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Bacteria can play a key role in the processing of 'difficult' ores. Bioleaching opens the way to potentially extract copper from vast amounts of otherwise hard to process refractory low-grade chalcopyrite. In my talk I will outline our research philosophy to develop bioleaching as a Precision Processing unit process step. In our view, Precision Processing is a sophisticated approach to mineral processing where the ultimate goal is to measure and characterise the ore body in-ground and in real time during mining, allowing the down-stream unit processes (bioleaching, in this case) to be continuously tailored and tuned via feedback and feed-forward controls to obtain the highest possible recoveries at the lowest possible cost and environmental impact. I will describe some of the work that we are undertaking to better understand the interfacial phenomena underlying the fundamental bioleaching process with the aim of coming to a Precision Processing approach. We use techniques such as interfacial electrochemistry (scanning electrochemical microscopy, SECM), AFM, zeta potential measurement, and synchrotron science to elucidate the parameters that drive bacterial selectivity and adhesion, bacterial metabolism, and dissolution and precipitation processes for model systems and real chalcopyrite ores. As examples of our research, I will discuss in some detail our method to produce and characterise micro-patterned CuxS - silica thin films as model substrates for electrochemical and bacterial adhesion work and our approach to the interfacial chemical characterisation of extracellular polymeric substances of bio-active bacterial cells. I will also cover some of our recent findings relating to measurement and interpretation of bacterial adhesion on sulfidic substrates and its implications for bacterial adhesion and substrate selectivity. After having identified and discussed crucial leaching parameters, such as pH, Eh, T, [Cu2+], and [O2], the talk will go on addressing some of the early achievements and challenges encountered in our work to design and prepare low-cost, rugged sensing devices that allow the in-situ (in this case, in-dump or in-heap) localised measurement of these parameters. I will conclude my talk by painting the picture of how the work of our group might contribute to realising the dream of transforming bioleaching into genuine high-tech Precision Processing of minerals. This is an ABSTRACT ONLY. A full-length paper was not prepared for this presentation.

Sep 13, 2010

Bendigo Mining operates a 600 000 t/a comminution, gravity, flotation and leaching processing plant for the recovery of gold from their Kangaroo Flat Operation, in the Bendigo goldfields. The free gold and gold bearing sulfi des present are typically coarse grained and hence are highly amenable to gravity recovery. Plant operating data is consistently showing that over 78 per cent of the feed gold is recovered in a circuit, consisting of inline pressure jigs, inline spinners followed by free gold tabling and intensive leaching of tabling tails. The circuit receives coarse crushed product from high pressure grinding rolls and the grinding mill discharge, which allows material to be re-circulated through the gravity process until the particles are small enough to enter the flotation circuit. A plant audit was completed on 26 November 2009 designed to give an indication of the overall operational characteristics of the gravity circuit including single pass efficiencies of associated equipment. The techniques, results and challenges of such a survey are discussed.

Aug 1, 2010

By D Thomas

Geochemical data related to AMD for the West Coast and Southland regions have been collated into a relational database and GIS system. The types of information include; rock geochemical data, water chemistry data and aquatic macro-invertebrate abundance data. This information will be combined with eco-toxicology experiments to determine impact thresholds on aquatic ecosystems. Ultimately these datasets will be combined with remediation investigations to produce a Framework to assist decision making related to mine planning, consent and compliance.   Current geochemical research examines the controls on As concentrations downstream of gold mining areas and the variability of AMD from Brunner Coal Measure rocks. Assessment of factors that control the chemistry of Brunner Coal Measure AMD such as mine type, hydrogeology, geology, geochemistry and climate is in progress. Minerals that control the concentration of aluminium downstream of AMD point sources include alunite, jurbanite and various forms of Al(OH)3.

Jan 1, 2005

By R J. Goldfarb, A B. Christie, D I. Groves

Small orogenic gold deposits have the same deposit-scale geological and geochemical features as those that characterise giant orogenic gold systems (>16 Moz Au). Therefore, a broader-scale approach is needed to identify the critical controls on giant deposits and their disproportionate distribution throughout time and space. Ages of giant gold systems cluster around well-defined periods of lithospheric growth at continental margins, and it is orogen-scale processes during these Late Archaean, Early Proterozoic and Phanerozoic times that determine gold endowment of a province.   A critical factor for giant orogenic gold provinces appears to be asthenospheric upwelling at the time of gold mineralisation to most effectively transfer the thermal energy required to initiate and sustain high hydrothermal fluid flux. The extent of this fluid flux should be related to thickness of the lithosphere beneath a province at the time of gold mineralisation, such that giant gold deposits are much more likely to develop in orogens with oceanic or thinned continental lithosphere. A proxy for the latter is likely to be a short premineralisation crustal history such that thick subcontinental lithospheric mantle was not developed. Conversely, orogens with protracted premineralisation crustal histories are more likely to have a thick subcontinental lithospheric mantle, which is difficult to delaminate and, hence, such provinces will normally be poorly endowed. The nature of the lithosphere also influences the intrinsic gold concentrations of potential source rocks, with back-arc basalts, transitional basalts and basanites enriched in gold relative to other rock sequences. Thus, segments of orogens with thin lithosphere may be defined by conjunction of giant-scale fluid flux through gold-enriched sequences.   Although the nature of the lithosphere plays the crucial role in dictating which orogenic gold provinces will contain one or more giant deposits, the precise siting of those giants depends on the critical conjunction of a number of province-scale factors that control fluid conduits, traps, and seals in tectonically and lithospherically suitable terranes within accretionary orogens.

Jan 1, 2005

By Adams R. W

A commercial scale strong acid leaching plant was commissioned at the Risdon plant of the Electrolytic Zinc Company of Australasia Limited, a member of the Pasminco group of companies, in February 1988. It was designed to upgrade the lead/silver residue product from 26% to 37% lead, thus improving the realised value and increasing overall zinc recovery. This in turn enables the lead smelter treating the lead residue to improve its productivity. The equipment consists of two 250m3 bricklined leach tanks and two 6.5m diameter stainless steel high rate thickeners operating with counter current washing at 95¦C and 120 g/L H2SO4. The present filtration and drying equipment is also being replaced. Two 35m2 squeeze action filter presses equipped with horizontal plates are being installed, together with ancillary drying equipment to ensure that the final product complies with the transportable moisture limit. The new filtration plant is due to be commissioned in mid-1989.

Jan 1, 1989

By Ibil S

The Gameta Gold Deposit is located on the north-eastern corner of Fergusson Island in the D'Entrecasteaux Islands of Milne Bay Province, PNG, at lat. 9¦ 25' 5, long. 150¦ 47' E or AMG co- ordinate 256740 E/8959000 N (Figure 1). The area is covered by the Fergusson (SC56-05) 1:250,000 scale Topographic Map Sheet and the Koitabu (9079)1:100,000 scale Topographic Map Sheet. The property is held 100% by Union Mining NL (UMG) and lies 105 km NNE of Alotau and 33 km to the ESE of UMGs recently developed Wapolu Gold Mine, a Joint Venture between UMO (51%) and Macmin NL (49%). The inferred resource estimated from surface results and 105 RC drill holes, currently stands at 1.89 million tonnes at 2.6 git gold (1.0 g/t Au cut-off) or 155,000 oz. Evaluation of the property is currently proceeding. To date 111 RC holes have been drilled for a total of 4611 m.

Jan 1, 1997

By J Morton

The Resource Management Act 1991 represented an innovative and unique piece of planning and environmental legislation when it was introduced. Since the Act was passed into law in 1991 it has been subject to nine amendments, many of which were of the ætinkerÆ variety. These amendments recognise that the Act has not been as successful in providing the æone-stop shopÆ for resource users that the Act was hoped to be. The latest and most significant attempt at changing the Act was the Resource Management Amendment Act 2003. The amendments made by the Amendment Act have proved to be largely unsuccessful in achieving any significant changes to the way resources are managed in New Zealand, and have failed to address many of the concerns which drove the original Resource Management Amendment Bill in 1999. The recent decision to discontinue further investment in Project Aqua has once again placed the Act in the spotlight as a significant hand-brake on major projects. This particular event has led to yet another review to be undertaken this year. The review will focus on five key areas:   1.   achieving the right balance of national and local interests; 2.   improving the design and process for local policy formulation; 3.   improving the consent decision making process; 4.   allocation of natural resources (water, air and geothermal); and 5.   supporting measures for building capacity and promoting best practice and implementation at the local authority level.  It is important for the business community and the mining industry in particular to seize the opportunity that this review provides to make sure that any amendments undertaken as a result of the review achieve the aims listed above. The review needs to be considered in light of the current regime for the management of natural resources in New Zealand. In addition to the Resource Management Act 1991, the Crown Minerals Act 1991 and the Building Act 1991, which form the core resource statutes in New Zealand, there have been other developments affecting the regime. Special legislation over and above the Resource Management Act 1991 has been enacted to protect the Hauraki Gulf and special legislation is currently being considered to protect the Waitakere Ranges in Auckland. In the Hauraki District mining is prohibited in some areas and a plan change mechanism is specified as the appropriate tool to use in the event a mineral resource is to be developed in those areas. The current review is a further opportunity to remedy the inadequacies of the Act.

Jan 1, 2004

Both here and in Australia, the unique commercial and tax features of joint venture are finding favour in forestry, fishing, technology and infrastructure projects. For New Zealand mining companies, joint ventures provide a means of access to foreign know how and investment funds, while retaining their corporate independence and their hard-earned tax losses.   This paper discusses some of the practical income tax and GST considerations where a joint venture structure is contemplated. The first part of the paper considers income tax, and in particular how joint ventures enable companies to access and carry forward tax losses. It explains why a joint venture may be advantageous relative to a jointly owned company.   The second part of the paper concerns GST and the focus is on two aspects: 1.   Joint ventures may be registered for GST. In some instances they have no choice and are required to do so. Where a joint venture is registered in respect of a taxable activity, the members are not permitted to register in respect of the same activity. This may be problem where the member has incurred its own expenses and the member wishes to register in its own right to claim back the GST on those expenses. This paper explores the issue and possible solutions. 2.   It is not uncommon to see joint ventures claiming GST on the costs of production, and the production being sold (and GST is being charged) by the members. In this paper we consider whether these arrangements have a tax risk, and what can be done to make them technically sound.

Jan 1, 2005

One of the major changes in the resource industry in the nineties has been the re- internationalisation of the industry. The history of the resource business has been one of companies from the developed world utilising the cash flows from their operations to explore and develop mines in less developed regions of the world. This resource development has progressively generated wealth and economic development, which in tum, has led to a new generation of exploration and mining projects.   InSouth America, Chile had led the way in a mining resurgence, now closely followed by Argentina, Brazil, Venezuela and Peru. Although Chile has long had a significant copper mining industry, the pre-nationalisation phase was driven by American capital; the current phase has been spearheaded by RTZ - BHP at Escondida with Canadian junior companies, in particular, providing major speculative impetus. The Australian junior companies have not been significant in South America.   Although Canadian and USA exploration appears to be in decline, the mining industry, particularly in gold, is buoyant in North America. Interestingly, a number of listed and unlisted Australian companies are active, particularly in United States exploration.   Australian-based companies have dominated the South-East Asian exploration scene, especially in the Vietnam region. To date, the combination of political and legislative uncertainties have failed to lead to significant resource developments in this region. The area remains one of great potential, as exemplified by the exciting developments in Indonesia.   The Philippines has a history of mining, and this has been dominated by both local and North American operators. Both large and small Australian resource companies have a presence in the Philippines, and the development of the copper-gold potential could be impressive over the next decade.   The tales of the undeveloped mineral potential of China are probably rivalled only by the supposed strings of virgin Russian orebodies! Many Australian companies appear to have looked but few have chosen to proceed with Chinese developments. There seems little likelihood that China will, in the foreseeable future, rival South America as a target for Australian and North American resource capital.   Papua New Guinea has had an active, albeit chequered history in mining, with Australia long being the predominant source of exploration and development funds. The developing nation status of PNG has generated extreme uncertainty, with the current exploration scene all but dead. Most recently, the international flotation of Lihir Gold has tested the international and Australian investment community's commitment to PNG resource development.   The Australian exploration scene continues buoyant, although dominated by gold. The base metals scene is generating, on average, one significant base metal mine developed every couple of years. This is probably the fastest rate of significant base metal development in Australia's history.   The gold scene has been one of incredible dynamics, and there is no evidence that this momentum is waning. The development of new exploration techniques, together with a number of the companies reaching a critical size, has added to the momentum in the industry.

Jan 1, 1995

By Hale Y. M

Multielement reconnaissance geochemistry coupled with ground scintillation gamma ray measurements has been used to investigate the dispersion patterns of uranium and other major and trace elements in the arid Palmyrides region of central Syria. This region occupies an interplatform depression in the northern part of the Arabia Plate, upon which sediments up to 10 km thick have accumulated. Outcrops of strongly fractured Mesozoic and Cenozoic rocks form two major mountain belts, the northern and southern Palmyrides, between which is located the closed Ad-Daww basin, with a thick Neogene and Quaternary clastic cover. Among the various lithologies, phosphorites are well represented. Uranium and associated elements have been incorporated into the Upper Cretaceous and Lower Palaeogene sediments, especially the phosphorites, which are well represented in the region. These elements are derived from three possible sources, namely, sea water, Lower Cretaceous volcanism and metalliferous fluids leaking along taphrogenic lineaments. In and around the phosphorites, numerous traces of secondary uranium mineralization occur. Over 500 geochemical samples of outcropping rock, wadi and playa sediments, overburden and groundwaters were taken over an area of approximately 9000 sq km. Most samples were analyzed for 25 major and trace elements by nebulization ICPAES; for As, Sb, Bi and Se by hydride generation and ICPAES; and for U, Th and La and other REE by neutron activation analysis.

Jan 1, 1988

Technology is playing an increasingly large role in the operations of our mines. There is a temptation to regard the implementation of technological systems as the objective itself when, in reality, systems are used to support a business process. Only when the process succeeds will the systems be seen to succeed. Understanding the distinction between system and process is critical. This understanding, together with the resultant holistic approach, is considered to be critical to successful implementation and operation of Mine Control process. This paper examines the critical factors essential to success in establishing and sustaining a Mine Control process that maximises benefits to an operation. These factors have been developed during the author's experience of nearly 30 years in Mine Control projects across over 50 sites. Each factor is discussed in relation to real world examples at well-known mines.

May 1, 2010

Gold was first discovered on the Shotover by Thomas Arthur in 1862, and soon there were over 3000 miners working on the river. It has often been called the richest river in the world. Most countries probably have one of these, but it was certainly the richest in New Zealand. In the early days some miners collected as much as 200 oz/d from a sluice box, and the early river gravels must have been extremely rich before the gold bearing terrace gravels were sluiced into the river. Otago produced about 10 Moz out of the NZ total of over 30 Moz. Most of this was alluvial and possibly one third or more came from the Shotover. The extremely cold winter and danger of flooding made it a dangerous river to work. During 1863 when heavy rain melted snow in the high country, the river rose 35 ft overnight and drowned many miners camped on the banks. These hazards still exist and dominate the method of working. The early hand miners cleaned out much of the riverbed, and the advent of the hydraulic elevator enabled deeper parts of the river to be worked over. Extensive sluicing of high terraces also took place particularly around Skippers. Several companies have attempted operations on the Shotover. Many of these were distinctly unsuccessful, such as the suction dredge at Maori Point about 1930 and the Skippers Limited fluming in about 1934. At least two attempts were made to divert the river with the Sandhills cut above Skippers and the Oxenbridge Tunnel down near Arthur's Point.

Jan 1, 1983

By S Jahanshahi, D R. Swinbourne

A knowledge of the value of the activity coefficient of cobalt oxide in slag as a function of composition and temperature is necessary if effective strategies are to be devised to maximise the recovery of cobalt in nonferrous smelting processes. This work reviews previous studies and shows that comparison and evaluation of the results is hampered by variations in the choice of standard states for the species. Published results have been recalculated to a common set of standard states with a preferred value for the Gibbs free energy of formation of cobalt oxide. It has been shown that the value of the activity coefficient of cobalt oxide referred to the solid standard state in iron silicate slags is approximately two, at temperatures from 1523 to 1623¦K. It is suggested that some contradictory results are most likely due to errors in the measured partial pressure of oxygen.

Jan 1, 1998

By D Craw, N Newman

Previously published stream quality data and AMD (acid mine drainage) analyses have been collated into a database (DAME û Database for Assessment of Mine Environments) and additional samples including NMD (neutral mine drainage) have been collected from coal mine drainages on the West Coast. Variations in the chemistry of mine drainage samples can be related to four factors: 1.       regional geology (Brunner Coal Measures or Paparoa Coal Measures) 2.       mine type (open cast or underground) 3.       hydrogeology 4.       local geology   In general mines hosted in Paparoa Coal Measures produce NMD whereas mines hosted in Brunner Coal Measures produce AMD with highly variable chemistry. Differences in coal mine drainage chemistry between mines hosted in Brunner and Paparoa Coal Measure sequences can be measured with acid-base accounting geochemistry. Correlation of ANC (acid neutralising capacity) and MPA (maximum potential acidity) analysis of rocks with mine drainage samples is substantially better than correlation of NAG (net acid generation) analysis with mine drainage chemistry.   It is likely that NAG analysis over estimates acid generation potential of some samples due to release of organic acids that are not released under environmental conditions. In general, differences in mine drainage chemistry between Brunner and Paparoa hosted mines are attributed to the effect depositional environment and diagenesis on coal measure composition. Exceptions to generalisations relating mine drainage to Paparoa or Brunner host rocks are likely where local geological conditions cause increased deposition of pyrite in Paparoa rocks and additional analyses are required to confirm interpretations.   Based on the interpretation of these results a mine drainage chemistry hazard model has been constructed. The hazard model predicts likely variations in mine drainage chemistry based on the four factors listed above. The hazard model has implications for mine related water quality risks. For example, ecotoxicity, human health affects and selection of remediation techniques are all sensitive to mine drainage chemistry.

Jan 1, 2006

We are moving into an era where we experience the consequences of the skills crisis û namely many resource models have been generated by inexperienced people under pressure to deliver high quality resource estimates in unsupported environments, often without technical mentors. These resource models form the basis of our decision to pursue actual mining. This begs the question: how valid are the resource models that form the basis of our mining decisions? This paper presents various model validation tools such as comparison of input and output statistics, swath plots, sectional or bench comparisons between drill holes and models as well as a variety of other approaches. Each model validation tool currently used in industry is examined:how the tool generates results,what assumptions exist,what constitutes a pass/fail in the test, and what interpretations to consider when using the validation tool. Each validation toolÆs suitability and the inherent flaws in the underlying assumptions are also discussed. These are supported with examples of good versus bad validations. Our principles based reporting codes provide flexibility in how models are generated and what approaches and/or parameters are used to generate resource estimates. This flexibility works well when used by experienced practitioners. However, our reporting codes assume a level of experience not always available in the current skills crisis. This paper seeks to provide minimum model validation prerequisites for model acceptance and suitability, regardless of the resource analystÆs experience. As we move forward, our immediate challenge is to ensure our baseline resource models are material, transparent and competent.

Jan 1, 2009

Within ten months of the first significant intersection on the Vera deposit, approval was given to proceed with a $28.3 M underground development of the Vera-Nancy gold mine. Contrary to what the timeframe suggests, the development of the underground mine was planned in a logical and methodical manner which enabled confirmation of the resource, evaluation of the orebody for mining and sufficient production to recommence milling operations at the Pajingo treatment plant. This paper describes the underlying factors on which the project was planned and developed. The approach has successfully enabled the mine to be in production 18 months after discovery without compromising any future production or potential expansion

Jan 1, 1998

The offshore Maui gas/condensate field was discovered by Shell BP and Todd on Services Limited in 1969. Subsequent appraisal drilling and negotiations with the Government led to a development agreement, æThe Maui White Paper' being concluded in 1973. Part of this agreement provided for the Government to take a 50 per cent shareholding in the field. The field is comprised of a double domed anticlinal structure containing two gas reservoirs at depths ranging from 2700 - 3000 m. Water depth is 110 m. The development plan called for two standalone steel platforms to be installed sequentially over a period of some years depending on gas demand. The first platform (MPA) was put in place in 1976 but difficulties were experienced with piling and drilling of the 12 (later increased to 14) wells did not start until 1978. First gas was piped ashore late in 1979.

Jan 1, 1994

By R Riquelme

The El Salvador porphyry Cu deposit (26¦ 15Æ Lat S, ~2700 masl) and associated exotic mineralisation is situated at the back-scarp of the late middle Miocene Atacama pediplain in the western Precordillera. New, together with published 40Ar-39Ar data from El Salvador combined with morphologic analysis reveal that the palaeospring plumbing system related to exotic mineralisation at the Damiana exotic Cu deposit and the local geomorphology has not changed fundamentally between the late Eocene and late Miocene. Stable H/D isotope data on supergene alunite from El Salvador indicate an overall increase in dD values (VSMOW) from -74ë at 35.82 ¦ 0.95 Ma to -23ë at ~11 Ma. The transition from strongly to moderately negative deuterium values occurred between ~16 and ~13.5 Ma. Supergene alunite from the El Hueso (3950 masl) sedimentary rock-hosted epithermal deposit ca 35 km SE from El Salvador was dated at 8.19 ¦ 0.01 Ma and yielded a dD value of -25ë. We interpret the increasing deuterium excess as the result of strong evaporation and recycling of meteoric water after ~15 Ma and as indicative for a change in precipitation patterns and climate desiccation. In contrast, the strongly negative dD value for late Eocene supergene alunite points to a more humid climate and an elevation similar to the present. The late Miocene supergene activity at El Hueso is probably related to an uplift of the Precordillera to elevations sufficient for capture of orographically controlled precipitation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

Prior to 1972, Peko Mines Limited at Tennant Creek used a central mill at Peko, which consisted of a gravity circuit, flotation and cyanidation of tailings, to treat their gold ore from surrounding mines. The Warrego concentrator, 60km to the west, was built to handle the Warrego and Gecko copper orebodies, which were being developed concurrently with the concentrator construction The Warrego concentrator consisted of a flotation circuit, using autogenous grinding at 100 - 120 tph, compared to the more elaborate Peko circuit employing rod mill - ball mill grinding capable of treating only 18 - 26 tph. During development of the Warrego copper mine a gold rich ore pod was located, because of which the mining plans were adjusted to allow simultaneous, separate extraction of the copper and gold ores. However, the plans for the concentrator were not affected as the gold ore could be carted 60km to the Peko central mill for processing.

Jan 1, 1978

By E Widzyk-Capehart

The mines of the future can be envisioned as complex, large-scale technological systems being operated remotely from few centrally located (major cities) operating centres and skeletal crew stationed at the site. These systems will require remotely located human operators to constantly adapt to new and unforeseen system and environmental demands. In addition, the remote operators will need to match system properties to the changing demands and operational conditions, ie must be able to handle the ‘non-design’ emergencies, because the system designers would not have been able to foresee all possible scenarios of failures and provide automatic safety devices for every contingency. Therefore, it is highly important that the operators’ job, which involves problem solving and decision making at the workstation level, is facilitated by the proper interface designs. This paper argues that decision support systems and thus human-system interfaces for the mines of the future should be developed based on the principles of human-system integration that take into account human information processing and cognitive abilities. The information presented to the operator must support the operator in taking appropriate action through a human-system interface designed according to scientific principles of User Centred Design. A case study is presented where an iterative design process was used by CSIRO researchers as an evaluation method involving users (control room operators) at several stages of the user interface design in order to correct any design inadequacies as they emerged. This process allowed the designers to identify any usability issues before the user interface was fully implemented, which subsequently enabled the control room operators to easily adapt to the new interface and carry out all designated tasks in a timely and effective manner.

Nov 22, 2011