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By X Li, H Alehossein

The oscillating disc cutter (ODC) is an innovative technology for the continuous excavation of hard rock. This paper will discuss:the reasons for its development;its method of operation;current experimental results and mathematical modelling undertaken at the CMTE; andapplications in the mining and rock excavation industry.

Jan 1, 1999

By Granholm S

The current emphasis within the mining industry to reduce the cost of production has stimulated interest in the fields of maintenance and operational reliability of capital intensive mining equipment. From an economic point of view, high reliability is desirable to reduce the maintenance costs of the systems. Two graphical methods consider reliability analysis. The first one, the method of Total Time on Test (177)-plotting deals with the reliability data which are free from trend and serial correlation. The second method which is based on time dependent modelling approach deals with the data which are not free from trends and serial correlation. The examples show how these graphical methods can be used to calculate the optimal maintenance intervals for components or systems.

Jan 1, 1991

By C R. Headley, S O. Hille, N P. Jacob

The redevelopment of the Telfer Gold Mine in the Pilbara region of Western Australia was primarily based on the construction of a 17 Mtpa dual train concentrator coupled with open pit and underground mining operations. The unique copper-gold orebody at Telfer requires the application of complex flotation conditions normally reserved for base metal concentrators, where two competing minerals are managed into separate products. This paper describes the commissioning of the flotation circuit, the process modes and the master/slave relationship that flotation has with a variable orebody.

Jan 1, 2007

By Y Gu, W McCallum

Mathematically sophisticated methods are now in common use for metal balancing of complex separation flow sheets at many concentrators. These balances usually entail minimisation of the sum of weighted squares of data adjustments subject to flow sheet constraints. The adjusted data provides numerical consistency across the complete flow sheet to facilitate performance calculations. A mine with multiple ore sources can be considered as a flow sheet with the end node comprising the concentrator and its products concentrate(s) and tailings. If the mass transfer and grade estimates for each ore source are sufficiently reliable, a similar metal balancing approach can be used for combined mine and concentrator data. Comparison of balanced and measured assays and mass movements provides useful guidance to security of marginal grade ore and possible dilution problems. This paper includes a summary of results from a case study based on a mine with multiple ore sources.

Jan 1, 2002

Based on a principle developed at a South African Mine, the CSIR developed a device with which the alignment of guide rails in mine shafts could be measured. Originally the technique could only be used to obtain guide misalignment values at the bunton sets. At the time this was considered adequate since it was assumed that guide realignment could only be done at the support points anyway. The technology was developed further and now it is possible to obtain æcontinuousÆ guide profiles from the measurements. Software was developed with which a guide realignment schedule can be drafted and the shape of the realigned guides can be predicted. A measuring system based on this technology is being used to conduct guide alignment measurements in shafts. The data is then analysed and a realignment schedule is recommended in consultation with the mine. Such a schedule may be prioritised so that the worst sections in the shaft are dealt with first. The measurement hardware and analysis software are described. Examples are presented that illustrate the principles and highlight measurement errors. A case study illustrates measurements recorded in a newly equipped shaft. A repeat measurement, 18 months later, shows the effect of recommended realignment as well as the change in guide alignment over this period.

Jan 1, 2005

The design, construction and operation of a 500,000 tonne per year Carbon-In-Pulp (C.I.P.) plant at Kambalda embracing the period from 1980 to 1982 has been previously discussed (Sceresini, 1982).Since that time the annual throughput rate has increased to 780,000 tpy.This paper discusses the changes and improve-ment made to allow this increased production to occur with minimal capital expenditure.

Jan 1, 1984

The New South Wales Department of Mineral Resources has, since 1974, administered the Derelict Mines Rehabilitation Program (DMRP) to reduce the environmental impacts of abandoned and orphan mine sites. The application of the DMRP is presented in case studies of sites from the South Maitland Coalfield featuring residual drainage of acidic and saline water in a semi urban and rural community setting. The acidity here is typically derived from iron oxidation in shallow underground coal mine workings and in surface emplacements of coal washery reject materials. This paper presents summary information on AMD investigation, monitoring and rehabilitation. The experiences of community expectation, stakeholder consultation and peer review are discussed.

Jan 1, 2003

By Morandini AF, Occella E, Clerici C, Mancini R

This contribution presents the first results of an experimental research aimed at finding an unified description of the first stages of a rock comminution process. With reference to the case of the jaw crushers and to the specific subject of the comminution law, the tests reviewed and analysed in this contribution have been carried out, at a laboratory scale, on five different materials (limestones, quartzite, serpentinite) at different reduction ratios and feed rates, and accurately recording both total power and idle running power. The analysis of the results has shown that: ò the grain size distribution of the products complies with a modified form of the Rosin-Rammler equation, already found to be well suited to representing the grain size distribution of blasted rock in previous works by the authors; ò observed trends of the consumed power at increasing reduction ratios is steeper than predicted by the classical Rittinger, Kick and Bond laws, Rittinger law representing however a closer approximation of the experimental results; and ò a more accurate description of the experimental results is provided by a modified form of the Rittinger law. Accuracy of the semi-empirical expression has been found to be usually better than ten per cent by comparing actual results with expected Results.

Jan 1, 1993

By A Sellgren, M R. Carstens, R Visintainer

There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.

Jan 1, 2005

While South Africa is well endowed with mineral resources, it is generally accepted that its future will be determined more by the development of its human resources than its mineral wealth. The country has throughout its modern history suffered from an over-supply of unskilled labour and a shortage of skilled and professional manpower. There has furthermore always been an over-reliance on Whites as an internal source of professional manpower, supplemented by immigration wherever possible. Better utilisation of other population groups in professional positions has been hampered by the general lack of education and training among such groups. Although many problems still remain, there are emerging trends which are likely to positively affect the training of professional manpower in the future. The direct and indirect influences that are likely to affect professional training at the macro level include 1. government policy and objectives in respect of manpower education and training, 2. the emergence of technikons as fully- fledged tertiary education institutions, 3. demographic trends in South Africa as they pertain to education, 4. political and statutory developments in the country, 5. industry involvement in tertiary education, and 6. professional registration.

Jan 1, 1986

By Jifan X, Yongyu W, Liangjing L

Shallow interception of groundwater is a special dewa- tering form in the specific geological and hydrogeological conditions. It has an economic and technical effect. The roof of the Fankou Lead-zinc deposit is the Hutianqun aquifer made up of the limestone of the upper Carboniferous system. - A "water-bearing basin" is surrounded by the aquifuge and the aquitard below ¦0 m level at the Shiling Hill section in the Hutianqun aquifer. Based on the natural conditions, an interception gallery is excavated at -40 m level out of "the water- bearing basin", the other gallery excavated at ¦0 m level in the poor water-bearing zone of the Jinxing Hill. During 20 years of experience, the better interception effects have been gained.

Jan 1, 1988

By E Villaescusa

This paper describes a methodology for the design of mine pillars at the McArthur River Mine. The pillar strength is calculated using a method that accounts for confinement, pillar geometry and intact rock properties. The average pillar stress was calculated using in situ measurements of vertical stresses at shallow depth and the tributary area method in conjunction with numerical modelling. Observations of pillar behaviour indicate that an existing pillar stability graph may be slightly conservative and further adjustments for the local rockmass conditions are needed. The results to-date indicate that all mine pillars are stable for a range of mining geometries at McArthur River Mine.

Jan 1, 1998

By R G. Barker, N Mortimer

In New Zealand, platinum group metals (PGM) occur in three main geological environments of economic interest: layered mafic igneous complexes, the Dun Mountain Ophiolite Belt, and in association with placer gold deposits. Most of the layered mafic complexes with PGM potential occur in the Median Batholith. These include the Longwood (Permian), Bluff (Permian), Riwaka (Devonian) and Rotoroa (Jurassic) igneous complexes. Exploration of the Longwood Complex discovered PGM associated with gabbroic rocks. Best assays to date include a 1 m drill intersection of 1 g/t Pt + Pd and float rock with 3.0 ppm Pt and 3.3 ppm Pd. The Greenhills complex at Bluff consists of basal dunite overlain by wehrlite and gabbro. PGM occur with chrome spinel in the basal dunite and Pt geochemical anomalies have been identified associated with the wehrlite-gabbro contact zone. The Greenhills complex has some similarities to Alaskan-Ural type complexes.Reconnaissance exploration in the Dun Mountain Ophiolite Belt has identified PGM geochemical anomalies, but no follow-up work has been carried out. During the late 1800s and early 1900s, PGM were recovered as a byproduct of placer gold mining in Southland. Placer gold prospects with PGM potential include the Waiau River, deposits flanking the Longwood Complex and some Southland beaches.

Jan 1, 2002

Estimation of operating costs in the nickel production industry requires a detailed analysis of material flows from mine to smelter to refinery. Despite the small number of nickel producers compared to other base metals, the existence of two very different ore types (sulphide and laterite) and a wide variety of mining and processing technologies make the identification of these flows of critical importance if an accurate global picture is to be obtained. Smelting and refining processes in nickel metallurgy have evolved with a high degree of adaptation to specific operating conditions in different locations. Overall costs are calculated by combining individual cost elements for each unit in production chains from mine to saleable metal product. The average cost of western world primary nickel production in 1995 was US$2.07/lb ($4560/tonne). Average operating costs remained virtually unchanged in the three years to 1995 after an 8.5 per cent fall in 1993, but a 3.9 per cent increase to $2.15/lb is expected for 1996. A major factor in this rise results from the lower prices of copper and cobalt this year, reducing the by-product credits available to major producers.

Jan 1, 1996

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

By Strickland R. E J

Heap leaching is establishing itself as an efficient method for the extraction of gold from low grade ore. It has the advantage of low capital costs, low operating costs and rapid startup. However, not all ores are amenable to heap leaching. It is only applicable to well oxidized ores that have reasonable permeability characteristics. Ore with excess fines or clay often display low permeability and are unsuitable for heap leaching.In this study, an attempt has been made to increase the rate of cyanide leach solution percolation by flocculating clay particles or reducing the surface tension of the leach solution. A wetting agent was found to decrease the rate of gold dissolution, possibly by presenting a hydrophobic surface to the gold particle. Flocculation of the clay increased the solution flow rate. The flocculation agent had no affect on the total gold leached but decreased the leaching rate.

Jan 1, 1992

By J Mauk

Water-rock reactions such as pyrite oxidation and calcite dissolution strongly influence the pH of pit lakes that develop in open-cast mines after mine closure. The Martha Mine, located in world-class epithermal Au-Ag deposit at the southern end of the Coromandel Peninsula, New Zealand, is scheduled to close in 2007, after which the pit excavation will be rehabilitated into a recreational lake; the first pit lake in New Zealand. Mineral distribution maps from XRD results of 130 andesite samples identify regions that could produce or consume acidity in the future pit lake. Maps show pyrite, calcite, adularia, albite, illite and chlorite distribution in the wall rocks. These data identify five alteration mineral associations: potassic, propylitic, weathered, oxidised and weakly-altered. Pyrite occurs in potassic, propylitic and weathered associations, whereas calcite is restricted to propylitic association in the northeast wall. Subaerial, epilimnion, and hypolimnion exposure zones describe the physical and chemical weathering processes that are likely to occur in regions of pit wall, and the potential effects on lake water chemistry. The pH of epilimnion water will depend on the relative abundance of pyrite and calcite in the propylitic association in the northeast wall, whereas hypolimnion pH will depend upon the frequency of whole-lake circulation events that distribute dissolved oxygen to deep lake layer. In mines with diverse alteration associations, mineral distribution maps are an essential precursor for accurately estimating water-rock reactions in pit lake environments. Data may be directly incorporated into a quantitative geochemical model of future pit lake water chemistry.

Jan 1, 2002

The perception of the mining industry in the Australian community has changed considerably over the last four decades. This has been partly brought about by changing values and expectations of the Australian community as well as by global factors. The legal environment for the Australian mining industry has undergone significant changes. Among them, the High Court's Mabo decision which confirmed native title rights as part of the common law and environmental legal developments are dealt with particularly. It is suggested that the Australian legal environment is not necessarily the prime cause for Australian mining companies taking their investment off shore. This is a summary on how native title impacts on land tenements and some of the major issues that emerged since the `Mabo decision' and the Native Title Act 1993 are discussed. Environmental legal developments have resulted in liability facing directors and senior management in compliance matters .and in operating mining and other businesses because of changes in community expectations. In the next decade it is suggested there will be many drivers for more changes in the legal environment. Some of these are touched on including the changing roles of the Commonwealth and State Governments, the High Court as -law-makers and the changing relationships with indigenous people in Australia and in overseas countries. The changing legal environment for mining demands a national approach in many areas on the proposition that resource based industries are part of a national industry. The uniform law approach among the States has been taking place but this needs to further. An appropriate task force should be forward to review the entire legal structure and regulations affecting mining on a national rather than a State basis . The mining industry will need to work with expectations of a changing community which have powerful, but sometimes contradictory, interest groups.

Jan 1, 1997

Permian ultramafic and associated rocks form a belt in East Nelson and contain widespread, but minor, chromite and copper mineralisation and some mining was carried out last century. Since mining ceased, about 1910, little mapping of the belt has been carried out although its origin has been debated vigorously. Recently it has been inferred to form part of a ophiolite sequence, which has been tectonically disrupted to form a melange, and several 'plate -tectonic' models have been proposed. Mapping in the central part of the belt has shown that mTlanges are to the east of the ophiolite sequence. Faulting is widespread so that in anyone section part of the sequence may be absent. Some of the faulting is difficult to recognise and probably took place during or soon after the sequence accumulated. Other faulting is clearly of Cenozoic age and includes major NNE striking faults, with large horizontal displacement, and approximately east-west striking faults with almost entirely vertical movement. The writer agrees that 'plate tectonics' could provide an acceptable explanation for the origin of the ophiolite sequence but the models so far proposed do not take into account the nature and field relationships of the rock units present. Copper Mineralisation is largely controlled by the younger faults, particularly those striking about north-east, and is largely confined to the western part of the ultramafic rocks particularly where slivers of the volcanics of the adjacent Lee River Group are enclosed. Mineralisation, along NNE striking shear zones, has recently been found in the volcanics some distance from the ultramafic rocks. The chromite mineralization is in the form of primary layering in the basal part of the ultramafic belt although in places it has been concentrated into lenses probably during serpentinisation.

Jan 1, 1977

Paddington processing plant is located approximately 30 km north of Kalgoorlie on the Menzies Highway and is owned by Placer Dome Asia Pacific. First mining was from the Paddington Pit, but in subsequent years the plant has had a history of treating ores from a large number of sources, and has used several different methods to reconcile mining and mill production. Reconciliations are necessary to keep a check on the quality control of mining and grade control processÆs. There is a need to be able to identify and resolve issues that will affect the profitability of the organisation quickly. They are also used to check the quality of the resource/reserve statements, and allow the accurate and timely payment of royalties to stakeholders. During the formation of the Kalgoorlie West operations when Delta Gold Limited and Goldfields Limited merged in 2001, the complexity of reconciliations increased dramatically. The expansion of the scope of reconciliations to include two mills, four underground mines and seven open pits, and ore from one deposit to both mills meant that a revised strategy was essential. A variety of issues have arisen over the years with discrepancies occurring when reconciling both tonnes and grade. There are many ways to approach reconciliations, and in recent times these philosophies have been widely debated on site. A consistent and logical approach that takes into account many different sources of ore, as well as different methods of delivery to the Run of Mine stockpiles is therefore necessary. This would standardise the different approaches taken by the various operations that combined to form Kalgoorlie west. The new method reconciles mill production back to the individual ore sources, and produces reconciled-mined tonnes and grade based on the mill throughput and the change in stockpiles. There will generally be a small discrepancy between the claimed mined tonnes produced (and grades) and the mill production. This needs to be highlighted to the operations concerned if it considered unacceptably large. Paddington mill over the last few years has had up to ten sources of ore each year, and up to 15 different stockpiles being processed during each month from those various pits. This combined with the need for a blended oxide/fresh feed, whilst striving to deliver a consistent (grade and hardness) product to the mill, has meant that reconciliations have been very difficult.

Jan 1, 2003