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The 115-year history of the Hall-Heroult process for production of aluminium has been characterised by a sustained technology-driven improvement in costs and productivity. In the past decade the industry has effectively transferred best practice into older technology with improvements through computer control of the process, and redesign of cell linings using computer modelling . Incremental development is now at the point where diminishing returns will apply for further technical improvement effort however, until the gap between technical limits and current best practice is addressed through major process redesign. The process remains a long way short of its technical limits in energy consumption, carbon anode consumption, cell life and product purity. Investment cost in new capacity is very high, supporting the retention of older and less efficient technology and hence limiting the application of best practice in environmental performance and occupational health exposure. The industry is a major emitter of greenhouse gases yet the process has the potential to release oxygen as the primary waste. All of the above issues will be addressed in the new century, but only through commitment to the necessary long-term research and development that is required to achieve a redesign of the process.

Jan 1, 2000

Brunswick Mine, one of the largest underground zinc mines in the world, is scheduled to close in 2010 after almost half a century of production. All mines eventually close; some suddenly as a result of unsustainable economic or technical conditions and others, as in our case, as a result of the depletion of the orebody. When the mine is the most significant employer and an economic driver in the region, it is key that the closure is handled in a planned, communicated, well-executed fashion. The following paper documents strategies, plans and activities that are currently taking place in order to ensure a seamless closure that satisfies all stakeholders including employees, management, regulatory bodies and the public. It is an important deliverable for the company that the good will, credibility and reputation that has been built up over the years is sustained throughout the closure process and beyond. A life of mine labour agreement with the unionised workforce, staff retention and recruiting programs, regulatory closure plans, communications and transition adjustment activities will be discussed. The use of a stage-gate style project management tool analysing the risks and key deliverables will be highlighted. It is hoped that the concepts and approaches discussed here may be of value to other operations that will be faced with closure, and its inherent challenges, in the not too distant future.

Jan 1, 2006

By J V. Lawless

Two types of low sulphidation epithermal deposits that have different gangue mineralogies and ore shoot geometries are recognised. One has laterally near-continuous ore shoots over a significant vertical interval that consist of quartz, chalcedony, pyrite, minor base metal sulphides and adularia, with electrum. The other type of deposit has discrete near-vertical ore shoots of a lesser vertical extent, that consist of quartz, pyrite, base metal sulphides, sulphosalts, electrum and in their upper parts barite, which are enclosed in veins of earlier quartz. The gold mineralisation in both deposit types is considered to be a co-precipitate of pyrite, with that in the first type of deposit produced by prolonged boiling in an upflow of a hydrothermal system (Upflow Deposits); an example is Waihi in New Zealand. The other type is produced by mixing, a deep water primed for gold deposition by prior limited boiling, with an iron-bearing oxidised condensate of the steam released by the boiling, in an outflow of a hydrothermal system (Outflow Deposits); an example is Thames in New Zealand. Early recognition of these different types of deposits can be used to develop mineralisation models of predictive value on which to focus exploration drilling. Early recognition of an Upflow Deposit promotes an extensive program to delineate the extension of the main ore shoot. In contrast recognition of an Outflow Deposit requires a more intensive approach to find individual ore shoots which, although smaller than those found in Upflow Deposits, may be high-grade, particularly if there is earlier mineralisation present to act as a protore.

Jan 1, 1999

I am wearing two hats today. When the invitations went out to participate in this forum, two were received in the head office of the Department of Lands and Survey - one addressed to the Director-General of Lands and one to the Chairman of the National Parks Authority. It seemed logical that as the department is responsible to the Government for the administration of the National Parks Act 1952, we should respond by providing one speaker to cover both the department's interests and those of the National Parks Authority. I hope, however, that this will not blur the clear distinction which exists in the context of the mineral industry between Crown land on the one hand administered by the department for the statutory Land Settlement Board and national parks and allied reserves on the other hand which are the responsibility of the National Parks Authority.

Jan 1, 1976

In the estimation of reserves the known values of the variables of interest from surrounding drill holes are used to compute or estimate the unknown value of the orebody over a given region or at a given point of interest. The classical means of doing this are: 1. The Polygonal Method û where the region is divided into polygons centred on bore holes, each variable is then assumed to have constant value over each polygon. 2. Inverse distance methods, where the variable is assumed to vary linearly with the distance between the known values of the drill holes. 3. Inverse distance squared method û a quadratic variation is assumed for the variables between the bore holes.

Jan 1, 1983

By Noller B. N, McGill R. A

The Alligator Rivers Region has been the scene of one of Australia's most intensive environmental monitoring efforts since the current generation of uranium mining was mooted in the 1970s. Prior to mining, the local environment and the nature of potential impacts were not well known. The initial monitoring programs therefore included large baseline characterisation and research components. After some 15 years, water, soil and sediment monitoring programs have been reduced to a fraction of their early size, as the mining and natural systems became better known and characterised, and the actual nature of the environmental impacts were established. Modem techniques allow much more rapid and thorough identification of chemical species and elements of concern, allowing much more focused monitoring programs to be designed. In the 1980s data collection was emphasised at the expense of interpretation, and monitoring programs were maintained at much higher levels than were in fact required. It is now clear that investigations are important and should be distinguished from monitoring programs, and that the timely interpretation of investigations and implementation of recommendations can greatly reduce the effort and expense that can be involved in a monitoring program. Monitoring programs based on a sound understanding of potential environmental impact may then be efficient and cost-effective, yet provide sufficient information to assess the environmental impact of mining, guide further environmental protection measures when problems are detected, and demonstrate compliance with regulatory requirements.

Jan 1, 1994

By J E. Askew

The rapid expansion of gold production in Australia over the last five years can be attributed in part to the development of selective mining techniques for open pit gold operations. These techniques allow an increase in head grade with a substantial reduction in mill feed tonnage, as compared with traditional open pit designs. As a result, the capital requirements for mine development and mill construction are substantially reduced, improving the cash flow profile in the early years of operations. To put such a design into effect, the emphasis of mine production must be on producing gold, rather than tonnes of ore. Mine planning at Martha Hill has been based on such a philosophy. After the quantity and grade of the resource had been defined, the exploration programme was increasingly concerned with the local variability of ore zones, and with determining the position of values within broad ore-definition envelopes. The purpose of this work has been to allow the prediction of the tonnages and grades achievable from various levels of the pit when mining selectively using hydraulic excavators. The studies have so far indicated that the Martha Hill deposit can be mined selectively during the early years of production. The additional costs for detailed grade control and a reduced digging efficiency are more than compensated by the exclusion from the mill feed of much valueless material.

Jan 1, 1986

A simulation and animation model was constructed for the Stockton Coal Mine. This mine is located in the north western area of the South Island of New Zealand. This model was used to study the optimum size of the stockpile areas whilst achieving the correct product coal qualities. The model evaluated the impact on stockpile size and product coal qualities for both bulk and selective mining. The effect of modifying the amount of known clean coal quality was also investigated. The software used was GPSS/H« for the simulation and Proof Professional« for the animation. From the study, it was recommended to incorporate selective mining in future studies. The shipping plan needed to be modified for a better correlation between coal production levels, in situ coal resources and wash plant capacity.

Dec 6, 2010

I have spent most of the past 35 years working as an economic geologist in the area of exploration and development of base and precious metals. Most of this period has been as an employee of Trans-National-Corporations (TNC's). I presently act as a consulting geologist to a joint venture company, bringing together two such TNC's: Anglo American Corporation and affiliated companies De Beers (Diamonds) and Minorco (Metals mining outside of Southern Africa), and Normandy Mining Limited ofAustralia. Normandy is presently through its gold arm PosGold, Australia's largest gold miner and Anglo American can claim to be the world's largest gold company producing over 280 tonnes of gold a year, more than twice its nearest rival Gold Fields of South Africa. In addressing this topic, the role that Government can, and should play in mineral development, I will be drawing heavily on some examples from these and other TNC's experience in recent offshore mining investment.

Jan 1, 1995

The mining industry continues to faces significant challenges due to increasing resource constraints (quality of ore bodies, water, energy, human resources) and increasing license to operate requirements (safety, health, environment, location) from society, employees and shareholders. Technology advancements and hence research are necessary to ensure that the industry remains viable in this changing environment. Collaborative research is an important part of a company's research portfolio and offers the opportunity for the industry to work on generic issues that it is facing. Obvious benefits include the reduced cost to individual companies by sharing the costs, the opportunity to leverage government funding and the opportunity to conduct longer term projects resulting in skills development (PhD and MSc). Limitations of collaborative research include the reduced focus on company specific issues and the loss of competitive advantage from owning the outcomes of the research. The challenge for researchers and research managers is for them to demonstrate the value derived from longer term, pre-competitive collaborative research. The competitive advantage is not necessarily derived only from the outcomes of the research but rather from the company's ability to direct the research, translate the generic research outcomes to address company specific issues and to implement improvements at its operations. Implementation remains the greatest challenge. In this paper, case studies of selected collaborative research projects are presented to demonstrate key success factors required for implementation of research outcomes. This is an ABSTRACT ONLY. A full-length paper was not prepared for this presentation.

Sep 13, 2010

By K B. Quast, A Schuurmans

Laboratory batch rod and ball milling tests were conducted on samples of Heavy Medium Separator (HMS) sinks from Renison Limited. The effects of mill rotation speed, rod volume and ball size on the resulting product size distribution were investigated. Between 48 and 69 per cent of critical speed, the product sizing distribution curves remained very similar, with a finer grind resulting from increasing the speed of rotation at constant grind time. Increasing the rod loading from ten to 53 per cent by volume caused the product size to become finer and more closely sized with a transition occurring at approximately 29 per cent. This was interpreted as a change of dominant grinding mechanism from abrasion to impact. No preferential grinding of the cassiterite was observed. The effect of increasing ball size at constant charge weight was to preferentially grind the coarser particles and generate more intermediate sized particles, whereas the product from a mixed ball charge gave a distribution similar to that obtained when a charge containing only smaller balls was used.

Jan 1, 1998

Study on Mineral Processing Technology for a Refractory Iron Ore

Sep 13, 2010

By R Miller, D Hawcroft

The business environment is never still and there has been enormous change in demand, technology and opportunity during the last decade. In order to succeed it is necessary for organisations to change the way work is planned, scheduled and carried out. This is necessary just to survive over time. The success or failure of the business is strongly influenced by people; the way they work, the way they are guided and their feelings about being part of both a team, as well as an organisation. Our Sustainable Integrated Management System (SIMS) philosophy is built on the belief that people want to be constructive and creative and it is their environment and working relationships that influence how their energies are directed.

Jan 1, 2000

By Z U Bajwah

During the Palaeoproterozoic, a large number of granitic intrusions were emplaced in the various parts of the Pine Creek Geosyncline (PCG). In the central region, the granitic magmatism is represented either by the coalesced mass, eg the Cullen Batholith, or individual plutons such as the Mount Bundey Granite which together with the Mount Goyder Syenite intrude the metasedimentary strata, causing wide spread contact aureoles. Some of these granitic intrusions are temporally and genetically related to gold (and less commonly base-metals) mineralisation present in the adjacent metasediments. These plutons are characterised by the presence of biotite and homblende which appear late in the paragenetic sequence. Electron microprobe analyses of biotite and homblende show that these minerals are poorly to moderately zoned. Biotites are characterised by a decrease in Fe/(Fe + Mg) ratios when plotted against AIVI. Similarly a modest decrease in Ti from centre to the margins of the biotite crystals has also been observed. Furthermore, an increase in Mg/(Mg + EFe) ratios from centre to the margins as well as in mafic to felsic rocks is also apparent. On the other hand, homblendes from the granitic bodies display less well marked trends and are poorly zoned. However, they show systematic increases in Mg/(Mg + EFe) ratios, and decreases in Fe, Al"' and Fe/(Fe + Mg) ratios, when plotted against Si. Magnetic susceptibility measurements on powdered samples of the plutons give results characterised by high values ranging from 0.8 x 10-4 to 2.0 x 10-3 emu/g which place the granites in magnetite- series field. This indicates that the oxidation state of the magma was high during crystallisation. The range of chemical compositions of the mafic phases indicates a rise in the oxidation state of the magma as it progressively became saturated in H20-volatiles and other metals, not partitioned into the earlier crystallised phases in the final stages of magma consolidation. These variations in chemical compositions also indicate that initially fOz was high and became progressively higher during fractional crystallisation of magmas; this subsequently led to the emanation of hydrothermal fluids responsible for the mineralisation in the adjacent metasediments.

Jan 1, 1994

By A B. Christie

The Institute of Geological and Nuclear Sciences' Mineral Resources Programme is currently carrying out research under two major projects:   HAREM (Hauraki Andesite Rhyolite Epithennal Mineralisation) The Hauraki Goldfield lies within a belt of andesite-dacite-rhyolite volcanics of Miocene Pliocene age which is underlain by a basement of Mesozoic greywacke. It contains some 50 separate epithermal gold deposits and is a world-class gold and silver producer. The HAREM project is aimed at improving models of the epithermal gold mineralisation, and to better understand the processes and controls of origin, transport and deposition of the gold.   MARGO - (Marlborough Gold) The MARGO project is aimed at determining the geological factors that controlled the formation of the Mesozoic mesothermal gold-antimony-tungsten deposits in the Marlborough Schist belt. Following reconnaissance work on 12 deposits, our current work is concentrated on deposits in the Wakamarina valley.

Jan 1, 1994

A New Online Detection Method for Arsenic Minerals in Process Streams

Sep 13, 2010

If you are to be and remain competitive in the mining industry, it is vital that your company management systems are efficient. An integral part of today's competition in a ruthless market is to keep internal costs to a minimum. Integrating our core and parallel management systems is becoming an essential strategy to ensure efficiencies are maintained to the highest level, allowing the maximisation of profits, and to maintain that leadership status within our industry. The uniquely designed Integrated Management Process provides the path to develop, implement, and monitor an Integrated Management System in a simple but highly efficient and effective manner.

Jan 1, 1997

Management of Mining Wastes in European Union and Developments in Turkey

Sep 13, 2010

By E Ben-Awuah

Mine planning is the backbone of all mining enterprises and determines the profitability or otherwise of any mining investment. Providing high quality ore and tailings containment at the right time are the main drivers in oil sands mining. Recent environmental and regulatory requirements also makes waste management an integral part of mine planning in the oil sands industry (Directive 074). Due to the limitation of lease area, the pit phase advancement in oil sands mining is carried out simultaneously with the construction of tailings dykes in the mined out areas of the pit. These in-pit dykes are constructed to hold tailings that are produced during the processing of the oil sands ore after an initial external tailings facility. Most of the materials used in constructing these in-pit and ex-pit dykes come from the oil sands mining operation, making it necessary to have a plan for supplying the dyke material. The research problem here is categorised as: determining the order of extraction of ore, dyke material and waste to be removed from a predefined ultimate pit limit over the mine life that maximises the net present value of the operation û a strategic schedule; anddetermining the destination of dyke material that minimises construction cost depending on the construction requirements of the various dykes as per their designs û an operational schedule. There has been developed, implemented and verified a theoretical optimisation framework based on mixed integer goal programming (MIGP) to address the oil sands long-term production scheduling and waste management problem. The research introduced the development of multiple material types and multiple destination optimisation techniques using MIGP in the context of mine planning. This study presents an integration of mixed integer programming and goal programming in solving large-scale mine planning optimisation problems using clustering and pushback techniques.

Sep 26, 2011

By P Phelan

This paper presents the general background and development of raiseboring followed by case histories of circumstances where raiseboring equipment was used in a different manner to normal. Each project has been summarised for this paper as described below: Case 1: Retrieval of a 40 tonne truck from a stope at Peak Gold Mines. Case 2: Slot raising - Conventional, Uphole and Downhole Reaming at Peak Gold Mines. Case 3: Reamer recovery by Downreaming at Tower Colliery. Case 4: The importance of Mucking Raisebore Holes û Thalanga Project. Case 5: Pilot Drilling Dewatering Holes at Beaconsfield Gold Mines. Case 6: Low angle æcut offsÆ in vein at Telfer Gold Mine.

Jan 1, 1998