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Uniaxial compressive strength and Young's modulus values measured in the laboratory on NX diamond drill cores were examined statistically to bring out any significant differences between different locations in the mine which might require special treatment in subsequent photoelastic analyses of the mine layout. Correlations were sought between the strength and modulus and various other features of the rock. The estimated mineral content of the core correlated with the modulus of the core, but the range of modulus values was too limited to show any strong correlation with compressive strength.Strength in the vertical direction was found to be significantly higher than in the horizontal direction and the same pattern was followed by the moduli, but was less pronounced. It was concluded that, whilst the modulus variations were significant, they would not invalidate any photoelastic studies.

Jan 1, 1969

By Lindbeck K

The mining industry in Western Australia is a large sector of the WA economy providing $12 billion (1993) of the export income for the State. Historically, mining in WA developed from traditional prospecting in the late-1880s leading to major underground operations by the turn of the century. Large open pits were developed in WA following World War II and became increasingly common since the gold boom of the 1980s. With the development of the open pits has been concomitant evolution of mining legislation, principally the Mining Acts of 1904 and 1978, which has been also accompanied by a practical evolution of the administrative system within the Department of Minerals and Energy. The mining industry has recognised the need for sound environmental management at mine sites, taking up the challenge and becoming a world leader in rehabilitation techniques. Any environmental management program in the industry has three stages: approval by government; management by the industry; and return to the State in an environmentally acceptable condition. The WA environmental requirements, procedures and industry performance in these three stages are discussed.

Jan 1, 1994

This paper describes some experiences in the design of flotation reagent schemes for the efficient flotation of complex gold ores containing free gold and/or gold associated with easily flotable sulphide minerals such as chalcopyrite and bornite. Historically, the design of gold flotation reagent schemes has been based primarily on experiences using high dosage levels of water soluble charged collectors such as xanthates and dithiophosphates and carefully controlled regions of pH. This approach has been effective with gold associated with complex sulphide minerals, in particular gold associated with iron sulphides such as pyrite. An alternative two-stage reagent approach is presented that is applicable to certain types of gold ores. This approach involves using very small dosages of uncharged water insoluble collectors at natural ore pH followed by a modified bulk flotation reagent approach for the second stage. The reasons for utilising this approach, when applicable, are discussed and illustrated with examples.

Jan 1, 1997

By M H. Mian

Much has been published on resuspension of sediments in lakes and estuaries. In general, resuspension has implications on transport and release of contaminants from the sediments. It has been shown that wind-induced waves contribute to erosion of sediments, which are then distributed to various sections of the water body by currents. Empirical equations formulated on the basis of cohesionless sediment behaviour have been applied to the design of a few tailings ponds in different parts of the world, especially in the selection of the necessary depth of water to minimise negative environmental impacts. The paper highlights the shortcomings inherent in these equations using field-measured data from a tailings site in Canada. Laboratory measured tailings properties are used to identify critical shear stresses required to initiate tailings erosion. The influence of cohesion on resuspension of fine-textured tailings is discussed.

Jan 1, 2003

The technological advancement in computing power and the increasing demand for information processing systems spread throughout many aspects of a corporation's business activities has revolutionised management information systems departments. This revolution is manifest in the proliferation of mini-computers and micro-processors as well as the planned or unplanned migration from centralised processing to distributed processing. The total data processing investment in people, hardware, software and telecommunications has reached a high level in many organisations. Therefore, the cost of inadequate planning or ad hoc growth of systems can be considerable. The concept of MIS systems planning has gained adherence in recent years; however, there appears to be a wide diversity in the effectiveness and quality of corporate systems plans. To be effective a systems plan must have the support and concurrence of executive management of an organisation. A disciplined planning approach to systems together ,with the involvement of senior user management as well as MIS management is necessary to develop a satisfactory systems plan that forms the basis of a corporation's data processing strategy.

Jan 1, 1980

Owing to the 'creeps' and consequent movements in the mines, followed by the recent fire in the southern workings, the whole of the orebody above the 800 ft. level is now very much crushed and broken. The same applies to the hanging wall or overwall coutrny, which has subsided towards the workings, so that for some years past all development work within the lode has had to be carried out with extreme care.The continual but slow subsidence of the overburden into the stopes necessitates a periodical renewal of all gangways in the lode, and, as the subsidence amounts to as much as 60 ft. in places, these new gangways must necessarily pass through the mullock-filling of old stopes in addition to broken ore. They at times pass into the broken ground of the hanging-wall for some distance, where the orebody has widened underneath by the original folding and puckering.

Jan 1, 1932

By M A. Faizulin, N G. Stukalova

The present till now practice of averaging of ore by metal content at mining-dressing enterprises does not allow evaluating objectively really existing regularities of dressing process. The processing of large statistical data by specially designed methods has revealed the relationships of extracted mass of metals into concentrates when processing of ore at preparation plants. The analysis of the obtained relationships points to necessity of timely control by flows of ore with due account of different sorts of metal. For this problem solving it is offered to use specially designed methods on carrying out of calendar planning of a mining and shipment of ore at open casts, based on ranked arriving of flows of different sorts ores to preparation plant. The given methods includes economic-mathematical model forming and its implementing by worked out method. The formed model allows taking into account different technological and organisation limits, typical operation conditions of open cast and preparation plants. Using this methods of control of mining operations and designed on its basis the complex of software allows increasing volume of metals, extracting into concentrate, up to two per cent without any additional costs and saving of the existing technological schemes at preparation plant.

Jan 1, 2003

One distinctive feature of the global mining industry approaching the twenty-first century is the worldwide commitment of mining houses to large-scale projects in developing countries. One good example is BHP's development of the Escondida copper project in Chile. The Escondida orebody was discovered in 1981 and construction began in July 1988. Mining began in December 1990 at a design capacity of 320 000 tonnes of copper contained in concentrate. Out put has grown significantly and shortly Escondida will become the largest single copper mine in the world producing copper at the rate of 800 000 tonnes per annum, including 80 000 tonnes of copper metal. Escondida provides a case study of the development and growth of a large-scale mining operation in a developing country. Key elements have been innovative financing, the management of country risk, the recruitment of an excellent workforce, the use of advanced technologies and best practice in environmental management and community relations. Escondida is one of the global mining industry's success stories in the 1990s.

Jan 1, 1996

Classifications of Ni-Cu deposits are based on petrology, geochemistry and the geotectonic setting of host igneous bodies (Naldrett and Cabri, 1976; Besson et al, 1979; Nadrett, 1989). The four major classes in Naldrett's (1989) division rest on the geotectonic setting of the igneous complexes and the classes are further subdivided on the basis of the petrology and geochemistry of the intrusion. A more common subdivision of mafic and ultramafic igneous rocks is based on the environment of rock-forming processes, endogenic or exogenic, intrusive or extrusive, and this subdivision has been applied, in practice, to the classification of sulphide Ni-Cu deposits, too. The extrusive deposits, Class I in Naldrett's (1989) classification, are directly related to volcanic processes whereas all the others refer to the intrusive environment. This paper looks at the differences between the extrusive and intrusive groups of Ni-Cu deposits and presents generic, genetic and structural features of the intrusive group.

Jan 1, 1996

Mine dewatering has long been a problem with mines and some of the shallowest mines have the biggest problems. Machinery was developed by the ancients for raising water by rope buckets with treadmills or by horse whim. From the 1700's on into the early part of this century, massive cornish pumps or equivalent were the vogue powered by steam. One Australian mine pumping system was claimed to be the largest in the world just after the turn of the century. It was installed at Beaconsfield in Tasmania and the mine, like so many other mines of the period, were beaten by problems and cost associated with mine dewatering. The owners of that mine are looking at the feasibility of dewatering using surface drilled wells. Much simpler and smaller pumps are the order now and it is feasible to use boreholes instead of shafts to contain the pumps or else to use the holes to convey discharge waters to the surface from pumps located in drives or stopes.

Jan 1, 1988

From December 1994 to November 1997 Odin MiningÆs Estero Hondo alluvial gold mine in western Ecuador washed almost 3.2 million bank cubic metres of gravel to produce just over 2600 kilograms of pure gold at a recovered grade of about 0.8 grams per bank cubic metre. The operation was a simple open pit. Draglines stripped the overburden, backhoes mined the gravel, and trucks transported the ore to a stationary, gravity-based wash plant for processing. At start-up the planned throughput was 55 000 bank cubic metres/month, but a year later this had been increased to 100 000 bank cubic metres/month. From April 1993 to July 1997 a total of 440 churn drill holes and 15 pits were sunk to test the property. The methods used to prepare the resource and reserve estimates from the raw field data are described, and seven sets of completed estimates are used to track the evolution of the projectÆs resource/reserve base through the exploration, feasibility and production stages.

Jan 1, 2003

By M M. Tarshan

Separator performance is evaluated by the so-called separation efficiency. The concept of efficiency in mineral dressing operations must be interpreted with considerable care. Although qualitative use of term efficiency is valid and useful, difficulties arise in expressing it quantitatively because two conflicting criteria, grade and recovery are normally involved in its evaluation. It is undesirable to express efficiency as a single value, even though this is frequently done in practice, since there are strictly speaking an infinite number of combinations of grade and recovery that can give that one value. Inefficiencies in processes can be attributed to three broad sources: mineral limitations as represented by the separability curves, equipment limitations (which prevent the maximum separation indicated by the separability curves), and human failure to minimise these inefficiencies. In the present paper, the efficiency of a two-constituent separation process has been examined. The separation process has been evaluated by comparing the sharpness factor of the actual, the absolutely efficient and the absolutely inefficient operations.

Jan 1, 2000

In those days no one worried - there were plenty of other things to do. But in'these days it is different. Everyone worries- and. because there is so much worry, emotion has entered the picture. And, worse than that, capital is being made in political circles. People who were quite unaware, five years ago, that any problem existed, have now become experts on the subject, and shout to high heaven that something should be done - and yet they go on using the leaded high octane petrol they deplore so much. And even scientists, who should know better, adduce only such evidence as fits the argument in hand. And the Press is not without blame - some of its reportings is open to serious question, whatever may be the excellence of its motives. The point is made that one should know what one is talking about. And make sure that the evidence quoted is fact - and make sure too, that all the evidence is used, not only that which suita the argument.

Jan 1, 1971

I am honoured, deeply honoured, that so distinguished a group has assembled to acknowledge the signifi- cance of the work of my Melbourne flotation research laboratory, to review progress since Principles of Flotation (Wark, 1938) was published, to highlight the present state of knowledge, and to point the way for future research. The flotation research which began in 1929 was sponsored by a group of mining companies2 at the instigation of Harry Hey of the Electrolytic Zinc Company of Australasia Limited. There were never more than three of us work- ing in rather cramped conditions in a laboratory made available by the Department of Chemistry at the Uni- versity of Melbourne, but what we lacked in space was more than offset by a freedom unparalleled in indus- trial research in Australia at that time. I pay special tribute to my first colleague, Alwyn Cox; to my wife who worked with us for several years; and to Keith Sutherland who followed Cox in 1936. They were my sole colleagues up to 1938 when Principles of Flo- tation (Wark, 1938) was published.

Jan 1, 1984

Metal grades and contents of ore deposits should be measured in an unbiased manner, and with a degree of precision that reduces to an acceptable level the risk to put into production inviable prospects. The additive property of variances for metal grades and contents is used to assess the accuracy and precision characteristics of this measurement process. Each stage in the process of extracting different types of samples from ore deposits, preparing test samples from drill core sections, drill chips or crushed ore, and collecting and assaying test portions, contributes a variance component to the intrinsic variability of a metal's distribution in its matrix. Deducting such extrinsic variances results in more precise estimates for metal grades and contents of elementary units. The cumulative metal content for a set of elementary units of in-situ ore, and the sum of the variances for metal contents of all units in the set, can be used to calculate confidence intervals and confidence ranges at different probability levels as measures for risk.

Jan 1, 1976

By Lewis IE

Copper-lead dross is a by-product of the refining of lead bullion produced by the Imper- ial Smelting Process. This dross contains some 27 percent copper, 50 percent lead, four percent zinc and one percent sulphur. An ammonium carb- onate leach at atmospheric temperature and pressure removed the copper from the dross while the lead zinc and precious metals remained in the leach residue for return to the smelter. The leach solution containing the copper was then purified by liquid-liquid ion exchange using LIX64N in a kerosene diluent. ("LIX" is the registered trade mark of a range of hydroxy oximes marketed by General Mills Inc.) The pilot plant had a capacity of 0.7 kg/h of CuSO4,5H20 and was operated for some fifty days on a two shift basis. Copper sulphate of excellent purity was produced, and the results obtained indicated that a copper recovery of ninety percent from the dross could be expected from a commercial installation.

Jan 1, 1975

By Adam R. A

Techniques for the optimisation of open pit design and development are now accepted as standard practice in the mining industry. These techniques are used to analyse the impacts on project profitability of factors such as product price, slope design criteria and equipment selection. A fundamental assumption used in this type of analysis is that dump and stockpile designs and sequencing are predetermined. The cost of haulage for a typical truck shovel mining operation is in the range of 25 - 50 per cent of mine operating costs. Substantial cost savings can be achieved by optimisation of dump design and location of associated road and ramp systems.Factors which affect both the operation and total cost of dumping include; Ramp gradients and location, road design, dump placement and shape, dumping height, slope design (interim and final), slope stability, environmental requirements and equipment selection. This paper discusses these factors and their effects on the total mining operation and project value. Reference is made to case studies in which some of these factors have had a significant impact.

Jan 1, 1992

By Tapponnier P

In North Vietnam, large ductile shear zones are observed along the Red river fault and the Dienbien fault. Left-lateral sense of the Red river shear zone is related to the direction of shortening E-W. NE dipping foliation planes is subvertical. Stretching lineation is subhorizontal ( 25¦). Left-lateral slip observed in the Oligocene Yansun granites demonstrates the major tectonic phase in Neogene, The stress field established from microfaults observed in triassic limestones, Oligocene granites and Neogene Conglomerates. Measurements of striations on fault mirors are used for calculating the stress tensor and for separating tectonic phases. Two tectonic phases in tertiary are separated : first tectonic phase related to the compressive direction E-W corresponds to the major tectonic phase represented by NW left-lateral shear zone. Second phase having the compressive direction N-S associated with the right-lateral movement of the Red-river fault zone opening of the Eastern sea and the Red-river and the Red-river delta is associated with the left-lateral movement along the Red-river.

Jan 1, 1990

This paper reviews an analytical model that defines the relationship of weight-weighted or volume-weighted average haulage distance with bench height and other related parameters; presents the optimum bench heights under various conditions in terms of minimising the weighted average haulage distance of ore/waste during the full lifetime of an open pit mine, and discusses the truck-haulage economics of mining open pits by high bench, specifically by 15 m, 18 m and 20 m bench through marginal analysis. The observations from these analyses disprove the previous conflicting assertions that the overall weighted average haulage distance either increases or decreases monotonically with bench height. It is concluded that: (i) an increase of bench height to 15 m from 12 m is likely to be viable under the general conditions of large-scale deep open-pit mines; (ii) the reduction of haulage cost is limited with the case of increasing bench height to 18 m from 15 m; and (iii) the feasibility of mining open pits by 20 m benches is generally questionable. These conclusions may serve as a useful guide for those who advocate open pit mining by high benches.

Jan 1, 1995

By A Kyllo a, D R. Swinbourne

Electric arc furnace (EAF) dusts contain significant quantities of zinc, found almost entirely as either zinc oxide or zinc ferrite. The dust has been classified as a hazardous waste due to the relative high lead, cadmium and hexavalent chromium contents. It is important that environmentally acceptable processes be developed to treat this waste. One possible process involves reacting the zinc compounds in the dust with metallic iron, thus avoiding zinc vapour reoxidation by CO2 as occurs in carbon reduction processes. It consists of two stages where the first is the reduction of iron oxides to iron and the second the reduction of zinc oxide to zinc vapour by the iron. In this work the effects of operating variables such as temperature, CO/CO2 ratio and pressure on the recovery of zinc from an industrial EAF dust obtained from the Smorgon Steel Mill were investigated. Zinc recoveries in the second stage were found to approach 100 per cent at 1000oC after about four hours in nitrogen but within 40 minutes if a low vacuum was used.

Jan 1, 2000