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By Rokot M

In a little over three years, Chevron Niugini has built up a team of relatively young, hard working men and women, mostly Papua New Guineans, who spend most of their working days out among people in the Southern Highlands and Gulf Provinces who are directly affected by the Kutubu Petroleum Development Project. These are Land and Community Relations officers, or LACROs. They take on a huge responsibility, not only representing Chevron but also being friend, advisor and negotiator, frequently dispensers of medicines, and agricultural advice and more. When things go well, others get the praise, when things go wrong, LACROs are the martyrs. Just as the geologists who locate the oil, the drillers who find it, the engineers who design the facilities, the construction gangs who build them, the landowners who claim it, and the Government who monitor it, so are the LACROs part of a team.

Jan 1, 1991

By P Thompson, D Rose, S Yu, W Baum, R Zahn, D Meadows, G Hall

Opportunities to improve mill operations are often cited by mining companies and recognised in many concentrators spread throughout the world but are not always followed through. Copper-molybdenum concentrator operations are challenged by a continuously increasing list of detrimental factors. They include deteriorating ore characteristics and poor mineralogical information on deeper ores, water quality and availability, steel wear and increasing power costs. Rapidly declining productivity, sustainability and environmental factors, new taxes, mining industry global skill set shortages, to name but a few, must also be considered. The days of maximising value by just increasing production or simple cost cutting are fading and will not be sufficient for the future of more complex mineral processing operations and larger plants. As a result, FLSmidth’s Global Process Technology Group has launched a plant and process optimisation program based on mineralogical and metallurgical surveys.Copper-molybdenum concentrators of the future need a paradigm shift. Modelling and simulation tools alone are not the answer to complex mineralogical associations and larger scale equipment and operations. Detailed area by area review aimed at identifying process constraints in terms of equipment and operating practice in conjunction with robust diagnostic work, ie mineralogical and metallurgical characterisation, are mandatory for process optimisation. The navigational beacon, for all operations who want to remain competitive, will be ‘process efficiency’. Since the use of automated mineral analysers has become more readily available and reliable, mineralogical-metallurgical plant surveys have proven themselves as the most efficient tool for optimising plant performance.The following paper will illustrate how operations can move toward eliminating under-performing flow sheets, fixing run-away flotation conditions, maximising individual process equipment performance, preventing shortcuts in Bond work index testing which may cause the failure of comminution models and minimising costly and time-consuming ‘debottlenecking’. As previous plant surveys have shown, the net project cash flow can be increased by 50 to 200 per cent if a combination of robust ore characterisation and plant process mineralogy is performed. The combined plant survey approach has been demonstrated successfully in a multitude of operations. This includes the use of key ore types in concert with statistically sampled process streams, bench-scale metallurgical tests and automated mineral analysis on a size-by-size basis.CITATION:Meadows, D, Hall, G, Rose, D, Thompson, P, Baum, W, Zahn, R and Yu, S, 2014. Copper-molybdenum concentrator surveys using mineralogy and process benchmarking tools to improve overall plant performance, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 315–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By García B., Wolff E.

In Colombia, northeast of Antioquia, there is a gold deposit that has produced continuously since the middle of the XIX century, located within mining title RPP-140, property of Gran Colombia Gold Segovia (GCGS) since 2010. Mining materials are taken to the “María Dama” Processing Plant where 1500 tonnes of materials are processed daily. Before 2010, the previous owner of the mining title processed about 600 tpd and directly discharged almost all tailings, given that they had no capacity to put them into final deposits. El Chocho was conceived as a final tailings deposit to store the pulp produced by the processing plant; it was divided into two phases with two dams (upper dam and lower dam) given that the presence of illegal miners at the lower phase impeded a single dam design. A squatter impeded construction of the upper dam; so afterwards, starting at the higher end was necessary (owned by GCGS), building dam 1B to store tailings in pulp; after the squatter returned the lands to the owner (GCGS), construction of tailings dam 1A was required and thus complete construction of dam 1C or the upper dam. While all of this was happening, GCGS decided to acquire a 1500 tpd filter press which currently dehydrates tailings in order to take them to the valley controlled by dam 1A. Construction of dam 1A was designed following the containment wall model, made with geotextile tubes. These improvements generated reduced pressure on renewable natural resources because water is recirculated and less fresh water contributions are required; less pressure is placed on soil, flora and fauna because the area intervened for tailings storage will have a higher storage capacity and, as such, a longer useful life.

Jun 17, 2024

By S S. Kanchibotla, I Brunton

Most blast fragmentation models assume the rock mass properties, explosive properties and blast design variables to be constants and uniformly distributed within a blast. However, in reality all these input variables vary within a blast resulting in variation in the resulting fragmentation size distribution. A stochastic modelling approach is introduced in this paper to quantify this variation. This technique takes the input variables as statistical distributions rather than constants and through several thousand iterations, generates a statistical representation of the expected fragmentation resulting from a production blast. A case study of three production blasts from a large open pit mine are presented and the modelled fragmentation æenvelopeÆ shows good agreement with the fragmentation æenvelopeÆ estimated from Split image analysis. The various blast-related parameters influence different parts of the fragmentation distribution, eg rock strength and explosive velocity of detonation have most impact on the fines. The technique is used to identify the parameters that have the greatest influence on various size fractions. Such an analysis will be useful to direct resources to efficiently minimise the variation.

Jan 1, 2001

By G Cao, Y R. Cui, J X. Zhao, H P. Gui, G H. Wang, Z M. Wang, M M. Ren, B Li

Pyro-metallurgy is still the main process for lead production and a lot of lead direct smelting processes have been developed in recent years. All the processes will experience two steps in common. The first is the oxidisation of PbS to PbO and then reduction from PbO to Pb, furthermore, from ZnO to Zn. So, the composition of melts, especially the slag composition at reduction step change continuously. Up to now, there are few systematic results on the slag physical-chemical properties with its composition change. In this work, the typical lead direct smelting processes were analysed from theoretical and practical standpoints. The full-period slag composition and slag melting point change were compared. Especially, to the PbO and ZnO reduction steps, based on the full-period slag composition change, the slag properties were predicted. Based on dust composition and test results, the mechanism of Pb compound evaporation and its effect on practice and measurement of high PbO bearing slag physical-chemical property is discussed. It is suggested that to restrain the evaporation in practice and to obtain more accurate measurement results of physicochemical properties of smelting slag are the key problem not only to set high efficiency, energy saving process, but also to environmental pollution control.

Aug 21, 2024

By G S. Anderson, N W. McDonald

"The IsaMill™ was originally developed to address liberation issues at Mount Isa Mines (now Glencore) operations, McArthur River and Mount Isa in the early 1990s. Following on from the industrial success at those operations, the IsaMill™ was commercialised. In the year 2000, Kalgoorlie Consolidated Gold Mines (KCGM) became the first external user of the technology with a 1.1 MW M3000 IsaMill™ installed to supplement the roaster capacity at its Gidji Processing Plant. The IsaMill™ was used to ultra-fine grind about 10 t/h of pyrite flotation concentrate to 10–12 µm prior to gold cyanide leaching. Based on the success of the Gidji installation, another was installed at the processing plant at KCGM’s Fimiston operation in 2002 in a similar duty.In 2014, a 3 MW M10 000 IsaMill™ was selected to replace the roasters at Gidji as part of the A$98 M emissions reduction project. The mill was commissioned in April 2015 at the design 30 t/h, allowing the immediate shutdown of the two roasters. Replacement of roasting with ultra-fine grinding completely eliminated air emissions at Gidji while maintaining overall plant production rates.This paper details the history of the IsaMill™ at KCGM from the original M3000 to the latest M10 000. It covers the basis of the process selection, circuit design, operating and maintenance data.Citation:Anderson, G S and McDonald, N W, 2016. IsaMill™ at Kalgoorlie Consolidated Gold Mines - from the M3000 to the M10 000 and Replacement of the Roasters at Gidji Processing Plant, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 29–38 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

The International Symposium-cum-Workshop on Management andControl of High Gas Emissions and Outbursts in Underground CoalMines was held in Wollongong in March 1995. Coverage of high gasemissions was virtually confined to instantaneous outburst implications, essentially seam gas pre-drainage. Globally, instantaneous outbursts have been known for 150 years, andthe first Australian outburst occurred in 1895 and Australian occurrences and mines affected have increased since. Few significant coal producing countries are unaffected. The coals affected range in rank from lignites to anthracites. Geological disturbances are the most likely environments for occurrences. The most likely mining geometry is of virgin headings, with some occurrences on longwalls and in other situations. Widespread research into many aspects of the problem has yet to produce a generally accepted explanation. Explosive inducement is a well-known control. Apparently high advance rates increase face gassiness and create higher stress abutments, increasing proneness. The most popular preventive measure, pre-drainage of virgin coal ahead of faces has produced highly successful very long hole drilling performances but without the precision necessary for accurate geometric hole patterns, despite quite sophisticated drilling equipment and hole surveying instruments. For the future, more precise degasification is sought, even from the surface, together with rapid face coal gassiness assessments to confirm lowering below threshold values, as well as other proneness lowering measures, perhaps related to new heading and longwall geometries and to new equipment to provide them. But above all, safe management plans are required for each operation, to safeguard the miners and their working environments, and thus to protect underground coal mining from this mounting threatening problem.

Jan 1, 1997

By A K. Bhatnagar, S Saha, P Dixit, A K. Mukherjee, P Patra

TATA Steel’s R&D Division at Jamshedpur has developed a slime beneficiation process to recover iron values from iron ore slime. This process recovers iron ore concentrate containing 2.2 per cent alumina from a feed containing 7–10 per cent alumina. The reject generated from beneficiation of iron ore slime is treated as waste as the iron content in the reject is below 45 per cent. Effective utilisation of this waste is required for making the iron ore slime beneficiation process a zero-waste technology. In this connection several studies were made towards utilisation of slime waste. One of these studies revealed that slime waste can be used as a soil conditioner. Slime waste contains particles of size less than 10 micron and when these particles are mixed with soil in definite proportions, the porosity and the permeability of the mixture goes down. As a result, the water holding capacity (WHC) improves. This concept was evaluated through a series of tests at greenhouse level to optimise the soil to slime ratio. Finally, a pilot scale field trial was carried out over a period of three months using paddy rice as the crop. Three separate plots with compositions of: soil + organic matter comprising Farmyard Manure (FYM), (ii) soil and slime waste (2:1) + organic matter (FYM), and (iii) soil and slime waste (2:1) + organic matter (FYM) + Nitrogen, Phosphorus and Potassium (NPK) fertiliser were used for the pilot trial. The results showed a 20 per cent increase in the productivity of paddy rice for plot (ii) as compared to plot (i). This was due to the beneficial effect of slime waste in the soil. The addition of inorganic fertiliser such as NPK in the ratio of (4:2:1) further enhanced the productivity of paddy rice.

Sep 18, 2023

By P J. Fairfield

"This paper reflects on the author’s experiences in undertaking mining studies and reviewing mining projects and technical reports, particularly over the past five years, and the impact of recent changes in reporting standards and listing requirements pertaining to mining-related evaluation and valuation exercises. It also discusses contemporary changes in the expectations of the investment community and the implications for the role of the technical specialist in providing advice to such stakeholders.Not for the first time in history, the resources industry has experienced a significant downturn after a period of strong, sustained growth in line with the traditional view of the cyclical nature of commodity markets. The resource industry is currently faced with capital austerity in the wake of projects ‘failing’ (not delivering to expectations). In response, the industry has experienced changes in investment behaviour (slowing of investment) and an increasing regulatory burden as stakeholders seek a greater understanding of mining project risks.This paper discusses this response and uses case studies to highlight the key learnings (perhaps re-learnt) by the industry. It also discusses the challenges faced by technical specialists in communicating the results of technical and valuation studies to the investment community.As investors seek to take advantage of the current stage in the investment cycle, the key challenge of the technical specialist is to effectively communicate the uncertainty in technical assumptions, risks and opportunities that drive project value.CITATION:Fairfield, P J, 2016. Managing expectations – from buyer beware to buyer be aware, in Proceedings Project Evaluation 2016, pp 66–74 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By D van der Spuy, T Kewe, K Keet, N Moffatt, A P. Paine

The Blue Cube Mineral Quantifier Inline (MQi) instrument uses reflective light spectroscopy and advanced chemometrics to measure mineral or elemental grade in a slurry line. The instrument takes scans continuously and sends data to the DCS or PLC control system.Controlling the concentrate grades on a flotation circuit using low-frequency measurements can be difficult or impossible, especially on a circuit that has fast process dynamics. The ability to rapidly measure changes in grade makes it possible to continuously manipulate the flotation circuit operating parameters such as level, airflow and reagent addition set points to optimise plant performance throughout changing conditions.At Barrick’s Porgera mine in Papua New Guinea the flotation circuit feeds sulfide concentrate slurry to a pressure oxidation circuit. In order to maximise gold recovery in the flotation plant and increase performance in the pressure oxidation process, there is a stringent requirement to maintain a stable and optimum sulfur grade. The gold recovery is directly affected by the sulfur grade as most of the gold at Porgera is submicroscopic and associated with the sulfides (disseminated?pyrite).Porgera considered various points in the flotation circuit for installing Blue Cube analysers. This was part of a plant upgrade to improve process control. Due to budget constraints it was decided to initially only install one Blue Cube analyser on the final concentrate stream of the flotation circuit measuring sulfur, sulfides, gold and particle size. The accuracy of the calibration results were very good for all these properties. The sulfur measurement was used in an advanced control system to optimise and stabilise the grade. The paper presents comparisons between mineral grades determined using analytical laboratory analyses and the online Blue Cube data measurements, as well as benefits achieved by measuring grade online. An analysis of the plant data before and after installation of the Blue Cube and the advanced process control upgrade indicate that the flotation recovery increased by 1.98 per cent.CITATION:Kewe, T, Moffatt, N, Strobos, P, van der Spuy, D, Paine, A P and Keet, K, 2014. Evaluation of the Blue Cube MQi slurry analyser for application in an advanced control system for the optimisation of a gold sulfide flotation circuit, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 357–362 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By R Cooksey

The Globe-Progress Mine is an open pit gold mine that is part of the larger Reefton Goldfields deposit located on the West Coast of New Zealand. The regional geology comprises a series of north to south oriented fold structures that have undergone post-deformation mineralisation. The structural geology within the mine itself is more complex, with major shears hosting numerous high-grade mineralised quartz shoots and splays that have been historically mined.The selective mining of ore within the pit is challenging due to the orientations of the hanging wall and footwall areas of the main Globe shear zone, the lithologies of these areas which range from highly brecciated and sheared material to competent mineralised host rock, and in the hazards presented by the numerous old historic underground workings. The coordination of drilling, modelling and excavation of the ore requires careful planning to maximise recovery whilst operating with the pit design boundaries.Grade control packages are custom designed to reflect the orientation of the footwall and hanging wall mineralisation. The shear material in the footwall zone dips between 60° and 70° and requires angled drilling whereas the footwall mineralisation is contained in shallow dipping quartz veins sub parallel to bedding and can be vertically drilled to best intercept the mineralisation. Ore excavation is directed so that the contact between the footwall and hanging wall is mined in the correct direction so that any non-visual ore contacts can be safely mined and that the ore-waste dilution is reduced.The ongoing grade control and selective mining of the Globe Progress deposit continues to deliver high grade ore for processing by ensuring that waste and dilution of ore is reduced and that recovery is maximised.

Aug 22, 2011

By PáDeáBosscher, A Bruwier, M Weidenbach, C Philippe, T Ly, A Van Den Bosch

In the mining business the cost of grinding media represents up to 40 per cent of the total milling cost and therefore grinding media optimisation has a direct impact on the concentratorsÆ bottom line. In the process of optimising grinding media alloys, Magotteaux developed its own methodology which consists of a series of analyses, tests, calculations and evaluations and assist the concentrator in optimising their processes.This paper presents the Prominent Hill case study where this methodology has been applied on both the secondary ball mill and regrind IsaMill«.The analysis of the wear conditions in the secondary ball mill allows Magotteaux to select a series of grinding media alloys to be tested to reduce grinding media consumption. By marking these different grinding media types with a unique drilling pattern, one can quantify the relative wear performance and cost effectiveness of each grinding media type within the same milling environment. After selecting the most economical grinding media composition a full scale industrial trial, involving topping up the selected grinding media is carried out and the media wear performance closely monitored and analysed.For stirred grinding mills, suppliers propose different grinding media, mainly ceramic beads, with specific properties and cost. Therefore the concentratorsÆ choice is a compromise between grinding efficiency, wear resistance and cost. The selection of the correct grinding media for stirred milling and the assessment procedure will be presented in this paper. The test results of the new stirred grinding media type in the regrind IsaMill« at Prominent Hill are presented and analysed.CITATION:Weidenbach, M, Van Den Bosch, A, Bruwier, A, Ly, T, De Bosscher, P and Philippe, C, 2012. Forging ahead - A collaboration between the OZ Minerals Prominent Hill Concentrator and Magotteaux to improve plant performance, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 105-110 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By P Christen

The Ernest Henry Copper gold mine situated in North West Queensland, Australia, is owned and operated by Xstrata Copper. Currently the open pit produces 11 Mtpa of ore. With open pit mining ceasing in mid 2011 development has begun on an underground sublevel cave mine to extend the life of the operation by another 12 years. When completed the open pit will be 530 m deep and 1.5 km in diameter. The orebody dips at approximately 45° and has been outlined a further 450 m below the base of the pit. This provides some challenges for the Ernest Henry underground mine which is designed to initially truck development and production ore from the end of the pit until a hoisting shaft is commissioned in 2013. Production will then increase to 5.0 Mtpa on its way to an ultimate rate of 6.0 Mtpa in 2016.This paper will focus on the capital development and infrastructure requirements for the underground mine. Areas covered include mine accesses, ore handling system, accommodations for the dip of the orebody, primary ventilation design, dewatering systems and selection of an underground workshop over surface only maintenance.Discussions include the complications arising due to the mine being located directly below a large open pit and the combination of first principle cost analysis and risk assessment which has been used to safely optimise the feasibility study designs.

Mar 21, 2011

By Hoffmann CF

Thermal conditions at depths of several k.i'-.r.,etres in hydrothermal systems are a major (actor controlling gold transport into the epithermal environment. Understanding of the coupling of thermal, metal and ligand (HZZ S) sources in the root zones of hydrothermal systems therefore becomes important for the application of tectonic and igneous petrochem- ical studies to regional scale precious metal exploration. The evaluation of favourable conditions in this source zone and application to explor- ation rests on a detailed knowledge of the gases, H2S, CO2 hydrocarbons and other trace components preserved in fluid inclusions. Recent developments in analytical techniques now permit examination of these components and the recognition of complex hydrocarbons in rluid inclusions from epithermal and other lydrothermal systems appears promising for ieoosit-source correlation.

Jan 1, 1987

By N McIntyre, M Edraki, K R. Jain

From the very early stages of a mining project, there is a requirement to predict the chemistry of potential drainages from various waste storage facilities. However, using relative masses to scale chemical loads measured by laboratory kinetic tests, such as humidity cells, to a full-scale mine waste facility will lead to concentration predictions that are unrealistically high for many dissolved constituents. Scaling factors developed by various procedures indicate that laboratory rates may range anywhere from two to eight times (Drever and Clow, 1995) to 100 to 1000 times faster than field rates (Malmstrom et al, 2000; Smith and Beckie, 2003; Ritchie, 1994). This contribution will use previous works and secondary data to discuss the significance of scale in water quality predictions. It will also present primary experimental geochemical and numerical data from a column leaching study on coal spoils to discuss potential applications of mesoscale leaching tests in bridging the gap between bench-top tests and field scale trials.

Aug 2, 2023

By M Scoble, C Hughes, M Roberts

At 14 per cent, the representation of women working in the mining industry is the lowest among primary industry categories in Canada. Despite an increase in research and industry commitment to advance and retain women in the mining industry, the gender gap in mining organisations persists.This paper is based upon a recent Canadian survey of 163 highly qualified women (HQW) working in the mining sector. For the purpose of this research, HQW were defined as women with a BachelorÆs degree or higher. This research sought to identify career progression and retention patterns of women who in theory have the educational qualifications to advance into positions of leadership in mining operations. We considered why womenÆs advancement in mining organisations has stalled; examined the career development pathways of HQW; and investigated the interactions of mining workplace culture on HQWÆs career development and retention within the Canadian mining industry. Results?indicated two distinct career pathway trends for HQW. æThe specialistÆ; a career characterised by multiple professional scientific and technical positions, and æthe corporateÆ; a career characterised by professional administrative roles and roles in mid-level management. It was found that neither æcorporatesÆ nor æspecialistsÆ systematically progressed into senior management and executive roles. These findings suggest that HQWÆs careers in mining are stalled, despite a strong indication by respondents of interest in their professional career advancement. With regards to?workplace?culture, respondents indicated that blatant forms of gender discrim-ination have been reduced in mining workplaces; however, exclusion from informal networks, implicit bias and subtler forms of workplace discrimination persist. Consistent with previous mining sector research, improving work-life balance, work flexibility and mentorship were found as key drivers for HQW to advance and remain in the industry.CITATION:Hughes, C, Scoble, M and Roberts, M, 2012. Where are the women? Highly qualified women in the mining industry, in Proceedings International Mine Management 2012, pp 23-34 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By D Reid

Run-out analyses of tailings storage facilities are typically undertaken using methods based on rheological theory. These are reasonable techniques to model the behaviour of tailings that, through significant run-out and possibly mixing with supernatant water, are generally acting in a fluidised manner. Such modelling often follows on from two-dimensional continuum analysis models where, if failure is predicted, grid failure often occurs when deformations begin to increase. This results in a disconnect between the prediction of failure and the modelling of the potential extent of the failure.Recently, rezoning methods have been incorporated into commercially available two-dimensional soil mechanics deformation codes. Rezoning techniques enable large deformations to be modelled within a two-dimensional continuum analysis framework; however, while promising, the use of such tools is not yet widespread, and a consensus is yet to develop on how they should be applied to tailings dam run-out modelling.This paper uses FLAC rezoning techniques to model the flow behaviour of two historic tailings dam failures. The purpose of these analyses is to critically assess the performance of rezoning against some available historic failures. The required data to undertake such an analysis is outlined, along with the inherent limitations and assumptions required. Parametric analyses are outlined to address some of these issues. In general, the analyses undertaken underestimated the flow distance observed in the historic failures by varying degrees; however, in some instances, the analysis reasonably reproduced the qualitative shape of the initial failure zone. A variety of potential reasons for the discrepancy between historical observations and the models undertaken are provided.CITATION:Reid, D, 2015. The use of rezoning techniques to model historic tailings failures, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 201–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By I M. Howard

With the bell-less top (BLT) charging system replacing the centuries old double bell charging method, the furnace efficiency has been greatly improved together with considerable reduction in the furnace down time and operational problems. But still there are many draw-backs which need further attention to achieve better efficiency and operational effectiveness. The performance and operational problems of the BLTs have been highlighted and possible solutions to overcome some of the major problems are discussed.

Jan 1, 1999

DML Resources Limited - Mining Division produced over 50 000 oz of alluvial gold in the 1995 - 1996 year from five operations located in the West Coast and Otago Regions on the South Island of New Zealand. DML Resources Limited - Mining Division have a twenty year history of alluvial gold mining development in New Zealand. Recent expansions have seen the establishment of two operations in Chile whilst exploration continues in Bolivia, Peru and Argentina. The overseas growth is based on a stable production base in New Zealand focussed on the West Coast and Southland/Otago present and future operations. DML Resources consider that the mining potential in the Arahura Valley on the West coast will be fundamental to their New Zealand operations for some time. Collectively the plants operating in this catchment are referred to as the Poutini Project. Recent and late Pleistocene gravels derived from the erosion of the Alpine Schists running parallel to the Alpine Fault located on the Pacific/Australian Plant boundary are thought to be the sources of the alluvial gold in the Arahura and adjacent catchments. These gravels have been extensively mined for the past 130 years yielding some six million ounces over this period. Production from the Poutini Project started in 1989 and stood at approximately 35 000 oz for the 1995 - 1996 year. This production was split among three plants each working different areas of the deposit. Recovery techniques from each of the plants are fundamentally the same. Gravels are fed to a floating treatment plant where, following screening, the gold is recovered using jig plants and knudsen bowls. Overburden to wash stripping ratios vary between zero and seven to one with plants treating between 80 and 250 cubic metres per hour. Restoration of the land following mining is undertaken progressively. All land in the Poutini Project area mined to date has been restored to a standard suitable for dairy farming purposes. The Poutini Project is a cooperative venture between the Maori landowners and DML Resources Ltd. The Arahura River has particular cultural significance to the Maori as it is the source of the much valued greenstone or pounamu a type of jade valued for jewellery and tools. The Poutini Agreement was signed in 1989 setting out the role of each party in the mining of the Arahura and adjacent lands. Current exploration and development should extend the resource to allow mining to continue on the Poutini project for an additional three to five years at current gold prices. Production within new Zealand beyond this point may be compromised by increasing difficulty in gaining access to prospective areas within New Zealand, lowered margins due to high New Zealand dollar exchange rates and the overall lowering of alluvial headgrades throughout the West Coast and Otago/Southland regions. To counter these effects DML has continued to improve on operational efficiency and performance monitoring to optimise the mining practices used. This paper detains the background to the Poutini Project, the geology, plant and equipment used together with descriptions of the current mining methods employed.

Jan 1, 1996

The ERMS Process was developed during four years of testwork by Austpac Gold NL to overcome the severe metallurgical problems of the ilmenite atWestport, in the South Island. These deposits have been known for about one hundred years. They were originally mined for gold, and only later attracted attention as a possible source of titanium minerals.   The resource is of world scale and may exceed 20 million tonnes of contained ilmenite. Similar deposits occur at Barrytown further south and together these areas would constitute an important opportunity for export-oriented mineral development, if a viable beneficiation technology were available. Further processing is essential, as the composition of the ilmenite is well below market specifications.

Jan 1, 1993