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By Gibson I, Somerville J

Three main confined aquifers occur in interseam sediments beneath the planned excavation for the Loy Yang Brown Coal Open Cut. Sub-artesian groundwater pressures occur in all aquifers necessitating dewatering to prevent excessive seepage and depressurisation to prevent heaving of the open cut floor and batter instability. Reduction of water pressures in coal joints is also required to maintain coal face stability. This paper describes the depressurization and dewatering strategies, investigation for and installation of pump bores and groundwater observation bores. Approximately 5000m of drilling is carried out annually for dewatering at Loy Yang and both cable tool and rotary flush drilling methods are utilized. The cabletool method is used to obtain accurate samples for laboratory analysis, whereas rotary flush methods are used for speed and for installation of the larger diameter pumping bores. A method of re-establishing pump bores after partial excavation during mine development has been successfully developed with large cost savings. Trials are also being conducted with pre-collaring of deep bores with rotary methods then sampling the aquifer strata with a cable tool rig.

Jan 1, 1988

By Bartosiewicz H

A method for the determination of the gas content of coal seams is presented which improves upon existing methods. The method makes use of a gravitational technique for measurement of the gas desorbed. The amount of lost gas is estimated by determining an empirical relationship relating the desorption of gas with time for each sample separately. This is to replace the assumption that desorp- tion follows a square root law with time. Laboratory investigations have been conducted which indicate that the square root desorption law does not hold good for carbon dioxide. Results of investigations on various factors influencing the technique are presented. It is shown that co-efficients of the empirical equation are dependent upon the elapsed time and the period of observation. Data about gas pressure measurements is presented and it is concluded that gas pressure can be approxi- mated to 0.6 times the pressure below a column of water equal to the depth of cover. This estimate is good enough for adsorption tests to evaluate desorption co-efficients. The technique for repressurisation of the sample,

Jan 1, 1982

This paper presents a review of computer techniques for the automatic contouring of geological and geophysical data with output as interactive display on graph plotters or graphics terminals and passive display on automatic drafting tables. The advantages of the method of fitting a triangulated surface to randomly distributed data using an advancing front algorithm are described, as well as the technique for determining interpolated values for the production of contour line segments and a contour smoothing algorithm. This contouring method is employed by the Geological Survey of Queensland and is implemented as an interactive system. An alternative method ideally suited to randomly distributed data involves the use of piecewise parametric cubic splines. This method which is ideal for sharp variations in magnitude and areal extent typical of geophysical anomalies is discussed. The mathematics of surface interpolation using non-parametric splines and an explicit piecewise surface fitting technique are discussed. Curve tracing techniques which are suitable for automatic contouring are also presented and the inherent advantages of interactive contouring using on-line plotters and graphics terminals for previewing of displays are described.

Jan 1, 1977

By Turco E, Pelizza S, Castellani F, Stanganelli V

Excavation are in progress for the building of tunnels of the waterworks in West Campania (Naples). The works afferent to part II envisage tunnelling through a miocenic clay formation over consolidated by two tunnels whose sections are respectively 50 and 10m2. Tunnel blasting is carried out by mechanical means. An excavator is used in the big tunnel, whereas in the small tunnel a roadheader machine is used for a short tract and a mechanized shield is used over a long stretch. The tunnel feature complex problems regarding stability. This is particularly so for the big tunnel whose face appears unstable. For this reason the clay on the face is sistematically bolted by means of 3-metre and 12-metre bolts. This prevent the use of a TBM for tunnel Excavation.

Jan 1, 1987

Concrete has been used for many years in block caving, principally for drift and drawpoint linings. This paper describes the requirements for concrete in this application, the required properties, the mix design, and transportation and placement systems. In addition a concrete mix design rationale is also proposed.

Jan 1, 2000

By Moore A. J

Blasting in mines in an urban environment can be conducted safely and within regulatory vibration limits by careful attention to detail and the application of correct techniques. Factors affecting blast vibration are described using surface and underground mining examples. An understanding of these factors provides an essential base for effective planning and operational control. Techniques are described for assessing and predicting vibration levels and the presentation of data for planning purposes such as environmental impact statements for new projects and the protection of buffer zones around existing operations.

Jan 1, 1997

By Glassock C. D

Most Australian mining projects are becoming smaller, more remote and with lower grades of ore. Their small size has been making it harder for mining companies to absorb the large infrastructure costs. This has forced companies to reduce those costs in every way they can. Social factors, environmental groups and even tax laws have added other pressures to force down the infrastructure costs for remote projects. For the last ten years, the downward trend in costs has been marked. It seems certain to continue for years into the Future.

Jan 1, 1997

By Qi P. H

Gold dissolution can be achieved with a number of complexing ligands, all with varying degrees of stability. Processes based on the use of halogens have been known for many years. Beside providing the necessary complex- ing role, the halogens under the appropriate conditions are very effective oxidants for gold. Of the halogens, the gold iodide complexes are the most stable in aqueous solution. Iodine can establish the desired oxidation poten- tial for oxidizing gold, and unlike chlorine and bromine, the oxidizing potential of iodine is mild enough to avoid the oxidation of impurity constituents like metal sulfides. A series of experiments to investigate the fundamental electrochemistry of gold in different halide solutions was performed. Cyclic voltammograms of gold in the presence of 10-2 M chloride, bromide and iodide, respectively show that for a given potential the rate of oxidation is much faster in iodide solution than in either chloride or bromide. An overlay of linear sweep voltammograms for the anodic oxidation of gold in iodide and the cathodic reduction of iodine species on gold provides an effective method for examining the dissolution of gold in iodideftodine solution. The dissolution rates obtained from both electrochemical and actual leaching results are compared. Optimum leaching conditions are analyzed in terms of the iodide/iodine concentrations. Conceptual processes for the recovery of gold and iodide and the regeneration of iodine are discussed.

Jan 1, 1991

The continuous casting of zinc alloys has been of fundamental importance for many years in the production of a number of products, including sheet for architectural applications, battery cans for dry cells and wire for metallising. The intrinsic benefits of continuous casting, including efficiency and high tonnage capability, uniformity of metallurgical structure and properties, and absence of voids and other defects, have contributed to the success of these products. Less well known, but of growing importance, is the more recent application of continuous casting technology to the production of zinc alloy bar stock products, including bearing stock, machining bar stock, forging stock and cathodic protection anodes. A wide range of zinc alloys are now continuously cast in a variety of cross sectional shapes and sizes to suit the diverse characteristics of these products. Of particular significance are the introduction of hollow zinc-aluminum bearing stock, and the availability of zinc alloy machining bar stock for hydraulic applications and for producing prototypes of zinc alloy pressure die castings. In addition to the traditional benefits, continuous casting provides special properties which are important in the application of these bar stock products. The list of successful applications of continuously cast zinc alloy bar stock is growing rapidly, and the market potential for resultant new zinc applications appears to be significant.

Jan 1, 1993

By Laajalehto K

The basic condition necessary for flotation is hydrophobicity of the surface of the mineral to be floated. For sulphides, this condition usually requires treatment with a collector solution. The conditions for this treatment have until recently usually been chosen by the trial and error principle which has indeed been working relatively well under favourable conditions; ie for simple homogeneous ores. However, the present tendency to increasing use of complex and often relatively lean ores sets increasing requirements for the control of the flotation process. This development is the reason for the present rapid development of process control methods in flotation. In addition to the already well-established practices of pH and reagent feed controls, the importance of measuring and controlling the electrochemical potential of the ore particles to be floated is recognised in the case of sufficiently conductive minerals. In fact, the electrochemical potential seems to be the basic quantity determining the flotation behaviour of such relatively well-conducting minerals as sulphides. Since the hydrophobicity of the mineral and, hence, its flotation properties are ultimately determined by the composition and structure of its surface, information on these under different process conditions is important for design and operation of efficient flotation processes. The basic requirement set for the methods used for obtaining this information is high surface sensitivity of the method. The recent rapid development of surface characterisation has produced several methods which fulfil this requirement. Their application to the problem of characterising surfaces of mineral samples in contact with collector solution is, however, often complicated. The main reason for this is the vacuum environment necessary for the measurement. In the case of flotation experiments this means that in most of these methods the measurement cannot be made in situ, but the sample must be extracted from the liquid and subsequently evacuated in the vacuum chamber of the instrument. It is essential to carry out these steps so as to avoid to the extent possible changes in the sample surface. For the purpose of establishing whether this has been accomplished it is important to compare the results of methods operating in vacuum with some available in situ method. An optimal choice of methods seems therefore to be a combination of the available powerful vacuum methods with in situ measurements. The most usual combination seems to be X-ray photoelectron spectroscopy (XPS or ESCA), Fourier transform infrared spectroscopy (FTIR) and electrochemical measurements. This choice combines the unique possibilities for direct elemental and chemical characterisation offered by XPS (Cecile, 1985) with the in situ capability of FTIR and electrochemistry. In the XPS measurements, it is essential to apply a special sample handling technique to avoid loss or damage of some sensitive species of the collector-based layer on the mineral surface. In the following will be given some examples of the application of the XPS technique in combination with electrochemical methods of sample treatment to studies of the layer formed on sulphide substrates in ethyl xanthate (EX)

Jan 1, 1993

By Roberts C

The satisfactory testing and characterisation of mineralisation amenable to heap leaching, is of prime importance to successful operation of a project. This paper outlines a methodology for assessing material suitability. A general model is used for classing material types for suitability for treatment and for economic analysis. The four levels of these are overburden, oxide, transitional and unoxidised materials. During exploration, reverse circulation (RC) drilling can be used effectively to define these zones by a combination of logging, analysis and provision of cuttings for column leach and bottle roll trials. RC cuttings can he used effectively for column leach trials, when calibrated against conventional processing-sized samples, obtained from surface. Tbis allows metallurgical testing to depth and definition of transitional ore types and the base of oxidation, accurately and economically with an acceptable density of samples. The accurate prediction of base of oxidation and variations in recovery with depth and ore types can be used to develop 'economic' pit designs with zones of variable recovery. Petrological studies of leaching results and examination of mineralisation types carried out on concentrates, provide information on gold distribution and physical and chemical constraints. The examination of concentrates can be particularly useful for types of mineralisation when overall gold content is frequently at or below one pan per million. Explanation of anomalous recovery of gold grains in dense goethite and solution-robbing by carbonaceous material can be identified by use of petrological and scanning electron microscope. An understanding of the role of the host rock in leaching characteristics can also he provided by petrology where siliceous or clayey materials can require significantly different treatment.

Jan 1, 1994

The mining industry worldwide relies upon the identification of resources that can be economically developed and operated. Access to land is paramount through all stages of the exploration, development, operation and rehabilitation stages. Clear rights to use of land for the purposes of mining must be available and protected throughout the life of the project. Stable and enduring criteria for mining of the resource, once identified, are required to attract exploration and development expenditure. The purpose of this paper is to investigate the varying approaches to granting access to land for use for exploration and mining development, including the processes by which a project is approved by community and government and the time scale for such approval. The paper concentrates on the legal issues arising throughout this process. The law is stated as at September 1997.

Jan 1, 1997

Ion exchange resins are an attractive alternative to activated carbon in both column and resin-in-pulp processes for the recovery of gold from cyanide solution. Resins are widely used for this purpose in the Soviet Union apparently in preference to activated carbons.A wide range of resins are available and the high level of resin technology is demon-strated in the resin processes used to recover uranium.The anionic gold complex, Au(CN) 2 , is selectively adsorbed onto weak and strong base resins. However other anionic cyanide complexes, cyanide ions and other anions from the process water are also adsorbed onto resin sites. Resin selectively for gold is not as high as it is for activated carbons. As a result similar gold loading capacities are obtained for resins and carbons when used in plant liquors.

Jan 1, 1984

By Cousens DR, Benhamou M, French DH

Techniques appropriate to petrographic image analysis are being developed using digitized backscatter electron images of well characterized mineral assemblages obtained from a Cameca scanning electron microprobe. Emphasis is on developing descriptors for size, shape and association of mineral grains as these all convey important information concerning the nature of rocks and the processes that have operated upon them. Processes, for example, that could indicate the proximity of mineralization. For convenience, the work is being carried out on the PDP11/73 host computer of the electron micropt be, although it is recongnized that such a multi-user environment is not appropriate for practical image analysis. The eventual aim is to develop a low-cost microcomputer-based package for quantitative description of mineral textures and rock fabrics as an objective aid to the petrographic analysis of ores and host rocks.

Jan 1, 1989

Zinc alloy castings continue to account for a very large, world-wide end-use market for zinc. However, an ever expanding multitude of other materials and processes are increasingly providing viable, cost-effective alternatives to designers, many of whom have no particular allegiance to any one industry. In order to meet this challenge, innovation of and for the zinc hot chamber pressure die casting process, in concert with sustained and inventive market development, is clearly required. While 'Quality' is now the watchword, and the goal of zero defects is being rigorously pursued, other important goals which must be addressed include net shape casting, enhanced productivity and increased energy efficiency. The paper gives an overview of several practical, process-orientated, projects designed to help achieve these goals. For example, a project designed to understand and precisely measure dimensional changes of castings with time has provided some of the critical information needed for net shape casting. A second study is looking anew at surface quality in relation to process conditions as an important step toward the goals of zero scrap rate and increased productivity. Developing the correct die casting machine parameters for achieving optimal quality and properties of zinc (ZA) die castings is a further example of research designed to benefit both the die caster and his customer, chiefly the original equipment manufacturer (OEM). A project on die soldering or galvanising in response to varying process parameters is similarly being considered in order to foster increased understanding and avoidance of problems, with a special interest in the use of special coatings. The maintenance or expansion of the future market for zinc die casting alloys also depends on design for functional applications, as an adjunct to their traditional decorative use. The role that alloys with enhanced properties can play, such as ZATEC, a new high creep resistant alloy developed specifically for elevated stress/elevated temperature applications, will be briefly discussed.

Jan 1, 1993

In order to realise seafloor massive sulfide (SMS) mining, the environmental baseline survey around targeted SMS mining areas and the creation of an environmental assessment technique suitable for quantifying the impacts of ocean floor mining are necessary. The targeted areas generally host large chemosynthetic communities in association with active hydrothermal venting. The ecosystem structure around the chemosynthetic communities has not been clarified yet in macro-scale or quantitatively. The systematic approach and plan for the baseline survey and the environmental assessmentÆs basic studies are introduced. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Jensen B

The approach of using the Coward Triangle for the analysis of flammable mine gas mixtures has been examined for its application, to the flammability of coal dust/gas/air mixtures. Explosible lean limit and rich limit concentration data for dust/methane/air mixtures are examined and illustrated using co-ordinate geometry. It is concluded that a three-dimensional envelope representing hybrid explosible mixtures can be drawn. The dimensions of this explosive zone will vary with the characteristics of the coal dust and the gaseous composition of the mine atmosphere. Further research is needed to establish these dimensions for important mined seams.

Jan 1, 1994

By Hohnen CA, Limerick JM, Hall DRT

An uniquely-designed flash furnace for smelting of nickel concentrate and for the recovering of metal values from the slag generated has been in successful use for nearly six years. Within the last eighteen months the ability of the furnace to treat slag arising from converting operations without significant reduction in capacity has also been successfully demonstrated. Previously, converter slag had been treated separately in an electric furnace. The salient features of smelter developments are outlined and slag chemistry is discussed. The low cost method for the introduction of coal to partially replace light fuel oil is reviewed and total energy requirements evaluated.

Jan 1, 1984

By Fukuda M, Kurita K

A mathematical model for estimating the liquid level in the hearth is presented. The analytical result was checked on a cold two-dimensional model and an additional boundary condition for the fundamental equation resulted. The applicability of the resultant equation was investigated on a cold model and a regression equation obtained for the average liquid level for Kashima No. 1 BF. Comparison of calculated and observed results were in fairly good agreement. It is concluded that the liquid level in the commercial furnace can be calculated from the measured values of pressure in the bosh and operating conditions.

Jan 1, 1975

By Simpson JF, Murrie SJ

In determining new areas for slag disposal a foamed slag aggregate has been developed for use as a skid resistant material. The foaming of the slag does not rely on the use of water, but rather on the slag chemistry. Laboratory test results indicated that a product having good skid resistant properties has been prod- uced. A section of road is being assessed for performance of the aggregate in a surface dressing application under heavy load. The results from the test section after seven months have shown that the foamed slag is suitable for this application. Further test sections are now being considered.

Jan 1, 1979