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By K Luthbom, A Lagerkvist

According to the Swedish Environmental Protection Agency, the number of potentially contaminated sites in Sweden is approximately 40 000. The funding for remediation from the Swedish Government alone amounts to $A 60 - 80 M (300 - 400 MSEK) annually for the period 2003 - 2006. Uncertainties will arise when obtaining samples in field, preparing them in laboratories and analysing them. Different procedures give rise to varying errors. Using data for decision-making that does not truly represent the site could be fatal. Misclassification of soil could lead to unnecessary costs or to risks to human health and the environment. The total uncertainty of an environmental sample can be split into analytical uncertainty and sampling uncertainty. The analytical uncertainty is usually known and reported from routine analysis. The size of the sampling uncertainty is less well known. Hence, the question is how big are the sampling uncertainties for contaminated soil and how big is the analytical error compared to the total sampling error? A scrap yard and two landfills within a workshop area were investigated. An excavator dug trial pits and samples were taken with a trowel from the walls of the trial pits. Samples were put into plastic bags and taken off site for preparation and analysis using XRF. Sample preparation included drying and sieving. The samples were homogenised by kneading the sample bags prior to analysis. The sampling and sample handling were performed in an intuitively way without knowledge of sampling theory. However, Pierre GyÆs sampling theory was used for subsequent evaluation of the data from the site investigation. The theory defines seven sampling errors, which can be applied to sampling of soil. Some errors have a variance that can be calculated or at least estimated, while other errors can give some idea whether the bias is positive or negative. The total sampling error varied over three orders of magnitudes from sample to sample. The single largest contributor to the large variation in error was the contaminant level. When comparing the analytical error and the total sampling error the ratio varies more than three orders of magnitude.

Jan 1, 2005

By M Freeman

Significant improvements in the metallurgical performance at Pasminco Rosebery Mine have occurred over the last two years. Lead and silver recoveries have increased by more than ten per cent, lead concentrate grades are four per cent higher, zinc recoveries are up 1.5 per cent, and zinc concentrate grades have increased by two per cent. These impressive results have not occurred through the application of some new wonder reagent, but through the application of some fundamental metallurgical principals. The basic premise applied during this study was that to make an effective separation you must first achieve liberation. Therefore, the laboratory and plant studies examined the liberation characteristics within the lead circuit, and the impact of regrinding. The work demonstrated clearly that galena/sphalerite liberation was poor, and significantly impaired plant performance. Further, it was suggested that the application of lead regrinding of the lead scavenger concentrate and the lead first cleaner tailing would not only benefit lead metallurgy, but also improve sphalerite flotation. A similar approach was then applied to the zinc circuit. From these studies, solutions applying simple circuit changes utilising existing equipment were proposed and implemented. Further to the improvements in galena/sphalerite liberation, significant improvements in concentrate quality were achieved by reducing variation within the process. The implementation of changes in work practices negotiated in the Enterprise Agreement, employee contributions and specialist training also made a significant contribution to the unprecedented improvement in the lead and zinc flotation circuit performance. The results of these plant changes are discussed, along with the suggested scope for further improvement.

Jan 1, 2000

By M D. Rosengren, G Gregor, M F. Young

Over the last 15 years the silver/lead/zinc ore treated at Mount Isa became increasingly complex and lower grade. Metal recoveries dropped dramatically, causing a serious decline in profitability. The ætraditionalÆ response of increasing tonnage to reduce unit cost was unsuccessful, since the additional tonnage was even lower quality ore. A major technical and capital program in the 1990s restored metallurgical performance, but business return was still too low and ore quality continued to decline. In 1996 a new, holistic approach integrated the steps of geology, mining, concentrating, smelting, and refining. Previous assumptions about æfixedÆ and æmarginalÆ costs in mining and processing were shown to be wrong. Detailed analysis showed that some ore sources were reducing profit. This led to a fundamental redesign and downsizing of both Mount Isa and Hilton mines. The result was dramatic increases in head grades, metallurgical performance and plant stability without any capital expenditure. The business is now smaller, but more profitable.

Jan 1, 1998

This paper examines some of the important aspects of mineral taxation policies and practices, with reference to the mining tax regimes of selected Pacific Rim countries (see Tables 1 and 2). The following subjects are addressed:what is æmineral taxationÆ?, basis for mineral taxation, types of mineral taxes, objectives of the mineral taxation regime, best practices, and mineral royalties. Many countries, in some cases with the encouragement and assistance of international funding agencies, are actively assessing the international competitiveness of their mining tax regimes with a view to attracting investment. However, these countries recognise that the mining tax regime is not the only consideration that is taken into account by prospective investors. The countryÆs geological prospectivity, physical infrastructure, labour force, political risk, and regulatory system are also important factors in the investment decision making process. Although it is probably true that an attractive mining tax regime will not necessarily attract mineral investment, there is a real possibility that an unattractive regime can drive away investment. For example, Hugo Dummett, general manager for discovery at BHP, hinted recently that BHP could cease exploration in Russia in the absence of positive tax changes. Dummett is reported as saying that if taxes æend up being as onerous as they are now, we really have to rethink why we are hereÆ (Mining Journal, London, November 27, 1998).

Jan 1, 1999

By R B. Wanty

Historically, most investigations of biogeochemical cycling in acid rock drainage systems involved synoptic sampling over longer time periods (one sample per week or month) or intensive time series studies over a few hours or days. However, many important episodic loading events, such as seasonal meltwater and storm events occur on timescales that are rarely observed by these traditional sampling approaches. Monitoring these transient processes, which may contribute the bulk of the annual metal loading, is essential for accurate assessment in acid rock drainage areas. Recent work also has demonstrated dramatic diel (24 hour cycle) variations in trace metal concentrations in response to diel changes in temperature, pH, oxygen, and photochemical cycling (Brick and Moore, 1996; Nimick et al, in prep). To characterise a system that may respond to diel, seasonal, and episodic events, a monitoring program must sample at a frequency that captures the details of these major forcing events. We developed two novel instruments, the Zn-DigiScan and the DigiSampler to examine low and high frequency temporal changes in acid rock drainage areas. The Zn-DigiScan is a battery powered real time in situ chemical analyser designed for long-term deployments with hourly analyses of Zn. Stream physical parameters (temperature, conductivity, dissolved oxygen, pH, turbidity, etc) were measured every 15 minutes with a water quality sonde. The DigiSampler was developed for the long-term daily sampling of biogeochemically active elements and can take either discrete samples or samples integrated over 24 hours. The DigiSampler collects 2 ml samples in a Teflon coil which are separated by 0.2 ml nitrogen bubbles. The sample coil is returned to lab and the 2 ml samples are diluted 1:10 and analysed for trace metals by ICP-MS. Initial results from a three-day deployment at Fisher Creek, MT, USA have successfully demonstrated the ability of the Zn-DigiScan to record Zn concentrations at levels below 100 ¦g/L. Zinc concentrations measured at 30 minute intervals in Fisher Creek showed a diel cycle with low values of ~25 ¦g/L in the late afternoon and increasing to ~60 ¦g/L by early morning. Zn concentrations were inversely related to temperature and pH, suggesting that temperature and pH dependent adsorption was the main factor controlling diel Zn fluctuations. Initial deployment of the DigiSampler also was successful, revealing diel cycles in Zn, Cu, and Mn. Comparison of trace metal samples collected by the DigiSampler showed good agreement with samples collected by an Isco automated water sampler, demonstrating that the DigiSampler can collect clean samples for trace metal analysis at the low ¦g/L range.

Jan 1, 2003

In the humid, subtropical climatic conditions, typical of Papua New Guinean high-lands, auriferous carbonate-quartz lodes and stockwork veins of the Upper Ridges mine at Wau, have weathered in situ forming manganese dioxide-quartz wad flatmakes and veins. Vein assemblages and sulphidized host breccia have been chemically weathered to 20-25m depth, and microscopic grains of electrum (550-600 fine) formerly enclosed in carbonate, sulphide and quartz have dissolved in the oxidizing alkaline fluid. Coarse secondary electrum, crystalline and dendritic, is concentrated by manganese dioxide and at the base of chemical weathering. Fineness is unchanged, eliminating the possibility of gold and silver migration as a chloride complex. Experimental tests on the stability of thiosulphate, and its ability to dissolve gold and silver from colloid, crystal and synthetic alloy confirm that secondary electrum at Upper Ridges is most compatible with precipitation from (Au,Ag)(S203)23-; a complex readily destabilized in the presence of MnO., or with decreasing Eh.

Jan 1, 1984

This paper outlines the role of commissioning in the project cycle, shows how to get organised for commissioning and describes the principal commissioning activities. Emphasis is placed on appointing key commissioning staff early in the project to coordinate the preparations for commissioning and on detailed planning and tracking to ensure that the required commissioning activities are performed satisfactorily. The management of safety during commissioning is reviewed.

Jan 1, 2005

By Szwedzicki T

In recent years substantial advances have been made in the field of geomechanics. Staff at the Western Australian School of Mines (WASM) are keen to see that such advances continue and that the mining industry in Australia can take full advantage of such developments in a timely manner. WASM views mining geomechanics in its broadest sense, as being concerned with the characterisation of the physical properties and the behaviour of earth materials (soil, rock and water) and openings as mining proceeds. Aspects such as, soil and rock improvement techniques for difficult site conditions and the rock breaking processes, are also considered to be an integral part of mining geomechanics. This paper indicates the inter-relationships between the various areas within the field of geomechanics and the strong reliance of all of these areas on site specific engineering geology.

Jan 1, 1992

Australian mining practice operates at the forefront of technology. In recent times Australian designers, contractors and operators have shown many examples of technical "entrepreneurship" in solving geological mining and metallurgical problems. Developments have occurred in the fields of equipment, processing, operating techniques and training which have relevance to the mining industry in other countries. Our mineral exports play a key role in main- taining the viability of the Australian economy. Although the export potential of our specialised equipment and technology is at a much lower level it is a growth area. The export of our mining technology can continue to be basically the result of individual efforts but the question of whether it would be war- ranted and desirable, to establish a coordinating structure should be examined. Existing and new initiatives by the Federal Government indi- cate the Government's interest in the export of technology. The mining industry should take a proactive role formulating policy and programs within its technical jurisdiction.

Jan 1, 1988

By A E. Waltho, W J. Shaw

Predicting the physical characteristics of various ore types has for long been a difficult problem during mining. Grade control practices tend to concentrate on the chemical grade of the ore. Estimation of physical characteristics such as beneficiation behaviour is commonly limited to the simplistic application of historical averages. Large amounts of geochemical data are often gathered during the exploration and mining stages of a project, especially in ferrous and base metal deposits. In addition to the elements of principal economic interest, samples are often analysed for suites of gangue constituents to determine whether the mineralisation lies within target specifications. This multi-element data is often put to no other use than this simple chemical classification, yet it may present the geologist or metallurgist with valuable insights into the mineral content and physical characteristics of the deposit. Normative mineral estimates have been used as a method for characterising igneous rocks for almost 100 years. The method establishes and applies a set of sequential rules, by which the chemical components of a sample are assigned to mineral components. Provided that it is possible to make some realistic assumptions about the mineral species likely to be present in a rock unit or deposit and their paragenesis, this approach can be extended to a variety of mineral deposits. The geochemical data that are routinely collected when, for example, drilling iron ore and base metal deposits, can be used to derive estimates of normative mineral content. These estimates can be used to characterise physical or metallurgical aspects of the ore, such as density, beneficiation behaviour and metal recovery. This paper examines the application of normative mineral estimates to a variety of practical resource characterisation problems. The potential for predicting the lump and fines proportions of iron and manganese ores is also discussed.

Jan 1, 1999

The underground storage of LPG and other hydrocarbons is in current commercial use in Northern Hemisphere countries in Europe, Asia and the USA.Elgas Pty Ltd, a 50 per cent joint venture between AGL and BOC, embarked on a worldwide feasibility investigation in 1989 to establish the viability of constructing an underground LPG storage facility in Sydney, Australia, the first of its kind in the country. Elgas recognised that with the limited 19 000 tonnes of storage capacity at Port Botany and the limitations imposed by use of small coastal ships (up to 10 000 tonnes capacity), a larger storage facility was required to utilise higher capacity ships from more remote sources such as the North West shelf and overseas. This would achieve security of supply in high demand periods and economies of scale. The underground option also provides improvements to safety and environmental standards.

Jan 1, 1999

Over years of exploration the massive and tabular orebodies in the area to the South West of Western Areas Gold Mine had been assessed as containing about 50 million ounces of gold û a world class orebody. Planning initially was for a surface and subvertical shaft system to exploit this area but because of cost, a single lift shaft to an area which could be accessed ex Western Areas was planned to intersect the reef at 2760 metres. It was also planned to mine out the shaft pillar area long before the deep shafts would reach that position. This is not the normal practice in South African Gold Mines. The stoped out shaft pillar was backfilled to minimise movement in the shaft sites. The result of a competitive tender/adjudication process was that Cementation Mining û Skanska won and was awarded the R192 million contract to sink the Main and Ventilation Shafts on 15 June 1995. On 1 April 1999 Western Areas and Placer Dome SA formed a Joint Venture, which now owns and operates the mine on which the South Deep Shafts are situated. This situation prevails today.

Jan 1, 2002

By H Kundapen, J J, C Rumble, S Miller

This paper describes measures taken by Ok Tedi Mining Limited (OTML) to minimise the risk of acid rock drainage (ARD) resulting from mining operations at its Mt Fubilan porphyry copper-gold mine in the remote Star Mountains of Papua New Guinea. The risk of acid generation and metal leaching as a result of oxidation of these sulfidic deposits has long been recognised by OTML. In 1998, OTML instigated the ARD Management Program to fully evaluate these risks and to formulate, if necessary, trial and implement appropriate management strategies. In implementing the ARD Management Program, OTML has adopted a risk management approach consisting of five stages: risk identification, risk analysis, risk assessment, risk treatment, and review and monitor. Significant progress has been made in relation to risk identification, analysis and assessment. The work currently underway to put in place a comprehensive risk treatment and review process will ultimately determine the success or otherwise of this approach.

Jan 1, 2003

By I Mason, G Turner, J Hargreaves

One of the key objectives in production from any mine is the minimisation of ore loss and dilution. This can only be achieved when the distribution of ore within the mine is known. The distribution of ore is usually evaluated from a combination of drill hole information and underground mapping data. Three-dimensional models of the ore distribution are then constructed by interpolating grades, contact locations and confirming these estimates through mapping. While the interpolation procedure can incorporate an understanding of the local geological conditions, it is an approximation and thus susceptible to some degree of ore loss or dilution. Naturally, such problems increase in areas of sparse geologic information or greater geologic complexity. Borehole radar offers an approach to decrease the interpolative aspects of modelling by providing a continuous image of some ore contacts. Borehole radar works by building a two-dimensional image of an ore contact from radio waves bounced off the contact from closely spaced positions along a borehole. This image can be imported into Datamine (or a similar design package) and incorporated into geological models of a given ore block. The results of a trial survey from the Mariners nickel mine at Kambalda are presented to illustrate the improved level of detail and accuracy that can be achieved through the incorporation of borehole radar into orebody delineation practice. Once implemented on a large-scale this technique has the potential to greatly increase the cost-effectiveness of long hole stoping at Kambalda, through increased ore recovery and reduced dilution.

Jan 1, 2000

By S D. Dessureault

In one of North AmericaÆs largest mines, which contains more than six active coal-producing faces, mine controllers must meet the complex challenge of adhering to the mine plan while also ensuring customer quality. Fleet management systems (FMS) provide many different avenues to control production flows, from the faces to the various pit crushers. Nonetheless, mine controllers must balance a variety of factors such as unplanned downs, differing customer demands, their own daily key performance indicators (KPIs) related to equipment utilisation, among others. Deviating from the short-term mine plan is the most common means of balancing the other factors, since adherence to the plan is traditionally only measured during the weekly variance meeting with engineering staff. However, such deviation may be one of the most costly responses, as long-term scheduling issues may arise such as multi-face dead-heading or insufficient stripping. This paper focuses on the development of a system for real-time adherence to mine plan within a control room environment. This system is part of a larger blending-focused, multi-million dollar project with elements of a centralised remote control room, developed at the University of ArizonaÆs Mining Information Systems and Operations Management (MISOM) Mine Control Center (MC2). The mine plan (MPL) component of the overall blending system integrates both historical and real-time FMS data with mine plan requirements directly sourced from original systems (no additional input required). The measures, displayed largely as graphs, have tools to help controllers manage the production to facilitate adherence to the plan. Some measures are designed to motivate crews to perform by inciting competition between crews, softened through a study of the controller culture. The MPL component was deployed at the mine, and the before and after deployment adherence was measured. This paper discusses the technical development of the new tool, its deployment, and an ethnography (study of culture) to understand controller motivation.

Sep 26, 2011

On the basis of the data known on formation, characteristics and stability of solute heavy non-ferrous metals under different temperature and pressure conditions and different concentrations of substances dissolved it is found to be possible to obtain a condition of mineral formation resulting in selective production of free-floating minerals. This process of forced mineral formation has been taken as a basis of new methods of refractory copper raw materials concentration, complex processing of lead dust from copper smelting plants, lead flotation tailings final concentration and of those of polymetallic ores concentration. This list of effective utilisation of the process is not exhaustive (Bekturganov Abishev and Shkodin, 1987; Bekturganov and Sim, 1987; Bekturganov, 1988; Abishev and Bekturganov, 1989; Bekturganov, 1989a). To understand the character of the sulphurising thermodynamic and kinetic examination have been done. Analysis of conditions of the newly formed mineral associations formation and stability facilitates the elaboration of methods of improvement of results of the valuable components selective separation.

Jan 1, 1993

Since the earliest recorded prospecting of the 1860's mineral exploration and mining in Fiordland has been discouraged by the formidable physical difficulties presented by its isolation, extremely rugged relief, treacherous coastal waters and generally unfavourable weather conditions. Government assistance was often sought by the miners and prospectors but little, if any, support or encouragement was received after the initial period. During the 1840's decorative marble was quarried at Caswell and Dusky Sounds. A prospector discovered and attempted to mine copper sulphides to the north of Dusky Sound (Parks Mineral Beds) and near Mt Solitary. A small Pb, Zn, Cu, Ag, Au bearing quartz reef was discovered and driven on in the granite coast line of Preservation Inlet (Bradshaws Reef) and the ore roasted on site. Alluvial and quartz lode gold was discovered at Preservation Inlet in the 1890's and led to the recorded recovery of 11 000 oz of mainly lode gold. Falloff in grades with depth, thinning and splitting of the reefs and the high mining costs at this location led to a virtual abandonment of the field by 1906. In the late 1950's and early 1960's the geology of Fiordland was mapped by the Geological Survey at 1:250 000 scale, but field work was largely confined to the shore lines of the coast and fiords. In view of the physical difficulties it is not surprising that mineral exploration and mining up to 1970 was limited to the scant attention outlined above.

Jan 1, 1977

By S G. Gatehouse

Extensive gold mining activity û dominantly alluvial û has taken place in the Sofala-Wattle Flat district since the 1850s.This work will have located most, if not all, of the visible sources for the gold in current stream systems.Also, there are many gold bearing elevated Tertiary alluvial terraces in the district which may confuse possible gold signals from primary hard rock sources in the streams.Associated element signatures eg As and other chalcophiles, will discriminate non-alluvial signatures but will not necessarily distinguish non gold bearing mineralisation.Both trace elements and conventional gold analyses will dominantly re-identify known occurrences. Conventional BCL sampling is considered misleading as experience from the Oberon area to the south of Sofala demonstrated that BCL sampling was very sensitive û perhaps too sensitive.All occurrences û major or minor û of gold will be detected (Gatehouse, 1992). To improve on BCL sampling, a small, -120# sample with selective duplication was recommended to screen coarse-grained gold anomalism and a program of sampling covering an area thought to be prospective was enacted.Samples returning anomalous Au were analysed in duplicate and if the results demonstrated reproducibility, indicating fine gold only, the sample site was assigned a high priority.It was found that most of the reproducible samples clustered in one area û Spring Gully. The results of this sampling program led to immediate identification and, ultimately, the successful delineation of the Spring Gully gold deposit near Wattle Flat.

Jan 1, 2004

By Coronel PT

Like companies in other sectors of industry, mining companies are experiencing significant problems with low labour productivity, high labour turnover, and accidents. Increasingly, companies are recognising that good training is a vital factor in dealing with these problems. One such company is Aberfoyle Tin Limited. Early in 1979 the company engaged P.A. Consulting Services Pty. Ltd. (P.A.) to upgrade and formalize its miner training procedures. P.A. developed a programme using their Process Analysis Method of Training (P.A.M.T.) and trained a company trainer in its use. As a result of its application and the establishment of a formal training school, the rate of production of trained miners has been greatly increased. Despite some problems caused by lack of resources at the mine, the trainees graduating under the new scheme have been shown to be of comparable standard to those produced by the previously used "on the job" training method.

Jan 1, 1980

Investment decisions in the Australian mining industry are often made without awareness of the impact of risk on project outcomes. A fundamental change in thinking is required to move away from the traditional attitude of æcushioning the blowÆ towards a measured approach to project risk. Such an approach involves quantifying and understanding project uncertainty so that investments may be shielded from downside risk while at the same time exposed to upside potential. Communication and collaboration between study teams and corporate financial managers must be improved before the industry can improve its project investment record. Monte-Carlo simulation provides a way to quantify and understand investment risk, but its accuracy depends on how well the variability of input parameters is estimated. Research in this area is currently centred on quantifying uncertainty in mineral resource estimation using new conditional simulation techniques, but a less-rigorous method can be applied in practice to begin the education process and develop the required awareness at board level.

Jan 1, 2003