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By Gadsden R. W

Physical and chemical requirements are defined for coke and ferrous materials used in modern high productivity blast furnaces operating in Australian conditions. Recent developments in the type of equipment required to be installed at the steelworks to ensure these requirements are described with illustrations from current plant practice provided.

Jan 1, 1976

Design of underground extraction layouts to protect surface improvements is an important area of subsidence research in the Coal Mining Engineering Branch of the Department of Mineral Resources, New South Wales, Australia. Some conventional partial extraction layout are important with reference to coal recovery and surface subsidence. The analysis ofsubsidence data collected from field surveys over longwall panels in the Southern Coalfield of New South Wales allows assessment of the effect of pillars left unmined between the longwall panels in reducing surface subsidence. The availability ofa wide variety of layouts with ranging degrees of surface movements affords considerable flexibility in designing layouts to suit a particular situation.Total extraction of coal should be the aim as far as possible. Partial extraction layouts should only be considered when surface subsidence movements caused by total extraction are not acceptable to the surface improvements.

Jan 1, 1985

By Orid A

A fast, non-contact technique for measuring sizes of rock fragments on a conveyor belt is presented. An image processing technique called active stereopsis is used which makes use of a light stripe projected on to the surface of the fragments on the conveyor belt. A CCD TV camera is used to capture the shape of the distorted light stripe. the video image of this shape is then processed by a computer program so that the 3D profile of the surface can be obtained by triangulation. The sizes of the rock fragments are then calculated from this profile. The speed of the technique is improved by calibrating the light stripe system before measurement begins so that the profile of the fragment surface can then be measured using simple geometry. The technique is fast and highly parallel so that it is able to operate in real time.

Jan 1, 1990

The nickel ores mined in New Caledonia for one century are mainly silicate ores. These ores are nickel enriched saprolites, formed by partial weathering of peridotites (predominantly harzburgites and some dunites), serpentinised to varying degrees. Saprolites constitute the lower horizon of lateritic soils, sometimes up to 100 metres thick, developed on peneplains now greatly modified by erosion. Saprolites are generally overlain by laterites, a more weathered horizon, where the main components are iron oxy-hydroxides with a low nickel grade. The structure of saprolites depends essentially on the serpentine content of peridotites and, on the other hand, serpentine minerals may have a high nickel content and, so, represent important nickel bearing minerals in silicate ores. Two types of serpentines can be found in nickel ores from New Caledonia: ò primary serpentines, formed by hydration of olivine at temperatures below 400¦C, during overthrusting of peridotites in late-Eocene (Paris, Andreieff and Coudray, 1979), are generally very abundant; ò secondary nickeliferous serpentines, associated with other sheet silicates in garnierites, are now relatively scarce but garnierites were selectively mined one century ago, because of their high nickel grade.

Jan 1, 1996

South Africa is the world's largest producer of gold. The survival of its gold mining industry is dependent, to a large extent, on the successful implementation of new mining technology which reduces the operating costs. Gold mines of the country have a record of a high operational cost per tonne of rock excavated. The geology of the gold-bearing rock, in addition to the mining depth and the gold recoverable grade, profoundly affect the profitability of the industry. Among the other mining operations, drilling and blasting take a fair share of the mining cost. It is therefore proper to implement a dynamic approach of technological review aimed at combating the escalation of mining costs. Over the years, the industry has moved away from labour intensive activities. Mechanised operations are introduced where possible. Management techniques are oriented more towards better utilisation of human resources and machinery so as to enhance productivity in the stopes. This paper addresses the issue with particular reference to blasting operations in the stopes of deep gold mines. It reviews the conventional drilling and blasting techniques. It outlines some innovative changes brought about in the course of recent years with the aim of optimising productivity and the stope efficiency in particular. It focusses on the peculiarities of the blasting technology in deep mines. It discusses the issue of interaction between the high stress fields underground and the blasting generated stresses on rock fragmentation, as well as their impact on the remaining excavations. It anticipates the concept of the new technology of selective blasting in stoping. Finally it puts forward the crucial role played by management of the human factor underground.

Jan 1, 1995

By D E. Langberg, J S. J va, D R. Swinbourne

Specifications on the types and levels of impurities tolerable in metals are becoming increasingly stringent, and are pushing the limits achievable with conventional refining technologies. Particularly difficult is the removal of electrochemically noble elements with low volatilities, such as copper, from more active host metals such as lead, iron and aluminium. Electrochemical refining, utilising the ability of certain solid electrolytes to selectively transport copper or other impurity cations away from the molten host metal into a separate refining phase, may provide an answer to this problem. Numerous studies on solid electrolytes used in concentration sensors have been reported, as well as a limited number on metal refining. Oxygen anion conducting solid electrolytes have been applied to the deoxidation of copper and steel while cation conductors, eg ¯ -alumina and Nasicon materials, have been used to remove lithium and sodium from aluminium. However, solid electrolytes have yet to be applied to the removal of noble elements. The behaviour of solid electrolytes under the extreme conditions of molten metal refining is not well understood. This paper will examine the potential use of solid electrolytes to remove noble metals such as copper from active host metals such as iron. The suitability, and selection criteria of available solid electrolytes for implementation in the metal refining industry in the future will be discussed. In particular, the stability of Cusicon, a copper superionic conductor potentially suitable for use in metal refining, has been assessed and the results of the experiments are presented.

Jan 1, 2000

While the potential for the discovery of new high grade resources exists, it is almost inevitable that the ore resources used to provide society's ongoing demand for primary metals will deteriorate over time as the higher grade reserves are exploited first and are progressively depleted. This deterioration in quality of metallic ore resources will bring about significant interactions with other resources such as energy and water, resulting in an increase in the amount of these resources required per unit of primary metal production. In this paper it is shown that as ores deteriorate in quality, the contributions of the mining and mineral processing stages to the life cycle-based embodied energy and water of primary metal production will increase significantly. Therefore efforts to reduce the impact of deteriorating ore resources on energy and water consumption should focus on these stages.   The results from life cycle assessments of the production of various metals by a number of different processing routes, particularly copper and to a lesser extent nickel, have been used to identify a number of opportunities and technologies for reducing the energy consumption in the mining and mineral processing stages, including: comminution, eg high pressure grinding rolls, stirred mills, ore sorting, preconcentration, advanced blasting techniques, advances in diesel technology for loading and hauling, alternative processing routes, eg heap leaching, in situ leaching, water treatment and re-use, water quality 'fit for purpose', dry processing, floating modules to reduce evaporation, and paste thickeners. All the above and existing developed flotation technologies can impact on the mineralogy of the concentrate supplied to the smelter. Removal of gangue minerals early on in processing may have further downstream process implications on fuel and water requirements. The above technologies are in various stages of development, with some more advanced than others. However, all can be expected to play their part in improving the sustainability of the Australian mining industry.

Jun 1, 2010

By M Wortley, O Gu, D La Rosa, J McMaster

Metso Minerals Cisa have developed VisiofrothÖ û a system which calculates parameters of the froth surface using vision from remote cameras mounted about individual flotation cells. The parameters calculated from this system can be utilised within process control strategies to achieve stabilisation or optimisation of the flotation process. As part of a JKMRC AMIRA P9 field campaign, froth vision was collected from various cells operated at different air rates and froth depths within Rio TintoÆs Northparkes copper roughing and scavenging circuit. At the same time, samples were collected to determine the cell metallurgical performance at each operating condition. These froth images have been processed using the VisiofrothÖ system with froth velocity, bubble size, froth collapse rate and various froth colour parameters calculated. These parameters have been compared to the measured concentrate flow and concentrate grade produced at each condition. This analysis shows that the concentrate tonnage flow is strongly correlated with froth velocity whereas the concentrate grade is best correlated using froth velocity in combination with a bubble stability parameter which affects the bubble size distribution on the top surface of the froth. This paper summarises the results from this analysis as well as an overview of the VisiofrothÖ system and the parameters that are measured by the software.

Jan 1, 2007

By Moort van J C

A new low-intensity magnetic separator which operates by spinning particles in a continuously rotating magnetic field is able to reduce particle entrapment of non-magnetics to an almost insignificant level. In such separators the removal of ma

Jan 1, 1997

Epithermal deposits have been defined as the lower temperature end of a spectrum of hydrothermal mineral deposits and are inferred to have formed near the EarthÆs surface. The preservation of an epithermal gold deposit in an Archaean craton is rather problematic, especially when such deposits form clusters or groups as reported for the Pilbara and Yilgarn cratons. For two of the better studied examples of epithermal gold deposits in these cratons, Becher and Wiluna, the evidence that they formed near the Earth surface is non-diagnostic, and the epithermal origin appears uncertain. Despite the simplicity of the original definition, there have been numerous errors in classifying epithermal gold deposits. It is suggested that these errors are primarily due to poor criteria defining the group as there is limited evidence of poor observational science being the cause. The criteria being used to recognise epithermal gold deposits include tectonic setting, ore element suite and quartz vein textures. None of these are diagnostic of epithermal deposits and their link back to the original low pressure-temperature definition of the class is tenuous. There has been definition creep over time as new observations on potential epithermal gold deposits become accommodated within a flexible definition. There is some urgency establishing and then using criteria to reliably identify epithermal deposits. Distinction of epithermal gold from weathered gold deposits is an important step. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Okura T, Hino J

Coal utilization for copper flash smelting in Japan was initiated due to the sudden upheaval in the price of oil in the last ten years. A major portion of the heavy fuel oil has already been replaced by coal resulting in a corresponding decrease in energy costs. In addition to energy cost savings, an interesting metallurgical phenomenon was observed in flash smelting operations. Unlike oil combustion, coal is not burned completely in the shaft. A considerable fraction of coal particles remain on the surface of slag and are burned at the settler. Chemical investigation has shown that oxygen potentials at the settler have consequently decreased, bringing the slag and matte phases into reducing conditions, thus oxidation and reduction can coexist in one flash smelting unit. As a result, a decrease in magnetite and copper contents in the slag, elimination of furnace hearth build-up and dissolution of intermediate layer between matte and slag have been observed. In general, these led to improvements of furnace operations. However, thermodynamic investigations have shown that some minor elements such as As, Sb, Bi and Pb concentrate from slag to matte. Results evaluated on the basis of thermodynamic data relatively agree with practical observa- tions. Consequently, for coal utilization in flash smelting operations it will be necessary to control oxygen potentials from the stand- points of copper loss in slag and minor element Distributions.

Jan 1, 1987

By J D. van Wees

Preliminary project evaluation is relevant to the evaluation process of the decision makers (or executives) prior to making the critical business choices. Important to the assessment is an integrated sensitivity, scenario and risk analysis at every stage of a mining project. This should include the evaluation of different options taking into account uncertainties. Construction of interactive financial computer models where each element is functionally integrated into a fully integrated life-cycle allows rapid and automatic study of the sensitivity of each element through changes in the value of an input. The scenario analysis is the effect of changing more than one input at a time, organised through scenarios in a decision tree. Risk analysis is an integrated analysis of the effect of all uncertainties of the parameters, using Monte Carlo simulation. Key to the asset decisions process is that the decision maker is provided with the essential integrated decision information. We have clustered this information into several scenario groups. Within each group, two levels of uncertain information are distinguished: discrete scenarios critical for the decisions; and remaining uncertainty within the scenario (risk analysis) which can be modelled by continuous probability density functions (pdfÆs). For an asset, the relevant scenarios in each group and the associated continuous pdfÆs need to be defined. When the scenario groups and associated pdfÆs have been defined for the asset, the decision process can be started by structuring the different scenario groups in a Scenario Tree. A Scenario Tree contains decision and end nodes. Each end node corresponds to a completely defined mine project or asset model. The calculations for each end node result in a set of stochastic realisations for the reserves, production forecast, cash flow, and profitability indicators (NPV, IRR, DPR). Thus, a deterministic and fully probabilistic multi-commodity analysis tool is provided to investigate the sensitivity and robustness of decisions.

Jan 1, 2003

By Harris RW

Acoustic Emission structural integrity evaluation tests rely on the validity of the detected acoustic emission data and the ability of the practitioner to both analyse and interpret the data to make a correct decision on the future use of the structure tested. Unfortunately with acoustic emission surveillance testing, it is not possible to know that all the available data has been assessed property. The equipment sensitivity, threshold settings, and event capture capacity, when combined with the decision making ability of the operator in real time, make it very difficult to achieve reliable integrity evaluation. The main problem is to interpret the data and so any monitoring system should involve expert systems in conjunction with both acoustic emission and other operational monitoring data to maximise the utilisation of the large amounts of information now available from operating plants, mines and structures.

Jan 1, 1991

By Gregory O, Winters BI, Garlick C, Rogers H, Ye ZC

BHP New Zealand Steel produces iron from titaniferous ironsand by a direct reduction process comprising multi- hearth furnaces/rotary kilns/electric iron melters. The electric iron melter is a six-in-line rectangular submerged-arc furnace which takes the partially reduced ironsand (80% metallization) from the rotary kiln and completes the reduction process to produce iron of nominally 3% carbon. As the melter operates at around 1500 ¦C and under very hostile conditions, it is near-impossible to obtain any basic operating parameters such as the velocity and temperature distribution in the slag and in the molten iron. As a first attempt to understand the operating conditions inside the melter, a scaled room-temperature model using wax and water to represent the slag and iron, was constructed. This paper will report on some of the preliminary model results on the temperature distribution.

Jan 1, 1995

The face of project evaluation is changing continuously, making it ever more critical to get a clear understanding upfront of the objectives, decision-making processes and criteria of the project proponents. Requirements are usually significantly different for emerging æjuniorsÆ compared with long established major mining houses and companies in developing countries compared with western companies. Requirements are also different for different types of evaluations, such as due diligence studies compared with feasibility studies of æownedÆ projects and there are often key misunderstandings around the use of the term æbankableÆ. Further, it has become increasingly important with increasingly remote and lower quality resources to understand risk relativities such as infrastructure compared with the core processing facilities. This has also driven the need for more trade-off studies to determine the best balance between critical issues, such as optimisation of the interface between mine and processing plant, capital versus operating cost and automation versus labour. In every project evaluation, it is also critical to consider emerging trends and changing requirements and standards such as sustainability and community interface. Finally, the inescapable drive to reduce time to market has driven changes such as increased use of more standardised designs and innovative approaches to the transition from project development to execution. This paper begins with a brief review of the different objectives and risks of each project development stage to establish a framework for subsequent discussion of the different requirements of different types of companies in different locations, different types of evaluations and different types of projects and project components. This is followed by a review of changing requirements and standards and some innovative developments in sustainability and community interface are presented. Finally, the paper outlines a number of developments in the area of operational readiness planning that focus on minimising the time to achieve maximum return on investment.

Jan 1, 2009

By Golosinski T. S, Jorgenson J. D

Several methods are available for inspections of mine shafts. These involve use of inclinometers, moving beams, inertial platforms and decelerometers. Inspections which use decelerometers are of most interest since they allow assessment of conditions of shaft steelwork, conveyances and the shaft itself. This assessment is based on recording and analysing dynamic behaviour of shaft conveyances. Sample inspections of several WA shafts confirm feasibility of using this method for periodic shaft Inspections.

Jan 1, 1995

In recent years stricter requirements imposed variously by the Companies Acts, auditors and the Stock Exchanges have resulted in annual financial statements of mining companies becoming more detailed, informative and useful. Standards of reporting on ore reserves have not kept pace with the improvements in financial information disclosure, despite the fact that ore reserves are usually the most important asset of a mining company. The ore reserve reporting practices of fifteen leading Australian mining companies are analysed against important specific criteria. In terms of detailed and meaningful disclosure, there is scope for major improve- ments in annual ore reserve reporting Practices.

Jan 1, 1981

There are countless petroleum and mineral fiscal systems throughout the world. This is because many petroleum and mineral producing countries have developed their own methods of calculating government take through fiscal evolution or individual negotiation. Those countries fortunate enough to have petroleum and mineral reserves within their national boundaries are naturally reluctant to yield this resource without a reasonable return for their population. As resource companies are perceived to be enormous conglomerates with endless amounts of cash and resources, governments and the general public demand reasonable division of production while these finite resources last. On the other hand, because companies engaged in the exploration for, and production of, minerals, oil and gas have to be large or lucky (preferably both) to sustain the great physical and commercial risks involved, the income and profit figures look so large that the general public sees them as an acceptable target for taxation. Taxation of the resource industry has been one of the industry's greatest cash flow problems through the years. Allen and Seba (1993) attribute this to the fact that the most equitable tax systems are those that affect the widest possible total of the population.

Jan 1, 1996

By E Topal

There are presently no suitable underground mine production scheduling optimisation models available for application to sublevel stope mining. Scheduling underground production for maximum return is therefore still a manual process, which generally involves scheduling production from the next available highest cash flow stope within the operational constraints of the project. In most mining operations, the scheduling problem is too large and complex to guarantee truly optimal results through manual scheduling. This paper reviews some general optimisation studies that have been proposed for underground hard rock mining. Furthermore, an example of a mixed integer programming model is presented for a small conceptual sublevel stoping operation. Comparative results of a schedule generated by a mixed integer programming (MIP) production scheduling model and a manually generated model on a nine stope example is presented. Results indicate that the potential benefits of the MIP production scheduling model for the purpose of maximising NPV are significant. Finally, a new constraint was formulated to limit multiple exposures of fill masses for use in an existing MIP production scheduling model. Testing of the formulation took place on the central stope of the nine stope example, which showed that the formulation performed its task without breaking other operational constraints.

Jan 1, 2007

This paper discusses a number of examples of how environmental factors have been incorporated into the water management aspects of mining projects. One example is the Kingston Lignite Project in the South-East of South Australia where the most significant environmental issue was considered to be the effect of drawdown from mine dewatering and depressurization upon the use of groundwater. By proposing an alternative mining method - the use of floating dredges rather than a two-pass dragline method - drawdown effects would no longer be a concern. A second example is the Pine Creek Gold Mine in the Northern Territory. In this case the principal area of interest from an environmental viewpoint was water management - in particular effluent disposal, contaminated seepage from overburden and tailings, and project water supply. Through an integrated approach to the management of wastes and water the potential for water quality impairment was significantly reduced and external water supply requirements were also significantly reduced.

Jan 1, 1987