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Resources and reserves are critical inputs into the determination of an operating mineÆs financial results and balance sheets, but how well understood is this fact. Do the investors, directors, accountants and geologists/engineers responsible for preparing or relying on relevant aspects of the end results properly understand the inputs and outputs and the associated risks that may be established. The first step is to understand how financial reports are impacted. The most obvious, and best known, impact is in the calculation of depreciation and amortisation charges against long term assets. In addition, however, there is a requirement to regularly determine whether asset book values are impaired û this is nearly always performed globally by the preparation of a discounted cashflow model for a mine which is usually based on a mine life as determined from the resource and reserve statement û the particular driver here is normally the short and long term production plans. A key aspect of the short term production plan is that it would normally not assume that the reserve and resource statement implies consistent grade, stripping ratios, etc. However, outside of the early years of a plan, more generic assumptions of these variables are often made in conjunction with the reserve and resource statement. Depending on the timeframe of the detailed production plans, this can have a large impact on a projectÆs net present value. Other financial balances that may also be impacted include restoration and rehabilitation provisions, retrenchment provisions and deferred or equalisation stripping accounts. The age old question of whether all reserves should be used or whether some or all of the resources should be included for financial reporting purposes has never been adequately resolved. It is our view that there should be no prescriptive answer to this question but judgement of all professionals involved in the process needs to be included. Furthermore, the company needs to be able to support their conclusions with well thought out and appropriate answers. This may not be in line with the approach that certain accounting standard setters may be proposing or taking, and this paper will outline the current status of global requirement and the likely future directions. Whether reserves or resources are utilised, does not change the key requirement that those preparing or using reserve and resource statements need to understand key aspects. For example: geologists/engineers do they know how reserves or resources will be used? have they imparted information on variability of key drivers such as grade or depth or dilution? do they know that major financial/business altering decisions may be made based on the analysis? accountants do they understand where the numbers have been derived from and the assumptions that may have been made in their determination? do they understand the degree of accuracy (or inaccuracy) that may exist particularly with resources)? do they understand the history of resource reconciliations and what it may mean for the future? directors do they understand the processes undertaken by the company to prepare the financial report and the interaction between the geologists/engineers and accountants? do they understand the potential sensitivity of results to the input variables? Financial reporting is extremely reliant on the use of the reserves and resources, however, the geologists/engineers, accountants and directors do not always understand the interactions between themselves which may lead to misleading public reporting. More education and communication between various parties is needed.

Jan 1, 2002

By R J. Goldfarb

Reduced intrusion-related gold deposits have become a new, low-grade, large-tonnage exploration target during the last decade. The best recognized examples of such deposits are recognized throughout the Tintina Gold Province of the northern North American Cordillera. Because such examples may have many features in common with orogenic gold deposits, such as anomalous Bi, W and Te, low salinity and CO2-rich ore fluids, and a spatial/temporal association with igneous rocks, confusion and controversy have now become commonplace in classification of many gold deposits formed along convergent margins. The best discriminators of IRGS are likely to be their: +        regional location in deformed shelf sequences on the inboard side of a series of accreted terranes and within terranes that also contain important tin and (or) tungsten deposits; +        local spatial association of gold ores with cupolas and contact aureoles of relatively reduced, alkaline-leaning, and volatile-rich plutons; +        post-deformational timing of gold deposition; +        extremely low sulfide content (commonly <1 vol %) of ores within igneous bodies and the outward zoning, through proximal skarns and to distal base metal-rich veins, from the causative pluton; and +        low grades (<1 g/t Au) of auriferous sheeted vein systems in pluton cupolas.

Jan 1, 2005

By R J. Mills, B S. Sinclair, D A. Fergusson, A G. Goldstone

In 2005, Solid Energy New Zealand Limited obtained non-notified consent for the disposal of 1Mt of coal ash at the Rotowaro minesite, forming part of a coal supply agreement with the Huntly Power Station. The consenting of major mine site activities has historically required wide consultation and involves notification of the application.   The risk and cost associated with consultation can be significantly reduced via a non-notified process. A non-notified consenting process necessitates environmental effects to be shown to be æless than minorÆ, which requires the combination of robust science and a pragmatic approach to design, assessment of environmental effects, and consenting issues.   Key issues examined included consideration of how to practically operate a significant disposal project within the confines of an operating mine, minimising the costs, civil and geotechnical design and practical issues associated with traditional disposal. Environmental issues specifically related to the coal ash, led to a site specific performance driven approach to management rather than relying on conventional prescriptive approaches. Environmental issues of concern include the leaching of boron and aluminium from ash into groundwater and mine water management systems where both boron and aluminium can occur at elevated levels.   Coal ash exhibits unusual geochemical characteristics reflecting the primary coal composition and the combustion process. The dominant coal type combusted at the Huntly Power Station is derived from Rotowaro and the resulting ash is cementitious and has a high alkalinity. As a result the disposal design is based on the characteristics of the ash itself rather than the material into, or onto which the ash is disposed. Non-notified status was able to be achieved through consideration of these key characteristics of the ash, ensuring that the dimensions of the disposal site and each location was designed to minimise the flow of groundwater through the ash and demonstrating that the physical ash disposal effects are less than minor compared to the consented mining operation.

Jan 1, 2006

The only simple sulphide mineral of antimony of importance is stibnite, SbS3, containing 71·8% antimony when pure. It is lead-grey, has a densityof 4·5 to 4·6 and melts at 546°C. It is both friable and sectile (Hardness 2 on Moh's scale) and, as a result, slimes very readily during milling.It is commonly associated with pyrite and arsenopyrite other minerals occurring with stibnite in minor quantities are chalcopyrite, galena, and scheelite. The latter mineral occurs in sufficient quantity at the Yellow Pine Mine, Stibnfte, Idaho, to justify the production of a scheelite concentrate.Stibnite mayor may not contain gold. Other minerals such as pyrite or arsenopyrite may contain gold. At Wiluna at the main mine nearly all the gold is asociated with arsenopyrite the stibnite being almost free from gold, whilst at the Moonlight Mine both arsenopyrite and stibnite carry gold.The mineral, tetrahedrite, which is a complex sulphide of copper and antimony; must also be considered an economic source of these two metals.Part of the copper may be replaced by iron, zinc; silver; or mercury, whilst part of the antimony is often replaced by arsenic.CLASSIFICATION OF ANTIMONIAL GOLD ORESFor the purposes of this paper antimonial gold ores may be conveniently classified as follows: CLASS 1. Ores from which a satisfactory gold extraction may be obtained by fine grinding, followed by cyanidation and which contain insufficient antimony to justify tIie production of an antimonial concentrate.CLASS 2. (a) Ores in which a satisfactory gold extraction may be obtained by straight cyanidation, but which contain sufficient antimony to justify the production of an antimonial concentrate.CLASS 2. (b) Ores from which the gold extraction by straight cyanidation is unsatisfactory. This type of ore requires the production of an antimonial concentrate for reasons which will be considered later.In deciding whether an ore belongs to class 1 or 2 (a) it should be remembered that the normal price of star antimony is about £1.00 sterling per ton and that the value of each 1% of antimony recoverable as metal is worth about £1 per ton.The antimony content of antimonial gold ores is liable to be considerably...

Jan 1, 1944

By R Salmon, C Jones

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

Jan 1, 2002

By A B. Christie

Known epithermal deposits in the Coromandel region belong to the low-sulphidation type, represented by three subtypes: (1) andesite-hosted epithermal Au-Ag, (2) rhyolite-hosted epithermal Au-Ag, and (3) andesite-hosted polymetallic veins. Paleo-depths for a range ofdeposits are estimated using various features including: paleo-surface indicators (e.g. sinters), hydrostatic pressures estimated from homogenisation temperature measurements on fluid inclusions, and alteration mineralogy. Paleo-depth estimates to the base of the ore zone for the rhyolite-hosted Coromandel deposits are in the range 200 to 500 m. Andesite-hosted Au-Ag deposits have more variable paleo-depths, and are deeper (up to 950 m) in those deposits with base metals at depth. The majority of Coromandel Au-Ag deposits have limited depth extents (<200 m) of economic grade mineralisation, although Waihi and Karangahake are notable exceptions with depth extents of 575 m and 700 m respectively. Limited depth extents of economic ore are a feature of epithermal systems worldwide and are commonly attributed to gold deposition from boiling fluids. Under hydrostatic conditions in epithermal/geothermal systems, boiling in an up-flowing hydrothermal fluid is controlled by the boiling point for depth (BPD) curve. From fluid inclusion studies of many low-sulphidation epithermal systems, deposition of electrum in economic concentrations appears to be confined to a temperature window of 260 to 180¦C. This means that for dilute, gas-poor fluids that follow the BPD curve, gold deposition is limited to a vertical depth zone of about 400 m, with its upper boundary at about 100 m below the ground surface. The greater depth extent at Waihi and Karangahake, can be explained by mixing of/a deep, hot (300¦C) fluid with cooler (c. 200¦C) heated ground waters. This has the effect of lowering the 260¦C isotherm by up to 300 m, thereby increasing the depth range of economic grade gold deposition within the 260 to 180¦Cwindow of electrum deposition.

Jan 1, 2000

The polymerisation of silica is found to interfere with thickening of leach pulps at Risdon. Hydroxyl ion and fluoride ion are catalysts for this reaction. Stability may be obtained by the presence of aluminium or ferric iron.INTRODUCTIONAt Risdon it has been a matter for satisfaction that, although the concentration, of silica in leach solutions is appreciable, it has ,given relatively little cause for anxiety.However the margin of safety is small and some intermittent difficulty in thickening leach residues during the last few years has prompted a further investigation, certain parts of which are described here since they may be of general interest.Leaching and ClassificationThe method of leaching which is practised at Risdon has been described in, two previous articles, by W. C. Snow (1936) and S. W. Ross (1949) to whiCh the reader is referred for detail. Continuous leaching is practised, the circuit solution flowing through five air agitated pachucas in series, to tlie first of which calcine is added. The circuit solution, which also enters the first pachuca, consists of spent electrolyte from, the electrolytic cells and contains 90 -gm. of free sulphuric acid per litre. About 80 per cent of the solublezinc oxide is extracted from the calcine in the first pachuca, at a pH value of 1-1 (7 gm.H2S04/1 at 55 to 60°C. In the later pachucas the leaching rate decreases sharply. The leach pulp which leaves the 'last pachuca contains an average of 17 gm. of free acid per litre, corresponding to a pH of 1.7; but, owing to variations in extraction, the end point fluctuates between 2.5 and 0·3 gm. free acid per litre (pH:> 1·5 to 2.5). The average flow through the plant is 1,250,000 gallons per day, which corresponds to a production of 300...

Jan 1, 1958

Implementation of Fine-Screening in Preparation of KGHM PM SA Sandstone-Carbonate Copper Ore for Flotation

Sep 13, 2010

By P González, E Córdova, E Faundez

An integrated mine system must be capable of displaying and reporting valuable information that can be used to easily understand, manage and take action on the key parameters being reported.One of the key aspects of integration is the standardisation of the mine information up to a level capable of adapting the main characteristics of past projects at the mine and enforcing the same or higher standards for newer projects being developed.At the El Teniente mine, photogrammetry is used to map the advance of horizontal developments, and the constructed 3D representation of each face is then used by the geologists to obtain structural information about the areas being photographed.The mine realised that valuable mining information could also be extracted from the photogrammetry being applied, with three possible areas of development envisioned.The first area was creating a link between the developments being planned on a yearly and monthly basis and matching them with plan sections of the 3D developments of the system to account for any deviations.The second area was to use vertical sections of the 3D developments to estimate the overbreak of the excavations in different areas of the mine.The third area was the provision of a more detailed analysis of the sections so that they could provide information on the thickness of the shotcrete being applied.This paper presents the different alternatives being used and examines how the project is currently being developed and managed at the mine. It also looks at the challenges associated with implementing the reporting platform and the results being obtained.CITATION:Córdova, E, Benado, D, González, P and Faundez, E, 2016. Mine planning information from photogrammetry sources at the El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 653–658 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By J E. Lynch

The Weda Bay nickel and cobalt laterite deposits on Halmahera Island, Republic of Indonesia were first drilled in May 1996 by Strand Minerals Pte Ltd (Strand). Subsequent exploration has delineated four large laterite provinces, parts of which have been diamond drilled to outline an indicated nickel resource of 59.9 Mt of 1.51 per cent Ni and 0.09 per cent Co within a total indicated and inferred resource of 117 Mt of 1.36 per cent Ni and 0.12 per cent Co. The project is held as a Seventh Generation Contract of Work (COW) by PT Weda Bay Nickel, which is jointly owned by Strand (90 per cent) and PT Aneka Tambang (ten per cent). Strand is a wholly owned subsidiary of Weda Bay Minerals Inc, a company listed on the Toronto and Alberta Stock Exchanges in Canada. Halmahera is located in the north-eastern part of the Indonesian archipelago at the convergent junction of three major plates and is a region of considerable tectonic and geological complexity. The western arms of Halmahera form a classic volcanic island arc while the central region and eastern arms contain ophiolite complexes and interlayered sediments. The extensive areas of laterite discovered at Weda Bay have developed over serpentinised harzburgites and dunites of pre-Cretaceous age. Weathering of these rocks has produced laterite profiles that are enriched in nickel and cobalt. There are three economically mineralised laterite types, namely limonites, ferruginous saprolites and saprolites and all are amenable to rapid pressure acid leaching with recoveries of 98 per cent nickel and 94 per cent cobalt in less than 20 minutes.

Jan 1, 1999

By A R. Penney

Since mining-induced seismicity first became apparent at the Beaconsfield Gold Mine in 2002, there has been an ongoing program of geotechnical investigations to understand the phenomenon and allow for the development of strategies to manage the risks it posed to personnel, the business and the community at large. Studies resulting from a seismically induced rockfall on Anzac Day 2006 have been extensive, and have advanced the understanding and management of seismicity at the mine. Enhancement of the mineÆs seismic array, implementation of extensive monitoring of ground behaviour, improved ground support and reinforcement design, and ongoing numerical modelling provide a technical framework for the management of seismicity. In addition, extensive involvement of the workforce in risk assessment and the development of standard work procedures (SWPs), has contributed to a æbest practiceÆ approach to manage seismic hazards at the mine.

Jan 1, 2008

A detailed study of the capital investment and production cost for copper electrowinning plants shows that significant savings in both can be achieved by increasing the current density. From the economic analysis it is determined that the optimum current density which will result in lowest capital investment and lowest operating cost is between 60 A/sq. ft. and 70 A/sq. ft., or at least three times as high as the Conventionally employed current density. The specific investment, expressed as $/ton-year, is found to be a function of both the current density and plant capacity and has a minimum value at the optimum current density. Empirical equations are developed for the purpose of estimating the capital investment and operating cost for plants of any production capacity operating at any current density.

Jan 1, 1972

By W J. Rankin

Metals are well suited to sustainable development goals. They are not biodegradable and have virtually an unlimited lifespan and the potential for unlimited recyclability. Thus metals can be considered as renewable materials. However mineral resources, the source of primary metals, are ænon-renewableÆ as their supply is finite, but this does not necessarily mean scarcity. In this paper the results from a series of Life Cycle Assessments of primary metal production processes for copper, nickel, lead, zinc, aluminium and steel have been used to examine how metals may contribute to societyÆs transition to sustainable development. Particular issues considered include:current metal reserves and how these may change in the future; some of the environmental impacts (Total Energy, Global Warming Potential and Acidification Potential) associated with primary metal production and how they will be exacerbated by declining ore grades; new processing technologies with lower energy consumptions and improved metal extraction efficiencies that will reduce reserve depletion and environmental impacts; increasing the utilisation of æmetals in useÆ by recycling, with particular reference to aluminium; and the potential impact of a carbon tax on metal prices and how this may influence the ways in which metals are used in the future.

Jan 1, 2002

Whilst the fossil fuel-based power industry moves towards carbon capture and storage (CCS) or so-called 'geosequestration', the minerals industry should adapt to reap the benefits of the new technology. If CCS becomes viable, the door is open to potential key developments in mineral processing. For example, truly continuous steelmaking could at last be realised using natural or manufactured gas combined with generic melt circulation. Iron ore fines would form a thin molten layer moving countercurrent to the gaseous reductant on one side of a melt circulation loop with efficient post-combustion without deleterious effects of slag accumulation on the other. This eliminates oxygen steelmaking because carbon has no access to the circulating molten iron. Steelmaking merely requires addition of the appropriate low level of carbon and in-line impurities removal to meet product specification. Concerning non-ferrous smelting, nothing short of virtually zero gas emission will be acceptable in the future. For dolomite-hosted Zn/Pb sulfide ores, typified by those in the Carpentaria region of Northern Australia, the way forward proposed is sulfur fixation at the mine site employing the highly exothermic reaction of SO2 with dolomite, followed by encapsulation of sulfated dolomite in fused ore slag. This releases enough energy for direct ore smelting to individual metal products. However, without CCS the strategy would be unacceptable because of greenhouse gas emissions. The scheme is advocated for direct ore smelting at McArthur River. As a result, the environmental problems of disposal of flotation tailings are avoided. Also, highly energy intensive ultra-fine grinding is eliminated, as indeed froth flotation itself, with overall very significant energy savings and exceptionally high increases in metals recovery. Zinc and lead recoveries approaching 99 per cent are predicted to be entirely feasible.

Sep 13, 2010

By N Weerasekara, M Powell, P Toor

The effect of liner wear on SAG mill performance has gained much attention in recent years. It is commonly observed that the three key performance criteria of SAG milling; throughput, power and product size all improve as the liner wears.The increase in throughput is generally ascribed to the increase in the grate apertures and the increase in mill volume due to the wear of these components. Whilst the decrease in product size is attributed to the reduction in lifter height and angle, resulting in more breakage by means of attrition and abrasion.Though it is widely acknowledged that the wearing of liner components such as Lifters, Plates and Grates have a significant impact on mill performance, their individual contribution to changes in mill performance has been unclear, and resultantly lead to questions like; what percentage of the throughput increase can be attributed to the increase in mill volume (plate wear)? and how much can be attributed to the increase in grate aperture (grate wear)?It has been found that through the use of grinding surveys, analysis of production data and JKSimMet it was possible to separate the effects of changing liner profile, increasing mill diameter and increasing grate aperture on the mill performance allowing for the quantification of each.The outlined methodology allows for both troubleshooting of problem liner components which reduce milling efficiency in their wear life as well as providing a basis for a more quantitative approach to liner design and reline scheduling.CITATION:Toor, P, Powell, M, Hilden, M and Weerasekara, N, 2015. Understanding the effects of liner wear on semi-autogenous grinding mill performance, in Proceedings MetPlant 2015, pp 150–161 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

Development of Grindability Tests Based on Direct Measurement of Energy Nowadays, for the characterisation of the grindability different grindability indices - Bond-work index (Wi), Hardgrove Grindability Index (HGI) or Zeisel specific grindability (Wt) - are used. Generally, the grindability tests are carried out under relatively simplified circumstances, in a special dry batch mill with defined feed size material until prescribed conditions are reached at room temperature. However, in the fine- and ultra fine grinding, which is a frequent task (fly ash, tailings, alumina, etc), a fine material (<50 - 200 ¦m) is usually ground down to the few micrometers. The conventional grindability testing methods and apparatuses (Bond-, Hardgrove-, Zeisel-processes) for their determination, although, are not suitable directly to measure the grindability of such fine materials, since the maximal particle size of the feed material (0.5 - 3 mm) to be tested is much higher. One of the important goals of the research carried out in our Institute was to develop the novel grindability testing methods, which are suitable for the fine and ultra fine grinding, and additionally provide the possibility for the fast determination of the grindability. In order to realise the above aim the conventional Bond- and Hardgrove- mills were modified in order to directly measure the grinding work. In particular, the Hardgrove-mill was equipped with a simple torque-meter (load cell). The Bond-mill was rigged with a digital electric power measurer. The systematic experiments were carried out parallel in both mills using the conventional and the developed methods. Finally the results of both were compared. The measuring results have proved that the Bond-work index can be determined based on the developed methods. The new grindability testing methods were applied successfully in several industrial research tasks for the determination of the specific grinding energy and the Bond-work index. These methods can be also used in the industrial practice for the control of the grinding process.

Sep 13, 2010

By I M. Platten, Y Xie

Complex gold deposits are generally characterised by variable geometries, strong structural controls on grade distribution and a high-nugget effect. The use of diamond drilling and fire assays in this environment often results in an understatement of grade. Bulk samples are likely to be the closest estimators of true grade, and may be required to evaluate geological/grade risk during resource estimation/feasibility studies. Any bulk sampling program requires appropriate planning and implementation. The planning stage should attempt to delimit the extent and nature of mineralisation; characterise mineralogy and metallurgical properties of the ore; and define bulk sample size and how it will be sampled/processed. The approach to sample processing will be governed by the results of metallurgical testing and geological knowledge. Careful design of sampling protocols must be undertaken through material characterisation, understanding of gold particle sizing and the application of GyÆs Sampling Theory.

Jan 1, 2008

ON mineral lease 38 of the Sulphide Corporation Limited, Broken Hill, a shaft was sunk in the early days Ior prospecting purposes and at the present time it is accessible as far as the 1000-ft. level where a connexion exists with the main workings of the Corporation's Central Mine, mineral lease 9. About the year 1895· a crosscut was driven east from this shaft at the 1330-ft. level cutting the Central Ore-body in mineral lease 9 and the shaft is supposed to extend a further depth of 25 ft; but no records of any of this work are in existence, the whole of the evidence being based on hearsay and memory:Fig. 1 shows the position of the Extended shaft in relation to the main workings. The shaft filled with water to the 1000-ft. level where it overflowed through the crosscut to the main shaft and was pumped to the surface, but when the South drive on the 1300-ft. level was pushed to the southern boundary, it was deemed advisable for safety, to tap the water at this level and so relieve the...

Jan 1, 1919

By B Cope, Y Churi

Roxgold was a small exploration company when it discovered the Zone 55 orebody at the Yaramoko project in Burkina Faso in 2010. Since this time, it has actively progressed the project with the completion of a preliminary economic assessment in 2013, a feasibility study in early 2014 and obtained full permitting for construction in January 2015. With no other underground gold mine in Burkina Faso, developing a modern and productive modern gold mine in West Africa was considered a significant challenge as Roxgold moved from explorer to producer.To facilitate this development, Roxgold engaged an international underground mining contractor to partner this development. This has enabled Roxgold to successfully develop the mine over a relatively short time frame with construction commencing in April 2015, first gold being poured in May 2016 and commercial production being achieved in October 2016.This paper discusses key elements of the project development and highlights some of the challenges faced with operating in a remote poorly developed area with a limited mining culture. Furthermore, the authors highlight the key technical and operational aspects that make the Yaramoko project a very successful development project.CITATION:Cope, B and Churi, Y, 2017. The development of the Yaramoko gold project in Burkina Faso, West Africa, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 173–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By D N. Castendyk, J L. Mauk

The world-class Waihi (>6.6 Moz Au, >41.8 Moz Ag) and adjacent Favona (>0.5 Moz Au) deposits are within a single volcanic-hosted epithermal Au-Ag district located in the southern Coromandel Peninsula, New Zealand. Gold and silver mineralised quartz veins at both deposits are hosted in porphyritic andesite flows of the Waipupu Formation. Both deposits have veins surrounded by intense widespread hydrothermal alteration that is characterised by the assemblage of quartz, pyrite, adularia, illite or interstratified illite-smectite, plus less common chlorite and albite, which is locally overprinted by minor calcite or rare kaolinite. Quantitative mass transfer calculations using Gresen's general metasomatic equation indicate that hydrothermally altered andesite at both deposits is enriched in silicon, potassium, rubidium, barium, sulphur, gold, arsenic and antimony, whereas sodium, strontium and calcium are mostly lost. Iron and magnesium show mixed gain and loss. Element gain or loss can be directly related to the prevailing alteration mineralogy. Addition of potassium, rubidium and barium coupled with the concomitant loss of sodium, strontium and calcium in intensely altered wall rocks corresponds to the replacement of plagioclase by adularia or illite. Partial retention of sodium and calcium reflects the presence of hydrothermal albite and calcite, respectively. Mass balance calculations show distinct element gain and loss that can be related to the intensity and type of alteration mineralogy. However, because most rocks are intensely altered and the progression into less altered peripheral rocks is not observed in this study, the lateral extent of elements gain or loss is unconstrained with anomalies extending at least 200 to 300 m away from major veins.

Jan 1, 2003