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By D Cork, R Peet

"Methane is a signifi cant greenhouse gas. Methane is released from coal seams during the mining process, both in surface and underground operations. This uncontrolled release is termed æfugitive emissionsÆ and in underground mines is transferred to the atmosphere in ventilation air, known as ventilation air methane (VAM). The global VAM emissions are over 369 Mt of CO2-e/a (Butler, 2011; US EPA, 2010). Coal mines may abate this VAM or consider abatement should there be a price on carbon. These fugitive emissions are heading towards ten per cent of AustraliaÆs emissions by 2020 (Department of Climate Change, 2011).There are safety issues involved in VAM destruction. Due to the nature of coal, and coalextraction, unpredicted methane spikes above the lower-explosive-limit (LEL) can occur in theventilation air; for example outburst events or ventilation failure. This could lead to a mine fi re ifthe mine ventilation air was connected to a VAM abatement plant and the risks are left unmitigated.CorkyÆs is working with the mining industry to directly address these safety issues. CorkyÆs calltheir technology VAM RAB, which stands for ventilation air methane regenerative afterburner(VAM RAB). VAM RAB utilises the principles of a thermal oxidiser.This paper discusses fi ve independent layers of protection (ILPs) to fi rst stop methane reachingthe thermal oxidiser and secondly prevent the fl ame front from burning away from the VAMRAB. The test work completed or contemplated includes safety integrity level (SIL) assignmentto various vents, barriers and door systems to prevent a fl ammable mixture reaching the VAMRAB, proven rapid response methane monitoring sourced from the petrochemical industry, anddefl agration experiments to test the eff ectiveness of the passive geometry and active engineeringcontrols. These experiments and SIL assessments indicate that it is possible to safely connect theVAM RAB to a working coal mine.Further work is required to upscale the pilot safety work. Refi nement to the design is possible;for example improvement to safety duct controls once trialled at demonstration scale plus thermalenergy capture for power generation or other applications to provide heat. Nevertheless, thispaper shows how safety issues can be managed by a multilayer of protection approach usingvents, barriers and doors, and appropriate thermal oxidiser geometry."

Jun 1, 2012

By J Mauk, J Rowland, S Rabone

Most epithermal Au-Ag deposits in the Hauraki Goldfield are hosted in late Miocene andesites. Broken Hills is an exception, being one of the few economic deposits hosted in rhyolite. Investigation of Broken Hills provides the opportunity to collate structural data that may be compared with that collected from andesite-hosted deposits in order to evaluate the importance of rock type on vein development. The rhyolite host rock at Broken Hills is strongly flow-banded, but this anisotropy does not appear to affect the orientation of mineralised structures. There is a range of structures at Broken Hills: veins, faults, fractures, and large breccia pipes. Veins generally strike north-south, with localised changes in strike and thickness. Slip vectors determined from striations indicate near pure dipslip on the main lode, indicating an extensional tectonic setting. The orientations of vein deflections are parallel to slip vectors. This correlation is common in modern extensional fault arrays where fault growth and linkage produces subvertical deflections in fault orientation (eg TVZ). There are three main types of breccias: 1. Primary breccias related to rhyolite emplacement. 2. Jigsaw type secondary breccias that are that developed during the life of the hydrothermal system. 3. Breccia pipes. Broken Hills was a dynamic epithermal mineralising system.

Jan 1, 2003

The Crown Minerals Act provides a new+framework for the management of Crown owned minerals and requires that regard be had for the principles of the Treaty of Waitangi. The Act requires the preparation of Minerals Programmes to achieve the Act's objectives of efficient allocation of rights and the recovery of a fair financial return on its minerals. Efficient allocation requires that a permit is allocated to the party which values it most highly. A fair financial return to the Crown must be considered in the context of the economic rent available from individual mineral projects, with the proviso that a nil return to the Crown as the owner of the resource will not be considered a fair return from the community's perspective.

Jan 1, 1992

With the continued implementation of stricter limitations on the discharge of excess process water from all existing and future mining and metallurgical operations, the design and operation of the entire process water circuit must form an integral part of any total operational package. It is far better to æanticipate and circumvent the problemÆ rather than be forced into an expensive remediation program after the event. By far the greatest problem relates to the treatment and disposal of what is generically known as acid drainage. In simple terms, an acidic metal sulfate solution is generated by a series of chemical and biological reactions as soon as most sulfide minerals are exposed to air and water. Treatment of this solution by one or more of a wide range of chemical and physical options can involve substantial capital and operating costs, although there are recent processing options that yield saleable by-products, thereby reducing the financial liability of what is effectively a waste stream. This presentation provides an overview of the Australian situation compared with the rest of the world and outlines the basic features of a number of the more advanced passive and active acid drainage options.

Jan 1, 2004

By D C. McPhail, S L. Rogers, J Brugger

Using iron- and sulfur-oxidising bacteria to catalyse the breakdown of sulfides that host the gold is an important biological method for the pretreatment of refractory gold ores. Following this biological treatment a combination of chemical and physical methods are used for leaching (such as the cyanide process) and concentration (such as carbon-in-pulp or electrowinning) of gold. Although these methods are well accepted by industry, they harbour limitations in the processing of low-grade refractory ores, and regulatory agency/public acceptance of cyanide use. Thus, it is beneficial to industry to develop environmentally friendly, cost-efficient leaching and concentration techniques that are based on micro-organisms. This may soon be possible by adapting the results of recent regolith geoscience research, which has shown that micro- organisms are capable of driving a biogeochemical cycle of gold dispersion, transport and reconcentration in the supergene environment. The indigenous microbiota in biologically active soil microcosms from a number of Australian sites are capable of solubilising up to 80 wt per cent of the gold contained in these materials during 50 days of incubation. Studies using molecular microbial techniques have shown that a metallophilic bacterium, Ralstonia metallidurans, is present in biofilms on gold grains from a number of Australian sites. R metallidurans is capable of actively accumulating gold from solution, suggesting that the bacterium may contribute to the formation of secondary gold grains and nuggets. Identifying the biochemical and physiological pathways that lead to the dispersion and accumulation of gold in regolith, and quantifying the reaction kinetics of these processes may thus lead to the development of industrial bio-processing capacities for gold-containing ores.

Jan 1, 2007

Effective Dry Density Benefication of Coal

Sep 13, 2010

Cyclonic Separation Effect of Metallic Ores in Cyclonic-Static Micro-Bubble Flotation Column

Sep 13, 2010

By E Jak, M Shevchenko, E Nekhoroshev, D Shishin

In the field of pyrometallurgy, the presence of multiple molten phases with distinct chemical compositions, such as slags, mattes, speiss liquids, metals and molten salts, is a well-known phenomenon. These phases exhibit strongly non-ideal solution behaviour and are mutually miscible to varying degrees. To describe these complex molten liquids, the Modified Quasichemical Model (MQM) has proven effective and has been applied to numerous binary, ternary and several higher-order multicomponent systems related to pyrometallurgy. In recent decades, the complexity of high-temperature processes has escalated due to increased impurity concentrations in primary ores, the incorporation of recycled consumer products and the integration of metallurgical plants through by-product and waste exchanges. To address these issues, PYROSEARCH laboratory has been developing large 20-component thermodynamic database using a generalised CALPHAD (CALculation of PHAse Diagrams) methodology integrated with experimental investigations. Over the past decade, strategic decisions were made balancing the ability to generate experimental data, prediction power, accuracy, stability of calculations, as well as computational time, which are discussed in the paper. Examples provided for issues of >3 liquid immiscibility, non-ionic behaviour and exaggerated ‘sharp’ enthalpies of mixing in silicate slags, dealing with multiple oxidation states, as well as comparative analysis of pair and quadruplet approximation in MQM.

Aug 21, 2024

Distinguished guests ladies and Gentlemen. As many of you know, before I became a Labour Member of Parliament, I had an unusual career path for a politician, in that I spent quite a few years working in the business community. In other words, I was mainstreamed before I was institutionalised. Given that some of this time was spent working for the then Macraes Mining Company Limited, now Gold and Resource Developments NL, I feel that I may have a perspective on how things are seen, on both sides of the fence. In terms of public perception and esteem I am not sure which career option was the step up and which was the step down. So far what I have found very familiar, is that in both roles there is a gulf between the reality and the perception of that reality - a gulf that is both huge and hard to bridge. I think it is a point worth making here amongst another busy industry cluster, that we can all too easily get so embroiled in the day to day activities, that we lose sight of how this might look to those running on a different treadmill. I can still remember scratching my head at the beginning of some days, as I worked to get new mining projects started that I knew were going to bring real jobs and economic benefit to New Zealand, but ending the day feeling like I may instead have been proposing bringing back both strip mining and slavery. If I learnt one valuable lesson out of that time it was this: .... mining has become so publicly demonised on the road to ecological nirvana, that even attempting a lucid dialogue on mining issues, with some, is incredibly difficult.

Jan 1, 2000

Thermodynamics of Non-Cyanide Gold Solvents The present status of the raw material base in the gold industry requires specific ways to recover gold and silver from ores. Most gold is closely associated with sulfides which require flotation followed by pressure or bacterial oxidation. The next stages of processing usually require using expensive operations for the preparation of leaching. A lot of researchers want to find a new alternative solvent for the extraction of precious metals from these products. According to the authors, one of the best ways is to use sulfur-based solvents (thiosulfate, sulfite, and their various mixtures). Thermodynamics of gold and silver thiosulfate dilution are calculated for conditions: the concentration of Au - 200 mg/L, oxygen - 3.2 mg/L, thiosulfate - 79 mg/L, OH- - 170 mg/L. the general result is the possibility of process remains under standard conditions. (erAu = = 0.035 V, ?G298 = - 29.18 kJ/g-atom ??). Silver with thiosulfate forms two strong complexes: [AgS203]- and [Ag(S203)2]3-. ?G0 = -1027 kJ/mol. The complex [AgS203]- is less stable: ?G0 = 486 kJ/mol. It should be noted that despite the high stability of gold complexes, the sodium thiosulfate may decompose to sulfite and elemental sulfur during the process, especially when heating. Gold is slightly soluble in the sodium sulfite solution, however it forms the strong complex [Au(SO3)2]3-. Depending on the concentration of free S2O32-ions, silver with sodium sulfite forms three complexes: [AgSO3]-, [Ag(SO3)2]3- and [Ag(SO3)3]5-. The dissolution speed of gold in sodium sulfite solution may be in the same range as it is during cyanidation. In this case, a practical application of sulfite process can be also used, especially for the products containing free elemental sulfur. In conclusion, sulfite-thiosulfate gold lixiviants can be used for concentrates after pressure oxidation of the cakes.

Sep 13, 2010

Water Balancing in Mineral Processing - Issues and Opportunities

Sep 13, 2010

Lean Iron Ore Beneficiation in India

Sep 13, 2010

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 R G. Barker

This paper reviews the annual status of the New Zealand mining industry (metallic minerals and coal) including key aspects such as mineral production, mineral exploration expenditure, commodity price trends, key industry players, market activity and other significant commercial factors.   Strong commodity prices during 2006 have been underpinned by a number of key factors including US dollar weakness and emerging market demand, particularly from countries such as China and India. In real terms commodity prices have recovered significantly since 2002 and are currently at 20-year highs.   New Zealand exploration spending on metallic minerals (predominantly gold) is at a 15 year high driven by rising global commodity prices. New Zealand gold production in 2006 was about 340,000 oz and is expected to grow in 2007 as new mines at Frasers and Globe-Progress (Oceania Gold) and Favona (Newmont) come on stream. Gold production broadly lags 10 years behind exploration spending and exploration activity over the last five years remains well below that seen in the early 1980Æs. Expenditure on coal exploration shows a similar trend with strong growth from a low base over the last five years, reaching over $11 M in 2006. Total coal production in 2006 was 5.9 Mt, an increase of 10% on 2005 with imports from Indonesia adding a further $1.1 Mt.   Newmont and Oceana Gold are by far the largest public gold mining companies operating in New Zealand, although only Oceana Gold maintains a presence on the local stock exchange. Other metals explorers with New Zealand projects include a range of public-listed Juniors (market capitalisation less than NZ$50m) domiciled largely in New Zealand, Australia and/or Canada. Capital-raising on public markets directed towards New Zealand exploration is estimated at around NZ$12 M for 2006, the bulk of this coming via Glass EarthÆs NZ$10 M IPO on the NZAX in October.   The New Zealand Coal sector is dominated by the state-owned enterprise Solid Energy with around 80% market share by production. Other domestic coal competition remains limited, and includes the L&M Group, Pike River Coal, Eastern Corporation, and New Vale (acquired by Solid Energy in 2007). Pricing parity comes mainly from imported coal and global thermal coal prices have remained strong during 2006 at around US$45-55/t, driven by continued expansion in Chinese demand. Coking coal prices have eased 16% since 2005 to around US$98/t in 2007.   Although recent increases in exploration spending suggest a renaissance in the New Zealand minerals sector, long-run trends indicate that we have simply rebounded from a low base over the last five years and much work is still to be done to stimulate further growth in the mining industry to maintain minerals production at current levels. Key industry challenges include marketing exploration opportunities to local and overseas investors, building a critical mass of NZX-listed explorers and providing an internationally competitive environment to attract further capital and expertise.

Jan 1, 2007

Although AustraliaÆs coal mining industry is currently experiencing a pleasing period of price relief, long-term trends toward lower real prices will surely continue. Higher price levels attract expansion by existing operators and market entrance by new operators. History clearly demonstrates the relentless long-term march toward ever lower real prices. Therefore, the need for economic returns applies constant pressure to improve productivity. To be sustained, high productivity requires a systematic response based on a solid understanding of critical productivity determinants. The most powerful determinant of productivity is now widely understood to be workplace culture. Culture largely comprises a combination of behaviours, symbols and attitudes. This paper will examine and review scienceÆs latest discoveries in human behaviour. It will provide a proven, practical framework for understanding behaviour and applying this knowledge. Significantly, it will highlight why conventional approaches toward improving productivity often provide disappointing economic returns. The modern understanding of behaviour factors will cover coal face operations. More importantly, because executive and managerial levels in coal mining have significantly greater impact on industry and mine productivity the paper will concentrate on leadership. Particular emphasis will be placed on use of modern systems and in particular use of what are by far the most powerful drivers of behaviours û measurement, analysis and reporting systems. The paper and presentation will show how conventional systems rooted in antiquated American legislation from the early 1900s stifle productivity improvement and drive suboptimal and even counterproductive behaviours. These commonly used systems will be compared with accurate and effective modern methods for assessing performance to improve productivity. These principles are proven in all industries and effective application in mining will be highlighted. Actual results will be used to demonstrate practical approaches successfully applied in both metal and coal mining in Australia and overseas.

Jan 1, 2005

A Sun SPARCstation based computer network is utilised to store and process mining data at the Macraes Gold Mine. Techbase and Medsystem software running on the SunOS unix platform is used to generate all data plans, sections and other design data required on a daily basis to run the mining operation. The Macraes site is regarded as a fully integrated site where all geological, grade control, exploration, orebody modelling, resource estimation, pit optimisation and mine design is undertaken on site by MacraesÆ professional staff. The methodologies employed are regarded as æstate-of-the-artÆ where computerisation allows the rapid and efficient evaluation of large quantities of mining data by a handful of professional personnel. Ore reserves are estimated using an indicator kriging method and roving cone pit optimisation, a complex process that would not have been achievable in pre-computing days.

Jan 1, 1992

When it comes to structuring major mining contracts, the two most widely adopted formats are æmeasure and valueÆ and æcost-plusÆ. A problem with both of these formats is the difficultly of aligning the objectives of the mining company with those of the contractor to achieve mutually beneficial outcomes. An alternative contractual arrangement is for the mining company to enter into an Alliance arrangement with the contractor, linking remuneration to mine performance across a range of targets. These targets can change over time as operational requirements change.   The aims of this paper are to: +        outline alternative types of mining contracts, as well as their strengths and pitfalls; +        describe the philosophy behind the Alliance contract at Newmont Waihi GoldÆs Favona underground mine; and +        identify some of the keys to success and pitfalls to avoid when implementing an Alliance.

Jan 1, 2007

Mechanism of Modified Sodium Silicate on Fluorite Ore Flotation

Sep 13, 2010

A survey has been undertaken of the petrography of North Island greywackes with a particular focus on the occurrence in them of smectite (swelling clay) and chlorite, two minerals that are closely associated, chemically similar, and commonly interlayered with each other. Smectite is the mineral which is a major cause of greywacke aggregatesÆ poor performance. Smectite occurs in post-metamorphic shear zones and in surface weathering profiles over greywackes. This study focuses on the petrography of fresh greywacke rocks.   The occurrence and abundance of smectite and chlorite and their relationship in greywackes is largely a function of the chemistry of the sediment and the maximum temperature that the sediment has been subjected to during diagenesis and/or very low grade (anchizone) metamorphism. Rock chemistry, particularly total iron and MgO, determines the smectite and/or chlorite content in fine-grained greywackes (argillites and siltstones) but chemistry is less influential in sandstones, where at low grades of metamorphism much of the Fe and Mg of the rock is held in unreacted detrital minerals and the mineral constituents of lithic grains.   Four zones which represent different levels of diagenesis and very low grade metamorphism, based on the crystallinity of illite and chlorite in the greywackes, and the proportion of smectite interlayered with chlorite, have been mapped in the North Island. In the anchizone smectite does not appear as a discrete mineral, it is always interlayered with chlorite. In the upper anchizone chlorite contains approximately ten per cent of smectite interlayered with chlorite. In the lower anchizone about 30 per cent smectite can occur in chlorite.   In addition to the smectite and chlorite inherent in the greywackes as the result of the thermal overprint, smectite as a discrete mineral and smectite-chlorite interlayered minerals with high levels of smectite, occur in abundance on shear zone surfaces and in alteration zones adjacent to shear zones; these are the main contributers to the high levels of smectite recorded in many greywacke aggregates.

Jan 1, 2006

By R N. Robson, A B. Christie, I J. Graham

Strategy development by the minerals industry identified the fragmented management of mineral resources as a significant impediment to the discovery and development of New Zealand Æs mineral resources. The total gross value of New Zealand Æs potential resources of coal and minerals is estimated at about $400 billion, but their potential value is not being realised. The management of minerals is now largely under the control of 86 local authorities (regional and district councils) and the lack of recognition of the significance of the sector has lead to inconsistencies in the way minerals are managed. The industry strategy influenced science funding for minerals, with the result that the 'mineral wealth' component now includes research on making better use of resource data in minerals management. Initially this research has targeted Otago and Northland regions where a number of initiatives are now in progress.   In Otago the Regional Council has budgeted to contribute $1 million towards a regional geophysical survey to advance mineral exploration and the management of subsurface resources in the region, to work cooperatively towards improving public awareness of the significance of minerals to regional economic activity, and to better coordinate policy-making for minerals at regional and district levels.   Crown Minerals, and the Far North and Whangarei district councils are considering providing funding support for an economic study of the mineral potential of Northland, building on a mineral resource assessment undertaken by GNS Science. Enterprise Northland is adding minerals to their list of potential growth sectors, and is supporting the operation of a Northland region minerals focus group.   Regional development agencies and local authorities have shown that they are willing to include mineral resources in their development strategies and to provide for them in policies and plans when supplied with information and assisted with technical support.

Jan 1, 2006