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By R Graber, R Johnson

North American steelmaking practices have evolved based on access to iron ore raw materials containing very low phosphorus contents, typically less than 0.025 per cent P. Cleveland-Cliffs managed Tilden iron ore operation produces iron ore pellets exceeding 0.030 per cent P, which by global standards would be considered low phosphorus, but has limited penetration in the North American iron ore market due to phosphorus content. Recently cathodoluminescence microscopy has augmented more standard ore characterisation techniques enhancing our understanding of the genetic history and process mineralogy of TildenÆs complex martite ore. This paper highlights the unique capabilities that cathodoluminescence microscopy provides for phosphorus mineral identification in fine-grained iron ores.

Jan 1, 2005

By U JSger

The Westerschelde tunnel will be the first permanent road link between the Dutch regions of South Beveland and South Flanders. Two tunnel tubes, each 6.6 km long, will be driven using the shield tunnelling method. The difficult ground conditions and a water pressure of up to 6.5 bar make great demands on the design. This paper describes the problems and their solutions.

Jan 1, 1999

By O N. Antzutkin, W Forsling, K J. Pike an

The adsorption mechanism of three different O,OÆ-di-alkyl-dithiophosphate (dtp) collectors, K[S2P(OR)2] with R = Et, i-Bu and i-Amyl, on the surface of synthetic chalcocite (Cu2S) was studied by means of solid-state 31P CP/MAS NMR spectroscopy. The morphology changes on the conditioned Cu2S surfaces, in the collector concentration range 0.1 - 10 mM, were also monitored with scanning electron microscope (SEM). In order to assign Cu(I)-dtp species on the surface of Cu2S, the corresponding bulk Cu(I)-dtp compounds, which are clusters of the monovalent copper containing either Cu6(antiprismatic) or Cu8(cubic) cores, were synthesised, and characterised by means of solid-state 31P CP/MAS and static 65Cu NMR. Further investigations on the crystal habits of the bulk systems were carried out by powder x-ray diffraction and SEM. A comparative analysis of the 31P chemical shift and chemical shift anisotropy (CSA) data estimated from the experimental NMR spectra of the polycrystalline bulk Cu(I) dialkyldithiophosphate complexes was used for assigning the 31P resonance lines in the NMR spectra of the collector treated Cu2S powder samples. The species formed on the synthetic Cu2S surfaces were assigned to polycrystalline phases of: Cu6L6 with L = Et2dtpû, Cu6L6 and Cu8L6(S) with L = i-Bu2dtpû, and Cu8L6(S) with L = i-Amyl2dtpû. A heterophase autocatalytic step process of both formation and growth of solid CuxLy (L = R2dtp, x = 6 or 8 and y = 6) complexes on the collector treated Cu2S surface is proposed. A possible role of the oxidised form of dithiophosphate collectors, bis[di-alkyl-thiophosphoryl]-disulfane (disulfide), is discussed in terms of a specific self-redox reaction. The second order quadrupolar lineshapes in 65Cu NMR spectra were simulated and the interaction parameters, CQ and hQ, for the bulk dialkyldithiophosphato-copper(I) complexes were obtained.

Jan 1, 2005

A description is given of a detailed examination of a coal bore core and of attempts to predict properties of equivalent "as-mined" coal using the bore core data so obtained. The accuracy of the prediction was measured by testing independently a large sample of coal which was produced under near mining conditions from a site adjacent to the bore core. Very encouraging results were obtained particularly in the prediction of size and ash distributions and washability characteristics of run-of-mine Coal.

Jan 1, 1972

By J Ranford, A Harris, K Laughton

The Angas Zinc Mine (Angas) is a poly-metallic, underground mine in the Adelaide Hills that has been developed through arguably one of the most volatile financial time periods in living memory. From boom times during the commencement of the project, the global financial crisis (GFC) through the stabilisation of the operating period and then a subdued capital market for the period where mine life extension was targeted, the financial environment has always presented a different set of challenges. Indeed even the Underground Operators’ Conferences that have been held across the span of the project allude to these changes: ‘Boom and Beyond’, Launceston (2008); ‘Safe, Innovative and Sustainable’, Canberra (2011) and ‘Managing the Margin’ in Adelaide (2014).Angas gives a rare opportunity to see the entire life-of-mine of a project and its economic performance within a relatively short time frame. Angas, owned and operated by Terramin Australia Ltd (Terramin), will have undergone resource estimation drill out, feasibility study, permitting, commissioning, operating and completion and rehabilitation all within a period of approximately ten years. A number of sensitivities of the project were tested, particularly in the bankable feasibility study (BFS) stage and the aim of this paper is to identify the factors that impacted the operations profitability the most, whether they were identified preproduction or not. The key sensitivities assessed in the BFS were typical of similar studies, including operating costs, metal recoveries, capital costs, zinc prices, lead prices and exchange rates. The manner in which these sensitivities presented themselves in real life were not as anticipated and modelled in the feasibility study and were also heavily impacted by technical challenges.CITATION:Harris, A, Laughton, K and Ranford, J, 2014. Feasibility to mine completion – the real impacts on project economics, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 99–110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By R Bunduwongse

The oil crisis had repercussions throughout the world and most importantly on mining, where the drive to reduce the use of liquid fossil fuel led directly to the appearance and subsequent growth in the design of mobile crushers in late 1970s early 1980s, which heralded a new era in both quarrying and mining. Even though mobile crushing has now become common, even preferred in the quarrying industry, this has not been the case in mining. This paper looks at why, in spite of the initial optimism, this technology has yet to gain full acceptance in the mining industry. The paper examines some of the problems that have been encountered in the past and offers suggestions as to how they can be avoided by applying the appropriate technology. It then takes a look at the successful application of the semi-mobile in-pit crushing system used by Italian Thai Development Company (ITD), on the Mae Moh Phase 5 contract and examines how the techniques used successfully there could be applied to the industry at large.

Jan 1, 2007

By Voss Smith F, Matters C. W, Slee R. T, Coldham JC, Davies HW, Wallman H. H

The Committee desires to thank the managers of the various mines along the line of lode for their hearty co-operation in its labours. It would also extend thanks to Messrs. J. O. Moulden, Howchin, Twelvetrees, and the West Australian Geological Survey for various information; to Messrs. J. G. Dreyer, S. Pope, T. Read, P. Moncrieff, R. Williams, and W. J. Rose for analyses; and to a number of local gentlemen for advice and help. Professor Skeats, of the Melbourne University, gave much valued assistance in petrology, and Mr. Herbert Lavers kindly undertook the study of the garnets.INTRODUCTIONThe famous Broken Hill lode is situated in a low range of hills, the Barrier Ranges, near the western border of New South Wales. It has been worked since 1884-first for, silver, then for silver and lead, and at present for lead, silver, and zinc. No excuse seems necessary for placing before members even an imperfect report on the geological features of this notable ore deposit, since so little work has been done on the subject as to constitute almost a national reproach. This is the more deplorablesince the evidence laid open by mining operations is destroyed almost as soon as it is exposed, and there exists the real need of a continuous and connected record of geologieal developments.

Jan 1, 1911

By J S. Petersen

The occurrence of coarse gold particles leading to grade complexity and sampling challenges is a common feature of many gold deposits. Poorly designed sampling protocols applied to these deposit types can lead to an excessively high fundamental sampling error. Together with other errors, the fundamental sampling error contributes to the nugget effect. Proper sample collection, preparation and assay protocols are required to minimise this error, and hence reduce the total nugget effect. Reduction of the nugget effect is a key requirement for subsequent geostatistical resource estimates to be effective. A case study from the Nalunaq gold mine in Greenland is presented, which is characterised by notable quantities of coarse gold (>30 per cent +100 ¦m gold) hosted in quartz veins. Diamond drilling provides a good measure of gross geological continuity at practical grid spacings, but is not considered to represent the mineralisation effectively. On-reef development with face and bulk sampling, together with detailed geological studies were undertaken during the resource delineation phase. This contribution describes the nature of the Nalunaq deposit, its gold particle size characteristics, how sampling and assay protocols were developed (including QA/QC issues), application of GyÆs sampling theory and its calibration, and how the data was subsequently applied to grade estimation.

Jan 1, 2005

By O Dahl, I M. Platten, E J. Sides

Many narrow-vein gold deposits are characterised by a high to extreme nugget effect and the presence of coarse gold. They rank amongst the most difficult of deposits to produce an accurate and precise resource estimate. This contribution presents a case study from the Nalunaq Gold Mine in Southern Greenland. The mine commenced operation in May 2004 and is currently operating at a rate of 400 tonnes per day, to produce about 100 000 oz gold per annum from a total resource base of 1.2 Moz. Mineralisation is characterised by quartz veins that are hosted within a shear zone that is continuous over about 1000 m. The principal orebody is the Main Vein structure, which ranges up to 3 m in width, maintains an average dip of 35¦SE, and contains significant gold grades (1000s g/t Au). Gold particles are often visible, with 25 per cent being greater than 250 microns in size. Variography using underground development samples indicates a nugget effect of about 75 per cent. For the 2005 resource estimate, a 2D metal accumulation ordinary kriged block model was used to produce a global grade for the Target and South Blocks of the Main Vein. Grade control chip-channel samples are collected from æshantyÆ drive footwalls, and used as the basis for both the kriged block model and to determine the grade of individual stope blocks by peripheral weighted averages. Geology plays a key role in mining efficiency, given the locally variable nature of the ore zone.

Jan 1, 2006

To finalise the arrangement and details of the headframe to be erected over the new No. 3 Shaft, the haulage and winding equipment requirements were first determined, then tentative designs were prepared to cover the needs of general shaft servicing work for men and materials, mullock and ore handling, and the probable requirements of a breaker station to be built adjacent to the headframe, which would provide for the crushing of the run-of-mine ore down to a size which would be suitable for feeding on to the concentrating mill.

Jan 1, 1957

By S Long, A J Koen, D MacKay

The Mt Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Following the evolution of the mine plan through a number of stages, the ‘sublevel shrinkage (SLS) with continuous fill’ mining method was implemented in 2010 to extract the Mt Wright orebody. The production front in this mining method is similar to a sublevel cave (SLC) operation; however, backfill is placed into the top of the production zone as opposed to requiring the overlying strata to cave.Continuous fill to replace the void created by extracting the ore was required to manage the potential risks associated with the proximity of infrastructure to the footwall, associated long-term stability and air blast potential due to the limited ‘cavability’ of the material within the cave zone. The available fill material was sourced from a disused waste dump from a previous open pit operation, which introduced further technical and economic risks associated with dilution from ‘no grade’ broken material. Procedures and processes to manage these risks have been incorporated into the operation of the mine.Despite encountering a number of challenges, the SLS method has been in use for approximately three years at Mt Wright and has proven to be viable economically, technically and operationally. This paper will discuss the challenges encountered and what was done to overcome them, the operational and financial performance to date, along with the outcomes of some successful continuous improvement projects that have improved the efficiency of the operation.CITATION:Mackay, D, Long, S and Koen, A J, 2014. Sublevel shrinkage – the Mt Wright story, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 205–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By F J. van Zyl, C A. S Thomson

"Anglo American Thermal Coal conducted a high level study of all of its underground collieriesto determine if there were electrical power saving opportunities at the main fan stations.A systems approach to electrical power savings was used to identify potential savings in the various components of a primary ventilation system. Furthermore, only technological interventions were considered to obtain electrical power savings. From generic technological driven electrical power saving strategies four energy savings strategies were identifi ed, namely potential overall reduction in ventilation volume, improved underground air utilisation, optimisation of fan-set effi ciency and potential fan drift design optimisation. The study indicated the colliery (say Colliery D, Shaft A) that showed most potential in the four technology driven energy savings strategies. A detail study was undertaken at Colliery D, Shaft A to increase the confi dence level and the study confi rmed that up to 45 per cent of the main fan absorbed power can be saved (475 kW) with an estimated capital payback period of 18 months. The study clearly showed that an integrated approach to optimise the entire mine ventilation system has great potential for power saving, and that a clear, well -defi ned methodology will be applicable to similar underground collieries. This paper discusses the background to the study and the process followed to implement the energy savings initiative at Colliery D, Shaft A."

Jun 1, 2012

By J P. Sykes, A Trench

Mineral commodity prices are subject to volatility over both the short and longer run – driving fluctuating operating margins for mining companies over time. Such market dynamics influence mine operating decisions depending on the interplay of company-specific and mineral market factors. The company factors include corporate financial strength and price-risk management strategy, as well as mining practices and methods at the operation level. The critical mineral market factor is the price of the ex-mine product. This results from underlying microeconomic and macroeconomic root-causes pertaining to mineral supply and demand, in addition to the activities of financial participants within commodity markets.Significant changes in commodity prices of an extended duration, either up or down, remain the principal influence upon mine economics – and therefore on mining practices too. Accurate and precise forecasting of commodity prices (and of relevant exchange rates) continues to prove elusive both to mineral economists and market analysts. Thus, at any given point in time, there are often widely differing price forecasts available for both the relevant commodity and currency. Companies as a result are unclear how to respond in practical operating terms to such price-side uncertainty – other than to manage incremental capital and operating expenditure. Typical company – and industry financier – responses to the difficulty in predicting future mineral commodity prices are to take measures to manage uncertainties in mining project revenues and costs. These operating practices are prudent – yet come at an economic cost: that is, lost revenue and margin opportunity is inevitable in any such system not easily capable of responding to price volatility in the market. The mine of the future will seek to capture this lost economic opportunity. This paper presents a three-stage framework for analysing commodity price forecasts to aide understanding of the commodity price cycle and the periods of high-margin opportunity.CITATION:Trench, A and Sykes, J P, 2014. Perspectives on mineral commodity price cycles and their relevance to underground mining, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 19–32 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

A new national-scale geochemical survey is under way inAustralia with the aim to provide energy and mineral explorers with state-of-the-art precompetitive data and information about the continentÆs potential resources. This low-density geochemical survey will provide a national geochemical data layer using consistent sampling medium and sampling, preparation and analytical methods. Large-scale geochemical patterns thus revealed are expected to point to new areas of exploration potential. The project is funded under the Onshore Energy Security Program. It is hoped that this new national geoscience dataset will help make Australia a more attractive destination for energy and mineral exploration investments. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Lynce AJ

A method has been developed for the prediction 'of 'the- . performance of a multi-stage grinding=cyclone classification circuit of any degree of complexity on any ore for a wide range `of operating conditions, The-.method involves ;the. s` inu ation b'f the circuit on a digital computer by means of. matheinatical' models ":bf the"' individual units:, the. development of which is- also discussed'., At present, in order to establish 'the!'" charac'teristtics of they ¦ore- and the machines. in mathematical terms;. it is necessary to know'the performance of a , simpl,.e. ; system on tri.e ore - for! one known ,,feed rate and.fe.ed s,l-zing, analysis. ' ,Fiiither work on :the- separate identification 'of the terms defining the characteristics of the ore and the machines may permit the method to be, applied directly to the cj.4ta,derived from small scale tests on ores,

Jan 1, 1964

By T Leach, F Kaiqiang

The Jianchaling gold deposit is located about 1200 km south west of Beijing in central China. The deposit was discovered in 1988 by the Northwestern Geological Exploration Bureau (711 Exploration Team). Sino Gold Limited, an Australian based company, developed the mine in 1998 and is currently operating a 1000 t per day underground mine, producing about 80 000 ounces of gold per year. The pre-mine resource for Jianchaling was 1.6 million tonnes at 9.85 g/t gold. The deposit occurs within the east-west trending Mesozoic Qinling-Dabie orogenic belt formed during the Yanshanian Orogeny. In the Jianchaling region, gold mineralisation is primarily hosted by regional west-northwest to east-southeast striking faults, the most important of which, the reverse sinistral F145 fault, hosts the larger gold deposits including Jianchaling. At the mine scale, the most important zone of mineralisation is localised within a shallowly north dipping dilation on the F145 fault. Proterozoic dolomite forms the hangingwall and serpentinite and talc schist the footwall to the fault. Within the footwall, serpentinite is the most important host rock to mineralisation. Initial alteration involves replacement of serpentine to dolomite ¦ pyrite, talc to ankerite ¦ pyrite, and magnetite and chromite to pyrite, the latter locally through a transitional hematite phase. Proximal to feeder structures, the carbonate minerals have undergone partial dissolution and replacement to quartz. Gold is related to arsenean pyrite and marcasite rimming and replacement of early-formed pyrite, and associated with iron release during the processes of dolomitisation, silicification and carbonate dissolution.

Jan 1, 2004

During the later part of 2007 I was lucky enough to visit the Atlas Copco facilities in Sweden, and to see first hand what a large and diverse company Atlas Copco is. The reason this paper calls the Atlas Copco experience a bonanza is that it means a source of great and sudden wealth or luck; a spectacular windfall or a rich mass of ore, as found in mining. I think this aptly describes the scholarship as it has greatly increased my wealth of knowledge of the mining industry. This paper intends to encourage all those eligible to apply for this fantastic scholarship opportunity, and seeks to thank all those involved who made this scholarship the amazing experience that it was. Atlas Copco produces most of its Swedish products in the town of +rebro, and it was here that I spent most of my time, visiting the Underground Rock Excavation group, the Surface Mining Equipment group and Rocktec. I also travelled around Sweden and was able to visit one of OricaÆs manufacturing plants, the Secoroc groupÆs manufacturing plant, the Geotechnical Drilling and Exploration group as well as being fortunate enough to visit the LKAB mine in the Arctic Circle in Sweden. The trip was not all information on Atlas Copco products and services however; I was able to go to the Ice Hotel in JukkasjSrvi and drink Absolut Vodka out of ice glasses, go on a reindeer safari (as well as eat them!), sample the fine meat from a moose, drink local schnapps, attend the Atlas Copco Christmas party, wander around the wonderful city of Stockholm and generally immerse myself in the great Swedish culture.

Jan 1, 2008

The underground mining of a narrow vein hard rock orebody is a capital and labour intensive method of extraction. Due to the nature of underground mining it is difficult for higher level managers to physically see the efficiencies and inefficiencies of a particular method. Extraction methods and sequencing often need to be altered from the original planned methods as a result of mine developent, providing more in depth information as it progresses. As a result of these issues contract mining of these orebodies is common practice. There are several types of contract structures for the purpose of underground contract mining with many complex permutations of them that reflect the different needs of each individual company and orebody. The different contracts are arranged dependent on the mining companyÆs desire to transfer or, alternatively, embrace risk. This presentation gives a brief overview on these different methods and their various advantages and limitations with regard to small scale and narrow vein underground mining. With respect to these different contracting methods, the presenter reviews the mutual growth benefits of emerging partnering opportunities, specifically with regard to smaller explorers exploring and developing prospective mining tenements. The specific advantages to small explorers include the resource flexibility and speed of project development that private mining contractors can provide. Given the contracting methods that are available, there is potential for small private mining companies to gain minor stakes in major projects and major stakes in medium sized projects by employing innovative contracting solutions to provide mutual benefits to the parties. Some potential scenarios to this effect are suggested in the presentation. This paper is available as a PowerPoint presentation only.

Jan 1, 2006

By B Dunstan, F Wirfiyata

PT Newmont Nusa Tenggara (PTNNT) operates the Batu Hijau copper and gold mine and process plant on the island of Sumbawa, Nusa Tenggara (Barat)  NTB, Indonesia. The plant consists of a nominal capacity 120 000 t/d conventional semi-autogenous ball milling crushing (SABC) circuit followed by sulfide flotation to produce a bulk copper concentrate for sale. Process control is effected by a plant wide distributed control system that overlays an extensive integrated programable logic controller (PLC) framework. The system is enhanced by a supervisory expert control system.Since plant commissioning in September 1999, over US$4 million has been expended as part of a systematic continuous improvement approach to optimise plant control performance. Works completed to date include: redesign and upgrade of architecture of the control system to ensure long-term system reliability, security and upgradeability and to provide a suitable platform for advanced control; integration of supervisory and advanced control tools, techniques and instrumentation; and implementation of sound network communication and plant data reporting tools. This paper outlines the evolution of process control and associated systems and tools that contribute to successful operation and ongoing performance optimisation at Batu Hijau.

Jan 1, 2009

By McConachy G. W, Wright J. V

During the 110 years since the discovery of the Broken Hill PbZnAg deposit six major mining companies have mined the ore body and explored the ore environment. Despite this activity, no new orebodies have been found at Broken Hill. The failure to discover large new resources cannot be attributed to a lack of activity because major companies have maintained substantial exploration commitments over many decades. This suggests that not only was a unique coincidence of conditions required to form the deposit but also that full recognition and definition of the critical parameters may not yet have been recognised. In an attempt to illuminate some of the more unusual and poorly studied characteristics of the ore environment some new areas of investigation are presented here which may contribute to understanding the ore deposit setting and focus exploration towards different and perhaps more productive targets. Sedimentological characteristics of the host succession of the Broken Hill deposit are apparently unique along the line of lode. An upward-coarsening megasequence reflected in the development of clastic psammites stratigraphically below the ore deposit is one important ingredient which has received little exploration focus. These psammites also host mineralisation and form part of a spectrum of quart-zrich rocks collectively referred to as gametiferous psammites, garnet quartzites and blue quartz lodes. Sedimentological data interpreted from outcrop, drill core and downhole geophysical well logs support a elastic origin for some of these rocks; an interpretation which is at variance with traditional interpretations favouring an exhalative origin. A clastic origin for many of the footwall psammites, and their close spatial association with the orebodies suggests their role in ore formation was important. It is interpreted as a critical part of the fluid flow architecture within the sedimentary basin, which focussed ore forming fluids into an unique environment favourable for trapping mineralisation. Detailed stratigraphic correlation near the deposit has also highlighted that quartzofeldspathic rocks (Potosi gneisses and lode pegmatites) have complex relationships with ore. Suites of stratabound quartzofeldspathic pegmatites have received limited study, but their distribution and voluminous development suggests they may be as important to ore formation as the psammitic lode rocks which host the orebodies. These associations are not in conflict with some recent ore forming models invoking deposition in a shallow water environments of deposition. The geochemistry of parts of the host sequence has been studied extensively in the past but this has not been merged with current stratigraphic subdivisions. A large drillhole data base now permits the geochemistry to be related to the sedimentary succession and reveals that a signature involving stratigraphic vectors best illustrated by changes in MnO, Na2O, Pb and Zn can be detected. This is interpreted to reflect sedimentary basin processes as opposed to a classical volcanic hydrothermal alteration pipe associated with seafloor venting. The stratigraphic setting together with characteristics of some of these poorly understood areas is discussed to emphasise that construction of sound models for exploration requires the total ore environment to be studied with attention directed to the geometry and setting of the full range of host rocks. Control of the greater portion of the line of lode by a single company, Pasminco Australia Limited, now permits disparate datasets and observations to be merged and presents new opportunities and encouragement for model refinement and exploration success.

Jan 1, 1993