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By J P. Clark

Industrial minerals contribute about 50% of the NZ$1.2 billion generated annually by the minerals industry in New Zealand. The value is supplemented by a further NZ$500 million of minerals imported to supply our vital agricultural and industrial activity. As globalisation of the world's economy precedes, sources of minerals are being processed by fewer companies giving an ever-increasing control over global markets. If only to protect its primary production New Zealand needs to aggressively develop its mineral resources. The successful development of a deposit requires identification of the preferred market. While low-value aggregates dominate New Zealand industrial mineral production it is more specialised minerals supplied to the manufacturing and industrial sectors that provide more value per tonne. Minerals that have highly desirable intrinsic properties, or through value-added processing provide desirable properties, have the ability to fill niche markets both locally and overseas. Research and development towards enhancement or creation of desirable mineral properties could benefit New Zealand with both increased mineral potential and export of technological information. But, it is nearly always the market not the resource that dictates the viability of an industrial mineral and, with the globalisation of industrial mineral markets resulting in fewer but larger companies, any supplier must be ready to explore niche markets in order to compete on a more global basis.

Jan 1, 2000

By K J. Thompson

This paper describes the work which has been undertaken at the Ohai coalfields in Southland to restore overburden heaps during past opencast mining operations, and procedures which have been adopted to ensure that restoration is achieved concurrent with present opencast mining activities. The system implemented for the treatment of wastewater from opencast mining operati6ns is also described.

Jan 1, 1981

By B Rosemberg, F Lemos, A J. B Dutra

The chemistry of cyanide solutions is complex, this complexity being responsible for the ability to act as complex-forming agents in metal dissolution processes, among them gold and silver. Such ionic species are used in hydrometallurgical processes, in particular in gold extraction and electro-plating. Due to the high toxicity of cyanide, the discard of effluent from processes and/or industries demands rigorous treatment so as to minimise its concentration. Among the conventional chemical treatment of such effluents one can mention SO2/air; biological degradation; oxidation by using hydrogen peroxide; oxidation by sodium hypochlorite, etc. However, the electrolytic recycling process is also promising for cyanide recovery and offers the possibility of recycling it to the aforementioned industrial processes. Such a process does not use additional chemicals but enables direct re-utilisation to the main process aiming at adjusting the cyanide concentration.

Jan 1, 2002

By D J. Brake

There has been a strong trend over the past decade in hard rock mines towards the use of very high powered auxiliary (or secondary) fans; in many mines, the installed power for the secondary ventilation system now exceeds that of the primary ventilation system. This also reflects the trend to use two-stage auxiliary fans pushing air into a single ‘trunk’ duct that in turn splits into multiple branches with multiple outlets feeding multiple workplaces. This often produces a poor result in terms of face flows due to the high resistance, high leakage and badly managed duct outlets, as well as high fan capital and operating (power) costs, which in turn also results in a higher cost for the underground power reticulation/distribution systems. This paper explores the reasons why this trend exists and what ventilation practitioners can do to utilise less expensive systems that simultaneously deliver better workplace conditions. It includes a case study.CITATION:Brake, D J, 2017. Auxiliary ventilation design – why and how mines waste so much power on inferior systems, in Proceedings Australian Mine Vent Conference 2017, pp 27–34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By S Speed, N Corlis, A Goldstone, G N. Browne, M Fitzpatrick

In 2005, Solid Energy New Zealand Limited obtained non-notified consent for the disposal of 1Mt of coal ash at the Rotowaro minesite, forming part of a coal supply agreement with the Huntly Power Station. A non-notified resource consent was sought which necessitated that environmental effects be shown to be æless than minorÆ, and resulted from robust science and a pragmatic approach to design. As part of the assessment of environmental effects, there was a need to understand the effects of boron concentrations on aquatic organisms (ie algae, plankton, plants and invertebrates) in the receiving environment. Boron is a naturally occurring element that is found in the form of borates in the oceans, sedimentary rocks, coal, shale, and in some soils but Waikato coals and ashes have particularly high boron content. Boron is an essential micronutrient for higher plants with interspecies differences in the levels required for optimum growth. As aspects of the ANZECC (2000) derived boron limits are based on toxicity of aquatic algae and plants to boron it was important to assess these components in the environment. The effects on the receiving environment of the Awaroa Stream were assessed using predicted water chemistry and comparing actual boron concentrations in a comprehensive and multifaceted reference-condition approach of catchment ecological indicators. In addition a toxicological-based assessment of boron and a re-calculation of the ANZECC trigger levels were undertaken and applied to the ecological indicators. The reference-condition approach revealed that habitat and overall water quality attributes at and between sites was more influential in determining the aquatic biotic communities than boron concentrations alone. There was no evidence of any gradient of changes in ecological indicators with changing boron concentrations, nor evidence of any residual effect of high historic boron concentrations on the aquatic biota.

Jan 1, 2006

Role of Bubbles in the Action of Flotation Agents

Sep 13, 2010

By H Chen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Mesozoic iron oxide-copper-gold (IOCG) mineralisation in southern Perú and the northern Chile coastal IOCG belt have emerged as two of the major exploration targets in the Central Andes in the last two decades. These Mesozoic Andean IOCG deposits formed in two mineralisation epochs, the Middle-Late Jurassic (170–150 Ma) and Early Cretaceous (130–110 Ma), with the major Cu-rich IOCG deposits located in the Early Cretaceous mineralisation belt. The early studies in some IOCG centres support a magmtic-hydrothermal model for both Cu-rich IOCG deposits and broadly contemporaneous Cu-poor ‘Kiruna-type’ magnetite deposits. However, recent evidence from field, geochronology, fluid inclusions and stable isotopes show that in the major Central Andean deposits (eg Raúl-Condestable, Mina Justa in southern Perú, La Candelaria-Punta del Cobre and Mantoverde in northern Chile), the incursion of evaporite-sourced basinal brines or sea water may be a prerequisite for economic Cu mineralisation. Moreover, the Cu-poor massive magnetite deposits could be interpreted as a product from iron oxide melt, with minimal intervention by non-magmatic fluids. Therefore, they could represent two contrasted deposit types and contain little genetic relationships. The different roles of magmatism during the Mesozoic are responsible for the variable mineralisation in the Central Andes, including IOCG, magnetite and ‘manto-type’ deposits. The ore modelling for both the Middle-Late Jurassic and Early Cretaceous metallogenic epochs in the Central Andes are reconstructed.CITATION:Chen, H, 2015. The Mesozoic iron oxide-copper-gold (IOCG) mineralisation in the Central Andes – a refined IOCG ore-forming model in the Palaeozoic Continental Margin, in Proceedings PACRIM 2015 Congress, pp 251–254 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By R E. Myers, G N. Phillips

Many of the worldÆs larger iron ore deposits are hosted by rock sequences of Archaean to early Proterozoic age. Most models for the genesis of these deposits are influenced, either directly or indirectly, by the nature of the atmosphere at the time of their formation, and more specifically by the presence or absence of oxygen in the early atmosphere. Since the early-1950s, the geological literature suggests that the Archaean atmosphere was æreducingÆ, and that it may not have contained significant amounts of free oxygen until ca 2 Ga. There are many different definitions of the term æreducingÆ, but the criterion adopted here is whether crustal iron was limited to Fe2+, or whether Fe3+ was also widespread, ie was there scope for redox changes in the state of iron? Significantly, major Australian banded iron formations span this period of inferred atmosphere transition, eg Mt Goldsworthy, Mt Tom Price, Middleback Ranges. Geological evidence for a reducing Archaean atmosphere is both ambiguous and controversial (see review by Phillips, Law and Myers, 2001). Many earlier ideas (eg no Archaean redbeds; all very large iron ore deposits being post-Archaean) have been disproved by dating, whereas other evidence (eg homogeneous detrital gold grains, inferred palaeosols) has not withstood geological scrutiny. The interpretation of some data sets (eg inferred detrital uraninite and pyrite in some Archaean meta-sedimentary rocks) is still controversial. In fact, some lines of evidence now suggest that oxygen was present in the atmosphere well before 2.5 Ga (eg sulfates in the Pilbara craton, carbon distribution in clastic sedimentary rocks). An oxidising Archaean atmosphere has important implications for the development of iron formations. First, the atmosphere is an obvious potential source of oxygen to stabilise ferric iron minerals. Second, reduced fluids in equilibrium with ferrous iron are commonly inferred to transport iron in solution to the depositional site. The redox state of the atmosphere thus provides critical constraints on the solution chemistry of surface waters, effective transport paths for iron and particularly on viable precipitation mechanisms. Iron formations developed from fluids in equilibrium with the atmosphere also have the potential to provide important constraints on the evolution of EarthÆs early atmosphere. If an oxygenated atmosphere is a necessary condition for the development of iron formations, then the Archaean atmosphere must have been oxidising since at least 3.5 Ga. If the redox state of the atmosphere is not a necessary condition, then the time distribution of iron formations cannot be used to provide constraints on atmospheric evolution. Given these uncertainties, models for the genesis of iron ore deposits of Archaean or early Proterozoic age should not rely on a reducing atmosphere in the absence of independent evidence and the alternative of an oxidising atmosphere should also be considered.

Jan 1, 2002

By W J. Rankin

A study was carried out to compare the environmental impacts of a number of process routes for lead and zinc metal production from sulphide ores using Life Cycle Assessment methodology and based on average industry data derived from the literature. The processes investigated were:blast furnace production of lead; Imperial Smelting Process for lead and zinc production; and electrowinning of zinc with the mining and mineral processing stages common to all three routes. The effect of a number of process variables, namely ore grade, fuel source for electricity generation and efficiency of generation, on the environmental impacts was also examined. The environmental impact categories considered in the study were:total (or full cycle) energy consumption; Global Warming Potential (GWP); and Acidification Potential (AP). The results of the study show that when produced separately, zinc production is more than twice as energy intensive as lead production (viz 48 and 20 MJ/kg respectively), however when produced jointly by the Imperial Smelting process, the energy intensity of the two metals is not all that dissimilar (viz 36 and 32 MJ/kg respectively). The metal production and refining stage was found to make the greatest contribution to the overall environmental impacts for all three processes. The study also highlighted the importance of taking a life cycle approach when comparing the environmental impacts of different processes.

Jan 1, 2002

Au-Ag Recovery from Complex Ore by Flotation

Sep 13, 2010

Traditionally, the gravity cleaning of coal has been evaluated in pilot plant tests. Attention is now turning to the development of empirical models of gravity cleaning equipment that can be used for the design and evaluation of circuits. This paper presents some preliminary information for spirals and water-only cyclones treating fine coals. Also discussed is how such information gives a better understanding of the operating and performance characteristics of this equipment, how realistic comparisons can be made between different types of equipment, and how small mobile plants could be designed for treating the fine coals 'stockpiled' at many NZ mines.

Jan 1, 1985

By G B. Arehart

The Midas epithermal system is one of the larger low-sulfidation epithermal vein systems discovered in the western US in recent years, containing in excess of 3 Moz of gold (premining). The deposit is spatially and temporally related to bimodal volcanism in the Northern Nevada Rift; dates on igneous rocks (16 - 14.7 Ma) bracket the age of high grade veins (15.3 Ma). Hydrothermal alteration at Midas is typical of epithermal systems, comprising proximal potassic through distal propylitic assemblages; in contrast to many epithermal systems, Midas has minimal development of wallrock illite/sericite. Mineral assemblages are clearly zoned on the vein structures that acted as focal planes for fluid upflow. Geochemical zoning patterns also show this zoning. Metals were deposited in open-space veins as the result of boiling of hydrothermal fluids; multiple episodes of crustiform mineral deposition are documented in the vein textures. The major vein minerals include quartz, adularia, calcite, selenides and sulfides, with electrum as the primary ore mineral. REE patterns for vein material are similar to patterns for coeval rhyolites, but distinctly different from patterns of the host rocks. Stable isotope data are consistent with meteoric water as the dominant ore fluid. Combined REE and stable isotope data suggest that fluid from which the main ore-bearing stage of the veins was deposited was slightly lower pH than other stages.

Jan 1, 2005

By D N. Castendyk, J L. Mauk

The world-class Waihi (>6.6 Moz Au, >41.8 Moz Ag) and adjacent Favona (>0.5 Moz Au) deposits are within a single volcanic-hosted epithermal Au-Ag district located in the southern Coromandel Peninsula, New Zealand. Gold and silver mineralised quartz veins at both deposits are hosted in porphyritic andesite flows of the Waipupu Formation. Both deposits have veins surrounded by intense widespread hydrothermal alteration that is characterised by the assemblage of quartz, pyrite, adularia, illite or interstratified illite-smectite, plus less common chlorite and albite, which is locally overprinted by minor calcite or rare kaolinite. Quantitative mass transfer calculations using Gresen's general metasomatic equation indicate that hydrothermally altered andesite at both deposits is enriched in silicon, potassium, rubidium, barium, sulphur, gold, arsenic and antimony, whereas sodium, strontium and calcium are mostly lost. Iron and magnesium show mixed gain and loss. Element gain or loss can be directly related to the prevailing alteration mineralogy. Addition of potassium, rubidium and barium coupled with the concomitant loss of sodium, strontium and calcium in intensely altered wall rocks corresponds to the replacement of plagioclase by adularia or illite. Partial retention of sodium and calcium reflects the presence of hydrothermal albite and calcite, respectively. Mass balance calculations show distinct element gain and loss that can be related to the intensity and type of alteration mineralogy. However, because most rocks are intensely altered and the progression into less altered peripheral rocks is not observed in this study, the lateral extent of elements gain or loss is unconstrained with anomalies extending at least 200 to 300 m away from major veins.

Jan 1, 2003

I want to explore whether it is valid or even useful to talk about sustainable corporations. After 20 years of focus on sustainable development, the concept of a sustainable corporation is not particularly helpful and it may in fact be profoundly misleading. Why? û because it obscures the need for corporations to be recognised as part of a sustainable society, rather than achieving some kind of corporate nirvana divorced from the social, political and environmental reality. It is more helpful to ask whether corporations are ready to recognise that they are one player among many within society û with the demands this would place on them in terms of transparency, accountability and social responsibility. The achievement of sustainable development has become the new corporate orthodoxy of many large corporations. It has become a clichT to argue that corporations must become æsustainableÆ. The achievement of æsustainabilityÆ is encouraged, as the ultimate step in some form of corporate evolution. We are failing to recognise that sustainability a process û not an end in itself. An enormous array of instruments is being developed to measure when sustainability is or is not being achieved. For example, corporate reporting has burgeoned into an art form, which describes æsustainabilityÆ in a variety of ways. There is no external standard applied to such reporting. These descriptions are quite partial and often place the best possible gloss on the companyÆs activities. I have become increasingly uneasy about this rhetoric and this paper has allowed me the luxury of sorting out my unease. I will discuss, largely in the Australian context, the current debate and literature and describe the way some global mining corporations are dealing with these questions, and finally, offer some suggestions which might be helpful at the operational level.

Jan 1, 2002

An Integrated Solid Waste Management Method for Western Macedonia, Greece

Sep 13, 2010

Consents Required for Overseas Persons Overseas Investment Regulations 1974 Foreign investment proposals must be reviewed by the Overseas Investment Commission to ensure that these are in accord with national interests. Consent must be obtained from the Commission for: 1. New investment proposals which include: a. An overseas person acquiring 25 per cent or more of any class of share in a company. b. A New Zealand company issuing shares to an overseas person where this will result in that person owning 25 per cent or more of the company. c. An overseas person acquiring business assets for consideration in excess of $100 000. d. An overseas person commencing business in New Zealand. 2. Borrowing in New Zealand: An overseas person must obtain consent to raise funds in excess of $300 000 in New Zealand. 3. Borrowing Overseas: New Zealand incorporated companies must obtain consent to borrow overseas. Current policy is borrowing will be approved where the loan is for a specified fixed term of one year or more.

Jan 1, 1982

By W J. Rankin

Metals are well suited to sustainable development goals. They are not biodegradable and have virtually an unlimited lifespan and the potential for unlimited recyclability. Thus metals can be considered as renewable materials. However mineral resources, the source of primary metals, are ænon-renewableÆ as their supply is finite, but this does not necessarily mean scarcity. In this paper the results from a series of Life Cycle Assessments of primary metal production processes for copper, nickel, lead, zinc, aluminium and steel have been used to examine how metals may contribute to societyÆs transition to sustainable development. Particular issues considered include:current metal reserves and how these may change in the future; some of the environmental impacts (Total Energy, Global Warming Potential and Acidification Potential) associated with primary metal production and how they will be exacerbated by declining ore grades; new processing technologies with lower energy consumptions and improved metal extraction efficiencies that will reduce reserve depletion and environmental impacts; increasing the utilisation of æmetals in useÆ by recycling, with particular reference to aluminium; and the potential impact of a carbon tax on metal prices and how this may influence the ways in which metals are used in the future.

Jan 1, 2002

Resources and reserves are critical inputs into the determination of an operating mineÆs financial results and balance sheets, but how well understood is this fact. Do the investors, directors, accountants and geologists/engineers responsible for preparing or relying on relevant aspects of the end results properly understand the inputs and outputs and the associated risks that may be established. The first step is to understand how financial reports are impacted. The most obvious, and best known, impact is in the calculation of depreciation and amortisation charges against long term assets. In addition, however, there is a requirement to regularly determine whether asset book values are impaired û this is nearly always performed globally by the preparation of a discounted cashflow model for a mine which is usually based on a mine life as determined from the resource and reserve statement û the particular driver here is normally the short and long term production plans. A key aspect of the short term production plan is that it would normally not assume that the reserve and resource statement implies consistent grade, stripping ratios, etc. However, outside of the early years of a plan, more generic assumptions of these variables are often made in conjunction with the reserve and resource statement. Depending on the timeframe of the detailed production plans, this can have a large impact on a projectÆs net present value. Other financial balances that may also be impacted include restoration and rehabilitation provisions, retrenchment provisions and deferred or equalisation stripping accounts. The age old question of whether all reserves should be used or whether some or all of the resources should be included for financial reporting purposes has never been adequately resolved. It is our view that there should be no prescriptive answer to this question but judgement of all professionals involved in the process needs to be included. Furthermore, the company needs to be able to support their conclusions with well thought out and appropriate answers. This may not be in line with the approach that certain accounting standard setters may be proposing or taking, and this paper will outline the current status of global requirement and the likely future directions. Whether reserves or resources are utilised, does not change the key requirement that those preparing or using reserve and resource statements need to understand key aspects. For example: geologists/engineers do they know how reserves or resources will be used? have they imparted information on variability of key drivers such as grade or depth or dilution? do they know that major financial/business altering decisions may be made based on the analysis? accountants do they understand where the numbers have been derived from and the assumptions that may have been made in their determination? do they understand the degree of accuracy (or inaccuracy) that may exist particularly with resources)? do they understand the history of resource reconciliations and what it may mean for the future? directors do they understand the processes undertaken by the company to prepare the financial report and the interaction between the geologists/engineers and accountants? do they understand the potential sensitivity of results to the input variables? Financial reporting is extremely reliant on the use of the reserves and resources, however, the geologists/engineers, accountants and directors do not always understand the interactions between themselves which may lead to misleading public reporting. More education and communication between various parties is needed.

Jan 1, 2002

By N H. S Oliver

Five major veining events have been identified within the area surrounding the Mount Whaleback microplaty hematite deposit. These veining events can be directly correlated to the established deformation history of the Hamersley Province (Brown et al, in press). Vein formation temperatures of 203 to 231¦C have been obtained from primary fluid inclusions within veins which formed around the postulated time of ore formation. Preliminary proton induced x-ray emition (PIXE) analysis of these inclusions indicates KCl is the dominant salt species with varying levels of Ca, Fe, Ti, Mn present. It is suggested that some of these veins may have formed from feeder or effluent fluids from microplaty hematite ore formation.

Jan 1, 2002

No one process, product or effect of the minerals sector can be viewed in isolation when addressing sustainable development. Meaningful assessments of the minerals sector require that its processes and production are drawn together in a generic framework that gives a holistic view of its performance and progress. Lifecycle Assessment is increasingly accepted as an appropriate means of constructing such a framework. It is a step beyond using the simplistic concept of the triple bottom line of social, environmental and economic performance to drive and communicate sustainable development. However, fundamental questions need to be raised about the scope and purpose of lifecycle assessment, such as what effects and performances should be assessed, for whom should they be assessed, and what performance indicators should be used and how should they be selected. The principles of eco-efficiency, industrial ecology, The Natural Step (TNS) and other pertinent philosophies and initiatives driving mineral sector sustainable development are outlined to support a lifecycle stewardship vision for the minerals sector. Articulating this vision through a holistic lifecycle indicator system showing inputs and outputs, natural partnerships, effects on community, environment and economy facilitates recognition of problems, opportunities and partnerships that can be usefully pursued.

Jan 1, 2002