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By D Obeng, D Alexander

Over the past five years, commodity prices have been high and the focus of many plants has been æthe more metal the better, at whatever costÆ. In the recent economic crisis, the focus has shifted more to reducing the cost of production and operating at higher efficiency. Since 2002, JKTech has partnered with the Century mine in north-west Queensland to transfer technology and understanding through the good, bad and ugly economic environments, using methodology and techniques arising from research at the Julius Kruttschnitt Mineral Research Centre (JKMRC) and other research institutions around the world as part of the AMIRA International P9 Project. The JKTech studies were concentrated around the primary zinc circuit. During this period, Century expanded the primary zinc regrind capacity, installed additional scavenging capacity, installed and commissioned a Jameson cell for concentrate cleaning in the carbon preflotation circuit, and installed additional primary grinding capacity. Flotation circuit models were developed for each of the survey campaigns and enabled opportunities for further improvement to be identified, implemented and tested in the subsequent campaign.

Jan 1, 2009

By Wylie A. W, Jarrett R. G

Two versions of a radiometric-type caliper for measuring borehole diameter are described. One, based on the bow-spring principle, is suitable for percussion (exploration) drill holes. The other, which utilizes hemispherical wall contactors actuated by springs, is suitable for blast holes. Both utilize low-power radioactive sources and employ a scintillation detector to measure the "inverse-square law" response of the device to changes in borehole radius. The performance of the device is examined and examples of its use are illustrated.

Jan 1, 1976

By Wu Y. H, Lu J. P

Slope stability has now become a practical tool in the design and oper- ation of open pits. The stability of rock slope depends on many factors, including not only structural geology, the existence of weak layers, ground- water, blasting and weathering, but also the virgin stress field. This paper presents an application of a numerical method to investigate the effect of the virgin stress on slope stability. The finite element method is employed to simulate the excavation of open pits. Redistributed stress fields in the slope of open pit are computed for several different virgin stress fields. Based on the redistributed stress fields, the shear force which tends to produce sliding of a rock mass and the frictional resistance to sliding are evaluated. The possibility of potential failure is assessed by the limit equilibrium method. The combination of the finite element method with the equilibrium method provides a powerful analytical tool for slope stability. The significant effect of virgin stress on the stability of slopes is shown by studying a typical case.

Jan 1, 1989

By R Memary

The environmental and economic impacts of a significant dependence on fossil fuels are affecting the future of sectors such as of mining. These impacts are prompting the Australian Government to seek solutions for reducing its dependence on fossil fuels more generally, such developing clean energy and improving energy efficiency. However, limited research has been undertaken to assess the potential synergies between clean energy and mining in an uncertain global future. This paper analyses current energy use by mining in Australia and reviews the drivers and opportunities for energy efficiency and cleaner energy technologies to be coupled to mining under three future scenarios. Linkages between mining and clean energy are investigated for three global scenarios for mining and metals to 2030, developed by the World Economic Forum (WEF), namely Green Trade Alliance, Rebased Globalism and Resource Security. These scenarios are applied to assess how they could change the barriers, opportunities and trade-offs required for the development of a more sustainable energy sources by the minerals industry in Australia.

Nov 22, 2011

By Crosby N. R

The design of mine openings and the assessment of their reserve are processes ihicl, require the routine manipulation of considerable amounts of data. A number of computer programs have been assembled to operate in a mini computer in order to provide some mechanical assistance for these processes. The system responds to plain language commands. which allows mining engineers to compute the reserves for a number of possible mining outlines, on an interactive basis. Methods of numerical analysis were used in preference to statistical or qeostatistical techniques.

Jan 1, 1977

This paper first describes the essentials of the slurry shield method and its achievements, then problems encountered during driving tunnels and their countermeasures, and finally shows problems to be solved in the future. The author works at Tekken Construction Co., Ltd. as a director. All the data cited are based on material gained from the slurry shield tunneling works undertaken by the said company. The mark, viz*, indicates that Tekken Construction Co., Ltd. has obtained or is applying for a patent in the U.S., Europe and Japan. 1. CONSTRUCTION RECORDS BY SLURRY SHIELD METHOD AND ITS PROBLEMS (1) Shield machines in the future should have the following characteristics; a. to be able to drive less cohesive soil b. to make no change to the ground water table level c. to make it possible to let people work in normal air pressure d. to cause less settlement at the surface To meet the above conditions various kinds of mechanical shields have been are tried, viz. limited air pressure type, rotary cutter with slit regulator, screw-discharge type, blind shield, etc. As far as the author knows, however, they are not 100% successful. Tunnels need their own accuracy in accordance to the usage. Both ease of driving

Jan 1, 1976

The problem of instantaneous outbursts remains unsolved after over a century of events and the investigation of the mechanism of the phenomenon and means of treating it. Outbursts have occurred of up to 5,000 tonnes with perhaps up to 500,000 m3 of accompanying gas, either methane (CH4) or carbon dioxide (C02) or mixtures. The low density of CH4 and the high density of CO2 give particular problems. Australia with both gases has experienced outbursts for 85 years with fatalities as recent as 1978. The Bulli Seam of the Illawarra area of the Sydney Basin is affected and outbursts with both CH4 and CO2 occur. The Northern and Central Bowen Basin also experiences outbursts with both gases. Proneness of affected mines is related to the high rank of the'coal and the proneness of the seams-is localised according to depth, gassiness, structure and development geometry. Proneness may be reduced by appropriate choice of mining methods. In addition to outbursting mines other mines have symptomatic phenomena. Traditional preventive methods have been used and control by induce- ment has been practised. A method of local prediction for widespread use has not been achieved although locally successful prediction 1Superintendent Rock Mechanics and Strata Control, The Broken Hill Proprietary Company Limited, Steel Division Collieries, Wollongong, N_RW

Jan 1, 1980

The program, WASTRT 70, was set up specifically to handle the design of tunnel liners and underground structures where inter- action between rock and structure significantly affects the design. It may however be used for any mass/R.C. structure capable of being simulated by straight line elements between modes and with loading restricted to nodes. The analysis system adopts typical elastic/stiffness matrix methods. Two main mass/R.C. design segments are utilized (1) Design of section depth based on maximum required stresses and optimum steel/concrete ratios. (2) Design of reinforcement for a given section depth with concrete stresses given for mass and water code structures. Each design segment covers shear, minimum principal stress on ~ , heavy compression as per code (columns), heavy compression one-face steel (tunnel liners), tension and water code requirements for all moment/thrust/section depth ratios on rectangular sections.

Jan 1, 1976

Mining software packages are used extensively in industry for resource estimation as well as for mine design and operation. Research undertaken in the W H Bryan Mining Geology Research Unit at the University of Queensland has shown that modifi

Jan 1, 1994

Tectonic subsidence plots have been calculated for well, extrapolated-well and significant off-well (seismically-based) locations in the Vulcan Sub-basin and adjacent highs (western Timor Sea). The subsidence curves have been normalized to a common datum, the distinctive "near top Permian" marker, and corrected for sediment compaction, palaeobathymetry, eustatic sea-level change and loading effects.Four principal phases of post-Permian basin development are recognised and quantitatively described by integrating the results of the sub-sidence analysis into the regional (e.g. recent Ocean Drilling Program-derived) framework of the tectonic evolution of the North West Shelf. They are1. the Triassic-mid Jurassic Westralian Superbasin intracratonic phase,2. the late Jurassic-early Cretaceous North West Shelf rift phase,3. the mid Cretaceous-Palaeogene North West Shelf subsidence phase, and4. the Neogene-present Timor collision phase. Rapid Triassic tectonic subsidence occurred in an intracratonic setting, possibly subsequent to aborted late Palaeozoic rifting. Intracratonic sub-sidence mechanisms such as deep crustal metamorphism and/or intrustion and regional tectonic compression are invoked in addition to any post-rift thermal subsidence which may have occurred.

Jan 1, 1990

By King RP, Kientzler P

In recent years, ultrasonic comminution technology has been developed at the Utah Comminution Center. An ultrasonic grinding device was assembled and investigated. An ultrasonic transducer system has been significantly improved by using a special type of piezoelectric ceramic and preloading to 4.1 x le kPa to obtain maximum strength. The improved system provides constant and rapid vibratory promotion of fatigue fracture resulting in more effective breakage. The design principles for an ultrasonic mill are developed in this paper. Size reduction was successfully achieved in the ultrasonic nip-roll device for a variety of materials. Ultrasonic comminution has repeatedly demonstrated the capability of producing fine particles from a variety of materials. A comparison between ultrasonic grinding and dry ball milling of limestone showed that the ultrasonic device produced much narrower size distributions than the ball mill. This trend is especially obvious in the coarse size range where few particles remain, and in the fine size range where overgrinding is prevented. This behavior might have some interesting applications in areas other than mineral processing like powder metallurgy or material science where narrow and controlled product sizes are required for the successful elaboration of high-technology ceramics and glasses. Ultrasonic comminution has a significant advantage in the accurate control of the product size.

Jan 1, 1993

Total extraction is a misnomer and invariably some coal losses occur in the mining of pillars. "Fulls" pillar extraction is by the pocket and fender method, the splitting method or the open end method, with extraction in the pillar, and in rows of pillars in planned sequence, using combinations of coal and timber and roof-bolts for support. Where circumstances dictate, partial extraction is used, leaving behind portions of pillars in large blocks for support. The use of such extraction plans and supports as minimum guidelines has contributed greatly to safety in United States Coal Mines.

Jan 1, 1974

By Moxon N. T, Berndt J. R

BHP-Utah Coal Limited's Peak Downs Mine is located in Cen- tral Queensland, approximately 200 km south west of Mackay. The annual raw coal production of the mine is over 8 million tpa, requiring the removal of about 40 million cubic metres of prime overburden. This is achieved through the use of five large draglines. The large depths of overburden (up to 55 metres) encountered over half the strike length of the mine enables cast blasting to be carried out in conjunction with draglines employ- ing the chopping method of digging. The objective of cast blast- ing is to use explosive energy to move as much material directly into spoil as possible. The additional costs of drilling and blast- ing are offset by reducing dragline rehandle. Two factors which are of primary importance to the design of cast blasts are initiation control and material velocity. High speed motion picture photography is a powerful diagnostic tool to quantify these aspects of blasting (Winzer, Montenyohl and Ritter, 1979; Chiappetta et al., 1983; Anon., 1983). The objec- tives of such analysis are to: 1. Determine the burden velocity, 2. Determine the time to initial movement (that is, the inter- val between a face hole firing and the initial movement of the burden), 3. Check the accuracy of the initiation sequence. BHP Central Research Laboratories (CRL) and Peak Downs Mine monitored a cast blast in the mine's Winchester Pit on 18 August, 1988. The objectives of this exercise were to: 1. Quantify current cast blast performance, providing a base case for comparison with modified blast design. 2. Compare two orientations of angled holes within the blast. 3. Assess the effectiveness of cast blasting utilising an air-deck. 4. Check blast timing with respect to burden movement times.

Jan 1, 1989

By C Swamydas

VV Mineral (VVM) group of companies is the largest and the first private producer and exporter of beach sand mineral products in India. During 2010, the company produced and marketed around 750 000 tons of saleable products. Their operations are mainly in the state of Tamil Nadu and Andhra Pradesh, India. Almost all the wet pre-concentration plants use sea water as the concentration medium, since there is no fresh water source available near the deposits. The mines are located along the south-east coast of India in the states of Tamilnadu and Andhra Pradesh. The orebody varies in terms of mineral assemblage, slime content, grain size, and surface coating resulting in different behaviour of the minerals. Three different deposits containing ilmenite of different TiO2 content were studied. The study shows that there is no significant impact of using sea water for wet concentration prior to high tension separation of ilmenite. There is no significant variation in recovery and purity of ilmenite produced from these deposits when wet concentration of the deposits were carried out with sea water as the concentration medium and whether the concentrates were washed with fresh water or not before dry separation using High Tension Roll Separators (HTRS).

Oct 5, 2011

By M Dohm, L Pretorius

This paper provides a brief historical background to the approximately 12-year project that led to the revision of rope selection factors in the South African regulations, thus providing the ability to hoist economical payloads from single lift ultra-deep shafts. The efforts over the past 20 years have led to the revision of the legislation pertaining to rope selection factors, the redesign of rope constructions to meet the required duties associated with ultra-deep shafts, codes of practice for the design, operation and maintenance of winding plants, and a code of practice for the condition assessment of winder ropes. As a consequence the Moab Khotsong ultra-deep hoisting system could be developed and installed, with the assurance of predictable performance. Access to deep orebodies by means of single lift, ultra-deep shafts has a critical impact on the life cycle costs and efficiencies of ultra-deep mining complexes. A brief description of the main components of the hoisting system at Moab Khotsong is presented. An in-depth review of the development process applied to ensure a stable, safe and cost-effective rope construction for the ultra-deep Moab Khotsong shaft follows. The paper concludes with an overview of the experiences gained during the installation and commissioning phases of the winder, as well as operational and maintenance issues.

Jan 1, 2005

By Paine GG

The in-situ retorting of shallow oil shale deposits is an attractive alternative to the material handling problems of conventional open pit mining techniques, which involve removing overburden, fragmenting and transporting the shale to a fixed retort, and finally disposing of the hot spent shale.For in-situ retorting to be successful, the oil shale has to be fractured and the fragmented rock expanded into a void, to allow controlled propagation of a flame front through the in-situ retort. The principles of cratering with explosives have been used to develop a process for the in-situ fracturing of a thin oil shale deposit overlain by a formation of porous rock. The overlying porous rock formation is first compressed by explosive charges to create voids in the porous rock. The oil shale is then fragmented and pushed in to the voids with separate explosive charges. This paper discusses methods of creating voids in porous rocks with minimal surface disturbance, and then methods of obtaining the most uniform fragmentation of the shale. The whole process can be completed, in practice, in one blast. The results of an experimental blast are presented, and possible modifications are then discussed.

Jan 1, 1985

This paper is written as a supplement to that of Edwards, Baker and Knight on "The Geology of the Wonthaggi Coalfield" 1, the West Area pit being in an early developmental stage at the time of their paper. The thin seams to the west of Dudley Basin 2 had beenknown for many years but it was not until 1935 that it became necessary to work them. The West Area Pit came into production as Dudley Area Pit approached exhaustion in 1937. From available information it was estimated that early work would be in a 36in. bottom seam. The present top seam was not included in the reserves, but it was to be extracted where it proved thick enough for economical working.THE SEAMSEdwards, Baker and :Knight (1944) had insufficient information to correlate positively the West Area seams with those in the Dudley Basin. Their opinion was, however, that they were a westerly extension of the Bottom Seam. Since then the driving of the present north-east heading towards No. 4 Bench McBride Tunnel has established that the West Area seams are those worked as Bottom Seam in the Dudley Basin. West Area Top Seam is a seam that occurred above the Bottom Seam in the Dudley Basin. Only sporadic attempts have been made to work it in Central Area, because 30in. was considered an economic minimum height until recent times. This seam should not be confused with Top Seam, Dudley Basin, which lies some 300ft. above the bottom seam measures and except in isolated areas over deeper workings has been eroded away in West Area.

Jan 1, 1953

Mining software systems have provided a basis for integration of resource, survey, and design functions. They can similarly provide a basis for incorporating ground conditions into the process.Exploration and mine geologists have a prime role to play in this process, extending their responsibilities further across the geological spectrum, into exploration of ground conditions, analyses of results, and assessments of their implications for mining. Ground conditions are as much a part of the geology of a prospect or mine as its mineralisation, and can have critical imnlicationa for mining.

Jan 1, 1993

The theory of declining optimimum cut-off grades is more than 25 years old, but for a number of reasons it is still not widely used in industry. A lack of faith in the veracity of estimated grades is not in itself a reason to abandon any attempt to optimise cut-off grades. The use of declining cut-off grades has been thought to cause high-grading, but in fact this is only true if an artificially high discount rate is used in the calculations. Perfect application of an optimum cut-off grade should ensure that only ore generating more than a minimum net return is mined, and that as much as possible of the ore capable of generating that return is mined. Therefore differing mining costs in different parts of some underground mines necessitate local modifications to cut-off grade. Optimisation of cut-off grade is of necessity an iterative process. Integration of that process into a feasibility study need not be excessively time-consuming. A number of approximations can be made to speed the optimisation (any attempt to achieve a high level of accuracy is probably doomed to failure by a lack of precise cost and price projections). A procedure is outlined for optimising cut-off grade during planning of a typical underground mine.

Jan 1, 1991

The paper, one of two papers on the Queensland Railways Brunswick Street tunnels presented at the VIII Australian Tunnelling conference, describes documentation, tendering and construction aspects.Tender documents were written to reduce the risk taken by the contractor. Details of tenders received are analysed and the changing industrial situation at that time described.Construction aspects covered include mobilisation, major equipment, tunnelling equipment and manning. Program and progress are reported including industrial relations and advance rates for Mitsui-Miike S-200 and S-65 roadheaders. Cycle times and performance in terms of cutting rate and pick wear are provided for the roadheaders.

Jan 1, 1993