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By N J Welham

A commercial enargite concentrate was mechanically milled in inert and oxidising atmospheres for 10 hours. No substantial effect was observed in either an inert atmosphere or in air other than a broadening and weakening of the diffraction peaks. Milling dry in oxygen or wet in air was dramatic with a significant reaction occurring which formed arsenolite, As2O3 and CuSO4.5H2O, both of which are readily soluble.A small amount of SO2 was also formed. Dissolution in acid left CuS as the major phase implying incomplete oxidation. The small fraction of tennantite in the sample was comparatively resistant to oxidation.

Jan 1, 2001

More than in any other way, the community judges the minerals industry by its environmental performance. Minerals Council of Australia web site www.minerals.org.au/media/code Time is overtaking us. What was good enough yesterday is not good enough today. What may be acceptable today wonÆt be tomorrow. So we need to leap forward. We need to begin to move towards sustainability. Dick Zandee, Managing Director, Placer Dome Asia Pacific The competition for access to exploration and mining opportunities is intense. So is competition for the best people, capital and community support. Poor environmental performance damages a companyÆs ability to attract these. Quite simply, good environmental management is good business. Hugh M Morgan AO,Chief Executive Officer,WMC Limited. Decisions made by private industry and international corporations are increasingly determining the fate of the environment. ...Nothing could be more shortsighted than for todayÆs conservationists to neglect cooperation with business and industry as a means of moving company philosophy and public accountability ahead in favour of the environment. Dr Claude Martin,Director General,WWF International The four quotes above well illustrate the challenges faced by companies and conservationists in attempting to achieve the societal goal of sustainable development. That this aspirational goal itself is far from clearly defined, although it has been widely accepted and endorsed by governments, business and civil society, exacerbates the challenges. Sustainable development has as its central thesis the integration of environmental, social and economic policy. Its attainment by business has been described John Elkington (1998) as the pursuit of the ætriple bottom lineÆ - the achievement of social and environmental targets, in addition to the traditional economic bottom line. It is self-evident that business is both competent and comfortable defining and measuring economic performance and reporting that performance to internal and external audiences. As long as information has been prepared according to the established standards of measurement and reporting of economic performance, all audiences can have confidence in its accuracy. Business does not enjoy the same competence and comfort with regard to social and environmental performance. This is no startling condemnation of business, any more than it is a criticism of governments, non-government organisations (NGOs) or academia. It is a statement of fact that the tools to allow for credible definition and reporting against the other two components of the ætriple bottom lineÆ have yet to be fully developed and are, therefore, far from being widely accepted. Crucial to achieving sustainability is the ability to measure progress toward the goal. The task is to develop means to define appropriate performance standards and to credibly measure and report company environmental and social performance against those standards.

Jan 1, 2000

By Box JC

A comprehensive computer simulation has been developed for heap and dump leaching processes. It deals with complex chemical interactions, involving several minerals and reagents, which vary with time and location in the dump. The simulation is generally applic- able to ores of various metals extracted by different reagents. It requires only mineral- ogical data obtainable from drill cores and chemical data obtainable from the literature; there is no curve-fitting with adjustable parameters. Applications in designing testwork programmes, evaluating operating options, transferring experience to new situations and reducing uncertainty in long-term forecasts are described. Specific examples are included illustrating the potential of the simulation.

Jan 1, 1983

By Zharinov SE

Geonechanical modelling of island arc sys- tems and their analogs is investigated. Slow seismotectonic movements along the inclined deep fault zone under the compressive horizontal stress conditions are proposed to be the princi- pal mechanism controlling the structures and processes in the active continental margins. A model of shearing surface crack in an elastic half-plane is used for simulation. The main ele- ment of the model is viscous interaction bet- ween the crack sides, the viscosity varying with depth. To describe the stress-strain state of the medium an integro-differential singular equation is derived and solved numerically. The results of simulation are in good agreement with geological and geophysical data on the ac- tive continental margins.

Jan 1, 1987

By D Craw

A glasshouse experiment was set up to investigate arsenic uptake in rye corn grown in different arsenic rich substrates. Sods of material were taken from various locations and planted with rye corn seeds. The plants grew for 13 weeks after which time the above ground biomass was harvested. Analysis of the rye corn plants showed a narrow range of arsenic concentrations, which did not reflect the arsenic contents of the soil. Comparison of the results from this study with previous work showed the glasshouse rye corn to have lower arsenic concentrations in above ground biomass than rye corn grown in field conditions. The environmental conditions present on the tailings and water-rock interactions were considered the main factors involved with the difference in arsenic uptake between field studies and the glasshouse study. This suggests that bioavailability processes are influenced by a variety of factors and cannot necessarily be predicted by the use of soil factors or glasshouse trials alone as is often done when planning phytoremediation work and mine shut down.

Jan 1, 2007

About 90 per cent of the pre-mining BIF-hosted iron ore resource of the Hamersley Province of Western Australia is of the Phanerozoic supergene martite-goethite type. The remaining ten per cent formed as supergene deposits at ~2000 ¦ 200 Ma, and were later modified by burial to form the Proterozoic martite-microplaty hematite ores. The supergene-metamorphic segment of this general unified model has been challenged by three recently published hypogene-based genetic models for the hematite ores, all requiring meteoric oxidation to produce the ore. The most recent and detailed, by Taylor et al (2001), is based on data from the small Southern Batter and North deposits of the Mount Tom Price mine. The authors proposed that during Stage 1 æoverpressured bicarbonate-saturated basin brines from the dolomite aquifer of the Wittenoom FormationÆ at 150 - 250¦C, dissolved free silica from BIF to produce a stratigraphically thinned, magnetite-carbonate-silicate-apatite rock. In Stage 2, meteoric oxidation of siderite to secondary microplaty hematite + ankerite, and magnetite to martite, at unspecified elevated temperatures and pressures, was followed by carbonate leaching (Stage 3). Finally, during Stage 4, weathering with removal of apatite, produced the typical low-phosphorus, porous martite-microplaty hematite ores of the Tom Price-Whaleback type. However, evidence of both microplaty hematite and martite reduced to magnetite, and of infill silica, apatite, and ferroan chlorite, with late-stage pyrite, in the pore space of martite-microplaty hematite ore, shows that the hydrothermal activity at Mount Tom Price is a post-ore event. Neither pyrite nor ferroan chlorite could resist the oxidation required to form hematite ore. Recrystallisation of microplaty hematite in these infilled zones to a typically coarser form than present in most of the normal ores, is a further supporting factor. A more credible, post-ore alternative to the hypogene genetic model is suggested here. Re-exposure to leaching by ground water of the metamorphosed ore deposits in the Phanerozoic resulted in the partial removal of remnant goethite. Localised modifications in the porous BIF/ore contact zones were driven by exothermic oxygen/pyrite/carbon reactions in the footwall Mt McRae Shale. Cool descending oxygenated meteoric water in the permeable ore horizons, acted as one limb of a thermal convective cell. In the other limb, heated reducing solutions rose through the permeable contact zones, to produce the observed localised modifications of BIF and ore. Expelled silica from the carbonatised BIF invaded adjacent porous ore to form erratic silicified ore zones, and to produce the local quartz vein systems found in the associated overlying BIF.

Jan 1, 2002

By S M. W Rajaratnam, P Varma, T L. Sletten

Mining employees undertaking shift work are at considerable risk of experiencing sleep disturbances and circadian rhythm disruptions. In the complex, high-risk environment of mining, these sleep and circadian disruptions lead to adverse impacts on employee health, alertness and safety. Evidence-based tools that effectively target improvements in sleep health amongst shift workers are needed. Variability in work hours and individual differences in the response to shift work mean that a ‘one-size-fits-all’ solution is often insufficient in complex work environments. Currently no interventions provide tailored support for shift workers based on their rosters, personal commitments and sleep habits. Existing technologies, such as smartphone applications and watches, allow sleep monitoring, but their strategies are targeted towards night sleepers, which does not translate to shift work contexts. To address this, our team has developed an innovative digital tool that implements biomathematical models to provide automated, personalised sleep and circadian intervention strategies to optimise sleep, alertness and performance during shift work. The tool uses mathematical models of sleep and alertness regulation that provide physiologically optimal times for an individual to sleep when experiencing circadian disruption. This program of work included co-designed development of a world-first app with shift workers and the examination of the preliminary efficacy of the intervention for improving sleep, alertness and performance.

Apr 16, 2024

By L Neems

In conjunction with Orica Explosives, Worsley Alumina have managed a program of continuous improvement to their cap rock blasting over the last two years. Blasting conditions are challenging because of the hard and shallow nature of the material. Blasting costs must be controlled and the environmental consideration of noise and dust is critical. Worsley have sought to determine the optimum balance between drilling and blasting costs and fragmentation. As the cap rock has few inherent weaknesses, loader productivity is strongly controlled by the degree of fragmentation from blasting. The optimum blasting solution is also constrained by maintaining airblast levels at the surrounding residences below 115 dBL . The major blast design parameters optimised during the program were stemming type, stemming length, powder factor and blasthole diameter. A series of carefully managed trial blasts were fired during 1997 and 1998 to quantify the effect of these parameters. Fragmentation was digitally measured using OricaÆs Powerseive G technique. Shovel productivity, airblast levels and blasting costs were also quantified. As a result of the project, Worsley now have an increased knowledge of the key parameters driving blast performance, and their consequent impact on downstream processes, the environment and total mining cost.

Jan 1, 1999

By Y Potvin

Underground mines in Australia are progressively operating at greater depth, sometimes in conditions where mine induced stresses are very high. In such conditions, the seismic activity often becomes intense and violent and in response, mines must develop and implement a sound rock burst risk management strategy to continue operating safely.This paper discusses the latest techniques successfully used in Australian mines to mitigate the risk of rock bursts. In particular, the paper describes how the analysis of data collected from seismic monitoring systems can provide an understanding of the seismicity and be used for quantifying seismic hazards in the mine. Once an adequate understanding and assessment of seismic hazard has been achieved, the associated risk can be mitigated using different layers of protection.Strategically, modifying the mining method, the extraction sequence and/or the mining layout can alleviate the seismic hazard, but these solutions generally cannot be implemented rapidly. In the short-term, seismic risk can be mitigated tactically using an energy absorbing support system or to remove personnel from being exposed to rock burst damage by implementing exclusion zones.

Mar 21, 2011

By K G. van den Boogaart, M Lehmann, U Mueller

Geometallurgical parameters are descriptions of the mineralogy and microstructure of the ore determining its mineralogical and microstructural characteristics. From a conditional geostatistical simulation of such properties, a processing model can compute recovery, equipment usage, processing costs, and thus the monetary value for mining and processing a block with certain processing parameters. The output can be used for optimising mining sequences or finding optimal processing parameters by solving the corresponding stochastic optimisation problem.The approach requires two properties of the simulation not provided by established geostatistical techniques:Many relevant geometallurgical parameters are from non-Euclidean statistical scales such as (mineral) compositions, (grain size) distribution, (grain) geometry, and (stratigraphic type) categorical, which might produce nonsensical values (for example, negative proportions, negative facies probablities, planar grains) when simulated with standard geostatistical techniques.Due to the nonlinearity of processing, the entire conditional distribution of the geometallurgical parameters is relevant, not only its mean and variance. The geostatistical simulation needs to reproduce the joint conditional distributions of all the geometallurgical parameters.The multipoint conditional geostatistical simulation technique discussed here allows for jointly simulating dependent spatial variables from various sample spaces. The technique combines an infill simulation, similar to the one used in multipoint geostatistics, with a new form of distributional regression to estimate conditional distributions of arbitrary scales from different information sources, including training images, training models and observed data. The distributional regression is based on a generalisation of logistic regression and is related to both Bayesian Maximum Entropy geostatistics and high order cumulants.The method ensures that simulated data reside in the set of possible values and honour the characteristics of the joint distribution to be reproduced. The computational effort is substantial, but affordable for a useful application with standard problems: from processing-aware block value prediction and block processing optimisation as shown in the test application to a mathematically completely defined simulated model situation with a complex processing model.CITATION:van den Boogaart, K G, Tolosana-Delgado, R, Lehmann, M and Mueller, U, 2014. On the joint multipoint simulation of discrete and continuous geometallurgical parameters, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 379–388 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

This paper outlines the aims, objectives and means by which a life of mine land use plan was established for Comalco's bauxite mine at Weipa. Comalco realises the need to strategically plan for future mining activities and still minimise the impact of operations on the natural resources of the region. With this realisation long-term forward planning has been implemented to improve the Company's ability to select future sites for mining, industrial use, agriculture, town expansion and conservation purposes.The knowledge of mineral, water, soil and animal resources has expanded dramatically in the past decade. During 1990 Cornalco purchased Geographic Information System technology which has allowed previously collected resource data to be presented in map form. These maps as part of the Life of Mine Land Use Plan are both information based and strategic which can be efficiently updated. The maps allow a broad audience from engineers, geologists, environmental scientists and site managers to government officers and the general public to comprehensively view and scrutinise the operations.

Jan 1, 1992

The invitation to speak today was in the form of a single sentence instruction: How does your company run and how do you communicate from top to bottom? It looks like I'll have to let you into our little secret. The team at Croesus know what works for us but we've never talked about it with others - least of all presented it at a conference such as this. In fact we tend to avoid the jargon normally associated with Best Practice or TQM, however in our own way, each of our staff are 100 per cent loyal to our company's aim to maintain and strengthen our commercial success. Just how we achieve this at Croesus is the subject of this presentation today, but first a little history. My dear old grandfather arrived in Kalgoorlie, as a mining engineer 100 years ago. Do you think he would have chuckled if someone suggested to him that a hundred years later we would just be starting to understand Kalgoorlie's geological mysteries? Well, here we are 100 years later and Croesus Mining is fortunate to be part of a generation now realising the true potential of Kalgoorlie's Goldfields. This provides us with a very fertile field in which to sow the seeds we can obtain from the World's Best Practice in Mining and Processing. With each new mineral deposit being discovered, old theories are being exploded. Each new deposit has a personality of its own, leading to some belated pioneering theories of where to drill next, and how to reduce internal costs so that we can win the war against constantly increasing external costs. What we have now and what the old timers didn't have is a huge database of geological input spanning several gold booms and a couple of nickel booms. My only interest in history is to pick up the points that may help us for our future. This is what we are doing in our company which is something of a David, in the David to Goliath range of mining companies in Australia. As a humbling thought; of the 115 164 tonnes of gold that the world's mines have produced throughout history, four tonnes have been produced by Croesus Mining. That's equivalent to 0.003 per cent of the total world's gold production. In the past financial year we achieved a dividend yield of five per cent. To put this into perspective, that's over twice the dividend yield of BHP, Australia's largest company. As we are somewhat less known than BHP, let me spend a few moments giving some particulars of our company's background.

Jan 1, 1995

By J Harmse

This paper deals with the modernisation of the brakes on an electrically coupled Blair multi-rope hoist and covers the removal of the old calliper brakes and hydraulic control system, and its replacement with brake discs, disc braking units and hydraulic control systems. The paper covers the braking requirements of the hoist, which is made up of two electrically coupled single-drum hoists, together with the theory behind the choice of brakes and control systems supplied. The paper also covers the project logistics that were required in order to install and commission the new brakes and control systems with the minimum disruption to production on the only rock hoist on a major production shaft. Items covered include the modifications to civil works, pre-installation of bearing lubrication systems, brake discs and hydraulics and the interfacing of the new hydraulic control system to the existing electric control system. It had to be designed to be compatible to a new electric drive and control system due for installation at the end of 2005.

Jan 1, 2005

By Wu H. W, Just G. D

Australia's mineral resources boom in the two decades up to 1980 saw the establishment of about 25 new mining towns across the continent Quality housing and a high standard of community services were incorporated to attract a labour force for the major mine or mines i eing serviced. Town construction costs were high and were principally born by the private enterprise mine developer. There has been a change in the pattern in recent years and over 20 new mine developers have adopted a fly-in fly-out arrangement rather than construct new towns. Employees are drawn from a home base which is typically a large city, coastal community or established mining town and flown to the mine site for intensive work periods of about two weeks. The change has occurred for many reasons. Mining companies have been unwilling to support the high construction costs of towns, short life and smallermining operations do not justify a town, fast jet aircraft are available and there is a better perceived family lifestyle in established (coastal) communities. On the other hand reduced permanent development at new mine sites does not assist Australia's perceived need for decentralization. There have been questions as to the social problems which may develop from the artificial separation of the "breadwinner" from his family. The paper reviews a recent survey of the attitude of Australian mining companies employees, governments and unions to fly-in fly-out arrange- ments. The support for this approach is analysed and conclusions drawn that the concept is likely to be with the Australian mining industry for some time in the future.

Jan 1, 1991

Renison Limited produces high and low grade tin concentrates at an annual rate of 5000 tonnes of contained tin metal. In spite of the fine average cassiterite grain size, emphasis is placed on gravity concentration methods to produce a high grade final product. Cassiterite flotation is considered and operated as a gravity circuit scavenger responsible for approximately 15 percent of recovered tin metal as a fine grained low grade concentrate. Metallurgical problems mainly result from ore-type variations which may be aggravated by a number of circulating loads. The rationalisation of circuitry is being studied to provide more effective control by operators and to allow exploitation of current control and modelling techniques.

Jan 1, 1977

By Nilmani M, Malone J, Taylor RN, Floyd JM, Gray NB, Fountain CR

CSIRO staff and University of Melbourne staff and students collaborated in an intense programme of investigation on the CSIRO 50 kg Sirosmelt pilot plant.In two days of operation copper matte converting and zinc slag fuming trials were performed, whilst investigation of the process dynamics and process chemistry was carried out. This exercise is an example of the techniques available for process evaluation, which can rapidly advance the understanding of pyrometallurgical operations by use of a team approach covering a wide range of experiments.

Jan 1, 1985

By Xianguo C, Baoqi S, Shaozhong Z, Huiling Z, Zhengbing C

Acidless and fluoless flotation is a new method for separating feldspar from quartz at the natural pH value of tap water in the absence of any acid and fluoride and other inorganic reagents. The paper introduces the production application of this method in plants and research results on the mechanism involved in the flotation method.

Jan 1, 1993

By E Werner, B R. Leavitt

The chemistry of acidic mine drainage discharging from flooded coal mines is commonly reported to improve with time after flooding. This investigation describes a 18-year dataset of post-flooding water chemistry for a below-drainage underground coal mine within the northern Pittsburgh coal basin (Pennsylvania, USA). The Montour mine is a 5650-hectare below-drainage coal mine of maximum 260 metres depth. Montour was closed in 1980 and flooded to within 38 metres of land surface within 4.8 years. Pumping averaging 210 L/s was then employed to maintain water levels at this elevation. The flooded proportion of the mine (by volume) at full flooding was 56 per cent. The shaft where water was pumped from Montour for water control is located about 70 per cent of the distance between the mine water table and the back of the mine ù that is, it is close to the back of the mine. The residence time (total water volume at flooding divided by pumping rate for control) is estimated at 5.6 years. Time series of chemical analyses show three phases of chemical behavior in post-flooding discharge. In Phase I (zero to two years after flooding), iron concentrations were high and reached their maximum (1100 mg/L). In Phase II (two to four years after flooding), a transition was begun to alkaline conditions, with decline in iron and other solutes. In Phase III (>4 years), net alkaline conditions began, with iron concentrations declining exponentially to 50 per cent of mined volume. This attainment of net alkalinity in this case may have also depended on abundant calcite in overburden extended up to 30 m above the mine floor.

Jan 1, 2003

By Niemann G

The paper addresses certain mining provisions of the Aboriginal Land Rights (Northern Territory) Act 1976 and the development of Mining agreements negotiated pursuant to Section 43 of the Act. Difficulties for miners and Land Councils alike arising out of the operation of the Land Rights Act will be discussed. Possible scenarios for the resolution of these difficulties will be proposed.

Jan 1, 1984

By Grinbaum B, Stevens G. W, Dalton R. F

Many hydrometallurgical processes produce large amounts of acid waste. This is illustrated by the copper S/X-E/W process which produces a bleed from the electrolysis tank house in the form of a concentrated sulphuric acid stream. Currently, the bleed stream is necessary to remove impurities such as iron that decreases the efficiency of the electrowinning process. However, this comes at a high financial cost owing to large quantities of make-up sulphuric acid required. A process has thus been developed with Zeneca Specialties (UK), ICI Australia and Gunpowder Copper Co at the University of Melbourne for the recovery of sulphuric acid from copper tank house bleed liquor. The recovery process uses the method of solvent extraction. Solvent extraction has the advantage of being a well-established technology in the mining industry and will reduce the environmental impact of the S/X-E/W process, as all additional chemicals can be completely recycled. A simplified diagram of the process is shown in Figure 1. Tank House

Jan 1, 1997