Search Documents

By J Crosbie, M Lord, R Bitencourt, P Defferrard

The MMG Century mine, which is the largest zinc/lead mine in Australia, began operating in 1999 and ceased mining from the open pit in July 2015, with processing completed in early 2016. Closure plans were developed from 2006, and detailed planning for closure commenced in early 2011 with the appointment of a dedicated closure planning resource. The site will continue to be managed during the active and passive closure phases to complete rehabilitation commitments and demonstrate that closure completion criteria have been achieved.Completion of the mining/processing phase of the project provides an opportunity to reflect on successes, missed opportunities and lessons learnt with respect to planning and execution of mine closure. This paper highlights examples of success at Century and also identifies key learnings and areas for improvement in progressive closure outcomes. Specific examples examine mine planning and execution involving bulk movement of waste rock and construction of permanent waste encapsulation landforms. The paper also provides recommendations for other sites that are planning for closure.Decisions made during the operational phase of the project life can result in a significant increase in closure liability and reduce the likelihood of achieving lease relinquishment. Likewise, it is of paramount importance to assess the consequences and thoroughly understand the risks associated with changes or deferral of closure plans, progressive rehabilitation targets and closure related key performance indicators.CITATION:Lord, M, Bitencourt, R, Crosbie, J and Defferrard, P, 2016. Closure planning lessons Learnt from the Century mine, in Proceedings International Mine Management Conference, pp 207-216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

One of the major changes in the resource industry in the nineties has been the re- internationalisation of the industry. The history of the resource business has been one of companies from the developed world utilising the cash flows from their operations to explore and develop mines in less developed regions of the world. This resource development has progressively generated wealth and economic development, which in tum, has led to a new generation of exploration and mining projects.   InSouth America, Chile had led the way in a mining resurgence, now closely followed by Argentina, Brazil, Venezuela and Peru. Although Chile has long had a significant copper mining industry, the pre-nationalisation phase was driven by American capital; the current phase has been spearheaded by RTZ - BHP at Escondida with Canadian junior companies, in particular, providing major speculative impetus. The Australian junior companies have not been significant in South America.   Although Canadian and USA exploration appears to be in decline, the mining industry, particularly in gold, is buoyant in North America. Interestingly, a number of listed and unlisted Australian companies are active, particularly in United States exploration.   Australian-based companies have dominated the South-East Asian exploration scene, especially in the Vietnam region. To date, the combination of political and legislative uncertainties have failed to lead to significant resource developments in this region. The area remains one of great potential, as exemplified by the exciting developments in Indonesia.   The Philippines has a history of mining, and this has been dominated by both local and North American operators. Both large and small Australian resource companies have a presence in the Philippines, and the development of the copper-gold potential could be impressive over the next decade.   The tales of the undeveloped mineral potential of China are probably rivalled only by the supposed strings of virgin Russian orebodies! Many Australian companies appear to have looked but few have chosen to proceed with Chinese developments. There seems little likelihood that China will, in the foreseeable future, rival South America as a target for Australian and North American resource capital.   Papua New Guinea has had an active, albeit chequered history in mining, with Australia long being the predominant source of exploration and development funds. The developing nation status of PNG has generated extreme uncertainty, with the current exploration scene all but dead. Most recently, the international flotation of Lihir Gold has tested the international and Australian investment community's commitment to PNG resource development.   The Australian exploration scene continues buoyant, although dominated by gold. The base metals scene is generating, on average, one significant base metal mine developed every couple of years. This is probably the fastest rate of significant base metal development in Australia's history.   The gold scene has been one of incredible dynamics, and there is no evidence that this momentum is waning. The development of new exploration techniques, together with a number of the companies reaching a critical size, has added to the momentum in the industry.

Jan 1, 1995

This paper examines the reform of mining legislation over recent years, the establishment of new Crown land management agencies, and the role of the Crown and environmental groups in nature conservation inNew Zealand. It describes the relationship of the minerals industry to the Department of Conservation and environmental groups over recent years, and the prospects for mineral development on the Conservation Estate in future.

Jan 1, 1995

By J Zhou, D M. Hunter, S M. Iveson, K P. Galvin

The REFLUX Classifier is used to perform particle separations on the basis of density utilising a set of parallel inclined channels positioned above a vertical fluidised section. In continuous mode, feed enters part way up the vertical section, while fluidisation water is introduced from below. Lower density particles are conveyed upwards and collected in an overflow stream, while high density particles segregate onto the inclined surfaces, settle to the base of the system and empty via an underflow stream. Pressure transducers are used to measure the suspension density in the vertical section. This suspension density is maintained by a pneumatically controlled underflow valve to maintain a target suspension density or ‘set point’.Previously, Galvin et al (2010) demonstrated the significant improvement achieved via a new laminar-shear separation mechanism, achieved by utilising closely spaced inclined channels in the REFLUX Classifier. For the separation of low-density coal particles from mineral matter, a channel spacing of 6 mm proved effective; however, for the separation of gangue minerals from much higher density minerals such as iron ore, the shear-induced lift needs to be even higher. In this paper, we examine the influence of two different channel widths on the continuous processing of an industrial iron ore feed in the REFLUX Classifier. It was found that when moving from 6.0 mm to 3.0 mm channels, the ability of the system to reject coarser gangue material and retain finer high density material across a particle size range from 0.125 to 1.0 mm was increased, resulting in a higher grade product.CITATION:Hunter, D M, Zhou, J, Iveson, S M and Galvin, K P, 2017. Influence of shear rate on separation of iron ore fines using the REFLUXTM Classifier, in Proceedings Iron Ore 2017, pp 205–210 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

Although small scale mining is regarded by many as of historical value only, this kind of mining activity is still much more widespread than is usually assumed. It has been estimated that it produces as much as ten per cent of the global mineral output. More significantly this figure is often much higher for many of the developing countries of Africa, Asia and South America, signifying the relatively greater contribution of small scale mining to the economies of those countries. It is also noted that small scale mining has always been a feature of mineral production in New Zealand and Australia. An attempt is made to define small scale mining, and the factors determining the suitability of small scale mining operations are discussed. The state of the art in small scale mining is reviewed and the author endeavours to rationalise the important parameters which contribute to successful small scale mining operations and discusses how these parameters may be optimised. The benefits of small scale mining to the mining industry as a whole and to the community at large are outlined. The paper concludes by emphasising the necessity to maintain small scale mining and 'explores' its future 'prospects'.

Jan 1, 1990

The Fosterville Goldfield has a modest past production (0.3 Moz), but is now emerging as a significant goldfield (2.6 Moz resources, including 1.1 Moz reserves) with implications for exploration within the orogenic gold provinces of the Lachlan Fold Belt in Australia and the Buller Terrane on the West Coast of New Zealand. Fosterville is located 20 km east of the 22 Moz Bendigo Goldfield and is geologically similar to other Victorian goldfields, however the nature of the gold mineralisation differs significantly. Unlike other Victorian goldfields there is no primary free gold at Fosterville. The gold occurs in as sub-SEM resolution particles, in fine grained arsenopyrite and pyrite crystals disseminated through the wall rocks in fault controlled quartz-carbonate vein stockworks. The Fosterville Goldfield comprises several subparallel fault systems striking 340¦ over an exposed strike length of 28 km. The Fosterville Fault system comprises the west dipping (~75¦), reverse Fosterville Fault and several less steeply west dipping splay faults formed in the footwall. The splay faults extend through east dipping beds from the Fosterville Fault across a syncline hinge into stratigraphically controlled positions on the west dipping limb of the syncline. The predominant control on gold mineralisation is the intersection of the bedding on the east dipping limb of the syncline and faulting which, is in turn controlled by the orientation of bedding in the west dipping limb of the syncline. The mineralised shoots are thus subparallel to the plunge of the syncline and show a plunge reversal about a culmination in the footwall syncline. This provides a very powerful exploration tool with bedding û cleavage intersection lineations measured in outcrop and oriented core indicating the plunge of mineralisation. Mineralisation is also, albeit less commonly, controlled by local variations in strike and dip of the host fault and at metre scale by host lithology. As the faults and mineralisation are stratigraphically controlled, detailed stratigraphic interpretations are essential to provide control on structural interpretations for resource modelling. Compared to other Victorian goldfields, the Fosterville Goldfield formed later (385 Ma to 360 Ma cf 440 Ma), at lower temperatures and at shallower depths (fluid inclusion studies of Au associated veins suggest vein formation at ~270¦C (range 140¦C to 385¦C) and at depths of 2.6 - 5.7 km).

Jan 1, 2005

By C Zhang, P Wang, S Yao

The Zhilingtou Au-Ag deposit is situated in the eastern part of the complexly deformed and metamorphosed South China Caledonian Fold Belt. It consists of seven orebodies that are almost exclusively hosted by biotite plagioclase gneiss of the Precambrian Chencai Group. They form an apparent en echelon pattern in both cross-section and level plan. Three different ore types, based on mineralization textures, have been recognised within the Zhilingtou lode. These are Au-Ag-rich quartz veins, Au and Ag-bearing silicified rocks and Au-Ag-containing altered rocks with quartz stockworks. The mineralisation is principally composed of electrum, argentite, pyrite and minor sphalerite, galena as well as traces of hessite and chalcopyrite plus a gangue assemblage of quartz, rhodonite, sericite and chlorite. Fluid inclusions related to Au-Ag mineralisation yield a wide range of homogenisation temperatures from 110 to 447¦C, with two distinctive peak values at 250 - 300¦C and 350 - 400¦C respectively. d30Si values of quartz veins and silicification from the three stages of mineralisation range from -0.1 to -0.4ë. The mineralisation at Zhilingtou is interpreted as forming by recirculated meteoric water extracting ore-forming elements from metamorphic rocks due to Mesozoic volcano-magmatic activity.

Jan 1, 1995

By K Palmer

Alluvial platinum was recovered during gold mining operations in Maud Creek, a tributary of the Howard River. Average electron probe analyses give Pt 88.75, Fe 5.27, Ir 0.70, Os 1.06, Pd 0.34, Ru 0.14, Rh 1.29, Cu 1.06. Rare grains of a Pt-Fe-Cu alloy are also present and an unusual feature of all grains is the relatively high rhodium content which finds expression in segregations of rhodium arsenide, cherepanovite. Platinum is found in the Orepuki area of Southland, where it is probably partly derived from the mafic rocks of the Longwood Complex. Rocks of the Rotoroa Complex, similar to those of the Longwood Complex, form bedrock in Maud Creek and are possibly the source of the Howard platinum. Alternatively, it might be derived by glacial transport from the Matakitaki ultramafic block 30 km to the southwest. Origin from the Rotoroa rocks is preferred as, if the Matakitaki rocks are part of the Dun Mountain Ophiolites, they might be expected to contain osmiridium rather than platinum. The ratio Pt:Ir-Os has been widely used to distinguish low Pt:Ir-Os ophiolitic from high Pt:Ir-Os gabbroic assemblages. Mafic complexes such as Longwoods, Darran, Rotoroa, and Riwaka might be expected to show similar high Pt:Ir-Os ratios and be targets for platinum exploration. Detrital platinum examined from the Parapara area, Golden Bay is mainly osmiridium, with rare grains of rutheniridosmine, very similar in composition to that found in concentrates from the Kaniere dredge, West Coast.

Jan 1, 1987

Investigation of the Effect of N-Substituents on Performance of Thioureas as Special Collectors for Copper Sulfides by ab Initio Calculations

Sep 13, 2010

The Hyde-Macraes Shear Zone (HMSZ) is low angle, duplex thrust system that has developed in a graphitic pelite schist within the Otago schist belt, New Zealand . At Round Hill lateral ramps have developed parallel to the movement direction between+ the footwall and hangingwall shears. These structures exhibit normal oblique-slip displacement which has been an important mechanism for creating space in an otherwise compressional system. Gold-bearing quartz veins were emplaced along the boundary shears and lateral ramps during thrusting. Gold within the lateral ramps is coarse (up to 300 microns) however hanging wall cataclasite development in the boundary shears after the gold was deposited has reduced the grainzise of most of the gold to less than one micron. This bimodal gold distribution has metallurgical implications with respect to the maximisation of gold recovery at Macraes.

Jan 1, 1993

By R Byrnes, P Hensley

The outstanding environmental management initiatives undertaken by Novacoal at its Western Main Site near Lithgow in New South Wales over the past five years are detailed in this paper. These initiatives have been based on a combination of proven and innovative investigation and implementation techniques, close consultation with regulatory authorities and full support by colliery management. The results of these initiatives have enabled the colliery to exceed its pollution control obligations from a base well below industry standards. The initial poor condition of the mine was the result of over 50 years of traditional mining which paid little regard to environmental management. The transformation of the colliery within such a short period, with limited capital, is considered a model for the N.S.W. coal industry.

Jan 1, 1995

By Walker K, Burton RC

An outline of the ventilation and refrigeration requirements of deep South African gold mines is presented. This is followed by a brief description of the history of controlled recirculation in mines and the practical and economic benefits such schemes can offer. The potential hazard of a fire in a recirculation system is discussed.The major part of the paper describes the first large-scale field trial of controlled recirculation to be conducted in South Africa. Emphasis is placed on the monitoring system that was used for data acquisition during the trial, and also on a safety system designed to shut off the recirculation fans in the event of a fire.The paper concludes with a review of the latest development work taking place on recirc-ulation safety systems.

Jan 1, 1985

Western Mining Corporation has grown from a small gold exploration and mining company, funded by large established mining companies, into a large multi-commodity and multi-national mining company with shareholders who no longer have the same understanding of mining as the founders. Ore reserve calculation methods and reporting procedures have gradually changed throughout the group during this growth. These changes have been led by the newer mines, in particular the Kambalda nickel mines, where the need for more global, less conservative reserves were required to justify capital and forward sales contracts and to inform shareholders of the true worth of their company. This change in attitude to reserves has flowed back to the gold mines and has allowed a better informed management and investing public to plan for the future. Management of the calculation of reserves remains the responsibility of individual mining operations, but a corporate reporting and management structure exists through the office of the Director of Exploration and divisional chief geologists who strive to maintain standards of calculation and reporting. Specialist ore reserve geologists are starting to justify their place in the organisation, particularly at the larger operations. Reporting to the new AusIMM Standards is fully supported, although the amount of supplementary information requested will need to be considered carefully because of the large number of factors that make up even the simplest reserve.

Jan 1, 1990

To ensure that its voice is heard in the development of policies and plans under the Resource Management Act, the mining industry is challenged to participate in their preparation. This paper outlines a number of practical ways in which the industry can participate in debate on sustainable management and how it can be put into practice within the industry.

Jan 1, 1992

In 1948, it became clear that the ventilation system of The Zinc Corporation Limited and New Broken Hill Consolidated Limited mines, would be inadequate for future operations. The,paper describes in detail the process of designing an entirely new ventilation system for a large underground mining operation. The system was based on a single new upcast airway to be located on the boundary of the two properties, which were to be ventilated in parallel as two separate ventilating districts.From calculations of resistance, and assessments of future air requirements, the duties of a new exhaust fan to be located on the collar of the upcast airway were specified as 700,000 cubic feet per minute at 2·6 in. w.g. total pressure for initial operation in 1953 increasing to a maximum of 900,000 c.f.m. at 3·6 in. w:g. total pressure ten years later. The economic size of the new airway was calculated from a consideration of the first thirty years operation of the system, and it was decided to provide a 20 ft. diameter concrete-lined shaft.The new system went into operation five years after the initial planning, and the effect of the difference between actual and predicted rates and distribution or production are discussed. The final result was entirely satisfactory.INTRODUCTIONThe first proposal for an investigation of The Zinc Corporation Limited-New Broken Hill Consolidated Limited ventilation system with a view to putting it on a proper technical basis was made in 1938. A new Main Shaft was then being sunk, and it was decided to postpone the enquiry until this had been completed to No. 14 Level, when operations would be temporarily suspended and the shaft commence to operate as a major airway. The investigation was completed early in 1940, when Z.C. Ltd. upcast fan was...

Jan 1, 1956

The Rio Tinto Iron Ore group currently estimates grade attributes for mineral resources using ordinary kriging (OK). OK produces a smoothed globally unbiased estimate, but does not capture local variability, which can have significant impact on mine planning and scheduling. The dimensions and the multivariate nature of iron ore deposits make point simulations of whole deposits impractical. With a direct block simulation method the size and speed limitations of point simulations can potentially be overcome, resulting in a viable method for capturing local variability and for providing risk measures into the mine plan and schedules. Some iron ore deposits are highly folded (post mineralisation) and require preprocessing using an unfolding algorithm to properly define the continuity parameters and directions of anisotropy before simulation can proceed. Block co-simulation proceeds in unfolded space and since mine planning require a block-model with regular block-sizes; a regular block-model is unfolded first. This paper discusses a block co-simulation approach that can be used to simulate the irregular blocks resulting from the unfolding process. A section of an iron ore deposit is used for testing the block co-simulation algorithm and the simulation results are compared against the Isatis direct block simulation method. Available blasthole data is also used to validate the behaviour of the block co-simulation algorithm.

Sep 26, 2011

East Otago gold deposits are hosted in Otago Schist that is the metamorphosed equivalent of Permian-Triassic Torlesse terrane greywackes. Relatively undeformed Torlesse sequences in Canterbury have <l m - 50 m bedding, with c. 500 m - l km and c. three kilometre scale units, typically either: 1) thick-bedded, massive, sandstones; 2) thin-bedded sandstone-argillite flysch; or 3) siltstone- or argillite-dominated units. Such lithological layering in Otago was intensely folded, deformed, and overprinted by metamorphic fabrics during Jurassic-Cretaceous regional metamorphism. Although primary sedimentary structures can no longer be recognised, a æghostÆ lithological variation is still present in Otago represented by psammitic (sand-derived), interlayered (sandstone-siltstone derived) and pelitic (siltstone-mudstone derived) schist. Lithological æunitsÆ in the schist are typically either 20 100 m or c.1 - 2 km thick, and are oblique to faults and shears hosting gold mineralisation at Macraes, Barewood, Nenthom, and Oturehua. Lithological variations and folds in lithological units are important in the along-strike distribution of gold in these deposits, and in the development of relatively high-grade pods and shoots at l00 m - 1.5 km scales. Ramps, flats and step-overs (known to be locally important for controlling mineralisation) are commonly located at lithological boundaries, presumably by local refraction of faults or shear zones as they propagated through folded stratigraphy. The various lithologies have also responded differently to deformation, causing variations in permeability that affected the penetration of mineralising fluids. Mapping lithological variations in barren host-rocks, either directly+ by fieldwork or indirectly by aerial geophysics, is a key to understanding and predicting the distribution of gold at mine and deposit scales.

Jan 1, 2001

By Morsky P, Kalapudas R, Natunen H, Virtanen M

The development of autogenous grinding modification in Outokumpu, known with the name 'Outogenius Comminution', was 'reversed'. At first the metallurgists studied and tested tens of years autogenous grinding in detail in full scale circuits at the concentrators of the company. After the final solution already had been found, also a pilot plant was built and now finally, research work is under way to develop a special laboratory method for testing the suitability of ores for 'Outogenius Comminution'.

Jan 1, 1993

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 C T. Portelli

Belt conveyor transfers are the most likely location for high wear rates and failures. Belt transfers are necessary to change the direction of conveyed material and will remain a part of belt conveyor systems into the future. Burden being accelerated due to fall and changes in direction from one system to the next, prevents steady state flow which introduces component fatigue. The conveyor belt is considered the greatest cost item over the life of a belt conveyor system and consumes considerable downtime to replace, therefore a financial incentive exists to preserve this high-cost item. Other issues created at the transfer include health risks of uncontained dust and product losses due to spillage. Additional consideration to support the belt is one way to improve the life of components and contain dust within the transfer chute. The humble impact cradle/bed has changed little over the years whilst conveyor systems have achieved ever greater flow rates. Further development of the impact cradle is an opportunity to reduce maintenance costs and increase uptime. The peak technology on the market for conventional impact belt support is the dynamic impact cradle, which ensures the belt support area under the chute allows for some dynamic travel, whilst also maintaining a consistent skirt board area. The impact energy at a transfer when installed with Kinder Australia’s dynamic impact belt support system was measured to further understand the forces involved and how they compare with static belt support systems. Adding further dynamic capacity to the load zone has been shown to increase belt life by at least 30 per cent. Other components also benefit from reducing impact energy in the transfer and the incorporation of polyurethane bushes at roller supports has been employed further increase roller and frame life. Kinder Australia has developed a unique and innovative range of belt support technologies that further promote dynamic travel whilst maintaining a consistent skirt board area without a significant increase in belt-friction tension. This technology combines slider rails with rollers that can absorb impact independently within the support system and/or utilising exotic slider materials to overcome high belt speeds and/or system capacities. Kinder Australia has a vast library of documented case studies and application data to ensure the future systems being offered will survive, provide better chute sealing and protect the conveyor belt.

Sep 18, 2023