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By Bearman R. A, Parkin R. M

In the comminution industry cone crushers are widely used for secondary and subsequent stages of size reduction. Traditionally cone crushers have been operated and monitored manually. Alteration of discharge setting is now commonly achieved via hydraulic means, however, compensation of liner wear can still involve plant shutdown and loss of production. Drift in discharge setting due to liner wear is still a major problem that must be addressed to improve product quality, consistency and reduce recirculating load. The continuous demand for better quality products and the high cost of reprocessing or discarding unsaleable material, highlights the need for re-examination of the technology associated with the crushers to ensure optimum control and system efficiency. A collaborative project between Pegson Ltd, one of the leading UK manufacturers of jaw and cone crushers, De Montfort University Leicester, and Transfer Technology plc was established to address the technological requirement for automation of the control of cone crushers. The machine chosen for the study is a 900 Autocone cone crusher manufactured by Pegson Ltd. The design philosophy is based on a mechatronic approach providing a complete solution through a distributed network of intelligent sensors, artificial intelligence technology and adaptive control. The modular design of the system ensures a progressive sophistication in technology that allows the automation to be phased in as required. This will ensure maximum benefits to all sectors of the aggregate industry. It is estimated that the automation will result in savings of around ten per cent. The savings will result from minimising the production of unsaleable products by reliable condition monitoring and automation of the control and maintenance of system parameters to optimise system efficiency. Extension of the methods and principles into the mining sector is anticipated. The control over the size of crusher product will offer great benefits to the mining industry with significant implications for subsequent milling and beneficiation processes.

Jan 1, 1995

The demands of the economy require larger manufacturing facilities using greater quantit- ies of raw materials which must be mined, handl- ed, stockpiled and recovered with efficiency and dependability. All over the world, mining com- panies, steel manufacturers, power stations and process plants are not only seeking but finding methods of increasing outputs and'reducing costs in the field of materials handling. In mining bigger continuous mining machines and shovels, larger trucks and crushers are digging and processing greater quantities of differing materials which have to be handled and shipped at rates once thought to be impossible. To implement such schemes demands the blending of a lot of diverse-equipment, mining machinery, bins, feeders, reclaimers and it is here that the belt conveyor assumes a role of ever increas- ing importance. Significant developments have taken place in the seventies with respect to conveyor belt transportation; not only in the systems but also in the components which combine to make such systems work efficiently.

Jan 1, 1976

By L Reynolds, N Whetter, S C. Cox

The Reefton Goldfield has had the largest hard-rock gold production (64 t Au) on the West Coast of the South Island of New Zealand, and is currently under renewed development by Oceana Gold. The gold predominantly occurs in variably sheared quartz veins that are associated with zones of tighter, shorter wavelength folds in the host Greenland Group metasediments. The quartz veins typically occur as a series of plunging shoots that align with specific fold limbs or fold hinge zones. Shear zones containing disseminated mineralisation and quartz veins have thickness variations that relate to the angular relationship between the shear and host-rock bedding. Exploration strategies and targeting can be developed around both types of structural control.

Jan 1, 2005

By Porter I

Rock mass classification systems have emerged as a powerful tool which can be used for assessing ground conditions and determining support requirements in underground mines. They should not be used as a substitute for complete engineering design, but rather as a supplement to observational methods and analytical study. In general, the use of rock mass classification is attractive, but each classification system has various deficiencies. Use of any particular system should be made only with knowledge of that systems limitations. It is desirable to employ a number of systems and design methods which will allow for comparison and lead to a better understanding of the rock mass condition.The Rock Mass Quality system (Q-System), developed by the Norwegian Geotechnical Institute, and the Rock Mass Rating (RMR) System, Bieniawski, were designed primarily for civil engineering structures. Laubscher et al (1978) further developed the RMR-system specifically for rock mechanics engineering in the mining industry. A method of stope design, which introduces a stability factor for the rock mass and compares this with hydraulic radius, was developed by Mathews et al (1981). This paper reviews the above systems by applying them to stability assessment of crown pillars in two Australian metal mines and provides a critical analysis of the various approaches. In particular each system will be analysed to determine its suitability for use in crown pillar design. The most suitable system(s) will form the basis for future development in crown pillar stability analysis.

Jan 1, 1994

By S Corbel, P J. T Donchak, W Gorczyk

The Hodgkinson Province numerical modelling project aims to develop an improved understanding of the physical conditions that lead to the localisation of goldbearing fluids within known systems and apply this understanding to the prediction of potential new sites of gold mineralisation. The project follows a series of stages from identifying the key parameters required to construct and test simulations through to reverse engineering of known deposits and ultimately applying the conditions identified in the preliminary stages to predictive simulations. Results of the modelling demonstrate strong geometric controls of the localisation of fluids during mineralisation. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Voermans F. M, Hoyle M. W H

The Archean geological sequence in the West Pilbara region (Fig 1), a deformed greenstone volcano-sedimentary succession regionally intruded by layered mafic/ultramafic lopoliths, batholithic granites, granite stocks and transected by swarms of dolerite dykes, has prompted several companies to search for a variety of base metals and and platinoids (Fig 2). In the first instance, detailed aeromagnetic surveying was completed, producing patterns of marked magnetic anomalism which proved substantially successful in the demarcation of areas warranting geological reconnaissance and detailed follow-up. Revelant to this paper were the obvious magnetic features overlying outcropping and buried mafic/ultramafic bodies which ultimately were proven to be host to Ni-Cu sulphides, pgm, Ti, V, Cr and, more recently, Ag and Au mineralisation. Routine stream sediment, soil sampling and ground geophysical techniques of the day appear, in most cases, to have been adequate in the detection of mineralisation, except in the case of Radio Hill massive sulphides where the Turam E.M. (1972) signal essentially failed to detect the blind conductor (Peters, de Angelis 1987).

Jan 1, 1988

By Moyes A. J

The Intec Copper Process uses a strong chloride electrolyte at atmospheric pressure and 80 - 85¦C to produce high purity, 99.99 per cent copper granules and elemental sulphur. A recent, exhaustive study by an independent, major Australian corporation has shown the capital cost of an Inter plant to be approximately half that of a copper smelter at the 200 000 tpa capacity level and approximately half the operating and capital cost at the 50 000 tpa level. The Inter process costs were also shown to be greatly superior to the best available leach/SX/electrowin technology. The process utilises a multi-stage counter current leach at 80 - 85¦C with the addition of air at atmospheric pressure to precipitate iron as a goethite type compound, followed by a two-stage purification process separating impurities in metallic- and other forms. Purified cuprous chloride/sodium chloride solution is fed to an electrolytic diaphragm cell where high purity copper granules are produced at current densities of 1000 - 1500 A/m2 withoutthe need for conventional electrode stripping. Power consumption is approximately half that of the cupric route. The product is suitable for the direct powder metallurgical conversion of the granules to products such as wire or strip. All the steps in the 'furnace free' conversion of copper mineral to product have been demonstrated The process can treat low grade and contaminated concentrates without penalty, thereby offering greater returns to the miner. Lead, zinc and silver may be recovered as metals, with the high oxidation potential of the electrolyte allowing extraction of gold at high efficiency. The gold is selectively precipitated on activated carbon with negligible copper and silver contamination.

Jan 1, 1992

By Thiel D. V

It is quite well known, although not so well documented, that radio noise is generated during rock fracture. Radio noise has also been observed during severe earthquakes. The source has been thought to be the fracturing of the rock, although the mechanism has never been unequivocably proven. A study of these radio emissions may provide insight into rock dynamics prior to seismic events, and after blasting. A programme of electric-field recordings has been undertaken at Brisbane quarries during multi-hole blasting. Preliminary analysis has shown that three types of signal may be distinguished. They are hole detonation, rock fall and post blast relaxation signals. It is thought that information about the blast, and the fracture of the rock, may be ascertained from these Signals.

Jan 1, 1990

The calibrated thermal IR data of part of Cambay Basin is used to determine surface temperatures and to detect the heat flow. Applying the conductive heat flow continuation technique, the three dimensional configuration of the hydrocarbon bearing reservoir was defined. The zone delineated by the present study coincides with the oil-bearing structures inferred by seismic survey. The results indicate the possibility of the technique as an effective tool in hydrocarbon exploration.

Jan 1, 1986

By Blake W

Based on preliminary computer model simulations and stability analyses, both longi- tudinal and transverse, large dimension, cut- and-fill rooms were designed for the parallel dipping ore layers at Kamoto mine. Full scale testing of the designed rooms showed that the rooms are stable and that the rock behavior is predictable. Ordinary waste rock was selected as the filling material because the fill was found to carry little load.

Jan 1, 1973

By Aylmore M. G

Samples have been taken from a two-stage industrial gold roaster treating a pyrite/pyrrhotite/arsenopyrite concentrate, in order to describe the mineralogy, composition and surface area of the calcines. Sulphides oxidised to produce a porous magnetite in the first stage and a porous hematite in the second; pyrite predominantly roasted via a pyrrhotite intermediate. Sulphur was eliminated in both the first and second stages whereas arsenic was eliminated in the first but retained in the second, partly as rims on hematite particles. The finer sized particles from the cyclones and electrostatic precipitator, while having the greatest surface area, were the most refractory with respect to gold solubilisation, probably as a result of incomplete decomposition (through short-circuiting) in the first stage, and through a combination of factors such as overheating and entrapment of sub-microscopic gold in the second stage.

Jan 1, 1992

By Thompson AG, Cadby GW

The New Austrian Tunnelling Method (NATM) is a proven concept for the safe and economic construction of underground facilities. This is especially true for tunnelling activity where changing ground conditions are often encountered. However, the principles central to the NATM have gained only limited use within Australia, presumably due to the measurement process inter- fering with tunnel driving and the cost associated with instrumentation and interpre- tation expertise. The design and operating principles of two basic instruments are explained together with laboratory simulated test results and suggest- ions for use in an integrated NATM style approach to underground excavation and construc- tion. The two instruments monitor load in rock reinforcement and deformation in rock or primary and secondary linings. The instruments may be fitted with a miniature display module which outputs the measured parameter in engineering units directly. The design of the sensing components allows the instruments to be installed in various configurations suitable for routine performance monitoring, quality control, support element testing or detailed investigations. The display module which reduces the need for instrumenta- tion expertise should suit contractors and allow performance data to be obtained which quickly may be used to modify support procedures to suit ground conditions. When complemented by convergence measurements the devices enable most facets of the NATM to be implemented.

Jan 1, 1987

The Canada Centre for Mineral and Energy Technology (CANMET) /Calgary Coal Research Laboratory and the National Research Council in Ottawa established a joint working research group with industry to develop and test various computer models for application in surface coal mining operations in western Canada.The first part of the paper deals with the problems the group experienced during the past two years especially having model specification and requirements defined and understand site management practices.The second part of the paper deals with site specific development of general mine model for TransAlta Utilities' Highvale Mine in Alberta. Described here are the development of an interactive truck/shovel model for their three pit operation, selection and application of dragline model for tandem operation with the extended bench method, criteria for operational model of the five seams operation with selec-tive mining approach.

Jan 1, 1985

By Smith IEM

Some samples from arc-type volcanic suites collected in northern New Zealand and southeastern Papua New Guinea show rare earth element (REE) and Y abundances which are enriched relative to the those typical of their respective associations. This enrichment appears to be the result of an alteration process which selectively mobilises the REE and re-precipitates them as REE-bearing minerals in veins and interstitial patches. The alteration is on a micron scale and is not detected in routine petrographic examination. The spectre of REE mobility in young apparently fresh rocks is important to igneous geochemists who use REE abundances to constrain petrogenetic models and may also be important because it indicates the operation of a natural REE enrichment process which could operate in the formation of economic REE deposits.

Jan 1, 1990

By McMahon DW

The major components of a mineral reserve estimate for project development purposes are described with respect to sampling, geology, estimation methods, mining factors, metallurgical factors, environmental factors, financial and other factors. Each of these components impact to varying degrees on the recoverable metal or product of a new mining project. The evaluation of a project is a complex process involving the best the profession can provide in terms of geological understanding, engineering ingenuity, metallurgical skills and financial evaluation.

Jan 1, 1983

By McKendry J. B

Gretley Colliery is situated at Wallsend, a suburb of Newcastle in New South Wales and is owned and operated by the Newcastle Wallsend Coal Ccnpany, a wholly owned subsidiary of Peko Wallsend Limited. The mine has been an efficient bord and pillar producer by industry standards. However, its continued economic viability was threatened because the bulk of remaining reserves lie in more difficult mining conditions and are of poorer quality. Alternatives were examined to improve productivity and allow Gretley to become more competitive in the current difficult market Environment.

Jan 1, 1988

Valuers will often intuitively express the probability that property value will exceed a certain amount . . . 'I think the chances that the value will exceed $50 million are excellent. The chances that they will exceed $80 million are poor'. This paper shows how it is possible to combine the uncertainties of the value of several key items to provide an estimate of the probability of a certain overall value being achieved. The valuation of a large copper/gold deposit was naturally influenced by uncertainties in the base assumptions of costs and metal prices. Potential acquisition of the property through share purchase raised the issue of what was a reasonable intrinsic value for the shares. Market considerations could be used to appropriately adjust the intrinsic value. After a range of possible metal prices and operating costs were determined, estimates were made of their probable distributions. By combining these probabilities in a random selection, a range of property values was calculated. Each value had its respective probability of occurrence. This allowed a most likely value of shares to be calculated. This paper demonstrates how the valuer's intuition is complemented by numerical analysis.

Jan 1, 1994

By D Moy, T Carter

This paper outlines the feasibility assessment conducted to explore the possibility of constructing two submarine water supply pipelines beneath the Ma Wan Channel in Hong Kong using either horizontal directional drilling or tunnelling. The Ma Wan Channel is a major shipping channel in the Northwest New Territories, which separates Ma Wan Island from the mainland. The challenges faced by the projectÆs designers included space limitations on either side of the channel, marine department restrictions on construction activity within the channel and selection of a suitable crossing alignment and profile given the channelÆs depth, irregular sea floor topography and complex geology. The existing geological information indicated the proposed alignment would cross granitic and volcanic formations, which would likely be faulted. The primary concerns with horizontal directional drilling were:the length, diameter and depth of the crossing were at the limit of precedent experience in rock; the lack of available space at both the entry and exit sites; and whether the technique would be flexible enough to cope with the anticipated range of ground conditions. The primary concerns for tunnelling were: the possibility of encountering large inflows of high pressure groundwater; andthe possibility of encountering disturbed ground within the fault zones which could flow if not properly treated. As a means to evaluate and mitigate these technical risks for both construction options, a directionally drilled pilot hole was used to investigate the ground conditions along the proposed pipeline alignment. The pilot hole results indicated that either directional drilling or a closed face TBM drive were technically feasible crossing options at a crossing depth of 80 m. The results also indicated that either an open face TBM or a drill blast drive would need to be constructed at much greater depth because of the presence of highly permeable, disturbed ground in mid-channel at this crossing elevation.

Jan 1, 1999

In the Illawarra District of New South Wales, Mines were traditionally developed from the seabord. The advantages were close access to the working faces and a minimal depth of cover. Travelling times to the working faces have become prohibitive in many cases due to progressive westward development of the mines. As a result, additional vent- ilation shafts were sunk to service existing mines and new mines were established west of the Illawarra escarpment. Mining operations west of the escarpment are now being conducted at an increasing depth of cover and can be effected by gas related problems such as high seam gas emission rates and gas outbursts.

Jan 1, 1983

During the 1950's there was a flurry of activity on the design of main ventilation shafts for mines. More recently, a new ana- lysis was commissioned in relation to the multi-shaft, nuclear waste isolation facili- ties currently under design in the United States. This paper presents the major find- ings of that study and should prove of value as a reference in the design of proposed new shafts. An overview of mine shaft resistance introduces the effects of the shaft walls, fittings, conveyances and shaft stations. Each of these is analyzed in turn. A com- pletely new technique is described, which facilitates the estimation of wall resis- tance. The effect of size of a conveyance is quantified and shown to be dominant when the cage occupies more than 30 per cent of the shaft cross-section. The dynamic effects of a moving conveyance are also analyzed.

Jan 1, 1988