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Solution transport of gold and silver has occurred as a result of the chemical weathering of many Western Australian epigenetic gold deposits. Evidence for the remobilization of gold exists in the form of small crystalline octahedra, mustard gold, flake gold, and coatings on iron-oxide. This "secondary" gold is of high purity (low silver content). It is believed that the high chloride content of laterite profiles combined with the acid produced by the oxidation and hydrolysis (ferrolysis) of iron has caused dissolution of Au/Ag and Au/Te alloys. Gold, and less frequently silver, is subsequently reprecipitated in the profile nearby.Pyrite, which is a ubiquitous accessory of gold in vein or lode systems, is probably an important source of iron for the development of acidity. Where carbonate is abundant in the primary assemblage, neutralization directs the oxidation of sulphide to a path which produces thiosulphate, and an alternative type of Au/Ag oxidation process. Sulphide/carbonate ratios in the vein system, and adjacent wallrock are seen as important in determining the course and extent of remobilization in the oxidized zone of gold deposits.

Jan 1, 1984

By Slechta JJ

The performance of a hydrocyclone treating fine coal has been examined over a wide range of feed and operating conditions.The results were expressed in terms of partition curves from which the water split to the oversize flowstream,the corrected separation size and reduced partition curves were determined-.The following conclusions were obtained. (a) The water split to the oversize flowstream was found to be dependent upon the vortex finder and spigot diameters of the cyclone and the flowrate and solids content of the feed slurry. (b) The corrected separation size was dependent on the solids content of the feed,and the vortex finder and spigot diameters.The hydraulic pressure (or flowrate) of the feed slurry did not have a significant effect.This phenomenon could be explained in terms of crowding of the particles at the Spigot.

Jan 1, 1984

By Ghiani M, Currelli L, Fuganti A

the results of an experimental study aimed at beneficiating a complex ore containing bastnaesite and other rare-earth minerals, with associated barite and fluospar are illustrated. Owing to its minero-petrographic, physico-mechanical and structural characteristics, the crude ore is not amenable to classic concentration methods, such as flotation, magnetic and gravity separation. Therefore the technical feasibility of selective disintegration followed by size classification has been studied, whereby bastnaesite and the other rare-earth minerals can be concentrated into the finest size fractions. Leaching and subsequent extraction of rare-earth metals by liquid-liquid separation represents the final stage of beneficiation.

Jan 1, 1993

By Tarrant GC

Cement and resin encapsulated tendons are widely used in the stabilisation of mine roadways. One of the main factors in controlling the efficiency of the reinforcement is the ability of the tendon to generate load in response to rock deformation. The analysis of field data from instrumented reinforcing tendons complimented with extensive laboratory investigations have more accurately defined the mechanisms by which load generation occurs. The role of reinforcing tendon profiles, hole geometry and encapsulation medium properties in controlling the reinforcement stiffness and capacity are discussed. The results of the investigation have implications in both the design of rock reinforcing systems and the optimisation of encapsulation mediums and tendons.

Jan 1, 1992

By Lawson F

The Australasian Institute of Mining and Metallurgy is a society of engineers and scientists formed in 1893 (incorporated by Royal Charter in 1955) to advance science and engineering in the mineral industries, and to facilitate the exchange of information and ideas to enhance the professional excellence of its members. The Institute has several grades of members. The professional members are linked with Student and Company Members, as well as an Affiliate grade covering other professionals and non-professionals with experience in the mineral industry. The diverse group covers all sections of the mineral industry, from exploration through production to marketing of minerals and petroleum. Corporate (professional) membership also covers science and engineering professionals from specialisms other than the "traditional" ones in geosciences, mining and petroleum engineering and metallurgy. The Institute has Branches throughout Australia, New Zealand, Papua New Guinea and Oceania, whose activities complement the corporate occasions arranged for the benefit of all members by Headquarters in Melbourne. Members are drawn from all sections of the industry - private enterprise, government, research, education, and the support sector, including consultancies, manufacturers and suppliers. Membership of The Institute allows professionals to contribute to their profession through participation in The Institute's seminars and conferences, its many committees and Branch meetings, and through contribution to its many high standard publications. The Institute is the main body for the accreditation of professionals in the minerals industry. The activities of The Institute are directed towards the achievement of professional excellence. It provides opportunitites for contact with, and professional support from, colleagues, and the interchange of information on the latest industry developments.

Jan 1, 1989

By Matsuo T, Uga Y

The tunnelling work to construct a sewage trunk line designed by the Sewage Bureau of Kobe City along north side slope of Rokko mountain range incorporated an all ground condition type (broad spectrum) TBM with slurry transport system with jet pump manufactured by Kawasaki Heavy Industries, Ltd. Boring dia. of the tunnel measured to 2.0 m. The construction planning and implemen- tation were done by Ohbayashi Corporation, the general contractor. The heading way was 3342.4 m in overall length.; construction work ran from April '84 to June '85. The max. daily progress marked 31.9 m and the max. monthly progress 493.1 m according to the relevant record. The machine proceeded with the work under geological conditions featured with conglomerate, rhyolite, tuff breccia and slate, whereby soft soil zone mostly of clay was encountered in a limited area. In the latter case, however, steel segments were substituted for supporting steel ribs. The tunnel was routed beneath a meandering road with the result that more than 40% of overall length show a curvature of 50 to 200 m radius.

Jan 1, 1987

This paper deals briefly with three of the more controversial aspects of the geology of the Mount Isa ore deposits namely the geologic structures, the method of ore deposition and the origin of the ore.In the section on geologic structures, an outline is first given of the purely tectonic deformation advocated by the early authors. The current interpretation, which differs in the proposed order of events and causal forces, is then discussed. Other concepts, which attribute all or part of the deformation to sedimentary features or preconsolidation movement, are outlined ilnd commented on.The remaining two sections deal mainly with the better known lead-zinc orebodies. In the first of these a brief description and criticism is given of the early interpretation which was based on the deposition of successive waves of mineralisation which replacedindividual beds in the shales. The current ideas, which visualise emplacement of the ore between the beds rather than replacement of them, is then discussed. The final section develops the case for a sedimentary origin of the lead-zinc ores and broadly outlines the author's ideas concerning the evolution of the Mount Isa ore deposits.INTRODUCTIONAny consideration of the geology of Mount Isa must begin with the work of Blanchard and continue with that of Hall. Individually, or as co-authors, they published various papers on the geology of Mount Isa. Of these, the best known is their "Rock Deformation and Mineralisation at Mount Isa" (1941) which gave a comprehensive account of all aspects of Mount Isa geology.It is necessary to appreciate the limits set on geological knowledge of the mine and environs in 1941 by the extent of mine development and regional geologic studies. Underground, 7 level (897 ft.) was the lowest producing level. Development on 8 (1073 ft.) and 9 (1247 ft.) levels consisted only of exploratory drives and crosscuts in the vicinity of the Davidson Shaft. The tops of the 650 and 750...

Jan 1, 1961

The seam gas content at Westcliff Colliery is 12-15m3/tonne of coal.Composition ranges from 99% CH4 to 52% C02 in one area. Desorption rates are proportional to gas contents and CH4 is preferentially desorbed. A crushed zone of reduced permeability advances with the face - at Westcliff ribside crushed zones are 2.5 to 6.5m wide. Poor strata control widens crushed zones. 12 months of pre-drainage allowed 2 heading development and longer pillars to be used in a virgin area instead of 3 or more headings without drainage. Machined coal may lose as much as 1.6m3/tonne being conveyed out of Westcliff Colliery. Experience differs from mine to mine. Permeation is affected by time, strata movements, changing water content, and changing stress. Permeabilities vary from lOmd for Pittsburgh Seam to less than 1 and for the Bulli Seam. All these data and differences await further investigation.

Jan 1, 1982

Increasing demands on quality of metallurgical grade alumina and for lower production costs led to the development of a new fluid bed calcining process. The process, jointly developed in Germany by Vereinigte Aluminium Werke A.G. and Lurgi Gesellschaften m.b.H., takes advantage of modern chemical engineering methods such as counter-current flow of combustion air and solids, direct heat-exchange between combustion air and fine solids and near stoichiometric combustion of oil in a fluid bed. Using a two-stage Venturi-type suspension preheater for heat-recovery from combustion flue- gases, the circulating fluid bed technique with internal oil combustion at 2.2000 F for the calcining step and 'a five-stage fluidized bed cooler for heat recovery from calcines, the process gives an outstanding heat- efficiency. In a first industrial plant for 560 sh. t. alumina per day heat consumption figures of less than 1.400 BTU/lb A12O3 were achieved.

Jan 1, 1971

Introduction The mine winder is an essential element in the mining of ore in deep level mines and therefore requires a high degree of reliability to avoid interruption of production. Failure of any component on a winder may also be dangerous and expensive to repair. The larger the failure the larger the stoppage. The failure of a winder drum is the ultimate catastrophe, not only because of the cost of replacement, but also because of the lead time in procuring a new drum. Today these types of failure are not as common but many failures have occurred in the past and even today many an old winder is con- sidered for a new and often more arduous duty. As far back as the turn of the century a lot of information had been gathered to try and clear up the complexities of the multi- layering effect of coiling rope under tension onto a drum. Before comparing results obtained by various researchers the nature of the pressure distribution between rope and drum due to multi-layering will be discussed briefly.

Jan 1, 1987

By Evans A. F

Arising out of the increasing demands for efficiency in modern ore-dressing operations has grown a requirement for fuller knowledge of the characteristics of the ore treated. In part, this is being met by improved methods of study of the mode of occurrence of the constituent minerals, and of the intricacies of their physical relationships.A typical instance of the need for such a study is the presence of some undesired mineral in a flotation concentrate or tailing, which may be due either to mechanical association through insufficient grinding, or to incomplete separation in the flotation operation.Again, with modern practice in fine grinding, which often requires that from 70% upwards of the ground ore shall pass a 200-mesh screen, it is obviously impossible to obtain data on comparative grinding efficiencies, for instance, unless there is adequate knowledge of the size-composition of the material passing the finest available screen.Studies like these can be made satisfactorily only after size-separation (which may be carried out conveniently by elutriation) and by actual visual examination with the aid of a microscope, and the minute size of the mineral grains to be examined has necessitated the development of a new technique of sizing and microscopic examination.

Jan 1, 1932

Ferromanganese metasediments in the immediate vicinity of the Mid-Proterozoic Broken Hill Pb-Zn-Ag lodes, have undergone high grade (upper amphibolite facies) metamorphism,to form Mn-pyroxenoid (rhodonite,pyroxmangite) and garnet-rich lithologies. Such lithologies bear compositional (bulk rock,rare earth element)and morphological similarities to recent and ancient ferromanganese hydrothermal sediments of the Pacific.The non-metasomatic,stratiform garnetites are predominantly composed of magnesia-rich, calcium-poor almandine spessartine and quartz, which possess a bulk chemistry comparable to alumina-rich ferrommanganese oxide deposits of the Pacific. Such sediments are attributed to a mixed protolith comprised of clay and ferro-manganese oxides (mainly amorphous goethite with lesser todorockite-birnessite). Manganiferous pyroxenoid rocks are probably derived from alumina-poor ferromanganese cherts,similar to Japanese tetsusekiei.Rare earth element compositions ofBroken Hill garnetites are very similar to those of recent ferromanganese seafloor accumulations, suggestive of some genetic link.

Jan 1, 1990

By Mandzic E. H

The Dome Mine of Timmins Mining company is located in South Porcupine, N.W. Ontario. The orebody being mined partially lies in the No. 3 shaft pillar. Stability analysis has been carried out to establish the influence of nearby mining on ground movement in the shaft vicinity. Mathematical modelling of shaft displacement has been done for stope layout at depths from 180-210 m and distances of 10-50 m from the shaft. Analysis indicated that ground displacement around the shaft is below 1 mm/m and one third less for cut and fill than in the case of open stope mining. The result of the investigation was later confirmed by cut and fill mining of this orebody.

Jan 1, 1986

Opinions vary widely within the community on what are legitimate environmental social respon- sibilities. The extreme conservationists see the responsibility as the total preservation of the natural environment achieved by opposition to all forms of industrial development that would disturb it. The `growth-at-any-price men' consider it more important to stimulate economic growth, develop new industries, and maximize profit letting the environment take care of itself: within this wide spectrum of concern are the middle-of- the-road men, part of the vast majority, fully aware of the need to compromise to achieve a satisfactory economic growth rate whilst pre- serving to the greatest extent practicable the con- ditions upon which we depend for a balanced self-perpetuating existence. Environmental change is not new. It is the inevitable accompaniment of human activity. Plato wrote in the 5th Century B.C.* of the devastating changes wrought by man and his animals on the ancient world of the Mediter- ranean. Down through the ages rural development to *The Dialogues of Plato: `What are now her moun- tains were lofty, soil-clad hills; her so-called shingle plains of the present day were full of rich soil; and her mountains were heavily afforested-a fact of which there are still visible traces. There are moun- tains in Attica which can now keep nothing but bees, but which were clothed, not so very long ago, with fine trees producing timber suitable for roofing the largest buildings; and roofs hewn from the timber are still in existence. There were also many lofty cultivated trees, while the country produced bound- less pasture for cattle. The annual rainfall was not lost, as it is at present, through being allowed to flow over the denuded surface into the sea, but was received by the country, in all its abundance, into her bosom, where she stored it in her impervious potter's earth and so was able to discharge the drain- age of the heights into the hollows in the form of perennial springs and rivers throughout the land.' provide the necessities of life for expanding populations has required the destruction of vast areas of forest. Industrial activities over the last 200 years have discharged enormous quantities of solid wastes, liquid and gaseous effluents that were environmental pollutants of the worst kind. Urbanization has drawn people, their machines, and industries into vast concentrations aggregat- ing the environmentally bad effects of each to the extent that there is evidence that through thermal pollution these large urban industrial complexes nrp nffPrtina raainnnl rlimnta.c

Jan 1, 1978

Drum winders have now been built to attain depths of 3000 m and more in a single lift in accordance with the South African Code of Practice SABS 0294, which was introduced at the time of the last hoisting conference in 2000. Since then, this code has not only been followed for several winders in South Africa but was also followed in deep mines in Canada. Design of winders and their braking systems are described in the paper. Koepe winders are in use for high payloads of up to 50 t and to hoisting depths of around 2100 m. As known, the stress range of the hoisting ropes is the key parameter for rope fatigue. However, as per the SABS Code of Practice 0294, relying on static design is not the answer to the question of where the limits are for Koepe installation. The paper describes factors that are recognised to have influence in rope life and suggests definition of new design criteria for friction winders in order to get viable solutions for high-capacity hoisting from deep mines similar to drum hoisting.

Jan 1, 2005

Results from current NERDDC funded research into the geotechnology of highwall trench mining methods have clear implications for mine planners in the areas of blast design, trench shape, location of the surcharge spoil and remnant coal pillar design.Adoption of successful smooth wall blasting techniques not only removes safety hazards from the trench face, but limits development of bedding partings at the seam contacts that interrupt the smooth transition of stress across the coal seam.

Jan 1, 1992

Solar Salt, Lunar Ambitions I Bauerti The title of this paper is `Solar Salt, Lunar Ambitions'. It is largely the result of a lack of imagination and a tight deadline. I was seeking a catchy title to convey the image of being 'here' and wanting to get `there', with `there' being a long way away and our being held 'here' by powerful gravitational forces. I tried `Solar Salt, Lunar Landings', but that implied we had already reached `there' when, on reflection, we had not. A colleague suggested 'Solar Salt, Luna Park' which is a fun park in Sydney and, I must admit, there was appeal in the image of having embarked on a wild roller coaster ride with stomach-wrenching twists and turns and the only reward being a pair of sweaty palms, and a feeling of nausea. That's sometimes how it feels when you launch into change. In the end I settled for the more sedate `Lunar Ambitions'. It contained that suggestion of hope and continual striving which are central to the idea of best practice. I will discuss our experiences in this area shortly, but I would firstly like to provide some background to our business. The salt industry is steeped in history and tradition. As one learned commentator observed, common salt is 'a substance seemingly too ordinary to think about, yet it is the oldest of man's raw materials and the basis of some of his newest inventions' (Multhauf, 1978). From ancient times, salt was recognised as a key necessity of life and it has played a role in the rise and fall of governments throughout history. The Romans recognised its importance when they gave their soldiers money regularly to purchase salt, hence our modern word 'salary'. Today, while culinary use remains important, the main consumer of salt is the chemical industry (Figure 1).

Jan 1, 1995

By C F. Nichol, L Smith, R D. Beckie

A better understanding of the hydrogeology within mine waste rock and cover systems is essential for the quantification, prediction and prevention of metals loading to the environment surrounding waste rock piles. The effect of surface condition on the internal flow mechanisms within an intermediate-scale constructed waste rock pile is being investigated at the Cluff Lake Mine, Saskatchewan. Changes in the water balance, the outflow distribution and water residence time have been observed in the waste rock pile following successive modifications of the surface condition. The three year old, run of mine, free-dumped surface was ripped to a depth of 30 cm to 40 cm, and levelled in October of 2001. In August 2002, a 10 cm to 15 cm cover of compacted waste rock was placed on the pile. Outflow, precipitation and run-off data collected during natural and artificial rainfall events have been used to quantify the maximum infiltration rate, and the spatial pattern of discharge and cumulative volume of water that infiltrated into the waste rock under each surface condition. Infiltration data together with the outflow data provide a basis to address the residence time of water within waste rock and the dominant flow mechanisms for different surface conditions. With a free dump surface spatially distinct wetting fronts are observed at the base of the pile that vary in flow rate by an order of magnitude (measured at a 2 m by 2 m scale) and in time by up to a week. Following ripping and levelling, similar cumulative outflows were observed, but the magnitude and arrival time of wetting fronts changed across the pile. A decrease in outflow volume, a decrease in infiltration volume, a two-fold increase in the response time of wetting fronts and a more spatially uniform distribution was observed following placement of the compacted surface layer. Based on preliminary data, the internal structure appears to be the dominant factor controlling outflow variability.

Jan 1, 2003

By C Kusi-Manu, E Nyamusika

Geita Gold Mining Limited (GGML) is owned and jointly managed by Ashanti Goldfields Company (Ghana) and Anglogold (South Africa). The mine is currently one of the largest gold producing open pit operations in Africa producing 620 000 ounces of gold and mining in excess of 70 000 000 tonnes of material per annum. The mine currently has 2000 full time employeeÆs and a mine life in excess of 12 years. Geita Gold Mine is comprised of 11 different gold deposits situated in the Lake Victoria Goldfields of North Western Tanzania (Figure 1). The gold deposits are primarily associated with banded ironstone formations within an Archaean greenstone belt. Current global resources, including Inferred, stand at 129.5 million tonnes grading 3.91 g/t (16.2 M oz). Open pit reserves total 70.4 million tonnes grading 4.16 g/t (9.4 M oz). The majority of the gold resource is hosted by the three deposits (Nyankanga, Lone Cone and Geita Hill) within the æGeita TrendÆ a large and continuous (>4 km long) mineralised zone (Adofo, 2002). Geita Gold Mine commenced operations in June 2000, as the second large-scale open pit gold mine in Tanzania. The new workforce of 800 people had no previous experience in open pit gold mining. Since the start of the operation, Geita Gold MineÆs management ambition was to become a world leader in the application of best practice in all technical disciplines and in operational success. Staff development and training was identified as one of the major components in the company achieving its aim. Geita Gold MineÆs management has committed the necessary training staff, resources and the commitment of over $US 1 M a year to staff training and development programs for 2003 and 2004. The process and management of Geita Gold MineÆs mining geology staff training and development program is presented in this paper.

Jan 1, 2003

By Jiang G

The Chinese Central Government attaches great importance to the development of its coal industry. Besides carrying out the policy of simultaneous development of large, medium and small coalmines,the main strategy is to gradually modernize coal mining areas and coalmines and to increase the output from individual coalfaces. There are particular implications, processes and main experiences of coalmine modernisation in China.Ensuring a coal output of over one M tonne/yr from one coalface is a very complicated system-engineering project which deals with a wide range of problems. The most important measure used for achieving an output of over one M tonne/yr from a single coalface is the analysis of affecting factors on coalface production by means of the theory c reliability. Thus, as far as possible , the production stoppages caused by mechanical equipment failures and other factors are avoided, the equipment recovery rate is increased and the working hours of shearers are extended so as to ensure a high output and high efficiency.

Jan 1, 1991