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By Schmincke H-U

The Pleistocene basanite-tephrite Rothenberg cone complex was built by an alter- nation of strombolian and phreatomagmatic phases of explosive eruption. Two main centres, on a one km long NNE-trending fissure, were active during its construction. The strombolian deposits from three discrete facies corresponding to the crater-fill and inner wall and outer wall environments on the cone. The outer wall facies consists of an alternation of 1. 'normal' coarse-grained, relatively well- sorted lapilli and bomb beds, and 2. finer-grained poorly-sorted lapilli beds. Evidence suggests that the former was pro- duced by open-vent lava fountaining, with balanced magma supply and discharge rates, and the latter are the products of eruptions during partial blockage of the vent, by collapse of wall-rock, and formation of a degassed crust on the magma. The resulting explosions there- fore ejected a mixture of fresh actively ves- iculating magma, older partially degassed lava and material recycled from the wall of the cones. The phreatomagmatic deposits are an alternation of moderately-sorted fall beds and thinner ash-rich pyroclastic surge and rain-flushed units. The clast populations are much more diverse than strombolian ones, including abundant wall rock fragments from 0-100 m depth. The juvenile (magmatic) particles range from highly vesicular scoria to dense 'bread-crusted' clasts, and contain abundant small wall rock inclusions. The phreatomagmatic phases are products of explosive interaction of small batches of magma with shallow groundwater. Vesiculation of this magma played a small but significant role throughout the fragmentation.

Jan 1, 1987

By K Brand, M J. Ind, M Rynhoud

Water management at a tailings storage facility (TSF) presents one of the major risks to the safe performance of the facility. International and domestic dam safety guidelines assess a dam’s hazard category based on the consequences of a dam failure and the subsequent downstream damage to the environment and communities.Often a rigorous risk assessment is undertaken during the design stages to identify and control hazards associated with water management through life-of-mine (LOM) phases. However, as experienced during the recent downturn in commodity prices, early closure of a mine can occur rapidly and unexpectedly. Although guidelines such as the Australian National Committee on Large Dams Incorporated (ANCOLD) recommend that one of the key objectives of integrated TSF planning is to ‘plan all phases of a tailing dam’s life to ensure adequate storage capacity including early closure ’ (Australian National Committee on Large Dams Incorporated (ANCOLD), 2012) this is often overlooked by owners who are focused on fulfilling the mine’s potential and early closure is not on their radar.CITATION:Ind, M J, Rynhoud, M and Brand, K, 2016. Life-of-mine spillway strategy – managing risk associated with surface water at a tailings storage facility, in Proceedings Life-of-Mine 2016 Conference, pp 209–211 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

Laboratory scale simulation experiments show that the adsorption capacity of Au(CN)Z- on activated carbon in the presence of organic plant contaminants is dependent on the particle size of the carbon. This observation suggests that fine carbon in a CIP contactor can protect coarse CIP carbon from fouling in a dirty CIP plant. A preliminary test of this concept was made using fine lignite coal as the organic scavenger in the presence of the CIP carbon Calgon GRC22 in an alkaline cyanide solution containing Teric 401, sodium ethyl xanthate and kerosene.

Jan 1, 1991

In recent years a large number of Horizontal Belt Filters have been installed in the Australian mining and chemical industries. This paper deals briefly with the general background and advantages leading to the selection of this type of filter. Several different applications are described and particular reference is given to the simplification of the fines treatment circuit at the South Bulli Coal Washery.

Jan 1, 1989

By Smith JW

Studies of 13C/12C ratios of carbon dioxide in seam gases and in secondary calcites show that 1. In mines prone to carbon dioxide outbursting, the source of this gas is external to the coal. 2. Faults draining reservoirs of magmatic or primary carbon dioxide, rather than intrusives, are the most likely points of entry of carbon dioxide into mines. 3. The higher the concentration of carbon dioxide in seam gas and the wetter the mine, the lower the likelihood of secondary calcite occurring as a filling in cleats, fractures etc. 4. A -role played by carbon dioxide in promoting outbursting may be the conversion of calcite to soluble bicarbonate, the removal of this in mine water and the subsequent weakening of the resistance of the bulk coal to stress.

Jan 1, 1980

By Scott A

The object of most blasting operations is to destroy the insitu structure of the rock mass so that mechanical equipment can efficiently excavate the rock fragments. In achieving this objective the blasting engineer is also concerned with minimising damage to the adjacent rock which forms the mine structure relied upon to provide support. Damage to this "structural" rock is undesirable but usually occurs as a result of two distinct processes: ò readjustment of stresses around the excavation as a result of the mining process itself ò impact of vibration and high pressure gases from blasting operations. Gross damage to mine structures from either cause is observed as visible alteration to the appearance of the rock structure in the form of cracking, slabbing, back or over break and visible displacement. Recent work at the Julius Kruttschnitt Mineral Research Centre (JKMRC) has shown that significant reduction in the strength of a rock mass can take place well before the onset of these obvious signs of damage. It has been demonstrated that the effect of blast damage on the behaviour of the rock mass can be many times more prominent than the effect of stress redistribution. This offers the blast design engineer the opportunity to significantly reduce blast induced damage to rock structure by modifying blasting practices. This paper introduces the current JKMRC postgraduate research projects investigating the evaluation and control of blast damage.

Jan 1, 1990

By G Stephenson, G MacDonald, A Yeomans, S Sinclair, V Knott

Rio Tinto has actively committed to progressive reclamation, concurrent with commercial operations, at its Diavik Diamond Mine. The most significant piece of progressive reclamation undertaken at Diavik to date has been the construction of an engineered thermal rock cover for the mine’s largest waste rock storage area. This 80-metre-tall and 2000-metre-long area is known as the Waste Rock Storage Area – North Country Rock Pile (WRSA-NCRP) and contains the operationally segregated potentially acid-generating waste rock mined over the last 20 years. As part of the mine plan, an opportunity was recognised where a limited 1.5 per cent of the WRSANCRP surface area was required for storage of the balance of life-of-mine generated waste rock and a decision was made to advance the closure design almost a decade ahead of final closure. With over 12 860 000 tonnes of material placed and 57 443 dozer hours logged since cover construction, progressive reclamation on the WRSA-NCRP is scheduled to be complete in mid-2023, three years before planned cessation of commercial operations in 2026. The progressive closure of the WRSA-NCRP demonstrates Rio Tinto’s commitment to not only closure, but modern best practices with integrated mine closure. Over the past seven years, Diavik has overcome multiple implementation hurdles for this project including the psychology of operational standby, the financial mechanisms required to support closure, working within the constraints of a mine plan and the associated operational organisational structures. This paper outlines the lessons learned to provide an example of successful integrated mine planning for closure. The North Country Rock Pile project had three major learnings which resulted in an effective organisational structure that allowed for the execution of an integrated planning model for progressive closure. The initial hurdle the project faced was adapting the psychology of an operational open pit mining team. The team was an experienced mining group who came in with the perspective to target the shortest haul possible resulting in the initial perception that the longer haul of material to the NCRP was an un-necessary task impacting operational performance metrics. After the installation of an improved dispatch tracking system and performance metrics, it was possible to demonstrate that the mine was shovel constrained. This showcased the short haul was generating an increase in queue time not production. With updated performance metrics, the team was aligned to target a decrease standby through haulage to the NCRP. These performance metrics had to be reinforced by financial mechanisms. The operations team was able to offset costs by charging time to the capital project set-up for the closure of the NCRP. This allowed the operations team to receive credit for time that would have otherwise likely been standby. As well, the progressive closure project was able to receive the benefit of not having to incur costs for the drill, blast and load as that was done as part of the operation. This was a significant benefit to the project and one of the primary drivers for the early approvals of the work as the project costs were limited to the incremental haulage distance and placement of the material. Life of Mine Conference 2023 | Brisbane, Australia | 2–4 August 2023 114 While the combined operational and progressive closure approach provided financial advantages, it did result in the project being constrained by the operational activities. A traditional capital project is managed through a linear execution plan where the deliverables within a project are within the realm of control of the project execution team. However, the NCRP project had to be continuously adapted to the outcomes of the pit operations. This included geotechnical constraints, ore delivery, and other operational delays. To adapt, the planning module had to be dynamic but not reactive to allow for adjustments on a shift-by-shift basis. Based on this requirement the Diavik Closure Projects structure adopted a mine planning format. The team executed a similar planning timeline and reporting structure as the mine operations team, allowing planning to be integrated into the operational planning structures on a daily, weekly, monthly and quarterly basis. This resulted in the Projects team as a core pillar of the mine planning team. The process of continuous improvement spanned six years and has resulted in the project being ahead of schedule and under budget for the project’s scheduled progressive closure completion date of June 2023. The North Country Rock Pile project supports the argument that bulk earthworks progressive closure projects should be integrated into the operational mine plan. If the project is aligned the mine plan it allows for dynamic adjustments which capitalise on evolving opportunities inevitable in an operating mine. These cultural and organisational alignments should be supported by appropriate performance metrics and financial mechanisms to ensure united priorities. The result of this alignment provides long-term financial savings for the business as well as delivery of closure objectives.

Aug 2, 2023

The Olympic Dam mining operation is some 520 kilometres NNW of Adelaide on the Roxby Downs Pastoral lease. The deposit containing copper, uranium, gold and silver was discovered in 1975 by Western Mining Corporation (WMC). A joint venture was formed in mid-1979 between WMC (51 per cent) and British Petroleum (BP, 49 per cent) for the development and exploitation of the deposit. WMC assumed 100 per cent ownership after acquiring BP's share in early-1993. Ore is won from a highly mechanised underground mining operation and processed to refined products. Current annual output from the mining of 3.0 Mt of ore is approximately 83 500 t of refined copper, 1400 t of uranium oxide, 750 kg of gold and 12 000 kg of silver. Conventional long hole, open stoping techniques are used to extract the production ore. Since stope production began in April 1988, full surveys and appraisals of stopes have been carried out to evaluate the integrity of the design and blasting techniques. This evaluation included the determination of the degree of dilution or non break that had occurred. Performance information also made it possible to re-design any adjacent stopes to retrieve remaining ore and conversely, avoid the chances of targeting backfilled material in the future. Performing stope surveys proved not only to be a time-consuming process but one fraught with access and line-of-sight problems. Occasionally it was not possible to obtain any stope survey data, and as was often the case with the mine pass system, rarely. In 1992 the sudden failure of the pillar between the fine ore and mullock passes and the subsequent delays to production, emphasised the need to effectively monitor pass wear. Initial information regarding the development of the Cavity Measurement System (CMS) prototype (Figure 1) indicated that it had the potential to solve these problems by the introduction of a remote scanning device into a cavity. Following a great deal of investigation, Olympic Dam Operations purchased the first CMS in Australia. This paper discusses its application for all underground void surveys and the procedures developed to manage both field and office requirements.

Jan 1, 1995

By Poplawski R. F

A 32-channel PSS seismic monitoring system was commissioned at Mt Charlotte mine in 1994, and at the time it was the first such system in Australian mines. The system continuously observes the occurrence of seismic events and locates them accurately in space and time. Mt Charlotte has a history of seismicity, with the largest event in recent years of Richter magnitude 4.3. The decision to 'go seismic' was made despite some uncertainty regarding its potential usefulness. However after the first year of operation, benefits have been realised in terms of less production downtime, improved mine safety and mine planning, and better understanding of the nature of Mt Charlotte seismicity. The seismic network has performed well, recording 550 events in its first year of operation to a location accuracy averaging ¦ 12 metres. System reliability is excellent, with very little downtime, and acceptable operation and maintenance times and costs. Observations show major distinct changes in the rate of mining induced seismicity over time periods of weeks and months. Events have tended to cluster in specific mine areas and on particular faults and structures. Case examples of pillar preconditioning, breakout around an orepass, and a major stope rockburst, illustrate the role of seismic data and the benefits it brings to safety, productivity and planning.

Jan 1, 1995

By Beeforth C. G

The use of Non-Linear Programming to obtain improved schedules of future activity in two specific cases of mining and treatment of minerals is described. The two cases were (i) reclamation of gold, uranium and sulphur from old surface tailings dams and, (ii) underground mining of gold. The method used an augmented Lagrangian device to reduce a constrained Non-Linear Programme to a sequence of unconstrained hill- climbing procedures. The main advantages of the method appear to be those of (a)flexibility of modelling of industrial characteristics and constraints and, (b) reasonably modest computation times.

Jan 1, 1977

By J Tien, J Huang, N Haque, M O’Brien

Coal preparation is an integral part of producing coal for thermal powerplants and metallurgical processing plants. Coal processing plants use various unit processes to separate gangue and ash content from mineral coal, thus increasing the specific energy content.A flow sheet and a simulation model was established for a typical coal processing plant using Microsoft Excel. This model used the mass balance and split factors for run-of-mine (ROM) coal, tailings and water usage from a typical, generic coalmine.The common method of coal preparation initially involves several stages of crushing to reduce the size of coal. It is then sent to the processing plant for further washing. The typical method in Australia for coarse coal material processing is the use of dense medium cyclone (DMC) (Kininmonth and Baafi, 2009). Flotation cells are used for processing of fine coal. The fine products are utilised for coking coal only. In our case study, the intended coal product is for thermal powerplants. Therefore, the fine coal processing utilised spirals instead of flotation, which is typical for the industry.CITATION:Huang, J, Haque, N, O'Brien, M, O'Brien G and Tien, J, 2016. Development, simulation, economic and environmental evaluation of a coal processing flow sheet, in Proceedings Life-of-Mine 2016 Conference , pp 48–51 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

Some important mineral fields are referred to in discussing the formation of placer deposits in Australia. Testing methods include boring hand, with percussion rigs; with auger and pit digging drills; and l by vibro drilling. Sampling errors are minimized by the use of correct techniques and equipment for boring, sampling, and sample dressing, A hypothetical set of data is used to demonstrate the final process of evaluation, and some relevant taxation provisions are discussed.

Jan 1, 1964

The geological features of the destructive plate margins of the southwest Pacific favour the formation of porphyry type deposits. The major controlling factor favouring the formation of gold-rich deposits of this type is a dense crust. This results in shallow intrusion of large magma bodies beneath andesite stratovolcanoes. Where the intrusives have near vertical sides, the comparatively low temperature of transfer of volatiles from the solidifying melt favours the partitioning of gold into bubbles of volatiles. They reduce the viscosity and density of the melt, resulting in the upward movement of a mineralised melt. With the drop of pressure with upward movement the bubbles separate into a two phase mixture, triggering freezing of the mineralised melt and the formation of a gold mineralised stockwork.

Jan 1, 1995

Where tunnel rounds are based on the burn cut, faster advance could often be achieved by increasing blasthole diameter from (the conventional)

Jan 1, 1981

By Vassiliev P

Cut-off optimisation, based on the work of Lane (1988), can be used to maximise the NPV (Net Present Value) of a mine by the judicious manipulation of cut-offs and the use of stockpiles. Apart from maximising NPV, cut-off optimisation will ver

Jan 1, 1998

By A Weeks, W J. Shaw, A Kuk

Grade control is a process that requires the interaction between many components of the mining operation and successful grade control is only realised through good data, robust systems, and a well-trained, motivated and disciplined workforce.The Mt Magnet Gold Project Pty Ltd (MMGP), a wholly owned subsidiary of Ramelius Resources Limited, started mining at Mt Magnet in February 2012 with high expectations for success. Positive cash flow would fund an aggressive exploration and mine development program in the area to increase mine life. Disappointment followed when after start-up the operation had issues achieving budget grade and realising the predicted grade of the mined ore. In January 2013, things started to improve. During the next six months, gold production steadily increased with successive months achieving record production. What had changed?Improvements started following the realisation that controlling grade was not the sole responsibility of the mining geologist and that everyone on-site has a role to play. This paper examines the factors that delivered success for MMGP.CITATION:Weeks, A, Shaw, W J and Kuk, A, 2014. Who is responsible for grade? – an evaluation of the value chain at Mt Magnet Gold Project, Western Australia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 477–482 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Orrock G, McKee DJ

Mathematical models of autogenous and semi-autogenous grinding mills have now reached a stage of development where they can be usefully applied to practical problems. In particular, the models are suitable for inclusion in simulations of grinding circuits to study the effects of cir- cuit changes, variations in ore type and changes in throughput. The paper describes a simulation study of the Elura grinding circuit where the empha- sis was on investigating methods of reducing product size from an autogenous mill-ball mill grinding circuit.

Jan 1, 1988

The mining industry has expanded significantly in the Pacific Region over the past two decades through a mix of new developments and brownfields expansions of existing operations. Despite this overall success there are also a number of well publicised examples of less than successful minerals ventures. These problem developments highlight the fact that success cannot be taken for granted and that rigorous planning and attention to detail is essential. The dominant growth has come through expansion of existing businesses, notably alumina, iron ore and coal, achieved through both efficiency gains on existing plant and step change capacity additions such as new mines and/or expanded processing plant. This expansion has largely been linked to increased market opportunities. The major issues are the quality and extent of the host resource, achieving the market targets, and the efficiency of the expansion effort. There can be also a range of site specific issues which need to be addressed. The development of new greenfields operations is often more complex as it can bring a wide range of new issues. Depending on the nature of the development, and the companies involved, these can extend from initial financing through to obtaining a market position. Incorporating major new technology and/or establishing infrastructure and attracting staff to remote locations can also add significant challenges. This paper outlines many of the critical factors which need to be considered prior to proceeding with major expansions or greenfields developments. These will be linked to a number of developments in the region over the past decade.

Jan 1, 2004

By R Pax

Feed ore variability, the major disturbance into a mineral processing plant receives considerable attention operationally, and at research and strategic levels to ensure that the throughput of the ore are maintained at all times whilst encouraging a sustainable approach to recovering the valuable minerals from ore bodies. Effort and insights from mineralogical and processing characterisation (eg. ore hardness) of sub-ore body domains allows sequencing for processing to ensure consistency and throughput for the size sensitive grinding unit processes. Optimising the blast fragmentation has benefit as does pre-concentration using ore sorting. Blending of ore domains with different characteristics is common for operations. In recent years a number of technologies have become available for on-line and more rapid assessment of ore and have been discussed in a recent paper by Cameron et.al. (2016) as an opportunity for further utilisation of mine-to-mill (and mine to product) strategies. Current concepts have focused on extensive characterisation of ores so that current control practices can be realised and made more effective with relatively slow measurements and actuation. CITATION: Pax, R, 2018. Dynamic concepts for mine to mill operation and optimisation, in Proceedings Complex Orebodies Conference 2018, pp 124–125 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

The Mobile Miner MM130 was delivered to Broken Hill in February 1992. During March the machine was extensively trialled on the surface to test manoeuvrability, climbing ability and muck handling prior to being trammed underground in April. The first cutting test on 30 April 1992 provided promising results. The machine has undergone continual development since it arrived in Broken Hill with aims of ensuring reliability and achieving performance goals. The paper gives a detailed account of recent performance comparing this with the predicted Performance.

Jan 1, 1993