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By A Hekmat, M Fuentes, F Armijo, R Castro, F Rodriguez

Interpreting the behaviour of granular material and simulating the gravity flow are complex processes in cave mining methods. In this paper, a new Cellular Automata based code – FlowSim – is used as a flexible tool to simulate the gravity flow and subsidence zone in block caving mines. The simulation results of the gravity flow model in a real scaled mine as well as a scaled physical model are presented in this study. In this research, FlowSim was first calibrated at a mine, based on the information obtained from smart markers. These markers were located in five points of the second block of the Esmeralda sector, at the El Teniente copper mine, Codelco, Chile. The calibration was performed with the objective of reducing the discrepancy between the extraction zone defined by markers in the mine and FlowSim outputs. Regarding the mine data, FlowSim was calibrated with the minimum error of ten per cent between real and simulated results. Then, the calibrated FlowSim model was used to simulate the flow behaviour of a scaled physical model. This model was constructed in the Block Caving Laboratory of the University of Chile to scale down the same block of the Esmeralda sector with the scale of 1:200. The FlowSim outputs show that this software enables the simulation of the gravity flow of the scaled model with less than five per cent discrepancy in grade and dilution entry to the drawpoints. According to the obtained results, this paper recommends FlowSim as an appropriate tool which can improve the design of production level in block caving and can enhance the prediction of the subsidence zone and dilution entry.CITATION:Castro, R, Hekmat, A, Fuentes, M, Armijo, F and Rodriguez, F, 2016. FlowSim – a versatile flow simulation tool to quantify extraction and design alternatives for block caving, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 645–652 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

In North-West Nelson the Riwaka Complex, a linear basic intrusive complex, is exposed for approximately 45 km. Some 500 km south, across the Alpine Fault, a linear zone of similar but less well known basic intrusives that may be correlatives of the Riwaka Complex is exposed discontinuously for about 80 km. The Complex was emplaced at several centres along a major tensional fracture zone that developed in upper Carboniferous to Lower Permian time. This fracture zone probably formed in response to the development of a west dipping subduction zone that gave rise to the Permian volcanic arcs in east Nelson and western Southland. The Riwaka Complex contains three rock suites. The Fractionation Suite, characterized by cyclic mineral layering and small scale cumulus banding is the largest and is divided into the Ultramafic, Hornblende and Plagioclase Series, each of which is subdivided into several units. The Cumulus Gabbros represent a restricted but important suite of unusual composition, while the third suite is the late phase Diorite Suite. Except in the lower units of the Ultramafic Series sulfide mineralisation is widespread. Pyrrhotite is the dominant sulfide with lesser chalcopyrite pentlandite and pyrite. Four significant zones of sulfide accumulation are recognised and discussed in some detail. Evidence suggests that the primary magma from which the Riwaka Complex was derived was sulfur deficient. It is concluded that the sulfur content of the Riwaka Complex was derived from assimilation of sulfur rich wall rocks during intrusive processes.

Jan 1, 1980

A fundamental component of grade control at Tarmoola Mine has been the monitoring of assaying through quality assurance programs. The programs have concentrated on issues related to accuracy and precision of leachwell and fire assay techniques, sample preparation and grade variability within a sample. An outcome of monitoring has been identification of shortcomings in the application of assaying techniques to Tarmoola ore types that contain coarse particulate gold. Leachwell has shown satisfactory precision since introduction as the primary assay technique in October 1998 but leachwell accuracy and recovery through comparison with fire assay techniques has identified bias. A bias toward higher fire assays in grades above 2 g/t invoked an investigation into the cause of the discrepancy between leachwell and fire assay. Testwork evaluated Leachwell assay recovery by varying leach time duration, which showed that by increasing the leach time improved recovery significantly. Monitoring of leachwell against fire assay had shown that a leachwell (200 g) with a one hour leach has under-called grade when compared with fire assay by up to 18 per cent, on average, for Tarmoola ore types. Alternatively, optimisation of the leachwell assaying technique using a 200 g pulp and a two hour leach has returned, on average, higher assays than fire assay by up to eight per cent. Testwork on screen fire assays, duplicate assays and fire assay to extinction has demonstrated assay variability associated with coarse, particulate gold. The variability and distribution of gold in Tarmoola ore types has emphasised the importance of high quality sample preparation for leachwell assaying to ensure liberation of gold to leaching solutions. Assay quality assurance protocols are vital to assay data integrity and enable confidence in delineation of ore-waste boundaries and provide early recognition of problematic assaying periods and isolation of grade control practices, which depart from performance standards critical to the operation.

Jan 1, 2000

By V Barrera, A Brzovic, M Gaete, L Burgos, E Arancibia

Fragmentation is one of the most relevant parameters in the design and operation of a mine using the caving mining method. Fragmentation affects all subsequent operations, including extraction, comminution processes, secondary blasting and transportation.There are a number of different models in the literature to estimate the size of the ore fragments that report to the drawpoints; however, there is still no industry consensus about which one to use. This paper proposes a new model for predicting the fragmentation reporting to the drawpoints that is based on the geotechnical unit characteristics, extraction height and column of primary ore. The model is developed from observations of fragmentation measurements in different mine sectors of Codelco’s El Teniente mine in Chile.This work focuses on the following three steps:collecting fragmentation and hang-up data from several mine sectorsdeveloping a geotechnical block model using oriented core placed within the main geotechnical unitsanalysing the data and modelling the fragmentation process.The proposed model is used to discuss the mechanisms and the influence of preconditioning on the size of the ore fragments that report to the drawpoints.CITATION:Brzovic, A, Vallejos, J, Arancibia, E, Burgos, L, Delonca, A, Gaete, M and Barrera, V, 2016. Analysis and modelling of the fragmentation process – case studies at El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 305–310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By S C. Dominy

This contribution examines the effect of feedstock sampling before the sorting stage of polyethylene terephtalate (PET) bottle recycling. Batches of waste PET bottles may contain non-PET bottles which need to be removed by sorting. Any residual presence of PVC is detrimental for the quality of products manufactured from recycled PET. The maximum tolerated concentration of PVC in cleaned PET is extremely low, which places high demands on the recovery of PVC achieved by sorting. To be confident of attaining the desired PET quality after sorting, acceptance sampling of truckloads of PET bottles may take place prior to sorting. It is shown that accounting for sampling uncertainty requires that the sorting process achieves a consistently high recovery of PVC bottles.CITATION:Glass, H J and Dominy, S C, 2017. Plastics recycling and sampling, in Proceedings Eighth World Conference on Sampling and Blending , pp 129–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J M. Parr, P M. Herzig, J B. Gemmell, S D. Scott

PACMANUS is an actively-forming seafloor analogue of volcanic-hosted massive sulfide orebodies, situated on the crest of an andesite-dacite-rhyodacite ridge overlying rifted older arc crust in a back-arc basin. Hydrothermal deposits range from Mn-oxide crusts to Cu-Zn-rich massive sulfide mounds and chimneys containing significant Au and Ag. Preliminary data suggest a substantial magmatic component to fluids and metal sources, and we speculate that PACMANUS is the cap to a complete hydrothermal system including subvolcanic and intrusive-related mineralisation.

Jan 1, 1995

The outlook for suppliers of energy to the expanding economies of the Pacific Basin region is essentially positive, but particularly for exporters of high quality steam coal. This paper argues that economic growth in the Pacific Basin region has exceeded world economic growth for some years and that this will continue to be the case for the next decade at least. It looks briefly at the link between economic growth and energy demand and at the relationship between energy demand and the demand for electricity. Changing preferences in fuel mix for electrical generation in the region are noted and tentative forecasts made about variations in this mix. The pros and cons of various forms of fuel used to generate electricity are considered from the point of view of the consumer. Having concluded that steaming coal in particular is likely to become even more important as a generator of base load electricity, the paper looks at the opportunities this presents for exporters such as Australia, and touches on some factors that could prevent development of those opportunities. This paper will concentrate on electrical energy. For the purposes of this paper, the Pacific Basin refers essentially to Australia, New Zealand and the Asian countries bordering the Western Pacific. As a supplier, Siberia is not included because, although it has great potential, it is thought that problems of climate, infrastructure and political restructuring will delay the realisation of that potential until the next century. Although it deals with the Pacific Basin region, where many countries are industrialising rapidly from a predominantly agricultural base, it looks at the experience of mature industrial DECD economies where their experiences seem relevant.

Jan 1, 1990

By D Craw, L C. Kerr, P Wopereis

Gold placers in the Nokomai and Nevis valleys are dominantly Quaternary in age. They occur mainly in western tributaries of the upper Nevis, eastern tributaries of the middle and upper Nokomai, and in the trunk valleys themselves. Placer gold in both valleys is dominantly a-phase Au-Ag-Hg alloy. Au-Ag alloy is absent or rare in most of the deposits, except in the lower Nokomai. Alpha-Au-Ag-Hg alloy is typically coarse-grained (up to 2 cm), angular, and rarely flattened or folded. Crystalline texture, quartz intergrowths, and psuedo-hexagonal crystal-pluck cavities are common. Fluvial transport distance predicted from the maximum Flatness Index ofAu-Ag-Hg alloy particles is typically less than 10-20 km. Coarse (up to 2 cm) cinnabar is commonly associated with the Au-Ag-Hg alloy, and both were probably derived from hydrothermal sources in western tributaries ofthe upper Nevis and eastern tributaries of the upper Nokomai. Minor secondary Au-Ag-Hg alloy occurs locally in the lower Nokomai, where it coats or cements detrital a-phase Au-Ag-Hg and Au-Ag alloy particles. Au-Ag alloy dominates over Au-Ag-Hg alloy in the lower half of the lower Nokomai alluvial plain and gravel of a raised channel incised into semischist basement adjacent to the plain. The Au-Ag alloy is rounded and commonly flattened and folded. Crystalline texture, quartz intergrowths, and pluck cavities are rare, and a fluvial transport distance of 25-40 km is estimated from maximum Flatness Index ofAu-Ag alloy particles. The Au-Ag alloy, three types of gamet, magnetite, clinozoisite and well foliated schist boulders in the abandoned channel are not found in the pumpellyite-actinolite facies bedrock in the Nokomai. These components were derived from greenschist facies schist and sedimentary sources in Otago, many tens of kilometers north of the Nokomai catchment. They were transported to the Nokomai either in Wakatipu Glacier till or fluvio-glacial outwash that entered the valley via Nokomai Saddle, the confluence with the Mataura, or both.

Jan 1, 2000

Mineral exploration and mining in New Zealand has had almost five years of new legislation. The requirement for different consents is a challenging, time consuming, expensive exercise but in most cases the new procedure is working, although the matter of obtaining access to land is still a major issue. Priority is critical. After lodgment of an application for a minerals permit there are many other matters to address such as identifying land owners, occupiers and administrators, preparation of access applications, consultation and preparation of various resource consent applications.

Jan 1, 1996

By R G. Barker, A B. Christie

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. More than 11 Moz of Au and 50 Moz of Ag have been produced from epithermal deposits in New Zealand, almost entirely from 50 deposits in the Hauraki goldfield. Since the 1980s, new deposits have been discovered at Waihi (Favona, Trio, Correnso) and nearby at Golden Cross. Feasibility studies into reopening the Talisman mine at Karangahake are continuing, and advanced projects with preliminary inferred resource estimates are reported at Wharekirauponga, Neavesville and Muirs. In the Taupo Volcanic Zone, 11 prospects have been drilled, resulting in the definition of large but low-grade Au-Ag resources at Ohakuri. In Northland, several Au, Ag and/or Hg prospects are known, and small quantities of Ag and Hg have been mined. Six prospects have had some drilling, with the most advanced exploration at Puhipuhi. The application of Taupo Volcanic Zone geothermal systems research to the modelling of former hydrothermal mineralising processes in some epithermal prospects has enabled better targeting of exploration.CITATION:Christie, A B and Barker, R G, 2015. Exploration for epithermal gold deposits in New Zealand, in Proceedings PACRIM 2015 Congress, pp 533–540 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Associates

The headwaters of Skippers Creek and the Shotover River are reputed to be among the richest alluvial gold catchments in the world. This alluvial gold has no doubt been derived from reef systems similar to, and associated with, the Bullendale lodes. Physiographically the prospect covers steep ridges and deeply incised gullies between the Richardson Mountains in the west and the Harris Mountains in the east. Vegetation is mainly tussock with bush either side of Murdochs Creek. Access to the area is by metalled road to Skippers and then by 4WD track to Bullendale. Alternatively the prospect area can be reached by helicopter from Queenstown in around ten minutes.

Jan 1, 1992

By N Weerasekara, M Powell, P Toor

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

Sep 7, 2015

Coals from the Southern Coalfield of New South Wales treated in the Port Kembla coal preparation plants of Australian Iron and Steel Pty. Ltd. differ supstantially in their characteristics. Knpwledge of performance not only enables comparison and promotes better control, but also provides the means for predicting results.Evaluation of performance of cleaning equipment has been made in terms of probable error (Ep). Results for Baum jigs, a Chance cone, heavy medium cyclones, and water washing cyclones were examined. The efficiency factors derived from the probable error were applied to the float and sink analysis, mathematically simulating operating conditions. This method was applied to the Balgownie seam.The Balgownie seam lies between the Bulli and Wongawilli seams in the coal measures of the South Coast and mining on a large scale began recently in the Bulli area. It is known locally as the Four Foot seam and exhibits rather difficult washability characteristics, due to a comparatively high middlings content. These properties and the relatively high inherent ash make careful selection of cleaning equipment essential for optimum recovery. The prediction technique is used to determine the possible results when this coal is cleaned in the Port Kembla plants. Predicted values are compared with results from full scale trial washings demonstrating the validity and accuracy of the technique.Applications of result forecasting are listed.

Jan 1, 1971

Copper Recovery from Printed Circuit Board by Carbonisation

Sep 13, 2010

By M J. Bourassa

In addition to the geologic risk of a particular project, the criteria that an international exploration company (æIECÆ) utilises when making an investment decision in a particular country should also include a critical analysis of the political, judicial and fiscal regime of the host country. A key investment criteria of an IEC is mineral tenure and the security and continuity of that mineral tenure under the host countryÆs existing legal system as well as the host countryÆs overall legal, political and fiscal framework, the latter of which can affect the projectÆs overall economic viability in a number of ways. The authors, Steve Vaughan and Michael Bourassa of Aird & Berlis, Toronto, Canada, have taken the position that developing an understanding of a countryÆs legal tradition is a crucial first step in analysing the mineral regulatory regime of a particular country. This paper continues their efforts to overview the most recent legal trends affecting the worldÆs mineral industry and attempts to analyse, categorise, compare and contrast differing legal systems, cultural backgrounds and economic philosophies relating to the development of mineral rights in Pacrim countries and the resulting commercial, legal, and political framework which ultimately drives the relevant mineral legislation. For the convenience of organisation of this analysis, the authors have divided the Pacrim countries into four smaller groups, firstly, on the basis of their legal tradition and, secondly, by their geographic location:Common Law Countries: USA, Canada, Australia and New Zealand; Spanish Civil Code Countries: Mexico, Central America (Panama, Nicaragua, El Salvador, Guatemala), South America (Chile, Peru, Ecuador, Colombia). Communist or Former Communist Countries: Mongolia, China, Russia. Countries of the Pacific Southwest: Phillippines, Indonesia, Malaysia, Indo-China (Vietnam, Laos, Cambodia, Thailand), Papua New Guinea. The discussion starts with an analysis of the various types of legal regimes, attempts to classify or categorise them, reiterates the necessity for the rule of law and those factors which encourage mineral exploration and development and discusses and recommends the expansion of a practical country competitiveness rating system developed by the Fraser Institute. In addition to the fundamental issue of mineral tenure û what it is and how secure it is û the paper discusses how different legal systems have shaped different approaches taken by individual nations to attract foreign mineral investment. The paper analyses the best practices and experiences accumulated in different Pacrim countries with varying legal traditions and identifies a practical country competitiveness rating system which the authors believe should be expanded to cover all minerally endowed countries. This rating system will permit countries to identify their mineral regime weaknesses and adjust their legal systems to better attract mineral investment and will also permit exploration and mining companies to compare their jurisdictional choices with those selected by their competitors.

Jan 1, 1999

Three large deposits of good quality lignite were located and delineated in the Central Otago region between October 1978 and July 1979. The program was initiated and funded by Mines Division of the Ministry of Energy as part of the national Coal Resource Survey. The exploration work was carried out by Lime and Marble Limited on a contract basis (Bowman, 1980). The three deposits were all potentially mineable by open cast methods and possessed combined indicated and, inferred reserves in the order of 1000 x 106 tonnes. They ranked with the previously discovered Eastern Southland 1ignites and as such constituted an important national energy resource. Fifteen months later a second more detailed investigation of similar duration was undertaken by the Liquid Fuels Trust Board (LFTB). The objective was to upgrade and refine the geological data base of all of the nine South Island 1ignite deposits in order to make preliminary economic assessments of their potential. Again Lime and Marble Limited acted as the exploration operator (Bowman, 1981a, 1981b, 1981c).

Jan 1, 1983

The Golden Cross mine is a Joint Venture between Coeur Gold New Zealand Limited, as Manager, and Viking Mining Limited. The mine is targeting Zero Lost Time Accidents as a goal.   The Golden Cross operation produces gold and silver from both underground and open pit. The mine is based on an epithermal gold-silver deposit. Treatment of ore is on a campaign basis for each ore type (i.e. underground or open pit). Milling is conventional SAG Mill and Ball Mill grinding circuit followed by carbon in pulp recovery of gold and silver. All tailing materials are treated through the Cyanisorb process to reduce cyanide levels prior to being discharged into the tailings dam.

Jan 1, 1995

A variety of cement raw materials occur within the Cenozoic sequence in Northland. These form the basis of Golden Bay Cement's cement manufacturing operation at Portland, Whangarei. High grade limestone is taken from the Whangarei Limestone formation, which has been shown to have been sub-aerially weathered and developed mature karst features prior to deposition of the overlying allochthon sediments. In this instance, remobilisation of allochthon sediments following uplift and erosion is inferred. At Portland Quarry, argillaceous limestone is extracted from deformed thrust sheets in the allochthon sequence. Quarry operations have been designed to handle the steep asymmetric folds, thrust faults and fracture zones that affect the resource.

Jan 1, 1999

By R Hall

Subduction zone magmatism is a direct response to tectonic and chemical processes operating at convergent margins. Changes in the tectonic configuration of plate boundaries in SE Asia during the Cenozoic had consequences for the nature and volume of magma produced. Retreat or advance of the trench hinge has probably been an important process in controlling the presence or absence of magmatism in SE Asian subduction zones. This process also provides a means of replenishing the mantle wedge and counteracting the effects of melt extraction in depleting the wedge. Changes in the nature of recycled material and lithologies of the over-riding plate also have the potential to influence the lavas that are erupted in arcs. Several locations in SE Asia have experienced magmatism bearing the geochemical signature of subduction but are remote from coeval subduction zones. Such magmatism requires an earlier period of mantle enrichment by subduction but may result from localised extension. The distribution of such magmatism may provide information of tectonic value. Some adakitic magmatism occurred in tectonic settings where there is no evidence for subduction of young oceanic crust at the time of magma genesis. Slab melting in such settings is not possible and alternative mechanisms are required to explain the occurrence of, at least some, adakitic lavas.

Jan 1, 1999

Particle Mechanics and the Design of Cyclone Tribochargers Triboelectric separation is a dry electrostatic technique that has shown promise in several particle processing applications. A tribocharger uses contact or friction to differentially charge particles of different materials, which are then separated by an electric field. The initial tribocharging process is poorly understood, with tribocharger design and operation largely a matter of trial and error. A better physical understanding of tribocharger operation would therefore be of immense value in the optimisation of triboelectric separation processes. A combination of charge measurements, trajectory modelling and high-speed video has been used to relate charging to particle mechanics in a cylindrical pneumatic cyclone, one of the most effective tribochargers for mineral separation applications, and the preliminary results are presented here. The consequences of these observations for cyclone tribocharger design and operation, and for tribocharger design in general, are discussed.  

Sep 13, 2010