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The importance of orebody definition and optimisation in project development cannot be overstated. Inappropriate orebody definition is the single most important reason for project under performance and/or failure. Without the firm foundation of good orebody definition, the structure of a project cannot be assembled reliably. Many factors need to be considered in the process of orebody definition. These factors are well summed up in paragraph 123 of The Institute's Code and Guidelines for Assessment and Valuation of Mineral Assets and Mineral Securities (Valmin Code). The factors range from the initial geological data through assaying, geotechnical and hydrogeological factors to mining and metallurgical considerations. There are other factors which also need to be considered including marketing and environmental factors. This paper briefly reviews some of these factors and their impact on project development. Three examples are presented where one or more of these factors have had significant impact on the development of the Project.

Jan 1, 1997

By Reimer TH

The model described in this paper has been developed for and in close collaboration with the Bong Mining Company Ltd, Liberia/West Africa. When working an irregular deposit a de- tailed short term production schedule becomes necessary in order to ensure an equal and homo- genous concentrator feed. If the irregularity of the ore body exceeds a certain degree, blen- ding facilities have to be provided between the mine and the concentrator, but even then sche- duling of the mine production is inevitable to meet the given requirements of the blending bed and to keep these conditions steady for at least some of the successive periods. To assist the planning department in set- ting up optimal production schedules a computer model has been developed using a linear pro- gramming approach. The deposit is divided into equally shaped blocks containing defined quali- ties and quantities of ore and/or waste; from which one has to select those quantities of ore which will meet the requirements of the blen- ding bed. The objective function of the model

Jan 1, 1977

By Neill B. K, Fander H. W, Wong K, Dunlop G, O&apos

Commercial interest in refractory gold is increasing rapidly. This trend is supported by the work patterns of Amdel, where, apartfrom routine process- ing of free-milling and refractory ores, the majority of testing now includes biological and pressure oxidation studies to enhance gold recoveries. Central Mineralogical Services have examined, among other ores, an apparently unique type of refractory coating. A summary is given of experience at Optimet Laboratories, Pty., Limited. Research into nitric acid pre-oxidation, underway at the South Australian Institute of Technology since 1987, has shown significant improvements in gold recoveries, and in some cases, large reductions in reagent consump- tions. Three final-year student research projects were undertaken in 1990, jointly between the University of Adelaide and the S.A. Institute of Tech- nology. These projects involved biological pre-oxidation, pressure leaching, and Scanning Electron Microscope examination of refractory ores, and the resultant pre-oxidation and cyanidation products.

Jan 1, 1991

By Kerr M. H, Slaughter P. J

Design of the new cemented hydraulic fill plant was based mainly on experience with a succession of previous fill plants. Two stage cycloning of combined concentrator tailings was introduced. Design of the two stage cyclone configuration was assisted by computer simulation of cyclone performance. Cementing additives, namely Portland cement and ground copper reverberatory furnace slag, drawn from bulk storage, are pre-slurried prior to mixing with hydraulic fill. Quality control of fill being sent under- ground is achieved by a series of automatic control loops. Plant instrumentation was given prime consideration during the design phase. Inventory checks of all mass flow metering equipment are made at regular intervals. Fill is pumped to boreholes at several locations. Details of the equipment and operating procedures for the plant are Discussed.

Jan 1, 1973

By De Cuyper J

Laboratory testwork has been performed on ancient residues from the cyanidation of a previously roasted gold-containing pyrite and arsenopyrite ore. By grinding to 95 per cent minus 60 microns, and after a strong aeration conditioning of the pulp, a gold recovery of approximately 67 per cent was obtained by cyanidation. This recovery was brought up to 80 per cent by leaching with thiourea, after a preleaching step with sulphuric acid under severe conditions of acidity and temperature. To avoid excessive capital costs bound to such processes, it was decided to investigate the possibility of applying flotation after grinding at a size similar or finer than the one used for the leaching tests. The method turned out to give interesting results because of the natural flotability observed at pH values lower than two for particles rich in gold present in the residue. After two cleaning steps, a final concentrate, representing around one weight per cent of the feed, was obtained with an approximate gold content of 350 g/t, representing a batch recovery of gold of about 50 per cent. Apart from sulphuric acid, whose addition was very high (flotation slurries at 25 g/l H2SO4), other reagents were not found necessary. Additional flotation tests were carried out to examine whether the recycling of the cleaner tails was justified but the gain observed appeared insufficient.

Jan 1, 1993

Dewatering tailing slurries by mechanical means is often not possible and gravity and solar driven processes must be used. It has been shown previously that better use of gravity is achieved when the tailing is drained as it settles. Not only are more compact sediments obtained but also the dewatering is faster. From the results of laboratory and field tests reported here, equations were established which describe the evaporation and drainage components of the dewatering. These equations were used to calculate the effects of ponding depth, solids content of the tailing and clim- atic conditions on the time required to dewater the tailing. Since the calculations can be made with and without the drainage component, the advantages to be gained with drainage can be determined. The tailing used in the work was a clay slime from a sand washing operation. However, it is anticipated that this approach will be applicable to other similar tailing.

Jan 1, 1978

Mr. Bradford said: - On assuming this chair, which has been oc- cupied by so many gentlemen of conspicuous ability, my first words must be an expression of the gratitude I feel for the honour you have done me in electing me to be your President for this year. When considering the subject matter of this address to you to- night, quite frankly may it be stated that for a long time I was on the horns of a very great dilemma, for while I could discourse on the modern political trend in relation to our industries at great length, it appeared to me that this was not the place for such a discussion.

Jan 1, 1987

By Jimbo I, Ogawa O

A series of experiments was carried out to investigate the solubilities of copper, arsenic, antimony and bismuth in silica-saturated iron silicate slags under controlled oxygen partial pressures at 1200 and 1250¦C. Molten copper containing each of the above elements was kept in contact with a slag in a silica crucible for 24 or 48 hours to attain equilibrium. No me- chanical entrapment of metal into the slag was observed. The appearance of the magnetite phase in the slag was avoided by holding oxygen potentials at substantially lower values than that evaluated from available data on iron silicate slags. Solubilities of copper, arsenic, antimony and bismuth in slags were plotted against oxy- gen potentials and both oxidic and atomic types of dissolution were found, except in the case of arsenic, from the dependencies of the solubili- ties on the oxygen potential and from positive intercepts of regression lines when extra- polated to zero oxygen potential. The dissolu- tion of arsenic seemed mostly oxidic. Distri- bution coefficients of arseò,ic, antimony and bismuth between copper and slag are also Discussed.

Jan 1, 1980

As I drove in from the airport on Sunday somebody said `On the right you will see Dun- troon, which is the military training school of Australia.' So I asked the driver, where did they get that name? `Oh,' he said, `from some people who built a house there. That was it's name- Duntroon.' It strikes a note with me because, that's the name of a 12th century castle on the west coast of Scotland where I spend what leisure hours I have and, therefore, it establishes the long connection between Australia and my native land. There is also a story I should tell you about the oil industry and its upsurge in Scotland recently which has resulted in great prosperity. And in Edinburgh, the walls of the banks are bulging-because of the incursion of foreign exchange and other resources.

Jan 1, 1978

The organisers of this function have suggested that this presentation should accomplish the following broad goals:set the technical tone for the conference to follow, implying some discussion of the æstate-of-the-artÆ of reserve estimation; and raise some current and common problems or deficiencies in our art in order to be thought provoking. As an engineer it is always easier to raise problems than to solve them with state-of-the-art. Consequently, I have had to limit the extensive list of problems that could have been discussed within this presentation. In regard to the state-of-the-art, this presentation will not be an esoteric discussion of the latest statistical estimation processes, although I intend to challenge those with skills in that area to address some of the thought provoking issues later on. The subtitle of the paper was established after reading an excerpt from æLife on the MississippiÆ by the American humorist Mark Twain in which Twain observed that the Mississippi River had become shorter during his working period on the River due to natural cut-offs and man made channels. Projecting into the future, he calculated that by now, Cairo, Missouri and New Orleans, Louisiana would become a single city with one mayor (the two cities are still separated by some 500 air miles). As a moral to this story Mark Twain observed that one can obtain: æwholesale returns of conjecture out of such a trifling investment of factÆ.

Jan 1, 2000

By Bourke J. H, Ashcroft T. B

Many changes have occurred in the world market for manganese over the last five years. Among these, the emergence of divided steel processes for the hot metal refining of pig iron is affecting the use of both ferruginous manganese ore and ferro manganese, at this stage particularly in the Japanese steel industry. Subsequent demand for higher quality manganese materials is promoting the use of thermally beneficiated products such as sinter. In addition, many processes are being developed for the direct smelting of fine manganese ores, of which plasma technology is the most advanced. Cost pressures and product quality requirements are encouraging pre- viously self sufficient countries such as The People's Republic of China and the USSR to import high grade manganese ores to supplement indigenous lower quality supplies. At the same time, Brazil has been provided with the impetus to convert its substantial reserves of ore to value added products.

Jan 1, 1988

By Eldridge B. J

During recent years, Central Queensland has experienced a boom in its coal mining industry. This has involved many companies in projects requiring large capital expenditure. As with most projects of this size, many operating problems are now being experienced which were unforseen at the feasibility stage. One of these problems is the failure of pit slopes and spoil piles at some of the strip mining operations. There have been serious stability problems associated with Utah Development Company's strip mining operations in Central Queensland, in particular the Goonyella Mine. A field investigation programme was under- taken to determine the cause of highwall and spoilpile slope failures. Spoilpile failures were found to result from weakness near the spoil/floor contact zone. Highwall failures were found to result from a combination of unfavourable bedding plane dips and weakness, and the presence of joints in weak o~erburdep; Satisfactory solutions fa the staiity, problems are difficult to formulate, and-field stability experimentation is still at an early Stage.

Jan 1, 1974

The word governing derives from gubernare meaningto pilot a ship. Being inclined to metaphors, one could be forgiven to think that politicians act this verb and captain the Nation's ship into some definite course. In the case of at least the mineral resources industry, it seems that there are not many James Cook followers in our parliaments: Australia's approach to mineral and energy policy is often chaotic - witness the 1935 to 1961 ban on iron ore export-ing which prevented the development of a significant steel industry at time when the World was hungry for this metal, just to mention one amongst many other examples.The follies of Australia's mineral policies are well il-lustrated in the case of uranium mining. Although Australia had the Western World's largest economic reserves of uranium, it is onlythefifth producing nation and its uranium potential is largely unrealised. At the root of this situation are the interventionist attitudes and policies of successive Federal Governments which for more than four decades distorted the Investment decision and, in more recent times. discouraaed investment.

Jan 1, 1990

By Tapp B. A

To date, few studies have been made regarding the energy requirements of the Australian mining and mineral processing industries. This paper indicates that these industries use a substantial proportion of the total Australian energy input (32.7% in 1971-72 and 36.10% in 1974-75). With the growth orientation of these industries, this input is likely to increase. Data shows that mining energy requirementE varied from 4.22% (of total Australian energy requirements) in 1971-72 to 4.16% in 1974-75. Energy requirements for the total mineral processing industries increased from 28.49% to 31.93% for the same period. The total estimated primary energy input varied from 22.56% to 25.2%, whilst indirect energy use, in the form of electricity increased from 10.16% to 10.66%; in the same period. Analysis of primary energy input data within the processing industries (1973/4) showed that the Iron and Steel Industry consumed 15.03% of the Australian total consumption, Non-Ferrous metals, 5.43%, Cement, 1.64%, and Refractories, 1.59%. In toto this represented 24.57% of the total

Jan 1, 1979

By Abdalla MH

The deformation resulting from the presence of a tunnel may signifcantly affected, nearby structures and need to be considered during design of both tunnel and structure. The aim of this paper is to study the effect of different factors which may affect the interaction between the tunnel and the str- ucture. These include; the depth of both tunnel and foundation level of the structure ( z and t ), distance between C.L. of tunnel and loads, breadth of the loaded area, Diameter of tunnel and lining of the tunnel. The problem is studied as a two dimensional plane strain model by the boundary element technique. The results of this study indicated that the presence of a cavity/tunnel increases, in general, the vertical displacement on the ground surface and at the foundation level as well as the horizontal and vertical stresses in the cavity/tunnel level. The effect of eccentricity is increasing as e/D decreasing. For pile foundation there is a quite different- influence of the presence of cavity/tunnel in both cases of friction pile and end bearing pile type of foundation.

Jan 1, 1987

By Sheng X. L

The Jurassic coals at Datong are characterised by their strong, massive sandstone and conglomerate roofs which fail suddenly over large areas, crushing pillars and creating destructive windblasts. collapsed areas have exceeded 180,000m2 and windblasts have extended over one km underground and 200m on the surface and have been accompanied by subsidence troughs on the surface. Scientific analysis has researched premonitory signs of caving and the nature of windblasts leading to considerations of alternative mining methods and ways of dissipating the energy of windblasts to reduce their damage and danger..

Jan 1, 1992

By Eaton R. A

The design of most underground mining machines shows little evidence of regard for ergonomic principles and operator comfort. Likewise, efficiency and ease of operation often appear to have been given little consideration in machines where ruggedness and simplicity have tended to dictate the configuration. Improvements in productivity are amongst the benefits to be gained by a different approach to machine design. The paper describes the philosophy and features of a test bed Load-Haul-Dump Vehicle undergoing trials at Mount Isa Mines. This machine is the outcome of a Research and Development Programme conducted by the Department of Mechanical Engineering at the University of Queensland and Mount Isa Mines Limited. The diesel powered test bed features an enclosed, air conditioned cabin, with a suspended operator's control station and electrically operated controls. An electronically controlled hydrostatic transmission incorporating wheel slip control, is another innovation. The performance and operator acceptance of the machine has led to adoption of most of the concepts in a new machine now being put into production.

Jan 1, 1987

The interfaces between the Broken Hill ore lenses and the enclosing wallrocks are, on a broad scale, parallel to metamorphic layering in the wallrock gneisses and quartzites. In detail, however, the concordant contacts are interrupted by piercement structures, formed by plastic injection of ore into the wallrocks during metamorphism.These discordant bodies vary from minor projections measuring less than I m long, to major ore shoots ("droppers") as much as 60 m long. The intrusive bodies consist of fragmented ore and wallrock in amatrix of recrystallised sulphides. Wallrock fragments have been altered to manganese-rich and calcium-rich mineral assemblages. The injected ore is enriched in sulphides compared with the parent ore, and there has been enrichment in a number of minor elements.Piercement structures formed during the waning phase of high grade metamorphism, when incompetent ore was injected plastically under pressure into the wallrocks, particularly at fold crests. Adjacent to the "droppers", retrograde schists developed as a result of shearing along the ore-wallrock interface.

Jan 1, 1976

By Wright D. C

The operation of the cyanide-sensitive Mintek/TB1 kegold electrode was studied in the laboratory, with regard to equilibration time and drift, the effects of pH, stirring, salinity, dissolved oxygen, zinc and copper(I) ions. Methods for valid calibration in the range 20-600 mg(NaCN)/L and pH values in the range 9 - 12 in the absence of copper were also studied. Increasing the salinity beyond a threshold of 40 g(NaCI)/L improves calibration and measurement. The sensitivity is 91 mV per decade change in the concentration of ionic cyanide, and output is reproducible to within 10 mV with attention to the factors listed above. However, salinity of 40 g(NaCI)/L also sensitises the electrode to interference by copper(1) ions. This copper sensitivity seems capable of saturation, suggesting a research strategy for possible remedies.

Jan 1, 1996

The five main ways in which coal is used are1. for electricity generation,2. as a lump fuel for domestic and industrial purposes,3. for gas making,4. for making carbon for chemical and metallurgicalindustry, and5. as a source of coal tar and coal-tar chemicals.In the past about 80 per cent of Victoria's brown coal has been used for power generation and the rest for making a lump fuel, in the form of briquettes. Some of these briquettes have been used for gas making, and a carbon industry based on them has recently been commenced, and could expand rapidly. However the enormous increases expected in power requirements, approximately a doubling every 10 years, will ensure that even if the manufacture of carbon increases dramatically and a large amount of coal is used for other purposes, the brown coal industry will always be dominated by power generation. As new fuels such as natural gas, oil, and nuclear fuel become available at competitive prices these will take their share of the power generation load.Natural gas or oil, or possibly pumped storage hydro, will almost certainly be used for all future peak-load stations, comprising around 40 per cent of the total installed generating capacity, but new base load stations will continue to be designed for brown coal operation until about the mid-1980s, by which time nuclear power stations will become competitive. By this time Victoria will have installed about 6000 MW capacity of brown coal stations, burning around 50 million tons/year of coal, compared with 18 million tons/year at present, with perhaps 15 million tons/year being used for other purposes.This consumption of 65 million tons/year should then remain fairly stable over the life of the power stations installed, well into the 21st century. Brown coal therefore appears to have an assured place in providinga major part of Victoria's fuel requirements, despite the diversification in fuel usage pattern which appears certain to occur with the recent developments in new fuel resources.

Jan 1, 1971