Search Documents

By S Fidler

Underground coal gasification (UCG) is a process by which coal is converted in situ to a combustible gas that can be used as a fuel or chemical feedstock. The process has been used in commercial-size projects in the former Soviet Union for more than 40 years, while significant national research programs have been undertaken in the United States and Western Europe. The Chinchilla UCG project is located at a site southeast of Chinchilla in Queensland. The UCG operation commenced in December 1999. A controlled shutdown of the process was initiated in January 2002 and successfully completed in April 2003. The process is currently under conservation and ready for restoration of gas production for commercial use in the near future. Groundwater plays an important role in the gas formation process during UCG. Most of the process water required for chemical reactions is usually derived from the coal seam itself and from surrounding aquifers. If insufficient water is available for chemical reactions the UCG gas will contain reduced concentrations of combustible components, and conversely, excessive water influx into the process area would cool down the reactor and thus limit the energy available for gas production reactions. Because of the importance of groundwater in the gasification reactions, and the potential to contaminate groundwater if the process is not correctly controlled, it is essential to predict and to control the groundwater influx into underground gasifiers during and after underground gasification. Control of groundwater requires a thorough understanding of hydrogeological conditions in the vicinity of the gasifier in order to be able to predict inflow rates, and constant monitoring throughout the process of water production rates and groundwater pressure in the coal seam and adjacent aquifers. Hydrogeological testing and groundwater monitoring in the vicinity of the UCG operation commenced six months in advance of its initiation. Monitoring of groundwater pressures in the vicinity of the gasifier have also been undertaken using vibrating wire piezometers installed in the coal seam at varying distances from the gasifier. This paper presents the results of the hydrogeological testing and groundwater quality monitoring carried out at the site, which show that it is possible to operate a UCG process without uncontrolled impacts on groundwater.

Jan 1, 2003

By R Steinhaus, D M. Frantois-Bongarton, P W. Cleary, G K. Robinson, M D. Sinnott

Multotec Process Equipment and Dominique Frantois-Bongarton have a patent for a mineral sampling device, which they call a æTrue-Belt SamplerÆ. This uses a plough, which is rotated about an axis parallel to a conveyor belt to throw material off the belt. A fixed sample cutter takes a sample from the material thrown off the belt.Discrete element modelling has been used to consider a range of plough designs, plough speeds, positions for the cutter relative to the plough, cutter apertures, cutter designs and frictional properties, prior to the building of a physical prototype. This modelling work will be discussed, both as an illustration of the role of modelling in the development of new materials-handling devices and in order to explain the likely strengths and weaknesses of this new type of sampling device.CITATION:Robinson, G K, Sinnott, M D, Cleary, P W, Steinhaus, R and Frantois-Bongarton, D M, 2012. Modelling of a ætrue-belt samplerÆ - A new device for sampling from a conveyor belt, in Proceedings Sampling 2012 , pp 33-40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By Walker BV

Mining activity has been an integral component in the New Zealand economy since the early days of European settlement. Recently in common with other Pacific Rim countries there has been a resurgence of investment in gold. A sustained and increasing exploration effort has resulted in the rapid development of alluvial gold mining operations, a number of hard rock gold discoveries, and a general optimism about New Zealand's prospectivity. New Zealand's attitude to mining development, in particular hard rock gold mining is influenced by high environmental values and a concern, largely through absence of examples, that modern mining may not perform to community standards. While these environmental concerns are wide spread there is a growing realisation that gold mining, if properly managed, can take place within acceptable environmental standards and that it has the potential to contribute significantly to New Zealand's economy. New mining developments have an important role to play in this process. The mining industry in New Zealand is now at a crossroads. Having invested substantially and confirmed the potential for gold mining developments it has found itself in a rapidly changing economic environment as the Labour Government puts in place a number of fundamental economic reforms. The reforms are intended to free up the economy removing the rafts of subsidies and protective measures which have stultified initiative and growth. A fundamental reform of the public service has been initiated including corporatisation of trading activities and the establishment of a Department of Conservation to administer estensive areas of Crown land. Both petroleum and mining taxation are being reviewed with the intention of creating a more neutral competitive environment. Mining legislation is also being re-examined with both efficiency and equity objectives. While the current environment is characterised by uncertainty and rapid change, the outcome will be a more market-oriented stable policy environment, to the mutual benefit of the industry itself and the New Zealand Community.

Jan 1, 1987

By K Tanguturi, B Belle, R Balusu

Management of high rates of goaf gas emissions between 4000 and 6000 L/s of methane gas in longwall panels is a challenging issue, particularly in start-up areas of the panels. There is a need for investigation of the effect of various goaf gas drainage concepts and techniques, and development of effective gas drainage strategies for management of high goaf gas emissions in start-up areas of the longwall panels. This paper presents the results of various computational fluid dynamics (CFD) simulations that were carried out to investigate the effect of different goaf gas drainage strategies and combinations for gas management in the start-up area of the longwall panels. Results indicated that the gas (methane) concentration in goaf holes on the tailgate (TG) side vary between 50 and 75 per cent under the simulated field conditions with flat coal seam gradients. The results also indicated that operation of more goaf holes for draining the goaf gas on the TG side results in high ingress of oxygen and further reduction in gas concentration in goaf gas drainage holes. The simulations also included scenarios with goaf gas drainage holes on the maingate (MG) side, TG cut-through seal and near the start-up area. This paper presents the results of various goaf gas drainage strategies and discusses the effect of various combinations in order to develop effective goaf gas drainage strategies for gas management in start-up areas of the longwall panels.CITATION:Tanguturi, K, Balusu, R and Belle, B, 2015. Development of goaf gas drainage strategies for start-up areas of highly gassy longwall panels, in Proceedings The Australian Mine Ventilation Conference, pp 251–258 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By P Bartlett, K Naidoo

Premier Diamond Mine is planning a new, mechanised, block cave, with a production level approximately 1000 m below surface. A high degree of tunnel damage is expected, due to stress and the relatively low in situ strength of kimberlite. An evaluation of the timing of tunnel excavation, tunnel size and spacing has been carried out to define critical parameters for planning layouts and development schedules. Extensive use has been made of three-dimensional FLAC3D numerical models, calibrated against known rock mass behaviour at 650 m depth, to examine the influence of undercut advance on production level excavations. These were able to represent the effect of stress rotation on tunnels during undercut advance and the effect of an inclined undercut. The analysis has provided guidelines that are possibly applicable to any deep block cave layout. The choice of drawpoint layout is of considerably less significance than the proportion of ground extracted on the production level elevation prior to advancing the undercut. The analysis shows that damage to production development will be potentially severe if it is all excavated prior to advancing the undercut, or is mined directly beneath the undercut face. The development of the main production tunnels alone ahead of the undercut may be feasible, but no breakaways should be put in as they appear to trigger a rapid increase in the severity of damage. The optimal sequence is when all production tunnels are developed at least 10 m in plan behind the undercut, where the induced peak field stress is less than 20 MPa and a maximum support pressure of 100 to 500 kN/m2 is require to contain movement. The assessment showed that the conditions are not significantly improved by increasing drawpoint spacing from 15 m to 18 m. The vertical spacing between the undercut and production level beneath is investigated. Provided production level development is carried out beneath the undercut, there would appear to be little benefit in increasing the vertical spacing between the undercut and production level beyond the current 15 m to 18 m.

Jan 1, 2000

By Kajioka H, Nakamura Y

Na2CO3 is a powerful flux for both dephosphorization and desulphurization in oxidizing atmospheres. In order to study refining with Na2CO3 and the nature of the Na2CO3 slag itself, hot metal (4Kg) was melted in Al203 crucibles in a high frequency induction furnace and oxidised with oxygen under Na2CO3 slag. The behaviour of Na2CO3 at high temperature was observed by thermobalance. It was found that dephosphorization ceases in a few minutes and [,P] after refining is easily lowered to less than 0.010%. [%P] after refining is affected by [Si], [P] of hot metal, the refining temperature and the consumption of Na2CO3. Desulphurization also ceases in a few minutes but it shows curious behaviour, increase of [S], decrease of (S) and increase in sulphur lost, during the latter half of run. [%S] after refining is also affected by [P] of hot metal, the refining temperature and the consumption of Na2C03o

Jan 1, 1980

By G Partington

A regional scale prospectivity model was developed for Papua New Guinea (PNG) to identify areas of porphyry Cu-Au mineralisation. Weights of evidence modeling techniques were used to determine spatial correlations between porphyry Cu-Au mines and predictive maps created from available spatial data. These predictive maps were then combined into a final prospectivity map. Despite limited regional scale data the model has successfully identified areas of known porphyry mineralisation as prospective and has also identified areas where new mineralised systems may be discovered with further exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Dunne RC

The physical properties of an orebody require determination for virtually all mining projects, new and existing. The extent and regularity of such determinations being subject to the size and homogeneity of the orebody. Such properties have an impact at the design stage of new plants, with respect to equipment specification, and thus effects capital costs; and also impacts on the operating costs of new and existing plants, with respect to power consumption, production levels and part replacements. All of these can severely alter the bottom line and can be the determining factor in the economic viability of many projects.This paper examines some of the most common properties that are measured, the procedures utilised in determining these properties, and their variability under conditions of reproducibility, and to a lesser extent repeatability.

Jan 1, 1997

Passive systems for the treatment of acid mine drainage (AMD) are typically more economic in the long term than active systems. Various flow charts for treatment selection have been prepared by scientists in the USA, however, they have typically not included a variable important at New Zealand AMD sites on the West Coast: topography and available land area. Very steep topography, dense and often protected vegetation (and animals such as snails), and a high-rainfall climate result in AMD with very high flow rates in locations with very limited space for remediation. Flow charts specific to New Zealand have been prepared which accommodate topography and available land area. Parameters necessary to use the flow charts are iron and aluminium concentrations, pH, ferrous to ferric iron ratio, dissolved oxygen concentration, topography and available land area. Prior to full scale construction, is it recommended that flow rates be quantified, small-scale trials be conducted, and cost, effectiveness, limitations, and risk of failure be reviewed for various options. One full-scale remediation system has been installed in New Zealand based on this methodology and another is planned. The performance of these systems, as well as future systems to be installed, will be used to validate these treatment system flow charts.

Jan 1, 2007

The new South Australian Mining Act be came operative in July, 1972. It provides appropriate updated legislation covering pro- specting, exploration and development of mining properties. Anomalies inherent in earlier legislation which provided for the private ownership of minerals in certain areas have been overcome by the vesting of the property in. all minerals in the Crown. Appropriate transition- al and long term provisions protect the right of individuals thereby divested of their former property in minerals. In the matter of pro- specting for and quarrying of extractive minerals, the rights of landowners have been formally recognized, and the concept of rehab- ilitation of quarried areas has been introduced utilizing money provided from a royalty fund especially established for this purpose. Con- temporary company exploration practice is catered for under a new exploration tenement and at the same time the legislation makes provision for the interests of individual pro- spectors. Special provisions have been enacted to cope with the rapidly developing opal mining industry. A feature of the new Act is the introduction of legislation which recognizes enlightened contemporary thinking on the matter of environmental considerations. The Act has also extended the powers and widened the jurisdiction of the Warden's Court. In general,

Jan 1, 1974

By J Johansson, J Lööw

There are many reports about how the new technology will affect our work, sometimes they are utopian but often dystopian. Most of the visions describe the industrial work, while the work of the managers does not seem to be affected. In this article, the authors will discuss how the new technology within the concept of Mining 4.0 changes the conditions for leadership and the work of managers in a modern mining industry.

Sep 1, 2024

The cloud transform simulation is a technique used to generate realisations of correlated attributes. The principle of this technique is to partition the scatter diagram between the input attributes into several interval classes and derive for each class a cumulative distribution function (CDF) using only the data pairs of the scatter diagram in that class. The simulation then proceeds like a traditional Monte Carlo simulation but using the derived CDF in each class.The cloud transform simulation has the advantage of being a simple and fast technique that is able to reproduce the uncertainty in the relationship between the two input attributes regardless of whether the relationship is linear or not. However, the technique has three major drawbacks. First, the number of classes has an impact on final simulated results and there is not a robust approach to define such number. Second, simulated results exhibit some saw tooth variations that are unrealistic and third the reproduction of the spatial continuity of the simulated attribute is not guaranteed.This paper presents the use of the quantile regression approach in order to overcome the first two disadvantages of the cloud transform simulation. Details of the technique and how it can be coupled with the cloud transform simulation are presented along with a real case study.

Sep 26, 2011

By T Clemens, D Trumm

Adopting environmentally acceptable practices in New Zealand is a crucial requirement for mineral wealth development. Recent planned expansions in the coal and gold industry have increasingly placed mining in the media spotlight. A lack of appropriate standard environmental guidelines has resulted in inconsistent responses and assessments of current and proposed mines. These inconsistencies have lead to delays in decisions on developing economic mineral deposits that may have only minor short-term impacts, and have also allowed unacceptable environmental management practices to continue elsewhere. A research collaboration between CRL Energy, Landcare Research, University of Canterbury and University of Otago aims to provide regulator groups and the mining industry with a unified approach to the requirements of the Resource Management Act 1991,the legislation that largely drives the nationÆs environmental policies and guidelines. The tangible outcome of this research program will be water quality and impact management guidelines integrated into a decision-making framework. The result of this unification will assist in the development of viable mineral deposits and minimise environmental impacts. The framework will be derived from a synthesis of three objectives. Objective 1 identifies potential water quality impact. This objective is based on a targeted geochemical study of the lithology and waterways of the West Coast and Southland regions. Objective 2 categorises the degree of impacts on the ecology of receiving aquatic ecosystems and determines the processes that drive aquatic ecosystem recovery. Objective 3 identifies best strategies to sufficiently manage impacted ecosystems, and to prevent future unacceptable impacts. Wide consultation with representatives of the mining industry and regulator groups will occur frequently during the development stages of the framework. It is anticipated that this multidisciplinary approach will provide a robust and coherent, standardised system that will assist in achieving industry and environmental targets.

Jan 1, 2004

New and more cost-effective methods of haulage and hoisting will be needed to develop the underground mines of the future. A review of the development of technology since the 1950s shows that once mechanised equipment became available it took 25 years for appropriate mining methods to be developed and the equipment made reliable, then a further 25 years to reach todayÆs level of automation and reliability. Suggestions are made about possible areas for ongoing research with the observation that there is little research worldwide into disruptive technologies. A call is made for better organisation and presentation of the opportunities and potential benefits of new underground mining technologies.

Jan 1, 2005

By M I. Pownceby, M A. Rhamdhani, S Purohit, G Brooks

The current practice of magnetite ore agglomeration involves high temperature oxidation roasting (typically at 1200–1350°C) of magnetite to hematite phase in order to improve the strength and reducibility of pellets. The requirement to pre-oxidise the magnetite before introduction to an ironmaking plant increases the CO2 emissions generated during the ironmaking process. In our previous papers, a novel, alternative agglomeration route for magnetite ores was presented where magnetite was converted to a reducible CaFe3O5 (CWF) phase through the addition of lime to produce a Lime-Magnetite Pellet (LMP) feedstock that can be directly charged to ironmaking units. The LMP process eliminates the magnetite oxidation stage, thereby reducing the CO2 emission during ironmaking. The concept was tested by thermodynamic calculations, high temperature experiments and scaled-down pilot scale test work. In this paper, larger scale synthesis of halfstoichiometric LMPs (1 mole of Fe3O4 and ½ mole of CaCO3) were prepared using a balling drum, followed by overnight drying at 110°C and induration at 1050°C for two hours. The LMPs were analysed using X-Ray Diffraction and Scanning Electron Microscope techniques for phase and microstructure characterisation. The LMPs were found to have 14–15 wt. per cent of CWF phase when indurated under a CO2/CO ratio of 8.5:1. Pilot scale testing of the LMPs was conducted following ISO standard test procedures. The test results indicated the LMP’s had a Reducibility Index (RI) of over 91 per cent, a Tumbler Index (TI) of 87 per cent and a Reduction Degradation Index (RDI) of 4.6 per cent. The results indicate LMPs may be useful as an alternative feedstock to ironmaking processes that would result in lower overall CO2 emissions.

Nov 8, 2021

By G W. Wilson

Rehabilitation of tailings impoundments is one of the most challenging aspects in mine closure, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modelling for this hydrologic system becomes difficult, as numerical models capable of analysing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings. This paper describes the development of a flux boundary model that enabled accurate modelling of the unsaturated zone in the tailings impoundment at Kidston Gold Mine, Queensland, Australia. The technique made it possible to accurately predict the spatial variation of infiltration to the tailings as a result of the presence of the phreatic table. The conceptual model defines the boundaries for the Kidston tailings dam, based on a generalised cross-section through the dam. Firstly the shape of the top boundary is described as a function of the particle size of the tailings associated with particle segregation that occurs due to the hydraulic placement of tailings. This function was rigorously tested using in situ infiltration tests and laboratory materials testing. Defining the bottom boundary of the section, ie the phreatic level was done by physically monitoring the phreatic level with 42 piezometers strategically located on the tailings dam. Analysis of this data led to the fixing of this bottom boundary through the introduction of a function that mimicked the shape of the phreatic level. The material properties of the surface layer, specifically the saturated permeability that would govern the infiltration/exfiltration rates of moisture through the top boundary layer were defined on the basis of extensive field and laboratory material testing. A function for the saturated permeability was developed on the principles of particle segregation. Finally a procedure is described for the application of the new conceptual model for the evaluation of the spatial infiltration to a tailings surface using the rigorous one dimensional surface flux boundary code SoilCover. The solution of the calculation described above was then used as the top boundary condition in conventional three dimensional saturated/ unsaturated flow codes, and verified against measured seepage rates from the tailings impoundment under drains. It was concluded that the developed spatial flux function was in deed a most rigorous representation of reality. Although the methodology presented here was applied to the Kidston tailings impoundment only, the authors believe that the principles are directly transferable to any tailings impoundment that has a varying phreatic zone thickness due to the presence of a pond. The mathematical equations describing the typical cross-section would be site specific, but the approach and ultimate solution methodology would be directly transferable.

Jan 1, 2003

In Finland fogging in mine ramps is a common problem. Fog forms when warm and humid exhaust air moves upwards the ramp, where the skin temperature of surrounding wallrock decreases to about 10¦C. Changes in fog thickness and lengths of fog-filled parts of the ramp depend at least on climatic conditions outside, diesel equipment usage in the mine, and the length of working sequence at a time. In this study fogging problems in three different mines, namely Orivesi mine, Louhi mine and PyhSsalmi mine, with different ore types, different layouts, and different depths are presented and compared. All these mines use diesel equipment and the ramp is used as an exhaust air route. In two of these mines the ramp is used as a haulage road and in the other for supply and repairing, checking, and surveying purposes. Measurements of humidity, temperature, air velocity, and dust content were performed in these mines. The measurement results, as well as field observations are presented, compared, and discussed. The results show that fog is observed in areas with high relative humidity values when air temperature and dew point temperature are less than 3¦C apart from each other. Air velocity values were high in many areas. In addition, measured particle concentration values were mainly high in areas, where fog was observed. A short literature review of recent fog formation studies is also presented. It demonstrates the complicacy of the fog formation process. Similarities and differences concerning fog problems in the ramps are found and presented. As already a lot of new information is gained, the continuation of research is considered plausible to find more economical ways of solving and preventing this problem in the future.

Jan 1, 2005

Development of a New Dry Density Separator for Fine-Grained Materials

Sep 13, 2010

Following a period or small-scale activity a joint venture was formed between Ceramco Limited of New Zealand and Georgia Kaolin Company of USA. The initial concept was to process clays for the paper industry but it soon, became apparent that insufficient markets were attainable for the grades of china clay that could be produced for an economic unit. Ceramco Limited acquired the Georgia Kaolin interest in 1975 and proceeded to search for a market, of markets, that would: 1. utilise the unique properties of the product, and 2. enable a viable operation to be created. This paper describes the mineral deposits, the process, the properties of the product, and the marketing methods of New Zealand China Clays.

Jan 1, 1984

Tin mining has taken place in the New England region of New South Wales since 1872. Until fairly recent times there was little pro- vision made for environmental protection. Mining methods,which included ground sluicing and open cutting,had considerable environmental impact. Much of the topsoil was lost and there is little vegetation on the infertile and at times toxic, subsoil. Thus much of the lands disturbed by mining have not been stabilised and are eroding, causing extensive pollution of adjacent watercourses. There are more than 1500ha of abandoned tin mine sites in the New England, representing one of the worst rehabilitation problems in New South Wales and reflecting poorly on the mining industry as a whole. Recent tin mining operations incorporate progressive rehabilitation in their mining cycle. Topsoil is stockpiled and later respread. This topsoil contains a seed source, facilitating revegetation and thus stabilisation. The tin mining industry, under considerable cost pressures at present, is seeking a cost- effective revegetation technique. Most of the mines in the New England are situated in a forest environment. Trials have been conducted in the past using exotic pasture species with limited success due to the characteristics of the subsoil. Other revege- tation trials have used pine or eucalypt tree species. The cost of these techniques is a major disadvantage. Certain acacias species were observed colonising disturbed tin mining areas on very infertile subsoils. Acacias have a number of characteristics indicating a possible applic- ations in mine rehabilitation programmes.

Jan 1, 1987