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By B B. Beamish, M S. Kizil

The processes that take place during the development of a heating are difficult to visualise. Bulk coal self-heating tests at The University of Queensland (UQ) using a two-metre column are providing graphic evidence of the stages that occur during a heating. Data obtained from these tests, both temperature and corresponding off-gas evolution can be transformed into what is effectively a video-replay of the heating event. This is achieved by loading both sets of data into a newly developed animation package called Hotspot. The resulting animation is ideal for spontaneous combustion training purposes as the viewer can readily identify the different hot spot stages and corresponding off-gas signatures. Colour coding of the coal temperature, as the hot spot forms, highlights its location in the coal pile and shows its ability to migrate upwind. An added benefit of the package is that once a mine has been tested in the UQ two-metre column, there is a permanent record of that particular coals performance for mine personnel to view.

Jan 1, 2005

By T S. Fayram

The successful application of flotation is now over one hundred years old. However in a practical industrial sense, it still remains predominantly an art rather than a quantifiable science. Moreover, the laboratory testing, interpretation and application of the technology can still be tedious, time consuming and costly. This paper outlines the use of proven statistical design of experimentation software for rapid optimisation of flotation testing with limited representative sample utilisation. This results in less costly required testing, a more thorough understanding of results and the ability to simultaneously optimise several variables and outcomes at once. At the Center for Advanced Mineral and Metallurgical Processing, this testing methodology has been used successfully in many metallurgical development and plant optimisation projects thereby confirming its real world utility and application.

Jan 1, 2005

By I M. Platten, Y Xie

Narrow vein gold mineralisation generally contains both fine (<100 ¦m) and coarse (>100 ¦m) gold particles. The in situ size and shape, deportment, distribution and abundance of the particles controls deposit sampling characteristics, grade distribution and metallurgical properties. Particles can range from individual disseminated grains, clusters of particles and masses above 1 cm in size. At each end of the coarse-gold to fine-gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated gold particles, through to extremely difficult for very coarse particles. Deposits generally show a background grade of mineralisation dominated by disseminated fine gold particles. Drilling will resolve the background grade well, though is likely to considerably understate the grade related to the coarser gold particles. Gold mineralogy has a significant impact on metallurgy, with key factors affecting recovery being particle size, deportment, liberation parameters and silver content of gold minerals. For coarse gold particles the focus should be on liberation and the early removal of the particles from the mill circuit by gravity concentrators and gold traps. Finer particles will require more grinding to liberate prior to flotation or cyanide extraction. The determination of gold particle sizing is thus required to minimise evaluation and geometallurgical uncertainty and lower project risk.

Jan 1, 2008

The Century zinc-lead orebody was discovered in 1990 and contains sufficient reserves to sustain open cut mining at 5 Mtpa of ore for approximately 20 years. It is proposed to pipe mineral concentrate in slurry form 300 km from the mine to the port of Karumba on the Gulf of Carpentaria. The concentrate will be dewatered at Karumba before being transported off-shore to deeper water in a self-unloading shuttle vessel for transfer to export bulk carriers. The four main environmental issues that attracted attention during the impact assessment phase of the project were: the selection of Karumba as the export port, the use of a pipeline to transport concentrate, the risk of concentrate spillage in the marine environment, and aquifer drawdown in the vicinity of the mine. This paper discusses these issues with emphasis on the context of the relationship between the Pasminco Century Project and Gulf communities. Environmental safeguards are discussed, including those that arose out of the negotiations regarding Aboriginal native title.

Jan 1, 1998

By H Benzer

Grinding clinker to finished cement consumes more energy than any other comminution process. World production of cement in 2009 was 2840 million tonnes and the energy required for comminution was 40-60 kWh/tonne depending on the clinker characteristics and the fineness of the finished cement. Machines used include single and multi compartment ball mills, HPGRs, vertical roller mills, centrifugal air separators, V separators, screens and crushers. The circuit most commonly used consists of a closed circuit HPGR followed by a single compartment ball mill and an air separator, and in operation the variables are adjusted to obtain maximum throughput with no loss of quality of the separator fines.A common objective in cement plants is to reduce energy consumption without affecting the particle size in the finished cement and simulation is used as one procedure to achieve this. Models are now available for all the machines commonly used in clinker circuits and circuit optimisation studies using simulation have been carried out in many plants leading to decrease in energy consumption per tonne of cement. In this paper the models used will be discussed briefly and several case studies will be reviewed which will highlight the effect of change in ball size in a two compartment mill, the role of the HPGR in an HPGR – ball mill – air separator circuit, and the use of a high intensity vibrating mill for producing finished cement with high additive ratio.

Aug 8, 2011

By S Youds

The backfilling operation at Olympic Dam mine supports a 9.8 Mtpa underground Long Hole Open Stoping (LHOS) operation. It involves a combination of Cemented Aggregate Fill (CAF), surface rockfill and underground rockfill. The fill material is introduced from the surface via boreholes into the top of the stopes. Due to the deleterious effects of the dust and the thickness of the atmosphere in the stope it is not possible to view the filling process either at optical or infrared (IR) wavelengths. The need for a means to measure the filling process is driven by the placement of both rock and CAF fill in the stopes. The large volumes and high relative cost of CAF makes the minimisation of CAF fill a business priority. Incorrect filling can lead to the sterilisation of ore reserve. The use of millimeter wave radar to view through the haze to give real-time data on the relative positions of the different fill masses is being developed as an in-stope fill monitoring device. This paper reviews the salient points of the technology and its potential use in the backfilling operation at Olympic Dam. The broader potential of this technology for use in the mining industry by æseeingÆ through water and dust laden environments such as that found in stopes and ore passes is also discussed.

Jan 1, 2002

By A Satyanaga, H Rahardjo, K G. Mercer

The soil-water characteristic curve (SWCC) is one of the most essential soil properties in unsaturated soil mechanics. The water flow and storage characteristics of an unsaturated soil are closely related to the amount of water contained in the pores and the negative pore-water pressure in the soil. These are both in turn, related to the particle-size distribution and the plasticity of the soil. The SWCC is obtained by laboratory testing which is difficult to perform, costly and time consuming. There is a significant advantage in establishing typical SWCC envelopes for different soil types from a geotechnical design and analysis viewpoint. This paper presents some of the research work undertaken by UWA and NTU to develop SWCC envelopes for soil types classified in terms of the ASTM D2487 Unified Soil Classification System (USCS). This was done by establishing a large database of soils from across the world, classifying them according to ASTM D2487 and undertaking SWCC testing for each soil. This paper presents the SWCC test results from a selection of three of the most common soil classifications encountered in geotechnical engineering practise.CITATION:Mercer, K G, Rahardjo, H and Satyanaga, A, 2018. The development of soil water characteristic curves for soil types classified according to the USCS, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 263–273 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

Excessive use of computers in teaching, especially in self-learning programs, may destroy creativity and initiative. It is essential that engineers remain innovative to develop new technology. Safety legislation may have hindered the Development of mine managers. It may be necessary to develop two distinct streams of mining engineers. One should be biased towards human relations and safety, to 'be a certificated mine manager, and the other should be mathematically based as a high-technology mining engineer who would not necessarily qualify for a certificate of competency without a postgraduate course.

Jan 1, 1986

By Wang J, Ma Y, Jia H

The Hedong Gold Mine is located in the Yan(ai area, tihandong hroo%ill, e. China. It is an underground mine with an annual gold output of some 700 0(H) grams. The orebody is located on the edge of the Wanger Shan metamorphism zone, and the hangingwall of orebodies is thus defined by a prominent set of fractures. The proximity of the metamorphism zone and the inclusion of the fracture set ensure that both the orebody and the country rocks are unstable. The main orebodies dip at an angle of between 40 to 45¦, with a strike length of 160 metres and a horizontal width of 50 metres. Surface subsidence in the area is not permitted. Cut and fill mining is usually practiced. As the mining operation proceeds to greater depths, the ore grade is diminishing and it is necessary to find a more efficient stoping method. Sublevel open stoping with sequential extraction and filling of each sublevel has been designed and applied in situ. This new mining method is called 'sublevel open and fill stoping method' in the mine. Experience to-date is that new mining method is Satisfactory.

Jan 1, 1998

In process industries, time-dependent random fluctuations of raw material characteristics and mass flow rates in bulk material or pulp flows cannot be always prevented for different reasons, eg because of the geological situation (no uniform formation of the deposit) or/and because of technological reasons (segregation in bunkers or on stockpiles). Since a long time, there has been practical experiences that such fluctuations can have negative consequences, eg: ò fluctuations of the final products characteristics, ò higher expenditure for process control, and ò worsening of technological characteristics (recovery, sharpness of separation etc). In the literature, there can be found a lot of details as to, eg the improvement of the sharpness of separation in a jig in dependence on the raw material blending (Kubitza, 1981; Gathen, 1983) or the decreasing flotation recovery with increasing raw material characteristics fluctuations in iron and potash ore processing plants (Bubnova, 1978). Up to now, however, these consequences of random fluctuations, eg on the separation efficiency were not predictable theoretically. It could be shown by means of the general model for mechanical macroprocesses (Graichen, 1989), that the reduction of input fluctuations passing a blending facility can be calculated in this way. In this example, the steady state of the process is the wanted one, but, in general, the model is able to describe also non-steady states of the process regarded. On the other hand, the general model of mechanical macroprocesses has been used successfully for modelling separation processes, eg cross-flow and air classification (Molerus, 1969; Neesse, 1991; Senden, 1979; Tichonov, 1973). That is why it was tried to model the influence of input fluctuations on the separation efficiency, that means, the impact of non-steady states - as a consequence of random fluctuations - on a separation process. The models discussed in the literature are related nearly exclusive to the steady state of the process. The reasons for that lie in the (relative) simplicity of the models and the fact that the steady state is aimed at by means of blending processes under practical conditions - because of the advantages mentioned above. These models cited have proved to be superior to other models, since the basic general model for mechanical macropocesses makes possible the consideration of turbulence acting in the process unit and influencing the separation process essentially. This is valid also for modelling the turbulent cross flow classification, applied to mechanical classifiers and hydrocyclones, where the correspondence between the separation characteristics (cut size, separation sharpness) calculated and determined experimentally is much better than for other models.

Jan 1, 1993

By Lama RD

The paper outlines the development in the control of dust in Australia over the last 20 years. Factors influencing dust make at the faces are discussed. The effect of high production systems is analysed. Changes in dust standards and results of dust sampling on longwalls and continuous miner panels are given. Research conducted on air curtains and water infusion on dust control on longwall faces is presented along with recommendations for future research. It is found that both dust curtains and water infusion can cut dust mak by 50" each when applied separately.

Jan 1, 1988

By Koppe J. C, Costa J. F C L

This paper compares different results for overburden volume estimation assisted by geoestatistics, particularly using kriging methods. The main goal is to obtain the most reliable digital terrain model for the calculation of the overburden volume. The data was collected on an irregularly spaced grid and interpolated values were calculated to provide a denser, more regular data set before volume estimation. The field work was developed at the Butia-Leste Coal Mine, southern most Brazil, where an accurate survey was done using a total station theodolite with electronic data collector. The study was developed in five main steps: data acquisition, exploratory data analysis, spatial continuity measurements, point and block kriging estimation and verification of the results. Data acquisition was carried out on a 5 x 5 in grid. This dense grid provides an exhaustive data set of the real terrain against which data subsets can be compared for the various interpolation procedures and volume calculation. This provides an interesting insight into the influence of the number of data on the estimation error. Univariate statistics were used to compare each data subset and the exhaustive dataset. Ordinary kriging on the data subsets followed by contouring was carried out using Geoeas and Surfer software respectively. A subroutine written in C provided the link between the files generated in Geoeas and subsequent contouring routines embedded into the Surfer package. Omnidirectional and directional variograms were modelled defining the parameters for kriging estimation using Geoeas. Different variogram models were checked through cross validation prior to kriging. A comparison between the magnitude of the differences in volumes calculated with the different DTMs was attained. These final result indicates the sensitivity of the volume obtained to the number of data points. As the number of data points increases the estimation error decreases, but at some point there is no significant decrease in the final volume with the collection of additional data.

Jan 1, 1995

By Morley I. W

Offshore minerals legislation has been introduced to provide jurisdiction over the exploration and recovery of mineral resources, particularly petroleum, from the territorial waters and parts of the continental shelves adjacent to coastal states. Ratificat- ion of the 1958 Geneva Conventions on the Law of the Sea has provided some measure of international agreement amongst signatory powers. Because the relationship of the Australian States to the Commonwealth in their federal system, the Australian offshore petroleum legislation is of particular interest. The customary role of the States in mineral resources management, which has extended to the offshore, is under challenge from recent unilateral Commonwealth Government legislative actions in the fields of mineral resources jurisdiction. Environmental considerations provide an additional issue, as yet unresolved, with the delay in submission of the Report of the Great Barrier Reef Petroleum Drilling Royal Commissions

Jan 1, 1974

By Miovski P, Hooft P. V

In the majority of recently commissioned gold mines granular activated carbon is used to adsorb gold from alkaline cyanide pulps or solutions. At the same time the carbon also adsorbs many other inorganic and organic species, most of which lower the activity of the carbon. Removal of these foulants is necessary before the carbon is reactivated and recycled. Standard practice for re- storing carbon activity involves high temperature treatment in a kiln - an apparently straightforward unit operation which is not always satisfactorily carried out. This paper presents the results of some fundamental work carried out on the thermal reactivation of carbon in a laboratory rotating pot kiln. The effects of temperature and steam addition on carbon activity were examined and compared with the activity of carbons obtained from a number of commercial kilns. Carbon was also reactivated using a small-scale Rintoul Furnace in which carbon was resistively heated by the direct passage of an alternating electric current. It was established that both elevated temperatures and the addition of steam to hot carbon generally enhanced its activity although peat-based extruded carbons responded a little differently to coconut shell types. Other measurements made included the weight loss and the hardness of carbons as a function of reactivation conditions.

Jan 1, 1987

Coal mining in the Bulli seam in the Southern Coalfield in New South Wales has experienced the dangers of outbursts of coal and gas. These incidents present a major risk to the safety of mine workers and consequently a threat to the overall viability of the mining operations. Since the occurrence of a major outburst incident in the South Bulli Colliery in 1991 involving three fatalities, the primary contributory factors associated with coal/gas outbursts in the Bulli coal seam have been identified and a strategy for the management of the outburst risk has been formulated by the cooperation of mine operators, mine workers and the Department of Mineral Resources. Utilisation of risk management techniques in combination with modern gas drainage technologies and geological control methods have led to the formation of this effective outburst management plan. Clause 15 of the Coal Mines (Underground) Regulation 1999 in NSW has made it mandatory in an area of outburst to carry out mining in accordance with a code or guidelines developed for mining in outburst prone areas (DMR, 1999). In this paper an outburst management system is discussed which was developed for collieries in the Southern Coalfield that brings together all the available information including past experiences and risk management techniques in a documented form in order to maximise safety of mine workers. It is concluded that since the introduction of the outburst risk management systems in the Southern Coalfield in 1994 considerable reduction in outburst incidences have been experienced.

Jan 1, 2003

I must tell you at the outset that I come to this conference deeply disturbed at the `role of Government in international dealings in mineral and energy resources'. I am disturbed by the confusion that now passes for policy. I am disturbed by the short- range view of critical problems taken by a majority of Governments. I am equally disturbed by the even shorter range of view taken by a growing army of industries. Many of them clamour for Governments to solve their problems in a specific way, with little regard for any other sector but their own-and with even less regard for the fact that every time a Government takes over some of their responsibilities they surrender some of their freedom. I would not say that longer range views don't exist. But I would say that they don't prevail at the present time. Instead, we are seeing the con- stant development of many policies for individual problems which don't tackle the fundamental causes. We must get back to basics without delay.

Jan 1, 1978

By M Ranjan, C R. Borra, P Palai, P P. Sahoo

Change in mould slag composition during casting of medium alloy steel is caused by the redox reaction between molten steel and mould flux. Mould flux generally contains a certain amount of SiO2, but elements such as Al, Mn and Ti in high/medium alloy steels reduce SiO2 in the mould flux, causing remarkable changes in the composition of the mould slag. As a result, the properties of the mould slag change greatly as continuous casting proceeds. This causes casting instability, process abnormality and casting defects. Effect of Ti as an alloying element in steel on mould slag is studied extensively through high temperature laboratory measurements and plant measurements. TiO2 gets picked up by the mould slag up to 3 per cent during casting a steel grade containing 0.1 per cent Ti. This changes the mould slag composition and results in decreasing the slag viscosity by up to 10 per cent and decreases slag break temperature by 30–40°C.

Aug 21, 2024

The mobility of radionuclides released into aquatic, terrestrial and subsurface environments by mining, industrial processes is an area that deserves significant scientific attention. The presence of microorganisms in these environments can influence the transport of radionuclides. Free-living microorganisms constitute mobile suspended particles that may have a radionuclide sorbing capacity higher than that of the environment. Radionuclide transport will then proceed faster with than without microorganisms. In contrast, if the majority of the microorganisms are growing in biofilms on surfaces, transport of radionuclides may be reduced. Microorganisms can directly sorb radionuclides either within the cell structure or on the cell wall. Radionuclides could also be sorbed by minerals precipitated by microorganisms. Microorganisms produce complexing agents that can influence radionuclide mobility. The involvement of microorganisms in biogeochemical processes is related to their ability to include various chemical elements and their combinations into biochemical redox reactions. Microorganisms can alter the extent of radionuclide oxidation that results in their deposition as a result of the formation of insoluble forms. Some studies have shown the bioremediative potential of stimulating reducing bacteria to use some of the soluble radionuclides as electron acceptors and thus precipitate them out of solution. The microbial involvement in providing a barrier for radioactive element migration (uranium, technetium) and the formation of ores (eg uranium) has been justified. The mediated impact of microbial activity on radionuclide migration occurs through its effect on the ambient geochemistry by geochemical speciation changes, pH changes and changes to the ambient redox potential. As the mobility of many radionuclides depends on the pH and redox potential of the environment, these microbially mediated geochemical changes can influence radionuclide migration through changes to both the dominant radionuclide species and mineral phases.

Jan 1, 2004

By I Ametov, G Levay

It is now common practice to use substantial amounts of recycled water in mineral processing plants to minimise both environmental discharge and withdrawal of fresh water from often limited water resources. Recycled water additions to process water are frequently obtained from sources such as tailings dams, tailings thickeners and concentrate dewatering. It has been suggested for some time that addition of recycled water to process water will impact the quality of the process water and that changes in water quality may influence flotation performance. To date, investigations of process water quality changes as a result of water recycling have been limited and as a consequence there are very few data available to substantiate these ideas. Thus the impact of recycling on process water quality remains largely unquantified. Over recent years we have conducted water quality studies at a number of mineral flotation plants with varying degrees of water recycle. This paper describes the results of these investigations, including data which suggest that build up of salinity due to recycling while it occurs, is reduced by fresh water make-up. The fate of flotation reagents such as collectors, promoters, frothers and flocculants during process water recycling has also been investigated. Results show that process water concentrations of these reagents vary from plant to plant, but that, with the exception of frothers, most reagents are generally removed from the system through mineral adsorption. In general, the results of these investigations suggest that recycling process water will not result in continuous increase in solute concentrations as appears to be the commonly held view.The effects of changing water quality on flotation can vary. In many cases, flotation conditions can be optimised to suit the water quality, while in others, treatment of the water may be necessary to obtain acceptable plant performance.

Jan 1, 2009

By P Vaikkattil, K Li, J Bullock

Unlocking maximum value is essential when designing a stope and the associated drill and blast packets. This is becoming increasingly important at Olympic Dam as the operation continues to expand south into the new mining areas away from existing infrastructure, increasing operating costs and required capital investment; into areas with less competent ground conditions, requiring smaller stopes and increased interactions. The introduction of Orica’s WebGenTM system is one way in which Olympic Dam can continue to unlock value into the future by decoupling traditional drill and blast limitations. The Lime 390 stope was the first stope at Olympic Dam to trial the new technology on the last blast packet. This paper reviews the drill and blast design of the Lime 390 stope, including the technical and operational challenges associated with the stope and the trial of the Orica’s WebGenTM system for the firing of the last blast packet.

Mar 15, 2021