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By Thomas G. A

THE irregularity of the Mount Morgan (Queensland) ore body presents problems other than those only of mining. For irregularity of outline is coupled with irregularity of grade, and the ore varies so rapidly from profitable to non-profitable, and fromhighly siliceous to highly pyritic, that the task of estimating quantities and values of ore reserves is manifestly rendered a difficult one, while the actual disposal of the broken ore demands constant supervision.Four classes of ore are handled. The oxidized ore, cheaply mined and cheaply treated, is obtained by quarrying from the top of the mountain. Below the 315-ft. mine level (measured from the original summit) sulphide ore comes in, and this is divided into siliceous sulphide ore (too siliceous for economic smelting), sulphide ore suitable for smelting, and ore too poor either to be smelted or to be treated by wet process with the siliceous ore. It is with these three latter descriptions of ore that this paper principally deals.Although the output from many stopes in the mine may usually be presumed beforehand to be either smelting or wet-treatment ore, yet it is never safe to take this for granted, and constant assaying is necessary. At the same time the ore merges from one class into...

Jan 1, 1911

Since early 1968 the Bureau of Mineral Resources (B.M.R.) has carried out VLF-EM test surveys in various parts of Australia and Papua. The aim of the work, primarily, was to examine the effect- iveness of the method as an exploration tool under a variety of Australian conditions. Selection of test areas was determined by the availability of geological, geophysical and drilling information and by the desirability to include a variety of physical variables such as depth of weathering and topography. The aim of the present account is to review the results of this work and to make an assessment of the method available to the mining industry. The author wishes to acknowledge considerable assistance both by way of data and discussion provided by Messrs. Paul Gillespie (B.M.R.). and John Haigh (formerly B.M.R., now Senior Geophysicist, McPhar Geophysics Australia.) The article is presented with permission from the Director, B.M.R.

Jan 1, 1971

By Ward C. W

Conventional polygonal and block modelling techniques inadequately represent the grade-thickness distribution of some narrow shear and stratabound gold deposits. The polygonal influence of high-grade drill intercepts can result in overestimates of resource tonnages at high-grade cut-offs. Although block modelling methods provide grade smoothing and a better representation of structural continuity, the technique can lack precise definition of ore width. An alternative method known as Spatial Object Modelling (SOM) has been developed on MineMap software to overcome some of these modelling issues. This method does not rely on a uniform cell size and allows grade smoothing between resource intercepts in three-dimensional space. The SOM technique creates grade-thickness bars on regular, user-defined spacings which allow easy visual comparison of raw intercept data to the interpolated model. Model cell values are readily transformed into isopachs, isopleths and resource perimeters for reporting and mine planning purposes.

Jan 1, 1997

By Falconer A. J

Two magnetic parameters are proposed as a basis for the assessment of ironsands beneficiation. The parameters are deter- mined for raw sand prior to dredging and for magnetic separator head feed over a production period of five months. The relationships between these parameters and the performance of the magnetic separators are examined to establish the value of magnetic assessment compared with the traditional soluble iron assay method. The results illustrate that the first parameter, true magnetic fraction (TMF), has a value superior to that of soluble iron when relating raw sand grade calculated by tri- angulation to magnet performance. In terms of the relationship between magnet head feed grade and magnet performance, TMF and soluble iron perform equally as assessment parameters. For the ironsands mined during the five month period, the second magnetic assessment parameter, composite fraction (CR), is shown to merely reflect TMF and offers no additional information for assess- Ment. Conclusions are that true magnetic fraction has many advantages over soluble iron in terms of time and cost of determination and that it is a meaningful and reliable parameter upon which to base all calculations relating to the mining and beneficiation of ironsands.

Jan 1, 1980

By Kilgour I

The installation of a final cleaning column at Ok Tedi Mining Limited was carried out to increase final concentrate grade in order to reduce concentrate handling, shipping and treatment charges and to reduce penalty payments. To fast-track the project a decision was made to install a full-size column on one of the two parallel circuits, designed on information readily available and utilising the experience of mill staff and an engineering consultant, rather than delay installation while a pilot scale program was conducted. A 3.66 m diameter by 12.8 m high column was installed to produce 40 t/h of final concentrate from a combination of rougher concentrate and recleaner concentrate. The column design and sparger system were by Cominco Engineering Services Limited.

Jan 1, 1991

Woodlawn Mines began underground operations in 1986. At the time of going underground it was envisaged that there would be no 'contract' payment to the underground employees. This was a relatively unique step to make, especially as most major underground mines in Australia relied heavily on the contract system to motivate their workforce. (Obviously with varying degrees of success.) Woodlawn faced the task of motivating their employees through a multi-skilled system with a great emphasis on leadership and a genuine care for their employees. The 'proof of the pudding' is that Woodlawn has not lost any time over industrial issues since beginning underground operations in 1986. To achieve success in any operation the organisation must not only be advanced in its management principles but also be prepared to be innovative in the way it deals with physical problems, ie ground control, equipment selection and maintenance. Difficult ground conditions at Woodlawn have necessitated the deployment of two Cabolt Jumbos and the construction of cost-effective shotcrete systems. The shotcrete system now being built has been tested in a prototype form and is proving to be a safe and simple way to manage weak, low stress friable ground. Although the ground at Woodlawn has low stress component by virtue of the fact the ore can have a density of 4.5dm3, cable dowelling has become a necessity. The two cable dowel jumbos install high quality reinforced cables. The pressure of 'production' means that these machines must be consistently available for use and the training of maintenance personnel and operators ensures that a maximum of cable dowels can be installed over any given time span. In any modem mine ventilation is a primary concern and the major area of concern comes from the vehicles themselves. In our recent replacement for the standard 'Toro' loader, three engine options were considered. A relative newcomer to underground mining was accepted. The Detroit 60 series (DDEC) engine came with a great reputation and has lived up to this. The engine has an electronic management system that reduces particulates to a hardly visible minimum, provides great amounts of engine power and reduces fuel consumption by approximately 45 per cent. The operational benefits of such an engine are worth sharing through this conference.

Jan 1, 1995

The Ok Tedi Project has been planned as a selective mining operation since the Feasibility Study. The nature of the orebody, and the need to 'stage' the infrastructure buildup meant that initially the mill would process gol ore using a leach-CIP process, followed by parallel leaching of gold ore and flotation of copper ore, and finally all flotation of copper ore. Cutoff grades were applied to gold and copper ore of 1.0-1.3 g/t Au and 0.4-0.3% Tot. Cu. Since startup, unpredicted occurrences of sulphide copper and, to a Lesser extent, carbonaceous material, has necessitated significant additional short term drilling (other than at grade boundaries), and shift grade control in the pit to control contaminant levels. Remodelling of the orebody based on the most up to date variography and geological interpretation has had a significant impact on the reserves, and thus the whole project development strategy; necessitating the earlier processing of copper ores, and preflotation of the gold ore.This paper discusses some of these points in detail, and in particular highlights how unforseen geological occurrences coupled with processing restrictions can have significant impacts on ore reserves and the mine development schedule.

Jan 1, 1986

The Gympie Province is a unique tectono-stratigraphic unit which does not fit into the overall palaeogeographic pattern of the New England Fold Belt (NEFB), and part of it has been proposed as an exotic terrane more closely linked to New Zealand. From E to W the Gympie Province comprises 6 distinct units which can be evaluated as suspect or exotic terranes.

Jan 1, 1990

By Singh RN

Monolithic packing systems have gained in popularity as a gate side packing method. However, there has been no detailed investigation to assess their underground strength behaviour. This work includes the laboratory and in situ investigation for strength behaviour determined on various monolithic packing materials namely Tekpak-XX, Hydropak-20, Hydropak-30, Astrapak-3R, Flashpak, Thyssen pack and Aquablends. A simple technique for assessing the pack strength was developed at the laboratory by using a penetrometer, of which penetration resistance can be directly correlated with the uniaxial strength of the pack. The in situ strength investigations were made on core samples obtained from three pipes inserted inside the pack, while the penetration test were made on the pack surface. The in situ results indicated that the packing material develops an inconsistent strength on various part of the pack which was mainly related to an inadequate mixing of grouts inside the pack.

Jan 1, 1992

The late 1960's and 1970's saw the initial development of the coal resources of the Bowen Basin of Queensland. The projects developed relied on large scale, open-cut operations using draglines for overburden removal and, in the majority of cases, project viability could be established based solely on those open-cut operations. Many of the mines developed in the 1980's have the same characteristics.Unlike these mines, the German Creek Mine has limited open-cut reserves at low overburden to coal ratios, and planning of the complex involved a large open-cut mine capable of developing early cash flow, with phased introduction of underground mining to replace open-cut capacity as the strip ratio increased.

Jan 1, 1985

By Hochwimmer B, Baxter JL

Heavy minerals are mined from two fossil strandlines on the southern Swan Coastal Plain. The Capel shoreline, 7 km inland, and the Yoganup shoreline, 15 km inland are arcuate, northwest-facing, and remote from the modern coast. Based on foraminiferal and molluscan assemblages, the shorelines are probably of Pliocene age. The Yoganup shoreline is adjacent to the Whicher Scarp, which is cut into the Leederville Formation (Lower Cretaceous) at the southern boundary of the Swan Coastal Plain. Stratigraphic relations and detailed sedimentology have been studied from temporary exposures in the Yoganup Extended and Yoganup North mines, within a strandline complex at 27 m and 18-33 m above sea level respectively. Heavy minerals were deposited in thin, shallowing-upward sequences along a wave-dominated clastic shoreline cut into pre-Cainozoic sediments. Lithofacies units deposited in eolian, foreshore, shoreface and lagoonal environments are the most significant sites of heavy mineral accumulation. The data collected provide a basis for further exploration.

Jan 1, 1986

By Mckenzie CK, Leach KR, Bateman KW

Modelling of industrial coal flotation based on data collected in several Central Queensland flotation plants and supplemented by laboratory data is discussed. The model is kinetic in form and provides the basis of an automatic control system. The important features of the model are, 1. a distribution of flotation rates for each species of particles corresponding to the range of particle sizes, 2. a physical restriction on the removal rate of solids in cells where froth 'overloading' occurs. In this condition the removal rate of solids is proportional to the removal rate of water, 3. enhanced particle floatability due to increasing collector addition where froth overloading does not occur, 4. a second mechanism of recovery of all particles by mechanical associ- ation with water. This mechanism is particularly important in the recovery of fine high-ash species.

Jan 1, 1978

By R Rodriguez, S Gumo

The Lihir Gold Mine, in Papua New Guinea, is a large open pit operation within an active geothermal system inside a collapsed volcanic crater. This unique setting has a big impact on the mine operation because of the occurrence of geothermal hazards. The system for managing geothermal hazards that has been developed by Lihir Gold Mine is a pioneering effort that can be applied to future mine discoveries in a similar environment. The controls are integral to the mining operations and allow mining to proceed whereas without them mining could not be considered. Truck and shovel productivities in conventional open pit operations are constrained by diggability, equipment availabilities and utilisation. At Lihir, additional constraints are in the form of 100 m exclusion zones around working shovels and 50 m exclusion zones around working drills. Given that the mine has seven large digging units and six drills, this amounts to a lot of area that excludes the presence of people on the ground. So how are the necessary work like grade control, survey, blasthole loading, and in-pit maintenance performed safely to achieve production targets? The answer is in the highly specialised procedures that have been developed that utilise geological, geothermal and geotechnical knowledge to predict problem areas and also deal with the organisation of movement in the pit for people and mining equipment. This paper will detail how scheduled material movement can be maintained despite the challenging conditions faced at Lihir Gold Mine.

Jan 1, 2007

By Hocking G

For some underground structures, the use of the plane strain assumption in stress analyses may not be justified. The finite element method and photoelasticity have been used to obtain complete 3-D solutions, but, for various reasons, neither method has found universal use. The boundary integral equation method (B.I.E.M.) can be more efficient and economical than the finite element method for 3-D problems involving large volume to surface area ratios. A B.I.E.M. program developed for calculating stresses and deformations in infinite elastic media has been used to determine the 3-D distributions of stress around T- and Y- junctions of circular tunnels in stress fields in which the ratios of horizontal to vertical stress are 0, 0.33, 1.0 and 2.0. For the T- junction considered,stress concentrations at the intersection are approximately twice the plane strain values. Except where horizontal field stresses are high, the stresses in both tunnels approximate the plane strain values at about two tunnel diameters from the point of intersection of the tunnel centre lines. The stresses in the two branches reach those for the corresponding plane strain, two parallel tunnel case two diameters from the point of intersection of thq inner tunnel walls. Very high stress concentra- tions occur in the pillar of rock between the inner tunnel walls near the point of intersection.

Jan 1, 1976

LESLIE BRADFORD GOLDEN JUBILEE ORATION "Not only a metallurgist but a scientist of the highest order" Leslie Bradford and the Australian Metallurgical Industry

Jan 1, 1987

This paper briefly reviews the history of mine haulage trucks. It reviews producti- vity limitations with respect to size or speed. Changing haul requirements once again create the need for more flexible mechanical drive power transmission equipment. The new equip- ment however is designed to provide extended life between overhauls as compared with previous mechanical transmissions.

Jan 1, 1981

By Dimitrakopoulos R

Ore textures in base metal deposits are an important factor in the liberation of the economic components of the ore, metal recovery and reagent consumption during beneficiation. Optimising the mine profit requires knowing the relationship between ore texture and mineral processing behaviour, and the ability to predict the metal grade and the ore texture at a suitable scale. A new method that generates distributions of mesotextures for any mining block size or shape is proposed and includes: I . establishing a protocol for acquiring mesotexture data: 2. measuring the mesotexture spatial correlations using a multi-texture variogram; 3. generating multiple simulations of mesotextures; and 4. upscaling the simulations to generate the expected mining block/stope mesotexture distributions. Models of the ore textures built using the proposed methodology can be used to assess resources and reserves, enhance ore/waste discrimination and predict the metallurgical behaviour of parcels of ore.

Jan 1, 1997

The Woodcutters deposit, 65 km south- southeast of Darwin, N.T., consists of a series of veins of pyrite, sphalerite, and galena with some silver, cadmium, antimony, and arsenic minerals. The veins are hosted by the Early Proterozoic Whites Formation, a sequence of black slates with interbedded carbonate rocks and minor ash tuffs. The known orebodies occur about 300 to 500 metres above the contact of Whites Formation with the underlying Coomalie Dolomite, which consists of dolomite and magne- site. The stratigraphic setting is lithologic- ally similar to that of the Mt. Isa deposit, Queensland. The orebodies are replacement veins occ- urring along fault and dyke structures which are sub-parallel to the axes of a double-nosed faulted anticline. The orebodies are in part associated with two unusual carbonatized lam- prophyric dykes. The dykes were intruded after the fold and its slaty cleavage were formed. The ore has replaced the dykes and host rocks and is therefore late-stage hydrothermal miner- alization. The known orebodies are open at depth. A "bonanza" of high-grade ore occurs at the upper part of the largest orebody and is currently the subject of an open cut mine planning study by a consortium of companies headed by Nicron Resources Ltd.

Jan 1, 1984

By Schofield D

The problem of production scheduling is sufficiently complex to negate the use of many conventional optimising techniques as there are numerous and diverse factors that must be considered when trying to produce an optimal schedule. These factors include: grade distribution, orebody geometry, production rate capacity, processing constraints and market price of the minerals amongst a variety of others. In addition it may be observed that many of these factors incorporate a degree of uncertainty and any schedule produced must inevitably consider risk as a primary consideration. The very nature of the problem has limited the use of conventional optimisers. Genetic algorithms use methods based upon evolution and natural selection to produce `optimal' solutions to complex system problems. They are extremely flexible and robust in their nature and it is these characteristics that are important in this particular problem domain. A particular strength of the genetic optimisation approach is the ability to handle the multiple and non-linear constraints that are typically encountered in mine scheduling problems. This paper concentrates on the development of a prototype application of a genetic algorithm to the problem of scheduling the output from multiple production points in an underground mining operation. In particular it.describes a system (GO-SCHED) that can be customised to handle a wide variety of underground scheduling problems. GO-SCHED, a Windows-based system, can interface with a variety of databases and spreadsheets for data input and output and provides a simple intuitive approach to the solution of the scheduling problem.

Jan 1, 1995

By Yamada K, Abe H

Magnetic scanning type mass spectrometers have been given improved sensitivity with a large dynamic range and considerable resolution by the addition of a computer-controlled electric equipment. A mass spectrometer equipped with this newly developed electric system was applied to studies of the activities of liquid iron-silicon alloys and of liquid iron-phosphorus alloys at 1600¦C. The range of silicon concentration was 5.8at%-51.1 Si= at%, and values of ySi -3.1+0.15 and es 11.5 +1.5 were obtained. The concentration range of phosphorus was 1.3at%-5.7at% and a value of eP=7.3+0.1 was obtained.

Jan 1, 1980