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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

Various software packages are discussed. These are components of an Integrated Planning and Scheduling System developed by MVM with the aim of providing up-to-date information for the Whaleback operation on: 1. Mine Topography. 2. Status of equipment in the mine. 3. Material moved from and within the mine. 4. Volume and density of same. 5. Quality of same.

Jan 1, 1986

By Quinlan M. J, Ratcliffe J. S

Chemical kinetics is a dependent process which usually correlates the rate at which a reaction proceeds with the mechanism descriptive of the manner by which reactive particles interact. Given the latter, the object gen- erally is to find the reaction rate dependency in terms of an intensive property of the system - number of reactive particles present, and of the energetics of the system - usually temperature. Chemical kinetics depend on a dem- onstration that reaction considerations alone control the phenomenological process under study. For these rea- sons, chemical kinetics are usually involved in homogeneous gaseous systems. Even in liquid homogeneous sys- tems earliness or lateness of reactant mixing rather than chemical kinetics may be controlling. Considerations of transport phenomena are involved in heterogeneous systems and often control the observable rate:an additional problem in such systems is to apportion the rate due to mass transfer - usually a linear process - and that due to reaction which may be linear or non-linear. Experimentally, conditions are often chosen so that only one consideration controls but this becomes more difficult where solid phases are involved. Kinetic modelling involves considerations of chemical kinetics, transport phenomena, and factors attributable to the physical environment in which the process takes place. The latter two considerations may be quite different as between experiment and plant. The kinetic model may be a mathematical representation of a conceptual mech- anistic model of the reaction. Alternatively, it may be an empirical relationship resulting from, for example, some curve fitting procedure applied to experimental data. The latter approach may be necessary where the system is particularly complicated.

Jan 1, 1975

Three key areas of C.I.P. plant design, viz. leach- ing time, adsorption and the gold loading on the carbon, are discussed and illustrated with examples. The need for accurate pilot plant data for use in assessing and optimising design is emphasized. This approach should minimize capital and maximise return on capital. It is demonstrated that, as regards adsorption, economics favours short retention time, high gold loadings and mechanically agitated, draft tube reactors. INTRODUCTION Little attempt appears to have been made in Australia to design the present generation of C.I.P. plants to achieve an economic optimum. Most would, seem to have been based on pre- liminary leaching data, gold extraction and value and rule of thumb which, in general, has led to over design and over capitalisation. An essential step to effective economic design is a comprehensive pilot plant study to establish definitive operating parameters, yields and reagent costs. In most cases the cost of developing this data will be more than offset against capital savings in plant; the operating profit should be increased substantially, and profit is maximised for known

Jan 1, 1982

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 OÆBrien D. R

Up until June 1988, Mount Thorley Coal Handling and Preparation Plant disposed of tailings by two methods. Approximately half of the plant tailings was mechanically dewatered by solid bowl centrifuges mixed with plant reject and was subsequently disposed in mine overburden spoils; the remainder was pumped to tailings ponds. Both future mine planning and environmental constraints could not allow for the long term construction of more tailings ponds so, following evaluation of available dewatering technology, belt press filters were selected for the treatment of tailings in excess of the capacity of the existing solid bowl centrifuges. Commission of the four 2.5 metre wide belt press filters soon showed that marked differences in performance were experienced when treating different coal seams. Further analysis showed that the coal tailings from different seams were quite different in terms of clay mineralogy, and these differences could be correlated with varying degrees of filter performance. Poor filter performance was experienced with coal tailings rich in sodium montmorillinite clays. A number of variables were investigated including in-line mechanical mixing of flocculant and feed slurry, cation exchange reagents such as gypsum, and upstream addition of cationic flocculant. In order to achieve satisfactory performance on the worst tailings, a combination of all of the above was required. In this paper, the reasons for selection of belt press filters and the program of investigations and testwork required to arrive at satisfactory belt press filter performance for the treatment of troublesome bentonitic rich tailings are discussed.

Jan 1, 1989

By Will D

This presentation is to outline the current practice of mechanised stoping a one-metre wide, gold bearing ore body to optimise fragmentation, minimise dilution and reduce stoping costs.Coolgardie underground operations have historically been mined using traditional shrink stope methods, but in this recent economic environment (with falling gold prices and high costs of traditional methods) it was necessary to look for alternative methods in order to reduce costs and increase productivity.Although still in a learning and refinement phase, CGNL is satisfied that it is feasible, practical and more economic to use mechanised long up-hole stope and long-hole rising methods to significantly reduce the mining cost, reduce dilution, increase safety and increase productivity three-fold compared to traditional airleg methods used throughout the Fasten Goldfields.

Jan 1, 1993

By Aziz NI, Guo H

Most of the existing models of the mechanisms of drilling and cutting processes are oversimplified in both stress state and failure criterion. On the other hand numerical modelling techniques are a more versatile method with great potential for development. In reviewing drillability and predicting performance of excavation machines the empirical tests, which simulate the physical breakage action in excavating processes are seen to be the best in terms of penetration rate predictability. Future methods of determination of drillability should concern the breakage characteristics and rock abrasivity involved in the two basic types of attack, i.e., percussive and rotary drilling.

Jan 1, 1988

Recognition is the most important aspect in the use of breccias as an exploration tool. Ore-hosting breccias occur in a wide variety of environ-ments, shapes, compositions and characteristics, but generally present favorable loci for the deposition of ore mineralization in epithermal, porphyry copper-gold-molybdenum, massive sulfide, carbonate-hosted, sedimentary lead-zinc deposits and others.

Jan 1, 1990

By Bowling K. McG, Hamilton J. D G

The influence of three important para- meters which affect the induration of iron-ore pellets, viz temperature, time, and lime content, have been assessed in terms of internal pellet structure and commonly-used pellet quality criteria. The pellets studied were produced from a typical hematite ore from the Pilbara area of Western Australia, using a 25 cm dia. pot-grate test rig. Isothermal laboratory induration tests were conducted in accordance with a statistically-planned programme. The internal structures were studied by optical microscopic examination of polished sections of the test pellets. The effects of SFCA (silico- ferrite of calcium and aluminium) and slag formation, matrix consolidation and grain modi- fications were studied, and have been related to pellet properties and to the time/temperature histories produced by the firing conditions chosen. The implications of the data for commercial pellet plant operations are discussed.

Jan 1, 1974

In the first half of 1987 two four metre diameter raise bore holes were drilled at the Olympic Dam Project for ventilation purposes. The first hole, 476 m x 4.0 m diameter was completed in 96 days, 35 days longer than scheduled. The second hole, 407 m x 4.0 m diameter was completed in 39 days, 2 days ahead of schedule. Both holes were drilled with a Robbins 121R rig using a Wirth head that consisted of 23 face cutters and 5 side cutters, supplied by a contractor. After the sites were located a grouting program was carried out to help seal off an aquifer between 160 and 180 m below the surface. Cavities discovered in the Andamooka Limestone were filled with concrete. Because of the overlying dune sands and clay both sites were pre-sunk to the competent Andamooka Limestone.

Jan 1, 1988

By Wilkinson LR

The object of this paper is to present a brief overview of applications of radioisotopes in mineral processing. The emphasis is towards on-line applications, and is to present the broad picture rather than become involved in the details of particular applications. For a more detailed and comprehensive coverage, the reader is referred to the International Atomic Energy Agency International Symposium on Nuclear Techniques in Exploration, Extraction and Pro- cessing of Mineral Resources, held in Vienna 7-11 March, 1977. Because of space limitations here, we have inmost cases restricted coverage to those applications of radioisotopes within the direct experience of Amdel and Australian research bodies. Radioisotopes spontaneously emit energy in tiie Form of a and S particles, and electromag- netic radiation. The electromagnetic radiation is generally referred to as y-radiation when it originates from the nucleus, and X-radiation when originating from the electrons orbiting the nucleus. X-ray and y-ray energies overlap, with X-rays extending from a few electron volts (%') up to about 100 keV. Gamma rays in the useful energy range extend from a few keV up to .feV.

Jan 1, 1978

By Soma T

Pyrite and Cu-concentrate were roasted in vertically suspended state in an externally heated tube. Tubes of three different lengths of reaction zone were used for three different reaction times. Roasted ores were submitted to chemical analysis and the extent of roasting reactions was determined. In case of pyrite, extent of roasting reactions was not affected much by reactor length and heating temperature (above 500¦C), but was considerably by ore/air ratio. Micro- scopic and XMA examinations led to the conclus- ion that pyrite particles decomposed to pyrrho- tite and then pyrrhotite was oxidized to give Fe-S-0 melt, magnetite and hematite. The extent of reaction was not uniform in all particles but had a wide distribution from unreacted pyrite to completely oxidized particles. Combustion of Cu-concentrate from Kuroko complex sulfide ore ) was unstable under a uniform wall temperature of 450¦C, but proceed- ed rapidly at temperatures above 500¦C. Sticking of roasted ores to the wall of the reaction tube induced choking of the tube, caused by melting of roasted ores, at tempera- tures above 950¦C. Enrichment of oxygen exterted less influence on reaction rate than heating temperature of the tube. Particle size of ore had a big effect on reaction rate.

Jan 1, 1980

By Clift N

Lead concentrate from the Isa and Hilton lead-zinc concentrators of Mount lsa Mines Limited is smelted at Mount Isa to produce a lead-silver bullion. This bullion is cast into four tonne blocks and shipped to Britannia Refined Metals Co Ltd, NorthDeet, England and to plants in Asia for refining and marketing. The traditional treatment stages at Mount lsa are sintering, smelting, and drossing and casting, with some of the sinter plant feed being pre-treated through an Isasmelt plant.A commercial scale lsasmelt based lead smelter was commissioned in early 1991.

Jan 1, 1993

The Blackwater Coal Mine is a modern open cut operation using large draglines for over- :)urden removal and shovels, loaders and trucks to mine and haul coal to the crushing and coal ?reparation plant. Operations at the mine are described in sequence following through overburden removal to the railing of product coal from the mine site. The close operating connection between the mine and washery, which results from the blending of raw coal into clean product via the qashplant bypass system, is stressed. Some features of special interest at Blackwater Mine, such as land reclamation and slope stability,are outlined.

Jan 1, 1974

By Motyka J, Adamczyk AF, Witczak S

A case study of migration of a paper factory fluid wastes, on the distance of 5 km from an underground disposal site to an ore mine is presented. The ore mine in question, situated in SW Poland is pumping 3.5 m3/s (ca 300 000 m3/day) of groundwater, producing a cone of depression about 150 m deep and several kilometers wide. The migration of wastes (pollutant) occurs within the carbonate karstic aquifer of Triassic age. The aquifer is about 100m thick and is characterized by the coefficient of hydraulic conductivity equal to 8 m/day on the average. The results of systematic measurements carried out for 13 years enabled to estimate the mean breakthrough curve of the pollutant. On this basis and taking into account the coefficient of hydraulic conductivity as well as the mean hydraulic gradient between the disposal site and the ore mine, the migration parameters of the polluting material, i.e. the real flow velocity, the effective porosity and the longitudinal disper- sivity have been calculated. As the measurements considered a long migration distance of the pollutant, the obtained hydrodynamic dispersion constant (dispersivity), in the authors opinion, is reliable enough to be applied for regional groundwater calculations, regardless of the "scale effect".

Jan 1, 1988

By Raymond G. F

Geostatistics - a tool used by geologists and mine planning engineers to estimate grades and rapidly evaluate alternative mining strategies has reached an advanced stage of development for the silver-lead-zinc orebodies at Isa and Hilton Mines. Geostatistics has been used for over a decade in the massive copper orebodies but the stratiform lead-zinc orebodies are much more complex and provided a completely different set of challenges. Recent increases in computer processing speed and power provided by the Integrated Mine Planning System (IMPS) has aided the development of the geostatistics package. Also the formation of a project team and the subsequent in-house development which has drawn together the expertise of geologists, engineers and system analysts has contributed significantly to the success of the project.The most important feature of any approach to modelling the lead-zinc orebodies is that the kriging search must consider estimate and sample points according to their positions relative to bedding surfaces. By transforming co-ordinates as perpendicular offsets from a plane representing the local strike and dip, it is possible to elongate the ellipsoidal influence to parallel bedding. By interactively modelling surfaces using CAD facilities and then specifying these surfaces as 'hard' or 'soft' boundaries, the geologist has complete control over the kriging process.

Jan 1, 1993

Orebodies in the Mt. Charlotte-Hannan's North area N. and E. of the town of Kalgoorlie provide a marked contrast to the pyritetelluride lodes of the Golden Mile, although both groups of orebodies appear to be fundamentally related.These highly siliceous telluride-free orebodies N. of the Golden Mile are closely related to strong oblique faulting. The Golden Mile lodes, while possessing an apparent overall relationship to the oblique faults also have a close relationship to E. dipping strike faults.INTRODUCTIONThe Mt. Charlotte-Hannan's North area lies N. and E. of the town of Kalgoorlie and is separated from the Golden Mile by the Golden Pike fault. The orebodies discussed lie in an area approximately 3 miles long by 1 mile wide (Fig. 1).The area includes the site of the original discovery of gold in the Kalgoorlie district in 1893. There have been numerous mining operations over the years, the bulk of the production coming from two orebodies, Mt. Charlotte and Hannan's North. These have provided approximately 900,000 tons of the 1,100,000 tons of ore mined in the area.Production to date from the principal orebodies in the area has been as follows.1. Hannan's North orebody, 582,000 tons of ore for 275,000 oz of gold2. Mt. Charlotte orebody, approximately 230,000 tons for 75,000 oz3. Pharlap and Golden Goose orebodies, each orebody approximately 8,000 tons for 2,700 oz4. Maritana Hill orebodies, approximately 170,000 tons for 70,000 oz...

Jan 1, 1965

Alluvial gold exploration is aimed at recognizing areas of anomalous gold content as evidenced by the nature of the drainage system, its age, geomorphic history and other features of the geological environment including the provenances. Subsequent studies to quantify the findings are governed by the need for accurate data based upon precise measurements. Computerization allows the use of more complicated mathematical procedures than are feasible manually, thus promoting the development of more advanced technological aids. Data banks provide the means of storing vast quantities of information for instant recall.Sample representivity is a major problem and a clear understanding of both sampling and analytical requirements is essential for dealing with problems arising from variations in sample size and particle size distribution. Field samples must always be large enough to ensure adequate representivity or the sampling has failed in its purpose.

Jan 1, 1984

The relative contents of Au in a series of groundwaters from water bores and exploration drillholes, located near Au mineralisation at Stawell, Ararat, Clunes and Ballarat in central Victoria, were found to be clear indicators of relative proximity to mineralisation in each region. In the same series, waters with anomalous concentrations of As distinguished Au mineralisation in bedrock from secondary palaeochannel or deep lead Au. In some groundwaters, acid pH values, high sulphate relative to other anions and detectable concentrations of reduced Fe reflected sulphide minerals associated with bedrock Au deposits. Close to some ore zones, locally anomalous groundwater concentrations of Mn reflected the Fe carbonates that accompany Au in these zones. In addition, elevated concentrations of other elements provided geochemical signatures for the aquifer lithologies associated with Au mineralisation. Of the lithological indicators Co and Ni, U and F, Rb and Cs, Mo and Li respectively reflected the mafic, felsic, potassic rich and quartz zones, principally in the Stawell mine area and to a lesser extent those at Clunes and Ballarat. Mineral stability diagrams, based on groundwater activities of K', Mgt and H`, demonstrated that a series of ore-zone groundwaters follow a trend that conforms with a biotite to sericite to kaolinite alteration sequence in aquifer mineralogy. This is a good illustration of how present day groundwaters under surface conditions can reflect the underlying mineral sequences that accompany these Au deposits. These observations around mine areas suggested that groundwater chemistry could provide a rapid and cost effective method of assessing prospectivity for An of extensive areas in central Victoria. To test this, regional sampling and analysis of 355 bore waters was carried out in a region where potential An bearing rocks are covered by Mesozoic and Cainozoic sediments and volcanics. Contoured elemental abundances and distribution from this program indicated five zones in which groundwaters had elevated Au and despite the cover, appeared to reflect variations in the underlying Palaeozoic rocks. Three of the Au zones could be in terrain affected by extensions or intersections of faults, a feature in common with the established Au deposits in central Victoria. Reflections of concealed Palaeozoic rocks included a possible zone of concealed Cambrian greenstones that coincides with three of the Au zones. It was concluded that each of the An zones represents a groundwater Au focus that warrants follow-up exploration.

Jan 1, 1997