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The Goonumbla district of central-west New South Wales, Australia, hosts four significant porphyry Cu-Au deposits that contain a combined probable ore reserve of 71.7 million tonnes at 1.2 per cent Cu and 0.5 g/t Au. Mineralisation in the Goonumbla deposits is associated with narrow, pipe-like intrusions of quartz monzonite porphyry, in which several intrusive phases have been recognised. Five textural characteristics have been used to distinguish the various intrusive phases recognised in the Goonumbla porphyry deposits: (1) phenocryst abundance; (2) nature of the groundmass; (3 and 4) proportion and mineralogy of the mafic and non-mafic phenocrysts; and (5) the presence or absence of anhedral quartz grains in the groundmass. In addition, each intrusive phase is classified according to its estimated original quartz, alkali feldspar and plagioclase contents. Features common to all of the intrusions are that they contain two types of plagioclase and two or three types of K-feldspar phenocrysts in variable proportions. Most of the intrusions also contain apatite micro-phenocrysts. The groundmass textures range from aphanitic through granular to euhedral K-feldspar in a quartz matrix. With only one exception, all of the intrusive phases recognised are either quartz monzonite porphyry or mafic (>5 per cent mafic minerals) quartz monzonite porphyry. The exception is a biotite - phyric monzodiorite, which occurs in the basal portions of one of the deposits. Textural variants of intrusive phases at Goonumbla have been investigated to establish whether specific combinations of characteristics indicate mineralised intrusions, while others suggest barren ones. Some correlations between intrusion types and Cu and Au grade have been recognised. The most important textural characteristic that relates to high grade mineralisation appears to be the low proportion of mafic minerals, because the quartz monzonite porphyry intrusions hosting most of the mineralisation in the two deposits studied contain

Jan 1, 1999

By R Knight

"In project evaluation there are two matters of keen interest to non-executive directors: the process by which an investment recommendation is reached, as well as the investment itself, as presented. It is sometimes mistakenly believed that Boards of directors are interested only in the result. That is not so. The process by which project evaluations are derived and socialised with the Board is as important as the result, sometimes more so.Setting aside the gloomy predictions of the doomsayers and looking through short-term volatility in supply and demand, the overall availability of mineral resources more often than not exceeds demand. There are in reality more development projects in prospect at any one time than are needed to meet the market. Only the fittest will prosper, although some others may survive.Optimism springs eternal in the mining industry and every project promoter, executive or entrepreneur has a convincing project development case. Some will create value for shareholders, but the historical evidence suggests that many will fail to meet the expectations set in their evaluation.Boards of directors make the final decision to invest, or not, in a new mine. Knowledge is power, and on that basis the balance of power favours management. Management has the facts (or in some cases, what passes for fact) and the passion to invest. The non-executives have the power of approval – yes or no – but before making a decision directors must demonstrate due diligence, the essential precursor to project approval.Management has a vital part to play in facilitating that due diligence process and in encouraging the independent thought processes of the Board. A closed approach by management fosters a negative, risk-averse attitude on the part of the Board. One that encourages an understanding of the rigour of the project evaluation process and the robustness of the result will allow directors to understand better the implications of their decision.CITATION:Knight, R, 2016. Project evaluation – a non-executive director’s perspective, in Proceedings Project Evaluation 2016, pp 11–19 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By P Craig, A Crosky, P C. Hagan, E Elias, B Hebblewhite, S Saydam, D Vandermaat

"Premature failure of rock bolts has been recorded at twelve underground coalmines over the past 15 years in Australia. Over the last four years, UNSW Australia has been conducting an Australian Research Council (ARC) and Industry funded linkage research project into premature failure of rock bolts. The extent of the problem was investigated by underground surveys of mines with known prematurely failed bolts using visual mapping, non-destructive load and ultrasound testing. A major component of this project was to define the environmental factors responsible for corrosion of rock bolts. The environment to which a rock bolt is exposed will include groundwater chemistry, the mineralogy of the strata, atmosphere within the drill hole and even microbial activity. This paper focuses on the groundwater survey and analysis findings to date along with in-hole bolt corrosion coupons installed into field sites. Corrosivity classification systems exist for general corrosion but do not apply to the rock bolt stress corrosion cracking (SCC) problem found in Australian underground coal. The method of in situ investigations is leading towards the building of a corrosivity classification model to assist mines in prediction of premature rock bolt failure. An ‘in-hole bolt corrosion coupon’ development by the project may have multiple benefits of: helping quantify any corrosivity classification system providing an in situ ground support corrosion monitoring tool for testing possible corrosion protection solutions.CITATION:Craig, P, Saydam, S, Hagan, P C, Hebblewhite, B, Vandermaat, D, Crosky, A and Elias, E, 2014. An investigation of the corrosive impact of groundwater on rock bolts in underground coalmines, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 277–286 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By M D. Sussman

A large number of countries in the world now have some regulation for labelling the presence of genetically modified organisms (GMO) in food. For the last ten years, ISO/TC 34/SC 16 has been providing methods, guidelines and requirements concerning the evaluation of molecular biomarkers including GMOs. This activity makes sure that stakeholders on all sides of commercial transactions are satisfied and their marketing or regulatory needs are met. Developing and maintaining a transparent, science-based environment for users of horizontal methods for molecular biomarker analysis is a high priority. Sampling and analysis of molecular biomarkers has become critically important for food and agricultural organisations developing, producing, distributing and selling genetically engineered, non-genetically engineered, identity preserved and/or organic crops and their derived products and preventing their respective destructive diseases. To aid in international harmonisation, a new work item proposal to develop an ISO type A management system standard (MSS) for organisations including laboratories using molecular biomarker analysis and sampling has been submitted to ISO/TC 34/SC 16. The purpose of this MSS is ensuring that determination of the presence, absence or quantification of a particular biomarker with a relationship to a product quality determinant, a marketing claim, a regulation or a plant pathogen is carried out under a suitable quality assurance / quality control system. This MSS will provide an overarching system to apply and manage molecular biomarker analysis and sampling for any organisation large, medium or small in a private, government or academic setting.CITATION:Sussman, M D, 2017. ISO/TC 34/SC 16 horizontal methods for molecular biomarker analysis – molecular biomarker analysis and sampling management system, in Proceedings Eighth World Conference on Sampling and Blending , pp 295–302 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By D Smith, A Ramdhani, J Francke

Ground penetrating radar (GPR), a well-established geophysical technique generally used for shallow civil engineering applications, has, in the last decade, found increasing acceptance as a complementary tool in mineral resource evaluations. As new sites are trialled with the method, a greater understanding is being garnered regarding the most suitable environments for long-range radar. Although successful projects have been conducted worldwide for mineral sands, iron ore and alluvial projects – tropical weathering environments have produced some of the most impressive results. Specifically, tropical nickel laterites have shown to be, with some notable exceptions, ideal GPR environments.Such high-resolution remote sensing has particular relevance to bulk commodities or those which possess significant rheological variation within geological units, and has led to some innovative downstream uses within exploration, project development and the larger mining industry. In this paper, we examine the application of long-range GPR in Indonesian nickel laterite deposits in general, to highlight some of these novel applications with particular reference to resource modelling, mine geology and operational economic implications.CITATION:Francke, J, Smith, D and Ramdhani, A, 2014. Ground penetrating radar to enhance the exploration-to-mining value chain, in Proceedings Ninth International Mining Geology Conference 2014 , pp 175–182 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

Confirmation that acid drainage (AD) was a significant environmental issue for the Australian minerals industry came in 1992 with the first national workshop on the topic. Subsequently the extent of AD was documented in a national survey published in 1997. The recommendations arising out of that survey served as a platform for actions by government, industry and industry-support organisations such as the Australian Centre for Mining Environmental Research (ACMER) to enable more effective prevention and management of AD. This paper briefly documents the extent of AD in the industry, the government regulations and guidelines for AD management, industry initiatives, the role of ACMER and other organisations in assisting industry through research and technology transfer, and the efforts being made to deal with AD at derelict mines. Future management of AD in the industry will be assisted by the linkage of Australia (through ACMER) into the International Network for Acid Prevention (INAP) which is facilitating the interchange of knowledge on AD as well as coordinating global research on the topic.

Jan 1, 2003

By B Flynn, P Knights

Low-loaders or 'floats' for relocating equipment in surface mines are limited to a capacity of approximately 350 t. In the iron ore industry it is desirable to be able to rapidly relocate excavators in order to maintain production rates within appropriate quality limits. In addition, the ability to rapidly relocate heavy equipment raises the possibility of improving the quality of repairs by performing maintenance in controlled shop conditions. However, many iron ore operations operate hydraulic excavators in the 600 to 800 t range, with newly released excavator models exceeding 800 t. These excavators are too large to float using conventional technology. This paper examines the potential for using multi-bogie transporters to relocate large hydraulic excavators in surface mines. Recent innovations have seen the development of modular transporters which can be coupled together to achieve larger platform areas. When separated, and with their drive bogies neutralised, these units are able to be towed behind prime movers and relocated between mines via public roads. The potential cost savings for relocating a Terex RH170 excavator in an open pit coal mine are examined. In the first six months of 2008, the analysis showed the potential for a 38 per cent reduction in total travel time with a corresponding revenue increase of approximately $350 k. The paper recommends that a feasibility study be conducted into offering a heavy equipment relocation service within the Pilbara region.

Jan 1, 2009

By A Kurniawan, A Sjadat and M Akhasyah

PT Freeport Indonesia’s Deep Ore Zone (DOZ) is a block cave mining operation that has been in production for 15 years. DOZ is located approximately 900 m below surface and has an average production rate of more than 5000 t/d. The footprint of the extraction level will ultimately be 900 m long and average more than 200 m wide. The undercut level is located 20 m above the extraction level.While developing Panel 1K on the northern portion of the extraction level, a major geotechnical problem was encountered when there was a change in lithology and an associated fault intersection. A large collapse of the hanging wall of the extraction level drifts occurred in the area of the fault intersection between February and March 2011. This was followed by a collapse of one of the undercut level drifts directly above the extraction level in May 2011.It was suggested that the best approach to mitigate risk during rehabilitation was to systematically open up the failed area under the protection of a steel set support system. To achieve this, approximately 60 t of grout was injected from the undercut level to fill the voids created when the rock mass between the two levels failed. A ground penetrating radar system was used to survey the condition of the rock mass between the two levels before and after the injection of grout. After the grout injection phase was completed to a satisfactory level of confidence, rehabilitation activities started on the extraction level by taking out the now consolidated material from inside the drift in 2 m advances from under steel sets initially constructed in secured ground.Controlled blasting was the key aspect to the success of the initiative to open up just enough of the drift to systematically support the rock mass before the next set was installed. The systematic support consisted of in-cycle shotcrete sprayed over mesh pinned to the exposed rock, as effectively as possible, with splitsets before spiling the next advance’s protection canopy with rebar. Once secure, a combination of steel set and pumped concrete was installed as the final support. This final support provided a safe platform to repeat the process until the failed zone was safely traversed.CITATION:Kurniawan, A, Sjadat, A and Akhasyah, M, 2016. Rehabilitation of the collapsed panel 1K north in the Deep Ore Zone block cave mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 763–768 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By A Vickerfält, J Huss, J Martinsson

The European Union has listed vanadium (V) as one of the critical raw materials for the transition to a future green society, as stated in the Critical Raw Material Act, written by Grohol and Veeh (2023). In the steelmaking industry based on V-containing iron ore, V is a possible by-product from the slag. A requirement for slags to be suitable for V extraction is a V content preferably above 8 wt per cent as V2O3 and a phosphorus (P) content below 0.1 wt per cent as P2O5. Hence, it is important to keep V in the slag phase while the P is moved to the metal phase during the steelmaking process.

Aug 21, 2024

By Flavelle IV

A survey is made of changes in the technical status of a number of western world copper extraction and refining operations over the past 20 years. Specific developments in pyro- and hydro-metallurgy and refining practices are identified together with factors in the changing environment of the industry which has influenced their adoption. Nickel extraction and refining is similarly discussed.The replacement of traditional technology by more attractive alternatives has occurred in a considerable number of operations. The develop-ment and status of new continuous smelting processes, advances in hydrometallurgy and refining innovations which emerged during the 1960s and early 1970s is discussed. The varying experience in commercial acceptance of these new technologies is noted.Finally some possible future directions are canvassed for both operators and the research and development institutions.

Jan 1, 1985

By S Wellink, D Chalmers, D Adermann, C Martin

The practice of recording blasts for quality control purposes has been conducted for several decades. However, at the low frame rates of a standard video camera, essential data is frequently missed as it occurs when the shutter is closed between frames.The use of high-speed video for the research, development and monitoring of the performance of blasting procedures is a well proven but under-utilised practice.The recent development of low cost, easy to use high-speed digital cameras and user friendly software can deliver a capability into mine management as a day-to-day production tool that can greatly improve blasting performance and reduce costs.Digital high-speed video and image analysis software can accurately quantify each blast. Analysis of the images can facilitate the identification of causes of variance from design, geology changes, errors in blast practice and areas of poor performance. The use of high-speed video greatly enhances the audit and review processes so that future blast design can be quickly and appropriately modified to deliver improved blasting performance and reduced costs.The three videos demonstrate the differences between standard video and high-speed video and the detail that can be obtained from them. These videos of open cut blasts can be used to identify blast performance variances. Capturing images at 1000 frames per second allows the analysis on a millisecond timescale where detonator timings, fragmentation, venting, fume generation and flyrock can be accurately identified.CITATION:Adermann, D, Chalmers, D, Martin, C and Wellink, S, 2015. High-speed video – an essential blasting tool, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 471–476 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By F I. Cox, D Peeler, T Bodisco

"Diesel particulate matter (DPM), in particular, has been likened in a somewhat inflammatory manner to be the ‘next asbestos’.From the business change perspective, there are three areas holding the industry back from fully engaging with the issue:There is no real feedback loop in any operational sense to assess the impact of investment or application of controls to manage diesel emissions.DPM are getting ever smaller and more numerous, but there is no practical way of measuring them to regulate them in the field. Mass, the current basis of regulation, is becoming less and less relevant.Diesel emissions management is generally wholly viewed as a cost, yet there are significant areas of benefit available from good management.This paper discusses a feedback approach to address these three areas to move the industry forward. The six main areas of benefit from providing a feedback loop by continuously monitoring diesel emissions have been identified: Condition-based maintenance. Emissions change instantaneously if engine condition changes. Operator performance. An operator can use a lot more fuel for little incremental work output through poor technique or discipline. Vehicle utilisation. Operating hours achieved and ratios of idling to under power affect the proportion of emissions produced with no economic value. Fuel efficiency. This allows visibility into other contributing configuration and environmental factors for the vehicle. Emission rates. This allows scope to directly address the required ratio of ventilation to diesel emissions. Total carbon emissions. For National Greenhouse Emissions Reporting (NGER)-type reporting requirements, calculating the emissions individually from each vehicle rather than just reporting on fuel delivered to a site.CITATION:Cox, F I, Bodisco, T and Peeler, D, 2014. Continuous remote emissions monitoring – the lynchpin for air quality management, in Proceedings 12th AusIMM Underground Operators’ Conference 2014, pp 137–142 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 24, 2014

The character of alluvial gold deposits presents severe difficulties, and sometimes limitations, on the extent to which metallurgical efficiency can be measured. Very little monitoring of metallurgical performance is practised. An indication of performance is often extracted from the comparison of production to the estimate. This is a dubious practice. The recovery efficiency of conventional practices, viz sluices, tables and jigs, falls off sharply below 0.2 mm. Field evaluation procedures tend to simulate these conventional practices. Thus the presence of fine gold may not be detected, particularly if obscured by clay. There is increasing evidence that fine gold could, in places, be present in sufficient concentrations to be economic. Most gold in paleoplacers is finer than 0.1 mm. There are established practices elsewhere in the mineral industry that may physically recover gold down to 5 microns in size and which could find application for fine alluvial gold.

Jan 1, 1984

By S O. Hille

Modern remote mining operations in Australia are more commonly trending towards fly-in/fly-out (FIFO) sites. This trend is driven by numerous factors including increased business centralisation, reduction in operating costs, and a desire to live in coastal cities that offer closer family networks and a greater diversity of facilities. Consequently, the resource development industry has had to adapt. When WMCÆs Mount Keith Nickel Operation commenced operations in 1994, it was developed as FIFO for its entire workforce. Since then, there have been several permutations of rosters within a 21 day compressed work cycle including the 14/7 cycle. This paper discusses a case study of the change in management process to the 9/5 work cycle focusing on minimising fatigue in the workplace. It includes the discussion of the business case, employee reaction and the practical application. The impact of the best practice change after 18 months is discussed.

Jan 1, 2002

By X Zhang, Y Zhu, P E. Ngoepe, P P. Mkhonto, W Xiong, L Han, L Lu

The triazine molecules have not been given much attention and they are potential collectors that may positively impact the mineral processing industry. The adsorption of triazine as collectors such as sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) on pyrite form a basis in design of flotation collectors that may be applicable in a wide range of sulfide minerals. The SDTBAT collector was compared with the sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC). All collectors were adsorbed in their neutral form containing sodium on the pyrite (100) surface. The computational calculations found that the adsorption energies followed the order: SDTBAT (-300.35 kJ/mol) > SNBX (-186.10 kJ/mol) > SNBDTC (-163.78 kJ/mol). It was observed that the SNBX and SNBDTC adsorbed through the S atoms, while the SDTBAT adsorbed through the S atoms and N atoms onto Fe atoms. It is clear that the SDTBAT had a strong binding energy which is attributed to the presence of the triazine group that is electron depositing to the active S atoms compared to the SNBX which possessed the oxygen that is electron withdrawing. Moreover, the SDTBAT collector was found to bind stronger than the xanthate. This was complimented by microflotation tests that showed fast floating and higher recoveries of pyrite when using the SDTBAT collector than the xanthate and DTC. This clearly demonstrated that the SDTBAT is a potential collector to replace the xanthate collector due to its high selectivity and flotation power.

Aug 24, 2022

By H Hoogvliet

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

Oct 5, 2011

By T M. El Hajj, A C. Chieregati, M T. G C Marques, J M. Braga Jr, H Delboni Jr

"The estimate and control of sampling errors is essential for all mining operations, especially when dealing with strategic materials, such as niobium. This paper is based on a traditional quality assurance and quality control technique used to confirm mineralised intersection zones, and proposes the validation of sampling data using diamond drill twin holes, in order to evaluate and improve the quality of the current data set. The geological model of the niobium mine – located in Araxá, Minas Gerais, Brazil – was built including 77 diamond drill holes of a sampling campaign carried out during the 1970s. There are few records about the collection and preparation procedures of these past samples, making it difficult to estimate the errors associated with their analytical results. Therefore, 11 twin drill holes were drilled to compare their samples against the samples from the 1970s drilling campaign. The new hole locations were chosen as near as possible to the old holes location. The JORC Code, 2012 edition, relates the use of twin holes as a good sampling technique to assess sampling and assay data. Three parameters were considered to validate the 1970s drill hole campaign by the twin drill hole campaign: the difference of the coordinates between the paired holes the difference among the positions of the geological contacts to validate the geologic description the difference between the paired samples grades was calculated to validate the analytical results.The analysis of the grade range variation between sample pairs was based on three techniques: geostatistical interpretation of vertical semivariogram to obtain the nugget effect calculation of the relative difference between duplicates calculation of the error associated with the sampling protocol established according to Pierre Gy’s Theory of Sampling.The results were satisfactory for hole coordinates; however, the ore content showed a high deviation, although this divergence can be explained by the nugget effect. For the lithological intervals, the new results contributed to an effective identification of variations among lithologies, ie brown weathered ore and saprolite. The twin drill holes campaign successfully validated the geological model data, allowing effective mine planning and higher reliability of the reconciliation results.CITATION:Marques, M T G C, El Hajj, T M, Braga Jr, J M, Chieregati, A C and Delboni Jr, H, 2017. Theory of Sampling and geostatistics for twin drill holes analysis in a niobium mine in Araxá, Brazil, Australia, in Proceedings Eighth World Conference on Sampling and Blending, pp 97–106 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

May 9, 2017

By Thompson IR, Solomons SS

Underground mining with the cut and fill method has been declining during the past decade or so, being replaced mostly by sublevel open stoping methods. During 1983 the Australian Mineral Industries Research Association Ltd. (AMIRA) commissioned a review of the method, with the aim of compiling the state-of-the-art, indicating future trends and recommending topics for research that would be needed to support this future mining. Mines using the cut and fill method in Australia and three other countries were visited to compile current practices and expected developments.Cut and fill is mostly used where geological and ground conditions are unsuitable for open or caving methods. These range from narrow, irregular orebodies to wide, massive orebodies where pillars are retained in ore. There is significant potential for improvement and further development of the method. It may then be used in a broader range of conditions and for orebodies that may not otherwise be viable to mine.

Jan 1, 1985

The construction of mine headframes of reinforced concrete is not a new departure as many structures have been built of this, material particularly in Canada and South Africa. This type of construction has been satisfactorily tested in service and is now accepted by the mining fraternity.The two headframes at New Broken Hill Consolidated Limited are the first structures of this type to be built in Australia, and provide an interesting application of reinforced concrete design and construction.Reasons for Adoption of ConcreteDuring 1947 the writer visited D.S.A. and Canada and inspected three headframes, of reinforced concrete construction.Leading details are as follows:(i) Hollinger Gold Mines. (Timmins, Ontario) : Height of sheaves 110 ft. Shaft has provision for 4 skips each of 12,000 lb. capacity. Structure incorporates surface crushing plant.(ii) International Nickel Corporation-Murray Shaft (Sudbury): Height to sheaves 153 ft. 6 in. Shaft provides for 2-12 ton skips and 2 cages. Surface crushing plant built integrally with frame.(iii) Asbestos-Johns Manviae (Quebec): Height of sheaves 116 ft. Shaft provides for 2 skips 200 cu. ft.

Jan 1, 1956

By M Hernan

Bendigo Mining Limited has established a modern underground gold mine and processing plant at Bendigo in central Victoria. The Bendigo goldfield produced around 22 000 000 oz of gold between 1851 and 1954. Approximately 4 000 000 oz were sourced from surface alluvial workings with the remaining 18 000 000 oz won from underground quartz reefs. The modern mine is accessed via the Swan Decline, which commences at the Kangaroo Flat site on the southern outskirts of Bendigo and progresses in a north easterly direction between the Deborah and Sheepshead anticlines, reaching a depth of almost 1000 m below the City of Bendigo. Development of this decline commenced in 1998. Since that time 20 km of underground development has been completed. Exploration drilling, on-reef development and bulk sampling carried out between 1999 and 2005 resulted in the estimation of a Probable Ore Reserve of 700 000 tonnes at 9.0 g/t gold for 207 000 oz of gold. These Ore Reserves were contained within four reefs located on the Deborah and Sheepshead anticlines. Reef mining commenced in late 2005 from the Shywolup and Greater Garrard reefs. Material mined was stockpiled on the surface in preparation for commissioning of the process plant which commenced in mid 2006. Mining and processing were carried out between August 2006 and May 2007 during which time 176 000 tonnes were processed at an average grade of 5.4 g/t gold to produce 26 735 oz of gold. Plant feed was sourced from four reefs. This paper discusses some of the issues which were encountered with the definition and mining of these geologically variable and nuggetty reefs. This paper covers exploration techniques, grade estimation, mine geological control, mining methods, geotechnical issues and reconciliations. It will also discuss some of the lessons learnt and how these will be applied to future Mineral Resource and Ore Reserve estimation, as well as underground operations.

Jan 1, 2008