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By I Clark, S C. Dominy

Bulk sampling programs are typically applied in coarse gold mineralised systems to verify resource/reserve grades. In recent years, there have been controversies surrounding some results of underground bulk sampling exercises compared to the predictions using diamond drill data. Just how realistic is it to predict 100 t lots from drilling that was designed to model blocks of several thousand tonnes? This study looks at the variation of relatively small units within larger planned mining units and compares some of the geostatistical techniques which purport to provide tools for such studies. Relative difficulty of application, computer timings and summaries of results will be used to illustrate the likely variation in bulk sampling units as opposed to mining units and large-scale planning units. A case study based on publicly available data from a gold project in North America is presented. A simplistic and unconditional geostatistical simulation model demonstrated that up to 50 per cent of a relatively high-grade mining block could show as uneconomic low-grade subblocks. A subsequent study will consider a similar demonstration using uniform conditioning. Erroneous impressions of early sampling results can lead to unsupported prejudgements of the final results. Bulk sampling programs require detailed planning based on ore characteristics, where protocols must fit the mineralisation type. Any program requires definition of aims and data quality objectives across grade, geological, geotechnical and geometallurgical parameters.CITATION:Clark, I and Dominy, S C, 2017. Underground bulk sampling, uniform conditioning and conditional simulation – unrealistic expectations?, in Proceedings Eighth World Conference on Sampling and Blending , pp 3–20 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Twemlow GL

The accounting profession in Australia and overseas has taken up the responsibility of setting standards specifically relating to the minerals and energy industries. Australia led the way with AAS7 Accounting for the Extractive Industries. This statement was issued in 1976 and amended 1977..It largely deals with accounting for preproduction expenditure and uses the term "economically recoverable reserves". It does not require disclosure of reserve quantities or values in balance sheets or as supplementary information in financial statements. The United States accounting profession in 1982 finally resolved an accounting standard in the same area as AAS7-SFAS69 Disclosures About Oil and Gas Producing Activities. It applies only to oil and gas producers, but has extensive disclosure requirements, including proved oil and gas reserve quantities. Current developments indicate that Great Britain is about to follow the US example. At this time in Australia, AAS7 or some other statement relating to the extractive industries has not been issued as an approved accounting standard by the ASRB. Standards issued by the ASRB are binding in law.

Jan 1, 1987

ThePike River coal field is located between 700 and 1000 m above sea level on the West Coast of the South Island. The area contains a resource of some 60 million tonnes of coal in a single coal seam and is part of the Paparoa mountain range that receives between 6.0 and 6.5 m of rainfall per annum. The area has been isolated and has received no on the coal plateau but has been extensively logged in the lower 3.5 km of Pike Stream. The PRCC development proposal recognises this and calls for an environmentally benign development that includes underground development of this resource. The coalfield abuts and is partly overlain by the Paparoa National Park. The underground development will enable a number of environmental goals to be readily achieved: it will be out of sight of the public,it will not impact the national park,noise will be mostly absent,there will be absolute minimal disturbance to the land surface,coal will be transported from the mine to a dewatering complex on PRCC land in a slurry pipeline thus obviating the need for trucks and noise in Pike Stream valley,all water draining from the mine will be collected, treated if required to consent standards and discharged from a single point,the road into the area will allow for an effective predator control programme to be undertaken enhancing native bird life,an environment suitable for the reintroduction of Whio (Blue Duck) will be created, andthe net effect of the mine development on the environment will be positive.

Jan 1, 2003

By Rao P. K, Sahoo P. K

The main constituents of ferromanganese slags are silicates of Mn, Ca and AI. Factors affecting the recovery of manganese from a low manganese content ferromanganese slag (about 16 per cent MnO) during acid leaching were studied. These included time, temperature, agitation, sulphuric acid addition, solid:liquid ratio and particle size. Agitation rates greater than 300 rev/min. leaching periods greater than 30 min and temperatures above ambient were found to have no effect on Mn recovery. Dissolution of Mn was found to be highly dependent on the amount of acid added.About 90 per cent of the Mn was recovered when 5·5 times the stoichiometric amount of acid was used. About 28 per cent of the Mn was recovered when the stoichiometric quantity of acid (with respect to Mn alone) was used. However, the recovery increased to about 75 per cent when the total stoichiometric requirement of acid with respect to Ca, Al, Mg and Fe as well as Mn was used for leaching. The extent of Mn dissolution also depended on the particle size of the slag. The percentage of Mn recovery (using 5·5 times the stoichiometric amount of acid) increased from about 60 per cent to about 92 per cent when particle size decreased from -36 +52 to -150 +200 mesh (B.S.S.). When the results of this study were compared with those in a previous study involv,ing the leaching of a high manganese content slag (containing about 40 per cent MnO) results were similar except that there was a gr-eater consumption of acid in the present case (i.e. low manganese content slag).

Jan 1, 1979

By Q Johnston

Since its inception in 1990, improved metallurgical processing technologies, coupled with mine planning enhancements and improved geological knowledge, have sequentially enabled better efficiencies and economies of scale at the Macraes Gold Project. Over a period of 11 years, processing enhancements have been achieved by: +        increasing mill throughput, from one million tonnes per year, to current throughput of 3.9 million tonnes per year; +        improving recovery rates, from 70 % to approx 84 %; and +        performance enhancement through innovation, eg the use of kerosene to combat ClL pregrobbing. Future processing improvements have been identified in optimising the ore feed and processing flowsheet. The introduction of the autoclave has transformed the process flow form a traditional 'mill headgrade and tonnes milled' operation, to a 'sulphur/gold ratio and sulphur tonnes oxidised' operation.

Jan 1, 2001

By R Cowen

Past successes of low impact mineral exploration and rehabilitation of mined areas in developed land of subdued contour provide little guidance for similar activity in more sensitive high country or mountain environments. Land management agencies and environmental pressure groups have expressed considerable concern about mineral development in these areas by land especially where the land involved has high environmental or productive values. Mineral explorers are responding with detailed proposals for integration of environmental assessment and mineral exploration at an early stage. A model programme for Fiordland National Park presented in this paper illustrates this approach.

Jan 1, 1981

By T D. H McGrath, W P. Staunton

Benchmarking, comparing an operation or process with the industry standard, is known to be a useful method for identifying plant optimisation opportunities, and in many cases providing the pathway to realise the benefits. The difficulty is generating the database of plant data necessary for a benchmarking exercise. Larger companies can benchmark internally; this option is not available to smaller companies, and the full value can only be realised with a comprehensive “industry wide” approach.The Gold Technology Group at Curtin University through the AMIRA P420 series of projects has undertaken several comprehensive metallurgical industry surveys in the gold industry over the last two decades. Analysis of these surveys has demonstrated areas where many operations can benefit from re-assessment of their operating practices.This paper will review the work undertaken by the Group in this area, in particular the 1999 surveys of gold companies in the Australasian region, and the 2012 international survey of the industry. The challenges of, and opportunities arising from these surveys will be discussed. Some of the highlights from analysis of these databases will be presented as well as noting changes in processing practices observed by the Group over the last 20 years.CITATION:McGrath, T D H and Staunton, W P, 2018. Keeping up with the Joneses – the value of industry surveys and benchmarking, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 509–516 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

The Central Andes in Peru, Chile, Bolivia, and Argentina , contain two contiguous terranes which were accreted to Gondwanaland between the end of the Devonian and the end of the Triassic. These terranes, Arequipa in the north, and Chilenia in the south, differ from each other in the timing and style of their metallogenic development. However, they contain over 90% of the Central Andean porphyry copper resource. The copper porphyries in the Arequipa terrane are Paleocene to lower Oligocene in age, whereas the Chilenia deposits are mid-upper Cretaceous and mid-upper Miocene. Porphyry copper deposits occur outside these terranes, but are all Miocene in age. Miocene porphyry-style mineralisation also exists in the Arequipa terrane, but is copper-deficient and gold-rich. The accreted terranes may have favoured porphyry and other styles of copper mineralisation because they possessed relatively thin continental crust compared to adjacent parts of the Andes. Crustal thickening which commenced at about 30 Ma in the Arequipa terrane coincided with a major change to polymetallic, precious metal mineralisation which commonly displays high sulfidation characteristics.

Jan 1, 1995

This paper describes the excavation of No. 1 Power Station Lift Shaft at the Kiewa Hydro-Electric Project. The advantages and limitations of the borehole method are outlined, and general principles of plant design are discussed.INTRODUCTIONFor many years, attempts have been made to reduce mine development costs by various methods. Some of the, techniques of tunnelling have been adopted in horizontal headings, and in main vertical shafts, mechanical plant has displaced hand labour with notable success. However, in the field of small rises and winzes, improvements have largely been effected by attention to details of procedure. The most promising avenues for' substantial reductions in cost relate to:(a) Long-hole drilling(b) The borehole method(c) Calyx drilling.Whilst each of these methods has its peculiar advantages, the borehole rising method is probably most useful, and capable of wide application.In brief, the borehole method of rising requires a, drill hole parallel to the axis of the rise. A hoisting rope is passed through the borehole, and is attached to a platform on which the rising crew are raised with their equipment to the drilling position in the rise.When properly planned, the method is particularly safe, and has generally received the approval of mine inspectors and safety authorities. Rising work is generally hazardous, even when special timbering methods are used. In...

Jan 1, 1959

The paper describes a simulating method.for ground water contamination originating from industrial and mining activrty. The finite difference model simulates heat, mass and solute transport. The applied stochastical method for dispersion provides more accurate solution of mass transport modelling. This method gives a more realistic approach of chemical processes in an aquifer depending on temperature.

Jan 1, 1988

By Baafi EY, MacKenzie -Wood P

An experienced and reliable knowledge of fire fighting procedures is necessary for mine emergency situations. Since experts in this area are scarce the technology of expert systems lends itself as a suitable component in the decision making process. This paper describes an expert system that is being developed for this purpose. The expert system. RESCUE. is a knowledge-based computer programme which incorporates the judgement, experience, rules of thumb. mine environmental conditions as well as human intuitions in the mine rescue operation. RESCUE makes decisions such as whether or not the affected area should be sealed.' whether or not rescuemen should be withdrawn, and which fire fighting agent is most appropriate for the situation. The IF..... THEN rules written in the VP-EXPERT shell contains antecedents and conclusions based on environmental as well as other conditions prevailing in the mine. For example, the CO/Oz deficiency ratio indicates the progress of heating; explosibility trends are given by varying flammable gases C CH4,H2,CO) in relation to oxygen concentration, and barometric pressure falls may affect explosibility by increasing CH4 content in workings. The interaction of such numeric-based rules with others rules reflecting the experience and judgement of the experts assist the system to arrive at its conclusions and subsequent course of action.

Jan 1, 1988

By B J. Hutchison, S Gannon, J Chambers, D Oko-oboh

The Kanmantoo copper mine is located in the Adelaide Hills area of South Australia and is owned and operated by Hillgrove Resources (HGO). The mine is a drill and blast, truck and shovel operation mining sulfide (chalcopyrite) ore located in chloritised andalusite biotite schist. The initial Kanmantoo open pit operation occurred in the 1970s, before falling copper prices closed the mine. In 2010 the mine was reopened by HGO and the Kavanagh cutback of the Kanmantoo pit was undertaken. The Spitfire, Nugent and Emily Star satellite pits were also mined through to 2015 before the latest steep wall Giant pit design was developed to take mining out to 2019.There are no major fault structures and only two significant shear zone structures exposed in the open pit walls. The main Garnet Andalusite Biotite Schist (GABS) unit is quite competent so the pit designs have therefore mainly been controlled by four distinct joint sets. This paper is a case study on the influence of the joint regime on the wall stability of the main GABS unit and how a better understanding of the joint regime and the use of rock reinforcement has allowed the steep wall design to be adopted.The paper also describes the remote geotechnical mapping and slope monitoring techniques used to manage the rockfall risks associated with the steep walled slope design.CITATION:Hutchison, B J, Chambers, J, Gannon, S and Oko-oboh, D, 2017. Case study of joint structure and the design and performance of open pit walls at the Kanmantoo copper mine, in Proceedings Tenth International Mining Geology Conference 2017, pp 355–364 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By D T. Feinstein, M B. Gotkowitz

In Wisconsin, state laws and regulations governing metallic mine permitting stipulate that protection of groundwater quality be assured indefinitely through all phases of the mining project, including development, active mining, reclamation, and long-term closure. By rule, the Wisconsin Department of Natural Resources (WDNR) requires that permit applicants use a numerical model to assist in the assessment of compliance with this requirement for all proposed mine-waste facilities. As a part of the compliance assessment, model calculations are used to predict groundwater solute concentrations through time at designated boundaries for comparison to current groundwater quality standards. In practice, this modelling requirement has involved the application of numerical solute-transport models. Our review of a solute-transport model submitted by the developers of a proposed mine near Crandon, Wisconsin, provides us with an opportunity to assess the usefulness of transport modelling as a permitting requirement. Recent evaluations of solute-transport models by other workers suggest limitations in predictive accuracy. Our review of the model submitted for this project also identified important limitations due primarily to uncertainty in calibration of model parameters at the undeveloped site. The utility of any model to predict project compliance or non-compliance with numerical standards is limited by the range of uncertainty of key model parameters, such as dispersivity and porosity. Uncertainty in the future behaviour of the solute source(s) also reduces the predictive power. Moreover, the site characterisation provided by the model may have limited power to describe the site condition post-development. Although these inherent shortcomings accompany the use of solute transport models at undeveloped sites, the requirement for model development and the ensuing technical review has substantially assisted in our evaluation of site conditions and project design. Through this process we have identified elements of the waste facility design that are crucial to the environmental viability of the project, resulting in modifications to original project proposals. While results from this model review will be used to evaluate compliance, additional benefits come from the identification of critical design features that enhance groundwater protection.

Jan 1, 2003

By A Tsoy

This abstract describes long-term mining schedule optimisation approach that may be suitable for complex marginal projects and is based on modern scheduling techniques. CITATION: Tsoy, A, 2018. Strategic mine schedule optimisation, in Proceedings Complex Orebodies Conference 2018, pp 91–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

THE ore treated is almost pure copper pyrites (chalcopyrite) in a gangue of quartz and quartz-felsite. Very little free iron sulphide (pyrite) occurs, and at the time of the erection of the flotation plant the stopes in the oxidized zone had been almostentirely depleted. This zone only extends to a shallow depth, and, below the l00-ft. level, the sulphide for the most part is clean and bright but in the crushed and brecciated parts of the ore channel, where surface water has circulated freely, the gangue is decomposed and kaolinized, and the copper sulphide badly tarnished. This class of ore gave considerable trouble at the mill, but unfortunately, was very limited in quantity. A sample of rich ore assayed-Copper, 21.2 %; iron, 24:.3 %; silica, 28.9 %; sulphur, 25.1%.The concentration in the original mill was effected by handpicking, jigging, and tabling. A considerable portion of the copper mineral arrives at the surface in the form of large lumps of very pure quality, eminently suitable for sorting out by hand.The rich ore is tipped over a grizzly at the shaft bins; the oversize hand-picked, and the undersize bagged direct.

Jan 1, 1912

In the 1890s, The Goldfields Water Supply Department in Western Australia commissioned the diamond drilling of two deep artesian exploratory water bores near Coolgardie (Blatchford, 1899). At the time, in spite of strongly-worded advice to the contrary from the Government geologists, there was a wide popular belief that you could obtain artesian groundwater virtually anywhere providing you drilled deep enough. The first Coolgardie hole was drilled to over 900 m, despite the fact that the bore penetrated granite from a depth of 5 m below the surface. Drilling proceeded for more than 16 months, between July 1896 and November 1897. A small quantity of salt water was struck at a depth of 36 m. The second bore was mercifully terminated at a depth of 50 m, also in granite, with again only a small inflow of salt water. Such were the desperate lengths that were pursued to obtain a reliable water supply for the influx of people in the Eastern Goldfields gold rush. The WA Goldfields continued to rely on huge condensers for water supply until that great engineering feat, the construction of a water pipeline from Mundaring Weir to Coolgardie, was completed in 1903. An enormous network of rail tracks penetrated outwards from Kalgoorlie and Coolgardie for the collection of timber, principally to feed the condensers. Remnants of the rail network are still visible today. The acute shortage of fresh water led to great deprivation, disease and death among the early miners. Today, the water problems faced by the mining industry are thankfully not as severe, but they are nevertheless no less challenging. The southern part of the WA Goldfields is a notoriously difficult area for finding potable quality groundwater. Even as recently as the 1990s, there were occasional serious efforts to find potable groundwater in that area, some very imaginative and innovative. One mining company, working south of Southern Cross, spent many months experimenting with recovery of potable quality water from a shallow freshwater lens overlying hypersaline water in a low permeability weathered granite aquifer. They used very low capacity pumps manufactured from car windscreen washer pumps powered by solar panels.

Jan 1, 2000

THE furnace described in this paper was installed and has been used by the writer for the melting of rich gold-bearing material, and has given complete satisfaction. It may, therefore, prove of interest to other metallurgists who are faced with a similarproblem. A furnace of this type should be most suitable for the reduction of "cyanide preeipitate," "charcoal ash," "anode sludge," &c. formerly the melting was done in fire-clay crucibles, using coke or crude oil as fuel, but this method is costly, slow, and unsatisfactory. A small water-jacketed blastfurnace was also tried on this material after briquetting it, but was discarded in favour of the electric furnace. The furnace may be described as a simple form of the Heroult resistance furnace, with an adjustable upper electrode and a fixed bottom electrode. This is in accordanee with Stansfield's classification of electric furnaces. The heating is mostly due to the resistance offered the current by the molten slag. The melting chamber consists of a steel drum 14 in. in diameter and 21 in. high, and is lined with silica bricks specially made to fit the shell. The internal diameter is G in. The bricks contain 92 % silica, are made from calcined quartzite bonded with fireclay, and are similar in composition to those used for lining steel converters. They are set in a mixture of finely-ground quartzite and clay, and well dried out. The shell is bolted to a steel plate, which forms the decking of a truck running on rails, so that the furnace can be moved under ahood for carrying off the fumes. A cast-iron slag spout is bolted to the shell below the tapping hole, which is 4 in. from the bottom of the shell. Opposite this another hole 1 in. in diameter is drilled through the shell and lining for the passage of the lower...

Jan 1, 1918

By H R. Pein

"The Corridor Sands deposit is situated approximately 190 km north east of Maputo, Mozambique adjacent to the paleo-mouth of the Limpopo River. This deposit is one of the worldÆs largest known economically viable resource of titanium, accounting for approximately one third of the global resource. As part of the pre-feasibility and feasibility study for development of the Corridor Sands project, various geological and geotechnical investigations were undertaken, selected results of which are presented in this paper. These investigations have enabled a detailed understanding of the material characteristics of the orebody as well as the tailings materials, such as the fines, to be developed. These material characteristics have had a significant impact on the selection of the mining and disposal methods currently being implemented."

Jan 1, 2001

By B Clemen, D Gordon, F Cesnik, P Griffin

In March 2002 Newcrest Mining Ltd commissioned a 4 Mtpa gold-copper concentrator at its Cadia Valley Operations in New South Wales. This paper presents the design and construction considerations, commissioning and ramp up issues related to start up of the concentrator as well as current performance and future expansion plans. Commissioning of the plant was the culmination of six years of project planning, from discovery of the resource during the Cadia Hill drill out campaign in November 1996 to project implementation and plant operation. Current resource estimates stand at around 50 Mt with an average grade of 2.4 g/t gold and 0.8 per cent copper. At current processing rates the project life is expected to exceed ten years. The processing plant comprises a 9.75 m (32 ft) diameter Fully Autogenous (AG) mill, a single 6.7 m (22 ft) diameter ball mill, pebble crushers, gravity gold recovery circuit and flotation plant. Upgrades to the existing infrastructure and manning requirements at Cadia will be discussed as well as the resultant impacts on operating costs for the operation. The processing plant was expected to deliver 290 000 ounces of gold and 30 000 tonnes of copper in concentrate in its first full year of operation and progress against that goal will be presented.

Jan 1, 2003

By X Liu

The crystal chemistry of carbonate in Ca apatites, including Na-free and Na-bearing hydroxylapatite (CHAP) and Na-bearing fluorapatite (CFAP) and chlorapatite (CCLAP), has been investigated by Fourier transform infrared (FTIR) spectroscopy and single-crystal X-ray structure, using crystals synthesised from carbonate-rich melts at 1 GPa, 1400 - 1000¦C. The carbonate ion substitutes for both the X (OH, F, Cl) anion species in the apatite channel (type A carbonate) and the phosphate group (type B carbonate). The type A carbonate ion is oriented in the channel with two oxygen atoms close to the c-axis, and the type B carbonate ion is located close to the sloping faces of the substituted phosphate tetrahedron, with details varying with composition series. Sodium promotes the uptake of type B carbonate and also has a profound effect on FTIR spectra. Crystal compositions correspond approximately to the substitution formula Ca10-(y+z)Nay z[(PO4)6-(y+2z)(CO3)y+2z][X2-2x(CO3)x], with x + y up to 1.0 and z + 0.0 for CHAP, x + y + 4z + 0.4 for CCLAP, and x + y + 2z + 0.1 for CFAP, for equivalent conditions of synthesis. The sodium cation and A and B carbonate ion defects are locally coupled in all three composition series to facilitate charge compensation and minimise the effects of spatial accommodation. Synthetic Na-bearing type A-B CHAP with x + y + 0.5 has a similar chemical composition and FTIR spectrum to biological apatite.

Jan 1, 2008