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By M Fahey

Large volumes of tailings are produced annually by the goldmining industry of Western Australia. This material ishydraulically discharged into large storage facilities usingsub-aerial deposition methods. Much of the gold comes fromhighly weathered rock, resulting in tailings with significant claycontents. Consolidation of these materials can be very slow,particularly if occurring under the effects of self-weight alone.To optimise the consolidation behaviour of the tailings, disposalstrategies can take advantage of the effects of evaporation byallowing each tailings layer to dry before the next layer isdeposited. In the last 20 years, much of the gold processing inWestern Australia has utilised saline groundwater. As the salinetailings dry, the surface will develop a thin salt crust. Laboratorytests have shown that these crusts can drastically reduce thesurface evaporation, adversely affecting the behaviour of thestorage. This problem has been the focus of an extensive researchprogramme, with the objective of obtaining a fullerunderstanding of the mechanisms controlling the coupledconsolidation and evaporation behaviour of saline gold tailings.Part of this study involved site investigations of a wide range ofstorages to ascertain their current states. Methods of gainingaccess to the tailings following deposition were developed.In situ testing and high quality sampling were conducted on each storage and samples returned to the laboratory for analysis. These investigations have enabled full characterisation of the storages to be accomplished. Examples of data are shown herein and the implications of the results are discussed.

Jan 1, 2001

By K Broadley

Risk and dispute resolution are linked. Dispute resolution techniques are brought to bear on a dispute - which is an outcome of a risk being wholly or partially realised. There has been an increasing awareness by business of risk as a component of doing business. There is an accompanying awareness of the need to manage risk - including legal risk. Many companies have undertaken a systematic review of their potential risks and endeavoured to put in place systems to help to avoid or manage risks. A legal risk management program will not prevent disputes arising. However, such a program should prescribe how that dispute will be managed. The management of the dispute will involve consideration of the dispute resolution procedure to be adopted. The most appropriate processes will take into account the practical, personal and commercial considerations surrounding the dispute and be as efficient, cost-effective and user friendly as achievable in the circumstances for the benefit of all the parties. Carrying on business in South East Asia, whether as an explorer or a mining operator, brings additional considerations to bear in legal risk management and the dispute resolution process. A significantly different perspective is required due to the varying nature of the legal systems in many South East Asian jurisdictions. These jurisdictions often have relative uncertainty as to the law. This impacts on the dispute resolution processes and also raises further timing and cost issues. The authors contend that this is all the more reason to endeavour, as practically as possible, to adopt a legal risk management and dispute resolution profile which will provide business with the greatest prospects of maintaining control of the dispute resolution process. This presents a greater chance of a successful outcome to the dispute. In these times of increasing pressures on profitability because of low mineral prices, all costs of a minerals business are being reviewed. In such times, a significant legal dispute may have even greater potential to adversely impact on the companies concerned, together with the careers of the people involved. In this paper possible approaches to managing disputes and a case study a legal dispute in which Freehill Hollingdale and Page were involved are discussed. The dispute concerned an international mining company developing a gold mine in Indonesia and one of its contractors in Indonesia. Described is how that dispute was resolved. This achieved a very satisfactory result for the client - all things considered. Given the æadditionalÆ problems associated with ascertainment and enforcement of ærightsÆ in South East Asia, the longer the parties can retain control over their dispute the better off they will be. For this reason, the authors set out in this paper the main additional dispute resolution tools available - that are appropriate for use throughout South East Asia.

Jan 1, 1999

Two years ago I was sitting in a big lecture theatre at the School of Mines in Kalgoorlie at the annual New LeadersÆ Conference listening to a guy tell us all how much he loved his job, travelling the country ælegallyÆ blowing stuff up à and getting paid to do it. I would have paid to see and do the things he spoke of à now IÆm that guy. From finishing a mining engineering degree at the University of Ballarat, through the job hunt, to firing environmental blasts in Tassie and designing and implementing construction blasts in the middle of the Gold Coast. My name is Rohan Stevens and IÆm a blast-o-holic. While the æjob huntÆ we all embark on toward the end of our degrees is a stressful time, itÆs also very exciting in the current climate. There are a number of things I have learnt through both my hunt for the job that best suited me and working for the worldÆs largest explosives manufacturer. If at least you donÆt benefit from my learnings IÆm certain you will enjoy hearing about (and viewing) some of the work I have had the opportunity to be involved with over the last 18 months with Orica Mining Services.

Jan 1, 2008

By D O’Dea, B Godel, T Honeyands, G Evans, T Harvey

The pores within iron ore sinter are important for producing a high quality material that is strong and easily reduced. The complementary methods of mercury intrusion porosimetry (MIP) and X-ray computed tomography (CT) were used to characterise the structure of industrial and pilot scales sinters across a wide range of pore sizes (3 nm to 100 µm for MIP and 50 µm to 5 mm for CT). The inhomogeneous nature of sinter and the variation in the measurements make it difficult to compare samples. The generalised additive modelling (GAM) approach, using the open source statistical software package, R, has been applied to highlight where there are peaks in the concentration of pore sizes. Importantly, the shape of the GAM-fitted function and the heights of the peaks show statistically significant differences between samples. For the samples investigated, the GAM-fitted functions for the MIP volume distribution of pore diameters were found to have a common set of distinctive peaks at 0.005, 0.6 and 20 µm. The GAM approach was also applied to the X-ray CT measured pore wall thickness, highlighting a single peak whose position varies between samples. The cause of these distinctive peaks and their implications for sinter quality are discussed. Correlation was found between the volume in peak 1 (0.005 µm) and the concentration of primary hematite. No correlation was found between the pore wall thickness and the strength of the sinter, suggesting the composition of the pore walls may be more important. Future work will focus on small-scale sinters produced under tightly controlled conditions to study sinters with a wider range of quality values.CITATION:Harvey, T, O’Dea, D, Evans, G, Godel, B and Honeyands, T, 2017. Highlighting key features of the pore structure of iron ore sinter using mercury intrusion porosimetry and X-ray computed tomography, in Proceedings Iron Ore 2017, pp 39–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By M E. Dunphy, P Silversmith

The Reefton Goldfield, both historically and potentially, represents a significant gold producing camp in the Westland province of New Zealand. Some two million ounces of gold have been produced from the Greenland Group host rocks between 1870 and 1951 with the most significant producers being the Blackwater and Globe Progress mines.   Steep terrain, high rainfall, poor outcrop, widespread fluvio-glacial deposits, tertiary cover and sometimes onerous environmental access conditions have proved a challenge to conventional exploration techniques. In addition classic exploration techniques have come up against a desire to reduce exploration cycle time and exploration costs while increasing both quality and quantity of geological information.   The trial, and subsequent implementation, of Wacker sampling has proved a highly successful and effective geochemical tool currently being utilised to target, discover, and define potential economic gold mineralisation in the Reefton Goldfield.

Jan 1, 1997

Water rights and availability are extremely contentious issues in many mining regions around the world, in some instances leading to violent confrontation. This situation has the potential to only get worse because competition for 'scarce' water resources will increase with population growth. In this environment the dilemma facing the mining industry is how to generate confidence in developing a responsible, sustainable and transparent water management strategy that is recognised as such by all stakeholders. Whilst the water needs of the mining industry are minor compared to those of agriculture, an operating mine requires a relatively large quantity of water on a daily basis to carry out operations. Another contentious aspects of new mine development is the debate between all stakeholders on the amount and quality of water that a mine is able to discharge into the environment should this be required. There are a multitude of water resources available to the mining industry for operational needs however much of this water is saline and over the last two decades there has been a continual decline in water quality (ie salinity has increased). In today's world there are enormous internal and external pressures to reduce water consumption at a mine and/or alternatively use water not considered a resource by the local community (ie sewage, saline or salt water, desalinated water). Strategies to meet these objectives can be achieved by implementing good water management practices, by recycling process water, reducing water losses by evaporation and seepage (ie by increasing and improving dewatering practices) and employing new technologies such as dry stacking and dry processing. Recycled water, acid mine drainage water and water collected in the mining area have the potential to impact mineral processing performance, unless they are treated, because of the build up of mineral salts and decomposed chemical products in these types of waters. Besides this the regulatory requirements of any water discharged from a mine site (quantity and quality) have also become more stringent. For these reasons there is now some form of water treatment practiced at most mining operations around the world. This paper provides an overview of water stewardship undertaken in the mining industry over the last two decades and provides examples of water treatment practices that have recently been installed at mining operations that may be of interest to the reader.

Sep 13, 2010

In most surface mining operations, overall project economics is driven to a significant extent by the slope angles that can be achieved within the rock masses present. This is particularly true of precious metal pits in which stripping ratios can be relatively high, although examples from other non-precious metal operations (such as large iron ore and copper pits) can also be found. As a consequence, it is not surprising that in most large (deep) open pit mines, relatively small changes in slope angle (of the order of two or three degrees can translate into changes in project value measured in the tens or even hundreds of millions of dollars. Understanding how this potential value can be realised, and quantifying the associated risks, should be one of the key outcomes of modern slope engineering practice. In striving for optimised slope angles, therefore, mining companies and their specialist consultants are increasingly turning to more sophisticated methods of engineering open pit walls. This paper summarises contemporary slope engineering practice as well as some of the key technical issues that are either currently being researched or will need to be researched in the future. It is written in the context of the slope engineering process; namely, data collection and analysis, failure mode identification and stability assessment, slope design, slope formation, and slope (face) mapping and monitoring (the latter two activities being the primary on-going data collection functions that close the design loop).

Jan 1, 2002

It has been thought in the past that New Zealand had ample coal reserves, able to provide fossil fuel supplies well into the future. Such is not the case and every effort must be made to achieve the highest possible extraction rate in all new coal mining ventures. While the relative cost and availability of completion or fuels has been largely responsible for the slow growth of coal production in the past, a world shortage of fuels has given coal a new importance and required better utilisation of coal reserves. New mining ventures in thick-seam coal deposits cannot be planned and designed without geotechnical investigations designed to provide information required by the mining engineer and analyst. Finite element analysis of mine workings may provide essential information on the optimisation of mining techniques and the design of underground support and roadway shapes.

Jan 1, 1976

The Nena high sulphidation-type copper-gold deposit is composed of andesitic pyroclastic units with minor interstratified lava flows. Epiclastic sandstone and conglomerate, and siliciclastic rocks consisting of mudstone, shale, lithic and bioclastic sandstone and conglomerate are locally present. Pre-mineral diorite intruded and domed the volcano-siliciclastic sequence. Economic copper-gold is hosted by vuggy quartz altered lapilli tuff and tuff breccia. The early hydrothermal alteration stage involved deposition of epithermal banded quartz and chalcedonic silica in localised environments. This alteration stage was locally superimposed by a hydrothermal breccia event. Following the breccia event, magmatically-derived volatiles were channelled through a NW striking dilational fault zone and generated the high sulphidation alteration. The high sulphidation alteration is zoned from a vuggy quartz core with local massive replacement silica through a broad pyritic quartz-alunite halo and finally to a thin illite-smectite zone. This is surrounded by regional chlorite-epidote-smectite alteration. A gangue mineral phase consisting of quartz, alunite and baryte overprinted the zoned high sulphidation alteration and preceded the main copper-gold-arsenic mineralisation. Early sulphide deposition is characterised by marcasite, arsenical pyrite and melnicovenite. Main-stage copper-gold mineralisation involved sequential deposition of hypogene bladed covellite+chalcocite, enargite-luzonite and luzonite+stibioluzonite respectively. The copper sulphides are zoned from bladed covellite-chalcocite in the north (cross-sections 5000 - 5600 N) through enargite-luzonite (cross-sections 4700 - 5000 N) and to luzonite????stibioluzonite in the south (cross-sections 4400 - 4700 N). A late phase of minor acicular covellite and enargite+luzonite overprinted the zoned copper sulphides and associated gold mineralisation. Gold mineralisation commenced at the transition from enargite to luzonite, and continued through the deposition of luzonite-stibioluzonite in both stages. Most gold was deposited during the main-stage mineralisation. Yellow native sulphur was deposited in the remaining vugs and defines the waning stage of the hydrothermal system. Post-mineral dioritic intrusives and feldspar porphyries intruded the volcano-siliciclastic sequence. Finally, supergene chemical processes with associated erosion and uplift generated a 40 - 50 m thick oxide-hosted gold cap. The oxide gold cap is underlain by a 35 - 45 m thick blanket of supergene chalcocite+covellite mineralisation which overlies and occurs throughout the main hypogene copper-gold zone. Supergene gold is related to the distribution of primary gold-bearing sulphides. Therefore, remobilisation and redeposition of gold are considered to be insignificant and very localised.

Jan 1, 1999

Peculiarities of Quartz Distribution in Zinc Flotation Products and their Influence to Mineral Processing

Sep 13, 2010

By E Topal

Stopes are used in several underground mining methods. Boundary determination of these stopes is generally based on simple rules of thumb. While several stope boundary optimisation techniques are available, they fail to guarantee true optimum results. The first part of this paper reviews some important stope boundary optimisation studies and proposes a new algorithm to optimise stope boundaries and layouts for underground operations. The second part applies the proposed algorithm to a block model to test its ability to produce optimum results and demonstrate its applicability in a number of different scenarios. The results demonstrate that the proposed algorithm can find optimum stope boundaries and layouts in three dimensions for different stope sizes and economic conditions.

Jan 1, 2009

By S Christensen

In August 2001 the Minister for Conservation declined an application by GRD Macraes for an access arrangement to enable work at the Globe Progress Mine near Reefton. In her decision, Ms Lee said:æI have considered whether potential compensation and the proposed safeguards against some of the adverse effects are sufficient to outweigh my concerns as to the loss of conservation values, consistency with the objectives of the Conservation Act, the purposes for which the land is held by the Crown and, to a lesser extent, the North Westland Regional Management Plan. I do not think they are sufficient. To my mind, my concerns as to the consistency with the objectives of the Conservation Act, the purposes for which the land is held and the loss of some conservation values in particular, outweigh any potential compensation and possible mitigation of adverse effects.Æ Commenting on the MinisterÆs decision Guy Salmon of the Ecological Foundation stated that the Minister should have invited the applicant to provide a 10 000 hectare pest-free wildlife sanctuary as part of the æpriceÆ for obtaining that access. However,æfor many people of green persuasion, it has become fashionable to say no every timeàthose who really have the well-being of the environment at heart, will want to look carefully at the bigger picture of environmental restoration needsàThe deciding criterion: the mining company should show that its involvement on conservation land would produce a net conservation gain. That is a criterion that creates the right incentives for win-win-win solutions on conservation land.ÆThis paper considers whether the concept of off site mitigation is one which fits within the current legal regime. Two questions arise:Can such mitigation/compensation be legally considered in access arrangements or required as a condition of resource consents? Is this a realistic option for industry to be pursuing?

Jan 1, 2002

This paper discusses the prediction of subsidence over partial extraction systems in thick coal seams. A model based on empirical techniques using influence functions is developed to calculate the surface ground settlements above extraction panels. Independent of the influence function, two field parameters, the subsidence factor and the angle of draw (limit angle) are required to define the model. Both these parameters are best observed from critical or super critical subsidence areas. However in thick seams, extraction widths are typically sub critical and therefore it was necessary to refine an estimation process for sub critical conditions. Partial extraction systems in NZ are characterised by variability with respect to extraction thickness and depth. As extraction proceeds along a panel, conditions deteriorate once the critical span width is exceeded and therefore percentage extraction decreases. A further variable was introduced to the modelling which allows for varying extraction sequences. Two comparisons with field observations, one over a partial extraction panel, the other over abandoned workings, showed the method gave good agreement to measured subsidence values.

Jan 1, 2002

Gold rush histories are usually written as though they were unique events in the development of a region or nation. While this is a valid way of looking at gold rushes, it is not the only way. This paper is a brief attempt to relate the West Coast rushes to a wider context. During the second half of the nineteenth century the lure of gold transformed the Pacific Rim. Gold rushes drew more than half a million Europeans and Americans to lands bordering the Pacific. By 1900 a chain of mining, industrial and urban centres ran from California to Alaska; from Ballarat to New Guinea, and on to Western Australia. The New Zealand rushes were a significant chapter in this story. People, cargo and information passed from rush to rush. Techniques learned on earlier goldfields were imported; those developed in New Zealand were, in turn, taken up elsewhere. Administrative systems and regulations developed in Australia were implemented in New Zealand, improved and passed on to Canada. This interconnectedness was so strong that gold-seekers thought of the mining regions as a distinct culture, 'the whole digging world'. Much can be made of the similarities shared by rushes. But comparison can also highlight the individuality of each rush. +The early days of the West Coast rushes were perhaps the strongest assertion of a diggers' culture. A brief period in which a remarkable orderliness was created through mateship, self-regulation, and the occasional threat of rough justice. The West Coast rushes were both a unique experience and an integral part of a process which transformed the Pacific Rim during the nineteenth century. Understanding their part in that bigger story highlights just how unique they were.

Jan 1, 1996

The design of a mine should aim to optimise the market value by maximising revenues whilst minimising costs. In open pit mining, the nature of the extraction technique translates this objective into the maximum recovery of reserves while minimising waste extraction subject to technical, economical and safety constraints. Since the introduction by Lerchs and Grossman, in 1965, of a model that is now considered a classic in the area, open pit design has reached a level of maturity and acceptance by industry. These models are being used on a regular basis by designers and planners.This paper proposes a new alternative model for open pit design. It is based on genetic algorithms (GA) and exploits a reduction of the number of decision variables of the more traditional techniques. The novel approach provides more flexibility than traditional models; it can also be extended to consider planning problems that traditional open pit design models are not capable of handling. The algorithm has been designed for two dimensional problems and tested in a simple instance. The results obtained in this simple test are encouraging and are a good supporting argument for the development of a GA model capable of handling three-dimensional (3D) instances. The model presented in this paper is just a first step towards a full GA to solve the pit design problem and it is believed that novel tools like the one presented herein could become great allies in tackling challenging problems in open pit design, an illustration of such a challenging problem is presented and discussed.

Dec 6, 2010

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

As a minerals company, obtaining the appropriate consents under the Resource Management Act 1991 and getting permits granted for exploring, prospecting and mining under the Crown Minerals Act 1991, is necessary for actively exploring and mining in New Zealand. But the essential mix of ingredients for a viable and healthy Industry go way beyond this.   In the short term, an individual company seeking to operate on or within the Crown minerals estate of New Zealand must chart a course through the requirements raised by new cornerstone legislation, the Resource Management Act, the Crown Minerals Act and, the Conservation Act 1978 (where the minerals sought coincide with this estate).   However, this paper suggests that in the longer term for individual operators within the Industry and for the Industry at large to remain viable and sustainable and for New Zealanders to continue to enjoy its benefits, much more is required. Not least of which is a better balancing of competing uses and attitudes, which will require an opening of minds, a change in mindset, topped off with those two most essential of ingredients advocacy and leadership.   New Zealand has undergone massive restructuring in the last 15 years. Is it complete? Have each of its fronts evolved to the end point which was envisaged by the designers of the regime? What are the advantages? What is left to be done? What are the impediments from an incomplete transition which are left to either dog the Industry or remain as a challenge to be removed to ensure the Industry's smooth sailing into a prosperous and environmentally clean and friendly future? A future wherein an educated and understanding public welcome and are proud of the Minerals Industry to whom they owe the standard of living which they enjoy.   This presentation will examine the role of the New Zealand Minerals Industry Association (NZMIA) in paving the way for an optimum operating environment in which to couch a healthy industry into the future.

Jan 1, 1997

New Bio-Adsorber with Activated Carbon and Nano Tube Carbon for Separation of Nickel and Cadmium

Sep 13, 2010

By E Hollinger, J L. Mauk

Gold-silver mineralised veins at Favona, represent a new low-sulfidation epithermal vein discovery that occurs less than 1 km southeast of the world-class Waihi deposit. The Favona vein is hosted in Late Miocene andesitic lava flows and local dacitic tuffs that are intensely altered to quartz, adularia, chlorite, illite or interstratified illite-smectite (with ten to 70 per cent smectite) and pyrite. Adularia is widespread and envelops the veins, whereas chlorite and illite are mostly restricted to the footwall, and illite-smectite is confined to the hanging wall of the Favona vein. At shallow levels, kaolinite, cristobalite and rare alunite overprint the above minerals. A polymict hydrothermal breccia also occurs above and in the hanging wall of the Favona vein and contains clasts of altered andesite and various quartz vein fragments. Fluid inclusions in quartz veins sampled over a 300 m vertical interval have a homogenisation temperature range of 175¦ to 266¦C and dilute apparent salinities of 220¦C and grading into illite-smectite and local smectite which formed at 2. In contrast, late kaolinite, cristobalite and alunite formed from descending steam-heated acid-sulfate waters. Overall, the Favona and Waihi deposits are interpreted to have formed at similar levels in a single low relief hydrothermal system, with each deposit representing a distinct zone of fluid upflow.

Jan 1, 2002

Contact Angle Measurements on Lignite Surface

Sep 13, 2010