of about 50 - 120 ¦m, and to our present knowledge may be the smallest size range ever to be separated. A theory of the separation is given based on the difference of an adhesive force of the particles: the adhesive force between spherical particles and plate is more powerful than that of irregular shaped particles for the same particle size. These facts have been ascertained by the measurement of an adhesive force by a centrifugal method. US and Japanese patents have been obtained on this separator, which consists of a borosilicate glass cylinder of 150 mm outside diameter, 120 mm in width, and an AC electromagnet. The samples used in this study were mixtures of spherical glass particles and non-spherical shaped glass particles. The results are summarised as follows. In the case of mixtures of spherical particles and irregular shaped particles in the weight ratio of 1:1, the spherical content of the spherical product became 70 per cent - 75 per cent, and in the case of 3:1, the content became 87 per cent - 90 per cent, as the result of one separating operation. However, for a mixture of somewhat rounded particles and irregular shaped particles of weight ratio 1:1, the rounded content varied between 58 per cent - 73 per cent. The feed rate of the particles mixtures was about 0.3 g/min. Newton's Efficiency was 20 per cent - 60 per cent. The separator may find application in shape separation of ceramic powder, metal powder or industrial diamond powder.

Jan 1, 1993

By J Seccatore, T Marin, M Cardu, G De Tomi, F Galvão, A Rezende, E Melo

Small-scale mining operations are characterised by a large variety of equipment availability and a high level of operational flexibility. Mine planning is usually scarce or absent in small quarries in Brazil, and mine management generally focuses on daily operations. As a result, analysis of the effects of unit operations, such as blasting, over the whole mining process is often neglected. The goal of the following project was to study the effect of production blasting on loading and hauling times, secondary breaking times and primary crushing times at the Experimental Mine of the Research Center for Responsible Mining of the University of São Paulo, Brazil. The operations analysed included blasts that performed:under the average operational standard, defined in this paper as Case 1according to quarry standards, defined in this paper as Case 2.In order to establish the effects of blasting on the downstream process, three key performance indictors were used:The time taken to load the truck, when there is the need for material selection. Due to the fact that we do not have an operational baseline, the increase in time cannot be established, meaning that we must content ourselves with comparing the mean time in each scenario.The average time used for secondary breaking machinery.The time required for the primary crusher to fully process the load of a single truck. The results obtained indicate correlations between the coarseness of the blasted material and these operational times. Solutions are suggested and evaluated for the improvement of the small-scale mining process.CITATION:Marin, T, Melo, E, Seccatore, J, Cardu, M, Galvão, F, Rezende, A, Bettencourt, J and De Tomi, G, 2015. The effect of drilling and blasting performance on fragmentation in a quarry and time for loading, secondary breakage and crushing, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 355–362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Ore textures in Australian BIF-derived ores are quite complex and have formed the basis for ore genesis models, which includes hypogene upgrading or supergene upgrading then regional metamorphism for the microplaty hematite ores and supergene upgrading for the martite-goethite ores. Despite a high level of ore texture knowledge, little is known about the spatial distribution of ore textures within deposits or their relationship to downstream processing. This paper describes a new iron ore texture classification system to better understand the vertical textural zonation characteristics of Australian BIF-derived deposits, the interpreted role of recent supergene upgrading processes on modifying primary ore textures and their implications for downstream mineral processing. The iron ore textural classification scheme presented uses textural groupings defined on the basis of similarities in mineralogy, ore texture, porosity, mineral associations and hardness. The scheme is non-genetic and has been successfully applied to deposits in the Pilbara, Yilgarn and Gawler cratons. The main ore texture groups include dense martite/hematite, microplaty hematite, microplaty hematite-goethite, martite-goethite, goethite-martite and goethite-rich. Each group can be further subdivided into physically hard to softer subcategories. The ore textural groups can be divided into those interpreted to be associated with primary replacement of BIF and secondary textures resulting from more recent modification by near-surface hydration or dehydration processes. A schematic vertical section through BIF-derived deposits consists (from surface) of detritals underlain by a carapace, both of which may have been eroded, followed by a hydrated zone with replacement of primary ore martite and microplaty hematite by vitreous goethite. The hydrated zone is underlain by 0.2 - 6 m thick zones of intense dehydration and textural infilling of porosity with hematite and hydrohematite. Immediately below the dehydration zone is a strong zone of leaching, where more porous and friable ore textures occur, followed underneath by a gradational contact with primary ore. Secondary supergene processes can impact on beneficiation with hydration and leaching resulting in more difficult density separations at the concentrator stage due to reductions in density differences between ore and gangue and loss of heavy media into pores. Supergene modification of primary BIF-derived ore textures can substantially change lump metallurgical properties, with hydration and dehydration favourably increasing lump yield but reducing resistance to thermal shock whilst leaching will give the opposing outcome. The lump properties of ore textural groups appear to be relatively consistent within and between the iron ore deposits examined.

Jan 1, 2002

By M Zhu, G Tranell, N Simkhada, K Jakovljevic, M Wallin

Silicon is a vital element in many products today, such as electronic components, solar devices, high-quality alloys, and many others. The growing global demand highlights the need for the development of sustainable production methods to meet this demand as an alternative to the current carbothermic reduction, submerged arc furnace (SAF) based process. An alternative to this is the aluminothermic reduction of quartz in a CaO-SiO2 slag, which not only reduces direct carbon dioxide emissions but also promotes the utilisation of secondary raw materials such as quartz fines, aluminium dross and scrap as well as secondary alumina (SA) from dross recycling. In the current study, the effects of SA and CaF2 additions to slag on the resulting metal composition and metal yield were explored. Results were compared with thermodynamic simulations using FactSage™ 8.1. Experimental results show that, in agreement with thermodynamic simulations, the silicon content of the alloy is increased, while the Ca is decreased for starting slags where CaO-SiO2 is partly replaced by CaF2. Similarly, the addition of SA to the initial slag results in an alloy with a higher silicon content.

Jun 19, 2024

By M Salu

Ventilation control devices (VCD’s) and bulkheads are critical controls used for managing risk in underground coalmines. Following the Moura No. 2 mine explosion in 1994, the Queensland Mines Department required that the design of VCDs be based on live testing (such as in a mine testing explosion gallery) and more recently on numerical modelling using measured seal material properties. While the stipulated methods represent an idealistic solution, they are not practical to implement as solutions to daily challenges presented in underground coalmines.Not all VCD’s and bulkheads are placed in areas which have been mined to standard roadway dimensions. Operationally, VCD’s may be required to be placed close to intersections or require large dimensionally different areas (eg overcasts and pre-driven recovery road shutters) compared to the live testing or numerical modelling originally undertaken.This paper describes the various structural engineering methods utilised to account for the design of VCD’s where the operational requirements are non-standard. Siting and construction of VCD’s near the entry of cut throughs and geological structures requires additional design considerations. While VCDs constructed from a single material (eg sprayed mining plaster) are relatively straightforward to design, the addition of multiple openings (doors) or large pipes will complicate the structuralanalysis significantly.Temporary bulkheads used for the containment of grout such as for the construction of pre-driven recovery roads in coal mining have a significantly different risk profile to VCDs and should be designed accordingly. Recent failures and near-misses in such bulkheads have highlighted this issuefor the authors.The existence of an Australian Standard for Underground Mine VCDs and Bulkheads would go a long way to addressing many of the issues raised in this paper. Without a single, industry-accepted reference for VCD design, individual mines will have to continueto exercise their best judgements using whatever local expertise is available to them.

Oct 12, 2022

By B Firth, G OÆBrien, B Jenkins

In coal flotation, particles of different components of the coal such as maceral groups and mineral matter and their associations have different hydrophobicities and therefore different flotation responses. By using a new coal grain analysis method for characterising individual grains, more detailed flotation performance analysis and modelling approaches have been developed. The method involves the use of microscopic imaging techniques to obtain estimates of size, compositional and density information on individual grains of fine coal. The density and composition partitioning of coal processed through different flotation systems provides an avenue to pinpoint the actual cause of poor process performance so that corrective action may be initiated. The information on grain size, density and composition is being used as input data to develop more detailed flotation process models to provide better predictions of process performance for both mechanical and column flotation devices. A number of approaches may be taken to flotation modelling such as the probability approach and the kinetic model approach or a combination of the two. In the work reported here, a simple probability approach has been taken, which will be further refined in due course. The use of grain data to map the responses of different types of coal grains through various fine coal cleaning processes provided a more advanced diagnostic capability for fine coal cleaning circuits. This enabled flotation performance curves analogous to partition curves for density separators to be produced for flotation devices.

Jan 1, 2005

By C Jacobsen, N Harries

Assessing and managing instability hazards is an essential activity when working with unstable natural slopes and excavated open pit mining slopes. Slope monitoring has become the standard technique for the management of geotechnical risks associated with mine slope instability hazards. In recent decades, a proliferation of new monitoring techniques such as terrestrial radar, satellite InSAR and LIDAR have become standard operational tools, complementing conventional survey-based monitoring solutions. A reliable monitoring system should identify and record incipient anomalous slope movement. Although the most obvious purpose of a monitoring system is safety related, slope deformation and performance monitoring also enhance the understanding of slope behaviour and assists in improving system design and implementation. For a monitoring system to be considered an effective early warning tool, it needs to operate in real-time and should be linked to the mine’s emergency communication systems. Terrestrial radar systems have been developed that can provide near real-time measurements, at a high level of precision and covering broad areas in all weather conditions. This has had a positive impact on the management of geotechnical risks in operational conditions. The technology adoption of RADAR in mine monitoring has significantly progressed in the last 20 years from technology enthusiasts, to visionaries, to pragmatists to conservative users. However, the increasing adoption of RADAR cannot reduce or remove other monitoring techniques that often have important benefits; even if these technologies cannot be used as a real-time operational tool. An increasing awareness on the importance of combining data from different monitoring techniques to develop a holistic picture of all possible geotechnical hazards is a current industry trend. This is proving to be an excellent foundation for managing hazards associated with slope instability in open pit mines, and is only expected to improve with time with the adoption of new technologies based on big data and Artificial Intelligence (AI).

Nov 29, 2022

By T Purvis

Xstrata Copper is extending the Ernest Henry Mine with a 6 Mtpa sub-level cave (SLC) mine being constructed under the pit. The SLC mine will maintain the EHM operation until 2024 after the pit is completed in August 2011. In February 2008, the first cut of the new underground mine at EHM was fired with the start of an exploration decline. Since then Xstrata Copper has continued the development and construction of a SLC mine. During this process a number of challenges arose, some of which had not been anticipated in the planning stages, that in turn has been addressed to ensure the development continued. The challenges have been many and varied and range from setting up the portal area and commencing the exploration decline development in an active large open pit, to management of underground water. Further challenges were presented by the effects of the GFC on investment recommendations, with the scale of the mine varying from a shaft mine to a smaller scale trucking only mine in mid-2009 and back to the full shaft mine in late 2009. The effect was the parallel development of two separate mining scenarios, with the challenge of maintaining commonality for as long as possible to keep both options alive until the final board approval was obtained. In 2010 the RSPT caused further impacts. This paper will describe the current progress of mine development as well as how the various challenges have been met and some key lessons learnt from these experiences.

Mar 21, 2011

By O van Baalen

The Ernest Henry Mine is a copper-gold open pit operation situated in northwest Queensland, Australia. It is owned and operated by Xstrata Copper, with a current throughput of 11 Mtpa, however, open pit operations are scheduled to cease in mid 2011. The deposit dips approximately 45º and extends for at least another 400 m vertically below the final 530 m deep pit design.Construction and development of a sublevel caving (SLC) operation beneath the open pit was approved in December 2009. The feasibility design requires 39 km of development to be completed prior to production, which will commence in the fourth quarter of 2011. Initial ore production will be trucked and will increase to 3 Mtpa by the end of 2012, after which a hoisting shaft will be used. Ore production will then increase to 5 Mtpa in 2013 and ultimately to 6 Mtpa in 2016.Two 3000 kilo watt of refrigeration (kW(R)) modular refrigeration plants will be installed, as well as two 1600 kW mixed-flow fans capable of a combined flow rate of 780 m3/s at a total pressure loss across the mine of 2000 Pa. The main fans will be installed underground and will exhaust into the base of the pit.The following challenges were faced in the development of the ventilation and refrigeration network:•a relatively steep geothermal gradient,•tropical ambient conditions,•working under a wide pit shell, and•a large underground trucking fleet prior to shaft commissioning.A considerable number of ventilation studies were conducted with later studies extensively using Ventsim Visual™ mine ventilation software to complete the design process of the ventilation and refrigeration networks, including the comparison of several alternative designs. The paper focuses on design challenges prior to the commissioning of the hoisting shaft, and discusses resistance optimisation and occupational hygiene-related design parameters, such as heat and diesel emissions, production level ventilation, main fan selection and location, and refrigeration requirements.

Mar 21, 2011