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By P J. Fairfield

"This paper reflects on the author’s experiences in undertaking mining studies and reviewing mining projects and technical reports, particularly over the past five years, and the impact of recent changes in reporting standards and listing requirements pertaining to mining-related evaluation and valuation exercises. It also discusses contemporary changes in the expectations of the investment community and the implications for the role of the technical specialist in providing advice to such stakeholders.Not for the first time in history, the resources industry has experienced a significant downturn after a period of strong, sustained growth in line with the traditional view of the cyclical nature of commodity markets. The resource industry is currently faced with capital austerity in the wake of projects ‘failing’ (not delivering to expectations). In response, the industry has experienced changes in investment behaviour (slowing of investment) and an increasing regulatory burden as stakeholders seek a greater understanding of mining project risks.This paper discusses this response and uses case studies to highlight the key learnings (perhaps re-learnt) by the industry. It also discusses the challenges faced by technical specialists in communicating the results of technical and valuation studies to the investment community.As investors seek to take advantage of the current stage in the investment cycle, the key challenge of the technical specialist is to effectively communicate the uncertainty in technical assumptions, risks and opportunities that drive project value.CITATION:Fairfield, P J, 2016. Managing expectations – from buyer beware to buyer be aware, in Proceedings Project Evaluation 2016, pp 66–74 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By Robertson AC

Studies by Tennent, Isokangas Pty Ltd (TIP) have indicated that underground quarrying of backfill may be a cost competitive option for providing backfill for specialised situations in underground mining. Situations where suitable bulk fill material may not be available on the surface, and where the total cost of setting up a fill distribution system are prohibitive, could favour the mining of fill material underground adjacent to the stopes being mined. Considerations include environmental impact, scheduling, surface constraints and total costs. The examples quoted in this paper, and the case studies are based on the authors' personal observations and experience.

Jan 1, 1998

By R Winterberg

Concrete is a well established and reliable construction material for the permanent lining of tunnels, but shows some weak performance characteristics, which can be overcome by the addition of specialised fibre reinforcement. This paper addresses the particular performance design requirements of segmental linings, discussing the improvements of fi bres on concrete properties. Focus is made on the beneficial effects of fibre reinforcement on the cracking behaviour and the toughness performance, providing a safe and durable tunnel lining.Not only the mechanical performance of fibre reinforced concrete (FRC) for segmental linings, but also the durability of the linings has gained growing attention among the designers and consultants. Especially tunnel linings with exposure to media with corrosion potential, such as wastewater sewer tunnels or desalination plant outfall tunnels, have high requirements on their durability. The design of these structures must provide a comprehensive study of durability aspects. Fibre reinforcement can substantially improve the durability of concrete.Research has been carried out on the cracking behaviour of concrete. The beneficial effects of steel fibres on the cracking behaviour reduce the permeability by reducing the flow paths within the concrete. Crack bridging steel fibres create necking effects in bending cracks, leading to earlier closure of the cracks. Further, steel fibres create particular crack formations, which lead to a substantial reduction of the fl ow rates through separation cracks. The results also show that considerable cost savings can be achieved using FRC, as the thickness of the linings can be reduced.The durability design issues will be addressed and underlined by a case history on the Hobson Bay sewer tunnel in Auckland, New Zealand.

Mar 8, 2011

By P J. Bangerter, J Pan

Optimising for Net Present Value (NPV) with a strategic optimiser such as COMET, Prober-E, Blaser or Minemax has hitherto lacked a dynamic method for analysing the so-called third-order outcomes (such as Carbon emissions) of optimisation within life-of-mine planning. Optimisation, per se, has natural effects on carbon emissions in a life-of-mine plan. Contemporary strategic planning employs a mathematical optimiser to make sense of non-linear data (ie a block model) and produces a best-NPV optimised mining schedule, within a set of constraints. The very act of optimisation influences emissions, and in a dynamic way.

Aug 2, 2023

By N Maistry, A Singh

It is estimated that in less than a decade, high-grade iron ore reserves in South Africa will be depleted, leaving only low-grade ores with a dominant lithology of banded iron formation (BIF) hematite. BIF is a complex ore reserve as it is typically liberated below 1 mm, resulting in high energy costs. However, due to its abundance, its beneficiation potential should be evaluated to maximise recovery at an acceptable product grade. To develop a beneficiation program for BIF hematite, the first step is to determine the effect of two laboratory crushing techniques on mineralogical characteristics, specifically liberation and shape. For this study, the cone crusher and high pressure grinding rolls (HPGR) were used. The Electron MicroProbe Analysis (EMPA) and Mineral Liberation Analyser (MLA) were used to compare the mineralogical characteristics. The liberation characteristics for hematite are similar for both crushing techniques; however, HPGR preferentially liberates quartz. HPGR achieved 8– 12 per cent additional quartz liberation in the greater than 80 per cent and 100 per cent liberation classes respectively and specifically in +75 μm size range. Improved quartz liberation is associated with lower energy requirements for downstream milling and improved separation efficiencies for beneficiation units that operate in this size range. Both samples displayed similar shape characteristics; most particles were elongated smooth and the rest were elongated angular. Good hematite liberation is expected at grinds of 212 μm to 150 μm. Further consideration should be given to throughputs, energy efficiency and downstream equipment selection prior to selecting a crushing technique.

Sep 18, 2023

By Wilson AC

Permian coal from Western Australia's only producing coalfield at Collie is the dominant fuel used in generating electricity for the State's interconnected grid. Collie coal is sub-bituminous, non-coking and has a low ash, medium volatiles and high moisture content. The seams were laid down in a fluvial basin which extended beyond the Collie Basin and included the Wilga and Boyup Brook Basins at least. Adjacent parts of the southwest Yilgarn Block are prospective for Collie-type basins. In the past few years significant deposits have been delineated within the Perth Basin, specifically on the Vasse Shelf and in the Hill River area. In the former area high quality steaming coals are correlated with the lowest coal bearing member at Collie. The seams are amenable to underground mining and because of their high quality, the coal may have export potential. Sub-bituminous coal deposits of Jurassic age are present in the Hill River area. Exploration has down-graded the prospectivity of the Carnarvon and Canning Basins for sub-bituminous near-surface coal deposits. Tertiary lignite deposits are present in palaeo-drainage systems in the southern part of the State and their potential for development is being evaluated.

Jan 1, 1986

By A D. Campbell

The Homer Tunnel is located in a remote area of the South Island of New Zealand and carries large numbers of tourists to Milford Sound through an avalanche prone area. The tunnel is 1280 m long with a steep ten per cent unidirectional grade descending to the west. Construction of the tunnel began in the 1930s and was completed to a nominal 6 m width in 1954. In 1996, two passing bays were stripped-out to accommodate bi-directional flow of tourist coaches. During all phases of construction and widening there have been episodes of strain bursting.The condition of the tunnel and standard of internal services is below current international practice, principally in terms of; in-tunnel air quality, fire life safety, ground support, and road safety. A number of near-miss events have occurred involving coach fires on the approaches and inside the tunnel. The national road authority, NZTA, is considering a substantial investment to improve amenity and safety of the tunnel.This paper describes the rationale for the proposed upgrade works and the investigations undertaken to enable that design. A holistic approach to road tunnel safety has been adopted that balances the key interrelated safety drivers, namely; tunnel lining, traffic operations, ventilation, power supply and egress while ensuring continuity of safe access to Milford Sound.

Mar 8, 2011

By Partridge AC

The measurement of particle size is very important in many industries. Comments in this paper refer principally to the Mineral Industry and in particular to Coal Mining and Coal Preparation. The objective is to indicate the importance of particle size in process design and process assessment and to describe techniques for particle size measurement and the presentation of results.

Jan 1, 1984

By A Fowler

The unpredictability of the location, grade and width of narrow-vein deposits presents difficulties for mine geologists and engineers attempting to estimate, schedule, forecast and mine their deposit profitably. This unpredictability stems not only from the grade distribution within a vein, but also the irregularity of vein geometry in three-dimensional (3D) space. Traditional deterministic methods of modelling vein geometry do not account for the inherent variability of the veins, resulting in significant errors when using limited drill hole information. This paper presents a probabilistic method of modelling narrow-vein deposits using sequential gaussian simulation (SGS), which can quantify this variability and improve production forecasts. Vein geometry, thickness and grade are simulated to provide a number of different equi-probable realisations that each honour the drill hole and face sample input statistics. An example is presented from the Augusta narrow-vein Au-Sb mine in central Victoria, where the simulation results are validated against the input data and survey pick-ups of the veins along ore drives.

Aug 22, 2011

By Bucknell WR, Clarke DE

The paper provides a company's view of the relative merits of various valuation methods and outlines the basic approach it takes to the valuation of an exploration property. The negotiating process and methods of acquiring an interest in an exploration property is discussed The valuation methods discussed are: 1. Exploration Expenditure. 2. Real Estate. 3. Joint Venture Terms. 4. Rule of Thumb. 5. Net Present Value - Discounted Cash Flow. 6. Geoengineering.

Jan 1, 1994

By Morgan B. D

Since the mid 1950s, limonite deposits of a new type have been found in the northwest of Western Australia. The deposits consist of extensive fossil valley fillings up to several hundred feet in depth, of medium to high grade limonite, frequently containing limonitized fossil wood, and of Mesozoic or Tertiary age. The distribution of the deposits is closely linked with hilly outcrops of Archaean and Proterozoic jaspilite in the headwaters of the old valleys, from which the iron has been derived by leaching, and presumably re-precipitated by a process not unlike that which operates in forming bog iron deposits. Due to the relative resistance of tlie limonite to erosion, the rejuvenation of streams in the area in recent times has left limonitic remnants as mesas up to· several hundred feet above the levels of the present creeks, the courses of which generally are adjacent to or within a few miles of those of the old limonite filled valleys.The Robe River limonite deposits are the largest of this type known and can be traced for approximately 130 miles along the old stream, over 30 sq. miles of limonite remnants remaining at the present time.The present quantity of limonite in this system alone is probably in excess of 5,000,000,000 tons, and the original quantity must have exceeded four times this tonnage when allowance is made for erosion.Some thousands of millions of tons of this material contain in excess of 54 per cent Fe, with approximately 10 per cent combined water. The chief impurities are SiO2 and Al2O3, and minor elements are not present in objectionable amounts. A portion of these deposits was extensively tested by The Broken Hill Proprietary Company Limited (the B.H.P. Co. Ltd.) during 1962-1964. Most of the data presented in this paper are based on the work done on these deposits which are typical of those discussed. The overall problem of the origin of the limonite is discussed. It is apparent that the limonite originates from the jaspilitesof Archaean and Proterozoic age which form the highlands at the upstream ends of the deposits. The iron oxide has been chemically and/or mechanically derived from these jaspilites and deposited by one or more of the following mechanisms.A.-Chemical-sedimentary mainly by biological agenciesB.-Replacement of fluviatile sediments by iron-charged watersC.-Clastic sedimentary processesD.-Lateritization of fluviatile sediments.These various mechanisms are discussed; the authors favour machanismA.Manuscript received' at The Institute, 14th July, 1964.

Jan 1, 1964

By T Napier-Munn, E Louwrens, L Keeney

Geometallurgical characterisation of ore deposits is accepted practice in some parts of the mining industry today. Its primary aim is to provide constrained inputs that reflect inherent geological variability and its impact on metallurgical performance for the deposit. Geometallurgy improves project value because it suggests more valuable alternatives for scheduling and processing through an increased knowledge and understanding of the interactions of rock properties and extractive technologies. Lower project cost (both capital and processing) and improved recoveries are the result from closer tailoring of the mining and mineral processing strategies to the characteristics of the resource (Dunham, Vann and Coward, 2011). Tailings storage facilities (TSFs) can be seen as potential resources and it is argued that fundamental geometallurgical characterisation as applied in ore deposit characterisation should also be applied to planning the retreatment of TSFs. This paper will describe a research project at Julius Kruttschnitt Mineral Resource Centre assessing if geometallurgical principles and methodologies can successfully be applied to TSFs as they have been to primary deposits. The project is establishing a new standard method of tailings evaluation which will include a 3D spatial model of the tailings resource. Initial domaining of the TSFs was done using principal component analysis followed by k-means cluster analysis based on chemical assays from drill core samples. The subsequent characterisation of the drill core samples has involved chemical, mineralogical and metallurgical profiling, with a range of metallurgical tests being conducted on the samples. This characterisation step is followed by class-based analysis, predictive modelling and process performance domaining with the ultimate objective of establishing a 3D spatial model incorporating geochemical, mineralogical and metallurgical performance data. This approach, which takes into account processing performance permits a more realistic (as compared to doing limited chemical assays and metallurgical testing) economic evaluation of the potential of reprocessing the tailings material. It is believed that the approach is generic and can be applied to other TSFs being considered for reprocessing. The present case study has also established the gold, copper, magnetite and cobalt deportment for an iron oxide copper-gold deposit tailings resource.CITATION:Louwrens, E, Napier-Munn, T and Keeney, L, 2015. Geometallurgical characterisation of a tailings storage facility – a novel approach, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 125–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By Skinner W, Netting A. K O

Surface analysis of ore samples collected from corresponding concentrate and tailings process streams is now a widely used tool in many Australian base metal sulphide concentrators, particularly those involved in AMIRA projects. The use of tec

Jan 1, 1997

By M Ozkayhan, N Arslan

"The Efemçukuru underground mine in western Turkey is an intermediate sulfidation, epithermal gold deposit. The bulk of the mineral resources and all of the mineral reserves lie within the Kestanebeleni (KB) vein system. This system comprises four spatially-distinct mineralised zones: the south ore shoot (SOS), the middle ore shoot (MOS), the north ore shoot (NOS) and the KB north-west ore shoot. Production currently occurs only in the SOS, MOS and NOS zones. The gold mineralisation is very fine grained and occurs as free grains in quartz and carbonate, and as inclusions in sulfide minerals. Gold is recovered as part of a sulfide concentrate by flotation methods. Though hosted in the KB vein, the gold mineralisation is not evenly distributed within the veins. Definition of its occurrence is totally dependent on diamond drilling.Diamond drilling at Efemçukuru is done with its own equipment and staff, all managed by the mine geology group. The process over the mine’s six year production history incorporates continual improvement with an innovative approach by focusing on the following: drill team organisation career development and training product research and effective equipment management cost reduction planning and scheduling of development for drill stations.Over 40 000 metres of mostly BQ size core are drilled annually by three drill rigs at a cost approaching US$35/m.The planning and execution of the drilling pattern depends on the configuration of the ore shoot and the planned mining method. Ore extraction is mainly by drift and fill mining augmented by about 15 per cent longhole stoping. The drilling of a specific area is scheduled to be finished 3 to 8 months prior to mining. This scheduling is sufficient for short-term grade model updates and any needed changes to the planned development or stope sequencing prior to planned production from the stope area.CITATION:Arslan, N and Ozkayhan, M, 2017. Diamond drilling at Efemçukuru gold mine, Turkey – a case study on the benefits of timely and cost-effective drilling to short-term planning, in Proceedings Tenth International Mining Geology Conference 2017, pp 285–290 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

By T Angerer, N H. Maund, S Hagemann, D R. Cowan

Cliffs Natural Resources Pty Ltd - Asia Pacific Iron Ore's (formerly Portman Iron Ore Limited) K deposit (Dowd's Hill), at its Koolyanobbing operation in Western Australia, hosts enriched magnetite mineralisation below the presently mined haematite-goethite ore zone. Two distinct northwest-southeast elongated, highly magnetic anomalous bodies that dip to the north-east appear to be sourced by this deeper mineralisation. Magnetic modelling indicates significant remanent magnetisation with Qratios around 1.5, directed shallow down. The north-west anomaly is overlain by a ridge of uneconomic banded iron formation (BIF) and the present waste dump, whereas the south-east body was partly exposed during ongoing mining of overlying haematite-goethite ore. Sections of the magnetite mineralisation in this south-east anomaly were intersected previously by diamond drill holes. Review of the historic cores identified potential magnetite enrichment, with grades and mineralogy that might be amenable to beneficiation. A first-phase reverse circulation drilling program was designed to further delineate the trend and extent of the two anomalies. The following magnetite mineralisation assemblages are recognised from cores, reverse circulation (RC) drill cuttings and pit mapping of the south-east magnetic body: higher-grade magnetite-haematite ¦ goethite and magnetite ¦ pyrite and lower-grade, recrystallised magnetite-quartz (BIF), magnetite-carbonate, magnetite-talc and minor magnetite-bearing mafic schist. Disseminated specularite is locally present in theassemblages. Talc-schist and massive pyrite occur along the footwall contact. Magnetic susceptibility measured from drill chips within the magnetite-enriched zones reveals an apparent susceptibility values range of 0.2 to 1.3 SI. Preliminary results from Satmagan and Davis tube recovery analysis shows that the magnetite content in these mineralised zones correlate well with existing geophysical data and magnetic susceptibility measurements.

Jan 1, 2009

By Torrance AC

A joint research programme conducted by BHP Central Research Laboratories and Du Pont Wesfarmers Pty Ltd examined the effect of the size of cast primers on the run up and steady state detonation veloci- ties of ammonium nitrate based explosives as a function of blasthole diameter. Both continuous and point to point velocity of detonation meas- urement techniques were used. The field trials examined a number of the Du Pont HDP series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the run up velocity of 187mm diameter ANFO charges is negligible using cast primers as small as 150g. owever, emulsion and watergel explosives did exhibit run up in both 187 and 311mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blasthole diameters.

Jan 1, 1988

The 8 ft by 91/2 ft drive which joined No. 7 Shaft with Browne Shaft on the 1,480 ft level was extended from both ends and met at a point approximately 12,000 ft from No. 7 (2,000 ft from Browne).The surveying required for this 2 1/2 mile haulage drive called for greater accuracy than was obtainable from South Mine standard methods. Procedures and devices from published information were tried and modified as required to suit local conditions. Several new methods were applied and improved as the drive advanced. The control of angular, linear and level measurements was perhaps considerably in excess of the requirements, but this was offset by abnormally large discrepancies resulting from shaft plumbing. The accuracy of the final breakthrough, although not to the standard desired, was sufficient to complete the connection without inconvenience and added cost.INTRODUCTIONThe acquisition of the Browne Shaft leases in January 1962 presented the management of Broken Hill South Limited with the problem of transporting ore from these leases to its mill. It was eventually decided that diesel locomotivehaulage through a 2t mile drive on the 1,480 ft level between the two mines was the best solution. The drive was advanced from both ends after Browne Shaft was deepened by 80 ft to reach the 1,480 ft level horizon. Each end advancedabout 15 ft/day with the miners working three 7 hr shifts. Blasting was restricted to the end of the shift.The survey work involved five shaft plumbings and 78 theodolite stations in a traverse, underground and surface,of more than 5 miles. Because of the exceptional length of the drive, an unusually high degree of reliability was required.The aim was for a maximum error at breakthrough of 1 ft 1 in 30,000, and to secure this, precise methods of linear measurement were necessary. Shaft plumbing in particular posed special difficulties.

Jan 1, 1965

By P Cameron

MetPlant conferences have focused on ensuring mining projects are well designed then optimised to operate safely and effectively at the top end of world’s best practice to ensure shareholders are not just happy but delighted. This assumes the MetPlant was built right the first time. However, reality is, too often Plant Metallurgists (PlantMets) find after commissioning they are faced with the expensive task of correcting errors or modifying shortcomings to achieve product quality at name-plate capacity, i.e. get it right the second time. Why do companies spend good money to engineer an excellent feasibility study then allow “wise men” remote from the project team to impose cuts in budget and schedule, often under the guise of value engineering? Since mining is full of uncertainties, such actions can increase the risks of failure with the result that some MetPlants do not work well. Can PlantMets influence the remote wise men who often are also imposing the rules for lending and the required returns to appreciate the uncertainties of mining and their associated risks then let the project team get it right the first time? PlantMets can negotiate with the wise men from the outset of the project and bring them into an outer layer of the team where they can understand the risks then share responsibility and accountability to achieve the common goal of building a MetPlant which works well the first time and deliver the forecast profits. Since shareholders are not in the business to make losses they appoint a Board of Directors to deliver the best outcomes for the shareholders. Thus the Board should seek effective advice on the risk reward implications from the PlantMet before making their decisions.CITATION:Cameron, P, 2015. Do all metplants work well? PlantMets can ensure they do, in Proceedings MetPlant 2015, pp 2–9 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By D Lees, D Gilchrist

Sydney has hundreds of kilometres of sewer tunnels. Many of these are over 50 years old and some have been in service for more than 100 years. The tunnels are predominantly constructed in Hawkesbury Sandstone and many are unlined.Principles have been developed over many years for the safety factor required in designing and constructing new tunnels but these do not necessarily relate to the operation and maintenance of existing tunnels, and in particular those that do not necessarily require personnel access for anything other than regular inspections.Assessment of the stability of these established tunnels needs to take account of their size, their age, their function, and their method of construction, as well as the geology in which they are situated and any support measures which have been installed. More importantly a stability review needs to take account of the consequences of a collapse, with regard to the inspection process, carrying out of any required repairs and the long-term performance of the tunnel.This paper is based upon the authors’ experiences inspecting and reviewing more than 200 km of tunnel in the last ten years. It will show some of the procedures and methods adopted by Sydney Water, how these can be presented as an acceptable procedure in line with other safety standards, and how they might be adopted for other similar historic rock tunnels.CITATION:Gilchrist, D and Lees, D, 2014. The development of a procedure for the inspection of unlined rock service tunnels, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 543–552 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By L A. Martinez Tipe, J McKibben, S Barry

"Metal prices are central to a mineral investment decision and have a profound impact on the financial performance of companies in the mining industry. At its most basic level, metal prices are influenced by the disequilibrium between international metal volume supply and demand. That is, the commodity price is a regulator that equates international metal supply and demand where inventories act as a buffer between the emergence of this disequilibrium and its dissolution through a price change.From this viewpoint, mining companies are required to forecast metal and bulk commodity prices when evaluating minerals projects through discounted cash flow (DCF) analysis. While supply-demand models are instructive, many companies use historical prices, spot prices, futures/forward pricing and consensus opinion (or a combination of all of these) to develop price forecasts.This paper discusses the definition, fundamentals and differences between futures/forward and consensus pricing and the appropriateness of each in a DCF model for mine project economic evaluation.Our results demonstrate that great care is required when using either futures/forward or consensus pricing and that the decision to use one rather than the other requires consideration of other important elements in the DCF model (ie the risk-adjusted discount rate).CITATION:Martinez Tipe, L A, McKibben, J and Barry, S, 2016. Metal prices and the differences between forward and consensus pricing – which one is better for use in a discounted cash flow model?, in Proceedings Project Evaluation 2016, pp 149–158 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016