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By B Walker, A Robertson, C Wels, S Fortin

A background characterisation study was carried out in the Sangre de Cristo mountains, New Mexico, to: quantify naturally occurring contaminant loads from mineralised areas; define site-specific background concentrations; and to determine key factors controlling spatial and temporal variations in contaminant concentrations. The study included a comprehensive sampling and testing program (paste pH/EC, ABA, leach extraction tests) of soil/bedrock from mineralised areas (including erosional scars), and a ground water and surface water quality monitoring program in selected mineralised watersheds. Results demonstrate that high concentrations of contaminants occur naturally in ground and surface water draining the mineralised area of the Red River basin. The erosional scars were found to represent the major source of acid rock drainage (ARD) (~66 per cent) in this area due to: high rates of weathering and erosion, which continually exposes sulfide-bearing outcrops; and high rates of run-off as a result of high elevation and lack of vegetation. The scar material is generally very acidic (paste pH ranges from 8.5 to 1.5; average = 3.6) with highly elevated concentrations of sulfate and leachable metals. The composition and concentration of leachable metals vary significantly, not only between scars but also within a given scar. While all streams draining the various scar watersheds are highly acidic, each has a characteristic æfingerprintÆ of sulfate and metal concentrations. Most of the run-off from the scars infiltrates into alluvial debris flow aprons and reaches the Red River via groundwater flow.

Jan 1, 2003

By L Richards, R L. Brathwaite, C Mazenga

Underground mining of gold-silver bearing quartz lodes was carried out in the great mines at Martha Hill, Waihi over 70 years from 1882 until 1952. Shafts and stopes reached a total depth of 600 m on 16 levels, with workings extending laterally some 1.6 km, and as new reefs were discovered the workings extended beneath parts of the township. Over their long life the mines produced 1217 tonnes of gold-silver bullion from processing 12.2 million tonnes of mined ore. In the early-1980s drilling proved large reserves of gold and silver ore remaining in stock-work zones between the previously mined lodes. This led to a new era of mining at Waihi with the opening of the Martha Hill open pit in 1988. A series of three sink holes have formed above unfilled stopes of the Royal lode. In 1999 a sudden collapse crater 40 m in diameter occurred near an occupied part of Waihi, placing in danger several houses and a busy street. This crater formed close to a similar crater that occurred in 1961. The 1999 collapse resulted in subsurface investigations and risk assessment studies being commissioned by the local Hauraki District Council. However, a further 50 m diameter collapse crater in December 2001 formed in a residential area, swallowing and wrecking an occupied house, fortunately without injuring its five occupants. Two other houses were perched on the crater rim. The 2001 collapse led to an acceleration of the work being carried out by the Institute of Geological and Nuclear Sciences Ltd. (GNS) to identify the extent of the old underground workings at Waihi. For the risk assessment detailed rock mechanics analyses were made to consider the stability of the underground mine stopes, in terms of the stope back, hangingwall, footwall and crown pillar failure mechanisms, as well as void migration. The collapse crater areas were analysed using using several methods, including analysis to simulate the probability of void migration from unfilled stopes to the surface using the @Risk program. The analyses show that in the cases of the actual collapse craters, the voids have a high probability of migrating to the surface, thus providing a method of testing the void migration modelling. Modelling analysis applied to the remaining stopes of the old underground mines show there are further areas where void migration from unfilled stopes has a high, medium and low probability of reaching the surface as a collapse crater. The locations of these probabilistic hazard zones were outlined using the @Risk modelling and deterministically by using the dimensions of the historical collapses applied along the length of the stopes. Consideration of the æincubation periodÆ (the time interval between the cessation of mining and the occurrence of collapse) and comparisons with mine subsidence histories overseas, indicates that further collapses are likely to occur over the next 50 years. Risk assessment estimates made using property values and occupancy levels within the three hazard zones, were compared with Societal and Individual Risk criteria. Results indicate that safety within the high and medium zones may be unacceptable.

Jan 1, 2003

The commonly used stainless steels, their properties and uses are briefly discussed.Two specific topics are then explored in more detai's to highlight development areas, the potential of which has been largely unexploited in mining milling, refining and smelting operations. The high strength to weight ratios achievable in austenitic stainless steels has been widely used in the transport industry to design high integrity light weight vehicles,especially railway carriages. This use has rarely been extended into other structural areas where highly aggressive environments could make stainless steel a cost effective material compared to protected carbon steels. The recently developed weldable ferritic steels are described and their potential in materials handling discussed. Particular attention is paid to 3CR12, a nominal 12% Chromium, titanium stabilised steel finding wide acceptance in the mining industry.

Jan 1, 1985

The New England Fold Belt forms the easternmost and youngest section of the Tasman Fold Belt System of eastern Australia. From middle Palaeozoic to Early Cretaceous time it was the site of extensive episodic calc-alkaline magmatism related to W-dipping subduction. The oldest rocks may have formed at least partly in a volcanic island arc, but from the Late Devonian, the fold belt developed as a convergent Pacific-type continental margin. For Late Devonian-Carboniferous time, parallel belts representing continental margin volcanic arc, forearc basin and subduction complex assemblages can be recognised. Major dextral transform faulting may have offset parts of the fold belt in the Late Carboniferous. In addition, some structural blocks which appear to be out of place in the overall palaeogeographic setting are possible exotic or suspect terranes. A great variety of lode deposits ranging in age from middle Palaeozoic to Early Cretaceous is present in the New England Fold Belt. The vast majority of these are related to emplacement of extensive granite plutons and eruption of continental silicic volcanics in Late Permian-Late Triassic time. However, volcanogenic massive sulphides and volcanic hosted epithermal gold-silver deposits in older rock sequences include one major orebody (Mount Morgan) and several important ones (Mount Chalmers, Cracow, Silver Spur, Cangai and Halls Peak). Some problematical deposits are best classified as metamorphic-hydrothermal. These include gold-bearing quartz reefs and stockworks in sedimentary host rocks, the most important of which are at Gympie, and antimony-gold- tungsten mineralisation in the New England area, mainly at Hillgrove.

Jan 1, 1987

By Letz H

An investigation of earthquake hazard in Papua New Guinea (PNG) by a yearly extreme magnitude method using the magnitude 7 earthquake record since 1900 shows that the Bougain-ville Island seismic zone is by far the most active, followed by the New Britain and northern mainland PNG regions. Return period for magnitude 7.0 earthquakes occurring in normalized 10,000km2 areas of the Bougainville Island, New Britain, Huon, West Bismarck, North Sepik and Ramu seismic zones is 37, 60, 81, 88, 125 and 125 years respectively. These areas are much more active than the California Seismic Zone 4 region including the San Andreas Fault, which has a normalized magnitude 7.0 return period of 299 years, calcul-ated here by the same method.Only southern PNG, including the Papuan Fold Belt and most of the Bismarck Sea, are less active than California Zone 4. The Papuan Fold Belt is only marginally less active than California Zone 4, but more active than the State of California taken as a whole.

Jan 1, 1994

By R Williams, P Godwin

In a time of changing rainfall patterns and in the light of recent tailings dam failures, there is closer environmental scrutiny for proposed tailings dam construction or expansion. Therefore the elimination of the traditional tailings dam could provide both environmental and cost benefits to an operation. One method to dewater tails is using pressure filtration to achieve lower moistures than what is currently available using other dewatering technologies. Further benefits include a higher rate of filtrate recovery, reuse of waste material and the potential for dry stacking of the filtered tailings cake, thereby minimising both risk and cost. This paper chronicles the replacement of two existing belt filter presses with a single McLanahan recessed plate filter press to dewater a tailings stream at a Bacchus Marsh site. It covers the slurry testing, equipment selection, installation, commissioning and operation of the filter press to achieve the following objectives:• removing the current tailings dam and slimes cells from the existing process to minimise failure risk and reduce the cost of a dam upgrade, as well as operational and maintenance costs• free up the surface area which was previously occupied by tailings dams and slimes cells• recover additional water to be returned to the process• reduce flocculent usage• reduce truck movements and handling.The project’s owner also expects to reduce carbon emissions by over 3000 t over the lifetime of operation as well as substantially reducing operating expenditure. By recognising the carbon reduction benefits, the project owner was able to successfully achieve partial funding through the Voluntary Waste Industry Protocol.An unanticipated, but as yet unquantifiable, bonus for the project was to seek an offtake agreement for the tailings thereby allowing the tailings to be considered a valuable source of beneficiated clay suitable for the construction industry.CITATION:Godwin, P and Williams, R, 2017. Pressure filtered tailings – environmental and cost benefits, in Proceedings MetPlant 2017, pp 324–334 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Ormsby W. R, Farrar L

The stratigraphy of the central Pine Creek Geosyncline has been simplified into a three-fold subdivision comprising the Batchelor, Frances Creek and Finniss River Groups. The Batchelor Group consists of a sequence of shallow water coarse clastics and crystalline carbonates and is conformably overlain by the marine carbonaceous shale dominated Frances Creek Group. Interbedded within the carbonaceous shale are turbidites, iron formation, tuffs, carbonate and non carbonaceous shale. The Finniss River Group is a flysch sequence of greywacke and mudstone. The stratigraphic and structural evolution and igneous history are all interrelated. Although the Batchelor Group may have formed in a tensional regime, it is likely that regional compression and accompanying thin skinned deformation began during deposition of the Frances Creek Group. Continued compression resulted in D2 folding d6collement deformation, wrench faulting in compressional zones and thrust faulting. Occasional relaxation of compression is marked by a number of periods of basic intrusion and perhaps distal volcanism. The style of deformation within sediments varies away from granitic basement highs and is similar to that observed around salt domes and found in experimental diapiric models. Sedimentary facies changes also indicate local emergence of basement highs during sedimentation. As compression continued, the deposition of thick sequences of the Finniss River and El Sherana Groups brought about regional metamorphism. Relaxation of compression and waning of associated subsidence resulted in a relative increase in the rate of uplift and partial melting of diapiric sialic basement. In places, granitic magma moved upwards and crystallised forming grossly concordant bodies. Other masses moved laterally and formed extensive granitic sills. Later compression periods caused mainly brittle deformation which may have been strongly influenced by underlying basement fabric.

Jan 1, 1994

By J Plinke

The imperative to operate sustainably requires all equipment and processes to operate at their maximum possible efficiency. Achieving this ideal state requires a thorough understanding, not only of the process itself, but also of the tools available to design and assess potential improvements. This paper presents a case where the widely employed Discrete Element Method (DEM) toolset proved insufficient to model problematic material flow during the process of optimising wet screening performance. A Smoothed Particle Hydrodynamics (SPH) model was found to more accurately replicate the flow characteristics of the physical system. Site observations identified biased loading of the screen decks to cause inefficiencies in the wet screening of an iron ore processing circuit. Two numerical modelling approaches were pursued with the aim to select the most suitable one and continue the optimisation process based on that selected model. Selection criteria were established, based on the minimum requirements of being able to replicate the problem, including the main flow dynamics deemed to cause the issue. The DEM model was found to over-simplify the slurry flow dynamics within the scrubber and no laterally biased flow was introduced by the scrubber’s rotation to the otherwise symmetric system. Since DEM was not able to accurately replicate the existing problem, it was deemed an unsuitable method to assess the effect of any changes to the system. The second approach consisted of a SPH model. This model was deemed to map the flow within the scrubber with sufficient accuracy to address the problem, as it produced biased screen loading comparable to that reported from site. Changes to the wet chute, delivering material from the scrubber to the screen, aimed to neutralise the non-centrality introduced via the scrubber, were then successfully designed and assessed using the SPH model.

Nov 8, 2021

The selection of the ore haulage system is one of the most crucial decisions made in the development of an underground mining project. The haulage system is, once selected, one of the components of a mine that defines its ability to respond to changes in mining inventory and the market conditions for its products. Over the last decade, in Australia at least, this selection process has largely centred on the debate over the merits of shaft and decline truck haulage. Little attention, if any, was given to the application of inclined conveyor haulage as a real alternative to the shaft and truck haulage. This is despite well established precedents for its application in the underground coal industry and some limited applications in underground metalliferous mines. This paper seeks to explore the case for the application of inclined conveyors as a legitimate ore haulage system for underground mines. The case for conveyor haulage is illustrated by an overview of the application of conveyors at some existing operations, and discussion of what conveyors have to offer as a mine haulage system and the issues that are associated with them. Material drawn from the feasibility studies for NewcrestÆs Ridgeway mine and Telfer Deeps Project is presented as case studies that considered selection of inclined conveyor haulage. The purpose of these case studies is to highlight the value of impartially approaching tasks of this type with a robust plan. This plan should be able to respond to issues identified as the task progresses towards the objective of finding the right solution for an ore haulage system.

Jan 1, 2005

By Buizen M

The results of calibration trials conducted on parachute stoppings under a recently completed NERD&DC grant are presented. Applications of parachute stoppings, for rapid regulation and control of ventilation networks are described including use in mine recoveries, sealing sections and rescue work. Parachute stoppings are one of a series of non-rigid ventilation control structures specifically designed for quick installation in emergency situations, for use in high production/rapid advance areas and areas suffering roof-floor convergence.

Jan 1, 1988

By D Chalmers

Drill and blast mining techniques are used to mine coal outburst prone and high gas content coals in Australia. As the risk of an outburst is increased in high gas content coal, it is considered that drill and blast is the safest way to mine coals that refuse to yield gas even after considerable gas drainage efforts. The availability of suitable explosives for drill and blast in Australia is dependent on the æBuxtonÆ tests. With the diminished coal operations in England, the type and supply of such explosives is tenuous, causing significant disruption to the production of coal in some mines. In an attempt to free up the availability of explosives a review of the methods used for the testing of coal mine explosives was undertaken to ascertain the scientific basis for these tests. It was hoped that this comparison would allow regulators to have the confidence in explosives that had been tested elsewhere. Although this was not achieved, it has spawned a major research project that aims to better understand the mechanisms involved so that either confirmation of the current testing regime can be achieved or more suitable and scientifically based tests can be adopted. This paper looks at the ongoing research program investigating the parameters that are involved with methane ignitions from explosives. By utilising high-speed data capture and processing the research project is trying to view an ignition as it happens to identify the mechanisms involved so that better explosives can be designed for the coal mining industry.

Jan 1, 2007

The increasing global demand for rough materials forces almost every mine to look at the mechanisation in their processes. This will not onlyimprove performance but with safety issues becoming more and more prevalent, the need for the introduction of mechanisation technologies to mining applications is essential. Ongoing developments are occurring in almost every field, ranging from basic developments to specialised mining. Mechanical tunnelling and shaft sinking have set the standards regarding safety, profitability and environmental protection. Different machine types and working principles have been developed to suit the geological and hydrological requirements of tunnelling projects worldwide. Continuous activity in research and development leads to constant optimisation of tunnelling performance.

Jan 1, 2008

By Williams J. D

Magnetite has been used in coal processing for many years and it is likely that its use will continue well into the twenty first Century. While magnetite is only a minor cost component in coal processing, the use of processed magnetite in dense medium separation is essential to provide the split of quality coal products which the markets of today demand. The occurrence of magnetite in Australia is relatively abundant, but a combination of its iron content, magnetic properties, quality and proximity to the coal processing plants is essential to provide a low cost product for use in the Coal Industry. The demand for more splitting of coal in coal processing may require more grades of magnetite, particularly as a finer grade lower specific gravity medium to separate the finer quality low ash coals.

Jan 1, 1991

This presentation addresses the sources and weighting of project risk in coarse gold deposits with relevance to experiences at the Ballarat mine and Castlemaine goldfield. With sample representation and reliability often a source of great error in the resource estimation of coarse gold deposits, it follows that this matter should be of greatest risk to a mining project - but is it? What are the costs and efforts required to best quantify the sampling error due to nuggetty effect? After all, the main problem in Victorian gold mining ventures in the current decade is not the amount of gold available, but defi ning which portion of it can be converted to Ore Reserves or more so profitable gold bars. The author postulates that greater risk to the project lies in the geological interpretation and matching resource spatial parameters to mining methods, than the degree of uncertainty related to grade due to nuggetty gold. Recent experience in the Victorian goldfi elds is that the investor market has already severely discounted Mineral Resources reported in accordance with The JORC Code - so if they don't believe in the capacity to upgrade the resource why should we? To this end, Castlemaine Goldfi elds Ltd at its Ballarat gold project does not intend to estimate its gold mineralisation for public release, instead choosing to focus on the geological interpretation and mine planning elements. So with coarse gold deposits, is your Mineral Resource reported with The JORC Code a glass half full or half empty? Our mining forefathers in Victoria had no predictive tools which could define resources to any degree and yet were successful. By over emphasis on the definition of mineral resources and particularly the sampling error, are we ignoring the basics of cost control, solid geological interpretations and maximum mining flexibility. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010

By King MN, Travis IC

PISCES - the Planning and Information System for Coal Export Services has been developed by Port Waratah Coal Services (PWCS) to ensure the efficient and economic operation of the Hunter Valley Coal Chain. PISCES is a computer based integrated information and management system to coordinate operations commencing at minesites through the coal chain to shiploading at the Port. The PISCES system comprises a central database around which a number of planning modules interact. These include interactive programs for train planning and timetabling, stockpile management, berthing analysis and a coal shippers enquiry system. PWCS has previously developed - number of computer based systems for planning, controlling and monitoring complex coal handling operations and the extension of the PISCES system to the Hunter Valley Coal Chain is another initiative to assist the Hunter Valley Coal Export Industry in looking confidently towards the Future.

Jan 1, 1987

By W T. Pate, A V. Potapov, J K. Lichter

Even though flotation is one of the most important unit operations of mineral processing, accurate modelling of this process for plant performance prediction has remained elusive. In the last four to five years dramatic changes have occurred in our ability to make credible model based predictions. This paper briefly traces the history of flotation modelling from simple (lumped pulp-froth) æchemical kinetic analogueÆ models for single cells to more detailed multi-phase, multi-component population balance models for banks of cells. It then focuses on recent developments in physics-based modelling tools. This includes current efforts to model the forces of attachment and detachment at the individual event level as well as multi-event levels in individual cells and circuits. Two examples of these tools are presented. The first is DEM modelling of the mechanics of motion of bubbles in froths. The second is population balance modelling of the dynamics of flotation circuits describing how they are influenced by upstream processes (such as crushing and grinding) as well as internal process variables (such as aeration, agitation and reagent addition). Applications of each of these tools are discussed.

Jan 1, 2005

By S Shipard

Filters are used in water treatment and hydrometallurgical process plants for objectives such as generating a dry spadable solid, pumpable high density slurry or high purity filtrate. The priority objective of every polishing filter, sometimes also termed clarifying filters is high purity filtrate and these are found in many diverse industries and even different applications within the same industry.To generate a high purity filtrate, process designers have the choice of many different polishing filter products, but in reality very few polishing filters are based on fundamentally different filtering concepts.This paper reviews the technology merits of well-known and the more recently developed polishing filter products and aims to assist metallurgists and engineers with the selection of an appropriate polishing filtration technology for pregnant liquor filtration and other process applications, plus a guide to best practice.CITATION:Shipard, S, 2013. Polishing filters for mineral processing plants, in Proceedings MetPlant 2013 , pp 118-125 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By Bowra N

Working capital is best described as money that must be supplied from a company's treasury to buy inventories for raw materials and finished products and to provide credit to customers who have not yet paid for delivered products. Working Capital requirements for resource projects are to a large extent, dependent on specific characteristics of the projects concerned. Important variables are the nature of the project and speed with which sales can be realised. The project's location is also important as this will influence inventory levels. Working capital requirements have a time profile, the present value of which can represent a significant portion of a projects overall capital needs. A significant component of a project's working capital is not readily recoverable or able to be reassigned should the project fail or be deferred.

Jan 1, 1986

By A G. L Pratt, C Rossetti

The implementation of mass mining methods for large metalliferous deposits has led to the development and application of increasingly sophisticated automation and condition monitoring technologies in these mines. This technology aims to increase safety, equipment utilisation and monitoring of critical aspects of the underground ambient and geological environments. The communications networks required to support these aims and their associated technologies have evolved accordingly, and have done so in a demanding underground environment. The evolution of communication infrastructure for large underground mines has developed from basic analogue telephony to high-bandwidth optic fibre based systems. The latter is now the media of choice. More recently the developments in wireless broadband equipment designed specifically for underground environments have emerged to satisfy the needs of automation for mobile equipment and shaft conveyance communications. The use of internet protocols for industrial control and monitoring has led to the application of ethernet-based backbone networks as a standardised approach. There may also be a need for the integration of range of communications platforms in a mining operation to realise the full advantages offered by automation and condition monitoring technologies. As a result the design of the communications backbone networks for underground mines has started to become the domain of information technology professionals. Without these networks, the analysis of equipment utilisation is often not possible. The improvements that can be brought about by æsweating the assetsÆ and the transmission of business critical information are the most significant benefits of an integrated communications system. These benefits far outweigh the costs of strategic planning, subsequent specification and implementation of communication networks themselves. Future developments in mining systems and communications technology will continue to drive the demands placed upon communications networks as an essential mass mining infrastructure item. This paper outlines the benefits of secure high bandwidth backbone communications networks for mass mining operations and the need for a high degree of strategic thought and demand forecasting in the planning stages for these operations.

Jan 1, 2008

By T Muri

The drying operation of materials from particulate solids, through slurries and suspensions, to continuous sheets represents an important part of several processes in the chemical and mineral industries. The increasing demand of high productivity at low cost and minimal environmental impact makes it complex to evaluate and choose the best available drying technology for each industrial application. The drying technologies are mainly characterised on the basis of how the wet product is related to the drying medium, namely: direct and indirect drying. In the direct drying method (convection drying), the product is brought into direct contact with the drying medium, which may be hot gas or air. Large quantities of gas are necessary for transfer of the required energy. A special case of the direct dryer is the fluid bed dryer, in which the product floats on a cushion of air or gas. The process air is supplied to the bed through a perforated distributor plate and flows through the bed of solids at a velocity sufficient to support the weight of particles. Very high heat and mass transfer values are obtained as a result of the intimate contact with the solids and the relative velocities between individual particles and the fluidising gas. In the indirect drying method (conduction or contact drying), the wet product is separated from the drying medium. The drying unit can consist of a rotor forming the indirect contact heating surface mounted in a stationary or rotating shell. The indirect method uses saturated or superheated steam resulting in low energy consumption and minimal environmental impact. In this paper, a review is given of the technologies available on the market based on different drying methods. The advantages and the disadvantages are summarised with respect to issues such as investment and operating cost, maintenance, product capacity, product handling and environmental impact.

Jan 1, 2006