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Alcoa of Australia's Western Australian bauxite mining operations in the Darling Ranges, south east of Perth, present major challenges in the control of air blast. The close proximity of rural communities and the face profile make the traditional methods of air blast control difficult. An extensive blast noise monitoring programme has been established. The develop- ment of a computerised blast noise prediction model and the establishment of a radiosonde weather balloon facility have reduced blast induced complaints by a factor of ten. The meteorological factors affecting blast noise transmission are discussed and examples are given of adverse weather condit- ions for the south west region of Western Australia.

Jan 1, 1982

By Baafi EY

Open cut mining in Australia is facing the greatest challenge in its history in attempting to compete not only with other operations internationally, but also with underground operations domestically. Most flat dip and shallow depth surface-mineable coal reserves have been depleted during the last two decades and new open cut operations must extract deeper coal deposits. As open cut coal mines move into deeper areas and the stripping ratios increase, the relative cost of overburden removal also increases. It therefore becomes even more important to design the mine around the optimum overburden removal scheme. The deeper mines are usually multi-seam operations with a more complex geology and with more geotechnical and hydrological problems. Deeper mines are subjected to greater problems requiring more detailed mine planning and design, such as selection of the optimum mining method and pit layout. In planning and design of such operations, the number of alternative methods which need to be considered is consequently greater.Dragline productivity and its stripping capabilities are directly affected by the selection of digging method, strip layout and pit geometry. Every mine has a unique combination of geological conditions. The operating methods that work well at one mine may not necessarily work at another site. Selection of an optimal stripping method, strip layout and pit geometry for a given dragline must be considered with respect to the geological conditions of the mine. With increasing geological complexity of Australian strip mines, it is becoming more important to use sophisticated techniques such as computerised mine planning methods to assist in optimising dragline operations.

Jan 1, 1998

In seeking to improve the economic performance of mines, the management or human aspects are usually seen to be quite seperate from, and more significant than, the technical aspects. There are obvious aspects of industrial relations, man-management, skills training and supervision that are currently the focus of efforts to improve the productivity and quality of the mining process. However technology also has a lot to offer. Analysis of the costs involved suggests that innovations leading to improvement in the productivity of the excavation and transport of overburden and the recovery of coal (both in the mine and preperation plant) can lead to improvements in the economic performance of a mine that may outstrip the obvious non-technical or management opportunities for improvement. While there are some innovations currently being investigated within the industry that relate to the design of mining equipment, the type of machinery being used in open cut mines has not changed dramatically over the last twenty five years. It is also likely that mining equipment will remain essentially of the same form in the forseeable future. If significant improvements to mining performance are to be achieved other than by futher increases in the scale of machinery, then we need to seek ways to operate these same types of machines in a more productive and controlled manner. This paper discusses the identification of mining processes the improvement of which is likely to have a significant effect on mining costs and performance. Some areas of current research are discussed and potentially fruitful areas for future development are identified.

Jan 1, 1991

High interest to basic-ultrabasic rocks is ex-plained by their specific, sutural, geotectonic po-sition and by deep level of generation of ultraba-sic magmas. These two factors allow us to treat this group of rocks as valuable source of informa-tion about the lower crust and upper mantle of the Earth. Basic-ultrabasic xenolith series is another source of information about the interior of the Earth. Detailed studies of the xenolith series give valuable material to geologists as to how endogenic deposits are fed and what is their source.Besides, the interest is explained by attempts to understand the relationship between basic-ultra-basic complexes and deposits of metalliferous and non-metalliferous mineral material.Absence of genetic boundaries in manifestation of metalliferous and non-metalliferous minerals, their temporal and spatial relationship allow us to treat the minerogenesis of ultrabasic complexes as a result of one ore-forming process manifested in Koryak-Kamchatsky, Sakhalin-Japanese, Ryukyu-Korean and Taiwan-Philippines island arc systems which re-present, in the opinion of the authors, one eastern Asian chain of the Pacific ore belt (Radkevich, 11)87).

Jan 1, 1990

By Huntington J. F, Green A. A

The quality of a photointerpreter's anno- tation of an image may be displayed by writing maps in which the pixels are shaded according to the number of times a pixel was seen to be on a feature. The map of grey tones is more valuable, if, for each grey level, a measure of quality is determined, which is the probability that a feature exists in a pixel of a given grey tone. From repeated annotations (at least four) of the same image by a single observer, it is possible to formulate a perception model which describes stochastic processes in the observer. From that model, it is possible to assign estimates of data quality for each observer to each grey tone. For two observers on the same scene, the 'mean' method of quantifying the grey levels is to assign a value equal to the mean of the ii,:lities for each of the two observers separately. For this example, the grey tones arr thus quantified at probability levels of 0.70, 0.80, 0.90 and 0.95.

Jan 1, 1977

By J E. Lynch

The Mt Leyshon gold deposit produced in excess of three million ounces of gold and considerable silver over a period of approximately 130 years. Most of this production occurred between 1987 and 2001. Mining commenced in 1872, however it was highly likely that Chinese miners were not only removing alluvial gold from the area but were also mining very rich æreefÆ gold. Records for early alluvial and hard rock mining do not exist, however gold production was probably considerable. In the early 1980s Marathon Petroleum (Australia) Ltd (MPAL) joint ventured into the Mt Leyshon area which had been held as a mining lease by Noranda Australia Ltd since 1968. Noranda at that time was concentrating its exploration effort on the Balcooma base metal prospect areas to the north of Charters Towers. In early 1982 MPALs parent company was taken over by US Steel. This led to an opportunity for MPALs Australian management to purchase all tenements and licences (except for coal, oil and gas) which were duly purchased for $US 1 million. At this time MPAL had a remarkable array of gold tenements (many of which were subsequently mined by other companies) and Mt Leyshon was considered to be the highlight. Early æseedÆ capital ($A 3.1 million) was raised with backers being the Bank of America, the NSW Government Superannuation Scheme, Westpac, private individuals and a Queensland grocery chain by the name of æJack the SlasherÆ.

Jan 1, 2004

The design and operating characteristics of the hydraulic cyclone elutriator were described in detail by Kelsall and McAdam (1963), and the method of operation of the commercially available version, the Cyclosizer, is described in the manufacturer's pamphlet (Anon). Complete details of the operating procedure are given in the relevant operating manual (Anon, 1964).The cyclones which form the basis of the Cyclosizer (Fig. 1) under normal operating conditions produce typical cut sizes of 44, 33, 23, 15, and 10 µm for cyclones one to five respectively for material with a specific gravity of 2·7. At the end of the selected elutriation period each sized fraction is discharged and collected for subsequent assay or analysis but all material rejected by the fifth cyclone (e.g. minus 10 \lm quartz) normally passes to waste. When this material is needed for separate study, although its amount and average analyses can be calculated by difference, it may be necessary to collect more than 250 I. of very dilute suspension, flocculate the solids, allow to settle, and decant off the supernatant liquid.This procedure is cumbersome and inconvenient and the simple technique to be described may offer some advantages. The temperature of the water fed to the Cyclosizer is maintained at a constant value for added reproducibility.PROCEDUREThe present overall treatment of the subsieve material (minus 37 \lm) fed to the Cyclosizer incorporated several refinements compared with normal operation and these may be best illustrated by anactual example. Material to be cyclosized (25 to 100 g depending on size distributIOn and specific gravity) is completely dispersed in water at 23 QC by vigorous stirrmg, using suitable dispersants if necessary, in a...

Jan 1, 1974

A number of suggestions have been made to improve the design of cells used for electro winning and electro refining of metals. Most of these designs have been aimed at increasing the current density used in order to improve cell capacity, although the purpose of some has been to produce electro deposited metals in a continuous manner. Improvements in the electrolyte flow pattern in conventional cells have resulted in an increase in the rate of mass transport of metal ions to the electrode surface; giving rise to lower concentrat- ion polarization and an improvement in the nature of the product obtained, Other cell designs are based on a moving electrode, usually a rotating disk, and these may include provision for removal of the product in a continuous manner, The maximum current density which can be used in an electro- lytic deposition process is determined by the limiting diffusion current, the physical nature of the, product, the purity of the product required and by the increase in power costs which result from the higher cell voltages, This paper examines the properties of an agitated bed of particles as an electrode system when used for a metal deposition Process,

Jan 1, 1969

By T C. McCuaig, D B. Mapleson

The Wannaway Deposit is a structurally modified komatiite-hosted nickel-sulfide deposit. Until recently, nickel sulfide accumulations surrounding the Widgiemooltha Dome had been studied with a focus on understanding volcanological aspects of komatiite flow regimes and nickel-sulfide accumulation. Although volcanological features can be observed at Wannaway they are overprinted by several generations of structures associated with multi-phase deformation of the Dome. On the mine scale, two significant deformational events can be distinguished that control ore distribution. The first deformational event is represented by the formation of a layer parallel foliation within the footwall metabasalt and boudinaging of the ore into two distinct orebodies (mega boudins) during a north-south compressional event. Evidence of a second compressional event (east-northeast-south-southwest) is defined by reverse > dextral thrust-folding of the ore zone. The latter deformational event focussed the sulfide ore into thrust front positions where folded ore sequences are mined with stope widths up to nine metres wide. Later stage compressional and extensional deformation phases are observed but have minor, localised effects on the geometry of the ore zone. Four orders of control on the geometry and distribution of ore are interpreted through a combination of primary and secondary features observed at Wannaway. Extending the structural aspects of the secondary overprint features into areas of potential mineralisation has not only defined targets for extensions to the Wannaway Deposit, but has also aided to delineate high grade mineralisation and aid mining decisions. Obtaining an understanding of the volcanological conditions of formation, and more importantly, the structural evolution of the Wannaway region has been an integral part in optimising production.

Jan 1, 2003

By D S. Stewart, K W. Keskimaki

The Henderson Mine has been utilising a continuous panel caving method to extract molybdenum ore since starting operation in 1976. In the past three decades since the mine was designed, many changes have taken place in underground technology as well as the general nature of the mining business. The impacts of larger scale underground equipment and automation are significant at Henderson and continue to reshape the nature of the enterprise. During the first years of operation in the 1970s, Henderson required almost 2000 employees to achieve full production, today only about 400 people are required to fully utilise the plantÆs capacity. The most recent change to the facility is the conversion from a rail haulage system to an underground crushing and conveying system that transports ore 25 km to the Henderson mill site. This change has required the introduction of large, rubber tired haulage trucks underground and the mining methods necessary to develop the large openings demanded by the trucks and underground crusher. The development of the underground crusher is also the first step to mining the final bottom horizon of the orebody. Along with this move comes an opportunity to almost triple the effectiveness of the mining effort, through higher draw columns and wider draw bell spacing. This final advancement to a totally trackless mine has positioned Henderson well for safe and efficient operation as it enters the 21st century.

Jan 1, 2000

By Kurita K, Tanaka T

In order to clarify the gas flow and motion of coke and reaction in the raceway, the mathematical raceway model was developed. This model consists of the equations of momentum and continuity of gas and coke. The simulated results were compared with the results of the cold and hot experimental model. The relationship between the blast volume and the raceway size, the pressure distribution and the velocity distribution of coke are in good agreement with the experimental results. Moreover the equations of reaction and heat conservation were simultaneously calculated with the dynamic equations. Distributions of gas composi- itions and temperature were simulated and found to be in good agreement with the distributions of gas compositions of CO, CO2 on the tuyere level measur- ed in the hot experimental model.

Jan 1, 1981

This paper attempts to draw together the experience of over 30 years of research and practice in the United Kingdom on the rehabilitation of abandoned metalliferous mining wastes. The reliance on water when the mines were operating has implications for water quality and the techniques used to restore sites to alleviate the principal impacts of the mines. Drivers of reclamation included concerns about human health from wind blown dust and pollution of watercourses as well as perceptions of dereliction. Techniques of reclamation used involved removal of spoil from near to surface watercourses, capping of spoil, diversion of watercourses, use of impermeable membranes, prevention of surface sinks into underground workings and the use of constructed wetlands. The issues to be dealt with in mine reclamation have become more complex and sometimes diverge. The schemes in the 1990s described have been effective in dealing with pollution from spoil heaps and small but significant adit discharges; however, significant issues, particularly those of large flows of polluted water from mine sites, still need to be dealt with. Although the paper describes the legacy of mining, which largely finished in the late 19th/early 20th century, similar issues but on a larger scale are to be found in more recent mining, for example Eastern Europe. In many of these areas minerals still remain to be won and dealing with this legacy may fall on new mining developments.

Jan 1, 2006

All large open pits in Australia have been mined, or are planned to be mined well below the local water table. This raises several issues that impact on mine safety, mining costs and regulatory approvals. Some pits will be æwetÆ, where they are mined through permeable horizons and where there will be measurable groundwater inflows. These will require some form of dewatering. There may also be some difficulties in the disposal of excess water. Other pits, may be ædryÆ, where they are mined through impermeable material and there are no measurable groundwater inflows but where there are stability issues related to hydrostatic pressures within the pit walls. These may require some form of depressurisation. Some pits are a combination of both. Effective management of groundwater inflows and groundwater related stability issues and the development of cost effective and environmentally acceptable dewatering and depressurisation systems requires an understanding of site specific hydrogeological conditions and practical experience in what works best for different conditions. The presentation will include an outline of the key hydrogeological factors that impact on large pits, practical methodologies for achieving dewatering/ depressurisation, and some case studies from the Goldfields, Pilbara and North Queensland.

Jan 1, 2003

By Knight J. L, Baker G

The Wonthaggi coalfield is in South Gippsland, about 90 miles southeast of Melbourne. It is situated on the down-faulted block of the South Gippsland highlands that lies south of the Kongwak fault, between the Powlett River and the sea (Fig. 1). The coal, which is of Jurassic age, occurs in two small, and intensely faulted, limnic basins, that lie on either side of a concealed ridge of Silurian sediments. The coal was first found as thin seams outc1'opping in the cliffs at Cape Paterson, but the seams that are worked at Wonthaggi are concealed beneath a veneer of Cainozoic sands that covers the Jurassic strata, and were found by boring.The c9al seams are worked by the State Coal Mine, which was opened in 1909 to ensure a supply of coal for the Victorian railways, following a prolonged strike in the Newcastle field of New South Wales. The total production from 1910 to June, 1943, amounts to 13,918,800 long tons of coal. The coal seams are faulted to a degree unknown in most coal...

Jan 1, 1944

By T Connor

Alkali emissions are one of the environmental challenges facing alumina refineries. Queensland Alumina Limited (QAL) is undertaking a number of initiatives to continuously improve its environmental performance. One of these is a program aimed at the reduction of alkali emissions. Alkali emissions originate from a number of sources (eg elevated open tanks), and its level depends on a number of process parameters/ mechanisms (ie splash filling, thermal currents in tanks, streams discharged from a pipe, tank temperatures, atomisation) and climatic conditions (eg wind speed and direction, rain, etc). Under normal operating conditions, there is a continuous low level of alkali emissions from the plant. Certain vessels within the plant have been identified as major contributors to this level of emission, while certain activities within the plant contribute to a temporary elevation (æspikeÆ) of alkali emissions. QAL developed a method using phenolphthalein-treated pads to measure emissions within and outside QAL boundaries. These provide no information about mass emission rates but are important for detecting if alkali material is present. Since mass emission rates are important for determining if improvements in emissions are made, QAL identified the need to design an improved sampling method. Following the development and implementation of a sampling and analysis method to monitor alkali emission concentrations, QAL is conducting a number of feasibility studies evaluating a range of alkali emission reduction options. The alkali measurement method will be used to track and demonstrate progress in this environmental initiative. This paper will discuss the measurement method and emission reduction options being evaluated.

Jan 1, 2005

Recovery of gold by smelting zinc dust concentrate has been carried on at Lake View and Star, Ltd., since July, 1930, when the Merrill-Crowe precipitation plant was first put into operation.Part I describes the development of current gold-room practice, commencing with the clean-up of the MerrillCrowe plant, a procedure that has not materially changed since its inception, and then shows how modifications to straight roasting and smelting became necessary, following a gradual increase in the copper content of the ore treated by the mill.Present smelting practice converts most of the copper into a mixed copper-lead matte, thE sulphur being supplied by the addition of flotation concentrates containing about 35% sulphur as pyrite. The process yields gold bullion of a sufficiently high grade to send to the Royal Mint, but until 1943, suffered from the disadvantage of giving matte and slag by-products high in gold and silver, that were not recovered directly but had to be sent to a smelter.Part Il gives details, of experimental work cnrried out since 1943 which led .to a process for the satisfactory and economic recovery of not only the gold and silver, but also the copper from these, hitherto, troublesome by-products. Nevertheless, incidence of matte in a smelt has always been considered undesirable, and it is hoped that eventually it will be obviated by removing most of the copper from the zinc slime before smelting.Part III indicates the methods by which this might be achieved, and outlines the experimental work that has been done up to the present.

Jan 1, 1948

By E Broers, J Goh, S Davies

With recovery being important in optimising the business performance of a laterite and sulfide plant and with water being a precious resource in Australia, there has been increased pressure for companies to improve their methods of improving liquor recovery and improving water recovery in both laterite and sulfide plants. This has resulted in new control technologies such as the Manta Cube being applied on countercurrent decantation (CCD) and thickening circuits which is necessary to improve stability and optimise the liquor and water recovery in these processing plants. This paper describes the benefit of applying these new control techniques on CCD and thickening circuits in some of the mineral processing plants in Australia.

Jan 1, 2009

By Wetzeil N

High ambient temperatures combined with high surface humidity in the north of Australia and, in particular, the northern areas of the Northern Territory can make underground workplaces relatively inhospitable at certain times of the year. . Woodcutters' silver/lead/zinc mine, situated some 80 km south of Darwin, would be the most northerly underground operation of any significance in Australia. As such, during the build up to the wet season, it has a particular problem of ventilating a deep underground mine with already high dry and wet bulb temperatures at the surface. The Mine Management Act and Regulations mention only that workplaces shall be 'in a fit state for a person to work in or occupy'. Woodcutters therefore set in progress a Heat Stress Program to endeavour to set standards which would be more measurable and justifiable. The aim of the program was to compile a record of ambient atmospheric conditions in the working areas such that areas and/or work activities generating high ambient temperatures and humidities could be identified, quantified and qualified. Once the analysis stage of this program was completed, Woodcutters compiled a set of recommendations for the continued monitoring for, and control of, heat stress conditions to ensure that no underground employee was placed at risk from 'heat stress'. These recommendations are discussed in this paper.

Jan 1, 1994

By P Hodkiewicz, K Noormohamed

Gold deposits in the Chirano district in south-west Ghana are hosted in a variety of structural settings along the Chirano shear zone (CSZ), in Paleoproterozoic rocks of the Sefwi-Bibiani belt. Most gold mineralisation occurs in strongly sheared and hydrothermally altered Birimian mafic igneous rocks and tonalite intrusions within the CSZ. A recent program of open pit structural mapping, core logging, and three-dimensional modelling helped to define deposit-scale structural controls on gold mineralisation. These include strain domains, shear zone flexures, shear zone intersections and vein arrays associated with host-rock competency contrasts. Interestingly, the plunge of higher-grade shoots in some deposits appears to be associated with the intersection of the CSZ and broadly folded Tarkwaian sedimentary rocks, which are not significant gold hosts in the Chirano district. This paper presents the results of 3D modelling that were used to define structural controls on mineralisation in several open pits and one underground mine along a 9 km length of the CSZ. LeapfrogÖ software was particularly useful because it highlighted the orientations of structural features that focused hydrothermal fluid flow during alteration and mineralisation. The improved understanding of structural controls provided two main benefits: near-mine exploration drill targets and better definition of structural domains for resource estimation.

Jan 1, 2009

By H Zhang, Y Wang, S Sukenaga, H W. Ni, H Shibata, W Z. Mu

The crystallisation behaviour of low melting point CaO-SiO2-Al2O3-MgO inclusions greatly affect the deformability of inclusions during the rolling process. The crystallisation characteristics of CaO-SiO2- Al2O3-MgO melts representing the oxide inclusions in Si-Mn killed steel were systematically investigated. The effect of Al2O3 and MgO contents on the crystallisation change were analysed under a fixed CaO/SiO2 in the complex inclusions. The continuous-cooling-transformation (CCT) and time-temperature-transformation (TTT) experiments were conducted. The results showed that the increase of MgO content increases the crystallisation ability of CaO-SiO2-Al2O3-MgO inclusions, while the increase of Al2O3 content has the opposite effect. The viscosity, liquidus temperature of oxide melt and also the initial crystallisation potential might be the reasons for the change in crystallisation behaviour. Also, the crystallisation activation energy could semi-quantitatively characterise the crystal growth during the crystallisation of inclusions. To obtain low melting point plasticized CaO-SiO2-Al2O3-MgO (CaO/SiO2=1) system inclusions, the Al2O3 content of the system needs to be controlled larger than 15 wt per cent and the MgO content should be kept at a small amount.

Aug 21, 2024